WO2010137352A1 - Method and apparatus for thermally decomposing polymer waste, method for collecting carbide, carbide, rubber composition containing the carbide, and tire using the rubber composition - Google Patents

Abstract

Disclosed is a method for thermally decomposing polymer waste, wherein oxidation of carbides that remain after the thermal decomposition of the polymer waste can be suppressed. Specifically disclosed is a method for thermally decomposing polymer waste, which comprises: a step in which an oxygen-free gas is heated within a heat exchanger (1); and a step in which the heated oxygen-free gas is introduced into a thermal decomposition furnace (3) in which polymer waste (2) is contained, so that the polymer waste (2) and the oxygen-free gas are brought into direct contact with each other, thereby generating a thermal decomposition gas. The method for thermally decomposing polymer waste is characterized in that the gas flow rate of the oxygen-free gas to be introduced into the thermal decomposition furnace (3) is controlled within the range from 0.0015 m³/s [ntp] to 0.0095 m³/s [ntp].

Description

Thermal decomposition method and thermal decomposition apparatus for polymer waste, recovery method of carbide, carbide, rubber composition containing the carbide, and tire using the rubber composition

The present invention includes a thermal decomposition method and thermal decomposition apparatus for polymer waste, a method for recovering carbide from the polymer waste, a carbide obtained from the thermal decomposition method or the recovery method, and a mixture of the carbide. The present invention relates to a rubber composition and a tire using the rubber composition, and more particularly, to a thermal decomposition method for a polymeric waste that can suppress oxidation of carbides remaining after thermal decomposition of the polymeric waste. .

Conventionally, various polymer materials such as rubber materials and resin materials have been industrialized for the purpose of developing functional materials. On the other hand, the development of the polymer industry has led to mass production of general-purpose materials, Consuming and the treatment of polymer waste is a problem to be solved. In order to solve this problem, it is important to recycle and recycle polymer materials. For example, a tire made of a rubber material is mass-produced and consumed as a general-purpose material, and the number of used tires is large. Therefore, research on recycling of used tires is underway.

In Japanese Patent Application Laid-Open No. 2004-277687 (Patent Document 1), carbide obtained by dry distillation treatment of a waste tire is finely pulverized and heated to 500 ° C. or higher in a sealed container to be crystallized, and added to the tire. It can be recycled as an agent. However, it is well known that carbide is graphitized by high-temperature treatment, and the electron microscopic image described in JP-A-2004-277687 is judged to be a graphitized fine powder instead of carbon black. it can. Therefore, it is clear that the carbide described in JP-A-2004-277687 is not suitable as a rubber compounding agent.

Japanese Patent Application Laid-Open No. 2006-349224 (Patent Document 2) reports that a waste tire is preheated by microwave irradiation, pyrolyzed in a kiln type furnace, and the resulting carbide can be used as activated carbon. . However, there is no description that the carbide can be used as a compounding agent for rubber, and further, air can flow into the heating furnace relatively easily from the structure of the heating furnace described in JP-A-2006-349224. It seems that it can be used as activated carbon because the carbides are oxidized and become porous. Therefore, it is clear that the carbide described in JP-A-2006-349224 is not suitable as a rubber compounding agent.

Japanese Patent Application Laid-Open No. 2007-70167 (Patent Document 3) reports that glassy carbon can be obtained by heating a waste tire at 500 to 560 ° C. for 2 to 3 hours in a rotary dry distillation furnace. However, since the glassy carbon has almost no interaction with the rubber component, it is not suitable as a compounding agent for rubber.

In WO 2007/121166 (Patent Document 4), the tire is pyrolyzed at 350 ° F. (177 ° C.) to 850 ° F. (566 ° C.) for the purpose of recycling carbon black from the used tire, and then obtained. A method of removing volatile matter by heating at 900 ° F. (482 ° C.) to 1200 ° F. (648 ° C.) when the generated carbide is raised through a pipe into which air is introduced with a screw, and an apparatus thereof It has been reported. However, since air is introduced into the tube and the heating temperature is high, there is a possibility that the carbon black whose surface has been oxidized may be recovered, which is not suitable as a rubber compounding agent.

As described above, when carbon black having an oxidized surface is blended with a rubber composition, the tensile stress and strength of the rubber composition are significantly reduced, and therefore the carbon black may be unsuitable as a rubber compounding agent. Widely known. It is also widely known that graphitization proceeds when carbon black is subjected to a high temperature and a long thermal history, and when it is blended with a rubber composition, the tensile stress and strength are similarly significantly reduced.

On the other hand, in US Pat. No. 5,037,628 (Patent Document 5), a method in which carbide obtained by pyrolyzing scrap rubber is pulverized under mild pulverization conditions, and aggregated particles containing carbon black are separated using an air classifier. Has been reported. Here, the compatibility of the separated carbon black with the rubber material is greatly affected by the thermal decomposition conditions. However, in US Pat. No. 5,037,628, there is no description regarding thermal decomposition, and the compounding agent for rubber It is impossible to judge whether or not it is appropriate.

Recently, as an oiling facility for recovering components that can be used as useful substances from polymer waste, a heat exchanger for heating oxygen-free gas, a pyrolysis furnace containing polymer waste inside, A pyrolysis apparatus having an external heating means for heating the pyrolysis furnace from the outside, an oil content recovery apparatus for recovering condensed oil by cooling the pyrolysis gas generated in the pyrolysis apparatus, and the oil recovery There has been reported a circulation type oil making facility provided with a circulation path for circulating the residual gas after the oil is recovered by an apparatus as an oxygen-free gas to the heat exchanger (Japanese Patent Laid-Open No. 2008-285523). (See Patent Document 6). However, no attempt has been made to optimize the pyrolysis conditions from the viewpoint of recovering the pyrolyzed carbide as a suitable rubber compounding agent.

JP 2004-277687 A JP 2006-349224 A JP 2007-70167 A International Publication No. 2007/121166 US Pat. No. 5,037,628 JP 2008-285523 A

Therefore, an object of the present invention is to provide a thermal decomposition method and thermal decomposition apparatus for polymer waste that can solve the above-described problems of the prior art and can suppress oxidation of carbides remaining after thermal decomposition of the polymer waste. It is to provide. Another object of the present invention is to provide a recovery method capable of obtaining a pyrolytic recovery carbide that can maintain rubber characteristics sufficiently even when blended with a rubber component without deterioration in quality. Still another object of the present invention is to provide a carbide obtained by the above pyrolysis method or recovery method, a rubber composition obtained by blending the carbide, and a tire using the rubber composition.

As a result of intensive investigations to achieve the above object, the inventors of the present invention brought a polymer waste directly into contact with a heated oxygen-free gas to generate a pyrolysis gas. by controlling the gas flow rate of oxygen-free gas introduced in the range of ^{0.0015m 3 /s[ntp]~0.0095m 3 / s [ntp} ], oxidation of the carbide remaining in the pyrolysis furnace after pyrolysis The inventors have found that it can be suppressed, and have completed the present invention.

That is, the thermal decomposition method for polymer waste according to the present invention includes:
Heating the oxygen-free gas in the heat exchanger;
Introducing a heated oxygen-free gas into a pyrolysis furnace containing the polymer waste, bringing the polymer waste into direct contact with the oxygen-free gas, and generating a pyrolysis gas. In the thermal decomposition method of polymer waste,
And controlling the gas flow rate of oxygen-free gas to be introduced into the pyrolysis furnace in the range of ^{0.0015m 3 /s[ntp]~0.0095m 3 / s [ntp} ].

“Gas flow rate” refers to the flow rate of gas sent per 100 kg of polymer waste. Ntp means a reference state, and is expressed on the basis of a volume at a gas flow rate of 0 ° C. and 1 atm.

In the thermal decomposition method for polymer waste according to the present invention, it is preferable to control the temperature during thermal decomposition to 300 to 600 ° C. in the step of generating the thermal decomposition gas. In this case, oxidation of the carbide remaining after the thermal decomposition can be more reliably suppressed.

In the thermal decomposition method for polymer waste according to the present invention, the oxygen concentration in the oxygen-free gas is preferably controlled to 1% by volume or less. In this case, oxidation of the carbide remaining after the thermal decomposition can be more reliably suppressed.

The pyrolysis apparatus used in the thermal decomposition method for polymer waste according to the present invention includes a pyrolysis furnace that contains polymer waste therein, and an external heating means that heats the pyrolysis furnace from the outside. It is preferable that the oxygen concentration in the thermal decomposition apparatus is 1% by volume or less.

Further, the method for recovering the carbide of the present invention includes:
Heating the oxygen-free gas in the heat exchanger;
Introducing a heated oxygen-free gas into a pyrolysis furnace containing a polymer waste, bringing the polymer waste into direct contact with the oxygen-free gas, and generating a pyrolysis gas;
In the method for recovering carbide, the method includes cooling the pyrolysis gas and recovering the condensed oil, and recovering carbide remaining in the pyrolysis furnace after the thermal decomposition of the polymer waste.
And controlling the gas flow rate of oxygen-free gas to be introduced into the pyrolysis furnace in the range of ^{0.0015m 3 /s[ntp]~0.0095m 3 / s [ntp} ].

This “carbide” refers to a solid that is generated and left after a gas body and liquid components in the raw material are released by a thermal decomposition reaction by heating using a substance containing organic matter as a raw material. May be included.

In the method for recovering carbide according to the present invention, it is preferable to control the temperature during pyrolysis to 300 to 600 ° C. in the step of generating the pyrolysis gas. In this case, a carbide capable of sufficiently maintaining rubber characteristics even when blended with a rubber component can be more reliably obtained without deteriorating the quality of the carbide.

In the carbide recovery method of the present invention, it is preferable to control the oxygen concentration in the oxygen-free gas to 1% by volume or less. In this case, a carbide capable of sufficiently maintaining rubber characteristics even when blended with a rubber component can be more reliably obtained without deteriorating the quality of the carbide.

The pyrolysis apparatus used in the method for recovering carbide according to the present invention is:
A heat exchanger for heating anoxic gas;
It has a pyrolysis furnace containing polymer waste inside and an external heating means for heating the pyrolysis furnace from outside, and the polymer waste is in direct contact with oxygen-free gas heated by the heat exchanger. A decomposition device for generating pyrolysis gas by pyrolyzing by,
An oil recovery device for recovering the condensed oil by cooling the pyrolysis gas generated in the decomposition device;
A circulation path for supplying the residual gas after the oil is recovered by the oil recovery device to the heat exchanger as an oxygen-free gas;
A gas generator for generating an inert gas to be introduced into the pyrolysis furnace;
An oxygen concentration detector for detecting the oxygen concentration in the thermal decomposition apparatus system.

Furthermore, the carbide of the present invention is characterized in that it is a carbide obtained by the above pyrolysis method or recovery method, and its total acidity is preferably 0.1 meq / g or less, and further, a pulverization step and a classification step Of these, fine carbide obtained through at least one of the steps is more preferable. Furthermore, the rubber composition of the present invention is characterized by blending the carbide, and the tire of the present invention is characterized by using the rubber composition.

According to the present invention, the polymer waste in the thermal decomposition method for polymer waste is directly introduced into the pyrolysis furnace in the step of bringing the polymer waste into direct contact with the heated oxygen-free gas to generate the pyrolysis gas. by controlling the gas flow rate that oxygen free gas within the ^{0.0015m 3 /s[ntp]~0.0095m 3 / s [ntp} ], remain in the pyrolysis furnace after pyrolysis of polymer waste Oxidation of carbide can be suppressed. In addition, by suppressing the oxidation of the carbide remaining in the pyrolysis furnace after the thermal decomposition of the polymer waste, it is possible to obtain a carbide that can maintain the rubber characteristics sufficiently even when blended with the rubber component without deteriorating the quality. A possible recovery method can be provided. Furthermore, the carbide | carbonized_material obtained by the said thermal decomposition method or the collection | recovery method, the rubber composition formed by mix | blending this carbide | carbonized_material, and the tire using this rubber composition can be provided.

It is the schematic of an example which shows the thermal decomposition apparatus of the polymer waste suitable for implementation of this invention. It is a figure which shows the relationship between the gas flow rate of an oxygen-free gas, and total acidity. It is a figure which shows the relationship between the rubber characteristic of a rubber composition, and total acidity. It is a figure which shows the relationship between the oxygen concentration in a thermal decomposition apparatus system, and total acidity.

Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic diagram of a polymer waste pyrolysis apparatus used in the polymer waste pyrolysis method of the present invention and the carbide recovery method of the present invention. In the thermal decomposition method and the recovery method of the present invention, first, the oxygen-free gas is heated in the heat exchanger 1. By supplying the oxygen-free gas heated by the heat exchanger 1 to the pyrolysis furnace 3, the polymer waste in the pyrolysis furnace 3 is pyrolyzed. Here, the oxygen-free gas is a gas body other than oxygen and oxide, and examples thereof include inert gases such as nitrogen, argon and helium, and combustible gases such as hydrogen, methane and propane. By using oxygen gas, it is possible to prevent oxidation of carbides remaining in the pyrolysis furnace 3 after pyrolysis of polymer waste. In the thermal decomposition method and recovery method of the present invention, the heat exchanger 1 is not particularly limited, but a spiral heat exchanger, a plate heat exchanger, or the like can be used. Further, in order to supply the oxygen-free gas to the heat exchanger 1, in addition to being sent from the non-circulating gas generator 7, there is no residual gas after being recovered by the oil recovery device 9 via the circulation path 6 described later. You may circulate to the heat exchanger 1 as oxygen gas.

Next, in the thermal decomposition method and the recovery method of the present invention, a heated oxygen-free gas is introduced into a thermal decomposition furnace 3 containing the polymer waste 2 to remove the polymer waste 2 from the waste. Directly contact with oxygen gas to generate pyrolysis gas. By bringing the polymer waste 2 into direct contact with the oxygen-free gas, thermal decomposition in an oxygen-free state becomes possible. The pyrolysis furnace 3 is not particularly limited, but a normal kettle type pyrolysis furnace, fluidized bed type pyrolysis furnace, kiln type pyrolysis furnace or the like is used. The polymer waste 2 mainly refers to organic waste. Specifically, rubber such as tires (for example, spew, buff powder, tires divided into 4 to 32), rubber hoses, tubes, conveyor belts, and the like. Examples include material waste and resin material waste such as polyethylene, polyethylene terephthalate, polyvinyl chloride, and nylon. Furthermore, the decomposition apparatus 5 used in the thermal decomposition method and the recovery method of the present invention includes an external heating means 4 that heats the thermal decomposition furnace 3 from the outside, in addition to the thermal decomposition furnace 3 that contains the polymer waste 2 inside. Is preferably provided. Since the cracking device 5 includes the external heating means 4, the polymer waste 2 in the pyrolysis furnace 3 can be indirectly heated from the outside of the pyrolysis furnace 3. It becomes possible to reduce. This suppresses the generation of solid dust (fine suspended matter derived from polymer waste) that is swollen from the pyrolysis furnace 3 and mixed in the gas and circulates in the apparatus together with the gas. Can also be suppressed. The external heating means 4 is not particularly limited, but for example, an external heating furnace disposed around the pyrolysis furnace 3 is preferable. In addition, the heating medium used for the external heating means 4 indirectly heats the polymer waste 2 from the outside of the pyrolysis furnace 3, so that it is not limited to oxygen-free gas but uses various substances. Can do.

Here, the present invention in the thermal cracking process and recovery process, the gas flow rate of 0.0015m ³ /s[ntp]~0.0095m ³ / s of oxygen-free gas to be introduced into the pyrolysis furnace 3 [ntp] It needs to be controlled within the range. The thermal decomposition method and the recovery method of the present invention are intended to suppress the oxidation of the carbide remaining in the thermal decomposition furnace 3 after the thermal decomposition and recover a carbide suitable as a rubber compound. An index for evaluating the degree of oxidation of carbides is “total acidity”. If this value is large, it means that the surface of the carbide is oxidized, and the carbide is not suitable as a compounding agent for rubber. Means. In the thermal decomposition method and the recovery method of the present invention, the flow rate of the oxygen-free gas is controlled within the specified range, and the thermal decomposition is performed under mild conditions, so that the total acidity of the subsequently recovered carbides is reduced. It can be suppressed to 0.1 meq / g or less. If the total acidity is 0.1 meq / g or less, when the recovered carbide is mixed with pure carbon black (100% carbon black), the physical properties of the rubber composition can be reduced within 5% and recovered. The carbide can be reused. In addition, if the flow rate of the oxygen-free gas introduced into the pyrolysis furnace 3 is less than 0.0015 m ³ / s [ntp], the movement of the pyrolysis gas generated by pyrolysis is delayed, so the efficiency of the pyrolysis reaction is increased. On the other hand, if it exceeds 0.0095m ³ / s [ntp], the contact between the heated oxygen-free gas and the polymer waste becomes excessive, and the generation of solid dust and oxides such as nitrogen oxides This is not preferable because it can occur.

Here, FIG. 2 is a diagram showing the relationship between the gas flow rate of the oxygen-free gas and the total acidity, and FIG. 3 is a diagram showing the relationship between the rubber properties of the rubber composition and the total acidity. The vertical axis in FIG. 3 represents the recovered carbide 20 obtained by the thermal decomposition method or recovery method of the present invention when the rubber composition containing only GPF grade carbon black is expressed as an index with the tensile stress at 300% elongation as 100. The index value of the tensile stress at 300% elongation of a rubber composition containing a mixture of mass% and GPF grade carbon black 80 mass% is shown, and the horizontal axis in FIG. 3 represents the total acidity of the recovered carbide used in the rubber composition Degrees. Figures 2 and 3, the gas flow rate of oxygen-free gas to be introduced into the pyrolysis furnace 3 is desirably in the range of ^{0.003m 3 /s[ntp]~0.007m 3 / s [ntp} ]. The reason for this is that the pyrolysis reaction efficiency due to the movement of pyrolysis gas is maximized when the oxygen-free gas flow rate is around 0.003 m ³ / s [ntp], so the oxygen-free gas flow rate is 0.003 m ³ / s. [ntp] or more is preferable. On the other hand, when the gas flow rate of the oxygen-free gas is 0.007 m ³ / s [ntp] or less, the total acidity of the recovered carbide can be suppressed to 0.07 meq / g or less. This is because there is almost no decrease in physical properties when used in a rubber composition.

In addition, the measuring method of the said total acidity is as follows. First, 1 g of carbon black is precisely weighed, transferred to a flat bottom flask, added with 50 ml of 0.002N NaOH aqueous solution, and dispersed with ultrasonic waves. Then, a condenser tube is attached to the flat bottom flask and boiled for 2 hours while refluxing. The dispersion was cooled and solubilized, and a portion thereof was titrated with 0.002N NaOH aqueous solution, and the amount of NaOH used in the neutralization reaction per 1 g of carbon black was determined from the remaining amount of NaOH left unreacted. Ask. The unit is expressed in milliequivalents (meq / g) per unit mass.

Further, in the thermal decomposition method and the recovery method of the present invention, in order to control the gas flow rate of the oxygen-free gas introduced into the thermal decomposition furnace 3, the oxygen concentration detector 8 for measuring the oxygen concentration, Accordingly, the flow rate control means 13 for adjusting the gas flow rate, the blower 10 for keeping the gas flow rate constant, and the like can be used. For example, as shown in FIG. 1, in a pipe connecting the gas generator 7 and the heat exchanger 1 for supplying oxygen-free gas from the gas generator 7, an oxygen concentration detector 8, a flow control means 13 and An air blower 10 may be provided, or an oxygen concentration detector 8 and a flow rate control means 13 are provided in a circulation path 6 for circulating the residual gas recovered by the oil content recovery device 9 to the heat exchanger 1 as an oxygen-free gas. And a blower 10 may be provided.

In the pyrolysis method and the recovery method of the present invention, it is preferable to control the temperature at the time of pyrolysis to 300 to 600 ° C. in the step of generating pyrolysis gas from the polymer waste 2 and oxygen-free gas. If the temperature at the time of thermal decomposition is within the above specified range, the polymer waste can be stably and continuously decomposed. If the temperature during the pyrolysis is less than 300 ° C., the pyrolysis reaction does not proceed sufficiently, which may result in the formation of carbides in which the components to be decomposed are not completely removed. Undesirable reforming reactions and activation reactions occur between the generated carbides and the components that can be contained in the gas, increasing the total acidity in the carbides, or being porous and adversely affecting the reinforcing effect on the rubber. There is a risk of forming carbides that can be affected. Here, in order to control the temperature at the time of pyrolysis, the flow rate of the oxygen-free gas heated in the heat exchanger 1, the external heating means 4 for heating the pyrolysis furnace 3 from the outside, etc. are used. That's fine.

Next, in the recovery method of the present invention, the pyrolysis gas is cooled and the condensed oil is recovered. For this reason, in the thermal decomposition apparatus used for the recovery method of the present invention, one or more oil content recovery devices 9 are provided to cool the pyrolysis gas generated in the decomposition device 5 and recover the condensed oil content. Is preferred. As shown in FIG. 1, if a plurality of oil content recovery devices 9 are used, the pyrolysis gas generated in the cracking device 5 can be divided into oil content recovered in accordance with the boiling point thereof. Specifically, the first oil content recovery device 9a on the upstream side of the gas flow path and the second oil content recovery device 9b on the downstream side of the gas flow path are provided. The second oil recovery unit 9b on the downstream side of the gas flow path has the same configuration as the first oil recovery unit 9a, but is lower than the boiling point of the oil component targeted by the first oil recovery unit 9a. An oil having a boiling point in the region is recovered. In this way, by installing a plurality of oil content recovery devices 9, it is possible to recover an oil content having a constant composition and stable quality with a high recovery rate. Moreover, each oil content collection | recovery apparatus 9 is connected to the collection tank 10 through piping at the lower part, for example, and can collect | recover the collect | recovered oil content. Further, a condensing device or the like can be provided on the downstream side of the oil content recovery device 9, and the oil content condensed in the condensing device can be recovered.

Next, in the recovery method of the present invention, the carbide remaining in the pyrolysis furnace after the thermal decomposition of the polymer waste is recovered. For example, when pyrolyzed gas is generated and an oil component obtained by condensing the pyrolyzed gas is recovered, the pyrolyzed carbide remains in the pyrolysis furnace 3, so that the carbide can be recovered. Although the carbide is obtained by the above-described recovery method, generally, it is recovered as a lump, so for example, the carbide recovered by a pulverization process using a pulverizer or the like is finely crushed and further classified. A carbide having a specific particle size can be extracted by a classification process using the like.

In the thermal decomposition method and the recovery method of the present invention, the oxygen concentration is preferably controlled to 1% by volume or less. This means that the oxygen concentration in the thermal decomposition apparatus used in the thermal decomposition method and the recovery method of the present invention is controlled to 1% by volume or less. If the oxygen concentration in the pyrolysis apparatus is 1% by volume or less, oxidation of carbides remaining in the pyrolysis furnace after pyrolysis can be more reliably suppressed, quality does not deteriorate, and even if blended with a rubber component Carbide that can sufficiently maintain rubber properties can be obtained more reliably. The thermal decomposition apparatus used for the thermal decomposition method or the recovery method of the present invention includes, in addition to the above-described decomposition apparatus 5 and oil content recovery apparatus 9, in addition to these, the heat exchanger 1, the gas generator 7, the circulation path 6, oxygen A pyrolysis apparatus including the concentration detector 8, the flow rate control means 13, the blower 10, the recovery tank 10, the exhaust fan 11, the exhaust gas treatment device 12 and the like as appropriate is also included. The oxygen concentration in the thermal decomposition apparatus can be measured by, for example, a zirconia oxygen sensor using a solid electrolyte zirconia-based oxygen concentration cell. Here, FIG. 4 is a diagram showing the relationship between the oxygen concentration in the pyrolyzer system and the total acidity. From FIG. 4, in order to obtain the total acidity capable of obtaining high-quality carbides. It can be seen that the oxygen concentration in the thermal decomposition apparatus system is preferably 1.0% by volume or less.

Next, the thermal decomposition apparatus according to the present invention will be described with reference to FIG. The thermal decomposition apparatus shown in FIG. 1 includes a heat exchanger 1 for heating an oxygen-free gas, a thermal decomposition furnace 3 that contains a polymer waste 2 inside, and an external heating unit that heats the thermal decomposition furnace 3 from the outside. A decomposition apparatus 5 having heating means 4 for generating thermal decomposition gas by thermally decomposing the polymer waste 2 by directly contacting the oxygen-free gas heated by the heat exchanger 1; The pyrolysis gas generated in the cracking device 5 is cooled to recover the condensed oil component, and the residual gas after the oil component is recovered by the oil recovery device 9 is used as the oxygen free gas as the heat. A circulation path 6 for supplying to the exchanger 1, a gas generator 7 for generating oxygen-free gas introduced into the pyrolysis furnace 3, and oxygen for detecting the oxygen concentration in the pyrolysis apparatus system A concentration detector 8;

In the thermal decomposition apparatus of the present invention, the decomposition apparatus 5 includes a thermal decomposition furnace 3 that accommodates the polymer waste 2 inside and an external heating means 4 that heats the thermal decomposition furnace 3 from the outside. Here, the oxygen-free gas heated by the heat exchanger 1 is introduced into the pyrolysis furnace 3 containing the polymer-based waste 2, and the polymer-based waste 2 is brought into direct contact with the oxygen-free gas, Generate pyrolysis gas. By bringing the polymer waste 2 into direct contact with the oxygen-free gas, thermal decomposition in an oxygen-free state becomes possible. In addition, since the decomposition apparatus 5 includes the external heating means 4, the polymer waste 2 in the pyrolysis furnace 3 can be indirectly heated from the outside of the pyrolysis furnace 3. The gas flow rate can be reduced. This suppresses the generation of solid dust (fine suspended matter of polymer waste) that is swollen from the pyrolysis furnace 3 and mixed in the gas and circulates in the apparatus together with the gas. Occurrence can also be suppressed.

In the thermal decomposition apparatus of the present invention, the circulation path 6 supplies the residual gas after the oil content is recovered by the oil content recovery device 9 to the heat exchanger 1 as an oxygen-free gas. The exchanger 1 is connected by piping. The residual gas supplied to the heat exchanger 1 through the circulation path 6 can be directly supplied to the heat exchanger 1, but can also be supplied to the heat exchanger 1 after being heated in a hot stove (not shown). Good. In FIG. 1, the circulation path 6 is connected only to the second oil recovery unit 9b. However, the present invention is not limited to this, and the circulation path 6 is connected to the first oil recovery unit 9a. May be. In the thermal decomposition apparatus of the present invention, surplus gas can be released into the atmosphere after being treated by the exhaust gas treatment device 12 via the exhaust fan 11.

In order to control the oxygen concentration in the apparatus system to a certain value or less, the pyrolysis apparatus of the present invention has a gas generator 7 for generating an inert gas to be introduced into the pyrolysis furnace 3, and a pyrolysis apparatus system. And an oxygen concentration detector 8 for detecting the oxygen concentration. Here, by using the gas generator 7 and the oxygen concentration detector 8 together, the oxygen concentration in the pyrolysis apparatus system is monitored, and an inert gas is introduced into the pyrolysis furnace 3 according to the detection result. It becomes possible, the oxidation of the carbide | carbonized_material remaining in the thermal decomposition furnace 3 after thermal decomposition can be suppressed, and the carbide | carbonized_material suitable as a compound for rubber | gum can be collect | recovered.
In order to suppress the above total acidity to 0.1 meq / g or less, it is preferable to control the oxygen concentration in the thermal decomposition apparatus system to 1.0 volume% or less. Therefore, the thermal decomposition apparatus of the present invention further introduces an inert gas from the gas generator into the thermal decomposition apparatus system based on the oxygen concentration in the thermal decomposition apparatus system detected by the oxygen concentration detector 8. It is preferable to provide a device for controlling the flow rate. As a result, a signal is transmitted to the inert gas flow rate control means 13 based on the detection result of the oxygen concentration in the thermal decomposition system detected by the oxygen concentration detector 8, and the gas generator 7 is operated by this signal. An inert gas is generated, and this inert gas is introduced into the thermal decomposition system through the flow rate control means 13 whose opening degree is changed by the signal.

When the oxygen concentration detector 8 detects an oxygen concentration exceeding a preset reference value, the gas generator 7 for supplying an inert gas operates in conjunction with the detection result, and at the same time the flow rate Inert gas is introduced into the circulation path 6 by adjusting the opening of the control means 13. By introducing the inert gas, the oxygen concentration detected by the oxygen concentration detector 8 is lowered, and the oxygen concentration in the thermal decomposition apparatus system can be controlled to a reference value or less. Specifically, the gas generator 9 operates when the oxygen concentration in the thermal decomposition system detected by the oxygen concentration detector 8 exceeds 1.0 vol%, and at the same time, in the circulation path 6 via the flow rate control means 13. An inert gas is supplied to the gas, and the oxygen concentration in the thermal decomposition apparatus system is lowered. Next, when the oxygen concentration in the circulation path 6 is reduced to 0.2% by volume, a stop signal is issued to each device (the gas generator 7 and the flow rate control means 13), and the supply of the inert gas is stopped. Thereby, the oxygen concentration in the thermal decomposition apparatus system can be controlled to a reference value or less. When supplying an inert gas into the pyrolysis furnace 3, it is ideal to reduce the oxygen concentration to 0% by volume. However, from the viewpoint of the cost of supplying the inert gas, When the oxygen concentration is lowered to 0.2% by volume, it is preferable to stop the supply of the inert gas to the pyrolysis furnace 3. As the oxygen concentration detector 8, for example, a zirconia oxygen sensor using a solid electrolyte zirconia-based oxygen concentration cell is used. As the gas generator 7, for example, P.I. S. A nitrogen gas generator using the A (Pressure Swing Adsorption) method is used.

As shown in FIG. 1, the inert gas supplied by the gas generator 7 is introduced to the downstream side of the gas flow path from the oil content recovery device 9 and to the upstream side of the gas flow path from the heat exchanger 1. Is preferred. If the inert gas is introduced to the upstream side of the oil content recovery device 9, the temperature of the pyrolysis gas containing the oil content may be lowered, the oil content recovery efficiency may be reduced, or the piping may be blocked with oil. On the other hand, when the inert gas is introduced to the downstream side of the heat exchanger 1, the temperature of the hot gas for liquefying the polymer waste is lowered, and the thermal decomposition efficiency is lowered. Further, in the thermal decomposition apparatus of the present invention, it is preferable to install a flow rate control means 13 that works in conjunction with the oxygen concentration detector 8, whereby inert gas is introduced into the system by a detection signal from the oxygen concentration detector 8. Can be introduced.

Next, the carbide of the present invention will be described in detail. The carbide of the present invention is a carbide obtained by the above pyrolysis method or recovery method, and its total acidity is preferably 0.1 meq / g or less, more preferably 0.07 meq / g or less. If the total acidity of the carbide is 0.1 meq / g or less, as described above, the recovered carbide can be reused as a filler for rubber reinforcement. Moreover, it is preferable that the carbide | carbonized_material of this invention is a fine carbide | carbonized_material obtained through at least one process among a grinding | pulverization process and a classification process further. As described above, since the carbide is generally recovered as a lump, the carbide is finely crushed through a pulverization process using a pulverizer or the like, and the particle size of the carbide is selected through a classification process using a classifier or the like. Thus, the quality of the carbide can be improved.

Next, the rubber composition and tire of the present invention will be described in detail. The rubber composition of the present invention is characterized by blending a carbide obtained by the above-described thermal decomposition method or recovery method. In the rubber composition of the present invention, for example, in addition to the above carbide and rubber components, compounding agents usually used in the rubber industry, such as fillers, softeners, silane coupling agents, stearic acid, anti-aging agents, Zinc white, a vulcanization accelerator, a vulcanizing agent, and the like can be appropriately blended depending on the purpose. As these compounding agents, commercially available products can be suitably used. In addition, the said rubber composition can be manufactured by mix | blending various compounding agents suitably selected with the said carbide | carbonized_material with the said carbide | carbonized_material as needed, knead | mixing, heat-inserting, extrusion, etc.

The rubber component that can be used in the rubber composition of the present invention is not particularly limited, and in addition to natural rubber (NR), polyisoprene rubber (IR), styrene-butadiene copolymer rubber (SBR), polybutadiene. Synthetic rubbers such as rubber (BR), ethylene-propylene-diene rubber (EPDM), chloroprene rubber (CR), halogenated butyl rubber, acrylonitrile-butadiene rubber (NBR) can be used. You may use individually and may blend and use 2 or more types.

In the rubber composition of the present invention, the recovered carbide obtained by the above pyrolysis method or recovery method can be blended with pure carbon black. By combining the recovered carbide with pure carbon black, the physical property deterioration of the rubber composition can be suppressed to within 5%. The recovered carbide content in the total of the recovered carbide and pure carbon black is preferably in the range of 1 to 20% by mass. If content of this collection | recovery carbide | carbonized_material exists in the range specified above, the physical property fall of a rubber composition can be suppressed reliably.

The tire of the present invention is characterized by using the above-mentioned rubber composition, and can reduce the deterioration of physical properties of the tire even though the carbide recovered from the polymer waste is reused. The tire of the present invention is not particularly limited except that the above rubber composition is used, and can be manufactured according to a conventional method. Moreover, as gas with which this tire is filled, inert gas, such as nitrogen, argon, helium other than normal or the air which adjusted oxygen partial pressure, can be used.

Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples.

Example 1
Carbides were recovered from the waste truck tires using the thermal decomposition apparatus shown in FIG. 1 includes a heat exchanger 1, a polymer waste 2, a pyrolysis furnace 3, an external heating means 4, a circulation path 6, a gas generator 7, an oxygen concentration detector 8, an oil recovery. The apparatus 9, the recovery tank 10, the exhaust fan 11, the exhaust gas treatment device 12, and the flow rate control means 13 are provided, and the recovery tank 10 is provided downstream of the oil content recovery device 9.
Specifically, after putting about 100 kg of waste truck tire cut products (polymer waste 2) into the pyrolysis furnace 3 (capacity 0.5 m ³ ) and replacing the pyrolysis furnace 3 with nitrogen gas, While circulating the nitrogen gas in the thermal decomposition apparatus, the gas temperature was raised to about 500 ° C. by the heat exchanger 1, and this temperature was maintained. The gas flow rate of nitrogen gas introduced into the pyrolysis furnace 3 is set to 0.005m ³ / s [ntp], controlled in the range of ^{0.0045m 3 /s[ntp]~0.0055m 3 / s [ntp} ] However, the oxygen concentration in the pyrolyzer system was controlled within a range of 1% by volume or less. Here, a zirconia oxygen sensor or the like was used for measuring the oxygen concentration in the thermal decomposition apparatus. One hour after the start of heating by the heat exchanger 1, the pyrolysis gas started to be accumulated in the oil recovery device 9a, and the distillation stopped about 4 hours after the start of the heating by the heat exchanger 1. Stopping the distillation showed that the thermal decomposition reaction was completed, and the heat exchanger 1 was stopped and the system was left to cool for about 12 hours. Thereafter, the carbide was taken out from the pyrolysis furnace 3. Since the carbide includes a steel cord as a tire material, excess tire material was removed with a magnetic separator. Carbide from which excess tire material has been removed is pulverized into fine powder with a particle size of 1 mm or less with a hammer-type pulverizer, and this pulverized product is classified with an air classifier having rotating blades to obtain a particle size of 50 μm The above coarse powder was removed, and fine carbide for rubber compounding was recovered.
Next, the total acidity of the collected fine carbide for rubber compounding was measured by the above method and found to be 0.0594 meq / g.

(Example 2)
The gas flow rate of nitrogen gas introduced into the pyrolysis furnace 3 is set to 0.008m ³ / s [ntp], except for controlling the range of ^{0.0075m 3 /s[ntp]~0.0085m 3 / s [ntp} ] Were subjected to a thermal decomposition reaction in the same manner as in Example 1 above. In addition, since the gas flow rate in this example is higher than that in Example 1, distillation starts 45 minutes after the start of heating by the heat exchanger 1, and after 3 hours from the start of heating by the heat exchanger 1. Stopped.
Next, the total acidity of the fine carbide for rubber compounding obtained by pulverization and classification after recovery was measured by the above method and found to be 0.0908 meq / g.

(Example 3)
The gas flow rate of nitrogen gas introduced into the pyrolysis furnace 3 is set to 0.002m ³ / s [ntp], except for controlling the range of ^{0.0015m 3 /s[ntp]~0.0025m 3 / s [ntp} ] Were subjected to a thermal decomposition reaction in the same manner as in Example 1 above. In addition, since the gas flow rate in this example is lower than that in Example 1, the distillation started 1.5 hours after the start of heating by the heat exchanger 1 and 6 hours after the start of heating by the heat exchanger 1 Stopped.
Next, after collecting, the total acidity of the fine carbide for rubber compounding obtained by pulverization and classification was measured by the above method and found to be 0.0365 meq / g.

(Comparative Example 1)
The gas flow rate of nitrogen gas introduced into the pyrolysis furnace 3 is set to 0.011m ³ / s [ntp], except for controlling the range of ^{0.0105m 3 /s[ntp]~0.0115m 3 / s [ntp} ] Were subjected to a thermal decomposition reaction in the same manner as in Example 1 above. In addition, since the gas flow rate in this example is higher than that in Example 1, the distillation starts 40 minutes after the start of heating by the heat exchanger 1, and the distillation is started 2.5 hours after the start of heating by the heat exchanger 1. Stopped.
Next, after collecting, the total acidity of the fine carbide for rubber compounding obtained by pulverization and classification was measured by the above method and found to be 0.104 meq / g.

(Comparative Example 2)
The gas flow rate of nitrogen gas introduced into the pyrolysis furnace 3 is set to 0.013m ³ / s [ntp], except for controlling the range of ^{0.0125m 3 /s[ntp]~0.0135m 3 / s [ntp} ] Were subjected to a thermal decomposition reaction in the same manner as in Example 1 above. In addition, since the gas flow rate in this example is higher than that in Example 1, the distillation started 35 minutes after the start of heating by the heat exchanger 1, and the distillation was started 2.5 hours after the start of heating by the heat exchanger 1. Stopped.
Next, after collecting, the total acidity of the fine carbide for rubber compounding obtained by pulverization and classification was measured by the above method and found to be 0.145 meq / g.

(Comparative Example 3)
1 except that the gas generator 7 and the flow rate control means 13 were not operated in the pyrolysis apparatus shown in FIG. 1, the waste truck tire was pyrolyzed in the same manner as in Example 1 to recover the carbides ( That is, in Comparative Example 1, the thermal decomposition treatment was performed without taking any control means with respect to the oxygen concentration during the thermal decomposition reaction).
Next, the total acidity of the fine carbide for rubber compounding obtained by pulverization and classification after recovery was measured by the above method and found to be 0.151 meq / g.

(Comparative Example 4)
Except that the flow rate of oxygen-free gas introduced into the pyrolysis furnace 3 was controlled in the range of 27.0 m3 / h to 30.6 m3 / h in terms of 1 atm at 0 ° C, The waste truck tire was pyrolyzed without controlling the oxygen concentration in the cracker system.
Next, after collecting, the total acidity of the fine carbide for rubber compounding obtained by pulverization and classification was measured by the above method and found to be 0.205 meq / g.

(Comparative Example 5)
The gas flow rate of nitrogen gas introduced into the pyrolysis furnace 3 is set to 0.0010m ³ / s [ntp], except for controlling the range of ^{0.00095m 3 /s[ntp]~0.00105m 3 / s [ntp} ] Were subjected to a thermal decomposition reaction in the same manner as in Example 1 above. In addition, the gas flow rate in this example is less than 0.0015 m ³ / s [ntp], and only a small amount of distillate is observed even after 2 hours have passed since the heating by the heat exchanger 1 was started. However, since the thermal decomposition reaction hardly proceeded, it was stopped halfway.

Using the fine carbides for rubber compounding obtained in Examples 1 to 3 and Comparative Examples 1 to 4, rubber compositions having the compounding formulations shown in Table 2 were prepared, and the rubber compositions were unvulcanized and vulcanized. The later rubber properties were measured by the above method. The results are shown in Tables 3-5.

(1) Rubber properties when not vulcanized (a) Mooney viscosity Measured Mooney viscosity [ML _{1 + 4} (130 ° C)] at 130 ° C using Mooney viscometer according to JIS K6300-1: 2001 The rubber composition containing only GPF grade carbon black [manufactured by Asahi Carbon Co., Ltd., trade name: Asahi # 55] was indexed with the Mooney viscosity as 100. It shows that it is excellent in workability, so that an index value is small.
(B) Scorch time In accordance with JIS K6300-1: 2001, a Mooney viscosity-time curve is measured using a Mooney viscometer, and a time (t5) when the Mooney viscosity is increased by 5 points is obtained. This was the scorch time (minutes). Here, the scorch time of a rubber composition in which only GPF grade carbon black [manufactured by Asahi Carbon Co., Ltd., trade name: Asahi # 55] was blended was shown as an index. The closer the index value is to 100, the better the vulcanization time and the better the workability.

(2) Rubber characteristics after vulcanization (a) Hardness For vulcanized rubber obtained by vulcanization at 140 ° C for 30 minutes, a durometer hardness tester (type A) is used in accordance with JIS K6253: 2006. Evaluated. Specifically, a push needle was pushed into the surface of the rubber test piece of vulcanized rubber for 3 seconds, and the hardness of the rubber test piece was obtained from the push depth of the push needle. Here, the hardness of a rubber composition in which only GPF grade carbon black [manufactured by Asahi Carbon Co., Ltd., trade name: Asahi # 55] was blended was expressed as an index. The larger the index value, the higher the hardness of the rubber composition.
(B) Tensile stress For vulcanized rubber obtained by vulcanization at 140 ° C for 30 minutes, the tensile stress at 100% elongation and 300% elongation at room temperature was measured in accordance with JIS K6251: 2004, and GPF A rubber composition containing only grade grade carbon black [manufactured by Asahi Carbon Co., Ltd., trade name: Asahi # 55] was expressed as an index with the tensile stress as 100. The larger the index value, the greater the tensile stress and the higher the elastic modulus.
(C) Tensile strength A vulcanized rubber obtained by vulcanization at 140 ° C. for 30 minutes was measured for a tensile strength (Tb) at room temperature in accordance with JIS K6251: 2004. The rubber composition containing only Asahi Carbon Co., Ltd., trade name: Asahi # 55] was indexed with the tensile strength as 100. The larger the index value, the higher the resistance to fracture and the better the reinforcement.
(D) Elongation at cutting The vulcanized rubber obtained by vulcanization at 140 ° C. for 30 minutes was measured for elongation at room temperature in accordance with JIS K6251: 2004, and GPF grade carbon black [Asahi Carbon ( The rubber composition containing only the product name “Asahi # 55” manufactured by Co., Ltd. was indexed with the elongation at break as 100. It shows that the reinforcement effect to the rubber composition of the filler component mix | blended is so high that an index value is large.

* 1 Oil-extended rubber, oil-extended with 27.3 parts by mass of aroma oil for 100 parts by mass of rubber component, manufactured by JSR Corporation, product name: SBR 1723.
* 2 Product name: BROMOBUTYL 2255, manufactured by JSR Corporation.
* 3 A mixture of 20% by mass of fine carbide for rubber blending of any of Examples 1 to 3 and Comparative Examples 1 and 2 and 80% by mass of GPF grade carbon black.
* 4 Product name: Santoflex 6PPD, manufactured by Flexis.
* 5 Product name: Noxeller DM-P.
* 6 Product name: NOCRACK manufactured by Ouchi Shinsei Chemical Co., Ltd.
* 7 Ouchi Shinsei Chemical Co., Ltd., trade name: Noxeller
* 8 Product name: NOXELLER NS.

Tables 3 to 5, the range of carbide recovered by example, the gas flow rate of oxygen-free gas to be introduced into the pyrolysis furnace ^{0.0015m 3 /s[ntp]~0.0095m 3 / s [ntp} ] Thus, the total acidity, which is a standard for reinforcing the rubber, becomes 0.1 meq / g or less, whereby the rubber composition of Examples 1 to 3 in which the carbide is blended with GPF grade carbon black. Compared with the rubber composition containing only GPF grade carbon black, the product (ratio of fine carbide for rubber compounding in the total reinforcing filler: 20% by mass) has various rubber properties of unvulcanized rubber and vulcanized rubber. On the other hand, there was no reduction of 5% or more. On the other hand, the fine carbides for rubber compounding recovered in Comparative Examples 1 to 4 are all in that the flow rate of oxygen-free gas introduced into the pyrolysis furnace exceeds 0.0095 m ³ / s [ntp]. The acidity will exceed 0.1 meq / g, and as a result, the rubber composition of the comparative example has a rubber property that is reduced by 5% or more in any of the various rubber properties of unvulcanized rubber and vulcanized rubber. It was confirmed to have.

DESCRIPTION OF SYMBOLS 1 Heat exchanger 2 Polymer waste 3 Pyrolysis furnace 4 External heating means 5 Decomposition device 6 Circulation path 7 Gas generator 8 Oxygen concentration detector 9 Oil content recovery device 10 Recovery tank 11 Exhaust device 12 Exhaust gas processing device 13 Flow control means

Claims (13)

1. Heating the oxygen-free gas in the heat exchanger;
   Introducing a heated oxygen-free gas into a pyrolysis furnace containing the polymer waste, bringing the polymer waste into direct contact with the oxygen-free gas, and generating a pyrolysis gas. In the thermal decomposition method of polymer waste,
   Of polymer waste, characterized in that controlling the gas flow rate of oxygen-free gas to be introduced into the pyrolysis furnace in the range of ^{0.0015m 3 /s[ntp]~0.0095m 3 / s [ntp} ] Thermal decomposition method.
2. 2. The method for pyrolyzing polymer waste according to claim 1, wherein, in the step of generating the pyrolysis gas, the temperature during pyrolysis is controlled to 300 to 600 ° C.
3. The method for thermal decomposition of polymer waste according to claim 1, wherein the oxygen concentration in the oxygen-free gas is controlled to 1% by volume or less.
4. Heating the oxygen-free gas in the heat exchanger;
   Introducing a heated oxygen-free gas into a pyrolysis furnace containing a polymer waste, bringing the polymer waste into direct contact with the oxygen-free gas, and generating a pyrolysis gas;
   Cooling the pyrolysis gas and recovering the condensed oil;
   Recovering the carbide remaining in the pyrolysis furnace after pyrolysis of the polymer waste,
   Method for recovering carbide and controlling the gas flow rate of oxygen-free gas to be introduced into the pyrolysis furnace in the range of ^{0.0015m 3 /s[ntp]~0.0095m 3 / s [ntp} ].
5. The method for recovering carbide according to claim 4, wherein, in the step of generating the pyrolysis gas, the temperature during pyrolysis is controlled to 300 to 600 ° C.
6. The method for recovering carbide according to claim 4, wherein the oxygen concentration in the oxygen-free gas is controlled to 1% by volume or less.
7. A heat exchanger for heating anoxic gas;
   It has a pyrolysis furnace containing polymer waste inside and an external heating means for heating the pyrolysis furnace from outside, and the polymer waste is in direct contact with oxygen-free gas heated by the heat exchanger. A decomposition device for generating pyrolysis gas by pyrolyzing by,
   An oil recovery device for recovering the condensed oil by cooling the pyrolysis gas generated in the decomposition device;
   A circulation path for supplying the residual gas after the oil is recovered by the oil recovery device to the heat exchanger as an oxygen-free gas;
   A gas generator for generating an inert gas to be introduced into the pyrolysis furnace;
   An oxygen concentration detector for detecting an oxygen concentration in the pyrolysis apparatus system. A thermal decomposition apparatus for polymer waste, comprising:
8. The apparatus further comprises a device for controlling an inert gas introduction flow rate from the gas generator into the pyrolysis device system based on an oxygen concentration in the pyrolysis device system detected by the oxygen concentration detector. The thermal decomposition apparatus for polymer waste according to claim 7.
9. Carbides obtained by any one of the thermal decomposition method according to claims 1 to 3 and the recovery method according to claims 4 to 6.
10. The carbide according to claim 9, wherein the total acidity is 0.1 meq / g or less.
11. Furthermore, the carbide according to claim 9 or 10, which is a fine carbide obtained through at least one of a pulverization step and a classification step.
12. A rubber composition comprising the carbide according to any one of claims 7 to 11.
13. A tire using the rubber composition according to claim 12.

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