Pre-treatment method of rubber, pyrolysis treatment method of rubber, pre-treated rubber, pyrolysis product and pyrolysis oil

Abstract

Provided is a method for pretreating rubber, which enables pyrolysis of used rubber, hardly causes odor during pyrolysis, effectively reduces particularly volatile sulfur components and / or nitrogen components in a resultant pyrolysis product, and also reduces odor of oil obtained by pyrolysis. According to the present invention, the method for pretreating rubber involves pretreating sulfur-crosslinked rubber before pyrolysis. The method for pretreating rubber is characterized in that it includes a holding step of holding the sulfur-crosslinked rubber for at least 10 minutes under a flow of inert gas when the ambient pressure P is atmospheric pressure to produce pretreated rubber, the holding step being performed under a flow of inert gas when the ambient pressure P is atmospheric pressure.

Description

Technical Field

[0001] This invention relates to a method for pretreatment of rubber, a method for pyrolysis treatment of rubber, pretreated rubber, pyrolysis products, and pyrolysis oil. Background Technology

[0002] From a global environmental protection perspective, the recycling of used rubber, including from used tires, is encouraged. One such recycling technology involves pyrolyzing the used rubber and recovering the pyrolysis products, such as oil and carbon black (carbides). In recent years, various studies have been conducted to obtain high-quality pyrolysis products using such pyrolysis technologies.

[0003] In this specification, used tires refer to tire products that have been used once or that have not been used but have been collected or discarded.

[0004] For example, Patent Document 1 discloses controlling the flow rate of oxygen-free gas introduced into a pyrolysis furnace to suppress the oxidation of residual carbides after the pyrolysis of polymeric wastes such as tires. It has also been shown that, when blended with rubber components, the carbides obtained as a result of this control can adequately retain rubber properties.

[0005] Citation List

[0006] Patent documents

[0007] PTL 1: WO 2010 / 137352 A1 Summary of the Invention

[0008] The problem the invention aims to solve

[0009] Incidentally, rubber products generally contain a certain amount of sulfur and nitrogen (both mainly originating from various compounding agents). Therefore, when rubber products are pyrolyzed, the large amounts of these sulfur and / or nitrogen residues in pyrolysis products such as oil not only degrade the quality of the oil but also cause the oil itself to have a sulfurous odor. Furthermore, these sulfur and / or nitrogen residues also worsen the odor during pyrolysis (including odors in the working environment and odors emitted from pyrolysis products). This is a crucial technical problem to be solved in the rubber pyrolysis process.

[0010] Therefore, the technical problem of the present invention is to provide a method for pretreating rubber that can reduce odor during pyrolysis of used rubber, effectively reduce the content of particularly volatile sulfur and / or nitrogen in the resulting pyrolysis products, and further reduce the odor of the oil obtained from pyrolysis; and the pretreated rubber obtained by such a method.

[0011] In addition, the technical problem of the present invention is to provide a method for pyrolysis treatment of rubber, which can reduce the odor during pyrolysis of used rubber, effectively reduce the content of sulfur and / or nitrogen, which are particularly volatile, in the obtained pyrolysis products, and further reduce the odor of the oil obtained from pyrolysis.

[0012] Furthermore, the technical problem of the present invention is to provide pyrolysis products obtained by the above-described pyrolysis treatment method of rubber; and pyrolysis oil with reduced sulfur and / or nitrogen content and low odor as pyrolysis products.

[0013] Solution for solving the problem

[0014] The key structural features of the present invention that solves the above problems are as follows.

[0015] [1] A method for pretreating rubber, wherein the sulfur-crosslinked rubber is pretreated before pyrolysis treatment, wherein,

[0016] The method includes a holding step, wherein the sulfur-crosslinked rubber is held for more than 10 minutes under conditions satisfying the following formulas (1) and (2) to obtain a pretreated rubber:

[0017] 200 ≤ T ≤ 330 --- (1)

[0018] 0.0066e 0.0362T ≤ P ≤ 0.353e 0.0362T --- (2)

[0019] [In the formula, T represents the temperature of the sulfur-crosslinked rubber (unit: °C), and P represents the ambient pressure (unit: hPa), where P is below atmospheric pressure], and

[0020] In the holding process, when the ambient pressure P is atmospheric pressure, the holding is carried out under an inert gas flow.

[0021] [2] According to the rubber pretreatment method of [1], the holding time in the holding process is more than 10 minutes and less than 60 minutes.

[0022] [3] A method for pyrolysis treatment of rubber, wherein the method includes...

[0023] The pretreatment process, wherein the rubber is pretreated according to the method described in [1] or [2], and

[0024] The pyrolysis process involves pyrolyzing the pretreated rubber obtained in the pretreatment process at a temperature above 350°C to obtain pyrolysis products.

[0025] [4] A pretreated rubber obtained by a pretreatment method for rubber according to [1] or [2].

[0026] [5] A pyrolysis product obtained by the pyrolysis treatment method of rubber according to [3].

[0027] [6] A pyrolysis oil, which is a pyrolysis product according to [5].

[0028] [7] According to the pyrolysis oil of [6], wherein when the peak area value of the pyrolysis oil derived from benzothiazole in the gas chromatogram is A1, and the peak area value of the pyrolysis oil derived from benzothiazole in the gas chromatogram of the comparative pyrolysis oil obtained by pyrolysis treatment without pretreatment of the sulfur crosslinked rubber is A0, the reduction rate A1 / A0 is less than 0.60.

[0029] [8] The pyrolysis oil according to [6] or [7], wherein when the sulfur content ratio (mass%) of the pyrolysis oil measured according to JIS K 2541-4 is B1, and the sulfur content ratio (mass%) of the comparative pyrolysis oil obtained by pyrolysis treatment without pretreatment of the sulfur crosslinked rubber is B0, the reduction rate B1 / B0 is 0.90 or less.

[0030] The effects of the invention

[0031] According to the present invention, a method for pretreating rubber can be provided, which can reduce the odor during pyrolysis of used rubber, effectively reduce the content of particularly volatile sulfur and / or nitrogen in the resulting pyrolysis products, and further reduce the odor of the oil obtained from pyrolysis; and pretreated rubber obtained by such pretreating method.

[0032] In addition, according to the present invention, a method for pyrolysis treatment of rubber can be provided, which can reduce the odor during pyrolysis, effectively reduce the content of particularly volatile sulfur and / or nitrogen in the resulting pyrolysis products, and further reduce the odor of the oil obtained from pyrolysis.

[0033] Furthermore, according to the present invention, pyrolysis products obtained by the above-described pyrolysis treatment method of rubber can be provided; and pyrolysis oil, which has reduced sulfur and / or nitrogen content and low odor as a pyrolysis product, can be provided. Detailed Implementation

[0034] The following is a detailed description of the pretreatment method for rubber, the pyrolysis treatment method for rubber, the pretreated rubber, the pyrolysis products and the pyrolysis oil according to the present invention, based on its embodiments.

[0035] The term “used rubber” as used in this article includes vulcanized rubber and unvulcanized rubber, as well as rubber components separated by refurbishment, abrasion powder / fragments, rubber components used in the manufacture of tires and other materials, and residual unvulcanized and vulcanized rubber from the manufacture of tires and other materials.

[0036] The compounds described herein may be derived in whole or in part from fossil resources, biological resources such as plant resources, or recycled resources such as used tires. They may also be derived from a mixture of two or more fossil resources, biological resources, or recycled resources.

[0037] <Pretreatment methods for rubber>

[0038] The rubber pretreatment method of the present invention is a rubber pretreatment method, wherein the sulfur-crosslinked rubber is pretreated before pyrolysis treatment, characterized in that,

[0039] The method includes a holding step in which the sulfur-crosslinked rubber is held for more than 10 minutes under conditions satisfying the following formulas (1) and (2) to obtain a pretreated rubber:

[0040] 200 ≤ T ≤ 330 --- (1)

[0041] 0.0066e 0.0362T ≤ P ≤ 0.353e 0.0362T --- (2)

[0042] [In the formula, T represents the temperature of the sulfur-crosslinked rubber (unit: °C), and P represents the ambient pressure (unit: hPa), where P is below atmospheric pressure], and

[0043] During the holding process, when the ambient pressure P is atmospheric pressure, the holding is carried out under an inert gas flow.

[0044] As a result of the inventors' in-depth research, they have discovered that when used rubber is subjected to pyrolysis, a pretreatment process that meets specified conditions can significantly suppress the generation of undesirable odors during subsequent pyrolysis and effectively reduce the sulfur and nitrogen content in pyrolysis products such as oils. It is believed that this undesirable problem is at least partly caused by non-rubber organic components (vulcanization accelerators, antioxidants, and their degradation products, etc.) typically added during the manufacture of rubber products, and that through the aforementioned pretreatment process, these non-rubber organic components volatilize from the used rubber and are removed from the system. Therefore, according to the rubber pretreatment method of the present invention, odors can be reduced and the sulfur and / or nitrogen content in the obtained pyrolysis products can be effectively reduced during subsequent pyrolysis.

[0045] Appropriately, compared to the pyrolysis products (especially pyrolysis oil) obtained after pyrolysis treatment, the above-mentioned retention process reduces the amount of sulfur-containing compounds and nitrogen-containing compounds (benzothiazoles, thiophenes, and quinolines, which can be odor components in rubber chemicals) by more than 30%, respectively. In other words, when the ratio of sulfur-containing compounds or nitrogen-containing compounds in the pyrolysis product obtained by pretreating (retention process) and then pyrolyzing sulfur-crosslinked rubber is D1, and the ratio of sulfur-containing compounds or nitrogen-containing compounds in the comparative pyrolysis product obtained by not pretreating and then pyrolyzing (under the same conditions) is D0, D1 / D0 can be 0.70 or less.

[0046] Note that the content ratio of sulfur-containing compounds can be expressed as the total peak area related to sulfur detected by the SCD detector in GC / MS (gas chromatography-mass spectrometry). Similarly, the content ratio of nitrogen-containing compounds can be expressed as the total peak area related to nitrogen detected by the NPD detector in GC / MS (gas chromatography-mass spectrometry).

[0047] Suitablely, compared with the pyrolysis products (especially pyrolysis oil) obtained after pyrolysis treatment, the above-described retaining process reduces the amount of 6PPD (N-phenyl-N′-(1,3-dimethylbutyl)-p-phenylenediamine) by more than 50%. In other words, when the 6PPD content ratio in the pyrolysis product obtained by pretreating (retaining process) of sulfur-crosslinked rubber is E1, and the 6PPD content ratio in the comparative pyrolysis product obtained by not pretreating (under the same conditions) of sulfur-crosslinked rubber is E0, E1 / E0 can be 0.80 or less. More suitably, E1 / E0 can be 0.75 or less, or even more suitably 0.70 or less.

[0048] The 6PPD content ratio can be determined by the area value of the peaks originating from 6PPD detected by the NPD detector in GC / MS (gas chromatography-mass spectrometry) (only peaks identified as 1,4-phenylenediamine and N-(1,3-dimethylbutyl)-N'-phenyl-).

[0049] Note that the above-mentioned holding process (pretreatment method for rubber) is completely different from the general pyrolysis treatment of rubber because it does not cause active pyrolysis.

[0050] For example, even if the above-mentioned holding process is performed after pyrolysis, the desired effect will not be achieved because the pyrolysis process itself will not be affected.

[0051] Regarding the holding process according to the present invention, as long as the conditions satisfy equations (1) and (2), even if the temperature and / or pressure changes, it is within the range of "holding". That is, as long as the conditions satisfy equations (1) and (2), even if the temperature rises for more than 10 minutes, for example, the holding process of the present invention is satisfied.

[0052] The type of sulfur-crosslinked rubber used in the above pretreatment method is not limited, and all diene rubbers such as natural rubber (NR), synthetic isoprene rubber (IR), butadiene rubber (BR), styrene-butadiene rubber (SBR), ethylene-propylene-diene rubber (EPDM), and chloroprene rubber (CR) can be used.

[0053] In addition, for sulfur cross-linked rubber, rubber components that make up rubber products such as tires, rubber hoses, pipes, conveyor belts, tracks, sealing strips, glass chutes, etc. can be used, and the used materials are usually used for recycling purposes.

[0054] Furthermore, the sulfur-crosslinked rubber used in the above pretreatment method can be pre-crushed to a size of approximately 0.5 to 80 mm.

[0055] During the holding process, the sulfur crosslinked rubber is held for more than 10 minutes under the conditions satisfying the following formulas (1) and (2):

[0056] 200 ≤ T ≤ 330 --- (1)

[0057] 0.0066e 0.0362T ≤ P ≤ 0.353e 0.0362T --- (2)

[0058] [In the formula, T represents the temperature of the sulfur-crosslinked rubber (unit: °C), and P represents the ambient pressure (unit: hPa), where P is below atmospheric pressure]. If the holding time in the holding process is less than 10 minutes, non-rubber organic components, including sulfur and nitrogen, cannot be sufficiently removed.

[0059] Note that when the ambient pressure P is atmospheric pressure, the holding process is carried out under an inert gas flow. This allows volatiles from the sulfur-crosslinked rubber to be effectively removed from the system. The inert gas is not limited, but includes, for example, nitrogen, helium, argon, etc. On the other hand, while an inert gas can be used when the holding process is performed under reduced pressure, volatiles from the sulfur-crosslinked rubber can be removed from the system by suction without using an inert gas.

[0060] As shown in formula (1) above, the temperature T of the sulfur crosslinked rubber in the holding process is 200°C or higher and 330°C or lower. If the temperature T of the sulfur crosslinked rubber in the holding process is lower than 200°C, the non-rubber organic components in the sulfur crosslinked rubber cannot volatilize sufficiently. On the other hand, if the temperature T of the sulfur crosslinked rubber in the holding process exceeds 330°C, it will promote the decomposition of the rubber component (polymer component) of the sulfur crosslinked rubber. From the same point of view, the temperature T of the sulfur crosslinked rubber in the holding process is preferably 225°C or higher (i.e., replacing "200" in formula (1) with "225". This also applies to the following text.), more preferably 250°C or higher, even more preferably 260°C or higher, and preferably 300°C or lower (i.e., replacing "330" in formula (1) with "300").

[0061] The method of heating the sulfur-crosslinked rubber for the holding process is not limited, and in addition to heating with a heat source, self-heating by the compounded rubber, microwave heating, etc., can also be used. Furthermore, there are no particular limitations on the holding method in the holding process, and it includes, for example, methods that control the heat source output while monitoring the temperature of the sulfur-crosslinked rubber.

[0062] In addition, during the holding process, as shown in equation (2) above, the environmental pressure P (hPa) and temperature T (°C) of the sulfur crosslinked rubber should satisfy equation 0.0066e 0.0362T ≤P≤0.353e 0.0362T If the ambient pressure P during the process is kept below 0.0066e 0.0362T This will promote the decomposition of the rubber component (polymer component) of the sulfur-crosslinked rubber. On the other hand, if the environmental pressure P in the process is maintained above 0.353 e 0.0362T If this is not the case, the non-rubber organic components in the sulfur-crosslinked rubber cannot fully volatilize. From the same perspective, the environmental pressure P during the process is preferably 0.0136 e. 0.0362T The above is more preferably 0.0195e. 0.0362T The above, and preferably 0.246e 0.0362T Hereinafter, 0.171e is more preferred. 0.0362T the following.

[0063] The holding time in the holding process is preferably 10 minutes or more and 60 minutes or less. If the holding time is less than 60 minutes, excessive decomposition of the rubber component (polymer component) can be controlled. From the same point of view, it is more preferable that the holding time in the holding process is less than 40 minutes. On the other hand, from the viewpoint of more fully removing non-rubber organic components, including sulfur and nitrogen, the holding time in the holding process is preferably 20 minutes or more. Furthermore, in the holding process, for example, multiple temperature and time conditions can be combined, such as holding for 20 minutes at a first temperature and then holding for 15 minutes at a second temperature; or holding for more than 10 minutes at a temperature that is continuously increased or decreased within the range of the above formula (2).

[0064] The holding process for sulfur-crosslinked rubber can be performed only once, or it can be divided into two or three times. However, from the viewpoint of processing cycle efficiency and controlling the decomposition of rubber components, the cumulative holding time is preferably 60 minutes or less, more preferably 40 minutes or less.

[0065] In the holding process, from the viewpoint of making the pretreatment more effective and stable, it is preferable to keep the temperature fluctuation within 6°C, more preferably within 4°C, and even more preferably within 2°C.

[0066] Then, after the holding process, pretreated rubber is obtained.

[0067] <Pretreated Rubber>

[0068] The pretreated rubber of the present invention is characterized by being obtained through the aforementioned rubber pretreatment method. Specifically, the pretreated rubber of the present invention is a pretreated sulfur-crosslinked rubber. For recycling purposes, this pretreated rubber can be subjected to pyrolysis treatment.

[0069] The pretreated rubber is characterized by low levels of particularly volatile sulfur and nitrogen components. Specifically, the amount of sulfur-containing compounds and nitrogen-containing compounds (benzothiazoles, thiophenes, and quinolines, which can be odor components in rubber chemicals, belonging to this category) in the pretreated rubber is more than 30% lower than that in the sulfur-crosslinked rubber before pretreatment (holding process). In other words, when the ratio of sulfur-containing compounds or nitrogen-containing compounds in the pretreated rubber obtained by pretreatment (holding process) is D1, and the ratio of sulfur-containing compounds or nitrogen-containing compounds in the sulfur-crosslinked rubber before pretreatment (holding process) is D0, D1 / D0 can be less than 0.7.

[0070] <Methods for Pyrolysis Treatment of Rubber>

[0071] The method for pyrolysis treatment of rubber of the present invention is characterized in that the method includes,

[0072] The pretreatment process, wherein the above-mentioned rubber pretreatment method is performed, and

[0073] The pyrolysis process involves pyrolyzing the pretreated rubber obtained in the pretreatment process at temperatures above 350°C to obtain pyrolysis products.

[0074] According to the pyrolysis treatment method of the present invention, the rubber is pretreated according to regulations before the pyrolysis treatment of the sulfur crosslinked rubber, thereby reducing the odor during pyrolysis, effectively reducing the content of particularly volatile sulfur and / or nitrogen in the obtained pyrolysis products, and reducing the odor of the oil obtained from pyrolysis.

[0075] The pretreatment process is the same as the pretreatment method for rubber already described. Preferably, the pretreated rubber obtained after the pretreatment process is subjected to a pyrolysis process without cooling.

[0076] The rubber pyrolysis treatment method of the present invention may also include separate steps after the pretreatment step and before the pyrolysis step. Such separate steps include, for example, a rubber refining step and a step of mixing the rubber with a rubber decomposition catalyst.

[0077] The temperature in the pyrolysis process (pyrolysis temperature) is 350°C or higher. If the temperature is below 350°C, pyrolysis may not proceed sufficiently. Furthermore, from the viewpoint of controlling the deterioration of the quality of the obtained pyrolysis products and avoiding increased processing costs, the temperature in the pyrolysis process is preferably 800°C or lower, more preferably 600°C or lower. A rubber decomposition catalyst can be appropriately used in the pyrolysis process. Such a rubber decomposition catalyst includes, for example, zeolite catalysts and basic catalysts. In particular, when the pyrolysis temperature is below 400°C, the above-mentioned rubber decomposition catalyst is preferably used.

[0078] In order to improve the liquid yield of the obtained pyrolysis oil and the surface activity of the carbon black residue, the temperature in the pyrolysis process is preferably set to minimize the gasification and carbonization of the pyrolysis oil, specifically, above 400°C and below 550°C.

[0079] The pyrolysis process is not limited to any specific means, as long as the rubber undergoes pyrolysis. For example, it can be carried out in a pyrolysis furnace commonly used for rubber pyrolysis for recycling purposes. Furthermore, the conditions in the pyrolysis process, except for temperature, are not limited, as long as the rubber undergoes pyrolysis. For example, conditions commonly used for rubber pyrolysis for recycling purposes can be appropriately employed.

[0080] The pyrolysis process typically produces both solids and gases. Carbon black (carbides) can be recovered from the solids as a pyrolysis product. Furthermore, pyrolysis oil can be recovered from the gas as a pyrolysis product through cooling and condensation. Depending on the desired liquefaction temperature, pyrolysis oil can also be recovered from the gas by separating it into light and heavy oil components.

[0081] <Pyrolysis Products>

[0082] The pyrolysis products of this invention are characterized by being obtained through the aforementioned rubber pyrolysis treatment method. These pyrolysis products are obtained through the pyrolysis treatment of rubber, wherein the rubber has been pretreated according to regulations, thereby effectively reducing the sulfur and / or nitrogen content. Specifically, the pyrolysis products include carbon black (carbides) and pyrolysis oil.

[0083] Suitablely, when the peak area value of benzothiazole derived in the gas chromatography of the pyrolysis oil is A1, and the peak area value of benzothiazole derived in the gas chromatography of the comparative pyrolysis oil obtained by pyrolysis treatment (under the same conditions) without pretreatment of the sulfur-crosslinked rubber, the reduction rate A1 / A0 is 0.60 or less. More suitablely, the reduction rate A1 / A0 is 0.55 or less, and even more suitablely, it is 0.50 or less.

[0084] The reduction rate of benzothiazole (a compound containing sulfur and nitrogen) was calculated using the area values ​​of the peaks originating from benzothiazole (peaks identified only as benzothiazole) detected by the SCD detector in GC / MS (gas chromatography-mass spectrometry).

[0085] Suitablely, when the sulfur content ratio (mass%) of the above-mentioned pyrolysis oil, measured according to JIS K 2541-4, is B1, and the sulfur content ratio (mass%) of the comparative pyrolysis oil obtained by pyrolysis treatment without pretreatment of the sulfur-crosslinked rubber (under the same conditions) is B0, the reduction rate B1 / B0 is 0.95 or less. More suitablely, the reduction rate B1 / B0 is 0.90 or less, and even more suitablely, it is 0.85 or less.

[0086] Note that total sulfur can be measured according to JIS K 2541-4.

[0087] Suitablely, when the nitrogen content ratio (mass%) of the above-mentioned pyrolysis oil, measured according to JIS K 2609, is C1, and the nitrogen content ratio (mass%) of the comparative pyrolysis oil obtained by pyrolysis treatment (under the same conditions) without pretreatment of the sulfur-crosslinked rubber, measured according to JIS K 2609, is C0, the reduction rate C1 / C0 is 0.90 or less. More suitablely, the reduction rate C1 / C0 is 0.90 or less, and even more suitablely, it is 0.85 or less.

[0088] In addition, according to the standards described in the embodiments, the above-mentioned pyrolysis oil appropriately has an odor intensity of 3 or less.

[0089] Example

[0090] The present invention is described in more detail below with reference to embodiments, but the present invention is not limited in any way to the following embodiments.

[0091] (Preparation of sulfur-crosslinked rubber)

[0092] According to the formula provided in Table 1, the components were mixed using a 70cc sealed mixer, and then heated at 10MPa pressure and 145°C for 33 minutes to obtain vulcanized rubber (vulcanized crosslinked rubber). The resulting vulcanized rubber was cut into 2mm square cubes and made into vulcanized rubber sheets.

[0093] [Table 1]

[0094] Quality Natural rubber 100 HAF Carbon Black 50 stearic acid 2.0 Zinc oxide 3.5 Anti-aging agent 6PPD 1.0 CBS vulcanization accelerator 1.4 sulfur 1.1 Other chemicals 1.42

[0095] (Pretreatment of sulfur-crosslinked rubber)

[0096] The vulcanized rubber sheet is placed in a crucible and heated from room temperature to 300°C using an electric furnace at a rate of 20°C / min. After reaching 300°C, the temperature is held for 35 minutes (i.e., held for at least 10 minutes under the conditions satisfying equations (1) and (2)). At this time, nitrogen gas is introduced into the electric furnace at a flow rate of 1000 ml / min, forming a nitrogen gas flow inside the furnace. The vulcanized rubber sheet is pretreated in this manner before the pyrolysis process.

[0097] (Pyrolysis treatment)

[0098] Next, the pretreated vulcanized rubber sheet (pretreated rubber) is pyrolyzed using a tubular pyrolysis reactor equipped with a quartz tube, an electric furnace, and an oil collector. Specifically, approximately 25g of pretreated rubber is pyrolyzed by feeding 3 to 5g of pretreated rubber at 5-minute intervals. In this pyrolysis process, an electric furnace is set up so that the measuring temperature in the quartz tube is 500°C, and a nitrogen flow rate of 100ml / min is generated inside the furnace.

[0099] As a comparison, pyrolysis treatment was also performed on vulcanized rubber sheets that had not undergone the pretreatment described above under the same conditions.

[0100] <Evaluation of the intensity of oily odor>

[0101] The odor intensity of the pyrolysis oil obtained from the pyrolysis treatment of the above-mentioned vulcanized rubber sheets (with and without pretreatment) was evaluated by three healthy men and women (A, B, and C) with no olfactory abnormalities according to the following six-level criteria.

[0102] 0: No odor detected at all

[0103] 1: Almost no odor detected (detection threshold concentration)

[0104] 2: It can detect odors that are faint enough to identify what they are (cognitive threshold concentration).

[0105] 3: Odors can be easily detected.

[0106] 4: A strong odor was detected.

[0107] 5: A very strong odor was detected.

[0108] The decimal value of the average of the three evaluations was then processed as follows to determine the odor intensity (this is based on the method used to calculate odor intensity in the three-point comparison odor bag method). The evaluation results are provided in Table 2.

[0109] - If it is greater than 0.25 and less than 0.75, it is rounded to 0.5 (e.g., 2.31 and 2.68 are rounded to 2.5).

[0110] - If it is greater than 0.75 and less than 0.25, it is rounded to the nearest integer (e.g., 2.84 and 3.15 are rounded to 3).

[0111] [Table 2]

[0112] A B C average Odor intensity Pyrolysis oil (without pretreatment) 5 5 4 4.67 4.5 Pyrolysis oil (with pretreatment) 2 3 2 2.33 2.5

[0113] Table 2 shows that by performing a prescribed pretreatment on the rubber, the odor of the pyrolysis oil obtained from the pyrolysis of the rubber can be significantly improved.

[0114] <Evaluation of oil components (1)>

[0115] SCD and NPD detectors were installed on a gas chromatograph, and the composition of sulfur-containing compounds, nitrogen-containing compounds, benzothiazoles, and 6PPD in the pyrolysis oil obtained from the pyrolysis treatment of the above-mentioned vulcanized rubber sheets (with and without pretreatment) was analyzed by GC / MS (gas chromatography-mass spectrometry). For sulfur-containing compounds, the total peak area of ​​sulfur detected by the SCD detector was measured. For nitrogen-containing compounds, the total peak area of ​​nitrogen detected by the NPD detector was measured. For benzothiazoles (which are compounds containing both sulfur and nitrogen), the peak area derived from benzothiazoles detected by the SCD detector was measured. For 6PPDs (which are nitrogen-containing compounds), the peak area derived from 6PPDs detected by the NPD detector was measured. For each of the sulfur-containing compounds, nitrogen-containing compounds, benzothiazoles, and 6PPDs, the value of the untreated pyrolysis oil was set to 100, and the value of the pretreated pyrolysis oil was indexed. The results are provided in Table 3.

[0116] [Table 3]

[0117]

[0118] Table 3 shows that by performing the prescribed pretreatment on the rubber, the amounts of sulfur-containing compounds, nitrogen-containing compounds, benzothiazole, and 6PPD in the pyrolysis oil obtained from the pyrolysis treatment of the rubber can be reduced respectively.

[0119] <Evaluation of oil components (2)>

[0120] The sulfur content ratio (mass%) in the pyrolysis oil obtained by pyrolysis treatment of the above-mentioned vulcanized rubber sheets (without pretreatment / with pretreatment) was measured according to JIS K 2541-4, and the nitrogen content ratio (mass%) in the pyrolysis oil was also measured according to JIS K 2609. For each of the sulfur content ratio and nitrogen content ratio, the value of the untreated pyrolysis oil was set to 100, and the value of the pretreated pyrolysis oil was indexed respectively. The results are provided in Table 4.

[0121] [Table 4]

[0122]

[0123] Table 4 shows that by performing a specified pretreatment on the rubber, the sulfur content ratio and nitrogen content ratio in the pyrolysis oil obtained by the pyrolysis treatment of the rubber can be reduced respectively.

[0124] Industrial availability

[0125] According to the present invention, a method for pretreating rubber can be provided, which can reduce the odor during pyrolysis of used rubber, effectively reduce the content of particularly volatile sulfur and / or nitrogen in the resulting pyrolysis products, and further reduce the odor of the oil obtained from pyrolysis; and pretreated rubber obtained by such pretreating method.

[0126] Furthermore, according to the present invention, a method for pyrolysis treatment of rubber can be provided, which can reduce odor during pyrolysis of used rubber, effectively reduce the content of sulfur and / or nitrogen, which are particularly volatile, in the resulting pyrolysis products, and further reduce the odor of the oil obtained from pyrolysis.

[0127] In addition, according to the present invention, pyrolysis products obtained by the above-described pyrolysis treatment method of rubber can be provided; and pyrolysis oil with reduced sulfur and / or nitrogen content and low odor as pyrolysis products can be provided.

Claims

1. A method for pretreating rubber, wherein the sulfur-crosslinked rubber is pretreated prior to pyrolysis treatment, wherein, The method includes a holding step, wherein the sulfur-crosslinked rubber is held for more than 20 minutes under conditions satisfying the following formulas (1) and (2) to obtain a pretreated rubber: 200 ≤ T ≤ 330 --- (1) 0.0066e 0.0362T ≤ P ≤ 0.353e 0.0362T --- (2) In the formula, T represents the temperature of the sulfur-crosslinked rubber, in °C; P represents the ambient pressure, in hPa, where P is below atmospheric pressure. In the holding process, when the ambient pressure P is atmospheric pressure, the holding is carried out under an inert gas flow.

2. The rubber pretreatment method according to claim 1, wherein the holding time in the holding process is more than 20 minutes and less than 60 minutes.

3. A method for pyrolysis treatment of rubber, wherein the method includes, A pretreatment step, wherein the rubber pretreatment method according to claim 1 or 2 is performed, and The pyrolysis process involves pyrolyzing the pretreated rubber obtained in the pretreatment process at a temperature above 350°C to obtain pyrolysis products.

4. A pretreated rubber obtained by the pretreatment method of rubber according to claim 1 or 2.

5. A pyrolysis product obtained by the pyrolysis treatment method of rubber according to claim 3.

6. A pyrolysis oil, which is a pyrolysis product according to claim 5.

7. The pyrolysis oil according to claim 6, wherein when the peak area value of benzothiazole derived from the gas chromatograph of the pyrolysis oil is A1, and the peak area value of benzothiazole derived from the gas chromatograph of the comparative pyrolysis oil obtained by pyrolysis treatment without pretreatment of the sulfur crosslinked rubber is A0, the reduction rate A1 / A0 is 0.60 or less.

8. The pyrolysis oil according to claim 6, wherein when the sulfur content ratio of the pyrolysis oil in mass% as measured according to JIS K 2541-4 is B1, and the sulfur content ratio of the comparative pyrolysis oil obtained by pyrolysis treatment without pretreatment of the sulfur crosslinked rubber is B0, the reduction rate B1 / B0 is 0.90 or less.

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