Method for producing thermal decomposition product of waste plastic

Abstract

To provide a method for producing a thermal decomposition product of a waste plastic which can reduce the amount of production of inorganic chlorine gas when thermally producing a waste plastic containing polyvinyl chloride.SOLUTION: A method for producing a thermal decomposition product of a waste plastic includes: a step of obtaining a mixture of a first waste plastic containing, as a main component, a first resin derived from at least any one of polyethylene, polypropylene and polystyrene, a second waste plastic containing, as a main component, a second resin derived from polyvinyl chloride, and a third waste plastic containing, as a main component, a third resin derived from polyamide; and a thermal decomposition step of thermally decomposing the mixture, and thereby producing a thermal decomposition product. Therein a content of the first waste plastic with respect to a total amount of the first waste plastic, the second waste plastic and the third waste plastic contained in the mixture is 70 mass% or more.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a method for producing a pyrolysis product of waste plastics. [Background technology]

[0002] Because plastics are durable and non-corrosive, marine pollution caused by dumped used plastics has become a global issue. Used plastics (waste plastics) are a variety of plastics, mainly consisting of the four major general-purpose resins: polyethylene (PE), polypropylene (PP), polystyrene (PS), and polyvinyl chloride (PVC). As the problem of waste plastic disposal becomes more serious, chemical recycling, which recovers olefin gas and other substances from waste plastic, has been attracting attention. However, since hydrogen chloride, which is corrosive, is generated when polyvinyl chloride (PVC) is thermally decomposed, various studies have been conducted on how to handle hydrogen chloride. For example, Patent Document 1 discloses a dechlorination treatment system for treating waste plastics containing vinyl chloride, the dechlorination treatment system being characterized in that it includes a waste plastics input device for inputting waste plastics containing vinyl chloride into a pyrolysis furnace, a pyrolysis furnace connected to the waste plastics input device and for thermally decomposing the vinyl chloride contained in the waste plastics from the waste plastics input device to generate hydrogen chloride gas and organic gas, a gas treatment device connected to the pyrolysis furnace and for treating the hydrogen chloride gas and organic gas generated in the pyrolysis furnace, a cooling and solidification device connected to the pyrolysis furnace and for cooling and solidifying the waste plastics carbonized or melted in the pyrolysis furnace, an inert gas supply device connected to the pyrolysis furnace and for supplying a desired amount of inert gas to the pyrolysis furnace, and a vacuum device connected to the pyrolysis furnace to create a vacuum inside the pyrolysis furnace. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2002-309034 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the dechlorination treatment system described in Patent Document 1, hydrogen chloride generated in a pyrolysis furnace is recovered as hydrochloric acid in a hydrogen chloride gas absorption tower of a gas treatment device. Hydrogen chloride corresponds to inorganic chlorine gas. In recent years, in the chemical recycling of waste plastics, there has been a demand not only for a method of treating hydrogen chloride generated in a pyrolysis furnace, but also for a method of reducing the amount of hydrogen chloride itself generated in the pyrolysis furnace.

[0005] An object of the present invention is to provide a method for producing a pyrolysis product of waste plastics, which can reduce the amount of inorganic chlorine gas produced when polyvinyl chloride-containing waste plastics are pyrolyzed. [Means for solving the problem]

[0006] [1] A method for producing a thermal decomposition product of waste plastics, comprising: a step of obtaining a mixture of a first waste plastic containing as a main component a first resin derived from at least one of polyethylene, polypropylene, and polystyrene, a second waste plastic containing as a main component a second resin derived from polyvinyl chloride, and a third waste plastic containing as a main component a third resin derived from polyamide; and a thermal decomposition step of producing a thermal decomposition product by thermally decomposing the mixture, wherein the content of the first waste plastic is 70 mass% or more of the total amount of the first waste plastic, the second waste plastic, and the third waste plastic contained in the mixture.

[0007] [2] The pyrolysis product produced in the pyrolysis step contains a light olefin-containing gas and an organic chlorine; A method for producing the pyrolysis product of waste plastic described in [1] above.

[0008] [3] The ratio of the content of the third waste plastic to the content of the second waste plastic (the content of the third waste plastic / the content of the second waste plastic) is 0.5 or more by mass ratio; A method for producing a pyrolysis product of waste plastic described in [1] or [2] above.

[0009] [4] With respect to the total amount of the first waste plastic, the second waste plastic, and the third waste plastic contained in the mixture, The content of the second waste plastic is 0.01% by mass or more and 10% by mass or less, The content of the third waste plastic is 0.01% by mass or more and 20% by mass or less. A method for producing a pyrolysis product of waste plastic described in any one of [1] to [3] above.

[0010] [5] With respect to the total amount of the first waste plastic, the second waste plastic, and the third waste plastic contained in the mixture, The content of the first waste plastic is 90% by mass or more. A method for producing a pyrolysis product of waste plastic described in any one of [1] to [3] above.

[0011] [6] With respect to the total amount of the first waste plastic, the second waste plastic, and the third waste plastic contained in the mixture, The content of the second waste plastic is 0.01% by mass or more and 2.0% by mass or less, The content of the third waste plastic is 0.01% by mass or more and 8.0% by mass or less. A method for producing the pyrolysis product of waste plastic described in [5] above.

[0012] [7] The method further comprises a separation step of cooling the pyrolysis product produced in the pyrolysis step and separating it into a light olefin-containing gas, an oil component, and a water component; The oil component contains an organic chlorine, The water component contains inorganic chlorine. A method for producing a pyrolysis product of waste plastic described in any one of [1] to [6] above.

[0013] [8] The method for producing a pyrolysis product of waste plastic described in [7], wherein the content C1 of the organic chlorine in the oil component satisfies the following mathematical formulas (Mathematical Formula 1) and (Mathematical Formula 2). The organic chlorine content C1 = (organic chlorine content in the oil component / total content of chlorine atoms) × 100 ≧ 10.0 ... (Equation 1) Total content of chlorine atoms = (content of the organic chlorine in the oil component) + (content of the inorganic chlorine in the water component) ... (Equation 2) (In the above formulas (1) and (2), The unit of organic chlorine content in the oil component is [g], The unit of inorganic chlorine content in the water component is [g], The unit of the total chlorine atom content is [g], The unit of the organic chlorine content C1 is [mass%].)

[0014] [9] The content C2 of the inorganic chlorine in the water component satisfies the following formulas (Mathematical Formula 2) and (Mathematical Formula 3): A method for producing a pyrolysis product of waste plastic described in [7] or [8] above. The inorganic chlorine content C2=(the inorganic chlorine content in the water component / the total content of chlorine atoms)×100≦90.0…(Equation 3) Total content of chlorine atoms = (content of the organic chlorine in the oil component) + (content of the inorganic chlorine in the water component) ... (Equation 2) (In the above formulas (2) and (3), The unit of organic chlorine content in the oil component is [g], The unit of inorganic chlorine content in the water component is [g], The unit of the total chlorine atom content is [g], The unit of inorganic chlorine content C2 is [mass%].)

[0015]

[10] The light olefin-containing gas contained in the pyrolysis product is supplied to a petrochemical process and used. A method for producing a pyrolysis product of waste plastic described in any one of [7] to [9]. Effect of the Invention

[0016] According to one aspect of the present invention, a method for producing a pyrolysis product of waste plastics that can reduce the amount of inorganic chlorine gas produced when pyrolyzing waste plastics containing polyvinyl chloride can be provided. Furthermore, a method for producing a pyrolysis product of waste plastics that can diversify the types of waste plastics that can be used by using waste plastics derived from polyamide can be provided. [Brief description of the drawings]

[0017] [Figure 1] FIG. 1 is a schematic diagram of a production apparatus for a pyrolysis product of waste plastics that can be used to carry out the production method according to the first embodiment. [Diagram 2] FIG. 2 is a schematic diagram of an experimental apparatus used in the evaluation of the examples and comparative examples. [Diagram 3] FIG. 2 is a mass spectrum of a characteristic pyrolysis product of sample (c) prepared for the structural analysis of a specific organic chlorine compound in the Examples. [Figure 4] The peak of the target organic chlorine compound is shown on the chromatogram of the m / z=133 ion extracted from the pyrolysis GC-MS measurement of samples (a) to (c). [Diagram 5] 1 is a graph showing the relationship between polyamide ratio (relative to PVC) and organic chlorine ratio. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] In this specification, a numerical range expressed using "to" means a range that includes the numerical value before "to" as the lower limit and the numerical value after "to" as the upper limit. In this specification, the ordinal expressions "first," "second," and "third" are intended to distinguish configurations and do not imply an order. In this specification, expressions without ordinal numbers, such as "waste plastics" or "each waste plastic" are general terms for waste plastics and are used to give a common explanation for waste plastics with the ordinal numbers "first," "second," and "third." For example, when an explanation is given that applies commonly to multiple components expressed with ordinal numbers, such as "first waste plastic," "second waste plastic," and "third waste plastic," "first waste plastic," "second waste plastic," and "third waste plastic" can be expressed collectively by expressing them as "waste plastic" or "each waste plastic" without the ordinal number.

[0019] [First embodiment] [Method for producing pyrolysis products of waste plastics] The manufacturing method for pyrolysis products of waste plastics according to the first embodiment (hereinafter also referred to as the manufacturing method according to this embodiment) includes a step of obtaining a mixture of a first waste plastic containing as its main component a first resin derived from at least one of polyethylene, polypropylene, and polystyrene, a second waste plastic containing as its main component a second resin derived from polyvinyl chloride, and a third waste plastic containing as its main component a third resin derived from polyamide, and a pyrolysis step of producing pyrolysis products by pyrolyzing the mixture. The content of the first waste plastic is 70 mass % or more with respect to the total amount of the first waste plastic, the second waste plastic, and the third waste plastic contained in the mixture. The first waste plastic, the second waste plastic, and the third waste plastic are different waste plastics. The first resin, the second resin, and the third resin are different resins. The pyrolysis product is, for example, a gas component when it is discharged from a pyrolysis device. The pyrolysis product includes a component that condenses upon cooling and a component that does not condense. For example, when the pyrolysis product is cooled to 60°C, an oil component and a water component are separated from the pyrolysis product as condensable components.

[0020] In this specification, inorganic chlorine means chlorine atoms in inorganic chlorine gas (hydrogen chloride, hypochlorous acid, etc.) generated by thermal decomposition of the second waste plastic containing a polyvinyl chloride polymer. In this specification, organic chlorine means a chlorine atom contained in an organic chlorine compound.

[0021] The present inventors have found that by obtaining a mixture of a first waste plastic containing a first resin (such as a polypropylene-based polymer), a second waste plastic containing a second resin (a polyvinyl chloride-based polymer) as a main component, and a third waste plastic containing a third resin (a polyamide-based polymer) as a main component, and then pyrolyzing the mixture, an organic chlorine compound (hereinafter also referred to as a specific organic compound) that is thought to be generated by the reaction between the second resin (a polyvinyl chloride-based polymer) and the third resin (a polyamide-based polymer) is contained in the pyrolysis product, and the generation of this specific organic chlorine compound reduces the amount of inorganic chlorine gas generated. Therefore, in the pyrolysis process according to this embodiment, it is thought that a part of the inorganic chlorine that can be generated is replaced by organic chlorine in the specific organic chlorine compound. The structural analysis of specific organochlorine compounds is described in detail in the Examples section. According to the manufacturing method of the present embodiment, the amount of inorganic chlorine gas generated can be reduced when waste plastics containing polyvinyl chloride are thermally decomposed. Furthermore, by using waste plastics derived from polyamide, the types of waste plastics that can be used can be diversified.

[0022] Furthermore, since inorganic chlorine gas contained in the pyrolysis products can cause corrosion of various facilities, it has been conventionally often dissolved in water in a cooling device, neutralized with alkaline water, and then disposed of. According to the production method of this embodiment, the amount of inorganic chlorine gas produced is reduced, and therefore the amount of inorganic chlorine waste can be reduced. In addition, the specific organic chlorine compounds obtained in the pyrolysis process of this embodiment are heavy and difficult to dissolve in water, so when the pyrolysis products are separated in a cooling device, they are separated into oil components. The separated oil components can be used as fuel, etc. If the specific organic chlorine compounds can be used as fuel, etc., the demand for effective use of resources can be met.

[0023] <Step of Obtaining Mixture> In the manufacturing method according to the present embodiment, one aspect of the step of obtaining a mixture is a step of obtaining a mixture by mixing a first waste plastic containing a first resin derived from at least one of polyethylene, polypropylene, and polystyrene as a main component, a second waste plastic containing a second resin derived from polyvinyl chloride as a main component, and a third waste plastic containing a third resin derived from polyamide as a main component. One aspect of the step of obtaining a mixture may be a step of obtaining a mixture containing the first waste plastic, the second waste plastic, and the third waste plastic. The process for obtaining a mixture is a process for obtaining a mixture of a first waste plastic, a second waste plastic, and a third waste plastic so that the content of the first waste plastic in the obtained mixture is at least 70 mass% relative to the total amount of waste plastics. That is, in the mixture obtained in the process of obtaining a mixture, the content of the first waste plastic is 70 mass% or more relative to the total amount of waste plastics (the total amount of the first waste plastic, the second waste plastic, and the third waste plastic). When the content of the first waste plastics is 70% by mass or more, it is possible to reduce the amount of inorganic chlorine produced and to produce a large amount of light olefin-containing gas that can be recycled as a plastic raw material.

[0024] In this specification, the term "major component" refers to the component that accounts for the largest proportion of the components constituting the target object (e.g., a component that accounts for 45% by mass or more). For example, the term "major component" refers to a component that accounts for 50% by mass or more (upper limit 100% by mass) of the components contained in the target object. The content of the first resin in the first waste plastic is preferably 50% by mass or more, more preferably 75% by mass or more, even more preferably 85% by mass or more, and still more preferably 95% by mass or more. The content of the second resin in the second waste plastic is preferably 50% by mass or more, more preferably 75% by mass or more, even more preferably 85% by mass or more, and still more preferably 95% by mass or more. The content of the third resin in the third waste plastic is preferably 50% by mass or more, more preferably 75% by mass or more, even more preferably 85% by mass or more, and still more preferably 95% by mass or more.

[0025] (Content of the first waste plastic, the second waste plastic, and the third waste plastic) In the mixture obtained in the step of obtaining a mixture, the content of each waste plastic is preferably in the following range. The content of each waste plastic is a ratio (unit: mass%) to the total amount of waste plastics (the total amount of the first waste plastic, the second waste plastic, and the third waste plastic). In order to generate a larger amount of light olefin-containing gas when the mixture is pyrolyzed, the content of the first waste plastic is preferably 75% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more. The upper limit of the content of the first waste plastic is preferably 99.98% by mass or less. The content of the second waste plastic is preferably small from the viewpoint of further reducing the amount of inorganic chlorine gas produced when the mixture is thermally decomposed. The content of the second waste plastic is preferably 20% by mass or less, more preferably 10% by mass or less, even more preferably 5.0% by mass or less, and even more preferably 1.0% by mass or less. The lower limit of the content of the second waste plastic is, for example, 0.01% by mass or more. From the viewpoint of reducing inorganic chlorine, the content of the third waste plastics is preferably greater than the content of the second waste plastics. The content of the third waste plastic is preferably 0.01% by mass or more, more preferably 1.0% by mass or more, even more preferably 5% by mass or more, even more preferably 10% by mass or more, and even more preferably 15% by mass or more. The upper limit of the content of the third waste plastic is, for example, 20 mass % or less. It is preferable that the content of the first waste plastic is 70% by mass or more, the content of the second waste plastic is 0.01% by mass or more and 10% by mass or less, and the content of the third waste plastic is 0.01% by mass or more and 20% by mass or less. It is more preferable that the content of the first waste plastic is 90% by mass or more, the content of the second waste plastic is 0.01% by mass or more and 2.0% by mass or less, and the content of the third waste plastic is 0.01% by mass or more and 8.0% by mass or less. From the viewpoint of further reducing the generation of inorganic chlorine when the mixture is pyrolyzed (i.e., from the viewpoint of making it easier to generate specific organic chlorine compounds), the higher the ratio of the content of the third waste plastic to the content of the second waste plastic (content of the third waste plastic / content of the second waste plastic) (mass ratio), the more preferable. Therefore, the ratio (content of the third waste plastic / content of the second waste plastic) is preferably 0.5 or more, more preferably 1.0 or more, even more preferably 2.0 or more, even more preferably 3.0 or more, and even more preferably 4.0 or more, by mass ratio. The upper limit of the ratio (content of the third waste plastic / content of the second waste plastic) is preferably 5.5 or less, since the amount of organic chlorine generated tends to saturate when it exceeds 5.5 (see FIG. 5).

[0026] (Ratio of chlorine atom content to nitrogen atom content) In the process of obtaining the mixture of this embodiment, in the total amount of resin contained in the first waste plastic, the second waste plastic, and the third waste plastic, it is preferable that the content of chlorine atoms and the content of nitrogen atoms satisfy the relationship of the following mathematical formula (Mathematical Formula 10), it is more preferable that the relationship of the following mathematical formula (Mathematical Formula 10A) is satisfied, and it is even more preferable that the relationship of the following mathematical formula (Mathematical Formula 10B) is satisfied. In other words, the process for obtaining a mixture in this embodiment is preferably a process for obtaining a mixture of the first waste plastic, the second waste plastic, and the third waste plastic such that the content of chlorine atoms and the content of nitrogen atoms relative to the total amount of resin contained in the first waste plastic, the second waste plastic, and the third waste plastic satisfy the relationship of the following mathematical formula (Mathematical Formula 10).

[0027] (The content of the nitrogen atoms in the total amount of the resin) / (The content of the chlorine atoms in the total amount of the resin)≧0.2...(Number 10) (The content of the nitrogen atoms in the total amount of the resin) / (The content of the chlorine atoms in the total amount of the resin)≧0.6...(Number 10A) (The content of the nitrogen atoms in the total amount of the resin) / (The content of the chlorine atoms in the total amount of the resin)≧1.2... (Number 10B) (In the above formulas (10), (10A), and (10B), the unit of the content of the nitrogen atoms is [mass%], and the unit of the content of the chlorine atoms is [mass%].) The upper limit of the ratio ((the content of the nitrogen atoms in the total amount of the resin) / (the content of the chlorine atoms in the total amount of the resin)) is preferably 2.0 or less, since if it exceeds 2.0, the amount of organic chlorine produced tends to saturate.

[0028] The total amount of resin is the total amount of resin components contained in the first waste plastic, the second waste plastic, and the third waste plastic, and specifically, it means the total amount of the first resin, the second resin, the third resin, and "other resins" other than these resins. Examples of other resins include polyethylene terephthalate resins, (meth)acrylic resins, polyvinyl alcohol resins, polycarbonate resins, acetal resins, polybutylene terephthalate resins, fluororesins, and thermosetting resins (e.g., phenolic resins, melamine resins, urea resins, polyurethane resins, epoxy resins, and unsaturated polyester resins). Waste plastics include a wide variety of resins. For example, the first waste plastic may contain a second resin, a third resin, and other resins in addition to the first resin. Similarly, the second waste plastic may contain a first resin, a third resin, and other resins in addition to the second resin. The third waste plastic may contain a first resin, a second resin, and other resins in addition to the third resin. Therefore, by pyrolyzing a mixture in which the ratio (mass ratio) of the chlorine atom content to the nitrogen atom content in the total amount of resin contained in the first waste plastic, the second waste plastic, and the third waste plastic is adjusted, specifically, by pyrolyzing a mixture that satisfies the relationship of the above formula (Mathematical formula 10), it is believed that the reaction between the second resin (polyvinyl chloride polymer) and the third resin (polyamide polymer) will proceed smoothly, making it easier to generate specific organic compounds. As a result, it is believed that the amount of inorganic chlorine generated will be further reduced.

[0029] (Chlorine and nitrogen atom content) In the process of obtaining the mixture according to this embodiment, from the viewpoint of easily generating specific organic chlorine compounds and further reducing the amount of inorganic chlorine generated when the mixture is pyrolyzed, it is preferable that the chlorine atom content and the nitrogen atom content in the total amount of resin contained in the first waste plastic, the second waste plastic and the third waste plastic are each within the following ranges. The content of chlorine atoms is preferably from 0.01% by mass to 20% by mass, and the content of nitrogen atoms is preferably from 0.01% by mass to 20% by mass.

[0030] It is believed that most of the nitrogen atoms contained in the total resin are nitrogen atoms derived from -NH groups in the polyamide. For example, the nitrogen atoms contained in the additives and pigments in each waste plastic are in very low concentration and do not affect the content of nitrogen atoms derived from -NH groups. The nitrogen atom content in the total resin can be measured using a CHN elemental analyzer (manufactured by elementar, product number: vario EL cube) or a total nitrogen trace analyzer (manufactured by Nitto Seiko Analytech, product number: TN-2100H). The content of chlorine atoms in the total amount of resin can be measured using (a) a combustion apparatus and (b) an ion chromatography analyzer described in the Examples. In addition, when waste plastics whose components are specified are used in the process of obtaining the mixture according to this embodiment, the nitrogen atom content and chlorine atom content in the total amount of resin can be calculated from the specified components.

[0031] The total content of the first waste plastic, the second waste plastic, and the third waste plastic in the mixture is preferably 70% by mass or more, preferably 80% by mass or more, and more preferably 90% by mass or more. The upper limit of the total content of the first waste plastic, the second waste plastic, and the third waste plastic relative to the total amount of the mixture is 100% by mass.

[0032] The method for obtaining the mixture is not particularly limited, but includes a method of mixing the first waste plastic, the second waste plastic, and the third waste plastic by a known method. As a mixing means, for example, a known mixing device can be used. The process for obtaining the mixture may be a process of mixing the first waste plastic, the second waste plastic, the third waste plastic, and other materials as necessary, or a process of obtaining a mixture in which these waste plastics and other materials are mixed in advance. In the step of obtaining a mixture, the size and shape of each waste plastic are not particularly limited. The size and shape of each waste plastic are determined according to the specifications of the pyrolysis device used for pyrolyzing the mixture. Each waste plastic is preferably in the form of pellets.

[0033] This embodiment does not exclude the mixture containing other materials other than the first waste plastic, the second waste plastic, and the third waste plastic. Examples of the other materials include waste plastics other than the first waste plastic, the second waste plastic, and the third waste plastic (hereinafter also referred to as other waste plastics), and various additives. Examples of other waste plastics include the above-mentioned "other resins."

[0034] <Pyrolysis process> The pyrolysis step is a step of generating a pyrolysis product by pyrolyzing the mixture obtained in the step of obtaining a mixture. The pyrolysis product is produced by pyrolyzing the mixture obtained in the step of obtaining a mixture in a known pyrolysis device (for example, a pyrolysis furnace).

[0035] (Conditions for pyrolysis) The temperature of the pyrolysis in the pyrolysis step varies depending on the types and contents of the first resin, second resin, and third resin contained in the mixture, but is preferably 580° C. or higher and 680° C. or lower. The mixture is introduced into a pyrolysis device and pyrolyzed. The residence time of the mixture in the pyrolysis device is preferably 5 seconds or more and 15 seconds or less.

[0036] The pyrolysis product produced in the pyrolysis step contains a light olefin-containing gas and organic chlorine. Specifically, the pyrolysis product produced in the pyrolysis step contains a light olefin-containing gas, organic chlorine, and inorganic chlorine, and it is preferable that the organic chlorine is more than the inorganic chlorine.

[0037] In the production method according to this embodiment, it is preferable to further include a separation step of cooling the pyrolysis product produced in the pyrolysis step and separating it into a light olefin-containing gas, an oil component, and a water component. The oil component separated in the separation step contains organic chlorine, and the water component separated in the separation step contains inorganic chlorine.

[0038] <Separation process> The separation step is carried out, for example, using a cooling device. The pyrolysis product supplied to the cooling device is cooled, for example, to about 60° C. By this cooling, the non-condensable gas components contained in the pyrolysis product are separated as a light olefin-containing gas, and the condensable gas components contained in the pyrolysis product are separated into an oil component and a water component. The oil components separated in the separation step include, for example, oil components (e.g., hydrocarbon oils) derived from the raw material of the first resin and specific organic chlorine compounds produced by the reaction of polyvinyl chloride with polyamide in the thermal cracking device. From the viewpoint of effective utilization of resources, the oil component separated in the separation step is preferably returned to the pyrolysis device and used as fuel for pyrolyzing waste plastics. The water component separated in the separation process contains inorganic chlorine gas (hydrogen chloride, hypochlorous acid, etc.) generated by the thermal decomposition of the second resin. Usually, inorganic chlorine gas is dissolved in water and separated as hydrochloric acid, etc.

[0039] In the production method according to this embodiment, it is preferable that the content C1 of the organic chlorine in the oil component satisfies the following mathematical formulas (Mathematical Formula 1) and (Mathematical Formula 2). The organic chlorine content C1 = (organic chlorine content in the oil component / total content of chlorine atoms) × 100 ≧ 10.0 ... (Equation 1) Total content of chlorine atoms = (content of the organic chlorine in the oil component) + (content of the inorganic chlorine in the water component) ... (Equation 2) (In the above formulas (1) and (2), The unit of organic chlorine content in the oil component is [g], The unit of inorganic chlorine content in the water component is [g], The unit of the total chlorine atom content is [g], The unit of the organic chlorine content C1 is [mass%].)

[0040] The content C1 of the organic chlorine in the oil component more preferably satisfies the following formula (Mathematical Formula 11), and further preferably satisfies the following formula (Mathematical Formula 12). The organic chlorine content C1 = (organic chlorine content in the oil component / total content of chlorine atoms) × 100 ≧ 20.0 ... (Equation 11) The organic chlorine content C1 = (organic chlorine content in the oil component / total content of chlorine atoms) × 100 ≧ 30.0 ... (Equation 12)

[0041] In the production method according to this embodiment, it is preferable that the content C2 of inorganic chlorine in the water component satisfies the following mathematical formulas (Mathematical Formula 2) and (Mathematical Formula 3). The inorganic chlorine content C2=(the inorganic chlorine content in the water component / the total content of chlorine atoms)×100≦90.0…(Equation 3) Total content of chlorine atoms = (content of the organic chlorine in the oil component) + (content of the inorganic chlorine in the water component) ... (Equation 2) (In the above formulas (2) and (3), The unit of organic chlorine content in the oil component is [g], The unit of inorganic chlorine content in the water component is [g], The unit of the total chlorine atom content is [g], The unit of inorganic chlorine content C2 is [mass%].)

[0042] The content C2 of inorganic chlorine in the water component more preferably satisfies the following formula (Mathematical Formula 31), and further preferably satisfies the following formula (Mathematical Formula 32). The content of inorganic chlorine C2=(the inorganic chlorine in the water component / total amount of chlorine atoms)×100≦80.0 (Equation 31) The content of inorganic chlorine C2=(the inorganic chlorine in the water component / total amount of chlorine atoms)×100≦70.0 (Equation 32)

[0043] In the above formula, the organic chlorine content in the oil component, the organic chlorine content C1, the inorganic chlorine content in the water component, the inorganic chlorine content C2, and the total content of chlorine atoms are measured by the method described in the Examples.

[0044] In the production method according to this embodiment, the light olefin-containing gas contained in the pyrolysis product is preferably supplied to a petrochemical process for use. Petrochemical processes include, for example, ethylene production facilities, propylene production facilities, and gas recovery units. By light olefin gas is meant ethylene gas and propylene gas. In the production method according to this embodiment, the light olefin-containing gas contained in the pyrolysis product can be used as a gas that can be recycled as a plastic raw material (recycle gas).

[0045] FIG. 1 is a schematic diagram of a production apparatus 100 for producing a pyrolysis product of waste plastic that can be used to carry out the production method according to this embodiment. The waste plastic pyrolysis product manufacturing apparatus 100 includes a pyrolysis unit 10, a cooling unit 12, a dust removal unit 14, a cleaning unit 16, a storage drum 18, and an olefin purification unit 19. The pyrolysis unit 10, the cooling unit 12, the dust removal unit 14, the cleaning unit 16, the storage drum 18, and the olefin purification unit 19 are all known devices.

[0046] The pyrolysis device 10 generates pyrolysis products by pyrolyzing waste plastics introduced into the pyrolysis device 10. The pyrolysis products are discharged from the top of the pyrolysis device 10 and supplied to the cooling device 12 through a pipe L1.

[0047] The cooling device 12 includes a pipe L7 for supplying water and a cooling tower as a cooling means. A valve V2 for adjusting the flow rate of the water is disposed in the pipe L7. Pipes L10 and L20, through which the oil component and water component separated by cooling the pyrolysis product are discharged, are connected to the bottom of the cooling device 12. The light olefin-containing gas separated by cooling the pyrolysis product is discharged from the cooling device 12 and supplied to the dust remover 14 through the pipe L2.

[0048] The storage drum 18 stores the oil component separated in the cooling device 12. The storage drum 18 and the thermal cracking device 10 are connected by a pipe L8. A valve V1 for adjusting the flow rate of the oil component is disposed in the pipe L8. The oil component stored in the storage drum 18 is supplied to the thermal decomposition device 10 through a pipe L8 and is used as fuel for thermally decomposing waste plastics.

[0049] The dust remover 14 includes a pipe L3 for supplying water and a scrubber as a dust remover. Examples of the scrubber include a Venturi scrubber and a jet scrubber. The light olefin-containing gas from which dust has been removed by the dust remover 14 is supplied to the scrubbing device 16 through a pipe L4.

[0050] The scrubbing device 16 includes a scrubbing tower as a scrubbing means. An example of the scrubbing tower is a caustic soda scrubbing tower. The scrubbing water used for scrubbing the light olefin-containing gas is discharged from the bottom of the scrubbing device 16 and is supplied again to the scrubbing device 16 through a pipe L6. A valve V3 for adjusting the flow rate of the scrubbing water is disposed in the pipe L6. The light olefin-containing gas from which acidic gases such as inorganic chlorine have been removed (cleaned) by the cleaning device 16 is supplied to an olefin purification device 19 through a pipe L5. A valve V4 for adjusting the flow rate of the light olefin-containing gas is disposed in the pipe L5.

[0051] The olefin refinery 19 is a device that refines olefins such as ethylene and propylene from a light olefin-containing gas.

[0052] The pyrolysis product manufacturing apparatus 100 shown in FIG. 1 is structured so that the oil components separated in the cooling device 12 are stored in a storage drum 18 and then supplied to the pyrolysis device 10 to be used as fuel for pyrolyzing waste plastic.

[0053] The first waste plastic, the second waste plastic, and the third waste plastic used in the manufacturing method according to this embodiment will be described.

[0054] (First waste plastic) The first waste plastic is waste plastic containing, as a main component, a first resin derived from at least one of polyethylene, polypropylene, and polystyrene. The first resin derived from polyethylene is a resin whose main component is a polyethylene-based polymer, the first resin derived from polypropylene is a resin whose main component is a polypropylene-based polymer, and the first resin derived from polystyrene is a resin whose main component is a polystyrene-based polymer.

[0055] Examples of polyethylene polymers include ethylene homopolymers (such as low density polyethylene and high density polyethylene) and copolymers of ethylene with other monomers (such as ethylene-olefin copolymers). Examples of polypropylene-based polymers include propylene homopolymers and copolymers of propylene with other monomers (such as propylene-olefin copolymers). The polystyrene-based polymer includes a styrene homopolymer and a copolymer of styrene and another monomer (such as a styrene-(meth)acrylic copolymer, an AS resin, and an ABS resin). (Meth)acrylic means acrylic or methacrylic. However, vinyl chloride-ethylene copolymer and vinyl chloride-propylene copolymer are not considered to be polyethylene-based polymers and polypropylene-based polymers, respectively, but are considered to be polyvinyl chloride-based polymers. Therefore, both vinyl chloride-ethylene copolymer and vinyl chloride-propylene copolymer are classified as the second resin. Vinyl chloride-styrene copolymers are not considered to be styrene-based polymers, but are considered to be polyvinyl chloride-based polymers. Therefore, vinyl chloride-styrene copolymers are classified as the second resin. The first resin may be used alone or in combination of two or more kinds. The first waste plastic may be used alone or in combination of two or more kinds.

[0056] The total content of polyethylene-based polymer, polypropylene-based polymer, and polystyrene-based polymer in the first resin is preferably 50 mass% or more, more preferably 70 mass% or more, even more preferably 80 mass% or more, even more preferably 90 mass% or more, and even more preferably 95 mass% or more. In the first resin, the total content of the polyethylene polymer and the polypropylene polymer with respect to the total content of the polyethylene polymer, the polypropylene polymer and the polystyrene polymer is preferably 90% by mass or more, more preferably 95% by mass or more. A larger total content of the polyethylene polymer and the polypropylene polymer in the first resin is preferable because the larger the amount of ethylene gas and propylene gas that can be recycled as plastic raw materials can be produced.

[0057] (Second waste plastic) The second waste plastic is waste plastic containing, as a main component, a second resin derived from polyvinyl chloride. The second resin derived from polyvinyl chloride is a resin containing a polyvinyl chloride polymer as a main component. Examples of polyvinyl chloride polymers include vinyl chloride homopolymers, vinylidene chloride homopolymers, and copolymers of vinyl chloride with other monomers (e.g., vinyl chloride-ethylene copolymers, vinyl chloride-propylene copolymers, vinyl chloride-butadiene copolymers, vinyl chloride-vinyl acetate copolymers, vinyl chloride-styrene copolymers, vinyl chloride-vinylidene chloride copolymers, vinyl chloride-(meth)acrylic copolymers, and vinyl chloride-acrylonitrile copolymers). The second resin may be used alone or in combination of two or more kinds. The second waste plastic may be used alone or in combination of two or more kinds. The content of the polyvinyl chloride polymer in the second resin is preferably 50% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, and even more preferably 95% by mass or more.

[0058] (Third waste plastic) The third waste plastic is waste plastic that contains as its main component a third resin derived from polyamide, also known as nylon. The third resin derived from polyamide is a resin containing a polyamide-based polymer as a main component. Polyamide-based polymers include nylon and aramid. In general, polyamides containing an aliphatic backbone are collectively called nylons, and polyamides composed only of an aromatic backbone are collectively called aramids. Nylons include aliphatic polyamides (such as nylon 6, nylon 11, nylon 12, nylon 46, nylon 66, etc.) and semi-aromatic polyamides (such as nylon 6T, nylon 6I, nylon 9T, and nylon M5T, etc.). Nylon 6T is a nylon synthesized by condensation polymerization of hexamethylenediamine and terephthalic acid. Nylon 6I is a nylon synthesized by condensation polymerization of hexamethylenediamine and isophthalic acid. Nylon 9T is a nylon synthesized by condensation polymerization of nonanediamine and terephthalic acid. Nylon M5T is a nylon synthesized by condensation polymerization of methylpentadiamine and terephthalic acid. The third resin may be used alone or in combination of two or more kinds. The third waste plastic may be used alone or in combination of two or more kinds. The content of the polyamide polymer in the third resin is preferably 50% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, and even more preferably 95% by mass or more.

[0059] The first waste plastic, the second waste plastic, and the third waste plastic may each contain a filler as an inorganic substance. The type of the filler is not particularly limited. The size of the filler is usually micro-sized or nano-sized. The content of the filler contained in each waste plastic is preferably 30% by mass or less, more preferably 15% by mass or less, and further preferably 7.5% by mass or less.

[0060] It is preferable to use the first waste plastic, the second waste plastic, and the third waste plastic, each of which clearly specifies the components contained in the respective waste plastics (e.g., the first resin, the second resin, the third resin, etc.) and the amount of each component. Currently, the components contained in waste plastics vary greatly between industrial waste and general waste, and waste plastics contain a wide variety of resins. In addition, waste plastics may contain components other than plastic components (such as metals and glass). Therefore, it is difficult to accurately identify the plastic components (especially copolymer components) through analysis. Therefore, by using waste plastics whose components are clearly stated, it becomes easier to classify the waste plastics. Also, by clearly indicating the components, unknown components are prevented from being pyrolyzed. Therefore, the pyrolysis equipment can be operated stably. In addition, the waste plastics may be classified into first waste plastics, second waste plastics, and third waste plastics by analyzing the components contained in each waste plastic, and the components contained in each waste plastic and their amounts may be identified. The components contained in each waste plastic are analyzed by known analytical means (e.g., infrared absorption spectroscopy, infrared absorption spectroscopy, etc.) using multiple known analytical devices such as an infrared spectrophotometer (IR), a Fourier transform infrared spectrophotometer (FR-IR), a nuclear magnetic resonance analyzer (NMR) and a gas chromatograph. 1 H-NMR spectrum, 13 It can be analyzed by C-NMR spectroscopy, gas chromatography, etc. In addition, the components contained in each waste plastic may be analyzed using a resin discrimination handy sensor (manufactured by Ricoh Company, Ltd., product number: RICOH HANDY PLASTIC SENSOR B150).

[0061] [Modifications of the embodiment] When the production method according to the first embodiment includes a separation step, the oil component separated in the separation step may be pyrolyzed together with the mixture obtained in the step of obtaining a mixture. That is, the pyrolysis step according to the first embodiment may be a step of introducing the oil component separated in the separation step into a pyrolysis device and pyrolyzing the oil component together with the mixture obtained in the step of obtaining a mixture. The method for producing a pyrolysis product according to one embodiment does not need to include a step of obtaining a mixture. In one embodiment, a method for producing a pyrolysis product may generate a pyrolysis product by introducing each waste plastic into a pyrolysis device and pyrolyzing it (i.e., pyrolyzing each waste plastic while they coexist in the pyrolysis device) so that the content of the first waste plastic is 70 mass% or more (preferably 90 mass% or more) of the total amount of the first waste plastic, the second waste plastic, and the third waste plastic.

[0062] The present invention is not limited to the above-described embodiment, and may include modifications and improvements within the scope of the present invention. EXAMPLES

[0063] EXAMPLES Hereinafter, examples of the present invention will be described, but the present invention is not limited to these examples.

[0064] [Structural analysis of organic chlorine compounds] In order to confirm that a specific organic chlorine compound was produced by the reaction between polyvinyl chloride (second resin) and polyamide (third resin), the following structural analyses 1 to 3 were carried out.

[0065] <Preparation of Evaluation Samples (a) to (c)> Pellets of polyvinyl chloride (PVC) and pellets of polyamide (PA) were prepared. Nylon 6 was used as the polyamide (PA). Polyvinyl chloride (PVC) and polyamide (PA) were weighed out in the mass ratios shown in Table 1 and pulverized using a freeze pulverizer. The pulverized PVC and PA were mixed to prepare samples (a) to (c) for pyrolysis GC-MS measurement.

[0066] <Measurement procedure> Each sample was weighed into a sample cup and attached to the pyrolysis apparatus. The weight of the sample was adjusted for each sample so that the amount of polyvinyl chloride introduced into the pyrolysis GC-MS was constant (100 μg). Next, the sample cup was dropped into the pyrolysis apparatus, and the GC-MS measurement was started at the same time.

[0067] <Equipment used> Pyrolysis equipment: Frontier Labs "EGA / PY-3030D" Gas chromatograph mass spectrometer (GC-MS): Agilent "8890B / 5977B" Column: Agilent "HP-5ms UI" (length 30m x inner diameter 0.25mm x film thickness 0.25 μm)

[0068] <Pyrolysis GC-MS conditions> Pyrolysis temperature: 650℃ Split ratio: 50:1 Carrier gas (He) flow rate: 1 mL / min GC oven temperature: The temperature was increased from 50° C. (2 min) to 320° C. at a rate of 10° C. / min, and the temperature was maintained at 320° C. for 10 min.

[0069] <Structural analysis 1> The mass spectrum of the characteristic pyrolysis products of sample (c) is shown in FIG. As shown in FIG. 3, characteristic signals were observed at m / z=133, m / z=135, m / z=114, and m / z=154 from the pyrolysis product of sample (c). In pyrolysis GC-MS measurement, several dozens of pyrolysis products are actually detected from sample (c). Among them, we focused on the components with the mass spectrum in Figure 3 (specifically, the signals at m / z = 133, m / z = 135, m / z = 114, and m / z = 154) because these are characteristic components that are not detected when either simple PA or simple PVC is pyrolyzed. In FIG. 3, (i) indicates m / z=133, and (i * The fragment ion signal with m / z = 135 shown in (c) was observed with an intensity of approximately 3:1, indicating an isotope ratio of chlorine atoms (3:1), and therefore the pyrolysis product of sample (c) contains chlorine atoms. In Figure 3, the fragment ion (ii) is presumed to be an ion derived from the thermal decomposition product of PA, and therefore the thermal decomposition product of sample (c) contains a partial structure derived from the thermal decomposition product of PA (Reference: Pyrolysis-GC / MS Data Book of Synthetic Polymers: Pyrograms, Thermograms and MS of Pyrolyzates Elsevier; 1st edition (2011 / 10 / 27)). From the above, the pyrolysis products of sample (c) shown in FIG. 3 were presumed to be organic chlorine compounds, which are reaction products of PVC and PA.

[0070] <Structural analysis 2> Figure 4 shows the extracted ion chromatograms of m / z=133 obtained by pyrolysis GC-MS measurement of samples (a) to (c). In Figure 4, the peaks of the components defined in Structural Analysis 1 are indicated with (*). From the area of ​​the peak (*), the area ratio of sample (b) was calculated using the area of ​​the peak (*) of sample (a) as the standard using the following formula (Math 1X), and the area ratio of sample (c) was calculated using the following formula (Math 2X). Area ratio of sample (b) = (area of ​​peak (*) of sample (b) / area of ​​peak (*) of sample (a)) ... (equation 1X) Area ratio of sample (c) = (area of ​​peak (*) of sample (c) / area of ​​peak (*) of sample (a)) ... (equation 2X)

[0071] <Structural analysis 3> The area ratio of the peaks of the target components of sample (a), sample (b) and sample (c) obtained in structural analysis 2 was converted into the organic chlorine ratio in the organic chlorine compounds. The results are shown in Table 1. The graph in Figure 5 obtained in the experiment was used for conversion to the organic chlorine ratio. Figure 5 is a graph showing the relationship between the polyamide ratio (relative to PVC) and the organic chlorine ratio (mass%). The polyamide ratio (relative to PVC) is the ratio (mass basis) of the PA content to the PVC content, and the organic chlorine ratio (mass%) is the ratio (mass basis) of the organic chlorine content to the total content of PA and PVC. In FIG. 5, the organic chlorine ratio (78.8 mass%, peak area 149 when PVC:PA = 1:4 (mass ratio)) was taken as positive, and the peak area ratio of the target component obtained in structure analysis 2 was linearly converted into the organic chlorine ratio.

[0072] [Table 1]

[0073] From the results of structural analyses 1 to 3, it was estimated that a specific organic chlorine compound was produced by the reaction between polyvinyl chloride and polyamide. In addition, by comparing the organic chlorine ratios of samples (a) to (c), it was estimated that by increasing the ratio of polyamide to polyvinyl chloride, more organic chlorine was produced.

[0074] [Configuration of the experimental equipment used for evaluation] The evaluations of Examples 1 and 2 and Comparative Example 1 were carried out using an experimental apparatus 101 shown in Fig. 2. Fig. 2 shows a schematic diagram of the experimental apparatus 101. The experimental apparatus 101 is an improved version of the pyrolysis product production apparatus 100 shown in FIG. 1, which has been miniaturized for experimental purposes. The experimental apparatus 101 includes a pyrolysis device 10A, three impingers 20 connected in series, a flow path L1A into which waste plastic is introduced, a flow path L2A connecting the pyrolysis device 10A and the impingers 20, a flow path 21 connecting each impinger 20, an outlet 23 for recovering residues generated by pyrolysis, and a flow path 22 for discharging light olefin-containing gas. A flow meter 24 is provided in the flow path 22. Cooling water W is stored in each impinger 20.

[0075] Example 1 A first waste plastic (2100 g) containing polyethylene (PE) and polypropylene (PP) in a 1:1 (mass ratio), a second waste plastic (140 g) containing polyvinyl chloride (PVC), and a third waste plastic (560 g) containing polyamide (PA) were prepared and mixed to obtain mixture 1 (2800 g). Nylon 6 was used as the polyamide (PA). As the first waste plastic, the second waste plastic, and the third waste plastic, waste plastics whose components were clearly stated were used. Polyethylene (PE) and polypropylene (PP) correspond to the first resin, polyvinyl chloride (PVC) corresponds to the second resin, and polyamide (PA) corresponds to the third resin. The content of the first resin in the first waste plastic is 100% by mass. The content of the second resin in the second waste plastic is 80% by mass. The content of the third resin in the third waste plastic is 100% by mass. The waste plastics were all in the form of pellets. Mixture 1 was pyrolyzed under the following conditions to produce pyrolysis products. -conditions- Equipment: Pyrolysis equipment 10A (volume 8L) included in the experimental equipment ·Thermal decomposition temperature: 650℃ Pressure: 2kPa Residence time of mixture 1 in pyrolysis device 10A: 8 seconds

[0076] Next, the pyrolysis products generated in the pyrolysis device 10A were sequentially aerated through cooling water stored in three impingers 20 under the following conditions to condense the oil and water components. The cooling water W in the impingers 20 was adjusted to 0°C by ice-cooling from the outside. Thereafter, the condensate condensed above the cooling water W of the impinger 20 was left to stand for one day to separate into an oil layer and a water layer, after which the oil layer was recovered as an oil component and the water layer was recovered as a water component. The gas (light olefin-containing gas) that was not condensed by being passed through the water was collected from a flow path 22. In addition, the residue generated by the thermal decomposition was also collected from an outlet 23. -conditions- Cooling water in each impinger 20: 900mL -Cooling water temperature: 0℃

[0077] Example 2 The same first waste plastics, second waste plastics, and third waste plastics as those in Example 1 were used. In Example 2, a pyrolysis product was produced in the same manner as in Example 1, except that the first waste plastic, the second waste plastic, and the third waste plastic were mixed in the ratio shown in Table 2 to obtain mixture 2. Thereafter, in the same manner as in Example 1, the oil component and the water component were condensed from the pyrolysis product, and then the oil component and the water component were recovered.

[0078] Comparative Example 1 The same first and second waste plastics as those in Example 1 were used. In Comparative Example 1, a pyrolysis product was produced in the same manner as in Example 1, except that the first waste plastic and the second waste plastic were mixed in the ratio shown in Table 2 to obtain mixture 1C. Thereafter, in the same manner as in Example 1, the oil component and the water component were condensed from the pyrolysis product, and then the oil component and the water component were recovered.

[0079] <Evaluation> (Light olefin-containing gas) The gas (light olefin-containing gas) recovered from the flow path 22 was confirmed to contain a hydrocarbon fraction by gas chromatography. The gas chromatographic conditions were as follows: -conditions- Measuring instrument: Gas chromatograph (Agilent, product number: 7890A) Detector: FID (Flame Ionization Detector) Column: Two Agilent columns, part number "123-1015" and part number "19091P-S12", were connected in this order, and a gas containing light olefins was passed through the part number "123-1015" side. Detector temperature: 250℃

[0080] (Ratio of nitrogen atom content to chlorine atom content (nitrogen atom content / chlorine atom content)) The mixtures used in Examples 1 and 2 and Comparative Example 1 were used to measure the nitrogen atom content (N atom content) and chlorine atom content (Cl atom content) in the total amount of resin by the following method. From the obtained values, the ratio of the nitrogen atom content to the chlorine atom content (N atom content / Cl atom content) was calculated. The results are shown in Table 2. The nitrogen atom content was measured using a CHN elemental analyzer (manufactured by Elementar, product number: vario EL cube). The content of chlorine atoms was measured using the following device. (a) Combustion equipment Equipment: Nitto Seiko Analytech Co., Ltd., product name "AQF-2100H", (b) Ion chromatography analyzer Equipment: Thermo Fisher Scientific, product name "DIONEX Integrion RFIC" Columns: "IonPac AG12A" and "IonPac AS12A"

[0081] (The content of organic chlorine in the oil component C1 and the content of inorganic chlorine in the water component C2) The organic chlorine content C1 in the oil component and the inorganic chlorine content C2 in the water component obtained in each example were determined by the following methods. The results are shown in Table 2.

[0082] (1) Total chlorine atom analysis The total content of chlorine atoms in the recovered oil and water components was measured using the following device. (a) Combustion equipment Equipment: Nitto Seiko Analytech Co., Ltd., product name "AQF-2100H", (b) Ion chromatography analyzer Equipment: Thermo Fisher Scientific, product name "DIONEX Integrion RFIC" Columns: "IonPac AG12A" and "IonPac AS12A"

[0083] (2) Inorganic chlorine analysis The content of inorganic chlorine in the recovered water component was measured using the following device. The content C2 of inorganic chlorine in the water component was calculated from the above formula (Math 3). Equipment: Thermo Fisher Scientific, product name "DIONEX ICS2000" Columns: "IonPac AG11HG" and "IonPac AS11HG" (3) Organic chlorine analysis The organic chlorine content in the recovered oil component was calculated from the difference between the total content of chlorine atoms and the inorganic chlorine content. The organic chlorine content C1 in the oil component was calculated from the above formula (Math 1).

[0084] [Table 2]

[0085] Examples 1 and 2, in which a mixture containing a first waste plastic, a second waste plastic, and a third waste plastic in the ratios shown in Table 2 was thermally decomposed, had a higher organic chlorine content C1 and a lower inorganic chlorine content C2 than Comparative Example 1, which did not contain polyamide (third waste plastic) in the mixture. In addition, comparing Example 1 with Example 2, by increasing the ratio of the content of the third waste plastic to the content of the second waste plastic (content of the third waste plastic / content of the second waste plastic), the content of organic chlorine became higher than C1 and the content of inorganic chlorine C2 became lower. From the above results, it was found that, according to this embodiment, the amount of inorganic chlorine gas produced can be reduced when waste plastics containing polyvinyl chloride are thermally decomposed. [Industrial Applicability]

[0086] The method for producing the pyrolysis products of waste plastics of the present invention is industrially applicable since it is a technology that can reduce the amount of corrosive hydrogen chloride produced and can reuse the light olefin-containing gas contained in the pyrolysis products as a plastic raw material. [Explanation of symbols]

[0087] 10, 10A... pyrolysis apparatus, 12... cooling apparatus, 14... dust removal apparatus, 16... cleaning apparatus, 18... storage drum, 19... olefin purification apparatus, 20... impinger, 21, 22... flow path, 23... discharge outlet, 24... flow meter, 100... pyrolysis product manufacturing apparatus, 101... experimental apparatus, L1, L2, L3, L4, L5, L6, L10, L20... piping, L1A, L2A... flow path.

Claims

1. A step of obtaining a mixture of a first waste plastic mainly comprising a first resin derived from at least one of polyethylene, polypropylene, and polystyrene, a second waste plastic mainly comprising a second resin derived from polyvinyl chloride, and a third waste plastic mainly comprising a third resin derived from polyamide, The process includes a thermal decomposition step in which the aforementioned mixture is thermally decomposed to produce thermal decomposition products. With respect to the total amount of the first waste plastic, the second waste plastic, and the third waste plastic contained in the mixture, The content of the first waste plastic is 70% by mass or more. A method for producing thermal decomposition products from waste plastics.

2. The pyrolysis product produced in the pyrolysis step includes a light olefin-containing gas and organic chlorine. A method for producing thermal decomposition products of waste plastics as described in claim 1.

3. The ratio of the content of the third waste plastic to the content of the second waste plastic (content of the third waste plastic / content of the second waste plastic) is 0.5 or more by mass. A method for producing thermal decomposition products of waste plastics as described in claim 1.

4. With respect to the total amount of the first waste plastic, the second waste plastic, and the third waste plastic contained in the mixture, The content of the second waste plastic is 0.01% by mass or more and 10% by mass or less. The content of the third waste plastic is 0.01% by mass or more and 20% by mass or less. A method for producing thermal decomposition products of waste plastics as described in claim 1.

5. With respect to the total amount of the first waste plastic, the second waste plastic, and the third waste plastic contained in the mixture, The content of the first waste plastic is 90% by mass or more. A method for producing thermal decomposition products of waste plastics as described in claim 1.

6. With respect to the total amount of the first waste plastic, the second waste plastic, and the third waste plastic contained in the mixture, The content of the second waste plastic is 0.01% by mass or more and 2.0% by mass or less. The content of the third waste plastic is 0.01% by mass or more and 8.0% by mass or less. A method for producing thermal decomposition products of waste plastics as described in claim 5.

7. The process further includes a separation step in which the pyrolysis product generated in the pyrolysis step is cooled to separate it into a light olefin-containing gas, an oil component, and a water component. The aforementioned oil component contains organochlorine, The aforementioned water component contains inorganic chlorine. A method for producing thermal decomposition products of waste plastics as described in claim 1.

8. The content of the organic chlorine in the oil component C １ The following equations (Equation 1) and (Equation 2) are satisfied: A method for producing thermal decomposition products of waste plastics according to claim 7. The content of the aforementioned organic chlorine C １ = (Content of organic chlorine in the oil component / Total content of chlorine atoms) × 100 ≥ 10.0 ... (Equation 1) Total amount of chlorine atoms = (amount of organic chlorine in the oil component) + (amount of inorganic chlorine in the water component) ... (Equation 2) (In the above formulas (Equation 1) and (Equation 2), The unit for the content of organochlorines in the oil component is [g]. The unit for the inorganic chlorine content in the water component is [g]. The unit for the total amount of chlorine atoms is [g]. Organic chlorine content C １ The unit is [mass %].

9. The content of inorganic chlorine in the water component C ２ The following equations (Equation 2) and (Equation 3) are satisfied: A method for producing thermal decomposition products of waste plastics according to claim 7. The inorganic chlorine content C ２ = (Content of inorganic chlorine in the water component / Total content of chlorine atoms) × 100 ≤ 90.0 ... (Equation 3) Total amount of chlorine atoms = (amount of organic chlorine in the oil component) + (amount of inorganic chlorine in the water component) ... (Equation 2) (In the above formulas (Equation 2) and (Equation 3), The unit for the content of organochlorines in the oil component is [g]. The unit for the inorganic chlorine content in the water component is [g]. The unit for the total amount of chlorine atoms is [g]. Inorganic chlorine content C ２ The unit is [mass %].

10. The light olefin-containing gas contained in the pyrolysis product is supplied and used in a petrochemical process. A method for producing thermal decomposition products of waste plastics according to any one of claims 7 to 9.

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