CN115516016A - Regeneration method of waste polystyrene product - Google Patents
Regeneration method of waste polystyrene product Download PDFInfo
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- CN115516016A CN115516016A CN202180033768.7A CN202180033768A CN115516016A CN 115516016 A CN115516016 A CN 115516016A CN 202180033768 A CN202180033768 A CN 202180033768A CN 115516016 A CN115516016 A CN 115516016A
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- polystyrene
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J11/00—Recovery or working-up of waste materials
- C08J11/04—Recovery or working-up of waste materials of polymers
- C08J11/10—Recovery or working-up of waste materials of polymers by chemically breaking down the molecular chains of polymers or breaking of crosslinks, e.g. devulcanisation
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B09—DISPOSAL OF SOLID WASTE; RECLAMATION OF CONTAMINATED SOIL
- B09B—DISPOSAL OF SOLID WASTE
- B09B3/00—Destroying solid waste or transforming solid waste into something useful or harmless
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B09—DISPOSAL OF SOLID WASTE; RECLAMATION OF CONTAMINATED SOIL
- B09B—DISPOSAL OF SOLID WASTE
- B09B3/00—Destroying solid waste or transforming solid waste into something useful or harmless
- B09B3/50—Destroying solid waste or transforming solid waste into something useful or harmless involving radiation, e.g. electro-magnetic waves
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C15/00—Cyclic hydrocarbons containing only six-membered aromatic rings as cyclic parts
- C07C15/40—Cyclic hydrocarbons containing only six-membered aromatic rings as cyclic parts substituted by unsaturated carbon radicals
- C07C15/42—Cyclic hydrocarbons containing only six-membered aromatic rings as cyclic parts substituted by unsaturated carbon radicals monocyclic
- C07C15/44—Cyclic hydrocarbons containing only six-membered aromatic rings as cyclic parts substituted by unsaturated carbon radicals monocyclic the hydrocarbon substituent containing a carbon-to-carbon double bond
- C07C15/46—Styrene; Ring-alkylated styrenes
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F12/00—Homopolymers and copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an aromatic carbocyclic ring
- C08F12/02—Monomers containing only one unsaturated aliphatic radical
- C08F12/04—Monomers containing only one unsaturated aliphatic radical containing one ring
- C08F12/06—Hydrocarbons
- C08F12/08—Styrene
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J11/00—Recovery or working-up of waste materials
- C08J11/04—Recovery or working-up of waste materials of polymers
- C08J11/10—Recovery or working-up of waste materials of polymers by chemically breaking down the molecular chains of polymers or breaking of crosslinks, e.g. devulcanisation
- C08J11/12—Recovery or working-up of waste materials of polymers by chemically breaking down the molecular chains of polymers or breaking of crosslinks, e.g. devulcanisation by dry-heat treatment only
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B2250/00—Layers arrangement
- B32B2250/24—All layers being polymeric
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B2272/00—Resin or rubber layer comprising scrap, waste or recycling material
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B2307/00—Properties of the layers or laminate
- B32B2307/50—Properties of the layers or laminate having particular mechanical properties
- B32B2307/558—Impact strength, toughness
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B2597/00—Tubular articles, e.g. hoses, pipes
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2325/00—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an aromatic carbocyclic ring; Derivatives of such polymers
- C08J2325/02—Homopolymers or copolymers of hydrocarbons
- C08J2325/04—Homopolymers or copolymers of styrene
- C08J2325/06—Polystyrene
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W30/00—Technologies for solid waste management
- Y02W30/50—Reuse, recycling or recovery technologies
- Y02W30/62—Plastics recycling; Rubber recycling
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W30/00—Technologies for solid waste management
- Y02W30/50—Reuse, recycling or recovery technologies
- Y02W30/82—Recycling of waste of electrical or electronic equipment [WEEE]
Abstract
The present invention addresses the problem of providing a method for recycling waste polystyrene products, which can produce recycled polystyrene having a strength equivalent to that of naphtha-derived polystyrene. The problem is solved by a method for recycling waste polystyrene products, which comprises a step of obtaining recycled styrene monomer from waste polystyrene by subjecting the waste polystyrene products to a thermal decomposition treatment. Preferably, the problem is solved by a method for recycling the waste polystyrene product, wherein the waste polystyrene product comprises a non-colored polystyrene product and a colored polystyrene product.
Description
Technical Field
The present invention relates to a method for regenerating waste polystyrene products.
Background
Among plastics discharged from factories and homes, there are various plastics, and among them, polystyrene is used in many fields such as trays for food packaging, electric appliances, housings for information equipment, heat insulators, and cushioning materials, and accounts for a large proportion of waste plastics. Therefore, it is an important technical problem to regenerate a large amount of discharged waste polystyrene as a resource, and various regeneration methods have been proposed for this purpose.
As a method for recycling waste polystyrene, there is a material recycling method. In the regeneration of the material, the waste polystyrene is recovered, and the polystyrene product is manufactured again through the respective steps of washing, pulverizing and granulating. Various proposals have been made for recycling waste polystyrene (see, for example, patent document 1).
Documents of the prior art
Patent literature
Patent document 1: japanese patent laid-open No. 2020-7424
Disclosure of Invention
Problems to be solved by the invention
However, in recycling a material for producing a polystyrene product by the remelting method, the polystyrene is repeatedly melted to reduce the molecular weight of the polystyrene, which causes a problem of lowering the strength of the polystyrene. In order to obtain strength equivalent to polystyrene obtained by polymerizing a styrene monomer derived from naphtha (hereinafter also referred to as naphtha-derived polystyrene), for example, polystyrene produced by regeneration of a material needs to be reinforced by adding naphtha-derived polystyrene.
Therefore, a new method for regenerating a waste polystyrene product, which is a used polystyrene product, that is, a so-called waste polystyrene product, is desired, in which polystyrene obtained by regenerating the waste polystyrene product (hereinafter, also referred to as regenerated polystyrene) is converted into polystyrene having a strength equivalent to that of polystyrene derived from naphtha, and which can produce regenerated polystyrene.
The object of the present invention is to provide a recycling method for waste polystyrene products, which can produce recycled polystyrene having a strength higher than that of polystyrene produced by recycling a material. Further, since a material recycling of waste polystyrene products causes a hue defect of polystyrene due to scorching of the resin, it is an object to provide a recycling method capable of suppressing the hue defect of polystyrene.
Means for solving the problems
The present inventors have conducted extensive studies in order to solve the above problems, and as a result, have found that the above problems can be solved by chemical regeneration in which styrene monomer is regenerated from recovered waste polystyrene by thermal decomposition, thereby completing the present invention.
That is, the present invention includes the following aspects.
[1] A method for recycling waste polystyrene products, comprising the step of obtaining a recycled styrene monomer from waste polystyrene by subjecting the waste polystyrene products to a thermal decomposition treatment.
[2] The method for recycling a waste polystyrene product as described in [1], wherein the waste polystyrene product comprises a non-colored polystyrene product and a colored polystyrene product.
[3] The method for recycling waste polystyrene products according to [1] or [2], wherein the waste polystyrene products are pulverized to obtain pulverized waste polystyrene products, and the pulverized waste polystyrene products are subjected to thermal decomposition treatment.
[4] The method for recycling waste polystyrene products as described in any one of [1] to [3], wherein the step of obtaining the recycled styrene monomer comprises:
a step of thermally decomposing the waste polystyrene product by using a thermal decomposition device;
supplying the steam generated by the thermal decomposition to a condenser, thereby removing a gas flame component from a thermal decomposition product in which an oil component containing a regenerated styrene monomer and the gas flame component are mixed, to obtain an oil component containing a regenerated styrene monomer; and
and a step of performing distillation purification on the oil component containing the regenerated styrene monomer by using a distillation column to improve the purity of the regenerated styrene monomer.
[5] The method for recycling a waste polystyrene product as recited in [4], further comprising:
removing a solid component from a slurry component generated by the thermal decomposition by using a separator; and
and a step of thermally decomposing the clarified slurry from which the solid component has been removed by using the thermal decomposition device.
[6] The method for recycling waste polystyrene products as recited in any one of [4] and [5], wherein said thermal decomposition device is a thermal decomposition device using microwaves.
[7] The method for recycling waste polystyrene products as described in any one of [1] to [6], wherein the recycled styrene monomer contains at least 1 selected from the group consisting of inorganic substances, aromatic compounds, cyclohexadiene-based compounds and cyclohexene-based compounds in addition to the styrene monomer.
[8] A method for recycling a waste polystyrene product, comprising:
a step of recovering waste polystyrene products;
a step of subjecting the recovered waste polystyrene product to thermal decomposition treatment to obtain a regenerated styrene monomer from the waste polystyrene;
polymerizing the regenerated styrene monomer to obtain regenerated polystyrene; and
and a step of obtaining a regenerated polystyrene product comprising the regenerated polystyrene.
Effects of the invention
According to the present invention, it is possible to provide a method for recycling waste polystyrene products, which can produce recycled polystyrene having improved strength as compared with polystyrene produced by recycling materials.
In addition, in the present invention, scorch of the resin caused by the material regeneration of the waste polystyrene product is not caused, and therefore, according to the present invention, it is possible to provide a method for regenerating a waste polystyrene product, by which a regenerated polystyrene in which a hue defect of the resin is suppressed can be produced.
Drawings
FIG. 1 is a schematic view showing one embodiment of a method for recycling waste polystyrene products according to the present invention.
FIG. 2 is a schematic view showing one embodiment of a process for producing a regenerated styrene monomer in the method for regenerating a waste polystyrene product of the present invention.
FIG. 3 is a schematic view showing another embodiment of the production process of a regenerated styrene monomer in the method for regenerating a waste polystyrene product of the present invention.
Detailed Description
The method for recycling waste polystyrene products of the present invention will be described in detail below, but the following description of the components is an example of one embodiment of the present invention and is not limited to these contents.
(method of regenerating waste polystyrene product of the present invention)
The method for recycling waste polystyrene products of the present invention comprises a step of obtaining recycled styrene monomer from waste polystyrene by subjecting the waste polystyrene products to a thermal decomposition treatment.
The recycling method of the present invention is a chemical recycling method of styrene monomer as a raw material of polystyrene products from waste polystyrene products.
The waste polystyrene is a waste of polystyrene products composed of the regenerated styrene monomer of the present invention or a styrene monomer derived from petroleum, or polystyrene products obtained by material regeneration.
Further, as a preferred embodiment of the method for recycling waste polystyrene products of the present invention, there is a method for recycling waste polystyrene products comprising the following steps 1) to 4).
1) Process for recovering waste polystyrene product (hereinafter, also referred to as recovery Process)
2) A step of obtaining a regenerated styrene monomer from the waste polystyrene by subjecting the recovered waste polystyrene product to a thermal decomposition treatment (hereinafter, also referred to as a process for producing a regenerated styrene monomer)
3) A step of polymerizing the regenerated styrene monomer to obtain regenerated polystyrene (hereinafter, also referred to as a process for producing regenerated polystyrene)
4) A step of obtaining a recycled polystyrene product comprising recycled polystyrene (hereinafter, also referred to as a process for producing a polystyrene product)
In the present invention, the regenerated styrene monomer refers to a regenerated styrene monomer, that is, a styrene monomer obtained from waste polystyrene through a regeneration step.
In the present invention, the recycled polystyrene refers to a recycled polystyrene, that is, a polystyrene obtained by polymerizing a recycled styrene monomer or a polystyrene obtained by recycling a material.
The recycled polystyrene product obtained in the above step 4) (hereinafter, also referred to as a recycled polystyrene product) is supplied to the market. Then, waste recycled polystyrene products such as unnecessary recycled polystyrene products and used recycled polystyrene products are recycled.
The recycled waste recycled polystyrene products are subjected to the thermal decomposition treatment in the step 2). Thereby, the regenerated styrene monomer can be produced again.
In this manner, the recycled polystyrene product produced through the steps 1) to 4) can be subjected to the steps 1) to 4) again to produce a recycled polystyrene product.
According to the present invention, it is possible to repeatedly manufacture waste polystyrene products into recycled polystyrene products, and to establish a recycling-type recycling system for waste polystyrene products.
The outline of the regeneration method of the present invention will be described with reference to fig. 1.
The waste polystyrene product 1 is recovered (recovery step A).
The recovered waste polystyrene products are subjected to the respective steps of thermal decomposition treatment, oil component obtaining step, distillation purification step, and the like to produce the regenerated monomer 2 (regenerated styrene monomer production step B).
The produced regenerated styrene monomer 2 is polymerized to produce regenerated polystyrene 3 (step C for producing regenerated polystyrene).
The produced polystyrene product 4 can be supplied to the recovery step a as the waste polystyrene product 1 when it becomes unnecessary.
The waste polystyrene product 1 is a waste of the polystyrene product 4 obtained by the present invention, a polystyrene product containing a styrene monomer derived from petroleum, or a polystyrene product obtained by material regeneration.
As shown in FIG. 1, according to the recycling method of the present invention, a recycling-type recycling system of waste polystyrene products can be established.
The respective steps 1) to 4) will be described in detail below.
< recovery Process A >
And recycling the waste polystyrene products.
Here, the waste polystyrene product refers to a waste polystyrene product such as an unnecessary polystyrene product and a used polystyrene product.
The recovered waste polystyrene products are subjected to the thermal decomposition treatment in the step 2). The waste polystyrene products subjected to the step 2) may be subjected to the thermal decomposition treatment of the step 2) without any special screening after the recovery.
For example, polystyrene articles also have colored articles, but only non-colored polystyrene articles can be used without any limitation in recycling the material. Colored polystyrene articles (e.g., black polystyrene articles) can only be recycled into articles for specific uses such as hangers.
According to the recycling method of the present invention, a non-colored recycled polystyrene article can be produced from a waste polystyrene article comprising a colored polystyrene article (e.g., a black polystyrene article) and a non-colored polystyrene article without distinguishing the colored polystyrene article (e.g., a black polystyrene article) from the non-colored polystyrene article.
According to the recycling method of the present invention, the non-colored polystyrene product and the colored (colored) polystyrene product can be subjected to the thermal decomposition treatment in the step 2) in a mixed state.
Here, the colored (colored) polystyrene product refers to a polystyrene product in which a colorant such as a pigment is combined for coloring to a color. Examples of the combination include adding and attaching a colored laminate film to a polystyrene substrate.
According to the present invention, it is not necessary to perform an operation of sorting products by color after recycling, and colored polystyrene products can be recycled as well as non-colored polystyrene products. By the present invention, labor associated with the sorting operation after recovery can be reduced. Further, the recycling rate of the waste polystyrene products can be improved, and 100% recycling of styrene from the waste polystyrene products can be expected.
(crushing process)
Before the recovered waste polystyrene products are subjected to the thermal decomposition treatment step, a step of pulverizing the waste polystyrene products to obtain pulverized waste polystyrene may be further provided as necessary.
That is, the waste polystyrene products may be pulverized to obtain pulverized waste polystyrene products, and the pulverized waste polystyrene products may be subjected to the thermal decomposition treatment of the step 2).
< Process B > of producing regenerated styrene monomer
In the present invention, a condensable oil (also referred to as a monomer oil component in the present invention) containing a styrene monomer is obtained from a thermal decomposition product produced by thermally decomposing polystyrene, and the condensable oil is purified to obtain a regenerated styrene monomer. The purity of styrene in the regenerated styrene monomer differs depending on the purification method of the regenerated styrene monomer.
In the present invention, the monomer oil component refers to an oil component containing a styrene monomer.
Preferred embodiments of the regenerated styrene monomer production process B are as follows.
The waste polystyrene product is subjected to thermal decomposition treatment. Thus, the thermal decomposition product mixed with the monomer oil component and the gas flame (gas flare) component is generated in the form of steam. The vapor is condensed and separated to remove the gas flame component, thereby obtaining the monomer oil component. The monomer oil component is distilled and purified to obtain a styrene monomer. Thus, styrene monomer can be produced from waste polystyrene.
That is, as a preferred embodiment of the regenerated styrene monomer production step B, there is a production step including a thermal decomposition treatment step, an oil component obtaining step, and a distillation purification step.
Further, in the present invention, it is more preferable that the production process further includes a separation step after the thermal decomposition treatment step.
Hereinafter, each step constituting the regenerated styrene monomer production step B will be described in detail with reference to fig. 2.
Thermal decomposition process
The recovered waste polystyrene product 1 is subjected to a thermal decomposition treatment.
As shown in FIG. 2, when the waste polystyrene products 1 are thermally decomposed by the thermal decomposition device a, steam (decomposed gas) 10 is generated. The thermal decomposition product obtained in the form of steam comprises a monomer oil component 14 and a gas flame component 15.
Here, the gas flame component refers to a gas component and a coke component.
The type of the thermal decomposition device is not particularly limited as long as the thermal decomposition product containing the monomer oil component 14 and the gas flame component 15 can be obtained from polystyrene as described above, and for example, a thermal decomposition device using microwaves is preferable.
Thermal decomposition device using microwave
The following describes a method for thermally decomposing polystyrene using a thermal decomposition device using microwaves.
The term "microwave" means an electromagnetic wave having a wavelength of 1 m to 1 mm or an electromagnetic wave having a frequency of 300MHz (0.3 GHz) to 300 GHz.
Preferably, microwaves suitable for use in the present invention are electromagnetic waves having a frequency of about 915MHz to about 2450 MHz.
Examples of the microwave source include a magnetron.
The waste polystyrene product subjected to the thermal decomposition treatment is preferably added with a catalyst to initiate microwave thermal decomposition of the waste polystyrene product.
Such a catalyst is not particularly limited as long as it absorbs microwaves, transfers heat to the waste polystyrene products, and contributes to the thermal decomposition reaction of the waste polystyrene products, and may be appropriately selected according to the purpose, and for example, a catalyst containing a compound having a high dielectric loss at the frequency of microwaves is preferable.
Alternatively, the catalyst may be a catalyst composed of carbonaceous residue from a previously performed thermal decomposition reaction, ceramic beads containing a microwave absorbing additive, particles containing a microwave absorbing additive, or a combination thereof. In this case, examples of the microwave absorbing additive include silicon carbide and boron nitride.
Alternatively, the catalyst may be a catalyst composed of a carbon compound containing carbon in an amount of about 80 to about 90 mass%, and examples thereof include graphite.
In the raw material to be subjected to the thermal decomposition treatment after combining the catalyst and the waste polystyrene product, the content of the catalyst is preferably 0.5 to 50% by mass, more preferably 0.5 to 5% by mass, and still more preferably 0.5 to 2.5% by mass.
The thermal decomposition treatment is preferably performed without adding oxygen.
Here, "no oxygen is added" means that no molecular oxygen (O) is added 2 )。
In the thermal decomposition reaction of the present invention, it is preferable that molecular oxygen (O) is not added 2 ) And starting the thermal decomposition treatment when the oxygen content in the thermal decomposition device is a residual amount suitable for thermal decomposition.
Here, the desired content of oxygen remaining in the thermal decomposition device is preferably about 10 vol% or less, and more preferably about 5 vol% or less.
The thermal decomposition device may be provided with an anaerobic means for purging the thermal decomposition device.
Examples of the anaerobic means include the above-mentioned inert gas and fluid.
As the fluid, water may be used.
Examples of the inert gas include argon, nitrogen, and steam.
Further, as the anaerobic means, a vacuum source such as a vacuum pump or a venturi tube may be mentioned.
As the anaerobic means, the above-mentioned inert gas, fluid, vacuum source or a combination thereof may be used.
In the present invention, the steam generated by the initial evaporation of water present in the product can sweep the atmosphere in the thermal decomposition device to achieve anaerobic thermal decomposition.
Therefore, in the present invention, the thermal decomposition treatment is preferably performed under steam purge.
Alternatively, in order to make the appropriate purging of air based on water evaporation reliable, a predetermined amount of water may be added to the waste polystyrene products.
Molecular oxygen (O) 2 ) Although not added to the thermal decomposition apparatus, the waste may contain a large amount of oxygen. In the present invention, if the thermal decomposition reaction is initiated before the initiation of the thermal decomposition reactionWhen the moisture is evaporated and the temperature rises, the air existing in the thermal decomposition device is discharged by the steam generated in the thermal decomposition device, and therefore, the thermal decomposition reaction can be caused in a steam atmosphere without being in the air. The air is expelled, and when an appropriate temperature and internal pressure are reached, the thermal decomposition device is sealed. In the present invention, the thermal decomposition may be carried out not by the thermal decomposition which is carried out under a nitrogen or argon atmosphere and does not contain oxygen at all, which is generally carried out by an anaerobic means, but by the thermal decomposition by steam without introducing additional oxygen.
The waste polystyrene products are heated in the thermal decomposition device by absorbing microwaves and catalysts in the inner wall of the thermal decomposition device using microwaves and catalysts for a time sufficient to generate heat, thereby decomposing polystyrene.
The temperature of the thermal decomposition treatment of the waste polystyrene is preferably about 300 to about 650 c, more preferably about 300 to about 450 c.
As shown in fig. 2, if the waste polystyrene product is thermally decomposed using a thermal decomposition device a using microwaves, the above steam (mixture of the monomer oil component and the gas flame component) 10 is generated. The slurry components remain in the apparatus. The steam 10 is separated by condensation using a condenser c, thereby being separated into a monomer oil component 14 and a gas flame component 15.
When waste polystyrene products are thermally decomposed using the thermal decomposition device a, as shown in fig. 3, thermal decomposition treatment using the thermal decomposition device a may be performed a plurality of times. The steam 10 can be obtained by setting a plurality of thermal decomposition treatment processes (performed 2 times in fig. 3).
By performing thermal decomposition by microwave, it is possible to efficiently and uniformly heat polystyrene in a thermal decomposition device from the inside, to accelerate the thermal decomposition rate, and to improve the purity of styrene monomer in the monomer oil component, as compared with a thermal decomposition furnace using an external heater in general.
Separation process
In the present invention, the separation step is preferably performed on the slurry component 11 produced in the thermal decomposition treatment step.
That is, it is preferable that the slurry component generated by thermal decomposition is subjected to thermal decomposition treatment by separating a light liquid such as styrene monomer, styrene oligomer, ethylbenzene, and benzene, and a carbide (char), an inorganic substance, and the like from the slurry component by using a separator, and removing a solid component, and the clarified slurry from which the solid component has been removed is subjected to thermal decomposition again by using a thermal decomposition apparatus.
For example, as shown in fig. 2, when polystyrene is thermally decomposed using a thermal decomposition device a, a slurry component 11 generated in the device is treated using a separation device b. The clarified slurry 12 and the solid component (char/inorganic matter) 13 are separated by the separator b, and then the clarified slurry 12 is again fed to the thermal separator a.
Here, the char means a carbonaceous by-product generated by thermal decomposition.
The step of obtaining clarified slurry 12 from the slurry components 11 and introducing the clarified slurry 12 into the thermal separator a may be repeated.
The impurities contained in the waste polystyrene products, which are not required to be regenerated, can be removed by the separation device b. Examples of the inclusions include pigments used for coloring polystyrene products used in waste polystyrene products, molding components used for producing products, and the like. By introducing a separation step of removing these inclusions, it is possible to produce a regenerated styrene monomer having a good hue and quality even when, for example, a colored polystyrene product is to be regenerated. The separation step is effective in the recycling method of the present invention in which not only the non-colored polystyrene product but also the colored polystyrene product is to be recycled.
By adding a separation step, a regenerated styrene monomer of good quality can be efficiently produced. Further, in the thermal decomposition device, the accumulation of the solid component 13 can be suppressed, the number of times of washing in the thermal decomposition furnace can be reduced, and the monomer oil can be continuously produced.
Oil component obtaining process
The thermal decomposition product produced by thermal decomposition of the waste polystyrene is condensed and separated by utilizing the difference in boiling point, and is separated into the monomer oil component 14 and the gas flame component 15. Then, the monomer oil component 14 is supplied to the distillation purification step of the next step.
For example, as shown in fig. 2, steam 10 generated by the thermal decomposition process is supplied to the condenser c.
The condenser c includes a cooling pipe through which cooling water flows, and cools the steam (decomposition gas) discharged from the thermal decomposition device a to condense and separate the high boiling point component. In the condenser c, the monomer oil component 14 as the separated high boiling point component is supplied to the first distillation column d, and the gas flame component 15 as the uncondensed low boiling point component is discharged to the outside of the container of the condenser.
The monomer oil component 14 from which the gas flame component 15 has been removed may be subjected to a further step of supplying the monomer oil component to the thermal decomposition apparatus before the distillation purification step.
For example, a dimer component may be separated from the monomer oil component 14 using a condenser, and the dimer component may be subjected to a thermal decomposition treatment using a thermal decomposition apparatus, and the monomer oil component obtained thereby may be added to the monomer oil component obtained previously and remaining after the dimer component is removed from the monomer oil component 14, and the combined monomer oil component may be supplied to the first distillation column d. This can improve the yield of the regenerated styrene monomer.
In the present invention, the dimer component may contain an oligomer such as a trimer in addition to the dimer.
Distillation refining process
The monomer oil component 14 is distilled and purified by a distillation column, and is separated into styrene monomer and components other than styrene monomer.
For example, as shown in FIG. 2, 2 distillation columns are used. In the first distillation column d, a benzene/toluene/ethylbenzene component 16 is mainly separated from the monomer oil 14, and the remaining components are supplied to the second distillation column e. Next, in the second distillation column e, the dimer component/other (α -methylstyrene, etc.) component 17 is separated, and a styrene monomer (so-called regenerated styrene monomer 2) is obtained.
Here, as described above, the dimer component may contain oligomers such as trimers in addition to dimers.
The regenerated styrene monomer of the present invention thus obtained is a styrene monomer of good quality. Therefore, the regenerated polystyrene produced using the regenerated styrene monomer obtained in the present invention is a good regenerated polystyrene exhibiting the same strength and color as those of polystyrene derived from naphtha.
In the present invention, a step of supplying the dimer component/other (α -methylstyrene, etc.) component 17 separated from the styrene monomer in the second distillation column e to the thermal decomposition apparatus again may be added.
For example, as shown in fig. 2, a dimer component/other (α -methylstyrene, etc.) component 17 is separated from the second distillation column e.
The separated dimer component/other (α -methylstyrene, etc.) component 17 is supplied to the thermal decomposition apparatus a again. In this way, the dimer component/other (α -methylstyrene, etc.) component 17 is subjected to the thermal decomposition treatment again, whereby a regenerated styrene monomer can be additionally obtained. The yield of the regenerated styrene monomer can be further improved by combining the additionally obtained regenerated styrene monomer with the already obtained regenerated styrene monomer 2 shown in FIG. 2.
The production step B of the regenerated styrene monomer for producing the regenerated styrene monomer through the thermal decomposition treatment step, the oil component obtaining step and the distillation purification step is CO 2 The amount of discharge of (2) is suppressed.
Therefore, the method for recycling a polystyrene product of the present invention is considered to be a production method having a high Life Cycle Assessment (LCA) evaluation.
< Properties of regenerated styrene monomer >
The regenerated styrene monomer obtained in the present invention is excellent in quality, but contains a little impurity within a range not adversely affecting practical use.
As impurities, aromatic compounds such as toluene, benzene, cumene, dimer, trimer, ethylbenzene, α -methylstyrene, n-propylbenzene, phenylacetylene, and the like may be contained in a small amount in the regenerated styrene monomer without being completely removed.
As the impurities, inorganic substances such as silicon, copper, iron, titanium, and carbon may be contained.
In addition, as impurities, a small amount of a cyclohexadiene-based compound such as 1, 3-cyclohexadiene, 2-ethyl-1, 3-cyclohexadiene, 2-vinyl-1, 3-cyclohexadiene, 2-methyl-1, 3-cyclohexadiene, 1, 4-cyclohexadiene, 2-ethyl-1, 4-cyclohexadiene, 2-vinyl-1, 4-cyclohexadiene, 2-methyl-1, 4-cyclohexadiene, and the like, and a cyclohexene-based compound such as cyclohexene, cyclohexene hexane, and the like may be contained.
The content of the impurities in the regenerated styrene monomer is usually not more than 10 mass%, may be not more than 5 mass%, may be not more than 3 mass%, and may be not more than 1 mass%, and the lower limit is not particularly limited, and is usually more than 0 mass%. These upper and lower limits may be arbitrarily combined. The content of impurities in the regenerated styrene monomer is usually more than 0 mass% and 10 mass% or less, may be more than 0 mass% and 5 mass% or less, may be more than 0 mass% and 3 mass% or less, and may be more than 0 mass% and 1 mass% or less.
The content of the inorganic component in the regenerated styrene monomer is usually not more than 0.1 mass%, may be not more than 0.01 mass%, and may be not more than 0.001 mass%, and the lower limit is not particularly limited, and is usually more than 0 mass%. These upper and lower limits may be arbitrarily combined. The content of the inorganic component in the regenerated styrene monomer is usually more than 0 mass% and 0.1 mass% or less, may be more than 0 mass% and 0.01 mass% or less, may be more than 0 mass% and 0.001 mass% or less, and may be more than 0 mass% and 1 mass% or less.
< Process C for producing recycled polystyrene >
Polymerizing the obtained regenerated styrene monomer to obtain regenerated polystyrene.
As described above, the obtained recycled polystyrene is a recycled polystyrene having an improved strength as compared with polystyrene produced by recycling of the material.
The obtained regenerated polystyrene is polystyrene in which the hue defect caused by resin scorching is suppressed.
As the polymerization method of styrene monomer, there are solution polymerization, bulk polymerization, suspension polymerization, gas phase polymerization and the like, and any method can be adopted.
The solution polymerization method is, for example, a method of mixing 5 to 20% of a solvent having a boiling point of 130 to 200 ℃ such as ethylbenzene or toluene with a styrene monomer to polymerize the monomer, the bulk polymerization method is, for example, a method of adding a catalyst or the like to a styrene monomer and heating the mixture to polymerize the monomer, and the suspension polymerization method is, for example, a method of dispersing a styrene monomer in the form of particles in a large amount of water using a dispersant and polymerizing the dispersion by using a catalyst such as peroxide.
The form of the regenerated polystyrene obtained by polymerizing the regenerated styrene monomer includes not only a styrene homopolymer (styrene homopolymer) but also a copolymer (copolymer) of a styrene monomer and a monomer other than styrene. Further, a rubber-modified polystyrene obtained by graft polymerization in the presence of butadiene rubber or the like may be included.
The obtained regenerated polystyrene exhibited excellent strength when the strength was evaluated by the following measurement method. When the strength of polystyrene derived from naphtha is assumed to be 100, the strength of polystyrene obtained by material regeneration is about 90. When the strength of the polystyrene derived from naphtha is set to 100, the lower limit of the strength of the regenerated polystyrene of the present invention is usually higher than 90, preferably 95 or higher, more preferably 97 or higher, and still more preferably 99 or higher, and the upper limit is not particularly limited and usually 100 or lower. These upper and lower limits may be arbitrarily combined. When the strength of polystyrene derived from naphtha is set to 100, the strength of regenerated polystyrene may be 100 or more. When the strength of the polystyrene derived from naphtha is set to 100 in the future, the strength of the regenerated polystyrene obtained by the present invention is usually more than 90 and 100 or less, preferably 95 to 100, more preferably 97 to 100, and still more preferably 99 to 100.
[ method for measuring polystyrene Strength ]
The strength of polystyrene can be evaluated by tensile breaking stress according to JIS K7161-1, 2, or by flexural strength according to JIS K7171, for example. In the case of rubber-modified polystyrene, the impact strength of the beam can be evaluated in accordance with JIS K7111-1.
The obtained regenerated polystyrene exhibits a good hue in which yellowness is suppressed when the hue is evaluated by the following measurement method. Specifically, the hue is evaluated by the yellowness (YI value) or the like. The larger the YI value is, the stronger the yellow color is, and the larger the negative value is, the stronger the blue color is. The YI value of the recycled polystyrene obtained in the present invention is lower than that of polystyrene obtained by recycling the material, and the difference between the YI values is usually 0.1 or more, preferably 0.3 or more, more preferably 0.5 or more, and further preferably 1.0 or more. There is no particular upper limit for the difference in YI values.
[ method for measuring hue of polystyrene ]
The hue of polystyrene can be measured, for example, according to JIS K7373.
< Process D > for producing polystyrene product
A regenerated polystyrene product is obtained from the regenerated polystyrene.
As described above, the obtained recycled polystyrene product is a good recycled polystyrene product exhibiting the same strength and hue as those of polystyrene derived from naphtha.
The form of the polystyrene product is not particularly limited as long as it is a recycled polystyrene, and can be appropriately selected according to the purpose.
For example, by preparing a composition containing, as necessary, other components such as a colorant, water, and an organic solvent in addition to polystyrene, it is possible to produce polystyrene products used as, for example, a coating agent, ink, and adhesive.
Alternatively, a polystyrene product such as a stretched sheet or a foamed sheet can be produced by molding a composition containing recycled polystyrene into a sheet. Further, by molding the polystyrene sheet, a polystyrene product such as a food packaging container (for example, a food tray) can also be produced.
Further, by injection molding or injection blow molding the composition containing recycled polystyrene, it is possible to produce polystyrene products for food containers such as cups and bottles.
In addition, in general, when used for a food packaging container, recycled plastic is limited in use because the plastic may not be in direct contact with food, for example, because the transfer of the contents may occur. However, the recycled plastic obtained by the present invention is obtained by decomposing a waste polymer plastic into monomers, purifying, and polymerizing, and therefore, can be directly contacted with food, and is not limited in its application.
In the above embodiment, the case where a homopolymer is used as the waste polystyrene is described, but the present invention is not limited to the homopolymer, and is also applicable to a copolymer, that is, a waste styrene copolymer. Examples of such waste styrene copolymers include waste rubber-modified polystyrene (waste HIPS), waste styrene-acrylic acid copolymers (waste AS resin), and waste styrene-butadiene-acrylic acid copolymers (waste ABS resin). In the present invention, the waste polystyrene may contain these copolymers.
Examples
The present invention will be described in further detail with reference to the following examples, but the scope of the present invention is not limited to these examples.
(example 1)
The used polystyrene product is recovered, then pulverized and granulated. The granulated material 1t of waste polystyrene was put into a thermal decomposition apparatus using a microwave.
The reaction temperature in the thermal decomposition apparatus was set to 350 ℃, and 2 mass% of silicon carbide was used as a catalyst for waste polystyrene, and thermal decomposition treatment was performed under steam purge.
As a result, 600kg of a crude regenerated styrene monomer was obtained (yield 60%). The purity of the purified regenerated styrene monomer a is close to 95%.
(example 2)
A crude regenerated styrene monomer was obtained in the same manner as in example 1, except that in example 1, a step of supplying the monomer oil component from which the gas flame component was removed to the thermal decomposition apparatus again before supplying the monomer oil component to the distillation purification step was added.
As a result, 840kg of a crude regenerated styrene monomer was obtained (yield 84%). The purity of the refined regenerated styrene monomer b is higher than 99.8 percent.
(example 3)
A regenerated styrene monomer c was obtained in the same manner as in example 1, except that a step of supplying the dimer component/other (α -methylstyrene, etc.) component separated from the crude regenerated styrene monomer in the second distillation column to the thermal decomposition apparatus again was added to example 1.
As a result, 240kg of crude regenerated styrene monomer was obtained from the dimer component/other (e.g.,. Alpha. -methylstyrene) component separated in example 1. When the crude styrene monomer was combined with the regenerated styrene monomer a obtained in example 1, a total of 840kg of the crude regenerated styrene monomer was obtained from example 1 and example 3 (yield: 84%). The purity of the purified regenerated styrene monomer c is close to 95%.
(example 4)
Using the regenerated styrene monomers a to c obtained in examples 1 to 3, respectively, a mixed solution of 95 parts of styrene and 5 parts of toluene was prepared, and 400ppm of t-butyl peroxybenzoate was added to styrene as an organic peroxide, and the mixture was supplied to a tubular reactor connected at 120 to 160 ℃ to carry out continuous bulk polymerization. The mixed solution obtained by polymerization was heated to 220 ℃ by a heat exchanger, volatile components were removed under a reduced pressure of 50mmHg, and then pelletized to obtain regenerated polystyrenes A to C.
The strength and hue of each of the obtained recycled polystyrenes a to C were evaluated by the methods described below.
Comparative example 1
100 parts by mass of a used styrene resin composition was melt-kneaded at a cylinder temperature of 220 ℃ using a twin-screw kneading extruder, and the strands were cooled with water and pelletized to obtain polystyrene D.
The polystyrene D obtained by material regeneration was evaluated for strength and hue by the methods described below.
As a result of the comparison, it was confirmed that the recycled polystyrenes a to C exhibited more excellent strength and hue than the polystyrene D obtained by recycling the material. The measured value of the strength of the polystyrene D obtained by recycling the material was 45MPa, while the measured values of the strengths of the recycled polystyrenes A to C all showed 50MPa. The YI value of polystyrene D obtained by material regeneration was 1.0, and the regenerated polystyrenes A to C showed 0.4.
[ method for measuring polystyrene Strength ]
Using the obtained pellets, a dumbbell-shaped molded article for evaluation was produced by an injection molding machine (molding temperature: 220 ℃). Tensile test was carried out using the dumbbell-shaped molded article to measure the tensile breaking stress.
[ method for measuring the color of polystyrene ]
Using the obtained pellets, a plate-like molded article for evaluation was produced by an injection molding machine (molding temperature 220 ℃). The YI value was measured by a transmission measurement method using the plate-shaped molded article.
Therefore, the following steps are carried out: when the regenerated styrene monomer is produced from waste polystyrene by the regeneration method of the present invention, the regenerated styrene monomer can be produced in high yield and high purity.
Therefore, the following steps are carried out: according to the regeneration method of the present invention, high-quality styrene monomer can be produced from waste polystyrene, and regenerated polystyrene obtained by polymerizing the regenerated styrene monomer is excellent in strength and hue.
The present invention makes it possible to establish a 100% recycle polystyrene regeneration system that can be expected to regenerate 100% of styrene from waste polystyrene products.
Description of the symbols
1 waste polystyrene product
2 regeneration of styrene monomer
3 recycled polystyrene
4 polystyrene product
10. Steam generating device
11. Slurry
12. Clarifying slurry
13 solid component (char/inorganic substance)
14. Monomer oil
15. Gas flame
16 benzene/toluene/ethylbenzene
17 dimer/other (alpha-methylstyrene)
A recovery Process
Method for producing regenerated styrene monomer
Method for producing C recycled polystyrene
Method for producing D polystyrene product
a thermal decomposition apparatus
b separating device
c condenser
d first distillation column
e a second distillation column.
Claims (8)
1. A method for recycling waste polystyrene products, comprising the step of obtaining a recycled styrene monomer from waste polystyrene by subjecting the waste polystyrene products to a thermal decomposition treatment.
2. The recycling method of waste polystyrene articles of claim 1, wherein said waste polystyrene articles comprise non-colored polystyrene articles and colored polystyrene articles.
3. The method for recycling waste polystyrene products as claimed in claim 1 or 2, wherein said waste polystyrene products are pulverized to obtain pulverized waste polystyrene products, and said pulverized waste polystyrene products are subjected to a thermal decomposition treatment.
4. The method for recycling waste polystyrene products as claimed in any one of claims 1 to 3, wherein said step of obtaining recycled styrene monomer comprises:
a step of thermally decomposing the waste polystyrene product by using a thermal decomposition device;
supplying the steam generated by the thermal decomposition to a condenser, thereby removing a gas flame component from a thermal decomposition product in which an oil component containing a regenerated styrene monomer and the gas flame component are mixed, to obtain an oil component containing a regenerated styrene monomer; and
and a step of performing distillation purification on the oil component containing the regenerated styrene monomer by using a distillation column to improve the purity of the regenerated styrene monomer.
5. The recycling method of waste polystyrene articles as claimed in claim 4, further comprising:
removing a solid component from a slurry component generated by the thermal decomposition by using a separator; and
and a step of thermally decomposing the clarified slurry from which the solid component has been removed by using the thermal decomposition device.
6. The method for recycling waste polystyrene products as claimed in claim 4 or 5, wherein said thermal decomposition device is a thermal decomposition device using microwaves.
7. The method for recycling a waste polystyrene product as claimed in any one of claims 1 to 6, wherein said recycled styrene monomer contains at least 1 selected from the group consisting of inorganic substances, aromatic compounds, cyclohexadiene-based compounds and cyclohexene-based compounds in addition to styrene monomer.
8. A method for recycling a waste polystyrene product, comprising:
a step of recovering waste polystyrene products;
a step of subjecting the recovered waste polystyrene product to thermal decomposition treatment to obtain a regenerated styrene monomer from the waste polystyrene;
polymerizing the regenerated styrene monomer to obtain regenerated polystyrene; and
and a step of obtaining a regenerated polystyrene product made of the regenerated polystyrene.
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| JP2020086056 | 2020-05-15 | ||
| JP2020-086056 | 2020-05-15 | ||
| PCT/JP2021/018165 WO2021230312A1 (en) | 2020-05-15 | 2021-05-13 | Method for recycling waste polystyrene products |
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| JP (1) | JP7318810B2 (en) |
| KR (1) | KR20230013238A (en) |
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| WO2023209180A1 (en) | 2022-04-29 | 2023-11-02 | Repsol, S.A. | Method for styrene monomer production |
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| JPS51130405A (en) * | 1975-05-08 | 1976-11-12 | Mitsubishi Heavy Ind Ltd | Method for separating residues in pyroly tic oil recovery process |
| JP3709014B2 (en) * | 1996-06-05 | 2005-10-19 | 三菱レイヨン株式会社 | Method for recovering monomer from waste acrylic resin |
| JP2003335710A (en) * | 2002-05-21 | 2003-11-28 | Toshiba Plant Kensetsu Co Ltd | Method for recovering styrene monomer |
| JP2004002519A (en) * | 2002-05-31 | 2004-01-08 | Toshiba Plant Kensetsu Co Ltd | Method for producing polystyrene |
| JP4139897B2 (en) * | 2004-02-04 | 2008-08-27 | 独立行政法人産業技術総合研究所 | Method and apparatus for thermal decomposition of plastic |
| JP2008156457A (en) * | 2006-12-22 | 2008-07-10 | T Rad Co Ltd | Thermal decomposition method for polystyrene |
| JP2010195895A (en) * | 2009-02-24 | 2010-09-09 | National Institute Of Advanced Industrial Science & Technology | Method and apparatus for manufacturing degraded product of plastic |
| JP5772503B2 (en) * | 2011-10-26 | 2015-09-02 | 富士通株式会社 | Oil making apparatus and oil making method |
| JP7085923B2 (en) | 2018-07-05 | 2022-06-17 | 三菱電機株式会社 | Recycled styrene resin composition |
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| JPWO2021230312A1 (en) | 2021-11-18 |
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