Resin regeneration method and resin regeneration apparatus

Abstract

To provide a resin regeneration method and a resin regeneration apparatus which can improve monomer recovery efficiency.SOLUTION: A resin regeneration apparatus 10 includes: a reaction container 11 for storing a composition containing a filler capable of absorbing a resin and microwaves; a magnetic field heating part 12 for irradiating the composition stored in the reaction container 11 with microwaves, and thermally decomposing the resin by magnetic field heating; a decomposition gas recovery part 13 for recovering a decomposition gas generated by thermally decomposing the resin; and an inert gas supply part 14 for supplying an inert gas to the reaction container 11.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a resin recycling method and a resin recycling device. [Background technology]

[0002] In recent years, efforts have been made to significantly reduce waste generation through waste prevention, reduction, recycling and reuse. To achieve this, research and development is being carried out into methods for recycling resins.

[0003] Patent Document 1 describes a method for recycling plastic materials. In this method, the plastic material is first comminuted to form plastic granules having a desired particle size, and then the plastic granules are provided with a susceptor agent and a binder that impart specific dielectric properties to the plastic granules. The plastic granules provided with the susceptor agent and binder are then treated with microwave energy, and a solid product is then formed from the treated plastic granules. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Special Publication No. 2007-537894 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the method described in Patent Document 1, the plastic material is recycled without being thermally decomposed, and therefore the efficiency of monomer recovery cannot be improved.

[0006] An object of the present invention is to provide a resin regeneration method and a resin regeneration device that can improve the efficiency of monomer recovery. [Means for solving the problem]

[0007] (1) A method for regenerating resin, comprising: a step of irradiating a composition containing a resin and a filler capable of absorbing microwaves with the microwaves in an inert gas atmosphere to thermally decompose the resin by magnetic field heating; and a step of recovering decomposition gas generated by the thermal decomposition of the resin.

[0008] (2) The method for regenerating resin according to (1), wherein the filler contains carbon, β-silicon carbide, or Mn-Zn-based soft ferrite.

[0009] (3) The method for regenerating resin according to (2), wherein the filler is carbon fiber.

[0010] (4) A method for regenerating resin according to any one of (1) to (3), wherein the resin is polypropylene.

[0011] (5) A method for regenerating resin according to any one of (1) to (4), wherein the mass ratio of the filler to the resin is 1.5 or more.

[0012] (6) A resin regeneration device comprising: a reaction vessel for containing a composition including a resin and a filler capable of absorbing microwaves; a magnetic field heating unit for irradiating the composition contained in the reaction vessel with the microwaves to thermally decompose the resin by magnetic field heating; a decomposition gas recovery unit for recovering decomposition gas generated by the thermal decomposition of the resin; and an inert gas supply unit for supplying an inert gas to the reaction vessel.

[0013] (7) The resin regeneration apparatus described in (6), wherein the magnetic field heating unit includes a microwave cavity resonator that accommodates the reaction vessel, and a frequency control unit that controls the frequency of the microwaves so that the strength of the magnetic field at the center of the microwave cavity resonator is maximized. Effect of the Invention

[0014] According to the present invention, it is possible to provide a resin regeneration method and a resin regeneration device capable of improving the efficiency of monomer recovery. [Brief description of the drawings]

[0015] [Figure 1] FIG. 1 is a schematic diagram showing a resin recycling device according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0017] FIG. 1 shows a resin recycling device according to one embodiment of the present invention.

[0018] The resin regeneration device 10 includes a tubular reaction vessel 11 in which a composition C containing a resin and a filler capable of absorbing microwaves is accommodated, a magnetic field heating section 12 that irradiates the composition accommodated in the reaction vessel 11 with microwaves to thermally decompose the resin by magnetic field heating, a decomposition gas recovery section 13 that recovers decomposition gas generated by thermal decomposition of the resin, and an inert gas supply section 14 that supplies an inert gas to the reaction vessel 11. Here, the reaction vessel 11 and the decomposition gas recovery section 13 are connected via a pipe 15. In addition, a member (such as glass wool) that allows the decomposition gas and the inert gas to pass but does not allow the composition to pass is arranged at the end of the reaction vessel 11 on the side of the pipe 15.

[0019] In the resin recycling device 10, the filler absorbs the microwaves irradiated to the composition and generates heat, causing the resin to pyrolyze and generate decomposition gas containing monomers. At this time, many hot spots are generated by magnetic field heating, making it easier for the resin to pyrolyze and improving the efficiency of monomer recovery.

[0020] On the other hand, when the composition contained in the reaction vessel 11 is irradiated with microwaves and the resin is thermally decomposed by electric field heating, the number of hot spots decreases, making it difficult for the resin to be thermally decomposed and reducing the monomer recovery efficiency.

[0021] The resin is not particularly limited as long as it is a resin that undergoes thermal decomposition to generate decomposition gas containing a monomer, but examples thereof include polyolefins (such as polypropylene), polyesters (such as polyethylene terephthalate), and polyamides (such as nylon).

[0022] The material constituting the filler is not particularly limited as long as it can absorb microwaves, and examples thereof include carbon, silicon carbide (α silicon carbide, β silicon carbide, etc.), ferrite (Mn-Zn-based soft ferrite, etc.), and barium titanate. Among these, carbon, β silicon carbide, and Mn-Zn-based soft ferrite are preferred in terms of monomer recovery efficiency. Examples of the filler made of carbon include carbon fiber (PAN-based carbon fiber, pitch-based carbon fiber, etc.) and carbon nanotube, with carbon fiber being preferred.

[0023] The average fiber length of the carbon fibers is preferably 100 μm or less, more preferably 50 μm or less. When the average fiber length of the carbon fibers is 100 μm or less, the monomer recovery efficiency is improved. The average fiber length of the carbon fibers is, for example, 5 μm or more.

[0024] The mass ratio of the filler to the resin is preferably 1.5 or more, more preferably 3 or more. When the mass ratio of the filler to the resin is 1.5 or more, the recovery efficiency of the monomer is improved. The mass ratio of the filler to the resin is, for example, 10 or less.

[0025] The material constituting the reaction vessel 11 is not particularly limited as long as it is capable of transmitting microwaves, and examples thereof include quartz.

[0026] The magnetic field heating unit 12 is not particularly limited as long as it is capable of thermally decomposing the resin by magnetic field heating by irradiating microwaves to the composition contained in the reaction vessel 11. Here, the magnetic field heating unit 12 includes a microwave cavity resonator that contains the reaction vessel 11, and a frequency control unit that controls the microwave frequency so that the strength of the magnetic field at the center of the microwave cavity resonator becomes maximum.

[0027] An example of a commercially available product of the magnetic field heating unit 12 is the microwave reaction device MR-2G-100 (manufactured by Ryowa Electronics Co., Ltd.). The microwave reaction device MR-2G-100 includes a cylindrical microwave cavity resonator in which a standing wave of TM010 mode is formed, and a frequency control unit that controls the microwave frequency so that the strength of the magnetic field at the central axis of the microwave cavity resonator becomes maximum.

[0028] The decomposition gas recovery section 13 is not particularly limited as long as it is capable of recovering the decomposition gas.

[0029] The inert gas supply unit 14 is not particularly limited as long as it can supply an inert gas to the reaction vessel 11, and may be, for example, a cylinder filled with an inert gas. An example of the inert gas is nitrogen gas.

[0030] The resin regeneration method according to one embodiment of the present invention includes a step of irradiating a composition containing a resin and a filler capable of absorbing microwaves with microwaves in an inert gas atmosphere to thermally decompose the resin by magnetic field heating, and a step of recovering the decomposition gas generated by the thermal decomposition of the resin. The resin regeneration method according to one embodiment of the present invention can be carried out, for example, by using a resin regeneration device 10.

[0031] Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and the above embodiment may be modified as appropriate within the scope of the spirit of the present invention. EXAMPLES

[0032] Examples of the present invention will be described below, but the present invention is not limited to these examples.

[0033] [Example 1] 0.01g of polypropylene pellets and 0.19g of PAN-based carbon fiber CFMP-30X (manufactured by Nippon Polymer Industries Co., Ltd.) with an average fiber length of 40 μm were mixed to obtain a sample for recycling. Next, a resin recycling device (see FIG. 1) was used to place the sample for recycling in a reaction vessel and recover propylene gas. At this time, a microwave reaction device MR-2G-100 (manufactured by Ryowa Electronics Co., Ltd.) was used as the magnetic field heating section, the microwave frequency was set to 2.45 GHz, and the microwave output was set to 70 W. An attached reaction tube made of quartz glass was used as the reaction vessel. A nitrogen cylinder was used as the inert gas supply section to supply nitrogen gas to the reaction vessel at 0.5 L / min. A gas bag was used as the decomposition gas recovery section, and the decomposition gas was recovered together with the nitrogen gas supplied from the nitrogen cylinder. The recovered cracked gas was analyzed using an Agilent 6890N gas chromatograph and a PoraBOND Q column (both manufactured by Agilent Technologies), and the monomer recovery efficiency (the ratio of the recovered amount of propylene gas to the total amount of nitrogen gas and cracked gas) was found to be 680 μL / L.

[0034] [Example 2] The decomposition gas was recovered in the same manner as in Example 1, except that PAN-based carbon fiber CFMP-150X (manufactured by Nippon Polymer Industry Co., Ltd.) having an average fiber length of 100 μm was used instead of PAN-based carbon fiber CFMP-30X (manufactured by Nippon Polymer Industry Co., Ltd.) having an average fiber length of 40 μm. The monomer recovery efficiency was 6.9 μL / L.

[0035] [Example 3] The decomposition gas was recovered in the same manner as in Example 1, except that carbon nanotubes TC-2000 (manufactured by Toda Kogyo Co., Ltd.) with an average tube diameter of 16 nm and a length of 1 to 5 μm were used instead of carbon fibers, and the monomer recovery efficiency was 380 μL / L.

[0036] [Example 4] The decomposition gas was recovered in the same manner as in Example 1, except that Mn-Zn-based soft ferrite BSF-547 (manufactured by Toda Kogyo Co., Ltd.) having an average particle size of 3.20 μm was used instead of carbon fiber, and the monomer recovery efficiency was 580 μL / L.

[0037] [Example 5] The decomposition gas was recovered in the same manner as in Example 1, except that α-silicon carbide (α-SiC) 2500N (manufactured by Superior Graphite) having an average particle size of 0.5 μm was used instead of the carbon fiber, and the monomer recovery efficiency was 80 μL / L.

[0038] [Example 6] The decomposition gas was recovered in the same manner as in Example 1, except that β-silicon carbide (β-SiC) 220 (manufactured by Superior Graphite) having an average particle size of 300 μm was used instead of the carbon fiber, and the monomer recovery efficiency was 760 μL / L. [Explanation of symbols]

[0039] 10 Resin regeneration equipment 11 Reaction vessel 12 Magnetic field heating section 13. Cracked gas recovery section 14 Inert gas supply section 15 Piping C composition

Claims

1. a step of irradiating a composition containing a resin and a filler capable of absorbing microwaves with the microwaves in an inert gas atmosphere to thermally decompose the resin by magnetic field heating; and recovering a decomposition gas generated by thermal decomposition of the resin.

2. The resin regenerating method according to claim 1, wherein the filler contains carbon, β-silicon carbide, or Mn-Zn-based soft ferrite.

3. The resin regenerating method according to claim 2 , wherein the filler is carbon fiber.

4. The resin regeneration method according to claim 1 or 2, wherein the resin is polypropylene.

5. The resin regenerating method according to claim 1 or 2, wherein a mass ratio of the filler to the resin is 1.5 or more.

6. A reaction vessel containing a composition including a resin and a filler capable of absorbing microwaves; a magnetic field heating unit that irradiates the composition contained in the reaction vessel with the microwaves to thermally decompose the resin by magnetic field heating; a decomposition gas recovery section that recovers a decomposition gas generated by thermal decomposition of the resin; An inert gas supply unit that supplies an inert gas to the reaction vessel.

7. The magnetic field heating unit includes a microwave cavity resonator that accommodates the reaction vessel, and a frequency control unit that controls the frequency of the microwaves so that the strength of the magnetic field at the center of the microwave cavity resonator is maximized. The resin regeneration apparatus according to claim 6.

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