Resin material and method for producing resin material

Abstract

To provide a resin material obtained by reusing an electric wire waste material, and to provide a method for producing the resin material.SOLUTION: The plastic material (PVC2 CNT) is PVC2 CNT obtained by reusing a wire waste material 1, and includes polyvinylchloride (CNT2) which is a base material 11 recovered from the wire waste material 1, and carbon nanotubes (CNT) unevenly dispersed and mixed in the CNT2. The method for producing the resin material includes a step of recovering the base material 11 from the electric wire waste material 1, a step of producing the mixture 5 of the base material 11 and the carbon nanotube, and a step of heat-treating the mixture 5 to produce the resin material.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a resin material made from recycled electric wire waste and a method for manufacturing the resin material. [Background technology]

[0002] Conventionally, technologies for reusing waste electric wires for various purposes have been developed. For example, Patent Documents 1 and 2 introduce technologies for recovering polyvinyl chloride resins and polyethylene resins from waste electric wires and reusing them as insulators for electric wires, etc. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-2850 [Patent Document 2] Japanese Patent Application Laid-Open No. 2001-98124 Summary of the Invention [Problem to be solved by the invention]

[0004] A resin material made from recycled electric wire waste and a method for manufacturing the resin material are provided. [Means for solving the problem]

[0005] In order to solve the above problems, the resin material disclosed herein is a resin material made from recycled waste electric wire, and is characterized by comprising polyvinyl chloride recovered from the waste electric wire and carbon nanotubes unevenly dispersed and mixed into the polyvinyl chloride. [Brief explanation of the drawings]

[0006] [Figure 1] 1 is a schematic diagram illustrating a method for producing PVC2-CNT according to the present disclosure. FIG. [Figure 2] 1 is a graph showing the analysis results of (a) PVC1 and (b) PVC2 by TDNMR. [Figure 3] 1A is a graph showing the heating temperature dependence of the fluidity of PVC, and FIG. 1B is a graph showing the fluidity of PVC-CVT at 190°C. [Figure 4] 1 is a graph showing the CNT concentration dependence of resistivity of PVC-CNT. [Figure 5] 1 is a graph showing the CNT concentration dependency of the electromagnetic wave shielding properties of PVC-CNT. DETAILED DESCRIPTION OF THE INVENTION

[0007] Hereinafter, an embodiment in which the present disclosure is embodied in a resin material using waste electric wires will be described with reference to the drawings.

[0008] In this specification and drawings, polyvinyl chloride will be referred to as PVC, carbon nanotubes as CNT, and resin materials as PVC-CNT. In particular, new polyvinyl chloride will be referred to as PVC1, polyvinyl chloride recovered from waste electric wire 51 as PVC2, a resin material using PVC1 as PVC1-CNT, and a resin material using PVC2 as PVC2-CNT. When simply referring to PVC, it should be understood as PVC1 or PVC2, and when simply referring to PVC-CNT, it should be understood as PVC1-CNT or PVC2-CNT.

[0009] The resin material of the present disclosure is PVC2-CNT, which comprises PVC2, a base material recovered from waste electric wire, and CNTs dispersed unevenly in the PVC2. PVC2-CNT has electrical conductivity and electromagnetic wave shielding properties.

[0010] The method for producing PVC2-CNT will be explained with reference to FIG.

[0011] PVC2-CNT comprises a substrate 11 (PVC2) recovered from waste electric wire 51 and CNTs unevenly dispersed and mixed in the PVC2. The CNTs may be, for example, single-walled CNTs. In PVC2-CNT, the mass ratio of CNTs to PVC2 (CNT / PVC2) is preferably 1.0 to 2.5%.

[0012] (1) Substrate recovery process The waste electric wire 51 is composed of copper wire 12 and a substrate 11 (PVC2) covering the copper wire 12. As shown in FIG. 1(a), the waste electric wire 51 is immersed in an organic solvent 2 such as tetrahydrofuran (THF) to completely dissolve only the PVC2, thereby obtaining a solution 3 of PVC2 as shown in FIG. 1(b). The concentration of PVC2 in the solution 3 is preferably about 12 mass percent (wt%). The copper wire 12 that has settled in the solution 3 is removed.

[0013] Table 1 shows the results of a test comparing the time it takes for PVC2 to completely dissolve when 2 cm of discarded electric wire is immersed in 10 ml of THF and the temperature and stirring speed conditions are changed to dissolve the PVC2.

[0014] [Table 1]

[0015] As shown in Table 1, when waste electric wires were immersed in THF at 30°C, the time required for complete dissolution was 90 minutes. When the temperature of THF was increased to 60°C, the time required for complete dissolution was 40 minutes, a 55% reduction compared to when THF at 30°C was used. From the above, it can be seen that the time required for complete dissolution is shortened by increasing the temperature of THF.

[0016] When THF was not stirred, i.e., when the stirring speed was 0 rpm, the time for complete dissolution was 90 minutes. When the stirring speed was 300 rpm, the time for complete dissolution was 35 minutes, a 60% reduction compared to when the stirring speed was 0 rpm. From the above, it can be seen that the time for complete dissolution is shortened by increasing the stirring speed of THF.

[0017] (2) Mixture generation process 1(c), CNTs are added to a solution 3 of PVC 2, and the solution 3 and CNTs are stirred and homogenized in a sealed container at a temperature of 20°C to 30°C for about 48 hours to produce a mixed solution 4. The concentration of CNTs in the mixed solution 4 is preferably about 0.3 to 4 wt%.

[0018] As shown in FIG. 1(d), in an open container, the organic solvent 2 contained in the mixture 4 is dried and removed in an environment of 25° C. or higher and 35° C. or lower for about 4 hours to produce a mixture 5.

[0019] (3) PVC2-CNT production process As shown in FIG. 1(e), the mixture 5 is heat-treated at a temperature of 50° C. or higher and 90° C. or lower to produce PVC2-CNT as shown in FIG. 1(f).

[0020] Regarding the PVC2-CNT configured as described above, the test results regarding PVC1 and PVC2, and PVC1-CNT and PVC2-CNT will be described according to FIGS. 2 to 5.

[0021] <Analysis by TDNMR (Time-Domain Nuclear Magnetic Resonance) method> As shown in FIG. 2(a), PVC1 has two peaks in the region of relaxation time of 0.01 to 1 second. On the other hand, as shown in FIG. 2(b), PVC2 has one peak in the region of relaxation time of 0.01 to 1 second.

[0022] In the analysis by the TDNMR method, the length of the relaxation time is proportional to the hardness of the components of PVC. In other words, the region with a short relaxation time is derived from the crystalline phase, and the region with a long relaxation time is derived from the amorphous phase.

[0023] In the region of relaxation time of 0.01 to 1 second, since the number of peaks of PVC2 is smaller than that of PVC1, it can be seen that the phase corresponding to the hardness in the region of relaxation time of 0.01 to 1 second has disappeared in the process of the electric wire becoming the electric wire waste 51. Also, from such behavior (the difference in the number of peaks), it becomes possible to distinguish between a new electric wire and the electric wire waste 51.

[0024] <Temperature dependence of fluidity> Figure 3(a) is a graph showing the heating temperature dependence of PVC fluidity. In this test, the MFR (Melt Flow Rate), an index of ease of molding, is measured. The MFR is measured by heating PVC to 170-190°C and pressurizing it at a constant pressure of 1.8 MPa over an area of ​​1.5 cm. 2 This is the weight of PVC extruded through the holes in the tube every 10 minutes.

[0025] As shown in Figure 3(a), the MFR of both PVC1 and PVC2 increases as the temperature increases. Around 170°C, there is no difference in the MFR of PVC1 and PVC2. However, around 180 to 190°C, the MFR of PVC2 is about twice that of PVC1. In other words, around 180 to 190°C, PVC2 is more suitable for injection molding than PVC1.

[0026] <Fluidity at 190℃> Figure 3(b) is a graph showing the fluidity of PVC-CNT at 190°C. In this test, the above-mentioned MFR is measured for PVC-CNT heated to 190°C. The CNT concentration is 1.5 wt%.

[0027] As shown in Figure 3(b), the MFR of PVC2-CNT is significantly higher than that of PVC1-CNT. In other words, PVC2-CNT is far more suitable for injection molding than PVC1-CNT at temperatures around 190 °C.

[0028] <CNT concentration dependence of resistivity> Figure 4 is a graph showing the CNT concentration dependence of resistivity for PVC-CNT. In this test, PVC-CNT with a CNT concentration of 1 to 5 wt% was formed into a sheet, the sheet resistance was measured using the four-point probe method, and the sheet thickness was measured using a scanning electron microscope. Based on the sheet resistance and sheet thickness, the resistivity was calculated using the formula: resistivity (Ω·cm) = sheet resistance (Ω / sq) × thickness (cm).

[0029] As shown in Fig. 4, overall, as the concentration of CNT increases, the resistivity of PVC1-CNT and PVC2-CNT decreases. When the concentration of CNT is 1 wt% or more, the resistivity of PVC1-CNT and PVC2-CNT becomes almost the same value. When the concentration of CNT is 2 wt% or more, the resistivity of PVC2-CNT is lower than that of PVC1-CNT. Generally, since the electromagnetic shielding effect tends to increase as the resistivity decreases, it can be said that the concentration of CNT in PVC2-CNT is preferably 1 wt% or more, and more preferably 2 wt% or more rather than 1 wt% or more.

[0030] <Concentration Dependence of CNT on Electromagnetic Shielding Characteristics> Fig. 5 is a graph showing the concentration dependence of the electromagnetic shielding characteristics of PVC-CNT. In this test, for PVC-CNT with a CNT concentration of 1 to 5 mass percent (wt%), electromagnetic waves in the frequency bands of (a) 3.95 to 5.85 GHz, (b) 5.85 to 8.2 GHz, and (c) 26.5 to 40 GHz are used for analysis by the waveguide method.

[0031] Overall, as the concentration of CNT increases, the electromagnetic shielding effect of PVC1-CNT and PVC2-CNT increases. Also, regardless of the concentration of CNT, the electromagnetic shielding characteristics of PVC1-CNT and PVC2-CNT are almost equivalent. Here, from the perspective of improving the electromagnetic shielding characteristics of PVC2-CNT, it can be said that the concentration of CNT is preferably 1 wt% or more, and more preferably 2 wt% or more rather than 1 wt% or more.

[0032] Therefore, according to this embodiment, the waste electric wire 1 can be reused to produce PVC2-CNT. Also, PVC2-CNT has the merit that it is easier to injection mold than PVC1-CNT while maintaining an electromagnetic shielding effect equivalent to that of PVC1-CNT.

[0033] <Dependence of Solvent Type on Solubility of PVC2> The solubility of PVC2 was confirmed in several types of organic solvent 2. The organic solvents used were THF, cyclohexane, cyclohexanone, and 1,4-dioxane. In the experiment, PVC2 (1 g) was added to organic solvent 2 (10 mL) at 30°C and stirred at 300 rpm, and the amount of PVC2 remaining after 24 hours was confirmed.

[0034] [Table 2]

[0035] As shown in Table 2, it was found that the solubility of PVC2 depends on the type of organic solvent 2. THF showed the highest solubility, followed by cyclohexanone. 1,4-dioxane showed lower solubility, with much of the PVC2 remaining undissolved at the bottom of the container. Cyclohexane showed the lowest solubility, with almost no PVC2 dissolving.

[0036] <Dependence of resistivity and electromagnetic wave shielding properties on solvent type> Regarding the production of PVC2-CNT, we confirmed the effect of the solvent type on resistivity and electromagnetic wave shielding properties. For organic solvent 2, THF and cyclohexanone, which showed high solubility in the above "Solvent type dependence of PVC2 solubility," were used. In the experiment, the concentration of CNT in mixed liquid 4 was set to 2 wt%, and steps "(1) Substrate recovery process" to "(3) PVC2-CNT production process" were carried out.

[0037] [Table 3]

[0038] As shown in Table 3, the resistivity was lower when THF was used than when cyclohexanone was used, while the electromagnetic wave shielding properties were better when cyclohexanone was used than when THF was used.

[0039] Therefore, it is also preferable to use cyclohexanone as the organic solvent 2 in addition to THF.

[0040] The present disclosure is not limited to the above-described embodiment, and the shape and configuration of each part may be appropriately changed without departing from the spirit of the present disclosure. For example, in the process of recovering PVC2 from waste electric wire 51, PVC2 may be manually removed from copper wire 12. [Explanation of symbols]

[0041] 1. Electrical wire scrap 2. Organic solvents 3 solution 4 Mixed liquid 5 mixture 11 Base material 12 copper wire

Claims

1. A resin material made by recycling waste electric wires, A resin material comprising a base material recovered from the waste electric wires and carbon nanotubes unevenly dispersed and mixed in the base material.

2. The resin material according to claim 1 , wherein the resin material is electrically conductive.

3. The resin material according to claim 1 , wherein the resin material has an electromagnetic wave shielding property.

4. The resin material according to claim 1 , wherein the base material is polyvinyl chloride.

5. 2. The resin material according to claim 1, wherein the number of peaks in the relaxation time region of 0.01 to 1 second by TDNMR method of the base material is smaller than the number of peaks in new polyvinyl chloride.

6. 2. The resin material according to claim 1, wherein a mass ratio of the carbon nanotubes to the base material is 1 to 2.5%.

7. A method for producing the resin material according to claim 1, comprising: recovering the base material from the waste electric wire; forming a mixture of the substrate and the carbon nanotubes; and heat-treating the mixture to produce a resin material. The step of recovering the substrate comprises: The method includes a step of immersing the waste electric wire in an organic solvent to obtain a solution of the base material, The step of forming the mixture comprises: mixing the solution with carbon nanotubes to form a mixed solution; and removing the organic solvent contained in the mixture by drying.

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