Method for producing resin composition

Abstract

In this method for producing a resin composition, a polyvinyl chloride resin composition is produced by removing lead from a resin molded article containing polyvinyl chloride as a main component and containing a lead-based stabilizer. This method for producing a resin composition comprises: a pulverizing step for pulverizing a resin molded article to form a pulverized material; a dissolution step in which the pulverized material is immersed in an acidic or alkaline liquid and the lead contained in the lead-based stabilizer is dissolved from the pulverized material into the liquid; and a separation step for separating the pulverized material from the liquid in which the lead is dissolved. The purpose of the present invention is to efficiently produce a polyvinyl chloride resin composition by removing lead from a resin molded article containing polyvinyl chloride as a main component and containing a lead-based stabilizer and recycling the resin molded article.

Description

Technical Field

[0001] The present invention relates to a method for producing a resin composition, which is used for producing a polyvinyl chloride resin composition from a polyvinyl chloride resin molded product containing a lead stabilizer. Background Art

[0002] Resin molded products such as resin profiles with polyvinyl chloride as the main component are used in doors and windows such as resin windows. In addition, resin molded products containing lead stabilizers as heat stabilizers have been used in the past. When such resin molded products containing lead stabilizers are recycled to produce polyvinyl chloride resin compositions, it is best to remove the lead in the resin molded products from the viewpoint of safety. In this regard, a polyvinyl chloride recovery method is known that removes heavy metals from waste vinyl chloride resin compositions to recover polyvinyl chloride (see Patent Document 1).

[0003] In the conventional polyvinyl chloride recovery method described in Patent Document 1, waste vinyl chloride resin composition is dissolved in an organic solvent to prepare a polymer solution. Furthermore, after the polymer solution is brought into contact with an adsorbent, heavy metals are removed from the polymer solution by solid-liquid separation. However, the process of dissolving the waste vinyl chloride resin composition in an organic solvent and the process of preparing the polymer solution are both time-consuming. In addition, when recovering polyvinyl chloride from the polymer solution from which heavy metals have been removed, the polymer solution must be brought into contact with a precipitate solution to precipitate the polyvinyl chloride, which may also complicate the process for recovering the polyvinyl chloride for reuse.

[0004] Patent Document 1: Japanese Patent Application Publication No. 2008-174666 Summary of the invention

[0005] The present invention has been made in view of the above-mentioned conventional problems, and its object is to remove lead from a resin molded product containing polyvinyl chloride as a main component and a lead-based stabilizer to recycle the resin molded product, thereby efficiently producing a polyvinyl chloride resin composition.

[0006] The present invention is a method for producing a resin composition, which removes lead from a resin molded product containing polyvinyl chloride as a main component and a lead stabilizer to produce a polyvinyl chloride resin composition, and comprises:

[0007] A pulverizing step of pulverizing the resin molded product to form a pulverized material;

[0008] a dissolving step of immersing the pulverized material in an acidic or alkaline liquid to dissolve the lead contained in the lead-based stabilizer from the pulverized material into the liquid; and

[0009] The separation step is to separate the crushed material from the liquid in which the lead is dissolved.

[0010] According to the present invention, lead in a resin molded product containing polyvinyl chloride as a main component and a lead-based stabilizer can be removed to recycle the resin molded product, thereby efficiently producing a polyvinyl chloride resin composition. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 This is a flow chart showing the procedure for producing the polyvinyl chloride resin composition according to the present embodiment.

[0012] FIG. 2 is a diagram schematically showing the state of each stage in the production process of the polyvinyl chloride resin composition according to the present embodiment.

[0013] Figure 3 This is a diagram showing an example of the pulverized material immersed in an acidic or alkaline liquid according to the present embodiment.

[0014] Figure 4 This is a diagram showing a schematic structure of an extruder used for melting a crushed material according to the present embodiment.

[0015] Explanation of symbols

[0016] 10 ... resin molded product, 20 ... crushed material, 21 ... melt, 22 ... pellets, 30 ... liquid, 31 ... container, 40 ... adsorbent, 50 ... extruder, 51 ... feed port, 52 ... filter, 53 ... extrusion port, R ... maximum size. DETAILED DESCRIPTION

[0017] One embodiment of the method for producing a resin composition of the present invention will be described with reference to the drawings.

[0018] In the method for producing a resin composition of the present embodiment, lead is removed from a resin molded product containing polyvinyl chloride as a main component and a lead-based (Pb-based) stabilizer to produce a polyvinyl chloride resin composition. Thus, the resin molded product that has been produced is reused, and the resin molded product is recycled into a resin composition to produce a new resin composition.

[0019] Figure 1 FIG. 2 is a diagram schematically showing the state of each stage in the process of producing the polyvinyl chloride resin composition according to the present embodiment.

[0020] As shown in the figure, the useless resin molded product 10 (see A in FIG. 2 ) is recovered ( Figure 1S101). The resin molded product 10 is a molded product molded from a synthetic resin. The synthetic resin is polyvinyl chloride (PVC), and the resin molded product 10 is a polyvinyl chloride molded product having polyvinyl chloride as a main component and containing a lead stabilizer. In addition, the polyvinyl chloride is a hard polyvinyl chloride without adding a plasticizer, or a soft polyvinyl chloride with adding a plasticizer. The plasticizer is an additive for giving the polyvinyl chloride flexibility, which makes the polyvinyl chloride soft.

[0021] The stabilizer is a heat stabilizer used to inhibit the thermal decomposition of polyvinyl chloride. When the polyvinyl chloride is heated and formed, it is used to inhibit the decomposition of the polyvinyl chloride due to heat. The lead stabilizer is a stabilizer containing lead components, such as lead stearate, tribasic lead sulfate, dibasic lead phthalate, and dibasic lead stearate. The resin molded product 10 is made of polyvinyl chloride and contains various additives (such as modifiers) in addition to the lead stabilizer. The resin molded product 10 is, for example, a resin profile, a synthetic resin injection molded product, a resin sheet, and a resin hose.

[0022] Here, the resin molded product 10 is a resin profile, and A in FIG2 shows a cross section of the resin molded product 10 that is orthogonal to the length direction. The resin profile is a profile (extruded profile) formed by extruding a synthetic resin, and the resin molded product 10 is a polyvinyl chloride profile made of polyvinyl chloride. Specifically, the resin molded product 10 is a resin molded product (resin profile) of a resin window that has been used in doors and windows. The resin window has a synthetic resin window frame (resin window frame) and a window sash, and the window sash includes a synthetic resin frame (resin frame), and the resin window frame and the resin frame are respectively formed by the resin molded product 10.

[0023] In this way, the resin molded product 10 is a resin molded product (waste resin molded product) that is a discarded resin profile. The resin molded product 10 is used as a raw material, and the lead contained in the lead-based stabilizer is removed from the resin molded product 10 to manufacture a polyvinyl chloride resin composition. At this time, the lead contained in the resin molded product 10 is removed by a lead removal treatment to reduce the lead content, and polyvinyl chloride is recovered from the resin molded product 10. The lead concentration in the manufactured polyvinyl chloride resin composition is lower than the lead concentration in the original resin molded product 10. The polyvinyl chloride resin composition is a composition with polyvinyl chloride as the main component, and is used as a raw material for polyvinyl chloride molded products (recycled molded products).

[0024] Prior to the lead removal process, the recovered resin molded product 10 is crushed by a crusher to form a crushed material 20 of the resin molded product 10 (see B in FIG. 2 ) ( Figure 1The crusher is, for example, an impact crusher. When the resin molded product 10 is long or large, before being crushed by the crusher, the resin molded product 10 is first formed into a size that can be crushed by the crusher, such as by cutting the resin molded product 10. In this way, the resin molded product 10 is crushed to generate crushed material 20. The crushed material 20 is formed into, for example, a flake shape, a granular shape, or a powder shape.

[0025] After the resin molded product 10 is pulverized (see C in FIG. 2 ), the pulverized material 20 of the resin molded product 10 is immersed in an acidic or alkaline liquid 30, so that the lead contained in the lead stabilizer of the resin molded product 10 is dissolved from the pulverized material 20 into the liquid 30 ( Figure 1 S103). The acidic or alkaline liquid 30 is a solution for dissolving the lead in the crushed material 20 and is contained in a container 31. The acidic liquid 30 is, for example, hydrochloric acid, sulfuric acid, nitric acid, which are various acids that are not diluted with water or various acids that are diluted with water. The alkaline liquid 30 is, for example, an aqueous sodium hydroxide solution.

[0026] The crushed material 20 is put into the liquid 30 in the container 31, and the crushed material 20 is immersed in the liquid 30. In the process of immersing the crushed material 20 in the liquid 30, the lead in the crushed material 20 gradually dissolves in the liquid 30. In addition, the lead on the surface of the crushed material 20 is first dissolved in the liquid 30, and then the lead inside the crushed material 20 is gradually dissolved in the liquid 30. By dissolving the lead in the liquid 30, the lead can be removed from the crushed material 20.

[0027] Figure 3 This is a diagram showing an example of the pulverized material 20 immersed in the acidic or alkaline liquid 30 according to the present embodiment.

[0028] As shown in the figure, by crushing the resin molded product 10, crushed materials 20 of various shapes and maximum sizes R are formed. The maximum size R of the crushed materials 20 is the size of the largest part of the outer shape of each crushed material 20. The maximum size R of the crushed materials 20 immersed in the liquid 30 is a size in the range of 200μm to 10mm. Therefore, when crushing the resin molded product 10, the resin molded product 10 is crushed in such a way that the maximum size R of the crushed materials 20 is between 200μm and 10mm. Alternatively, after crushing the resin molded product 10, crushed materials 20 with a maximum size R less than 200μm and crushed materials 20 with a maximum size R greater than 10mm are separated and removed using a separation device, and crushed materials 20 with a maximum size R of 200μm to 10mm are sorted out. The crushed materials 20 with a maximum size R of 200μm to 10mm are immersed in the liquid 30.

[0029] In the lead removal treatment (treatment of removing lead from the pulverized material 20 by immersion) for removing lead from the pulverized material 20 (resin molded product 10) by immersing the pulverized material 20 in the liquid 30, the pulverized material 20 is immersed in the liquid 30, and the pulverized material 20 and the liquid 30 are stirred. Furthermore, the liquid 30 and the pulverized material 20 are heated so that the temperature of the liquid 30 and the pulverized material 20 reaches a preset temperature, and in this state, the pulverized material 20 is immersed in the liquid 30 for a preset time. For example, the temperature of the liquid 30 and the pulverized material 20 is maintained at a preset temperature by a constant temperature device, and in this state, the pulverized material 20 is immersed in the liquid 30 for a preset time, and the pulverized material 20 and the liquid 30 are stirred.

[0030] Then, the crushed material 20 is taken out from the liquid 30 in which lead is dissolved, and the crushed material 20 is separated from the liquid 30 ( Figure 1 Then, the crushed material 20 is washed with water by a water washing device. The liquid 30 is washed away from the crushed material 20 with water to wash the crushed material 20. Then, the water is removed from the crushed material 20 by a drying device to dry the crushed material 20.

[0031] In the crushed material 20 of the resin molded product 10 immersed in the liquid 30, the solubility of lead differs between the surface side and the center side. Therefore, after the treatment of removing the lead in the crushed material 20 by immersion, the following treatment is performed, that is, the lead is removed from the melt 21 of the crushed material 20 obtained by melting the crushed material 20 using the adsorbent 40 (see D in FIG. 2) (treatment of removing lead in the melt 21 using the adsorbent 40) ( Figure 1 S105). Thus, the lead remaining in the crushed material 20 after the impregnation is removed.

[0032] The melt 21 is a melt of polyvinyl chloride obtained by melting the crushed material 20, and contains a lead stabilizer. When the crushed material 20 of polyvinyl chloride is heated and melted, the lead contained in the lead stabilizer becomes a cation in the melt 21, and the lead ions as lead cations inhibit the thermal decomposition of polyvinyl chloride. In response to this, by adding the adsorbent 40 to the melt 21, the lead ions are adsorbed by the adsorbent 40, thereby removing the lead from the melt 21.

[0033] The adsorbent 40 is a solid cation adsorbent for adsorbing cations, and is used to adsorb cations, namely lead ions, in the melt 21 of the crushed material 20. The adsorbent 40 is, for example, a double hydroxide such as zeolite, chitosan, a porous material, or layered double hydroxide (LDH), and is formed into a powder or granular form. The adsorbent 40 uses an inorganic adsorbent to ensure that it will not decompose even at the temperature of the melt 21.

[0034] The adsorbent 40 is added to the crushed material 20 before melting, and then the crushed material 20 is melted, thereby adding the adsorbent 40 to the melt 21. Alternatively, after the crushed material 20 is melted, the adsorbent 40 is added to the melt 21. Here, the crushed material 20 and the powdered adsorbent 40 (adsorbent powder) are fed to the extruder, and the crushed material 20 is melted by the extruder. Therefore, the adsorbent 40 is added to the crushed material 20 before melting, and then the crushed material 20 is melted.

[0035] Figure 4 This is a diagram showing a schematic configuration of an extruder 50 used for melting the crushed material 20 according to the present embodiment.

[0036] As shown in the pressure diagram, the crushed material 20, the adsorbent 40, and various additives are fed into the extruder 50 from the feed port 51 (hopper) of the extruder 50. In addition, inside the extruder 50, the extruder 50 heats the crushed material 20 and the adsorbent 40 to increase their temperature, so that the crushed material 20 melts, and a molten material 21 ( Figure 1 In this way, the crushed material 20 separated from the liquid 30 is melted to obtain a melt 21 of the crushed material 20.

[0037] The extruder 50 mixes the pulverized material 20 and the adsorbent 40 while heating, so that the pulverized material 20 is heated and melted. As a result, the solid adsorbent 40 for adsorbing lead ions is added to the melt 21 of the pulverized material 20 inside the extruder 50. In addition, as the pulverized material 20 melts, lead ions are generated in the melt 21. A screw (not shown) is provided inside the extruder 50. The extruder 50 stirs and mixes the melt 21 and the adsorbent 40 by a rotating screw. The extruder 50 stirs the melt 21 to which the adsorbent 40 is added, mixes the melt 21 and the adsorbent 40, and uses the adsorbent 40 to adsorb the lead ions in the melt 21 ( Figure 1 The lead ions are adsorbed by the adsorbent 40, and lead is removed from the melt 21.

[0038] Here, the polyvinyl chloride as the main component of the resin molded product 10 is rigid polyvinyl chloride, and the polyvinyl chloride resin composition to be manufactured is a rigid polyvinyl chloride resin composition. Therefore, the melt 21 of the crushed material 20 is heated to a temperature suitable for melting rigid polyvinyl chloride. Specifically, the crushed material 20 is heated to a temperature range of 180 to 210° C. to melt the crushed material 20. The melt 21 to which the adsorbent 40 is added is heated to a temperature range of 180 to 210° C., and the melt 21 and the adsorbent 40 are stirred at a temperature of 180 to 210° C., so that the lead (lead ions) contained in the melt 21 is removed by the adsorbent 40.

[0039] Next, the adsorbent 40 adsorbed with lead ions is separated from the melt 21 ( Figure 1 S105-3) is performed to produce a polyvinyl chloride resin composition from which lead has been removed. A filter 52 for separating the adsorbent 40 is provided inside the extruder 50. The filter 52 is a sieve for filtering out the adsorbent 40 from the melt 21, allowing the melt 21 to pass through and preventing the adsorbent 40 from passing through. The extruder 50 allows the melt 21 to pass through the filter 52, and uses the filter 52 to separate the adsorbent 40 from the melt 21.

[0040] The mesh number (number) of the filter 52 is 20 to 100 meshes. The melt 21 is passed through the filter 52 having a mesh number in the range of 20 to 100 meshes, and the adsorbent 40 is separated from the melt 21 by the filter 52 having a mesh number in the range of 20 to 100 meshes. The mesh number of the filter 52 is the mesh number of the sieve specified in the ASTM standard (ASTM E11-04), and complies with the ASTM standard. The mesh size of the 20-mesh filter 52 is about 0.80 mm, and the mesh size of the 100-mesh filter 52 is about 0.15 mm. Therefore, the mesh size of the filter 52 is about 0.15 to 0.80 mm.

[0041] The extruder 50 continuously performs the melting of the crushed material 20, the stirring of the melt 21 to which the adsorbent 40 is added (adsorbing lead ions by the adsorbent 40), and the separation of the adsorbent 40 from the melt 21. Next, the extruder 50 extrude the melt 21 that has passed through the filter 52 from the extrusion port 53 (die head) to form the melt 21 ( Figure 1 In addition, the extrudate of the melt 21 extruded from the extrusion port 53 is cut into pellets 22 in sequence (see E in FIG. 2 ).

[0042] In this way, the extruded melt 21, i.e., the polyvinyl chloride resin composition, is processed to form pellets 22 ( Figure 1 The particles 22 are granular materials with polyvinyl chloride as the main component, and are formed into particles. Then, the polyvinyl chloride particles 22 are used to form a polyvinyl chloride molded product ( Figure 1 The molded product of polyvinyl chloride is, for example, a resin profile for doors and windows formed by extrusion molding.

[0043] In the method for producing a polyvinyl chloride resin composition according to the present embodiment described above, lead in a resin molded article 10 having polyvinyl chloride as a main component and containing a lead-based stabilizer can be removed, and the resin molded article 10 can be recycled and utilized, thereby efficiently producing a polyvinyl chloride resin composition. In addition, lead in the resin molded article 10 can be easily removed.

[0044] The lead removal treatment of the crushed material 20 is first performed by immersion before the lead removal treatment of the melt 21 is performed by the adsorbent 40. Thus, lead can be removed from the crushed material 20 before the melt 21 of the crushed material 20 and the adsorbent 40 are stirred, thereby reducing the lead content in the crushed material 20 and the melt 21.

[0045] When the maximum size R of the crushed material 20 is less than 200 μm, it is difficult to separate the crushed material 20 from the liquid 30. After the crushed material 20 is separated from the liquid 30, it may also become difficult to wash and dry the crushed material 20. In addition, when the maximum size R of the crushed material 20 is greater than 10 mm, the surface area per unit mass (specific surface area) of the crushed material 20 becomes small, which may affect the efficiency of dissolving the lead in the crushed material 20 in the liquid 30. It may also become difficult to feed the crushed material 20 into the extruder 50.

[0046] In contrast, when the maximum size R of the crushed material 20 is within the range of 200 μm to 10 mm (200 μm or more and 10 mm or less), the crushed material 20 can be easily separated from the liquid 30. In addition, the specific surface area of ​​the crushed material 20 can be ensured, so that the lead in the crushed material 20 can be efficiently dissolved in the liquid 30. The crushed material 20 can also be smoothly washed, dried, and fed into the extruder 50. The maximum size R of the crushed material 20 is more preferably a size within the range of 2 to 8 mm. As a result, the crushed material 20 can be smoothly separated from the liquid 30, and the dissolution efficiency of the lead in the crushed material 20 in the liquid 30 can be ensured.

[0047] When the polyvinyl chloride is hard polyvinyl chloride, if the temperature when the melt 21 to which the adsorbent 40 is added is stirred (the stirring temperature of the melt 21) is lower than 180°C, the viscosity of the melt 21 increases, which may make it difficult for the melt 21 to flow, affecting the stirring of the melt 21. It will also become difficult for the extruder 50 to extrude the melt 21. In addition, if the stirring temperature of the melt 21 is higher than 210°C, the hard polyvinyl chloride in the melt 21 may be thermally decomposed.

[0048] On the other hand, when the stirring temperature of the melt 21 is in the range of 180 to 210° C. (180° C. to 210° C.), the hard polyvinyl chloride in the melt 21 can be prevented from being thermally decomposed, and the viscosity of the melt 21 is made suitable for stirring, thereby promoting the flow stirring of the melt 21. The stirring temperature of the melt 21 is more preferably in the range of 190 to 200° C. Thus, the viscosity of the melt 21 can be maintained at a viscosity suitable for stirring, and the hard polyvinyl chloride in the melt 21 can be reliably prevented from being thermally decomposed.

[0049] The filter 52 can easily separate the adsorbent 40 from the melt 21 of the crushed material 20. However, when the filter 52 is a filter coarser than 20 mesh (a filter with a smaller mesh number), the adsorbent 40 may not be completely separated from the melt 21. In addition, when the filter 52 is a filter finer than 100 mesh (a filter with a larger mesh number), the pressure applied to allow the melt 21 to pass through the filter 52 becomes high, which may affect the efficiency of separating the adsorbent 40 from the melt 21. The pressure at which the extruder 50 extrude the melt 21 becomes high, which may also affect the production efficiency of the polyvinyl chloride resin composition, and there is a concern that the pressure of the melt 21 may cause the filter 52 to be damaged.

[0050] In contrast, when the mesh number of the filter 52 is within the range of 20 to 100 meshes (20 meshes or more and 100 meshes or less), the adsorbent 40 can be stably separated from the melt 21 of the crushed material 20, and the pressure applied to the melt 21 can be suppressed from becoming high, thereby ensuring the efficiency of separating the adsorbent 40 from the melt 21. In addition, the pressure of the extruder 50 extruding the melt 21 can be suppressed from becoming high, thereby ensuring the production efficiency of the polyvinyl chloride resin composition, and preventing the filter 52 from being damaged by the pressure of the melt 21. The mesh number of the filter 52 is more preferably within the range of 40 to 80 meshes. Thus, the adsorbent 40 can be efficiently separated from the melt 21 without applying a high pressure to the melt 21.

[0051] Furthermore, when the crushed material 20 is melted, polyvinyl chloride that does not contain lead (lead stabilizer) can be added to the crushed material 20 separated from the liquid 30, and the added polyvinyl chloride and the crushed material 20 are melted and mixed to produce a polyvinyl chloride resin composition. The polyvinyl chloride added to the crushed material 20 is a solid polyvinyl chloride, for example, formed into a powder or granular form. Among them, the polyvinyl chloride added to the crushed material 20 is unused polyvinyl chloride that does not contain lead, or polyvinyl chloride obtained by crushing a molded product of lead-free polyvinyl chloride, or it can be one or both of unused polyvinyl chloride and polyvinyl chloride obtained by crushing a molded product. The crushed material 20, the adsorbent 40, and the lead-free polyvinyl chloride are fed into an extruder, and the extruder 50 melts the crushed material 20 to which the lead-free polyvinyl chloride is added, and a melt 21 of polyvinyl chloride and the crushed material 20 is obtained. By adding the lead-free polyvinyl chloride, the lead concentration contained in the polyvinyl chloride resin composition can be reduced.

[0052] In the method for producing the polyvinyl chloride resin composition described above, after the lead removal treatment of the crushed material 20 is performed by impregnation (see C in FIG. 2 ), the lead removal treatment of the melt 21 is performed by the adsorbent 40 (see D in FIG. 2 ). In contrast, the polyvinyl chloride resin composition can be produced by performing the lead removal treatment of the crushed material 20 by impregnation instead of performing the lead removal treatment of the melt 21 by the adsorbent 40. In this way, the lead can still be removed. In particular, when the lead concentration in the polyvinyl chloride resin composition can be reduced to the target concentration by performing the lead removal treatment of the crushed material 20 by impregnation, it is effective to perform the lead removal treatment of the crushed material 20 by impregnation instead of performing the lead removal treatment of the melt 21 by the adsorbent 40. However, after performing the lead removal treatment of the crushed material 20 by impregnation, the lead concentration in the polyvinyl chloride resin composition can be further reduced by performing the lead removal treatment of the melt 21 by the adsorbent 40.

[0053] As described above, in the present embodiment, a method for producing a resin composition described in the following (1) to (3) is disclosed.

[0054] (1): A method for producing a resin composition, which comprises removing lead from a resin molded product having polyvinyl chloride as a main component and containing a lead-based stabilizer to produce a polyvinyl chloride resin composition, and comprises:

[0055] A pulverizing step of pulverizing the resin molded product to form a pulverized material;

[0056] a dissolving step of immersing the pulverized material in an acidic or alkaline liquid to dissolve the lead contained in the lead-based stabilizer from the pulverized material into the liquid; and

[0057] The separation step is to separate the crushed material from the liquid in which the lead is dissolved.

[0058] In the method for producing a resin composition described in (1), lead in a resin molded product containing polyvinyl chloride as a main component and a lead-based stabilizer can be removed to recycle the resin molded product, thereby efficiently producing a polyvinyl chloride resin composition.

[0059] (2): The method for producing a resin composition according to (1), wherein

[0060] In the dissolving step, the maximum size of the crushed material is 200 μm to 10 mm.

[0061] In the method for producing a resin composition according to (2), the pulverized material can be easily separated from the liquid, and lead in the pulverized material can be efficiently dissolved in the liquid.

[0062] (3): A method for producing a resin composition according to (1) or (2), comprising:

[0063] The mixing step is to add lead-free polyvinyl chloride to the pulverized material separated from the liquid, and melt-mix the polyvinyl chloride and the pulverized material.

[0064] In the method for producing a resin composition according to (3), the lead concentration contained in the polyvinyl chloride resin composition can be reduced by adding lead-free polyvinyl chloride.

Claims

1. A method for producing a resin composition, comprising removing lead from a resin molded product containing polyvinyl chloride as a main component and a lead stabilizer to produce a polyvinyl chloride resin composition, characterized in that: include: A pulverizing step of pulverizing the resin molded product to form a pulverized material; a dissolving step of immersing the pulverized material in an acidic or alkaline liquid to dissolve the lead contained in the lead stabilizer from the pulverized material into the liquid; as well as The separation step is to separate the crushed material from the liquid in which the lead is dissolved.

2. The method for producing a resin composition according to claim 1, wherein In the dissolving step, the maximum size of the crushed material is 200 μm to 10 mm.

3. The method for producing a resin composition according to claim 1 or 2, characterized in that: include: The mixing step is to add lead-free polyvinyl chloride to the crushed material separated from the liquid, and melt-mix the polyvinyl chloride and the crushed material.

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