Method for manufacturing a resin composition molded body, and apparatus for manufacturing a resin composition molded body.

Abstract

To provide a method for manufacturing a resin composition molded article that has excellent dimensional stability, is less prone to cracking, and has high water resistance, and can be industrially produced in an advantageous manner, and a manufacturing apparatus for a resin composition molded article that can be advantageously used in this manufacturing method. [Solution] A raw material mixture containing a thermoplastic resin and a non-thermoplastic substance is heated and kneaded to melt at least a portion of the thermoplastic resin to produce a molten raw material mixture containing the molten resin. The molten raw material mixture is extruded to form a molten molded body having a surface temperature of -30°C or higher relative to the melting point of the molten resin. The surface of the molten molded body is cooled to a first temperature within the range of -90°C to -20°C relative to the melting point of the molten resin, and then cooled to a second temperature lower than the first temperature to solidify the surface of the molten molded body, and then the entire molten molded body is solidified.

Description

Technical Field

[0001] The present disclosure relates to a method for manufacturing a resin composition molded body and an apparatus for manufacturing a resin composition molded body.

Background Art

[0002] As a method for manufacturing a resin composition molded body containing a thermoplastic resin and a non-thermoplastic substance, an extrusion molding method is known. In the extrusion molding method, using an extruder, a raw material mixture containing a thermoplastic resin and a non-thermoplastic substance is heated and kneaded to produce a molten raw material mixture, and the molten raw material mixture is extrusion-molded using an extrusion die. As the extrusion die, a cooling die having a first cooling part (A) with a plurality of flow paths and a second cooling part (B) with a flow path where the molten raw material mixture passing through the flow paths is merged is used, and the cooling temperatures of the first cooling part (A) and the second cooling part (B) are set so that the temperature of the molten raw material mixture passing through the flow paths becomes lower toward the vicinity of the cooling die than the central part of the molten raw material mixture (for example, see Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When manufacturing a resin composition molded body containing a thermoplastic resin and a non-thermoplastic substance by an extrusion molding method, the molten raw material mixture produced by an extruder contains unmolten non-thermoplastic substances. For this reason, cavities are likely to be generated inside the molded body extruded from the extrusion die, and cracks may occur starting from the cavities when the molded body is cooled. Also, when the molded body is cooled, gaps may occur between the thermoplastic resin and the non-thermoplastic substance due to the solidification of the molten thermoplastic resin, resulting in a decrease in dimensional stability or a decrease in water resistance.

[0005] The present disclosure aims to provide a method for manufacturing a resin composition molded article that has excellent dimensional stability, is less prone to cracking, and has high water resistance, and to provide an apparatus for manufacturing a resin composition molded article that can be advantageously used in the present manufacturing method. [Means for solving the problem]

[0006] This disclosure relates to a method for manufacturing a resin composition molded article, comprising: heating and kneading a raw material mixture containing a thermoplastic resin and a non-thermoplastic substance to melt at least a portion of the thermoplastic resin to produce a molten raw material mixture containing the molten resin; extruding the molten raw material mixture to form a molten molded article having a surface temperature of -30°C or higher relative to the melting point of the molten resin; cooling the surface of the molten molded article to a first temperature in the range of -20°C to -90°C relative to the melting point of the molten resin, then cooling it to a second temperature lower than the first temperature to solidify the surface of the molten molded article, and finally solidifying the entire molten molded article. [Brief explanation of the drawing]

[0007] [Figure 1] This is a perspective view of an example of a molded resin composition obtained by a manufacturing method according to one embodiment of the present disclosure. [Figure 2] This is a schematic cross-sectional view of an example of a manufacturing apparatus for a resin composition molded article according to one embodiment of the present disclosure. [Figure 3] Figure 2 is an enlarged cross-sectional view of the extrusion die of the manufacturing apparatus shown. [Figure 4] This is a cross-sectional view taken along line IV-IV in Figure 3. [Figure 5] This is a schematic cross-sectional diagram showing the flow of the molten raw material mixture through an extrusion die. [Figure 6] Figure 2 shows enlarged cross-sectional views of the primary and secondary coolers of the manufacturing apparatus. [Figure 7] This is a cross-sectional view taken along the line VII-VII in Figure 7. [Figure 8] This is a cross-sectional view of the molten body after passing through the second primary cooler. [Figure 9] Figure 2 is an enlarged cross-sectional view of the third cooler of the manufacturing apparatus shown. [Figure 10] This is a cross-sectional view along line XX in Figure 9. [Figure 11] This is a cross-sectional view of the molten body after it has passed through the third cooler. [Figure 12] This is an enlarged schematic cross-sectional view showing a modified example of a manufacturing apparatus for a resin composition molded article according to one embodiment of the present disclosure. [Figure 13] This is a perspective view of another example of a resin composition molded article obtained by a manufacturing method according to one embodiment of the present disclosure. [Figure 14] This is an enlarged schematic cross-sectional view showing yet another modification of a manufacturing apparatus for a resin composition molded article according to one embodiment of the present disclosure. [Figure 15] Figure 14 shows a cross-sectional view taken along the line XV-XV. [Figure 16] This is a cross-sectional view taken along the line XVI-XVI in Figure 14. [Figure 17] This is a cross-sectional view taken along line XVII-XVII in Figure 14. [Modes for carrying out the invention]

[0008] The embodiments of this disclosure will be described in detail below with reference to the drawings.

[0009] Figure 1 is a perspective view of an example of a resin composition molded article obtained by a manufacturing method according to one embodiment of the present disclosure. In Figure 1, the resin composition molded article 1 is in the form of a plate. The resin composition molded article 1 can be used, for example, as a paving material. Note that the resin composition molded article to be manufactured in this embodiment is not limited to a plate. For example, it may be in the form of a columnar body.

[0010] A method for manufacturing the resin composition molded body 1 will be described while referring to FIGS. 2 to 11. As shown in FIG. 2, the manufacturing apparatus 100 includes an extruder 10, an extrusion die 20, a first primary cooler 30, a second primary cooler 40, a first secondary cooler 50, a second secondary cooler 60, and a cutter 70. In the drawings, the X direction is the longitudinal direction of the manufacturing apparatus 100, the Y direction is the width direction of the manufacturing apparatus 100, and the Z direction is the height direction of the manufacturing apparatus 100.

[0011] The extruder 10 includes a screw 11 extending in the X direction and a hopper 12 disposed upstream of the screw 11. The raw material mixture 2 is stored in the hopper 12. The extruder 10 heats and kneads the raw material mixture 2 supplied from the hopper 12 with the screw 11 to melt at least a part of the thermoplastic resin, and generates a molten raw material mixture 3 containing the molten resin. The molten raw material mixture 3 is extruded in the X direction. The temperature of the extruder 10 when heating and kneading the raw material mixture 2 may be, for example, within the range of not less than the melting point of the thermoplastic resin + 10 ° C or less.

[0012] The raw material mixture 2 contains a thermoplastic resin and a non-thermoplastic substance. The ratio of the thermoplastic resin to the non-thermoplastic substance is, for example, within the range of 10:90 to 90:10 by mass ratio.

[0013] The thermoplastic resin may have a melting point (in the case of an amorphous thermoplastic resin having no crystalline part, it means the softening point) of 80 ° C or higher. Examples of the thermoplastic resin include polyethylene (PE), polypropylene (PP), polystyrene (PS), acrylonitrile-butadiene-styrene resin (ABS), polymethyl methacrylate (PMMA), polycarbonate (PC), polyamide 12 (PA12), polyacetal (POM), polyethylene terephthalate (PET), polyamide 6 (PA6), polybutylene terephthalate (PBT), polyphenylene sulfide (PPS), and polyether ether ketone (PEEK). These thermoplastic resins may be used alone or in combination of two or more.

[0014] The raw material mixture 2 contains multiple types of thermoplastic resins, and it is preferable that the molten resin contained in the molten raw material mixture 3 produced by the heat kneading of the extruder 10 contains multiple types of thermoplastic resins. The multiple types of thermoplastic resins contained in the molten resin may each have a different melting point. The difference in melting point between the thermoplastic resin having the highest melting point and the thermoplastic resin having the lowest melting point among the multiple types of thermoplastic resins contained in the molten resin may be 10 °C or more. However, it is not necessary for all the thermoplastic resins contained in the raw material mixture 2 to produce the molten resin. For example, some of the thermoplastic resins contained in the raw material mixture 2 may exist in a solid state in the molten resin.

[0015] The non-thermoplastic substance may be a thermosetting resin, an organic filler, or an inorganic filler. Examples of the thermosetting resin include polyimide (PI), polyurethane (PU), and phenolic resin (PF). Examples of the organic filler include cellulose-based material powders such as wood powder and pulp powder. Examples of the inorganic filler include calcium carbonate, magnetic substances, non-magnetic metals, glass, pebbles, metals, shells, sand, silica gel, and iron-based oxygen absorbers. The non-thermoplastic substance may be used alone or in combination of two or more.

[0016] The raw material mixture 2 may contain plastic waste. As the plastic waste, waste plastics derived from general waste, waste plastics derived from industrial waste, and waste plastics derived from marine plastic waste can be used.

[0017] The extrusion die 20 is connected to the extruder 10 via a connecting portion 15. As shown in Figures 3 and 4, the extrusion die 20 has branching channels 21 for branching the molten raw material mixture 3 and a confluence channel 22 for confluence of the molten raw material mixture 3 branched in the branching channels 21. The number of branching channels 21 is not limited, but there are two in the Y direction and two in the Z direction. The extrusion die 20 molds the molten raw material mixture 3 that has been confluenced in the confluence channel 22 to produce a molten molded body 4, which is then extruded in the X direction. The surface temperature of the molten molded body 4 extruded from the extrusion die 20 is -30°C or higher relative to the melting point of the molten resin contained in the molten raw material mixture 3. The surface temperature of the molten molded body 4 relative to the melting point of the molten resin may be within the range of -30°C or higher and 0°C or lower. The melting temperature of the molten raw material mixture 3 is the temperature of the molten raw material mixture 3 inside the extruder 10. The temperature of the molten raw material mixture 3 may be measured directly, or the internal temperature of the extruder 10 may be measured and this may be used as the temperature of the molten raw material mixture 3.

[0018] As shown in Figure 5, by merging the molten raw material mixture 3, which has been branched in the branched channel 21, in the confluence channel 22, the flow front 3a on the central side of the molten raw material mixture 3 flowing through the flow channels of the extrusion die 20 becomes smaller. As the flow front 3a becomes smaller, the difference between the flow front 3a of the molten raw material mixture 3 and the skin layer 3b in contact with the extrusion die 20 becomes smaller, and the thickness of the skin layer 3b becomes thinner. Therefore, the molten molded body 4 can be extruded from the extrusion die 20 at a uniform speed at both the surface and the center. If the temperature of the molten raw material mixture 3 introduced into the extrusion die 20 is excessively high, the fluidity of the molten raw material mixture 3 improves, but the fluidity of the molten raw material mixture 3 on the skin layer 3b side becomes lower, which can lead to a large difference in flow velocity between the skin layer 3b side and the central side of the molten raw material mixture 3. When the flow velocity difference becomes large, the molten molded body 4 extruded from the extrusion die 20 will have a higher density at the center and a lower density at the outside, making the final molded body more prone to cracking. On the other hand, if the temperature of the molten raw material mixture 3 becomes excessively low, the fluidity of the molten raw material mixture 3 decreases, and when the molten raw material mixture 3 branched in the branched channel 21 is merged in the confluence channel 22, the merged molten raw material mixture 3 may not join together properly. If the molten raw material mixture 3 does not join together, a cavity will form inside the molten molded body 4 extruded from the extrusion die 20, making the final molded body more prone to cracking. Furthermore, even if no cracks appear in the molded body, its water resistance may decrease, and cracks may occur due to water absorption and expansion upon contact with water. For this reason, in this embodiment, the temperature of the extrusion die 20 is adjusted so that the surface temperature of the molten molded body 4 extruded from the extrusion die 20 reaches the above temperature.

[0019] The primary cooler 30 is connected to the extrusion die 20. As shown in Figure 6, the primary cooler 30 has a cooling section 31 that contacts the surface of the molten body 4. By bringing the molten body 4 formed in the extrusion die 20 into contact with the cooling section 31 without contacting the outside air, deformation due to the internal pressure of the molten body 4 can be suppressed. The primary cooler 30 may be a cooling solid member adjusted to a first temperature within the range of -100°C to -50°C relative to the temperature at which the molten body 4 was formed. In the primary cooler 30, the surface of the molten body 4a forming the molten body 4 is cooled and solidified to produce a solidified body 4b.

[0020] The second primary cooler 40 is connected to the first primary cooler 30. As shown in Figure 6, the second primary cooler 40 has a cooling section 41 that is in contact with the surface of the molten molded body 4. The second primary cooler 40 may be a cooling solid member adjusted to a second temperature lower than the first temperature. By using a cooling solid member as the second primary cooler 40, the surface of the molten raw material mixture 3 can be cooled to the second temperature. The second temperature may be in a range of, for example, -70°C or more and -20°C or less relative to the first temperature.

[0021] The first primary cooler 30 has cooling tubes 32, and the second primary cooler 40 also has cooling tubes 42. Cooling tubes 32 and 42 are supplied with a cooling medium W. As the cooling medium W, hot water, steam, or chiller cooling water can be used. As shown in Figure 7, the cooling tubes 42 are arranged along the Y direction so as to sandwich the cooling section 41. The cooling medium W flows in the cooling tubes 42 located above the cooling section 41 and the cooling tubes 42 located below the cooling section 41 so as to face each other. The same applies to the cooling tubes 32 of the first primary cooler 30. Metals and ceramics can be used as materials for the first primary cooler 30 and the second primary cooler 40.

[0022] As shown in Figure 8, the molten body 4 cooled in the second primary cooler 40 forms a uniform solidified body 4b on its surface. The thickness of the solidified body 4b may be in the range of 0.1 mm to 5 mm.

[0023] As shown in Figures 9 and 10, the first secondary cooler 50 has a through-hole 51 through which the molten body 4 passes. Cooling pipes 52 are arranged outside the through-hole 51. Cooling medium W is supplied to the cooling pipes 52. As the cooling medium W, a cooling liquid such as cooling water adjusted to a temperature lower than the second temperature can be used. Since the cooling liquid has a higher heat capacity than solid materials, the entire molten body 4 can be cooled by using a cooling liquid as the cooling medium W. The temperature of the cooling medium W (temperature of the first secondary cooler 50) may be, for example, in the range of 20°C to 50°C. A degassing pipe 53 is arranged in the through-hole 51. By degassing the inside of the through-hole 51 with the degassing pipe 53 and creating a vacuum, the molten body 4 can be reliably brought into contact with the first secondary cooler 50. This allows the outer circumference of the molten body 4 to be cooled uniformly and improves the dimensional stability of the molten body 4.

[0024] By cooling the entire molten body 4 in the first secondary cooler 50, the thickness of the solidified body 4b increases, as shown in Figure 11.

[0025] As shown in Figure 2, the second secondary cooler 60 is a tank in which coolant is stored. By bringing the molten molded body 4 into contact with a large amount of coolant in the second secondary cooler 60, the entire molten molded body 4 can be cooled and solidified more reliably. Cooling water can be used as the coolant. The temperature of the cooling water (temperature of the second secondary cooler 60) may be, for example, in the range of 20°C to 50°C.

[0026] The cutting machine 70 cuts the solidified molded body produced in the second secondary cooler 60 to adjust it to a predetermined size.

[0027] In the manufacturing apparatus 100 of this embodiment, the extrusion die 20 and the primary cooler 30 are directly connected, but an insulating material may be placed between the extrusion die 20 and the primary cooler 30. For example, as shown in Figure 12, an insulating material 25a for supplying the molten molded body 4 extruded from the extrusion die 20 to the primary cooler 30 and a supporting insulating material 25b placed outside the insulating material 25a may be placed. By placing an insulating material between the extrusion die 20 and the primary cooler 30, the primary cooler 30 is insulated from the extrusion die 20, so that the temperature of the primary cooler 30 can be adjusted with precision. In addition, in order to improve the heat insulation between the extrusion die 20 and the primary cooler 30, the contact area between the extrusion die 20 and the primary cooler 30 may be reduced.

[0028] In the manufacturing apparatus 100 of this embodiment, the object to be manufactured is a solid type without a hollow portion, but the object to be manufactured is not limited to a solid type. For example, the object to be manufactured may be a hollow-type resin composition molded body 5 having a hollow portion 6, as shown in Figure 13.

[0029] When manufacturing a hollow resin composition molded body 5, members for forming a hollow section 6 are placed in the extrusion die 20, the first primary cooler 30, and the second primary cooler 40. For example, as shown in Figures 14 and 15, a hollow forming section 23 is placed in the confluence channel 22 of the extrusion die 20a. Hollow cooling members 33 and 43 connected to the hollow forming section 23 are placed in the first primary cooler 30a and the second primary cooler 40a, respectively.

[0030] A method for manufacturing a resin composition molded article 1 using a manufacturing apparatus 100 configured as described above includes a melting step, a forming step, a primary cooling step, a secondary cooling step, and a cutting step.

[0031] The melting process involves using an extruder 10 to heat and knead a raw material mixture 2 containing a thermoplastic resin and a non-thermoplastic substance to melt at least a portion of the thermoplastic resin and produce a molten raw material mixture 3 containing the molten resin. The heating temperature when heating and kneading the raw material mixture 2 should be such that each material contained in the raw material mixture 2 does not undergo thermal decomposition. For example, if the raw material mixture 2 contains cellulose-based material powder, at least a portion of the thermoplastic resin in the raw material mixture 2 may be a low-melting-point thermoplastic resin with a melting point of 80°C or higher and less than 190°C, and the heating temperature may be within the range of the melting point of the low-melting-point thermoplastic resin and 200°C or lower. If the heating temperature is 200°C, the high-melting-point thermoplastic resin with a melting point exceeding 200°C will not melt and will exist in a solid state in the molten raw material mixture 3. The heating temperature may also be within the range of the melting point of the low-melting-point thermoplastic resin + 5°C or higher and 30°C or lower. As the low-melting-point thermoplastic resin, PE, PP, PS, ABS, PMMA, PC, PA12, and POM can be used. For example, if the low-melting-point thermoplastic resin is PE (melting point: 145°C), the heating temperature may be 150°C or higher, or it may be within the range of 150°C to 175°C. If the low-melting-point thermoplastic resin is PP (melting point: 160°C), the temperature of the extruder 10 may be 165°C or higher, or it may be within the range of 165°C to 190°C.

[0032] The forming process involves extruding the molten raw material mixture 3 using an extrusion die 20 to form a molten molded body 4 whose surface temperature is -30°C or higher than the temperature of the molten resin in the molten raw material mixture 3. For example, if the temperature of the molten resin is 170°C, the temperature of the molten molded body 4 may be within the range of 140°C to 170°C.

[0033] The primary cooling step involves using a first primary cooler 30 to cool the surface of the molten molded body 4 to a first temperature within the range of -90°C to -20°C relative to the temperature of the molten resin of the molten raw material mixture 3, and then using a second primary cooler 40 to cool it to a second temperature lower than the first temperature, thereby solidifying the surface of the molten molded body 4. The second temperature may be within the range of -70°C to -20°C relative to the first temperature. For example, if the temperature of the molten resin is 170°C, the first temperature may be within the range of 70°C to 120°C. If the first temperature is 100°C, the second temperature may be within the range of 30°C to 80°C.

[0034] The secondary cooling process uses a first secondary cooler 50 and a second secondary cooler 60 to solidify the entire molten molded body 4. The first secondary cooler 50 and the second secondary cooler 60 are located within a range of, for example, 20°C to 50°C, and gradually cool the molten molded body 4 to its operating temperature.

[0035] The cutting process involves cutting the solidified molten body 4 to obtain a resin composition molded body 1.

[0036] In the manufacturing method of the resin composition molded article 1 of this embodiment, which has the above configuration, the molten molded article 4 obtained in the molding process, which has a surface temperature of -30°C or higher relative to the temperature of the molten raw material mixture 3 and is in an unsolidified state, is cooled in stages in the primary cooling process using a first primary cooler 30 and a second primary cooler 40. As a result, a solidified body 4b with uniform thickness and low crack occurrence can be formed on the surface of the molten molded article 4. Then, the molten molded article 4 with the solidified body 4b formed on its surface is cooled in the secondary cooling process, which reduces deformation due to internal pressure of the molten molded article 4, and allows the inside of the molten molded article 4 to solidify uniformly. For this reason, the resin composition molded article 1 obtained by the above manufacturing method of the resin composition molded article has excellent dimensional stability, is less prone to cracking, and has high water resistance.

[0037] Furthermore, in the method for manufacturing a resin composition molded article of this embodiment, when an extrusion die 20 having a branched channel 21 and a converging channel 22 is used in the molding process, and the molten raw material mixture 3 is branched into two or more channels, then converged, and then the molten molded article 4 is molded, the molten molded article 4 can be extruded from the extrusion die 20 at a uniform speed from the surface to the center. As a result, in the primary cooling process, a solidified body 4b with uniform thickness and fewer cracks can be formed more stably on the surface of the molten molded article 4.

[0038] Furthermore, in the method for manufacturing a resin composition molded article of this embodiment, if a cooling solid member adjusted to a first temperature is used as the first primary cooler 30 and a cooling solid member adjusted to a second temperature is used as the second primary cooler 40 in the primary cooling step, the surface portion of the molten molded article 4 can be cooled uniformly. As a result, a solidified body 4b with a more uniform thickness and fewer cracks can be formed on the surface of the molten molded article 4 after cooling.

[0039] In the method for manufacturing a resin composition molded article of this embodiment, if the overall cooling of the molten molded article 4 is carried out in the second secondary cooler 60 of the secondary cooling step by bringing a cooling liquid adjusted to a temperature lower than the second temperature into contact with the surface of the molten molded article 4, the inside of the molten molded article 4 can be solidified more stably and uniformly. If the overall cooling of the molten molded article 4 is carried out in stages using the first secondary cooler 50 and the second secondary cooler 60 in the secondary cooling step, the inside of the molten molded article 4 can be solidified even more stably and uniformly.

[0040] In the method for manufacturing a resin composition molded article of this embodiment, if the raw material mixture 2 includes a low-melting-point thermoplastic resin having a melting point in the range of 80°C to less than 190°C, and the raw material mixture 2 is heated and kneaded in the extruder 10 at a temperature range of above the melting point of the low-melting-point thermoplastic resin and below 200°C, the fluidity of the molten raw material mixture 3 is improved, so that a molten molded article 4 with fewer cracks can be obtained in the extruder mold 20. In addition, since the heating temperature of the extruder 10 is 200°C or lower, the time required to cool the molten molded article 4 formed in the extruder mold 20 to the usage temperature (20°C to 50°C) can be shortened.

[0041] Furthermore, the method for manufacturing a lipid composition molded article of this embodiment is applicable to molded articles of any shape. For example, even with shapes prone to molding defects, such as structures with fine irregularities on the outermost surface, structures with interlocking shapes (tongue and groove shapes) necessary for assembly and construction, and structures with hollow shapes, it is possible to manufacture molded articles with excellent dimensional stability, low cracking, and high water resistance.

[0042] The manufacturing apparatus 100 of this embodiment, configured as described above, can be advantageously used in the above-mentioned method for manufacturing a molded resin composition.

[0043] While embodiments of the present disclosure have been described above, the disclosure is not limited thereto. For example, in this embodiment, the primary cooling process is carried out using two coolers, a first primary cooler 30 and a second primary cooler 40, but the number of coolers is not limited to two. For example, a third primary cooler may be placed downstream of the second primary cooler 40. The temperature of the third primary cooler may be intermediate between the temperature of the second primary cooler 40 and the temperature of the first secondary cooler 50. Also, in this embodiment, the secondary cooling process is carried out using two coolers, a first secondary cooler 50 and a second secondary cooler 60, but the number of coolers is not limited to two. For example, one of the first secondary cooler 50 and the second secondary cooler 60 may be omitted, or a third secondary cooler may be placed downstream of the second secondary cooler 60.

[0044] In this embodiment, an example of the heating temperature of the extruder 10 when the raw material mixture 2 contains cellulosic material powder is given as being within the range of the melting point of the low-melting-point thermoplastic resin and up to 200°C, but the heating temperature of the extruder 10 is not limited to this. When the raw material mixture 2 does not contain cellulosic material powder, the heating temperature of the extruder 10 may be set to a temperature exceeding 200°C, for example, within the range of 200°C to 300°C. In this case, at least a portion of the thermoplastic resin with a melting point exceeding 200°C may melt and exist as molten resin in the molten raw material mixture 3. When the heating temperature of the extruder 10 exceeds 200°C, the primary cooling step may be performed in stages using three or more coolers. [Examples]

[0045] The present disclosure will be described in further detail below based on examples. However, the present disclosure is not limited to these examples.

[0046] [Example 1] As the thermoplastic resin, PE recovered from waste was prepared, and as the non-thermoplastic material, wood powder (passed through a 3 mm mesh sieve) was prepared. A raw material mixture containing this PE and wood powder in a mass ratio of 2:1 was obtained. Using the resin composition molded body manufacturing apparatus shown in Figure 2, a resin composition molded body was obtained by setting the temperatures of the extruder, extruder die, primary cooler, secondary cooler, and secondary cooler to the temperature conditions listed in Table 1 below.

[0047] [Example 2] A resin composition molded article was obtained in the same manner as in Example 1, except that PP recovered from waste was used as the thermoplastic resin, and the temperatures of the extruder, extruder die, primary cooler, secondary cooler, primary cooler, and secondary cooler were set to the temperature conditions shown in Table 1 below.

[0048] [Examples 3-5, Comparative Examples 1-7] A resin composition molded article was obtained in the same manner as in Example 1, except that a mixture of PP and PE recovered from waste was used as the thermoplastic resin, and the temperatures of the extruder, extruder die, primary cooler, secondary cooler, primary cooler, and secondary cooler were set to the temperature conditions shown in Table 1 below.

[0049] [Table 1]

[0050] [evaluation] For Examples 1-7 and Comparative Examples 1-10, the moldability, thickness, cross-sectional dimensions, appearance, and water resistance of the resin composition molded articles were evaluated using the following methods. The results are shown in Table 2 below.

[0051] (Can be molded or not) The molten bodies extruded from the extrusion die were visually observed. Those with uniform extrusion of the surface and center were designated as "A," while those with a significantly larger extrusion of the center relative to the surface were designated as "B." For those designated as "B," evaluation of thickness, cross-sectional dimensions, appearance, and joint connections was not performed.

[0052] (Thickness cross-sectional dimensions) The thickness cross-sectional dimensions of the resin composition molded body were measured at three locations: the center and the edges of the resin composition molded body, using an image measuring instrument. Among the three measured thickness cross-sectional dimensions, those with the largest difference from the target dimension (20 mm) were classified as "A" if the difference was ±0.5 mm or less, "B" if it was greater than ±0.5 mm and less than or equal to ±1.0 mm, "C" if it was greater than ±1.0 mm and less than or equal to ±2.0 mm, and "D" if it was greater than ±2.0 mm.

[0053] (exterior) The edges of molded resin compositions (1000 mm in length x 20 mm in thickness) were visually inspected to check for cracks. As a result, those with no cracks longer than 0.5 mm were classified as "A", those with fewer than 5 cracks between 0.5 mm and 1.0 mm in length were classified as "B", those with 5 or more cracks between 0.5 mm and 1.0 mm in length were classified as "C", and those with coarse cracks longer than 1.0 mm were classified as "D".

[0054] (water resistance) An immersion test was conducted in which a molded resin composition was immersed in hot water adjusted to 60°C. The molded resin composition was removed from the hot water each day, its thickness was measured, and the rate of change in the thickness of the molded resin composition relative to the previous day's thickness was calculated using the following formula. Change in thickness (%) = (Thickness of the molded resin composition - Thickness of the molded resin composition on the previous day) / Thickness of the molded resin composition on the previous day × 100

[0055] When the rate of change in thickness became 0.5% or less, the rate of expansion of the thickness of the resin composition molded body due to water absorption was considered to have reached equilibrium, and the end cross section (length 1000 mm x thickness 20 mm) of the resin composition molded body after the immersion test was visually observed. As a result, those in which no cracks with a major axis of 1 mm or more were observed were classified as "A", those in which microcracks with a major axis of 1 to less than 3 mm were observed were classified as "B", and those in which microcracks with a major axis of 3 mm or more were observed were classified as "C".

[0056] [Table 2]

[0057] From the results in Tables 1 and 2, it can be seen that, according to Examples 1 to 7, in which the temperatures of the extrusion die, primary cooler, and secondary cooler are within the range of this disclosure, resin composition molded articles with excellent dimensional stability, low cracking, and high water resistance can be manufactured industrially advantageously. [Explanation of Symbols]

[0058] 1…Resin composition molded body, 2…Raw material mixture, 3…Molten raw material mixture, 3a…Flow front, 3b…Skin layer, 4…Molten molded body, 4a…Molten body, 4b…Solidified body, 5…Hollow type resin composition molded body, 6…Hollow section, 10…Extruder, 11…Screw, 12…Hopper, 15…Connecting section, 20, 20a…Extrusion die, 21…Branching channel, 22…Converging channel, 23…Hollow forming section, 25a ...Insulation material for supplying molten molded body, 25b...Insulation material for support, 30, 30a...Primary cooler, 31...Cooling section, 32...Cooling pipe, 33...Hollow cooling component, 40, 40a...Secondary cooler, 41...Cooling section, 42...Cooling pipe, 43...Hollow cooling component, 50...First secondary cooler, 51...Through hole, 52...Cooling pipe, 53...Degassing pipe, 60...Secondary cooler, 70...Cutting machine, 100...Manufacturing equipment

Claims

1. A raw material mixture containing a thermoplastic resin and a non-thermoplastic substance is heated and kneaded to melt at least a portion of the thermoplastic resin, thereby producing a molten raw material mixture containing the molten resin. The molten raw material mixture is extruded to form a molten molded body whose surface temperature is -30°C or higher relative to the melting point of the molten resin. A method for manufacturing a resin composition molded article, comprising: cooling the surface of the molten molded article to a first temperature within the range of -90°C to -20°C relative to the melting point of the molten resin; then cooling it to a second temperature lower than the first temperature to solidify the surface of the molten molded article; and finally solidifying the entire molten molded article.

2. A method for producing a resin composition molded article according to claim 1, wherein the molten raw material mixture is branched into two or more channels, then merged, and then molded.

3. A method for producing a resin composition molded article according to claim 1, wherein the second temperature is within the range of -100°C or more and -50°C or less relative to the first temperature.

4. A method for manufacturing a resin composition molded article according to claim 1, wherein the surface of the molten molded article is cooled by bringing a cooling solid member adjusted to a first temperature into contact with the molten molded article, and then bringing a cooling solid member adjusted to a second temperature into contact with the molten molded article.

5. The method for producing a resin composition molded article according to claim 1, wherein the entire molten molded article is cooled by bringing a cooling liquid, adjusted to a temperature lower than the second temperature, into contact with the surface of the molten molded article.

6. A method for producing a resin composition molded article according to claim 1, wherein the entire molten molded article is cooled in stages.

7. The method for producing a resin composition molded article according to claim 1, wherein the molten resin comprises a plurality of thermoplastic resins with different melting points, and the difference in melting points between the thermoplastic resin having the highest melting point and the thermoplastic resin having the lowest melting point among the plurality of thermoplastic resins is 10°C or more.

8. The thermoplastic resin includes a low-melting-point thermoplastic resin having a melting point in the range of 80°C or more and less than 190°C. A method for producing a resin composition molded article according to claim 1, comprising heating and kneading the raw material mixture in a temperature range of above the melting point of the low-melting-point thermoplastic resin and below 200°C.

9. The method for producing a resin composition molded article according to claim 1, wherein the raw material mixture includes plastic waste comprising at least one of waste plastics derived from general waste, waste plastics derived from industrial waste, and waste plastics derived from marine plastic waste.

10. An extruder that heats and kneads a raw material mixture containing a thermoplastic resin and a non-thermoplastic substance to melt the thermoplastic resin and extrudes the molten raw material mixture to the outside, An extrusion die for extruding the molten raw material mixture to form a molten molded body, A primary cooler that cools the surface of the molten molded body in stages to solidify the surface of the molten molded body, A manufacturing apparatus for a resin composition molded body, comprising a secondary cooler for cooling the entire molten molded body to solidify the entire molten molded body.

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