Method for manufacturing preform

Abstract

The purpose of the present invention is to more efficiently produce a preform having desired characteristics although using a resin sheet obtained by pulverizing a recovered polyester resin molded article into a sheet shape. A resin sheet, which is obtained by pulverizing the recovered polyester resin molded article into sheets, is subjected to a heat treatment under reduced pressure conditions. A raw material resin is prepared by mixing a heat-treated resin sheet and a resin pellet comprising at least one of a raw material of a polyester resin, a biomass material, a chemically recycled material and a mechanically recycled material at a predetermined ratio, and foreign matter is removed from a molten resin obtained by plasticizing the raw material resin. And injection-molding the preform by supplying the molten resin to an injection molding device.

Description

Technical Field

[0001] The invention relates to a method for manufacturing a prefabricated part. Background Art

[0002] Conventionally, synthetic resin containers obtained by forming a bottomed cylindrical preform using a polyester resin such as polyethylene terephthalate into a bottle shape by biaxial stretch blow molding or the like have been used in a wide range of fields as containers for various beverages, various seasonings, etc. Such containers are generally considered to be PET bottles, and in recent years, in response to social demands, a recycling technology called "bottle-to-bottle" has been studied, in which used PET bottles are collected and reused as recycling materials to manufacture PET bottles.

[0003] For example, Patent Document 1 discloses a technique in which resin flakes obtained by crushing recovered polyester resin molded products into flakes are decontaminated, resin pellets produced by melting the flakes are solid-phase polymerized, and then conveyed to an injection molding device to produce a preform.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2021-98350 Summary of the invention

[0007] Problems to be solved by the invention

[0008] In view of the above background technology, the present inventors have conducted intensive studies and have completed the present invention as a result of realizing that a preform having desired properties can be more efficiently manufactured by using resin flakes obtained by crushing recycled polyester resin molded products into flakes.

[0009] Means for solving problems

[0010] The manufacturing method of the preform of the present invention is as follows: heat-treating resin flakes obtained by crushing recycled polyester resin molded products into flakes under reduced pressure conditions; mixing the resin flakes subjected to the heat treatment with resin pellets composed of at least one of original materials, biomass materials, chemically recycled materials or mechanically recycled materials of polyester resin at a prescribed ratio to prepare a raw material resin; and removing foreign matter from a molten resin obtained by plasticizing the raw material resin, and supplying the molten resin to an injection molding device to injection-mold a preform.

[0011] In addition, the method for manufacturing a preform involved in the present invention can be as follows: preparing a raw material resin by mixing resin flakes obtained by crushing a recycled polyester resin molded product into flakes and resin pellets composed of at least one of a virgin material, a biomass material, a chemically recycled material, a mechanically recycled material, and a post-consumer recycled material of the polyester resin at a predetermined ratio; plasticizing the raw material resin after heating it under reduced pressure; and removing foreign matter from a molten resin obtained by plasticizing the raw material resin, and supplying the molten resin to an injection molding device to injection mold a preform.

[0012] Effects of the Invention

[0013] According to the present invention, a preform having desired characteristics can be manufactured more efficiently, although resin flakes obtained by pulverizing a recovered polyester-based resin molded product into flakes are used. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is an explanatory diagram conceptually showing the entire device for preferably implementing the first embodiment of the present invention.

[0015] Figure 2 This is an explanatory diagram conceptually showing the entire device of the second embodiment that is preferably used to implement the present invention.

[0016] Figure 3 This is an explanatory diagram showing an example of an apparatus for performing a heat treatment on a resin sheet in an embodiment of the present invention. DETAILED DESCRIPTION

[0017] Hereinafter, preferred embodiments of the present invention will be described.

[0018] [First embodiment]

[0019] First, a first embodiment of the present invention will be described.

[0020] In the present embodiment, first, a resin flake is prepared by pulverizing a recovered polyester resin molded product into flakes.

[0021] When preparing the resin sheet, it is preferably washed by any washing method such as alkali washing, warm water washing, etc., in order to remove dirt such as residues of the contents remaining on the surface, mixed foreign matter, etc. The "recovered polyester resin molded products" may include waste materials (pre-consumer materials) generated in the process of manufacturing polyester resin molded products, in addition to used PET bottles and other polyester resin molded products (post-consumer materials) collected separately as resource waste.

[0022] When used polyester resin molded products such as PET bottles are collected and reused as recycling materials based on so-called mechanical recycling to produce recycled products, the reduction in intrinsic viscosity caused by the degradation of the resin due to the thermal history etc. during the production of the recycled products becomes a cause of malfunctions in the production process of the recycled products. Furthermore, if a large amount of acetaldehyde (AA) generated by thermal decomposition of the polyester resin, oligomers such as bis(hydroxyethyl) terephthalate (BHET), mono(hydroxyethyl) terephthalate (MHET), and cyclic trimer (CT) generated by depolymerization of the polyester resin, and low molecular weight impurity components such as limonene derived from the content remain in the recycled materials, not only the quality of the produced recycled products is affected, but also the production equipment is contaminated, which becomes a cause of reduced productivity.

[0023] In this embodiment, in order to avoid such undesirable conditions, the prepared resin sheet is subjected to a heat treatment in an atmosphere with a reduced pressure of preferably less than 1000 Pa and a temperature of preferably 160 to 240°C, so that a solid phase polymerization reaction of the polyester resin that forms the resin sheet is carried out while the resin sheet is kept in a sheet-like form without melting, and crystallization is promoted.

[0024] By carrying out a solid phase polymerization reaction, the terminal groups of the polyester resin whose molecular chains are cut due to degradation and whose polymerization degree is reduced are repolymerized, and thus, as the polymerization degree is restored, the intrinsic viscosity corresponding to the molecular weight can be restored. Furthermore, by heating the resin sheet under reduced pressure conditions, especially by exposing it to a temperature atmosphere of 160 to 240°C under reduced pressure conditions, the hydrolysis of the polyester resin can be suppressed, and the crystallization can be well promoted by the melting point depression effect. As a result, the free volume between the molecular chains of the polyester resin is reduced (the amorphous phase is reduced), and the low molecular weight impurity components (organic impurity components) and the water adsorbed on the resin sheet as described above contained in the free volume part of the resin sheet are selectively exuded to the surface layer of the resin sheet, so that they are volatilized or evaporated, or washed with warm water, steam, organic solvents, etc. as needed, so that they can be efficiently removed.

[0025] In this embodiment, the specific method of heat treating the resin sheet is not particularly limited. Figure 3 The processing apparatus 100 shown implements a heat treatment, and includes at least one preheating chamber 102 and a processing chamber 103 capable of adjusting the internal atmosphere to a temperature and pressure suitable for the heat treatment.

[0026] Here, it is explained Figure 3 The processing device 100 shown in FIG. 1 is preferably provided with a 7 to 18 m 3A closed container 101 is constructed in a manner to have an internal volume of . In addition, a processing chamber 103 is provided in the closed container 101, and two preheating chambers 102 are provided above the closed container 101. The two preheating chambers 102 are connected to the closed container 101 via an opening and closing mechanism such as a sliding gate (not shown) so as to be able to communicate with the processing chamber 103 while maintaining airtightness with the outside of the system.

[0027] In addition, Figure 3 In the figure, illustration of a heating device, a decompression device, and incidental equipment such as pipes for adjusting the internal atmosphere of the processing chamber 103 is omitted.

[0028] When the resin sheet is subjected to heat treatment using such a treatment apparatus 100, it is preferred that before the heat treatment, the resin sheet is placed in the preheating chamber 102 and the preheating chamber 102 is sealed to raise the temperature of the resin sheet to a predetermined temperature, and the pressure in the preheating chamber 102 is reduced to a predetermined pressure. At this time, for example, it is preferred that a jet hole or the like provided at an opening on the inner wall surface of the preheating chamber 102 is provided to allow the heated gas (e.g., N 2 Inert gas such as gas is ejected into the preheating chamber 102, and the ejection direction and ejection amount are appropriately adjusted to generate airflow in the preheating chamber 102, thereby stirring the resin sheet while raising its temperature, and decompressing and sucking the preheating chamber 102, thereby dispersing at least a part of impurity components contained in the resin sheet and removing them outside the system.

[0029] Thus, when the temperature of the resin sheet is raised, it is preferable to appropriately adjust the final temperature and pressure in the preheating chamber 102 in consideration of the internal atmosphere of the processing chamber 103. Furthermore, it is preferable to open the opening and closing device, and to drop the resin sheet in the preheating chamber 102 by its own weight while maintaining airtightness with the outside of the system, so as to supply the resin sheet into the processing chamber 103 without damaging the internal atmosphere of the processing chamber 103 adjusted to a temperature and pressure suitable for the heat treatment.

[0030] exist Figure 3In the processing device 100 shown, the resin sheets are sequentially introduced into two preheating chambers 102, and the preheating treatment of heating the resin sheets is performed alternately, and the resin sheets are sequentially dropped from the preheating chamber 102 where the introduced resin sheets have been heated to a predetermined temperature to the processing chamber 103, but the present invention is not limited thereto. According to the processing capacity of the processing device 100, that is, the total amount of resin sheets that can be subjected to heat treatment per unit time, the number of preheating chambers 102 can be one or more than three. In short, it is preferred to repeatedly perform the operation of dropping the resin sheets from the preheating chamber 102 to the processing chamber 103, evenly spread the resin sheets, and stack them sequentially while forming layers for each set of dropped sheets. Moreover, it is preferred that the resin sheets be subjected to heat treatment by being exposed to the internal atmosphere of the processing chamber 103 while being deposited in the processing chamber 103.

[0031] In addition, the treatment time for heat treatment of the resin flakes is usually more than 30 minutes. In order to suppress the hue degradation of the resin and perform solid phase polymerization reaction, it is preferably adjusted appropriately within the range of 1 to 8 hours. Preferably, after the resin flakes accumulated in the treatment chamber 103 have passed the treatment time, the amount equal to the amount dropped from the preheating chamber 102 is taken out from the treatment chamber 103 in order from the lower layer side formed and accumulated as described above to manage its treatment time. At this time, the time required for the preheating treatment in the preheating chamber 102 also depends on the water content, shape, etc. of the resin flakes, and the intervals of the operation of repeatedly dropping the resin flakes may cause deviations, so it is preferred to manage the treatment time for each set of resin flakes dropped.

[0032] In this way, in order to properly manage the processing time when the resin sheet is heated, Figure 3 In the processing device 100 shown, an opening and closing mechanism 104 is provided on the bottom side in the sealed container 101. The opening and closing mechanism 104 is configured to form the bottom surface of the processing chamber 103 and to be a partition with a take-out portion 105 provided at the bottom in the sealed container 101. Thus, when the opening and closing mechanism 104 is opened, the resin flakes are scattered on the take-out portion 105, and by appropriately adjusting the timing of opening and closing the opening and closing mechanism 104, the resin flakes in an amount equal to the amount dropped from the preheating chamber 102 can be taken out, and although there is some mixing, the resin flakes are taken out for each set dropped from the preheating chamber 102.

[0033] In addition, as described above, by performing the heat treatment under reduced pressure, impurities can be removed efficiently, but it is not preferable that the volatilized or evaporated impurities remain in the processing chamber 103. Figure 3The processing device 100 shown in FIG. 1 is provided with a circulation flow path 106 that can circulate the gas phase components in the processing chamber 103 and includes a catalyst tank 107 for decomposing low molecular weight impurity components from the polyester resin in the path. The circulation flow path 106 is configured to be connected to the processing chamber 103. Preferably, the processing device 100 is configured such that, for example, N 2 Inert gas such as gas is used as a carrier gas, etc., and gaseous components in the processing chamber 103 are guided to the circulation flow path 106 and circulated without damaging the internal atmosphere of the processing chamber 103, thereby reducing impurity components and the like retained in the processing chamber 103.

[0034] In addition, when cleaning the impurity components that selectively seep into the surface layer of the resin sheet, although not specifically shown in the figure, the resin sheet taken out from the processing chamber 103 can be liquid cleaned using a rotary or convection liquid cleaning machine, or a pressurized water vapor convection cleaning machine can be used for steam cleaning. In the case of liquid cleaning, it is necessary to dry the cleaned resin sheet, but in this drying process, the resin sheet can be heated again in the same atmosphere as the internal atmosphere of the processing chamber 103, or it can be dried using a hot air circulation drying device. Furthermore, the drying of the resin sheet can also use two jacketed rollers with spiral grooves on the surface, and the shear heat generated by the rotation of the rollers is used to make the surface layer of the resin sheet semi-fused and pressed, and the organic impurities and water of the resin sheet are further removed by a rotating forward drying device (open twin-screw extruder). In this case, the resin sheet that has been dried using an open roller twin-screw extruder is simply separated and dispersed into sheets by the pressing roller of the roller rear cooling section.

[0035] In this embodiment, as described above, the resin sheet is heat-treated under reduced pressure to remove low molecular weight impurity components (decontamination), and then the heat-treated resin sheet is mixed with resin pellets composed of at least one of a raw material of a polyester resin, a biomass material, a chemically recycled material, and a mechanically recycled material in a prescribed ratio to prepare a raw material resin.

[0036] It should be noted that in Figure 1 In the illustrated example, the resin flakes stored in the first tank 1 are supplied to the processing device 100 , and the resin pellets stored in the second tank 2 and the resin flakes subjected to the heat treatment are mixed in the mixer 3 .

[0037] Here, as polyester resins, for example, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyethylene furandicarboxylate, or copolymers thereof, etc., can be cited. Among such polyester resins, polyester resins obtained by polymerizing chemically synthesized diol components and dicarboxylic acid components are referred to as raw materials. Polyester resins whose biomass degree is increased by using ethylene glycol or its derivatives derived from plant-derived bioethanol as a diol component, or using terephthalic acid or its derivatives derived from plant-derived bio-paraxylene as a raw material, or furandicarboxylic acid or its derivatives derived from plant-derived fructose as a raw material, etc. as a dicarboxylic acid component, etc., are referred to as biomass materials. In recent years, recycling technologies for recycling as resin materials for molding include material recycling and chemical recycling. Among the recycled materials obtained through material recycling, materials that can be used to wash and reuse the recycled polyester resin molded products are called post-consumer recycled materials, and materials whose intrinsic viscosity is adjusted and low-molecular-weight impurity components are removed are called mechanical recycled materials. In chemical recycling, polyester resins contained in recycled polyester resin molded products are depolymerized, decomposed to at least oligomer components, and repolymerized are called chemical recycled materials.

[0038] When the resin flakes subjected to the heat treatment are mixed with the resin pellets composed of at least one of the original material of the polyester resin, the biomass material, the chemically recycled material and the mechanically recycled material to prepare the raw material resin, the ratio of the two can be appropriately adjusted to produce a preform with desired characteristics. For example, the residual amount of acetaldehyde is 1 to 15 ppm, preferably 1 to 10 ppm, and more preferably 1 to 5 ppm, the residual amount of bis(hydroxyethyl) terephthalate is 1 to 35 ppm, preferably 1 to 30 ppm, and more preferably 1 to 20 ppm, the residual amount of mono(hydroxyethyl) terephthalate is 1 to 35 ppm, preferably 1 to 30 ppm, and more preferably 1 to 20 ppm, and the residual amount of cyclic trimer is 6000 ppm or less, preferably 4000 ppm or less, and more preferably 3000 ppm or less, and when the mass of the preform is 14 to 50 g, it can be adjusted to produce a preform with an L* value of 70 to 90 and a b* value of 2 to 18 in the L*a*b* color system. Therefore, the resin pellets are preferably mixed in a ratio of 11 to 400 parts by weight with respect to 100 parts by weight of the resin sheet.

[0039] Here, the residual amounts of acetaldehyde, bishydroxyethyl terephthalate (BHET), monohydroxyethyl terephthalate (MHET), and cyclic trimer (CT), and the intrinsic viscosity can be determined, for example, as follows.

[0040] <Residual acetaldehyde>

[0041] Take the slice cut from the preform as a sample. Weigh 1.0 g of this sample in a glass bottle, add 5.0 mL of pure water, and seal it. Heat this suspension in an oven adjusted to 120 °C for 60 minutes, and then cool it in ice water. Collect 1.0 mL of the supernatant of the suspension, add 0.2 mL of a 0.1% 2,4-dinitrophenylhydrazine-phosphoric acid solution thereto, let it stand for 30 minutes, and determine it by high performance liquid chromatography. At the same time, the standard solution is also determined, and the acetaldehyde content is calculated based on the obtained standard curve.

[0042] <Residual amounts of BHET, MHET, and CT>

[0043] Take the slice cut from the preform as a sample. Weigh 0.2 g of this sample, add 1 mL of a mixed solvent of hexafluoroisopropanol and chloroform (weight ratio 1 / 1) and dissolve it completely. After adding 4 mL of chloroform to the solution, slowly add 5 mL of acetonitrile, and let it stand for 3 hours to precipitate the PET polymer. Take 1 mL from this suspension, filter it through a membrane filter with a pore size of 0.45 μm, and determine the filtrate by high performance liquid chromatography. At the same time, the standard solution is also determined, and the contents of MHET, BHET, and CT in the pellets are calculated based on the obtained standard curve.

[0044] <Intrinsic viscosity>

[0045] Take the slice cut from the preform as a sample. Vacuum-dry this sample at 150 °C for 1 hour and weigh 0.2 g. Add a mixed solvent of 1,1,2,2-tetrachloroethane and phenol (weight ratio 1:1) thereto to adjust the concentration to 1.00 g / dL, and stir it at 120 °C for 20 minutes to dissolve it completely. Cool the dissolved solution to room temperature, and use a relative viscometer adjusted to 30 °C to obtain the relative viscosity and determine the intrinsic viscosity.

[0046] In addition, the L* value and b* value in the L*a*b* colorimetric system are the values measured using a spectrocolorimeter at the main body part of the preform under the measurement conditions of a D65 light source and a 2° field of view.

[0047] In addition, when preparing the raw material resin, the resin flakes taken out from the processing chamber 103 as described above can be directly mixed with the resin pellets, but the resin flakes can also be stored in the buffer tank 300 and then mixed with the resin pellets to prepare the raw material resin. As described above, in the case of managing the processing time when the resin flakes are heated, the resin flakes are taken out from the processing chamber 103 intermittently according to the interval of the operation of repeatedly dropping the resin flakes from the preheating chamber 102 to the processing chamber 103, and the amount of the resin flakes taken out each time also depends on the processing amount in the preheating chamber 102. In such a case, especially when there is a deviation in the interval of the operation of repeatedly dropping the resin flakes, the amount of the resin flakes taken out per unit time is not constant. Therefore, if the resin flakes are stored in the buffer tank 300 in advance and taken out from the buffer tank 300 quantitatively at an arbitrary interval each time, it becomes easy to adjust the ratio of mixing with the resin pellets. Furthermore, in the plasticizing step described later, the input amount of the raw material resin can be easily adjusted according to the processing capacity of the extruder 200 so that the amount of the resin plasticized in the extruder 200 is always kept constant.

[0048] When the buffer tank 300 is provided, it is preferable to adjust the internal volume of the buffer tank 300 so as to be able to store more resin sheets. Thus, even if a malfunction occurs in a subsequent process after the process of preparing the raw material resin and a subsequent process is stopped, the heating process of the resin sheet can be continued without stopping, and the portion that is not sent to the subsequent process can be stored in the buffer tank 300.

[0049] In addition, in case of such a failure, a change in the situation such as a speed increase or decrease in the subsequent process may be assumed, and a relief tank 400 may be provided in the middle of the conveying path of the resin sheet taken out from the processing chamber 103 to the buffer tank 300. Furthermore, it is preferable that the resin sheet in the middle of the conveying can be conveyed to the buffer tank 300 by retreating to the relief tank 400.

[0050] Thus, for example, when the subsequent process is stopped, the resin sheet taken out from the processing chamber 103 can be evacuated to the safety tank 400, and the transfer to the buffer tank 300 can be restricted. When the processing speed of the subsequent process is accelerated, in addition to the resin sheet taken out from the processing chamber 103, the resin sheet evacuated to the safety tank 400 can also be transferred to the buffer tank 300. When the processing speed of the subsequent process is slowed down, part of the resin sheet taken out from the processing chamber 103 can be evacuated to the safety tank 400, and the amount of the resin sheet transferred to the buffer tank 300 can be appropriately adjusted. In this way, when the resin sheet is evacuated to the safety tank 400 as needed, the internal atmosphere of the safety tank 400 is preferably set to 100° C. or more to prevent the resin sheet from containing water.

[0051] Next, the prepared raw material resin is plasticized. At this time, the raw material resin is put into the extruder 200, and the heat from the heating cylinder and the shear heat of the screw are used to melt and knead while plasticizing, but it is preferably plasticized using a twin-screw extruder. The twin-screw extruder has a high kneading effect, can plasticize the resin sheet more uniformly, and can also shorten the time required for plasticization, so it is also preferred in terms of suppressing degradation, thermal decomposition, and depolymerization of the resin.

[0052] When a twin-screw extruder is used to plasticize the raw material resin, the twin-screw extruder is configured to have an exhaust port. For example, it is preferred that the exhaust port provided through the heating barrel is used to decompress and suction the gas phase components containing low molecular weight impurity components from the polyester resin retained in the twin-screw extruder and discharge them to the outside of the system. In this way, the impurity components remaining in the plasticized polyester resin can be further reduced. At this time, in particular, circulating oligomers and the like are generated in the equilibrium reaction during hot melting, so circulating oligomers are generated when polyethylene terephthalate is melted. Therefore, it is important to use the exhaust port of the twin-screw extruder to perform decompressive suction and removal. The optimal conditions (temperature, pressure) for gas-liquid separation of circulating oligomers are estimated. The melting point of circulating oligomers is 319°C, which is sublimable. When the resin melting temperature of polyethylene terephthalate at the exhaust port of the twin-screw extruder is assumed to be 300°C, the reduced vacuum pressure at which the circulating oligomer can sublimate (convert into gas) is approximately 0.1 KPa (100 Pa) or less, so it is necessary to adjust the pressure to a relatively high vacuum degree. Therefore, the possibility of molten resin being discharged (vented up) at the exhaust port also increases. In order to avoid discharge, in terms of the screw rotation direction of the twin-screw extruder used, it is preferred to use a twin-screw extruder of the reverse (different direction) type compared to a twin-screw extruder of the same (same direction) type.

[0053] In the present embodiment, after the above-mentioned steps, foreign matter is removed from the molten resin obtained by plasticizing the raw material resin, and the molten resin is supplied to the injection molding device 500 to injection-mold the preform. In order to remove foreign matter from the molten resin obtained by plasticizing the raw material resin, for example, a filter 600 for removing foreign matter may be provided on the ejection outlet side of the extruder 200. In addition, the specific structure of the injection molding device 500 is not particularly limited. For example, the preform can be injection-molded using the injection molding device 500 having at least one injection cylinder (pot) and a preform molding mold, and the at least one injection cylinder is configured to meter the supplied molten resin and then inject a certain amount of the molten resin.

[0054] In addition, when the molten resin obtained by plasticizing the raw material resin is supplied to the injection molding device 500, it is not preferable that the resin deteriorates (especially the color phase deteriorates) during the conveying process. Therefore, in order to shorten the time that the molten resin stays in the conveying path, it is preferable to set the conveying distance from the removal of foreign matter to the supply to the injection molding device 500, more specifically, the distance from the outlet of the gear pump 700 provided on the downstream side of the filter 600 to the inlet of the injection cylinder provided in the injection molding device 500, to 1 to 7 meters. At this time, the conveying amount of the molten resin is preferably 900 to 1500 kg / h.

[0055] According to the present embodiment as described above, a preform having desired characteristics can be manufactured more efficiently, although resin flakes obtained by pulverizing a recovered polyester-based resin molded product into flakes are used.

[0056] [Second Embodiment]

[0057] Next, a second embodiment of the present invention will be described.

[0058] In the present embodiment, similarly to the first embodiment, resin flakes are prepared by pulverizing a recovered polyester-based resin molded product into flakes.

[0059] In the first embodiment, the resin sheet prepared in this way is subjected to a heat treatment, but in the present embodiment, before the heat treatment, the prepared resin sheet is mixed with resin pellets consisting of at least one of a virgin material of a polyester resin, a biomass material, a chemically recycled material, a mechanically recycled material, and a post-consumer recycled material at a prescribed ratio to prepare a raw material resin.

[0060] In addition, Figure 2 In the example shown, the resin flakes stored in the first tank 1 and the resin pellets stored in the second tank 2 are mixed in the mixer 3 .

[0061] Hereinafter, regarding this embodiment, descriptions overlapping with the first embodiment will be omitted as appropriate, and the description will be mainly focused on points different from the first embodiment.

[0062] In this embodiment, as in the first embodiment where the resin flakes are heat-treated, the prepared raw material resin is heat-treated, and a solid phase polymerization reaction of the polyester resin in the raw material resin, especially the polyester resin forming the resin flakes, is carried out while the resin flakes and resin pellets contained in the raw material resin are maintained in such a form without melting, and crystallization is promoted.

[0063] In addition, when the raw material resin is subjected to heat treatment, a solid phase polymerization reaction also proceeds in the polyester resin forming the resin pellets contained in the raw material resin. As a result, the degree of polymerization of the polyester resin is increased, and the intrinsic viscosity of the raw material resin as a whole is easily adjusted, especially when the resin pellets contain post-consumer recycled materials, the intrinsic viscosity of the raw material resin as a whole is easily adjusted. Furthermore, by performing a heat treatment under reduced pressure conditions together with the resin flakes, the moisture adsorbed on the resin pellets can be efficiently removed, and the moisture content of the raw material resin as a whole can be reduced. As a result, the drying process can be omitted when the raw material resin is plasticized.

[0064] Here, before the heat treatment, when the resin sheet is mixed with resin pellets consisting of at least one of a virgin material of a polyester resin, a biomass material, a chemically recycled material, a mechanically recycled material, and a post-consumer recycled material to prepare a raw material resin, the ratio of the two can be appropriately adjusted in the same manner as in the first embodiment so that a preform with desired properties can be manufactured.

[0065] In this embodiment, the specific method of heat-treating the raw material resin is not particularly limited. For example, as in the first embodiment, the resin sheet is heat-treated, preferably using Figure 3 The processing apparatus 100 shown here performs a heat treatment.

[0066] In the description of the heating treatment of the raw material resin in the present embodiment, the “resin sheet” in the description of the heating treatment of the resin sheet in the first embodiment may be appropriately replaced with the “raw material resin”.

[0067] In this embodiment, the raw material resin is heat-treated under reduced pressure to remove low molecular weight impurities (decontamination) and then plasticized, similarly to the case where the resin sheet is heat-treated in the first embodiment. At this time, similarly to the case where the raw material resin is plasticized in the first embodiment, the raw material resin that has been heat-treated is fed into the extruder 200, and plasticized while being melt-kneaded using the heat from the heating barrel and the shear heat of the screw.

[0068] use Figure 3The processing device 100 shown implements a heat treatment, and the raw material resin taken out from the processing chamber 103 can be directly put into the extruder 200 for plasticization, or can be stored in the buffer tank 300 and then put into the extruder 200 for plasticization. Similar to the case where the processing time when the resin sheet is subjected to the heat treatment is managed in the first embodiment, the processing time when the raw material resin is subjected to the heat treatment can also be managed in the present embodiment. In this case, the raw material resin is taken out from the processing chamber 103 intermittently according to the interval of repeatedly performing the operation of dropping the raw material resin from the preheating chamber 102 to the processing chamber 103, and the amount of the raw material resin taken out each time also depends on the processing amount in the preheating chamber 102. In such a case, especially if there is a deviation in the interval of repeatedly dropping the raw material resin, the amount of the raw material resin taken out per unit time is not constant. Therefore, if the raw material resin is stored in the buffer tank 300 in advance and quantitatively taken out from the buffer tank 300 at arbitrary intervals, the input amount of the raw material resin can be easily adjusted according to the processing capacity of the extruder 200 so that the amount of plasticized resin in the extruder 200 can always be maintained constant.

[0069] When the buffer tank 300 is provided, it is preferable to appropriately adjust the internal volume of the buffer tank 300 so as to be able to store more raw material resin. Thus, even if a malfunction occurs in a subsequent process after the process of plasticizing the raw material resin and the subsequent process is stopped, the heating process of the raw material resin can be continued without stopping, and the portion that is not sent to the subsequent process can be stored in the buffer tank 300.

[0070] In addition, in anticipation of such a failure or a change in the situation such as the processing speed of the subsequent process becoming faster or slower, a safety tank 400 may be provided in advance in the middle of the conveying path for conveying the raw material resin taken out of the processing chamber 103 to the buffer tank 300. Furthermore, it is preferable that the raw material resin in the middle of the conveying can be conveyed to the buffer tank 300 while retreating to the safety tank 400.

[0071] Thus, for example, when the subsequent process is stopped, the raw material resin taken out from the processing chamber 103 can be withdrawn to the safety tank 400, and the transfer to the buffer tank 300 can be restricted. When the processing speed of the subsequent process is increased, in addition to the raw material resin taken out from the processing chamber 103, the raw material resin withdrawn to the safety tank 400 can also be transferred to the buffer tank 300. When the processing speed of the subsequent process is slowed down, part of the raw material resin taken out from the processing chamber 103 can be withdrawn to the safety tank 400, and the amount of raw material resin transferred to the buffer tank 300 can be appropriately adjusted. In this way, when the raw material resin is withdrawn to the safety tank 400 as needed, the internal atmosphere of the safety tank 400 is preferably set to 100° C. or more to prevent the raw material resin from containing water.

[0072] In this embodiment, after the above-mentioned steps, foreign matter is removed from the molten resin obtained by plasticizing the raw material resin, and the molten resin is supplied to the injection molding device 500 to injection-mold the preform. In order to remove foreign matter from the molten resin obtained by plasticizing the raw material resin, for example, a filter 600 for removing foreign matter may be provided on the discharge port side of the extruder 200, which is the same as the first embodiment. In addition, the specific structure of the injection molding device 500 is not particularly limited. For example, the preform can be injection-molded using the injection molding device 500 having at least one injection pot and a preform molding mold, and the at least one injection pot is configured to meter the supplied molten resin and then inject a certain amount of the molten resin.

[0073] According to the present embodiment as described above, a preform having desired characteristics can be manufactured more efficiently, although resin flakes obtained by pulverizing a recovered polyester-based resin molded product into flakes are used.

[0074] As mentioned above, although the present invention was described by showing the preferred embodiment, the present invention is not limited to the above-mentioned embodiment, and various modifications can be made within the scope of the present invention.

[0075] Description of reference numerals:

[0076] 100 Processing Device

[0077] 101 Processing Room

[0078] 102 Preheating Room

[0079] 107 Catalyst Tank

[0080] 200 Extruder (twin screw extruder)

[0081] 300 Buffer tank

[0082] 400 Safety Cans

[0083] 500 Injection molding device

[0084] 600 Filters

[0085] 700 gear pump.

Claims

1. A method for manufacturing a prefabricated part, characterized in that: The manufacturing method of the prefabricated part is as follows: The recovered polyester resin molded product is crushed into flakes to obtain resin flakes, and then heat-treated under reduced pressure; The resin flakes subjected to the heat treatment are mixed with resin pellets composed of at least one of a raw material of a polyester resin, a biomass material, a chemically recycled material, and a mechanically recycled material at a predetermined ratio to prepare a raw material resin; as well as Foreign matters are removed from molten resin obtained by plasticizing the raw material resin, and the molten resin is supplied to an injection molding device to injection-mold a preform.

2. The method for manufacturing a preform according to claim 1, wherein: The resin sheet is heat-treated in an atmosphere at a temperature of 160° C. to 240° C. with a reduced pressure of 1000 Pa or less.

3. A method for manufacturing a prefabricated part, characterized in that: The manufacturing method of the prefabricated part is as follows: The raw material resin is prepared by mixing resin flakes obtained by pulverizing the recycled polyester resin molded product into flakes and resin pellets consisting of at least one of a virgin material of the polyester resin, a biomass material, a chemically recycled material, a mechanically recycled material, and a post-consumer recycled material at a predetermined ratio; Plasticizing the raw material resin after heating it under reduced pressure; as well as Foreign matters are removed from molten resin obtained by plasticizing the raw material resin, and the molten resin is supplied to an injection molding device to injection-mold a preform.

4. The method for manufacturing a preform according to claim 3, wherein: The raw material resin is subjected to a heat treatment in an atmosphere at a temperature of 160° C. to 240° C. and at a reduced pressure of 1000 Pa or less.

5. The method for manufacturing a preform according to claim 1 or 2, wherein: The resin sheet is placed in a preheating chamber, the temperature of the resin sheet is increased to a specified temperature, and the pressure in the preheating chamber is reduced to a specified pressure. Thereafter, the resin sheet is repeatedly dropped from the preheating chamber into a treatment chamber whose internal atmosphere is adjusted to a specified temperature and a specified pressure while maintaining airtightness with the outside of the system, and the resin sheet is accumulated in the treatment chamber to be subjected to a heat treatment.

6. The method for manufacturing a preform according to claim 5, wherein: The resin flakes subjected to the heat treatment are sequentially taken out from the treatment chamber in an amount equal to the amount dropped from the preheating chamber from the lower layer side where the resin flakes subjected to the heat treatment are accumulated in the treatment chamber, and then mixed with the resin pellets to prepare the raw material resin.

7. The method for manufacturing a preform according to claim 5, wherein: The resin flakes subjected to the heat treatment are taken out from the treatment chamber in an amount equal to the amount dropped from the preheating chamber in order from the lower layer side where the resin flakes subjected to the heat treatment are accumulated in the treatment chamber, stored in a buffer tank, and then mixed with the resin pellets to prepare the raw material resin.

8. The method for manufacturing a preform according to claim 7, wherein: A safety tank is provided in the middle of a conveyance path for conveying the resin sheet taken out from the processing chamber to the buffer tank, so that the resin sheet in the middle of conveyance can be evacuated to the safety tank and conveyed to the buffer tank.

9. The method for manufacturing a preform according to any one of claims 5 to 8, wherein: The resin sheet is sequentially placed in a plurality of preheating chambers, and the resin sheet is sequentially dropped from the preheating chambers where the temperature of the placed resin sheet is raised to a predetermined temperature into the processing chamber.

10. The method for manufacturing a preform according to any one of claims 5 to 9, wherein: An airflow of heated gas is generated in the preheating chamber, the resin sheet is heated while being stirred by the airflow, and the preheating chamber is depressurized.

11. The method for manufacturing a preform according to claim 3 or 4, wherein: The raw material resin is put into a preheating chamber, the temperature of the raw material resin is raised to a specified temperature, and the pressure in the preheating chamber is reduced to a specified pressure. Thereafter, the raw material resin is repeatedly dropped from the preheating chamber into a treatment chamber whose internal atmosphere is adjusted to a specified temperature and a specified pressure while maintaining airtightness with the outside of the system, and the raw material resin is accumulated in the treatment chamber to be subjected to a heat treatment.

12. The method for manufacturing a preform according to claim 11, wherein: The raw material resin subjected to the heat treatment is sequentially taken out from the treatment chamber in an amount equal to the amount dropped from the preheating chamber from the lower layer side where the raw material resin subjected to the heat treatment is accumulated in the treatment chamber and plasticized.

13. The method for manufacturing a preform according to claim 11, wherein: The raw material resin subjected to the heat treatment is sequentially taken out from the treatment chamber in an amount equal to the amount dropped from the preheating chamber from the lower layer side where the raw material resin subjected to the heat treatment is accumulated in the treatment chamber, stored in a buffer tank, and then plasticized.

14. The method for manufacturing a preform according to claim 13, wherein: A safety tank is provided in the middle of a conveyance path for conveying the raw material resin taken out of the processing chamber to the buffer tank, so that the raw material resin in the middle of conveyance can be conveyed to the buffer tank while retreating to the safety tank.

15. The method for manufacturing a preform according to any one of claims 11 to 14, wherein: The raw material resin is sequentially introduced into a plurality of preheating chambers, and the raw material resin is sequentially dropped from the preheating chambers where the introduced raw material resin is heated to a predetermined temperature into the processing chamber.

16. The method for manufacturing a preform according to any one of claims 11 to 15, wherein: An airflow of heated gas is generated in the preheating chamber, the raw material resin is heated while being stirred by the airflow, and the preheating chamber is depressurized.

17. The method for manufacturing a preform according to any one of claims 5 to 16, wherein: A circulation flow path is connected to the treatment chamber, and the circulation flow path can circulate the gas phase components in the treatment chamber. The path of the circulation flow path includes a catalyst layer for decomposing low molecular weight components from the polyester resin. The gas phase components in the treatment chamber are circulated by guiding them to the circulation flow path, thereby reducing the low molecular weight components retained in the treatment chamber.

18. The method for manufacturing a preform according to any one of claims 1 to 17, wherein: The raw material resin is fed into a twin-screw extruder to be plasticized.

19. The method for manufacturing a preform according to claim 18, wherein: The twin-screw extruder includes a vent port, and a gas phase component including a low molecular weight component from the polyester resin retained in the twin-screw extruder is decompressed and sucked through the vent port to be discharged to the outside of the system.

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