Method for manufacturing resin container, mold unit, and molder

Abstract

A method for manufacturing a resin container (10) has an injection molding step (S1), a temperature adjustment step (S2) in which a preform (11) is housed in a cavity mold (31), an air introduction member (32) is brought into airtight contact with the preform (11), and a blow molding step (S3) in which the preform (11) is blow-molded in the cavity mold (31). The preform (11) is cooled by causing the preform (11) to adhere to the inner wall of the cavity die (31) by conveying air from the air supply port of the air introduction member (32) to the inside of the preform (11) and discharging the air from the discharge port of the air introduction member (32) to the outside of the preform (11).

Description

[0001] This application is a divisional application of the application filed on October 19, 2018 (entering the Chinese national phase on July 17, 2019), with international application number PCT / JP2018 / 039007 (national application number: 201880008105.8) and entitled "Method for manufacturing a resin container, mold unit and molding machine". Technical Field

[0002] This invention relates to a method for manufacturing resin containers, a mold unit, and a molding machine. Background Technology

[0003] Hot preform blow molding utilizes the latent heat of the preform during injection molding to perform blow molding. Compared to cold preform blow molding, it can produce a wider variety of containers with superior external aesthetics. Hot preform blow molding machines exist in models with a temperature control unit between the injection molding and blow molding sections (4-station type) and models without a temperature control unit (2-station and 3-station types). With a temperature control unit, it is generally easy to adjust the temperature conditions of the preform before blow molding to suit the final container shaping. Furthermore, various methods and devices have been developed for hot preform blow molding machines to shorten the molding cycle. For example, Patent Documents 1 and 2 shorten the mold opening and closing action of the injection mold and the lifting action of the stretching device; Patent Document 3 changes the control method of the injection molding device; and Patent Document 4 uses a preform shape and injection mold that allows for early demolding, thus shortening the molding cycle.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2005-007797

[0007] Patent Document 2: International Publication No. 2016-148189

[0008] Patent Document 3: International Publication No. 2017-002150

[0009] Patent Document 4: International Publication No. 2017-098673 Summary of the Invention

[0010] The problem the invention aims to solve

[0011] In recent years, there has been an urgent need to further improve the productivity of hot preform blow molding machines, specifically, to further shorten the molding cycle time. In order to shorten the molding cycle time, it is also necessary to shorten the mechanical action time as in Patent Documents 1 to 3, but as in Patent Document 4, it is important to shorten the injection molding time (cooling time) of the preform, which is the speed control step.

[0012] However, in Patent Document 4, a special preform shape becomes a necessary condition. Since the preform needs to be designed with an optimal shape (wall thickness distribution) corresponding to the container shape, Patent Document 4 can only handle a portion of container molding and cannot be considered highly versatile. In particular, the approach in Patent Document 4 cannot handle the molding of cosmetic containers (containers with larger wall thicknesses) that are advantageous when using hot-form preforms. Therefore, in hot-form preform blow molding methods, a highly versatile cycle-shortening method based on various molding techniques has not yet been designed.

[0013] Therefore, the object of the present invention is to provide a method for manufacturing resin containers, a mold unit, and a molding machine that can shorten the molding cycle and effectively mold the final product.

[0014] Solution for solving the problem

[0015] The present invention, which solves the above problems, provides a method for manufacturing a resin container, comprising the following steps: an injection molding step, in which a resin preform with a bottom is injection molded; a temperature conditioning step, in which the temperature of the preform manufactured in the injection molding step is conditioned; and a blow molding step, in which the temperature-conditioned preform is blow molded to manufacture the resin container, wherein, in the temperature conditioning step, the preform is housed in a cavity mold, an air inlet member is airtightly abutting against the preform, air is supplied to the interior of the preform from the air inlet of the air inlet member, and the air is discharged to the exterior of the preform from the outlet of the air inlet member, thereby sealing the preform against the inner wall of the cavity mold and cooling the preform.

[0016] According to the above structure, the preform can be cooled from the inside during the temperature regulation process, which can shorten the molding cycle and form the final product well.

[0017] In the method for manufacturing a resin container according to the present invention, it is preferable that a temperature regulating medium flows in the cavity mold, and in the temperature regulating step, the preform is regulated from the outside by being tightly sealed with the cavity mold, and the preform is cooled from the inside by convection of air from the air inlet member.

[0018] Based on the above structure, the cooling intensity is made relatively different on the inner and outer sides of the preform, which can take into account both temperature regulation and cooling, and can more effectively shorten the molding cycle and form the final product well.

[0019] In addition, the present invention, which solves the above problems, provides a method for manufacturing a resin container, the method comprising the following steps: an injection molding step, in which a resin preform with a bottom is injection molded; a temperature conditioning step, in which the temperature of the preform manufactured in the injection molding step is conditioned; and a blow molding step, in which the temperature-conditioned preform is blow molded to manufacture a resin container, wherein, in the injection molding step, resin material is injected into a space in the shape of the preform formed by closing an injection molding mold, and the resin material is cooled in the space from the end of the injection molding process, and the time for cooling the resin material in the space from the end of the injection molding process is less than 1 / 2 of the injection molding time.

[0020] Based on the above structure, the cooling time in the injection molding process can be shortened, thus shortening the injection molding time of the preform at the injection molding part, thereby shortening the molding cycle time of the container itself.

[0021] In addition, the present invention, which solves the above problems, provides a mold unit for use in a preform temperature control process. The mold unit includes: a cavity mold for receiving a resin-made, bottomed preform; and an air inlet member that can airtightly abut against the preform and deliver air into the interior of the preform. The air inlet member includes: an air outlet for delivering air into the interior of the preform; and an outlet for discharging air out of the preform.

[0022] According to the above structure, the preform can be cooled from the inside during the temperature regulation process, which can shorten the molding cycle and form the final product well.

[0023] In the mold unit of the present invention, it is preferable that the cavity mold is not a parting mold, but a fixed structure.

[0024] In addition, the present invention, which can solve the above problems, provides a molding machine, wherein the molding machine includes an injection molding section, a temperature regulating section, and a blow molding section, and the temperature regulating section includes the above-mentioned mold unit.

[0025] In addition, the present invention, which solves the above problems, provides a method for manufacturing a resin container, the method comprising the following steps: an injection molding step, in which a resin preform with a bottom is injection molded; a temperature conditioning step, in which the temperature of the preform manufactured in the injection molding step is conditioned; and a blow molding step, in which the temperature-conditioned preform is blow molded to manufacture a resin container, wherein the preform has a wall thickness of 2.0 mm or more and 10.0 mm or less, the area of ​​the container including the longitudinal axis centerline is 1.2 times or more and 10.0 times or less of the area of ​​the preform including the longitudinal axis centerline, and the preform is cooled from the inside in the temperature conditioning step.

[0026] The effects of the invention

[0027] According to the present invention, a method for manufacturing resin containers, a mold unit, and a molding machine are provided that can shorten the molding cycle and effectively mold the final product. Attached Figure Description

[0028] Figure 1 This is a block diagram of a molding machine.

[0029] Figure 2 This is a cross-sectional schematic diagram showing the temperature adjustment of the preform at the temperature adjustment unit in the first embodiment (the airflow direction for cooling blow molding).

[0030] Figure 3 (a) ~ Figure 3 (b) is a cross-sectional schematic diagram showing the case of blow molding of a container using a preform at the blow molding section of the first embodiment.

[0031] Figure 4 This is a flowchart illustrating the manufacturing process of resin containers.

[0032] Figure 5 This is a graph showing the temperature change of the preform over time in the first embodiment and the reference example. Figure 5 (a) represents the first embodiment. Figure 5 (b) indicates a reference example.

[0033] Figure 6This is a cross-sectional schematic diagram showing a modified example of temperature regulation of the preform at the temperature regulation unit of the first embodiment (airflow direction of cooling blow molding air).

[0034] Figure 7 This is a comparison diagram of the preform used in the preferred embodiment and the preform of the reference example. Figure 7 (a) shows an illustration of two preforms (the left one is thin-walled, and the right one is of normal wall thickness) and a container blow-molded from them. Figure 7 (b) is a diagram illustrating the heat exchange of preforms with different wall thicknesses.

[0035] Figure 8 (a) ~ Figure 8 (d) is a cross-sectional schematic diagram showing the temperature adjustment of the preform at the temperature adjustment section of the second embodiment.

[0036] Figure 9 (a) ~ Figure 9 (d) is a cross-sectional schematic diagram showing the case of blow molding of a container using a preform at the blow molding section of the second embodiment.

[0037] Figure 10 This is a graph showing the temperature change of the preform over time in the second embodiment and the reference example. Figure 10 (a) indicates the second embodiment. Figure 10 (b) indicates a reference example. Detailed Implementation

[0038] (First Implementation)

[0039] Hereinafter, an example of an embodiment of the present invention (first embodiment) will be described with reference to the accompanying drawings. Furthermore, for ease of explanation, the dimensions of the components shown in these drawings may sometimes differ from the actual dimensions of the components. First, refer to... Figure 1 This describes the molding machine 20 used to manufacture resin containers 10. Figure 1 This is a block diagram of molding machine 20.

[0040] like Figure 1 As shown, the molding machine 20 includes an injection molding section 21 for manufacturing a preform 11 and a temperature regulating section 22 for adjusting the temperature of the manufactured preform 11. An injection molding device 25 for supplying resin material as raw material is connected to the injection molding section 21. Additionally, the molding machine 20 includes a blow molding section (an example of a blow molding device) 23 for blow molding the preform 11 to manufacture a container 10 and an extraction section 24 for removing the manufactured container 10.

[0041] The injection molding section 21, temperature control section 22, blow molding section 23, and take-out section 24 are located at positions after rotating a predetermined angle (90 degrees in this embodiment) around the conveying member 26. The conveying member 26 is composed of a rotating plate, etc. Figure 2 and Figure 3 As shown, the preform 11 or container 10, with the neck 12 supported by the neck mold 27 mounted on the rotating plate, is conveyed to various parts as the rotating plate rotates.

[0042] Figure 1 The injection molding section 21 shown includes an injection cavity mold, an injection core mold, a neck mold, etc. (not shown in the figure). A bottomed preform 11 is manufactured by injecting synthetic resin materials such as polyester resin (e.g., PET) (e.g., polyethylene terephthalate) into the space formed by closing these molds from the injection molding apparatus 25. The preform 11 corresponds to the container 10 and has an optimal wall thickness distribution (shape). The thickness (average thickness, wall thickness) of its body is set, for example, to 1.0 mm to 5.0 mm, preferably to 1.5 mm to 3.0 mm.

[0043] The temperature regulating unit 22 is configured to adjust the temperature of the preform 11 manufactured by the injection molding unit 21 to a temperature suitable for final blow molding.

[0044] Here, refer to Figure 2 The temperature control unit 22 will be described in detail. For example... Figure 2 As shown, the temperature regulating unit 22 includes a mold unit 30, which comprises: a cavity mold (temperature regulating cavity mold) 31 that accommodates the preform 11 and is used for temperature regulating air supply; and a first air inlet member 32 that can be airtightly contacted with the preform 11 to supply air into the interior of the preform 11. The cavity mold 31 is not a parting mold that can be opened and closed, but has a fixed (single unit) structure that defines a space with approximately the same shape as the preform 11 manufactured by the injection molding unit 21. The cavity mold 31 has a structure divided into two sections, having an upper mold section 31a and a lower mold section 31b. Furthermore, Figure 2 The cavity mold 31 shown has a support platform 37 at the lower part of the lower mold 31b. Temperature regulating media (cooling media) flow inside both the upper mold 31a and the lower mold 31b to maintain a low temperature. The temperature of the temperature regulating media flowing inside the upper mold 31a and the lower mold 31b is not particularly limited, and can be appropriately selected within a range of 5°C to 80°C, preferably 30°C to 60°C. Alternatively, the temperature can be adjusted according to the size and shape of the preform 11. Figure 2The lower section mold 31b of the cavity mold 31 shown serves as the middle section mold. A cavity corresponding to the preform is formed on the support platform 37 to constitute the lower section mold, so that the temperature regulating medium (cooling medium) still flows inside the lower section mold, thereby forming a structure divided into 3 sections.

[0045] The first air inlet member 32 consists of a hollow first rod member 33 with an internal airflow hole and a first fitting core (first blow molding core member) 34. The first rod member 33 is housed inside the first fitting core 34 in a manner that allows it to move up and down. A first inner flow port 35 is provided at the top of the first rod member 33 for ejecting or drawing air. The air temperature is appropriately set within a range of, for example, approximately 0°C to approximately 20°C (room temperature) depending on the wall thickness of the preform 11 and the container 10. The first fitting core 34 is configured such that when the first air inlet member 32 is inserted into the preform 11 (so that the first air inlet member 32 can be airtightly abutted), the first fitting core 34 is fitted (closely contacting) the neck 12. This prevents air inside the preform 11 from leaking from the neck 12 to the outside of the first fitting core 34. The gap between the first rod member 33 and the first fitting core 34 is an airflow path for supplying and discharging air relative to the preform 11. The gap formed by the top of the first fitting core 34 and the first rod member 33 constitutes a first outer flow port 36 capable of ejecting or drawing air. The first inner flow port 35 and the first outer flow port 36 can respectively serve as an air supply port and an air outlet.

[0046] Next, refer to Figure 3 Explanation of blow molding section 23. (e.g.) Figure 3 As shown, the blow molding section 23 includes a mold 40 and a second air inlet member 50. The mold (blow molding mold) 40 consists of a bottom mold 42 and a pair of parting molds (blow molding cavity molds) 43 that can be opened and closed. By closing the bottom mold 42 and the parting molds 43, the shape of the sides and bottom of the container 10 is defined. The bottom mold 42 is positioned at the lower center of the molding space of the parting mold 43.

[0047] The second air inlet member 50 of the blow molding section 23 consists of a second rod member 51 and a second fitting core (second blow molding core member) 52. The second rod member 51 is housed inside the second fitting core 52 in a manner that allows it to move up and down. The second rod member 51 is a tension rod, and has an abutment portion 55 at its top end that contacts the inner bottom surface of the preform 11 to prevent eccentricity during stretching. A second inner flow port 53 is formed on the outer peripheral surface of the second rod member 51, which allows air to be ejected or drawn in. The second fitting core 52 is configured such that when the second air inlet member 50 is inserted into the preform 11 (so that the second air inlet member 50 can abut in an airtight manner), the second fitting core 52 is fitted (closely contacting) the neck 12. This prevents air inside the preform 11 from leaking from the neck 12 to the outside of the second fitting core 52. The gap between the second rod member 51 and the second fitting core 52 is a flow path for supplying and discharging air relative to the preform 11. The gap formed by the top of the second fitting core 52 and the second rod member 51 constitutes a second outer flow port 54 capable of ejecting or drawing air.

[0048] The second air inlet member 50 is configured to also supply air into the interior of the preform 11 from the second outer flow port 54 and discharge air to the exterior of the preform 11 from the second inner flow port 53. The second inner flow port 53 and the second outer flow port 54 can respectively serve as an air supply port and an air discharge port.

[0049] Next, the manufacturing method of the container 10 of the first embodiment will be described. Figure 4 This is a flowchart illustrating the manufacturing method of a resin container. The container 10 of this embodiment is manufactured through an injection molding process S1 in which a preform 11 is injection molded, a temperature conditioning process S2 in which the temperature of the preform 11 is adjusted, and a blow molding process S3 in which the preform 11 after temperature adjustment is blow molded to manufacture the container 10. The container 10 is removed by releasing the neck 12 from the neck mold 27.

[0050] First, the injection molding process S1 will be explained. In the injection molding process S1, a preform 11 is manufactured by injecting resin material from the injection molding unit 25 into a space formed by closing the injection cavity mold, injection core mold, neck mold, etc. After the resin filling process is completed or after a cooling process of a certain time (minimum) set after the resin filling process, the preform 11 is moved from the injection molding section 21 to the temperature control section 22.

[0051] In injection molding process S1, during the period from start time t10 (the time when the injection of resin material begins) to the first time t11, resin material is injected into the space of the preform shape. Figure 5(a)). During the period from the first time t11 (the time when the resin material injection is completed) to the second time t12, the preform 11 is cooled from the first temperature T11 to the second temperature T12. Figure 5 (a)). The first temperature T11 is a temperature above the melting point of the resin material. For example, if the resin material is PET resin, the first temperature T11 is 270°C to 300°C. The time from start-up time t10 to the first time t11 is the filling time (injection time), the time from the first time t11 to the second time t12 is the cooling time, and the time from start-up time t10 to the second time t12 is the injection molding time IT11 (filling time (including holding pressure time) + cooling time). In addition, during the period from the second time t12 to the third time t13 (the start time of temperature conditioning process S2), the preform 11 is cooled from the second temperature T12 to the third temperature T13 ( Figure 5 (a)). The time from the second time t12 to the third time t13 is the transport time DT11 between each process for the preform 11 or container 10. Figure 5 The diagram shows the time taken to transport the preform 11 from the injection molding section 21 to the temperature control section 22. Furthermore, based on the structure of the molding machine 20, the transport time DT11 between processes is always the same. The total time of the injection molding time IT11 and the transport time DT11 is the molding cycle time CT11.

[0052] The time from the end of resin injection to the cooling of the resin material (from the first time t11 to the second time t12) is preferably less than half of the injection time (from the start time t10 to the first time t11). Furthermore, depending on the weight of the resin material, the cooling time during the injection molding process can be shorter compared to the injection time. The cooling time is more preferably less than one-third of the injection time, further preferably less than one-quarter, and particularly preferably less than one-fifth.

[0053] Next, refer to Figure 2 The temperature control process S2 is described below. First, the preform 11 is housed within the space of the cavity mold 31, which is the shape of the preform. Next, a first air inlet member 32 is inserted into the interior of the preform 11 housed in the cavity mold 31 (so that the first air inlet member 32 can be airtightly abutted). Then, pre-blow molding is performed, in which air is supplied into the interior of the preform 11 from the first outer outlet 36 of the first air inlet member 32 while the first inner outlet 35 is closed, so that the preform 11 is sealed against the inner wall of the cavity mold 31. Next, cooling blow molding (cold blow molding) is performed. Figure 2In this cooling blow molding process, the first inner flow port 35 is opened, air is introduced through the first inner flow port 35, and air is discharged to the outside of the preform 11 through the first outer flow port 36. Thus, in pre-blow molding and cooling blow molding, the air flow directions are preferably set in opposite directions. At this time, since air is continuously ejected from the first inner flow port 35, the preform 11 is cooled from the inside by the convection of the air flowing inside. Furthermore, since the preform 11 is continuously in contact with the cavity mold 31, temperature adjustment is possible, preventing it from falling below the suitable temperature for blow molding from the outside, and also reducing temperature deviations that occur during injection molding. In addition, since the cavity mold 31 has space for the shape of the preform, the shape of the preform 11 does not change significantly. After a certain cooling time, the cooled preform 11 is moved towards the blow molding section 23.

[0054] Furthermore, the airflow direction of the first air inlet member 32 can be appropriately changed. For example, as... Figure 6 As shown, in cooling blow molding, air can be supplied from the first outer flow port 36 and discharged from the first inner flow port 35. In this case, pre-blow molding preferably involves supplying air into the interior of the preform 11 from the first inner flow port 35 while the first outer flow port 36 is closed. When it is desired to increase the cooling intensity on the lower side (bottom side) of the preform 11, air is directed from the first inner flow port 35 towards the first outer flow port 36. When it is desired to increase the cooling intensity on the upper side (body side) of the preform 11, air is directed from the first outer flow port 36 towards the first inner flow port 35. Furthermore, when it is desired to increase the wall thickness of a specific portion of the container 10 by more strongly cooling a particular portion of the preform 11, the air supply direction for pre-blow molding and the air supply direction for cooling blow molding can be set to be the same.

[0055] Here, refer again Figure 5 This describes the temperature change of the preform relative to time. In the temperature conditioning process S2, during the period from the third time t13 to the fourth intermediate time t14', the preform 11 is cooled from the third temperature T13 to the fourth temperature T14, and then, during the period until the fourth time t14, the temperature of the preform 11 is maintained at the fourth temperature T14. Figure 5(a) The fourth temperature T14 is a suitable temperature for blow molding, for example, 90°C to 105°C in the case of PET resin. The time from the third time t13 to the fourth time t14 is the temperature conditioning time TT11. In addition, the fourth temperature T14 represents the suitable temperature for blow molding of the preform. During the period from the fourth intermediate time t14' to the fourth time t14, the temperature conditioning in the temperature conditioning process S2 is continuously performed until the molding (cooling) of the preform 11 in the injection molding process S1 is completed. In addition, if the time to reach the fourth temperature T14 is shorter, the cooling blow molding can be stopped at the fourth intermediate time t14'. Furthermore, if the fourth temperature T14 is low, the tensile orientation of the preform 11 becomes good, which can improve the strength (physical property) of the container 10, so the fourth temperature T14 is expected to be 90°C to 95°C.

[0056] Next, refer to Figure 3 The blow molding process S3 is described below. First, the bottom mold 42 is brought to a standstill, and the preform 11 is placed in the mold 40 with the parting mold 43 open. Next, the parting mold 43 is closed. Figure 3 (a) Insert the second air inlet member 50 (so that the second air inlet member 50 can be airtightly abutted). At this time, the preform 11 is pushed towards the second rod member 51. Figure 3 The preform 11 is stretched downwards. Then, through final blow molding, air is supplied from the second outer flow port 54 into the interior of the preform 11, causing the preform 11 to expand into the shape of the container 10, thus manufacturing the container 10. Figure 3 (b) In cases where sufficient cooling is not achieved solely through contact between the mold 40 and the preform 11, cold blow molding can be performed after final blow molding. In this cold blow molding, air is supplied to the interior of the preform 11 through the second inner flow port 53, and air is discharged to the exterior of the preform through the second outer flow port 54. After final blow molding, the parting mold 43 is opened, and the container 10 is released from the mold 40.

[0057] The container 10, which has been pulled out of the mold 40, is moved to the extraction section 24. Figure 1 The container 10 is removed by releasing the neck 12 from the neck mold 27. The container 10 is manufactured by the above method.

[0058] Furthermore, when molding a preform 11 in the form of a thermoformed preform using a crystalline thermoplastic resin (a resin capable of being in a transparent amorphous state or an opaque crystalline state), whitening sometimes occurs due to insufficient cooling, depending on the material. For example, when using PET (polyethylene terephthalate) as the material, if slow cooling (e.g., cooling for tens of seconds at room temperature) is performed in the temperature range that promotes crystallization (120°C to 200°C), crystallization occurs due to the formation of spherulites, thus exhibiting a tendency to whiten (opaque). Therefore, conventionally, the injection molding mold (injection cavity mold, injection core mold, neck mold) is rapidly cooled (e.g., rapidly cooled at 10°C for 5 seconds) to shorten the passage time in the aforementioned crystallization temperature range, thereby ensuring sufficient cooling of the injection molding mold during the injection molding process and suppressing the crystallization (whitening) of the PET preform 11. In other words, as Figure 5 As shown in (b), in conventional resin container manufacturing methods, during the injection molding process, from the first time t21 to the second time t22, the preform is cooled from the first temperature T21 to a second temperature T22 that is lower than or approximately the same as the fourth temperature T24 (a suitable temperature for blow molding, for example, 90°C to 105°C). Furthermore, during the temperature conditioning process, from the third time t23 to the fourth intermediate time t24', the preform is heated from the third temperature T23 to the fourth temperature T24, and then, during the period until the fourth time t24, the temperature of the preform 11 is maintained at the fourth temperature T24. Figure 5 (b) Therefore, the cooling time in the injection molding process becomes longer, resulting in a longer molding cycle time CT21 for the container. Furthermore, in the case of containers with larger wall thicknesses, the cooling of the preform requires even more time, further increasing the molding cycle time CT21 of the container. Figure 5 (b)). Furthermore, if a special PET resin (copolyester: copolymer) modified to prevent crystallization is used, the cooling time of the preform 11 in the injection molding section can be shortened to some extent, and preforms and containers with suppressed whitening can be manufactured. However, this special PET resin is very expensive compared to general-purpose (ordinary) PET resin, and is not preferred for large-scale production of general-purpose containers.

[0059] According to the method for manufacturing the resin container 10 of this embodiment, the cooling process of the preform 11 is essentially omitted in the injection molding process S1, and the cooling process of the preform 11 is moved to the temperature conditioning process S2. In the temperature conditioning process S2, the preform 11 can be sealed in the cavity mold 31, and the temperature of the outer surface of the preform 11 can be effectively conditioned. Furthermore, the air is not trapped inside the preform 11, but flows continuously to generate convection, so the inner surface of the preform 11 can be cooled simultaneously. Since the temperature conditioning process S2 can be used to condition and cool the preform 11, the preform 11 can be demolded even at a high temperature in the injection molding process S1, and the subsequent molding of the preform 11 can begin as quickly as possible. That is, the molding cycle time CT11 can be shortened and the final molded product can be well molded. In addition, even if a general PET resin is used instead of a special PET resin, a non-whitened container can be molded with a shorter molding cycle.

[0060] Furthermore, in Patent Document 4, the body shape of the preform is designed to be relatively thin in order to enable early demolding during the injection molding process. This is effective as a countermeasure to shorten the molding cycle in blow molding machines without temperature control processes. However, if the preform shape is made thinner, the physical properties and appearance of the container 10 may deteriorate. Here, we will describe the case of manufacturing containers of the same shape using preforms of the same weight but with different body wall thicknesses. Figure 7 (a) shows an image of two 40g preforms (the left one is thin-walled, the right one is of normal wall thickness) and the shape (double-dotted line) of a container blow-molded from each preform. The body of the thin-walled preform is thinner, and correspondingly, the thin-walled preform is longer in the longitudinal direction. Figure 7 (left side of (a)). As a result, the stretch ratio in the longitudinal direction of the thinner preform is less than that in the longitudinal direction of the preform with a typical wall thickness. Generally, the higher the stretch ratio (orientation stretch), the higher the strength (impact strength, stiffness, tensile strength, etc.) and barrier properties of the container. That is, the physical properties of the container formed from the thin-walled preform are worse than those of the container formed from the preform with a typical wall thickness. In addition, if the stretch ratio becomes smaller, it becomes more difficult to adjust the wall thickness of the container, and the degree of deviation and appearance of the container are also more likely to deteriorate. Thin-walled preform ( Figure 7 (a) on the left side is also inferior to preforms with typical wall thickness in terms of temperature homogenization. Figure 7 (to the right of (a)). Figure 7(b) is a diagram illustrating heat transfer in preforms with different wall thicknesses. Compared to preforms with typical wall thicknesses, thin-walled preforms have less heat in their inner core, resulting in poorer heat transfer between the inner core and the cooler surface layer (outer layer). Consequently, thin-walled preforms are more difficult to homogenize, leading to greater container deviations compared to preforms with typical wall thicknesses.

[0061] In contrast, in this embodiment, since the preform 11 can be efficiently cooled using the temperature regulating unit 22, unlike Patent Document 4, even when using a preform with an optimal wall thickness distribution designed according to the container shape, the molding cycle time CT11 can be shortened. Furthermore, the possibility of a decrease in the physical properties of the container and whitening is also smaller, resulting in higher versatility.

[0062] Furthermore, the average wall thickness of the body of the preform 11 used in this invention is preferably set to be 2.0 mm or more and 10.0 mm or less (preferably 2.0 mm or more and 5.0 mm or less). Additionally, it is desirable that the longitudinal stretch ratio of the container 10 relative to the preform 11 is set to be 1.1 times or more and 4.0 times or less (preferably 1.1 times or more and 1.2 times or less, or 1.9 times or more and 4.0 times or less), and the transverse stretch ratio is set to be 1.1 times or more and 4.0 times or less (preferably 1.1 times or more and 1.8 times or less, or 3.0 times or more and 4.0 times or less). Furthermore, the area ratio (longitudinal section area ratio) of the area of ​​the cross-section of the container 10 including the longitudinal axis centerline relative to the area of ​​the cross-section of the preform 11 including the longitudinal axis centerline is preferably set to be 1.2 times or more and 16.0 times or less (preferably 1.2 times or more and 10.0 times or less). It is particularly desirable to set the longitudinal stretch ratio to approximately 2.5 times, the transverse stretch ratio to approximately 4.0 times, and the area ratio to approximately 10.0 times. By setting the molding conditions of the preform 11 as described above, and by molding the preform 11 from a common (typical) PET resin and implementing the temperature control method described above, it is possible to appropriately manufacture a container 10 with high strength (physical properties) and suppressed whitening (emulsification).

[0063] (Example of the first implementation method)

[0064] The following describes an embodiment of the first embodiment. However, the scope of the present invention is not limited to this embodiment. The scope of the present invention can be determined within the scope set forth in the claims or its equivalents.

[0065] Manufacturing tests of PET containers in Examples 1, 2, and 3 were conducted using a molding machine 20 equipped with the structure described in the first embodiment. The wall thickness (average thickness of the body), cycle time, container weight, and container capacity for each example are shown in Table 1. The injection time of the resin material in the injection molding process, the time for cooling the preform in the mold after injection molding, and the freezing temperature (temperature of the cooling medium (chilled water)) inside the injection molding cavity of the injection molding section for each example are shown in Table 1. The blow molding time of the preform in the temperature control process and the temperatures of the upper, middle, and lower temperature control points (POTs) of the cavity mold for each example are shown in Table 1. Furthermore, in Example 1, a two-section cavity mold without a middle temperature control point (POT) was used; in Examples 2 and 3, a three-section cavity mold was used.

[0066] Table 1

[0067]

[0068] In the manufacturing tests of Examples 1, 2, and 3, no whitening of the preform occurred, and containers with good shapes were manufactured. Furthermore, compared to cases where cooling based on pre-blow molding and cooling blow molding was not performed in the temperature control process, but cooling was performed in the injection molding process to prevent whitening of the preform, a 24.3% reduction in cycle time was achieved in Example 1, a 13.0% reduction in cycle time was achieved in Example 2, and a 37.5% reduction in cycle time was achieved in Example 3. When the preform has a large wall thickness and a large weight, the cooling time in the injection molding process becomes longer, resulting in a particularly significant reduction in cycle time in Example 3.

[0069] (Second Implementation)

[0070] Next, refer to Figure 1 , Figure 4 as well as Figures 8-10 Another example illustrating an embodiment of the present invention (the second embodiment). The molding machine 120 of the second embodiment ( Figure 1 Except for the structure of the cavity mold 131 of the mold unit 130 of the temperature regulating unit 122 and the structure of the mold 140 and the second air inlet member 150 of the blow molding unit 123, which differ from the molding machine 20 of the first embodiment, the other parts are the same or similar in structure to the molding machine 20 of the first embodiment. Therefore, the same reference numerals are used to mark the same or similar structures and the description is omitted. Hereinafter, only the temperature regulating unit 122 and the blow molding unit 123, which are different from those of the first embodiment, will be described.

[0071] First, refer to Figure 8The temperature control unit 122 will be described in detail. Figure 8 (a) ~ Figure 8 (d) is a cross-sectional schematic diagram showing the temperature adjustment of the preform 11 in the temperature adjustment unit 122. Figure 8 (a) ~ Figure 8 Details of each stage of (d) will be described later. The temperature regulating unit 122 includes a mold unit 130, which comprises: a cavity mold 131 that accommodates the preform 11 for temperature regulating air supply; and a first air inlet member 32. The cavity mold 131 is a parting mold that defines a space larger than the preform 11 manufactured by the injection molding unit 21. A temperature regulating medium (cooling medium) flows inside the cavity mold 131 to maintain a low temperature. The temperature of the temperature regulating medium (cooling medium) is not particularly limited, and can be appropriately selected, for example, within the range of 5°C to 80°C, preferably between 5°C and 30°C, and more preferably within the range of 10°C ± 5°C. The structure of the first air inlet member 32 is the same as in the first embodiment.

[0072] Next, refer to Figure 9 The blow molding part 123 is described in detail. Figure 9 (a) ~ Figure 9 (d) is a cross-sectional schematic diagram showing the blow molding process of the container 10 manufactured from the preform 11 in the blow molding section 123. Figure 9 (a) ~ Figure 9 The details of each stage of (d) will be described later. The mold (blow molding unit) 140 of the blow molding section 123 includes a shoulder mold 141, a bottom mold 142, and a base mold (body mold) 143. The bottom mold 142 and the base mold 143 are connected to each other, defining the shape of the sides and bottom of the container 10. The bottom mold 142 and the base mold 143 are connected to the second fixing plate 145 at their lower ends. The base mold 143 is not a parting mold with a generally cylindrical molding space, but is configured as a single mold, and the base mold 143 can be Figure 9 It moves vertically within the mold. Furthermore, the inner wall of the molding space in the base mold 143 is conical, with the diameter of the upper space being larger than the diameter of the lower space. The shoulder mold 141 consists of a pair of parting molds, which respectively... Figure 9 Either the left or right end of the shoulder mold 141 is connected to the first fixed plate 144. The first fixed plate 144 is connected to a mold opening and closing mechanism (not shown), and the shoulder mold 141 can move along... Figure 9 The shoulder mold 141 moves left and right in the closed state, engaging with the neck mold 27 and contacting or approaching the shoulder of the preform 11, defining the shape of the shoulder of the container 10. Additionally, on both sides of the shoulder mold 141 ( Figure 9 The front and depth sides of the paper are provided with pressure-bearing members (not shown) and are connected to each of the first fixing plates 144.

[0073] The second air inlet member 150 of the blow molding section 23 is the same as that in the first embodiment, except for the second rod member 151. The second rod member 151 is the same as that in the first embodiment in that it has an air passage hole inside, but it does not have a contact part at its top end that contacts the inner bottom surface of the preform 11. Instead, it is provided with a second inner passage 153 that can spray or draw air out.

[0074] The molding machine 120 of this embodiment manufactures a container 10 with a suspended bottom and a relatively thick wall. The stretching ratio of the preform 11 to the container 10 is intentionally set to be low. The manufactured preform 11 has a relatively thick wall; the thickness of its body can be, for example, 3.0 mm to 12.0 mm, preferably 4.0 mm to 8.0 mm. In addition, the filling capacity of the container 10 can also be, for example, 30 mL to 100 mL.

[0075] Next, the manufacturing method of the container 10 according to the second embodiment will be described. Similar to the first embodiment, the container 10 of the second embodiment is manufactured through an injection molding process S101 in which a preform 11 is injection molded, a temperature conditioning process S102 in which the temperature of the preform 11 is adjusted, and a blow molding process S103 in which the temperature-adjusted preform 11 is blow molded to manufacture the container 10. Figure 4 The container 10 is removed by releasing the neck 12 from the neck mold 27.

[0076] Injection molding process S101 is performed according to the same operation as injection molding process S1 in the first embodiment. Here, refer to Figure 10 Explain the temperature change of the preform relative to time in injection molding process S101. Figure 10 This is a graph showing the temperature change of the preform over time in the second embodiment and the reference example. Figure 10 (a) indicates the second embodiment. Figure 10 (b) indicates a reference example. In the injection molding process S101, during the period from the first time t31 (the time when the resin material is injected) to the second time t32, the preform 11 is cooled from the first temperature T31 to the second temperature T32. Figure 10(a)). The first temperature T31 is a temperature above the melting point of the resin material, for example, 270°C to 300°C in PET resin. The time from start-up time t30 to the first time t31 is the filling time (injection time), the time from the first time t31 to the second time t32 is the cooling time, and the time from start-up time t30 to the second time t32 is the injection molding time IT31 (filling time (including holding pressure time) + cooling time). In addition, during the period from the second time t32 to the third time t33 (the start time of the temperature adjustment process S102), the preform 11 is cooled from the second temperature T32 to the third temperature T33 ( Figure 10 (a)). The time from the second time t32 to the third time t33 is the transport time DT31 between each process for the preform 11 or container 10. Figure 10 The diagram shows the time taken to transport the preform 11 from the injection molding section 21 to the temperature control section 121. Furthermore, based on the structure of the molding machine 120, the transport time DT31 between all processes is the same value. The total time of the injection molding time IT31 and the transport time DT31 is the molding cycle time CT31.

[0077] Next, refer to Figure 8 The temperature regulation process S102 is described below. First, the preform 11 is moved between the open cavity molds 131, then the cavity molds 131 are closed, and the preform 11 is accommodated in the cavity molds 131. Figure 8 (a) Next, the first air inlet member 32 is inserted into the interior of the preform 11 housed in the cavity mold 131 (so that the first air inlet member 32 can be airtightly abutted). Figure 8 (b) Then, pre-blow molding is performed, in which air is supplied to the interior of the preform 11 from the first inner outlet 35 of the first air inlet member 32 with the first outer outlet 36 closed, causing the preform 11 to expand and seal against the inner wall of the cavity mold 131. Next, cooling blow molding is performed, in which the first outer outlet 36 is opened, and air is discharged to the exterior of the preform 11 from the first outer outlet 36 of the first air inlet member 32. Figure 8 (c)). At this time, air continues to be ejected from the first inner flow port 35, so the preform 11 is also cooled from the inside by the air flowing inside. After a certain period of cooling, the cavity mold 131 is opened ( Figure 8 (d) causes the expanded preform 11 to move to the blow molding section 123.

[0078] Here, refer again Figure 10This describes the temperature change of the preform relative to time. In the temperature conditioning process S102, during the period from the third time t33 to the fourth intermediate time t34', the preform 11 is cooled from the third temperature T33 to the fourth temperature T34, and then, during the period until the fourth time t34, the temperature of the preform 11 is maintained at the fourth temperature T34. Figure 10 (a)). The fourth temperature T34 is a temperature suitable for blow molding, for example, 90°C to 105°C in the case of PET resin (similar to the first embodiment, it is desirable to be 90°C to 95°C). After the fourth time t34, cooling in the temperature conditioning step S102 continues until the cooling of the preform in the injection molding step S101 is completed.

[0079] Next, refer to Figure 9 Explanation of blow molding process S103. First, the bottom mold 142 and the base mold 143 are brought to a standstill, and the preform 11 is accommodated in the mold 140 with the shoulder mold 141 open. Figure 9 (a) Next, close the shoulder mold 141 so that the shoulder mold 141 fits into the neck mold 27, and insert the second air inlet member 150 (so that the second air inlet member 150 can be airtightly abutted). Figure 9 (b)). Then, the preform 11 is expanded into the shape of the container 10 by final blow molding, in which air is supplied to the interior of the preform 11 from the second outer flow port 54. Afterward, the container 10 is manufactured by cold blow molding, in which air is supplied to the interior of the preform 11 from the second inner flow port 153 and air is discharged to the exterior of the preform from the second outer flow port 54. Figure 9 (c) After the final blow molding and cold blow molding are completed, the bottom mold 142 and the base mold 143 are lowered slightly, and then the shoulder mold 141 is opened to pull the container 10 out of the mold 140. Alternatively, if sufficient cooling can be achieved simply by contacting the preform 11 with the mold 140, cold blow molding can be omitted.

[0080] The container 10, which has been pulled out of the mold 140, is moved to the extraction section 24, and the container 10 is removed by releasing the neck 12 from the neck mold 27. The container 10 is manufactured by the above method.

[0081] In addition, such as Figure 10As shown in (b), in conventional resin container manufacturing methods, during the injection molding process, the preform is cooled from the first temperature T41 to a second temperature T42, which is lower than or approximately the same as the fourth temperature T44, during the period from the first time t41 (the time when the resin material is injected) to the second time t42. Furthermore, during the temperature conditioning process, the preform is heated from the third temperature T43 to the fourth temperature T44 during the period from the third time t43 to the fourth time t44. Therefore, the cooling time in the injection molding process is prolonged, resulting in a longer container molding cycle time CT41. In addition, in the case of containers with large wall thicknesses, the cooling of the preform requires even more time, further increasing the container molding cycle time C41.

[0082] According to the manufacturing method of the resin container 10 of this embodiment, the preform 11 can be cooled not only in the injection molding process S101, but also in the temperature conditioning process S102. In particular, in the temperature conditioning process S102, by supplying air into the interior of the preform 11, the preform 11 can expand and seal against the cavity mold 131, effectively cooling the outer surface of the preform 11 and obtaining a preform 11 with an appropriate shape. Furthermore, since the air is not confined inside the preform 11, but flows continuously to generate convection, the inner surface of the preform 11 can also be cooled simultaneously, allowing for faster cooling of the preform 11 compared to conventional methods. Moreover, due to the cooling in the temperature conditioning process S102, the preform 11 can be demolded even at high temperatures in the injection molding process S101, allowing for faster commencement of the subsequent molding of the preform 11. That is, the preform 11 can be effectively cooled by the cooperation of the injection molding process S101 and the temperature control process S102, which can shorten the molding cycle time CT31 and form the final product well.

[0083] Furthermore, for preforms with a large wall thickness, even if the outer wall of the preform 11 is cooled from one side, the inner wall and the side opposite to the side being cooled are difficult to cool, requiring a long time to cool to a suitable temperature for blow molding. According to the resin container 10 manufacturing method of this embodiment, the outer surface of the preform 11 can be effectively cooled in the temperature conditioning step S102 to obtain a thin-walled preform 11 with a suitable shape (close to the shape of the container 10). Moreover, since the inner surface of the preform 11 can also be cooled simultaneously, the preform 11 with a large wall thickness can be cooled more effectively and quickly compared to the past. Furthermore, through the cooling in the temperature conditioning step S102, the preform 11 can be demolded at a high temperature and transferred to the next step in the injection molding step S101, allowing for rapid start of the subsequent molding of the preform 11, shortening the molding cycle, and producing a well-formed final product.

[0084] Furthermore, according to the mold unit 130 of this embodiment, by providing a first air inlet member 32 including a first inner flow port 35 and a first outer flow port 36, air is not confined inside the preform 11 but is allowed to flow continuously, thereby generating convection. As a result, the preform 11 can be effectively cooled from its inner surface. Additionally, by using air to expand the preform 11 and seal it tightly against the cavity mold 131, the outer surface of the preform 11 can be effectively cooled, resulting in a preform 11 with an appropriate shape.

[0085] Furthermore, according to the mold unit 130 of this embodiment, the outer surface of the preform 11 can be effectively cooled to obtain a preform 11 with an appropriate shape, and the inner surface of the preform 11 can also be cooled at the same time. Therefore, compared with the past, the preform 11 with a large wall thickness can be cooled effectively and quickly.

[0086] Furthermore, the present invention is not limited to the above-described embodiments and can be appropriately modified and improved. Moreover, as long as the present invention can be realized, the material, shape, size, value, form, quantity, and arrangement of the constituent elements in the above embodiments are arbitrary and not limited.

[0087] In the blow molding section of the above embodiment, a second rod member 51 for cold blow molding was described, but any blow molding device capable of properly expanding the preform 11 into the container 10 can be used. For example, it may not be necessary to exchange air supply and exhaust through the second inner flow port 53 and the second outer flow port 54.

[0088] Furthermore, the mold opening and closing direction of the injection molding section's mold is preferably vertical (longitudinal). This is because if the mold opening and closing direction is horizontal (lateral), the preform demolded from the injection molding section will be in a higher and more softened state than usual. Under these conditions, the bottom side of the preform extending horizontally may bend vertically downwards due to the center of gravity during transport to the temperature control section, making it impossible to perform cooling blow molding in its normal shape. On the other hand, when the mold opening and closing direction of the injection molding section's mold is vertical (longitudinal), such bending deformation does not occur, allowing for cooling blow molding of the preform in its normal shape.

[0089] Furthermore, this application is based on Japanese Patent Application No. 2017-202716, filed on October 19, 2017, the entirety of which is incorporated herein by reference. In addition, all references cited herein are incorporated herein by reference in their entirety.

[0090] Explanation of reference numerals in the attached figures

[0091] 10. Container; 11. Preform; 12. Neck; 20, 120. Molding machine; 21. Injection molding section; 22, 122. Temperature control section; 23, 123. Blow molding section; 24. Take-out section; 25. Injection molding device; 26. Conveying component; 27. Neck mold; 30, 130. Mold unit; 31, 131. Cavity mold; 32. First air inlet component; 33. First rod component; 34. First fitting core ( 35. First inner flow port; 36. First outer flow port; 40, 140. Mold; 141. Shoulder mold; 42, 142. Bottom mold; 43. Parting mold; 143. Base mold; 50, 150. Second air inlet component; 51, 151. Second rod component; 52. Second fitting core (second blow molding core component); 53, 153. Second inner flow port; 54. Second outer flow port.

Claims

1. A method for manufacturing a resin container, the method comprising the following steps: In the injection molding process, a bottomed preform made of crystalline thermoplastic resin is injection molded. A temperature conditioning process, in which the temperature of the preform manufactured in the injection molding process is adjusted; and In the blow molding process, the preformed blank, after being subjected to temperature regulation, is blow molded to manufacture a resin container. The temperature control process includes pre-blow molding and cooling blow molding, and can be changed to either a first setting or a second setting. The preform is cooled by either the first setting or the second setting. The first setting is as follows: the preform is housed in the cavity mold, so that the air inlet component can be airtightly abutted against the preform. Through the pre-blow molding, the preform is sealed to the inner wall of the cavity mold, so that one of the air inlet and the air outlet of the air inlet component is blocked and the other is open. Air is then supplied to the interior of the preform from the one outlet and discharged to the exterior of the preform from the other outlet, thereby setting the air supply direction of the pre-blow molding and the cooling blow molding to be opposite. The second setting is: the air delivery direction of the pre-blow molding and the cooling blow molding is set to the same direction; A temperature-regulating medium flows within the cavity mold. During the temperature-regulating process, the preform is conditioned from the outside by being tightly sealed to the cavity mold, and cooled from the inside by convection of air from the air inlet member. In the injection molding process, the time from the end of resin material injection to the cooling of the resin material is less than 1 / 2 of the total injection time. The preform has a wall thickness of 2.0 mm or more and 10.0 mm or less, and the area of ​​the container including the longitudinal axis centerline is more than 1.2 times and less than 10.0 times the area of ​​the preform including the longitudinal axis centerline.

2. A mold unit for use in a preform temperature control process, the mold unit comprising: a cavity mold for receiving a bottomed preform made of crystalline thermoplastic resin; and an air inlet member that can be airtightly contacted with the preform and supply air into the interior of the preform. The air inlet component includes: an air outlet for supplying air into the interior of the preform; and an outlet for discharging the air outward from the preform. The air inlet component is composed of a hollow rod component (33) with an air flow hole inside and a blow molding core component (34). The top of the rod component is provided with an air supply port or an exhaust port (35) that can spray or draw air. The gap between the rod component and the blow molding core component forms the exhaust port or the air supply port (36) that can spray or draw air. In the pre-blow molding and cooling blow molding processes of the temperature regulation step, the settings can be changed to either a first setting or a second setting. The preform is cooled by either the first setting or the second setting. The first setting is as follows: one of the air inlet or outlet (35) located at the top of the rod member and the outlet or air inlet (36) formed by the gap between the rod member and the blow molding core member is closed, and air is supplied to the interior of the preform from the other of the two. In the cooling blow molding of the temperature regulation process, the closed one is opened, air is supplied to the interior of the preform from the one of the two, and the air is discharged to the exterior of the preform from the other of the two, thereby setting the air supply direction of the pre-blow molding and the cooling blow molding to be opposite. The second setting is: the air delivery direction of the pre-blow molding and the cooling blow molding is set to be the same.

3. The mold unit according to claim 2, wherein, The cavity mold is not a parting mold, but a fixed structure.

4. A blow molding machine, wherein, This blow molding machine has an injection molding section, a temperature control section, and a blow molding section. The temperature regulating unit includes the mold unit as described in claim 2 or 3.

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