Method of manufacturing complete body, and method of manufacturing semi-complete body

Abstract

To provide a method of manufacturing a complete body and a method of manufacturing a semi-complete body compatible with a demand for weight reduction and wall thinning of a bottle using a thermoplastic resin including polyester-based and polyolefin-based resin, and a demand for diverse shapes.SOLUTION: A method of manufacturing a complete body includes a step of further stretch blow molding a semi-complete body obtained by stretch blow molding a thermoplastic resin preform in a semi-complete blow mold to obtain a complete body. When a product of a longitudinal stretch ratio and a transverse stretch ratio during stretch blow molding is defined as an area magnification, an area magnification of the complete body to the semi-complete body is 30% to 60% of the area magnification of the complete body to the preform.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a finished product and a method for manufacturing a semi-finished product. [Background technology]

[0002] PET (polyethylene terephthalate) bottles, a typical example of polyester resin, are lightweight yet strong and durable. This improves convenience during transport and use, and they are widely used for contents such as soft drinks, seasonings, cooking oil, and cosmetics. PET bottles are also generally transparent, allowing the contents to be seen, improving product appearance and making it easy to identify the contents. A known method for molding PET bottles is the injection biaxial stretch blow molding method (also known as single blow molding), in which an injection-molded, bottomed preform is stretched axially within a mold using a stretch rod while compressed air is blown in to form the bottle.

[0003] Among PET bottles, double blow molding is a method for producing heat-resistant bottles, particularly highly heat-resistant bottles (see, for example, Patent Document 1). The double blow molding method involves two blow molding steps: biaxially stretch blow molding a preform to obtain a primary intermediate molded product that is 10% to 30% larger than the finished product; heating this primary intermediate molded product in a heating furnace to shrink it into a secondary intermediate molded product; and blow molding this secondary intermediate molded product into a finished bottle.

[0004] Representative examples of olefin-based resins include polypropylene and polyethylene. Bottles made from olefin-based resins are used for a variety of purposes, including as medicine containers due to their stability against chemicals such as medicines. Polypropylene, in particular, is used for infusion bottles due to its excellent heat resistance.

[0005] Olefin-based resin bottles are mainly manufactured by direct blow molding, but there are issues with the dimensional accuracy of the mouth and the strength of the pinch-off part of the bottom. In recent years, stretch blow molding using olefin-based resins has been considered from the perspective of weight reduction. Olefin-based resin preforms have a narrow heating temperature range, which makes it difficult to increase the molding process speed and poses stability issues, so each material manufacturer adjusts the MFR (melt flow rate) and density to improve the melt tension (for example, Patent Document 2).

[0006] Meanwhile, the Plastic Resource Recycling Promotion Act came into effect in April 2022, and based on the basic principle of 3R+RENEWABLE, it has become law to reduce the amount of packaging materials used in each process from design to manufacturing and recycling. This has led to calls for further weight reduction and thinner wall thickness for thermoplastic resin bottles while maintaining their strength and ease of use.

[0007] In recent years, the expansion of cross-border e-commerce (EC) has led to changes in transportation methods, such as an increase in post-in-bottle mail delivery. Furthermore, concerns about a shortage of glass bottles have led to changes in packaging methods. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Patent No. 4019308 [Patent Document 2] Patent No. 6289191 Summary of the Invention [Problem to be solved by the invention]

[0009] Therefore, the present invention provides a method for manufacturing a finished bottle and a semi-finished bottle that can meet the demands for lighter weight, thinner walls, and more diverse shapes for bottles made of thermoplastic resins including polyester-based and polyolefin-based resins. [Means for solving the problem]

[0010] The present invention has been made to solve at least some of the above-mentioned problems, and can be realized as the following aspects or application examples.

[0011] [1] One aspect of the manufacturing method of the finished product according to the present invention is to A step of stretch-blow molding a thermoplastic resin preform in a semi-finished blow mold to obtain a semi-finished product, and then stretch-blow molding the semi-finished product to obtain a finished product, A method for producing a finished product, characterized in that the area ratio is the product of the longitudinal stretch ratio and the transverse stretch ratio during stretch blow molding, and the area ratio of the finished product to the semi-finished product is 30% to 60% of the area ratio of the finished product to the preform.

[0012] According to one aspect of the method for manufacturing the finished product, by stretch-blow molding a semi-finished product smaller than the finished product, excellent moldability can be achieved even when the finished product is made lighter or thinner. Also, according to one aspect of the method for manufacturing the finished product, by stretch-blow molding a semi-finished product smaller than the finished product, excellent moldability can be achieved even when the finished product has a variety of shapes.

[0013] [2] In the manufacturing method of the completed product, The step is the second step, The method further includes a first step of stretch blow molding the preform made of the thermoplastic resin in the semi-finished blow mold to obtain the semi-finished product, the thermoplastic resin is a polyester-based resin or a polyolefin-based resin, The preform in the first step has an outer surface temperature To of 100°C to 140°C and an inner surface temperature Ti that satisfies the following formula (1): The temperature of the semi-finished blow mold in the first step can be adjusted to a temperature lower than the outer surface temperature To by −10° C. to −80° C. To = Ti ≤ To + 5°C (1)

[0014] According to one aspect of the method for manufacturing the finished product, the preform satisfies the formula (1), so that a finished product with excellent formability can be molded even if the preform is thick. Also, according to one aspect of the method for manufacturing the finished product, by adjusting the semi-finished blow mold temperature to the above temperature, the degree of molecular orientation when molding the finished product is increased, improving the strength of the finished product and allowing the molding of a finished product with excellent uniformity in wall thickness.

[0015] [3] In the manufacturing method of the completed product, the thermoplastic resin is polyethylene terephthalate, The outer surface temperature t of the semi-finished body immediately before the finished body is stretch-blow molded can satisfy the following formula (2). Tg≦t≦120℃ (2) where Tg is the glass transition temperature of polyethylene terephthalate

[0016] According to one aspect of the manufacturing method for the finished product, the semi-finished product satisfies the formula (2), which increases the degree of molecular orientation when molding the finished product, improving the strength of the finished product and allowing the molding of a finished product with excellent thickness uniformity.

[0017] [4] In the manufacturing method of the completed product, the thermoplastic resin is polyethylene, The outer surface temperature of the semi-finished product may be 100°C to 130°C immediately before the finished product is stretch-blow molded.

[0018] According to one embodiment of the manufacturing method for the finished product, by using a temperature between 100°C and 130°C, which is the crystallization temperature of polyethylene, the degree of molecular orientation when molding the finished product is increased, improving the strength of the finished product and allowing the molding of a finished product with excellent thickness uniformity.

[0019] [5] In the manufacturing method of the completed product, the thermoplastic resin is polypropylene, The outer surface temperature of the semi-finished product may be 120°C to 140°C immediately before the finished product is stretch-blow molded.

[0020] According to one embodiment of the manufacturing method of the finished product, by using a temperature between 100°C and 120°C, which is the crystallization temperature of polypropylene, the degree of molecular orientation when molding the finished product is increased, improving the strength of the finished product and allowing the molding of a finished product with excellent thickness uniformity.

[0021] [6] In the manufacturing method of the completed product, The semi-finished product is not similar in shape to the finished product, The completed product may be a flat bottle in which the longitudinal direction of the body at the height position where the body has the widest width is two to three times the width in the lateral direction perpendicular to the longitudinal direction.

[0022] According to one aspect of the manufacturing method of the finished product, it is possible to prevent accumulation of meat in the trunk portion in the short direction.

[0023] [7] In the manufacturing method of the completed product, The step is the second step, The method further includes a first step of stretch blow molding the preform made of the thermoplastic resin in the semi-finished blow mold to obtain the semi-finished product, The second step can be a continuous step carried out following the first step.

[0024] According to one aspect of the method for manufacturing the completed product, no space is required for storing the semi-finished product, and transportation using a vehicle or the like is not required.

[0025] [8] In the manufacturing method of the completed product, The step is the second step, The method further includes a first step of stretch blow molding the preform made of the thermoplastic resin in the semi-finished blow mold to obtain the semi-finished product, In the second step, the semi-finished product can be stored at room temperature or at a constant temperature, and then reheated and stretch-blow molded into the finished product.

[0026] According to one aspect of the manufacturing method for the completed product, the production line for semi-finished products can be separated from the production line for completed products, making it easy to adjust the production volume of completed products.

[0027] [9] In the manufacturing method of the completed product, The step is the second step, The method further includes a first step of stretch blow molding the preform made of the thermoplastic resin in the semi-finished blow mold to obtain the semi-finished product, In the first and second steps, the preform can be stretched in the longitudinal and transverse directions by a stretching step in which the stretching speed of the stretching rod is adjusted to one speed or multiple speeds in the range of 300 mm / sec to 1000 mm / sec, and a blowing step using compressed air.

[0028] According to one aspect of the method for producing the completed product, by controlling the drawing speed and the timing of the air blowing, it is possible to prevent the preform from bursting due to contact between the drawing rod and the preform.

[0029]

[10] In the manufacturing method of the completed product, The preform may have a multi-layer structure formed by a stack preform method, an overmolding method, or a direct blow molding method.

[0030] According to one aspect of the method for manufacturing the completed product, a completed product having a multi-layer structure can be manufactured.

[0031]

[11] One aspect of the method for producing a semi-finished product according to the present invention is to A method for manufacturing a semi-finished product used in the method for manufacturing the finished product, a first step of stretch-blow molding the preform made of the thermoplastic resin in the semi-finished blow mold to obtain the semi-finished product; the thermoplastic resin is a polyester-based resin or a polyolefin-based resin, The preform in the first step has an outer surface temperature To of 100°C to 140°C and an inner surface temperature Ti that satisfies the following formula (1): The temperature of the semi-finished blow mold in the first step is adjusted to a temperature that is lower than the outer surface temperature To by −10° C. to −80° C. To = Ti ≤ To + 5°C (1)

[0032] According to one aspect of the method for producing a semi-finished product, the stretch orientation of the semi-finished product can be enhanced by using a preform that satisfies the formula (1) and the semi-finished blow mold temperature. Then, by molding a finished product using such a semi-finished product, the strength of the finished product can be improved and the finished product can have excellent uniformity in wall thickness. [Effects of the Invention]

[0033] According to the manufacturing method of the finished product of the present invention, the degree of molecular orientation is increased when the semi-finished product is molded into a finished product, improving the strength of the finished product and enabling the molding of a finished product with excellent wall thickness uniformity. Furthermore, the moldability is excellent even when the finished product is made lighter and thinner. Furthermore, according to the manufacturing method of the finished product of the present invention, the moldability is excellent even when the shape of the finished product is diversified. Furthermore, according to the manufacturing method of the semi-finished product, the stretch orientation can be increased. [Brief explanation of the drawings]

[0034] [Figure 1] 1 is a flowchart of a method for manufacturing a completed product according to the present embodiment. [Figure 2] 1 is a schematic diagram for explaining the relationship between a preform, a semi-finished body, and a finished body according to the present embodiment. FIG. [Figure 3] 10 is a schematic diagram for explaining the relationship between a preform, a semi-finished product, and a finished product according to Modification 1. FIG. [Figure 4] 10 is a schematic diagram for explaining the relationship between a preform, a semi-finished product, and a finished product according to Modification 1. FIG. [Figure 5] 10 is a flowchart of a method for manufacturing a completed product according to Modification 2. [Figure 6] 1 is a stress-strain curve showing the results of the tensile test of Example 3 and Comparative Example 2. DETAILED DESCRIPTION OF THE INVENTION

[0035] Preferred embodiments of the present invention will be described in detail below with reference to the drawings. Note that the embodiments described below do not unduly limit the content of the present invention as defined in the claims. Furthermore, not all of the configurations described below are necessarily essential components of the present invention.

[0036] 1. Overview of the manufacturing method for the finished product An overview of the manufacturing method of the finished product according to this embodiment will be described with reference to Fig. 1. Fig. 1 is a flowchart of the manufacturing method of the finished product according to this embodiment. Details of each step will be described later.

[0037] 1, the method for manufacturing a completed product according to this embodiment includes a second step (S30). The method for manufacturing a completed product may also include a first step (S20) before the second step (S30). Furthermore, the method for manufacturing a completed product may also include a preform heating step (S10) before the first step (S20).

[0038] Each step will be described in detail below with reference to Figures 1 and 2. Figure 2 is a schematic diagram illustrating the relationship between the preform 10, semi-finished body 20, and finished body 30. The semi-finished body 20 has a smaller volume than the finished body 30. In Figure 2, the preform 10 is shown with a solid line, the semi-finished body 20 with a dashed line, and the finished body 30 with a dashed line. The preform 10 is composed of a mouth portion 12, a body portion 14, and a bottom portion 16.

[0039] 1-1. Preform heating process S10: Preform heating step is a step of heating a preform 10 made of a thermoplastic resin molded by, for example, injection molding. In this embodiment, a cold parison method (a so-called two-stage method) will be described, in which a preform that has been injection molded and then cooled to room temperature is reheated in the preform heating step (S10) and stretch-blow molded in the first step (S20).

[0040] As a method for heating the preform, a known method used in biaxial stretch blow molding can be used.

[0041] The preform 10 used in S10 can be obtained by injection molding, extrusion molding, or compression molding of a molten thermoplastic resin. The thermoplastic resin is not limited as long as it can be stretch-blow molded, and examples include PET (including crystalline, recycled PET, and modified PET), PEN, PEF, copolyester resin, PP, TPX, PE, plant-derived resin, biodegradable resin, recycled resins of the above resins, and blends of these resins. The preform can have a multilayer structure using the stack preform method, overmolding method, or direct blow molding method. The stack preform method is a method in which two preforms, one large and one small, are stacked and integrated to obtain the preform 10. The overmolding method is a method in which an inner layer preform is first injection-molded, then inserted into the injection core of an outer layer injection mold, and the outer layer resin is then injection-molded after the mold is closed. The direct blow molding method is a method in which a pipe-shaped resin is extruded using a multilayer extrusion device, sandwiched between blow molds, and air is blown in from a blow pin to form the preform 10.

[0042] 1-2. 1st process S20: The first step is a step of obtaining a semi-finished body 20 by stretch-blow molding a preform 10 made of a thermoplastic resin in a semi-finished blow mold (not shown), as shown in FIG.

[0043] In the first step, the preform 10 can be stretched in both the longitudinal and transverse directions through a stretching step and a blowing step. In the stretching step, a stretch rod 40 inserted into the preform 10 through the mouth 12 moves the bottom 16 in the direction of arrow 1 to stretch the body 14 in the longitudinal direction. In the first step and the second step described below, the stretching speed of the stretch rod 40 can be adjusted to a single speed or multiple speeds within a range of 300 mm / sec to 1000 mm / sec. In the blowing step, compressed air introduced through the mouth 12 can be used to inflate the body 14 of the preform 10 in the transverse (circumferential) direction until it comes into close contact with the semi-finished blow mold. The semi-finished blow mold has a cavity that forms the outer shape of the semi-finished product 20, as shown by the dashed line. By adjusting the stretching speed within the above range and controlling the timing of the compressed air injection, it is possible to prevent the body 14 from bursting due to contact with the stretch rod 40 during the stretching step.

[0044] When the thermoplastic resin is a polyester-based resin or a polyolefin-based resin, the preform 10 in the first step has an outer surface temperature To of 100°C to 140°C and an inner surface temperature Ti that satisfies the following formula (1), and the temperature of the semi-finished blow mold in the first step can be adjusted to a temperature that is -10°C to -80°C lower than the outer surface temperature To. To = Ti ≤ To + 5°C (1)

[0045] The draw ratio of the inner surface of the preform 10 is greater than that of the outer surface. Therefore, to ensure the heat quantity during shaping, it is preferable that the outer surface temperature To be 100°C to 140°C, and that the outer surface temperature To and inner surface temperature Ti of the body portion 14 of the preform 10 satisfy formula (1). By satisfying formula (1) at an outer surface temperature To of 100°C to 140°C, the semi-finished body 20 retains sufficient heat quantity even if the body portion 14 of the preform 10 is made thick, for example, 4 mm or more, resulting in excellent shaping properties of the finished product. On the other hand, with a polyolefin resin preform 10, if the inner surface temperature Ti is too high, drawdown may prevent an appropriate thickness from being obtained or the preform may burst, so it is preferable that formula (1) be satisfied.

[0046] In addition, by adjusting the semi-finished blow mold temperature to a temperature that is -10°C to -80°C lower than the outer surface temperature To, the degree of molecular orientation when molding the finished product 30 is increased, the strength of the finished product 30 is improved, and a finished product 30 with excellent uniformity in wall thickness can be molded.

[0047] It is preferable that the shape of the semi-finished body 20 is not similar to the shape of the finished body 30. Furthermore, it is preferable that the semi-finished body 20 has a shape with few irregularities to suppress internal strain, and for example, the cross section is preferably circular. It is preferable that the bottom of the semi-finished body 20 has a hemispherical shape, for example.

[0048] 1-3.Second process S30: The second step is a step in which a semi-finished product 20 obtained by stretch-blow molding a thermoplastic resin preform 10 in a semi-finished blow mold is further stretch-blow molded to obtain a finished product 30. In the second step, similar to the first step, the preform 10 can be stretched in both the longitudinal and transverse directions through the stretching and blowing steps. In the stretching step, a stretch rod 40 inserted into the semi-finished product 20 from the mouth 12 thereof moves the bottom in the direction of arrow 2 to stretch the body in the longitudinal direction. For example, the second step can be a continuous step following the first step. By using a continuous process, space for storing the semi-finished product 20 is not required, thereby saving space on the production line. Furthermore, by using a continuous process, there is no need to transport the semi-finished product 20 by vehicle or the like, thereby reducing transportation costs.

[0049] The finished product 30 obtained in the second step is a hollow body, for example a container having a mouth 12, a body and a bottom.

[0050] As shown in FIG. 2, the finished product 30 has a larger volume than the semifinished product 20. The areal ratio of the finished product 30 to the semifinished product 20 is 30% to 60% of the areal ratio of the finished product 30 to the preform 10. The areal ratio of the finished product 30 to the semifinished product 20 is preferably 35% to 55%, and more preferably 40% to 50%, of the areal ratio of the finished product 30 to the preform 10. The areal ratio is the product of the longitudinal stretch ratio and the transverse stretch ratio during stretch blow molding. The longitudinal stretch ratio is the maximum ratio at which the preform 10 or semifinished product 20 is stretched in the axial direction, and can be calculated as the height ratio of the body parts of the preform 10 and the finished product 30, or the height ratio of the body parts of the semifinished product 20 and the finished product 30. The transverse stretch ratio is the maximum ratio at which the preform 10 or semi-finished product 20 is stretched in the circumferential direction, and can be calculated as the ratio of the body diameters of the preform 10 and the finished product 30, or the ratio of the body diameters of the semi-finished product 20 and the finished product 30. The transverse stretch ratio of a flat container is calculated by calculating the area ratios in the longitudinal and lateral directions of the body diameter. The longitudinal stretch ratio and transverse stretch ratio can be calculated using the dimensions of the outer shape of the thin-walled semi-finished product 20 and the finished product 30, and can be calculated using the dimensions of the center of the wall thickness of the thick-walled preform 10. By performing stretch blow molding using a semi-finished product 20 (area ratio of 30% to 60%) that is smaller than the finished product 30, excellent moldability can be achieved even if the finished product 30 is made lighter and thinner. Furthermore, by performing stretch blow molding using a semi-finished product 20 (area ratio of 30% to 60%) that is smaller than the finished product 30, excellent moldability can be achieved even if the shape of the finished product 30 is diverse (for example, Variation 1 described below).

[0051] When the thermoplastic resin is polyethylene terephthalate, the outer surface temperature t of the semi-finished product 20 immediately before the finished product 30 is stretch-blow molded can satisfy the following formula (2). Tg≦t≦120℃ (2) where Tg is the glass transition temperature of polyethylene terephthalate

[0052] By ensuring that the outer surface temperature t of the semi-finished body 20 satisfies equation (2), the degree of molecular orientation when molding the finished body 30 increases, improving the strength of the finished body 30 and enabling the molding of a finished body 30 with excellent thickness uniformity.

[0053] When the thermoplastic resin is polyethylene, the outer surface temperature of the semi-finished product 20 immediately before the finished product 30 is stretch-blow molded can be 100°C to 130°C. The crystallization temperature of polyethylene when cooled is 100°C to 130°C.

[0054] When the thermoplastic resin is polypropylene, the outer surface temperature of the semi-finished product 20 immediately before the stretch blow molding of the finished product 30 can be 120°C to 140°C. The crystallization temperature of polypropylene when cooled is 120°C to 140°C.

[0055] The cooling crystallization temperature is the temperature range in which polyethylene and polypropylene are heated to melt and then recrystallize. This recrystallization process causes the molecular chains in the semi-finished product 20 to form a more regular crystalline structure, improving strength and rigidity. Stretching the semi-finished product 20 in this temperature range increases the crystallized region and enhances the crystal orientation, further improving the strength of the finished product 30.

[0056] The temperature of the semi-finished body 20 immediately before the second step may be adjusted by the temperature of the semi-finished blow mold in the first step, or a heating step of the semi-finished body 20 may be further provided between the first and second steps. For the heating step of the semi-finished body 20, a known method for heating the preform 10 can be used.

[0057] 2. Manufacturing method of the finished product according to the first modification A manufacturing method of the finished product 30a according to Modification 1 will be described in detail using Figures 3 and 4. Figures 3 and 4 are schematic diagrams for explaining the relationship between the preform 10a, semi-finished product 20a, and finished product 30a according to Modification 1. In Figures 3 and 4, the preform 10a is indicated by a solid line, the semi-finished product 20a by a dashed line, and the finished product 30a by a dashed-dotted line. The finished product 30a in Figure 3 is shown as viewed from the front, and the finished product 30a in Figure 4 is shown as viewed from the side.

[0058] The manufacturing method of the finished product 30a according to Modification 1 differs from the embodiment described in 1 above in that the finished product 30a is a flat container. The manufacturing method of the finished product 30a according to Modification 1 includes the second step (S30) as in the embodiment described in 1 above, and may perform, for example, a preform heating step (S10), a first step (S20), and a second step (S30) as shown in Fig. 1. In the following explanation, explanations of parts that overlap with the explanation of the embodiment described in 1 above will be omitted.

[0059] S10: The preform heating step can heat the body portion 14a of the preform 10a uniformly in the circumferential direction. When molding a flat container, there is a heating technology (e.g., JP 05-269828 A) that creates a temperature difference between the short side direction, where the stretching ratio is low, and the long side direction, where the stretching ratio is high, but this requires complex positioning of the preform that is transported while rotating. However, according to the manufacturing method of the finished product according to Variation 1, the body portion 14a can be heated uniformly in the circumferential direction, so complex positioning is not necessary.

[0060] S20: The semi-finished product 20a obtained by stretch blow molding in the first step is not similar in shape to the finished product 30a. Unlike the finished product 30a, the semi-finished product 20a can have a cross section of its body that is, for example, circular. For example, the diameter of the body of the semi-finished product 20a is smaller than the width of the finished product 30a in the short direction, and is sized so that it does not come into contact with the cavity of the finished product blow mold closed in the second step. This prevents buildup of material due to contact between the semi-finished product 20a and the cavity.

[0061] S30: The finished bottle 30a obtained by stretch blow molding in the second step is, for example, a flattened bottle in which the longitudinal direction of the body of the finished bottle 30a at the height where the body is at its widest is two to three times the width in the lateral direction perpendicular to the longitudinal direction. In a typical molding method, a flattened bottle with a flattening ratio of two to three times is produced. The lateral portion of the preform closest to the blow mold comes into contact with the preform during the initial stretch blow molding process, which tends to cause wall buildup and makes it difficult to adjust the longitudinal wall thickness distribution. In contrast, the finished bottle 30a according to Modification 1 can achieve uniform wall thickness distribution in both the lateral and longitudinal directions using the manufacturing method according to the first embodiment, thereby suppressing wall buildup in the lateral direction. Furthermore, by using the first embodiment for the semifinished bottle 20a immediately before the second step, the degree of molecular orientation during molding of the finished bottle 30a is enhanced, improving the strength of the finished bottle 30a. Furthermore, a flattened bottle with excellent wall thickness uniformity and two to three times the lateral width perpendicular to the longitudinal direction can be molded.

[0062] 3. Manufacturing method of the finished product according to the second modification 2 and 5, a method for manufacturing the finished product 30 according to the second modification will be described in detail. FIG. 5 is a flowchart of the method for manufacturing the finished product 30 according to the second modification.

[0063] As shown in FIG. 5, the method for manufacturing a finished product 30 according to the second modification differs from the embodiment of FIG. 1 in that it further includes a storage step (S22) and a semi-finished product heating step (S24).

[0064] The manufacturing method of the finished product 30 according to the second modification may include a manufacturing method of the semi-finished product 20 and a manufacturing method of the finished product 30 using the semi-finished product 20. The manufacturing method of the semi-finished product 20 may be the first step of manufacturing the semi-finished product 20, 20a used in the manufacturing method of the finished product 30, 30a described in the first embodiment or the first modification of the second embodiment.

[0065] S22: The storage step is a step of storing the semi-finished body 20 obtained by stretch blow molding the preform 10 in the semi-finished blow mold in the first step at room temperature or a constant temperature. By including the storage step in this manufacturing method, the production line for the semi-finished body 20 can be separated from the production line for the finished body 30, making it easier to adjust the production volume of the finished body 30. Furthermore, if the factory that manufactures the semi-finished body 20 and the factory that manufactures the finished body 30 are different factories, the method may include, for example, a step of transporting the semi-finished body 20 before and after the storage step.

[0066] S24: Semi-finished product heating step is a step of reheating the semi-finished product 20 after the storage step. The reheated semi-finished product 20 can be reheated to the temperature of the semi-finished product 20 just before the second step described in the first embodiment above.

[0067] S30: The second step is a step of stretch-blow molding the finished product 30 after the storage step and the semi-finished product heating step. The manufacturing method of the finished product 30 according to the second modification example provides excellent moldability even when the finished product 30 is made lighter or thinner, and excellent moldability even when the shape of the finished product 30 is diversified. [Example]

[0068] In Example 1, the finished product 30a shown in Figures 3 and 4 was molded according to Modification 1 of Example 2 above using various materials shown in Table 1 below. The areal ratio of the finished product 30a to the preform 10a in Example 1 was 43% (43% in both the longitudinal and lateral directions) of the areal ratio of the finished product 30a to the semi-finished product 20a. In Table 1, "long side thickness / short side thickness" indicates the longitudinal thickness of the body of the finished product 30 at the height position where the body has the maximum width, and the wall thickness in the lateral direction perpendicular to the longitudinal direction.

[0069] [Table 1]

[0070] As shown in Table 1, the difference between the long side thickness and the short side thickness was small for all materials. In addition, the thickness was excellent overall for all materials, and the moldability of the finished product 30 was also excellent. [Example]

[0071] Using the manufacturing method for the finished product 30 according to the embodiment 1 above, a finished product 30 (Example 2) having a bottle capacity of 600 ml and a diameter of 20 mm was molded. The surface ratio of the finished product 30 to the preform 10 in Example 2 was 40% of the surface ratio of the finished product 30 to the semi-finished product 20. The thermoplastic resin used was HB233R (MFR 0.3 g / 10 min JIS K6922-2, density 0.946 g / cm) manufactured by Japan Polyethylene Corporation. 3 High-density polyethylene (HDPE) conforming to JIS K7112 was used. A bottle was molded as Comparative Example 1 using the same resin and the same finished blow mold using a general single blow molding method. The wall thickness of both bottles was measured. The finished bottle 30 of Example 2 and the bottle of Comparative Example 1 had similar wall thickness distribution in the height direction. The wall thickness deviation (%) in the circumferential direction of the bottle was also measured. The measurement position was set at 0 mm at the base of the bottle, and the wall thickness was measured at four points in the circumferential direction at four heights in the axial direction of the bottle. The wall thickness deviation was expressed as a percentage by dividing the difference between the maximum and minimum wall thickness values ​​at each measurement position by the average value. The wall thickness deviations of Comparative Example 1 and Example 2 are shown in Table 2.

[0072] [Table 2]

[0073] As shown in Table 2, the wall thickness deviation rate in the circumferential direction of the finished bottle 30 of Example 2 was about half of the wall thickness deviation rate of the bottle of Comparative Example 1. [Example]

[0074] Using the manufacturing method for the finished product 30 according to the embodiment 1 above, a finished product 30 (Example 3) with a bottle capacity of 600 ml and a mouth diameter of φ20 mm was molded. The surface ratio of the finished product 30 to the preform 10 in Example 3 was 40% of the surface ratio of the finished product 30 to the semi-finished product 20. High density polyethylene (HDPE) was used as the thermoplastic resin. As Comparative Example 2, a bottle of the same shape was molded by direct blow molding. The wall thickness of both bottles was approximately 0.4 to 0.5 mm, and although the HDPE material manufacturers were different, the material density was 0.953 g / cm. 3 The weight of the bottle in Example 3 was 29 g, and the weight of the bottle in Comparative Example 2 was 28 g.

[0075] The bottles of Example 3 and Comparative Example 2 were capped when filled with water and subjected to a drop strength test (eight bottles for each were dropped from a height of 2 m as a severe condition to demonstrate the difference). As a result, none of the eight bottles of Example 3 broke, but six of the eight bottles of Comparative Example 2 broke, resulting in a cracking rate of 75%.

[0076] Next, 25 mm × 100 mm dumbbell-shaped test pieces were cut out in both the vertical and horizontal directions from the bottles of Example 3 and Comparative Example 2, and tensile tests were performed. FIG. 6 is a stress-strain curve showing the results of the tensile tests of Example 3 and Comparative Example 2. The horizontal axis of FIG. 6 is displacement in mm, and the vertical axis is tensile stress in MPa. The yield stress of Example 3 was 44 MPa horizontally (dashed line) and 45 MPa vertically (solid line). The yield stress of Comparative Example 2 was 22 MPa horizontally (dashed line) and 23 MPa vertically (solid line). As shown in FIG. 6, the test piece of Example 3 exhibited a yield stress approximately twice that of the test piece of Comparative Example 2.

[0077] The present invention is not limited to the above-described embodiments, and various modifications are possible. The present invention includes configurations that are substantially the same as those described in the embodiments (configurations with the same functions, methods, and results, or configurations with the same purpose and effects). The present invention also includes configurations that replace non-essential parts of the configurations described in the embodiments. The present invention also includes configurations that achieve the same effects or purposes as the configurations described in the embodiments. The present invention also includes configurations that add publicly known technology to the configurations described in the embodiments. [Explanation of symbols]

[0078] 1, 2...arrows, 10, 10a...preform, 12, 12a...mouth portion, 14, 14a...body portion, 16, 16a...bottom portion, 20, 20a...semi-finished body, 30, 30a...finished body, 40...stretched rod

Claims

1. A step of stretch-blow molding a thermoplastic resin preform in a semi-finished blow mold to obtain a semi-finished product, and then stretch-blow molding the semi-finished product to obtain a finished product, A method for producing a finished product, characterized in that the area ratio is the product of the longitudinal stretch ratio and the transverse stretch ratio during stretch blow molding, and the area ratio of the finished product to the semi-finished product is 30% to 60% of the area ratio of the finished product to the preform.

2. 2. The method for manufacturing a finished product according to claim 1, The step is a second step, The method further includes a first step of stretch-blow molding the preform made of the thermoplastic resin in the semi-finished blow mold to obtain the semi-finished product, the thermoplastic resin is a polyester-based resin or a polyolefin-based resin, The preform in the first step has an outer surface temperature To of 100°C to 140°C and an inner surface temperature Ti satisfying the following formula (1): The method for manufacturing a finished product is characterized in that the temperature of the semi-finished blow mold in the first step is adjusted to a temperature that is -10°C to -80°C lower than the outer surface temperature To. To=Ti≦To+5℃...(1)

3. 3. The method for manufacturing a finished product according to claim 1 or 2, the thermoplastic resin is polyethylene terephthalate, A method for manufacturing a finished product, characterized in that the outer surface temperature t of the semi-finished product immediately before stretch blow molding the finished product satisfies the following formula (2): Tg≦t≦120° C. (2) Here, Tg is the glass transition temperature of polyethylene terephthalate.

4. 3. The method for manufacturing a finished product according to claim 1 or 2, the thermoplastic resin is polyethylene, The method for manufacturing a finished product, wherein the outer surface temperature of the semi-finished product is 100°C to 130°C immediately before the finished product is stretch-blow molded.

5. 3. The method for manufacturing a finished product according to claim 1 or 2, the thermoplastic resin is polypropylene, The method for manufacturing a finished product, wherein the outer surface temperature of the semi-finished product is 120°C to 140°C immediately before the finished product is stretch-blow molded.

6. 3. The method for manufacturing a finished product according to claim 1 or 2, The semi-finished product is not similar in shape to the finished product, The method for manufacturing a finished bottle is characterized in that the finished product is a flat bottle in which the longitudinal direction of the body at the height position where the body has the widest width is two to three times the width in the short direction perpendicular to the longitudinal direction.

7. 2. The method for manufacturing a finished product according to claim 1, The step is a second step, The method further includes a first step of stretch-blow molding the preform made of the thermoplastic resin in the semi-finished blow mold to obtain the semi-finished product, A method for manufacturing a finished product, wherein the second step is a continuous step carried out following the first step.

8. 2. The method for manufacturing a finished product according to claim 1, The step is a second step, The method further includes a first step of stretch-blow molding the preform made of the thermoplastic resin in the semi-finished blow mold to obtain the semi-finished product, The second step is a method for manufacturing a finished product, wherein the semi-finished product is stored at room temperature or a constant temperature, and then reheated and stretch-blow molded into the finished product.

9. 2. The method for manufacturing a finished product according to claim 1, The step is a second step, The method further includes a first step of stretch-blow molding the preform made of the thermoplastic resin in the semi-finished blow mold to obtain the semi-finished product, The first and second steps are a stretching step in which the stretching speed of a stretching rod is adjusted to one speed or multiple speeds in the range of 300 mm / sec to 1000 mm / sec, and a blowing step using compressed air to stretch the preform in the longitudinal and transverse directions.

10. 3. The method for manufacturing a finished product according to claim 1 or 2, A method for manufacturing a finished product, wherein the preform has a multi-layer structure formed by a stack preform method, an overmolding method, or a direct blow molding method.

11. A method for manufacturing a semi-finished product used in the method for manufacturing a finished product according to claim 1, a first step of stretch blow molding the preform made of the thermoplastic resin in the semi-finished blow mold to obtain the semi-finished product; the thermoplastic resin is a polyester-based resin or a polyolefin-based resin, The preform in the first step has an outer surface temperature To of 100°C to 140°C and an inner surface temperature Ti satisfying the following formula (1): A method for manufacturing a semi-finished product, characterized in that the temperature of the semi-finished blow mold in the first step is adjusted to a temperature that is -10°C to -80°C lower than the outer surface temperature To. To=Ti≦To+5℃...(1)

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