Manufacturing method of finished product and manufacturing method of semi-finished product

Abstract

The present invention provides a method for manufacturing a finished product and a method for manufacturing a semi-finished product that can meet the demands for lighter weight and thinner walls as well as the demands for more diverse shapes for bottles made of thermoplastic resins including polyester-based and polyolefin-based resins. [Solution] A method for manufacturing a finished product includes a step of stretch-blow molding a thermoplastic resin preform in a semi-finished blow mold, and further stretch-blow molding the resulting semi-finished product to obtain a finished product. The product of the longitudinal stretch ratio and the transverse stretch ratio during stretch-blow molding is defined as the area ratio, 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.

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 representative example of polyester-based resins, are lightweight yet strong and durable. This improves convenience during transportation and use, and they are widely used for contents such as soft drinks, seasonings, edible oils, and cosmetics. PET bottles are also generally transparent, allowing the contents to be seen, making it easy to check the appearance of the product and recognize 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 in a mold with a stretch rod while compressed air is blown in to form the bottle.

[0003] Among PET bottles, there is a double blow molding method as a method for manufacturing heat-resistant bottles, particularly highly heat-resistant bottles (for example, Patent Document 1). The double blow molding method is a molding method including a two-stage blow molding process in which a preform is biaxially stretch-blow molded to obtain a primary intermediate molded product that is 10% to 30% larger than the finished product, this primary intermediate molded product is heated in a heating furnace to shrink into a secondary intermediate molded product, and this secondary intermediate molded product is blow molded into a finished bottle.

[0004] Representative examples of olefin resins include polypropylene and polyethylene. Bottles made of olefin resins are used for various purposes, for example, as medicine containers due to their stability against chemical substances such as medicines. In particular, polypropylene is used for infusion bottles due to its excellent heat resistance.

[0005] Olefin resin bottles are mainly manufactured by direct blow molding, but there are problems 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 resins has been considered from the viewpoint of weight reduction. Olefin resin preforms have a narrow heating temperature range, and the molding process speed cannot be increased, so there are problems with stability. Therefore, each material manufacturer adjusts the MFR (melt flow rate) and density to improve the melt tension (for example, Patent Document 2).

[0006] On the other hand, the Plastic Resource Recycling Promotion Act will come into effect in April 2022, and with 3R+RENEWABLE as the basic principle, it will be legalized to reduce the amount of packaging materials used at each stage from design to manufacturing and recycling. This calls for the promotion of further weight reduction and thinning of 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 the form of transportation, such as an increase in post-in-bottle mail delivery. Furthermore, there are concerns about a shortage of glass bottles, and packaging forms are changing. [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 product and a semi-finished product that can meet the demands for lighter weight and thinner walls as well as the demands for 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 in 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 Thermoplastic resin preform The torso of Semi-finished blow mold Until it sticks to The semi-finished product obtained by stretch blow molding is further Until the finished product is attached to the blow mold Stretch blow molding to obtain a finished product, A method for producing a finished product, characterized in that the product of the longitudinal stretch ratio and the transverse stretch ratio during stretch blow molding is defined as an areal ratio, and the areal ratio of the finished product to the semi-finished product is 30% to 60% of the areal ratio of the finished product to the preform.

[0012] According to one aspect of the method for producing the finished product, by stretch-blow molding a semi-finished product smaller than the finished product, the finished product has excellent moldability even if it is made lighter and thinner. Also, according to one aspect of the method for producing the finished product, by stretch-blow molding a semi-finished product smaller than the finished product, the finished product has excellent moldability even if it has a more diverse shape.

[0013] [2] In the manufacturing method of the completed product, The step is a second step, The preform made of the thermoplastic resin The body part of The semi-finished blow mold Until it sticks to The method further comprises a first step of stretch blow molding 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 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 manufacturing method of the finished product, the preform satisfies the formula (1), so that a finished product having excellent shapeability can be molded even if the preform is made thick. Also, according to one aspect of the manufacturing method of the finished product, by adjusting the semi-finished blow mold temperature to the above temperature, the degree of molecular orientation during molding of the finished product is increased, improving the strength of the finished product and allowing the molding of a finished product having 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) Here, Tg is the glass transition temperature of polyethylene terephthalate.

[0016] According to one embodiment of the manufacturing method for the finished product, the semi-finished product satisfies the formula (2), whereby the degree of molecular orientation during molding of the finished product is increased, improving the strength of the finished product and enabling 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, the temperature is set to 100°C to 130°C, which is the crystallization temperature of polyethylene, thereby increasing the degree of molecular orientation when molding the finished product, improving the strength of the finished product, and enabling 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 for the finished product, the temperature is set to 100°C to 120°C, which is the crystallization temperature of polypropylene, thereby increasing the degree of molecular orientation when molding the finished product, improving the strength of the finished product, and enabling 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 flattened bottle in which the longitudinal direction of the body at the height position where the body has the maximum width is two to three times as wide as the lateral direction perpendicular to the longitudinal direction.

[0022] According to one aspect of the manufacturing method for the finished product, accumulation of meat in the body portion in the short direction can be suppressed.

[0023] [7] In the manufacturing method of the completed product, The step is a second step, The preform made of the thermoplastic resin The body part of The semi-finished blow mold Until it sticks to The method further comprises a first step of stretch blow molding 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 products, and no transportation using a vehicle or the like is required.

[0025] [8] In the manufacturing method of the completed product, The step is a second step, The preform made of the thermoplastic resin The body part of The semi-finished blow mold Until it sticks to The method further comprises a first step of stretch blow molding to obtain the semi-finished product, The second step is to reheat the semi-finished product after storing it at room temperature or at a constant temperature to form the completed product. The product can be stretch blow molded.

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

[0027] [9] In the manufacturing method of the completed product, The step is a second step, The preform made of the thermoplastic resin The body part of The semi-finished blow mold Until it sticks to The method further comprises a first step of stretch blow molding 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 embodiment of the method for producing the completed product, the stretching speed and the timing of air blowing can be controlled to prevent the preform from bursting due to contact between the stretch rod and the preform.

[0029]

[10] In the manufacturing method of the completed product, The preform may be 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 comprises the steps of: A method for manufacturing a semi-finished product used in the method for manufacturing the finished product, comprising the steps of: The preform made of the thermoplastic resin The body part of The semi-finished blow mold Until it sticks toA first step of stretch blow molding 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 temperature of the semi-finished blow mold in the first step is adjusted to a temperature 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 the semi-finished product, the preform satisfies the formula (1) and the semi-finished blow mold temperature is set to the semi-finished product, so that the stretch orientation of the semi-finished product can be enhanced. Then, by molding a finished product using such a semi-finished product, the strength of the finished product can be improved and a finished product with excellent uniformity in wall thickness can be molded. Effect 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 finished product is molded from the semifinished product, improving the strength of the finished product and enabling the molding of a finished product with excellent thickness uniformity. Furthermore, even if the finished product is made lighter and thinner, it has excellent moldability. Furthermore, according to the manufacturing method of the finished product of the present invention, it has excellent moldability even if the shape of the finished product is diversified. Furthermore, according to the manufacturing method of the semifinished product, it is possible to increase the stretch orientation. [Brief description of the drawings]

[0034] [Figure 1] 4 is a flowchart of a method for manufacturing a completed product according to the present embodiment. [Diagram 2] FIG. 2 is a schematic diagram for explaining the relationship between a preform, a semi-finished body, and a finished body according to the embodiment. [Diagram 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. [Diagram 5] 11 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 PREFERRED EMBODIMENTS

[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 contents of the present invention described in the claims. In addition, not all of the configurations described below are necessarily essential components of the present invention.

[0036] 1. Overview of manufacturing method for 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 flow chart of the manufacturing method of the finished product according to this embodiment. Details of each step will be described later.

[0037] As shown in Fig. 1, the method for manufacturing a finished product according to this embodiment includes a second step (S30). The method for manufacturing a finished product may also include a first step (S20) before the second step (S30). Furthermore, the method for manufacturing a finished 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 for explaining the relationship between the preform 10, the semi-finished body 20, and the 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 by a solid line, the semi-finished body 20 by a dashed line, and the finished body 30 by 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] The preform can be heated by any known method used in biaxial stretch blow molding.

[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 can be PET (including crystalline, recycled PET, and modified PET), PEN, PEF, copolyester resin, PP, TPX, PE, plant-derived resin, biodegradable resin, recycled resin of the above resin, or blended resin. The preform can have a multilayer structure by a stack preform method, an overmolding method, or a 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, and then the inner layer preform is inserted into the injection core of an injection mold for the outer layer, and the outer layer resin is covered by injection molding after the mold is closed. The direct blow molding method is a method in which a pipe-shaped resin is extruded with a multilayer extrusion device, sandwiched between blow molds, and then air is blown in from a blow pin to mold 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 the vertical and horizontal directions by the stretching step and the blowing step. In the stretching step, the bottom 16 is moved in the direction of the arrow 1 by the stretching rod 40 inserted into the inside of the preform 10 from the mouth part 12 of the preform 10, and the body part 14 is stretched in the vertical direction. In the first step and the second step described later, the stretching speed of the stretching rod 40 can be adjusted to one speed or multiple speeds in the range of 300 mm / sec to 1000 mm / sec. In the blowing step, the body part 14 of the preform 10 can be inflated in the horizontal direction (circumferential direction) by compressed air introduced from the mouth part 12 until it is in 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 body 20 shown by the broken line. By adjusting the stretching speed within the above range and controlling the timing of blowing in the compressed air, it is possible to prevent the body part 14 from bursting due to contact with the stretching rod 40 in 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 semi-finished blow mold temperature 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 stretch ratio of the inner surface of the preform 10 is larger than that of the outer surface. Therefore, in order to secure the amount of heat during shaping, it is preferable that the outer surface temperature To is 100°C to 140°C, and the outer surface temperature To and the inner surface temperature Ti of the body part 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 a sufficient amount of heat even if the body part 14 of the preform 10 is made thick, for example, 4 mm or more, so that the shaping property of the finished body is excellent. On the other hand, in the preform 10 of a polyolefin resin, if the inner surface temperature Ti is too high, appropriate thickness may not be obtained due to drawdown, or the preform may burst, so it is preferable to satisfy formula (1).

[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 thickness uniformity 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. Moreover, it is preferable that the semi-finished body 20 has a shape with few projections and recesses in order to suppress internal distortion, and for example, the cross section is preferably circular. It is preferable that the bottom of the semi-finished body 20 is, for example, hemispherical.

[0048] 1-3.Second process S30: The second step is a step in which the semi-finished body 20 obtained by stretch-blow molding the thermoplastic resin preform 10 in the semi-finished blow mold is further stretch-blow molded to obtain the finished body 30. In the second step, the preform 10 can be stretched in the vertical and horizontal directions by the stretching and blowing steps, as in the first step. In the stretching step, the bottom part is moved in the direction of the arrow 2 by the stretching rod 40 inserted into the inside of the semi-finished body 20 from the mouth part 12 of the semi-finished body 20, and the body part is stretched in the vertical direction. For example, the second step can be a continuous step performed following the first step. By making it a continuous step, a space for storing the semi-finished body 20 is not required, so that the production line can be space-saving. In addition, by making it a continuous step, it is not necessary to transport the semi-finished body 20 using a vehicle or the like, and transportation costs can be reduced.

[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%, 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 the 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 stretching ratio is the maximum ratio at which the preform 10 or the semi-finished body 20 is stretched in the circumferential direction, and can be calculated as the ratio of the body diameter between the preform 10 and the finished body 30, or the ratio of the body diameter between the semi-finished body 20 and the finished body 30. The transverse stretching ratio of the flat container is calculated by calculating the area ratio in the longitudinal direction and the transverse direction of the body diameter. The longitudinal stretching ratio and the transverse stretching ratio can be calculated using the dimensions of the outer shape of the thin-walled semi-finished body 20 and the finished body 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 body 20 (area ratio of 30% to 60%) smaller than the finished body 30, excellent moldability can be achieved even if the finished body 30 is made lighter and thinner. In addition, by performing stretch blow molding using a semi-finished body 20 (area ratio of 30% to 60%) smaller than the finished body 30, excellent moldability can be achieved even if the shape of the finished body 30 is diversified (for example, modified example 1 described later).

[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) Here, Tg is the glass transition temperature of polyethylene terephthalate.

[0052] When the outer surface temperature t of the semi-finished body 20 satisfies the formula (2), the degree of molecular orientation when molding the finished body 30 is increased, 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 may be 100°C to 130°C. The crystallization temperature of polyethylene 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 finished product 30 is stretch-blow molded may be 120°C to 140°C. The crystallization temperature of polypropylene upon cooling is 120°C to 140°C.

[0055] The cooling crystallization temperature is the temperature range in which polyethylene and polypropylene are heated, melted, and then recrystallized. This recrystallization process causes the molecular chains in the semi-finished product 20 to form a more regular crystal structure, improving the strength and rigidity. When the semi-finished product 20 is stretched in this temperature range, the crystallized region increases and the crystal orientation improves, 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 may be adopted.

[0057] 2. Manufacturing method of the finished product according to the first modification A manufacturing method of the finished product 30a according to the first modification will be described in detail with reference to Figures 3 and 4. Figures 3 and 4 are schematic diagrams for explaining the relationship between the preform 10a, the semi-finished product 20a, and the finished product 30a according to the first modification. 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 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 completed body 30a according to the modified example 1 differs from the embodiment described in the above 1 in that the completed body 30a is a flat container. The manufacturing method of the completed body 30a according to the modified example 1 includes the second step (S30) like the embodiment described in the above 1, and may execute, 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 the above 1 will be omitted.

[0059] S10: 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 technique (e.g., JP 05-269828 A) that creates a temperature difference between the short side direction where the stretch ratio is low and the long side direction where the stretch ratio is high, but this requires complex positioning of the preform that is conveyed while rotating. However, according to the manufacturing method of the finished product according to the first modification, the body portion 14a can be heated uniformly in the circumferential direction, so complex positioning is not required.

[0060] S20: The semi-finished product 20a obtained by the 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 may have a cross section of the 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 of a size that does not contact the cavity of the finished product blow mold closed in the second step. This makes it possible to suppress the accumulation of material due to contact between the semi-finished product 20a and the cavity.

[0061] S30: The completed product 30a obtained by the stretch blow molding in the second step is, for example, a flattened bottle in which the longitudinal direction of the body of the completed product 30a at the height position where the body has the maximum width is two to three times the width of the lateral direction perpendicular to the longitudinal direction. In the case of a flattened bottle with a flattening ratio of two to three times in a general molding method, the lateral portion of the preform close to the blow mold comes into contact with the preform at the beginning of the stretch blow molding, so that the material tends to accumulate, and it is difficult to adjust the wall thickness distribution in the longitudinal direction. In contrast, the completed product 30a according to the modification 1 can have a uniform wall thickness distribution in the lateral direction and the longitudinal direction by the manufacturing method according to the embodiment of the above 1, and the material accumulation in the lateral direction can be suppressed. In addition, by making the semi-finished product 20a immediately before the second step according to the embodiment of the above 1, the degree of molecular orientation when molding the completed product 30a is increased, the strength of the completed product 30a is improved, and a flattened bottle with excellent wall thickness uniformity and two to three times the lateral direction perpendicular to the longitudinal direction can be molded.

[0062] 3. Manufacturing method of the finished product according to the second modification A method for manufacturing the finished product 30 according to the second modification will be described in detail with reference to Fig. 2 and Fig. 5. Fig. 5 is a flow chart of the method for manufacturing the finished product 30 according to the second modification.

[0063] As shown in FIG. 5, the method for producing 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 completed body 30 according to the modified example 2 may include a manufacturing method of the semi-finished body 20, and a manufacturing method of the completed body 30 using the semi-finished body 20. The manufacturing method of the semi-finished body 20 may be a first step of manufacturing the semi-finished body 20, 20a used in the manufacturing method of the completed body 30, 30a described in the embodiment 1 above or the modified example 1 of the embodiment 2 above.

[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 at 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 easy to adjust the production volume of the finished body 30. Furthermore, when the factory for manufacturing the semi-finished body 20 and the factory for manufacturing the finished body 30 are different, for example, the method may include 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 semi-finished product 20 after reheating 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. According to the manufacturing method of the finished product 30 according to the second modification, the finished product 30 has excellent moldability even if it is made lighter or thinner, and has excellent moldability even if the shape of the finished product 30 is diversified. EXAMPLES

[0068] In Example 1, the finished body 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 body 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 body 30a to the semi-finished body 20a. In Table 1, "long side thickness / short side thickness" indicates the longitudinal thickness of the body of the finished body 30 at the height position where the body has the maximum width, and the lateral thickness 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. Furthermore, the thickness was excellent overall for all materials, and the moldability of the finished product 30 was also excellent. EXAMPLES

[0071] Using the manufacturing method of the finished product 30 according to the embodiment 1 above, a finished product 30 (Example 2) having a medium 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 2 was 40% of the surface ratio of the finished product 30 to the semi-finished product 20. The thermoplastic resin 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) of JIS K7112 was used. In Comparative Example 1, a bottle was molded using the same resin and the same finished blow mold using a general single blow molding method. The thickness of both bottles was measured. The finished product 30 of Example 2 and the bottle of Comparative Example 1 had similar wall thickness distribution in the height direction. The wall thickness deviation rate (%) in the circumferential direction of the bottle was also measured. The measurement position was set at 0 mm at the ground surface 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 rate 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 deviation rates 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 in the circumferential direction of the finished bottle 30 of Example 2 was approximately half that of the bottle of Comparative Example 1. EXAMPLES

[0074] A finished product 30 (Example 3) with a bottle capacity of 600 ml and a mouth diameter of φ20 mm was molded using the manufacturing method for the finished product 30 according to the embodiment 1 above. 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 a direct blow molding method. The wall thickness of both bottles was about 0.4 to 0.5 mm, and although the HDPE material manufacturers were different, the material density was 0.953 g / cm. 3 The bottle weight of Example 3 was 29 g, and the bottle weight of Comparative Example 2 was 28 g.

[0075] The bottles of Example 3 and Comparative Example 2 were capped when filled with water, and a drop strength test was carried out (eight bottles of each type were dropped from a height of 2 m as a severe condition to create a difference). As a result, none of the eight bottles of Example 3 were cracked, but six of the eight bottles of Comparative Example 2 were cracked, resulting in a crack occurrence rate of 75%.

[0076] Next, dumbbell-shaped test pieces of 25 mm×100 mm 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 the displacement in mm, and the vertical axis is the 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 showed a yield stress about 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, including 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 effect). The present invention also includes configurations in which non-essential parts of the configurations described in the embodiments are replaced. The present invention also includes configurations that achieve the same effects as the configurations described in the embodiments, or configurations that can achieve the same purpose. The present invention also includes configurations in which publicly known technology is added 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 semi-finished product obtained by stretch-blow-molding a thermoplastic resin preform until the body portion thereof is in close contact with a semi-finished blow mold, and then stretch-blow-molding the semi-finished product until the body portion is in close contact with a finished product blow mold to obtain a finished product, A method for producing a finished product, characterized in that the product of the longitudinal stretch ratio and the transverse stretch ratio during stretch blow molding is defined as an areal ratio, and the areal ratio of the finished product to the semi-finished product is 30% to 60% of the areal ratio of the finished product to the preform.

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 body of the thermoplastic resin preform until the body is in close contact with the semi-finished blow mold to obtain the semi-finished body, 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, wherein the temperature of the semi-finished blow mold in the first step is adjusted to a temperature lower than the outer surface temperature To by −10° C. to −80° C. To=Ti≦To+5℃...(1)

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

4. The method for manufacturing a finished product according to claim 1 or 2, The thermoplastic resin is polyethylene, The outer surface temperature of the semi-finished product immediately before the finished product is stretch-blow molded is 100° C. to 13 0°C。 0°C.

5. 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. 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 product is characterized in that the finished product is a flattened 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. 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 body of the thermoplastic resin preform until the body is in close contact with the semi-finished blow mold to obtain the semi-finished body, A method for manufacturing a finished product, wherein the second step is a continuous step carried out following the first step.

8. 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 body of the thermoplastic resin preform until the body is in close contact with the semi-finished blow mold to obtain the semi-finished body, The second step is characterized in that the semi-finished product is stored at room temperature or at a constant temperature, and then reheated and stretch-blow molded into the finished product.

9. 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 body of the thermoplastic resin preform until the body is in close contact with the semi-finished blow mold to obtain the semi-finished body, The first and second steps are characterized in that the preform is stretched in the longitudinal and transverse directions by a stretching process in which the stretching speed of a stretch rod is adjusted to one speed or multiple speeds in the range of 300 mm / sec to 1000 mm / sec, and a blowing process using compressed air.

10. The method for manufacturing a finished product according to claim 1 or 2, The method for producing a finished product is characterized in that the preform has a multi-layer structure produced by a stack preform method, an overmolding method, or a direct blow molding method.

11. A method for manufacturing a semi-finished product using the method for manufacturing a finished product according to claim 1, comprising the steps of: The method further includes a first step of stretch blow molding the body of the thermoplastic resin preform until the body is in close contact with the semi-finished blow mold to obtain the semi-finished body, 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 lower than the outer surface temperature To by −10° C. to −80° C. To=Ti≦To+5℃...(1)

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