Preform and plastic bottle

Abstract

To provide a preform and a plastic bottle capable of being filled with high-temperature contents without crystallizing a mouth portion.SOLUTION: A preform 10 includes a mouth portion 11 having an opening 15, a body portion 20 connected to the mouth portion 11, and a bottom portion 30 connected to the body portion 20. The mouth portion 11 of the preform 10 includes a mouth body 12 and a thread portion 13. When an outer diameter of the mouth body 12 is denoted as D1 and an inner diameter of the mouth body 12 is denoted as D2, D2 / D1=0.80 to 0.90.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to preforms and plastic bottles. [Background technology]

[0002] BACKGROUND ART Conventionally, plastic bottles have been produced by biaxially stretching and blow molding a polyethylene terephthalate preform produced by, for example, injection molding. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-13664 Summary of the Invention [Problem to be solved by the invention]

[0004] The produced plastic bottle is filled with liquid contents through the mouth, and in this case, it is desirable to fill the mouth with liquid contents at a high temperature (e.g., 70°C to 90°C) without causing the mouth to crystallize, as is the case when filling with liquid contents at room temperature.

[0005] The present disclosure has been made in consideration of these points, and provides a preform and a plastic bottle that can be filled with a high-temperature liquid content without causing crystallization of the mouth portion. [Means for solving the problem]

[0006] The present disclosure relates to a preform comprising a cylindrical mouth portion having a mouth portion main body and a threaded portion provided on the outer periphery of the mouth portion main body, a cylindrical trunk portion connected to the mouth portion, and a bottom portion connected to the trunk portion, wherein, when the outer diameter of the mouth portion main body of the mouth portion is D1 and the inner diameter of the mouth portion main body is D2, D2 / D1 = 0.80 to 0.90, and the threaded portion extends continuously along the circumferential direction without any cut portions.

[0007] The present disclosure relates to a preform in which the mouth portion is amorphous, and the heat of crystallization during the first temperature decrease after the first temperature increase, as measured by differential scanning calorimetry, is 40.0 J / g or more and 43.0 J / g or less.

[0008] The present disclosure relates to a preform in which the mouth portion is amorphous and the heat of fusion during the second heating step, as measured by differential scanning calorimetry, is 41.0 J / g or more and 44.0 J / g or less.

[0009] The present disclosure relates to a plastic bottle including a cylindrical mouth portion having a mouth body and a threaded portion provided on the outer periphery of the mouth body, wherein, when the outer diameter of the mouth body of the mouth portion is D1 and the inner diameter of the mouth body is D2, D2 / D1 = 0.80 to 0.90, and the threaded portion extends continuously along the circumferential direction without any cut portions.

[0010] The present disclosure provides a plastic bottle, wherein the mouth portion is amorphous, and the heat of crystallization during a first temperature decrease after a first temperature increase, as measured by differential scanning calorimetry, is 40.0 J / g or more and 43.0 J / g or less.

[0011] The present disclosure relates to a plastic bottle in which the mouth is amorphous and the heat of fusion during the second heating step, as determined by differential scanning calorimetry of the mouth, is 41.0 J / g or more and 44.0 J / g or less. [Effects of the Invention]

[0012] According to this embodiment, the plastic bottle can be filled with a high-temperature liquid without causing crystallization of the mouth portion. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a front view showing a preform according to this embodiment. [Figure 2] FIG. 2 is a vertical cross-sectional view (cross-sectional view passing through the central axis of the preform) showing the preform shown in FIG. [Figure 3] FIG. 3 is a front view showing a plastic bottle produced from the preform according to this embodiment. [Figure 4A] FIG. 4A is a diagram showing a method for manufacturing a plastic bottle according to the present embodiment. [Figure 4B] FIG. 4B is a diagram showing a method for manufacturing a plastic bottle according to the present embodiment. [Figure 4C] FIG. 4C is a diagram showing a method for manufacturing a plastic bottle according to the present embodiment. [Figure 4D] FIG. 4D is a diagram showing a method for manufacturing a plastic bottle according to this embodiment. [Figure 4E] FIG. 4E is a diagram showing a method for manufacturing a plastic bottle according to this embodiment. [Figure 5A] FIG. 5A is a view showing the mouth of a preform according to Example 1. FIG. [Figure 5B] FIG. 5B is a view showing the mouth of the preform according to Comparative Example 1-2. [Figure 6] Figure 6 is a chart showing the measurement conditions for DSC performed on the mouth of the preform. [Figure 7] Figure 7 shows the results of DSC measurements performed on the mouth of the preform. [Figure 8] FIG. 8 is a diagram showing the dimensions of the preform of this embodiment. [Figure 9] FIG. 9 is a diagram showing the thickness distribution of the preform in this embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0014] <Present Embodiment> DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present disclosure will be described with reference to the drawings, in which: Figures 1 to 5A and Figures 6 to 9 show embodiments of the present disclosure.

[0015] In this specification, "upper" and "lower" refer to the upper and lower sides in a state in which the mouth 11 of the preform 10 faces vertically upward and the bottom 30 of the preform 10 faces vertically downward (FIGS. 1 and 2). In this specification, the "central axis CL" of the preform 10 refers to the central axis of the cylinder that forms the inner surface of the mouth 11 of the preform 10.

[0016] In this specification, the "height direction" refers to the direction along the central axis CL of the preform 10, and the "radial direction" refers to the direction perpendicular to the central axis CL of the preform 10. The "circumferential direction" refers to the circumferential direction of a circle centered on the central axis CL of the preform 10. The "horizontal cross section" refers to a cross section cut by a plane perpendicular to the central axis CL of the preform 10. The "vertical cross section" refers to a cross section cut by a plane including the central axis CL of the preform 10.

[0017] An overview of a preform according to an embodiment of the present disclosure will be described with reference to FIGS. 1 and 2. FIG.

[0018] The preform 10 shown in FIG. 1 includes a mouth portion 11 having an opening 15, a body portion 20 connected to the mouth portion 11, and a bottom portion 30 connected to the body portion 20. The body portion 20 has a large diameter portion 21, a small diameter portion 23, and a tapered diameter portion 22. The large diameter portion 21 is located on the mouth portion 11 side. The small diameter portion 23 is located on the bottom portion 30 side. The tapered diameter portion 22 is located between the large diameter portion 21 and the small diameter portion 23. The tapered diameter portion 22 tapers in diameter from the large diameter portion 21 side toward the small diameter portion 23 side. The thinnest portion of the body portion 20 and the bottom portion 30 is preferably the lowest portion 31 of the bottom portion 30. When the thickness of the lowest portion 31 of the bottom portion 30 is T7 and the thickness of the small diameter portion 23 of the body portion 20 is T4, T7 is an average value of approximately 0.8 x T4. In this embodiment, the thickness of a predetermined portion of the body portion 20 of the preform 10 refers to the distance between the outer surface and the inner surface of that portion when measured along a direction perpendicular to the central axis CL. In this case, the thickness of the body portion 20 of the preform 10 is measured using a fully automatic measuring device (EH-8000, Preform Automatic Thickness Measuring Device, manufactured by Ebic Co., Ltd.). The thickness of the bottom portion 30 refers to the distance between the outer surface and the inner surface along the normal direction to the outer surface.

[0019] The mouth portion 11 has a cylindrical mouth portion body 12, a threaded portion 13 provided on the outer periphery of the mouth portion body 12, and a support ring 14 provided below the threaded portion 13. The mouth portion body 12, excluding the threaded portion 13, has an outer diameter D1 and an inner diameter D2.

[0020] In this embodiment, as shown in FIG. 5A , the threaded portion 13 provided on the outer periphery of the mouth body 12 of the mouth 11 extends continuously in a spiral shape along the circumferential direction without any cut portions for air vents. Because the threaded portion 13 extends continuously in a spiral shape along the circumferential direction on the outer periphery of the mouth body 12, when the preform 10 is subjected to biaxial stretch blow molding as described below to produce a plastic bottle 40 and the plastic bottle 40 is filled with a high-temperature (e.g., 70°C to 90°C) liquid content through the mouth 41, the mouth 41 is thermally deformed uniformly along the circumferential direction (see FIG. 3 ). Therefore, when the high-temperature liquid content is filled into the plastic bottle 40 through the mouth 41, the mouth 41 is not thermally deformed non-uniformly. Therefore, when a cap 60 (see FIG. 3 ) is attached to the mouth 41 of the plastic bottle 40, the liquid content does not leak between the mouth 41 and the cap 60. Although no cut portion for an air vent is provided in the mouth portion 11, a cut portion for an air vent may be provided on the inner surface of the cap 60 instead.

[0021] The outer diameter D1 of the mouth body 12 may be 18 mm or more and 33 mm or less. In this case, the outer diameter D1 of the mouth body 12 may be 18 mm or more, 20 mm or more, or 22 mm or more. The outer diameter D1 of the mouth body 12 may be 33 mm or less, 30 mm or less, or 27 mm or less. The inner diameter D2 of the mouth body 12 may be 13 mm or more and 27 mm or less. In this case, the inner diameter D2 of the mouth body 12 may be 13 mm or more, 15 mm or more, or 18 mm or more. The inner diameter D2 of the mouth body 12 may be 27 mm or less, 24 mm or less, or 22 mm or less.

[0022] The length L1 of the mouth portion 11 in the height direction may be, for example, 14 mm or more and 28 mm or less. In this case, the length L1 of the mouth portion 11 in the height direction may be, for example, 14 mm or more, 16 mm or more, or 18 mm or more. The length L1 of the mouth portion 11 in the height direction may be 28 mm or less, 25 mm or less, or 23 mm or less.

[0023] The threaded portion 13 is for screwing on a cap (not shown) after the preform 10 is biaxially stretch blow molded to produce a plastic bottle 40 (see FIG. 3). The support ring 14 is provided below the mouth portion 11 and protrudes in an annular shape around the entire circumference. The body portion 20 is connected to the lower part of the support ring 14.

[0024] As described above, the body portion 20 has the large diameter portion 21, the small diameter portion 23, and the tapered diameter portion 22.

[0025] The large diameter portion 21 is connected to the lower part of the support ring 14. The large diameter portion 21 has an outer surface 21a and an inner surface 21b. The length L2 of the large diameter portion 21 in the height direction may be, for example, 0.5 mm or more and 4.5 mm or less. In this case, the length L2 of the large diameter portion 21 in the height direction may be, for example, 0.5 mm or more, 1.0 mm or more, 1.5 mm or more, 2.2 mm or more, 2.5 mm or more, or 2.9 mm or more. The length L2 of the large diameter portion 21 in the height direction may be 4.5 mm or less, 4.1 mm or less, or 3.8 mm or less.

[0026] The large diameter portion 21 has a generally cylindrical shape overall and has an outer diameter D3 and an inner diameter D4. The outer diameter D3 of the large diameter portion 21 may be 18 mm or more and 34 mm or less. In this case, the outer diameter D3 of the large diameter portion 21 may be 18 mm or more, 20.5 mm or more, or 23 mm or more. The outer diameter D3 of the large diameter portion 21 may be 34 mm or less, 31 mm or less, or 28 mm or less. The outer diameter D3 of the large diameter portion 21 may be larger than the outer diameter D1 of the mouth portion main body 12 described above, or may be the same as the outer diameter D1 of the mouth portion main body 12.

[0027] The inner diameter D4 of the large diameter portion 21 may be the same as the inner diameter D2 of the mouth main body 12 described above. The inner diameter D4 of the large diameter portion 21 may be 13 mm or more and 27 mm or less. In this case, the inner diameter D4 of the large diameter portion 21 may be 13 mm or more, 15 mm or more, or 18 mm or more. The inner diameter D4 of the large diameter portion 21 may be 27 mm or less, 24 mm or less, or 22 mm or less. The large diameter portion 21 has a thickness T1. The thickness T1 of the large diameter portion 21 may be 1.2 mm or more and 3.2 mm or less. In this case, the thickness T1 of the large diameter portion 21 may be 2.0 mm or more, 2.2 mm or more, or 2.4 mm or more. The thickness T1 of the large diameter portion 21 may be 3.2 mm or less, 3.0 mm or less, or 2.8 mm or less.

[0028] The reduced diameter portion 22 is connected to the lower part of the large diameter portion 21, and has a shape that gradually reduces in diameter from the large diameter portion 21 side toward the small diameter portion 23 side. The reduced diameter portion 22 is a cylindrical shape that is approximately a truncated cone, and has an outer surface 22a and an inner surface 22b. A third boundary portion 28 exists at the boundary between the large diameter portion 21 and the reduced diameter portion 22. The third boundary portion 28 is a point where, in a vertical cross section, the angle formed between the inner surface 21b of the large diameter portion 21 and the inner surface 22b of the reduced diameter portion 22, and the angle formed between the outer surface 21a of the large diameter portion 21 and the outer surface 22a of the reduced diameter portion 22, change significantly. In other words, third boundary 28 refers to a location in the vertical cross section ( FIG. 2A ) where the radius of curvature is minimal between inner surface 21 b of large diameter portion 21 and inner surface 22 b of reduced diameter portion 22, and a location where the radius of curvature is minimal between outer surface 21 a of large diameter portion 21 and outer surface 22 a of reduced diameter portion 22. If the location where the angle between inner surface 21 b of large diameter portion 21 and inner surface 22 b of reduced diameter portion 22 changes significantly and the location where the angle between outer surface 21 a of large diameter portion 21 and outer surface 22 a of reduced diameter portion 22 changes significantly are offset in the height direction, third boundary 28 refers to the location that is closer to mouth 11 of these locations.

[0029] The height direction length L3 of the reduced diameter portion 22 may be, for example, 8 mm or more and 16 mm or less. In this case, the height direction length L3 of the reduced diameter portion 22 may be, for example, 8 mm or more, 9 mm or more, 10.0 mm or more, 10.5 mm or more, or 11.0 mm or more. The height direction length L3 of the reduced diameter portion 22 may be 16 mm or less, 15 mm or less, 14 mm or less, 13.0 mm or less, 12.5 mm or less, or 12.0 mm or less. The horizontal cross section of the reduced diameter portion 22 may be circular throughout the height direction. The outer surface 22a of the reduced diameter portion 22 has an outer diameter D5 that varies along the height direction, and the inner surface 22b of the reduced diameter portion 22 has an inner diameter D6 that varies along the height direction. The outer diameter D5 and inner diameter D6 of the reduced diameter portion 22 each gradually decrease from the large diameter portion 21 side to the small diameter portion 23 side.

[0030] The outer surface 22a and the inner surface 22b of the reduced diameter portion 22 are each inclined with respect to the central axis CL of the preform 10. In a vertical cross section, the angle θ1 at which the outer surface 22a of the reduced diameter portion 22 is inclined with respect to the central axis CL may be 6° or more and 22° or less. In this case, in a vertical cross section, the angle θ1 at which the outer surface 22a of the reduced diameter portion 22 is inclined with respect to the central axis CL may be 6° or more, 8° or more, or 10° or more. The angle θ1 at which the outer surface 22a of the reduced diameter portion 22 is inclined with respect to the central axis CL may be 22° or less, 20° or less, or 18° or less. The angle θ2 at which the inner surface 22b of the reduced diameter portion 22 is inclined with respect to the central axis CL may be 6° or more and 22° or less. In this case, the angle θ2 at which the inner surface 22b of the reduced diameter portion 22 is inclined with respect to the central axis CL may be 6° or more, 8° or more, or 10° or more. The angle θ2 at which the inner surface 22b of the reduced diameter portion 22 is inclined with respect to the central axis CL may be equal to or less than 22°, or may be equal to or less than 20°, or may be equal to or less than 18°. The angle θ1 may be the same as the angle θ2.

[0031] The reduced diameter portion 22 has a thickness T2, which will be described later. The thickness T3 of the reduced diameter portion 22 at the second boundary 27 may be thinner, thicker, or the same as the thickness T1 of the reduced diameter portion 22 at the third boundary 28. The thickness T3 of the reduced diameter portion 22 and the small diameter portion 23 at the second boundary 27 may be 1.4 mm or more and 3.4 mm or less. In this case, the thickness T3 of the reduced diameter portion 22 and the small diameter portion 23 at the second boundary 27 may be, for example, 1.4 mm or more, 2.0 mm or more, 2.3 mm or more, 2.5 mm or more, or 2.7 mm or more. The thickness T3 of the reduced diameter portion 22 and the small diameter portion 23 at the second boundary 27 may be 3.4 mm or less, 3.2 mm or less, or 3.1 mm or less.

[0032] The outer diameter D7 of the reduced diameter portion 22 and the small diameter portion 23 at the second boundary 27 may be 15 mm or more and 27 mm or less. In this case, the outer diameter D7 of the reduced diameter portion 22 and the small diameter portion 23 at the second boundary 27 may be 15 mm or more, 18 mm or more, or 20 mm or more. The outer diameter D7 of the reduced diameter portion 22 and the small diameter portion 23 at the second boundary 27 may be 27 mm or less, 25 mm or less, or 24 mm or less. The inner diameter D8 of the reduced diameter portion 22 and the small diameter portion 23 at the second boundary 27 may be 13 mm or more and 20 mm or less. In this case, the inner diameter D8 of the reduced diameter portion 22 and the small diameter portion 23 at the second boundary 27 may be 13 mm or more, 14 mm or more, or 15 mm or more. The inner diameter D8 of the reduced diameter portion 22 and the small diameter portion 23 at the second boundary portion 27 may be 20 mm or less, 18 mm or less, or 16 mm or less.

[0033] Small diameter portion 23 is connected to the lower part of reduced diameter portion 22 and has an outer surface 23a and an inner surface 23b. A second boundary portion 27 exists at the boundary between reduced diameter portion 22 and small diameter portion 23. Second boundary portion 27 is a location where, in a vertical cross section, the angle formed between inner surface 22b of reduced diameter portion 22 and inner surface 23b of small diameter portion 23, and the angle formed between outer surface 22a of reduced diameter portion 22 and outer surface 23a of small diameter portion 23, change significantly. In other words, second boundary portion 27 refers to a location where, in a vertical cross section ( FIG. 2 ), the radius of curvature is minimal between inner surface 22b of reduced diameter portion 22 and inner surface 23b of small diameter portion 23, and a location where the radius of curvature is minimal between outer surface 22a of reduced diameter portion 22 and outer surface 23a of small diameter portion 23. When the point where the angle between the inner surface 22b of the reduced diameter portion 22 and the inner surface 23b of the small diameter portion 23 changes significantly and the point where the angle between the outer surface 22a of the reduced diameter portion 22 and the outer surface 23a of the small diameter portion 23 changes significantly are offset in the vertical direction, the second boundary portion 27 refers to the point that is closer to the bottom 30.

[0034] The height direction length L4 of the small diameter portion 23 may be, for example, 30 mm or less, 90 mm or less. In this case, the height direction length L4 of the small diameter portion 23 may be, for example, 30 mm or more, 40 mm or more, 48 mm or more, 50 mm or more, or 52 mm or more. The height direction length L4 of the small diameter portion 23 may be 90 mm or less, 80 mm or less, 70 mm or less, 60 mm or less, 58 mm or less, or 56 mm or less. The outer surface 23a and inner surface 23b of the small diameter portion 23 are each inclined with respect to the central axis CL of the preform 10. In a vertical cross section, the angle θ3 at which the outer surface 23a of the small diameter portion 23 is inclined with respect to the central axis CL may be greater than 0° and less than 5°. In this case, in a vertical cross section, the angle θ3 at which the outer surface 23a of the small diameter portion 23 is inclined with respect to the central axis CL may be greater than 0°, greater than 0.1°, or greater than 0.2°. The angle θ3 at which the outer surface 23a of the small diameter portion 23 is inclined with respect to the central axis CL may be 5° or less, 1° or less, or 0.7° or less. The angle θ3 at which the outer surface 23a of the small diameter portion 23 is inclined may be an angle (so-called draft angle) set to make it easier to remove the preform 10 from the injection molding die when producing the preform 10. The angle θ4 at which the inner surface 23b of the small diameter portion 23 is inclined with respect to the central axis CL may be greater than 0° and less than 5°. In this case, the angle θ4 at which the inner surface 23b of the small diameter portion 23 is inclined with respect to the central axis CL may be greater than 0°, greater than 0.1°, or greater than 0.2°. The angle θ4 at which the inner surface 23b of the small diameter portion 23 is inclined with respect to the central axis CL may be 5° or less, less than 1°, or less than 0.7°. The angle θ4 may be the same as the angle θ3.

[0035] The horizontal cross section of the small diameter portion 23 is circular throughout the height direction. The outer surface 23a of the small diameter portion 23 has an outer diameter D9 that varies along the height direction. The inner surface 23b of the small diameter portion 23 has an inner diameter D9 that varies along the height direction. 10 The small diameter portion 23 has an outer diameter D9 and an inner diameter D 10are gradually tapered from the reduced diameter portion 22 side toward the bottom portion 30 side. In a vertical cross section, the outer surface 23a of the small diameter portion 23 is generally linear, but a portion of the outer surface 23a of the small diameter portion 23 may be curved. Similarly, in a vertical cross section, the inner surface 23b of the small diameter portion 23 is generally linear, but a portion of the inner surface 23b of the small diameter portion 23 may be curved.

[0036] The thickness T4 of the small diameter portion 23 is uniform from the reduced diameter portion 22 (second boundary portion 27) side to the bottom portion 30 (first boundary portion 26) side. In other words, the thickness T4 of the small diameter portion 23, the thickness T3 at the second boundary portion 27, and the thickness T5 at the first boundary portion 26 are all the same (T3 = T4 = T5). The thickness T4 of the small diameter portion 23 (= T3 = T5) may be 1.8 mm or more and 3.7 mm or less. In this case, the thickness T4 of the small diameter portion 23 (= T3 = T5) may be, for example, 1.8 mm or more, 2.0 mm or more, 2.2 mm or more, 2.5 mm or more, 2.6 mm or more, or 2.7 mm or more. The thickness T4 (=T3=T5) of the small diameter portion 23 may be, for example, 3.7 mm or less, 3.5 mm or less, 3.3 mm or less, 3.2 mm or less, or 3.1 mm or less.

[0037] The outer diameter D of the small diameter portion 23 at the first boundary portion 26 11 In this case, the outer diameter D of the small diameter portion 23 at the first boundary portion 26 may be set to 18 mm or more and 24 mm or less. 11 The outer diameter D of the small diameter portion 23 at the first boundary portion 26 may be 18 mm or more, 19 mm or more, or 20 mm or more. 11 The inner diameter D of the small diameter portion 23 at the first boundary portion 26 may be 24 mm or less, 23 mm or less, or 22 mm or less. 12 In this case, the inner diameter D of the small diameter portion 23 at the first boundary portion 26 may be set to, for example, 13 mm or more and 18 mm or less. 12 The inner diameter D of the small diameter portion 23 at the first boundary portion 26 may be, for example, 13 mm or more, 14 mm or more, or 15 mm or more. 12may be 18 mm or less, may be 17 mm or less, or may be 16 mm or less.

[0038] Bottom portion 30 is connected to the lower part of small diameter portion 23 and has an outer surface 30a and an inner surface 30b. A first boundary portion 26 exists at the boundary between small diameter portion 23 and bottom portion 30. First boundary portion 26 is a point where, in a vertical cross section, the angle between the inner surface 23b of small diameter portion 23 and the inner surface 30b of bottom portion 30, and the angle between the outer surface 23a of small diameter portion 23 and the outer surface 30a of bottom portion 30, change significantly. In other words, first boundary portion 26 refers to the point where, in a vertical cross section ( FIG. 2 ), the radius of curvature first becomes 100 mm or less on the way from the inner surface 23b of small diameter portion 23 to the inner surface 30b of bottom portion 30, and the point where the radius of curvature first becomes 100 mm or less on the way from the outer surface 23a of small diameter portion 23 to the outer surface 30a of bottom 30. When the point where the angle between the inner surface 23b of the small diameter portion 23 and the inner surface 30b of the bottom portion 30 changes significantly and the point where the angle between the outer surface 23a of the small diameter portion 23 and the outer surface 30a of the bottom portion 30 changes significantly are offset in the vertical direction, the first boundary portion 26 refers to the point that is closer to the mouth portion 11.

[0039] The height direction length L5 of the bottom portion 30 may be, for example, 7 mm or more and 12 mm or less. In this case, the height direction length L5 of the bottom portion 30 may be, for example, 7 mm or more, 8 mm or more, or 9 mm or more. The height direction length L5 of the bottom portion 30 may be 12 mm or less, 11 mm or less, or 10 mm or less. The bottom portion 30 has a generally hemispherical shape. In a vertical cross section, the outer surface 30a of the bottom portion 30 is generally semicircular, but the outer surface 30a of the bottom portion 30 may have a curved shape including a non-circular portion. Similarly, in a vertical cross section, the inner surface 30b of the bottom portion 30 is generally semicircular, but a portion of the inner surface 30b of the bottom portion 30 may have a curved shape including a non-circular portion. In the vertical cross section, the center O1 of the semicircle constituting the outer surface 30a of the bottom portion 30 lies on the central axis CL. Furthermore, the center O2 of the semicircle constituting the inner surface 30b of the bottom portion 30 lies on the central axis CL. The center O2 of the semicircle that forms the inner surface 30b of the bottom 30 may be located at the same position as the center O1 of the semicircle that forms the outer surface 30a of the bottom 30. The horizontal cross section of the bottom 30 is circular throughout the entire height direction.

[0040] The radius of curvature R1 of the semicircle constituting the outer surface 30a of the bottom portion 30 may be 8 mm or more and 14 mm or less. In this case, the radius of curvature R1 of the semicircle constituting the outer surface 30a of the bottom portion 30 may be 8 mm or more, 9 mm or more, or 10 mm or more. The radius of curvature R1 of the semicircle constituting the outer surface 30a of the bottom portion 30 may be 14 mm or less, 13 mm or less, or 12 mm or less. The radius of curvature R2 of the semicircle constituting the inner surface 30b of the bottom portion 30 may be 6.5 mm or more and 10 mm or less. In this case, the radius of curvature R2 of the semicircle constituting the inner surface 30b of the bottom portion 30 may be 6.5 mm or more, 7.0 mm or more, or 7.5 mm or more. The radius of curvature R2 of the semicircle constituting the inner surface 30b of the bottom portion 30 may be 10 mm or less, 9.5 mm or less, or 9 mm or less.

[0041] The ratio (R1 / R2) of the radius of curvature R1 to the radius of curvature R2 may be greater than 1.0 and less than or equal to 1.9. In this case, the ratio (R1 / R2) of the radius of curvature R1 to the radius of curvature R2 may be greater than 1.0, greater than or equal to 1.1, or greater than or equal to 1.2. The ratio (R1 / R2) of the radius of curvature R1 to the radius of curvature R2 may be less than or equal to 1.9, less than or equal to 1.5, or less than or equal to 1.3. By setting the ratio to 1.9 or less, the radius of curvature R2 of the semicircle constituting the inner surface 30b of the bottom portion 30 does not become too small, and the angle θ4 at which the inner surface 23b of the small diameter portion 23 is inclined relative to the central axis CL does not become too large, which makes it difficult to produce the preform 10 by injection molding. By making the above ratio greater than 1.0, the radius of curvature R2 of the semicircle constituting the inner surface 30b of the bottom portion 30 does not become too large, the thickness T5 of the small diameter portion 23 at the first boundary portion 26 is ensured, and it is possible to prevent the preform 10 from becoming difficult to produce by injection molding.

[0042] The thickness T6 of the bottom portion 30 gradually decreases from the body portion 20 (first boundary portion 26) side toward the lowest portion 31 of the bottom portion 30 (the portion where the bottom portion 30 intersects with the central axis CL). That is, the thickness T5 of the bottom portion 30 (small diameter portion 23) at the first boundary portion 26 is thicker than the thickness T7 of the bottom portion 30 at the lowest portion 31. The thickness T5 at the first boundary portion 26 is the thickest within the bottom portion 30.

[0043] The thickness T5 of the bottom 30 (small diameter portion 23) at the first boundary 26 may be 1.6 mm or more and 3.4 mm or less. In this case, the thickness T5 of the bottom 30 (small diameter portion 23) at the first boundary 26 may be 2.4 mm or more, 2.6 mm or more, or 2.8 mm or more. The thickness T5 of the bottom 30 (small diameter portion 23) at the first boundary 26 may be 3.4 mm or less, 3.2 mm or less, or 3.0 mm or less. The thickness T7 of the bottom 30 at the lowest portion 31 may be 1.2 mm or more and 3.2 mm or less. In this case, the thickness T7 of the bottom 30 at the lowest portion 31 may be, for example, 1.2 mm or more, 1.5 mm or more, 1.7 mm or more, 1.9 mm or more, or 2.1 mm or more. The thickness T7 of the bottom portion 30 at the lowest portion 31 may be, for example, 3.2 mm or less, 3.0 mm or less, 2.7 mm or less, 2.5 mm or less, or 2.3 mm or less. The ratio (T7 / T5) of the thickness T7 of the bottom portion 30 at the lowest portion 31 to the thickness T5 of the bottom portion 30 (small diameter portion 23) at the first boundary portion 26 may be 0.5 or more and 1.0 or less. In this case, the ratio (T7 / T5) of the thickness T7 of the bottom portion 30 at the lowest portion 31 to the thickness T5 of the bottom portion 30 (small diameter portion 23) at the first boundary portion 26 may be 0.5 or more, 0.6 or more, or 0.7 or more. The ratio (T7 / T5) of the thickness T7 of the bottom portion 30 at the lowermost portion 31 to the thickness T5 of the bottom portion 30 (small diameter portion 23) at the first boundary portion 26 may be 1.0 or less, 0.9 or less, or 0.85 or less.

[0044] In this embodiment, the ratio (T7 / T1) of the thickness T7 of the bottom portion 30 at the lowest portion 31 to the thickness T1 of the large diameter portion 21 may be 0.80 or more and 0.95 or less. In this case, the ratio (T7 / T1) of the thickness T7 of the bottom portion 30 at the lowest portion 31 to the thickness T1 of the large diameter portion 21 may be 0.80 or more, 0.82 or more, or 0.83 or more. The ratio (T7 / T1) of the thickness T7 of the bottom portion 30 at the lowest portion 31 to the thickness T1 of the large diameter portion 21 may be 0.95 or less, or 0.93 or less. By making the ratio T7 / T1 0.80 or more, it is possible to prevent a defect known as whitening from occurring in the heel portion 49 of the plastic bottle 40, which will be described later, and to prevent a decrease in the strength of the heel portion 49. By making the ratio T7 / T1 0.95 or less, the thickness of the bottom portion 30 of the preform 10, which is less likely to be stretched during molding of the plastic bottle 40, can be reduced, thereby making it possible to increase the thickness of the body portion 42 and heel portion 49, which are stretched, even for a preform 10 of the same weight. This allows the weight of the preform 10 to be reduced.

[0045] The total height of the body portion 20 and the bottom portion 30 (i.e., the height of the portion of the preform 10 below the support ring 14) is L6, which is the sum of the above-described lengths L2, L3, L4, and L5 (L6 = L2 + L3 + L4 + L5). The total length L6 may be 55 mm or more and 100 mm or less. In this case, the total length L6 may be 55 mm or more, 60 mm or more, 65 mm or more, 70 mm or more, 73.0 mm or more, 75.0 mm or more, or 78.0 mm or more. The total length L6 may be, for example, 100 mm or less, 95 mm or less, 90 mm or less, 84.0 mm or less, 82.0 mm or less, or 80.0 mm or less. By making the total length L6 73.0 mm or more, the longitudinal stretching ratio during molding of the plastic bottle 40 (described later) is prevented from becoming too large, thereby preventing overstretching. This prevents a defect known as whitening from occurring in the heel portion 49 of the plastic bottle 40 and a decrease in the strength of the heel portion 49. By making the total length L6 84.0 mm or less, the thickness of the body portion 20 is less likely to become thin when the mass of the preform 10 is kept constant, as the total length L6 is reduced. This prevents whitening of the body portion 42 during molding of the plastic bottle 40. Furthermore, by not making the total length L6 of the preform 10 too long, it is possible to prevent the longitudinal stretching from becoming too small or from occurring at all. This makes it easy to mold the plastic bottle 40, even if it is a small, low-profile bottle with a capacity of approximately 100 mL.

[0046] The total length of the preform 10 is L7, which is the sum of the total length L6 and the length L1 (L7 = L1 + L6). The total length L7 of the preform 10 may be 60 mm or more and 130 mm or less. In this case, the total length L7 of the preform 10 may be 60 mm or more, 70 mm or more, 80 mm or more, 88 mm or more, 93 mm or more, or 98 mm or more. The total length L7 of the preform 10 may be 130 mm or less, 120 mm or less, 112 mm or less, 107 mm or less, or 102 mm or less.

[0047] The mass of the mouth portion 11 of the preform 10 is W1, and the total mass of the body portion 20 and the bottom portion 30 is W2. In this case, the ratio (W2 / W1) of the total mass W2 of the body portion 20 and the bottom portion 30 to the mass W1 of the mouth portion 11 may be 1.1 or more and 12 or less. In this case, the ratio (W2 / W1) of the total mass W2 of the body portion 20 and the bottom portion 30 to the mass W1 of the mouth portion 11 may be, for example, 1.1 or more, 1.5 or more, 1.80 or more, 1.95 or more, or 2.10 or more. The ratio (W2 / W1) of the total mass W2 of the body portion 20 and the bottom portion 30 to the mass W1 of the mouth portion 11 may be 12 or less, 8 or less, 4 or less, 2.70 or less, 2.55 or less, or 2.40 or less. By making the ratio W2 / W1 1.80 or more, the amount of resin in the body 20 and bottom 30 is not excessively reduced. This prevents the plastic bottle 40 from being overstretched in the longitudinal direction when it is molded, as described below. This prevents a defect known as whitening from occurring in the heel 49 of the plastic bottle 40, and prevents a decrease in the strength of the heel 49. By making the ratio W2 / W1 2.70 or less, the mass of the preform 10 is prevented from becoming too heavy.

[0048] The total mass (W1 + W2) of the preform 10 may be 10 g or more and 70 g or less. In this case, the total mass (W1 + W2) of the preform 10 may be, for example, 10 g or more, 15 g or more, 20 g or more, 22.0 g or more, 22.5 g or more, or 23.0 g or more. The total mass (W1 + W2) of the preform 10 may be 70 g or less, 50 g or less, 30 g or less, 25.0 g or less, 24.5 g or less, or 24.0 g or less.

[0049] As described above, in the body portion 20 of the preform 10, the large diameter portion 21 has a thickness T1, the reduced diameter portion 22 has a thickness T2, and the small diameter portion 23 has a thickness T4.

[0050] In this embodiment, the thickness T1 of the large diameter portion 21, the thickness T2 of the reduced diameter portion 22, and the thickness T4 of the small diameter portion 23 have the following relationship.

[0051] The average value of the thickness T1 of the large diameter portion 21≦the average value of the thickness T4 of the small diameter portion 23.

[0052] The body portion 20 of the preform 10 is composed of a large diameter portion 21 , a reduced diameter portion 22 , and a small diameter portion 23 , and the thinnest portion 20 A of the body portion 20 is present in the reduced diameter portion 22 .

[0053] Since the thin-walled portion 20A, which is the thinnest part of the body portion 20, is present in the reduced diameter portion 22, the present embodiment provides the following advantageous effects.

[0054] That is, plastic bottle 40 is obtained by blow molding preform 10 according to this embodiment (see FIG. 3). At this time, reduced diameter portion 22 of preform 10 roughly corresponds to shoulder portion 48 of plastic bottle 40. In this case, if reduced diameter portion 22 of preform 10 does not fully expand during blow molding, preform 10 will not fully expand with respect to upper portion 48a of shoulder portion 48 during blow molding, which may result in poor moldability.

[0055] On the other hand, the large diameter portion 21 formed directly below the support ring 14 of the preform 10 is the portion that is gripped by a gripper (not shown) to transport the preform 10 during the blow molding process, and if it does not have the desired outer diameter, it is thought that the gripper will not be able to securely engage with the preform 10.

[0056] Furthermore, since the large diameter portion 21 is the portion that is gripped by the gripper, it is also necessary for it to have a desired thickness.

[0057] Therefore, in this embodiment, thin-walled portion 20A, which is the thinnest part of body portion 20, is provided in reduced diameter portion 22 adjacent to large diameter portion 21 provided directly below support ring 14. This allows preform 10 to be gripped without any problems during the blow molding process using preform 10. Furthermore, thin-walled portion 20A can be reliably stretched during the blow molding process, which allows shoulder portion 48 of plastic bottle 40, particularly upper portion 48a of shoulder portion 48, to be molded with high precision by blow molding.

[0058] Furthermore, since the average value of the thickness T1 of the large diameter portion 21 is less than or equal to the average value of the thickness T4 of the small diameter portion 23, the body portion 42, which accounts for the majority of the plastic bottle 40, can be reliably formed using the small diameter portion 23.

[0059] Furthermore, by providing the thin-walled portion 20A in the reduced diameter portion 22, the reduced diameter portion 22 can be stretched during blow molding, allowing the shoulder portion 48 of the plastic bottle 40, particularly the upper portion 48a of the shoulder portion 48, to be molded with high precision.

[0060] The thickness of the reduced diameter portion 22 will be described later.

[0061] Next, the material of the preform 10 will be described. It is preferable to use a thermoplastic resin, particularly PE (polyethylene), PP (polypropylene), PET (polyethylene terephthalate), or PEN (polyethylene naphthalate), as the main material of the preform 10. Plant-derived biomass plastics, such as PLA (polylactic acid), can also be used. Alternatively, a resin blend of the above-mentioned resins may be used. The preform 10 can also be formed as a multilayer preform having two or more layers. That is, the preform 10 may be formed by injection molding into a preform having three or more layers, with the intermediate layer being a resin (intermediate layer) having gas barrier properties, such as MXD6, MXD6 + fatty acid salt, PGA (polyglycolic acid), EVOH (ethylene vinyl alcohol copolymer), or PEN (polyethylene naphthalate).

[0062] The preform 10 may also contain virgin polyester or chemically recycled polyester (hereinafter simply referred to as virgin polyester). Herein, "virgin polyester" refers to polyester that has not been subjected to a recycling process, i.e., unused polyester. Also, in this specification, "chemically recycled polyester" refers to polyester obtained by decomposing a polyester container to the monomer level and repolymerizing it.

[0063] When preform 10 contains virgin polyester or the like, the content of virgin polyester or the like is preferably 20 parts by mass or more and 100 parts by mass or less, and more preferably 60 parts by mass or more and 90 parts by mass or less, relative to 100 parts by mass of the total amount of resin material contained in preform 10. When preform 10 contains virgin polyester, aluminum, titanium, or germanium is preferably used as a catalyst used in producing virgin polyester, and titanium can also be used.

[0064] When the preform 10 contains a chemically recycled polyester, the chemically recycled polyester may be selected from antimony-catalyzed polyester, manganese-catalyzed polyester, titanium-catalyzed polyester, aluminum-catalyzed polyester, lithium-catalyzed polyester, and germanium-catalyzed polyester. In this specification, for example, antimony-catalyzed polyester refers to a polyester produced using an antimony catalyst as a polymerization catalyst. Therefore, the polyesters listed above refer to polyesters produced using the respective catalysts as polymerization catalysts.

[0065] Examples of antimony catalysts include antimony trioxide, antimony pentoxide, antimony acetate, triphenylantimony, and antimony glycol.

[0066] Examples of the manganese catalyst include fatty acid manganese salts such as manganese acetate, manganese carbonate, manganese chloride, manganese acetylacetonate salts, and manganese hydroxide.

[0067] Examples of the titanium catalyst include titanium alkoxides such as tetra-n-propyl titanate, tetra-i-propyl titanate, tetra-n-butyl titanate, tetra-n-butyl titanate tetramer, tetra-t-butyl titanate, tetracyclohexyl titanate, tetraphenyl titanate, and tetrabenzyl titanate; titanium oxides obtained by hydrolysis of titanium alkoxides; titanium acetate, titanium oxalate, potassium titanium oxalate, sodium titanium oxalate, potassium titanate, sodium titanate, titanate-aluminum hydroxide mixtures, titanium chloride, titanium chloride-aluminum chloride mixtures, titanium bromide, titanium fluoride, potassium hexafluorotitanate, cobalt hexafluorotitanate, manganese hexafluorotitanate, ammonium hexafluorotitanate, and titanium acetylacetonate.

[0068] Examples of aluminum catalysts include aluminum trisacetylacetate, aluminum monoacetylacetonate bis(ethylacetoacetate), and ethylacetoacetate aluminum diisopropylate.

[0069] Examples of the lithium catalyst include ethyllithium, propyllithium, n-butyllithium, sec-butyllithium, tert-butyllithium, and phenyllithium.

[0070] Examples of germanium catalysts include germanium dioxide, germanium tetroxide, germanium tetramethoxide, germanium tetraethoxide, germanium tetrapropoxide, germanium tetrabutoxide, germanium tetrapentoxide, and germanium tetrahexoxide.

[0071] In this embodiment, the term "polyester" refers to a copolymer of a dicarboxylic acid compound and a diol compound.

[0072] Examples of dicarboxylic acid compounds include malonic acid, succinic acid, glutaric acid, adipic acid, suberic acid, sebacic acid, dodecanedioic acid, eicosanedioic acid, pimelic acid, azelaic acid, methylmalonic acid, ethylmalonic acid, adamantanedicarboxylic acid, norbornenedicarboxylic acid, cyclohexanedicarboxylic acid, decalindicarboxylic acid, terephthalic acid, isophthalic acid, phthalic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 1,8-naphthalenedicarboxylic acid, 4,4'-diphenyldicarboxylic acid, 4,4'-diphenyletherdicarboxylic acid, 5-sodiumsulfoisophthalic acid, phenylendanedicarboxylic acid, anthracenedicarboxylic acid, phenanthrenedicarboxylic acid, 9,9'-bis(4-carboxyphenyl)fluorene acid, and ester derivatives thereof.

[0073] Examples of diol compounds include ethylene glycol, 1,2-propanediol, 1,3-propanediol, butanediol, 2-methyl-1,3-propanediol, hexanediol, neopentyl glycol, cyclohexanedimethanol, cyclohexanediethanol, decahydronaphthalenedimethanol, decahydronaphthalenediethanol, norbornanedimethanol, norbornanediethanol, tricyclodecanedimethanol, tricyclodecaneethanol, tetracyclododecanedimethanol, tetracyclododecanediethanol, decalindimethanol, decalindiethanol, Examples include 5-methylol-5-ethyl-2-(1,1-dimethyl-2-hydroxyethyl)-1,3-dioxane, cyclohexanediol, bicyclohexyl-4,4'-diol, 2,2-bis(4-hydroxycyclohexylpropane), 2,2-bis(4-(2-hydroxyethoxy)cyclohexyl)propane, cyclopentanediol, 3-methyl-1,2-cyclopentadiol, 4-cyclopentene-1,3-diol, adamantanediol, paraxylene glycol, bisphenol A, bisphenol S, styrene glycol, trimethylolpropane, and pentaerythritol.

[0074] Among polyesters, polyethylene terephthalate, which is a copolymer of terephthalic acid and ethylene glycol, or modified polyethylene terephthalate in which a copolymerization monomer is added to this is preferred.

[0075] The polyester may be biomass-derived polyethylene terephthalate or fossil fuel-derived polyethylene terephthalate. The biomass-derived polyethylene terephthalate may be polyethylene terephthalate in which the dicarboxylic acid compound is terephthalic acid derived from fossil fuel and the diol compound is ethylene glycol derived from biomass. In this way, by including biomass-derived polyethylene terephthalate in the preform 10, the environmental impact of the plastic bottle 40 can be reduced.

[0076] The polyester may contain a monomer other than the dicarboxylic acid compound and the diol compound as long as the properties of the present embodiment are not impaired. However, the content of such a monomer is preferably 10 mol % or less, more preferably 5 mol % or less, and even more preferably 3 mol % or less, based on the total structural units.

[0077] The preform 10 may also contain mechanically recycled polyester. In this case, the environmental impact of the plastic bottle 40 can be reduced. In this specification, "mechanically recycled polyester" refers to polyester obtained by sorting, crushing, and washing polyester containers to remove contaminants and foreign matter, obtaining flakes, and then treating the flakes for a certain period of time at high temperature and reduced pressure to remove contaminants from within the resin. The mechanically recycled polyester may contain two or more catalysts. In this case, the mechanically recycled polyester may contain two or more of antimony-catalyzed polyester, manganese-catalyzed polyester, titanium-catalyzed polyester, aluminum-catalyzed polyester, lithium-catalyzed polyester, and germanium-catalyzed polyester, for example.

[0078] When preform 10 contains mechanically recycled polyester, the content of mechanically recycled polyester is preferably 20 parts by mass or more and 100 parts by mass or less, and more preferably 60 parts by mass or more and 90 parts by mass or less, relative to 100 parts by mass of the total amount of resin material contained in preform 10.

[0079] Preform 10 may contain additives, as long as they do not impair the properties of this embodiment, such as oxygen absorbers, gas barrier resins (polyamides such as nylon 6, nylon 6,6, and polymetaxylylene adipamide (MXD6)), plasticizers, UV stabilizers, antioxidants, color inhibitors, matting agents, deodorizers, flame retardants, weather resistance agents, antistatic agents, thread friction reducers, slip agents, mold release agents, antioxidants, ion exchange agents, acetaldehyde absorbers (e.g., AA Scavengers manufactured by Color Matrix), and colorants.

[0080] Next, an example of a plastic bottle produced by biaxially stretching blow molding such a preform 10 will be described with reference to Figure 3. Of course, the plastic bottle produced using the above-mentioned preform 10 is not limited to this. For example, the plastic bottle may be a petaloid bottle. Furthermore, the plastic bottle 40 may be produced by various molding methods such as direct blow molding in addition to biaxially stretching blow molding.

[0081] In Figure 3, a plastic bottle 40 has a mouth 41, a substantially cylindrical body 42, and a bottom 43. The body 42 is provided below and continuous with the mouth 41. The bottom 43 is provided below and continuous with the body 42. A neck 44 is located between the mouth 41 and the body 42. A shoulder 48 is located between the neck 44 and the body 42.

[0082] A threaded portion 46 for screwing on a cap (not shown) is provided on the outer periphery of the mouth portion 41. The threaded portion 46 corresponds to the threaded portion 13 of the preform 10 described above. An annular support ring 47 that protrudes outward is provided on the outer periphery of the mouth portion 41 below the threaded portion 46. The support ring 47 corresponds to the support ring 14 of the preform 10 described above.

[0083] As described above, the body 42 is substantially cylindrical. A plurality of horizontal grooves 45 are formed in the body 42. The horizontal cross section of the shoulder 48 is substantially circular, and the area of ​​the horizontal cross section of the shoulder 48 gradually increases from the neck 44 side toward the body 42 side.

[0084] A heel portion 49 is formed on the radially outer portion of the bottom portion 43. The heel portion 49 is provided in an annular shape over the entire circumferential area of ​​the bottom portion 43. The heel portion 49 roughly corresponds to the first boundary portion 26 of the preform 10 described above, and is the portion of the bottom portion 43 that is stretched to be the thinnest during blow molding.

[0085] The size of such a plastic bottle 40 is not limited, and a bottle of any size may be used. The full capacity of the plastic bottle 40 may be, for example, 100 ml or more, 200 ml or more, or 300 ml or more. The full capacity of the plastic bottle 40 may be, for example, 600 ml or less, 550 ml or less, or 530 ml or less.

[0086] Furthermore, the thickness of the heel portion 49 of the bottom portion 43 is not limited to this, but may be, for example, 0.07 mm or more, 0.08 mm or more, or 0.09 mm or more. The thickness of the heel portion 49 may be, for example, 0.30 mm or less, 0.25 mm or less, or 0.20 mm or less. By making the thickness of the heel portion 49 0.30 mm or less, the weight of the plastic bottle 40 can be reduced. On the other hand, by making the thickness of the heel portion 49 0.07 mm or more, it is possible to prevent the bottom portion 43 from popping out and becoming permanently deformed when the plastic bottle 40 is placed in a vending machine or dropped.

[0087] Next, the operation of this embodiment (a method for manufacturing a plastic bottle) configured as described above will be described.

[0088] First, preform 10 shown in FIGS. 1 and 2 is prepared (FIG. 4A). In this case, thermoplastic resin pellets such as PET (polyethylene terephthalate) are placed in an injection molding machine (not shown), which heats, melts, and pressurizes the pellets. The pellets then become pressurized molten plastic, which is injected into an injection mold having an internal shape corresponding to preform 10. After a predetermined time has passed, the molten plastic hardens within the injection mold, forming preform 10. The injection mold is then separated, and preform 10 shown in FIGS. 1 and 2 is removed from the injection mold. Note that preform 10 may be produced by various molding methods, such as compression molding, in addition to injection molding.

[0089] Next, the preform 10 is heated by the heating device 51 (FIG. 4B). At this time, the preform 10 is heated uniformly in the circumferential direction by the heating device 51 while rotating with the mouth portion 11 facing downward. The heating temperature of the preform 10 in the heating step may be, for example, 90°C to 130°C.

[0090] Subsequently, the preform 10 heated by the heating device 51 is sent to the blow molding die 50 (FIG. 4C).

[0091] The plastic bottle 40 is molded using a blow molding mold 50. In this case, the blow molding mold 50 includes a pair of body molds 50a, 50b that are separated from each other, and a bottom mold 50c (FIG. 4C). In FIG. 4C, the pair of body molds 50a, 50b are open from each other, and the bottom mold 50c is raised. In this state, the preform 10 is inserted between the pair of body molds 50a, 50b.

[0092] 4D, after the bottom mold 50c is lowered, the pair of body molds 50a, 50b are closed, and the pair of body molds 50a, 50b and the bottom mold 50c form a sealed blow molding mold 50. Next, air is forced into the preform 10, and the preform 10 is subjected to biaxial stretch blow molding.

[0093] As a result, a plastic bottle 40 is obtained from the preform 10 in the blow molding mold 50. During this process, the body molds 50a, 50b are heated to 30°C to 80°C, and the bottom mold 50c is cooled to 5°C to 25°C. During this process, the preform 10 is expanded in the blow molding mold 50 and shaped into a shape corresponding to the inner surface of the blow molding mold 50.

[0094] Thereafter, as shown in Fig. 4E, the pair of body molds 50a, 50b and the bottom mold 50c are separated from each other, and the plastic bottle 40 is removed from the blow molding mold 50. In this way, the plastic bottle 40 shown in Fig. 3 is obtained.

[0095] The heel portion 49 (see FIG. 3) of the plastic bottle 40 corresponds to the periphery of the bottom portion 30 of the preform 10 (see FIGS. 1 and 2A), and is a portion that is likely to become thin after blow molding. That is, the periphery of the bottom portion 30 of the preform 10 is significantly stretched in both the direction of the central axis CL and the radial direction, so the heel portion 49 of the plastic bottle 40 is likely to become thinner than other portions. In this case, a defect known as whitening may occur in the heel portion 49, and the strength of the heel portion 49 may be reduced.

[0096] In contrast, according to the present embodiment, the thinnest portion of the body portion 20 and bottom portion 30 of the preform 10 is preferably the lowest portion 31 of the bottom portion 30. Furthermore, when the thickness of the lowest portion 31 of the bottom portion 30 is T7 and the thickness of the large diameter portion is T1, it is preferable that 0.80≦T7 / T1≦0.95 be satisfied. By satisfying 0.80≦T7 / T1, even when the mass of the preform 10 is reduced, the heel portion 49 of the plastic bottle 40 does not become too thin, thereby preventing whitening of the heel portion 49 and a decrease in the strength of the heel portion 49. In particular, because the heel portion 49 can be prevented from becoming thin without increasing the mass of the plastic bottle 40, the weight reduction of the plastic bottle 40 is not hindered. Since the relationship T7 / T1≦0.95 is established between the thickness T7 of the lowest part 31 of the bottom part 30 and the thickness T1 of the large diameter part, by reducing the thickness of the bottom part 30 of the preform 10, which is less likely to be stretched when molding the plastic bottle 40, it is possible to increase the thickness of the body part 42 and heel part 49, which are stretched, even for preforms 10 of the same weight. This allows the weight of the preform 10 to be reduced.

[0097] Furthermore, according to this embodiment, when the mass of the mouth portion is W1 and the total mass of the body portion 20 and bottom portion 30 is W2, the relationship 1.80≦W2 / W1≦2.70 holds. By satisfying 1.80≦W2 / W1, the amount of resin in the body portion 20 and bottom portion 30 is not excessively reduced. This prevents the plastic bottle 40 from being overstretched in the longitudinal direction when being molded. This prevents a defect known as whitening from occurring in the heel portion 49 of the plastic bottle 40 and a decrease in the strength of the heel portion 49. By satisfying W2 / W1≦2.70 between the mass W1 of the mouth portion and the total mass W2 of the body portion 20 and bottom portion 30, the mass of the preform 10 is prevented from becoming too heavy.

[0098] Furthermore, according to this embodiment, when the total length of the body portion 20 and the bottom portion 30 is L6, the relationship is 73.0 mm≦L6≦84.0 mm. By satisfying 73.0 mm≦L6, the longitudinal stretching ratio during molding of the plastic bottle 40 is not too large, preventing overstretching. This prevents a defect known as whitening from occurring in the heel portion 49 of the plastic bottle 40 and a decrease in the strength of the heel portion 49. Furthermore, by satisfying L6≦84.0 mm, when the mass of the preform 10 is constant, the total length L6 is reduced, making it difficult for the thickness of the body portion 20 to become thin. This prevents whitening of the body portion 42 during molding of the plastic bottle 40. Furthermore, since the total length L6 of the preform 10 is not too long, it is possible to prevent the longitudinal stretching from becoming too small or even from occurring at all. This allows the plastic bottle 40 to be easily molded, even if it is a small, low-profile bottle with a capacity of approximately 100 mL.

[0099] Furthermore, as described above, by setting the ratio (W2 / W1) of the total mass W2 of the body portion 20 and the bottom portion 30 to the mass W1 of the mouth portion 11 to 1.80 or more, excessive lateral stretching of the preform 1 can be suppressed. [Example]

[0100] Next, a specific example 1 of this embodiment will be described with reference to Figures 5A to 7. In the specific example 1, the mouth portion 11 of the preform 10 was subjected to differential scanning calorimetry (DSC).

[0101] In Example 1, a preform 10 having the configuration shown in Figures 1 and 2 was first produced. The mouth portion 11 of this preform 10 was made of amorphous PET (polyethylene terephthalate). The weight of this preform 10 was 23.4 g.

[0102] The outer diameter D1 of the mouth body 12 of the mouth 11 is 24.94 mm, and the inner diameter D2 is 20.60 mm.

[0103] Therefore, the thickness of the mouth body 12 is 2.17 mm.

[0104] The threaded portion 13 provided on the outer periphery of the mouth body 12 of the mouth 11 extends continuously in a spiral shape along the circumferential direction without having any cut portions for air vents.

[0105] DSC was performed on the mouth portion 11 of the preform 10 according to Example 1 of this embodiment.

[0106] The DSC measurement conditions are as follows (see FIG. 6). <Measurement conditions> Measurement equipment: Differential scanning calorimeter DSC8500 (PerkinElmer) Pretreatment: 40℃ x 12 hours vacuum drying Measurement temperature range: 30°C → 300°C (hold for 10 minutes) → 30°C (hold for 1 minute) → 300°C ·First heating rate: 10℃ / min ·First cooling rate: 10℃ / min ·Second heating rate: 10℃ / min Measurement atmosphere: Nitrogen atmosphere Sample weight: approx. 10 mg Sample container: Hermetic Pan (TA) <Measurement results> The results of DSC measurement are shown in Fig. 7. As shown in Fig. 7, the neck portion 11 of the present embodiment is amorphous, and the heat of crystallization during the first temperature decrease after the first temperature increase, obtained by DSC of the neck portion 11, was 42.1 J / g. Also, the heat of fusion during the second temperature increase, obtained by DSC of the neck portion 11, was 42.0 J / g.

[0107] The ratio of the outer diameter D1 to the inner diameter D2 of the mouth body 12 of the mouth 11, D2 / D1, was found to be D2 / D1=0.826.

[0108] It was confirmed that when the mouth body 12D2 / D1 was changed from 0.80 to 0.85, the heat of crystallization during the first cooling was 40.0 J / g or more and 43.0 J / g or less.

[0109] Furthermore, when D2 / D1 was changed from 0.80 to 0.85, it was confirmed that the heat of fusion during the second heating was 41.0 J / g or more and 44.0 J / g or less. <Comparative Examples 1 and 2> Next, a mouth portion 11 as shown in Fig. 5B was prepared as Comparative Example 1. As shown in Fig. 5B, the outer diameter D1 of the mouth portion body 12 of the mouth portion 11 was 24.94 mm, the inner diameter D2 was 21.74 mm, and the thickness of the mouth portion body 12 was 1.6 mm.

[0110] The threaded portion 13 on the outer periphery of the mouth body 12 extends spirally in the circumferential direction. Furthermore, a cut portion 13A for an air vent that extends in the height direction is formed on the threaded portion 13. Comparative Example 1 is made of amorphous PET.

[0111] Furthermore, as Comparative Example 2, a mouth portion 11 identical to that of Comparative Example 1 was prepared, except that it was made of crystallized PET.

[0112] Next, Comparative Example 1 and Comparative Example 2 were subjected to DSC under the same DSC measurement conditions as in Example 1.

[0113] The DSC measurement results for Comparative Example 1 and Comparative Example 2 are shown in FIG.

[0114] 7, the neck portion 11 of Comparative Example 1 was amorphous, and the heat of crystallization during the first cooling after the first heating, as obtained by DSC of the neck portion 11, was 39.1 J / g. The heat of fusion during the second heating, as obtained by DSC of the neck portion 11 of Comparative Example 1, was 40.1 J / g.

[0115] The ratio D2 / D1 between the outer diameter D1 and the inner diameter D2 of the mouth body 12 of the mouth 11 of Comparative Example 1 was found to be D2 / D1=0.872.

[0116] 7, the neck portion 11 of Comparative Example 2 was crystallized, and the heat of crystallization during the first cooling after the first heating, as measured by DSC of the neck portion 11, was 43.6 J / g. The heat of fusion during the second heating, as measured by DSC of the neck portion 11 of Comparative Example 2, was 44.6 J / g.

[0117] The ratio D2 / D1 between the outer diameter D1 and the inner diameter D2 of the mouth body 12 of the mouth 11 of Comparative Example 2 was found to be D2 / D1=0.872. <Concept> Considering the above points, as shown in Figure 7, the mouth portion 11 in Example 1 of this embodiment is made of uncrystallized PET, but the heat of crystallization during the first temperature decrease and the heat of fusion during the second temperature increase of the mouth portion 11 both showed results that were closer to those of the mouth portion 11 in Comparative Example 2 made of crystallized PET than those of the mouth portion 11 in Comparative Example 1.

[0118] The reason why the neck portion 11 of Example 1 of this embodiment exhibits results similar to those of the crystallized neck portion 11 of Comparative Example 2 in terms of the heat of crystallization during the first cooling and the heat of fusion during the second heating is believed to be that the thickness of the neck portion body 12 of the neck portion 11 in Example 1 was greater than that of the neck portion body 12 of Comparative Example 1, thereby improving the heat resistance of the neck portion 11. In Comparative Example 1, D2 / D1 = 0.872, and as described above, the heat of crystallization during the first cooling and the heat of fusion during the second heating of the neck portion 11 are inferior to those of Example 1. However, if D2 / D1 = 0.80 to 0.90, there is no problem with the heat of crystallization during the first cooling and the heat of fusion during the second heating of the neck portion 11. This point will be discussed further below.

[0119] Furthermore, the threaded portion 13 formed on the mouth body 12 of the mouth 11 of Example 1 does not have a cut portion for an air vent and extends continuously in a spiral. Therefore, even when high-temperature liquid contents (e.g., liquid contents at 70°C to 90°C) are filled into the plastic bottle 40 through the mouth 41, the mouth 41 undergoes uniform thermal deformation along the circumferential direction, and the mouth 41 does not undergo uneven thermal deformation. This prevents leakage of the liquid contents from between the mouth 41 and the cap 60. In contrast, in Comparative Example 1, the threaded portion 13 provided on the outer periphery of the mouth body 12 extends spirally along the circumferential direction, and furthermore, the threaded portion 13 is formed with a cut portion 13A for an air vent that extends in the height direction. Therefore, the continuity of the threaded portion 13 along the circumferential direction is interrupted by the cut portion 13A. As a result, when plastic bottle 40 is filled with high-temperature liquid contents (e.g., liquid contents at 70°C to 90°C) through mouth 41, the heat of crystallization during the first temperature drop of mouth 11 and the heat of fusion during the second temperature rise are reduced, causing mouth 41 to thermally deform unevenly along the circumferential direction. [Example]

[0120] Next, a second specific example of this embodiment will be described with reference to FIGS.

[0121] In Example 2, a preform 10 made of PET (polyethylene terephthalate) and having the structure shown in FIGS. 1 and 2 was produced.

[0122] The weight of this preform 10 was 23.4 g.

[0123] The outer diameter D3 of the large diameter portion 21 of the preform 10 was 25.65 mm.

[0124] Furthermore, the thickness T1 of the large diameter portion 21, the thickness T2 of the reduced diameter portion 22, and the thickness T4 of the small diameter portion 23 of the preform 10 changed according to the distance from the support ring, as shown in FIGS.

[0125] That is, as shown in Figures 8 and 9, in the large diameter portion 21 of the preform 10, its thickness T1 was constant until it was about 2 mm away from the support ring 14, and then the thickness T1 gradually decreased to the third boundary portion 28.

[0126] Thereafter, thickness T2 of reduced diameter portion 22 further decreases with increasing distance from support ring 14, and thickness T2 reaches its minimum value at thin-walled portion 20A of reduced diameter portion 22.

[0127] That is, thin-walled portion 20A of reduced diameter portion 22 is the thinnest portion of trunk portion 20 that extends in the circumferential direction of trunk portion 20. Thin-walled portion 20A of reduced diameter portion 22 is thinner than adjacent portions above and below in the height direction of preform 10. Thin-walled portion 20A of reduced diameter portion 22 will be described further below.

[0128] In Example 2, the length L3 of the reduced diameter portion 22 and the length L from the third boundary portion 28 between the large diameter portion 21 and the reduced diameter portion 22 to the thin-walled portion 20A are 10 The relationship between 10 / L3=30%~50%.

[0129] The thickness T2 of the reduced diameter portion 22 has a descending portion 20A1 that gradually descends from the third boundary portion 28 between the large diameter portion 21 and the reduced diameter portion 22 to the thin-walled portion 20A, and an ascending portion 20A2 that gradually increases from the thin-walled portion 20A toward the second boundary portion 27 between the reduced diameter portion 22 and the small diameter portion 23, and the thickness T2 of the reduced diameter portion 22 is greatest near the second boundary portion 27.

[0130] Thereafter, the thickness T4 from the second boundary portion 27 to the small diameter portion 23 was constant throughout the small diameter portion 23.

[0131] As described above, the distribution of thickness T2 of reduced diameter portion 22 forms a V-shape having a descending portion 20A1 that descends from the third boundary portion 28 between large diameter portion 21 and reduced diameter portion 22 to thin-walled portion 20A, and an ascending portion 20A2 that ascends from thin-walled portion 20A to the second boundary portion 27 between reduced diameter portion 22 and small diameter portion 23.

[0132] The thickness T1 of the large diameter portion 21 and the thickness T4 of the small diameter portion 23 are The relationship was such that the average value of the thickness T1 of the large diameter portion 21≦the average value of the thickness T4 of the small diameter portion 23.

[0133] As described above, according to this embodiment, the thin-walled portion 20A, which is the thinnest part of the body portion 20, is provided in the reduced diameter portion 22 adjacent to the large diameter portion 21 provided directly below the support ring 14. This allows the preform 10 to be gripped by the gripper without any problems during the blow molding process using the preform 10. Furthermore, the thin-walled portion 20A can be reliably stretched during the blow molding process, allowing the shoulder portion 48 of the plastic bottle 40 to be formed with high precision by blow molding (see FIG. 3).

[0134] Furthermore, since the average value of the thickness T1 of the large diameter portion 21 is less than or equal to the average value of the thickness T4 of the small diameter portion 23, the body portion 42, which accounts for the majority of the plastic bottle 40, was reliably formed using the small diameter portion 23.

[0135] Furthermore, by providing the thin-walled portion 20A in the reduced diameter portion 22, as described above, the reduced diameter portion 22 can be stretched during blow molding, thereby enabling the shoulder portion 48 of the plastic bottle 40, particularly the upper portion 48a of the shoulder portion 48, to be molded with high precision.

[0136] The thickness T2 of the reduced diameter portion 22 has a V-shaped distribution including a descending portion 20A1 descending from the large diameter portion 21 to the thin portion 20A and an ascending portion 20A2 ascending from the thin portion 20A to the small diameter portion .

[0137] In particular, the V-shape that forms the distribution of thickness T2 of reduced diameter portion 22 extends from third boundary 28 between large diameter portion 21 and reduced diameter portion 22 to second boundary 27 between reduced diameter portion 22 and small diameter portion 23. Therefore, in the blow molding process, it is possible to gradually and balancedly stretch descending portion 20A1 of reduced diameter portion 22, which begins at thin-wall portion 20A, which is also the smallest point of the V-shape, and extends from thin-wall portion 20A to third boundary 28. Similarly, it is possible to gradually and balancedly stretch ascending portion 20A2, which begins at thin-wall portion 20A and extends from thin-wall portion 20A to second boundary 27.

[0138] In this way, in the blow molding process, descending portion 20A1 and ascending portion 20A2 can be gradually stretched in reduced diameter portion 22, starting from thin-walled portion 20A, which is the smallest point of the V-shape. As a result, the thickness distribution of reduced diameter portion 22 has a V-shape that extends from third boundary portion 28 to the entire second boundary portion 27, so that the entire reduced diameter portion 22 can be stretched smoothly and reliably, thereby enabling shoulder portion 48 of plastic bottle 40, particularly upper portion 48a of shoulder portion 48, to be molded with high precision.

[0139] The length L3 of the reduced diameter portion 22 and the length L from the third boundary portion 28 between the large diameter portion 21 and the reduced diameter portion 22 to the thin-walled portion 20A are 10 The relationship with L 10Since / L3=30% to 50%, the thin-walled portion 20A can be located closer to the large-diameter portion 21 in the reduced-diameter portion 22. This allows the reduced-diameter portion 22 to be stretched from the thin-walled portion 20A located on the large-diameter portion 21 side, thereby enabling the upper portion 48a of the shoulder portion 48 of the plastic bottle 40 to be molded with high precision. [Explanation of symbols]

[0140] 10 Preform 11 Mouth 12 Mouth body 13 Threaded section 14 Support ring 15 Opening 20 Torso 20A thin section 20A1 descending section 20A2 ascending section 21 Large diameter section 22 Reduced diameter part 23 Small diameter section 26 First Boundary 27 Second Boundary 28 Third Boundary 30 bottom 31 Bottom 40 plastic bottles

Claims

1. a cylindrical mouth portion having a mouth portion body and a threaded portion provided on the outer periphery of the mouth portion body; a cylindrical body portion connected to the mouth portion; a bottom connected to the body, The outer diameter of the mouth body of the mouth is D1, When the inner diameter of the mouth body is D2, D2 / D1 = 0.80 to 0.90, The preform has a threaded portion that extends continuously along the circumferential direction without any cut portions for air vents.

2. The preform according to claim 1, wherein the mouth portion is amorphous, and the heat of crystallization during the first temperature decrease after the first temperature increase, as measured by differential scanning calorimetry, is 40.0 J / g or more and 43.0 J / g or less.

3. 3. The preform according to claim 2, wherein the mouth portion is amorphous and the heat of fusion during the second heating step, as measured by differential scanning calorimetry, is 41.0 J / g or more and 44.0 J / g or less.

4. A plastic bottle including a cylindrical mouth having a mouth body and a threaded portion provided on the outer periphery of the mouth body, The outer diameter of the mouth body of the mouth is D1, When the inner diameter of the mouth body is D2, D2 / D1 = 0.80 to 0.90, A plastic bottle, wherein the threaded portion extends continuously along the circumferential direction without any cut portions for air vents.

5. 5. The plastic bottle according to claim 4, wherein the mouth portion is amorphous, and the heat of crystallization during the first temperature decrease after the first temperature increase, as measured by differential scanning calorimetry, is 40.0 J / g or more and 43.0 J / g or less.

6. 6. The plastic bottle according to claim 5, wherein the mouth portion is amorphous and the heat of fusion during the second heating step, as determined by differential scanning calorimetry, is 41.0 J / g or more and 44.0 J / g or less.

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