JP7336085B1 - Plastic bottle, blow mold and method for manufacturing plastic bottle - Google Patents

Abstract

A plastic bottle, a blow molding die, and a method for manufacturing a plastic bottle are provided, which can suppress a phenomenon in which the bottom portion of the bottle is inverted and pops out.
A bottom portion (50) of a plastic bottle (10) includes a peripheral edge portion (51) located at the peripheral edge of the bottom portion (50), a ground portion (52) located radially inward of the peripheral edge portion (51), and a ground portion (52) located radially inward of the ground portion (52). and a central portion 53 located at the . The ground portion 52 includes an annular flat ground surface 52a. The central portion 53 is connected to a first wall surface 55a connected to the ground surface 52a, a second wall surface 56a connected to the first wall surface 55a and inclined with respect to the first wall surface 55a, and a second wall surface 56a. bottom surface 57a. A convex portion 58 is formed on the bottom surface 57a so as to protrude downward.
[Selection drawing] Fig. 4

Description

The present disclosure relates to plastic bottles, blow molds and methods of making plastic bottles.

In recent years, plastic containers have become popular as containers for containing contents such as food and drink (for example, Patent Document 1).

Such plastic bottles include plastic bottles that are sold in a heated state. Heating plastic bottles are sold in a bottle warmer. In a bottle warmer, filled plastic bottles are placed on a shelf heated by a heater. Then, the contents are usually heated so that the temperature of the contents is about 55° C. or more and 60° C. or less.

JP 2016-210516 A

However, if the temperature of the heater is set incorrectly, the plastic bottle may be heated to a higher temperature than expected. Also, there is a risk that the plastic bottle will be heated to a temperature higher than expected due to a temporary change in temperature. Thus, when the plastic bottle is heated to a temperature higher than expected, the pressure inside the plastic bottle becomes higher than expected, and the bottom of the plastic bottle may deform. In addition, if the plastic bottle is heated to a temperature higher than expected, the plastic may soften due to the heat, or the plastic may crystallize, thereby deforming the bottom of the plastic bottle. Then, due to deformation of the bottom of the plastic bottle, there is a risk that the bottom will turn over and pop out (buckling).

The present disclosure has been made in consideration of such points, and an object thereof is to provide a plastic bottle, a blow mold, and a method for manufacturing a plastic bottle that can suppress the phenomenon that the bottom part is inverted and pops out. and

A first aspect of the present disclosure is a plastic bottle comprising a mouth portion, a body portion, and a bottom portion, wherein the bottom portion has a peripheral edge portion located at the peripheral edge of the bottom portion and a radial direction larger than the peripheral edge portion. an inwardly positioned ground contact portion and a central portion positioned radially inwardly of the contact portion, the contact portion including an annular flat contact surface, the central contact portion being adjacent to the contact surface; a first wall surface connected to the first wall surface, a second wall surface connected to the first wall surface and inclined with respect to the first wall surface, and a bottom surface connected to the second wall surface; It is a plastic bottle formed with a projection projecting downward.

A second aspect of the present disclosure is the plastic bottle according to the first aspect described above, wherein the convex portion may be formed in an annular shape.

A third aspect of the present disclosure is the plastic bottle according to the first aspect or the second aspect described above, wherein the inclination angle of the first wall surface with respect to the central axis of the plastic bottle is 30° or more and 75° or less. It can be.

A fourth aspect of the present disclosure is the plastic bottle according to each of the first aspect to the third aspect described above, wherein the inclination angle of the second wall surface with respect to the central axis of the plastic bottle is 0.5° or more. It may be 20° or less.

A fifth aspect of the present disclosure is the plastic bottle according to each of the above-described first to third aspects, wherein the first wall surface may be a curved surface.

According to a sixth aspect of the present disclosure, in the plastic bottle according to the fourth aspect described above, the radius of curvature of the first wall surface may be 8 mm or more.

A seventh aspect of the present disclosure is the plastic bottle according to each of the above-described first to sixth aspects, wherein the second wall surface may be formed with a plurality of vertically extending ribs.

An eighth aspect of the present disclosure is a blow mold for blow molding a plastic bottle comprising a mouth, a body and a bottom, the body mold corresponding to the body of the plastic bottle. and a bottom mold corresponding to the bottom of the plastic bottle, wherein the bottom mold is located radially inward of the first side surface and the first side surface and is inclined with respect to the first side surface. and a top surface connected to the second side surface, wherein the top surface is formed with a concave portion recessed downward.

A ninth aspect of the present disclosure is the blow molding die according to the eighth aspect described above, wherein the concave portion may be formed in an annular shape.

A tenth aspect of the present disclosure is the blow molding die according to the above-described eighth aspect or the above-described ninth aspect, wherein the inclination angle of the first side surface with respect to the central axis of the plastic bottle is 30° or more and 75° or less. can be

An eleventh aspect of the present disclosure is the blow molding mold according to each of the eighth aspect to the tenth aspect described above, wherein the inclination angle of the second side surface with respect to the central axis of the plastic bottle is 0.5° It may be more than or equal to 20° or less.

A twelfth aspect of the present disclosure is the blow mold according to each of the eighth aspect to the tenth aspect described above, wherein the first side surface may be a curved surface.

According to a thirteenth aspect of the present disclosure, in the blow molding die according to the twelfth aspect described above, the radius of curvature of the first side surface may be 8 mm or more.

A fourteenth aspect of the present disclosure is the blow molding die according to each of the eighth aspect to the thirteenth aspect described above, wherein a plurality of vertically extending ribs may be formed on the second side surface. .

A fifteenth aspect of the present disclosure is a method of manufacturing a plastic bottle comprising the steps of providing a preform and providing a blow mold according to each of the eighth aspect to the fourteenth aspect above. and blow molding the preform in the blow mold.

Advantageous Effects of Invention According to the present disclosure, it is possible to suppress the phenomenon that the bottom portion is inverted and pops out.

FIG. 1 is a front view showing a plastic bottle according to one embodiment. FIG. 2 is a perspective view showing the plastic bottle according to one embodiment from below. FIG. 3 is a bottom view of a plastic bottle according to one embodiment. FIG. 4 is a cross-sectional view (cross-sectional view taken along line IV-IV in FIG. 3) showing a plastic bottle according to one embodiment. 5(a)-(b) are cross-sectional views showing a method of manufacturing a plastic bottle according to one embodiment. FIG. 6 is a cross-sectional view showing the bottom mold of the blow mold according to one embodiment. 7(a)-(b) are cross-sectional views showing a method of manufacturing a plastic bottle according to one embodiment. FIG. 8 is a diagram explaining the action of the plastic bottle according to one embodiment. FIG. 9 is a diagram explaining the action of the plastic bottle according to one embodiment. FIG. 10 is a diagram illustrating the action of a plastic bottle as a comparative example. FIG. 11A is a perspective view showing the plastic bottle according to the first modified example from below. FIG. 11B is a cross-sectional view showing a plastic bottle according to the first modified example. FIG. 12 is a cross-sectional view showing a blow mold according to a first modified example. FIG. 13 is a cross-sectional view showing a plastic bottle according to a second modified example. FIG. 14 is a cross-sectional view showing a blow mold according to a second modified example. FIG. 15 is a cross-sectional view showing a plastic bottle according to a third modified example. FIG. 16 is a perspective view showing a blow mold according to a third modified example. FIG. 17 is a cross-sectional view showing a blow mold according to a fourth modified example. FIG. 18 is a cross-sectional view showing a blow mold according to a fifth modification. 19 is a cross-sectional view showing a plastic bottle according to Comparative Example 1. FIG. 20 is a cross-sectional view showing a plastic bottle according to Comparative Example 2. FIG.

An embodiment of the present disclosure will be described below with reference to the drawings. 1 to 10 are diagrams showing an embodiment of the present disclosure. Each figure shown below is a figure shown typically. Therefore, the size and shape of each part are appropriately exaggerated for easy understanding. In addition, it can be modified as appropriate without departing from the technical idea. In addition, in each figure shown below, the same code|symbol is attached|subjected to the same part and detailed description may be partially abbreviate|omitted. In addition, numerical values such as dimensions and material names of each member described in this specification are examples as an embodiment, and can be appropriately selected and used without being limited thereto. In this specification, terms specifying shapes and geometrical conditions, such as parallel, orthogonal, and perpendicular terms, are interpreted to include substantially the same state in addition to strictly meaning.

Structure of Plastic Bottle First, a plastic bottle 10 according to the present embodiment will be described with reference to FIGS. 1 to 4. FIG. In this specification, the terms "upper" and "lower" respectively refer to the upper and lower sides when the plastic bottle 10 is erected (FIG. 1). In this specification, the “center axis CL” of the plastic bottle 10 refers to the center axis of the cylinder forming the inner surface of the mouth portion 20 of the plastic bottle 10 . The center axis CL of the plastic bottle 10 is a straight line orthogonal to a plane that becomes a ground plane when the plastic bottle 10 is grounded in an upright state.

Further, in this specification, "height direction" refers to a direction along the central axis CL of the plastic bottle 10, and "radial direction" refers to a direction orthogonal to the central axis CL of the plastic bottle 10. . Also, the “circumferential direction” refers to the circumferential direction of a circle centered on the central axis CL of the plastic bottle 10 .

The plastic bottle 10 shown in FIGS. 1 to 4 is produced by preparing a preform 100 obtained by injection molding (see FIG. 5) and subjecting this preform 100 to biaxial stretch blow molding.

As shown in FIG. 1, the plastic bottle 10 includes a mouth portion 20, a neck portion 21 positioned below the mouth portion 20, a shoulder portion 22 positioned below the neck portion 21, and a body portion positioned below the shoulder portion 22. It has a portion 30 and a bottom portion 50 located below the body portion 30 .

Of these, the mouth portion 20 has a threaded portion 23 to be screwed onto a cap (not shown) and a flange portion 24 positioned below the threaded portion 23 . By filling the plastic bottle 10 with a content such as a content liquid and screwing a cap onto the mouth portion 20, a content-filled plastic bottle 10A (see FIG. 8) is obtained.

The neck portion 21 is positioned between the flange portion 24 and the shoulder portion 22 and has a substantially cylindrical shape with a substantially uniform diameter.

The shoulder portion 22 is positioned between the neck portion 21 and the body portion 30 and has a shape whose diameter gradually increases from the neck portion 21 side toward the body portion 30 side.

The body portion 30 has a cylindrical shape with a substantially uniform diameter as a whole. However, the shape is not limited to this, and the trunk portion 30 may have a polygonal tubular shape such as a quadrangular tubular shape or an octagonal tubular shape. Alternatively, the body 30 may have a cylindrical shape with a non-uniform horizontal cross-section from top to bottom. The outer surface of the body portion 30 may be formed with, for example, a vacuum absorbing panel or grooves or other irregularities.

Next, the bottom portion 50 will be described with reference to FIGS. 2 to 4. FIG.

As shown in FIGS. 2 to 4 , the bottom portion 50 includes a peripheral edge portion 51 located at the peripheral edge of the bottom portion 50 , a ground contact portion 52 located radially inward of the peripheral edge portion, and a ground contact portion 52 located radially inward of the ground portion 52 . It has a central portion 53 located on the side. Among them, the grounding portion 52 includes an annular flat grounding surface 52a. Further, the central portion 53 includes a first wall surface 55a connected to the ground surface 52a, a second wall surface 56a connected to the first wall surface 55a and inclined with respect to the first wall surface 55a, and a second wall surface 56a connected to the first wall surface 55a. and a connected bottom surface 57a. A curved surface (not shown) may be interposed between the ground surface 52a and the first wall surface 55a. Here, first, the peripheral portion 51 of the bottom portion 50 will be described.

The peripheral edge portion 51 is positioned radially outward of the ground portion 52 . A radially inner end of the peripheral portion 51 is connected to a radially outer end of the ground portion 52 , and a radially outer end of the peripheral portion 51 is connected to the lower end of the body portion 30 . The peripheral portion 51 has an annular shape when viewed from the bottom direction. The peripheral edge portion 51 rises from below (the side of the ground contact portion 52) to above (the side of the body portion 30) as it goes from the radially inner side to the radially outer side (see FIG. 4). Further, in a vertical cross section (a cross section passing through the center axis CL) of the bottom portion 50, the peripheral edge portion 51 gradually forms an angle with respect to a ground contact surface 52a, which will be described later, of the ground contact portion 52 as it goes radially outward from the radially inner side. It may be curved so as to be large. A groove or the like is not formed in the peripheral portion 51 .

The ground portion 52 is a portion that contacts a mounting surface such as a table when the plastic bottle 10 is erected. The radially outer end of the grounding portion 52 is connected to the lower end of the peripheral portion 51 , and the radially inner end of the grounding portion 52 is connected to the lower end of the central portion 53 . As described above, the ground portion 52 includes an annular flat ground surface 52a. The ground contact surface 52a has an annular shape with no discontinuous portion in the circumferential direction (see FIG. 3). A groove or the like is not formed in the ground portion 52 . The width W1 (radial distance, see FIG. 3) of the grounding portion 52 may be greater than 0 mm and 10 mm or less, preferably 1 mm or more and 4 mm or less. Note that the ground portion 52 may be in line contact with the mounting surface of the table or the like. In addition, the inner periphery of the grounding portion 52 (the outer periphery of the annular inclined portion 55 described later) has a circular shape when viewed from the bottom surface direction, but is not limited to this, and may have, for example, a polygonal shape. good. Furthermore, W1 may partially differ in size.

Also, the thickness of the ground portion 52 is not limited to this, but can be set to, for example, 0.09 mm or more and 0.40 mm or less. When the thickness of the ground portion 52 is 0.09 mm or more, it is possible to prevent the plastic bottle 10 from turning white due to overstretching when the plastic bottle 10 is blow-molded. Further, since the thickness of the ground portion 52 is 0.40 mm or less, the weight of the plastic bottle 10 can be reduced. The reason why the plastic bottle 10 becomes white is that the overstretching in the blow molding causes fine irregularities on the surface of the plastic bottle 10, which diffusely reflect light.

The central portion 53 has a central recess 54 and an annular inclined portion 55 located around the central recess 54 .

The central recessed portion 54 is recessed upward (toward the inside of the plastic bottle 10). The central recessed portion 54 has a generally truncated cone shape as a whole and includes the above-described second wall surface 56a and a bottom surface 57a. The second wall surface 56a is positioned around the bottom surface 57a.

The second wall surface 56a has a substantially conical shape and extends linearly in a vertical cross section of the bottom portion 50 (a cross section passing through the central axis CL). Also, the second wall surface 56a is inclined with respect to the ground surface 52a in the vertical cross section of the bottom portion 50 . The inclination angle θ1 (see FIG. 4) of the second wall surface 56a with respect to the central axis CL of the plastic bottle 10 is preferably 0.5° or more and 20° or less. By setting the inclination angle θ1 to 0.5° or more, it is possible to improve releasability when removing the plastic bottle 10 from a blow molding die 70 to be described later. In addition, since the inclination angle θ1 is 20° or less, it is possible to effectively suppress the deformation of the central recessed portion 54 when the pressure inside the plastic bottle 10A with content increases. No groove or the like is formed in the second wall surface 56a.

No groove or the like is formed on the bottom surface 57a except for a projection 58, which will be described later. Therefore, portions of the bottom surface 57a other than the protrusions 58, which will be described later, are flat surfaces. Although the bottom surface 57a has a circular shape when viewed from the bottom surface direction, the bottom surface 57a is not limited to this and may have, for example, a polygonal shape. The diameter D2 (see FIG. 4) of the bottom surface 57a may be 20% or more and 50% or less, preferably 25% or more and 40% or less, of the maximum diameter D1 of the body portion 30. FIG. Also, the diameter D2 may be 18 mm or more and 30 mm or less. By setting the diameter D2 to be 18 mm or more, it is possible to suppress the extension of the insufficiently stretched portion, which will be described later, to the portion that constitutes the second wall surface 56a. Moreover, since the diameter D2 is 30 mm or less, the degree of freedom in designing the first wall surface 55a can be increased.

Also, the height H2 (see FIG. 4) from the ground contact surface 52a to the bottom surface 57a may be 20% or more and 40% or less, preferably 25% or more and 35% or less, of the maximum diameter D1 of the trunk portion 30. Furthermore, the height H2 from the ground surface 52a to the bottom surface 57a may be 16 mm or more and 25 mm or less. When the plastic bottle 10 is blow-molded, the height H2 of 16 mm or more allows the resin of the portions forming the annular inclined portion 55 and the second wall surface 56a to be sufficiently stretched. Therefore, the heat resistance of the portion can be improved. Moreover, since the height H2 is 25 mm or less, it is possible to prevent the plastic bottle 10 from turning white due to overstretching when the plastic bottle 10 is blow-molded.

Here, the portion forming the bottom surface 57 a is thicker than the other portions of the bottom portion 50 . That is, as will be described later, the bottom of the preform 100 (see FIG. 5(a)) has a portion that is difficult to stretch during blow molding (hereinafter simply referred to as an insufficiently stretched portion). In this embodiment, as will be described later, the understretched portion enters the recess 80 of the bottom mold 74 . A portion forming the bottom surface 57 a is formed so as to surround the concave portion 80 of the bottom mold 74 . Therefore, the portion forming the bottom surface 57 a is thicker than the other portions of the bottom portion 50 . In this case, the insufficiently stretched portion can be prevented from extending to the annular inclined portion 55 .

A protrusion 58 is formed on the bottom surface 57a so as to protrude downward. The convex portion 58 has a substantially inverted truncated cone shape as a whole, and includes a third wall surface 58a and a lower surface 58b. The third wall surface 58a is positioned around the lower surface 58b.

The third wall surface 58a has a substantially conical shape, and extends linearly in a vertical section of the bottom portion 50 (a section passing through the central axis CL). Further, the third wall surface 58a is inclined with respect to the central axis CL of the plastic bottle 10 in the vertical cross section of the bottom portion 50. As shown in FIG. The inclination angle θ2 (see FIG. 4) of the third wall surface 58a with respect to the central axis CL of the plastic bottle 10 is preferably 0.5° or more and 45° or less. By setting the inclination angle θ2 to 0.5° or more, it is possible to improve releasability when removing the plastic bottle 10 from a blow molding die 70 to be described later. Further, since the inclination angle θ2 is 45° or less, the spatial volume of the recessed portion 80 of the blow molding die 70, which will be described later, can be increased. Thereby, as described later, it is possible to prevent the resin that has entered the recessed portion 80 of the blow molding die 70 from flowing out of the recessed portion 80 to the outside in the radial direction. For this reason, as will be described later, in the plastic bottle 10, the range in which the thick portion is formed due to the portion of the preform 100 that is insufficiently stretched can be narrowed. No groove or the like is formed in the third wall surface 58a.

A groove or the like is not formed on the lower surface 58b, and the lower surface 58b is a smooth surface. Although the lower surface 58b has a circular shape when viewed from the bottom surface direction, the lower surface 58b is not limited to this and may have, for example, a polygonal shape. The bottom surface 58b may have an error or deformation (distortion, curvature, etc.) that is unavoidable in manufacturing, and the bottom surface 58b does not have to be a smooth surface.

The diameter D3 of the projection 58 (maximum diameter of the third wall surface 58a, see FIG. 4) may be smaller than the diameter D2 of the bottom surface 57a within a range of 1 mm or more and 5 mm or less. Since the diameter D3 is 1 mm or more smaller than the diameter D2 of the bottom surface 57a, the strength of the bottom mold 74, which will be described later, can be maintained. In addition, since the diameter D3 is smaller than the diameter D2 of the bottom surface 57a by 5 mm or less, it is possible to narrow the range in which the plastic bottle 10 is thickened due to the lack of stretching of the preform 100 .

Also, the height H3 of the projection 58 (vertical distance from the bottom surface 58b to the bottom surface 57a, see FIG. 4) may be 1.5 mm or more and 8 mm or less. By setting the height H3 to 1.5 mm or more, it is possible to more effectively prevent the resin that has entered the recessed portion 80 of the blow molding die 70 from flowing out radially outward of the recessed portion 80, as will be described later. Therefore, as will be described later, in the plastic bottle 10, it is possible to effectively narrow the range in which the thick portion is formed due to the portion of the preform 100 that is insufficiently stretched. Moreover, since the height H3 is 8 mm or less, it is possible to improve releasability when removing the plastic bottle 10 from a blow molding die 70, which will be described later.

The annular inclined portion 55 is positioned radially outward of the central recessed portion 54 and radially inward of the ground contact portion 52 . The upper end of the annular inclined portion 55 is connected to the lower end of the central recessed portion 54 , and the lower end of the annular inclined portion 55 is connected to the radially inner end of the ground portion 52 . The annular inclined portion 55 has a side shape of a truncated cone as a whole. The thickness of the annular inclined portion 55 may be substantially constant as a whole. As described above, the understretched portion does not extend to the annular inclined portion 55 . Therefore, the thickness of the annular inclined portion 55 can be reduced. The thickness of the annular inclined portion 55 is not limited to this, but may be, for example, 0.09 mm or more and 0.8 mm or less. Since the thickness of the annular inclined portion 55 is 0.09 mm or more, excessive stretching of the resin of the annular inclined portion 55 can be suppressed when the plastic bottle 10 is blow-molded. Therefore, it is possible to suppress whitening of the annular inclined portion 55 due to excessive stretching. Moreover, since the thickness of the annular inclined portion 55 is 0.8 mm or less, the heat resistance of the annular inclined portion 55 can be improved.

Further, the annular inclined portion 55 includes the above-described first wall surface 55a. The first wall surface 55a extends linearly in the vertical section of the bottom portion 50 (the section passing through the central axis CL). Also, the first wall surface 55a is inclined with respect to the ground surface 52a in the vertical cross section of the bottom portion 50 . The inclination angle θ3 (see FIG. 4) of the first wall surface 55a with respect to the central axis CL of the plastic bottle 10 is preferably 30° or more and 75° or less. Since the inclination angle θ3 is 30° or more, the annular inclined portion 55 is easily deformed when the pressure inside the content-filled plastic bottle 10A is increased. In addition, since the inclination angle θ3 is 75° or less, when the plastic bottle 10 is filled with the contents, it is possible to suppress the deformation of the annular inclined part 55 below the ground part 52 due to the weight of the contents. . The inclination angle θ3 is larger than the inclination angle θ1 formed between the second wall surface 56a and the central axis CL. The first wall surface 55a is a flat surface without forming grooves or the like.

Also, the height H4 of the first wall surface 55a (vertical distance from the ground surface 52a to the second wall surface 56a, see FIG. 4) may be 3 mm or more and 16 mm or less. However, the height H4 may be 20% or more and 80% or less of the height H2. When the height H4 is 3 mm or more, it is possible to more reliably prevent the insufficiently stretched portion from extending to the annular inclined portion 55 . Further, since the height H4 is 16 mm or less, the annular inclined portion 55 is easily deformed downward when the plastic bottle 10 filled with contents is heated. This can prevent the pressure inside the plastic bottle 10 from becoming too high.

The bottom portion 50 may be stamped with a die number, a factory symbol, a recycle mark, or the like. On the other hand, as will be described later, the annular inclined portion 55 is deformed so that the first wall surface 55a comes into contact with the heating surface 91 (see FIG. 8) when the plastic bottle 10A with content is heated. For this reason, it is preferable that the first wall surface 55a is not stamped with a die number, a factory symbol, a recycle mark, or the like. As a result, even when the annular inclined portion 55 is deformed such that the first wall surface 55a is in contact with the heating surface 91, the plastic bottle 10A with contents can be kept stable.

By the way, the size of such a plastic bottle 10 is not limited, and the bottle may be of any size. For example, the full filling volume of the plastic bottle 10 may be 100 ml or more and 1000 ml or less, preferably 150 ml or more and 700 ml or less, and more preferably 190 ml or more and 550 ml or less. As an example, the full filling capacity of the plastic bottle 10 may be 300 ml.

Furthermore, the weight of the plastic bottle 10 is not limited to this, but when the full filling volume is 550 ml or less, it may be 12 g or more and 28 g or less, preferably 16 g or more and 24 g or less.

Also, the plastic bottle 10 can be produced by biaxially stretching blow molding a preform produced by injection molding a synthetic resin material. The main material of the plastic bottle 10 is a thermoplastic resin, particularly polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polylactic acid (PLA), polycarbonate (PC), or the like. Available. Moreover, the plastic bottle 10 may have a multi-layer structure in which a barrier material layer is sandwiched between two polyethylene terephthalate layers. For example, a preform having a multilayer structure of PET/MXD6/PET may be manufactured and biaxially stretched blow-molded to manufacture the plastic bottle 10, which is a multilayer container. As a material for the plastic bottle 10, recycled plastic produced by sorting, crushing, and washing used plastic products may be used. The plastic bottle 10 may be produced by various molding methods such as direct blow molding in addition to biaxial stretch blow molding.

Method for Manufacturing Plastic Bottle Next, a method for manufacturing the plastic bottle 10 and a method for using the content-filled plastic bottle 10 according to the present embodiment will be described with reference to FIGS. 5 to 10. FIG.

First, as shown in FIG. 5(a), a preform 100 made of a plastic material is prepared. In this case, for example, the preform 100 may be produced by an injection molding method using an injection molding machine (not shown). Further, as the preform 100, a preform generally used conventionally may be used.

Also, as shown in FIG. 5B, a blow mold 70 for manufacturing the plastic bottle 10 is prepared. The blow mold 70 includes a pair of body molds 72 and 73 and a bottom mold 74 which are separated from each other. The body molds 72 and 73 are molds corresponding to the neck 21 , shoulder 22 and body 30 of the plastic bottle 10 . In this embodiment, the body molds 72 and 73 also correspond to part of the bottom 50 of the plastic bottle 10 . The bottom mold 74 is a mold corresponding to the bottom 50 of the plastic bottle 10 . The body molds 72 and 73 and the bottom mold 74 have shapes corresponding to the neck 21, shoulder 22, body 30 and bottom 50 of the plastic bottle 10, respectively.

As shown in FIG. 5(b), the body molds 72, 73 include a flat surface 75. As shown in FIG. Further, as shown in FIG. 6, the bottom mold 74 includes a first side surface 76, a second side surface 77 located radially inward of the first side surface 76 and inclined with respect to the first side surface 76, and a top surface 78 connected to the second side surface 77 . When the body molds 72, 73 and bottom mold 74 are combined, the first side surface 76 and the flat surface 75 are substantially connected to each other. Although not shown, the blow molding die 70 may be configured such that a curved surface is interposed between the first side surface 76 and the flat surface 75 .

The flat surfaces 75 of the body molds 72 and 73 are surfaces corresponding to the ground surface 52 a of the ground portion 52 of the bottom portion 50 of the plastic bottle 10 .

A first side surface 76 of the bottom mold 74 is a surface corresponding to the first wall surface 55 a of the annular inclined portion 55 of the bottom portion 50 . Therefore, the inclination angle θ4 of the first side surface 76 with respect to the central axis CL of the plastic bottle 10 may be equal to the inclination angle θ3 of the first wall surface 55a with respect to the central axis CL of the plastic bottle 10 . That is, the inclination angle θ4 of the first side surface 76 with respect to the central axis CL of the plastic bottle 10 may be 30° or more and 75° or less.

The second side surface 77 is a surface corresponding to the second wall surface 56 a of the central recessed portion 54 of the bottom portion 50 . Therefore, the inclination angle θ5 of the second side surface 77 with respect to the central axis CL of the plastic bottle 10 may be equal to the inclination angle θ1 of the second wall surface 56a with respect to the central axis CL of the plastic bottle 10 . That is, the inclination angle θ5 of the second side surface 77 with respect to the central axis CL of the plastic bottle 10 may be 0.5° or more and 20° or less.

The top surface 78 is a surface corresponding to the bottom surface 57 a of the central recessed portion 54 of the bottom portion 50 . For this reason, the top surface 78 is formed with a concave portion 80 corresponding to the convex portion 58 and recessed downward. In this embodiment, such a blow mold 70 is also provided.

The preform 100 is then blow molded in a blow mold 70 . At this time, the preform 100 is heated by a heating device (not shown). The heating temperature of the preform 100 in this heating step may be, for example, 90°C to 130°C.

Next, as shown in FIG. 7A, the preform 100 is mounted on a blow mold 70 for blow molding.

Next, blowing air is blown into the preform 100 until the preform 100 becomes a molded plastic bottle 10 in the cavity of the blow mold 70 as shown in FIG. 7(b). Inflate.

In plastics such as polyethylene terephthalate, the molecules are oriented by stretching, which improves the heat resistance. On the other hand, the non-stretched portion or the insufficiently stretched portion may be easily deformed by heat without improving the heat resistance. In general, a portion of the bottom portion of the preform 100 (X portion in FIG. 7A) is a portion that is difficult to stretch (hereinafter also simply referred to as an insufficiently stretched portion). In the plastic bottle 10, such an insufficiently stretched portion tends to be thicker than the surrounding portion.

In the present embodiment, the top surface 78 of the bottom mold 74 is formed with a concave portion 80 that is recessed downward. As a result, when the preform 100 expands, the insufficiently stretched portion enters the concave portion 80 . Since the recessed portion 80 is formed in the bottom mold 74 , it is possible to prevent the insufficiently stretched portion that has entered the recessed portion 80 from flowing out of the recessed portion 80 in the radial direction. Therefore, in the plastic bottle 10, the range in which a thick portion (hereinafter, also referred to as a thickened portion) is formed due to the portion of the preform 100 that is insufficiently stretched can be narrowed. That is, it is possible to narrow the range in which a thickened portion that may lower the heat resistance is formed. In this case, the thickened portion can be formed only in the vicinity of the convex portion 58 of the bottom portion 50 .

After that, the plastic bottle 10 is taken out of the blow mold 70 .

Thus, the plastic bottle 10 shown in FIG. 1 is obtained.

Next, the plastic bottle 10 is filled with a content such as a beverage. Subsequently, the opening 20 is closed with a cap (not shown). In this manner, a content-filled plastic bottle 10A (see FIG. 8) is obtained.

Next, how to use the plastic bottle 10 will be described. At this time, for example, as shown in FIG. 8, the contents-containing plastic bottle 10A is heated by a hot plate 90 . A heating surface 91 of the hot plate 90 is heated by a heater (not shown). By placing the plastic bottle 10A with contents on the heating surface 91, the plastic bottle 10A with contents is heated. Note that the hot plate 90 is used here instead of the bottle warmer. A heating surface 91 of the hot plate 90 corresponds to a shelf plate of a bottle warmer heated by a heater.

At this time, the pressure inside the content-filled plastic bottle 10A rises due to the heating of the content. Thereby, as shown in FIG. 9, the annular inclined portion 55 is deformed. At this time, the annular inclined portion 55 is deformed so that the first wall surface 55 a contacts the heating surface 91 . Therefore, the volume of the plastic bottle 10 is increased, and the bottom portion 50 can absorb the increase in pressure inside the plastic bottle 10A. As a result, it is possible to suppress the phenomenon (buckling) in which the bottom portion 50 inverts and protrudes outward. In addition, in the present embodiment, as described above, the area where the thickened thickened portion (the shaded portion shown in FIG. 9) is formed due to the insufficiently stretched portion of the preform 100 is narrowed. . In this way, since the range in which the thickened portion where the heat resistance is lowered is formed is narrow, even when the temperature of the contents becomes high, as shown in FIG. The amount of deformation of the concave portion 54 can be reduced. Therefore, it is possible to suppress a phenomenon (buckling) in which the bottom portion 50 is reversed and protrudes outward. In addition, in FIG. 9, the bottom part 50 after deformation is indicated by a dashed line.

On the other hand, as a comparative example, as shown in FIG. 10, when the convex portion 58 is not formed on the bottom surface 57a of the bottom portion 50, the range in which the thickening portion (shaded portion shown in FIG. 10) is formed can be widened. . That is, when the plastic bottle 10 is produced using the bottom mold 74 in which the recess 80 is not formed, the area where the meat pool is formed can be widened. In this case, when the temperature of the contents rises, the amount of deformation of the central recessed portion 54 of the bottom portion 50 increases. For this reason, a phenomenon (buckling) may occur in which the bottom portion 50 is reversed and protrudes outward. In addition, in FIG. 10, the bottom part 50 after deformation is indicated by a dashed line.

As described above, according to the present embodiment, the bottom portion 50 of the plastic bottle 10 has the peripheral edge portion 51 located at the peripheral edge of the bottom portion 50 and the ground portion 52 located radially inward of the peripheral edge portion 51 . , and a central portion 53 positioned radially inward of the ground portion 52 . Further, the ground portion 52 includes an annular flat ground surface 52a. Further, the central portion 53 includes a first wall surface 55a connected to the ground surface 52a and a second wall surface 56a connected to the first wall surface 55a and inclined with respect to the first wall surface 55a. As a result, when the pressure inside the content-filled plastic bottle 10A rises due to the heating of the content, the central portion 53 and the first wall surface 55a become the heating surface (for example, the heating surface 91 of the hot plate 90). ) to be grounded. Therefore, the volume of the plastic bottle 10 is increased, and the bottom portion 50 can absorb the increase in pressure inside the plastic bottle 10A. As a result, it is possible to suppress the phenomenon (buckling) in which the bottom portion 50 inverts and protrudes outward.

Also, the central portion 53 includes a bottom surface 57a connected to the second wall surface 56a. A convex portion 58 that protrudes downward is formed on the bottom surface 57a. In this case, thickened thickened portions due to insufficiently stretched portions of the preform 100 are formed only in the vicinity of the convex portions 58 . Therefore, it is possible to narrow the range in which the thickened portion is formed. As a result, it is possible to narrow the region where the heat resistance may be lowered. Therefore, the phenomenon (buckling) in which the bottom portion 50 is reversed and protrudes outward can be more effectively suppressed. It should be noted that the fact that the phenomenon (buckling) in which the bottom portion 50 inverts and protrudes outward can be suppressed will be described in the examples described later.

(Modification)
Next, modified examples of the plastic bottle and the blow mold will be described.

(First modification)
11A and 11B show a first modification of the plastic bottle 10. FIG. The modified example shown in FIGS. 11A and 11B is different in that the convex portion 58 is formed in an annular shape, and other configurations are substantially the same as those shown in FIGS. 1 to 10 described above. In FIGS. 11A and 11B, the same parts as those shown in FIGS. 1 to 10 are denoted by the same reference numerals, and detailed description thereof is omitted.

In the modification shown in FIGS. 11A and 11B, the convex portion 58 is formed in an annular shape. Specifically, the convex portion 58 has an annular shape when viewed from the bottom surface direction. In this case, the convex portion 58 further includes a fourth wall surface 58c located radially inward of the lower surface 58b.

The fourth wall surface 58c extends linearly in the vertical section of the bottom portion 50 (the section passing through the central axis CL). Also, the fourth wall surface 58c is inclined with respect to the central axis CL of the plastic bottle 10 in the vertical cross section of the bottom portion 50 . The inclination angle θ6 (see FIG. 11B) of the fourth wall surface 58c with respect to the central axis CL of the plastic bottle 10 is preferably 0.5° or more and 45° or less. When the inclination angle θ6 is 0.5° or more, the releasability of the plastic bottle 10 from the blow mold 70 can be improved. Further, since the inclination angle θ6 is 45° or less, the spatial volume of the recessed portion 80 of the blow mold 70 can be increased. As a result, the resin that has entered the recessed portion 80 of the blow mold 70 can be prevented from flowing out of the recessed portion 80 in the radial direction. Therefore, in the plastic bottle 10, the range in which the thick-walled portion is formed due to the insufficiently stretched portion of the preform 100 can be narrowed. No groove or the like is formed in the fourth wall surface 58c.

In this modification, the width W2 (radial distance, see FIG. 11B) of the projection 58 may be 3 mm or more and 10 mm or less. By setting the width W2 to be 3 mm or more, the thickened portion can be formed only in the vicinity of the convex portion 58 of the bottom portion 50 . In addition, since the width W2 is 10 mm or less, the strength of the bottom mold 74 can be sufficiently maintained.

When manufacturing the plastic bottle 10 according to the first modified example, as shown in FIG. 12, the recess 80 of the bottom mold 74 may be formed in an annular shape.

According to this modified example, the convex portion 58 is formed in an annular shape. Thereby, the length of the convex portion 58 can be increased. That is, the total area of the third wall surface 58a, the lower surface 58b and the fourth wall surface 58c can be increased. For this reason, even if a thickened portion is formed in the vicinity of the convex portion 58, the thickness of the thickened portion can be reduced. As a result, deterioration in the heat resistance of the projections 58 can be suppressed. Therefore, according to this modified example, the phenomenon (buckling) in which the bottom portion 50 is reversed and protrudes outward can be more effectively suppressed.

(Second modification)
FIG. 13 shows a second modification of the plastic bottle 10. As shown in FIG. The modification shown in FIG. 13 is different in that the first wall surface 55a is a curved surface, and other configurations are substantially the same as those shown in FIGS. 1 to 12 described above. In FIG. 13, the same reference numerals are assigned to the same parts as those in the embodiment shown in FIGS. 1 to 12, and detailed description thereof will be omitted.

In the modification shown in FIG. 13, the first wall surface 55a is a curved surface. The first wall surface 55a rises from below (the ground contact portion 52 side) to above (the body portion 30 side) as it goes radially inward from radially outward. In the vertical cross section (cross section passing through the central axis CL) of the bottom portion 50, the first wall surface 55a gradually increases in angle with respect to the ground contact surface 52a of the ground contact portion 52 as it goes radially inward from radially outward. It is curved so that

In this case, the curvature radius R1 of the first wall surface 55a is preferably 8 mm or more. Since the curvature radius R1 is 8 mm or more, the annular inclined portion 55 is easily deformed downward when the plastic bottle 10 filled with contents is heated. Thereby, an increase in the pressure inside the plastic bottle 10 can be suppressed. When the radius of curvature R1 of the first wall surface 55a exceeds 20 mm, in the vertical section, an imaginary straight line IL1 passing through the boundary point P1 between the first wall surface 55a and the ground surface 52a and the central axis CL of the plastic bottle 10 The angle θ7 formed by the two may be 30° or more and 75° or less. Here, the imaginary straight line IL1 is a tangent to the imaginary curve IL2. Also, the virtual curve IL2 is an arc extending from the first wall surface 55a in the vertical cross section and having the same center as the arc formed by the first wall surface 55a.

When manufacturing the plastic bottle 10 according to the second modification, as shown in FIG. 14, the first side surface 76 of the bottom mold 74 may be curved. In this case, the curvature radius R2 of the first side surface 76 may be equal to the curvature radius R1 of the first wall surface 55a. That is, the curvature radius R2 of the first side surface 76 may be 8 mm or more. When the curvature radius R2 of the first side surface 76 exceeds 20 mm, the angle θ8 formed between the imaginary straight line IL3 passing through the outer edge P2 of the first side surface 76 and the central axis CL of the plastic bottle 10 is 30 mm in the vertical section. ° or more and 75° or less. Here, the imaginary straight line IL3 is a tangent to the imaginary curve IL4. Also, the virtual curve IL4 is an arc extending from the first side surface 76 in the vertical cross section and having the same center as the arc formed by the first side surface 76 .

Also in this modified example, when the pressure inside the content-filled plastic bottle 10A rises, the central portion 53 deforms such that the first wall surface 55a contacts the heating surface. Therefore, the volume of the plastic bottle 10 is increased, and the bottom portion 50 can absorb the increase in pressure inside the plastic bottle 10A. As a result, it is possible to suppress the phenomenon (buckling) in which the bottom portion 50 inverts and protrudes outward.

(Third modification)
FIG. 15 shows a third modification of the plastic bottle 10. As shown in FIG. The modification shown in FIG. 15 is different in that a plurality of vertically extending ribs 59 are formed on the second wall surface 56a. are identical. In FIG. 15, the same reference numerals are assigned to the same portions as those in the embodiment shown in FIGS. 1 to 14, and detailed description thereof will be omitted.

In the modification shown in FIG. 15, a plurality of vertically extending ribs 59 are formed on the second wall surface 56a. Note that the number of ribs 59 may be 5 or more and 20 or less. The ribs 59 may be arranged at regular intervals in the circumferential direction. Each rib 59 has a lower end connected to the annular inclined portion 55 and an upper end terminating at a portion forming the second wall surface 56 a of the central recess 54 . Each rib 59 is formed in a groove shape, and has a substantially U-shape or substantially U-shape in a cross section perpendicular to the width direction. Each rib 59 is arranged along the slope of the second wall surface 56a. That is, each rib 59 is inclined at the same angle as the second wall surface 56a with respect to the ground contact surface 52a in the vertical section of the bottom portion 50 (the section passing through the central axis CL). Note that the intervals between the ribs 59 may not be constant. Also, the upper end of each rib 59 may terminate before the portion forming the second wall surface 56a. Further, each rib 59 may be inclined at a different angle from the second wall surface 56a with respect to the ground surface 52a in the vertical cross section (cross section passing through the central axis CL) of the bottom portion 50 . Furthermore, each rib 59 may be formed in a convex shape instead of being formed in a groove shape, and even if the ribs 59 formed in a groove shape and the ribs 59 formed in a convex shape are mixed, good.

When manufacturing the plastic bottle 10 according to the third modified example, as shown in FIG. 16, a plurality of vertically extending ribs 79 may be formed on the second side surface 77 of the bottom mold 74 . The ribs 79 are portions corresponding to the ribs 59 of the plastic bottle 10 , and may protrude radially outward from the second side surface 77 .

According to this modification, a plurality of ribs 59 extending in the vertical direction are formed on the second wall surface 56a. Thereby, the rigidity of the central concave portion 54 can be increased. Therefore, it is possible to suppress the deformation of the central concave portion 54 when the pressure inside the content-filled plastic bottle 10A increases. As a result, the phenomenon (buckling) in which the bottom portion 50 inverts and protrudes outward can be more effectively suppressed.

(Fourth modification)
FIG. 17 shows a fourth modification of the blow mold. The modification shown in FIG. 17 is different in that a step is formed between the trunk molds 72 and 73 and the bottom mold 74, and other configurations are shown in FIGS. 1 to 16 described above. It is almost the same as the form. In FIG. 17, the same reference numerals are assigned to the same parts as those shown in FIGS. 1 to 16, and detailed description thereof will be omitted.

In the modification shown in FIG. 17, a step is formed between the trunk molds 72 and 73 and the bottom mold 74 . In this case, the height H5 of the step may be, for example, 0.5 mm or more and 1.0 mm or less. Ideally, there should be no step between the body molds 72, 73 and the bottom mold 74. On the other hand, due to the machining accuracy and operating accuracy when machining the body molds 72 and 73 and the bottom mold 74, a slight step may occur. At this time, if the shape of the steps between the body molds 72, 73 and the bottom mold 74 differs every time the plastic bottle 10 is molded, the quality of the molded plastic bottle 10 becomes unstable. For example, in one molding process, the bottom mold 74 is positioned below the body molds 72, 73, and in another molding process, the bottom mold 74 is positioned above the body molds 72, 73. , the quality of the molded plastic bottle 10 becomes unstable. For this reason, the bottom mold 74 is always positioned above the body molds 72 and 73, so that there is a step of height H5 between the body molds 72 and 73 and the bottom mold 74. You may make it form. In this case, it can be considered that the first side surface 76 and the flat surface 75 are substantially connected to each other. Also in this case, the plastic bottle 10 can be manufactured in which the phenomenon (buckling) in which the bottom portion 50 is inverted and protrudes outward can be suppressed.

(Fifth modification)
FIG. 18 shows a fifth modification of the blow mold. The modification shown in FIG. 18 is different in that a gap G is formed between the body molds 72, 73 and the bottom mold 74, and other configurations are shown in FIGS. It is substantially the same as the shown form. In FIG. 18, the same reference numerals are given to the same parts as in the embodiment shown in FIGS. 1 to 17, and detailed description thereof will be omitted.

In the modification shown in FIG. 18, a gap G is formed between the trunk molds 72 and 73 and the bottom mold 74 . In this modification, the body molds 72 and 73 do not correspond to the bottom 50 of the plastic bottle 10 . Specifically, the body molds 72 and 73 correspond to the neck 21 , shoulder 22 and body 30 of the plastic bottle 10 , and the bottom mold 74 corresponds to the bottom 50 of the plastic bottle 10 . In this case, the width W3 of the gap G may be, for example, 0.5 mm or more and 1.0 mm or less. Also in this case, the plastic bottle 10 can be manufactured in which the phenomenon (buckling) in which the bottom portion 50 is inverted and protrudes outward can be suppressed.

Next, specific examples of the present invention will be described.

(Example 1)
First, a plastic bottle 10 having a full filling capacity of 300 ml and having the configuration shown in FIGS. 1 to 4 was produced. In this case, a 22-g PET single-layer preform was produced by injection molding, and the plastic bottle 10 was produced by subjecting this preform to biaxial stretch blow molding.

At this time, the height H of the plastic bottle 10 (see FIG. 1) was 132 mm, and the height H1 of the mouth portion 20 (see FIG. 1) was 21 mm. Moreover, the maximum diameter D1 of the trunk|drum 30 was 65 mm.

Also, in the bottom portion 50 of the plastic bottle 10, the height H2 from the ground surface 52a to the bottom surface 57a was 20 mm. Also, the height H3 of the convex portion 58 was 5 mm. Also, the height H4 of the first wall surface 55a was 10 mm. Also, the diameter D2 of the bottom surface 57a was 23.8 mm. Also, the diameter D3 of the projection 58 was 20 mm. The inclination angle θ1 of the second wall surface 56a with respect to the central axis CL of the plastic bottle 10 was 12.6°. Furthermore, the inclination angle θ3 of the first wall surface 55a with respect to the central axis CL of the plastic bottle 10 was 31.5°.

Next, the obtained plastic bottle 10 was filled with water at a temperature of 22°C. Water was filled up to a position of 25 mm downward from the upper end of the mouth portion 20 . After that, a cap (not shown) was attached to the mouth portion 20 .

Next, a severe test was performed on the content-filled plastic bottle 10A filled with water. At this time, eight plastic bottles 10A containing contents were placed on the heating surface 91 of a hot plate 90 (manufactured by AS ONE Corporation, EC-1200N) whose heating surface was set to 200.degree. By checking the plastic bottle 10 every 10 minutes, it was confirmed whether or not the plastic bottle 10 had a defective phenomenon. Specifically, it was confirmed whether or not the plastic bottle 10 was tilted or poorly grounded due to the deformation of the bottom portion 50 . In addition, it was confirmed whether or not so-called whitening had occurred in the bottom portion 50 . In addition, "whitening" refers to a phenomenon of whitening due to crystallization by heat.

(Example 2)
In the same manner as in Example 1, except that the plastic bottle 10 having the convex portion 58 formed in an annular shape as shown in FIGS. 11A and 11B was produced, and the width W2 of the convex portion 58 was 6 mm, I did a rigorous test.

(Example 3)
A severe test was conducted in the same manner as in Example 2, except that the height H3 of the projection 58 was 2 mm.

(Example 4)
A severe test was conducted in the same manner as in Example 2, except that the width W2 of the projection 58 was 4 mm.

(Example 5)
The same as Example 2 except that the height H4 of the first wall surface 55a was 7.2 mm, the inclination angle θ1 was 2.5°, and the inclination angle θ3 was 50°. and conducted a rigorous test.

(Example 6)
The same as Example 2 except that the height H4 of the first wall surface 55a was 3.3 mm, the inclination angle θ1 was 2.5°, and the inclination angle θ3 was 70°. and conducted a rigorous test.

(Example 7)
The plastic bottle 10 shown in FIG. 13 having a curved first wall surface 55a was manufactured, the inclination angle θ1 was 5°, the curvature radius R1 of the first wall surface 55a was 12.4 mm, A severe test was conducted in the same manner as in Example 2, except for the above.

(Example 8)
The plastic bottle 10 shown in FIG. 15 having a plurality of ribs 59 formed on the second wall surface 56a was manufactured, the height H4 of the first wall surface 55a was 3.3 mm, and the inclination angle θ1 was 2.5. A severe test was conducted in the same manner as in Example 2, except that the tilt angle θ3 was 70°.

(Comparative example 1)
A severe test was conducted in the same manner as in Example 1, except that a plastic bottle 10B in which the bottom surface 57a of the bottom portion 50 was not formed with the projections 58 as shown in FIG. 19 was produced.

(Comparative example 2)
A severe test was carried out in the same manner as in Example 2, except that the plastic bottle 10C shown in FIG. did In the plastic bottle 10C shown in FIG. 20, the central portion 53 does not have the annular inclined portion 55. As shown in FIG. In this case, the lower end of the central recessed portion 54 is connected to the radially inner end of the grounding portion 52 .

Tables 1 to 3 show the above results. In the column of "time (minutes) when the failure phenomenon occurred" in Table 3, "-" means that the failure phenomenon did not occur even after 120 minutes. In addition, in the "Determination" column of Table 3, "⊚" means that no defect phenomenon occurred even after 110 minutes or more. In addition, in the column of "judgment" in Table 3, "○" means that a defect phenomenon occurred in the end, but no defect phenomenon occurred after 80 minutes had passed. Furthermore, in the column of "determination" in Table 3, "x" means that a defect phenomenon occurred at 80 minutes or before 80 minutes had passed.

As a result, in the plastic bottles 10B and 10C according to Comparative Examples 1 and 2, the defective phenomenon occurred before 80 minutes passed.

In contrast, in the plastic bottles 10 according to Examples 1 to 8, no defect phenomenon occurred for 80 minutes. In particular, in the plastic bottles 10 according to Examples 1, 2, and 5 to 8, no defect occurred even after 110 minutes or more. As described above, it was found that the plastic bottle 10 according to the present embodiment can suppress the defective phenomenon of the bottom portion 50 .

It is also possible to appropriately combine a plurality of constituent elements disclosed in each of the above embodiments and modifications as necessary. Alternatively, some components may be deleted from all the components shown in each of the above embodiments and modifications.

10 Plastic bottle 20 Mouth 30 Body 50 Bottom 51 Peripheral edge 52 Grounding part 52a Grounding surface 53 Central part 55a First wall surface 56a Second wall surface 57a Bottom surface 58 Projection 59 Rib 70 Blow mold 72 Body mold 73 Body mold 74 bottom mold 75 flat surface 76 first side surface 77 second side surface 78 top surface 79 rib 80 concave portion 100 preform

Claims (15)

A warming plastic bottle comprising a mouth, a body and a bottom,
The bottom is
a peripheral portion located on the peripheral edge of the bottom portion;
a grounding portion located radially inward of the peripheral portion;
a central portion positioned radially inward of the ground contact portion;
The ground contact portion includes an annular flat ground contact surface,
The central portion is
a first wall surface connected to the ground surface;
A second wall surface connected to the first wall surface and inclined with respect to the first wall surface;
a bottom surface connected to the second wall surface;
A protrusion projecting downward is formed on the bottom surface,
The convex portion includes a lower surface and a third wall surface positioned around the lower surface and extending upward from the lower surface,
In a vertical cross section, the lower surface and the third wall surface extend linearly,
A portion of the bottom surface other than the convex portion is a flat surface extending in the horizontal direction,
The plastic bottle , wherein the height of the first wall surface is higher than the height of the protrusion . 2. The plastic bottle according to claim 1, wherein said projection is annular. 2. The plastic bottle according to claim 1, wherein the inclination angle of said first wall surface with respect to the central axis of said plastic bottle is 30[deg.] or more and 75[deg.] or less. 2. The plastic bottle according to claim 1, wherein the inclination angle of said second wall surface with respect to the central axis of said plastic bottle is 0.5[deg.] or more and 20[deg.] or less. The plastic bottle according to claim 1, wherein said first wall surface is a curved surface. 2. The plastic bottle according to claim 1, wherein the radius of curvature of said first wall surface is 8 mm or more. 2. The plastic bottle according to claim 1, wherein a plurality of vertically extending ribs are formed on said second wall surface. A blow mold for blow molding a warming plastic bottle comprising a mouth, a body and a bottom, comprising:
a body mold corresponding to the body of the plastic bottle;
a bottom mold corresponding to the bottom of the plastic bottle;
The bottom mold is
a first side;
a second side surface positioned radially inward of the first side surface and inclined with respect to the first side surface;
a top surface connected to the second side surface;
The bottom of the plastic bottle is
a peripheral portion located on the peripheral edge of the bottom portion;
a grounding portion located radially inward of the peripheral portion;
a central portion positioned radially inward of the ground contact portion;
The ground contact portion includes an annular flat ground contact surface,
The central portion is
a first wall surface connected to the ground surface;
A second wall surface connected to the first wall surface and inclined with respect to the first wall surface;
a bottom surface connected to the second wall surface;
A protrusion projecting downward is formed on the bottom surface,
The convex portion includes a lower surface and a third wall surface positioned around the lower surface and extending upward from the lower surface,
In a vertical cross section, the lower surface and the third wall surface extend linearly,
A portion of the bottom surface other than the convex portion is a flat surface extending in the horizontal direction,
The top surface is recessed downward and formed with a concave portion corresponding to the convex portion ,
The blow molding die, wherein the height of the first wall surface is higher than the height of the convex portion . 9. The blow mold of claim 8, wherein the recess is annular. 9. The blow mold according to claim 8, wherein the inclination angle of the first side surface with respect to the central axis of the plastic bottle is 30[deg.] or more and 75[deg.] or less. 9. The blow mold according to claim 8, wherein the inclination angle of the second side surface with respect to the central axis of the plastic bottle is 0.5[deg.] or more and 20[deg.] or less. 9. The blow mold of claim 8, wherein the first side is a curved surface. The blow mold according to claim 8, wherein the radius of curvature of the first side surface is 8 mm or more. 9. The blow mold according to claim 8, wherein the second side surface is formed with a plurality of vertically extending ribs. A method for manufacturing a plastic bottle, comprising:
preparing a preform;
providing a blow mold according to any one of claims 8 to 14;
Blow molding the preform in the blow mold.

Images