Synthetic resin container

Abstract

To provide a synthetic resin container which can suppress a mouth part 10 from deforming during boiling sterilization.SOLUTION: A synthetic resin container 1 includes a cylindrical mouth part 10, a shoulder part 14 integrally connected to the lower end of the mouth part 10, a body part 15 integrally connected to the lower end of the shoulder part 14 and a bottom part 16 integrally connected to the lower end of the body part 15. In the synthetic resin container 1, the mouth part 10 has a mounting part 11 to which a cap 2 is mounted, a neck ring 12 integrally connected to the lower end of the mounting part 11, and a straight part 13 which has a cylindrical outer shape and is provided integrally with the lower end of the neck ring 12. The part of 75% or more and less than 100% downward from the upper end 13a of the straight part 13 is a thermally crystallized part 13c which has a density of 1.365 g / cm3 or more.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a synthetic resin container. [Background technology]

[0002] Glass containers, such as wide-mouth bottles, whose mouths are closed with metal caps are widely used as containers for storing food contents, such as jam, which require boiling sterilization after hot filling. However, there is a demand for synthetic resin containers that use plastic instead of glass to make them lighter and less likely to break.

[0003] Conventionally, a known example of such a synthetic resin container includes a cylindrical mouth portion onto which a metal cap is attached, a shoulder portion integrally connected to the lower end of the mouth portion, a body portion integrally connected to the lower end of the shoulder portion, and a bottom portion integrally connected to the lower end of the body portion (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2018-199509 A Summary of the Invention [Problem to be solved by the invention]

[0005] In the above-mentioned conventional synthetic resin containers, the contents are hot-filled, the mouth is sealed with a metal cap, and then boiled for sterilization. During this process, however, there is a risk that the mouth will deform relative to the metal cap, which is resistant to thermal expansion, and the sealing between the metal cap and the mouth will be compromised.

[0006] In response to this, it is conceivable to thermally crystallize the mouth portion to increase its heat resistance, thereby ensuring a tight seal between the cap and the mouth portion after boiling sterilization.

[0007] However, even with this method, there was a problem in that the lower end portion of the mouth of the synthetic resin container would deform and stretch vertically due to the heat and increased internal pressure during boiling sterilization, causing the height of the container to increase and the internal volume of the container to increase, which could result in decompression deformation of the container after cooling.

[0008] The present invention was developed to solve these problems, and its purpose is to provide a synthetic resin container that is capable of suppressing deformation of the mouth during boiling sterilization. [Means for solving the problem]

[0009] The synthetic resin container of the present invention comprises a cylindrical mouth portion, a shoulder portion integrally connected to a lower end of the mouth portion, a body portion integrally connected to the lower end of the shoulder portion, and a bottom portion integrally connected to the lower end of the body portion. Made of polyethylene terephthalate A synthetic resin container, the mouth of which has an attachment part to which a cap is attached, a neck ring integrally provided at the lower end of the attachment part, and a straight part having a cylindrical outer shape integrally provided at the lower end of the neck ring, the straight part having a density of 1.365 g / cm or more and less than 100% of the straight part downward from the upper end. 3 The thermal crystallization has a density of at least 100 nm.

[0011] In the synthetic resin container of the present invention having the above-mentioned configuration, it is preferable that the mounting portion has a wide-mouth shape with an inner diameter of 35 mm or more. Effect of the Invention

[0012] According to the present invention, it is possible to provide a synthetic resin container capable of suppressing deformation of a straight portion during boiling sterilization. [Brief description of the drawings]

[0013] [Figure 1] 1 is a front view of a capped container using a synthetic resin container according to one embodiment of the present invention. [Diagram 2]FIG. 2 is a front view of the synthetic resin container shown in FIG. [Diagram 3] FIG. 2 is a plan view of the synthetic resin container shown in FIG. [Figure 4] FIG. 2 is a bottom view of the metal cap shown in FIG. [Diagram 5] 2 is an enlarged half sectional view of a main part of the synthetic resin container shown in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A synthetic resin container according to an embodiment of the present invention will now be described in detail with reference to the drawings.

[0015] In the claims and this specification, "upper" and "lower" refer to the "upper" and "lower" when the synthetic resin container 1 is placed in an upright position as shown in FIG.

[0016] As shown in Fig. 1, a synthetic resin container 1 according to an embodiment of the present invention is used together with a cap 2 as a capped container 3. In consideration of boiling sterilization, a metal cap is preferably used as the cap 2. In this embodiment, a description will be given assuming that a metal cap 2 is used.

[0017] 2, the synthetic resin container 1 comprises, from top to bottom, a mouth portion 10, a shoulder portion 14, a body portion 15, and a bottom portion 16. The mouth portion 10 comprises, from top to bottom, a mounting portion 11, a neck ring 12, and a straight portion 13. The synthetic resin container 1 is molded, for example, by blow molding an injection-molded preform.

[0018] 2 and 3, the mounting portion 11 is cylindrical with its axis O at its center, and has a male thread 11a formed integrally on its outer circumferential surface. In this embodiment, the male thread 11a is a four-thread thread, and a stopper portion 11b is formed integrally on its lower end portion. As will be described later, a metal cap 2 is attached to the mouth portion 10 by being screwed to the male thread 11a.

[0019] The neck ring 12 is provided integrally and continuously at the lower end of the mounting part 11. The neck ring 12 is in the form of a flange that protrudes radially outward from the outer circumferential surface of the mounting part 11, centered on the axis O, and extends all around the circumference centered on the axis O. The neck ring 12 functions, for example, as a gripping part for transporting the preform and the synthetic resin container 1, or as a part that is placed on the mold during blow molding.

[0020] The straight portion 13 is provided integrally and continuously at the lower end of the neck ring 12. The straight portion 13 is cylindrical with an outer diameter that is approximately the same as that of the mounting portion 11 and smaller than that of the neck ring 12, and the outer diameter is constant between the upper end 13a (see FIG. 5) on the neck ring 12 side and the lower end 13b (see FIG. 5) on the shoulder portion 14 side. Note that, as long as the outer diameter of the straight portion 13 is substantially constant, a part of the lower end side of the straight portion 13 may be pulled by the stretching of the shoulder portion 14, so that the thickness of the straight portion 13 gradually decreases downward. In this case, the outer diameter of the straight portion 13 may change linearly from the top to the bottom, or may be formed in a gentle curve.

[0021] The shoulder portion 14 is provided integrally and connected to the lower end of the straight portion 13. The shoulder portion 14 has an outwardly convex curved shape that gradually widens in diameter downward from the upper end connected to the straight portion 13. The boundary between the straight portion 13 and the shoulder portion 14 is the part where the shoulder portion 14 widens in diameter radially outward.

[0022] The body portion 15 is provided integrally and continuously with the lower end of the shoulder portion 14. The body portion 15 has a cylindrical shape with a lower portion having a slightly reduced diameter.

[0023] The bottom portion 16 is provided integrally with the lower end of the body portion 15 and closes the lower end of the body portion 15 .

[0024] The shapes of the shoulder portion 14, the body portion 15 and the bottom portion 16 can be variously modified.

[0025] The interior of the synthetic resin container 1 is a storage space S for contents (see FIG. 5). The synthetic resin container 1 can store, as contents, foods such as jam that require boiling sterilization after hot filling.

[0026] In this embodiment, the synthetic resin container 1 has a wide-mouth shape with an inner diameter of 35 mm or more at the attachment part 11. Since the synthetic resin container 1 has a wide-mouth shape, when contents such as the jam described above are stored, the contents can be easily taken out using a tool such as a spoon.

[0027] The synthetic resin container 1 can be a blow-molded product made of a synthetic resin such as polyethylene terephthalate, high density polyethylene, low density polyethylene, or polypropylene.

[0028] As shown in FIGS. 1 and 4, the metal cap 2 includes a cap body 21 and a liner material 22. The cap body 21 and the liner material 22 are made of a material other than metal.

[0029] The cap body 21 includes a substantially circular top wall 21a, a cylindrical peripheral wall 21b integrally connected to the outer periphery of the top wall 21a, an annular curled portion 21c protruding radially inward from the lower end of the peripheral wall 21b, and a plurality of lugs (projections) 21d protruding radially inward from the inner periphery of the curled portion 21c. In this embodiment, the cap body 21 is provided with four lugs 21d arranged at equal intervals in the circumferential direction in response to the male thread 11a provided in the mouth portion 10 being a four-start thread.

[0030] The cap body 21 can be a metal pressed product in which the top wall 21a, the peripheral wall 21b, the curled portion 21c, and the lugs 21d are integrally formed by pressing a metal plate such as a stainless steel plate.

[0031] The cap 2 is screwed and fixed to the mouth 10 by rotating it in a tightening direction relative to the mouth 10 so that the lug 21d is screwed into the male thread 11a provided on the mounting part 11 of the synthetic resin container 1 (bayonet connection). The cap 2 can be removed from the mouth 10 by rotating it in a direction that loosens the screw fastening to the mouth 10. By mounting the metal cap 2 on the mouth 10 of the synthetic resin container 1, a capped container 3 is formed.

[0032] The liner material 22 is provided on the inner surface of the top wall 21a of the cap body 21 (the surface facing the storage space S when the cap 2 is attached to the synthetic resin container 1). When the cap 2 is attached to the synthetic resin container 1, the liner material 22 abuts against the tip of the mouth part 10 and seals the gap between the tip of the mouth part 10 and the inner surface of the top wall 21a. In this embodiment, the liner material 22 is annular, arranged along the outer periphery of the inner surface of the top wall 21a, and fixed to the top wall 21a by means of adhesion or the like. As the liner material 22, for example, a sheet-shaped elastic body such as soft synthetic resin such as polyvinyl chloride or synthetic rubber can be used.

[0033] Furthermore, as long as the liner material 22 is provided on the inner surface of the top wall 21a of the cap body 21 and abuts the tip of the mouth portion 10 around its entire circumference, its shape can be modified in various ways, such as a shape that covers the entire inner surface of the top wall 21a.

[0034] In the synthetic resin container 1 of this embodiment, as shown in FIG. 5, the portion of the straight portion 13 from the upper end 13a downward to 75% or more but less than 100% has a compressive strength of 1.365 g / cm 3 In other words, if the height dimension (vertical dimension) of straight portion 13 from upper end 13a to lower end 13b is H, then range R of straight portion 13 from upper end 13a to 75% or more but less than 100% of height dimension H is thermally crystallized portion 13c.

[0035] Here, the thermally crystallized portion 13c is formed by heat-treating the portion of the straight portion 13 within the range R at a temperature at which the synthetic resin material constituting the synthetic resin container 1 crystallizes, thereby increasing the degree of crystallization and causing thermal crystallization. For example, when the synthetic resin container 1 is molded from polyethylene terephthalate, the thermally crystallized portion 13c changes from transparent to white (semi-transparent, opaque).

[0036] In this manner, in the synthetic resin container 1 of the present embodiment, the portion of the straight portion 13 in the range R from 75% or more to less than 100% downward from the upper end 13a is set to a value of 1.365 g / cm 3 Since the thermally crystallized portion 13c has a density equal to or greater than this, the heat resistance of the straight portion 13 can be improved. Therefore, even if the contents are hot-filled into the storage space S through the mouth portion 10, the metal cap 2 is attached to the mouth portion 10 to close the mouth portion 10, and then boiling sterilization is performed, the straight portion 13 can be prevented from deforming so as to expand vertically due to the heat and increase in internal pressure (pressure in the storage space S) during boiling sterilization, and this can prevent the problem that the straight portion 13 deforms so as to expand vertically, increasing the height of the synthetic resin container 1 and increasing the internal volume of the synthetic resin container 1, causing decompression deformation of the synthetic resin container 1 after cooling. The straight portion 13 is a portion whose external shape does not substantially change before and after blow molding.

[0037] If the range R in which the thermally crystallized portion 13c of the straight portion 13 is provided is less than 75% downward from the upper end 13a of the straight portion 13, deformation of the straight portion 13 cannot be sufficiently suppressed during boiling sterilization, and there is a risk of unexpected decompression deformation in the synthetic resin container 1 after cooling. On the other hand, if the range R in which the thermally crystallized portion 13c of the straight portion 13 can be provided is 100% downward from the upper end 13a of the straight portion 13, there will be a large step (thickness difference) at the boundary between the straight portion 13 and the shoulder portion 14, and the straight portion 13 will not actually be stretched, and a sudden change will occur due to the shoulder portion 14 being stretched, which may cause damage at the boundary when the container is subjected to an external force such as being dropped. In contrast, by setting the range R in which the thermal crystallization portion 13c of the straight portion 13 is provided to a range of 75% or more and less than 100% downward from the upper end 13a of the straight portion 13, as in the synthetic resin container 1 of this embodiment, deformation of the straight portion 13 during boiling sterilization can be effectively suppressed without causing the above-mentioned problems.

[0038] The synthetic resin container 1 of this embodiment can also be configured such that the mounting portion 11 and the neck ring 12 are thermally crystallized, and the density of the thermally crystallized portion 13c gradually decreases downward from the upper end 13a.

[0039] In this case, it is preferable that the mounting portion 11 and the neck ring 12 have a density equal to or greater than that of the straight portion 13, for example, 1.375 to 1.390 g / cm on average. 3 In this case, it is preferable to perform the thermal crystallization so that the density in the mounting portion 11 and the neck ring 12 is substantially uniform.

[0040] This configuration improves the heat resistance of the mounting part 11 and the neck ring 12, and prevents the mounting part 11 or the neck ring 12 from deforming during boiling sterilization, thereby preventing a decrease in the sealing performance between the cap 2 and the mouth part 10. In particular, even if the cap 2 having four lugs 21d is screwed to the male thread 11a and attached to the mouth part 10, it is possible to prevent the mouth part 10 from expanding between the four lugs 21d and deforming from a cylindrical shape to a square tube shape during boiling sterilization, thereby preventing a decrease in the sealing performance between the cap 2 and the mouth part 10. In addition, since the density of the thermally crystallized part 13c is gradually decreased from the upper end 13a downward, it is possible to make it more difficult for a step to occur at the boundary between the straight part 13 and the shoulder part 14.

[0041] In order to verify the effect of the present invention, the outer diameter of the mounting part is 48.8 mm, the wall thickness of the mounting part is 3.5 mm, and the average density of the mounting part and the neck ring is 1.383 g / cm 3 A polyethylene terephthalate synthetic resin container with an internal volume of 190 g, with a straight section having a vertical height of 4.0 mm, and a density of 1.365 g / cm within a range of 75% (3.0 mm from the top end) downward from the top end of the straight section. 3 We prepared synthetic resin containers of the Examples, which had the above-mentioned thermal crystallization portion, a synthetic resin container of Comparative Example 1, which had no thermal crystallization portion on the straight portion, and a synthetic resin container of Comparative Example 2, which had a thermal crystallization portion only in a range of 37.5% (1.5 mm from the top end) downward from the top end of the straight portion.We then prepared each of these synthetic resin containers by filling them with hot water at 87°C, leaving a specified head space, then sealing the mouth with a metal cap and sterilizing them by boiling at 98°C for 20 minutes, and then cooling them to room temperature.

[0042] As a result, in the synthetic resin container of the embodiment, the deformation of the straight portion in the elongation direction was suppressed to 0.25 mm or less, and no abnormality occurred in the appearance or in the sealing property between the mouth and the cap.

[0043] In contrast, in the synthetic resin containers of Comparative Examples 1 and 2, the deformation in the elongation direction of the straight portion was large, at 8.45 mm and 1.05 mm, respectively, resulting in poor appearance of the mouth and an increase in the internal volume, which increased the degree of pressure reduction and caused unexpected deformation.

[0044] The present invention is not limited to the above-described embodiment, and it goes without saying that various modifications can be made without departing from the spirit and scope of the present invention.

[0045] For example, the synthetic resin container 1 can be used to store a variety of contents, not limited to food items such as jam.

[0046] In the above embodiment, the male thread 11a on the mouth portion 10 is a four-start thread, and the cap 2 is provided with four lugs 21d, but the number of threads on the male thread 11a and the number of lugs 21d can be changed in various ways as long as they are the same. Also, the cap 2 is not limited to being attached to the mouth portion 10 by a screw connection, and may be attached by other connection means such as an undercut connection. [Explanation of symbols]

[0047] 1. Plastic containers 2 Metal Cap 3. Container with cap 10 Mouth 11 Mounting part 11a Male thread 11b Stopper part 12 Neck Ring 13 Straight section 13a top end 13b Bottom edge 14 Shoulder 15 Torso 16 Bottom 21 Cap body 21a Ceiling wall 21b Surrounding wall 21c curl section 21d Rug 22 Liner material O axis S Storage space H Height dimension R Range

Claims

1. A cylindrical mouth portion; a shoulder portion integrally formed on a lower end of the mouth portion; a body portion integrally connected to a lower end of the shoulder portion; A synthetic resin container made of polyethylene terephthalate, comprising: The mouth portion has an attachment portion to which a cap is attached, A neck ring is provided integrally with the lower end of the mounting portion; A straight portion having a cylindrical outer shape is provided integrally with the lower end of the neck ring, The straight portion has a thickness of 1.365 g / cm 3 from 75% to less than 100% downward from the upper end. ３ A synthetic resin container characterized in that it has a thermal crystallized portion having a density of at least 1000 nm.

2. 2. The synthetic resin container according to claim 1, wherein the mounting portion has a wide mouth with an inner diameter of 35 mm or more.

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