JP2013159380A - Synthetic resin container - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a synthetic resin container of bottom structure with decompression absorbing performance that can surely cope with a large internal pressure change while the deformation of a bottom part in the internal pressure change is uniform and gentle in the synthetic resin container having the decompression absorbing performance at the bottom part.SOLUTION: A synthetic resin container includes a bottom part formed with an annular leg part having an outer peripheral wall extended from a body part, a grounding part and an inner peripheral wall, and a raised bottom part located above the grounding part on the inside from the inner peripheral wall of the leg part. The raised bottom part is projected downward from a root with the inner peripheral wall of the leg part, widened in width toward the outer peripheral side from the center part outer edge of the raised bottom part, and formed with a plurality of curved swelling parts formed with a plurality of swelling portions in a radial direction, equally in a circumferentially connected state.

Description

  The present invention relates to a synthetic resin container having a vacuum absorption performance at the bottom, and more particularly to a synthetic resin container having a bottom structure that can be deformed by a change in internal pressure.

  Synthetic resin containers are widely used as packaging containers for various liquids because they are excellent in light weight and impact resistance. In particular, a stretch-molded container formed by stretch-blow-molding polyethylene terephthalate (PET) has a combination of transparency, gas barrier properties, light weight, impact resistance, appropriate rigidity, etc., and is used for containing liquid contents. It is widely used as a packaging container, and the transition to a synthetic resin container is progressing also in the seasoning etc. which were filled with the glass bottle conventionally.

In order to improve the storage stability of the contents, hot filling of the contents is also widely performed in synthetic resin containers such as polyester, but in the synthetic resin containers due to the volumetric shrinkage of the contents due to cooling. Deformation will always occur under pressure. In order to prevent this, generally, a panel part is provided on a container body part via a rib part, and decompression deformation is absorbed by this panel part (Patent Document 1, etc.).
However, in the contents such as seasonings as described above, it is required to maintain the image of the appearance of the product that has been used for many years, such as sticking a roll label to a glass bottle. It is not desirable to provide the panel portion because labeling cannot be performed. In addition, if the body part is deformed improperly due to pressure reduction, it can be seen at a glance, and therefore it is desired to be able to cope with changes in internal pressure without affecting the appearance.

  In order to satisfy such a requirement, various synthetic resin containers having a vacuum absorption performance at the bottom without providing a vacuum absorption panel at the body have been proposed (Patent Documents 2 and 3).

Japanese Patent No. 2998559 Special table 2008-539141 JP 2008-178994 A

The synthetic resin container having the bottom shape described in Patent Documents 2 and 3 corresponds to the change in the internal pressure by reversing the bottom inclined surface around the fulcrum formed at the bottom, but absorbs the reduced pressure. If there is an uneven thickness on the radiation from the center of the bottom when producing the performance, a difference in strength occurs on the inclined surface of the bottom, causing non-uniform deformation, and stably achieving the desired vacuum absorption capacity. There is a possibility that it cannot be demonstrated.
In addition, the bottom shape described in Patent Document 3 requires a separate device for pushing the inverted inclined portion of the bottom upward during self-supporting conveyance. Furthermore, when the container is held and conveyed by a gripper or the like without pushing the reverse inclined portion of the bottom upward, the apparatus becomes complicated and the productivity may be inferior.

Accordingly, an object of the present invention is to provide a bottom made of a synthetic resin container having a reduced pressure absorption capability at the bottom, which has uniform and gentle deformation of the bottom due to a change in internal pressure and has a reduced pressure absorption capability that can reliably cope with a large change in internal pressure. It is to provide a synthetic resin container having a structure.
Another object of the present invention is to provide a synthetic resin container having no change in the appearance of the container due to a change in the internal pressure of the container, maintaining the self-sustainability of the container, and being excellent in transportability and productivity. .

  According to the present invention, the outer peripheral wall continuous from the trunk portion to the bottom, the annular leg portion including the grounding portion and the inner peripheral wall, and the raised bottom portion in which the inner side of the inner peripheral wall of the leg portion is located above the grounding portion. The raised bottom portion protrudes below the base of the inner peripheral wall of the leg portion and widens from the outer edge of the central portion of the raised bottom portion toward the outer peripheral side. In addition, a synthetic resin container is provided, in which a plurality of curved bulge portions in which a plurality of bulge portions are formed in the radial direction are equally formed in a state of being connected in the circumferential direction. .

In the synthetic resin container of the present invention,
1. The central part of the raised bottom part protrudes outward or inward of the raised bottom part,
2. The surface of the curved bulge is rough;
3. The surface of the inner peripheral wall of the leg is rough,
Is preferred.

In the synthetic resin container of the present invention, inside the annular leg formed at the bottom of the container, a raised bottom protruding downward, and the raised bottom wide from the outer edge of the central portion of the raised bottom toward the outer peripheral side. Since the plurality of curved bulging portions are formed equally in a state of being connected in the circumferential direction, the raised bottom portion can be deformed up and down in response to a change in internal pressure. Further, since the curved protruding portion is formed and the surface area of the raised bottom portion is increased, the raised bottom portion becomes thin, so that a movable region that can cope with a large change in internal pressure is secured and can be easily deformed. Become.
In addition, a large number of adjacent bulges on the raised bottom and a plurality of bulges extending in the radial direction on the curved bulge, thereby generating a compressive force applied to the raised bottom when the raised bottom is moved. Can be mitigated. As a result, when the internal pressure changes during absorption of the reduced pressure of the container and a stress acts on the raised bottom, the raised bottom can be moved gently toward the inside of the container while being uniformly bent and deformed. Thus, the desired vacuum absorption ability can be exhibited.
In addition, since a plurality of bulging portions are formed in the curved bulging portion in the radial direction, the raised bottom portion is easily deformed stepwise from the central portion toward the outer peripheral side, and the raised bottom portion is increased upward. It can be moved and can cope with a large change in internal pressure.
Further, the raised bottom portion is divided by a radial groove (intersection line) forming a curved bulge portion, or a plurality of bulge portions are partitioned by radial and circumferential grooves (intersection lines). Because the shape retention of the entire bottom is improved, even when the contents are hot filled in the container and the container is warmed while receiving a load due to the weight of the contents, the vapor pressure of the filled contents, etc. Therefore, even when the inside of the container becomes a positive pressure exceeding the atmospheric pressure, it is effectively prevented that the raised bottom portion abnormally bulges outward from the container.

In addition, by forming the central portion of the raised bottom portion so as to protrude outward or inward of the raised bottom portion, it becomes possible to further reduce the thickness of the central portion, and also to a greater change in internal pressure. It is possible to secure a movable region that can be accommodated and to further easily deform.
Further, the surface of the curved bulge formed on the raised bottom and the inner surface of the annular leg are formed to be rough, that is, the bottom metal used when molding the synthetic resin container of the present invention. Since the mold is roughened, the mold releasability can be improved even at the bottom of a complicated shape, and the productivity is excellent.
In the synthetic resin container of the present invention, since the annular leg portion that does not contribute to the absorption under reduced pressure is formed at the bottom, the height of the container can always be kept constant even when the internal pressure changes. At the same time, the independence of the container is maintained, and the transportability is excellent.
Further, in the synthetic resin container of the present invention, it is not necessary to form a panel for absorbing the reduced pressure in the body portion, so that appearance characteristics can be maintained and a label can be attached.

It is a side view which shows an example of the synthetic resin containers of this invention. It is a bottom view of the synthetic resin container shown in FIG. It is a partial sectional view for explaining the behavior of the bottom of the synthetic resin container shown in FIG. 1, (A) is an empty state, (B) is a state immediately after quasi-high temperature filling (for example, 72 ° C.), ( (C) is a diagram showing a decompressed state after filling (B), (D) is a diagram showing a decompressed state immediately after high temperature filling (for example, 85 ° C.), and (E) is a superposition of (A) to (D). FIG.

Preferred embodiments of the synthetic resin container of the present invention will be described based on specific examples shown in the accompanying drawings.
A synthetic resin container 1 according to the present invention shown in FIG. 1 (hereinafter also referred to as container 1) includes a mouth portion 2, a shoulder portion 3, a trunk portion 4 and a bottom portion 5, and the trunk portion 4 is an upper portion continuous from the shoulder portion 3. It consists of the trunk | drum 4a, the lower trunk | drum 4b connected to a bottom part, the center trunk | drum 4c located between the upper trunk | drum 4a and the lower trunk | drum 4b.
The central body portion 4c has three circumferential ribs 6, 6, and 6 formed in parallel and at equal intervals to ensure the mechanical strength of the body portion and the shape retaining property against internal pressure deformation. Further, the outer peripheral surface excluding the rib 6 portion is formed straight in the axial direction, and a label (not shown) can be wound around the trunk portion.
In the specific example shown in the figure, ribs 7 are also formed between the lower body 4b and the bottom 5, and the body 4 and the bottom 5 are clearly defined, but the body and the bottom are not necessarily clearly defined. It does not have to be.

The bottom part 5 is composed of an annular leg part 8 and a raised bottom part 9 located inside the annular leg part 8. The annular leg portion 8 is positioned below the rib 7 and forms a rising upward from the outer peripheral wall 8a, the grounding portion 8b, and the grounding portion 8b that continue from the body portion 4 so that the outer diameter of the container decreases as it goes downward. It consists of an inner peripheral wall 8c.
As is clear from FIGS. 1 and 3A, the raised bottom portion 9 is located above the grounding portion 8b and is directed from the base 8d of the annular leg portion 8 toward the central portion 10 of the raised bottom portion 9. It has a shape that protrudes downward.
2 and 3A, the central portion 10 of the raised bottom portion 9 is formed to be substantially flat, and curved bulging portions 12, 12,... Described later are connected to the outer edge thereof. In addition, a thick portion 10 b that is partitioned by a circle 10 a that is thicker than the thickness of the central portion 10 is formed at the central portion of the central portion 10.

In the present invention, as is apparent from FIGS. 1 and 2, the curved bulging portions 12, 12... Widened from the outer edge of the central portion 10 of the raised bottom portion 9 toward the outer peripheral side are equal in the circumferential direction. 12 rows per minute, connected in a state. The curved bulging portions 12, 12... Are curved surfaces protruding outward from the raised bottom portion 9, and the raised bottom portion 9 is formed by radial grooves (intersections, hereinafter omitted) 13, 13,. It is faced by partitioning. Further, in the specific example shown in the figure, the curved bulging portions 12, 12... Are partitioned by circumferential grooves (intersection lines, hereinafter omitted) 14, 14. Three substantially spherical bulging portions 12a, 12b, 12c projecting in the radial direction are formed in the radial direction.
Here, the curved bulging portion 12, the radial grooves 13, 13... And the circumferential grooves 14, 14 that partition the bulging portions 12 a, 12 b, 12 c formed in the curved bulging portion 12. ..., and the intersections 15, 15 ..., which are the points where the radial and circumferential grooves intersect, are when the adjacent curved bulges 12 and bulges 12a, 12b, 12c bend. Acts as a base point for
The bulging portions 12a, 12b, and 12c are obtained by adding notations a to c to the curved bulging portion 12 connected in the circumferential direction from the central portion 10 of the raised bottom portion 9 toward the outer peripheral side. is there.

With the above-described configuration, the raised bottom portion 9 on which a large number of adjacent curved bulge portions 12 are formed can move in the vertical direction in response to changes in internal pressure. Further, since the curved bulging portion 12 is formed and the surface area of the raised bottom portion 9 is increased, the raised bottom portion 9 is thinned, and a movable region that can cope with a large internal pressure change is secured and easily deformed. Is possible.
In addition, a plurality of adjacent bulging portions 12 adjacent to the raised bottom portion 9 and a plurality of bulging portions 12a, 12b, and 12c extending in the radial direction on the curved bulging portion 12 can be moved. It becomes possible to alleviate the influence of the compressive force on the raised bottom portion 9 that sometimes occurs. As a result, when the internal pressure changes during absorption of the reduced pressure of the container 1 and a stress acts on the raised bottom portion 9, the raised bottom portion 9 can be gently moved toward the inside of the container 1 while being uniformly bent and deformed. Thus, the desired reduced pressure absorption ability can be exhibited stably.

In addition, since the plurality of bulging portions 12a, 12b, and 12c are formed on the curved bulging portion 12 in the radial direction, the raised bottom portion 9 is easily deformed stepwise from the central portion toward the outer peripheral side, The raised bottom portion 9 can be moved largely upward, and can cope with a large change in internal pressure.
Further, the raised bottom portion 9 has a radial groove 13, 13... That forms a curved bulge portion 12, or a plurality of bulge portions 12a, 12b, 12c has a radial groove 13, 13,. Since the shape retention of the entire raised bottom portion 9 is improved by being partitioned by the circumferential grooves 14, 14,..., The contents are hot-filled in the container 1, and the load due to the weight of the contents Even when the container 1 is warmed while receiving, or even when the inside of the container 1 becomes a positive pressure exceeding the atmospheric pressure due to the vapor pressure of the filled contents, the raised bottom portion 9 is abnormal outside the container 1. It is effectively prevented from bulging.

In the synthetic resin container of the present invention, as is apparent from the behavior of the bottom corresponding to the change in internal pressure shown in FIGS. The raised bottom portion 9 having the curved bulging portion 12 in which the protruding portions 12a, 12b, and 12c are formed is deformed so as to be lifted inward of the container 1 while being uniformly bent and deformed, and exhibits reduced pressure absorption performance.
In the synthetic resin container of the present invention, as described above, the radial grooves 13, 13,..., The circumferential grooves 14, 14,. Since the raised bottom portion 9 having the curved bulging portion 12 in which the bulging portions 12a, 12b, and 12c are formed serves as a base point for exerting the reduced pressure absorption capability, the radial grooves 13, 13,... It is desirable to reduce the thickness of the circumferential grooves 14, 14... And the intersections 15, 15. As a result, the raised bottom portion 9 becomes more easily bent, and it becomes easier to move the raised bottom portion 9 toward the inside of the container 1.

In FIG. 3 for explaining the fluctuation | variation of the bottom part according to the internal pressure change of the synthetic resin container of this invention, (A) is an empty state, (B) is the state immediately after semi-high temperature filling (for example, 72 degreeC), ( (C) is a partial cross-sectional view showing a decompressed state after filling (B), (D) is a partially sectional view immediately after high temperature filling (for example, 85 ° C.), and (E) is a stack of (A) to (D). FIG.
In the synthetic resin container of the present invention, immediately after the contents are filled (B) regardless of the filling temperature, the raised bottom portion 9 moves below the empty state (A) due to the weight of the contents. However, when it is cooled after being filled and sealed at a sub-high temperature of 72 ° C. and is in a reduced pressure state (C), the raised bottom portion 9 moves slightly upward from the empty state (A). The state of projecting downward is maintained. Further, when it is cooled after being filled and sealed at a high temperature of 85 ° C. and is in a reduced pressure state (D), the central portion 10 of the raised bottom portion 9 is located above the root 8 d of the annular leg portion 8. The inner side of the bulging portion 12b is greatly raised upward.
Therefore, as apparent from FIG. 3 (E) formed by superimposing these drawings, in the synthetic resin container of the present invention, the curved bulging portion 12 of the raised bottom portion 9 itself is not removed when exhibiting the reduced pressure absorption ability. The composition having a conventional bottom bottom absorption capability is obtained by stepwise deformation so that the raised bottom portion 9 rises inward from the bulging portion 12a to 12c on the center side of the raised bottom portion 9 without inversion. As compared with the resin container, the vertical change of the raised bottom portion 9 is gentle, and the raised bottom portion 9 can be largely moved upward, which can cope with a large change in internal pressure. Thereby, the desired reduced pressure absorption ability can be exhibited while reducing the load on the bottom of the container due to the deformation of the bottom.

The synthetic resin container of the present invention is not limited to the specific examples described above, and various modifications can be made.
That is, in the specific example shown in the figure, there are 12 curved bulging portions 12 in the circumferential direction (the number of radial grooves is 12), and three bulging portions are 13a, 13b, 13c (grooves in the circumferential direction). However, the present invention is not limited to this, and the range of 6 to 24 in the circumferential direction (the number of grooves in the radial direction is 6), although not limited to this. The range of 1 to 5 in the radial direction (the number of grooves in the circumferential direction is in the range of 1 to 5), the surface area of the raised bottom 9 is increased and the thickness is reduced. Therefore, it is desirable from the viewpoint of formability while securing a movable region that can cope with a large change in internal pressure.
Here, when the number of the curved bulging portions in the circumferential direction is less than 6, there is a risk that the radial groove serving as a base point when the raised bottom portion bends is not effectively formed as compared with the case where the curved bulging portion is within the above range. If the number of curved bulges exceeds 24 in the circumferential direction, the groove in the radial direction becomes shallower than in the above range, so that the raised bottom becomes difficult to bend and the reduced pressure absorption capacity decreases. There is a fear. In addition, when the number of bulging portions in the radial direction exceeds 6, the degree of freedom of the shape formed on the raised bottom becomes higher than that in the above range, and it is nonuniform (for example, asymmetrical) during decompression deformation. ) There is a risk of deformation.

Further, it is desirable that the intervals (radial widths) between the plurality of bulging portions are substantially equal intervals in order to cause uniform deformation.
Note that the shape of the curved bulging portion depends on the shape of the raised bottom portion because the raised bottom portion is divided by the number of the above ranges.

The raised bottom part preferably has an outer diameter of 85 to 95% of the diameter of the grounding part of the bottom part, in order to ensure the self-supporting property of the container and the vacuum absorption performance. Further, the central portion of the raised bottom portion preferably has an outer diameter of 20 to 35% of the outer diameter of the raised bottom portion.
Further, in the specific example shown in the figure, the central portion 10 of the raised bottom portion 9 is formed to be substantially flat, but it may protrude outward or inward from the raised bottom portion. It is possible to reduce the thickness, and to exhibit a greater reduced pressure absorption performance.
Further, in the synthetic resin container of the present invention, it is preferable that the thickness of the bottom portion is equal to or less than the thickness of the thinnest portion of the trunk portion, and depending on the diameter of the raised bottom portion, It is desirable that the thickness is reduced to a range of 2 to 0.3 mm.

In the present invention, the shape of the raised bottom portion cannot be determined in general depending on the size of the container, but in this embodiment, the container height is 176 mm, the shoulder and bottom outermost diameter is φ65.5 mm, and the outside of the central torso A synthetic resin container having a diameter of 60.5 mm and a biaxial stretch blow molding capacity of 400 ml, and as shown in FIG. 3, the vertical distance h1 from the ground contact portion 8b of the annular leg 8 to the root 8d is 9 mm, The raised bottom portion 9 is formed so that a vertical distance h2 from the grounding portion 8b to the central portion 10 of the raised bottom portion 9 is 4 mm in a state where the container 1 is empty. Here, it is preferable that the vertical distance h1 is in the range of 3 to 15 mm, the container 1 is empty, and the vertical distance h2 is in the range of 2 to 10 mm.
Here, if the vertical distance h1 is less than 3 mm, the raised bottom may protrude from the grounding part due to thermal deformation during hot filling, and if the vertical distance h1 exceeds 15 mm, bottom molding is difficult. There is a risk of becoming.
If the vertical distance h2 is less than 2 mm, the raised bottom may protrude from the grounding portion due to thermal deformation during hot filling, as in the case described above, and the vertical distance h1 and the vertical distance It is preferable that the vertical distance h2 does not exceed 10 mm because securing the h2 distance of 5 mm or more is suitable for the raised bottom portion 9 to exhibit the reduced pressure absorption capability.

In the synthetic resin container of the present invention, as long as it has the bottom shape described above, it can be molded by a conventionally known method for producing a synthetic resin container, but it enables vertical movement of the raised bottom due to the change in the internal pressure of the container. In the above, since it is important that the raised bottom portion is thin, it is preferable that the raised bottom portion 9 is formed by a stretch blow molding method capable of forming a thin wall.
In stretch blow molding, a preform made of a thermoplastic polyester resin such as polyethylene terephthalate is molded using a bottom mold capable of shaping the bottom shape described above into a container bottom.
In this case, the curved bulging portions 12, 12... And the plurality of bulging portions 12a, 12b, 12c are composed of radial grooves 13, 13... And circumferential grooves 14, 14. Since the concavo-convex shape is formed on the bottom, it is preferable that the bottom mold has a rough surface in order to improve the releasability of the bottom mold. In particular, since the surface of the curved bulging portions 12, 12... And the portion corresponding to the inner peripheral wall 8c of the annular leg portion 8 may be uneven, it may be difficult to perform die cutting. From the viewpoint of releasability, it is preferable that the bottom mold portion corresponding to is roughened. Therefore, even in the molded synthetic resin container, the surfaces of the curved bulging portions 12, 12... And the surfaces of the inner peripheral walls 8c of the annular legs 8 that are in contact with the bottom mold are formed to be rough. The

For the synthetic resin container of the present invention, thermoplastic polyester resins that have been conventionally used for stretch blow molding, particularly ethylene terephthalate thermoplastic polyesters are advantageously used. Of course, such as polybutylene terephthalate, polyethylene naphthalate, etc. Other polyesters or blends with polycarbonate or arylate resin can also be used.
In addition to a single layer of the thermoplastic polyester resin, it may have a multilayer structure of the thermoplastic polyester resin and a gas barrier resin or an oxygen-absorbing resin, and has heat resistance that can withstand hot filling at high temperatures. In order to give, it is preferable that the mouth part of the preform to be used is thermally crystallized.
Also, the stretch blow molding conditions can be molded under conventionally known molding conditions as long as a bottom mold capable of imparting the above-described shape to the bottom can be used, and can be molded by two-stage blow molding in addition to single-stage blow molding. It is preferable that it is heat-set from the viewpoint of heat resistance.

In the synthetic resin container of the present invention, since a vacuum absorbing function is given to the bottom that does not affect the container appearance, a container image that is filled by hot filling and a roll label is attached to the trunk is established. It can be effectively used as a seasoning container.
In addition to such contents, the present invention can also be applied to contents that are hot-filled at a relatively high temperature.

  DESCRIPTION OF SYMBOLS 1 Synthetic resin container (container), 2 mouth part, 3 shoulder part, 4 trunk | drum, 5 bottom part, 6 rib, 8 leg part, 9 raised bottom part, 10 center part, 12 curved bulging part, 12a, 12b, 12c Swelling part 13 Groove in radial direction 14 Groove in circumferential direction 15 Intersection point.

Claims (4)

  Synthetic resin in which an outer peripheral wall continuous from the trunk portion, an annular leg portion consisting of a grounding portion and an inner peripheral wall, and a raised bottom portion, the inner side of which is located above the grounding portion, are formed above the inner peripheral wall of the leg portion. The raised bottom portion protrudes downward from the base of the inner peripheral wall of the leg portion, widens from the outer edge of the central portion of the raised bottom portion toward the outer peripheral side, and extends in the radial direction. A synthetic resin container characterized in that a plurality of curved bulging portions formed with a plurality of bulging portions are equally formed in a state of being connected in the circumferential direction.   The synthetic resin container according to claim 1, wherein a central portion of the raised bottom portion protrudes outward or inward of the raised bottom portion.   The synthetic resin container according to claim 2, wherein a surface of the curved bulging portion is a rough surface.   The synthetic resin container according to any one of claims 1 to 3, wherein a surface of an inner peripheral wall of the leg portion is a rough surface.

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