JP6830235B2 - Synthetic resin container - Google Patents

Description

The present invention relates to a synthetic resin container, particularly a synthetic resin container having a device for suppressing the shape of the container from being damaged when the pressure inside the container is reduced.

Conventionally, containers made of synthetic resin (PET bottles) made of synthetic resin materials such as PET have been distributed as containers for storing liquids, and many of them are containers for storing beverages and liquid seasonings. It's being used.

Depending on the type of beverage or liquid seasoning to be filled, heat filling is performed. In this heat filling, the volume of the container decreases when the temperature of the container drops due to heat dissipation after the high temperature container is filled and capped, and the gas portion remaining in the mouth and shoulder of the container. As the volume of the container decreases and the inside of the container becomes decompressed, the peripheral wall of the container body is deformed such as a dent, and the appearance of the container is easily spoiled.

Therefore, in synthetic resin containers, many devices have been proposed in which a movable panel that absorbs decompression is provided in the body of the container, and the decompression is absorbed by denting the panel inward to reduce the decompression in the container. .. However, since this type of container has a panel on the body around which the label is wrapped, in a container that does not like it, the bottom is recessed inward to reduce the decompression inside the container. A container has been proposed in which the pressure is reduced, the pressure is absorbed, and the pressure is released when the cap is opened to return to the original bottom shape.

For example, as shown in Patent Document 1, the bottom wall portion at the bottom of the container is formed by a peripheral ground contact portion, a rising peripheral wall portion that continuously rises upward inward in the container radial direction of the ground contact portion, and this rise. An annular movable portion continuously extending inward in the container radial direction and a convex concave portion continuously upward from the inside of the movable portion in the container radial direction are provided at the upper end of the peripheral wall portion. A container in which a movable portion is raised so as to move the recessed portion upward and is rotatable in the vertical direction around the upper end portion of the peripheral wall portion is shown.

Japanese Patent No. 5489953

By the way, in recent years, when recycling used containers or disposing of them as waste, it is desired to recycle or reduce the amount of waste, and it is desired to minimize the adverse effect on the environment when incineration is performed. There is. From this point of view, it is considered to reduce the wall thickness of the peripheral wall portion of the body of the container to reduce the amount of the synthetic resin material used.

However, in the conventional container having a structure in which the state of decompression in the container is reduced by moving the movable portion of the bottom portion upward, the weak portion of the thinned container may be deformed.

In addition, when the container filled with high temperature cools and the volume decreases, and the cap of the container in the absorbed state is opened by moving the bottom to the upper part of the container due to the reduced pressure generated by it, the inside of the container becomes atmospheric pressure. Therefore, there is a problem that the bottom of the container, which has moved upward, returns to the original lower shape, and the liquid level of the head space of the container in the container is lowered, giving the consumer the impression that the container is small. ..

Therefore, in view of the above circumstances, in view of the above circumstances, when the internal pressure of the container capped by filling the container at a high temperature is reduced by heat dissipation of the container, the reduced pressure state in the container progresses, so that the container body An object of the present invention is to suppress the occurrence of distorted deformation and dents by denting deformation of the bottom of the container, and an object of the present invention is to provide a synthetic resin container in which the appearance shape of the body of the container is appropriately maintained. In addition, when the container that has absorbed the decompression due to the dented deformation movement of the bottom of the container is opened, the bottom surface is prevented from returning to the state before the deformation under the atmospheric pressure state, and the liquid level of the container is lowered. The purpose is to provide a container without air pressure.

(Invention of claim 1)
The present invention has been made in consideration of the above problems, a container mouth (2) and the shoulder (3) and body portion (4) and the bottom (5) consisting of a synthetic resin, said bottom ( 5) consists of a bottom outer peripheral wall portion (9) and a bottom wall portion (10) .
The bottom wall portion (10) has a rising peripheral wall portion (12) that continuously rises upward in the container radial direction of an annular ground contact portion located on the outer periphery of the bottom wall portion (10). ,
The wall area surrounded by the rising peripheral wall portion (12) on the bottom wall portion (10) is deformed so as to move in the vertical direction, and the distance between the ground contact surface (15) on which the container is placed and the wall region changes. In the possible synthetic resin container (1)
In the wall area surrounded by the rising peripheral wall portion (12 ) at the bottom wall portion (10) ,
When the pressure inside the container is decompressed, the pressure inside the container is changed by self-deformation, and the pressure inside the container is reversed to absorb the decompression inside the container. A decompression absorbing means (14) that maintains its shape is provided.
The decompression absorption means (14)
It is inclined downward from the upper end portion (13) of the rising peripheral wall portion (12) on the container center side, and rotates in the vertical direction around the upper end portion (13) of the rising peripheral wall portion (12). An annular first plate surface (18) that is possible, and
The bottom central concave wall (17), which is convex upward and through which the central axis of the container passes,
From the lower end portion (19) of the bottom central concave wall portion (17), the first portion is extended in a direction orthogonal to the container central axis toward the rising peripheral wall portion (12) side and parallel to the ground contact surface (15). The first plate surface portion (18), which is connected to the inside of the plate surface portion (18) in the container radial direction via the connecting portion (21) and receives a pulling force upward of the container when the inside of the container is depressurized, is inverted upward. It consists of an annular second plate surface (20) that generates a resistance force in the direction of suppressing dented movement.
When the pulling force received by the first plate surface portion (18) exceeds the drag force from the second plate surface portion (20), the first plate surface portion (18) becomes the upper end portion of the rising peripheral wall portion (12). From a state in which the connecting portion (21), which is inclined downward with respect to (13) and arranged in the circumferential direction of the center axis of the container, has a curved shape in which the cross-sectional shape is convex downward. In a state where the one plate surface portion (18) is inclined upward in the container, the connecting portion (21) arranged in the circumferential direction of the central axis of the container becomes a curved shape in which the cross-sectional shape is convex upward and is inverted and recessed. A second plate surface portion (20) and a bottom center concave wall portion (17) that rotate and are connected to the first plate surface portion (18) and the first plate surface portion (18) via the connecting portion (21). Moves upside down in the container and moves
When the pressure inside the container is set to the atmospheric release pressure, the first plate surface portion (18) in a state of being inclined upward in the container and the curved connecting portion (21) having a convex cross-sectional shape upward are the first. It has a configuration in which the inverted recessed state is maintained, which is composed of a second plate surface portion (20) connected to the plate surface portion (18) via the connecting portion (21) and a bottom center concave wall portion (17). It is intended to solve the above-mentioned problems by providing a characteristic synthetic resin container.

(Effect of the invention of claim 1)
According to the invention of claim 1, when the temperature of the hot-filled container changes in the cooling direction and the pressure inside the container is reduced, the bottom is inverted before the body is deformed. Since the volume reduction can be generated at once, the appearance of the container is not spoiled.

Therefore, the thickness of the peripheral wall portion of the body portion can be reduced, and the amount of the synthetic resin material used for molding the container can be reduced, which is an excellent effect.

Further , according to the present invention, in addition to the effect of the invention of claim 1, when the container in which the decompression is absorbed by the upward movement of the bottom wall portion is opened, the bottom wall portion is in the state before deformation even in the atmospheric pressure state. Since it does not return and maintains the inverted recessed state after deformation, it has the effect that the liquid level of the container whose volume has been reduced by cooling does not decrease.

Further , according to the present invention, the decompression absorbing means has an annular first plate surface portion, and the first plate surface portion rapidly reverses and rotates from a downwardly inclined state to an upwardly inclined state. Since it moves from the lower position (height position close to the ground plane) to the upper position (height position away from the ground plane) including the connecting part, increase the degree of sudden change of the decompression absorbing means. This has the effect of preventing the container body and the like from being distorted and dented.

Further , according to the present invention, when the pulling force received by the first plate surface portion exceeds the drag force from the second plate surface portion, the first plate surface portion reversely rotates and is connected to the second plate. Both the face part and the bottom center concave wall part move to the upper part of the container, and the annular first plate surface part in a state of being inclined downward becomes a state of being inverted and inclined upward, and the pressure inside the container becomes the atmospheric release pressure. At that time, the inverted state of the first plate surface portion is preferably maintained, and there is an effect that the liquid level of the contained material does not drop when the package is opened.

It is explanatory drawing which shows an example of embodiment of the synthetic resin container which concerns on this invention. It is explanatory drawing which shows the bottom part in one example in the cross section. It is explanatory drawing which shows the state which the bottom | bottom in one example is seen from the bottom. It is a graph which shows the transition of the bottom depth at the time of change of the internal pressure of the decompression absorption means. It is explanatory drawing which shows the position of the bottom depth A and the bottom depth B in the graph of FIG. It is explanatory drawing which shows the inclination of the 1st plate surface portion and the length along the inclination direction of the 1st plate surface portion in one example. It is explanatory drawing which shows the example which provided the protrusion part on the plate surface part of the bottom part of a container.

Next, the present invention will be described in detail based on the embodiments shown in FIGS. 1 to 7. In the figure, 1 is a container made of synthetic resin, and the container 1 is blow-molded in a bottle shape using a synthetic resin such as PET as a material.

As shown in FIG. 1, the synthetic resin container 1 is composed of a mouth portion 2, a shoulder portion 3, a body portion 4, and a bottom portion 5, and a cap (not shown) is put on the mouth portion 2. It is a container that can be closed.

(Body)
The body portion 4 continuous with the shoulder portion 3 whose diameter increases as it goes down toward the lower part of the container has a cylindrical shape, and the peripheral wall portion 6 of the body portion 4 is provided for reinforcement at intervals in the container height direction. A plurality of concave grooves 7 are provided, and the concave grooves 7 are continuous in the circumferential direction.

Further, the body portion 4 forms a step portion 8 at a position close to the boundary with the shoulder portion 3 where the upper end portion of the body portion is continuous and at a position close to the boundary with the bottom portion 5 where the lower end portion of the body portion is continuous. The outer diameter of the body 4 is slightly smaller than the outer diameter of the shoulder 3 and the bottom 5, so that a packaging label (not shown) can be stably arranged around the body 4. ..

(bottom)
The bottom portion 5 continuous with the body portion 4 via the step portion 8 is continuous with the bottom outer peripheral wall portion 9 forming the outer peripheral surface of the bottom portion 5 and the lower end of the bottom outer peripheral wall portion 9, and serves as the lower surface of the container. It is composed of a bottom wall portion 10 formed.

As shown in FIG. 2, the bottom wall portion 10 is located on the outer periphery of the bottom wall portion 10 and is continuous with the lower end of the bottom outer peripheral wall portion 9, the ground contact portion 11, and the container radial direction in the ground contact portion 11. It has a rising peripheral wall portion 12 that continuously rises upward inwardly. A decompression absorbing means 14 continuous with the upper end portion 13 of the rising peripheral wall portion 12 is provided as a wall region of the portion surrounded by the rising peripheral wall portion 12.

(Decompression absorption means)
The wall region surrounded by the rising peripheral wall portion 12 which is the decompression absorbing means 14 is deformed so as to move in the vertical direction of the container, and the distance from the ground contact surface 15 on which the container is placed can be changed. It is a part, and as described above, after the high temperature container is filled and capped, the temperature of the container decreases, and the volume of the container decreases accordingly, compared with the pressure in the container immediately after the high temperature filling. Even if the pressure starts to be reduced, the shape of the peripheral wall portion 6 of the body portion 4 plays a role of preventing the shape from being damaged by deformation or dents.

Then, the decompression absorbing means 14 changes the distance from the ground contact surface 15 when the pressure inside the container changes when the inside of the container is decompressed so that the shape of the peripheral wall portion 6 of the body portion 4 is not impaired. It is provided so as to perform a deformation operation in which the container is instantly inverted and recessed by self-deformation.

In the synthetic resin container 1 of the present embodiment, the decompression absorbing means 14 is continuous from the upper end portion 13 of the rising peripheral wall portion 12 toward the inside in the container radial direction, and is centered on the position of the upper end portion 13. An annular first plate surface portion 18 that can be moved in the vertical direction of the container 1, an annular second plate surface portion 20 parallel to the ground contact surface connected to the first plate surface portion 18, and the second plate surface portion 20. It is composed of a bottom central concave wall portion 17 that is continuous from the inside in the container radial direction and is convex upward.

(Bottom center concave wall)
As shown in FIGS. 1, 2, and 3, the bottom center concave wall portion 17 passes through the container central axis OO, extends upward from the lower end portion 19, and tapers in a tapered shape. It is composed of a peripheral wall portion 22 having a circumferential shape and a top wall portion 23 continuous with the upper end portion of the peripheral wall portion 22, and when the first plate surface portion 18 moves in the vertical direction of the container, the bottom center concave wall portion 17 is formed. Will move in the vertical direction of the container along with the second plate surface portion 20.

As described above, in the decompression absorbing means 14, since the first plate surface portion 18 and the second plate surface portion 20 formed in an annular shape around the bottom central concave wall portion 17 are arranged concentrically, the decompression absorbing means 14 is used. There is a plate-like object having tension in the spreading direction of the surface toward the center of the bottom portion 5 (container center axis OO) and in the spreading direction of the surface extending in the circumferential direction of the bottom central concave wall portion 17. It will be.

Then, as described above, the first plate surface portion 18 having the tension is rotatably oriented in the vertical direction of the container with respect to the upper end portion 13 of the rising peripheral wall portion 12 toward the container center side. It is inclined downward from the container, and when the internal pressure of the container 1 is reduced (when the pressure inside the container is depressurized), the distance from the ground contact surface 15 to the second plate surface portion 20 becomes small. From the lower position state 24, which is present, to the upper position state 25, where the distance from the ground contact surface 15 to the second plate surface portion 20 is large, the container is inverted and recessed by self-deformation, and the distance becomes large at once and is accommodated. It is provided so that the inverted recessed state is maintained even when the cap is opened while the object is cooled and the pressure is released to the atmosphere.

That is, in the decompression absorbing means 14, when the pressure inside the container changes in the direction in which the pressure inside the container is reduced, the first plate surface portion 18 is separated from the ground surface 15 from a lower position close to the ground surface 15. It is provided so as to move to the upper position instantly, and as shown in the graph of FIG. 4, the fluctuation of the distance from the ground plane 15 with respect to the degree of decompression is self-deformation and has a stepped shape as shown in d of FIG. It performs a deformation operation that changes to.

The mechanism for instantaneously moving from the lower position to the upper position is as follows. As shown in FIGS. 2 and 3 , the annular first plate surface portion 18 inclined downward is continuous with the annular second plate surface portion 20 via the connecting portion 21 arranged in the circumferential direction of the container center axis. Since the second plate surface portion 20 is a plate material arranged parallel to the ground plane 15, that is, in the direction orthogonal to the container central axis OO, the pulling force upward of the container is applied when the pressure is reduced. It plays the role of a resistance member that generates a resistance force in the direction of suppressing the upward movement of the first plate surface portion 18 to be received.

Then, when the pressure is reduced from the pressure immediately after filling and the pulling force received by the first plate surface portion 18 exceeds the drag force from the second plate surface portion 20, the first plate surface portion 18 rises to the peripheral wall portion 12. once it rotated upward by the upper end portion 13 to the center, thus,
As shown in FIG. 2, the first plate surface portion 18 which is inclined downward with respect to the upper end portion 13 of the rising peripheral wall portion 12 and the container center axis are arranged in the circumferential direction and the cross-sectional shape is convex downward. From the lower position state 24 consisting of the connecting portion 21 in a curved shape, the second plate surface portion 20 parallel to the ground contact surface 15, and the bottom center concave wall portion 17 .
The first plate surface portion 18 that is inclined upward in the container, the connecting portion 21 that is arranged in the circumferential direction of the container center axis and has a curved cross-sectional shape that is convex upward, and the above-mentioned parallel to the ground contact surface 15. The self-deformation that instantly moves to the upper position state 25 including the second plate surface portion 20 and the bottom center concave wall portion 17 is performed.

In particular, in the decompression absorbing means 14, since the first plate surface portion 18, the connecting portion 21, and the second plate surface portion 20 are arranged concentrically, the deformation operation that occurs when the pressure inside the container is reduced and the pressure inside the container changes. The transition is as follows.

(Bottom depth graph)
The variation of the decompression absorption means 14 of the container 1 according to the above embodiment is shown below. FIG. 4 is a graph showing the transition of the depth when the internal pressure changes, and as shown in FIG. 5, the bottom center concave wall portion 17 is in contact with the bottom center of the top wall portion 23 (the portion corresponding to the gate position at the bottom of the bottle). The distance to the ground 15 is defined as the bottom depth A, and the distance from the lower surface of the second plate surface portion 20 to the ground surface 15 is defined as the bottom depth B, indicating the transition of the bottom depth when the internal pressure changes.

In the graph of FIG. 4, the vertical axis is the bottom depth (mm) and the horizontal axis is the bottle internal pressure (kPa). Then, in the graph showing the variation form of the decompression absorption means 14, first, in the portion of transition a, the decompression absorption means 14 is in the lower position state 24 and the container 1 is depressurized in the container. It is the transition of the bottom height when the pressure inside the container changes under the negative pressure state where the decompression is promoted. The starting point of transition a is the same as the pressure inside the container and the air pressure outside the container.

In the part of transition b, following transition a, the pressure inside the container is pressurized with respect to the air pressure outside the container by lowering the negative pressure level inside the container, and the pressure is increased. This is the transition of the bottom height when the pressure inside the container changes until the pressure inside the container becomes positive with respect to the pressure outside the container.

In the part of transition c, following transition b, the pressure inside the container is further increased in a positive pressure state with respect to the atmospheric pressure outside the container, and the pressure is further increased in a positive pressure state. It shows the transition of the bottom height when the pressure inside the container changes.

(Stepped transition d)
Then, as shown in the above transition a, the distance fluctuates when the decompression inside the container is progressing under the negative pressure state where the pressure inside the container is lower than the air pressure outside the container. The decompression absorbing means 14 performs a deformation operation in which the fluctuation of the distance from the ground contact surface 15 changes in a stepwise manner due to self-deformation so that the stepwise transition d of is suddenly changed from the lower position state 24 to the upper position state 25. It has been shown to change to.

(Stepped transition e)
Further, as shown in the above transition c, the distance fluctuates when the pressure inside the container is increasing under the positive pressure state where the pressure inside the container is higher than the air pressure outside the container. The decompression absorbing means 14 performs a deformation operation in which the fluctuation of the distance from the ground contact surface 15 changes in a stepwise manner due to self-deformation so that the stepped transition e of the above position is suddenly changed from the upper position state 25 to the lower position 24. It has been shown to change. From this figure, in the state where the distance suddenly fluctuates due to decompression, when the cap is opened and the internal pressure of the container becomes the same as the atmospheric pressure (bottle internal pressure 0 kPa), it does not return to the original position before reversal, and it is in a recessed state ( It can be seen that the state shown in the upper position state 25 in FIG. 2) is maintained, and the original state is restored by further pressurizing.

In the synthetic resin container 1 of the present invention having the decompression absorbing means 14 at the bottom 5, after accommodating and capping a high-temperature container, the temperature of the container changes in the direction of cooling and the pressure inside the container is reduced. It will be in a state of being. Then, in the present container 1, the decompression absorbing means 14 does not gradually change from the lower position close to the ground plane to the upper position away from the ground plane, but suddenly changes as described above. .. As a result, there is no continuous formation of dents or deformations due to the continuous application of the depressurizing force to the peripheral wall portion of the body portion, and there is an effect that the appearance of the container is not spoiled.

In the synthetic resin container 1 for a filling amount of 300 ml and the synthetic resin container 1 for a filling amount of 500 ml, the angle θ1 between the rising peripheral wall portion 12 and the first plate surface portion 18 of the decompression absorbing means 14 with respect to the horizontal plane. For example, the angle of inclination (depression angle) θ2 of the first plate surface portion 18 downward toward the center of the container and the length D along the inclination direction of the first plate surface portion 18 should be a combination of the values shown below. Is good.

In FIG. 6, the angle between the rising peripheral wall portion 12 and the first plate surface portion 18 of the decompression absorbing means 14 is θ1, the angle of inclination of the first plate surface portion 18 downward on the container center side is θ2, and the first plate. The length of the surface portion 18 along the inclination direction is shown as D. Further, the synthetic resin container 1 for a filling amount of 300 ml has a bottle outer diameter of 60 mm and the diameter of the decompression absorbing means 14 is 49 mm, and the synthetic resin container 1 for a filling amount of 500 ml has a bottle outer diameter of 72 mm and the decompression absorbing means 14 The diameter of is 60 mm.

(300 ml container)
θ1 = 70 °, θ2 = 25 °, D = 10mm
θ1 = 78 °, θ2 = 17 °, D = 9mm
θ1 = 85 °, θ2 = 8 °, D = 9mm

(500 ml container)
θ1 = 77 °, θ2 = 18 °, D = 12mm
θ1 = 82 °, θ2 = 13 °, D = 12mm
θ1 = 87 °, θ2 = 8 °, D = 11mm

In the present invention, the first plate surface portion 18 reverses and rotates due to the depressurization, and the bottom wall portion 10 moves upward of the container 1 to reduce the internal volume of the container and absorb the decompression, but the movement of the bottom wall portion 10 The change in the internal volume due to the above is the angle between the rising peripheral wall portion 12 and the first plate surface portion 18 of the decompression absorbing means 14, the angle of inclination of the first plate surface portion 18 downward toward the center of the container, and the first plate. Since it is generally determined by the length along the inclination direction of the surface portion 18, such a numerical value is determined to be a suitable numerical value according to the filling temperature condition, the size of the container, the wall thickness of the container, and other conditions related to strength. Although not limited, in the present invention, particularly in a bottle having a container shape of 250 to 1000 ml, particularly in a bottle having a container shape of 300 to 500 ml, θ2 of the inversion site is in the range of 7 to 26 °, more preferably. 8 to 25 ° is suitable, and if it is smaller than this range, the self-deformation state when deformed by decompression is not stable, and if it is too large beyond the above range, it becomes more due to inversion due to self-deformation. It requires a large decompression force and may cause unfavorable deformation in other parts of the container.

Then, by setting the inclination angle of the first plate surface portion 18 to the above-mentioned angle with respect to the horizontal plane, the inversion of the first plate surface portion 18 inward of the container proceeds better without affecting other parts of the container. Moreover, the shape is well maintained even in the state of open pressure to the atmosphere, and the decrease in the internal volume of the container due to inversion can be set appropriately large, so that there is an effect that a sufficient decompression absorption effect can be obtained.

FIG. 7 shows a shape in which convex protrusions 26 are provided on the first plate surface 18 at the bottom of the container at intervals in a spiral shape toward the inside of the container. In the present invention, when the first plate surface portion 18 is inverted, the plate surface is deformed, but it becomes the starting point of the deformation at that time, disperses the force, is more easily deformed, and is not preferable to the plate surface due to the deformation. It has the effect of preventing deformation marks and the like from remaining. By arranging a plurality of such protrusions 26 on the second plate surface portion 20, the same effect as described above can be obtained even in the deformation including the second plate surface portion 20.

1 ... Synthetic resin container 4 ... Body 5 ... Bottom 6 ... Peripheral wall of the body 9 ... Bottom outer wall 10 ... Bottom wall 11 ... Grounding 12 ... Rising peripheral wall 13 ... Upper end of rising peripheral wall 14 ... Decompression absorption means 15 ... Grounding surface 17 ... Bottom center concave wall 18 ... First plate surface 19 ... Bottom center concave wall 20 ... Second plate surface 21 ... Connecting 22 ... Bottom center concave wall peripheral wall 23 ... Top wall part of the bottom center concave wall part 24 ... Lower position state 25 ... Upper position state 26 ... Protrusion

Claims (1)

It is a container made of synthetic resin consisting of a mouth (2) , a shoulder (3) , a body (4), and a bottom (5) , and the bottom (5) is a bottom outer peripheral wall (9) and a bottom wall. It consists of (10)
The bottom wall portion (10) has a rising peripheral wall portion (12) that continuously rises upward in the container radial direction of an annular ground contact portion located on the outer periphery of the bottom wall portion (10). ,
The wall area surrounded by the rising peripheral wall portion (12) on the bottom wall portion (10) is deformed so as to move in the vertical direction, and the distance between the ground contact surface (15) on which the container is placed and the wall region changes. In the possible synthetic resin container (1)
In the wall area surrounded by the rising peripheral wall portion (12 ) at the bottom wall portion (10) ,
When the pressure inside the container is decompressed, the pressure inside the container is changed by self-deformation, and the pressure inside the container is reversed to absorb the decompression inside the container. A decompression absorbing means (14) that maintains its shape is provided.
The decompression absorption means (14)
It is inclined downward from the upper end portion (13) of the rising peripheral wall portion (12) on the container center side, and rotates in the vertical direction around the upper end portion (13) of the rising peripheral wall portion (12). An annular first plate surface (18) that is possible, and
The bottom central concave wall (17), which is convex upward and through which the central axis of the container passes,
From the lower end portion (19) of the bottom central concave wall portion (17), the first portion is extended in a direction orthogonal to the container central axis toward the rising peripheral wall portion (12) side and parallel to the ground contact surface (15). The first plate surface portion (18), which is connected to the inside of the plate surface portion (18) in the container radial direction via the connecting portion (21) and receives a pulling force upward of the container when the inside of the container is depressurized, is inverted upward. It consists of an annular second plate surface (20) that generates a resistance force in the direction of suppressing dented movement.
When the pulling force received by the first plate surface portion (18) exceeds the drag force from the second plate surface portion (20), the first plate surface portion (18) becomes the upper end portion of the rising peripheral wall portion (12). From a state in which the connecting portion (21), which is inclined downward with respect to (13) and arranged in the circumferential direction of the center axis of the container, has a curved shape in which the cross-sectional shape is convex downward. In a state where the one plate surface portion (18) is inclined upward in the container, the connecting portion (21) arranged in the circumferential direction of the central axis of the container becomes a curved shape in which the cross-sectional shape is convex upward and is inverted and recessed. A second plate surface portion (20) and a bottom center concave wall portion (17) that rotate and are connected to the first plate surface portion (18) and the first plate surface portion (18) via the connecting portion (21). Moves upside down in the container and moves
When the pressure inside the container is set to the atmospheric release pressure, the first plate surface portion (18) in a state of being inclined upward in the container and the curved connecting portion (21) having a convex cross-sectional shape upward are the first. It has a configuration in which the inverted recessed state is maintained, which is composed of a second plate surface portion (20) connected to the plate surface portion (18) via the connecting portion (21) and a bottom center concave wall portion (17). Characterized synthetic resin container.