JP2010275014A - Synthetic resin bottle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resin bottle configured to exhibit a reduced-pressure absorbing function by the recessed deformation of a bottom wall which exhibits the reduced-pressure absorbing function sufficiently and effectively suppresses the progress of a fold, thereby to retain a self-standing property sufficiently and to create a bottle wall structure. <P>SOLUTION: In a synthetic resin bottle biaxially stretched blow molded, a protrusion that is formed by allowing the bottom wall to protrude below a circumferential edge and exerts a function as a grounding portion is arranged at the inner side of the circumferential edge of a bottom face of a bottom, and a recessed portion formed by recessing the bottom wall inward and upward with the inner side of the protrusion as a base end is arranged at the central portion, thereby constituting so that the reduced-pressure absorbing function is exerted by the recessed upper displacement of the bottom wall from the protrusion to the recessed portion by the progress of the recessed state of the inside, and the circumferential edge exerts a function as the grounding portion instead of the protrusion. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention has a synthetic resin casing, in particular, a body having a high shape retaining property, and when the inside is in a reduced pressure state, the reduced pressure is absorbed by the depressed deformation of the bottom wall of the bottom. The present invention relates to a synthetic resin casing.

  Conventionally, polyethylene terephthalate (hereinafter referred to as PET) resin biaxially stretched blow-molded casings, so-called PET bottles, have excellent transparency, mechanical strength, heat resistance, gas barrier properties, etc., and are used for various beverages. Widely used as a container. Conventionally, there is a so-called high-temperature filling method for filling a PET bottle with content liquids such as fruit juices and teas that require sterilization, and the contents liquid is filled into the casing at a temperature of about 90 ° C. Then, the cap is sealed and then cooled, and the inside of the housing is in a considerably reduced pressure state.

  For this reason, for applications involving high-temperature filling as described above, for example, as described in Patent Document 1, a so-called reduced-pressure absorption panel is formed, which is a region that can be easily deformed in a depressed state by depressurization intentionally in the trunk. Then, by deforming the reduced pressure absorption panel into a depressed shape at the time of depressurization, while maintaining a good appearance, it is possible to ensure rigidity as a casing in a portion other than the reduced pressure absorption panel, A so-called decompression absorption function is exhibited so as to prevent troubles in stacked storage, vending machines, and the like.

On the other hand, when it is necessary to avoid the formation of the vacuum absorption panel on the body due to the design requirements related to the appearance of the housing, or the vacuum absorption panel itself is a part that is easily bent and deformed, In applications where it is necessary to increase the surface rigidity and impart high shape retention to the barrel, or for sale in a vending machine, for example, as disclosed in Patent Document 2, without forming a vacuum absorbing panel on the barrel A synthetic resin casing made to exhibit a reduced pressure absorption function by the depression-like deformation of the bottom wall of the bottom is used.
In particular, in the case of a small casing of 350 ml or 280 ml, even if a vacuum absorbing panel is formed on the trunk, the area is limited, so that the rigidity and buckling strength of the trunk and the vacuum absorbing function are sufficiently compatible. This is difficult, and it is necessary to exert a reduced pressure absorption function by deformation of the bottom wall of the bottom as described above.

Here, the casing 101 shown in FIG. 10 is an example of a synthetic resin casing configured to exhibit a reduced-pressure absorption function due to the depression-like deformation of the bottom wall of the bottom 105, (a) is a front view, (B) is a bottom view.
In the casing 101, the wall thickness of the trunk portion 104 is increased, and the surface groove and buckling strength of the trunk portion 104 are increased by the circumferential groove rib 107. While maintaining the shape, the vacuum absorbing function is exhibited by further depression-like deformation (deformation in the direction of the arrow in FIG. 10A) of the depression 115 of the bottom 105.

Japanese Patent Laid-Open No. 08-048322 JP 2007-269392 A

However, the housing 101 of the type shown in FIG. 10 is also required to reduce the thickness of the housing in order to save resources and reduce costs. As further depression-like deformation progresses,
While the depression deformation in the depression 115 does not proceed uniformly over the entire circumference, as shown in the bottom view of FIG. 10B, while forming a number of folds V in the radial direction and the circumferential direction, The crease V advances to the peripheral portion 112 that is unevenly advanced and is arranged at the peripheral portion of the bottom portion 105 and that functions as a grounding portion, impairing the appearance, and further, the housing 101 is self-supporting. There is a problem that it results in a loss of performance.

In order to solve the above-described problems in the prior art, the present invention sufficiently exhibits the reduced-pressure absorption function and is sufficiently self-supporting in the casing that exhibits the reduced-pressure absorption function by the depression-like deformation of the bottom wall. It is an object of the present invention to create a bottom wall structure that is secured and in which generation of folds is effectively suppressed.

Of the means for solving the above problems, the main configuration of the present invention is as follows.
In a biaxial stretch blow molded synthetic resin case,
On the bottom surface of the bottom portion, on the inner side of the peripheral portion, a protrusion that functions as a grounding portion formed by protruding the bottom wall downward from the peripheral portion is disposed,
In the central part, a concave recess formed by recessing the bottom wall upward and inward with the inner side of this ridge as the base end is arranged,
Along with the progress of the internal decompression state, the decompression absorption function is exhibited by the depression-like upward displacement of the bottom wall from the protrusion to the depression recess,
Instead of the ridges, the peripheral part is configured to exhibit the function as a grounding part,
It is said.

An unprecedented feature of the casing having the above-described structure is that a protrusion is disposed between the recessed portion disposed at the peripheral portion and the central portion on the bottom surface of the bottom portion, and the protrusion protrudes downward from the peripheral portion. It is in the point formed.
When the housing is in a reduced pressure state, the bottom wall portion (hereinafter sometimes referred to as a recessed deformed portion) from this protrusion to the recessed recess is reduced due to the upward displacement of the recessed shape into the housing. Absorption function is demonstrated.

Here, before the depressed deformed portion is displaced upward due to the reduced pressure, the protrusion is configured to exert a function as a grounding portion. However, the depressed deformed portion is displaced upward due to the reduced pressure due to the reduced pressure, and the protruding protrusion In a state where the portion is displaced above the peripheral portion, the peripheral portion exhibits a function as a grounding portion.
In this way, by sharing the function of the grounding portion between the ridge and the peripheral portion, the ridge can be sufficiently displaced upward without deteriorating the independence of the housing during decompression.

  The ridge is formed by projecting the bottom wall downward in a bent shape, and when the pressure is reduced, the bent bottom wall is extended so that the depressed deformation portion is largely deformed into a depressed shape and displaced upward. Combined with the configuration that can sufficiently displace the ridges described above, it is possible to fully exhibit the reduced pressure absorption function with a margin, and suppress the occurrence of folds in the depressed deformed portion. Combined with the rib-like action of the ridges, it is possible to effectively suppress the occurrence of folds at the peripheral edge.

Another configuration of the present invention is that the peripheral portion of the bottom surface of the bottom portion is formed in a flat shape in the main configuration described above. In a state where the portion is displaced above the peripheral portion, the function as the ground contact portion of the peripheral portion can be stably exhibited.
In the above configuration, the configuration in which the peripheral portion is formed in a flat shape indicates that the peripheral portion has a vertical plane shape with respect to the central axis direction of the casing, that is, the casing has a horizontal plane when standing.

Still another configuration of the present invention is that the peripheral portion of the bottom surface of the bottom portion is an annular flat portion in the main configuration described above, and the depression deformed portion is displaced upward due to the reduced pressure, and the protrusion protrudes. In the state where the tip portion is displaced upward from the peripheral portion, the function of the peripheral portion as the grounding portion can be more stably exhibited.
Here, the annular flat portion can be not only an annular shape but also a polygonal annular shape.
In the above configuration, the annular flat portion is assumed to be a vertical plane with respect to the central axis direction of the casing, that is, a horizontal plane when the casing is in a standing posture.

  Still another configuration of the present invention is that, in the main configuration described above, the peripheral portion has an inclined surface shape inclined obliquely upward toward the central axis direction of the housing.

In the high-temperature filling step, the case having the above-described structure is considered to be that immediately after the high-temperature content liquid is filled and sealed with a cap, the synthetic resin forming the case is softened and the case is in a pressurized state. Thus, the problem that the bottom wall of the housing is deformed in a bulging shape downward, that is, the so-called bottom falling phenomenon is effectively suppressed.
And by making the peripheral part into the inclined surface shape inclined obliquely upward toward the central axis direction of the casing by the above configuration, the bottom-down phenomenon can be effectively suppressed, and then the casing is When the reduced pressure state is reached, the depressed deformed portion can be uniformly displaced upward in a depressed shape so that the reduced pressure absorption function can be exhibited smoothly and sufficient self-sustainability by the peripheral edge portion can be ensured.

  Still another configuration of the present invention is such that, in the above configuration, the width of the peripheral portion is in the range of 2 to 4 mm, and the height difference between the lower end of the peripheral portion and the inner peripheral edge is in the range of 0.2 to 0.8 mm. It is said.

If the inner part is made horizontal, the bottom drop is likely to increase, and if the bottom drop increases to a certain extent in applications such as filling the content liquid at a higher temperature, or when further thinning the casing, When the body is in a decompressed state, the depressed upward displacement of the deformed deformed part is unevenly biased, and as a result, the decompression absorbing function is not fully exhibited, and further, the local area is locally There is a risk that deformation will occur and the independence of the housing will be impaired.
On the other hand, if the inclination of the peripheral edge portion is too large, the bottom drop can be sufficiently suppressed, but the depression-like upward displacement of the depression deformation portion becomes difficult, and the reduced pressure absorption function is not sufficiently exhibited.

  Here, the width of the peripheral portion is preferably set to a range of 2 to 4 mm in consideration of the function as the ground contact portion after the depressed upward displacement of the depressed deformed portion at the time of decompression, and the width of the peripheral portion is 2 In the range of ~ 4 mm, the degree of inclination of the peripheral edge is defined by the height difference between the lower end and the inner peripheral edge, and by making this height difference in the range of 0.2-0.8 mm, the bottom drop is effective. It is possible to sufficiently exhibit the reduced pressure absorption function while being suppressed.

Still another configuration of the present invention is that the ridge is a circumferential ridge.
By making the protrusion into a peripheral protrusion, the function as the grounding portion can be exhibited more stably.
Here, the shape of the ridge is not limited to the circumferential ridge as described above, and a configuration in which a large number of ridges are arranged in a circumferential shape may be employed. Further, the protrusions can be arranged in a polygonal circumferential shape in addition to the circumferential shape.

  Still another configuration of the present invention is a configuration in which a depressed recess is provided via a stepped portion formed in a reduced diameter inside the ridge.

  With the above configuration, the upward displacement of the depressed deformed portion during decompression can be caused to proceed more smoothly by the action of the peripheral rib of the stepped portion, and the occurrence of folds at the displaced portion can be more effectively suppressed. it can.

Yet another configuration of the present invention is that the cross-sectional shape of the ridge is trapezoidal or U-shaped, and the configuration is depressed and deformed so as to extend the trapezoidal or U-shaped cross-sectional shape. The upward displacement of the part can be made to proceed more smoothly.
Further, the grounding function can be sufficiently exerted by utilizing the flat tip portion protruding from the trapezoidal shape or the U-shaped cross section.

  Here, when the cross-sectional shape of the protrusion is trapezoidal or U-shaped, the shape of the protrusion, such as the width and protrusion height, considers the size and thickness of the housing, the independence of the housing, etc. It can be set as appropriate based on calculations and test results relating to deformation modes such as ease of deformation of the bottom wall.

  According to still another configuration of the present invention, the depressed concave portion has a shape in which a flat cross-sectional shape changes from a circle near the center to an equilateral triangular shape at the base end.

With the above configuration, the formation of the folds at the depression deformed portion at the time of decompression can be specified in a flat cross-sectional shape and dispersed in the direction in which the vertices of the regular triangle are located, and the formation of the folds at the annular flat portion can be further determined. It can be effectively suppressed.
In addition, since the depression-like deformation mode can be controlled, it is possible to exhibit a constant reduced pressure absorption function more stably.

  According to still another configuration of the present invention, a groove-like recess formed by stepping the bottom wall upward and inward is provided at the boundary between the inner peripheral edge of the peripheral edge and the outer peripheral edge of the protrusion. It is said.

  With the above configuration, the depression-like upward displacement of the depression-deformed portion in the decompressed state can be smoothly advanced starting from the groove-like concave portion, and the peripheral portion can function as a grounding portion by suppressing distortion deformation in the peripheral portion. Can be exhibited stably.

  Still another configuration of the present invention is a round casing in which a plurality of circumferential groove ribs are formed on a cylindrical body.

With the above configuration, by forming a plurality of circumferential groove ribs on the cylindrical body, the surface rigidity of the body is increased to provide high shape retention, and a vacuum absorbing panel is formed on the body during decompression. It is possible to provide a round casing capable of exhibiting a reduced pressure absorption function with the bottom.

Since the present invention has the above-described configuration, the following effects can be obtained.
In the case having the main structure of the present invention, the function of the grounding part is shared by the ridge and the annular flat part, so that the ridge is sufficiently displaced upward during decompression without impairing the independence of the case. Possible configurations can be obtained.
The ridge is formed by protruding the bottom wall downward in a bent shape, and when the pressure is reduced, the bent bottom wall is extended so that the depressed deformation portion is largely deformed into a depressed shape and displaced upward. In combination with the configuration that can sufficiently displace the above-described protrusion, the decompression absorption function can be sufficiently exerted, thereby suppressing the occurrence of a fold in the depressed deformed portion, and the protrusion Together with the rib-like action, it is possible to effectively suppress the occurrence of folds at the peripheral edge.

It is a front view which shows 1st Example of the housing of this invention. It is a bottom view of the housing of FIG. FIG. 3 is an enlarged longitudinal sectional view taken along the line AA in FIG. 2, enlarging the vicinity of the bottom of the housing of FIG. 1. It is a graph which shows the result of a decompression absorption capacity measurement test. It is a graph which shows the other result of a decompression absorption capacity measurement test. It is a front view which shows 6th Example of the housing of this invention. It is a bottom view of the housing of FIG. (A) is the longitudinal cross-sectional view of the peripheral part of the bottom part shown along the BB line in FIG. 7 of the housing of FIG. 6, and the vicinity of a protrusion, (b) is 5th implementation shown for a comparison. It is a longitudinal cross-sectional view shown similarly to (a) about the case of an example. It is a bottom view which shows the other example of the shape of a bottom part. (A) which shows the housing of a prior art example is a front view, (b) is a bottom view.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below along the examples with reference to the drawings.
1 to 3 show a first embodiment of a synthetic resin casing according to the present invention. FIG. 1 is a front view, FIG. 2 is a bottom view, and FIG. It is a longitudinal cross-sectional view shown along an AA line.
This housing 1 is a biaxially stretched blow-molded product made of PET resin having a mouth tube part 2, a shoulder part 3, a cylindrical body part 4, and a bottom part 5 and having a capacity of 280 ml.

The body portion 4 is formed with three circumferential groove ribs 7 as one means for increasing the surface rigidity and the buckling strength, and the body portion 4 has a high shape retaining property. Of course, the means for increasing the surface rigidity and the buckling strength is not limited to the circumferential groove rib 7.
A bottom portion 5 is continuously provided at the lower end of the body portion 4 via a heel wall portion 11 formed in a curved cylindrical shape. A peripheral edge portion 12 of the bottom surface of the bottom portion 5 is an annular flat portion 12a. .
In addition, a circumferential ridge 13a is provided on the inner side of the peripheral edge portion 12 as a ridge 13 that functions as a grounding portion formed by projecting a bottom wall downward from the annular flat portion 12a. In this case, a concave recess 15 formed by recessing the bottom wall upward and inward through a stepped portion 15s formed in a reduced diameter is provided with the inner side of the circumferential protrusion 13a as a base end. .
In addition, a groove-like recess 17 formed by stepping the bottom wall upward and inward is provided at the boundary between the inner peripheral edge of the peripheral edge 12 and the outer peripheral edge of the protrusion 13.

The circumferential ridge 13a is formed of a pair of side walls 13s and a flat tip flat portion 13t, and its cross-sectional shape is trapezoidal (can be U-shaped). The protruding height H from the portion 12a is 2 mm, and the width W of the tip flat portion 13t is 6 mm.
Further, the shape of the depressed recess 15 is such that its flat cross-sectional shape gradually changes from a circle near the center to a regular triangle at the base end.
Here, when the ridge 13 is used as the grounding portion as described above, there is a concern that the independence may be lowered as compared with the case where the peripheral edge portion 12 is used as the grounding portion. By considering the protruding height within a predetermined range in consideration, even when the housing is about to fall down, the annular flat portion 12a, which is the peripheral portion 12, can contact the grounded surface and be supported. The independence of the housing can be maintained without reducing the rolling equiangular angle.

With the above-described configuration, in the case 1 of the present embodiment, when the inside of the case 1 is in a reduced pressure state due to cooling after the high-temperature filling step, the effect of the circumferential groove rib 7 is combined with the body portion 4. The cylindrical shape of is held,
As schematically shown by a two-dot chain line in FIG. 3, the circumferential protrusion 13a having a trapezoidal cross section is deformed so as to extend, and the depression from the circumferential protrusion 13a to the depression 15 The deformable portion 16 is displaced upward in a depressed shape (see the direction of the white arrow in FIG. 3), and the reduced pressure absorption function is exhibited.

As described above, in the state where the depressed deformed portion 16 is displaced upward due to the reduced pressure, the annular flat portion 12a functions as a grounding portion instead of the circumferential protrusion 13a. The independence of is maintained.
Here, by disposing a groove-like recess 17 at the boundary between the inner periphery of the peripheral edge 12 and the outer periphery of the ridge 13, the depression-like deformed portion 16 in the decompressed state starts from the groove-like recess 17 as a starting point. The upward displacement can be progressed smoothly, and distortion function in the peripheral edge portion 12 can be suppressed and the function of the peripheral edge portion 12 as a ground contact portion can be exhibited more stably.

Next, in order to confirm the operational effects of the housing of the present invention, a housing having a width W of 6 mm and a protruding height H of 2 mm of the tip flat portion 13t of the above embodiment,
A casing having a width W of the tip flat portion 13t of the circumferential protrusion 13a of 6 mm and a protruding height H of 1 mm and 0 mm, and a width W of the tip flat portion 13t of 5 mm, 7 mm and 8 mm with a protrusion height H of 2 mm. A total of six types of cases were prepared, and a reduced pressure absorption capacity measurement test related to the reduced pressure absorption function was performed.
(1) Six types of chassis prepared: chassis of the first embodiment; width W is 6 mm, projecting height H2 mm (the chassis of the above-described embodiment)
-Housing of the second embodiment; width W is 6 mm, projecting height H1 mm
-Housing of the third embodiment; width W is 5 mm, projecting height H2 mm
-Housing of the fourth embodiment; width W is 7 mm, projecting height H2 mm
-Housing of the fifth embodiment; width W is 8 mm, projecting height H2 mm
The case of the comparative example: width W is 6 mm, protrusion height H0 mm (that is, it corresponds to a conventional case in which no protrusion 13 is provided on the bottom surface of the bottom 5).
(2) Vacuum absorption capacity measurement test The casing to be measured is fully filled with water, a burette with a rubber stopper is attached to the mouth tube portion, a vacuum pump is operated, and a manometer at a speed of 0.4 kPa / sec. The decompression capacity is calculated from the difference between the values of the burette before and after the test by reading the value of the burette when the pressure is reduced and the housing is deformed illegally such as local depression deformation or buckling deformation.

FIG. 4 shows the reduced pressure absorption capacity measurement of the casings of the first example, the second example, and the comparative example in which the width W of the tip flat portion 13t is a constant value of 6 mm and the protruding height H is 2 mm, 1 mm, and 0 mm, respectively. The test results are shown in a graph with the horizontal axis representing the reduced pressure strength (kPa) and the vertical axis representing the absorption capacity (ml).
In the figure, the result of the case of the first example is indicated by a line T1, the result of the case of the second example is indicated by a line T2, and the result of the case of the comparative example is indicated by a line T6.

In any of the above three types of the casings, the mode of the unauthorized deformation is any one of the three angular positions indicated by the arrow V in FIG. 2 of the annular flat portion 12a (that is, the central angular position where the vertex of the regular triangle is located). At the location, the bottom wall was bent in the radial direction in a V shape.
And the decompression absorption capacity in the point which carried out the illegal deformation | transformation and the point shown by S1, S2, S6 in the figure is as follows, and confirms the effect by arrangement | positioning of the housing of this invention, especially the circumferential protrusion 13a. I was able to.
-Housing of the first embodiment: 22.4 ml
-Housing of the second embodiment; 18.4 ml
・ Comparative body: 14.2 ml

FIG. 5 shows a first embodiment, a third embodiment, a fourth embodiment, and a fifth embodiment in which the protrusion height H is a constant value of 2 mm, and the width W of the tip flat portion 13t is 6 mm, 5 mm, 7 mm, and 8 mm, respectively. The test result of the vacuum absorption capacity measurement test of the case of an example is made into a graph similarly to FIG.
In the figure, the result of the enclosure of the first embodiment is the line T1, the result of the enclosure of the third embodiment is the line T3, the result of the enclosure of the fourth embodiment is the line T4, and the fifth embodiment. The result of the case is shown by the line T5.

As in the case of the three types of casings shown in FIG. 4, the five types of casings shown in FIG. 5 are in the form of unauthorized deformation in the three angular positions indicated by arrows V in FIG. The bottom wall is bent in the radial direction in a V shape at any one of the positions (corresponding to the center angle position where the apex of the regular triangle is located).
And the vacuum absorption capacity | capacitance in the point which carried out the illegal deformation | transformation and S1, S3, S4, S5 in the figure was as follows.
-Housing of the first embodiment: 22.4 ml
-Housing of the third embodiment: 20.3 ml
-Housing of the fourth embodiment; 24.7 ml
-Housing of the fifth embodiment; 26.2 ml

From the test results of FIG. 5, in the region where the decompression strength is high (the region of 20 kPa or more in FIG. 5), the absorption capacity at the same decompression strength increases as the width W of the tip flat portion 13t is increased from 5 to 8 mm. It can be seen that the depressed deformation portion 16 can be easily displaced upward, the decompression absorption capacity at the point of unauthorized deformation is large, and a larger decompression absorption function is exhibited.
Here, if the width W is too large, it may affect the shapes of the annular flat portion 12a, the stepped portion 15s, the recessed portion 15 and the like. However, the size of the housing and the protruding height of the circumferential protrusion 13a are affected. Considering the ratio with H, etc., it can be set as appropriate based on the calculation and test results relating to the deformation mode.

  Next, FIGS. 6 to 8 show a housing of a sixth embodiment of the present invention, FIG. 6 is a front view, and FIG. 7 is a bottom view. The overall shape of the housing 1 is substantially the same as the housing shown in FIGS. 1 and 2, and the shape of the ridge 13 is a projection height H of 2 mm and a width W of 8 mm. It is the same as the casing of the embodiment.

FIG. 8A is an enlarged vertical cross-sectional view of the main part in the vicinity of the peripheral edge 12 and the ridge 13 of the casing of the fifth embodiment described above, and FIG. 8B is the casing of the sixth embodiment.
As for the shape of the bottom portion 5, the protrusions 13 are continuously provided from the heel wall portion 11 via the peripheral edge portion 12 in both cases. Is provided with a groove-shaped recess 17 formed by stepping the bottom wall upward and inwardly in a step shape.

In both cases, the width Wp of the peripheral portion 12 is 3 mm. However, in the case of the fifth embodiment, the peripheral portion 12 is horizontal and has an annular flat portion 12a.
In the housing of the sixth embodiment, as shown in FIG. 8 (a), the peripheral portion 12 is characterized by an inclined surface inclined obliquely upward toward the central axis direction of the housing.
When the degree of inclination of the inclined surface is expressed by the height difference h (see FIG. 8A) between the lower end 12b of the peripheral portion 12 and the inner peripheral edge, the height difference h is set to 0.5 mm.

Here, in the high temperature filling step, immediately after filling the high temperature content liquid and sealing with the cap, the synthetic resin forming the casing is softened and the inside of the casing is in a pressurized state. A so-called bottom drop phenomenon occurs in which the bottom wall of the body is deformed in a bulging shape downward (in the direction of the white arrow in FIGS. 8A and 8B).
This bottom-down phenomenon increases as the filling temperature of the content liquid increases and the wall thickness of the housing further decreases, and when it increases to a certain extent, when the housing is depressurized, As a result, the depressed upper displacement of the portion 16 occurs unevenly and unevenly. As a result, the vacuum absorber is not sufficiently exhibited, and further, local deformation occurs at the peripheral portion, and the self-supporting property of the housing is reduced. There is a risk that it will be damaged.

  The housing of Example 6 is for dealing with the further increase in the filling temperature of the content liquid and the further thinning of the wall thickness of the housing as described above, and the peripheral portion 12 is shown in FIG. By making it inclined as seen, the above-mentioned bottoming phenomenon is effectively suppressed.

In addition, if the inclination of the peripheral edge portion 12 is excessively increased, the bottom drop can be sufficiently suppressed, but on the other hand, the depressed deformation portion 16 is difficult to be displaced upward during decompression, and the decompression absorption function is sufficiently exerted. It will not be done.
Accordingly, the width Wp of the peripheral edge portion 12 is 2 to 4 mm (3 mm in the case of the sixth embodiment) in consideration of the function as the ground contact portion after the depression-like upward displacement of the depression deformation portion 16 at the time of decompression. ) And the height difference h is in the range of 0.2 to 0.8 mm (0.5 mm in the case of the sixth embodiment). The function can be fully exhibited.

As mentioned above, although the structure of this invention and its effect were demonstrated along the Example, embodiment of this invention is not limited to the said Example. Here, FIG. 9 is a bottom view showing three other examples (a), (b), and (c) of the shape of the bottom.
In the above-described embodiment, the flat cross-sectional shape of the depressed recess 15 is an equilateral triangular anisotropy shape, but of course, the flat cross-sectional shape can be a circular shape as shown in FIG. Further, as shown in FIG. 9B, the step portion 15s may be polygonal.

  In addition, the shape of the ridge 13 such as the width and the height of the protrusion considers the size and thickness of the housing, the independence of the housing, etc., and calculates the deformation mode such as the ease of deformation of the bottom wall. It can be set as appropriate based on the test results. Further, the protrusion 13 is not limited to the peripheral protrusion 13a as in the above-described embodiment, and as shown in FIG. 9C, a large number (in the example of FIG. 9C, 8 The projecting ridges 13) may be arranged around the notch 13K.

Further, the groove-shaped concave portion 17 can be disposed as needed, and the shape such as the width and the groove depth can be appropriately determined.
Further, whether the peripheral edge portion 12 is horizontally flat, inclined, or the degree of inclination can be appropriately determined in consideration of the filling temperature of the content liquid, the degree of thinning, and the like. Is.

The synthetic resin casing of the present invention exhibits a reduced pressure absorption function sufficiently by deformation of the bottom wall of the bottom part, exhibits sufficient self-sustainability even during reduced pressure, and further suppresses the occurrence of folds. Yes, it can be expected to develop further applications in the field of bottles that require high temperature filling.

DESCRIPTION OF SYMBOLS 1; Housing 2; Mouth part 3; Shoulder part 4; Trunk part 5; Bottom part 7; Circumferential groove rib 11; Heel wall part 12; Peripheral part 12a; Projection 13t; tip flat part 13s; side 15; depression 15s; step 16; depression deformation part 17; groove-like depression 101; housing 104; trunk 107; circumferential groove rib 112; V: Fold H: Projection height W; Width Wp (of ridge); Width (of peripheral edge)

Claims (11)

A biaxially stretched blow molded synthetic resin casing, formed on the bottom surface of the bottom portion (5), on the inner side of the peripheral portion (12), with the bottom wall protruding downward from the peripheral portion (12). A protrusion (13) that functions as a ground contact portion is disposed, and a recessed portion formed by recessing the bottom wall upward and inward with the inner side of the protrusion (13) as a base end in the center portion (15) is disposed, and along with the progress of the internal reduced pressure state, the vacuum absorption function is exhibited by the depression-like upward displacement of the bottom wall from the protrusion (13) to the depression recess (15), and A synthetic resin casing in which the peripheral portion (12) functions as a grounding portion instead of the ridge (13). The synthetic resin casing according to claim 1, wherein the peripheral edge (12) of the bottom of the bottom (5) is formed flat. The synthetic resin casing according to claim 1 or 2, wherein the peripheral portion (12) of the bottom surface of the bottom portion (5) is an annular flat portion (12a). The synthetic resin casing according to claim 1, wherein the peripheral edge portion (12) has an inclined surface inclined obliquely upward toward the central axis direction of the casing. The width (Wp) of the peripheral edge portion (12) is in the range of 2 to 4 mm, and the height difference (h) between the lower end of the peripheral edge portion (12) and the inner peripheral edge is in the range of 0.2 to 0.8 mm. The synthetic resin casing as described. The synthetic resin casing according to claim 1, 2, 3, 4, or 5, wherein the protrusion (13) is a peripheral protrusion (13a). The recessed portion (15) is arranged through a step portion (15s) formed in a reduced diameter inside the ridge (13), according to claim 1, 2, 3, 4, 5 or 6. Synthetic resin housing. The synthetic resin casing according to claim 1, 2, 3, 4, 5, 6 or 7, wherein the cross-sectional shape of the ridge (13) is trapezoidal or U-shaped. 9. The depressed recess (15) according to claim 1, 2, 3, 4, 5, 6, 7 or 8, wherein the flat cross-sectional shape changes from a circle near the center to an equilateral triangle at the base end. Synthetic resin housing. A groove-shaped recess (17) formed by stepping the bottom wall upwardly and inwardly at the boundary between the inner peripheral edge of the peripheral edge (12) and the outer peripheral edge of the ridge (13) is provided. 1, 2, 3, 4, 5, 6, 7, 8 or 9. The composition according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10, wherein the cylindrical body (4) is a round casing having a plurality of circumferential groove ribs (7). Resin housing.

Images