JP4696717B2 - Plastic container - Google Patents

Description

  The present invention is a bottle-shaped synthetic resin container having an annular lateral groove in the container body, and has improved buckling strength with respect to longitudinal load without reducing the vacuum absorption performance and rigidity against lateral load. It relates to a resin container.

  For example, synthetic resin such as polyethylene terephthalate is formed into a bottle shape by blow molding as a container for beverages such as carbonated beverages such as cola and cider, fruit juice beverages, mineral water, coffee beverages and various teas. The container made from manufacture is generally used widely (for example, refer patent document 1 and patent document 2).

  Such bottle-type synthetic resin containers have rapidly spread and penetrated in recent years, and with the widespread use of such bottle-type synthetic resin containers, there are a variety of products that use bottle-type synthetic resin containers. Accordingly, containers having various capacities from a large capacity exceeding 2000 ml to a small capacity of about 200 ml have been required depending on the contents. In addition, the form of sales of products using bottle-shaped synthetic resin containers has also diversified, especially for relatively small-capacity beverage bottle containers with a capacity of about 200 to 500 ml, in addition to over-the-counter sales. More and more are being sold by vending machines.

JP 2004-262500 A JP 2003-285814 A

  By the way, this type of bottle container usually has a reduced pressure absorption structure for preventing an irregular shape change of the container with a decrease in internal pressure because the container after filling and sealing the contents is in a reduced pressure state. Patent Document 1 discloses, as an example of a bottle container having such a reduced pressure absorption structure, a synthetic resin bottle-type container provided with a plurality of annular grooves along the surface of a cylindrical body. ing. The annular groove formed in the bottle container of Patent Document 1 is deformed in accordance with the pressure reduction in the container and shrinks the container in the vertical direction to reduce the volume, thereby relaxing the degree of decompression in the container. In Patent Document 1, by making the inclination angle of the groove side wall with respect to the groove bottom of the annular groove within a predetermined range, the smooth bottle longitudinal direction using the annular groove without making the annular groove into a complicated shape The shrinkage can be achieved.

  In addition, the annular groove formed along the circumferential direction of the container body portion functions to alleviate the degree of decompression in the container and secure the rigidity of the container. By setting the interval between the grooves within a predetermined range, it is possible to enhance the surface rigidity opposed to the lateral pressing generated by the pressure reduction.

  As described above, the annular groove capable of ensuring the rigidity of the container while providing the container with a reduced pressure absorption performance with a simple configuration is generally a cylindrical body (or a round bottle) called a round bottle (or It is especially effective for bottle containers having a shape approximating a cylindrical shape). For round bottles distributed in the market, a plurality of such annular grooves are formed in the container body. Not a few.

  However, the annular groove as described above deforms the container in the vertical direction and exhibits reduced-pressure absorption performance, and since it can be deformed in the vertical direction, the container has a longitudinal direction in the case of transportation or the like. When a load (longitudinal load) is applied, the container tends to buckle. For example, when the contents are filled at a high temperature in order to suppress the growth of bacteria after filling, high vacuum absorption performance is required. In this case, if the groove depth is increased to increase the amount of deformation of the annular groove to improve the vacuum absorption performance, there is a problem that sufficient buckling strength against a longitudinal load cannot be secured.

In addition, if the groove depth of the annular groove is reduced, the buckling strength against the longitudinal load can be secured, but the required vacuum absorption performance and the rigidity to keep the container shape (cylindrical shape) against pressure reduction ( Not only can the decompression strength be obtained, but also the rigidity when a lateral load (lateral load) is applied to the container will be reduced, and this will not be suitable for sale by vending machines. There was also a problem of end.
That is, in the case of being offered for sale by a vending machine, the bottle container filled with the contents is continuously dropped while being rolled sideways in the vending machine, and the container filled with the subsequent contents. While receiving the load due to the weight, the container waits for the side surface of the container to come into contact with the stopper and be discharged to the takeout port, and then is discharged to the takeout port by dropping. In this way, the bottle container used for sale by the vending machine supports the lateral load applied when it is dropped while being rolled, and the load caused by the container filled with the subsequent contents, by contacting the stopper. Because rigidity that can withstand lateral loads is required, and those with low rigidity against such lateral loads are deformed and clogged in the vending machine or fall through the stopper and fall into the take-out port. It cannot be offered for sale at a vending machine.

  As described above, in the conventional bottle container in which a plurality of annular grooves are formed in the container body, the reduced pressure absorption performance, the reduced pressure strength, and the rigidity against the lateral load are secured while maintaining the vertical load. There was a limit to improving the buckling strength.

  Therefore, in the light of the above circumstances, the present inventors have made extensive studies, and in this type of bottle container that is usually formed by blow molding a preform, the thickness of the container body is Focusing on the fact that the wall thickness distribution is not constant but has a certain thickness distribution, the groove depth of the annular groove, which was conventionally the same, is determined for each part where the annular groove is formed. It is found that the buckling strength against the longitudinal load can be improved while balancing with the reduced pressure absorption performance, the reduced pressure strength, and the rigidity against the lateral load by setting according to the difference of the above, and the present invention is completed. It came to.

  That is, the present invention provides a ring-shaped container body that is improved in buckling strength against a longitudinal load without causing a decrease in the balance while maintaining a reduced pressure absorption performance, reduced pressure strength, and rigidity against a lateral load. An object of the present invention is to provide a bottle-shaped synthetic resin container having horizontal grooves.

A synthetic resin container according to the present invention that solves the above problems is a synthetic resin container having a mouth portion, a trunk portion, and a bottom portion, and the trunk portion is annular along the circumferential direction of the trunk portion. A plurality of horizontal grooves formed, and for each portion where the horizontal grooves are formed, the depth of the horizontal grooves is changed according to the thickness of the body portion, and one of the plurality of horizontal grooves is In the part where the thickness of the body part on the upper side in the height direction of the part where the transverse groove is formed is relatively thin relative to the thickness of the other part, the groove depth of the transverse groove is set to the The structure is relatively shallow according to the wall thickness .

The synthetic resin container according to the present invention is a synthetic resin container having a mouth portion, a trunk portion, and a bottom portion, and the trunk portion is formed in an annular shape along a circumferential direction of the trunk portion. Each of the plurality of horizontal grooves has a plurality of horizontal grooves, and the depth of the horizontal grooves is changed in accordance with the thickness of the body portion for each portion where the horizontal grooves are formed. In the portion where the thickness of the trunk portion on the upper side in the height direction of the portion to be formed is relatively thick with respect to the thickness of other portions, the groove depth of the transverse groove is set to the thickness of the trunk portion. Accordingly, a relatively deep configuration may be used.

According to the synthetic resin container according to the present invention having such a configuration, by reducing the groove depth of the lateral groove in correlation with the thickness of the trunk portion, the reduced pressure absorption performance required for the container and the reduced pressure strength Furthermore, it is possible to improve the buckling strength against the longitudinal load while balancing with the rigidity against the lateral load.
In changing the groove depth of the transverse groove in correlation with the thickness of the trunk, by making the groove depth of the transverse groove relatively shallow according to the thickness of the trunk, the thin part that tends to buckle easily Deformation can be suppressed and the buckling strength with respect to the longitudinal load of the container can be improved. Also, by making the groove depth of the lateral groove relatively deep according to the wall thickness of the trunk, the buckling strength against vertical load should be equal to or higher than the conventional product while increasing the groove depth of the horizontal groove. It is possible to improve the reduced pressure absorption performance and the reduced pressure strength without reducing the buckling strength, and increase the rigidity against the lateral load.

In the synthetic resin container according to the present invention, in particular, the thickness t [mm] of the trunk portion on the upper side in the height direction of the portion where one horizontal groove is formed among the plurality of horizontal grooves, and the groove depth of the horizontal grooves. It is preferable to satisfy the relationship of the following formula (1) with d [mm] .
α × t−3.1 ≦ d ≦ α × t−2.3 [where α = 16.7] (1)

Moreover, the synthetic resin container according to the present invention has a shoulder portion that is continuous with the mouth portion at a portion on the upper side in the height direction of the trunk portion, and a reduced pressure absorption panel is provided on the shoulder portion. You can also.
With such a configuration, the vacuum absorption performance of the container can be further improved, and the degree of vacuum generated in the container is reduced by the vacuum absorption panel provided on the shoulder, and the cylindrical degree of the container body ( (Roundness when the container body is cut horizontally at an arbitrary height position) can be increased. This makes it easy to keep the cross-sectional shape of the container body in a circular shape (or a shape close to a circular shape) with excellent rolling properties, and make the container more suitable for sale by a vending machine. Can do.

  According to the present invention as described above, in a container having an annular lateral groove in the container body, by changing the groove depth of the lateral groove according to the thickness of the body for each portion where the lateral groove is formed. The buckling strength against the longitudinal load of the container can be improved without lowering the reduced pressure absorption performance, the reduced pressure strength, and the rigidity against the lateral load required for the container.

Hereinafter, a preferred embodiment of a synthetic resin container according to the present invention will be described with reference to the drawings.
Here, FIG. 1 is a front view showing an outline of an embodiment of a synthetic resin container according to the present invention.

  A container 1 shown in FIG. 1 generally has a container shape called a round bottle, and includes a mouth part 2, a body part 3, and a bottom part 4. The body portion 3 includes a cylindrical portion 32 formed in a cylindrical shape having substantially the same diameter, and a shoulder portion 31 that is squeezed from the upper end of the cylindrical portion 32 and continues to the mouth portion 2.

Further, in the illustrated example, the body 3 (tubular portion 31) has five lateral grooves (annular grooves) 5 formed in an annular shape along the circumferential direction arranged at equal intervals in the height direction. . When the internal pressure of the container 1 decreases, the lateral groove 5 formed in the body part 3 deforms (contracts) the container 1 in the longitudinal direction to absorb the pressure decrease, and also deforms in the radial direction. It also functions as a skeleton that suppresses uneven deformation such as the container 1 being tilted or having an elliptical cross section, and the rigidity of the container 1 against lateral loads is secured. Is to do.
Here, the height direction means a direction along a direction orthogonal to the horizontal plane when the container 1 is placed on the horizontal plane with the mouth portion 2 facing up.

The distance between adjacent lateral grooves 5 (the distance between the center lines C1 and C2 along the deepest part) h3 is usually about 10 to 20 mm, although it depends on the capacity of the container 1 and the number of the lateral grooves 5 formed. .
If the interval h3 between the adjacent lateral grooves 5 exceeds the above range, the number of lateral grooves 5 that can be formed in the body portion 3 is limited to a smaller number than necessary, and the lateral grooves 5 are reinforced by the lateral grooves 5. Since the proportion of the side surfaces that are not present increases, the reduced pressure absorption performance, the reduced pressure strength, and the rigidity against the lateral load become insufficient. On the other hand, if the lower limit is not reached, the lateral grooves 5 are arranged too densely and the side surfaces become bellows-like, so that the buckling strength against a longitudinal load may be reduced.
In the example shown in the figure, the horizontal grooves 5 are arranged at equal intervals. However, the intervals at which the horizontal grooves 5 are arranged are not equal intervals. For example, the upper portion, the center, the lower portion, etc. Alternatively, it may be varied as necessary.

  The groove width w of the lateral groove 5 is also set in consideration of the reduced pressure absorption performance, the reduced pressure strength, the rigidity with respect to the lateral load, the buckling strength with respect to the longitudinal load, and can be normally set to about 3 to 8 mm. Further, in the illustrated example, the cross-sectional shape of the lateral groove 5 is U-shaped, but if it deforms according to the pressure change in the container and can suppress uneven deformation of the container 1, for example, a V-shaped Any cross-sectional shape such as a U shape, a trapezoidal shape, a polygonal shape, or the like can be used without departing from the effects of the present embodiment.

Such a synthetic resin container 1 can be manufactured, for example, by biaxially stretching blow-molding a bottomed cylindrical preform manufactured by known injection molding or extrusion molding. In general, the container 1 formed by molding does not have a constant thickness of the body portion 3, and such a thickness distribution tends to be prominent in a relatively small volume.
Nevertheless, in the conventional container in which this kind of annular groove is formed, the groove depth is the same for all the grooves, but in the present embodiment, the transverse groove 5 formed in the body portion 3 is used. The groove depth is changed in accordance with the thickness of the body portion 3 for each portion where the lateral groove 5 is formed.

More specifically, in a portion where the thickness of the body portion 3 on the upper side in the height direction of the portion where the lateral groove 5 is formed is relatively thin with respect to the thickness of the other portion, The groove depth is made relatively shallow in accordance with the thickness of the body 3. Thereby, the deformation | transformation of the thin part which tends to buckle can be suppressed, and the buckling strength with respect to the longitudinal load of the container 1 can be improved.
Further, in a portion where the thickness of the body portion 3 on the upper side in the height direction of the portion where the horizontal groove 5 is formed is relatively thicker than the thickness of the other portion, the groove depth of the horizontal groove 5 is set. The depth is relatively increased according to the thickness of the body 3. Thereby, while increasing the groove depth of the lateral groove 5, the buckling strength against the longitudinal load can be equal to or higher than that of the conventional product, and the deformation amount of the lateral groove 5 is increased without reducing the buckling strength. Thus, it is possible to improve the reduced pressure absorption performance and increase the reduced pressure strength and the rigidity against the lateral load of the container 1.

Thus, in this embodiment, by changing the groove depth of the transverse groove 5 in correlation with the wall thickness of the trunk portion 3, the reduced pressure absorption performance required for the container 1, the reduced pressure strength, The buckling strength against the longitudinal load can be improved while balancing with the rigidity against the lateral load, but the thickness t [mm] of the body portion 3 on the upper side in the height direction of the portion where the lateral groove 5 is formed, and the lateral groove In particular, it is preferable that the relationship of the following formula (1) is established between the groove depth d [mm] of 5.
α × t−3.1 ≦ d ≦ α × t−2.3 [where α = 16.7] (1)

  The above formula (1) improves the buckling strength from a large number of samples in which the groove depth of the lateral groove 5 is changed according to the thickness of the body portion 3 without reducing the reduced pressure strength and the rigidity against the lateral load. Extracting what could be made, and creating a graph with the horizontal axis representing the wall thickness t of the body portion 3 on the upper side in the height direction of the portion where the horizontal groove 5 is formed and the vertical axis representing the groove depth d of the horizontal groove 5 It is obtained by regression analysis of the correlation between the two, and if the groove depth d becomes deeper than the relationship of the above formula (1), the buckling strength of the container 1 against the longitudinal load is improved. It tends to be difficult to obtain. On the other hand, if the groove depth d becomes shallow without satisfying the relationship of the above formula (1), the reduced pressure absorption performance, the reduced pressure strength, and the rigidity against the lateral load tend to decrease.

Here, the thickness t of the body portion 3 is an intermediate position between the height position of the deepest portion of the horizontal groove 5 to be noticed and the height position of the deepest portion of the horizontal groove 5 adjacent to the upper side in the height direction (the uppermost position). In the horizontal groove 5, it is set as the thickness in the position which becomes the height direction upper side 7mm from the deepest part of the said horizontal groove 5 (refer FIG.2 and FIG.3 mentioned later).
Further, when the groove depth d of the lateral groove 5 is determined in applying this embodiment, for example, a mold having no protrusion corresponding to the lateral groove 5 is used, and the lateral groove 5 is not provided in advance. A container having the same dimensions may be blow-molded, and the groove depth d of the lateral groove 5 may be determined for each part in accordance with the container thickness distribution caused by the molding conditions at that time. However, without allowing the thickness distribution of the container 1 to remain, for example, in the method as described in JP-A-6-99482, that is, when blow molding, each part of the preform is set to a desired temperature. By adjusting to, an arbitrary thickness distribution can be positively achieved.

Moreover, in this embodiment, as shown in FIG. 6, by providing the shoulder part 31 with the reduced pressure absorption panel 6, the reduced pressure absorption performance of the container can be further improved. The reduced pressure absorption panel 6 relaxes the degree of reduced pressure generated in the container by gently deforming inward of the container 1 when the internal pressure of the container 1 decreases. The provision of 31 is effective in increasing the cylindricity of the body 3 after filling the contents (roundness when the container body is cut horizontally at an arbitrary height position).
Thereby, it becomes easy to keep the cross-sectional shape of the trunk | drum 3 in the circular shape (or shape approximated to circular shape) excellent in rolling property, and it shall be a container more suitable for sale with a vending machine. Can do.

  The synthetic resin container according to the present embodiment as described above can be manufactured by blow molding or the like as described above. However, the thermoplastic resin constituting the container 1 is optional as long as blow molding is possible. The resin can be used.

Specifically, thermoplastic polyesters such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polycarbonate, polyarylate, polylactic acid or copolymers thereof, those blended with these resins or other resins are suitable. In particular, an ethylene terephthalate thermoplastic polyester such as polyethylene terephthalate is preferably used. Further, acrylonitrile resin, polypropylene, propylene-ethylene copolymer, polyethylene and the like can be used.
In these resins, various additives such as a colorant, an ultraviolet absorber, a release agent, a lubricant, a nucleating agent, an antioxidant, an antistatic agent and the like are blended as long as the quality of the molded product is not impaired. You can also.

In the ethylene terephthalate thermoplastic polyester, most of the ester repeating units (for example, 70 mol% or more) are occupied by ethylene terephthalate units, the glass transition point (Tg) is 50 to 90 ° C, and the melting point (Tm) is 200 to 275 ° C. Those within the range are preferred.
As an ethylene terephthalate-based thermoplastic polyester, polyethylene terephthalate (PET) is particularly excellent in terms of pressure resistance, heat resistance, heat pressure resistance, and the like. Copolyesters containing a small amount of ester units composed of diols such as propylene glycol can also be used.

Moreover, the synthetic resin container according to the present embodiment can be constituted by two or more thermoplastic polyester layers in addition to the case of being constituted by a single layer (one layer) of thermoplastic polyester layer. Furthermore, an intermediate layer sealed between an inner layer and an outer layer composed of two or more thermoplastic polyester layers can be provided, and the intermediate layer can be a barrier layer or an oxygen absorbing layer. Thus, by providing the barrier layer and the oxygen absorbing layer, it is possible to suppress the permeation of oxygen from the outside into the container, and to prevent the alteration of the contents in the container due to the oxygen from the outside.
Here, as the oxygen absorbing layer, any layer can be used as long as it absorbs oxygen and prevents permeation of oxygen, but a combination of an oxidizable organic component and a transition metal catalyst, or substantially oxidized. It is preferred to use a combination of non-gas barrier resin, oxidizable organic component and transition metal catalyst.

Next, the present invention will be described in more detail with reference to specific examples.
[Example 1]
A preform made of polyethylene terephthalate (PET) was heated to about 90 ° C. above its glass transition point (Tg) and set in a pair of left and right bisected molds heated to about 150 ° C.
Next, while stretching the preform with a stretch rod, blow air is supplied at a pressure of about 3.0 MPa to perform biaxial stretch blow molding, and then cooling blow is performed at an air supply pressure of about 3.0 MPa. A round bottle container having a capacity of about 280 ml as shown in FIG. 1 was obtained in which five U-shaped horizontal grooves 5 were arranged at equal intervals.

The dimensions of the obtained container 1 are as follows: height H is about 132 mm, shoulder portion 31 has a height h ₁ of about 13 mm, and cylindrical portion 32 has a length h ₂ of about 90 mm. The maximum diameter φD of the part 3 (cylindrical part 32) was about 66 mm.
Further, the thickness t of the body portion 3 (tubular portion 32) is about 0.29 mm at a height of about 85 mm from the ground contact surface when the container 1 is placed on a horizontal surface with the mouth portion 2 up. t1), about 0.41 mm (t2) at about 71 mm, about 0.32 mm (t3) at about 55 mm, about 0.35 mm (t4) at about 40 mm, about 24 mm And about 0.38 mm (t5).
The distance h3 between the center lines C1 and C2 along the deepest part of each horizontal groove 5 is about 15 mm, and the position where each horizontal groove 5 is formed from the ground plane (the center line along the deepest part of each horizontal groove 5). ) Is about 78 mm for the top horizontal groove 5, about 63 mm for the second horizontal groove 5 from the top, about 48 mm for the third horizontal groove 5, about 32 mm for the fourth horizontal groove 5, The lateral groove 5 was about 17 mm. The groove depth d of each lateral groove 5 is about 2.0 mm (d1), about 4.0 mm (d2), about 2.6 mm (d3), and about 3.2 mm (d4) in order from the uppermost lateral groove 5, respectively. 3.6 mm (d5), and the width w of each lateral groove 5 is about 4.0 mm, about 4.6 mm, about 4.0 mm, about 4.1 mm, about It was 4.4 mm.

  Here, Table 1 shows the thicknesses t1 to t5 of the body 3 (cylindrical portion 32) at each position, the groove depths d1 to d5 of each lateral groove 5, and the groove width w of each lateral groove 5. 2A is a cross-sectional view of the round bottle container obtained in the present embodiment corresponding to the AA cross section in FIG. 1, and FIG. 2B shows the body 3 (cylindrical portion). 32) is a graph showing the relationship between the wall thicknesses t1 to t5 and the groove depths d1 to d5 of each lateral groove 5.

[Example 2]
In contrast to Example 1 in which the thickness distribution of the resulting round bottle container was kept loose, the temperature of each part of the preform was adjusted so as to be blow-molded with the wall thickness distribution shown in Table 2. In the same manner as in Example 1, a round bottle container having a capacity of about 280 ml in which five transverse grooves 5 having a U-shaped cross section were arranged at equal intervals was obtained.

  Here, the thicknesses t1 to t5 of the body portion 3 (tubular portion 32) at each position, the groove depths d1 to d5 of each lateral groove 5, and the groove width w of each lateral groove 5 are shown in Table 2. The dimensions of are the same as in Example 1. 3A is a cross-sectional view of the round bottle container obtained in the present embodiment, corresponding to the AA cross section in FIG. 1, and FIG. 3B shows the trunk portion 3 (tubular portion). 32) is a graph showing the relationship between the wall thicknesses t1 to t5 and the groove depths d1 to d5 of each lateral groove 5.

[Comparative Example 1]
Except for setting all the groove depths d1 to d5 of each horizontal groove 5 to 3.0 mm, the same as in Example 1, the five horizontal grooves 5 having a U-shaped cross section are arranged at equal intervals, and the capacity is about 280 ml. A round bottle container was obtained.
Here, Table 3 shows the wall thicknesses t1 to t5 of the body portion 3 (tubular portion 32) and the groove depths d1 to d5 of each lateral groove 5 at each position.

[Comparative Example 2]
Except that all the groove depths d1 to d5 of each lateral groove 5 are set to 4.0 mm, the five lateral grooves 5 having a U-shaped cross section are arranged at equal intervals in the same manner as in Example 1, and the capacity is about 280 ml. A round bottle container was obtained.
Here, Table 4 shows the thicknesses t1 to t5 of the body portion 3 (cylindrical portion 32) and the groove depths d1 to d5 of each lateral groove 5 at the above positions.

[Evaluation 1 (Buckling strength)]
As shown in FIG. 4, the round bottle containers obtained in Examples 1 and 2 and Comparative Examples 1 and 2 are set on the pressure receiving table 13 with the mouth portion 2 facing upward. A pressing member 11 provided with a notch 12 for escaping air was pressed against the mouth 2 and a longitudinal load was applied at a constant speed. With the passage of time, the pressing amount of the pressing member 11 increases, and accordingly, the load applied to the container 1 increases. When the load exceeds a certain load, the container 1 is significantly deformed and buckled. The transition was recorded by the load cell 10, and the load when the container 1 buckled was defined as the buckling strength. The results are shown in Table 5.

[Evaluation 2 (Decompression Strength)]
For each of the round bottle containers obtained in Examples 1 and 2 and Comparative Examples 1 and 2, after filling the container with water up to the upper end of the mouth part 2, the container is deformed or crushed unevenly. Vacuum suction was applied from the mouth 2 until the end. Table 5 shows the reduced pressure strength (load acting in the container 1) and the reduced pressure absorption amount (corresponding to the amount of water sucked).

[Evaluation 3 (lateral stiffness)]
Each of the round bottle containers obtained in Examples 1 and 2 and Comparative Examples 1 and 2 was filled with 280 g of hot water (87 ° C.) and sealed with a cap 6. After cooling with water so that the temperature became 0 ° C., the product was cooled to 5 ° C. with a refrigerator, and then the pressure was reduced to the same level as that in the vending machine.
Then, as shown in FIG. 5, when a pressing member having a width and thickness □ T of □ 10 mm is pressed against the side surface of the container placed horizontally on the horizontal surface, a load F of 59 N is applied from the vertical direction. The diameter φD1 of the body part 3 (tubular part 32) was measured along the vertical direction. The results are shown in Table 5.

  In addition, the container located on the lowermost side waiting for being discharged in a stacked state in the vending machine when it is offered for sale by the vending machine, the container side is supported by a stopper, Usually, the stopper is attached at a distance of about 20 mm from the side wall surface on the container bottom side of the passage through which the container is supplied in the vending machine. In the above measurement, the distance X from the bottom surface of the container to the edge of the pressing member was set to 20 mm in order to reproduce the state in which a lateral load was applied to the container in the vending machine.

As can be seen from the results shown in Table 5, in Example 1, all of buckling strength, reduced pressure strength, and lateral rigidity are improved compared to Comparative Example 1. In contrast to Comparative Example 2 which is excellent in reduced-pressure absorption performance and lateral rigidity but inferior in buckling strength, the reduced-pressure strength and lateral rigidity are in Comparative Example 2 although the buckling strength is greatly improved. It was confirmed that the buckling strength could be improved without reducing the reduced pressure strength and lateral load.
Moreover, in Example 2, it has improved in all of buckling strength, decompression strength, and lateral rigidity with respect to both the comparative examples 1 and 2, and especially buckling strength has improved remarkably.
As described above, according to the present invention, it was confirmed that the buckling strength against the longitudinal load can be improved and the reduced pressure absorption performance, the reduced pressure strength, and further the rigidity against the lateral load can be improved.

  Although the present invention has been described with reference to the preferred embodiment, it is needless to say that the present invention is not limited to the above-described embodiment, and various modifications can be made within the scope of the present invention. .

  For example, in the above-described embodiment, the container 1 having the cylindrical portion 32 formed in a cylindrical shape having substantially the same diameter is taken as an example. However, the specific shape of the container 1 is limited to such a case. Absent. As long as the cylindrical part 32 in which the horizontal groove 5 is formed approximates a cylindrical shape, for example, the cylindrical part may have a rectangular shape whose cross section is a polygon such as a hexagon or an octagon. Moreover, even if the cross section is a quadrangle, the present invention is applied by approximating a cylindrical shape by rounding or chamfering a corner portion or by curving a side surface outward. be able to.

  The present invention can also be applied to a relatively medium-capacity synthetic resin container having a volume of about 300 to 500 ml. However, the volume 100 tends to have a large thickness difference between the thick and thin portions in the thickness distribution. It is particularly suitable for a relatively small capacity synthetic resin container of about ~ 300 ml.

  As described above, according to the present invention, in a bottle container having an annular groove in the container body, the buckling strength against the longitudinal load while balancing the reduced pressure absorption performance, the reduced pressure strength, and the rigidity against the lateral load. The range of use as a bottle container can be further expanded.

It is a front view showing an outline of one embodiment of a synthetic resin container according to the present invention. 2 is an explanatory diagram of Embodiment 1. FIG. FIG. 6 is an explanatory diagram of Example 2. It is explanatory drawing which shows the evaluation method of buckling strength. It is explanatory drawing which shows the evaluation method of lateral rigidity. It is a front view which shows the outline of the modification in one Embodiment of the synthetic resin containers which concern on this invention.

Explanation of symbols

1 Container 2 Mouth 3 Body 4 Bottom 5 Horizontal Groove

Claims (4)

A synthetic resin container having a mouth, a body, and a bottom,
The trunk portion has a plurality of lateral grooves formed in an annular shape along the circumferential direction of the trunk portion ,
For each part where the lateral groove is formed, the groove depth of the lateral groove is changed according to the thickness of the body part ,
In the part where the thickness of the body portion on the upper side in the height direction of the part where one horizontal groove is formed among the plurality of horizontal grooves is relatively thin with respect to the thickness of the other part, A synthetic resin container characterized in that the groove depth is relatively shallow in accordance with the thickness of the body portion . A synthetic resin container having a mouth, a body, and a bottom,
The trunk portion has a plurality of lateral grooves formed in an annular shape along the circumferential direction of the trunk portion,
For each part where the lateral groove is formed, the groove depth of the lateral groove is changed according to the thickness of the body part,
In the part where the thickness of the trunk portion on the upper side in the height direction of the part where one horizontal groove is formed among the plurality of horizontal grooves is relatively thicker than the thickness of the other part, A synthetic resin container characterized in that the depth of the groove is relatively deep according to the thickness of the body portion. Between the thickness t [mm] of the trunk portion on the upper side in the height direction of the portion where one horizontal groove is formed among the plurality of horizontal grooves, and the groove depth d [mm] of the horizontal groove, the following formula ( The synthetic resin container according to claim 1 or 2 , wherein the relationship 1) is established.
α × t−3.1 ≦ d ≦ α × t−2.3 [where α = 16.7] (1)   The synthetic resin product according to any one of claims 1 to 3, wherein a shoulder portion that is continuous with the mouth portion is provided at a portion on the upper side in the height direction of the trunk portion, and a reduced pressure absorption panel is provided on the shoulder portion. container.

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