JP7003448B2 - Plastic container - Google Patents

Description

The present invention relates to a plastic container, and more particularly to a plastic container characterized by its shape.

Plastic containers, especially PET (PolyEthylene Terephthalate) bottles, are often used as containers for filling beverages and the like. The range of application of PET bottles is expanding.

In Patent Document 1, it is made of a thermoplastic resin, the shape of the horizontal cross section of the body has a concave portion toward the center, and the cross section of the body is formed from a curved line having a radius of curvature of 2 mm or more or a straight line. A plastic container characterized by being used is disclosed. Further, the shape of the vertical cross section of the shoulder portion of the plastic container of Patent Document 1 is formed by a curve having a radius of curvature of 33 mm.

Japanese Unexamined Patent Publication No. 58-073536

The plastic container of Patent Document 1 is said to have excellent pressure-reducing deformation resistance and heat-resistant deformation resistance, and have an excellent appearance. However, Patent Document 1 does not mention the vertical buckling strength (buckling strength), which is the strength to withstand the vertical load of the plastic container, and the side wall strength, which is the strength to withstand the horizontal load.

By the way, products filled in plastic containers are stored in vending machines, product shelves in shops, and the like. At this time, products manufactured with a size larger than the storage space of the vending machine or the product shelf cannot be stored, clogged, or cannot be taken out, which makes the product unsuitable. The same is true for transport devices when plastic containers and commodities are manufactured. Therefore, there are some restrictions on the dimensions of the plastic container.

On the other hand, there are many cases where it is necessary to increase the capacity of the contents as much as possible in response to the demands of consumers even within the dimensions of such a fixed limit. Then, in order to increase the capacity within such a limitation, a method of changing the shape of the shoulder can be considered. That is, the volume of the plastic container can be secured by changing the design of the shoulder portion extending from the mouth portion to the body portion from a state close to vertical to a shape extending in the horizontal direction.

However, in this way, the buckling strength of the plastic container decreases as the shoulders are stretched.

Therefore, an object of the present invention is to provide a plastic container which is particularly excellent in buckling strength while ensuring an internal volume within a predetermined dimension.

In order to solve the above problems, the present invention is a plastic container having a mouth, a shoulder, a body, and a bottom sequentially in the axial direction, wherein the body has a connecting portion of a right-angled body connected to the shoulder. The shoulder portion has a plurality of ridge lines extending radially in a plan view, the ridge line extends continuously to the connection portion, and the shoulder portion has a trapezoidal panel between the ridge lines, and the connection portion is provided. The portion has a rectangular panel between the ridges, the ridges projecting outwards, and the trapezoidal panel and the rectangular panel are radially inward in a cross section perpendicular to the axial direction. The shoulders are curved so that the shape of the vertical cross section of the ridge has a single radial radius of curvature that is convex outward in the radial direction and faces at the end of the shoulder on the side of the mouth. The opening angle formed by the tangent at the end is 100 ° or more and 157 ° or less.

Further, the trapezoidal panel and the rectangular panel have another ridge line extending in the axial direction at the center of the circumferential direction, and the other ridge line is located inside the radial direction with respect to the ridge line . It is a feature.

Further, the radius of curvature is 0.35 times or more and 1.18 times or less the maximum body diameter.

Further, the number of trapezoidal panels is 18 or more and 30 or less.

According to the present invention, in a plastic container having a mouth, a shoulder, a body, and a bottom in order in the axial direction, the body has a connecting portion of a rectangular body connected to the shoulder, and the shoulder is viewed in a plan view. It has multiple ridges that extend radially, the ridges extending continuously to the connections, the shoulders having trapezoidal panels between the ridges, and the connections having rectangular panels between the ridges. , The ridges project outwards, the trapezoidal panel and the rectangular panel bend inward in the radial direction in a cross section perpendicular to the axial direction, and the shoulders are radial in shape in the vertical cross section of the ridges . It is characterized by having a single radius of curvature convex to the outside of the mouth, and at the end of the shoulder on the side of the mouth, the opening angle formed by the tangents at the opposite ends is 100 ° or more and 157 ° or less. It is possible to provide a plastic container having a particularly excellent buckling strength while ensuring an internal volume within a predetermined size.

Further, the trapezoidal panel and the rectangular panel have another axially extending ridgeline in the center of the circumferential direction, and the other ridgeline has a predetermined dimension according to the configuration in which the ridgeline is located radially inside the ridgeline. It is possible to provide a plastic container in which the buckling strength is particularly enhanced while the internal volume is secured.

Furthermore, according to the configuration in which the radius of curvature is 0.35 times or more and 1.18 times or less of the maximum body diameter, the buckling strength is particularly enhanced while the internal volume is secured within the predetermined dimensions. Plastic containers can be provided.

Further, according to the configuration in which the number of trapezoidal panels is 18 or more and 30 or less, it is possible to provide a plastic container in which the internal volume is secured within the predetermined dimensions but the buckling strength is particularly increased. ..

It is a front view which showed the PET bottle as an example of the plastic container which concerns on this embodiment. It is the front view which the shoulder part was enlarged. It is sectional drawing of the shoulder part of the PET bottle cut by the line III-III of FIG. It is a front view which showed the PET bottle as an example of the plastic container which concerns on another embodiment. It is sectional drawing of the shoulder part of the PET bottle cut by the VV line of FIG. It is sectional drawing of the connection part of the PET bottle cut by the VI-VI line of FIG. It is a front view of the PET bottle of the comparative example 1. FIG. FIG. 3 is an enlarged front view of the shoulder portion of Comparative Example 1. It is a front view of the PET bottle of the comparative example 2. FIG. FIG. 3 is an enlarged front view of the shoulder portion of Comparative Example 2.

Hereinafter, the details of the embodiment of the present invention will be described with reference to the drawings. First, the configuration of the plastic container according to the present embodiment will be described in detail. The plastic container according to the present embodiment is a blow-molded container that is processed by blow-molding from its prototype preform (preformed body). FIG. 1 is a front view showing a PET bottle 1 as an example of a plastic container according to the present embodiment. In the following, for convenience of explanation, the mouth portion 10 in which the contents are taken in and out in the state of FIG. 1 in which the PET bottle 1 is upright and its axial direction extends vertically is referred to as the top. The PET bottle 1 has a mouth portion 10, a shoulder portion 20, a body portion 30, and a bottom portion 40 in order in the axial direction.

The mouth portion 10 extends in a cylindrical shape in the axial direction of the PET bottle 1. The mouth portion 10 has an annular cross section perpendicular to the axial direction. In the mouth portion 10, the opening 11 is formed in the radial direction perpendicular to the axial direction. The opening 11 is a filling port and a spout for the contents.

The mouth portion 10 has an annular support ring 12 protruding outward in the radial direction below the center in the axial direction. The support ring 12 is used for supporting the PET bottle 1 when it is molded or transported.

The mouth portion 10 has a screw 13 on the outer periphery thereof for attaching a lid (not shown). The PET bottle 1 is sealed by attaching a lid to the mouth portion 10. The PET bottle 1 may be configured to be hermetically sealed. For example, when a stopper-type lid is used, protrusions and grooves may be formed on the outer and inner circumferences of the mouth portion 10 instead of the male screw 13. .. Further, the PET bottle 1 may be configured such that a peelable sealing seal is attached to the upper end of the mouth portion 10 if it is not necessary to reseal after opening the bottle.

An annular turnip 14 may be formed between the support ring 12 and the male screw 13 so as to project radially outward from the outer periphery of the mouth portion 10. When the PET bottle 1 is transported, the gripper of the transport equipment can grip the PET bottle 1 by sandwiching the recess between the turnip 14 and the support ring 12. The support ring 12 projects radially outward from the turnip 14.

The upper side of the mouth portion 10 in the axial direction from the support ring 12 may be crystallized by heating with a so-called crystallization device so as to have the heat resistance required for filling the contents at a high temperature until it becomes white.

The mouth portion 10 has a neck portion 15 at the lower end in the axial direction. The neck portion 15 is connected to the support ring 12 at the upper end in the axial direction. The neck portion 15 is formed in a true cylindrical shape in which its outer diameter and wall thickness hardly change in the vertical direction. The neck portion 15 has a smaller outer diameter than the support ring 12. Therefore, the lower surface of the support ring 12 extends outward in the radial direction with the outer peripheral surface of the neck portion 15 as the base. When the PET bottle 1 is transported, the gripper of the transport equipment can grip the PET bottle 1 by using the lower surface of the support ring 12 and the outer peripheral surface of the neck portion 15.

The body portion 30 is connected to the shoulder portion 20 at the connecting portion 31 at the upper end in the axial direction, and is connected to the bottom portion 40 at the lower end portion in the axial direction. The body portion 30 is a portion having the maximum outer diameter (maximum body diameter D) of the PET bottle 1. The body portion 30 illustrated in FIG. 1 extends in a cylindrical shape in the axial direction and is formed into a substantially sized body. The body portion 30 has an annular cross section perpendicular to the axial direction. That is, the PET bottle 1 is a so-called round bottle.

The plastic container according to the present embodiment is not limited to the body portion 30 of the substantially sized body illustrated, and may have a configuration having different diameters in the vertical direction. Further, the plastic container according to the present embodiment is not limited to the illustrated round bottle, and may be a so-called square bottle having a body portion formed by connecting a plurality of panels in the circumferential direction.

The connecting portion 31 is preferably a small cylinder. As a result, since the cross-sectional area of the connecting portion 31 is constant, the internal volume of the PET bottle 1 can be easily adjusted regardless of the shape of the shoulder portion 20, and the internal volume of the PET bottle 1 can be easily adjusted regardless of the shape of the body portion 30. It is possible to improve the stability when the PET bottle 1 is placed sideways. In particular, since the PET bottle 1 having the small connecting portion 31 can stably maintain the state of being laid sideways when loaded inside the vending machine, the PET bottle 1 can be normally removed from the vending machine. The vendor suitability, which is the characteristic of being discharged, can be made excellent.

As illustrated in FIG. 1, the body portion 30 has a pressure absorbing panel 32. A plurality of pressure absorbing panels 32 are provided at equal intervals in the circumferential direction of the body portion 30. As a result, a columnar portion 33 extending in the axial direction is formed in the region between the adjacent pressure absorbing panels 32, 32. In these, the pressure absorbing panel 32 is formed with a wide width and the columnar portion 33 is formed with a narrow width in the circumferential direction. As a result, the pressure absorbing panel 32 is configured to be deformable in and out in the radial direction, while the columnar portion 33 is configured to have increased rigidity and hardly deformed. The columnar portion 33 has the same function as a so-called vertical rib (vertical groove) extending vertically in the axial direction, and improves the buckling strength of the body portion 30.

The pressure absorbing panel 32 is configured to change the internal volume of the PET bottle 1 by deforming inward and outward in the radial direction when the internal pressure (internal pressure) of the PET bottle 1 changes. The pressure absorbing panel 32 configured in this way has a function of absorbing a change in internal pressure and preventing the PET bottle 1 from being deformed as a whole. On the other hand, even when the internal pressure of the PET bottle 1 changes, the structure itself of the body portion 30 is maintained with the columnar portion 33 as the skeleton. Therefore, the structure of the body portion 30 having the pressure absorbing panel 32 and the columnar portion 33 can absorb the change in the internal pressure of the PET bottle 1 and prevent the PET bottle 1 from being distorted.

The pressure absorption panel 32 exemplified in FIG. 1 has a rectangular shape with rounded corners having two parallel sides along the axial direction and having a long axis extending in the axial direction. The body portion 30 illustrated in FIG. 1 has six pressure absorbing panels 32. Each of the pressure absorbing panels 32 has a step wall surface 34, a connecting surface 35, and a convex rib 36.

The step wall surface 34 is recessed one step inward from the outer surface of the surrounding body portion 30 in the radial direction. The step wall surface 34 has a rectangular shape with all corners rounded, and a cross section perpendicular to the axial direction (horizontal cross section) is curved inward in the radial direction. The connecting surface 35 surrounds the step wall surface 34. The connecting surface 35 is composed of two rectangular sides extending parallel to each other in the axial direction and two arc-shaped sides having an arc shape on the outer side in the axial direction at the upper and lower ends in the axial direction. It is composed of edges. All four sides of the connecting surface 35 are inclined with respect to the direction in which the step wall surface 34 extends. The convex rib 36 projects radially outward from the step wall surface 34 and extends linearly in the axial direction. The convex rib 36 extends from the upper end to the lower end in the axial direction of the step wall surface 34. A plurality of convex ribs 36 are formed and are arranged at equal intervals in the circumferential direction.

When the inside of the PET bottle 1 is depressurized and the body portion 30 is pulled inward in the radial direction, the uneven surface formed by the step wall surface 34 and the convex rib 36 is stretched, so that the pressure absorbing panel 32 is radially inward. It is configured to easily deform inward. Further, the step wall surface 34, which is a one-step recess and curves in the circumferential direction toward the inside in the radial direction, is configured so that the curve does not reverse and deforms in response to a change in the internal pressure of the PET bottle 1, particularly a change in decompression. Has been done. Further, the connecting surface 35 can prevent the deformation of the pressure absorbing panel 32 from spreading to the surrounding body portion 30. Therefore, the pressure absorbing panel 32 can effectively absorb the change in the internal pressure of the PET bottle 1, particularly the change in the reduced pressure, and can prevent the PET bottle 1 from being distorted.

The convex rib 36 increases the rigidity of the pressure absorbing panel 32 and thus the body portion 30. As a result, it is possible to prevent excessive deformation of the step wall surface 34, make the body portion 30 have an appropriate hardness to make it easier to hold the PET bottle 1, and increase the buckling strength of the PET bottle 1. On the other hand, if the number of convex ribs 36 is too large, the pressure absorbing panel 32 is less likely to be deformed and the pressure absorbing function is deteriorated. Therefore, it is designed so that the number and dimensions of the convex ribs 36 are appropriate. FIG. 1 shows an example in which nine convex ribs 36 are formed for one pressure absorbing panel 32.

The pressure absorbing panel 32 is not limited to the configuration exemplified in FIG. 1, and has a shape, number, and a range that effectively absorbs changes in internal pressure to prevent deformation of the PET bottle 1 and has good shapeability. The dimensions, angles, etc. may be designed. For example, the pressure absorbing panel 32 may be replaced with a rectangular panel, and the panel may be twisted in the circumferential direction in the vertical direction. The convex rib 36 is not limited to the configuration exemplified in FIG. 1, and may be a concave rib, these ribs may extend in any direction, or the ribs may intersect with each other. Moreover, the pressure absorbing panel 32 may not have ribs.

The body portion 30 has a peripheral groove 37 and a peripheral groove 38, respectively, above and below the pressure absorbing panel 32. Both the peripheral groove 37 and the peripheral groove 38 have the same function as the so-called lateral rib (lateral groove), and improve the side wall strength of the body portion 30. Further, both the peripheral groove 37 and the peripheral groove 38 function as a cushion by increasing the elastic limit with respect to the vertical load in the axial direction. As a result, the PET bottle 1 is less likely to buckle, although the displacement is large with respect to the vertical load in the axial direction.

Each of the peripheral groove 37 and the peripheral groove 38 exemplified in FIG. 1 is recessed inward in the radial direction from the outer surface of the body portion 30 and extends around the body portion 30. In both the cross sections of the peripheral groove 37 and the peripheral groove 38, both sides of the groove are curved toward the outside in the radial direction of the PET bottle 1, and the bottom of the groove is formed flat. The peripheral groove 37 and the peripheral groove 38 may be formed in a straight line on both sides of the groove, or may have a U-shaped cross section as a whole without having a flat bottom.

The body portion 30 is not limited to the configuration exemplified in FIG. 1, and the shape, number, and position of the pressure absorbing panel 32, the peripheral groove 37, and the peripheral groove 38 may be arbitrarily designed. Further, the body portion 30 may not have the pressure absorbing panel 32, the peripheral groove 37, and the peripheral groove 38.

The bottom portion 40 is connected to the body portion 30 at the upper end in the axial direction. The bottom portion 40 has a corner portion 41, a bottom wall 42, and a dome 43. The corner portion 41 is curved toward the lower side in the axial direction of the PET bottle 1 and the outer side in the radial direction. The flat plate annular bottom wall 42 extends in the direction perpendicular to the body portion 30 and serves as a ground plane for the PET bottle 1.

In FIG. 1, the dome 43 exemplified by the hidden line is formed in a truncated cone shape that curves toward the inside (upper side in the axial direction) of the PET bottle 1. The dome 43 has a function of preventing deformation due to heat of the contents of the PET bottle 1 and changes in the internal pressure. The dome 43 may be designed with an angle of inclination with respect to the ground contact surface within a range in which the internal pressure or the like is effectively dispersed to prevent the PET bottle 1 from being deformed and the shapeability is good. Further, the dome 43 may be configured to project in a plurality of steps toward the upper side in the axial direction on the inner side in the radial direction. Further, the bottom portion 40 may be formed with ribs having a function of reinforcing the dome 43, for example, radial ribs.

The bottom portion 40 is not limited to the configuration exemplified in FIG. 1, and is deformed downward in the axial direction even if the inside of the PET bottle 1 is positively pressured in a state where it is easily deformed by heat as in the case of filling the contents. It is good if the configuration is difficult to do. In particular, the dome 43 may be designed to be maintained at least above the ground plane of the PET bottle 1 even if it is deformed by heat. As a result, the bottom portion 40 is prevented from protruding outward from the bottom wall 42 (lower side in the axial direction), and the dimensions of the PET bottle 1, particularly the total height, become larger than the design value, or the PET bottle 1 It is possible to prevent the ground contact surface of the surface from being uneven and the buckling strength from being lowered.

FIG. 2 is an enlarged front view of the shoulder portion 20. The shoulder portion 20 is connected to the mouth portion 10 at the upper end in the axial direction, and is connected to the body portion 30 at the lower end in the axial direction. The upper and lower ends of the shoulder portion 20 may be chamfered. The shoulder portion 20 is configured to extend outward in the radial direction of the PET bottle 1 from the upper side in the axial direction to the lower side in the axial direction.

The shoulder portion 20 is formed in a cylindrical shape whose diameter increases from the side of the mouth portion 10 toward the side of the body portion 30. The shoulder portion 20 has a cross-sectional shape (vertical cross-section) parallel to the axial direction through the center in the radial direction, and appears as two curves 21 and 21 on both the left and right sides in FIG. The curves 21 and 21 each have a single radius of curvature r that is convex outward in the radial direction. This facilitates the design of the shoulder portion 20 and improves its shapeability. Further, when the shoulder portion 20 is composed of the curve 21 having a single radius of curvature r, the stress with respect to the axial load is effectively dispersed, and at the bending point which is the starting point when buckling occurs. The buckling strength of the PET bottle 1 is enhanced because the portion that tends to be easily formed is not formed.

If the radius of curvature r of the curve 21 is too small, the mouth portion 10 tends to buckle on the upper side of the shoulder portion 20, and the buckling strength decreases. On the other hand, if the radius of curvature r of the curve 21 is too large, it becomes difficult to secure the internal volume, and the buckling strength tends to decrease as the mouth portion 10 falls under the shoulder portion 20. It ends up. Therefore, the radius of curvature r is preferably 0.35 times or more and 1.18 times or less the maximum body diameter D.

At the end of the shoulder portion 20 on the side of the mouth portion 10, the angle formed by the tangents 22 and 22 at the opposite ends is defined as the opening angle θ. The tangents 22, 22 and the opening angle θ here have the shape of a vertical cross section similar to the radius of curvature r described above. It does not matter if the shape of the vertical cross section of the shoulder portion 20 and the shape of the left and right ends of the shoulder portion 20 in the front view are the same. Therefore, the straight line with the upper end of the curve 21 in FIG. 2 as a contact point is the tangent line 22.

If the opening angle θ is too small, it becomes difficult to secure the internal volume. On the other hand, if the opening angle θ is too large, the mouth portion 10 tends to buckle on the upper side of the shoulder portion 20, and the buckling strength decreases. Therefore, the opening angle θ is preferably 100 ° or more and 157 ° or less.

The PET bottle 1 has a ridge line 23 extending axially linearly from the upper end to the lower end of the shoulder portion 20 in a front view. Although not shown, the ridge line 23 extends linearly in the radial direction from the inner end to the outer end of the shoulder portion 20 in a plan view. The shoulder portion 20 has a plurality of ridge lines 23, and the plurality of ridge lines 23 extend radially in a plan view. An isosceles trapezoidal panel 24 is formed in a plan view in a region surrounded by closed curves on four sides of the inner end line, the outer end line, and the adjacent ridge lines 23, 23 of the shoulder portion 20. That is, the shoulder portion 20 is configured by connecting a plurality of trapezoidal panels 24 in the circumferential direction. The plurality of trapezoidal panels 24 may have different shapes, but are preferably the same shape from the viewpoint of improving the buckling strength. Since the plurality of trapezoidal panels 24 have the same shape, the strength of the shoulder portion 20 in the circumferential direction is equalized, and the buckling strength is improved. Here, the ridge line 23 extends from the upper end to the lower end of the shoulder portion 20. That is, the trapezoidal panel 24 extends from the upper end to the lower end of the shoulder portion. Therefore, the shoulder portion 20 is less likely to have a weak portion in the axial direction, and the buckling strength is improved.

FIG. 3 is a cross-sectional view of the shoulder portion 20 of the PET bottle 1 cut along the line III-III of FIG. The shoulder portion 20 is configured by connecting a plurality of trapezoidal panels 24 in the circumferential direction centered on the axial direction, and the ridge line 23 is a joint portion between adjacent trapezoidal panels 24. The trapezoidal panel 24 may be curved inward or outward in the radial direction of the PET bottle 1.

The ridge line 23 between the adjacent trapezoidal panels 24 acts like a reinforcing rib to increase the rigidity of the shoulder portion 20 and improve the strength against a load in the vertical direction when the shoulder portion 20 is viewed from the front. Therefore, even if the shoulder portion 20 is stretched to secure the internal volume of the PET bottle 1 and the shape is such that the buckling strength is difficult to be secured, the strength against the axial and radial loads of the PET bottle 1, that is, the buckling Strength and side wall strength are increased. Further, when the internal pressure of the PET bottle 1 changes, the trapezoidal panel 24 easily deforms inside and outside the PET bottle 1, whereas the ridge line 23 hardly deforms, so that the trapezoidal panel 24 absorbs the change in the internal pressure. It also has a function of preventing the PET bottle 1 from being deformed as a whole.

If the number of trapezoidal panels 24 is too small, the effect of reinforcing the strength of the shoulder portion 20, and thus the PET bottle 1, particularly the buckling strength, is weakened. On the other hand, if the number of trapezoidal panels 24 is too large, the shapeability will not be good, or the shape will be substantially the same as a circle, and conversely, the effect of reinforcing the strength of the PET bottle 1, especially the buckling strength, will be obtained. It gets weaker. Therefore, it is preferable that the number of trapezoidal panels 24 is 18 or more and 30 or less. As a result, the strength of the PET bottle 1, particularly the buckling strength, can be increased while improving the shapeability of the PET bottle 1. The shoulder portion 20 illustrated in FIG. 3 and the like is configured by connecting 24 trapezoidal panels 24 having the same shape in the circumferential direction, and has 24 ridge lines 23.

There is no big difference in strength between the ridge line 23 and the trapezoidal panel 24 regardless of whether they are odd numbers or even numbers. However, if these are composed of an even number, the mold dividing line (parting line) and the ridge line 23 of the mold can be easily aligned at the time of biaxial stretch blow molding, and the appearance of the PET bottle 1 is good. Can be. Further, the ridge lines 23 do not have to be evenly spaced in the circumferential direction. That is, the shape of each trapezoidal panel 24 may be different. However, since the ridge lines 23 are configured at equal intervals in the circumferential direction, the design of the shoulder portion 20 becomes easy, the shapeability thereof becomes good, and the load on the shoulder portion 20 is effectively dispersed. Strength, especially buckling strength, is improved.

Next, the configuration of the plastic container according to another embodiment will be described in detail. Here, the differences from the PET bottle 1 described above will be described in detail, and the same components will be designated by the same reference numerals and the description thereof will be omitted as appropriate. FIG. 4 is a front view showing a PET bottle 2 as an example of a plastic container according to another embodiment. The PET bottle 2 has a connection portion 231 corresponding to the connection portion 31 of the PET bottle 1. As illustrated in the PET bottle 2 of FIG. 4, the body portion 230 has a ridge line 233 in which the ridge line 223 between the adjacent trapezoidal panels 224 of the shoulder portion 220 corresponding to the ridge line 23 between the adjacent trapezoidal panels 24 extends in the axial direction. Is more preferably provided in the connecting portion 231.

When the plastic container is biaxially stretched and blow molded, the preform, which is formed with a shorter axial length, is stretched in the axial (longitudinal) direction of the plastic container, and the upper side of the stretched portion is It tends to be thin and the lower side tends to be thick. Therefore, it is difficult to secure the strength on the upper side of the stretched portion, for example, near the base of the shoulder portion 220 and the body portion 230. However, the PET bottle 2 has a ridge line 233 at the connection portion 231 near the upper end of the body portion 230, which acts like a reinforcing rib to increase the rigidity and make it easier to hold the PET bottle 2, for example. be able to. Further, the ridge line 233 provided in the connecting portion 231 improves the buckling strength and the side wall strength of the PET bottle 2. In particular, by increasing the side wall strength of the PET bottle 2, the strength when stacked horizontally in a vending machine is ensured, and the vendor suitability can be improved.

The shoulder portion 220 is configured by connecting a plurality of trapezoidal panels 224 corresponding to the trapezoidal panels 24 of the PET bottle 1 in the circumferential direction. Similarly, the connecting portion 231 is configured by connecting rectangular panels 234 having a rectangular shape in the front view in the circumferential direction. The ridge line 233 is a joint portion of the adjacent rectangular panels 234. The rectangular panel 234 may be curved inward or outward in the radial direction of the PET bottle 2.

In the PET bottle 2, all of the ridge lines 223 of the shoulder portion 220 extend as they are as the ridge lines 233 of the connecting portion 231. When the ridge line 223 and the ridge line 233 are continuously configured, the design of the shoulder portion 220 and the connecting portion 231 becomes easy and the shapeability thereof becomes good. Further, since the ridge line 223 and the ridge line 233 are continuous, the load on the shoulder portion 220 and the connection portion 231 is effectively dispersed, and the strength, particularly the buckling strength is improved.

As with the trapezoidal panel 24 described above, the number of the trapezoidal panel 224 and the rectangular panel 234 are preferably 18 or more and 30 or less. As a result, the strength of the PET bottle 2, particularly the buckling strength, can be increased while improving the shapeability of the PET bottle 1. However, the ridge line 223 and the ridge line 233 do not have to be all continuous, and the ridge lines 223 and the ridge line 233 do not necessarily have to be the same number.

5 is a cross-sectional view of the shoulder portion 220 of the PET bottle 2 cut along the VV line of FIG. 4, and FIG. 6 is a connection portion 231 of the PET bottle 2 cut along the VI-VI line of FIG. It is a cross-sectional view of. In the PET bottle 2, as illustrated in FIGS. 5 and 6, both the trapezoidal panel 224 of the shoulder portion 220 and the rectangular panel 234 of the connecting portion 231 are curved inward in the radial direction of the PET bottle 2. There is.

The trapezoidal panel 224 and the rectangular panel 234 are curved inward in the radial direction of the PET bottle 2, so that the ridge line 223 and the ridge line 233 stand out more and the rigidity of the shoulder portion 220 and the connection portion 231 is further increased. As a result, the buckling strength of the PET bottle 2 is further increased.

When the trapezoidal panel 224 and the rectangular panel 234 are configured to be curved inward in the radial direction of the PET bottle 2, at least the shape of the vertical cross section of the ridge line 223 is a single radius of curvature convex outward in the radial direction. It may be r.

The trapezoidal panel 224 and the rectangular panel 234 may be curved inward in the radial direction of the PET bottle 2 only in the shoulder portion 220, or may be a part of the shoulder portion 220. ..

Further, although the description by illustration is omitted, the trapezoidal panel 224 and the rectangular panel 234 may be configured to bend inward in the radial direction of the PET bottle 2. That is, the trapezoidal panel 224 and the rectangular panel 234 may have a configuration having a crease (a ridge line different from the ridge line 223 and the ridge line 233) extending in the axial direction at the center in the circumferential direction. Another ridge of the shoulder 220 is located radially inside the PET bottle 2 with respect to the ridge 223. Similarly, another ridge of the connecting portion 231 is located radially inside the PET bottle 2 with respect to the ridge 233. Even with such a configuration, the buckling strength of the shoulder portion 220 and the connecting portion 231 can be improved.

The shapes other than the shoulder portion 20 of the PET bottle 1 and the shoulder portion 220 of the PET bottle 2 are not limited to the examples shown in FIG. 1 and may be any shape. For example, in the present embodiment, it can be suitably used for the round bottle of the barrel shown in FIG. However, the plastic container to which this embodiment is applied is not limited to a round bottle with a small cylinder, and may be a bottle having a constricted portion having a narrowed body diameter. Further, the shapes of the pressure absorbing panels, the horizontal grooves, and the vertical grooves provided on the body portion 30 and the body portion 230 can be freely designed.

The PET bottle 1 and the PET bottle 2 (hereinafter collectively referred to as PET bottle 1) according to the present embodiment are not limited by size and can be applied to various sizes. For example, the internal volume of the PET bottle 1 is preferably 80 ml or more and 2000 ml or less, and more preferably 200 ml to 1000 ml. The total length of the PET bottle 1 in the axial direction may be 90 mm or more and 310 mm or less, and the maximum body diameter D of the body portion 30 may be 40 mm or more and 105 mm or less.

Further, the PET bottle 1 according to the present embodiment can be suitably used for a lightweight bottle. In particular, from the viewpoint of maintaining the buckling strength of the PET bottle 1 while having light weight, when the internal volume is, for example, 320 ml, the mass of the material is preferably 12 g or more and 22 g or less.

As the material of the plastic container for which the PET bottle 1 is exemplified, a polyolefin such as high-density polyethylene, medium-density polyethylene, low-density polyethylene, linear low-density polyethylene, polypropylene, an ethylene-vinyl alcohol copolymer, a plant, or the like is used as a raw material. Various plastics that can be blow-molded, such as polyethylene, can be used. However, it is preferable that the plastic container is mainly composed of polyester such as polyethylene naphthalate, particularly polyethylene terephthalate. The above-mentioned resin contains various additives such as colorants, ultraviolet absorbers, mold release agents, lubricants, nucleating agents, antioxidants, and antistatic agents as long as the quality of the molded product is not impaired. be able to.

As the ethylene terephthalate-based thermoplastic resin constituting the PET bottle 1, the ethylene terephthalate unit occupies most of the ester repeating portion, generally 70 mol% or more, and the glass transition point (Tg) is 50 ° C. or higher and 90 ° C. or higher. It is preferable that the melting point (Tm) is 200 ° C. or higher and 275 ° C. or lower. As an ethylene terephthalate-based thermoplastic polyester, polyethylene terephthalate is particularly excellent in terms of pressure resistance, etc., but it is composed of dibasic acids such as isophthalic acid and naphthalenedicarboxylic acid, and diols such as propylene glycol, in addition to the ethylene terephthalate unit. Copolymerized polyesters containing a small amount of ester units can also be used.

Polyethylene terephthalate has the highest production volume among thermoplastic synthetic resins. The polyethylene terephthalate resin has various properties such as heat resistance, cold resistance, chemical resistance, and abrasion resistance. Furthermore, polyethylene terephthalate resin has a lower proportion of petroleum in its raw material than other plastics, and can be recycled. As described above, according to the configuration containing polyethylene terephthalate as a main component, a material having a large production amount can be used, and various excellent properties thereof can be utilized.

Polyethylene terephthalate is obtained by condensation polymerization of ethylene glycol (ethane-1,2-diol) and purified terephthalic acid. It is preferable that at least one of a germanium compound, a titanium compound, and an aluminum compound is used as the polymerization catalyst of polyethylene terephthalate. By using these catalysts, it is possible to form a container having higher transparency and excellent heat resistance than the antimony compound is used.

By molding the above-mentioned material, the plastic container according to the present embodiment can be manufactured. The plastic container is preferably a molding method that combines the production of a preform by injection molding and the processing from the preform to a plastic container by biaxial stretch blow molding. A plastic container using biaxial stretch blow molding has a high stretching effect and excellent strength.

The preform may be molded and then boxed and temporarily stored in a warehouse or the like, or may be continued as it is to the next step. That is, a so-called cold parison method (two-stage method) in which preform molding and biaxial stretching blow molding are performed at different locations or devices may be used, and both are performed at the same location or device. The so-called hot parison method (one-stage method) may be used. Further, the manufacturing process from the molding of the preform to the filling of the contents may be continuous in-line.

The method of filling the contents of the PET bottle 1 is also not limited. Therefore, the PET bottle 1 may be used for hot filling or aseptic filling.

As described above, the PET bottle 1 (PET bottle 2) has a mouth portion 10, a shoulder portion 20 (shoulder portion 220), a body portion 30 (body portion 230), and a bottom portion 40 in order in the axial direction, and the shoulder portion. Reference numeral 20 is configured by connecting a plurality of trapezoidal panels 24 (trapezoidal panels 224) in the circumferential direction centered on the axial direction, and passing through a radial center perpendicular to the axial direction and a cross section parallel to the axial direction (vertical cross section). ) (Curve 21) has a single radial radius of curvature r that is convex outward.

The PET bottle 1 and the PET bottle 2 configured in this way can be particularly excellent in buckling strength while the internal volume is secured within the predetermined dimensions.

Hereinafter, the present disclosure will be described in more detail and concretely with reference to Examples. However, the present disclosure is not limited to the following examples.

<Materials and manufacturing methods>
[Example 1]
A preform made of 21.8 g of polyethylene terephthalate was blow-molded by biaxial stretching to prepare a normal bottle of PET bottle 1 shown in FIG. 1 and the like. In the PET bottle 1, the radius of curvature r of the shoulder portion 20 is 35.3 mm, and the opening angle θ is 145.3 °. Round chamfers were made between the mouth portion 10 and the shoulder portion 20 and between the shoulder portion 20 and the connecting portion 31 with a radius of 4 mm, respectively.

The bottles of all the examples and comparative examples were decided to have a total height of 138 mm, a maximum body diameter D of 68 mm, and a full filling capacity of 336 ml. Then, the bottles of each example were filled with 320 ml of water and then closed with a lid (not shown) to prepare a filler.

In order to make the full filling capacity uniform without changing the total height of bottles having different shoulder shapes in each example, the upper end of the body portion 30, that is, the axial length of the connecting portion 31 was changed. In the PET bottle 1 according to the first embodiment, the axial length (body height) from the bottom wall 42 to the upper end of the connecting portion 31 is 92.9 mm.

Further, in the same manner, a preform made of 18.3 g of polyethylene terephthalate was biaxially stretch-blow molded to prepare a filler of PET bottle 1 made of a lightweight bottle as shown in FIG. 1 and the like. In the PET bottle 1 according to the first embodiment, the shoulder portion 20 is configured by connecting a plurality of trapezoidal panels 24 in the circumferential direction centered on the axial direction, and the vertical cross section represented by the curve 21 in FIG. 2 and the like. Has a feature according to the present embodiment, such as having a single radius of curvature r whose shape is convex outward in the radial direction.

[Example 2]
In the PET bottle 2 of the second embodiment, as shown in FIGS. 5 and 6, the trapezoidal panel 224 of the shoulder portion 220 and the rectangular panel 234 of the connecting portion 231 are curved inward in the radial direction of the PET bottle 2. In that respect, it was different from the PET bottle 1 of Example 1. However, the PET bottle 2 according to the second embodiment also has a shoulder portion 220 formed by connecting a plurality of trapezoidal panels 224 in the circumferential direction centered on the axial direction, and the shape of the vertical cross section is a single convex outward in the radial direction. It had features according to the present embodiment, such as having a single radius of curvature r.

[Comparative Example 1]
FIG. 7 is a front view of the PET bottle 300 of Comparative Example 1. The PET bottle 300 had a mouth portion 10, a shoulder portion 320, a body portion 330, and a bottom portion 40 in that order in the axial direction, and did not have a configuration corresponding to the trapezoidal panel 24 of the first embodiment. Therefore, the filler according to Comparative Example 1 did not have the characteristics according to the present embodiment.

FIG. 8 is an enlarged front view of the shoulder portion 320 of Comparative Example 1. In the PET bottle 300, the radius of curvature r of the shoulder portion 320 is 33.2 mm, the opening angle θ is 144.8 °, and the body height is 92.88 mm. Therefore, the PET bottle 300 of Comparative Example 1 had substantially the same shape as the PET bottle 1 of Example 1.

[Comparative Example 2]
FIG. 9 is a front view of the PET bottle 400 of Comparative Example 2. The PET bottle 400 had a mouth portion 10, a shoulder portion 420, a body portion 430, and a bottom portion 40 in that order in the axial direction, and did not have a configuration corresponding to the trapezoidal panel 24 of the first embodiment. Therefore, the filler of Comparative Example 2 did not have the characteristics according to the present embodiment.

FIG. 10 is an enlarged front view of the shoulder portion 420 of Comparative Example 2. In the PET bottle 400, the radius of curvature r of the shoulder portion 420 is set to 23 mm, the opening angle θ is set to 157.2 °, and the body height is set to 89.63 mm. Therefore, the PET bottle 400 of Comparative Example 2 has a smaller radius of curvature r and a larger opening angle θ than the PET bottle 1 of Example 1.

<Evaluation method>
(Buckling strength test)
The buckling strength test of each of the fillers of Example 1, Example 2, Comparative Example 1, and Comparative Example 2 in an upright state was performed. For the measurement of buckling strength, TOP LOAD TESTER MODEL NO., A tester manufactured by Agr Top Wave. C506-02-0001 was used. A load is applied from above the mouth 10 at a constant speed, and the maximum load in a so-called yield state is the buckling load [N], which is an index of buckling strength, and the displacement at that time is the buckling displacement [mm]. It was said. Table 1 shows the results of the buckling strength test.

The following points were derived from the above-mentioned examples. In Comparative Example 2, since the opening angle θ was too large, buckling occurred on the upper side of the shoulder portion 420, and as shown in Table 1, the result was that the buckling strength was extremely weak. Compared with Comparative Example 2, in Comparative Example 1 in which the radius of curvature r was larger and the opening angle θ was smaller, the buckling displacement was slightly larger, but the buckling strength was increased. In Example 1 having a shape substantially similar to that of Comparative Example 1, the buckling strength was significantly increased. Further, in the second embodiment in which the plurality of trapezoidal panels 224 constituting the shoulder portion 200 are curved inward in the radial direction, the buckling strength is further increased. This tendency was the same for both normal bottles and lightweight bottles.

In particular, in the lightweight bottle, in Example 1 having substantially the same shape as Comparative Example 1, the buckling strength is increased to the extent that it approaches the normal bottle of Comparative Example 1 in which the mass of the material is as large as 3.5 g. rice field. Further, in Example 2, the buckling strength was increased to the extent that the mass of the material was 3.5 g larger than that of the normal bottle of Comparative Example 1.

From the results of the above examples, it was shown that the buckling strength is sufficiently enhanced in the filler with the PET bottle 1 and the PET bottle 2 according to the present embodiment. Therefore, in the present embodiment, it has been shown that the PET bottle 1 and the PET bottle 2 which are particularly excellent in buckling strength can be provided while the internal volume is secured within the predetermined dimensions.

The present disclosure can be suitably used for various plastic containers filled with a liquid as a content. However, the present disclosure is not limited to the embodiments and examples described above. The plastic containers of the present disclosure include, for example, various non-carbonated beverages such as water, green tea, oolong tea, black tea, coffee, fruit juice, and soft drinks, carbonated beverages, seasonings such as soy sauce, sauce, and mirin, cooking oil, sake, and shochu. It is useful for storing foods containing alcoholic beverages such as detergents, cosmetics, pharmaceuticals, and all other contents. In particular, the plastic container of the present disclosure is suitable for sale in a narrow storage space or for use in a vending machine because the internal volume is secured within the predetermined dimensions and the buckling strength is particularly excellent. .. Further, the plastic container of the present disclosure is also suitable for a plastic container that requires weight reduction because it is excellent in strength, particularly buckling strength, even if it is reduced in weight.

1, 2 PET bottles (plastic containers)
10 Mouth 20, 220 Shoulder 21 Curved (vertical cross-sectional shape)
22 Tangents at the ends of the shoulders 23, 223 Ridges 24, 224 Trapezoidal panels (panels)
30, 230 Body 31, 231 Connection 40 Bottom 233 Ridge 234 Rectangle panel D Maximum body diameter r Curve radius of curvature θ Shoulder opening angle

Claims (4)

In a plastic container having a mouth, shoulders, torso, and bottom sequentially in the axial direction.
The body portion has a connecting portion of a body portion connected to the shoulder portion.
The shoulder has a plurality of ridges extending radially in a plan view.
The ridge extends continuously to the connection and extends.
The shoulder has a trapezoidal panel between the ridges.
The connection has a rectangular panel between the ridges.
The ridgeline protrudes outward and
The trapezoidal panel and the rectangular panel are curved inward in the radial direction in a cross section perpendicular to the axial direction.
The shoulder has a single radius of curvature whose vertical cross-sectional shape of the ridge is radially outwardly convex.
A plastic container characterized in that an opening angle formed by a tangent at the end of the shoulder on the side of the mouth is 100 ° or more and 157 ° or less at the opposite end. The trapezoidal panel and the rectangular panel have different axially extending ridges at the center of the circumferential direction.
The plastic container according to claim 1, wherein the other ridgeline is located inside the ridgeline in the radial direction. The plastic container according to claim 1 or 2, wherein the radius of curvature is 0.35 times or more and 1.18 times or less the maximum body diameter. The plastic container according to any one of claims 1 to 3, wherein the number of trapezoidal panels is 18 or more and 30 or less.

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