JP2017001705A - Synthetic resin container - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a synthetic resin container excellent in both of decompression absorption performance and self-standing performance when performing hot filling.SOLUTION: In a synthetic resin container having decompression absorption performance in a bottom,: a leg part consisting of an outer peripheral wall continuing from a trunk, a grounding part and an inner peripheral wall is formed; a movable bottom positioning upward from the grounding part in an inside from the inner peripheral wall of the leg part; an annular part is disposed between the movable bottom and the inner peripheral wall; and a plurality of swelling parts and a plurality of recesses are alternately formed in a circumferential direction in the annular part.SELECTED DRAWING: Figure 2-1

Description

  The present invention relates to a synthetic resin container, and more particularly, to a synthetic resin container excellent in both reduced-pressure absorption performance and self-supporting property during hot filling.

  Synthetic resin containers are widely used as packaging containers for various liquids. In particular, a stretch-molded container formed by stretch-blow-molding polyethylene terephthalate (PET) has a combination of transparency, gas barrier properties, light weight, impact resistance, appropriate rigidity, etc., and is used for containing liquid contents. Widely used as a packaging container.

  In a synthetic resin container such as polyester, it is widely performed to hot-fill the contents in order to enhance the storage stability of the contents. However, in this case, the synthetic resin container is inevitably deformed under reduced pressure due to the volumetric shrinkage of the contents due to cooling. In order to prevent this, Patent Document 1 discloses that the bottom wall portion of the bottom portion is connected to the grounding portion from the radial inner side and extends upward, and the upper end portion of the rising peripheral wall portion is directed radially inward. The bottle is provided with a movable wall portion that protrudes and a depressed peripheral wall portion that gradually decreases in diameter from the radially inner end of the movable wall portion.

  In Patent Document 2, the bottom wall portion of the bottom portion is connected to the grounding portion from the inside in the bottle radial direction and extends upward, and the annular shape protrudes from the upper end portion of the rising peripheral wall portion toward the inside in the bottle radial direction. A bottle having a movable wall portion and a depressed peripheral wall portion extending upward from an inner end portion of the movable wall portion in the bottle radial direction is disclosed.

  However, in the bottles of Patent Documents 1 and 2, there is room for improvement in reduced-pressure absorption performance and self-supporting property during hot filling.

JP 2012-232772 A JP 2012-246014 A

  An object of the present invention is to provide a synthetic resin container which exhibits excellent reduced-pressure absorption performance during hot filling and has stable self-supporting properties.

  According to the present invention, the bottom part is a synthetic resin container having a reduced pressure absorption performance, and the bottom part is formed with an outer peripheral wall continuous from the trunk part, a leg part including an earthing part and an inner peripheral wall. A movable bottom portion located above the grounding portion is formed inside the inner peripheral wall, and an annular portion is provided between the movable bottom portion and the inner peripheral wall of the leg portion. A synthetic resin container is provided in which a plurality of bulging portions and a plurality of concave portions are alternately formed in the circumferential direction.

In the synthetic resin container of the present invention,
1. The outer peripheral width of the bulging portion at the outer edge of the annular portion is 5 to 50 mm,
2. The ratio of the inner diameter of the annular part to the outer diameter of the annular part is 0.9 to 0.6,
3. The ratio of the outer peripheral width of the bulging part to the radial length of the bulging part is 0.5 to 12,
4). The outer edge and / or inner edge of the annular portion is formed by a plurality of straight lines and / or curves;
5). A folded portion is formed on the outer peripheral edge of the annular portion;
6). The outer edge of the movable bottom is formed by a plurality of straight lines and / or curves;
7). The outer edge of the annular part, the inner edge of the annular part and the outer edge of the movable bottom part are formed by a plurality of straight lines, and the inner edge of the annular part and the outer edge of the movable bottom part coincide with each other;
8). An annular groove is formed on the outer peripheral edge of the movable bottom;
9. A central portion is formed on the inner side of the inner edge of the movable bottom portion, between the outer edge of the movable bottom portion and the inner edge in contact with the central portion, protruding downward in the radial direction, a plurality of curved portions formed in the circumferential direction, And a groove portion that connects the inner edge of the movable bottom portion so as to be located above the outer edge in the container axial direction between the curved portions,
10. The groove portion of the movable bottom portion is formed radially,
11 The depth of the groove of the movable bottom is 0.1 to 3.0 mm at the center position between the inner and outer edges of the movable bottom;
12 The groove portion of the movable bottom portion has a curved bottom portion protruding downward, and the inclination angle of the curved bottom portion with respect to the horizontal direction is 2 to 15 ° at the center position between the inner and outer edges of the movable bottom portion;
13. The center line of the recess of the annular part is located on a virtual straight line extending the center line of the groove part of the movable bottom part;
14 The central portion protrudes outward or inward of the container;
Is preferred.

  According to the synthetic resin container of the present invention, the bottom part is provided with the movable bottom part and the leg part, and further, the annular part is provided between the movable bottom part and the inner peripheral wall of the leg part. Therefore, when the contents are heated or self-weighted when the contents are hot filled, the gap between the movable bottom part and the annular part (the outer edge of the movable bottom part or the apex of the annular groove part) serves as a fulcrum, and only the movable bottom part moves downward. Moving. After that, when the contents are cooled and volume shrinkage of the contents occurs, first, the stress that the movable bottom part returns to the original shape works, and only the movable bottom part moves upward with a fulcrum between the movable bottom part and the annular part. However, when the volume shrinkage further proceeds, the fulcrum changes between the leg portion and the annular portion (the outer edge of the annular portion or the apex of the folded portion), and the annular portion moves upward together with the movable bottom portion. Therefore, in the present invention, the downward movement of the movable bottom during hot filling is suppressed, while the movable bottom can be moved greatly upward during cooling, and the hot The vacuum absorption performance during filling can be maximized.

It is a side view which shows an example of the synthetic resin containers of this invention. (A) is a schematic bottom view explaining the bottom part of the synthetic resin container of FIG. FIG. 2B is a schematic aa sectional view of FIG. (C) is a bb sectional view of Drawing 2-1 (A). (D) is the elements on larger scale of the annular part shown by Drawing 2-2 (B). (E) is a DD arrow enlarged schematic view in Drawing 2-1 (A). It is a figure which shows the other example of the synthetic resin containers of this invention. (A) is a schematic bottom view. (B) is a schematic aa sectional view of (A). (C) is an approximate bb sectional view of (A). It is a schematic bottom view which shows the other example of the synthetic resin containers of this invention. It is a schematic bottom view which shows the other example of the synthetic resin containers of this invention. (A) is a schematic bottom view. (B) is a schematic aa sectional view of (A). It is a partial cross section figure for demonstrating the behavior of the bottom part of the synthetic resin containers shown in FIG. (A) is an empty state, (B) is a state immediately after hot filling, (C) is a vacuum absorption first stage after hot filling, (D) is a vacuum absorption second stage after hot filling, (E) Indicates a superposition of (A) to (D).

The synthetic resin container of the present invention will be described based on specific examples shown in the accompanying drawings. In the present specification, “upper” and “upper” mean the mouth side in the container axial direction, and “lower” and “lower” mean the bottom side in the container axial direction.
A synthetic resin container 1 of the present invention shown in FIG. 1 includes a mouth portion 2, a shoulder portion 3, a trunk portion 4 and a bottom portion 5. The body part 4 includes an upper body part 4a continuous from the shoulder part 3, a lower body part 4b continued from the bottom part, and a central body part 4c located between the upper body part 4a and the lower body part 4b.
Three circumferential ribs 6, 6, and 6 are formed in the central body portion 4 c in parallel and at equal intervals, and the mechanical strength of the body portion and the shape retaining property against internal pressure deformation are ensured. Moreover, the outer peripheral surface except the rib 6 part is formed straight in the axial direction, and a label (not shown) can be wound around the body part.
In the specific example shown in FIG. 1, ribs 7 are also formed between the lower body 4b and the bottom 5, and the body 4 and the bottom 5 are clearly defined, but the body and the bottom are not necessarily clearly defined. It does not have to be.

  Roughly speaking, the bottom portion 5 includes an annular leg portion 10, a movable bottom portion 20 located inside the leg portion 10, an annular portion 30 provided between the leg portion 10 and the movable bottom portion 20, and a central portion 40. Consists of. The leg portion 10 includes an outer peripheral wall 11 that is located below the rib 7 and continues from the trunk portion 4, a grounding portion 12, and an inner peripheral wall 13 that forms a rising upward from the grounding portion 12. The inner edge of the inner peripheral wall 13 and the outer edge of the annular portion 30 are connected continuously or via a folded portion 50 described later. The movable bottom portion 20 is located above the grounding portion 12, and the outer edge of the movable bottom portion 20 is connected to the inner edge of the annular portion 30 continuously or via an annular groove portion 60 described later.

<Annular part>
FIG. 2 is a view for explaining the bottom of the example of the synthetic resin container of the present invention shown in FIG. FIG. 2A is a schematic bottom view. FIGS. 2-2 (B) and (C) are respectively a schematic aa sectional view and a schematic bb sectional view of (A).
Referring to FIG. 2-1 (A), the synthetic resin container 1 of the present invention has a movable bottom portion 20, and further has an annular portion 30 between the movable bottom portion 20 and the inner peripheral wall 13 of the leg portion 10. It has an important feature. With such a feature, the movable bottom portion can be moved upward in multiple stages during cooling, and very excellent reduced pressure absorption performance can be obtained while maintaining independence.

  As shown in FIGS. 2-2 (B) and (C), the annular portion 30 is inclined downward toward the center of the bottom as a whole, that is, the inner edge 30b of the annular portion 30 is more than the outer edge 30a. Is also located below. The outer edge 30a or the inner edge 30b is formed by a plurality of straight lines and / or curved lines, that is, the annular portion 30 has a polygonal annular shape in addition to the annular shape as shown in FIG. A ring formed from a curve that is concave in the radial direction (hereinafter may be referred to as a concave curve), a ring formed from a curve that is convex in the radial direction (hereinafter may be referred to as a convex curve), An appropriate shape such as an annular shape formed by combining the concave curve and the convex curve or an annular shape formed by combining a straight line and the concave curve and / or the convex curve can be used.

  Furthermore, the annular portion 30 is preferably formed with the following dimensions from the viewpoint of more effectively performing multi-stage vacuum absorption during cooling.

Referring to FIG. 2-3 (D), which is a partially enlarged view of the annular portion 30 shown in FIG. 2-2 (B), the annular portion outer edge 30a (in the case of the embodiment shown in FIG. The starting point of the annular part on the upper edge (which coincides with the inner edge of the movable bottom part 20) is indicated by L, and the annular part on the inner edge 30b (in the embodiment shown in the figure, coincides with the outer edge of the movable bottom part 20). The end point of is represented by M. The projections of the start point L and the end point M onto the ground contact surface G in the vertical direction are represented by L ′ and M ′, respectively.
The height (outer edge height) from the ground contact surface G in the annular portion outer edge 30a is defined by a line segment LL ′ and is preferably in the range of 6 to 12 mm. Further, the height (inner edge height) from the ground contact surface G at the inner edge 30b of the annular portion is defined by a line segment MM ′, and is preferably in the range of 4 to 10 mm. Further, as described above, since the inner edge 30b of the annular portion 30 is positioned below the outer edge 30a, the value of the line segment LL ′ of the outer edge height is larger than the value of the line segment MM ′ of the inner edge height. It is set to become.

Referring to FIGS. 2-1 (A) and 2-3 (D), points L ′ and M ′ that are symmetrical with respect to the central axis (not shown) of the container 1 are L ″ and M ″, respectively. It is represented.
The outer diameter of the annular portion 30 is represented by a line segment L′ L ″, and the inner diameter of the annular portion 30 is defined by a line segment M′M ″. The annular portion 30 is formed to have a thickness (radial width) such that the ratio of the inner diameter M′M ″ of the annular portion to the outer diameter L′ L ″ of the annular portion is 0.9 to 0.6. It is preferable. If the annular portion is too thick, the movable bottom portion becomes small, and the reduced pressure absorption capability may be impaired. If the annular portion is too thin, the reduced pressure absorption amount does not change so much between the first stage and the second stage of vacuum absorption, and the effects of the present invention may not be exhibited sufficiently.

  With continued reference to FIGS. 2-1 (A) and 2-3 (D), in the present invention, the annular portion 30 has a plurality of bulged portions 31 protruding in a curved shape downward in the radial direction. Are formed at equal intervals, and between the adjacent bulging portions 31, 31, there is provided a recess 32 recessed inward of the container. By having the bulging part 31 and the recessed part 32, the bulging part 31 becomes easy to bend in the circumferential direction, and generation | occurrence | production of the wrinkle when the stress of the circumferential direction acts with respect to the cyclic | annular part 30 is suppressed. The bulging part 31 and the recessed part 32 are preferably set to the following shapes from the viewpoint of more reliably preventing the occurrence of wrinkles and cracks during reversible deformation and the formability.

  As shown in FIG. 2D, it is preferable that both the radial line passing through the portion of the bulging portion 31 that protrudes most outward of the container and the radial line of the concave portion 32 are substantially arc-shaped. Specifically, the curvature radius R1 of the bottom of the bulging portion 31 is preferably 3 to 20 mm, and the curvature radius R2 of the bottom of the recess 32 is preferably 6 to 50 mm. Thereby, it becomes easy to produce bending deformation between the bulging part 31 and the recessed part 32 which adjoin each other, and the deformation | transformation which bends in the middle of the recessed part 32 is suppressed.

  In addition, referring to FIG. 2A, the outer peripheral width b of the bulging portion 31 is preferably 5 to 50 mm in terms of the outer edge distance of the bulging portion 31. If the outer peripheral width b is too wide, the number of the concave portions 32 is inevitably reduced, and the amount of soot absorbed is insufficient, so that there is a risk that wrinkles are likely to occur when a load is applied in the circumferential direction. On the other hand, if the outer peripheral width b is too narrow, the mechanical strength of the bulging portion 31 is increased, and the movable amount of the annular portion 30 may be reduced.

  Further, in the present invention, the outer peripheral width b of the bulging portion 31 and the radial length L′ M ′ of the bulging portion 31 are set to close values, and the bottom surface of the bulging portion 31 is formed in a shape close to a square. It is preferable to do. The load acting on the bulging portion 31 is effectively distributed in the radial direction and the circumferential direction, and the occurrence of irreversible deformation of each bulging portion 31 is suppressed, thereby promoting reversible deformation of the entire annular portion 30. Because. Specifically, the ratio of the outer peripheral width b of the bulging portion 31 to the radial length L′ M ′ is preferably 0.5 to 12.

  As shown in FIG. 2E (E), which is an enlarged view taken along the line DD in FIG. 2A, the concave portion 32 is a side surface of each of the two adjacent bulging portions 31, 31. It has a groove bottom 321 formed between curved surfaces 311 and 311 and extending in the radial direction. Both side surfaces 311 and 311 form an angle α, and the angle α is preferably 80 to 100 °. The width d of the groove bottom 321 of the recess is preferably 0.5 to 2.0 mm.

  Furthermore, another aspect of the annular portion 30 will be described with reference to FIG. 3A is a schematic bottom view, FIG. 3B is a schematic aa cross-sectional view of FIG. 3A, and FIG. 3C is a schematic bb cross-sectional view of FIG. In the present embodiment, the folded portion 50 is formed at the outer peripheral edge portion of the annular portion 30 (specifically, between the outer edge 30a of the annular portion and the inner peripheral wall 13 of the leg portion). It is different from the synthetic resin container 1 of the present invention shown. The folded portion 50 is folded so as to be recessed inward of the container, and the inner edge of the folded portion 50 coincides with the outer edge 30 a of the annular portion 30.

  Although the depth of the folding | returning part 50 is not limited to this, it exists in the range of 0.5-3.0 mm in the perpendicular | vertical distance from the upper end of the folding | returning part 50 to the inner edge (namely, outer edge 30a of a cyclic | annular part) of the folding | returning part 50. Is preferred. The radial width w of the folded portion 50 is normally set to 1.0 to 3.0 mm in the widest portion in the container axis direction.

  By providing the folded portion 50 having an appropriate depth and width in this manner, the inner peripheral wall 13 of the leg portion 10 is located at the center of the bottom portion 5 when the weight and heat of the contents act on the bottom portion due to hot filling or the like. Pulling in the direction excessively (inward falling) is prevented, and the inner edge of the folded portion 50 is not excessively pulled. As a result, even when subjected to hot filling or the like, the movable bottom 20 does not protrude excessively or does not cause non-uniform deformation, so it deforms even during decompression, for example at a high temperature of 87 ° C. It can also be used for hot filling. If the folded portion 50 is too shallow or the folded portion 50 is too wide, there is a possibility that the inner peripheral wall 13 of the leg portion 10 may fall inward when the movable bottom portion 20 moves downward. On the other hand, if the folded portion 50 is too deep or too narrow, the moldability may be poor.

Still another embodiment of the annular portion 30 will be described with reference to FIG. In the present embodiment, both the outer edge 30a and the inner edge 30b of the annular portion 30 are formed by a plurality of straight lines, and the shape of the annular portion 30 is a polygon (specifically, a hexagonal shape). It differs from the synthetic resin container 1 of the present invention shown in FIG. As already described, the outer edge 30a and the inner edge 30b of the annular portion 30 may be formed by a plurality of straight lines and / or curves. However, the annular portion 30 is a starting point when the annular portion 30 is deformed in the circumferential direction during decompression. Therefore, it is preferable to make the annular portion 30 into a polygonal annular shape. Further, the intersection of the plurality of straight lines and / or curved lines preferably overlaps with the groove bottom 321 of the recess 32. Further, in this case, the polygon is preferably an 8-24 square from the viewpoint of moldability.
When the annular portion 30 is a polygonal annular shape, the outer diameter L′ L ″ of the annular portion is defined by the diameter of the circumscribed circle of the polygon that constitutes the annular portion outer edge 30a. Similarly, the inner diameter M′M ″ of the annular portion is defined by the diameter of a polygon circumscribed circle constituting the annular portion inner edge 30b.

<Movable bottom>
Next, the movable bottom 20 in the synthetic resin container 1 of the present invention will be described. Referring again to FIG. 1 and FIGS. 2-2 (B) and (C), the movable bottom portion 20 as a whole is inclined upward toward the center of the bottom portion 5, that is, the inner edge of the movable bottom portion 20 is more than the outer edge. Is also located above. A substantially flat central portion 40 defined by an annular protrusion 41 projecting downward is formed on the inner side of the movable bottom portion 20. The central portion 40 is located at the center of the bottom portion 5 and is located at the uppermost position in the container axial direction in the region radially inward from the ground contact portion 12. Although the annular protrusion 41 does not necessarily have to be formed, it is formed at the boundary between the movable bottom portion 20 and the central portion 40 as in the present embodiment, thereby generating a radial direction that occurs in accordance with the movement of the movable bottom portion 20. Can be absorbed.

  The outer diameter of the movable bottom portion 20 is preferably 50 to 70% of the outer diameter of the grounding portion 12 of the leg portion, from the viewpoint that the effects of the present invention can be exhibited to the maximum. If the outer diameter of the movable bottom portion 20 is too large, the radial width of the annular portion 30 becomes narrow, and there is a possibility that a desired effect cannot be exhibited. Further, the outer diameter of the central portion 40 is preferably 25 to 40% of the outer diameter of the movable bottom portion 20.

  The movable bottom portion 20 has a curved portion protruding in a curved shape downward in the radial direction between the inner edge (outer edge of the annular projection 41 when the annular projection 41 is formed) from the outer edge of the movable bottom portion 20 to the central portion 40. 21 are formed at equal intervals in the circumferential direction, and extend from the inner edge (outer edge of the annular protrusion 41) in contact with the central portion 40 between the adjacent curved portions 21 and 21 toward the outer edge of the movable bottom portion 20. A plurality of groove portions 22 are formed at equal intervals.

  As shown in FIG. 2-1 (A), the curved portion 21 and the groove portion 22 are formed in a uniform shape and radially at equal intervals from the viewpoint of ensuring uniform deformation during filling of the contents or during decompression. Has been. In particular, it is preferable to determine the arrangement of the groove portions 22 so that the center line of the recess portion 32 provided in the annular portion 30 is positioned in a virtual straight line extending the center line of the groove portion 22, and is the same as the number of the recess portions 32. It is most preferable to determine the arrangement of the groove portions 22 so that only the groove portions 22 are provided and the center line of the concave portion 32 is positioned in a virtual straight line extending the center line of the groove portions 22. Thereby, in the synthetic resin container of the present invention, the behavior of the movable bottom portion 20 and the annular portion 30 becomes smooth in both the circumferential direction and the radial direction in the multi-stage vacuum absorption during cooling, and locally. There is no risk of excessive load. Furthermore, there is an advantage that the design of the container is improved.

  Referring to FIGS. 2-1 (A) and FIGS. 2-2 (B) and (C), the groove portion 22 has a curved bottom portion 22a protruding downward, and from the outer edge of the movable bottom portion 20 toward the central portion 40. It is formed so that the position of the inner edge (outer edge of the annular projection 41) that is inclined upward and is in contact with the central portion 40 rather than the outer edge of the movable bottom portion 20 is located above the container axis direction.

The groove portion 22 absorbs the bending that occurs in the bottom radial direction when heat is further applied due to the weight of the contents, hot filling, or the like, and smoothly restores the original shape (upwardly inclined state) during decompression. It is preferable to set the depth of the groove and the inclination angle of the curved bottom portion 22a so that the shape restoring action can be exhibited.
Referring to FIGS. 2-2 (B) and (C), the depth D of the groove 22 is the difference between the distance D2 between the line segment X2 and the point m2, and the distance D1 between the line segment X1 and the point m1. It is represented by D2-D1. Then, as shown in FIG. 2-2 (B), the innermost and outer edges of the movable bottom portion 20 (in the specific example shown in the figure, the position of the inner edge is deepest in the vicinity of the center position m2). The depth D is preferably in the range of 0.1 to 3.0 mm. Moreover, the depth D can also be adjusted suitably in the radial direction of the groove part 22.
Specifically, the center position m2 is obtained by drawing a line segment X2 connecting the inner and outer edges of the movable bottom 20 in the curved portion 21 and passing through the midpoint of the line segment X2, as shown in FIG. 2-2 (B). It means the point where the straight line Y2 perpendicular to the line segment X2 and the curved portion 21 intersect. The line segment X1 is a line segment that connects the inner and outer edges of the movable bottom portion 20 in the groove 22, as shown in FIG. 2-2 (C), and m1 passes through the midpoint of the line segment X1 with respect to the line segment X1. This is the point where the vertical straight line Y1 and the curved bottom 22a of the groove 22 intersect.
In addition, the inclination angle θ of the curved bottom portion 22a of the groove portion with respect to the horizontal direction is preferably in the range of 2 to 15 ° at the center position m1. Specifically, as shown in FIG. 2C, the inclination angle θ is obtained by drawing the tangent line Z of the curved bottom 22a of the groove at the center position m1 and expressing the tangent line Z with respect to the horizontal direction. Is done.

  It is preferable that the circle connecting the tops (lowermost points) of the curved parts 21, 21... Has a diameter of 60 to 90% of the outer diameter of the movable bottom part 20.

  Further, the outer edge of the movable bottom portion 20 may be formed by a plurality of straight lines and / or curved lines. Specifically, it is formed from an annular shape, a polygonal annular shape, or a curve that is concave in the radial direction (hereinafter, this may be referred to as a concave curve) depending on the shape and width of the curved portion 21 and the groove portion 22. A ring formed from a curve that is convex in the radial direction (hereinafter, this may be referred to as a convex curve), a ring formed by combining the concave curve and the convex curve, or a straight line and the The shape can be appropriately changed to an annular shape formed by combining the concave curve and / or the convex curve. From the viewpoint of effectively preventing the occurrence of wrinkles in the circumferential direction, the outer edge of the movable bottom portion 20 is preferably formed by a plurality of straight lines, as shown in FIG. The outer edge is preferably a polygonal ring. Further, the intersection of the plurality of straight lines and / or curves preferably overlaps with the groove bottom 22 a of the groove portion 22.

  Furthermore, another aspect of the movable bottom portion 20 will be described with reference to FIG. 5A is a schematic bottom view, and FIG. 5B is a schematic aa cross-sectional view of FIG. In the present embodiment, an annular groove portion 60 that protrudes upward is formed on the outer peripheral edge portion of the movable bottom portion 20 (that is, between the outer edge of the movable bottom portion 20 and the inner edge 30b of the annular portion). The inner edge of the annular groove portion 60 coincides with the position of the outer edge of the movable bottom portion 20. From the viewpoint of imparting mechanical strength to the movable bottom portion 20 and the annular portion 30, it is preferable that the vertical distance from the upper end of the annular groove portion 60 to the outer edge of the annular groove portion 60 is in the range of 0.5 to 3.0 mm. Moreover, it is suitable that the width | variety of the annular groove part 60 is 1.0-3.0 mm.

  In the embodiment of the present invention, the shape of the central portion 40 is not limited to the specific example described above, and various changes can be made. For example, in the specific example shown in the figure, the central portion 40 is formed substantially flat, but may protrude outward or inward of the container, thereby making the central portion 40 thinner. Becomes possible, and a larger vacuum absorption performance can be exhibited.

  The thickness of the movable portion, mainly the movable bottom portion 20 and the annular portion 30, during absorption of reduced pressure between the inner peripheral wall 13 of the leg portion of the bottom portion 5 and the outer edge of the central portion 40 is equal to or less than the thickness of the thinnest portion of the trunk portion 4. It is preferable that the thickness is 0.15 to 0.4 mm, particularly 0.2 to 0.3 mm, although it depends on the diameters of the movable bottom portion 20 and the annular portion 30.

6A and 6B for explaining the fluctuation of the movable bottom 20 and the annular portion 30 in accordance with the change in the internal pressure of the synthetic resin container 1 of the present invention, FIG. 6A is an empty state, and FIG. (C) is a partial cross-sectional view showing the first stage of the decompressed state after filling in (B), (D) is a partial sectional view showing the second stage of the decompressed state, and (E) is (A)-( FIG.
In the synthetic resin container 1 of the present invention, immediately after the contents are filled (B) regardless of the filling temperature, the movable bottom 20 moves downward from the empty state (A) due to the weight of the contents. However, when the annular portion 30 is formed as described above, the portion between the movable bottom portion 20 and the annular portion 30 serves as a fulcrum α for the downward movement, and thus when filled and sealed at a high temperature of 87 ° C. However, the movable bottom does not move downward too much. After the hot filling, when the contents are cooled and the inside of the container is in a reduced pressure state, only the movable bottom 20 is smoothly moved upward around the fulcrum α as shown in (C) at first. Then, as shown in (D), a portion between the annular portion 30 and the leg portion 10 is set as a new fulcrum β, and upward movement occurs around the fulcrum β, and only the movable bottom portion 20 is used. The annular portion 30 also moves upward. Therefore, finally, the movable bottom 20 is positioned above the empty state (A).
The position of the fulcrum α will be described in more detail. In the embodiment in which the annular groove 60 is provided on the outer peripheral edge of the movable bottom portion 20, the fulcrum α is located at the apex of the annular groove 60, as shown in FIG. In an aspect in which the annular groove portion 60 is not provided, the fulcrum α is located at the outer edge of the movable bottom portion. Similarly, with respect to the position of the fulcrum β, the fulcrum β is located at the apex of the folded portion 50 in the embodiment in which the folded portion 50 is provided at the outer peripheral edge of the annular portion 30, but in the embodiment in which the fulcrum β is not provided, Located at 30a.
As is apparent from FIG. 6 (E) formed by superimposing these figures, in the synthetic resin container of the present invention, even when the contents are filled at a high temperature and the weight and heat of the contents act, 20 does not move excessively downward, and when it is in a depressurized state after that, it gradually deforms and rises to the inside of the container to exhibit the desired depressurization absorption performance. Can do.

<Manufacturing method>
The synthetic resin container 1 of the present invention can be formed by a conventionally known manufacturing method as long as it has the bottom shape provided with the movable bottom 20 and the leg 10 described above. Since it is important that the movable bottom portion 20 is thin in order to enable vertical movement, it is preferable to form the movable bottom portion 20 by a stretch blow molding method capable of forming the thin portion.

  In stretch blow molding, a preform made of a thermoplastic polyester resin such as polyethylene terephthalate is molded using a bottom mold that can shape the bottom shape described above to the bottom of the container. At this time, an uneven shape composed of the bulging portions 31, 31..., The concave portions 32, 32..., The curved portions 21, 21. Therefore, it is preferable that the bottom mold has a rough surface in order to improve the releasability of the bottom mold. Accordingly, even in the molded synthetic resin container, the surfaces of the movable bottom portion 20 and the annular portion 30 and the surfaces of the leg portions 10 that come into contact with the bottom mold are formed to be rough.

  For the synthetic resin container 1 of the present invention, thermoplastic polyester resins conventionally used for stretch blow molding, particularly ethylene terephthalate thermoplastic polyesters are advantageously used. Of course, polybutylene terephthalate, polyethylene naphthalate, etc. Other polyesters or blends with polycarbonate or arylate resin can also be used. In addition to a single layer of the thermoplastic polyester resin, it may have a multilayer structure of the thermoplastic polyester resin and a gas barrier resin or an oxygen-absorbing resin, and has heat resistance that can withstand hot filling at high temperatures. In order to give, it is preferable that the mouth part of the preform to be used is thermally crystallized.

  Furthermore, the stretch blow molding conditions can be molded under conventionally known molding conditions as long as a bottom mold capable of imparting the above-described shape to the bottom portion can be used. In addition to single-stage blow molding, molding is also performed by two-stage blow molding. It is preferable that it is heat-set from the viewpoint of heat resistance.

  In the synthetic resin container of the present invention, the vacuum absorption performance and the self-supporting property are imparted to the bottom that does not affect the container appearance. Therefore, the synthetic resin container of the present invention can be effectively used as a container for liquid contents filled by hot filling, and can also be applied to contents filled at a relatively high temperature. It is.

DESCRIPTION OF SYMBOLS 1 Synthetic resin container, 5 bottom part, 10 leg part, 13 inner peripheral wall, 20 movable bottom part, 21 curved part, 22 groove part, 30 annular part, 31 bulge part, 32 recessed part, 40 center part, 50 folded part, 60 annular Groove

Claims (15)

The bottom is a synthetic resin container having reduced pressure absorption performance,
The bottom part is formed with an outer peripheral wall continuous from the body part, a leg part made up of a grounding part and an inner peripheral wall, and a movable bottom part located above the grounding part is formed inside the inner peripheral wall of the leg part. Has been
An annular part is provided between the movable bottom part and the inner peripheral wall of the leg part,
A synthetic resin container, wherein a plurality of bulging portions and a plurality of concave portions are alternately formed in the circumferential direction in the annular portion.   The synthetic resin container according to claim 1, wherein an outer peripheral width of the bulging portion at an outer edge of the annular portion is 5 to 50 mm.   The synthetic resin container according to claim 1 or 2, wherein a ratio of an inner diameter of the annular portion to an outer diameter of the annular portion is 0.9 to 0.6.   The synthetic resin container according to any one of claims 1 to 3, wherein a ratio of an outer peripheral width of the bulging portion to a radial length of the bulging portion is 0.5 to 12.   The synthetic resin container according to any one of claims 1 to 4, wherein an outer edge and / or an inner edge of the annular portion is formed by a plurality of straight lines and / or curves.   The synthetic resin container according to any one of claims 1 to 5, wherein a folded portion is formed at an outer peripheral edge of the annular portion.   The synthetic resin container according to any one of claims 1 to 6, wherein an outer edge of the movable bottom portion is formed by a plurality of straight lines and / or curves.   The outer edge of the annular part, the inner edge of the annular part, and the outer edge of the movable bottom part are formed by a plurality of straight lines, and the inner edge of the annular part and the outer edge of the movable bottom part coincide with each other. A synthetic resin container according to any one of the above.   The synthetic resin container according to any one of claims 1 to 8, wherein an annular groove is formed in an outer peripheral edge of the movable bottom.   A central portion is formed on the inner side of the inner edge of the movable bottom portion, between the outer edge of the movable bottom portion and the inner edge in contact with the central portion, protruding downward in the radial direction, a plurality of curved portions formed in the circumferential direction, The synthetic resin container according to any one of claims 1 to 9, further comprising a groove portion that connects the inner edge of the movable bottom portion so as to be positioned above the outer edge in the container axial direction between the curved portions.   The synthetic resin container according to claim 10, wherein the groove portion of the movable bottom portion is formed radially.   The synthetic resin container according to claim 10 or 11, wherein a depth of the groove portion of the movable bottom portion is 0.1 to 3.0 mm at a center position between inner and outer edges of the movable bottom portion. The groove portion of the movable bottom portion has a curved bottom portion protruding downward;
The synthetic resin container according to any one of claims 10 to 12, wherein an inclination angle of the curved bottom portion with respect to a horizontal direction is 2 to 15 ° at a center position between inner and outer edges of the movable bottom portion.   The synthetic resin container according to any one of claims 10 to 13, wherein a center line of the concave portion of the annular portion is located on an imaginary straight line extending from a center line of the groove portion of the movable bottom portion.   The synthetic resin container according to any one of claims 10 to 14, wherein the central portion protrudes outward or inward of the container.