JP2016199294A - Synthetic resin container - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a synthetic resin container which excels both in fall resistance performance and decompression absorption performance.SOLUTION: In a synthetic resin container, a bottom part has decompression absorption performance. At the bottom part, an outer peripheral wall 11 continuing from a trunk part, and a leg part 10 comprising a grounding part 12 and an inner peripheral wall 13 are formed. On further inside than the inner peripheral wall of the leg part, a movable bottom part 20 positioned further upward than the grounding part is formed. At the grounding part, a plurality of heel parts 14 and a plurality of leg groove parts 15 are provided alternately in the circumferential direction.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 drop resistance performance and reduced pressure absorption performance.

  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.

  A container made of synthetic resin such as polyester is widely filled with the contents at a high temperature 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 a reversal inclined part that is formed in a region surrounded by a leg part and inclines in a concavo-convex manner in a symmetrical shape toward the inside of the body part or the outside of the body part, A bottom central portion surrounded by the inversion inclined portion, and the leg portion includes a plurality of concave portions formed at predetermined intervals in the circumferential direction, and a plurality of downward projecting portions formed between the concave portions. Has proposed a synthetic resin bottle characterized in that the lower end surface of the base plate is a ground contact surface. According to the bottle of Patent Document 1, the bottle is filled with contents in a state in which the inverted inclined portion protrudes outward and downward from the body portion, and the inverted inclined portion is sealed after fitting a cap or the like in the mouth portion. By simply pushing up the inside of the barrel and reversing the recess, the capacity inside the bottle can be reduced and the reduced pressure inside the bottle can be easily eliminated. Further, Patent Document 2 has a synthetic resin which has an inner part composed of a depressed wall part and a flat wall part at the bottom, and can exhibit a reduced pressure absorption action when the inner part is depressed and displaced in the body part. A casing is disclosed.

By the way, in the bottle or the case that gives the bottom part the decompression absorption performance as described above, it is necessary to secure a sufficient area of the bottom part (bottom center part) to be inverted and deformed. I have to make it smaller. For this reason, if an impact is applied to the leg when the container is dropped, the grounding part may be wrinkled or crushed, which may reduce the grounding performance of the leg or cause a poor appearance.
Here, Patent Document 1 is to improve the buckling strength by forming a recess in the leg part, and Patent Document 2 is provided with a transverse groove in a part from the leg wall part to the heel wall part, It describes that the amount of absorption under reduced pressure is further improved and the force is dispersed during reverse deformation. However, it was necessary to improve the effect of suppressing wrinkles and crushing in the legs when dropped.

  Incidentally, the applicants first have a bottom portion having a bottom center portion, an annular peripheral portion and a side portion, and a heel portion and a groove portion are alternately formed in the peripheral portion on the peripheral portion, and the heel portion Has proposed a synthetic resin container having an outer peripheral width of 6 to 9 mm (see Patent Document 3). In the case of the synthetic resin container of Patent Document 3, buckling deformation due to the vertical load was effectively suppressed even when a vertical load was applied after the contents were filled and sealed. The drop performance has not been studied, and there was room for improvement in these performances.

JP 2008-044333 A Japanese Patent No. 4725899 JP 2014-55025 A

  Accordingly, an object of the present invention is to provide a synthetic resin container that is excellent in both drop-proof performance and reduced-pressure absorption performance.

  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 positioned above the grounding portion is formed inside the inner peripheral wall, and a plurality of heel portions and a plurality of leg groove portions are alternately provided in the circumferential direction on the grounding portion. A synthetic resin container is provided.

In the synthetic resin container of the present invention,
1. The outer peripheral width of the heel portion is 4 to 72 mm;
2. The ratio of the inner diameter of the grounding portion to the outer diameter of the grounding portion is 0.75 to 0.95;
3. The ratio of the outer peripheral width of the heel portion to the radial length of the heel portion is 0.5 to 20,
4). A step is formed between the outer peripheral wall of the leg portion and the grounding portion,
5. Between the outer edge of the movable bottom part and the inner edge in contact with the central part, it protrudes in the radial direction, and a plurality of circumferentially formed curved parts, and between the curved parts, the inner edge of the movable bottom part is above the outer edge in the container axial direction. Having a groove to connect so as to be located in the
6). The groove portion of the movable bottom portion is formed radially,
7). The depth of the groove of the movable bottom is 0.1 to 0.1 at the center position between the inner and outer edges of the movable bottom.
Being 3.0 mm,
8). 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. ,
9. The center line of the leg groove part is located on an imaginary straight line extending from the center line of the groove part of the movable bottom part;
10. The number of the leg groove portions and the number of the groove portions of the movable bottom portion are the same;
11. The outer edge of the movable bottom is formed by a plurality of straight lines and / or curves;
12 A folded part is formed at the upper end of the inner peripheral wall of the leg part, and the inner edge of the folded part is connected in line with the position of the outer edge of the movable bottom part;
13. The central part of the movable bottom part protrudes outward or inward;
Is preferred.

  In the synthetic resin container of the present invention, the bottom portion has a movable bottom portion that imparts a reduced pressure absorption performance, and includes a plurality of heel portions and a plurality of leg groove portions provided alternately in the circumferential direction. Even when the movable bottom portion is enlarged and the leg portion is thinned, when the leg portion receives an impact due to dropping, sufficient fall resistance can be ensured by the cushioning effect of the leg groove portion. Therefore, in the synthetic resin container of the present invention, the leg portion does not necessarily have the same thickness as the conventional one, and there is no problem even if the movable bottom portion is enlarged and the leg portion is narrowed instead. The shape can be determined freely. Furthermore, if a heel part and a leg groove part are provided in the leg part, the leg part itself also exhibits reduced pressure absorption performance. In particular, in a mode in which the number of leg groove portions of the leg portion and the groove portion of the movable bottom portion are the same, and these are positioned on the same straight line, the direction in which the impact of the fall is transmitted can be controlled, so that the load due to the impact is concentrated locally. Without dropping, the drop resistance is further improved. In addition, the reduced pressure absorption effect is further improved.

It is a side view which shows an example of the synthetic resin containers of this invention. It is a figure explaining the bottom part of the synthetic resin containers of FIG. (A) is a bottom view and (B) is a partial cross-sectional schematic view. It is a figure explaining the bottom part of the synthetic resin containers of FIG. (C) is a partially enlarged view of the leg portion shown in FIG. 2-1 (B), and (D) is an enlarged view taken along the line DD in FIG. 2-1 (A). It is a figure which shows the aspect which provided the level | step difference 30 in the synthetic resin container of this invention. It is a partially expanded sectional view of the bottom part for demonstrating the movable behavior of the synthetic resin containers of this invention. (Α) is an α-α cross-sectional view in FIG. 2-1 (A), and (β) is a β-β cross-sectional view in FIG. 2-1 (A). It is a partial cross section schematic diagram 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 filling with an intermediate temperature, (C) is a reduced pressure state after filling with an intermediate temperature, and (D) is a diagram showing a superposition of (A) to (C). . It is a side view which shows another embodiment of the synthetic resin containers of this invention. It is a figure explaining the bottom part of the synthetic resin containers shown in FIG. (A) is a bottom view and (B) is a partial cross-sectional schematic view.

The synthetic resin container of the present invention will be described based on specific examples shown in the accompanying drawings.
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 and a movable bottom portion 20 located inside the leg portion 10. 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 movable bottom portion 20 is located above the grounding portion 12 and is connected to the upper end of the inner peripheral wall 13 of the leg portion 10.

<Leg>
FIGS. 2-1 and 2-2 are views for explaining the bottom of the example of the synthetic resin container of the present invention shown in FIG. In the present invention, together with the movable bottom portion 20 described above, a plurality of leg groove portions 15 are provided in the ground contact portion 12 of the leg portion 10 at equal intervals in the circumferential direction, and a heel portion 14 is provided between the adjacent leg groove portions 15 and 15. It has important features in terms. Due to such characteristics, in the synthetic resin container of the present invention, even when subjected to an impact due to dropping, wrinkles and crushing are unlikely to occur in the leg portion 10 due to the buffering effect of the leg groove portion 15. Therefore, in the present invention, even if the movable bottom portion 20 is enlarged in order to improve the vacuum absorption performance, and the leg portion 10 is made narrower by shortening the radial dimension of the grounding portion 12, sufficient drop resistance performance can be obtained. Can be maintained.

  Thus, in the synthetic resin container of the present invention, even if the radial dimension of the grounding portion 12 is shortened and the leg portion 10 is made thin, sufficient drop resistance can be exhibited. 10, the ratio of the inner diameter to the outer diameter of the grounding portion 12 is preferably 0.75 to 0.95. If the leg portion 10 is too thin, the shaping of the heel portion 14 and the leg groove portion 15 is deteriorated, and wobbling is likely to occur when grounded, so that the self-supporting property may be impaired. There is a possibility that it cannot be demonstrated. The outer diameter of the grounding portion 12 is represented by a line segment L′ L ″, and the inner diameter of the grounding portion 12 is represented by a line segment M′M ″. L, L ′, L ″, M, M ′, and M ″ will be described in detail later.

  The heel portion 14 and the leg groove portion 15 reversibly deform the entire grounding portion 12 when a drop impact load is applied, and the drop impact is transmitted even when the leg portion 10 has the radial dimension. It is preferable to set the following shape so as to effectively prevent wrinkles and crushing from occurring at the bottom by controlling the direction.

As shown in FIG. 2-2 (C), the end points of the heel part 14 and the leg groove part 15 are L, the start points of the heel part 14 and the leg groove part 15 are M, and the heel part when the container 1 is placed empty. The grounding point with 14 grounding planes G is N. The starting point M is located at the boundary between the ground contact portion 12 and the inner peripheral wall 13.
A point on the groove bottom curve LM when the valley depth of the leg groove portion 15 with respect to the heel portion 14 is maximum is O, and a point on the heel portion curve LNM is P. Let L ′ and M ′ be the projections of points L and M onto the ground contact surface G in the vertical direction, respectively. The points L ′ and M ′ that are symmetrical with respect to the central axis (not shown) of the container 1 are denoted by L ″ and M ″, respectively.

In the present invention, the leg height, the radial length, the inner diameter height, and the valley depth of the heel portion 14 are defined as follows, and preferred ranges thereof are as follows.
Line segment LL ′: represents the leg height of the heel part 14 and is preferably 1 to 3 mm.
Line segment L′ M ′: represents the length of the heel portion 14 in the radial direction, and is preferably 3 to 7 mm.
Line segment MM ′: represents the height of the inner diameter of the heel portion 14 and is preferably 0.1 to 1.0 mm.
Line OP: represents the valley depth of the heel portion 14, and is preferably 0.2 to 1.0 mm.
Further, the heel portion curve LNM is preferably arcuate, and when the arc radius is defined as the tip radius, the tip radius is preferably 2 to 6 mm.
Since the heel portion 14 has a shape that satisfies the above numerical range, the entire ground contact portion 12 can be effectively reversibly deformed.

  Referring to FIG. 2A, the outer peripheral width b of the heel portion 14 is preferably 4 to 72 mm in terms of the outer edge length of the heel portion 14. Thus, when a load due to a drop impact is applied, the heel portion 14 and the leg groove portion 15 are reversibly deformed with the end point L and its vicinity as a fulcrum. Further, circumferential bending between the heel portion 14 and the leg groove portion 15 is likely to occur, and generation of wrinkles due to circumferential compression of the outer peripheral wall 11 is suppressed.

  Furthermore, in the present invention, the ratio of the outer peripheral width b of the heel portion 14 to the radial length L′ M ′ of the heel portion 14 is preferably 0.5 to 20. Moreover, it is preferable that the bottom surface of the heel portion 14 is formed in a shape that is closer to a square, whereby the load that has acted on the heel portion 14 is effectively distributed in the radial direction and the circumferential direction. , The occurrence of irreversible deformation such as buckling is suppressed, and reversible deformation of the entire ground contact portion 12 is promoted.

  Further, as shown in FIG. 2-2 (D), the leg groove portion 15 is sandwiched between the side surfaces 141 and 141 of the two adjacent heel portions 14 and 14, and is formed by a curved surface extending in the radial direction. A groove bottom 151 is provided. Both side surfaces 141 and 141 form an angle α, and the angle α is preferably 80 to 100 °. The width d of the groove bottom 151 of the leg groove is preferably 0.5 to 2.0 mm.

  It is preferable that the connecting portion between the groove bottom 151 of the leg groove portion and the side surface 141 of the heel portion and the connecting portion between the side surface 141 of the heel portion and the front end surface 142 are configured with curved surfaces. Further, the boundary between the groove bottom 151 of the leg groove and the side surface 141 of the heel portion is preferably an arc surface having a radius of 0.3 to 1.0 mm, and the boundary between the side surface 141 of the heel portion and the tip surface 142 is It is preferably an arc surface having a radius of 0.5 to 2.0 mm.

  Furthermore, the groove bottom 151 of the leg groove part is preferably formed by a gentle line (curved line or straight line) along the radial direction, as shown in FIG. As a result, bending deformation easily occurs between the heel portion 14 and the leg groove portion 15 adjacent to each other, and deformation that is bent in the middle of the leg groove portion 15 is suppressed. The direction can be reversibly deformed.

  FIG. 3 is a view showing a mode in which a step 30 is provided in the synthetic resin container of the present invention. In the present invention, the heel portions 14 and the leg groove portions 15 described above are alternately provided on the ground contact portion 12 of the leg portion 10. Further, as shown in FIG. It is preferable that a step 30 is provided between the contact portion 12 and the grounding portion 12 in the circumferential direction. As a result, even when an excessive load is applied to the heel portion 14 and the leg groove portion 15, the bending deformation at the boundary between the heel portion 14 and the leg groove portion 15 proceeds excessively, and fold marks are attached to the outer peripheral wall 11. Can be suppressed. The step 30 is preferably formed of a curved surface. Moreover, it is preferable that the depth of the level | step difference 30 is 0.1-1.0 mm. The depth of the step 30 is defined as S at the boundary between the step 30 and the outer peripheral wall 11, T as the boundary between the step 30 and the grounding portion 12, and a line perpendicular to the line segment ST at the midpoint of the line segment ST. Is represented by a distance u from the intersection of the right-angle line and the step 30 to the line segment ST.

In the leg part 10, it is not limited to the specific example mentioned above, A various change is possible.
For example, in the specific example shown in the figure, the plurality of heel portions 14 and leg groove portions 15 are each formed in 16 pieces, but the present invention is not limited to this, and preferably has symmetry. In addition, although it depends on the diameter of the movable bottom portion 20, it is desirable to increase the grounding performance and drop resistance performance of the leg portion 10 in the range of 3 to 72, more preferably 8 to 24. If the number is less than 3, the cushioning effect of the leg portion 10 may be smaller than that in the above range and drop resistance may be reduced. If the number exceeds 72, The width of the leg groove 15 may be smaller than that in the above range, and molding may be difficult.
In addition, the leg groove portion 15 preferably has a substantially trapezoidal shape constituted by both side surfaces 141, 141 and a groove bottom 151, but is not limited thereto, and may be, for example, an arc shape or a V shape.

<Movable bottom>
Next, the movable bottom 20 in the synthetic resin container of the present invention will be described. As already described, in the present invention, it is also an important feature that the movable bottom portion 20 is provided at the bottom portion.

  Referring to FIGS. 2-1 (A) and (B), the movable bottom portion 20 is formed with a substantially flat central portion 22 defined by an annular protrusion 21 protruding downward at the center thereof. The portion 22 is located at the uppermost position in the container axis direction in the entire movable bottom portion 20. The annular protrusion 21 does not necessarily have to be formed. However, the annular protrusion 21 is formed at a portion where the inner edge of the movable bottom portion 20 and the outer edge of the central portion 22 are in contact with each other as in the present embodiment. It is possible to absorb the radial deflection caused accordingly.

  Further, as is apparent from FIG. 2A, the movable bottom portion 20 is formed between the inner edge (the outer edge of the annular protrusion 21 when the annular protrusion 21 is formed) in contact with the center portion 22 from the outer edge of the movable bottom portion 20. 2, a plurality of curved portions 23 projecting downward in the radial direction are formed at equal intervals in the circumferential direction, and an inner edge (outer edge of the annular projection 21) that contacts the central portion 22 between the adjacent curved portions 23, 23. ), A plurality of groove portions 24 extending toward the outer edge of the movable bottom portion 20 are formed at equal intervals.

  The curved portion 23 and the groove portion 24 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. In particular, the arrangement of the groove portions 24 is preferably determined so that the center line of the leg groove portion 15 provided in the leg portion 10 is positioned in a virtual straight line extending the center line of the groove portion 24. It is most preferable that the arrangement of the groove portions 24 is determined such that the groove portions 24 are provided in the same amount as that of the leg groove portions 15 and the center lines of the leg groove portions 15 are positioned in an imaginary straight line extending from the center lines of the groove portions 24. Thereby, in the synthetic resin container of the present invention, the direction in which the impact of the drop is transmitted can be controlled, and the load due to the impact does not concentrate locally, so that the reduced pressure absorption performance and the drop resistance performance are maximized. be able to. Furthermore, the design of the container can be improved, the mold can be easily manufactured, and the mold can be easily removed during the manufacture.

  As is clear from FIGS. 2-1 (A) and (B), the groove portion 24 has a curved bottom portion 24 a protruding downward, and is inclined upward from the outer edge of the movable bottom portion 20 toward the central portion 22. The inner edge (outer edge of the annular protrusion 21) that is in contact with the central portion 22 rather than the outer edge of 20 is formed so as to be positioned above the container axis direction.

The groove 24 absorbs the bending that occurs in the radial direction of the bottom when heat is further applied due to the weight of the contents, or filling at an intermediate temperature or high temperature, 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 so that the shape restoring action can be exhibited.
The depth D of the groove 24 is, as shown in FIG. 4 (α), near the center position m1 between the inner and outer edges of the movable bottom 20 (in the specific example shown, the position of the inner edge is the outer edge of the annular protrusion 21). And 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 24. Specifically, as shown in FIG. 4 (α), the center position m1 is obtained by drawing a line segment X1 connecting the inner and outer edges of the movable bottom portion 20 in the groove 24 and passing through the midpoint of the line segment X1. This means that the straight line Y1 perpendicular to the crossing of the curved bottom 24a of the groove portion. The depth D is expressed by the difference between the distance D1 between the line segment X1 and the point m1 and the distance D2 between the line segment X2 and the point m2, that is, D2−D1, with reference to FIGS. Is done. A line segment X2 is a line segment connecting the inner and outer edges of the movable bottom portion 20 in the bending portion 23, and m2 is a straight line Y2 passing through the midpoint of the line segment X2 and perpendicular to the line segment X2 and the bending portion 23. It is a crossing point.
In addition, the inclination angle θ of the curved bottom portion 24a 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. 4 (α), the inclination angle θ is represented by an angle of the tangent line Z with respect to the horizontal direction by drawing the tangent line Z of the curved bottom 24a of the groove at the center position m1. .
Furthermore, the radius of curvature R of the curved bottom 24a of the groove is preferably in the range of 30 to 300 mm. Thereby, when the movable bottom part 20 moves from the outer edge of the movable bottom part 20 as a starting point, it is possible to reduce the bending that occurs in the radial direction as compared with the case of the linear shape.
In addition, the shape of the above-mentioned movable bottom part 20 is one form, Comprising: It is not limited to the said shape, Other shapes may be sufficient if it is a bottom part shape which has a pressure reduction absorption capability.

In FIG. 5 for explaining the fluctuation of the movable bottom according to the change in internal pressure of the synthetic resin container of the present invention, (A) is an empty state, (B) is a state immediately after medium temperature filling (for example, 65 ° C.), ( (C) is a partial cross-sectional view showing the decompressed state after filling in (B), and (D) is a diagram in which (A) to (C) are superimposed.
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, even when filled and sealed at an intermediate temperature, as described above, the movable bottom portion does not excessively move downward due to the formation of the groove portion 24. In the case of being cooled after being filled with medium temperature and in a reduced pressure state (C), the movable bottom portion 20 is smoothly moved upward by utilizing the shape restoring action of the groove portion 24, and the movable portion after absorbing the reduced pressure is moved. The bottom part 20 is located above the empty state (A).
As is apparent from FIG. 5D in which these figures are overlaid, in the synthetic resin container of the present invention, even when the contents are filled at an intermediate temperature and the contents's own weight and heat 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.

Next, another aspect of the movable bottom portion 20 will be described with reference to FIGS. In the present embodiment, an annular folded portion 40 is formed at the upper end of the inner peripheral wall 13 of the leg portion 10 and protrudes upward from the upper end of the inner peripheral wall 13 and then folded downward. The inner edge 40a of the folded portion 40 is formed. Is different from the synthetic resin container 1 of the present invention shown in FIG. 1 in that it is connected in line with the position of the outer edge of the movable bottom portion 20.
Although the depth of the folding | returning part 40 is not limited to this, It is suitable for it to exist in the range of 0.5-3.0 mm by the perpendicular distance from the upper end of a folding | turning part to the inner edge 40a of a folding | turning part. If the folded portion is shallower than the above range, the possibility that the inner peripheral wall 13 of the leg portion 10 will fall inward when the movable bottom portion 20 moves downward is increased compared to the case where the folded portion is within the above range, When it is larger than the above range, the moldability is inferior to that when it is within the above range.

  As described above, the movable bottom portion 20 is connected to the inner peripheral wall 13 of the leg portion 10 via the folded portion 40 having an appropriate depth, so that the weight and heat of the contents can be moved by filling with an intermediate temperature or a high temperature. Even when acting on the bottom portion 20, the inner peripheral wall 13 of the leg portion 10 is prevented from being excessively drawn (inwardly tilted) toward the center of the movable bottom portion 20, and the inner edge 40 a of the folded portion 40 is also excessively drawn. There is no. As a result, even when subjected to medium temperature or high temperature filling, etc., the movable bottom 20 does not protrude excessively or does not cause non-uniform deformation. Can also respond.

  In the embodiment of the movable bottom part 20, it is not limited to the specific example mentioned above, A various change is possible. For example, in the specific example shown in the figure, the central portion 22 of the movable bottom portion 20 is formed to be substantially flat, but may protrude outward or inward from the movable bottom portion 20, thereby the central portion 12. Can be made thinner, and a greater vacuum absorption performance can be exhibited.

  Furthermore, in the specific example shown in the figure, the outer edge of the movable bottom portion 20 forms a circle. However, the present invention is not limited to this. That is, the outer edge of the movable bottom portion is formed by a plurality of straight lines and / or curves. Also good. Specifically, the shape can be appropriately changed to a polygonal shape or a petal shape depending on the shape and width of the curved portion and the groove portion. In addition, when the said outer edge is made into polygonal shape, it becomes an origin when the said outer edge deform | transforms into the circumferential direction at the time of pressure reduction, and there exists an effect which suppresses generation | occurrence | production of the wrinkle in the said outer edge.

  The outer diameter of the movable bottom portion 20 is preferably 85 to 95% of the outer diameter of the ground contact 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 angle of the leg portion with the inner peripheral wall 13 may become steep and it may be difficult to mold. The outer diameter of the central portion 22 of the movable bottom portion is preferably 20 to 35% of the outer diameter of the movable bottom portion 20. It is preferable that the circle connecting the tops of the curved portions 23, 23... Has a diameter of 60 to 90% of the outer diameter of the movable bottom portion 20.

  The thickness of the bottom portion is preferably equal to or less than the thickness of the thinnest portion of the body portion, and although depending on the diameter of the movable bottom portion 20, the thickness of the movable bottom portion 20 excluding the central portion 22 is particularly zero. It is desirable that the thickness is reduced to 15 to 0.4 mm, particularly 0.2 to 0.3 mm.

  Regarding the crystallinity of the bottom, from the standpoint of maintaining the drop-proof performance, the crystallinity of the leg 10 including the heel 14 and the leg groove 15 provided between the adjacent heels 14 and 14 is set to 20 to 20. It is preferable to increase to 50%. Further, from the viewpoint of suppressing the internal falling of the inner peripheral wall 13 of the leg 10, at least the degree of crystallinity of the inner peripheral wall 13 of the leg 10 is set at least when the folded portion 40 is formed. It is preferable to increase the crystallinity of the portion 40 to 20 to 50%.

<Manufacturing method>
The synthetic resin container of the present invention can be formed by a conventionally known manufacturing method as long as it has the bottom shape including the above-described movable bottom and legs. In order to make it possible, it is important that the movable bottom portion 20 is thin. Therefore, 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, the concavo-convex shape including the heel portions 14, 14..., The leg groove portions 15, 15..., The curved portions 23, 23. Therefore, it is preferable that the bottom mold has a rough surface in order to improve the releasability of the bottom mold. Therefore, in the molded synthetic resin container, the surface of the movable bottom 20 and the surface of the leg 10 that are in contact with the bottom mold are formed to be rough.

  For the synthetic resin container of the present invention, thermoplastic polyester resins that have been 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. Moreover, not only a single layer of the thermoplastic polyester resin, but also a multilayer structure of the thermoplastic polyester resin and a gas barrier resin or an oxygen-absorbing resin, to impart heat resistance that can withstand high temperature filling, The mouth portion of the preform to be used is preferably 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 drop resistance performance are imparted to the bottom that does not affect the appearance of the container. Therefore, the synthetic resin container of the present invention is useful as a container for the contents to be filled by heating. That is, the synthetic resin container of the present invention is suitable not only as a container for contents filled at a medium temperature such as seasonings and dressings, but also as a container for contents filled at a higher temperature. Can be used.

DESCRIPTION OF SYMBOLS 1 Synthetic resin container 5 Bottom part 10 Leg part 11 Outer peripheral wall 12 Grounding part 13 Inner peripheral wall 14 Heel part 15 Leg groove part 20 Movable bottom part 23 Curved part 24 Groove part

Claims (14)

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 consisting of a grounding part and an inner peripheral wall, and inside the inner peripheral wall of the leg part. , A movable bottom portion located above the grounding portion is formed,
A synthetic resin container in which a plurality of heel portions and a plurality of leg groove portions are alternately provided in the circumferential direction on the grounding portion.   The synthetic resin container according to claim 1, wherein an outer peripheral width of the heel portion is 4 to 72 mm.   The synthetic resin container according to claim 1 or 2, wherein a ratio of an inner diameter of the grounding portion to an outer diameter of the grounding portion is 0.75 to 0.95.   The synthetic resin container according to any one of claims 1 to 3, wherein a ratio of an outer peripheral width of the heel portion to a radial length of the heel portion is 0.5 to 20.   The synthetic resin container according to any one of claims 1 to 4, wherein a step is formed between an outer peripheral wall of the leg portion and a grounding portion.   Between the outer edge of the movable bottom part and the inner edge in contact with the central part, it protrudes in the radial direction, and a plurality of circumferentially formed curved parts, and between the curved parts, the inner edge of the movable bottom part is above the outer edge in the container axis direction. The synthetic resin container according to any one of claims 1 to 5, further comprising a groove portion connected so as to be positioned.   The synthetic resin container according to claim 6, wherein the groove portion of the movable bottom portion is formed radially.   The synthetic resin container according to claim 6 or 7, 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 6 to 8, 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 6 to 9, wherein a center line of the leg groove portion is located on an imaginary straight line obtained by extending a center line of the groove portion of the movable bottom portion.   The synthetic resin container according to any one of claims 6 to 10, wherein the number of the leg groove portions and the number of the groove portions of the movable bottom portion are the same.   The synthetic resin container according to any one of claims 1 to 11, wherein an outer edge of the movable bottom portion is formed by a plurality of straight lines and / or curves.   The synthetic resin container according to any one of claims 1 to 12, wherein a folded portion is formed at an upper end of an inner peripheral wall of the leg portion, and an inner edge of the folded portion is connected to coincide with a position of an outer edge of the movable bottom portion. .   The synthetic resin container according to any one of claims 1 to 13, wherein a central portion of the movable bottom portion protrudes outward or inward.