WO2016121890A1

WO2016121890A1 - Synthetic resin container

Info

Publication number: WO2016121890A1
Application number: PCT/JP2016/052539
Authority: WO
Inventors: 三浦　正樹; 和志松清; 卓細貝; 秀人門前; 祐一宮崎; 山崎　和彦
Original assignee: 東洋製罐株式会社
Priority date: 2015-01-29
Filing date: 2016-01-28
Publication date: 2016-08-04

Abstract

The purpose of the present invention is to provide a synthetic resin container having excellent decompression absorption performance, having a bottom structure capable of withstanding internal pressure changes associated with hot-packing and subsequent decompression absorption, and having excellent freestanding capability in the container, and excellent shape stability in the bottom or the container. According to the present invention, provided is a synthetic resin container having decompression absorption performance in the bottom, wherein the synthetic resin container is characterized in that: a leg part comprising an outer peripheral wall, a ground-contacting part, and an inner peripheral wall is formed at the bottom thereof; a moveable bottom is formed farther to the inside than the inner peripheral wall of the leg part; and curved parts and grooved parts are provided between the outer edge of the moveable bottom and an inner edge in contact with a center part.

Description

Plastic container

The present invention relates to a synthetic resin container having a vacuum absorption performance at the bottom, and more specifically, has a bottom structure that can cope with a change in internal pressure associated with hot filling and subsequent vacuum absorption, as well as the self-supporting property of the container and the bottom. Or it is related with the container made from a synthetic resin excellent also in the shape stability of a container.

Synthetic resin containers are widely used as packaging containers for various liquids because they are excellent in light weight and impact resistance. 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.

Hot filling of the contents to enhance the shelf life of the contents is widely used in synthetic resin containers such as polyester, but due to the volumetric shrinkage of the contents due to cooling, the pressure is reduced in the synthetic resin containers. Deformation always occurs. In order to prevent this, various synthetic resin containers having a vacuum absorbing performance at the bottom have been proposed (Patent Documents 1 to 3).

JP 2012-91830 A Japanese Patent No. 5408501 JP 2013-144560 A

The synthetic resin containers having the bottom shape described in Patent Documents 1 to 3 above all exhibit a pressure reducing performance by raising the bottom-like bottom surface toward the inside of the container at the time of pressure reduction. Various improvements, such as increasing the amount of movement of the bottom surface, have been made in order to exhibit excellent vacuum absorption performance.

However, in such a bottom portion having a structure that is greatly deformed toward the inside of the container, when the contents are filled by hot filling and the weight and heat of the contents act on the raised bottom surface, the raised bottom surface becomes The container may protrude downward from the grounding surface of the container, which may impair the independence of the container.

In addition, when the internal pressure changes after filling and the inside of the container is depressurized and the bottom surface is deformed toward the inside of the container, the container is deformed as desired due to the thickness distribution on the bottom surface, filling conditions, surrounding environment, etc. Otherwise, it may deform non-uniformly and impair the shape stability of the bottom or container.

Accordingly, an object of the present invention is to have a bottom structure that has excellent decompression absorption performance and can cope with a change in internal pressure accompanying hot filling and subsequent decompression absorption. The object is to provide a synthetic resin container excellent in shape stability.

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 on the inner side of the inner peripheral wall. Between the inner edge contacting the outer edge and the central portion of the movable bottom portion, a plurality of protrusions project in the radial direction and are formed in the circumferential direction. A synthetic resin container is provided that includes a curved portion and a groove portion between the curved portions that connects the inner edge of the movable bottom portion so as to be positioned above the outer edge in the container axial direction.

In the synthetic resin container of the present invention,
1. The grooves are formed radially;
2. The groove has a curved bottom portion projecting downward;
3. The depth of the groove is 0.1 to 3.0 mm at the center position between the inner and outer edges of the movable bottom,
4). The angle of inclination of the curved bottom with respect to the horizontal direction is 2 to 15 ° at the center position between the inner and outer edges of the movable bottom;
5. The curvature radius R of the curved bottom is 30 to 300 mm;
6). The width of the groove is wider or narrower than the width of the inner and outer edges at the center position between the inner and outer edges of the movable bottom;
7). An annular protrusion protruding downward is formed at the boundary between the inner edge of the movable bottom part and the outer edge of the central part,
8). A folded portion is formed at the upper end of the inner peripheral wall of the leg portion, and the inner edge of the folded portion is connected in line with the position of the outer edge of the movable bottom portion;
9. The central portion protrudes upward or downward;
10. The synthetic resin is polyester, the outer peripheral wall upper end and the outer edge of the movable bottom portion are connected by an annular support, and the crystallinity by the density method of the annular support is 30% or more,
11. A plurality of heel portions and a plurality of leg groove portions are alternately provided in the circumferential direction on the grounding portion;
12 A step is formed between the outer peripheral wall of the leg and the grounding portion;
13 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;
14 The number of the leg groove portions and the number of the groove portions of the movable bottom portion are the same;
Is preferred.

Further, according to the present invention, there is provided a polyester container having a vacuum absorbing performance at the bottom, wherein the bottom is formed with an outer peripheral wall continuous from the trunk, a grounding portion and an inner peripheral wall. A movable bottom portion is formed on the inner side of the inner peripheral wall and positioned above the grounding portion.
There is provided a polyester container characterized in that the annular support connecting the upper end of the inner peripheral wall and the outer edge of the movable bottom has a crystallinity of 30% or more by density method.

Furthermore, according to the present invention, 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, inside the inner peripheral wall of the leg part and above the grounding part. A method for producing a polyester container, comprising: a movable bottom portion positioned; and an annular support portion connecting the upper end of the inner peripheral wall and the outer edge of the movable bottom portion,
When the preform is biaxially stretch blow-molded using the body mold and the bottom mold, the portion corresponding to the annular support portion of the bottom mold is adjusted to a temperature of 130 to 160 ° C. A method of manufacturing a polyester container is provided.

In the synthetic resin container of the present invention (in this specification, it may be abbreviated as “container of the present invention”), it protrudes in the radial direction on the inner side of the leg formed on the bottom of the container, and plural in the circumferential direction. A movable bottom portion is formed that includes the formed curved portion and a groove portion that is present between the curved portions and is inclined upward toward the center portion. According to such a configuration, it is possible to increase the distance (height distance) between the movable bottom portion and the grounding surface, and when the movable bottom portion protrudes downward due to the heat or weight of the contents in hot filling, It is possible to prevent the movable bottom from protruding beyond the ground plane.

In addition, when the weight of the contents and heat are applied by hot filling or the like in the upwardly inclined groove portion, the bending that occurs in the radial direction of the bottom portion is absorbed, while the stress that tries to return to the original shape (upward inclined state) Act. Therefore, when the contents are cooled and the inside of the container is depressurized, the entire movable bottom portion moves smoothly upward using the above-described action.

Furthermore, in the container of the present invention, when the leg portion that does not contribute to the vacuum absorption is formed at the bottom portion, the internal pressure change is coupled with the fact that the amount of deformation of the movable bottom portion is controlled as described above. Even if this occurs, the height of the container can be kept constant at all times, the independence of the container is maintained, and the transportability is excellent.

In addition, when the container of the present invention is made of polyester and has an annular support having a high degree of crystallinity, the heat or weight of the contents is applied during hot filling and the movable bottom protrudes downward. Further, it is possible to more effectively prevent the inner peripheral wall from being bent inward in the container radial direction, and more reliably prevent the movable bottom portion from protruding beyond the ground contact portion. This is because the degree of crystallinity of the annular support portion connecting the inner peripheral wall of the leg portion of the bottom portion and the outer edge of the movable bottom portion is as high as 30% or more and has rigidity.

Furthermore, in the above-described method for producing a polyester container having an annular support, the crystallinity of the annular support connecting the inner peripheral wall of the leg and the outer edge of the movable bottom is set to 30% or more by ordinary one-stage blow molding. Such a polyester container can be produced with high productivity.

It is a side view which shows an example of the container of this invention. It is the bottom view (A) and partial cross section schematic (B) of the container shown in FIG. It is a partially expanded sectional view of the bottom part for demonstrating the movable behavior of the container shown in FIG. 2A is a cross-sectional view taken along the line aa in FIG. 2A, and FIG. 2B is a cross-sectional view taken along the line bb in FIG. It is a partial cross section figure for demonstrating the behavior of the bottom part of the container shown in FIG. 1, (A) is an empty state, (B) is a state immediately after hot filling, (C) is decompression after hot filling. The state (D) shows the superposition of (A) to (C). It is a side view which shows an example of the container of this invention in case it has a folding | turning part. It is the bottom view (A) and partial cross-sectional schematic (B) of the container shown in FIG. It is a partially expanded sectional view of the bottom part for demonstrating the movable behavior of the container shown in FIG. FIG. 6A is a sectional view taken along the line aa in FIG. 6A, and FIG. 6B is a sectional view taken along the line bb in FIG. It is a bottom view which shows another example of the container shown in FIG. It is a side view which shows an example of the container of this invention in case it has an annular support part. It is the bottom view (A) and partial cross-sectional schematic (B) of the container shown in FIG. It is the bottom view (A) and partial cutaway schematic view (B) which show another example of the container of this invention in the case of having an annular support part. It is a figure for demonstrating an example of the suitable manufacturing method of the container of this invention in case it has an annular support part. It is a side view which shows an example of the container of this invention in case a knurling is provided in the leg part. It is a figure explaining the bottom part of the container 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 container of FIG. (C) is a partially enlarged view of the leg portion shown in FIG. 14-1 (B), and (D) is an enlarged view taken along arrow DD in FIG. 14-1 (A). It is a figure which shows the aspect which provided the knurling and the level | step difference 30 in the leg part in the container of this invention. It is a side view which shows another embodiment of the container of this invention in case a knurling is provided in the leg part. It is a figure explaining the bottom part of the container shown in FIG. (A) is a bottom view and (B) is a partial cross-sectional schematic view.

The container of the present invention will be described based on specific examples shown in the accompanying drawings. A 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 continuous from the bottom part, and a central body part 4c located between the upper body part 4a and the lower body part 4b.

The central body 4c has three

circumferential ribs

6, 6, and 6 formed in parallel and at equal intervals to ensure the mechanical strength of the body and the shape retaining property against internal pressure deformation. 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 by the ribs 7. The body 4 and the bottom 5 do not necessarily have to be clearly defined.

Roughly speaking, the bottom portion 5 includes an annular leg portion 8, a movable bottom portion 9 located inside the leg portion 8, and a central portion 12 located inside the movable bottom portion 9. The leg portion 8 is located below the rib 7 and includes an outer peripheral wall 8a continuous from the trunk portion 4, a grounding portion 8b, and an inner peripheral wall 8c that forms a rising upward from the grounding portion 8b. The movable bottom portion 9 is located above the grounding portion 8 b and is connected to the upper end of the inner peripheral wall 8 c of the leg portion 8.

At the center of the bottom portion, a substantially flat central portion 12 defined by an annular protrusion 11 protruding downward is formed. The central portion 12 is located at the uppermost position in the container axis direction in the region surrounded by the grounding portion 8b. Although the annular protrusion 11 is not necessarily formed, the annular protrusion 11 is formed at the boundary between the inner edge of the movable bottom portion 9 and the outer edge of the central portion 12 as in the present embodiment, so that the movement of the movable bottom portion 9 can be performed. It is possible to absorb the bending in the radial direction.

<Curved part, groove part>
As is clear from FIG. 2A, there is a gap between the outer edge of the movable bottom portion 9 and the inner edge in contact with the central portion 12 (the outer edge of the annular protrusion 11 when the annular protrusion 11 is formed) in the radial direction. A plurality of curved portions 13 projecting in the circumferential direction (16 in the radial direction in FIG. 2) are formed at equal intervals, and between the adjacent

curved portions

13, 13, the inner edge (annular shape) of the movable bottom portion 9 is formed. A plurality of groove portions 14 (16 in FIG. 2) are formed at equal intervals so as to connect the outer edge of the protrusion 11 so as to be positioned above the outer edge of the movable bottom portion 9 in the container axis direction. As shown in the drawing, the curved portion 13 and the groove portion 14 are formed in a uniform shape and at equal intervals in order to ensure uniform deformation during filling of the contents or during decompression. desirable.

As is clear from FIG. 2, the groove portion 14 has a curved bottom portion 14 a protruding downward, and is inclined upward from the outer edge of the movable bottom portion 9 toward the central portion 12. That is, the groove portion 14 is formed such that the inner edge (outer edge of the annular protrusion 11) in contact with the center portion 12 is positioned higher in the container axial direction than the outer edge of the movable bottom portion 9.

The groove 14 absorbs the bending that occurs in the bottom radial direction when the contents are heavy or when heat is applied due to hot filling or the like. It is preferable to set the depth and width of the groove, the inclination angle of the curved bottom, the radius of curvature, and the like so that the shape restoring action can be exerted smoothly.

As shown in FIG. 3A, the depth D of the groove portion is near the center position M1 between the inner and outer edges of the movable bottom 9 (in the specific example shown in the figure, the position of the inner edge is the outer edge of the annular protrusion 11). It is preferable that it is deepest. 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 a groove part. Specifically, as shown in FIG. 3A, the center position M1 is drawn by a line segment X1 connecting the inner and outer edges of the movable bottom 9 in the groove portion 14, and passes through the midpoint of the line segment X1. Means a point where a straight line Y1 perpendicular to the crossing of the curved bottom portion 14a of the groove portion intersects. 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 9 in the bending portion 13, and M2 is a straight line Y2 that passes through the midpoint of the line segment X2 and is perpendicular to the line segment X2 and the bending portion 13. It is a crossing point.

In the specific example shown in FIG. 2A, the width in the circumferential direction of the groove portion 14 is the widest in the vicinity of the center position M1, that is, the groove portion 14 is formed in a substantially spindle shape, but is movable. Even if it is formed so as to be wide in the vicinity of the inner and outer edges of the bottom portion 9 and narrowest in the vicinity of the center position M1, it is preferable because the movable bottom portion can be easily moved and restored.

The inclination angle θ of the curved bottom 14a of the groove 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. 3A, the inclination angle θ is expressed by an angle with respect to the horizontal direction of the tangent line Z by drawing the tangent line Z of the curved bottom 14a of the groove at the center position M1. .

The curvature radius R of the curved bottom portion 14a of the groove is preferably in the range of 30 to 300 mm. Thereby, when the movable bottom part 9 moves from the outer edge of the movable bottom part 9 as a starting point, the curved bottom part has a non-curved surface shape (for example, constituted by one or two or more planes) in the radial direction. The bending which arises can be reduced.

The thickness of the groove 14 is preferably thin. As a result, when weight and heat are applied due to hot filling or the like, the adjacent curved portions 13 are easily bent so as to widen the interval, and at the time of decompression, the adjacent curved portions 13 are narrowed so as to reduce the interval. It becomes possible to move the entire movable bottom 9 uniformly and gently upward.

FIG. 4 is a diagram for explaining the fluctuation of the bottom according to the change in the internal pressure of the container of the present invention. (A) is an empty state, (B) is a state immediately after hot filling (for example, 87 ° C.), (C) is a partial sectional view showing a decompressed state after filling in (B), and (D) is FIG. 4 is a diagram in which (A) to (C) are superimposed.

In the container of the present invention, regardless of the filling temperature, immediately after the contents are filled (B), the movable bottom portion 9 moves downward from the empty state (A) due to the weight of the contents. Even when filled and sealed at a high temperature of ° C., as described above, since the groove portion 14 is formed, the movable bottom portion does not move excessively downward. Further, in the case of being cooled after being hot-filled and in a reduced pressure state (C), the movable bottom portion 9 smoothly moves upward by utilizing the shape restoring action of the groove portion 14, and the movable bottom portion after absorbing the reduced pressure. 9 comes to be positioned above the empty state (A).

As is clear from FIG. 4D, which is a superposition of these figures, in the container of the present invention, even when the contents are filled at a high temperature and the weight and heat of the contents act, the movable bottom 9 is If it does not move excessively downward, and then is in a reduced pressure state, the movable bottom portion 9 is gently deformed to rise to the inside of the container, thereby exhibiting a desired reduced pressure absorption performance. can do.

<Folding part>
Next, another embodiment of the present invention will be described with reference to FIGS. In the present embodiment, as is apparent from FIGS. 6B and 7 in particular, an annular shape that protrudes upward from the upper end of the inner peripheral wall 8c to the upper end of the inner peripheral wall 8c of the leg 8 and then turns downward. 1 is different from the container of the present invention shown in FIG. 1 in that an inner edge 15a of the folded portion 15 is connected in line with the position of the outer edge of the movable bottom 9.

The depth of the folded portion 15 is not limited to this, but is preferably in the range of 0.5 to 3.0 mm in the vertical distance from the upper end of the folded portion to the inner edge 15a of the folded portion. If the folded portion is shallower than the above range, the possibility that the inner peripheral wall 8c of the leg portion 8 will fall inward when the movable bottom portion 9 moves downward is increased as compared with the case where it is within the above range. If the folded portion is deeper than the above range, the moldability may be inferior to that in the above range.

As described above, the movable bottom portion 9 is connected to the inner peripheral wall 8c of the leg portion 8 via the folded portion 15 having an appropriate depth, so that the weight and heat of the contents are transferred by the hot filling or the like. 9, the inner peripheral wall 8 c of the leg portion 8 is prevented from being excessively drawn in the central direction of the movable bottom portion 9 (inward falling), and the inner edge 15 a of the folded portion 15 is also excessively drawn. Effectively prevented. As a result, even if it is applied to hot filling or the like, the bottom of the container according to the present embodiment having the folded portion is reduced in pressure because the movable bottom 9 does not protrude excessively or does not deform unevenly. Even uniform deformation sometimes occurs, and it can cope with hot filling at a high temperature of 87 ° C. or higher.

<Annular branch>
Still another embodiment of the present invention will be described with reference to FIGS. In this embodiment, the container is made of polyester, and as is clear from FIGS. 10A and 10B, the outer edge 9 a of the movable bottom portion 9 is interposed between the upper end of the inner peripheral wall 8 c of the leg portion 8 and the annular support portion 16. linked.

The annular support 16 is adjusted to have a high degree of crystallinity, that is, has a higher rigidity than other parts. Specifically, in the polyester container of the present embodiment, an annular support having a crystallinity of 30% or more by the density method, particularly 30 to 40%, is formed at a position connecting the upper end of the inner peripheral wall and the outer edge of the movable bottom. It has important characteristics.

In addition, the crystallinity degree by the said density method is calculated | required by a following formula.
X (%) = (ρc / ρ) × [(ρ−ρa) / (ρc−ρa)] × 100
Where
ρ indicates the density (g / cm ³ ) of the measurement site measured by the density gradient tube.
ρc represents the density (g / cm ³ ) of the crystal.
ρa represents the amorphous density (g / cm ³ ).
When polyethylene terephthalate is used as the polyester resin, the degree of crystallinity is determined using values of 1.455 (g / cm ³ ) as ρc and 1.335 (g / cm ³ ) as ρa.

FIG. 11 is a bottom view (A) and a partial cross-sectional view (B) showing another example of the polyester container of the present embodiment. In this embodiment, an annular support 16 is formed on the upper end of the inner peripheral wall 8c of the leg 8 at the upper end of the inner peripheral wall 8c, and then protrudes upward from the upper end of the inner peripheral wall 8c. This is different from the polyester container shown in FIGS. In other words, in this embodiment, the shape of the annular support portion 16 is a concave shape that is recessed inward of the container from the outer edge 9 a of the movable bottom portion 9.

The depth of the concave portion of the annular support portion 16 having the concave shape is not limited to this, but is preferably in the range of 0.5 to 3.0 mm in the vertical distance from the upper end of the concave portion to the outer edge 9a of the movable bottom portion 9. When the depth of the concave portion is in the above range, coupled with the high crystallinity of the annular support portion 16, the inward tilting of the inner peripheral wall 8 c of the leg portion 8 when the movable bottom portion 9 moves downward is very effective. Can be prevented. When the concave portion is deeper than the above range, the moldability may be inferior to that in the above range.

Thus, the movable bottom portion 9 is connected to the inner peripheral wall 8c of the leg portion 8 via the annular support portion 16 having a high degree of crystallinity, so that the weight and heat of the contents are transferred by the hot filling or the like. Even when acting on, the inner peripheral wall 8c of the leg portion 8 is extremely effectively prevented from being drawn excessively (inwardly falling) toward the center of the movable bottom portion 9. Furthermore, when the annular support portion 16 has a recessed shape that is recessed inward of the container, not only the leg can be prevented from falling down but also the outer edge 9a of the movable bottom portion 9 can be effectively prevented from being pulled in. As a result, even when subjected to hot filling or the like, the bottom of the container of the present invention is uniformly deformed even during decompression because the movable bottom 9 does not protrude excessively or does not deform unevenly. For example, it can cope with hot filling at a high temperature of 87 ° C. or higher.

In the polyester container of the present embodiment, as described above, in order to effectively prevent the inner wall 8c from falling down, it is important that the annular support 16 at the bottom has a crystallinity of 30% or more. In order to more effectively prevent the inner peripheral wall 8c from falling down, it is desirable that the crystallinity of the movable bottom portion 9 is similarly set to 30% or more, particularly 30 to 40%. From the viewpoint of heat resistance of the polyester container, it is desirable that the crystallinity of the barrel is in the range of 27 to 40%.

9 to 11 show the movable bottom portion 9 having the bending portion 13 and the groove portion 14. In the present embodiment having the annular support portion having a high degree of crystallinity, the movable bottom portion 9 is the bending portion. 13 and the groove part 14 may not necessarily be provided. In other words, as long as the bottom part has the reduced pressure absorption performance, the movable bottom part may have another shape. That is, from the viewpoint of maximizing the self-supporting property and shape stability of the container, it is preferable that the movable bottom portion 9 includes the curved portion 13 and the groove portion 14, but the self-supporting property and the shape stability of the container are improved. In addition, when there are other demands such as improvement of the decorating property of the bottom, it is preferable that the movable bottom 9 has other shapes.

<Leg>
FIG. 13, FIG. 14-1 and FIG. 14-2 are views for explaining an embodiment in which a so-called knurling is provided on a leg in the container of the present invention. In the present embodiment, an important feature is that a plurality of leg groove portions 17 are provided at equal intervals in the circumferential direction in the ground contact portion 8b of the leg portion 8, and a heel portion 18 is provided between the adjacent

leg groove portions

17 and 17. is there. Due to this feature, in the container according to the present embodiment, even if the impact due to the drop is received, the leg portion 8 is less likely to be wrinkled or crushed due to the buffering effect of the leg groove portion 17. For this reason, in this embodiment, even if the movable bottom portion 9 is enlarged in order to improve the vacuum absorption performance, and instead the leg portion 8 is narrowed by shortening the radial dimension of the grounding portion 8b, the impact due to dropping is reduced. Sufficient drop-proof performance can be ensured by the buffering effect of the leg groove when the part is received. Therefore, in this embodiment, 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, so the shape of the bottom portion can be freely set. I can decide. Furthermore, by providing the heel part and the leg groove part in the leg part, the leg part itself also exhibits the reduced pressure absorption performance.

Thus, in the container of this embodiment, even if the radial dimension of the grounding portion 8b is shortened and the leg portion 8 is made thin, sufficient drop resistance can be exhibited. The ratio of the inner diameter to the outer diameter of the grounding portion 8b is preferably 0.75 to 0.95. If the leg portion 8 is too thin, the heel portion 18 and the leg groove portion 17 are poorly shaped, and wobble tends to occur when grounded, so that the self-supporting property may be impaired. If the leg portion 8 is too thick, the effect of the present embodiment can be sufficiently obtained even if the movable bottom portion 9 is enlarged in order to improve the vacuum absorption performance, and even if the leg portion 8 is made thin instead, sufficient fall resistance can be maintained. There is a possibility that it cannot be demonstrated. The outer diameter of the grounding portion 8b is represented by a line segment N′N ″, and the inner diameter of the grounding portion 8b is represented by a line segment O′O ″. N, N ′, N ″, O, O ′, and O ″ will be described in detail later.

The heel portion 18 and the leg groove portion 17 reversibly deform the entire grounding portion 8b and transmit the drop impact even when the leg portion 8 has the radial dimension described above when the drop impact load is applied. It is preferable to set the following shape so that the direction can be controlled and wrinkles and crushing can be more effectively prevented from occurring at the bottom.

As shown in FIG. 14-2 (C), the end points of the heel portion 18 and the leg groove portion 17 are N, the start points of the heel portion 18 and the leg groove portion 17 are O, and the heel portion when the container 1 is placed empty. A grounding point with 18 grounding planes G is P. The starting point O is located at the boundary between the ground contact portion 8b and the inner peripheral wall 8c. Further, a point on the groove bottom curve NO when the valley depth of the leg groove portion 17 with respect to the heel portion 18 is maximum is Q, and a point on the heel portion curve NPO is R. Let N ′ and O ′ be the projections of points N and O onto the ground plane G in the vertical direction, respectively. Points N ′ and O ′ that are symmetrical with respect to the central axis (not shown) of the container 1 are denoted by N ″ and O ″, respectively.

In the present embodiment, the leg height, radial length, inner diameter height, and valley depth of the heel portion 18 are defined as follows. The preferred ranges for each are as follows.
Line segment NN ′ represents the leg height of the heel portion 18 and is preferably 1 to 3 mm.
Line segment N′O ′: represents the length of the heel portion 18 in the radial direction, preferably 3 to 7 mm.
Line segment OO ′: represents the height of the inner diameter of the heel portion 18 and is preferably 0.1 to 1.0 mm.
Line QR: Represents the valley depth of the heel portion 18 and is preferably 0.2 to 1.0 mm.

Further, the heel curve NPO is preferably arcuate, and when the arc radius is defined as the tip radius, the tip radius is preferably 2 to 6 mm.

When the heel portion 18 has a shape that satisfies the above numerical range, the entire ground contact portion 8b can be reversibly deformed effectively.

Referring to FIG. 14-1 (A), the outer peripheral width b of the heel portion 18 is represented by the outer edge length of the heel portion 18 and is preferably 4 to 72 mm. Thus, when a load due to a drop impact is applied, the heel portion 18 and the leg groove portion 17 are reversibly deformed with the end point N and its vicinity as a fulcrum. Moreover, it becomes easy to produce the bending of the circumferential direction between the heel part 18 and the leg groove part 17, and generation | occurrence | production of the wrinkles by the compression of the circumferential direction of the outer peripheral wall 8a is suppressed.

Furthermore, in the present invention, the ratio of the outer peripheral width b of the heel portion 18 to the radial length N′O ′ of the heel portion 18 is preferably 0.5 to 20. In addition, the bottom surface of the heel portion 18 is preferably formed in a shape that is closer to a square, whereby the load that has acted on the heel portion 18 is more effectively distributed in the radial direction and the circumferential direction. The occurrence of irreversible deformation such as buckling at 18 is suppressed, and reversible deformation of the entire ground contact portion 8b is promoted.

Further, as shown in FIG. 14-2 (D), the leg groove portion 17 is sandwiched between the side surfaces 181 and 181 of the two

adjacent heel portions

18 and 18 and is formed by a curved surface extending in the radial direction. A groove bottom 171 is provided. Both side surfaces 181 and 181 form an angle α. The angle α is preferably 80 to 100 °. The width d of the groove bottom 171 of the leg groove is preferably 0.5 to 2.0 mm.

It is preferable that the connection portion between the groove bottom 171 of the leg groove portion and the side surface 181 of the heel portion and the connection portion between the side surface 181 of the heel portion and the tip end surface 182 are formed of a curved surface. Further, the boundary between the groove bottom 171 of the leg groove and the side surface 181 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 181 of the heel portion and the tip surface 182 is It is preferably an arc surface having a radius of 0.5 to 2.0 mm.

Furthermore, it is preferable that the groove bottom 171 of the leg groove part is formed by a gentle line (curve or straight line) along the radial direction as shown in FIG. 14-2 (C). As a result, bending deformation is likely to occur between the heel portion 18 and the leg groove portion 17 adjacent to each other, and deformation that is bent in the middle of the leg groove portion 17 is suppressed. The direction can be reversibly deformed.

FIG. 15 is a view showing a mode in which a step 30 is provided in the container of the present embodiment. In the present embodiment, the heel portions 18 and the leg groove portions 17 described above are alternately provided on the ground contact portion 8b of the leg portion 8, but as shown in FIG. It is preferable that a step 30 is provided in the circumferential direction between 8a and the grounding portion 8b. As a result, even when an excessive load is applied to the heel portion 18 and the leg groove portion 17, it is possible to prevent the bending deformation at the boundary between the heel portion 18 and the leg groove portion 17 from proceeding excessively and causing a fold mark on the outer peripheral wall 8a. Because it can. The step 30 is preferably formed of a curved surface. The depth of the step 30 is preferably 0.1 to 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 8a, and T at the boundary between the step 30 and the grounding portion 8b, and is perpendicular to the line 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.

The leg portion 8 is not limited to the specific example described above, and various modifications can be made. For example, in the specific example shown in FIG. 14A, the plurality of heel portions 18 and leg groove portions 17 are respectively formed in 16 pieces, but the heel portion 18 and the leg groove portions 17 are not limited thereto. The heel portion 18 and the leg groove portion 17 are preferably arranged symmetrically in the ground contact portion 8b, and the number thereof is 3 to 72, more preferably 8 to 24, although it depends on the diameter of the movable bottom portion 9. It is desirable to be within the range in order to improve the ground contact performance and drop resistance performance of the legs 8. If the number is less than 3, the cushioning effect of the legs 8 is reduced as compared with the case where the number is within the above range, and the drop resistance may be deteriorated. If the number exceeds 72, the width of the leg groove portion 17 becomes smaller than that in the above range, and molding may be difficult.

The shape of the leg groove portion 17 constituted by the side surfaces 181 and 181 of the heel portion and the groove bottom 171 is preferably a substantially trapezoidal shape, but is not limited thereto, and may be, for example, an arc shape or a V shape. Good.

From the viewpoint of maintaining the drop-proof performance, it is preferable to increase the crystallinity of the leg portion 8 including the heel portion 18 and the leg groove portion 17 to 20 to 50%.

Further, in the present embodiment in which the knurling is provided in the leg portion, the movable bottom portion 9 does not necessarily include the curved portion 13 and the groove portion 14, in other words, as long as the bottom portion has a reduced-pressure absorbing performance, The shape may also be That is, from the viewpoint of maximizing the self-supporting property and shape stability of the container, it is preferable that the movable bottom portion 9 includes the curved portion 13 and the groove portion 14, but the self-supporting property and the shape stability of the container are improved. In addition, when there are other demands such as improvement of the decorating property of the bottom, it is preferable that the movable bottom 9 has other shapes.

When the movable bottom portion 9 has the curved portion 13 and the groove portion 14, the positional relationship between the curved bottom portion 13 and the groove portion 14, the heel portion 18 and the leg groove portion 17 is preferably as follows. That is, as shown in FIGS. 16 and 17, the bending portion 13 and the groove portion 14 are formed in a uniform shape and radially at equal intervals from the viewpoint of ensuring uniform deformation at the time of filling the contents or at the time of decompression. The arrangement of the groove portions 14 is preferably determined so that the center line of the leg groove portion 17 provided in the leg portion 8 is located in a virtual straight line extending the center line of the groove portion 14, and is the same as the number of the leg groove portions 17. It is most preferable that the arrangement of the groove portions 14 is determined so that the groove portions 14 are provided only and the center lines of the leg groove portions 17 are positioned in a virtual straight line extending from the center lines of the groove portions 14. Thereby, 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 can be maximized. 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.

<Various changes>
The container of this invention is not limited to embodiment mentioned above, A various change is possible. In the specific example shown in the figure, 16

curved portions

13, 13... And 16

groove portions

14, 14... Are formed in the movable bottom 9, but the present invention is not limited to this. The curved portion 13 and the groove portion 14 are preferably formed symmetrically on the movable bottom portion 9. Further, although depending on the diameter of the movable bottom portion 9, it is desirable that the number is in the range of 3 to 36 in order to increase the movable region of the movable bottom portion and to exhibit a greater reduced pressure absorption performance. If the number is less than 3, the bending width at the time of decompression may be smaller than that in the above range, and the reduced pressure absorption performance may be reduced. If the number exceeds 36, The width of the

groove portions

14, 14... Is smaller than that in the range, and molding may be difficult.

The

curved portions

13, 13... Are not limited to the shape shown in the figure as long as the

adjacent grooves

14, 14,... Can be restored, but ensure a movable region that can cope with a large change in internal pressure. For this purpose, a shape protruding downward is preferable as in the specific example shown in the figure.

Further, although not shown, an annular recess is formed concentrically from the center of the central portion 12 so as to be recessed inward of the container, and the

curved portions

13, 13... And the

groove portions

14, 14. It is also possible to divide into two. As a result, the movable bottom portion on the outer edge side of the annular recess is less likely to bend than the movable bottom portion on the inner edge side of the annular recess, so that not only the movable bottom portion is prevented from falling too downward, but also the contents cool down. When the inside of the container is depressurized, the fulcrum for the movable bottom to move upward becomes the outer edge of the movable bottom (in the case of providing an annular fulcrum or folded part), the annular fulcrum or the folded part, and the fulcrum moves further upward. It becomes easy. The interval at which the aforementioned annular recesses are arranged concentrically from the center of the central portion 12 is not particularly limited, but an equal interval is suitable.

The groove portion 14 may have a portion that is partially inclined downward in the radial direction of the bottom portion as long as the inner edge of the movable bottom portion 9 is formed so as to be positioned above the outer edge in the container axial direction. .

The folded portion 15 shown in FIG. 6 is formed in an annular shape. However, when the rigidity is insufficient due to a problem such as wall thickness, the folded portion 15 is changed to the curved portion 13 as shown in FIG. It is preferable not to form in the corresponding part, but to form in the part corresponding to the groove part 14 at intervals. Thereby, it can prevent effectively that the inner edge 15a of the folding | turning part 15 falls inward according to a movement of a movable bottom part.

Furthermore, in the specific example shown in the figure, the central portion 12 is formed to be substantially flat, but the central portion 12 may protrude upward or downward. As a result, the central portion 12 can be made thinner, and a greater reduced pressure absorption performance can be exhibited. Further, as described above, the annular protrusion 11 is not necessarily required, but a diameter generated in accordance with the movement of the movable bottom portion 9 is formed by forming the annular protrusion at a portion where the inner edge of the movable bottom portion 9 and the outer edge of the central portion 12 are in contact with each other. It becomes possible to absorb the deflection of the direction.

Furthermore, in the specific example shown in the figure, the outer edge 9a of the movable bottom portion 9 forms a circle, but the shape of the outer edge 9a of the movable bottom portion is not limited to this. That is, the outer edge 9a of the movable bottom portion may be formed by a plurality of straight lines and / or curved lines, and specifically, appropriately changed to a polygonal shape or a petal shape depending on the shape and width of the curved portion and the groove portion. can do. When the outer edge 9a has a polygonal shape, the outer edge 9a serves as a starting point when the movable bottom portion 9 is deformed in the circumferential direction at the time of decompression, and suppresses generation of wrinkles at the outer edge 9a.

It is preferable that the movable bottom portion 9 has an outer diameter of 85 to 95% of the diameter of the grounding portion at the bottom portion, in order to secure the self-supporting property of the container and to ensure the maximum vacuum absorption performance. If the outer diameter of the movable bottom portion 9 is too large, the angle between the movable bottom portion 9 and the inner peripheral wall 8c of the leg portion may become steep and it may be difficult to mold. The central portion 12 preferably has an outer diameter of 20 to 35% of the outer diameter of the movable bottom portion 9.

Further, it is preferable that the circle connecting the tops of the

curved portions

13, 13... Has a diameter of 60 to 90% of the outer diameter of the movable bottom portion 9. If the size of the circle is less than 60% of the outer diameter of the movable bottom 9, the bending width at the time of depressurization becomes smaller than that in the above range, and the depressurization absorption performance may be lowered. If it exceeds 90% of the outer diameter of the bottom 9, the angle with the inner peripheral wall becomes steep as compared with the case where it is in the above range, and there is a possibility that molding becomes difficult.

In the container of the present invention, the thickness of the bottom is preferably equal to or less than the thickness of the thinnest portion of the trunk, and is 0.15 to 0 depending on the diameter of the movable bottom 9. It is desirable that the thickness is reduced to 0.4 mm, preferably 0.2 to 0.3 mm.

Further, in order to suppress the internal falling of the inner peripheral wall 8c of the leg 8, the crystallinity of at least the inner peripheral wall 8c of the leg 8 is preferably 20 to 50%, more preferably 30 to 50%. preferable.

<Manufacturing method>
The container of the present invention can be molded by a conventionally known method for producing a synthetic resin container as long as it has the bottom shape described above, but is preferably molded by a stretch blow molding method. In order to allow the movable bottom 9 to move up and down due to changes in the internal pressure of the container, it is important that the movable bottom 9 is thin. However, stretch blow molding enables the movable bottom 9 to be thin.

In stretch blow molding, a preform made of a thermoplastic polyester resin such as polyethylene terephthalate is prepared and molded using this preform and a bottom mold capable of shaping the bottom shape described above into the container bottom. At this time, since the concave / convex shape composed of the folded portion 15, the

curved portions

13, 13..., The

groove portions

14, 14... Is formed on the bottom portion, in order to improve the releasability of the bottom mold. The bottom mold preferably has a rough surface. Accordingly, even in the molded container, the portions (such as the surface of the movable bottom portion 9 and the surface of the inner peripheral wall 8c of the leg portion 8) that are in contact with the bottom mold are formed to be rough.

For the container of the present invention, thermoplastic polyester resins conventionally used for stretch blow molding, particularly ethylene terephthalate thermoplastic polyesters are advantageously used. Of course, other polyesters such as polybutylene terephthalate and polyethylene naphthalate are used. Or a blend of a polyester resin and a polycarbonate, an arylate resin, or the like can be used.

The container of the present invention may have not only a single layer structure of the thermoplastic polyester resin, but also a multilayer structure of the thermoplastic polyester resin layer and a gas barrier resin or oxygen-absorbing resin layer. .

It is preferable that the mouth portion of the preform used is thermally crystallized in order to provide heat resistance that can withstand hot filling at high temperatures.

Stretch blow molding conditions can be molded under conventionally known conditions as long as a bottom mold capable of imparting the above-described shape to the bottom can be used, and can be molded by two-stage blow molding as well as single-stage blow molding. It is preferable to perform heat setting from the viewpoint of heat resistance.

Thus, the container of the present invention can be produced by appropriately selecting a conventionally known method. However, when the container of the present invention is made of polyester and an annular support having a high degree of crystallinity is provided at the bottom, it is manufactured by single-stage blow molding, which is a conventionally known biaxial stretch blow molding, from the viewpoint of manufacturing with high productivity. It is preferable to do. This will be described in detail below.

In this case, a conventionally known polyester preform can be used as the preform used for molding. Particularly preferably, a bottomed preform made of an ethylene terephthalate-based polyester resin which has been conventionally used for biaxial stretch blow molding can be used.

The ethylene terephthalate-based polyester resin is such that terephthalic acid accounts for 50 mol% or more, particularly 80 mol% or more of the dicarboxylic acid component, and ethylene glycol is 50 mol% or more, particularly 80 mol, of the diol component. It is a polyester occupying a ratio of more than%. Examples of the remaining components include components conventionally used in polyester resins. Specifically, aromatic dicarboxylic acids such as isophthalic acid, phthalic acid and naphthalenedicarboxylic acid; alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid; aliphatic dicarboxylic acids such as succinic acid, adipic acid, sebacic acid and dodecanedioic acid A dicarboxylic acid component consisting of one or a combination of two or more of propylene glycol, 1,4-butanediol, diethylene glycol, 1,6-hexylene glycol, cyclohexanedimethanol, ethylene oxide adduct of bisphenol A, etc. The diol component which consists of 1 type (s) or 2 or more types can be mentioned.

In a preferred method for producing a polyester container having an annular branch having a high degree of crystallinity (hereinafter sometimes referred to as “preferred production method”), the polyester resin should have at least a molecular weight sufficient to form a film. Yes, an injection grade or extrusion grade is used depending on the application. The intrinsic viscosity (IV) is generally in the range of 0.6 to 1.4 dL / g, particularly 0.63 to 1.3 dL / g.

In a preferred manufacturing method, when the preform is biaxially stretch blow-molded using the body mold and the bottom mold, at least the bottom mold 24 is set so that the crystallinity of the annular support is 30% or more. It is important that the temperature of the portion corresponding to the annular support is adjusted to a temperature of 130 to 160 ° C.

FIG. 12 is a diagram for explaining a biaxial stretching blow process for a polyester container having an annular support. The molding die denoted as 21 as a whole is composed of a core die 22 for fixing the mouth portion of the preform 20, body die 23 and 23 composed of a pair of split dies, and a bottom die 24. The preform is heated to the stretching temperature. As is apparent from FIG. 12, the

body molds

23 and 23 form portions corresponding to the shoulder 3 and the body 4 of the container shown in FIG. It has a surface that is adjacent to the mold 24 and is continuous with the surface of the bottom mold 24 that forms a portion corresponding to the ground contact portion 8b together with the outer peripheral wall 8a.

The bottom mold 24 is an outer bottom mold 24a that forms an annular support at the bottom of the polyester container, and is located concentrically with the outer bottom mold 24a inside the outer bottom mold 24a. It consists of a combination with the inner bottom mold 24b to be formed. These are integrally movable in the axial direction. The surface of the outer bottom mold 24a is adjusted to a temperature of 130 to 160 ° C. so that the annular support 16 can be heat-set by contacting with the annular support 16 so that its crystallinity can be 30% or more. Has been. At this time, the inner bottom mold 24b may be configured as a bottom mold 24 integrated with the outer bottom mold 24a, and the bottom mold 24 may be adjusted to a temperature of 130 to 160 ° C. The mold may be adjusted to different temperatures.

When the temperature of the bottom mold 24 is lower than 130 ° C., the crystallinity does not become 30% or more. On the other hand, when the temperature of the bottom mold 24 is higher than 160 ° C., the crystallinity is higher than 30%, but the transparency of the container is lowered, the durability of the mold is lowered, and the production efficiency is lowered.

FIG. 12 (A) is a diagram showing a state before the bottom mold 24 is moved. In this state, the bottom mold 24 is in a position where portions corresponding to the inner peripheral wall 8c of the leg portion and the movable bottom portion 9 are extended below the grounding portion position 23a of the trunk mold. In particular, it is preferable that the outer bottom mold 24a that forms the annular support 16 of the container be lower than the ground contact portion position 23a by the length of the inner peripheral wall 8c. In this state, the preform 20 installed in the molding die is stretched and stretched in the axial direction by the stretch rod 25, and blow air is introduced into the interior to be expanded and stretched in the circumferential direction. The container being molded in this way contacts the surface of the body part mold 23 to form a body wall and extends downward from the grounding part position 23a of the body part mold.

Next, as shown in FIG. 12 (B), the bottom mold 24 is raised in the container axial direction while flowing blow air into the container, so that the container being stretched and molded is completely attached to the bottom mold 24. The portion that contacts and corresponds to the annular support portion 16 comes into contact with the outer bottom mold 24a that is temperature-controlled at the above temperature, and is heat set. A portion corresponding to the inner peripheral wall 8c is formed, and a portion corresponding to the movable bottom portion 9 is formed in a raised bottom shape that rises inward from the grounding portion 8b.

In a polyester container having an annular support, it is preferable that not only the annular support 16 but also the entire shoulder, trunk and bottom are heat set. Therefore, it is preferable that the mold temperature of the body mold 23 is adjusted to the range of 125 to 160 ° C., and the inner bottom mold 24 b is an integral configuration as the bottom mold 24 and the temperature is adjusted. . For both the body mold 23 and the bottom mold 24, the time for the container to contact the mold is preferably in the range of 1 to 3 seconds.

In the preferred manufacturing method, as described above, it is preferable that the movable bottom portion 9 is sufficiently stretched and thinned by biaxial stretch blow molding in order to exhibit the reduced pressure absorption performance by the bottom portion. This makes it possible to easily move up and down due to a change in the internal pressure of the container, starting from the annular support 16 to which crystallization is promoted and rigidity is given.

The preferred manufacturing method is not limited to the above-described embodiment, and various modifications can be made. For example, when the bottom mold 24 is raised after the portion to be the annular support 16 is extended below the grounding portion position 23 a of the body mold 23, the bottom mold 24 is connected to the annular support 16 and the movable bottom 9. Since it rises while contacting, it becomes possible to form the movable bottom 9 and heat set the annular support 16 and the movable bottom 9. Thereby, the part which should become the annular support part 16 of the container being formed contacts the outer mold 24a earlier, the contact time with the outer bottom mold 24a of the part which becomes the annular support part 16 becomes longer, and the annular support part 16 Crystallization can be promoted, and the crystallinity of the annular support 16 can be reliably increased (30% or more).

As shown in FIG. 11, when the annular support 16 has a concave shape recessed inward of the container, the outer bottom mold 24a shown in FIG. 12 is shaped to protrude further upward than the surface of the inner bottom mold 24b. Others may be formed in the same manner. Also in this case, the annular support 16 is maintained by a method of maintaining the temperature of the outer bottom mold 24a at a higher temperature than that of the inner bottom mold 24b, or a method of increasing the contact time between the outer bottom mold 24a and the portion to be the annular support 16. Crystallization can be promoted.

Among the containers of the present invention, a polyester container having an annular branch having a crystallinity of 30% or more will be described in the following experimental example. The molding method and measurement method of the polyester container in each experimental example are as follows.

(Polyester container)
A preform (PF) obtained by injection molding using polyethylene terephthalate (hereinafter referred to as PET) was heated, and a PET bottle was molded under the conditions shown in Table 1 using a single-stage blow molding machine. Other common conditions are shown below.
PF heating temperature: 100 ° C
Blow mold temperature (body): 145 ° C

(Measurement of crystallinity)
A 3 mm × 5 mm section was cut out from the annular support at the bottom of the molded PET bottle, and the crystallinity was measured using a density gradient tube.

(Heat resistance evaluation)
The molded PET bottle was filled and sealed with water heated to 87 degrees. When the leg part of the PET bottle falls inward, the movable bottom part falls below the grounding part. After sealing and cooling, whether the height of the movable bottom part partially falls below the grounding part was visually evaluated. The evaluation criteria are as follows.
The height of the movable bottom is above the ground contact: Good The height of the movable bottom is below the ground contact: Evil

As can be seen from Table 1, it was confirmed that when the crystallinity of the annular support portion was 30% or more, there was no inclination of the inner peripheral wall of the leg portion and a movable bottom portion maintaining heat resistance was formed. It was also confirmed that when the bottom mold temperature is 130 to 160 ° C., it is possible to form a movable bottom having an annular support having a crystallinity of 30% or more. When the bottom mold temperature was lower than 130 ° C., the degree of crystallinity did not reach 30%, the inner peripheral wall of the leg part fell down, and the bottom part protruded from the grounding part. On the other hand, when the bottom mold temperature is higher than 160 ° C., the crystallinity is higher than 30%, but the transparency of the container is lowered, the durability of the mold is lowered, and the production efficiency is lowered. End up. Therefore, the bottom mold temperature is preferably 130 to 160 ° C.

In the container of the present invention, since the vacuum absorption performance is imparted to the bottom that does not affect the container appearance, it can be effectively used as a container for seasonings and the like filled by hot filling. In addition to such contents, the present invention can be applied to contents filled at a relatively high temperature.

1 plastic container, 2 mouth part, 3 shoulder part, 4 body part, 5 bottom part, 6 ribs, 8 leg parts, 8a outer peripheral wall, 8b grounding part, 8c inner peripheral wall, 9 movable bottom part, 9a outer edge of movable bottom part, 11 annular protrusion, 12 central part, 13 curved part, 14 groove part, 14a curved bottom part, 15 folded part, 16 annular support part, 17 leg groove part, 18 heel part, 30 steps.

Claims

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,
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. A synthetic resin container comprising a groove portion connected so as to be positioned.
The synthetic resin container according to claim 1, wherein the grooves are formed radially.
The synthetic resin container according to claim 1 or 2, wherein the groove portion has a curved bottom portion protruding downward.
The synthetic resin container according to any one of claims 1 to 3, wherein a depth of the groove portion is 0.1 to 3.0 mm at a center position between inner and outer edges of the movable bottom portion.
The synthetic resin container according to claim 3 or 4, 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 3 to 5, wherein a radius of curvature R of the curved bottom portion is 30 to 300 mm.
The synthetic resin container according to any one of claims 1 to 6, wherein a width of the groove portion is wider or narrower than a width of the inner and outer edges at a center position between the inner and outer edges of the movable bottom portion.
The synthetic resin container according to any one of claims 1 to 7, wherein an annular projection protruding downward is formed at a boundary between an inner edge of the movable bottom portion and an outer edge of the central portion.
The synthetic resin container according to any one of claims 1 to 8, 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 in alignment with a position of an outer edge of the movable bottom portion. .
The synthetic resin container according to any one of claims 1 to 9, wherein the central portion protrudes upward or downward.
The synthetic resin is polyester;
The inner peripheral wall upper end and the outer edge of the movable bottom are connected by an annular support,
The synthetic resin container according to any one of claims 1 to 8, wherein the crystallinity of the annular support portion by a density method is 30% or more.
The synthetic resin container according to any one of claims 1 to 11, wherein 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 12, wherein a step is formed between an outer peripheral wall of the leg portion and a ground contact portion.
The synthetic resin container according to claim 12 or 13, wherein the center line of the leg groove part is located on a virtual straight line extending from the center line of the groove part of the movable bottom part.
The synthetic resin container according to any one of claims 12 to 14, wherein the number of the leg groove portions and the number of the groove portions of the movable bottom portion are the same.
A polyester container having a vacuum absorbing performance at the bottom, wherein the bottom is formed with an outer peripheral wall that is continuous from the trunk, a leg that includes a grounding portion and an inner peripheral wall, and on the inner side of the inner peripheral wall of the leg, A movable bottom located above the grounding part is formed,
A polyester container having a crystallinity of 30% or more by a density method of an annular support portion connecting the upper end of the inner peripheral wall and the outer edge of the movable bottom portion.
The bottom part is formed with an outer peripheral wall continuous from the trunk 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 inside the inner peripheral wall of the leg part, and the inner part A method for producing a polyester container in which an annular support connecting the upper end of the peripheral wall and the outer edge of the movable bottom is formed,
When the preform is biaxially stretch blow-molded using the body mold and the bottom mold, the portion corresponding to the annular support portion of the bottom mold is adjusted to a temperature of 130 to 160 ° C. A method for producing a polyester container.