JPH11300815A - Blow-molded container - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress an influence to be inflicted by the shrinkage over time of a bottom part to the bottom sealed part of a blow-molded plastic container which is peeled after lamination, and harden and stabilize the contact-bonding of the bottom sealed part and further increase the contact-bonding strength of the bottom sealed part, according to necessity. SOLUTION: A bottom sealed part 12 molded in a protruding stip shape of the blow-molded plastic container which is peeled after lamination is constructed of a main part bottom rib 14 with a thick wall and a leg rib 17 with a thin wall which forms a connection part to a bottom wall 9. The leg rib 17 hinders the fluidity of a material during molding, so that the bottom sealed part 12 is molded in such a state that a sufficiently high pressing force is caused to act upon the bottom sealed part 12. Consequently, the outer layer 2 and the inner layer 3 of the bottom sealed part 12 are contact-bonded forcefully and thereby the influence to be caused by the shrinkage over time of the bottom part is prevented from spreading in such a direction that the development of bottom cracks is promoted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a bottom sealing portion of a blow-molded laminated exfoliated plastic container.

[0002]

2. Description of the Related Art A blow-molded bottle generally called a delami bottle is constructed by laminating an outer layer having high self-shape holding ability and an inner layer in a flexible shape in a state of being easily peeled off. Laminated release plastic containers are known.

[0003] The blow-molded laminated exfoliated plastic container is obtained by extruding an outer layer parison and an inner layer parison having almost no compatibility into a laminated parison by co-extrusion, and blow molding the laminated parison. Since the bottom seal part crushed and formed by the pinch-off part of the mold basically has a laminated structure of an outer layer part and an inner layer part having almost no compatibility, there is dissatisfaction that bottom cracks easily occur in the outer layer part. there were.

As a conventional technique for solving this dissatisfaction, a bottom seal portion formed by being flatly crushed and formed by a pinch-off portion of a blow mold is formed by projecting a pair of rib pieces by polymerization and pressing to form a ridge along a parting line. There is a technique (see Japanese Patent Application Laid-Open No. Hei 8-216238) in which a plurality of biting portions are formed on the protruding ridge-shaped object, and the biting portion cuts from one of the pair of rib pieces to the other.

In this prior art, the bottom seal portion is formed in a ridge shape having a height width, so that the pressure-bonding area between the outer layer and the inner layer in the bottom seal portion is increased, and a plurality of biting portions are provided. In addition to further increasing the crimping area between the outer layer and the inner layer, the resistance to the shearing force parallel to the crimping surface is drastically increased, thereby obtaining a bottom seal with high mechanical strength, which is unlikely to cause bottom cracks. Is possible.

[0006]

However, in the above-described prior art, bottom cracks may occur in the bottom seal portion due to the shrinkage of the bottom portion with time after the completion of blow molding of the container. In the case of the container described above, there is a problem that a bottom crack often occurs when the container is filled with the content liquid and dropped or subjected to impact.

Also, by forming a plurality of biting portions, the press-bonding area between the outer layer and the inner layer in the bottom seal portion surely increases. The increase in the crimping strength is limited to the increase in the crimping area.
There is a problem that the demand for further increasing the crimping strength of the bottom seal cannot be satisfied.

Further, by increasing the thickness of the bottom seal portion,
It is possible to obtain a large bite amount of the bite portion, increase the crimping area and increase the resistance to the shearing force along the crimping surface, but almost in proportion to the thickness of the bottom seal portion,
The influence of the shrinkage of the bottom over time after the blow molding is completed appears strongly, and the bottom cracks are easily generated.Therefore, the thickness of the bottom seal is increased, and the bottom seal has a compression strength and a resistance to shearing force. However, there is a problem that means for simply increasing the mechanical strength cannot be adopted.

Accordingly, the present invention has been made to solve the above-mentioned problems in the prior art, and it is a technical object of the present invention to suppress the influence of the temporal shrinkage of the bottom portion after the completion of blow molding on the bottom seal portion. Accordingly, an object of the present invention is to make the press-fitting of the bottom seal portion strong and stable, and to increase the press-fitting strength of the bottom seal portion as necessary.

[0010]

Means for Solving the Problems Among the present invention for solving the above technical problems, the means according to the first aspect of the present invention is a blow-molded laminated exfoliated plastic container, and has an intake hole in an upper outer layer. Opening, forming the bottom seal part of the bottom part crushed flat by the pinch-off part of the blow mold into a ridge shape by polymerizing and pressing a pair of rib pieces. , A bottom rib which is a main part,
The bottom rib is connected to the bottom wall.The bottom rib is made up of a thinner leg rib than the bottom rib. To arrange.

[0011] The bottom seal portion, which is formed into a ridge shape by polymerizing and pressing a pair of rib pieces, has a wall structure in which an outer layer, an inner layer, an inner layer, and an outer layer are laminated in this order along the pressing direction. Because of the ridge structure having a width, the ridge structure has a large press-bonding area, so that a large press-bonding strength is exhibited even between the outer layer and the inner layer having low weldability.

The bottom rib is formed in combination with the bottom rib, and the leg rib forming the connecting portion with the bottom wall of the bottom seal is thinner than the bottom rib. However, since a pair of rib pieces are formed by crushing flat by crushing the pair of rib pieces firmly, the thickness of the bottom rib, which is the main part of the bottom seal portion, is not large, and therefore the thickness of the leg ribs is not large. The wall thickness is sufficiently small as long as a mechanically connected state with the bottom wall of the bottom seal portion can be stably secured.

As described above, the bottom rib, which is the main part of the bottom seal portion, and the leg rib connecting the bottom wall have a small thickness.
Since the wall thickness is small, it is easy to bend and deform, so that the influence of the temporal shrinkage of the bottom wall after the blow molding is completed is absorbed by the bending and prevented from being transmitted to the bottom rib. Hold the crimp.

[0014] In addition, since the thickness of the leg ribs is small,
The pinch-off portion of the blow mold for molding the leg ribs acts as a weir against the flow of the plastic material molded on the bottom ribs, thereby reducing the mold clamping force of the blow mold. Effectively works for crimping of parts.

The biting portion formed in the bottom rib has a structure in which one rib piece bites into the other rib piece, so that the overlapping surface of the outer layer and the inner layer in the bottom rib becomes uneven at the biting portion. As a result, the overlapping area is increased to increase the pressure bonding strength, and the resistance to the shearing force parallel to the main portion of the pressure bonding surface is increased.

Further, since the biting portion is formed by local pressing deformation of the bottom rib due to a strong pressing force, a strong pressing force acts on the bottom rib portion near the biting portion. The inner layer is strongly pressure-bonded, and exhibits a strong pressure-bonding strength.

Further, since the bottom rib, which is the main part of the bottom seal portion, is connected to the bottom wall through thin leg ribs, even if the bottom rib is made thicker, the bottom rib is not damaged. There is almost no possibility that the effect of the temporal shrinkage that occurs will act to facilitate the occurrence of bottom cracks in the bottom seal portion, thereby increasing the thickness of the bottom rib and mechanically controlling the bottom seal portion with respect to the bottom wall. It is possible to enhance the reinforcing rib function.

According to a second aspect of the present invention, in addition to the first aspect, the biting direction of the biting portion is alternately reversed.

According to the second aspect of the present invention, since the biting directions of the adjacent biting portions are opposite, the outer layer and the inner layer near the biting portion are strongly pulled and greatly extended and deformed at the time of forming the biting portion. As a result, the press-bonded area between the outer layer and the inner layer is increased, and the outer layer and the inner layer are pressed more strongly, whereby the press-bonding strength of the entire bottom seal portion is increased.

Further, since the biting portion is alternately located on the opposite side to the main portion of the crimping surface, the rib portions are engaged with both sides of the main portion of the crimping surface by the plurality of biting portions. The connection of the rib pieces is structurally enhanced.

According to a third aspect of the present invention, in addition to the first aspect of the present invention, the bottom wall portion where the bottom seal portion is continuously provided is formed inward along a long diameter along a parting line where the bottom seal portion is located. It is a curved, substantially elliptical arc-shaped wall-shaped raised portion, and the bottom seal portion is formed in an arch shape curved along the elliptical spherical surface of the raised portion.

According to the third aspect of the present invention, the thick protruding portion is formed into an elliptical spherical wall shape whose major axis is along the parting line, so that the direction of the temporal shrinkage of the bottom wall after the mold release is obtained. However, the direction becomes orthogonal to the parting line, so that the influence of the shrinkage of the bottom wall with time hardly acts on the bottom seal portion in the direction of generating the bottom crack.

Further, the raised portion is formed into a thick dome shape in the shape of a thick elliptical arc wall, and the bottom seal portion is formed into an arch structure along the raised portion, so that the bottom wall sags due to a change with time, that is, It prevents the central part of the bottom wall from swelling downward and keeps the proper structure of the bottom part.

[0024]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a front view, FIG. 2 is a side view, and FIG. 3 is a bottom view of a container 1 according to the present invention. The container 1 is made of a synthetic resin material such as polyethylene or polypropylene and has a necessary self-shape holding ability. The molded outer layer 2 and the inner layer 3 formed of a flexible plastically deformable bag-shaped plastic resin material having low compatibility with the outer layer 2 such as nylon, eval, and polyethylene terephthalate (see FIG. 2). It is a blow molded container.

The body 4 of the container 1 has a cylindrical shape. The body 4 is erected at the upper end of the body 4 and has a thread on the outer peripheral surface. An intake hole 6 for introducing outside air between the outer layer 2 and the inner layer 3 is provided, and a bottom 7 having a circular bottom wall 9 is continuously provided at the lower end of the slightly enlarged body 4. I have.

The bottom portion 7 (see FIGS. 3 and 4) includes a peripheral leg wall 8 constituting a leg portion of the container 1 and a bottom wall 9 surrounded by the leg wall 8 and depressed in the container 1. And a bottom seal portion 12 integrally connected to the bottom wall 9 and located on the parting line and crossing the bottom wall 9.

The leg wall 8 (see FIG. 4) has a structure in which an outer substantially upright cylindrical wall portion and an inner lower portion of a tapered cylindrical wall portion whose diameter is expanded downward are connected in an arc shape. The bottom wall 7 (see FIG. 3 and FIG. 4) has a flat plate-shaped portion 10 continuous with the inner peripheral edge of the leg wall 8 and a central portion of the flat portion 10 traversing the parting line along the parting line. It has a generally elliptical spherical arc-shaped dome structure along the parting line, and includes a thick raised portion 11 which is curved and depressed inside the container 1.

Bottom seal portion 12 (see FIGS. 3, 4 and 5)
Is located across the center of the raised portion 11 of the bottom wall 9 with both ends extending to the tapered cylindrical wall portion of the leg wall 8, and is a parison blow-molded into the container 1. Are flattened from the front and rear, and a pair of rib pieces 13 obtained by polymerizing and pressing as they are is formed into a ridge shape.

The bottom seal portion 12 is composed of a slightly thin leg rib 17 forming a connecting portion with the raised portion 11 and a thick bottom rib 14 forming a main portion. 14 has a recessed hole 16 forming a biting portion 15 that bites from one rib piece 13 to the other rib piece 13.
However, the ribs 13 are formed in a row with a depth greater than the thickness of the rib pieces 13 and the direction of depression is alternately reversed.

As described above, since the bottom seal portion 12 has a structure in which the thick bottom rib 14 is connected to the raised portion 11 by the slightly thin leg ribs 17, the concave hole 16 is formed. At the same time, the material displaced by the recess 16 is
It is difficult to move to the ridge 11 side through the portion, so that the pressure at the bottom rib 14 is increased, and the crimp strength between the outer layer 2 and the inner layer 3 at the bottom rib 14 is increased. The compression strength of the outer layer 2 and the inner layer 3 at the biting portion 15 located on the molding direction side is extremely high.

The bottom seal portion 12 has an arch shape which is entirely curved along the elliptical spherical arc surface of the protruding portion 11, and the center of the bottom wall 9 due to temporal shrinkage deformation after completion of blow molding. The occurrence of sagging deformation of the part is reliably prevented.

[0032]

Since the present invention has the above-described structure, the following effects can be obtained. Forming a bottom seal portion, a bottom rib serving as a main portion, and a connection portion with a bottom wall of the bottom,
It is composed of leg ribs that are thinner than the bottom rib, and when the bottom seal portion is crushed and formed, the leg rib portion starts to be pressed before the bottom rib portion, so that the material of the bottom rib portion is It becomes difficult to escape to the wall side, so that the bottom seal part will be molded with a strong molding pressure, and the outer layer and the inner layer of the bottom seal part will be strongly pressed together, the crimp strength will be sufficiently large, It is possible to reliably obtain a bottom portion where no bottom crack occurs.

The biting portion is formed by the concave molding of the concave hole. At the time of the concave molding of the concave hole, the material of the bottom rib portion where the concave hole is molded is difficult to move to other parts.
For this reason, the biting portion is formed with a large pressing force, so that the biting portion not only increases the press-bonding area between the outer layer and the inner layer in the bottom seal portion, but also press-fits the outer layer and the inner layer at the biting portion. The strength has been dramatically increased.

Since the leg rib, which is a portion connected to the bottom wall of the bottom seal portion, is thinner than the bottom rib, it is structurally apt to be flexibly deformed accordingly. The effect of the shrinkage of the bottom wall over time on the bottom seal part is absorbed by the flexural deformation of the leg ribs, and is not transmitted to the bottom rib, which is the main part of the bottom seal part. And make sure it is maintained.

According to the second aspect of the present invention, since the recessed directions of the adjacent recessed holes are reversed, the two rib pieces are engaged with each other by meshing with each other, and the outer layer and the inner layer at the biting portion are engaged with each other. Is increased, and the area of the crimp between the outer layer and the inner layer at the bottom seal portion is increased, so that the crimp strength between the outer layer and the inner layer at the bottom seal portion is further increased.

According to the third aspect of the present invention, the bottom wall portion to which the bottom seal portion is continuously formed is a thick raised portion. In addition to reducing the action in the direction that causes bottom cracks in the part, the raised part is made into a wall structure that is curved and depressed into an elliptical arc wall shape, and the bottom seal part has an arched structure along this raised part. As a result, the central portion of the bottom wall does not bulge downwardly due to shrinkage with time after the completion of the blow molding, so that proper molding of the container can be reliably obtained.

[Brief description of the drawings]

FIG. 1 is an overall front view showing an embodiment of the present invention.

2 is an overall side view, partially broken away, of the embodiment shown in FIG. 1;

FIG. 3 is an overall bottom view of the embodiment shown in FIG. 1;

FIG. 4 is an enlarged vertical sectional front view of a bottom portion of the embodiment shown in FIG. 1 at a position slightly deviated from a parting line.

FIG. 5 is an enlarged vertical sectional side view of a main part of the embodiment shown in FIG. 1, showing details of the structure of the bottom seal portion.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1; Container 2; Outer layer 3; Inner layer 4; Trunk 5; Mouthpiece 6; Inlet 7; Bottom 8; Leg wall 9; Bottom wall 10; Flat portion 11; Raised portion 12; 14; bottom rib 15; biting portion 16; concave hole 17; leg rib

Claims (3)

[Claims] 1. A blow-molded laminated exfoliated plastic container, wherein an air inlet (6) is opened in an upper outer layer (2),
The bottom seal part (12) of the bottom part (7) formed by being flattened and crushed by the pinch-off part of the blow mold is connected to a pair of rib pieces (1).
3) is formed into a ridge shape by polymerizing and press-bonding, and the bottom rib (14) forming a connecting portion between the bottom rib (14) as a main portion and the bottom wall (9) of the bottom (7). Leg ribs thinner than) (17)
A blow-molded container comprising: a bottom rib (14); and a biting portion (15) that bites from one side of the pair of polymerized rib pieces (13) to the other in a row at substantially equal intervals. 2. The blow-molded container according to claim 1, wherein the biting directions of the biting portions are alternately reversed. 3. A bottom wall (9) portion on which a bottom seal portion (12) is continuously provided is substantially inwardly curved along a major axis along a parting line where the bottom seal portion (12) is located. An elliptical arc-shaped wall-shaped thick raised portion (11), and the bottom seal portion (12) is formed in an arch shape curved along an elliptical spherical arc surface of the raised portion (11). 3. The blow molded container according to 2.