JP2004058596A - Method for manufacturing container made of synthetic resin provided with inner rib on bottom part and container manufactured thereby - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a container made of a synthetic resin provided with inner ribs on the bottom part without using a special preform, and a container manufactured by using it. <P>SOLUTION: The container made of the synthetic resin is provided with the inner ribs R on the bottom part b. The inner ribs R are molded by the first biaxially oriented blow molding for molding a plurality of leg parts divided by a plurality of parts radially extending from the center of the bottom part to the trunk part as a blow-molded body by a biaxially oriented blow molding, and by the second biaxially oriented blow molding which brings the inclined faces of the leg parts to each other accompanied with heat shrinkage of this blow-molded body, and brings the inclined faces of the leg parts into close contact with each other or makes them close to each other. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for manufacturing a synthetic resin container having an inner rib at a bottom portion, and a container manufactured using the method.
[0002]
[Prior art]
Conventionally, as a synthetic resin pressure-resistant container containing carbonic acid, etc., a round-bottom container with a separate base cup was used, but recently from the center of the bottom to the trunk, due to problems such as recycling, A petaloid-bottomed container having a plurality of leg portions partitioned by a plurality of radially extending valley portions is mainly used.
[0003]
By the way, since the container at the petaloid bottom is partially grounded by a plurality of legs, the container as a container is not as comfortable as compared to a container having an annular grounding portion, and the appearance is not always preferable. . In the case of a container having a small diameter (for example, φ = 70 mm or less), a so-called champagne base having a recess near the center and having an annular grounding portion around the center, such as a petina can or a ramune container, is used. When a champagne base is to be used for a large container, there is a disadvantage that the strength that can withstand the internal pressure cannot be maintained.
[0004]
On the other hand, the present applicant has already provided a plurality of inner ribs on the inner wall of the preform used for the biaxial stretch blow molding, so that the preform is subjected to the biaxial stretch blow molding to form a synthetic resin container. A technique of forming a plurality of inner ribs on the bottom to improve the internal pressure resistance of the container has been proposed in Japanese Patent Publication No. 63-11212.
[0005]
[Problems to be solved by the invention]
However, in the above technique, the thickness of the inner rib formed on the bottom of the container after blow molding in the container axial direction is smaller than that of the inner rib at the preform stage. There is an inconvenience that the strength obtained from the rib is smaller than the inner rib at the preform stage, and it costs more than using an existing preform because a special preform is used. There was an inconvenience.
[0006]
The problem to be solved by the present invention has been made in view of such a fact, and without using a special preform, a method of manufacturing a synthetic resin container having an inner rib on a bottom portion and a method of manufacturing using the method. To provide a finished container.
[0007]
[Means for Solving the Problems]
In order to solve this problem, the invention according to claim 1 provides a synthetic resin container by subjecting a blow molded article subjected to biaxial stretch blow molding to heat shrinkage by heat treatment and again performing biaxial stretch blow molding. In manufacturing, a plurality of leg portions partitioned by a plurality of valley portions extending radially from the center of the bottom to the body of the blow molded product are formed by a first biaxial stretch blow molding, and the blow molded product is formed by a subsequent heat treatment. Characterized in that the slopes of the leg portions are brought closer to each other with the heat shrinkage of the legs, and then the inner ribs are formed by bringing the slopes of the leg portions into close contact with or closer to each other in a second biaxial stretch blow molding. This is a method for manufacturing a synthetic resin container having an inner rib.
[0008]
The invention according to claim 2 is a synthetic resin container provided with an inner rib on a bottom portion, wherein the inner rib is a plurality of blow molded articles formed by biaxial stretching blow molding and extending radially from the center of the bottom to the body. The first biaxial stretch blow molding for forming a plurality of leg portions defined by valley portions, a heating process for bringing the slopes of the leg portions closer to each other due to the heat shrinkage of the blow molded body, and the slopes of the leg portions being adhered to each other Alternatively, it is characterized by being molded through a second biaxial stretch blow molding approaching.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described more specifically with reference to the drawings.
FIG. 1 is a partial cross-sectional view showing an existing preform 10 made of polyethylene terephthalate (PET) used in the manufacturing method according to the present invention.
[0010]
The preform 10 is an existing preform molded using, for example, ordinary injection molding, and includes a mouth portion 11 and a main body portion 12. In the case where heat resistance is required, the mouth portion 11 can be appropriately subjected to whitening treatment so as to be thermally crystallized in advance so as not to cause thermal deformation.
[0011]
In the production method of the present invention, the bottle-shaped container 1 is produced by heat-treating the blow-molded article subjected to biaxial stretch blow molding using the preform 10 to thermally shrink it, and then performing biaxial stretch blow molding again. .
[0012]
FIGS. 2A and 2B are a side view and a bottom view, respectively, of a blow molded body 20 obtained by biaxially stretch blow molding the preform 10 by the manufacturing method according to the present invention.
[0013]
In the first biaxial stretch blow molding, the preform 10 is heated to a temperature range of 70 to 130 ° C. (preferably 90 to 120 ° C.) at which a blow effect can be obtained, and the mold temperature is set to 50 ° C. The biaxially stretched blow molding is performed on the blow molded body 20 by heating to about 230 ° C. (preferably 70 to 180 ° C.). As shown in FIG. 2, this blow-molded body 20 has a petaloid-bottomed bottle-type having a plurality of leg portions 22 divided by five valley portions 21 extending radially from the center of the bottom portion 20a to the body portion 20b of the blow-molded body 20. It becomes.
[0014]
FIGS. 3A and 3B are a partial cross-sectional view and a bottom view of the blow molded body 20 that has been subjected to a heat treatment and a heat contraction, respectively.
[0015]
In the heat treatment, the blow molded body 20 is taken out of the primary mold and then heat shrunk in a temperature range of 110 to 225 ° C (preferably 130 to 200 ° C). Thereby, as shown in FIG. 3, the slopes 22f of the leg portions 22 approach each other due to the thermal shrinkage of the blow molded body 20, and the slopes 22f come into contact with or close to each other.
[0016]
4A and 4B are a partial cross-sectional view and a bottom view of the bottle-type container 1 obtained by biaxially stretch-blow-molding the blow-molded body 20 shrunk by the heat treatment, respectively.
[0017]
In the second biaxial stretch blow molding, the contracted blow molded body 20 is biaxially stretch blow molded to the bottle-type container 1 at a mold temperature of 60 to 170 ° C (preferably 80 to 150 ° C). As a result, the slopes 22f of the leg portions 22 come into close or close contact with each other as the blow molded body 20 expands again, and become functionally one inner rib R.
[0018]
In particular, as shown in FIG. 4, the bottle-type container 1 of the present embodiment is blow-molded so that the bottom b has a recess b1 near the center and the periphery thereof is a champagne base having an annular grounding portion b2. The leg portions 22 that are in close contact with or close to each other constitute an annular or substantially annular ground portion b2, and a plurality of ribs R are formed inside the container 1 along the annular or substantially annular ground portion b2.
[0019]
According to the manufacturing method according to the present invention, the existing preform 10 is diverted to biaxially stretch blow-molding of the petaloid-bottomed blow-molded body 20 having the leg portions 22 partitioned by the five valley portions 21, After the slopes 22f of the leg portions 22 are brought close to each other by heat shrinkage, a plurality of inner ribs R are formed by making the slopes 22f of the leg portions 22 come into close contact with or close to each other by performing biaxial stretch blow molding again. Also, compared to the conventional manufacturing method using a preform provided with an inner rib in advance, the thickness of the inner rib after blow molding in the container axial direction can be easily increased to increase the strength.
[0020]
Further, according to the manufacturing method according to the present invention, since the manufacturing is performed using the existing preform 10 without using a special preform, the bottle type container 1 having the inner rib R at the bottom can be manufactured at low cost. . In addition, according to the manufacturing method of the present invention, since the blow molded body 20 is heated and shrunk, the heat resistance of the bottle-type container 1 against heat shrinkage can be improved.
[0021]
Furthermore, according to the bottle-type container 1 manufactured by the above method, since a plurality of inner ribs (beams) R enter the annular or substantially annular grounding portion b2, a conventional champagne base is adopted as the bottom 1b of the container 1. As compared with the case, the strength against the internal pressure can be increased. Moreover, in the bottle-type container 1, the thickness of the annular or substantially annular grounding portion b2 can be reduced by the increased strength due to the inner rib R, so that the weight of the container 1 can be reduced.
[0022]
For this reason, for example, in the case of a container having a conventional champagne base, it is necessary to set the thickness of the grounding portion to 1.2 mm or more. It is difficult to adopt it only to containers below the container (American size bottle type container), and it is not suitable for the so-called Paste Rise bottle that pasteurizes contents such as fruit juice and carbonic acid and fills it.
In the bottle-shaped container 1 manufactured according to the present invention, since the annular grounding portion b2 is provided with the champagne base having the plurality of inner ribs R, the champagne base is adopted for the American-sized bottle-shaped container which has been difficult in the past. At the same time, it can be used as a pastelize bottle with high internal pressure resistance.
[0023]
In addition, since the bottle-type container 1 is heat-treated in its manufacture, the heat-resistance against heat shrinkage at high temperatures is improved as compared with a conventional bottle-type container having an inner rib at the bottom, so that the container can be used as a heat-resistant container. Can be used.
[0024]
What has been described above merely shows preferred embodiments of the present invention, and those skilled in the art can make various modifications within the scope of the claims.
For example, in the present embodiment, the bottom b of the bottle-type container 1 is formed so as to be a champagne base, but the external shape of the bottom is appropriately changed by biaxial stretch blow molding using various molds. it can. Further, the container obtained by the biaxial stretch blow molding is not limited to a bottle type container, and can be applied to containers having various shapes.
[0025]
【The invention's effect】
Therefore, according to the manufacturing method of the present invention, a blow molded body having a plurality of legs partitioned by a plurality of valleys is biaxially stretch blow-molded by diverting an existing preform, and subsequently, a slope of the legs is formed. Are brought close to each other by a heat treatment, and then a plurality of inner ribs are formed by applying the biaxial stretch blow molding again to bring the slopes of the leg portions into close contact with or closer to each other. The thickness of the inner rib after blow molding in the container axial direction can be easily increased to increase the strength, as compared with the conventional manufacturing method using the above method.
[0026]
Further, according to the production method of the present invention, since the production is performed using an existing preform without using a special preform, a synthetic resin container having an inner rib at a bottom can be produced at low cost. In addition, according to the manufacturing method of the present invention, since the blow-molded body is heated and shrunk, the heat resistance of the synthetic resin container against heat shrinkage can be improved.
[0027]
Furthermore, according to the synthetic resin container manufactured by the manufacturing method according to the present invention, since a plurality of inner ribs (beams) enter the annular grounding portion, compared to a case where a conventional champagne base is adopted as the bottom of the container. Thus, the strength against internal pressure can be increased. Moreover, in the synthetic resin container, the thickness of the annular grounding portion can be reduced by the increased strength due to the inner rib, so that the container can be reduced in weight.
[Brief description of the drawings]
FIG. 1 is a partial cross-sectional view showing an existing preform made of a PET resin used in a manufacturing method according to the present invention.
FIGS. 2 (a) and 2 (b) are a side view and a bottom view, respectively, of a blow molded article obtained by biaxially stretch blow molding a preform by the production method according to the present invention.
FIGS. 3 (a) and 3 (b) are a partial cross-sectional view and a bottom view of a heat-shrinkable blow molded article, respectively.
FIGS. 4A and 4B are a partial cross-sectional view and a bottom view of a bottle-shaped container obtained by biaxially stretch-blow-molding a blow-molded article shrunk by a heat treatment, respectively.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Synthetic resin container 11 Mouth part 12 Body part 20 Blow molded body 20a Bottom part 20b Trunk part 21 Valley part 22 Leg part 22f Slope b1 Depression b2 Ring-shaped or substantially ring-shaped ground part R Inner rib

Claims (2)

In producing a synthetic resin container by subjecting the blow molded body subjected to biaxial stretch blow molding to heat treatment and heat shrinkage, and then performing biaxial stretch blow molding again,
In the first biaxial stretch blow molding, a plurality of leg portions partitioned by a plurality of valley portions extending radially from the bottom center to the body portion of the blow molded body are formed, and the heat of the blow molded body by a subsequent heat treatment is formed. After the slopes of the leg portions are brought closer to each other with shrinkage, the inner ribs are formed by bringing the slopes of the leg portions into close contact with or closer to each other in a second biaxial stretch blow molding. A method for producing a synthetic resin container having an inner rib. A synthetic resin container having an inner rib on a bottom,
A first biaxial stretch blow molding for forming a plurality of leg portions defined by a plurality of valley portions extending radially from a bottom center to a body portion as a blow molded body formed by biaxial stretch blow molding; And a heat treatment for bringing the slopes of the leg portions closer together with the heat shrinkage of the blow molded body, and a second biaxial stretch blow molding for bringing the slopes of the leg portions close to or closer to each other. A synthetic resin container having an inner rib at a bottom portion.

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