JP4393731B2 - Synthetic resin container with excellent shape retention - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention is intended to effectively avoid the deterioration of the shape resulting from the thinning of the container for the synthetic resin container filled with the relatively high temperature contents.
[0002]
[Prior art]
Synthetic resin containers such as PET bottles are lightweight and easy to handle, and they can ensure transparency and have an appearance that is comparable to glass containers. In recent years, it has been widely used as a container for filling foods, beverages, cosmetics, drugs, and the like.
[0003]
By the way, the container made of synthetic resin has a low strength against heat. Especially for a container made of PET resin (polyethylene terephthalate resin), the temperature of the contents at the time of filling is about 85 to 87 ° C. In the case of filling the contents having a temperature exceeding 5,000, it is inevitable that the container is deformed by heat shrinkage.
[0004]
In this regard, for example, a technique disclosed in Japanese Examined Patent Publication No. 7-67732 is known in which the heat resistance of the container is improved by performing biaxial stretch blow molding at least twice with a heat treatment step interposed therebetween. The allowable filling temperature of the contents tends to be increased. However, when this type of container is used to reduce the amount of resin used (weight reduction) (for example, when the amount of resin used in a 2-liter container is reduced from 69 g to 55 g or less) ) Due to the weight of the contents (water head pressure) and the heat of the contents, the lower region of the body of the container cannot be projected and the initial shape cannot be maintained as shown in FIG.
[0005]
In order to maintain the appearance of the container, it is effective to form a horizontal rib on the body of the container. However, because the container is thin, the rib may warp due to the effect of heat. Has not yet been made effective.
[0006]
[Problems to be solved by the invention]
SUMMARY OF THE INVENTION An object of the present invention is to propose a container structure with good shape retention that can maintain an initial shape even when the thickness is reduced with respect to a synthetic resin container having improved heat resistance.
[0007]
[Means for Solving the Problems]
The present invention is a synthetic resin container provided with a reduced pressure absorption panel in the body portion and subjected to biaxial stretch blow molding,
In the body portion of the synthetic resin container , a reinforcing lateral rib is provided across the vacuum absorbing panel,
It is a synthetic resin container excellent in shape retention, characterized in that a recess having the same level as the container surface is provided in the central area of the lateral rib .
[0008]
The lateral rib is preferably formed so as to protrude toward the inside of the body of the container during blow molding.
[0009]
The container having the above-described configuration can be provided with a vertical rib that protrudes toward the inside of the trunk portion (to ensure rigidity) in order to prevent deformation when the container is gripped . It is desirable to form the vertical rib as a recessed portion lower than the surface of the body portion of the container.
[0010]
Moreover, it is preferable that the synthetic resin container has a quadrangular cross section having a vertically long concave or convex column extending along the axis of the container at at least four locations around the trunk.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described more specifically with reference to the drawings.
FIG. 1 shows a container of a synthetic resin bottle shape (rectangular shape) according to the present invention, and FIG. 2 shows an AA cross section in FIG.
[0012]
In the figure, reference numeral 1 denotes a container body, and 2 denotes a mouth part integrated with the container body 1.
Reference numeral 3 denotes a groove portion for increasing the rigidity of the container by dividing the container body 1 into upper and lower parts, and 4 is a vacuum absorbing panel. The reduced pressure absorption panel 4 has a function of preventing the shape of the container from being deformed due to the volume change accompanying the cooling of the contents.
[0013]
Reference numeral 5 denotes a reinforcing lateral rib formed so as to cross the vacuum absorption panel 4 in the container body, and the lateral rib 5 has a surface of the container body in the central area (longitudinal central area). And a recess 5a having the same level .
[0014]
6 is a reinforcing vertical rib disposed between the lateral ribs 5, and 7 is a column formed at four locations around the trunk, and this column 7 is a vertically long extending along the axis P of the container. An example having a concave-shaped concave surface 7a is shown.
[0015]
Single biaxially oriented synthetic resin container molded by blow molding or, for example, as disclosed in KOKOKU 7-67732 and JP-molded by at least twice the biaxial stretch blow molding sandwiching the heat treatment Resin used per container in a container made of synthetic resin (residual stress in the main body of the container is extremely reduced and the resin density is high and the strength against heat from the outside is increased) When the thickness is reduced to reduce the amount, the horizontal ribs warp due to the weight of the contents (water head pressure) and the heat they hold even if the horizontal ribs are provided to ensure the shape retention of the container ( Since it deforms plastically, it does not return to its original state even after the contents are cooled.), The appearance of the container is deteriorated. In the container according to the present invention, since the concave portion 5a provided in the horizontal rib 5 is at the same level as the surface of the container, the entire horizontal rib 5 is prevented from warping, and the container maintains its initial shape. Further, the lateral rib 5 effectively exhibits its function, and the rigidity of the container is kept high.
[0016]
The lateral ribs 5 are preferably arranged along the width direction so as to cross the vacuum absorbing panel 4.
[0017]
In the above FIG. 1, an example is shown in which both ends of the lateral ribs 4 have lengths that reach the pillars 7 respectively. It is desirable to make the length not reachable.
[0018]
The pillar 7 is provided with a U-shaped concave surface 7a or a round-shaped convex surface 7a so that the column 7 is not easily buckled when a load is applied from the upper portion or the lower portion of the container.
[0019]
Vertical ribs 6 can be provided between the horizontal ribs 5 adjacent to the pillars 7. When such vertical ribs 6 are provided, the container is always constant even when the container is deformed by the load when the container is gripped. The location (in the present embodiment, the end portion direction of the lateral rib 5) is deformed, and when the load related to the deformation is released, the original shape (initial shape) is restored immediately, so that the so-called container deformation repeatability is achieved. improves.
[0020]
FIG. 3 shows another structural example of the synthetic resin container according to the present invention. In this example, the periphery of the vertical rib 6 is formed as a concave portion 8 lower than the surface of the body of the container, and the contour shape of the vertical rib 6 at the time of forming the container is raised. In addition to further enhancing the reinforcing effect, the end of the lateral rib 4 is shortened so as not to reach the column 7. According to such a configuration, the buckling strength is further increased in the container having a square cross section, and the repeatability of the deformation of the container is further improved.
[0021]
In forming a container using polyethylene terephthalate resin as a resin by applying two biaxial stretch blow molding methods sandwiching heat treatment, the following procedure is followed.
[0022]
First, a preform obtained by extrusion molding or injection molding is heated to, for example, 70 to 130 ° C., more preferably about 90 to 120 ° C., which can exhibit a distraction effect. And 50-230 ° C., more preferably 70-180 ° C., stretched surface magnification 4-22 times (more preferably 6-15 times, oversize about 1.2-2.5 times larger than the finished product in capacity) The first biaxial stretch blow molding is performed under the following conditions.
[0023]
Next, the obtained blow-molded product is subjected to a forced heat treatment for shrinking to about 0.60 to 0.95 times from the finished product at 110 to 255 ° C., more preferably 130 to 200 ° C. Then, the second biaxial stretch blow molding is performed in the temperature range of 60 to 170 ° C., more preferably 80 to 150 ° C. Of course, the container according to the present invention can be molded by one biaxial stretch blow molding regardless of the above conditions.
[0024]
【The invention's effect】
According to the present invention, in a resin container having excellent heat resistance, high shape retention can be maintained even when the container is thinned to reduce the amount of resin used.
[Brief description of the drawings]
FIG. 1 is a side view of a synthetic resin container according to the present invention.
FIG. 2 is a view showing a cross section AA in FIG. 1;
FIG. 3 is a view showing another configuration example of the synthetic resin container according to the present invention.
FIG. 4 is a view showing a main part of a conventional synthetic resin container.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Container body 2 Mouth part 3 Groove part 4 Pressure-reduction absorption panel 5 Horizontal rib 5a Recessed part 6 Vertical rib 7 Column 7a V-shaped concave surface 8 Recessed part P Axis center

Claims (6)

It is a synthetic resin container provided with a vacuum absorption panel in the body part and subjected to biaxial stretch blow molding,
In the body portion of the synthetic resin container , a reinforcing lateral rib is provided across the vacuum absorbing panel,
A synthetic resin container excellent in shape retention, characterized in that a concave portion having the same level as the container surface is provided in the central region of the lateral rib . The synthetic resin container according to claim 1, wherein the lateral rib protrudes toward the inside of the body portion of the container. The synthetic resin container according to claim 1 or 2, wherein the synthetic resin container is provided with a vertical rib protruding toward the inside of the trunk portion. The synthetic resin container according to claim 3, wherein the vertical rib has a recessed portion whose periphery is lower than the surface of the body portion of the container. The synthetic resin container is formed of a rectangular cross section having a vertically long concave surface or a convex column extending along the axis of the container at at least four locations around the trunk portion. The synthetic resin container described. 6. The synthetic resin container according to claim 5, wherein the lateral rib has a length such that both ends thereof do not reach the pillar.

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