JPH07112856B2 - Container with dent panel with reinforcing ribs - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a hollow blow-molded container made of a biaxially stretched thermoplastic material, and particularly to a thin-walled plastic formed into a shape corresponding to partial evacuation without adversely affecting the appearance. It concerns a container.

Metered, thin-walled containers made of thermoplastic materials such as polyester resins and thermoplastic polymers containing at least 50% by weight of monomers containing polymerized nitrile groups (hereinafter referred to as nitriles) are well known in the container industry. Has been. For example, polyethylene terephthalate (hereinafter referred to as PET)
Has a wide range of applications in the field of containers for foods, air fresheners, cosmetics, beverages and the like.

PET can be molded into a transparent, thin-walled container having high hardness, high impact strength, high molding accuracy, and high hygiene by stretch blow.

When the parison is stretched in the horizontal and vertical directions in a temperature range suitable for biaxial stretching by the biaxial stretching blow molding method, it is possible to mold a transparent and heat resistant container having high impact resistance.

Nitrile and heat-set PET containers have particularly high heat resistance. The biaxially stretch blow molded container has improved hardness and strength, as well as improved gas barrier properties and transparency.

When a container of thermoplastic material is filled with a hot liquid (such as a liquid that has been sterilized at high temperature) and sealed, cooling causes the liquid to shrink, resulting in partial vacuuming or decompression of the container and the wall of the container. Is often deformed. Backflow in the filling mechanism and the use of vacuum filling equipment in filling operations likewise may result in partial vacuuming or depressurization inside the container, resulting in deformation. Such deformations are usually concentrated in areas of the container where mechanical strength is weak, often resulting in an irregular and unacceptable appearance container.

Furthermore, if deformation occurs in the part where the label is attached to the container,
As a result of container deformation, the label's appearance will also be adversely affected.

If the wall thickness of the container is increased, it is possible to strengthen the wall of the container to some extent and thereby reduce the decompression deformation effect. However, increasing the wall thickness results in a significant increase in the amount of raw material required to produce the container and a significant reduction in production rate. The resulting increase in cost is not acceptable to the container industry.

Pratt U.S. Pat. No. 3,708,082 discloses one attempt so far made to reduce the effects of vacuum deformation. Pratt discloses a container with four flat wall panels for the body portion of the container. In the area below the grip, ribs run around the entire circumference of the container and serve to stiffen the side wall portion in the circumferential direction. The ribs also serve as hinges to allow the container to be indented to a limited extent along a selected area.

Japanese Patent No. 30654 of 1979 discloses another method for reducing the reduced-pressure air deformation effect. In this method, the container is provided with a plurality of recessed panels separated by lands so that the deformation is carried out inward in a uniform and controlled manner, resulting in a reduced pressure deformation. The effect is uniform and the appearance of the container is not adversely affected.

Some of these prior art approaches use an indentation panel (ie, a recessed surface portion where a quantitative indentation is made) to overcome the thermal deformation of the container.

However, various problems arise with containers designed to use large, indented panels of width 30-40 mm or greater. Large indented panels can accommodate larger deformations, but as the width of the indented panels increases, it becomes difficult to achieve a controlled even indentation and cooling of hot-filled contents. Corresponding to the amount of shrinkage caused by the, the risk of non-uniform deformation of the dent panel is increased and the strength of the container body is reduced. For this reason, even if the inside of the container is depressurized, the portion of the dent panel is pushed by the weight of the contents and the phenomenon of bulging outward occurs.

Moreover, when making heat-setted panel containers with large indented panels, there is a significant problem of shrinkage and unwanted waviness on the surface of the container.

DESCRIPTION OF THE INVENTION The present invention relates to a hollow blow-molded container of biaxially stretched thermoplastic material, the container wall having a dent panel and the dent panel having a reinforcing rib.

The present invention has a wide width, such as a circumferential width of 40 mm or more,
Moreover, even if a dent panel having a large area with a length-to-width ratio in the height direction of 4: 1 or less is formed on the container, it is possible to cause the dent panel to undergo uniform and controlled decompression deformation. Reinforcement that does not reduce the strength of the dent panel, and therefore the dent panel does not bulge outward due to the weight of the contents and that the corrugated shape of the dent panel does not deform during heat setting. It is an object to provide a container having a dented panel with ribs.

The container can accommodate partial vacuuming or depressurization without detrimentally changing the strength or appearance of the container. The thin-walled container of the present invention specifically has a bottom, a neck, and a body extending between the neck and the bottom, the body including a plurality of indented panels, and at least one indented panel. At least one reinforcing rib extends inside.

According to the present invention, by providing a reinforcing rib in the dent panel, a wider dent panel (30 to 40 mm or more, the ratio of length to width is 4: 1 or less) can be used,
This has the effect of permitting a greater controlled decompression deformation of the container than in the case of a container without a ribbed indentation panel. A larger number of reinforcing ribs is required when increasing the area of the dent panel to accommodate a larger controlled vacuum deformation.

The left and right ends of the reinforcing rib extending into the dent panel are separated from the left and right edges of the dent panel, so the dent panel's strength is increased without impairing the dent panel's ability to absorb reduced pressure deformation. Produce an effect. Therefore,
The present invention is a container material capable of hot filling, i.e. 65-110.
It is particularly suitable for use with materials that allow the contents to be safely filled into containers at temperatures of ° C, more commonly at temperatures of 75-95 ° C. In this way, the container can be used with a relatively wide indentation panel, which has the effect of being able to accommodate greater vacuuming or depressurization by controlled and uniform depressurization deformation. . Reinforcing ribs are also used when the negative pressure in the container is removed,
It also has the effect of preventing the dent panel from being pushed by the weight of the contents and bulging outward. Reinforcing ribs are also effective in preventing swelling and waviness of large dent panels in heat-set PET containers when removed from the mold.

Description of an Embodiment of the Invention FIG. 1 shows a thin blow molded plastic container 1, which is made of heat set polyethylene terephthalate (PET) or nitrile. The container 1 includes a body 2 having a shoulder 3. The main body 2 can have a cross section of any shape, for example,
It may be rectangular (FIG. 4), square (FIG. 3), polygon such as hexagon or octagon, or circle. The lower end of the body 2 is closed by a bottom 4, the body 2 extends upwardly from the bottom and tapers diametrically inward at the upper end of the body to form a shoulder 3, which Ends at the network section 5. The neck portion 5 may have external threads for attachment of a cap (not shown), and the neck portion 5 may be a non-stretched neck portion such as disclosed in US Pat. No. 4,379,099. To
It can also be crystallized to provide heat, chemical and mechanical strength.

The body 2 of the container is specially shaped to accommodate controlled changes in the volume of the container when the interior of the container is partially evacuated or evacuated. As can be seen from FIGS. 1 and 2, a concave dent panel 6 is formed around the main body 2. The dent panel 6 is
It may be formed on each side of the polygonal body 2, and adjacent dent panels 6 are separated from each other by lands 7.

The dent panel 6 may be formed on a smaller number of side surfaces than all the side surfaces of the container, for example, every other side surface. These indented panels are elongated in the longitudinal direction of the container and have a substantially rectangular shape (Fig. 2) or an elliptical shape (Fig. 1). Each dent panel may be provided with one or more reinforcing ribs 8 which serve to strengthen the dent panel 6.
The reinforcing ribs 8 are preferably concave, preferably extending only inside the dent panels and not into the lands separating adjacent dent panels. The length of the reinforcing rib is considerably shorter than the width of each recess panel, and the left and right edges of the recess panel and the left and right ends of the reinforcing rib are separated from each other.

The number of reinforcing ribs per panel depends primarily on the height of the recessed panel and the type and thickness of the material forming the container. That is, different materials have different resistances to deformation under vacuum and in the process of heat setting, and the required number of reinforcing ribs per dent panel changes accordingly. Furthermore, the conditions under which the container is filled with the contents and the nature of the contents filled into the container also affect the number of reinforcing ribs required. Reinforcing ribs should preferably be spaced 25-45 mm apart. For wide panels or panels with a very small height to width ratio (eg less than about 2: 1), the spacing should be reduced. In this case, the ribs may be closer than 25 mm apart. Based on the type of material of the container, the content of the container and the filling temperature, the number of reinforcing ribs per panel should be determined by a person having ordinary skill in the art after conducting ordinary experiments. You can

Furthermore, reducing the width of each panel and increasing the number of panels does not improve the container's ability to absorb reduced pressure deformation, as compared to the case of using a wide dent panel with an appropriate number of reinforcing ribs provided therein. . Similarly, a dent panel with too many ribs will not be able to undergo a well-controlled deformation, i.e. a controlled vacuum deformation, and thus the purpose of the dent panel will not be achieved.

The following examples illustrate the invention, but the invention is not limited thereto.

EXAMPLE A panel with a width of 46 mm and a length: width ratio of 2.7 was used to make a container with a round cross section of 64 ounces and six recessed panels as shown in FIG. The panel was not ribbed, the container was hot filled with the contents, capped and allowed to cool to room temperature, blistering was observed on the panel. The blisters got worse when I removed the cap and released the vacuum.

The dent panel was then provided with reinforcing ribs to make the same container. No blister was observed on the panel when hot-filled and cooled to room temperature under the same conditions. Similarly, no blister was observed when the cap of the container was removed and the vacuum was released.

In another example, a 64 ounce container was made with a square cross section and indented panels on each side. The width of the dent panel is about 56m
The m, length: width ratio was 2.8. When you remove the container from the mold,
The panel produced corrugations that did not fit the surface of the mold. When the containers were hot filled, blistering was noted on one or more panels both when the container was under vacuum and after the vacuum was released. The blisters were worse after removing the cap.

When the panels were ribbed to make the same container, there were no problems either when the container was removed from the mold or after hot filling under the same conditions.

[Brief description of drawings]

1 is a side view of a container having a dent panel with ribs, FIG. 2 is a side view of a container of another example according to the present invention, FIG. 3 is a cross-sectional view of a square container, and FIG. It is a cross-sectional view of a rectangular container. 1: container, 2: body part, 3: shoulder part, 4: bottom part, 5: neck part, 6: dent panel, 7: land, 8: reinforcing rib.

Claims (2)

[Claims] 1. A thin wall container blow molded by blow molding using a thermoplastic synthetic resin and heat set, the peripheral surface of the main body extending between the bottom portion and the neck portion is divided by a land which is a peripheral wall of the main body portion. A plurality of recessed panels are formed in an even arrangement, and at least a part of the recessed panels is formed with a reinforcing rib having a circumferential length shorter than the circumferential width of each recessed panel in a lateral direction. A container having a dent panel with reinforcing ribs, which is separated from the left and right edges and the left and right ends of the reinforcing rib. 2. A container having a dent panel with reinforcing ribs according to claim 1, wherein a plurality of reinforcing ribs are formed in the dent panel.