JP2005112440A - Container - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the weight of a plastic bottle container as a whole while good handling properties of the container are retained. <P>SOLUTION: A waist part 15 is formed in the middle of the height direction of the trunk 13 of the bottle container 10 by the shape of a blow molding die used in a blow molding process of a preform 1. First and second drawn parts 16 and 17 are formed on the waist part 15, which is made as a thick-walled part at least on the basis of the size setting of the second drawn part 17. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a container formed by stretch blow, and particularly to a plastic bottle container having a large capacity.

  Plastic bottle containers such as PET bottles are easy to mold, suitable for mass production, and have excellent properties such as high mechanical strength and light weight. It is used in a wide range of fields. In particular, they are used in large quantities as beverage containers filled with various beverages.

  There are many types of plastic bottle containers to meet market demands. For example, as a large capacity, a plastic bottle container having a capacity of about 2000 ml is used. In such a large-capacity plastic bottle container, the cross-sectional shape is generally formed in a substantially rectangular shape in consideration of refrigerator storage properties and ease of holding.

In addition, in a plastic bottle container having a large capacity, a concave waist portion that surrounds the entire circumference is formed in an intermediate portion in the height direction of the barrel portion in order to give the barrel a necessary strength. The waist portion not only functions as a reinforcing portion, but can also function as a gripping portion that hooks a finger when holding the plastic bottle container with one hand (see, for example, Patent Documents 1 and 2).
JP-A-8-230856 JP-A-8-310521

  In recent years, there has been a strong demand for weight reduction of plastic bottle containers for the purpose of promoting resource saving. Since this type of plastic bottle container is formed by stretching and blowing a preform (parison), it is possible to achieve weight reduction by reducing the resin weight of the preform.

  However, in the method of simply reducing the resin weight of the preform, the plastic bottle container is thinned as much as the weight is reduced. In particular, when the rigidity and resilience of the waist portion are lowered, deformation is easily caused when the container is gripped, and it becomes difficult to ensure good handling properties.

  The present invention has been considered in view of the above circumstances, and when reducing the weight of the container, it is possible to reduce the weight of the entire container while ensuring good handling properties by avoiding thinning of the waist portion. The purpose is to provide a container that can be used.

  In order to achieve the above object, the container of the present invention is a container that forms a waist portion in the middle in the height direction of the trunk portion according to the shape of the blow mold when the preform is blow-molded. In this, a primary narrowing portion and a secondary narrowing portion are formed, and the waist portion is thickened by having at least the secondary narrowing portion.

If it does in this way, even if another site | part becomes thin for weight reduction, since thickness required for a waist part can be ensured, it can avoid that the rigidity and the recoverability of a waist part are impaired remarkably. This makes it possible to reduce the weight of the entire container while ensuring good handling properties.
Moreover, since the waist portion is only thickened by appropriately setting the size of the secondary narrowing portion, there is no inconvenience that the manufacturing process is complicated and the cost is increased.

In the container of the present invention, the drawing ratio of the secondary narrowing portion with respect to the maximum diameter of the trunk portion is 0.65 to 0.85 times.
If it does in this way, in a stretch blow molding, a waist part can be thickened moderately and the rigidity and restoration nature of a waist part can be improved.
In addition, when said drawing ratio is less than 0.65 time, it will become easy to produce a meat pool in a waist part, and when it exceeds 0.85 time, the effect of thickening in a waist part will become thin.

In the container of the present invention, the thickness ratio of the waist part to the thickness of the body part is 1.15 to 1.5 times.
If it does in this way, rigidity required for a waist part can be secured, making a body part thin.
In addition, when said thickness ratio is less than 1.15 times, the rigidity improvement effect will become thin, and when it exceeds 1.5 times, the thickness of a waist part will become excess and it will lead to thickness reduction of another site | part.

In the container of the present invention, the trunk cross section is substantially rectangular or square, and the secondary narrowing portion is formed in the center in the circumferential direction of the opposing surface, and the secondary narrowing is formed on both sides in the circumferential direction. A primary narrowing portion shallower than the narrowing portion is formed.
If it does in this way, when grasping a container, it will become possible to hold a container stably by putting a finger along a primary narrowing-down part and hooking a fingertip on a secondary narrowing-down part. Thereby, the handleability of the container can be further improved.

In the container of the present invention, the body section has a substantially rectangular cross section, and its short side is 110 mm or less.
If it does in this way, even if it is a large sized container about 2000-3000 ml, for example, it can support with one hand stably.

In the container of the present invention, the width in the height direction of the primary narrowing portion and the width in the height direction of the secondary narrowing portion are 7 to 15 mm, respectively.
In this way, since the narrowing-down and the finger size are matched, the fit feeling of the finger is increased, and the handling property of the container can be further improved.
Moreover, when the narrowing width is set as described above, the thickness distribution at the time of stretch blow molding is moderately affected, and the waist portion can be easily thickened.

In the container of the present invention, the radius of the tangent circle where the vertical surface of the primary narrowing portion and the upper and lower inclined surfaces contact is 8 to 20 mm.
In this way, when gripping the container, the finger fits on the vertical surface of the primary narrowing portion and the upper and lower inclined surfaces thereof, so that the handling property of the container can be further improved.

  As described above, according to the present invention, even when the entire container is reduced in weight, the necessary thickness of the waist portion can be ensured. It is possible to reduce the weight of the entire container while securing the properties.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[preform]
First, a preform for manufacturing a plastic bottle container (hereinafter simply referred to as a bottle container) will be described with reference to FIG.
FIG. 1 is a cross-sectional view showing an example of a preform.
In the present specification, the preform is used as a general term for an intermediate molded body, and includes a parison, a menco, and the like.

1. As shown in FIG. 1, a preform 1 for manufacturing a bottle container is made of a thermoplastic resin, and includes a mouth part 1a, a part 2 serving as a shoulder part of the bottle container, and a body part of the bottle container. It forms in the bottomed cylinder shape provided with the part 3 used as and the part 4 used as the bottom part of a bottle container.
In addition, this preform 1 can be made into arbitrary shapes. In the example shown in FIG. 1, the portion 4 that becomes the bottom of the bottle container has a substantially hemispherical shape, but is not particularly limited to this shape, for example, the portion 4 that becomes the bottom becomes an elliptical shape, or the tip is flattened. You can also

2. As the thermoplastic resin constituting the preform 1, any resin can be used as long as it can be stretch blow molded and thermally crystallized.
Specifically, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polycarbonate, polyarylate, or thermoplastic polyesters such as copolymers thereof, blends of these resins or other resins are suitable, In particular, an ethylene terephthalate thermoplastic polyester such as polyethylene terephthalate is preferably used.
Further, acrylonitrile resin, polypropylene, propylene-ethylene copolymer, polyethylene and the like can also be used.
These resins are blended with various additives such as colorants, ultraviolet absorbers, mold release agents, lubricants, nucleating agents, antioxidants, antistatic agents and the like within a range that does not impair the quality of the molded product. be able to.

The ethylene terephthalate-based thermoplastic polyester constituting the preform 1 occupies most of the ester repeating units, generally 70 mol% or more of the ethylene terephthalate units, and has a glass transition point (Tg) of 50 to 90 ° C., a melting point ( Those having a Tm) in the range of 200 to 275 ° C are preferred.
As an ethylene terephthalate-based thermoplastic polyester, polyethylene terephthalate (PET) is particularly excellent in terms of pressure resistance, heat resistance, heat pressure resistance, etc. In addition to ethylene terephthalate units, dibasic acids such as isophthalic acid and naphthalenedicarboxylic acid Copolyesters containing a small amount of ester units composed of diols such as propylene glycol can also be used.

Further, the preform 1 of the present embodiment can be composed of two or more thermoplastic polyester layers in addition to the case of being composed of a single layer (one layer) of thermoplastic polyester layer.
Furthermore, the preform 1 of the present embodiment can include a medium layer enclosed between an inner layer and an outer layer composed of two or more thermoplastic polyester layers, and the intermediate layer is a barrier layer or an oxygen absorbing layer. be able to.
By providing the barrier layer and the oxygen absorbing layer in this manner, it is possible to suppress the permeation of oxygen from the outside into the bottle container, and to prevent the deterioration of the contents in the bottle container due to the oxygen from the outside. It is suitable for a bottle container for beverages containing carbon dioxide gas.
Here, as the oxygen absorbing layer, any layer can be used as long as it absorbs oxygen and prevents permeation of oxygen, but a combination of an oxidizable organic component and a transition metal catalyst, or substantially It is preferred to use a combination of a gas barrier resin that does not oxidize, an oxidizable organic component and a transition metal catalyst.

[Bottle container]
Next, the bottle container according to the present embodiment will be described with reference to FIGS.
2 is a front view of the bottle container, FIG. 3 is a side view of the bottle container, FIG. 4 is an XX sectional view of the bottle container, and FIG. 5 is a YY sectional view of the bottle container.

1. Configuration of Bottle Container The bottle container 10 is a plastic bottle container formed by stretch blow molding the preform 1 described above, and as shown in FIG. 2, a mouth portion 11, a shoulder portion 12, a trunk portion 13 and a bottom portion. 14.
The body portion 13 preferably has a substantially rectangular cross-sectional shape and a short side of 110 mm or less.
If it does in this way, even if it is a large container with a capacity | capacitance of 2000-3000 ml, while being able to ensure favorable refrigerator stowability, it becomes possible to hold | maintain the bottle container 10 with one hand.

2. The waist part 15 The concave waist part 15 is formed in the intermediate part of the height direction of the trunk | drum 13 over the perimeter. The waist part 15 is a part having both a reinforcing part function for imparting a necessary strength to the body part 13 and a gripping part function for facilitating handling when the bottle container 10 is held with one hand. Even in the case of reducing the weight, it is necessary to ensure a predetermined thickness at this portion in order to maintain the necessary rigidity and resilience.

The waist portion 15 is formed by a primary narrowing portion 16 having a relatively shallow trunk diameter and a secondary narrowing portion 17 having a trunk diameter deeper than that. In other words, narrowing projections for the primary narrowing portion 16 and the secondary narrowing portion 17 are formed to protrude at the waist corresponding portion of the blow mold used for stretch blow molding, and the preform 1 stretched by stretch blow is blown. By contacting the primary and secondary narrowing convex portions of the mold, the waist portion 15 is formed.
Since the above-mentioned narrowed convex portion becomes a resistance when the preform 1 is stretched, the size setting of the narrowed-down portions 16 and 17, particularly the size setting of the secondary narrowed-down portion 17 has a great influence on the wall thickness distribution during stretch blow molding. give.

In the present invention, paying attention to the above phenomenon, the waist portion 15 is thickened based on the dimension setting of the secondary narrowing portion 17.
If it does in this way, even if another site | part becomes thin for weight reduction, it becomes possible to ensure thickness required for the waist part 15. FIG. Thereby, it can avoid that the rigidity and the recoverability of the waist part 15 are impaired, and the whole container can be reduced in weight, ensuring favorable handling property.

Further, the drawing ratio (B2 / A) of the secondary narrowing portion 17 with respect to the maximum diameter A of the body portion 13 in the minor axis direction is preferably 0.65 to 0.85 times.
If it does in this way, the waist part 15 can be thickened moderately in stretch blow molding, and the rigidity and resilience of the waist part 15 can be improved.
If the drawing ratio (B2 / A) is less than 0.65 times, the waist portion 15 tends to be thickened, and if it exceeds 0.85 times, the effect of thickening the waist portion 15 is reduced.

Further, the thickness ratio of the waist portion 15 to the thickness of the body portion 13 is preferably 1.15 to 1.5 times.
If it does in this way, rigidity required for waist part 15 can be secured, making body part 13 thin.
If the thickness ratio is less than 1.15 times, the effect of improving the rigidity is reduced, and if it exceeds 1.5 times, the thickness of the waist portion 15 becomes excessive, leading to thinning of other parts.

Moreover, the cross-sectional shape of the trunk | drum 13 is made into a substantially rectangular (or square), and while forming the secondary narrowing part 17 in the center part of the circumferential direction of the surface which opposes, the primary narrowing part 16 is formed in the circumferential direction both sides. It is preferable to form.
If it does in this way, when grasping bottle container 10, it will become possible to hold bottle container 10 stably by putting a finger along primary narrowing part 16 and hooking a fingertip on secondary narrowing part 17.

The width C1 in the height direction of the primary narrowing portion 16 and the width C2 in the height direction of the secondary narrowing portion 17 are each preferably 7 to 15 mm.
In this way, since the size of the narrowing-downs 16 and 17 and the size of the finger are matched, the feeling of fitting the finger is increased and the handling property of the bottle container 10 can be further improved.
Further, when the widths C1 and C2 of the narrowing-downs 16 and 17 are set as described above, the thickness distribution at the time of stretch blow molding is moderately affected, and the waist portion 15 can be easily thickened.

Further, the radius R of the tangent circle where the vertical surface 16a of the primary narrowing portion 16 and the upper and lower inclined surfaces 16b and 16c are in contact with each other is preferably 8 to 20 mm.
In this way, when the bottle container 10 is gripped, the fingers fit on the vertical surface 16a of the primary narrowing portion 16 and the upper and lower inclined surfaces 16b, 16c, so that the handling property of the bottle container 10 can be further improved. .

[Manufacturing method of bottle container]
Next, a method for manufacturing the bottle container 10 will be described.

1. Production of Preform The preform 1 can be produced in the form of a bottomed cylinder by known injection molding or extrusion molding.
In addition, when using the multilayer preform which equips an intermediate | middle layer with an oxygen absorption layer as the preform 1, using a conventionally well-known co-injection molding machine etc., the inner and outer layers are made of polyester resin, Alternatively, a multilayer preform having a bottom and an opening corresponding to the shape of the injection preform mold can be manufactured by inserting two or more oxygen absorption layers.

2. Stretch Blow Molding Next, the preform 1 is biaxially stretch blow molded.
In general, there are two stretch blow molding methods, a hot parison method and a cold parison method. The hot parison method is a method of stretch-blow molding in a softened state without completely cooling a bottomed preform formed by injection molding a polyester resin, and is excellent in productivity.
On the other hand, in the cold parison method, a cooled bottom preform having a size smaller than the final shape and non-crystalline polyester is formed in advance by injection molding a polyester resin. Is preheated to a stretching temperature and stretched in a blow mold, and is excellent in precision such as dimensions.
Any method can be used for manufacturing the bottle container 10 according to the present embodiment.

Stretch blow molding is a one-stage blow molding method that blows the preform as it is to the size of the final molded product, and a preform is blown once to be larger than the final molded product to form a medium product. There is a two-stage blow molding method in which this intermediate product is thermally shrunk to obtain a final molded product.
The two-stage blow molding is suitable for uniforming the wall thickness of the container, but has a problem that productivity is lowered because the number of steps is complicated and complicated.
In the present embodiment, since the bottle container 10 having a desired thickness distribution can be obtained by the single-stage blow molding as described below, a single-stage blow molding method with fewer steps and excellent productivity is adopted, and the cost is low. Compatible with beverage bottle containers that require mass production.

FIG. 6 is an explanatory diagram of stretch blow molding.
In the stretch blow molding according to the present embodiment, first, the preform 1 is heated to a stretching temperature equal to or higher than the glass transition point (Tg), for example, 85 to 120 ° C., and the heated preform 1 is subjected to a predetermined heat treatment (heat set). Biaxial stretch blow molding is performed in a blow mold 20 heated to a temperature.
Specifically, the heated preform 1 is stretched in the longitudinal direction (axial direction) by a stretching rod or the like, and stretched in the lateral direction (circumferential direction) by blow air. The stretched blow molded article is brought into contact with the inner surface of the blow mold 20 for a predetermined time, and then cooled by an internal cooling fluid. Thereafter, the blow mold 20 is removed, and the bottle container 10 is obtained.

In the present embodiment, a narrowing convex portion 20a for the primary narrowing portion 16 and a narrowing convex portion 20b for the secondary narrowing portion 17 are formed so as to protrude from the waist corresponding portion of the blow mold 20 used for the stretch blow molding described above. The waist portion 15 is formed by bringing the preform 1 stretched by stretch blow into contact with the narrowed projections 20a and 20b.
At this time, the projecting dimension of the narrowing convex portion 20b of the mold is set so that the narrowing ratio (B2 / A) of the secondary narrowing portion 17 with respect to the maximum diameter A of the body portion 13 is 0.65 to 0.85 times. Is done.

  When stretch blow molding is performed in this manner, the preform 1 tends to stay in the waist portion corresponding portion due to the resistance of the narrowing convex portion 20b of the mold when stretched, and the wall thickness distribution portion corresponds to the waist portion corresponding portion. Moderately biased. Thereby, the waist part 15 of the bottle container 10 blow-molded is thickened compared with the trunk | drum 13, and the thickness ratio becomes 1.15 to 1.5 times.

Next, specific examples of the bottle container 10 according to the present invention will be described with reference to FIGS. 2 to 4, 7 and 9.
2 to 4 are a front view, a side view, and an xx cross-sectional view of the bottle container according to the first and second embodiments, and FIG. 7 is a thickness distribution of the front of the bottle container according to the first and second embodiments. FIG. 8 is a graph showing the wall thickness distribution of the bottle container according to Example 1 and Example 2, and FIG. 9 is a table showing the wall thickness distribution of the bottle container according to Example 1 and Example 2. is there.

Two types of bottle containers 10 having a capacity of 2000 ml were produced by the above production method (Examples 1 and 2).
As shown in FIGS. 2 to 4, the bottle containers 10 of Examples 1 and 2 are both substantially rectangular in cross section, the short side length A is 87.5 mm, the primary narrowing portion 16 and the secondary narrowing portion 16 Both the widths C1 and C2 in the height direction of the narrowed portion 17 were 10 mm. Further, the radius R of the tangent circle where the vertical surface 16a of the primary narrowing portion 16 and the upper and lower inclined surfaces 16b and 16c contact each other was set to 15.9 mm.
In addition, the size B1 of the primary narrowing portion 16 in the minor axis direction was 75.5 mm (depth 6 mm) in Example 1, and 71.5 mm (depth 8 mm) in Example 2.
In addition, the size B2 of the secondary narrowing portion 17 in the minor axis direction was 67.5 mm (depth 10 mm) in Example 1, and 63.5 mm (depth 12 mm) in Example 2.

When the thickness distribution of the bottle container 10 of Example 1 and Example 2 molded under the above conditions was examined, on the long side (front side) of the bottle container 10 according to Example 1, in the upper trunk portion 13. The thickness of the central portion (measurement position 181.5 mm) is 0.27 mm, and the thickness of the central portion (measurement position 69.5 mm) in the lower body 13 is 0.26 mm, whereas the waist portion 15 The thickness of the central part (measurement position 127.0 mm) was 0.33 mm.
According to this, the thickness ratio of the waist portion 15 to the trunk portion 13 is about 1.2 times, and as a result, the rigidity (proportional to the cube of the thickness ratio) of the waist portion 15 is larger than that of the trunk portion 13. About 1.7 times.
In addition, on the short side (side surface), since the secondary narrowing portion 17 is not provided, the waist portion 15 is slightly thickened.

On the other hand, on the long side (front side) of the bottle container 10 according to Example 2, the thickness of the central portion (measurement position 181.5 mm) in the upper trunk portion 13 is 0.27 mm, and the center in the lower trunk portion 13 is. The thickness of the portion (measurement position 69.5 mm) was 0.25 mm, whereas the thickness of the central portion (measurement position 127.0 mm) in the waist portion 15 was 0.33 mm.
According to this, the thickness ratio of the waist part 15 with respect to the trunk | drum 13 is about 1.3 times, As a result, the rigidity of the waist part 15 became about 2.1 times compared with the trunk | drum 13. FIG.
In addition, although the waist part 15 of the short side (side surface) was thickened rather than Example 1, the thickness ratio with respect to the trunk | drum 13 remained only about 1.1 times.

  The present invention can be applied to a container formed by stretch blow. Particularly, it is useful for a plastic bottle container having a large capacity.

It is sectional drawing which shows an example of preform. It is a front view of a bottle container. It is a side view of a bottle container. It is XX sectional drawing of a bottle container. It is YY sectional drawing of a bottle container. It is explanatory drawing of stretch blow molding. It is a graph which shows the thickness distribution of the bottle container front which concerns on Example 1 and Example 2. FIG. It is a graph which shows the thickness distribution of the bottle container side surface based on Example 1 and Example 2. FIG. It is a table | surface which shows the thickness distribution of the bottle container which concerns on Example 1 and Example 2. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Preform 10 Bottle container 11 Mouth part 12 Shoulder part 13 Body part 14 Bottom part 15 Waist part 16 Primary narrowing part 16a Vertical surface 16b Inclined surface 16c Inclined surface 17 Secondary narrowing part 20 Blow mold

Claims (7)

When the preform is blow-molded, it is a container that forms a waist portion in the middle in the height direction of the trunk portion by the shape of the blow mold,
The container is characterized in that a primary narrowing portion and a secondary narrowing portion are formed in the waist portion, and the waist portion is thickened by having at least the secondary narrowing portion.   The container according to claim 1, wherein a drawing ratio of the secondary narrowing portion with respect to a maximum diameter of the trunk portion is 0.65 to 0.85 times.   The container according to claim 1 or 2, wherein a thickness ratio of the waist part to a thickness of the body part is 1.15 to 1.5 times.   The trunk section has a substantially rectangular or square cross section, the secondary narrowing section is formed at the center in the circumferential direction of the opposing surface, and the primary narrowing section shallower than the secondary narrowing section on both sides in the circumferential direction. Is formed, The container in any one of Claims 1-3 characterized by the above-mentioned.   The container according to claim 1, wherein the trunk section has a substantially rectangular cross section and a short side of 110 mm or less.   The container according to any one of claims 1 to 5, wherein a width in the height direction of the primary narrowing portion and a width in the height direction of the secondary narrowing portion are 7 to 15 mm, respectively.   The container according to any one of claims 1 to 6, wherein a radius of a tangent to which the vertical surface of the primary narrowing portion and the upper and lower inclined surfaces contact is 8 to 20 mm.

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