WO2012073744A1

WO2012073744A1 - Preform

Info

Publication number: WO2012073744A1
Application number: PCT/JP2011/076828
Authority: WO
Inventors: 松岡　建之
Original assignee: ザコカ・コーラカンパニー
Priority date: 2010-12-03
Filing date: 2011-11-21
Publication date: 2012-06-07
Also published as: JP2012116160A; JP5631183B2

Abstract

Provided is a preform in which the amount of resin can be further reduced. A preform (10) is constituted by a mouth portion (12), and a bottomed cylindrical preform main body (14) extending from the mouth portion (12), wherein the preform main body (14) is stretched by biaxial stretching blow molding, while the mouth portion (12) is not stretched, to form a plastic bottle. The preform main body (14) comprises a plurality of volume-reducing portions (50) formed at a uniform interval in the circumferential direction of the preform (10), at a boundary portion to the mouth portion (12) and a portion to be stretched by the biaxial stretching blow molding.

Description

preform

The present invention relates to a preform formed into a plastic bottle by biaxial stretch blow molding.

Generally, plastic bottles (pet bottles) mainly composed of polyethylene terephthalate resin are manufactured by biaxially stretching blow-molding a preform. In recent years, there has been a strong demand for manufacturing lightweight bottles with a reduced amount of preform resin.

In view of such a request, the applicant of the present invention has proposed a bead ring and a support ring as a structure for reducing the weight of the bottle mouth (same as the mouth of the preform) without sacrificing the strength of the mouth. Has proposed a structure in which the outer peripheral surface is partially thinned (see Patent Document 1).

JP 2010-95269 A

The structure described in Patent Document 1 is useful in that the amount of preform resin can be reduced by the amount of meat removal. However, further reduction of the amount of resin is desired from the viewpoint of resource saving in recent years.

Therefore, an object of the present invention is to provide a preform that can further reduce the amount of resin.

The inventor of the present invention focused on the biaxial stretch blow molding method as a result of intensive studies on how to reduce the amount of resin while taking into consideration the strength, moldability, and container handling appropriateness. In this molding method, generally, a bottomed cylindrical preform main body continuous to the lower end of the support ring of the mouth is stretched without stretching the mouth of the preform. The present inventor has found that the lower part of the support ring (that is, the boundary part with the mouth part in the preform main body part) remains thick without being stretched in the same manner as the bottle body part. The present invention has been completed.

That is, the preform of the present invention is composed of a mouth portion and a bottomed cylindrical preform body portion extending from the mouth portion, and the preform body portion without being stretched by biaxial stretch blow molding. In a preform that is stretched and molded into a plastic bottle, the preform body is evenly distributed in the circumferential direction of the preform at the boundary with the mouth and stretched by biaxial stretch blow molding. It has a plurality of lightening portions formed at intervals.

According to the present invention, since the boundary portion that has remained thick in the conventional portion of the preform main body is cut out, the amount of resin in the cut out portion can be reduced. Further, compared with the case where the entire boundary portion is uniformly thinned, the strength of the boundary portion does not need to be greatly reduced. In particular, since the lightening portions are formed at equal intervals, the strength of the boundary portion is well balanced in the circumferential direction, and the amount of resin is reduced in consideration of strength. Moreover, in the case of forming a preform by an injection molding method, the fluidity of the injected resin is better than the case where a thin portion is provided in the entire circumferential direction in order to form the thinned portions at equal intervals. Thus, molding defects are less likely to occur.

According to a preferred aspect of the present invention, the mouth portion may have a circumferential ring portion having a diameter larger than that of the preform main body portion at a portion defining a boundary with the preform main body portion. In addition, the preform main body portion has a cylindrical outer peripheral surface having no unevenness that is continuous with the lower end of the circumferential ring portion, and is formed on the outer peripheral surface continuous with the lower end of the cylindrical outer peripheral surface without the unevenness. It is good to form the extraction part.

According to this aspect, the preform and thus the plastic bottle after molding can be stably handled by using the peripheral ring portion and the cylindrical outer peripheral surface without unevenness. Thereby, the handleability at the time of handling a preform and a plastic bottle can be improved.

More preferably, the height of the thinned portion is larger than the height of the cylindrical outer peripheral surface having no irregularities.

Further, according to a preferred aspect of the present invention, the portion of the lightening portion is closer to the circumferential ring portion, and the amount of lightening is larger, and the amount of lightening gradually decreases as the distance from the circumferential ring portion increases, and finally disappears. Good.

According to this aspect, the formability from the preform to the plastic bottle is improved. Specifically, the portion of the lightening portion farthest from the circumferential ring portion is easily stretched, but if there is a step at this portion, the preform may burst during biaxial stretch blow molding. . Therefore, according to the preferable aspect in which such a step is eliminated, the moldability to the plastic bottle can be ensured. Moreover, since the part of the lightening part close | similar to a circumferential ring part is hard to be extended | stretched in the case of biaxial stretch blow molding, the amount of lightening can be increased effectively.

Furthermore, according to a preferred aspect of the present invention, the mouth portion may have a second circumferential ring portion on the upper side of the circumferential ring portion and a thread on the upper side of the second circumferential ring. Further, when a plurality of lightening portions are formed on the outer peripheral surface between the circumferential ring portion and the second circumferential ring portion at the same equal interval as the plurality of lightening portions in the preform main body portion. Good.

According to this aspect, the amount of resin can be further reduced as a whole preform. In addition, since both the hollowed portions of the mouth portion and the preform main body portion are equally spaced from each other, the strength of the upper and lower portions of the circumferential ring portion not only improves the balance in the circumferential direction, but also an injection molding method. When the preform is molded by the above-described method, the fluidity of the resin and the removal of the mold are improved, and molding defects are less likely to occur.

Preferably, the cross-sectional shape of the thinned portion is an arc shape.

According to this configuration, when the preform is injection-molded, it can be easily taken out from the mold for that purpose as compared with the trapezoidal shape.

It is a front view of the plastic bottle which concerns on embodiment. It is a front view of the preform concerning an embodiment. FIG. 3 is a longitudinal sectional view of the preform cut along the line III-III in FIG. 2, which is cut at a position that does not pass through a preformed portion of the preform. FIG. 4 is a longitudinal sectional view of a preform cut at an angle different from that of FIG. 3, and is cut at a position passing through a preformed portion and a central axis. FIG. 5 is a cross-sectional view taken along line VV in FIG. 3.

Preferred embodiments of the present invention will be described with reference to the accompanying drawings.
In the following, first, a plastic bottle will be briefly described, and then a preform molded into the plastic bottle will be described in detail. Further, in the following description, in the preform, the direction where the mouth portion exists is the upper side, and the direction where the preform main body portion exists is the lower side. The height means a length along the direction (vertical direction) of the central axis of the preform. The cross-sectional shape means a cross-sectional shape in a plane (transverse section) orthogonal to the central axis.

As shown in FIG. 1, the plastic bottle 1 has a mouth part 2, a shoulder part 3, a trunk part 4, and a bottom part 5 in order from the upper side. These parts (2, 3, 4 and 5) are integrally formed and constitute a bottle wall for storing a beverage therein. Examples of the beverage include non-carbonated beverages such as water, green tea, oolong tea, and fruit juice. However, in another embodiment, the liquid filled in the plastic bottle 1 may be a food such as a carbonated drink or a sauce.

As shown in FIG. 2, the preform 10 includes a mouth portion 12 and a bottomed tubular preform body portion 14 extending downward from the mouth portion 12. The preform 10 is manufactured by injection molding using polyethylene terephthalate as a main material, and is then formed into a plastic bottle 1 by being subjected to biaxial stretch blow molding. At this time, only the preform main body portion 14 is stretched by the biaxial stretch blow molding, and the mouth portion 12 is not stretched. For this reason, the shape and size of the mouth portion 2 of the plastic bottle 1 are the same as the shape and size of the mouth portion 12 of the preform 10. In other embodiments, a thermoplastic resin other than polyethylene terephthalate (for example, polyethylene or polypropylene) can be used as the main material.

2 to 4, the mouth portion 12 has a cylindrical peripheral wall 20 having an upper end opened. The inner peripheral surface 22 of the peripheral wall 20 extends in the vertical direction without a step, while the outer peripheral surface 24 of the peripheral wall 20 is formed with a screw thread 26, a bead ring 28, and a support ring 30 in order from the top. Yes. The sealing performance of the plastic bottle 1 is maintained by fitting a cap (not shown) to the mouth portion 2 using the screw thread 26. Each of the bead ring 28 and the support ring 30 is a circumferential ring portion (sometimes referred to as a flange portion) having a larger diameter than the preform main body portion 14, and extends outwardly from the outer peripheral surface 24 in the circumferential direction. Protruding. A plurality of lightening portions 32 are formed on the outer peripheral surface of the outer peripheral surface 24 between the bead ring 28 and the support ring 30. A boundary between the mouth portion 12 and the preform main body portion 14 is defined by the support ring 30, and the upper portion (that is, the entire mouth portion 12) from the lower surface of the support ring 30 is not stretched in the biaxial stretch blow molding.

As shown in FIGS. 2 to 5, the preform main body 14 has a cylindrical body 40 having a constant diameter, a bottom 42 continuous to the lower part of the body 40, and a support continuously to the upper part of the body 40. And a neck portion 44 continuous with the lower end of the ring 30. The bottom portion 42 is often hemispherical, but is not limited to such a shape, and may be any shape that closes the lower portion of the body portion 40. The neck portion 44 has a curved portion 46 extending upward from the upper portion of the body portion 40 so as to expand slightly and a short cylindrical shape extending from the curved portion 46 to the support ring 30 without being curved. , And a vertical portion 48. Further, on the outer peripheral surface of the neck portion 44, a plurality of lightening portions 50 are formed at equal intervals in the circumferential direction.

Here, focusing on the thickness of the portion excluding the thinned portion 50, in the preform main body portion 14, the thickness of the trunk portion 40 and the bottom portion 42 is the same or substantially the same, but the thickness of the vertical portion 48 is It is slightly smaller than the thickness of the body 40 and the bottom 42. For this reason, the thickness of the bending portion 46 is configured to gradually decrease from the trunk portion 40 to the vertical portion 48. Further, the thickness of the vertical portion 48 is the same as or substantially the same as the thickness of the portion between the bead ring 28 and the support ring 30, and the thickness of the portion where the screw thread 26 exists (the upper portion of the mouth portion 12). Bigger than. Further, focusing attention on the outer diameter, the preform main body portion 14 has the largest outer diameter of the vertical portion 48, and the outer diameter is the same or substantially the same as the outer diameter of the portion between the bead ring 28 and the support ring 30. It is.

As shown in FIG. 5, there are a total of eight thinned portions 50, which are lined up symmetrically with equal intervals in the circumferential direction across the column portion 52. A portion 54 that connects the lightening portion 50 and the column portion 52 is rounded by an arc having a center of curvature inside the preform main body portion 14 so that both are smoothly connected. The cross-sectional shape of the lightening portion 50 is an arc shape curved inward of the preform main body portion 14. Therefore, the thinned portion 50 has the thinnest central portion and is gradually thickened at both ends thereof.

Here, the difference between the minimum outer diameter of the lightening portion 50 and the outer diameter of the column portion 52 is preferably 3.0 mm or less, more preferably 1.5 mm to 2.0 mm. This is because if the thickness exceeds 3.0 mm, the thermoplastic resin may not reach both ends of the thinned portion 50 when the preform 10 is injection-molded. Further, the arcuate R (curvature radius) of the thinned portion 50 is preferably in the range of 5 to 50 mm, more preferably 30 mm. When R is less than 5 mm, undercutting occurs, and it becomes difficult to take out the preform 10 from the mold. On the other hand, when R exceeds 50 mm, it is not possible to sufficiently obtain a lightening effect for weight reduction.

As shown in FIGS. 2 to 4, an outer peripheral surface 56 without unevenness is formed between the thinned portion 50 and the support ring 30. The outer peripheral surface 56 is a short cylindrical surface continuous with the lower edge of the base end side of the support ring 30 and is different from the outer peripheral surface where the thinned portion 50 and the column portion 52 exist in that the thinned portion 50 is not thinned. Yes. The outer peripheral surface 56 is flush with the outer peripheral surface constituting the column part 52. Although the height of the outer peripheral surface 56 is sufficiently shorter than the height of the thinned portion 50, the length is not limited as long as it can be stably gripped when the preform 10 is handled. If a preferable example is given, the height of the outer peripheral surface 56 is 1 mm or more and 2 mm or less.

The thinned portion 50 is mainly formed on the outer peripheral surface of the vertical portion 48, and a part thereof also reaches the outer peripheral surface of the curved portion 46. The depth of the lightening portion 50 (that is, the amount of lightening) can be constant over the height direction, or can be made smaller in the curved portion 46 than in the vertical portion 48 as shown in FIG. it can. However, it is preferable that the thickness of the lightening portion 50 gradually decreases as it goes downward. More preferably, the amount of lightening of the lightening portion 50 is larger as the portion is closer to the support ring 30, gradually decreases as the distance from the support ring 30 increases, and continues to the outer peripheral surface of the body portion 40 without a step. Eventually disappear. By carrying out like this, since preform 10 becomes difficult to burst while performing biaxial stretch blow molding, the moldability to plastic bottle 1 is securable.

Although not described in detail, the lightening portion 32 on the mouth portion 12 side can be formed in the same manner as the lightening portion 50 on the preform main body portion 14 side. For example, the total number of the lightening portions 32 is eight, and the columnar portions 60 are spaced apart from each other and arranged in a line-symmetric manner at equal intervals in the circumferential direction, so that the cross-sectional shape can be an arc shape. However, preferably, in the circumferential direction, the size and the size of the lightening portion 32 in consideration of the lightening portion 50 so that the position of the lightening portion 32 and the position of the lightening portion 50 are aligned with the support ring 30 as a boundary. It is good to form the space | interval of the adjacent lightening

parts

32 and 32. FIG. If formed in this way, the strength of the upper and lower portions of the support ring 30 is balanced in the circumferential direction, and the fluidity of the resin and the removal of the mold are improved.

An example of the manufacturing process of the plastic bottle 1 will be described.
First, using a mold, polyethylene terephthalate is injected into the mold, and the preform 10 is injection-molded. After injection molding, the mold is opened, the preform 10 is taken out, and set in a blow molding machine. In the blow molding machine, only the preform main body portion 14 of the preform 10 is heated, and the preform main body portion 14 is stretched in the vertical direction by the stretching rod, and the preform main body portion 14 is laterally blown by blowing compressed air. Stretch in the direction. Thereby, the shoulder part 3, the trunk | drum 4, and the bottom part 5 are shape | molded. On the other hand, the mouth 12 becomes the mouth 2 while maintaining the size and shape as it is, and a series of molding of the plastic bottle 1 is completed.

Here, when the preform main body portion 14 is stretched, the lightening portion 50 and the column portion 52 are stretched until there is no boundary between them (that is, a step), and constitute the upper portion of the shoulder portion 3. . For this reason, in the upper part of the shoulder portion 3, the thinned portion 50 existing in the preform 10 disappears. Therefore, if it sees as the plastic bottle 1, it will become unclear whether the preform 10 for the manufacture has used the one having the lightening portion 50.

The operational effects of the preform 10 of the present embodiment described above will be described.

1. In view of the reduction in the amount of resin and the strength of the preform main body portion 14, the thinned portion 50 is partially formed in the lower portion of the support ring 30 that has not been stretched and remains thick. The amount of resin (amount of polyethylene terephthalate) used for the preform 10 can be reduced. Moreover, compared with the case where the whole thickness of the lower part of the support ring 30 is made thin, a strength fall can be suppressed. In particular, since the thinned portions 50 are formed at equal intervals, the strength of the lower portion of the support ring 30 is well balanced in the circumferential direction, and the amount of resin is reduced in consideration of strength.

2. From the viewpoint of moldability of the preform When the preform 10 is injection-molded, the thinned portions 50 are formed at equal intervals, so that the injected resin flows in a well-balanced manner. Moreover, since the thinned portion 50 is formed in an arc-shaped cross section, it is easy to ensure the fluidity of the resin. Furthermore, since the thinned portion 50 has such an aspect, after injection molding, the product (preform 10) can be easily extracted from the mold used for injection molding, and molding defects are unlikely to occur. Therefore, the moldability of the preform 10 can be maintained well, and the productivity of the plastic bottle 1 can be improved.

3. From the viewpoint of handling Since an outer peripheral surface 56 having no irregularities is formed between the thinned portion 50 and the support ring 30, the preform 10 and the plastic bottle 1 are stabilized by using the outer peripheral surface 56 and the support ring 30. Can be handled. Thereby, the handleability at the time of handling the preform 10 and the plastic bottle 1 can be ensured appropriately.

Modification of the Embodiment The structure of the preform 10 described above can be modified as appropriate without departing from the scope of the present invention. For example, the number of the lightening portions 50 is not limited to eight and may be two or more. It is also possible to form the thinned portion 50 not on the outer peripheral surface of the neck portion 44 but on the inner peripheral surface of the neck portion 44. However, from the viewpoint of ease of die removal of the mold, it is preferable to form it on the outer peripheral surface.

1: plastic bottle, 10: preform, 12: mouth part, 14: preform body part, 24: outer peripheral surface, 26: thread, 28: bead ring (second circumferential ring part), 30: support ring (Circumferential ring part), 32: lightening part, 40: body part, 42: bottom part, 44: neck part, 46: curved part, 48: vertical part, 50: lightening part, 52: pillar part

Claims

A plastic bottle comprising a mouth portion and a bottomed cylindrical preform body portion extending from the mouth portion, and the preform body portion is stretched without stretching the mouth portion by biaxial stretch blow molding In the preform molded into
The preform main body portion has a plurality of lightening portions formed at equal intervals in the circumferential direction of the preform at a portion which is a boundary portion with the mouth portion and is stretched by biaxial stretch blow molding. It is a preform.
The mouth portion has a circumferential ring portion having a diameter larger than that of the preform main body portion in a portion defining a boundary with the preform main body portion,
The preform main body portion has a cylindrical outer peripheral surface without unevenness that is continuous with the lower end of the circumferential ring portion, and the outer peripheral surface that is continuous with the lower end of the cylindrical outer peripheral surface without unevenness. The preform according to claim 1, wherein a thinned portion is formed.
The preform according to claim 2, wherein a height of the cutout portion is larger than a height of the cylindrical outer peripheral surface without the unevenness.
The said lightening part has a large amount of lightening as the site | part close | similar to the said circumferential ring part, and as it distances from the said circumferential ring part, the amount of lightening reduces gradually and it finally lose | disappears. Preforms.
The mouth portion has a second circumferential ring portion on the upper side of the circumferential ring portion, and has a thread on the upper side of the second circumferential ring, and the circumferential ring portion and the first The outer peripheral surface between the two circumferential ring portions is formed with a plurality of lightening portions at the same equal intervals as the plurality of lightening portions in the preform main body portion. The preform according to one item.
The preform according to any one of claims 1 to 4, wherein a cross-sectional shape of the lightening portion is an arc shape.