WO2012002184A1

WO2012002184A1 - Plastic bottle and preform

Info

Publication number: WO2012002184A1
Application number: PCT/JP2011/063974
Authority: WO
Inventors: 松岡　建之
Original assignee: ザ・コカ－コーラ・カンパニー
Priority date: 2010-07-02
Filing date: 2011-06-17
Publication date: 2012-01-05
Also published as: JP5683852B2; TW201233592A; JP2012012101A

Abstract

A plastic bottle and a perform formed by two-axis stretch blow molding have a non-crystalline mouth section having improved heat resistance and reduced weight which are simultaneously achieved without requiring a change in an existing manufacturing facility or with a minimum change in the facility. The non-crystalline mouth section of a bottle has a screw thread section with which a cap is engaged and also has a bead section which is located below the screw thread section. The screw thread section and the bead section are formed on the outer peripheral surface of the mouth section so as to protrude therefrom, the outer peripheral surface extending from the top surface of the mouth section. At least in the range from the top surface to the upper end of the bead ring, the inner diameter of the mouth is in the range of 21 mm - 22 mm inclusive and the outer diameter of the mouth is in the range of 25 mm - 26 mm inclusive. The height of the thread of the screw thread section is in the range of 0.7 mm - 1.1 mm inclusive.

Description

Plastic bottles and preforms

The present invention relates to a mouth structure of a plastic bottle and a preform.

Conventionally, as a plastic bottle typified by a PET bottle, a plastic preform formed by injection molding or the like is manufactured by biaxial stretch blow molding, and its mouth is sealed with a screw by a cap. Many are used (see, for example, Patent Documents 1 to 4). As the mouth of this kind, it is known that the resin remains amorphous, and the resin is crystallized (whitened) to improve heat resistance. The former amorphous type is mainly filled with aseptic filling. The latter crystallization type is mainly used for hot filling. Crystallization type bottles are also used as bottles for heating and selling contents in vending machines and stores.

The structure of the mouth portion of the plastic bottle and the preform is generally formed of a threaded portion, a bead ring, and a support ring on the outer peripheral surface, regardless of whether the type is amorphous or crystallized. And as shown below, between both types, while making the outer diameter of a mouth part common, the inner diameter of a mouth part is mutually different (refer patent document 1).

<Amorphous type mouth>
Inner diameter: 21.74 mm ± 0.13 mm
Outer diameter: 24.94mm ± 0.13mm
<Mouth of crystallization type>
Inner diameter: 20.6mm ± 0.13mm
Outer diameter: 24.94mm ± 0.13mm

As can be seen from the above dimensional relationship, conventionally, when the necessary thickness is formed in the mouth, the position of the inner peripheral surface of the mouth is adjusted in the radial direction, so that the heat generated by the crystallization process (heat treatment) The crystallization type mouth is made thicker than the non-crystalline mouth so that deformation and filling and thermal deformation during heating sales do not occur.

Patent Document 1 proposes another dimension for the non-crystalline type mouth, based on the above general dimensions. Specifically, focusing on the problem that the phenomenon of inversion occurs when the non-crystalline type mouth of the above dimensions is left in a high temperature environment such as 37 ° C., as a solution to the problem, non-crystalline type It has been proposed to reduce the inner diameter of the lip portion until it becomes equal to the inner diameter of the crystallization type mouth portion (that is, 20.6 mm ± 0.13 mm).

この According to this proposed solution, the thickness of the mouth increases. As a result, it has the effect of improving the mechanical strength and heat resistance, and is considered effective against the internal fall phenomenon. Moreover, such an effect is effective not only in the case of using for the above-mentioned heating sales application, but also in the case where Patent Document 2 points out, that is, when the non-crystalline type mouth is used as a hot filling application It seems to be. In addition, since the inner diameter of the non-crystalline type mouth is equal to the inner diameter of the crystallization type mouth, there is no need to change the mandrel for transporting the preform between the two types of mouth. This is also advantageous.

JP 2004-338789 A JP 2008-37492 A (paragraph 0004 etc.) JP-A-9-239852 Japanese Patent Laid-Open No. 5-92475

In recent years, it has been studied to use a non-crystalline type mouth for a warm sale product or a hot filling product. This is because, by adopting the non-crystalline type mouth in the bottle, the crystallization process in the preform manufacturing can be omitted, the dimensional stability is improved, and the cost reduction effect is produced.
Further, from the viewpoint of resource and cost saving, there is a demand for lighter plastic bottles, and more specifically, a reduction in the amount of resin used for preforms.

In this regard, Patent Document 1 adopts an amorphous type mouth as a bottle, but does not consider any reduction in the amount of resin. Actually, in the above-mentioned solution described in Patent Document 1, the inner diameter of the amorphous type mouth is uniformly reduced in the entire region in the height direction in order to ensure the thickness of the mouth. The method of uniformly setting the value does not lead to any reduction in the amount of resin.

However, in order to reduce the amount of resin, it is conceivable to partially reduce the inner diameter of the non-crystalline type mouth. However, since the mandrel has a structure that depends on the inner diameter of the mouth portion, a mandrel is separately required to cope with such a partially changed inner diameter.

Therefore, the present invention provides a plastic bottle and a preform that can achieve both improvement in heat resistance and weight reduction while requiring no change to existing manufacturing equipment or minimizing the non-crystalline type mouth. The purpose is to provide.

As a result of diligent study, the present inventor changed the conventional idea of reducing the inner diameter of the mouth part to increase the thickness of the amorphous type mouth part, and a new idea of increasing the outer diameter of the mouth part. Recalling that, from the viewpoint of the strength of the existing mouth and the relationship with the cap, the inventors have found that the above-described object can be achieved with the configuration described later, and have completed the present invention.

That is, the plastic bottle of the present invention is a plastic bottle formed by biaxial stretch blow molding, and has a mouth that is not crystallized and is sealed by a cap. An outer peripheral surface extending from the surface and an inner peripheral surface extending from the top surface. On the outer peripheral surface, a threaded portion into which the cap is screwed and a bead ring projecting below the threaded portion are formed. . And at least in the range from the top surface to the upper end of the bead ring, the inner diameter of the mouth portion is 21 mm or more and 22 mm or less, the outer diameter of the mouth portion is 25 mm or more and 26 mm or less, and the thread portion is the height of the thread. Is 0.7 mm or more and 1.1 mm or less.

The preform of the present invention is biaxially stretch blow molded to obtain a plastic bottle having a non-crystallized mouth that is sealed by a cap. It has the same structure and dimensions as the mouth of the bottle.

According to the plastic bottle and preform of the present invention, at least in the range from the top surface to the upper end of the bead ring, the inner diameter of the mouth is a conventional amorphous type mouth (inner diameter: 21.74 mm ± 0.13 mm, outer Since the diameter includes an inner diameter of 24.94 mm ± 0.13 mm), it is not necessary to minimize or change to existing manufacturing equipment (for example, a mandrel). On the other hand, since the outer diameter of the mouth exceeds the outer diameter of the conventional amorphous type mouth, the heat resistance is improved as compared with the conventional amorphous mouth.

In addition, according to the present invention, it is possible to reduce the weight in consideration of the strength of the entire mouth portion as compared with the case where the dimension of the inner diameter is constant throughout the height direction as in Patent Document 1.
More specifically, according to the knowledge of the present inventor, the site where the bead ring exists is higher in strength than the site where it does not exist. For this reason, as in Patent Document 1, it is not necessary to set the inner diameter of the portion where the bead ring exists in the same manner as the other portions so as to increase the thickness.
On the other hand, the present invention sets the outer diameter dimension to be thicker than the conventional one at least in the range from the top surface to the upper end of the bead ring. Therefore, since it is possible to adopt the same dimensions as those in the past for the portion where the bead ring exists, it is possible to reduce the weight while ensuring the strength of the entire mouth portion.

Furthermore, according to the present invention, the height of the thread at the mouth is 0.7 mm or greater and 1.1 mm or less, which is smaller than the height of the conventional thread (generally 1.245 mm). Thereby, weight reduction can be attained compared with the case where the dimension of an outer diameter is enlarged with the height of a screw thread being the conventional dimension.

Here, if the height of the screw thread is made small, it is assumed that the screwing property of the cap to the mouth and the sealing property at the time of screwing are concerned. In this regard, according to the knowledge of the present inventor, compared to the clearance between the thread diameter on the conventional mouth side and the thread valley diameter on the cap side, the thread valley diameter on the conventional mouth side and the cap valley diameter on the cap side are compared. It has been found that the clearance between the thread diameter is large (this point, for example, clearly shown in FIG. 1 of Patent Document 2). According to the knowledge of the present inventor, it has been confirmed that even if the large clearance is slightly reduced, the screwability and the sealing performance are not impaired. Therefore, the weight reduction which considered screwing property and sealing performance can be achieved by setting it as the above-mentioned dimension range (0.7 mm or more and 1.1 mm).

According to a preferred aspect of the present invention, the cap has a screw portion that is screwed into the screw portion of the mouth portion, and when the mouth portion is closed by the cap, the thread valley diameter of the screw portion of the mouth portion. And the screw thread diameter of the threaded portion of the cap is preferably 0.8 mm or less.

This aspect is in view of the above-mentioned knowledge of the present inventor, and the clearance that has been relatively large conventionally becomes small.

According to a preferred aspect of the present invention, R of the corner portion connecting the top surface and the outer peripheral surface is preferably 0.8 mm or more and 2.0 mm or less.

According to this aspect, it becomes larger than the value of R in the conventional corner portion (generally around 0.5 mm). Thereby, when there exists an outer ring in a cap like the existing cap, an outer ring becomes easy to open outside at the time of screwing of a cap to an opening. Therefore, even when the outer diameter of the mouth portion is increased as compared with the conventional case as described above, it is possible to provide a structure that can easily ensure the screwability and sealing performance with the cap.

According to a preferred aspect of the present invention, the screw portion of the mouth portion may be formed at a position 2 mm or more away from the top surface.

According to this aspect, since the mold used for manufacturing the molded body (preform) before biaxial stretch blow molding can be given a thickness, there is an advantage that the durability of the mold is improved.

According to a preferred aspect of the present invention, the screw portion of the mouth portion may be continuous in a spiral shape without having an intermittent portion on the outer peripheral surface.

According to this aspect, it is possible to improve the strength of the screw part particularly against heat compared to a screw part with a so-called vent slot. Therefore, it is effective to improve heat resistance in the amorphous type mouth.

According to a preferred aspect of the present invention, a support ring may be formed on the outer peripheral surface so as to protrude below the bead ring. And regarding the outer diameter of the mouth, the range from the top surface to the upper end of the bead ring is preferably smaller than 0.5 mm as compared to the range from the lower end of the bead ring to the upper end of the support ring.

It is a front view of the plastic bottle which concerns on embodiment. It is a front view of the preform used for manufacture of the plastic bottle of FIG. It is a front view which expands and shows the opening | mouth part of the plastic bottle of FIG. It is sectional drawing which shows the opening | mouth part of FIG. 3 with the dimension. FIG. 4 is a half sectional view showing a state in which the mouth portion of FIG. 3 is closed with a cap. It is a half sectional view showing the state where the mouth part concerning a comparative example was closed with the cap.

A plastic bottle according to a preferred embodiment of the present invention will be described with reference to the accompanying drawings.

As shown in FIG. 1, a plastic bottle 1 (hereinafter referred to as “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 bottle 1 may be a food such as a carbonated beverage or a sauce.

The bottle 1 is formed by biaxially stretching blow-molding the preform 100 shown in FIG.
An example of the manufacturing process of the bottle 1 will be described. First, using a mold, a thermoplastic resin is injected into the mold, and the preform 100 is injection molded. Examples of the thermoplastic resin include polyethylene, polypropylene, and polyethylene terephthalate. The preform 100 includes a mouth portion 102 having the same shape as that of the mouth portion 2 and a bottomed cylindrical portion 104 connected to the lower side of the mouth portion 102. After the injection molding of the preform 100, the mold is opened, the preform 100 is taken out and set in a blow molding machine. In a blow molding machine, only the tubular portion 104 of the preform 100 is heated, the tubular portion 104 is stretched in the vertical direction by a stretching rod, and compressed air is blown to stretch the tubular portion 104 in the lateral direction. Then, the shoulder portion 3, the body portion 4 and the bottom portion 5 are formed. Thereby, a series of shaping | molding of the bottle 1 is completed. Thereafter, the beverage is filled, and the mouth portion 2 as a spout is closed by the cap 6 (see: FIG. 5).

In this embodiment, the mouth portion 102 of the preform 100 is not crystallized, and thus has the same shape as the mouth portion 2 of the bottle 1. Therefore, the entire bottle 1 including the mouth 2 is made of a non-crystallized resin, does not require a crystallization step, and has excellent transparency. The non-crystallized state refers to a state where the crystallinity is less than 20%. Further, the crystallinity can be measured by a known measurement method such as a density method. In the following, the mouth 2 will be described in detail, but it goes without saying that the description also applies to the mouth 102.

3 and 4, the mouth portion 2 has a cylindrical peripheral wall 10 having an upper end opened. The peripheral wall 10 includes a top surface 11 constituting an upper end surface, an outer peripheral surface 12 extending from the top surface 11, and an inner peripheral surface 14 extending from the top surface 11. The top surface 11 is made of a flat surface, for example. On the outer peripheral surface 12, a screw portion 16, a bead ring 18, and a support ring 20 are formed so as to protrude from the top surface 11 side. On the other hand, the inner peripheral surface 14 extends without a step in the vertical direction. That is, the inner peripheral surface 14 is configured as a straight surface in a range from the top surface 11 to the lower end of the support ring 20.

The thread portion 16 may employ a double thread or a triple thread, but is preferably composed of a single thread that is less loose and has high strength. Moreover, the reinforcement effect of the circumferential direction can be acquired by setting it as the continuous single thread | thread, and a thermal deformation can be prevented. The thread of the thread portion 16 is not formed with a vent slot (intermittent portion), and as a whole, one height continues in the length direction in a spiral shape. Each of the bead ring 18 and the support ring 20 protrudes outward from the screw portion 16 and is formed on the outer peripheral surface 12 in the circumferential direction. In addition, the bead ring 18 and the support ring 20 mean the rib which protruded cyclically | annularly on the outer peripheral surface 12, and are the concepts containing the site | parts (for example, flange part etc.) named by another expression.

As shown in FIG. 5, the cap 6 is a so-called screw cap. The cap 6 may be one that does not have tamper evidence (tamper-opening display function), but here, an example having tamper evidence is described.

The cap 6 has a cap body 30 and a tamper evidence band 32. The cap body 30 includes a disk-shaped lid portion 36 that covers the upper portion of the mouth portion 2, and a cylindrical portion 38 that covers the side of the mouth portion 2. The tamper evident band 32 is connected to the lower end of the cylindrical portion 38 via a detachable bridge 42. A tab 44 is formed on the lower inner surface of the tamper evident band 32 so as to face upward, and the tab 44 is engaged with the outer peripheral surface 12 between the bead ring 18 and the support ring 20.

The cylindrical part 38 of the cap body 30 is a part that hangs down from the periphery of the lid part 36 in a skirt shape. A threaded portion 50 is formed on the inner peripheral surface of the cylindrical portion 38 to be screwed into the threaded portion 16 of the mouth portion 2. On the inner surface of the lid portion 36, an outer ring 52, an inner ring 54, and a small protrusion 56 are formed to protrude between the rings. The outer ring 52 extends from the lid portion 36 with a slight gap from the inner peripheral surface of the cylindrical portion 38, and its cross-sectional shape is arbitrary, but here is formed in a reverse trapezoidal shape in front view. The inner ring 54 is longer on the inner diameter side than the outer ring 52 and longer than the outer ring 52, and extends from the lid portion 36. The inner ring 54 has an arbitrary cross-sectional shape. Here, the inner ring 54 is formed in a shape extending slightly from the lid portion 36 toward the outer diameter side and then bending toward the inner diameter side. The small protrusions 56 are formed in a ring shape like the outer ring 52 and the inner ring 54, but the protruding amount is smaller than that of the outer ring 52 and the inner ring 54.

When the cap 6 shown in FIG. 5 is closed, the screw portion 50 and the screw portion 16 are screwed together, and the small protrusions 56 come into contact with each other so as to be pressed against the top surface 11. The outer ring 52 is in contact with the straight surface of the outer peripheral surface 12 from below the corner portion connecting the top surface 11 and the outer peripheral surface 12. On the other hand, the bent portion of the inner ring 54 contacts the inner peripheral surface 14. In this way, the mouth portion 2 is sealed by the cap 6 so that the upper end portion is sandwiched in the radial direction.

On the other hand, when the cap 6 is rotated in the opening direction in this sealed state, the bridge 42 is broken, and the tamper evident band 32 is separated from the cap body 30 and falls onto the upper surface of the support ring 20. The tamper-evident band 32 after dropping faces the bead ring 18 with a slight gap therebetween, and is held by the support ring 20 and the bead ring 18 so as not to be easily removed in the vertical direction.

Here, the characteristic dimensions of the mouth portion 2 will be described with reference to FIGS.

1. The inner diameter (port inner diameter) of the inner

diameter

port portion 2 is 21.74 mm ± 0.13 mm. This dimension is the same as the inner diameter of a general amorphous type mouth distributed in the current market. For this reason, when manufacturing the bottle 1 which has the mouth part 2, it is useful at the point which can utilize the manufacturing equipment for manufacturing the bottle which has a general non-crystalline type mouth part. More specifically, the same non-crystalline type preform and preform 100 of the present embodiment can be used for the mandrel for transporting the preform in the manufacturing facility. Thus, since it is not necessary to change the existing manufacturing equipment, such as no need to change the shape of the mandrel, the production efficiency of the bottle 1 can be increased while maintaining the formability of the bottle 1.

In addition, since the inner peripheral surface 14 is a straight surface, the inner diameter of the mouth portion 2 is constant in the range from the top surface 11 to the lower end of the support ring 20.

2. Outer diameters of opening 2 can be divided into two extraoral diameter and band size. The outer diameter of the mouth is the outer diameter of the straight surface at the upper end of the mouth 2. Here, the outer diameter of the mouth is constant in the range from the top surface 11 to the upper end of the bead ring 18, and the length is 25.62 mm ± 0.13 mm. On the other hand, the band diameter is the outer diameter of the straight surface in the range corresponding to the tamper evident band 32, that is, in the range from the lower end of the bead ring 18 to the upper end of the support ring 20. The length of the band diameter is constant in the height direction and is 25.71 mm ± 0.13 mm.

Here, the size of the band diameter is the same as the band diameter of a general amorphous type mouth. For this reason, an existing cap having tamper evidence can be used to close the mouth 2.

On the other hand, the dimension of the mouth outer diameter is larger than the mouth outer diameter (24.94 mm ± 0.13 mm) of a general amorphous type mouth. For this reason, the thickness of the mouth portion 2 (3.88 mm = 25.62 mm-21.74 mm) is within a range from the top surface 11 to the upper end of the bead ring 18 (see FIG. 3). 2 mm = 24.94 mm-21.74 mm). Thereby, the mechanical strength and heat resistance of the mouth part 2 of the present embodiment are improved as compared with a general amorphous type mouth part.

3. The thread diameter and the thread diameter of the thread height mouth portion 2 mean the diameter of the thread of the thread portion 16, and the length is 27.43 ± 0.13 mm. The thread diameter dimension is the same as the thread diameter of a general amorphous type mouth. Therefore, the thread diameter is a dimension that can ensure the versatility of the existing cap.

On the other hand, the height of the thread is a value obtained by subtracting the outer diameter of the mouth from the thread diameter and dividing by 2, that is, 0.905 ± 0.13 mm (= (27.43-25.62) × 1/2 ± 0). .13 mm). The height of this thread is 1.245 ± 0.13 mm (= (27.43-24.94) × 1/2 ±) of the thread height of a general amorphous type mouth 2 ′. 0.13 mm).

Here, the general non-crystalline type mouth 2 'and the cap 6' are fitted as shown in FIG. In FIG. 6, the configuration corresponding to the configuration of the mouth portion 2 of the present embodiment is denoted by “′”, and the description thereof is omitted.

As shown in FIG. 6, the clearance G ₁ ′ between the thread valley diameter of the mouth portion 2 ′ and the screw thread diameter of the cap 6 ′ is equal to the screw thread diameter of the mouth portion ₂ ′ and the thread valley diameter of the cap 6 ′. Is more than twice as large as the clearance G ₂ ′. For example, G ₁ ′ is set to 0.87 mm, and G ₂ ′ is set to 0.21 mm.

On the other hand, in the present embodiment, as shown in FIG. 5, the clearance G ₁ between the thread valley diameter of the mouth portion 2 and the thread diameter of the cap 6 is equal to the thread diameter of the mouth portion 2 and the cap 6. is only slightly greater clearance or G ₂ and the the same degree, or from which between the screw root diameter. Here, G ₂ has the same dimensions (0.21 mm) as G ₂ ′, but G ₁ is set to 0.32 mm. The reason why G ₁ is smaller than G ₁ ′ is that the mouth 2 of the present embodiment has a mouth outer diameter larger than that of a general non-crystalline type as described above, so that This is because the structure is filled.

As described above, the general point of view of making the general amorphous type clearance G ₁ ′ as small as the clearance G ₁ of the present embodiment is that the versatility of the existing cap can be ensured even if it is reduced in this way. This is based on what the inventor found. Therefore, according to the mouth portion 2 of the present embodiment, the screw diameter is the same as that of a general non-crystalline type mouth portion 2 ', but the screw thread height is lower than this. There is no need to interfere with the screwability of the existing cap 6 with respect to the portion 16 and the sealing performance of the cap 6 when closed.

4). R at corner
The corner portion connecting the top surface 11 and the inner peripheral surface 14 has an R of 0.3 mm, which is the same as a general amorphous type mouth 2 '.
On the other hand, the corner portion connecting the top surface 11 and the outer peripheral surface 12 has R of 1.2 mm. The dimension of R is larger than R (0.58 mm) of a general amorphous type mouth 2 ′. By enlarging in this way, when the cap 6 is screwed, the lower end of the outer ring 52 is easily opened outward when it comes into contact with the corner portion on the outer peripheral surface 12 side. In other words, since the thickness of the mouth portion 2 of the present embodiment is larger than that of a general amorphous type mouth portion 2 ′, if R on the outer peripheral surface 12 side is as small as 0.58 mm, When the cap 6 is screwed, the lower end of the outer ring 52 is difficult to escape outward. In order to solve this problem, the mouth portion 2 has a configuration in which R on the outer peripheral surface 12 side is increased to 1.2 mm so as to easily secure screwability and sealing performance with the cap 6.

In addition, in FIG.5 and 6, the mode of the outer rings 52 and 52 'at the time of sealing is shown typically. Specifically, in the general amorphous type mouth portion 2 ′ shown in FIG. 6, the lower end of the outer ring 52 ′ is inclined toward the inner diameter side. On the other hand, in the amorphous type mouth portion 2 of the present embodiment shown in FIG. 5, the lower end of the outer ring 52 is pushed outward in the radial direction by the upper portion of the outer peripheral surface 12 and extends in the vertical direction. This is because, as described above, the upper end portion of the mouth portion 2 of the present embodiment is thicker than the upper end portion of a general amorphous type mouth portion 2 ′.

In addition, although R of the outer peripheral surface 12 side was set to 1.2 mm, it is not restricted to this dimension. R on the outer peripheral surface 12 side is preferably 0.8 mm or more and 2.0 mm or less, and among them, the balance between the action of escaping the lower end of the outer ring 52 and the action of contacting the outer ring 52 to ensure the sealing performance. In view of this, the most preferable is 1.2 mm. On the other hand, if it is less than 0.8 mm, the action of escaping the lower end of the outer ring 52 becomes insufficient. On the other hand, if it exceeds 2.0 mm, the contact area of the mouth part 2 with respect to the outer ring 52 decreases, so that the sealing performance is improved. There may be a shortage.

5. The screw part 16 of the start position mouth part 2 of the screw part is formed at a position away from the top surface 11 by 2.59 mm or more. That is, the screw thread start position of the screw portion 16 on the top surface side 11 side is 2.59 mm from the top surface 11. This dimension is larger than the dimension (1.70 mm) of a general amorphous type mouth 2 '. By doing so, the mold used for manufacturing the preform 100 can be made thick, and the durability of the mold can be improved. Further, it is possible to avoid the influence of sink marks or the like at the time of molding the bottle screw portion 16 that occurs on the inner surface of the inner ring 54 interference portion of the cap 6 and to improve the sealing performance.

Specifically, when the preform 100 of the present embodiment is manufactured using a mold similar to a mold for manufacturing a general amorphous-type preform with a mouth, the mold becomes thin. End up. Therefore, among the molds for manufacturing the preform 100 of the present embodiment, as a mold corresponding to the mouth part 2, for example, a mold that opens in a lateral direction (a direction orthogonal to the axial direction of the mouth part 2), and the mold When using a mold that is set on the upper side of the mold and opens upward (one direction in the axial direction of the mouth portion 2), the thickness of the latter mold is increased because the screw thread starting position is far from the top surface 11. It can be used.

In addition, although the screw thread start position of the mouth part 2 was set to 2.59 mm from the top surface 11, it is not restricted to this dimension. Considering the dimension (1.70 mm) of the general amorphous type mouth portion 2 ′ and the mold surface, the screw thread starting position of the mouth portion 2 is preferably 2 mm or more and 3 mm or less from the top surface 11. This is because if it exceeds 3 mm, the straight surface at the upper end of the outer peripheral surface 12 is too long, and the screwability and sealing performance with the cap 6 can be sacrificed.

The effect of this embodiment is demonstrated.
As described above, according to the mouth portion 2 of the present embodiment, not only the existing mandrel can be used, but also the existing cap can be effectively used to secure the screwing property, the sealing property, and the opening / closing property. Moreover, the moldability of the preform 100 can be ensured in consideration of the mold surface, and the heat resistance of the mouth portion 2 can be improved as compared with a general amorphous type mouth portion 2 ′.

As a result of this improvement in heat resistance, the mouth 2 can be prevented from being deformed by heat, so that the bottle 1 having the amorphous mouth 2 can be used as a bottle for a heated product (for example, a vending machine or a store). It is also possible to use it as a bottle that warms and sells the contents. In addition, depending on the type of contents stored in the bottle 1, the use of the bottle 1 having the amorphous type mouth 2 as a hot filling bottle can be expected. In addition, according to evaluation of this inventor, even if it uses the bottle 1 of this embodiment for filling at 70 degreeC (medium temperature filling), it has confirmed that the opening part 2 does not deform | transform by heat.

In addition, according to the mouth part 2 of the present embodiment, it is possible to achieve both improvement in heat resistance and weight reduction in consideration of the strength of the whole mouth part. In detail, in the method of changing the design from a general amorphous type mouth part to a crystallized type mouth part, focusing only on the improvement of heat resistance, as described above, the mouth inner diameter is uniformly narrowed. The thickness of the mouth will be secured. For this reason, the portion where the bead ring and the support ring having relatively high strength exist in the mouth portion is also thickened, and the amount of resin required for the mouth portion as a whole increases.

On the other hand, according to the present embodiment, the outer diameter of the mouth portion 2 is increased to increase the outer diameter of the mouth portion 2 and the thickness of the mouth portion 2 is ensured. No need to thicken. That is, the amount of resin for thickening decreases from the upper end of the bead ring 18 to the lower portion thereof. On the other hand, the part where the bead ring 18 and the support ring 20 are present and the part between them (the part constituting the band diameter) originally have a certain degree of strength. Is secured. Thus, according to this embodiment, the heat resistance of the mouth portion 2 can be improved by increasing the thickness while securing the strength and reducing the weight as a whole.

In addition, if a weight is shown for reference, the weight of the mouth portion 2 of this embodiment (the weight of the portion from the top surface 11 to the lower end of the support ring 20) is 5.4 g. On the other hand, the weight of the mouth of the crystallization type having the inner diameter and the outer diameter described in the background art is 6.4 g.

In addition, since the mouth part 2 of this embodiment is a non-crystallization type, it cannot be overemphasized that the process and installation of a crystallization process become unnecessary. Further, since the crystallization treatment is not performed, the dimensional stability of the mouth portion 2 is improved, and hence the sealing performance with the cap 6 is also improved.

Modification of the Embodiment The structure and dimensions of the mouth portion 2 described above can be appropriately changed without departing from the scope of the present invention. For example, the tolerances of the inner diameter, outer diameter, and thread height of the mouth portion 2 are not limited to the above 0.13 mm. These tolerances may be dimensions such as 0.10 mm and 0.15 mm.

Also, the inner diameter and outer diameter of the mouth 2 are not limited to the above dimensions. In particular, the dimensions of the mouth inner diameter and the mouth outer diameter are determined in a complementary manner in consideration of various factors such as strength required for the mouth portion 2. For example, regarding the inner diameter of the mouth, in view of the circumstances leading to the present invention, it includes a general amorphous type mouth (mouth inner diameter: 21.74 mm ± 0.13 mm), and is a general crystallization type. However, it is not desirable from the viewpoint of weight reduction and existing manufacturing equipment. In view of this point, an appropriate range of the inner diameter of the mouth included in the present invention is 21 mm or more and 22 mm or less.

On the other hand, regarding the outer diameter of the mouth, in view of the circumstances leading to the present invention, it is necessary to exceed the mouth of general amorphous type and crystallization type (outer diameter: 24.94 mm ± 0.13 mm). If the excess amount is small, the strength for heat resistance is not improved. On the other hand, if the amount is too large, it is not desirable from the viewpoint of weight reduction and sealability. In view of this point, when the inner diameter of the mouth is in the range of 21 mm or more and 22 mm or less, an appropriate range of the outer diameter of the mouth included in the present invention is 25 mm or more and 26 mm or less.

Also, the band diameter is not limited to the above dimensions (25.71 mm). According to the above dimensions, the band diameter is 0.09 mm (= 25.71 mm−25.62 mm) larger than the outer diameter of the mouth. In this respect, since the difference between the band diameter and the outer diameter of the mouth is 0.77 mm (= 25.71 mm−24.94 mm) in the general amorphous type and crystallized type mouths, The difference between is considerably reduced. In view of the circumstances leading to the present invention, if the dimensions of the outer diameter of the mouth and the band diameter in consideration of weight reduction are specified, the difference between the two included in the present invention is preferably smaller than 0.5 mm. In this case, the band diameter can be the same as the outer diameter of the mouth, but it is possible to consider the reduction in weight by making the band diameter larger than the outer diameter of the mouth.

The height of the thread of the mouth 2 is not limited to the above dimensions (0.905 mm). As described above, the height of the thread is a value obtained by subtracting the outer diameter of the mouth from the thread diameter and dividing by 2, and is 1.245 ± 0.13 mm for a general amorphous type. Therefore, if the screw thread diameter is 27.43 mm and the outer diameter of the mouth is 25 to 26 mm, the screw thread included in the present invention is considered in consideration of heat resistance, weight reduction and sealability in view of the circumstances leading to the present invention. A reasonable range of the height is 0.7 mm or more and 1.1 mm or less.

For even the clearance G ₁ between the thread root diameter of the mouth portion 2 of the crest diameter and the cap 6 it is not limited to the above dimensions (0.32 mm). In view of the circumstances that led to the present invention, the clearance G _1, the general needs to be smaller than the non-crystalline type of the clearance G _{1 '(0.87mm),} but inhibits too small screw compatibility-sealability There is a fear. In view of this, a reasonable range of the clearance _{G 1} included in the present invention is 0.15mm or 0.8mm or less.

1: Bottle, 2: Mouth, 6: Cap, 11: Top surface, 12: Outer surface, 14: Inner surface, 16: Screw part, 18: Bead ring, 20: Support ring, 100: Preform, 102 : Mouth

Claims

In a plastic bottle formed by biaxial stretch blow molding, the plastic bottle having a non-crystallized mouth sealed by a cap,
The mouth has a top surface, an outer peripheral surface extending from the top surface, and an inner peripheral surface extending from the top surface,
On the outer peripheral surface, a threaded portion to which the cap is screwed and a bead ring projecting below the threaded portion are formed.
At least in the range from the top surface to the upper end of the bead ring, the inner diameter of the mouth is 21 mm or more and 22 mm or less, and the outer diameter of the mouth is 25 mm or more and 26 mm or less,
The screw portion is a plastic bottle having a thread height of 0.7 mm or more and 1.1 mm or less.
The cap has a screw portion that is screwed into the screw portion,
2. The difference according to claim 1, wherein when the mouth portion is sealed by the cap, a difference between a thread valley diameter of the thread portion of the mouth portion and a thread diameter of the thread portion of the cap is 0.8 mm or less. Plastic bottle.
The plastic bottle according to claim 1 or 2, wherein R is 0.8 mm or more and 2.0 mm or less at a corner portion connecting the top surface and the outer peripheral surface.
The plastic bottle according to any one of claims 1 to 3, wherein the screw portion of the mouth portion is formed at a position 2 mm or more away from the top surface.
The plastic bottle according to any one of claims 1 to 4, wherein the thread portion of the mouth portion is continuous in a spiral shape without having an intermittent portion on the outer peripheral surface.
On the outer peripheral surface, a support ring is formed to protrude below the bead ring,
Regarding the outer diameter of the mouth portion, the range from the top surface to the upper end of the bead ring is smaller than 0.5 mm compared to the range from the lower end of the bead ring to the upper end of the support ring. The plastic bottle according to any one of 1 to 5.
A biaxial stretch blow-molded preform to obtain a plastic bottle with a non-crystallized mouth that is sealed by a cap,
The mouth has a top surface, an outer peripheral surface extending from the top surface, and an inner peripheral surface extending from the top surface,
On the outer peripheral surface, a threaded portion to which the cap is screwed and a bead ring projecting below the threaded portion are formed.
At least in the range from the top surface to the upper end of the bead ring, the inner diameter of the mouth is 21 mm or more and 22 mm or less, and the outer diameter of the mouth is 25 mm or more and 26 mm or less,
The thread part is a preform having a thread height of 0.7 mm to 1.1 mm.