JP5273558B2 - Synthetic resin housing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress the deformation, thermal crystallization, or the like caused by heat accumulation of a neck ring of a synthetic resin bottle made by biaxial draw-blow molding. <P>SOLUTION: The synthetic resin bottle made by biaxial draw-blow molding has the neck ring projecting circumferentially in an outer flange shape from the outer circumferential surface of the circumferential wall of a mouth-to-neck portion. The neck ring is provided with an empty-walled portion that is formed to extend upward in a circumferential groove shape from the inner circumference of the lower end face of the neck ring, and with a number of rib pieces that traverse the inside of the empty-walled portion in the direction of the bottle radius to connect the circumferential wall of the mouth-to-neck portion to the outer circumference of the neck ring. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

The present invention relates to a synthetic resin casing made by biaxial stretch blow molding, and more particularly, to a structure of a neck ring portion disposed on the mouth and neck of the casing.

  Conventionally, polyethylene terephthalate (hereinafter referred to as PET) resin biaxially stretched blow-molded housings, so-called PET bottles, have excellent transparency, mechanical strength, heat resistance, gas barrier properties, etc., and are used for various beverages. Widely used as a container.

  In many cases, a neck ring portion is disposed on the mouth and neck of the plastic bottle. And in the transport process and heat treatment process of preform which is a precursor of PET bottle, biaxial stretch blow molding process, transport process of PET bottle itself, filling process of content liquid, capping process, etc., it is arranged in each process equipment The support part is supported by a method of supporting the neck ring part from above or below, a method of holding it from above and below, and a method of supporting both using the neck ring part and the tube wall of the mouth and neck part. The remodeling or the frame is supported in a certain posture.

  For example, Patent Document 1 describes an invention relating to a structure of a neck ring portion related to a capping process, and a neck ring portion 103 disposed on a mouth-and-neck portion 102 as shown in FIG. A method is described in which a support portion 51 is brought into contact with and supported by the end surface 111 from below. Further, FIG. 6B shows a method of supporting by using the support portion 51 using both the neck ring portion 103 and the cylindrical wall 102 p of the mouth and neck portion 102.

On the other hand, the biaxial stretch blow molding method for PET bottles includes the hot parison method and the cold parison method. The hot parison method is a method in which the preform maintains the preheating of the injection molding and moves to the blow molding process as it is. The parison method is a method in which a preform injection molding process and a blow molding process are separated, and after the preform is cooled once, it is reheated and blow molded.
For example, cited document 2 describes the molding process of the hot parison method described above.

JP 2003-181906 A JP 2000-202897 A

Here, since the processes related to the preform and the casing described above are continuously performed at a high speed and in large quantities, it is necessary to surely and smoothly support the neck ring part by the support part arranged in each process. For this reason, a high degree of dimensional accuracy is required in the neck ring portion and the vicinity thereof (hereinafter referred to as the neck ring portion vicinity portion).
On the other hand, since the portion near the neck ring portion is a relatively thick portion, cooling during the injection molding of the preform is not sufficient, so-called heat accumulation, and due to this heat accumulation, the portion near the neck ring portion Various problems may occur, including deformation.

In particular, in the hot parison method in which the preheating of the injection molding is maintained and the process proceeds to the blow molding process as it is, problems such as the deformation of the vicinity of the neck ring portion due to heat accumulation are more serious.
In the case where the casing is made of PET resin, a problem arises in that thermal crystallization proceeds due to heat accumulation, whitening progresses, and transparency is impaired.
In the case of the hot parison method, blow molding is performed by connecting a blow mold for blow molding under the lip mold for molding the neck and neck by injection molding while maintaining the preheating of the injection molding. As a result, there is a problem that the resin that is still in a soft state flows in the gap between the lip mold and the blow mold, and a large step is formed immediately below the lower end of the neck ring. .

The present invention was made in view of the problem related to the neck ring portion of the synthetic resin casing by biaxial stretch blow molding, and the problem is that the neck ring portion is deformed due to heat accumulation in the neck ring portion. Furthermore, it is to suppress problems such as thermal crystallization.

Of the means for solving the above problems, the main configuration of the present invention is as follows.
In a synthetic resin casing by biaxial stretch blow molding,
The neck ring part protrudes from the outer peripheral surface of the peripheral wall of the mouth-and-neck part in the shape of an outer collar,
In the neck ring part, while forming a thinned part in a circumferential groove shape upward from the inner peripheral side portion of the lower end surface of the neck ring part,
A large number of rib pieces that connect the peripheral wall of the neck and neck and the outer peripheral side portion of the neck ring are disposed across the hollow portion in the radial direction of the neck and neck.

With the above configuration, by forming a hollow portion in the neck ring portion, it is possible to suppress heat accumulation caused by the neck ring portion vicinity portion being thick in the molding of the preform,
Effectively suppresses deformation near the neck ring due to molding shrinkage, whitening due to heat accumulation in the PET resin housing, and resin flow into the gap between the lip mold and the blow mold in the hot parison method. It becomes possible.

On the other hand, when the thinned portion is formed, a so-called thermal dripping phenomenon is caused in which the outer peripheral side portion of the neck ring portion remaining in an umbrella shape outside the thinned portion loses support and hangs inward. Moreover, since the rigidity as a neck ring part becomes low, the problem that a neck ring part will deform | transform when it supports in a support part at each process also arises.
Further, in the blowing process, the peripheral wall of the mouth and neck portion located inside the lightening portion is easily deformed into a bulging shape without any support, resulting in a problem that the dimensional accuracy in the vicinity of the neck ring portion is lowered.

Therefore, the neck ring is arranged by arranging a large number of rib pieces that connect the peripheral wall of the neck and neck portion and the outer peripheral side portion of the neck ring portion by traversing the inside of the neck portion in the radial direction with the above configuration. It is possible to effectively suppress the above-described problems caused by the formation of the thinned portion in the portion.
That is, the housing having the main configuration of the present invention is formed by forming a thinned portion in the neck ring portion and disposing a rib piece in the thinned portion,
This eliminates the problems of mold shrinkage, whitening, and resin flow to the mold connection part due to heat accumulation in the vicinity of the neck ring part and effectively suppresses deformation in the vicinity of the neck ring part. It is possible to achieve a high degree of dimensional accuracy in the vicinity of the part.

  Another configuration of the present invention is that, in the above main configuration, biaxial stretch blow molding is a hot parison method.

In the hot parison method that maintains the preheating of the injection molding and moves directly to the blow molding process, the occurrence of heat accumulation and the deformation in the vicinity of the neck ring portion are more serious than the cold parison method. By arranging a rib piece in this cutout portion and forming
Not only in the case of using the cold parison method, but also in the hot parison method, the problem of molding shrinkage, whitening, or resin flow to the mold connection portion due to heat accumulation in the vicinity of the neck ring portion is solved, and the neck It is possible to effectively suppress deformation in the vicinity of the ring portion and achieve high dimensional accuracy in the vicinity of the neck ring portion.

Since the synthetic resin casing of the present invention has the above-described configuration, the following effects are exhibited.
That is, by forming a thinned portion and disposing a rib piece in the thinned portion, molding shrinkage and whitening due to heat accumulation in the vicinity of the neck ring portion, even in a case by a hot parison method In addition to eliminating the problem of resin flow to the mold connecting part, it is possible to achieve high dimensional accuracy in the vicinity of the neck ring part by effectively suppressing deformation in the vicinity of the neck ring part. Processes such as conveyance, filling, and capping using the ring unit can be performed with high productivity.

It is a front view which shows partially one Example of the synthetic resin casings of this invention. It is a plane sectional view shown by an arrow along the AA line in FIG. (A) is the BB line in FIG. 2, (b) is a longitudinal cross-sectional view of the mouth-neck part vicinity shown by an arrow along CC line. It is a longitudinal cross-sectional view of the mouth-neck part vicinity shown similarly to FIG. 3 about the comparative example of the shape of a neck ring part. It is a longitudinal cross-sectional view of the mouth-neck part vicinity shown similarly to FIG. 3 about the other comparative example of the shape of a neck ring part. It is explanatory drawing which shows the example of the support method of the housing using a neck ring part.

Hereinafter, an embodiment of a synthetic resin casing of the present invention will be described along examples, with reference to the drawings.
1 to 3 show an embodiment of the synthetic resin casing of the present invention, FIG. 1 is a partially front view, and FIG. 2 is an arrow view along the line AA in FIG. FIG. 3 is a longitudinal sectional view in the vicinity of the mouth and neck, (a) is a line BB in FIG. 2, and (b) is an arrow view along the line CC. Is.
This casing 1 is formed by a hot parison method in a biaxial stretch blow molding method made of PET resin, and a cylindrical mouth and neck portion 2 is erected on the upper end of a tapered cylindrical shoulder portion 4. It is a thing.

In addition, a neck ring portion 3 is provided in a circumferentially protruding manner from the outer peripheral surface at a substantially central height position of the mouth and neck portion 2. Hereinafter, the structure of the neck ring portion 3 will be described.
The vicinity of the neck ring portion 3 is formed to be relatively thick, and particularly heat buildup occurs in the molding process by the hot parison method, but in the neck ring portion 3 of the present embodiment, in order to eliminate this heat buildup, A thinned portion 12 is formed in a circumferential groove shape upward from the inner peripheral side portion of the lower end surface 11 of the neck ring portion 3.

  Further, in this embodiment, as can be seen from the longitudinal sectional view of FIG. 3, the inner peripheral edge of the thinned portion 12 corresponds to the outer peripheral surface of the cylindrical wall 2p of the mouth-and-neck portion 2, and the outer peripheral edge is inclined downward and outward. It is an inclined surface. Accordingly, the outer peripheral side portion 3a of the remaining neck ring portion 3 is arranged in an umbrella shape outside the outer peripheral surface of the cylindrical wall 2p.

A large number of rib pieces 13 cross the radial direction of the mouth-and-neck portion 2 and connect the peripheral wall 2p of the mouth-and-neck portion 2 and the outer peripheral side portion 3a of the neck ring portion 3 (this embodiment). 12) and the like are arranged at a central angular position. (See Figure 2)
Here, in FIG. 3 (a), a casing using the neck ring portion 3 and the peripheral wall 2p of the mouth-and-neck portion 2 by a support portion 51 disposed in an apparatus such as a transporting process, a filling process, or a capping process. 1 shows an example of a method for supporting 1.
In this example, as shown in FIG. 6B, the support 1 is brought into contact with the lower end surface 11 of the neck ring portion 3 and the outer peripheral surface of the peripheral wall 2p of the mouth-and-neck portion 2 to keep the casing 1 constant. It is to support the attitude.
Of course, the method of supporting such a case is based on the method as shown in FIG. 6B and the neck ring at the support portion 51 as shown in FIG. A method of supporting the lower end surface 11 of the portion 3, a method of supporting the neck ring portion 3 from above with the support portion 51, a method of sandwiching the neck ring portion 3 from above and below, and the like can be selected as appropriate.

Next, FIG. 4A is a longitudinal sectional view in the vicinity of the mouth neck portion 2 shown in the same manner as FIG. 3 for a comparative example of the shape of the neck ring portion 3, which shows the shape of the conventional neck ring portion. Is.
If the neck ring portion 3 has a conventional shape as described above, the portion near the neck ring portion 3 becomes relatively thick as described above, so that it is surrounded by a two-dot chain line in FIG. Since this region becomes the heat accumulation region Rh, when it is made of PET resin as in this embodiment, thermal crystallization proceeds and whitens.
Also, in the hot parison method, the resin flows into the gap between the lip mold and the blow mold mold connecting portion, and a large step S is formed immediately below the neck ring portion 3 as shown in FIG. End up. If the step S is formed in this way, it becomes difficult to reliably and smoothly achieve the support by the support portion 51 as shown in FIG. 3A, resulting in a line trouble and a decrease in productivity. End up.

Next, FIG. 5 shows another comparative example of the shape of the neck ring portion 3, in which the thinned portion 12 is formed in the neck ring portion 3 of the comparative example of FIG.
In this example, the formation of the hollow portion 12 is intended to suppress the occurrence of heat accumulation, which can prevent whitening due to the heat accumulation, and the flow of the resin to the gap of the mold connecting portion described above. This can be effectively prevented, and the step S seen in the comparative example of FIG. 4 can no longer be seen.

However, on the other hand, by forming the thinned portion 12, the phenomenon that the outer peripheral side portion 3a of the neck ring portion 3 hangs down obliquely as shown by the white arrow in the figure, and further, during blow molding, A phenomenon in which the cylindrical wall 2p of the neck portion 2 expands and deforms as indicated by a two-dot chain line in the drawing occurs in a portion from the position where the neck ring portion 3 is disposed to the lower portion. When thermal dripping or expansion deformation occurs in this way, it becomes difficult to reliably and smoothly achieve support by the support portion 51 as shown in FIG. 3A, resulting in line trouble and reduced productivity. Resulting in.
Further, there is a concern that the rigidity of the neck ring portion 3 is lowered due to the formation of the lightening portion 12.

In this respect, in the neck ring portion 3 of the casing 1 of the embodiment shown in FIGS. 1 to 3, the above-described neck ring portion 3 is provided by arranging a large number of rib pieces 13 in the portion where the thinned portion 12 is formed. The size of the neck ring portion 3 and the vicinity of the neck ring portion 3 including the cylindrical wall 2p can be effectively suppressed from the thermal dripping phenomenon of the outer peripheral side portion 3a and the expansion deformation of the cylindrical wall 2p of the mouth and neck portion 2. The accuracy can be maintained at a high level, and the support by the support portion 51 as shown in FIG. 3A can be achieved reliably and smoothly, and the productivity can be achieved at a high level.
Of course, the neck ring portion 3 of this embodiment can eliminate the heat accumulation phenomenon by forming the thinned portion 12 to prevent whitening due to the heat accumulation, and to the gap of the mold connecting portion. The flow of the resin can be effectively prevented.

As mentioned above, although embodiment of this invention and its effect were demonstrated along the Example, embodiment of this invention is not limited to the said Example.
In the above embodiment, the biaxial stretch blow-molded casing formed by the hot parison method has been described. However, the configuration according to the neck ring portion of the present invention is also effective by the cold parison method. That is, although not as remarkable as the hot parison method, the deformation near the neck ring due to heat accumulation may be a problem depending on the shape near the mouth and neck and the thickness.
In the above embodiment, the case made of PET resin has been described. However, the structure of the present invention is also effective for biaxially stretched blow-molded cases made of other resins such as polypropylene.

As described above, the synthetic resin casing of the present invention effectively suppresses problems such as deformation and whitening of the neck ring part even if it is a biaxially stretched blow molded product of the hot parison method. A wide range of applications in various applications is expected by taking advantage of the productivity in the filling process due to the high dimensional accuracy of the neck ring.

DESCRIPTION OF SYMBOLS 1; Housing 2; Mouth-and-neck part 2p; Tube wall 3 of (mouth-neck part); Neck ring part 3a; Rib piece 51; support portion 102; mouth and neck portion 102p; peripheral wall 103; neck ring portion 111; lower end surface Rh;

Claims (2)

Synthetic resin casing by biaxial stretch blow molding, wherein the neck ring part (3) protrudes from the outer peripheral surface of the peripheral wall (2p) of the mouth neck part (2), In the neck ring portion (3), a thinned portion (12) is formed in a circumferential groove shape upward from the inner peripheral side portion of the lower end surface (11) of the neck ring portion (3), and the thinned portion (12) A rib piece (13) that connects the peripheral wall (2p) of the mouth neck portion (2) and the outer peripheral side portion of the neck ring portion (3) across the inside in the radial direction of the mouth neck portion (2). ), A synthetic resin casing. The synthetic resin casing according to claim 1, wherein the biaxial stretch blow molding is a hot parison method.

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