JPS6396022A - Panel wall for deformation of bottle body - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to the structure of a panel wall for vacuum absorption formed in the body of a polyethylene terephthalate resin bottle that is biaxially stretched and blow-molded. In other words, C exhibits great durability against increased pressure inside the tank, but relates to a panel wall structure that easily and uniformly deforms when the pressure inside the tank decreases.

[Conventional technology]

The biaxial stretch blow molded bottle made of polyethylene terephthalate resin (hereinafter simply referred to as PET) is heat treated (heat cent) after the biaxial stretch blow molding to improve the heat resistance of the bottle itself, and to improve the heat resistance of the bottle itself. It is known that heat-resistant bottles can be used to fill and store liquids such as beverages that require high-temperature filling.

However, this type of pET bottle does not have high rigidity like glass bottles or metal fM bottles, but it is flexible, so the structure of the bottle is probably a normal one. When filled at high temperature, the body of the tank will be improperly deformed due to the internal contraction of the liquid inside the tank and the drop in stem pressure in the head space, which will cause the body to deform and seriously impair the appearance of the product. Put it away.

Therefore, this type of PET bottle is designed with almost flat vertically long panel walls for absorbing reduced pressure installed parallel to each other in the body. By absorbing the deformation through the deformation of the panel wall, the shape of the deformed bottle is made to have an appearance that does not give any impression of abnormality.

Pressure and stress acting on the panel walls of the bottle made of heat-resistant PET are the pressure and stress that is applied to the panel walls of the bottle when filling with high-temperature contents. The liquid pressure due to the height difference between the liquid level and the liquid filled in the bottle is released to atmospheric pressure immediately after filling, and when capping, the internal pressure rises due to headspace vapor pressure ( For example, 90°C
When the bottle is filled with liquid, the internal pressure of the bottle becomes approximately 1,7149 k+r/cJ due to the pressure increase caused by the steam, and during tumble sterilization, the pressure gradually decreases from the state at the time of capping due to slow cooling in the atmosphere. During cooling, a decrease in pressure occurs due to a decrease in the volume of the liquid content and a decrease in pressure in the head space, and deformation stress is generated in response to these pressure changes.

In this way, the panel wall is not only heated by the liquid content, but also subjected to pressure changes such as the above-mentioned pressurization (during filling and capping), normal pressure (immediately after filling), and reduced pressure (during cooling). Due to the steam pressure and the heat of the content liquid during filling and capping, the panel wall is in a high temperature and pressurized state, and is pushed outward and deformed in a convex shape compared to when sliding.

[Problem that the invention seeks to solve]

According to many experiments, when the temperature of the filled liquid is below 80°C, the generated pressure is relatively low and the degree of temperature increase in the bottle is also small, so the allowable stress of the bottle itself is still large. , the tendency of the panel wall to deform into a convex shape is relatively small, and the shadow of this convex deformation ζT of the panel wall hardly appears after cooling.
When the temperature exceeds .degree. C., the generated internal pressure becomes high, and the degree of convex deformation of the panel wall after capping becomes large.

This convex deformation on the panel wall is due to the filling liquid temperature and
= Under the influence of the vapor pressure mentioned above, the decrease in the strength of the bottle material and the residual strain occur together. (C) There is a forward direction (F which remains as permanent strain).

The panel walls installed on conventional bottles of this type are made as flat as possible over the entire area in order to achieve uniform deformation.
In order to reduce convex deformation, it is constructed with an inclined surface, in order to cause convex deformation and ffi, ff< However, in reality, as mentioned above, the filling liquid temperature was 85°.
In the case of C and above, the convex deformation that inevitably occurs on the panel wall becomes large due to the thermal influence of the filling liquid temperature and the influence of the vapor pressure, resulting in residual strain (permanent deformation) when cooled. The panel wall, which has been permanently deformed into a convex shape, is no longer able to function as a normal panel wall and the decompression absorption effect has disappeared, resulting in the entire body of the bottle becoming irregularly shaped into a triangular or oval shape. The appearance of the bottle was deteriorated due to deformation or failure of the panel wall to absorb and deform under reduced pressure.

A detailed examination of the permanent deformation that occurred in this panel wall revealed that
The bending angles of the two bent parts of the stepped part that is bent and formed around the panel wall in order to recess form the panel wall change in opposite directions, resulting in a value that is different from the angle at the time of forming. There was found.

The change in the bending angle of the two bends in this step is caused by the action of the filling liquid temperature and vapor pressure described above causing deformation in the two bends that changes the degree of bending in opposite directions. This is probably due to permanent deformation due to exceeding the allowable stress range, but if the step section deforms in this way, the entire panel wall will remain deformed in a convex shape, and will collapse smoothly to absorb the reduced pressure. It becomes impossible to transform.

Furthermore, it is known that the structure of the panel wall is flat, which is less prone to convex deformation due to increased pressure during capping, and conversely more likely to deform concave due to reduced pressure during cooling. If a flat structure is used, permanent deformation will occur in the stepped portion as described above, making it impossible to obtain normal decompression absorption deformation.Even if decompression absorption deformation is possible, this Because it is not possible to specify and stabilize the mode of action of the stress that acts on the panel wall due to reduced pressure, it is not possible to obtain a constant and stable deformation progress, and as a result, the degree of deformation that absorbs the reduced pressure differs between each panel wall. This resulted in an abnormal appearance on the outside of the bottle.

In addition, the simplest method is 11', which does not leave convex deformation in the panel wall as a permanent deformation! The first stage can be achieved by increasing the heat setting effect on the bottle, but in order to increase the heat setting effect, it is necessary to increase the heat setting temperature and increase the time to 14 degrees. , the productivity will be significantly reduced, and it is not practical, and in this way, even if the deformation for vacuum absorption of the panel wall is applied, it is not possible to uniformly generate deformation for vacuum absorption of the panel wall. However, the problem of poor appearance due to non-uniform deformation remains unsolved.

The present invention prevents permanent deformation of stepped portions due to increased pressure when the basic structure of the panel wall is a heavily used structure, and the deformation due to reduced pressure is constant and uniform on each panel wall. The technical challenge is to make it occur.

[Means for solving problems]

The means according to the invention comprises biaxially stretched blow-molded PET
In the panel wall 3 vertically arranged in parallel on the body 2 of the bottle body (see Fig. 1), on the imaginary center line M (see Fig. 2) along the long side of this panel wall 3. At least a pair of ridgeline step portions 3c are provided extending in the transverse direction with the apex 3d which is the bending point located at 3a
, the height difference of the ridge line step portion 3c is increased to 1. O+lIn or less, and the plane portion 3a is located at the center in the longitudinal direction.

[Effect]

Every time the ridgeline stepped portion 3c with the apex 3d positioned on the center line M is formed, reduced pressure acts on the panel wall 3 and stress for deformation is generated, and this stress is applied along the ridgeline stepped portion 3c. 41 acts on the apex 3d, and because of this, the panel wall 3 is deformed to absorb the reduced pressure from the location where the apex 3d is located.

By locating the flat portion 3a between the pair of ridge step portions 3c, when the stress for decompression deformation concentrates on the apex 3d, the flat portion 3a receives deformation force at both upper and lower ends of the center. As a result, decompression absorption deformation in the flat portion 3a is caused smoothly, reliably, and always in a constant state.

Since the flat portion 3a is located at the center in the longitudinal direction, deformation for absorbing reduced pressure occurs at the center of the panel wall 3. Therefore, the deformation for absorbing reduced pressure that occurs in the panel wall 3 is It occurs as a whole, without bias, and in a certain order.

Since the level difference of the ridgeline step 3c is set to 1.0+u+ or less, the wall cross-sectional structure has a narrow interval between the two bent portions forming the ridgeline step 3c, so that the pressure action due to pressure increase and decrease and the filling Despite the effect of liquid temperature, the wall cross-sectional structure extending down to this ridge line step portion 3c is difficult to deform.

-9= Therefore, even if the pressure increase and filling liquid temperature during capping act on this ridgeline stepped portion 3c, the ridgeline stepped portion 3c will not be permanently deformed, and a convex permanent deformation of the panel wall 3 will occur. Never.

Also, due to the presence of the ridgeline stepped portion 3c, the flat portion 3a is connected to the surrounding portion, that is, the deformed portion 3b (see FIG. 2), which is another portion of the panel wall 3, during biaxial stretch blow molding of the bottle 1. Since it becomes difficult to receive the residual stress from part 4,
During heat-set molding, the flat dimensional accuracy of the panel wall 3 is increased, and it is possible to suppress the increase in flavor variation due to high-temperature filling of the molded bottle 1, making it possible to produce bottles of higher quality each time. can.

〔Example〕

Standard biaxial stretch blow-molded PET bottle body 2 with a capacity of 1.51 and a body 2 wall thickness of 0.33 to 0.3511
The relationship between the level difference and the deformation of the stepped portion 5 of the panel wall 3 to be recessed was varied, and the relationship between the stepped portion 5 and the deformation was determined by filling a specified amount of 90°C hot water, turning for 30 seconds after gear soaping, and then standing upright. So 5
An experiment was conducted by leaving it for 30 seconds and then cooling it to room temperature with cold water. When the step difference at the 0th step was 2.01, the bulging deformation of the panel wall 3 after capping was large, and the deformation of the step due to this deformation was considered to be permanent deformation. This resulted in poor deformation during cooling.

When the level difference at the 0th step is 1.2 mm, the panel wall 3 will normally bulge and deform after capping, but the deformation of the step due to this deformation becomes permanent deformation and the panel wall 3 absorbs decompression during cooling. It didn't happen smoothly.

When the step difference at the 0th step is 1.0 mm, the bulging deformation of the panel wall 3 after capping is relatively small, and the degree of permanent deformation of the step due to this deformation is also small, so that the depressurization of the panel wall 3 that occurs during cooling is The absorption deformation did not become so non-uniform as to impair the appearance of the bottle 1.

When the step difference at the 0th step is 0.7 mm, the expansion deformation of the panel wall 3 after capping is small, and this deformation causes almost no permanent deformation of the step. Therefore, the decompression absorption deformation of the panel wall 3 during cooling occurs. (:lAchieved very smoothly and uniformly.

When the step difference at the 0th step is 0.5+nl, it is almost the same as when the step is 0.7 mm, and the amount of deformation of the panel wall 3 during capping is about the same, but as permanent deformation occurs at the step. There was absolutely no deformation of the panel wall 3 due to its absorption of reduced pressure, and the deformation of the panel wall 3 was achieved extremely smoothly and uniformly.

I was able to get the following results.

From this experimental result, it can be confirmed that the difference in level of the step provided in the panel wall 3 that needs to be deformed to absorb reduced pressure needs to be 1.01 or less.

Further, the flat portion 3a formed on the panel wall 3 is the main part that stabilizes the deformation form of the panel wall 3, but according to many experiments, the size of the flat portion 3a is as follows. Approximately one-fourth of the entire panel wall 3 is suitable.

Furthermore, the ridge line step portion 3c for concentrating the stress generated in accordance with the external pressure acting on the panel wall 3 on the apex 3d needs to be inclined with respect to the center line M for this purpose. The angle of inclination of this ridgeline stepped portion 3c, that is, the angle of the apex 3d, is preferably about 30 to 140 degrees;
If it is less than °, the degree of concentration of the generated stress on the vertex 3d will become too strong, and the deformation in the flat part 3a will be close to bending deformation, and the deformation will tend to concentrate on the flat part 3a. On the other hand, if the angle is 140° or more, the degree of concentration of the generated stress on the vertex 3d is poor, and the effect of making the deformation of the panel wall 3 uniform is reduced.

In the embodiment shown in FIGS. 2 and 3, the apex 3d is located at a point dividing the length of the long side of the panel wall 3 into three equal parts, and the angle of the apex 3d is set to about 80°, and the ridge step part This shows the case where a step of 3c is formed with Q of 7mm.

In the case of this embodiment, the convex deformation due to the pressure increase during canoping is mainly achieved in the 1ζ deformation part 3b, and the flat part 3a
Although the amount of convex deformation was small, during the decompression absorption deformation, the flat part 3a was greatly depressed and deformed, and the deformed part 3b was also greatly curved and deformed by being pulled by the depressed deformation of the flat part 3a. Panel wall 3-12- The deformed shape was constant throughout.

In the embodiment shown in FIGS. 4 and 5, the planar portion 3a of the embodiment shown in FIGS. A bending line portion 3g having a bending point at the second apex 3f is formed, and a part of the deformation portion 3b is tilted upward toward the step portion 5 by this bending line portion 3g to form a curved wall structure. It is molded in the part 3e.

In the case of this embodiment, the bulging deformation of the deformable portion 3b due to the pressure increase during capping is suppressed, thereby reducing the bulging deformation of the entire panel wall 3 during capping,
There is no permanent deformation at all in the stepped portion 5 that forms the boundary between the panel wall 3 and the rib portion 4, and stress concentration during decompression absorption deformation occurs at both ends of the flat portion 3a and the deformed portion 3b.
The deformed portion 3
The deformation form of b can be made constant, and more stable decompression absorption deformation of the panel wall 3 can be obtained.

〔Effect of the invention〕

As is clear from the above description, the present invention suppresses the amount of deformation of the par 14 = wall during pressure increase, and conversely increases the amount of deformation during depressurization and smoothes the occurrence of deformation due to pressure reduction. This makes it possible to maintain the appearance of the bottle well, and by having a ridge line step with a small step, it is possible to improve the J' law specificity of a flat panel wall during heat cent molding. As a result, it is possible to almost eliminate variations in flavor during high-temperature filling, making it possible to form bottles of higher quality.Furthermore, in this way, the deformation of the panel wall to absorb the reduced pressure is smooth and constant. Since it is stable and stable, it has many excellent effects such as being able to obtain a bottle that exhibits higher heat resistance.

[Brief explanation of the drawing]

FIG. 1 shows an overall external view of a large bottle made of polyethylene terephthalate I resin, which is generally biaxially stretched and blow-molded, in which the present invention is carried out. 2 and 3 show an embodiment of the present invention, with FIG. 2 being a front view thereof and FIG. 3 being a sectional view taken along the center line. 4 and 5 show another embodiment of the present invention, with FIG. 4 being a front view thereof and FIG. 5 being a sectional view taken along the center line. Explanation of symbols 1; Bottle body, 2; Body part, 3; Panel wall, 4; Rib part, 5;
Stepped portion, 3a; flat portion, 3I]; deformed portion, 3c; ridgeline stepped portion, 3d; apex, 3e; deformation auxiliary portion, 3fi second apex,
3g: Bent line part, M: Center line. Applicant: Yoshino Kogyo Co., Ltd.

Claims (1)

[Claims] The body part (2) of the polyethylene terephthalate resin bottle (1) that has been subjected to biaxial stretch blow molding has a vertically elongated shape that deforms in response to pressure changes within the bottle (1) and absorbs the pressure changes. This is a structure of panel walls (3) for reducing pressure absorption installed in parallel with each other, with the apex (3d) that is the bending point located on the imagined center line (M) along the long side, and the short side at least a pair of ridgeline step portions (3c) extending transversely in the direction;
The depressed part in between is a flat plane part (3a), the step of the ridge step part (3c) is set to a value of 1.0 mm or less, and the plane part (3a) is located at the center in the longitudinal direction. A panel wall for transforming the bottle body.