JPH0957840A - Manufacture of hollow container - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the pressure resistance and heat resistance of a hollow container by a method wherein a portion selected from a predetermined portion of the bottom part of the container is crystallized by a method wherein a screening plate, which fits to the bottom part of the container and, at the same time, is opened at the portion corresponding to the predetermined portion of the container, is arranged between the bottom part of the container and a heating device. SOLUTION: On a lowermost stage, a bottom plate 7 is provided. In addition, on the bottom plate 7, a heating device 3 is provided. Further, above the heating device 3, a screening plate 3 is provided. The screening plate 3 is made of an aluminum alloy and has an engraving having the same shape as that of the bottom part of a biaxially oriented and blown container 1 and has at least one opening corresponding to the portion selected from among the bottom part central part of the bottom part of the biaxially oriented and blown container, the peripheral part of the bottom part central part, valley line parts, a portion ranging from the edge of the peripheral part of leg parts to a foundation part, a valley part, the outside surface part of the leg parts and the portion at the upper side part of the bottom part. The heat developed from the heating device arranged below the screening plate 2 heats a predetermined portion of the bottom part of the biaxially oriented and blown container 1 for a certain period of time in order to crystallize the predetermined portion of the bottom part of the container 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a pressure- and heat-resistant self-supporting hollow container, and more particularly to a hollow container which has improved pressure resistance and heat resistance during heat sterilization of contents and is also excellent in impact resistance. It relates to a manufacturing method.

[0002]

2. Description of the Related Art Conventionally, as a pressure- and heat-resistant self-standing hollow container, a bottom cup is bulged to form a hemispherical shell in order to enhance the inner pressure resistance of the container body, and a base cup molded into a bottomed cylindrical shape is added to this. The most popular type of container is that it is attached to the container to make it self-supporting. However, the use of the base cup requires that the base cup be separately molded and mounted and fixed.
The weight of the container becomes large and the shape also becomes large, and the heat sterilization of the contents cannot be performed smoothly because the hot water does not reach the bottom of the container sufficiently in the heat sterilization process. -There were various problems such as water being accumulated in the scoop, and it was difficult to drain it quickly.

[0003] Further, from the viewpoint of resource saving and environmental issues, it is desired to effectively reuse used empty containers.
For containers equipped with a base cup, the container body and the base are usually
Since the materials of the scoop and the adhesive are different, when they are reused, they must be separated, and there is a problem that the cost is increased in terms of process.

Due to these problems, a pressure and heat resistant container which does not require a base cup has been desired. Several proposals have been made for pressure-resistant containers that do not require a base cup, and generally, a plurality of legs are radially bulged around the center of the bottom, and valleys are formed between these legs. It is either a structure in which a line portion is formed or a champagne type structure. For example, it is described in JP-B-48-5708, JP-B-59-40693, JP-B-61-9170, JP-A-63-202424 and JP-A-3-43342.

However, although the container described in each of these items can obtain satisfactory performance as a pressure resistant container, it obtains sufficient performance when used as a pressure resistant heat resistant container for performing a heat sterilization process. I can't. That is, in the containers described in the above items, since the unstretched region and the low stretched region exist in the center of the bottom and the periphery of the center, the temperature of the contents during heat sterilization is from 50 ° C to 70 ° C.
When the temperature rises to about 0 ° C, the internal pressure increases and the container material itself easily undergoes creep deformation.
The bottom center part and the unstretched region around the center part and the low stretched region and its peripheral region undergo creep deformation and project,
The container will lose self-sustaining stability.

As a method for solving this problem, for example,
It is conceivable to use the container described in JP-A-5-85535. Since this container is a container in which the center of the bottom is crystallized and the periphery of the center is sufficiently stretched, creep deformation of the bottom can be suppressed to some extent when the internal pressure increases during heat sterilization. However, even in the case of this container, it is difficult to sufficiently stretch the valley line portion formed between the leg portions and a low stretched region remains in the portion, so that the portion creeps during heat sterilization. Deformation causes the bottom to protrude and loses independence stability.

[0007]

As a result of earnest research, the researchers of the present invention have found that a plurality of legs are radially bulged around the center of the bottom, and a valley line is formed between these legs. In the case of a bottom structure with a part formed, it was found that the stress due to the internal pressure was concentrated especially on the bottom center part and the valley line part. It has been found that the creep deformation is large in the partial region, especially in the portion near the center of the bottom of the valley line. In addition to the valley line portion, it was found that the portion from the edge of the peripheral portion of the center portion of the bottom portion of the leg portion to the ground contact portion undergoes creep deformation during heat sterilization and projects to the bottom portion. In addition, it was found that, in the valley line portion, the stretch orientation at the body side end is higher than that at the portion near the center of the bottom portion, but creep deformation is likely to occur. It was also found that the end portion near the bottom upper side surface of the valley line portion and the bottom upper side surface portion are also susceptible to creep deformation and are involved in the deformation of the bottom portion.

The present invention has solved such drawbacks and has a low stretched region at the center of the bottom and a low stretched region and a high stretched region at the valley line where creep deformation easily occurs due to an increase in internal pressure during heat sterilization. The present invention proposes a method of manufacturing a container that effectively crystallizes the upper surface portion of the bottom portion and the like.

[0009]

SUMMARY OF THE INVENTION The present invention is directed to radially bulging a plurality of legs around the mouth and neck, shoulders, torso, and center of the bottom, and between the legs. In a biaxially stretched blow container made of a saturated polyester resin biaxially stretch blow-molded, which comprises a bottom having a self-supporting structure in which a valley line part is formed, a container bottom is fitted between the container bottom and a heating device. And a shielding plate having an opening corresponding to at least one portion selected from the following (A) to (F) is installed, and is selected from (A) to (F) at the bottom of the container. It is a method for producing a pressure- and heat-resistant self-standing hollow container in which the other part is crystallized and the other bottom is not crystallized. (A) Center part of bottom part (B) Peripheral part of center part of bottom part (C) Valley line part (D) Part from edge of said peripheral part to ground contact part (E) Valley part (F) Outside leg part Upper surface of the surface and bottom

Hereinafter, the present invention will be described in detail. In the present invention, a device that generates heat can be used as the heating device, and specifically, an infrared heater, hot air, an infrared lamp, a quartz tube heater, a high frequency heating device, or the like can be used. Further, it goes without saying that a heat source other than this can be used. Further, these heat sources can be used in combination.

In the present invention, the material of the shielding plate is not particularly limited, but specifically, a metal such as aluminum, iron, copper or an alloy thereof, a heat resistant resin, a ceramic or the like can be used. It suffices if the heat source can be shielded to a specific portion on the bottom of the container.

The saturated polyester resin used in the hollow container of the present invention is preferably a thermoplastic polyester resin whose main repeating unit is ethylene terephthalate, and the thermoplastic polyester resin contains a homopolymer of polyethylene terephthalate as a main component.

As the thermoplastic polyester resin, a part of the terephthalic acid component is, for example, isophthalic acid,
Aromatic dicarboxylic acids such as naphthalene dicarboxylic acid, diphenyl dicarboxylic acid, diphenoxyethane dicarboxylic acid, diphenyl ether dicarboxylic acid, diphenyl sulfone dicarboxylic acid; alicyclic dicarboxylic acids such as hexahydroterephthalic acid and hexahydroisophthalic acid; adipic acid, sebacine Acids, aliphatic dicarboxylic acids such as azelaic acid; those copolymerized by substituting one or more other difunctional carboxylic acids such as P-β-hydroxyethoxybenzoic acid and oxyacids such as ε-oxycaproic acid. Can be used.

In the thermoplastic polyester resin, a part of the ethylene glycol component is used, for example, trimethylene glycol, tetramethylene glycol, hexamethylene glycol, decamethylene glycol, neopentylene glycol, diethylene glycol, 1,1-cyclohexanedimethylol. , 1,4-cyclohexanedimethylol, 2,2 (4'-β-hydroxyethoxyphenyl)
It may be a copolymer obtained by substituting one or more polyfunctional compounds of other glycols such as sulfonic acid and functional derivatives thereof for copolymerization.

The thermoplastic polyester resin used in the container of the present invention preferably has an intrinsic viscosity of 0.7 to 1.0, particularly preferably 0.75 to 0.9.

Further, the saturated polyester resin used in the present invention may appropriately contain additives such as colorants, heat deterioration inhibitors, antioxidants, ultraviolet absorbers, antistatic agents, antibacterial agents and lubricants. .

The shield plate of the present invention has a shape that fits with the bottom of the container and has an opening at a portion corresponding to at least one portion selected from (A) to (F) of the container bottom. Is. Among the combinations (A) to (F), the combination of (B) and (C), the combination including (B) and (C) and (E), and the combination of (B), (C) and ( A combination including F) is preferred, and (D)
Can be combined as needed. The shield is
It preferably has a shape that fits with the bottom of the container.
In (A) to (F), at least a part of each region may be opened. It is also possible to use two or more kinds of shield plates having different combinations of opening portions. By using a plurality of shielding plates, the selected portions (A) to (F) at the bottom can be crystallized stepwise.

In the present invention, the parts (A) to (F) are
This is the bottom of the container. The (A) bottom center is, for example, a portion indicated by 31A in FIG. 10, (B) the peripheral portion of the bottom center is a portion indicated by 31B in FIG. 10, and the (C) valley line portion is It is a band-shaped portion formed between the leg portions and is, for example, a portion indicated by 31C in FIG.
(D) The portion extending from the peripheral edge of the center of the bottom portion to the ground contact portion refers to the portion indicated by 31D in FIG. 10, for example. (E)
The valley portion is a region sandwiched by the ground contact portion of the leg portion, the outer side surface portion of the leg portion, and the valley line portion, and for example, 31E in FIG.
Means the part indicated by. (F) The outer side surface portion and the upper side surface portion of the bottom portion of the leg portion refer to a portion indicated by 31F in FIG. 10, for example. The shielding plate of the present invention may be one in which at least a part of the parts (A) to (F) is opened.

Next, the present invention will be concretely described with a manufacturing apparatus. In FIG. 1, the basic configuration is that the bottom plate 7, the heating device 3 is installed on the bottom plate 7, and the shielding plate 2 is installed above the bottom plate 7. This shielding plate has the same engraving as the shape of the bottom of the biaxially stretched blow container 1, and the bottom of the biaxially stretched blow container has (A) the center of the bottom, (B) the periphery of the center of the bottom, and (C) the valley line. Part, (D) part from the edge of the peripheral part of the leg part to the ground contact part, (E) valley part, (F)
The shield plate is made of an aluminum alloy and has an opening corresponding to at least one portion selected from the outer surface portion of the leg portion and the upper surface portion of the bottom portion. Further, a shield plate support plate 6 for supporting the shield plate 2, a container support plate 5 for supporting the biaxially stretched blow container 1 installed above the support plate 22A, an upper plate 4 installed above the container support plate 4, and an upper plate 4. The container lifting / loading cylinder 8 supported, the container pressure loading cap pressing plate / container supporting plate 10 for connecting the container lifting / loading cylinder 8 and the container supporting plate 5, and the bottom plate 7 are erected upright. It comprises a shield plate support plate 6, a container support plate 5, and a support column 9 for supporting the upper plate 4.

During crystallization of the bottom of the container, the surface temperature of the surface of the shielding plate which is in contact with the biaxially stretched blow container is preferably below the glass transition point of the saturated polyester resin. During crystallization of the bottom of the container, the surface temperature may be a temperature below the glass transition point of the saturated polyester resin,
The temperature may or may not be adjusted. For example, a method in which the surface temperature is set to about room temperature before crystallization and then crystallization is performed without cooling can be used. When the crystallization is continuously performed, the shielding plate may not be cooled during the heating of the bottom of the container, but may be discharged during the crystallization of the next container after the container is discharged. The temperature of the shielding plate may be raised at the same time as the heating, as long as it is below the glass transition temperature of the saturated polyester resin. When temperature control is performed during crystallization, for example, as the shielding plate, a temperature control medium tube or a temperature control pipe connected to a temperature control pipe provided for temperature control can be used. In the present invention, it is convenient and preferable to install the cooling water pipe on the side of the bottom of the container, but it is also possible to install it on other parts.

The heat generated by the heating device installed below the shielding plate is transmitted from the opening of the shielding plate to the bottom of the biaxially stretched blow container, and a specific portion of the bottom is heated for a certain period of time, whereby the bottom of the container is heated. A specific portion can be crystallized. The size of this opening is set so that a desired crystallization range can be obtained. At this time, the shielding plate can be temperature-controlled by the temperature-adjusting medium. At the bottom of the container other than the opening, heat transfer can be controlled by temperature control, so that crystallization can be adjusted. At this time, the surface temperature of the surface of the shielding plate that is in contact with the biaxially stretched blow container is preferably a temperature not higher than the glass transition point of the saturated polyester resin.

The shield plate has a shape that fits with the bottom of the container. At the time of fitting, it is preferable that the shield plate and the bottom of the container are in contact with each other, but a gap may be provided as long as a portion other than a desired portion is not crystallized. Further, in order to improve the degree of adhesion, a method of manufacturing by pressing can be used.
When the container is installed on the container support plate at a position substantially corresponding to the engraving on the shield plate, when the bottom part is inserted into the shield plate, the container rotates so that the bottom part matches the shape of the shield plate, The bottom of the container and the shield can be fitted well.

When crystallizing the bottom of the container, internal pressure may or may not be applied to the biaxially stretched blow container.
In the case of manufacturing by applying internal pressure, as shown in FIG. 2, the apparatus includes a container internal pressure load cap 11 to be mounted on the mouth / neck portion 21 of the container and a compressed air supply for supplying compressed air for applying internal pressure to the container. Packing 1 for preventing the compressed air sent into the tube 12 and the container from leaking from the mouth / neck portion 21.
3 Compressed air having an arbitrary pressure can be fed into the container from the compressed air feeding tube 12 to apply an internal pressure.

The opening of the shielding plate used for crystallization of the bottom of the container can be selected by combining the portions corresponding to the portions (A) to (F), and if necessary, two or more kinds of shielding plates can be selected. Can be used. Further, it is sufficient that the opening of the shielding plate does not correspond to all the corresponding portions and at least a part thereof can be crystallized.

The heating time in the present invention varies depending on the heat source, but is generally 20 seconds to 5 minutes. Preferably 3
0 seconds to 3 minutes. When using two or more types of shielding plates, the heating time for one shielding plate can be set to 20 seconds or less.

In the crystallization of the bottom portion in the manufacturing apparatus of the present invention, the bottom portion heat treatment can be continuously performed by sequentially using a plurality of shielding plates, and the treatment can be performed online.

In the present invention, by crystallizing a specific part of the bottom of the hollow container, the chemical resistance to the lubricant used in the conveyor line of the filling factory can be improved and the occurrence of stress cracks can be suppressed. be able to.

[0028]

The present invention will be described in detail below with reference to examples. Example 1 Polyethylene terephthalate (IV = 0.85) was injection-molded to obtain a bottomed cylindrical preform. The mouth / neck portion 21, the support ring 22A, and the lower support ring 22B of this preform were heated by an infrared heater to be crystallized. After reheating this bottomed tubular preform, it was placed in a blow mold and biaxially stretch blow molded to obtain a hollow container. Next, between the bottom of this hollow container and the infrared heater (heating device), (A) bottom center, (B) bottom center periphery, (C) valley line part, (D) leg part An aluminum alloy that has a shape that fits with the bottom of the container by opening a portion from the edge of the peripheral portion to the grounding portion and a portion corresponding to a part of the (E) valley portion, and is cooled by cooling water. A shielding plate (shown in FIGS. 4 and 5) made of metal is installed, the bottom of the container is fitted with the shielding plate, and the portions (A), (B), (C), (D) and (E) are Crystallization was performed by heating to obtain a hollow container 1B (volume: 1.5 liter) shown in FIG. Hollow container 1
As shown in FIG. 6, the bottom portion of B has a self-supporting structure in which five legs swell radially around the center portion at equal intervals and valley lines are formed between the legs. (A) bottom center part, (B) bottom center part, (C) valley line part,
(D) The part from the edge of the peripheral part of the leg part to the ground contact part and (E) part of the valley part were crystallized.

In this hollow container 1B, at 5 ° C., 2.
After filling with 5 gas volumes of carbonated water and capping, a hot water shower at 70 ° C. was applied for 30 minutes. Then, shower with water at 20 ° C for 10 minutes to cool,
The total height of the bottle and the deformation rate of the body diameter were measured. As a result, the deformation rate of the total height of the hollow container is 1.6%, and the deformation rate of the body diameter is
It was 0.9%. Next, when the 12 filled containers were dropped upright onto the concrete from a height of 1.0 m, there was no breakage in the bottom of all the containers.

Example 2 In Example 1, as the preform, the one under the support ring was heated by an infrared heater to be crystallized, and the mouth / neck part was relieved of stress and strain by heating. 7 and the shielding plate shown in FIG. 8 is used, (A) bottom center part of the biaxially stretched blow container container, (B) bottom center part periphery part, (C) valley line part, (D) leg part periphery Heating the periphery from the edge of the part to the grounding part, (E) part of the valley part, and (F) the outer surface part of the leg part and the end of the valley line part that is part of the upper side surface part of the bottom, It crystallized. As shown in FIGS. 9, (a) and (b), the bottom of the obtained container has five legs bulging radially at equal intervals around the center and valleys between the legs. It has a self-supporting structure in which a line portion is formed, and (A) the central portion of the bottom portion, (B) the peripheral portion of the central portion of the bottom portion,
(C) valley line part, (D) part from the edge of the peripheral part to the ground contact part, (E) part of the valley part, and (F) outer surface part of the leg part and upper surface part of the bottom part Around the end of the valley line part which became a part was crystallized. The hollow container had a volume of 1.5 liters.

This hollow container was filled with 2.5 gas volume of carbonated water at 5 ° C. and capped, and then a hot water shower at 70 ° C. was applied for 30 minutes. afterwards,
After showering with water at 20 ° C. for 10 minutes and cooling, the total height of the bottle and the deformation rate of the body diameter were measured. As a result, the deformation rate of the total height of the hollow container was 2.0%, and the deformation rate of the body diameter was
1.0%. Next, when the 12 filled containers were dropped upright onto the concrete from a height of 1.0 m, there was no breakage in the bottom of all the containers.

Example 3 The same procedure as in Example 1 was carried out except that the surface temperature of the shield plate at the start of heating and crystallization was room temperature, cooling water was not supplied during heating and crystallization, and the shield plate was not cooled. . The surface temperature of the shielding plate at the end of this crystallization was a temperature below the glass transition point of the saturated polyester resin. The hollow container was filled with 2.5 gas volume of carbonated water at 5 ° C., capped, and then subjected to a hot water shower at 70 ° C. for 30 minutes. Then, it was showered with water at 20 ° C. for 10 minutes to cool, and the total height of the bottle and the deformation rate of the body diameter were measured. As a result, the deformation rate of the entire height of the hollow container was 2.0%, and the deformation rate of the body diameter was 1.0%. Next, when the 12 filled containers were dropped upright onto the concrete from a height of 1.0 m, there was no breakage in the bottom of all the containers.

Comparative Example 1 The same procedure as in Example 1 was carried out except that the bottom of the container was not crystallized. The hollow container had a volume of 1.5 liters. The hollow container was filled with 2.5 gas volume of carbonated water at 5 ° C., capped, and then subjected to a hot water shower at 70 ° C. for 30 minutes. afterwards,
It was cooled by showering with water at 20 ° C. for 10 minutes. The bottom of the container of the bottle was protruding, and there was no self-sustaining stability.

[0034]

As described above, according to the present invention, by using a shielding plate having a specific shape to crystallize a specific portion of the bottom of the container, the pressure resistance and heat resistance during heat sterilization of the contents are increased. A pressure- and heat-resistant self-supporting hollow container with improved impact resistance can be obtained.

[Brief description of drawings]

FIG. 1 is a front view of the device of the present invention.

FIG. 2 is an enlarged view of the main part (F part) of FIG.

FIG. 3 is a front view of the hollow container of the present invention.

FIG. 4 is a plan view of a shield plate 2A of the present invention.

FIG. 5 is a sectional view taken along the line A-A ′ of the shielding plate 2A of the present invention.

FIG. 6 is a bottom view of the hollow container of the present invention.

FIG. 7 is a plan view of a shield plate 2B of the present invention.

FIG. 8 is a B-B ′ sectional view of the shielding plate 2B of the present invention.

FIG. 9 is a bottom view and a side view of the hollow container of the present invention.

FIG. 10 is a bottom view showing each part of the bottom portion of the hollow container of the present invention.

FIG. 11 is a side view showing each part of the bottom of the hollow container of the present invention.

[Explanation of symbols]

1, 1A Biaxially stretched blow container 1B Hollow container 2, 2A, 2B Shielding plate 3 Heating device 4 Upper plate 5 Container supporting plate 6 Shielding plate supporting plate 7 Bottom plate 8 Cylinder for lifting and loading container 9 Strut 10 Pushing pressure cap inside container Plate / container support plate 11 Internal pressure load cap 12 Compressed air inlet tube 13 Packing 14 Temperature control medium tube 15 Piping 16 Opening 21 Mouth and neck 22A Support ring 22B Support ring lower 23 Shoulder 24 Body 25 Bottom 31A (A ) Bottom center part 31B (B) Bottom center part peripheral part 31C (C) Valley line part 31D (D) Leg part bottom center part peripheral part edge to ground contact part 31E (E) Valley line part Part that is sandwiched by the outer surface of the leg 31F (F) Outer surface of the leg and the upper surface of the bottom 31a Opening 31b that corresponds to the center of the bottom of the shielding plate 31b Peripheral area around the bottom center of the shading plate 31c Opening area corresponding to the valley line of the shielding board 31d Opening area from the edge of the peripheral area around the bottom center of the leg of the shielding plate to the grounding area Corresponding opening area 31e An opening corresponding to a part of a portion sandwiched between the valley line portion of the shield and the outer surface of the leg 31f An opening corresponding to a portion of the outer surface of the leg of the shield and the upper surface of the bottom 32 Leg Department

Claims (1)

[Claims] 1. A self-standing structure in which a plurality of legs are radially bulged around the mouth and neck, shoulders, torso, and center of the bottom, and valley lines are formed between these legs. In a biaxially stretched blow container made of a saturated polyester resin biaxially stretch blow molded having a bottom having a possible structure, between the container bottom and the heating device, the container bottom is fitted, and the following ( A shielding plate having an opening corresponding to at least one or more parts selected from (A) to (F) is installed, and the part selected from (A) to (F) at the bottom of the container is crystallized, and other than this 1. A method for producing a pressure- and heat-resistant self-supporting hollow container, characterized in that the bottom of the container is not crystallized. (A) Center part of bottom part (B) Peripheral part of center part of bottom part (C) Valley line part (D) Part from edge of said peripheral part to ground contact part (E) Valley part (F) Outside leg part Upper surface of the surface and bottom