JP2006264042A - Mold for manufacturing bottle container by biaxial stretch blow molding method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mold for manufacturing a bottle container suitable for the delivery of a heated beverage. <P>SOLUTION: The mold for manufacturing the plastic bottle container by a biaxial stretch blow molding method is composed of at least two body molds for forming the body part of the bottle container and one bottom mold for forming the bottom part of the bottle container and the mold splitting position of the body molds and the bottom mold is set to the position corresponding to the rib provided to the lower part of the body of the bottle container. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a mold for manufacturing a bottle container by a biaxial stretch blow molding method, and more particularly to a mold for manufacturing a plastic bottle container such as a PET bottle container used for filling and heating a beverage. .

  The production of bottle containers by the biaxial stretch blow molding method is a common production method in the production of PET (polyethylene terephthalate) bottle containers and the like that are currently widely used. The mold used for this biaxial stretch blow molding method generally comprises at least two body molds that form the body of the bottle container and one bottom mold that forms the bottom of the bottle container. The parting position is normally provided at the ground contact portion when the bottle container is erected (Japanese Patent Laid-Open No. 2-74319 (Patent Document 1), FIG. 3 and Japanese Patent Laid-Open No. 2004-42275 (Patent). Reference 2) See FIG. This is because by providing the mold splitting position at this position, an exhaust path for the air in the mold at the time of molding can be secured. In a bottle container molded with a mold having such a mold structure, a circumferential protrusion is often generated at the ground contact portion corresponding to the mold splitting position.

In the past, PET bottle containers have been used only for the distribution of cold beverages, but recently it has become common to sell PET bottle containers filled with beverages and heated. In such warming sales, beverages in bottled containers are often sold by heating on a hot plate (generally referred to as a hot warmer) at a store. In this warming sales, if there is a circumferential protrusion on the ground contact portion of the bottle container, the heat conduction is hindered by the protrusion, and the liquid temperature rise varies during hot warmer heating.
Japanese Patent Laid-Open No. 2-74319 JP 2004-42275 A

  An object of the present invention is to provide a mold for producing a bottle container suitable for the circulation of a warmed beverage by a biaxial stretch blow molding method, and in particular, there is a circumferential protrusion on the ground contact portion of the bottle container. The object is to provide a mold that does not occur.

  The inventors of the present invention have examined the cause of the occurrence of a circumferential protrusion at the ground contact portion of the bottle container, and have found the following two causes. First, when the body mold and the bottom mold are combined at the time of molding, a difference in height occurs, and a step occurs in the ground contact portion of the bottle container, which is the part of the mold. Secondly, when the body mold and the bottom mold are combined at the time of molding, it is necessary to secure an interval of about 0.5 to 1.0 mm so that the body mold and the bottom mold do not interfere with each other. The resin flows in and a circumferential protrusion is generated at the ground contact portion of the bottle container.

  The present inventors have determined that ribs and bottom molds should be separated from the bottom part of the bottle container, particularly considering other restrictions, and ribs provided with the bottom mold and bottom molds at the bottom of the cylinder. The present invention has been completed by finding that the above-mentioned problem can be solved by setting the position corresponding to the above.

  Accordingly, the biaxial stretch blow molding mold of the present invention is a mold for manufacturing a plastic bottle container by a biaxial stretch blow molding method, and the mold forms the body of the bottle container. It consists of at least two barrel molds and one bottom mold that forms the bottom of the bottle container, and the dividing positions of the trunk mold and the bottom mold are at positions corresponding to ribs provided at the lower portion of the bottle container. It is characterized by being.

Biaxial Stretch Blow Molding Method The mold of the present invention is for producing a bottle container by a biaxial stretch blow molding method. In this biaxial stretch blow molding method, a test tube preform is placed in a mold, and a gas is blown into the preform while blow-molding the preform with a rod, and the mold is blow molded. A bottle container having a shape inside a mold is manufactured.

Mold Structure The structure of the mold of the present invention will be described with reference to FIG. A mold for producing a bottle container by the biaxial stretch blow molding method of the present invention includes two body molds 1 that form a body part of the bottle container and one bottom mold 2 that forms the bottom part of the bottle container. At least, the parting position 3 between the body mold 1 and the bottom mold 2 is at a position corresponding to a rib provided at the bottom of the body of the bottle container. The “rib” referred to here is a ring-shaped portion that is usually provided at the lower part of the barrel of the bottle container in order to ensure the strength against pressure from the lateral direction of the bottle container. If the parting position is above the rib, the bottom mold cannot be removed after the bottle container is formed. By setting the dividing positions of the body mold and the bottom mold to such positions, there is no protrusion on the ground contact portion of the bottle container, and the temperature of the contents can be stably raised during heating by the hot warmer.

  Next, the structure of a conventional mold will be described with reference to FIG. The conventional mold includes at least two body molds 1 that form the body of the bottle container and one bottom mold 2 that forms the bottom of the bottle container. Is provided at a position corresponding to the ground contact portion when the bottle container is erected.

Separation of bottom mold In the present invention, the bottom mold is preferably separated into a heel portion and a bottom mountain portion. Here, the “heel portion” refers to the portion from the ground contact portion at the bottom of the bottle container to the place where the wall surface of the bottle container is vertical and its peripheral portion.

  The structure of the mold of the present invention in which the bottom mold is separated into a heel portion and a bottom mountain portion will be described with reference to FIG. The mold according to a preferred embodiment of the present invention comprises at least two body molds 1 that form the body of the bottle container and one bottom mold 2 that forms the bottom of the bottle container. In addition to the fact that the parting position 3 is at a position corresponding to the rib provided at the lower part of the body of the bottle container, the bottom mold 2 is divided into a heel part 4 and a bottom mountain part 5. The heel portion 4 and the bottom mountain portion 5 are fixed in advance, and function as an integral bottom mold 2 at the time of molding. A gap 6 is provided between the heel portion 4 and the bottom mountain portion 5.

  This gap can be exhausted from the air inside the mold, but is kept at such an interval as to prevent the plastic from protruding. This interval is preferably 0.3 to 0.7 mm, and more preferably about 0.5 mm. And it is preferable that this clearance gap 6, ie, the classification | category position of a bottom type | mold, exists in the position corresponding to the earthing | grounding part at the time of standing a bottle container upright. Furthermore, it is preferable from the viewpoint of moldability and heat resistance that the separation position is at a position of 50 to 75% of the body diameter from the center of the bottom mold.

Mold Dimensions The dimensions inside the mold of the present invention correspond to the dimensions of the bottle container, but are not particularly limited. For example, the trunk diameter is 55 to 70 mm (preferably 60 to 70 mm), the total height is 130 to 170 mm, and the inner diameter of the ground contact portion is 50 to 75% (preferably 55 to 70%) with respect to the trunk diameter.
Can be.

  However, in consideration of sales with vending machines, the size of the bottle container (total height of the bottle container) that can be used is about 130 to 138 mm due to restrictions imposed by the dimensions of the column for the bottle container of the vending machine that is normally used. Limited. Therefore, in consideration of the variation error at the time of forming the bottle container, it is preferable that the mold has a center height of 132 to 136 mm ± 2 mm. In addition, the outer diameter of the body is preferably 66.0 mm ± 0.5 mm in consideration of variation errors during molding of the container. If the outer diameter of the barrel is 67 mm or more, there will be a problem of clogging in the column of the vending machine or near the discharge port. If it is 65 mm or less, two or three bottle containers will be discharged from the discharge port. Can cause problems. From such a viewpoint, the dimensions of the mold of the present invention are preferably such that the total height of the container is 132 to 136 mm ± 2 mm, and the outer diameter of the container body is 66.0 mm ± 0.5 mm.

In mold Sokoyama present invention, preferably those having a bottom mountain that is convex toward the central portion of the bottom mold. By doing in this way, the grounding part of a bottle container will be fully extended | stretched at the time of shaping | molding, intensity | strength and heat resistance will improve, and also the upright stability of a bottle container will increase.

  In the mold of the present invention, the height of the bottom mountain from the ground contact portion is preferably 25 to 40% (preferably 25 to 35%) of the trunk diameter. It is preferable that the top of the bottom mountain is at a position higher than the mold splitting position. The bottom mold of such an aspect has a top of the bottom mountain protruding from the side.

Measurement of variation in liquid temperature rise A preform was produced under the following conditions.
PET resin: Far East Bob CB651G
Molding machine: FE160 (Nissei Plastic Industry): Resin temperature setting at molding 285 ° C

The obtained preform was as follows.
Total length 85mm, mouth inner diameter 21.7mm, trunk diameter 22mm, bottom thickness 3mm, weight 23g, mouth crystallization treatment completed.

The obtained preform was blow molded under the following conditions to obtain a bottle container.
Blow molding machine: LB-01 manufactured by KRUPP CORPLAST
Mold temperature: trunk 60 ° C, bottom 10 ° C
Air pressure: 30 kg / cm ²

  For a mold having a total height of 136 mm, a trunk diameter of 66.0 mm, a ground contact diameter of 45 mm, and a bottom mountain height of 16.5 mm, a conventional mold divided by the ground contact portion (comparative example), and a heel portion divided by a body side rib The molds (Examples) of the present invention in which the bottom mountain portions were separated (interval of 0.5 mm) were produced, and using these molds, a PET bottle container having a total height of 136 mm, a trunk diameter of 66 mm, and a full injection of 300 ml was formed.

Each of the 32 bottle containers was filled with 280 ml of water, a K thermocouple was attached to the cap, and the rise in the liquid temperature at the center of the bottle container was measured. The plate temperature was set to 100 ° C., and the time until the liquid temperature reached 23 ° C. to 55 ° C. was measured. In the case of using a bottle container manufactured by using the body part split mold of the present invention example, the heating time is generally shorter than that of the bottle container manufactured using the bottom part split mold of the comparative example. In addition, the width of the longest time and the shortest time was 27 minutes, which was about 1/2 that of the comparative example.

Checking moldability For a mold with an overall height of 136 mm and a barrel diameter of 66.0 mm, the bottom mountain height is varied in the range of 12 to 28 mm, and the grounding diameter (the diameter inside the grounding part of the bottle container) is in the range of 35 to 53 mm. The PET bottle container was molded and the moldability was confirmed. The molds used were those in which the parting position was at the rib part, and those without a heel part (bottom mold integrated) and those with a heel part were confirmed. The results are shown in the following table. The symbols in the table have the following meanings.
○: The shape of the bottle container can be molded as the mold.
Δ: The heel portion (grounding portion) is wavy.
X: The heel portion is not molded as in the mold (insufficient dimension of 1 mm or more) or cannot be molded.

By separating the heel part of the mold, it was possible to mold well even if the bottom mountain was high.

A mold having a total height of 136 mm and a body diameter of 66 mm (for 280 ml bottle container) was prepared. The bottom mountain height was changed in the range of 12 to 28 mm, and the ground contact diameter was changed in the range of 30 to 53 mm.

About the PET bottle container shape | molded using these metal mold | dies, it put into the thermostat (each temperature 75, 78, 80 degreeC) for 10 hours, and confirmed whether the bottom did not buckle. This buckling means that the bottom protrudes below the grounded portion of the bottle container. The symbols in the table have the following meanings. The results are shown in the following table. The symbols in the table have the following meanings.
Temperature in table: No problem occurred up to that temperature.
Formability molding ○: The shape of the bottle container can be molded according to the mold.
Molding Δ: The heel portion (grounding portion) is wavy.
Molding x: The heel part is not molded according to the mold (dimensions of 1 mm or more are insufficient) or cannot be molded.
Heat resistance (evaluated with 5 samples)
Heat resistance ○: Not protruding from the ground. (No buckling)
Heat resistance x: protrudes from the ground. (With buckling)
Overturning Check if the bottle falls over when it is shaken slightly by placing a bottle container containing 280 ml of water on a 10 degree inclined stainless steel plate. In case of a fall, “fall” is described.

A PET bottle container was formed using a mold having a total side wall strength of 136 mm and a barrel diameter of 66.0 mm.

  In the case with the horizontal rib, a circular rib having a width of 5 mm and a depth of 1 mm on one side was provided at a position where the lower side of the rib was 10 mm in height from the ground contact portion.

  An empty bottle container (without cap) is turned sideways, a panel is faced up, a stainless steel rod of 10 mm square and length 20 mm is placed on it, and 6 kgf from the top of the bottle container by the top load tester manufactured by Agr-TopWave. A load was applied and the displacement (mm) was measured.

It was confirmed that the bottle container with the lateral rib has a smaller displacement and higher strength than the bottle container without the lateral rib.

It is sectional drawing of an example of the metal mold | die of this invention. It is sectional drawing of an example of the conventional metal mold | die. It is sectional drawing of an example of the metal mold | die of the suitable aspect of this invention.

Explanation of symbols

1. 1. Body type Bottom mold3. 3. Splitting position of body mold and bottom mold 4. Bottom heel part Bottom type bottom mountain part 6. The gap between the bottom heel and bottom mountain

Claims (8)

A mold for producing a plastic bottle container by a biaxial stretch blow molding method,
The mold comprises at least two body molds forming the body of the bottle container and one bottom mold forming the bottom of the bottle container;
2. A biaxial stretch blow molding mold characterized in that a parting position between the body mold and the bottom mold is at a position corresponding to a rib provided at a lower part of the body of the bottle container.   The metal mold | die of Claim 1 which has a convex-shaped bottom mountain in the center part of the said bottom mold.   The mold according to claim 2, wherein the bottom mold is divided into a heel portion and the bottom mountain portion.   The metal mold | die of Claim 3 which exists in the position corresponding to the earthing | grounding part at the time of the bottle container standing upright, when the separation position of the said heel part of the said bottom mold | type and the said bottom peak part is upright.   The metal mold | die of any one of Claims 2-4 in which the vertex of the bottom mountain of the said bottom mold exists in the position higher than the parting position of the said trunk | drum and the said bottom mold.   The metal mold | die of Claim 3 or 4 in which the classification position of the said heel part and the said bottom mountain in the said bottom mold exists in the position of 50 to 75% of a trunk diameter from the center of the said bottom mold.   The metal mold | die of any one of Claims 2-6 whose height of the said bottom mountain from the said grounding part is 25 to 40% of the said trunk | drum diameter.   The metal mold | die of any one of Claims 1-7 whose internal diameter of the said trunk | drum is 55-70 mm.

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