JP5730128B2 - Molding method for resin containers - Google Patents

Description

  The present invention relates to a resin container used for containing liquid contents and a molding method thereof.

  An infusion container such as an infusion bottle containing an infusion solution is widely used as an infusion solution containing a drug or the like for administration to a patient. As such an infusion container, a container having a flexible container body that contains the infusion solution and two mouths that are formed in the container body and face each other is known (for example, Patent Document 1 and Patent Document 2). These infusion containers are generally a method in which air is blown into a tube-shaped resin extruded from a molding machine by an inflation method so as to expand to a predetermined size, and this is taken up and tubularly biaxially stretched by injecting air. Molded.

Japanese Patent No. 4048337 JP-A-5-337163

  The above-described molding method is expensive because the production speed is slow. Furthermore, since it is difficult to control the thickness, there is a drawback that the quality is likely to vary. On the other hand, blow molding methods are widely used as molding methods for containers made of thermoplastic resins such as polyethylene and polypropylene, and containers for foods, beverages, medicines, and industrial products are manufactured by the molding method.

  When the blow molding method is adopted, the production speed is relatively fast and the production efficiency is good. Moreover, since thickness control is easier than when the above-described molding method is adopted, there is little variation in quality. However, as in Patent Document 1 and Patent Document 2, even if an attempt is made to mold a resin container having two mouth portions by the blow molding method, blow air will escape from one of the mouth portions. It cannot be molded. As a countermeasure, it may be possible to close one of the mouths with another plug member for each molding so as not to let out blow air. In this case, it is necessary to provide a plug member for each molding. Depending on the working state, there is a problem in that blow-out of air occurs, and in some cases, the mouth shape is deformed.

The present invention is the view of the prior art problems, production cost is suppressed, and an object thereof is to provide a molded how the resin container can be molded of resin kettle stable quality.

In order to achieve the above object, the following technical measures were taken.
That is, the method for molding a resin container according to the present invention includes a container body and first and second mouth portions that are formed on the container body and face each other, and the second mouth portion is the first mouth. A method for molding a resin container having an inner dimension smaller than a part, wherein a cylindrical preform body serving as the container body and a preform body formed on a blow molding die in which the shape of the resin container is molded The preform having the first and second mouth portions formed in the first and second mouth portions is loaded so that the second mouth portion is located on the distal end side of the stretch rod inserted into the preform, and the second mouth portion is loaded. The front end of the stretch rod having a tip dimension larger than the inner dimension of the mouth portion is brought into contact with the lower end portion of the inner surface of the preform body so as to close the second mouth portion, and the second mouth portion is Air seal from the inside, As ether, it lowers the stretch rod with blowing blow air, and is characterized in that the preform body biaxially stretched without leaking the blow air.

  In the method for molding a resin container according to the present invention, a preform is loaded into a blow mold in which the shape of the resin container is molded so that a small second opening is positioned on the distal end side of the stretch rod. The stretch rod is brought into contact with the lower end of the inner surface of the preform body, the second mouth is air-sealed from the inside, blow air is blown and the stretch rod is lowered so as to maintain this air-sealed state, The preform body is biaxially stretched without leaking blow air. That is, the molding method according to the present invention makes it possible to adopt a blow molding method, so that the production speed is fast and the production efficiency is good. Moreover, since thickness control is easy, quality variation can be reduced.

The front end abutting portion of the stretch rod that abuts the lower end portion of the inner surface of the preform main body is formed in a round shape with a convex cross section or a concave cross section, and the lower end portion of the inner surface of the preform main body is at the front end abutting portion. It is preferable that the cross section is formed into a concave shape or a convex shape with a convex cross section.
In this case, since the sealing performance between the tip contact portion of the stretch rod and the lower end portion of the inner surface of the preform body is enhanced, a reliable air seal state can be obtained. Thereby, production management becomes easy and the quality of the resin container can be further stabilized.

  The lower end portion of the inner surface of the preform main body with which the front end of the stretch rod abuts may have a tapered shape that decreases in cross section as it goes in the traveling direction of the stretch rod. Even in this case, since the sealing performance between the tip contact portion of the stretch rod and the lower end portion of the inner surface of the preform main body is enhanced, a reliable air seal state can be obtained. Thereby, production management becomes easy and the quality of the resin container can be further stabilized.

The stretch rod is formed in a columnar shape, and the first and second mouth portions of the preform are formed in a cylindrical shape, and the diameter of the stretch rod as the tip dimension is the inner dimension of the second mouth portion. It is preferable that it is 2 mm or more larger than the inner diameter.
In this case, since the deterioration of the sealing performance due to the misalignment between the axis of the stretch rod and the axis of the preform is suppressed, production management is facilitated, and the quality of the resin container can be further stabilized.

  As described above, according to the present invention, it is possible to adopt a blow molding method in which the preform body is biaxially stretched without leaking blow air, and the production speed is increased, so that the production cost can be suppressed. In addition, the thickness can be easily controlled, and variations in quality can be reduced, so that a resin container with stable quality can be obtained.

(A) is a schematic cross-sectional view of the molding machine for enforcing the molding method of the resin container concerning one embodiment of the present invention, and (b) is the schematic longitudinal cross-sectional view. It is sectional drawing of the preform used for the shaping | molding method of resin containers, and the figure of the stretch rod inserted in this. It is a figure which shows the state which is implementing the molding method of a resin container. It is a figure explaining the state which extending | stretching of the preform main body is advancing. (A) is a front view of the infusion bottle shape | molded with the shaping | molding method of resin containers, (b) is the side view.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic cross-sectional view and a schematic vertical cross-sectional view of a molding machine 1 for carrying out a method for molding a resin container according to an embodiment of the present invention, and FIG. 2 is used in the method for molding a resin container. It is sectional drawing of the preform 20, and the figure of the stretch rod 2 inserted in this. In the following description, the sides corresponding to the upper and lower sides in FIGS. A molding machine 1 shown in FIG. 1 has an apparatus configuration for carrying out a blow molding method, and is divided into two blow molding dies 3 and a stretch rod device 4 positioned above the blow molding dies 3. And a blow air device 11 for supplying blow air and a control unit 12 for controlling the stretch rod device 4 and the blow air device 11. Each die 3A of the blow molding die 3 has a shape of a finished infusion bottle (resin container), and a cavity in the shape of the infusion bottle is formed by closing the die. Yes. Each die 3A of the blow molding die 3 is formed with two upper and lower mouth portions 6 and 7 facing the main body molding portion 5.

  The main body molding portion 5 is composed of a horizontally long portion 8 and an elliptical portion 9 so as to form a horizontally long and vertically extending cylindrical cavity. The stretch rod device 4 includes a columnar stretch rod 2, a blow nozzle 10 that supports the stretch rod 2 so that it can be driven up and down, and a drive unit 13 that drives the stretch rod 2 up and down. The stretch rod device 4 is fixed by a fixing member (not shown) so that the axis of the stretch rod 2 coincides with the axis of the cavity of the blow molding die 3. The stretch rod 2 that is controlled and driven in the vertical direction protrudes downward from the blow nozzle 10 by a predetermined amount at a predetermined speed and enters the cavity of the blow mold 3.

  A preform 20 shown in FIG. 2 is made of polypropylene (PP), and has a cylindrical preform body 23 extending in the vertical direction, and a cylindrical first mouth portion 21 formed above the preform body 23. And a cylindrical second mouth portion 22 formed on the lower side of the preform main body 23. This preform 20 is formed in advance by an injection molding machine or the like (not shown). The preform body 23 has an inner diameter (inner dimension) n1 of 17.0 mm, a thickness center diameter n2 of 19.4 mm, and a wall thickness t1 of 3.5 mm at the center. The first mouth portion 21 has the same inner diameter as the preform body 23, and the first mouth portion 21 includes an upper collar portion 24 positioned at the upper end of the preform 20, and the upper collar portion 24. A middle collar portion 25 is formed on the lower side with a predetermined interval.

  The inner diameter (inner dimension) n3 of the second mouth portion 22 is 7.4 mm, and the second mouth portion 22 is formed so as to be reduced in diameter from the preform body 23. Accordingly, the second mouth portion 22 has a smaller inner diameter n3 than the first mouth portion 21. The second mouth portion 22 is formed with a lower collar portion 26 positioned at the lower end of the preform 20 and a thin film portion 27 that closes the second mouth portion 22. The length h1 of the second mouth portion 22 is 10.0 mm, and the thickness t2 of the thin film portion 27 is 0.5 mm. The length h2 from the lower surface of the middle collar part 25 to the upper surface of the lower collar part 26 is 64.1 mm. The stretch rod 2 inserted into the preform 20 has the same diameter over its entire length, and its diameter n4 is 15.0 mm. As a result, with the stretch rod 2 inserted into the preform 20, there is sufficient space between the stretch rod 2, the first mouth portion 21 and the preform body 23 to allow sufficient blow air to pass. It is done.

  Since the diameter (tip dimension) n4 of the stretch rod 2 is 15.0 mm as described above, it is 2 mm or more larger than the inner diameter n3 of the second mouth portion 22. As a result, the stretch rod 2 is driven downward (lowered), and when the tip 2 </ b> A comes into contact with the inner surface lower end portion 23 a of the preform main body 23, the second mouth portion 22 is blocked by the stretch rod 2. . Here, the inner surface lower end portion 23a of the preform main body 23 does not necessarily indicate only the region of the preform main body 23 but also includes a portion entering the region of the second mouth portion 22. Therefore, the case where the stretch rod 2 abuts includes a case where the stretch rod 2 abuts on a portion including the region of the second mouth portion 22.

  When the second mouth 22 is closed by the stretch rod 2, the second mouth 22 is air-sealed from the inside. As shown in the enlarged view of FIG. 2, the tip contact portion 2a of the stretch rod 2 that contacts the inner surface lower end portion 23a of the preform body 23 is formed in a rounded cross-sectional shape, and this tip contact portion The lower end portion 23a of the inner surface of the preform body 23 with which 2a abuts is formed in a rounded shape with a concave cross section along the tip abutting portion 2a. Accordingly, when the distal end contact portion 2a of the stretch rod 2 contacts the inner surface lower end portion 23a of the preform body 23, the convex cross-section of the cross-section and the concave cross-section of the cross-section are combined, and the second mouth 22 is reliably sealed from the inside. Is done. The second mouth portion 22 is closed by the thin film portion 27, but the thin film portion 27 has only the above-described thickness that can be damaged by the blow air pressure or the contact with the stretch rod 2.

  Contrary to the above-described shape, the front end contact portion 2a of the stretch rod 2 and the inner surface lower end portion 23a of the preform body 23 are formed in a round shape with a concave cross section. The lower end portion of the inner surface of the main body 23 may be formed in a round shape having a convex cross section along the tip contact portion. Also in this case, when the tip contact portion of the stretch rod 2 contacts the lower end portion of the inner surface of the preform main body 23, the rounded cross section and the round cross section are combined, and the second mouth 22 is formed from the inside. Air seal is ensured.

  Further, the lower end portion of the inner surface of the preform main body 23 with which the front end 2A of the stretch rod 2 abuts may have a taper shape in which the cross section becomes smaller as it goes downward (in the traveling direction of the stretch rod 2). More specifically, there is a lower end portion of the inner surface that has a tapered shape that decreases in diameter as it goes downward. In this case, as the stretch rod 2 is pressed against the lower end portion of the inner surface of the preform main body 23, the sealing performance increases, and the second mouth portion 22 is reliably air-sealed from the inside.

  The shaping | molding method for shape | molding an infusion bottle using the above-mentioned shaping | molding machine 1 is demonstrated. FIG. 3 is a diagram illustrating a state in which the resin container molding method is being performed, and FIG. 4 is a diagram illustrating a state in which the preform 20 is being stretched. First, as shown in FIG. 3, the preform 20 is loaded into the blow mold 3 so that the second mouth 22 is positioned on the distal end side of the stretch rod 2 inserted into the preform 20. At that time, the middle flange portion 25 of the first mouth portion 21 of the preform 20 is hooked on the upper side of the mouth portion 6 on the upper side of each mold 3A, and is formed by the axis of the preform 20 and each die 3A. Fix so that the axis of the cavity matches.

  The stretch rod 2 is driven to enter the inside of the preform 20. The stretch rod 2 is lowered until its tip 2A comes into contact with the inner surface lower end portion 23a of the preform body 23. And it seals from the inside so that the 2nd opening 22 may be obstruct | occluded. Subsequently, the blow air 50 is blown and the stretch rod 2 is further driven downward, and the preform body 23 is biaxially stretched by longitudinal stretching with the stretch rod 2 and lateral stretching with the blow air 50.

  At that time, the control unit 12 controls the drive unit 13 and the blow air device 11 of the stretch rod device 4 so that the air sealing state of the second mouth 22 can be maintained by these operations. In order to maintain the air-sealed state, the control unit 12 drives the stretch rod 2 downward and blows air 50 so that the longitudinal stretching by the stretch rod 2 precedes the transverse stretching by the blow air 50 more than usual. To control the blowing pressure. Since the longitudinal stretching by the stretch rod 2 precedes the lateral stretching by the blow air 50, the tip 2A of the stretch rod 2 is always in contact with the inner surface lower end portion 23a of the preform body 23 so that the air seal state can be maintained. Become.

  In the present embodiment, the preform temperature is set to 123 ° C. by heating the blow molding die 3, and the stretch speed of the stretch rod 2 is set to 1 m / s. The blowing pressure by the blow air device 11 was sequentially controlled by the control unit 12 so as to maintain the air seal state at this stretch speed. As shown in FIG. 4, while the longitudinal stretching by the stretch rod 2 precedes the lateral stretching by the blow air 50, the biaxial stretching by these is performed by the second mouth portion 22 to the mouth portion 7 below the blow molding die 3. Proceed until fit.

  The shapes of the first mouth portion 21 and the second mouth portion 22 of the preform 20 are substantially unchanged, and only the preform main body 23 is biaxially stretched and gradually becomes thinner. The preform body 23 is stretched to the shape of the cavity, and becomes the shape of the container body 31 of the infusion bottle 30 shown in FIG. FIG. 5 is a front view and a side view of the infusion bottle 30 formed by the resin container forming method. The infusion bottle 30 includes a container body 31 in which the preform body 23 is biaxially stretched, and first and second mouth portions 21 and 22 that are formed in the container body 31 and face each other. The dimensions of each part of the infusion bottle 30 are as follows. The inner diameters of the first and second mouth portions 21 and 22 are the same as those of the preform 20, the trunk outer diameter (long side) d1 is 68.5 mm, and the trunk outer diameter (short side) d2 is 41.5 mm. The length h3 from the lower surface of the middle collar portion 25 to the upper surface of the lower collar portion 26 is 96.0 mm, and the central thickness of the container body 31 is 58.7 mm (in terms of yen). Therefore, the longitudinal draw ratio: 96.0 / 64.1 = 1.498, the transverse draw ratio: 58.7 / 19.4 = 3.025, and the ratio between the longitudinal draw ratio and the transverse draw ratio is about 1: 2.

  In the method for molding a resin container according to the present embodiment, the small second opening 22 is positioned on the distal end side of the stretch rod 2 in the blow molding die 3 in which the shape of the infusion bottle 30 is molded. The reformer 20 is loaded, and the tip 2A of the stretch rod 2 is brought into contact with the lower end portion 23a of the inner surface of the preform body 23 so that the second mouth portion 22 is air-sealed from the inside, and blow air is maintained so as to maintain this air-sealed state. 50 is blown and the stretch rod 2 is lowered, and the preform body 23 is biaxially stretched without leaking the blow air 50. In this way, since the blow molding method can be adopted, the production speed is high. Thereby, production cost can be suppressed. In addition, since the thickness can be easily controlled and the variation in quality can be reduced, the infusion bottle 30 having a stable quality can be obtained.

  The front end abutting portion 2a of the stretch rod 2 that abuts on the inner surface lower end portion 23a of the preform main body 23 is formed in a rounded cross-section, and the preform main body 23 that abuts the front end abutting portion 2a. Since the inner surface lower end portion 23a is formed in a rounded cross-sectional shape along the tip contact portion 2a, the sealing property between the tip contact portion 2a of the stretch rod 2 and the inner surface lower end portion 23a of the preform body 23 Will increase. Therefore, a reliable air seal state can be obtained, production management becomes easy, and the quality of the infusion bottle 30 can be further stabilized. The front end abutting portion 2a of the stretch rod 2 is formed in a round shape having a concave cross section, and the inner surface lower end portion 23a of the preform main body 23 that abuts the front end abutting portion 2a is along the front end abutting portion 2a. The same effect can be obtained even when formed in a round shape with a convex cross section, or when the inner surface lower end portion 23a of the preform main body 23 is tapered so that the cross section becomes smaller toward the traveling direction of the stretch rod 2. Can be obtained.

  Since the diameter n4 as the tip dimension of the stretch rod 2 is 2 mm or more larger than the inner diameter n3 as the inner dimension of the second mouth portion 22, there is a difference between the axis of the stretch rod 2 and the axis of the preform 20. The deterioration of the sealing performance based on the above is suppressed, the production management becomes easy, and the quality of the infusion bottle 30 can be further stabilized.

  The infusion bottle 30 of the present embodiment has a container body 31 in a biaxially stretched state, which is formed by causing the longitudinal stretching by the stretch rod 2 to precede the transverse stretching by the blow air 50 than usual. Since the said container main body 31 shape | molded in the state which stabilized the ratio of lateral stretch was obtained, the required characteristic as the infusion bottle 30 is satisfy | filled reliably, and high quality can be maintained.

Molding how the resin vessel of the above embodiment is an illustration of a molding how the resin vessel according to the present invention. The molding method of the resin container of the present invention may include other steps as necessary. In order to seal the second mouth portion with the stretch rod, the shape of the tip of the stretch rod or the preform You may change the shape of the inner surface lower end part of a main body. You may change shapes, such as a resin container to shape and a stretch rod. The resin container formed by the method for forming a resin container of the present invention is not limited to an infusion bottle, and may be a container used for other uses such as beverages, chemicals, and industrial use. The resin used for molding is appropriately changed, and in addition to polypropylene, known flexible ones such as polyethylene, polyester, nylon, vinyl chloride, chlorinated polyethylene, and ethylene-vinyl acetate copolymer are used. Can be adopted.

DESCRIPTION OF SYMBOLS 1 Molding machine 2 Stretch rod 2A Tip 2a Tip contact part 3 Blow molding die 4 Stretch rod device 12 Control part 20 Preform 21 First mouth part 22 Second mouth part 23 Preform main body 23a Inner surface lower end part 30 Infusion solution Bottle 31 Container body

Claims (4)

A method for forming a resin container comprising a container main body and first and second mouth portions formed in the container body and facing each other, wherein the second mouth portion has an inner dimension smaller than that of the first mouth portion. Because
In the blow molding die in which the shape of the resin container is molded,
A preform having a cylindrical preform body serving as the container body and the first and second openings formed in the preform body is placed on the distal end side of the stretch rod inserted into the preform. Load so that the second mouth is located,
The second end of the stretch rod having a tip dimension larger than the inner dimension of the second mouth portion is brought into contact with the lower end portion of the inner surface of the preform body so as to close the second mouth portion. Air seal the mouth from the inside,
A method for molding a resin container, comprising blowing blow air and lowering the stretch rod so as to maintain an air-sealed state, and biaxially stretching the preform body without leaking the blow air.   The front end abutting portion of the stretch rod that abuts the lower end portion of the inner surface of the preform main body is formed in a round shape with a convex cross section or a concave cross section, and the lower end portion of the inner surface of the preform main body is at the front end abutting portion. The method for forming a resin container according to claim 1, wherein the resin container is formed in a round shape having a concave cross section or a convex cross section.   2. The resin according to claim 1, wherein the lower end portion of the inner surface of the preform body with which the tip of the stretch rod abuts has a tapered shape that decreases in cross section as it goes in the traveling direction of the stretch rod. A method for forming a container.   The stretch rod is formed in a columnar shape, and the first and second mouth portions of the preform are formed in a cylindrical shape, and the diameter of the stretch rod as the tip dimension is the inner dimension of the second mouth portion. The method for molding a resin container according to any one of claims 1 to 3, wherein the inner diameter is 2 mm or more larger than the inner diameter.

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