JP2024023723A - Blow-molded container - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a blow-molded container with a metal mouthpiece, having a more preferable shape and a mouthpiece integrated with resin of a container body.

SOLUTION: In a blow-molded container, an inner diameter surface of an intermediate short cylindrical part between a tip side short cylindrical part having a threaded groove for connecting a valve or joint to be connected to the container in the inner diameter side and a flange at the opposite tip side is embedded in the resin of a container body, and the resin in which the inner peripheral surface of the intermediate short cylindrical part is embedded is screwed to the threaded groove to close a gap between the valve or joint to be connected to the container and a mouthpiece.

SELECTED DRAWING: Figure 6

COPYRIGHT: (C)2024,JPO&INPIT

Description

The present invention relates to a blow-molded container made of polyethylene naphthalate (PEN) resin or the like.

The main methods used to manufacture resin containers are direct blow molding, which uses high-density polyethylene (HDPE), and biaxial stretch blow molding, which uses preforms made of thermoplastic resins such as PET and PEN. (Patent Document 2).

Due to the characteristics of direct blow molding, there are variations in the sealing performance of the interface between the base and the resin when the base is integrally molded, and it is necessary to apply adhesive coating to the interface between the metal and the resin, which increases manufacturing man-hours and manufacturing costs.

In biaxial stretch blow molding, a cylindrical preform with a shorter axial length and a bottom than the desired container is formed by injection molding, the preform is heated in a blow molding machine, and then molded with gold. Air is blown into the softened preform in the mold to inflate it into the desired shape to form a container.

An example of a biaxial stretch blow molding machine is shown in Patent Document 3. The blow molding machine proposed in Patent Document 3 has a heating box having a plurality of infrared heaters arranged at intervals in the axial direction of the preform, facing the transport path of the preform, and The preform, which is intermittently conveyed above and stopped in front of the infrared heater of the heating box, is heated while rotating. In this case, a cooling air blowing means is provided that has a cooling air blowing nozzle that blows cooling air toward the preform from a cooling air blowing port at a position opposite to the stop position of the preform on the opposite side of the infrared heater across the preform. The cooling air blowing means has a blowing amount adjusting means for adjusting the blowing amount of cooling air from the cooling air blowing port, and the blowing position of the cooling air blowing port is made variable.

Resins used for containers manufactured with biaxial stretch blow molding machines include polyester resins, especially PET and PEN, which are thermoplastic polyester resins that have crystallinity but are slow to crystallize. It has the characteristic that it can be easily made into a container. Although PEN has superior heat resistance and chemical resistance compared to PET, it is more likely than PET to cause deviation in container thickness during stretch blow molding, making it impossible to increase the stretching ratio in the radial direction of the container.

Regarding the stretching ratio of PEN, the preform must be stretched at least 2 times or more in the longitudinal direction, and stretched 2.5 times or more in the transverse direction from the start to the completion of stretching in the longitudinal direction. is said to be preferable (Patent Document 4).

Biaxial stretch blow-molded containers with metal caps are shown in Patent Documents 1 and 5. In the example of Patent Document 1, the metal of the cap is made of aluminum, stainless steel, brass, etc., and adhesive resin is used to ensure interfacial adhesion between the cap and the thermoplastic resin. The gap between the valve and the cap is sealed with an O-ring.

By insert-molding a metal cap during injection molding of a preform, it is possible to provide a metal cap integrated with the molded container body. Patent Document 5 discloses a cap that has a female thread on the inner diameter surface on the tip side and a flange portion on the outer periphery opposite to the tip (container body side).

US Patent Application Publication No. 2014/0299610 Japanese Patent Application Publication No. 2017-20651 Japanese Patent Application Publication No. 11-188785 Unexamined Japanese Patent Publication No. 2019-1880 Japanese Patent Application Publication No. 2012-189106

An object of the present invention is to obtain a blow-molded container with a metal cap that has a more preferable shape and a cap that is integrated with the resin of the container body.

In this invention, the metal cap 10 is insert-molded during injection molding of the preform 2, thereby providing the metal cap 10 integrated into the molded container body. The cap 10 is provided with a thread 16 on the inner diameter of the tip side of the container, and has a short cylindrical portion 11 at the tip, a short cylindrical intermediate portion 13, and a thin flange 14 on the side opposite to the tip of the short cylindrical portion 13 on the outer periphery. The inner and outer peripheries of the intermediate short cylindrical portion 13 and the entire thin flange are embedded in the resin of the container body. It is preferable to provide a thick flange 12 between the short cylindrical end portion 11 and the short cylindrical intermediate portion 13 on the outer periphery.

The thin flange 14 embedded in the resin of the container body resists external force acting on the mouthpiece 10 in the axial direction of the container. By providing a plurality of notches or projections and depressions around the thin flange 14, it is possible to provide resistance to external force in the circumferential direction that acts on the base 10.

The thick-walled flange 12 is provided to withstand gas pressure blown into the preform and fix the preform in a fixed position within the mold when the preform is blow-molded. Further, the thick flange 12 can be used as a wrench when attaching a joint or a valve to the base 10 by forming the outer periphery of a regular even-numbered square such as a regular hexagon or a regular octagon.

The resin 17 covering the inner diameter surface of the intermediate short cylindrical portion 13 of the cap is used as a seal to close the gap between the cap 10 and a valve or joint connected to the cap 10, so that the contents of the container can be stored in the cap 10 made of metal. The structure shall be such that it does not come into contact with the

The blow-molded container of the present invention can be a biaxial stretch blow-molded container made of PEN resin in which the maximum circumference of the body 1t is 8 to 10 to 12 times the circumference of the mouth 1m. The biaxial stretch blow-molded container made of PEN resin of the present invention can be manufactured by heating and softening a preform 2 made of PEN resin obtained by injection molding.

The resin 17 covering the inner diameter surface of the intermediate short cylindrical portion 13 of the cap acts as a seal to close the gap between the valve or fitting connected to the cap 10 and the cap 10, and the resin 17 acts as a seal to close the gap between the valve or fitting and the cap 10. This prevents the contents from leaking out. Further, the structure can be such that the contents do not come into contact with the metal base 10, and it can be used as a container for chemicals that may corrode metal.

A cross-sectional side view of a preform used to form the container of Figure 2. A side view showing an example of the container of the present invention Front view of the cap of the container in Figure 2 Same side view Same rear view Cross-sectional side view of the cap embedded in the preform A plan view schematically showing a biaxial stretch blow molding machine Same side view A side view showing details of the heating device used for manufacturing the container of the present invention Graph showing the distribution of electric power supplied to each heater element of the heating device in FIG. 9

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 is a side view showing an example of a thin-walled container of the present invention, and FIG. 1 is a cross-sectional side view showing an example of a preform used for blow molding the container shown in FIG.

A biaxial stretch blow-molded container 1 of PEN shown in FIG. 2 includes a bowl-shaped or dish-shaped bottom portion 1b, a cylindrical body portion 1t, and a shoulder portion 1s, and a mouth portion 1m located at the center of the shoulder portion 1s. A metal base 10 is provided by insert molding.

The cap 10 has a shape as shown in FIGS. 3 to 6, for example, and includes a short cylindrical portion 11 at the tip, which is the open end of the container, a thick-walled flange 12 with an octagonal cross section, a short intermediate cylindrical portion 13, and a short cylindrical portion 13 at the innermost end of the container. The thin flange 14 is located at . A plurality of notches 15 are provided at equal intervals on the periphery of the thin flange 14. A thread 16 for screwing a joint or a valve is provided inside the short cylindrical portion 11 .

This cap 10 is attached to a mold when injection molding the preform 2, and is integrated with the resin injected into the mold. The outer periphery and thin flange 14 are embedded within the resin forming the container body. The relatively thick resin 17 that has flowed into the inner diameter side of the cap 10 is screwed into the thread 16 and comes into close contact with the cylindrical portion provided at the tip end of the threaded part of the joint or valve mounted on the cap 10, thereby causing the joint to become attached. It acts to prevent the contents of the container from leaking from the gap between the valve and the cap. If necessary, an O-ring or the like can be provided in this part to further improve the sealing performance.

The shape of the preform 2 for the desired container shape is such that the inner diameter r is about 1/8 to 1/10 of the diameter of the container body to be molded, and the axial length L is the axial length of the container to be molded. Appropriately, it is about 1/1.5 to 1/2. Further, the wall thickness of the body portion 2t of the preform 2 should be thicker than that of a typical conventional preform, since the stretching ratio in the radial direction is large.

7 and 8 are a schematic plan view and side view of the blow molding machine 20. FIG. In the illustrated blow molding machine 20, a preform mounting section A, a heating device B, a blow molding section C, and a molded product removal section D are arranged along a passage 22 of a moving table 21 that moves rightward in the figure. . The moving table 21 includes a holder 23 that grips the preform base 10 and rotates at a constant speed around a vertical axis (around an axis perpendicular to the plane of the paper in FIG. 7). The holder 23 includes a stretching rod 24 that is inserted into the inner diameter of the gripped preform to stretch the preform in the axial direction, and an air supply port (not shown) that blows pressurized air into the preform that is airtightly loaded into the holder 23. ) and are provided.

The heating device B has a tunnel-shaped peripheral wall with open sides of the mounting part A and the blow molding part C, and a heater 32 consisting of a plurality of heater elements h (h1 to h13) is arranged on one side wall 31 of the peripheral wall. A cooling air blowing slit 33 elongated in the axial direction of the preform is provided on the opposite side wall 34.

The power supply device 39 that supplies power to the heater elements h is provided with an adjustment device that individually adjusts the power supplied to each of the heater elements h1 to h13. On the side wall 34 provided with the slit 33, an upper shielding plate 35a and a lower shielding plate 35b, which set the positions of the upper end 33a and lower end 33b of the opening of the slit 33, are provided so as to be individually movable up and down and fixed at set positions. It is being An air chamber 36 is provided outside the slit 33, and air supplied from the blower 37 to the air chamber 36 via the flow rate adjustment valve 38 flows out from the slit 33.

FIG. 9 is a diagram showing details of the heating device B, particularly an example of the positional relationship between the loaded preform 2, the heater 32, and the slit 33. The heater 32 is composed of a plurality of infrared heaters h (h1 to h13), and each infrared heater h is provided so that its position can be finely adjusted in the direction toward and away from the preform 2 and in the axial direction of the preform.

Each infrared heater h is arranged at a constant distance from the surface of the preform 2 that it faces, but the infrared heaters facing the upper and lower ends, that is, the bottom and mouth of the preform, are heated by the respective infrared heaters. The diameter of the preform at the target part changes, and the thickness of the part to be heated also varies depending on the shape of the corresponding part of the container being molded, so the optimal position depending on the shape of the container is determined through experiments. In this embodiment, the infrared heaters h12, h13, and h1 at the upper and lower ends are arranged closer to the preform surface than the infrared heaters h2 to h11 at the body.

The heating temperature of the portion of the preform 2 facing each infrared heater h is adjusted by a power supply device 39. The electric power supplied to each infrared heater h will vary depending on the shape of the preform and the shape of the container to be molded, but the power supplied to each infrared heater h will vary depending on the shape of the preform and the shape of the container to be molded. The graph in FIG. 10 shows suitable electric power to be supplied to each infrared heater when molding is performed using a preform having a direction length of 300 mm and an inner diameter of 30 mm. The resin used in this case was PEN, and the container shape shown in FIG. 2 was that of a household propane cylinder used in Japan.

As shown in FIG. 10, the power supplied to the infrared heaters h2 to h11 that heat the body 2t of the preform is approximately equal, but the power is supplied to the infrared heaters h12 and h13 located at the upper and lower ends, especially the infrared heaters h12 and h13 located at the upper end. Reduce the amount of power used. This causes excessive heating of the area where the infrared heater is placed close to the preform surface, and this also causes the upper edge of the preform to be softened near its limit to obtain a large draw ratio. This prevents the stretching rod 24 from penetrating.

Note that if the heating temperature is too high overall, the molded container may be distorted, the container may burst during molding, or the drawing rod may penetrate. If the upper and lower heating temperatures are low, insufficient expansion or distortion of the container will occur. If the heating temperature is low overall, there will be insufficient expansion, if the heating temperature of the body is low, the container will burst during molding, and if the heating temperature of the upper and lower parts is high and the heating temperature of the body is low, the stretching rod will penetrate and the container will burst. or distortion may occur. Furthermore, if the heating temperature at the bottom is high, the drawing rod will penetrate, and if the heating temperature at the mouth or neck is low, there is a tendency for the container to burst during molding.

A slit 33 for blowing out cooling air is provided on the opposite side of the heater 32 with the preform in between, and serves to equalize the heating temperature of the preform. The width of the slit 33 is, for example, 5 mm for a preform with an inner diameter of 30 mm, and its upper end is set at a position corresponding to the upper end 2a of the body 2t of the preform, and its lower end 33b is set at an intermediate position of the neck 2s. .

As described above, the preform 2 provided with the base 10 is obtained by injection molding. The preform 2 is mounted on the holder 23 of the movable table 21 at the preform mounting portion A in an inverted state, that is, with the mouth facing down. The moving table 21 with the preform mounted thereon is moved to the heating device B and rotates the holder 23. At the same time, the infrared heater h and the blower 37 are operated, and the balance between the infrared rays irradiated from the infrared heater h and the cooling air flowing out from the slit 33 heats the preform 2 and softens the resin.

The preform 2 heated to a predetermined temperature is moved to the blow molding section C by the movement of the moving stage 21 and stopped, and after closing the mold 41, by supplying pressurized air into the preform, Molded into desired shape. During this molding, a stretching rod 24 is inserted into the preform 2 from the mouth 2m of the preform to stretch the preform 2 in the axial direction. It is also possible to provide a heater on this stretching rod and insert it into the preform to heat the preform 2 from the inside when the preform 2 is heated by the heating device.

When the blow molding process is completed, the mold 41 is opened, the stretching rod 24 is pulled out, the movable table 21 is moved to the molded product removal section D, and the molded thin-walled container is removed from the movable table 21. The moving table 21 returns to the preform mounting section A by moving along the passage 22 to the left in the figure or by moving along a circuit (not shown).

In the above example, the molding of a container with a cylindrical body was explained, but a container with a rounded square cylindrical body, a cone or a square pyramid with rounded corners, a container with an uneven body It is possible to produce containers of various shapes, such as, and with this invention, it is possible to produce containers with a thin wall whose maximum circumference is 8 times or more than the circumference of the mouth, which was previously impossible. It can be produced by axial stretch blow molding.

1 Biaxial stretch blow-molded container 2 Preform 2b Bottom of preform 2t Body of preform 2s Neck of preform 2m Mouth of preform 10 Mouthpiece 11 Short cylindrical end of mouthpiece 12 Thick-walled flange of mouthpiece 13 Thick-walled flange of mouthpiece Intermediate short cylindrical part 14 Thin flange of base 17 Resin

Claims (3)

The mouth part has a metal cap with a thread on the inner diameter side, and the cap has a short cylindrical part on the distal end side with the thread on the inner diameter side, an intermediate short cylindrical part, and the intermediate short cylindrical part. A blow-molded container comprising a thin-walled flange located on the side opposite to the tip, and wherein the intermediate short cylindrical portion and the thin-walled flange are embedded in the resin of the container body,
The inner diameter surface of the intermediate short cylindrical portion is embedded in the resin of the container body, and the embedded resin is screwed into the thread to close the gap between the valve or joint connected to the cap and the cap. A blow molded container. The blow-molded container according to claim 1, further comprising a thick flange located between the short cylindrical end portion and the short cylindrical intermediate portion, the thick flange having a circumferential shape of a regular even number square. The blow molded container according to claim 1 or 2, which is molded by a biaxial stretch blow molding method.

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