JPS61134224A - Manufacturing method for thin-walled hollow containers - Google Patents

Abstract

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

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method for manufacturing a thin-walled hollow container that integrally has a thin-walled body portion and a tubular portion at one end of the thin-walled hollow container. The present invention relates to a manufacturing method for blow molding a thin-walled hollow container in which the tubular portion connected to the container is thick and the body of the container is thin.

[Conventional technology]

Medical containers such as infusion bags or blood bags are generally flat and collapsible containers, but these containers are held on support rods in hospital rooms, etc., and the contents are stored when administering medicine to a patient. Infusion fluid and blood gradually pour out,
It is also necessary that no residue remains in the container. Therefore, it is desirable for this type of container to have an extremely thin wall so that its shape can be easily deformed even when the contents naturally drip, and there is no dead space where the contents remain inside the container. . In other words, without introducing air into the container from outside the container,
A closed system in which the container itself is deformed by the weight of the contents and the contents naturally drip due to the deformation is desirable, and an extremely thin wall thickness is desired in terms of shape.

Furthermore, this type of container has tubular parts such as an inlet for filling the contents, an outlet for discharging the contents, and a connection port for connecting with other containers at the upper or lower end of the container. It is set in.

This tubular part is connected to a flexible pipe to pour out and inject the contents, but the connection of this flexible pipe requires that the contents do not leak and that there is no infiltration of germs from the outside. It is desired that this tubular portion be formed with a thick wall.

By the way, as a method of manufacturing this type of container, there is a method of welding and molding two synthetic resin sheets.

In other words, the desired container can be obtained by placing a thick-walled pipe that will become the tubular part of the container between two thin-walled sheets and welding the two sheets together. However, this sheet welding method tends to enclose foreign substances such as dust, dirt, and bacteria between the sheets, and special attention must be paid to conditions such as sheet storage and manufacturing environment. This kind of medical container must be avoided, especially since the inside of the container is required to be clean.

Therefore, it is being considered to form thin-walled hollow containers using a blow molding method that does not enclose foreign substances such as dust, dirt, bacteria, etc. However, in blow molding, pressure fluid is blown into the parison to inflate it. Moreover, the wall thickness of each part is regulated by the blow ratio, and the wall thickness of the tubular part and the body part are relatively similar. For this reason, it is impossible to integrally mold the thick tubular portion required for the container and the container body so thin that its shape can be easily deformed by natural dripping of the contents.

Therefore, a method has been proposed in which a thick-walled pipe is inserted when forming a thin-walled hollow container by blow molding to form a container having a thick-walled tubular portion and a thin-walled container body (for example, (Sho 57-142850). However, with this method, the apparatus itself becomes complicated, and furthermore, the welding between the inserted pipe and the parison is incomplete and unsatisfactory.

[Means to solve the problem]

Therefore, the present invention is designed between two split molds facing each other, which are composed of a main mold having the external shape of a thin-walled body portion on the inner surface of the mold, and a sliding mold having the external shape of the tubular portion on the inside surface of the mold. A cylindrical parison made of molten synthetic resin is placed in the cylindrical parison, and the sliding mold is first tightened to form a thick tubular part at one or both ends of the cylindrical parison. A method for manufacturing a thin-walled hollow container, in which the rod is expanded in a direction perpendicular to the mold clamping direction to thin the cylindrical parison other than the tubular part gripped by a sliding mold, and then the main mold is tightened and blow-molded.

This is an attempt to solve the above-mentioned conventional problems.

[Effect]

In other words, in the present invention, since the sliding mold is first tightened to form the tubular portion at one end or both ends of the cylindrical parison, the tubular portion can be formed under pressure while maintaining the approximate wall thickness of the cylindrical parison.
Next, with the tubular part pressed and gripped by a sliding mold, the cylindrical parison other than the tubular part is expanded using a rod inserted into the cylindrical body in advance to increase the wall thickness of the cylindrical parison. Since a thin wall can be formed, by tightening the main mold and performing blow molding, a thin hollow container having a thin body and a thick tubular part integrally can be obtained.

In particular, the present invention allows the thickness of the cylindrical parison for forming the body to be controlled to a desired thickness by adjusting the degree of expansion of its rods.

The material constituting the thin-walled hollow container according to the present invention is ethylene-vinyl acetate copolymer (vinyl acetate content IQw
t% or more), soft polyvinyl chloride.

Low density polyethylene, medium density polyethylene, ionomer, ethylene-propylene elastomer.

These are styrene-butadiene elastomers, polyester elastomers, and blends thereof. In addition, in a thin-walled hollow container, the average wall thickness of the body part is Q, 7 mm or less, preferably 0.5 mm or less, while the average wall thickness of the tubular part is 1
, 3 mm or more, preferably 1.2 mm or more, and according to the present invention, the average wall thickness of the body part can be freely controlled to 1/2 or less of the average wall thickness of the tubular part. This can be achieved by forming a thick tubular part as described above, and then arbitrarily setting the degree of expansion of the rod with respect to the wall thickness of the cylindrical barino, which is regulated by the thickness of this tubular part. However, the conventional molding method of simply filling a cylindrical parison with fluid and inflating it has limitations compared to the professional one, and there is also a limit to the wall thickness of the body. It is.

〔Example〕

FIG. 7 shows the overall shape of an infusion bag 1, which is an example of a thin-walled hollow container according to the manufacturing method of the present invention. The infusion bag 1 is made of ethylene-vinyl acetate copolymer (vinyl acetate content: IQwt%) and includes a flat body part 2 and an upper end tubular part 3 connected to the upper end of the body part 2. It has a lower end tubular part 4 connected to the lower end.

The body part 2 has a mounting hole 5 bored through the flat plate part on the outside thereof. The overall shape of the infusion bag 1 is 130 mm in width.

The height is 250 mm, the bulge of the body is 20 mm, and the outer diameters of the upper and lower tubular parts are both φ15 mm. The difference from the wall thickness is 0.02 mm, and there is almost no variation depending on the location, and the average wall thickness is 0.2 mm, and the wall thickness of the upper and lower end tubular portions is 2 mm. The tubular barisno used at this time had an outer diameter of 50 mm and a wall thickness of 2.2 mm.

In addition, when this infusion bag was manufactured by conventional blow molding, a cylindrical barisno with an outer diameter of 50 mm and a wall thickness of 2.2 mm was used, and the overall shape of the obtained infusion bag was 130 m in width.
m, height 250 mm, body bulge 20 mm, outer diameters of the upper and lower cylindrical parts are both φ15 mm, wall thickness of the upper and lower end cylindrical parts 2 mm, and thickness of the central part X of the body. The thickness was 1.5 mm, the thickness of the end y was Q, 4 mm, and the average thickness of these was 1.1 mm. In this infusion bag, the wall thickness of the body part varies depending on the location, and the wall thickness of the central part X is particularly thick, so that the so-called body part is stiff and it is difficult to allow the contents to drip naturally. FIG. 1 and FIG. 2 show an apparatus used for manufacturing the above-mentioned infusion bag 1 according to an embodiment of the present invention. 11 is a single-layer or multi-layer cylindrical barrisno 20
It is an extrusion type that extrudes. At the center of the lower end of this extrusion 11 is a core 12 (hereinafter referred to as an upper end core 12
). Below the extrusion type 11, there is a split mold 13.degree. 13 which can be clamped around the upper end core 12. This split mold 13.13 is composed of a main mold 14 having an outer shape of the body 2 of a thin-walled hollow container on its inner surface, and a sliding mold 15 having an outer shape of the thin-walled body on its inner surface. . This sliding mold has an inner surface having the external shape of a tubular portion protruding from the main mold 14, and the other end thereof is housed in a sliding recess 16 in the main mold 14. A spring 17 is interposed between the sliding mold 15 and the sliding mold 15 . When the split mold 13 is open as shown in FIG.
The sliding mold 15 protrudes and is not biased by the spring 17.

Below the upper end core 12 is a core 1 for forming a lower end tubular part having an outer diameter that is the same as the inner diameter of the lower end tubular part 4 of the infusion bag 1.
8 (hereinafter referred to as the lower end core 18). This lower end core 18 can be moved upwardly and downwardly by a cylinder 18a provided below.

On the parting surface formed by the split mold 13, two vertical rods extending perpendicularly i from below are provided so as to be located outward from the locus formed by the sliding of the sliding mold 15 that protrudes. It is. These two vertical rods have a mechanism to expand along the parting surface. The expansion speed can be set freely. Furthermore, the two vertical rods can be moved upwardly and downwardly by means of cylinders (not shown).

The manufacturing method of the present invention will be explained in order with reference to FIG. 3 and FIG. 6.

The thermoplastic synthetic resin plasticized and melted by an extruder (not shown) is sent to the extruder 11, and from the extruder 11, a cylindrical barisno 20 having a predetermined wall thickness is suspended between the split molds 13 and 13. . The cylindrical barino 20 has upper end cores 12 and 2.
It hangs down so that the vertical rod 19 of the book is housed inside.

When the lower end of the cylindrical burr 20 reaches the lower end of the split mold 13, the hanging of the cylindrical burr 20 is stopped (FIG. 3).

Next, clamping of the split mold 13.13 is started.

As the mold clamping progresses, the sliding mold 15 protruding inward from the mold comes into contact with the cylindrical parison 20, presses against the cylindrical parison 20 while resisting the spring 17, and closes the upper end core 1 inside the cylindrical parison.
2 and a sliding mold 15 to form an upper end tubular portion 3 whose inner diameter is regulated by the outer diameter dimension of the upper end core 12. When the cylindrical parison 20 is clamped by the sliding mold 15, the mold clamping is stopped. (Fig. 4) Here, two vertical rods 19 placed inside the cylindrical parison
Expand at an appropriate speed. The width of the expansion of the vertical rod 19 at this time is determined by the relationship between the wall thickness of the body 2 of the infusion bag 1, which is a molded product, and the wall thickness of the cylindrical parison 20. (FIG. 5) The sliding mold 15 is again clamped and accommodated in the main mold 14 while compressing the spring 17, and the clamping of the split mold 13 is completed.

At this time, the cylindrical parison 20 is held on its entire circumferential surface by the main mold 14.

After the mold clamping is completed, compressed fluid is blown into the lower end core 18 to perform blow molding, and after cooling for a certain period of time, the lower end core 18 is pulled down by the cylinder 183 and extracted. At the same time, the vertical rod 19 is also pulled down by a cylinder (not shown) and extracted from the molded body 20'. (FIG. 6) The split mold is opened, the molded body 20 is pulled out from the upper end core 12, and the edge portion is removed to obtain the infusion bag 1, thereby completing the manufacturing method of the present invention.

Note that the upper end core 12 and the lower end core 18 are used to regulate the inner diameter of the tubular portion of the infusion bag 1 in the above embodiment, but especially when threading the tubular portion 3, it is necessary to accurately shape the thread. It is effective because it can be reproduced.

However, in the present invention, the effect of attaching a thick-walled tubular portion to a thin-walled body can be sufficiently achieved without regulating the inner diameter with the upper and lower end cores, so the upper and lower end cores can be replaced with blowing needles. You can also do it. Furthermore, depending on the infusion bag, the tubular part may be only at one end, the upper end or the lower end, and the sliding mold may be provided only at one of the upper or lower ends, rather than at both the upper and lower parts as in the above embodiment. is also possible. In the most basic form of the present invention, a sliding mold is provided only on the upper part of the split mold, a blowing needle is used for blowing, and the upper end core and lower end core used in the above embodiments are not used.

In other words, the sliding mold is tightened to form the tubular part, and then the vertical rod previously inserted into the cylindrical parison is expanded to reduce the wall thickness of the tubular body, and then the main mold is tightened and the blowing is performed. Blow molding is performed by ejecting pressurized fluid from a needle.

By the way, in the above embodiment, the sliding mold protrudes due to the spring, and the sliding mold is retracted into the main mold as the mold clamping progresses, but this movement is possible even without the spring. . For example, it is also possible to move the sliding mold in and out using a hydraulic cylinder. The advantage of using a hydraulic cylinder in this way is that it is easy to time the mold clamping, and the movement can be easily controlled electrically.

The infusion bank manufactured as described above has a thick-walled tubular part and an extremely thin-walled body part, so the infusion solution (the contents) drips naturally without applying any external force, making it possible to introduce air into the container. In addition to obtaining a so-called closed system,
Connection was now possible by simply press-fitting the rubber tube. Such an infusion bag can be manufactured very easily and without secondary processing according to the present invention, and can only be manufactured according to the present invention.

FIG. 8 shows the overall shape of a wrist cuff 30 for blood pressure measurement, which is another embodiment of the thin-walled hollow container according to the manufacturing method of the present invention. The cuff 30 is formed of a body part 31 made of a thin elastic body and a thick tubular part 32 provided at one end of the body part 31.
The tubular portion 32 functions to guide outside air into the body portion 31. The arm cuff 30 wraps around the arm and puts pressure on the arm when measuring a person's blood pressure.
It is designed to introduce pressure air of about 100 g to inflate it equally. The cuff 30 has a body part 31 with an extremely thin wall thickness of 0.5 mm, and a tubular part 32 with a thick wall thickness of 2 mm.

The method of manufacturing the arm cuff 30 is the same as the above embodiment and its steps, but it is preferable to use soft polyvinyl chloride for the parison. This soft polyvinyl chloride has an average degree of polymerization of 800 to 12,000, preferably 1,500 to 1.
0,000 polyvinyl chloride and the polyvinyl chloride 100
30 to 220 parts by weight, preferably 50 to 220 parts by weight
Preferably, it contains 2.0 parts by weight of a plasticizer.

If the average degree of polymerization of the polyvinyl chloride is less than 800, mechanical strength such as tensile strength will decrease, while if it exceeds 12.000, the surface appearance of the parison during molding will be poor and the moldability will be extremely poor. Furthermore, if the amount of plasticizer added to the polyvinyl chloride is less than 30 parts by weight, the molded product will become inelastic,
On the other hand, if it exceeds 220 parts by weight, mechanical strength such as tensile strength is significantly reduced. Various other fillers, stabilizers, stabilizing aids, pigments, etc. can also be appropriately blended into the above-mentioned soft polyvinyl chloride.

Since the cuff 30 has a thick tubular part 32 and an extremely thin body part, the process is complicated when connecting it to another rubber tube via a hard pipe, etc. It has the characteristic that the tubular part can be sealed and joined simply by press-fitting it into the pipe without using adhesives, which significantly deteriorate the appearance of the pipe.

Further, in the above embodiment, an expanded version is shown with two vertical rods, but the number of vertical rods of the present invention is not limited to two. For example, four vertical rods are arranged in parallel in a cylindrical parison. It is also possible to expand the two vertical rods while maintaining a constant distance. If this is an example in which the vertical rods are expanded while maintaining a constant distance between them, an insert member may be interposed between the vertical rods, and various parts such as a filtration device may be inserted into the thin body portion. This makes it possible to effectively implement the present invention.

The thin-walled hollow container of the present invention can be used as containers for various other fields, in addition to the infusion bath jig or arm cuff for blood pressure measurement of the above-mentioned embodiments. medical bags for blood or drainage,
It can be widely used in bags for storing automobile window cleaning liquid, containers for squeezing caulking agents or adhesives, etc.

[Effects of the Invention] With the above structure, a container having both a thick-walled tubular portion and a thin-walled body can be easily obtained without secondary processing, and furthermore, the wall thickness of the thick-walled tubular portion can be reduced. can be easily controlled.

[Brief explanation of drawings]

Figure 1 is an overall perspective view of an apparatus for carrying out the manufacturing method of the present invention, Figure 2 is a side view of the same apparatus, Figure 3 is a reverse mold, and Figure 6 shows the steps of an embodiment of the manufacturing method of the present invention. The perspective view shown in FIG. 7 is an infusion bag obtained in the above embodiment, and FIG. 8 is a cuff for measuring blood pressure according to another embodiment. 13...Divided mold 14...Body mold 15.
...Sliding mold 19...Vertical rod 20...Tubular body

Claims (1)

[Claims] A method for manufacturing a thin-walled hollow container integrally having a thin-walled body and a thick-walled tubular portion at one or both ends thereof, comprising: a main body mold having an external shape of the thin-walled body on the inner surface of the mold; and an external shape of the tubular portion. A cylindrical parison made of molten synthetic resin is placed between two split molds facing each other, which are composed of a sliding mold that has a sliding mold on the inner surface of the mold, and the sliding mold is first tightened to form a thick-walled tube. forming a section at one end or both ends of the cylindrical parison,
Next, a plurality of rods previously inserted into the tubular parison are expanded in a direction perpendicular to the mold clamping direction to thin the tubular parison other than the tubular portion gripped by the sliding mold, and then the main mold is removed. A method for manufacturing thin-walled hollow containers by tightening and blow molding.