JPS627078B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improved method of forming a frangible seal of the type in which a first member is hermetically fused to a second member. Although the illustrated embodiment relates to sealing a closure to a container, it should be understood that the invention relates to a method that can be used to seal various types of plastic parts that are subsequently separated. .

Sterile medical solutions, such as 5% glucose solution and physiological saline, are supplied to the hospital for intravenous injection into the patient's veins from containers suspended above the patient. The sterile liquid flows down by gravity through a tubular administration set connected at one end to the container and at the opposite end to an intravenous needle to the patient.

Such containers are often formed from thermoplastic material and include a neck having one or more mouths or openings therethrough. Such openings are typically hermetically sealed to provide the container with a sterically sealed contents.

The mouth area should preferably be in a sterile environment. Thermoplastic closures bonded directly to the neck of the bottle experience the difficulty of requiring large forces to break or remove the closure. Thermoplastic closures are known that have a breakable section around the base that is provided with a row of slots or cuts in the closure. Such closures do not maintain a sterile environment within the closure. An example of this type of closure is shown in US Pat. No. 3,904,060.

Thermoplastic closures are also known that are joined completely around the base to form a hermetic seal, with the break portion formed adjacent to the seal. The fracture section typically requires bending shear forces to break, and the forces required are often too great for many applications. An example of a closure requiring a screw ring with separate threads to provide bending shear to fracture the fractured portion is disclosed in U.S. Patent No.
No. 3923182.

As protective caps for plastic containers used in medical applications, constructions with multiple holes or cuts to break the cap from the container are unsuitable because bacteria can enter therethrough. In addition, the structure in which the entire base of the protective cap is heat-sealed to the neck of the container requires excessive force to break the cap, resulting in a screw jam (a structure based on the same principle is seen in molded caps for Western liquors and drinks). must be used.

As described above, it is difficult to achieve both sealing performance and breakability of the protective cap, and it has been difficult in the prior art to satisfy these two requirements at the same time.

The present invention solves these difficulties and provides a sealing method for hermetically sealing, for example, the neck of a plastic container with a plastic protective cap, which does not require excessive force to break the protective cap. With the goal.

Another object of the invention is to provide a method that allows for simplified closure construction, particularly by avoiding the need for an annular lip extending outwardly from the closure to seal the closure to the container. There is a particular thing.

Other objects and advantages of the invention will become apparent as the description progresses.

In accordance with the present invention, there is provided a method of forming a breakable seal of the type in which a first plastic member is hermetically fused to a second plastic member.
The method includes attaching the first member onto the second member such that the first member substantially seats on a surface of the second member. The sealing mold is heated above the melting point of the material of the member. A sealing mold is brought sideways toward and in heat exchange relationship with a portion of the first member toward the second member surface on which the first member is seated. A sealing mold is forced into the surface of the second member, melting the surface and a portion of the first member. The surface of the second member moves to form a fused seal perpendicular to the surface such that when the first member is removed from the second member, the seal ruptures due to tensile stress. be done.

In the illustrated embodiment, the sealing mold is heated to a range of 0.5 to 55°C above the melting points of both parts. The surface is compressed by at least 0.013 cm from its original height by the sealing action of the mold.

In the illustrated embodiment, the first member comprises a plastic cup closure and the second member comprises a flat surface portion of the container neck. The sealing mold has an inner dimension substantially equal to the outer dimension of the sidewall of the obturator, and the sealing mold is brought vertically downwardly and around the sidewall in heat exchange relationship so that the sealing mold The mold is pressed into the flat surface of the container neck.

Further details are set forth in the description and claims below, and are illustrated in the accompanying drawings.

FIG. 1 is a partial perspective view of a container with a protective closure sealed to the neck of the container according to the method of the present invention.

FIG. 2 is a sectional view of the front.

FIG. 3 is an enlarged partial view of the closure and the frangible seal of the container prior to rupture.

FIG. 4 is an enlarged partial view of the fragile seal portion of FIG. 3 after rupture. FIG. 5 is a diagram illustrating an assembly process during manufacturing and assembling the container shown in FIG. 1.

Referring now to the drawings, a thermoplastic container 10 having a body 11 and an integral neck portion 12 is partially illustrated. The neck portion 12 is integrally formed with the body 11 of the container 10 in a conventional manner. In the illustrated embodiment, a mouth 15 is provided, shown here as a mouth tube integrally formed with and projecting from the neck portion 12.
The mouth tube 15 has a screw-in closure cap 1.
6 and hermetically sealed.

In accordance with the present invention, a thermoplastic protective lid or device 20 covers the cap 16 to create a hermetically sealed sterile environment. Obturator 20
is generally cup-shaped having a generally circular cross-sectional shape, having a bottom edge 22 and a sidewall 24 extending upwardly from the bottom edge. Preferably, sidewall 24 is sloped slightly upwardly and inwardly toward the central axis of obturator 20. The sidewalls extend to an integrally formed top 26 and the entire cap 20 is fabricated as a single molded member.

The method of attaching the closure 20 to the container 10 is the fifth method.
Illustrated in the figure. As shown therein, closure 20 is mounted over the mouth or opening such that its bottom edge 22 rests on or abuts flat upper surface 27 of neck portion 12 . A heated pressure sealing mold 28 is heated above the melting point of the plastic material. Sealing mold 28 has an inner diameter that is substantially equal to the outer diameter of the lower portion of sidewall 24 adjacent bottom edge 22 .

A sealing mold 28 is brought downwardly onto the obturator and into heat exchange relationship with the sidewall portion adjacent the bottom edge 22. Subsequent downward pressing of sealing mold 28 forms a depression 34 in surface 27. Both surface 27 and sidewall 24 are fused and a portion of fused surface 27 is moved to form a fused seal 30 perpendicular to surface 27 as shown in FIG. The downward heating and pressurization thus moves the material on the container surface to form a thin vertical wall 30 in the inner diameter area of the sealing mold;
An annular bead 32 is then formed around the recess 34. In this way, a frangible web or section 30 is formed on the vertical sidewalls of the recess 34 and perpendicular to the recess. Advantageously, the frangible section 30 ruptures under tensile loads so as to produce a horizontal rupture as shown in FIG. One suitable polyolefin, such as polypropylene, has a tensile stress whose bending yield point is between 442 and 562.
Kg/cm ² while it ranges from 302 to 387 Kg/cm ² . The seal therefore ruptures under less load than existing commercial seals, making removal of the closure easier. This closure device can therefore be used in conjunction with a screw jack, but
No screwdriver is required to rupture the weakened section. Additionally, the illustrated horizontal fracture of the weakened section minimizes snagging of the section due to the relatively clean and simple fracture of the weakened section compared to a weakened section that requires shear force rupture. The closure seals completely around the mouth without vents or holes, thus ensuring sterility.

The obturator 20 is made long enough to provide a mechanical advantage or leverage such that when pushed sideways by hand, the weakened portion is ruptured. It has been found that a length at least equal to the diameter is satisfactory.

Thermoplastic materials suitable for containers and closures include:
Includes various polyolefins such as polyethylene, polypropylene, polyaromers and copolymers thereof. The heated mold 28 is preferably heated to a temperature in the range of 0.5 to 55°C above the melting point of the plastic. A temperature of 22.5°C above the melting point of the plastic produces satisfactory results.

In a particular embodiment, an indentation 0.0508 cm deep (dimension a in Figure 3) is formed and a thin vertical weakened section 3 0.013 cm wide perpendicular to the flat surface of the neck.
0 remained. Preferably, the depression has a depth of at least 0.013 cm. The vulnerable part 30 is
Tensile stress when the obturator is removed generally causes it to fracture horizontally.

The present inventors previously proposed in Japanese Patent Application No. 53-29213 (Japanese Patent Publication No. 61-3691) that a flange was provided on the outer periphery of the bottom edge 22 of the cup-shaped closure 20, extending outward and integral with the bottom edge. A method of forming a seal having a fragile thin section 30 by welding the flange and the surface 27 by means of a heated mold 28 has been proposed.

Similar to the invention of Japanese Patent Publication No. 61-3691, the present invention also covers the neck of a plastic container, which is easier to break than the adhesive protective cap of the prior art, although it has an adhesive property that is particularly important in medical applications. This allows for the formation of a security cap.
This does not require twisting the cap to rupture the frangible seal formed by the present invention;
This is because the cap can simply be pushed to the side and a tensile stress applied to the broken area by leverage. This is due to the fact that thermoplastics such as polypropylene generally have lower tensile strength than their bending strength, and the present invention provides a thin section with a sealable wall thickness of 0.013 cm or less. This is because it is formed.

In addition, according to the present invention, there is no need to provide an annular flange on the outer periphery of the bottom edge of the protective cap before sealing, unlike the invention of Japanese Patent Publication No. 61-3691. If such an annular flange is made too thick, a thin broken part will not be formed when it is heat welded to the upper edge surface of the container neck, so it needs to be formed thinner than the side wall of the protective cap body. Injection molding of molded parts with different wall thicknesses requires special consideration. However, according to the present invention, since there is no need to provide the annular flange itself, it is superior to the present inventors' invention in Japanese Patent Publication No. 61-3691 in that it uses a protective cap with a simpler structure. ing.

Although specific examples have been shown and described that illustrate the invention, various modifications and substitutions may be made by those skilled in the art without departing from the novel spirit and scope of the invention.

[Brief explanation of the drawing]

1 is a partial perspective view of the container with a protective closure, and FIG. 2 is a front sectional view thereof. FIG. 3 is an enlarged sectional view of the fragile seal portion before rupture, FIG. 4 is an enlarged sectional view of the portion after rupture, and FIG.
The figure is a drawing of the assembly process of the container of FIG. 1. 10 is a thermoplastic container, 12 is a neck, 15 is a mouth, 16 is a closure cap, 20 is a protective closure, 2
2 is the bottom, 24 is the side wall, 27 is the top surface, 28 is the sealing mold, and 30 is the fragile cross section.

Claims (1)

[Scope of Claims] 1. A method of forming a breakable seal of the type in which a first plastic member is hermetically fused to a second plastic member, the first member being attached to a surface of the second member. attaching a first plastic member onto a second plastic member so as to substantially seat the first plastic member; heating a seal mold to a temperature above the melting point of the first plastic member; moving the member toward the surface of the second member seated thereon and laterally to and in heat exchange relationship with a portion of the first member; pushing the seal mold into the surface of the second member such that a portion of the first member melts and moves to form a transverse fused seal against the surface of the second member; said method, thereby forming a frangible seal such that tensile stress causes said seal to rupture when said first member is removed from a second member. 2. the first plastic member is a plastic cup closure, the second plastic member is a plastic flat surface, and the plastic cup closure is seated in an inverted position on the plastic flat surface; A method according to claim 1. 3. The plastic cup closure has a generally circular cross-sectional shape, the side walls thereof slope upwardly and inwardly in the inverted position, and the sealing mold has an inner diameter substantially equal to the maximum outer diameter of the side walls. The method according to claim 2, comprising: 4. A method according to any one of claims 1 to 3, wherein the sealing mold is heated to about 0.5 to 55 degrees Celsius above the melting points of the first and second plastic members. 5. The surface of the second plastic member is recessed from its original height by at least about 0.013 cm by the sealing action of the mold. Method.