Method Of Packaging Between Laminated Webs With Heat And Ultrasonic Seals

Abstract

A sealed package of metal-foil-polyethylene laminates, at least one edge of which is sealed by ultrasonic means, to form a rupturable seal through which the contents of the package can be released by moderate pressure on the package walls; and the method of making and filling such a package singly or in groups and with or without integrally attached package portions for receiving articles to which the contents of the rupturable package may eventually be supplied.

Description

It is common, in the medical and surgical field and elsewhere, to package liquid, semiliquid or solid materials in packages formed by sealing together the edges (other than folded edges) of flat sheets of polyethylene or other heat-sealable material, either alone or laminated with other materials including metal foil. The seals thus formed are generally quite durable so that such packages can be opened most accurately by cutting or tearing an end or corner, in a well-known manner.

It is an object of the present invention to provide a package in which one edge, for instance, is closed by ultrasonic sealing, which provides security but which can be opened, to squeeze out liquid or pasty contents, with only moderate pressure and with the assurance that only the specially sealed edge will give way.

The method of making such packages, as described herein, has particular importance in assuring sterility of the contents and facilitating the sterile packing of other articles when a two-compartment package is involved.

Practical embodiments of the invention will be described with reference to the accompanying drawings, in which:

FIG. 1 represents an elevation of a simple package embodying this invention;

FIG. 2 is a flow diagram showing the steps followed in making the package of FIG. 1;

FIG. 3 represents an elevation showing somewhat diagrammatically a group of packages in filling position, with indications of the nature of other steps to be taken to complete the process;

FIG. 4 is a flow diagram showing the steps followed in making the packages of FIG. 3; and

FIG. 5 represents an elevation of a single completed package according to FIGS. 3 and 4.

Referring to the drawings, the package of FIG. 1 comprises front and back walls, each composed of a metal-foil-polyethylene laminate, the polyethylene faces being heat sealed together along both sides 10, 11 and across the bottom 12. Within the pouch or pocket thus formed there is inserted, in a customary manner, a quantity of lubricant 13 or other material up to a desired level 14, and the top of the package is sealed ultrasonically throughout the zone 15. The strength of the latter seal can be predetermined very accurately, ensuring that it is less than the heat seals along edges 10, 11 and 12. Additionally, a weakened point may be formed, as indicated at 16, to ensure breaking of the seal initially at that point when the package is squeezed to release the contents.

Packages of the type just described may conveniently be made by taking the steps indicated in FIG. 2, webs of foil-polyethylene laminate being brought into facing contact at 17, heat sealed at 18 in a pattern designed to produce units having sealed areas 10, 11 and 12 as shown in FIG. 1, filled at 19 with liquid, pasty or dry material, as desired, and then ultrasonically sealed across their top edges in a suitable apparatus 20, the horn of which is shaped and proportioned, preferably, to seal a plurality of adjacent packages in each cycle of operation, each sealed area being as indicated at 15 in FIG. 1.

The welding device 20 is provided with a horn about one quarter inch wide and long enough to span, for instance, four package widths. It acts on the superimposed laminated webs through a "Teflon" coated glass fiber buffer pad (not shown), with a pressure of 40 p.s.i. to 50 p.s.i. for a time of about 3 sec. The seal thus made will not rupture through normal sterilization cycles but ruptures readily, when desired, under a finger pressure of about 10 pounds. Since a normal adult female can exert a thumb pressure of 20-25 pounds without undue exertion, and a male adult can exert 40-45 pounds, it will be understood that a 10 pound squeeze is well within the competence of any prospective user (e.g., nurse or other hospital attendant).

Assuming that the packages have been filled and sealed in groups or in a strip, as would be most efficient, the final step of cutting apart the individual packages is effected at 21. If a sterilization step is required, it can be performed in any suitable manner without affecting the package seals.

In FIG. 3 is represented a group of four two-compartment packages, each designed to have a lubricant or other material enclosed in one compartment, a catheter or other medical or surgical device in the other compartment and a rupturable ultrasonic seal between the compartments.

The initial step in the making of such packages, according to the steps outlined in FIG. 4 involves the provision of a polyethylene (PE) web having a width corresponding to the total length of each package to be formed, and a foil web having a width corresponding to the length of the liquid material compartment, including end and rupturable seal zones. These webs may be laminated together in a known manner, and the laminations are brought together, with the polyethylene sides in contact, at the point 22. Foil-PE laminates are not broadly new, but a PE web with foil laminated only along one edge has a peculiar new utility in the present context.

The facing laminations are then heat sealed together at 23, along parallel transverse zones 23' (FIG. 3), to form a succession of open sleeves, which are cut apart, conveniently, in groups of four (24a, 24b, 24c, 24d) each group being subjected to welding action by the horn of an ultrasonic device 25, the shape of the welded area being shown at 25' in FIG. 3 as a narrow strip extending along one edge of the foil lamination, with wide V-shaped indentations 26 at the middle of each sleeve. The nozzles 27' of a filling machine 27 are inserted in the open ends of each compartment formed in the upper end of each sleeve by the seals 23' and 25', material such as a lubricant is supplied through the nozzles from a source (not shown) to fill each compartment up to a line 28 (e.g., 65 percent to 80 percent of capacity), and the nozzles are removed. The compartments are then heat sealed along the upper margin 29' in the sealing and cutting unit 29, and the packages are separated by cutting on the lines 30, along the center of each zone 23'.

Packages made as just described are suitable for use for packing such medical and surgical items as catheters, drainage tubes and the like which are placed in the enclosed spaces 31a, 31b, 31c and 31d through the open ends shown at the bottom of FIG. 3, said ends being then heat sealed (corresponding to seals 23') and the complete packages sterilized, as by gas, in a well-known manner. In this case the material supplied to the smaller sealed compartments may desirably be a lubricant which, at the time of use, is released by squeezing the compartment to break the seal 25' (starting at the indentation 26) so that the catheter or the like has its tip and at least adjacent portions covered with lubricant while maintained in completely sterile condition.

It is known that heat sealing techniques require that a threshold time-temperature relationship must be established before sealing takes place and it is difficult, if not impossible, to control accurately the seal strength in the face of such critical parameters. By using an ultrasonic seal, the strength of which is a function of easily controlled time and pressure factors, very precise variations in seal strength can be achieved.

Claims

What is claimed is:

1. The method of making a sealed package which includes providing two package elements each being a polyethylene web of extended length and limited width and each having a narrower strip of metal foil laminated adjacent a corresponding edge, bringing the polyethylene surfaces of said elements into facing contact, applying heat to selected areas of said contacting surfaces to heat seal said elements together in said areas, applying ultrasonic sealing means to laminated areas of said contacting surfaces to join said elements together in said laminated areas, the ultrasonic and heat seals cooperating to define a partially enclosed pocket, placing a material to be packaged in said pocket, additionally sealing the elements to complete the closure of the pocket, and severing the filled package from the webs.

2. The method according to claim 1 in which the additional seal is a heat seal.

3. The method according to claim 2 in which the first heat seals extend transversely across the width of the polyethylene webs, the ultrasonic seal extends longitudinally adjacent an edge of the laminated portions spaced from the first mentioned edge, and the additional heat seal extends longitudinally adjacent said first mentioned edge.