US3149772A - Self sealing sachets or containers - Google Patents

Description

Sept. 22,v 1964 c. F. oLssoN SELF SEALING sAcHETs oR CONTAINERS *Filed Dec.

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@mais Umso/v @Ya/WMM United States Patent O 3,149,772 SELF' SEALING SACHE'IS 0R CONTAINERS Charles F. Olsson, Johannesburg, Transvaal, Republic of South Africa, assignor to Technipak (Proprietary) Limited, Johannesburg, Transvaal, Republic of South Africa Filed Dec. 4, 1961, Ser. No. 156,683 Claims priority, application Republic of South Africa, Dec. 7, 1960, 4,987/60; Jan. 6, 1961, 64/61; Mar. 20, 1951, 1,146/61 1 Claim. (Cl. 229-62) This invention relates to sachets or containers for liquids or iluent materials that approximate to liquids in their behaviour, at least the closure of which is made of thin plastic sheeting. Fluent material of this sort is included herein in the term liquid.

Conventional sachets are not cap-able of standing stably upon their bases, as are bottles and other containers of rigid material so that, once they have been opened and while they still contain liquid, Ithey cannot be placed, unpropped, upon a table top. This is a serious disadvantage when the contents are to be consumed slowly.

The invention is further concerned with the packaging of gas-charged, or gas-generating liquids, or of gases themselves, in containers. More particularly, the invention relates to the packaging of liquids containing or generating carbon dioxide, and especially to the packaging of highly active preparations such as kaflir beer, in which there is prolonged and vigorous generation of carbon dioxide for a considerable period after brewing and packaging.

The usual methods of packaging or bottling of liquids have hitherto not been practical or economical in the case ot kailir beer without prior refrigeration or ageing to reach a state of greatly reduced activity or generation of carbon dioxide. The beverage in either of these states is traditionally regarded as unpalatable and unfit for consumption.

It is, therefore, an object of the present invention to provide a sachet which enables carbonated beverages to be packaged and transported safely and without aiiecting its carbonated or carbon dioxide-forming state significantly. A further object of the invention is to provide a sachet which can be placed upon a table top or the like without spillage of its liquid contents.

A sachet or container according to the invention consists in two superimposed layers of plastic sheet material secured together to define between them a passage for liow of iiuid, the passage extending along an end oi the container so that distortion of the container by its iluid contents will cause at least one kink to form across the passage. The kink serves as a valve, which is opened by an increase in pressure, because the passage is of considerably greater than capillary size; and a port connects the inner end of the passage with the cavity of the sachet.

The closure may be open to atmosphere at the outer end remote from the port, or may be closed and be severable to form an outlet to atmosphere.

Preferably the passage is formed by heat-sealing the superimposed layers along substantially parallel lines spaced apart, the innermost line being discontinued to provide the port and, if necessary, the outermost line being discontinued to provide the outlet.

The invention also includes a method of filling the sachet or container.

A number of embodiments of the invention is illustrated in the accompanying drawings in which FIGURE l is a face view of one form of closure,

FIGURE 2 is a face view of a second form,

FIGURE 3 shows the form of FIGURE 1 but with kinks across the passage,

FIGURE 4 is a plan View of the illed sachet,

FIGURE 5 is a face view of another form of closure, and

FIGURE 6 is a face view of yet another form of closure.

The sachet is conveniently and indeed for preference made of polythene sheeting formed to tubular shape and then ilattened. The gauge is not critical, provided the material is robust enough for its task. Lengths are cut from the attened tube to form individual sachets.

In the case of FIGURE 1, the closure is formed by heat-sealing two parallel lines or zones 1t), 12, oiiset laterally from one another. The line 10 extends from the border 14 of the sachet towards but not up to the opposed border 16. The line 12 extends from the border 16 towards but not up to the border 14.

The space between the lines 16, 12 constitutes the passage 18 referred to above. The space 20 between the line 12 and what will be the cavity of the sachet when the latter is expanded forms a port between the cavity and the passage, while the space 22 provides an outlet from the passage to atmosphere.

In FIGURE 2, the line 12 is the same as in FIGURE l, but the line It) extends right across the width of the sachet to form a seal.

In FIGURE 5, three heat-sealed lines 24, 26, 28, are provided alternately staggered.

FIGURE 6 is a variant of FIGURE l, in which the outer seal 11 is continued across the sachet and egress of gas into the atmosphere is by way of a hole or holes 13 in one orboth walls of the passage 1S, near to the end of the passage, remote from the port 22.- In other words the hole or holes 13 is or are the equivalent of the outlet 22.

In use, the sachet is iilled, through the open bottom which is then heat-sealed, or from the top and the closure is then applied, or by an injector tube.

This bulges the body of the sachet as indicated in FIGURES 3 and 4. As the lines lil,` 12 or 24, 26 and 28 do not permit bulging, except in a portion of the closure zone, constituted by the passage 18 up to the kink, that zone, in accommodating itself to the swollen condition, becomes kinked, as indicated at 30, obliquely or laterally to the length of the lines. The presence of the kink or kinks causes the walls of the passage 18, at the corner 32 of the kink, to be iirmly pressed together and to offer more resistance to luid iiow along the passage 18 than is oered by the portions of the passage between the kinks.

The kink 3i) or several kinks may be artiiicially produced as a permanent feature of the sachet, during fabrication, but this will not usually be necessary.

It the substance put into the sacket be gas-producing, such as the beverage known as kailir beer, the peculiar attributes of which have been discussed above, then the sachet of FIGURES 1 or 5 is used. As the gas is evolved, the passage 18 offers an initial resistance to gas flow but rapidly yields when the pressure has built up suiiciently within the sachet. However, the kink 3i! continues to otter resistance until it is overcome and gas flows past it. It there is a second kink, the same thing happens, until the gas escapes to atmosphere. Pressure within the sachet is thus relieved. If gas generation continue, the balance is again disturbed, a quota of gas forces its way along the passage up to the kink or kinks past it or them and so to atmosphere; and so on.

The pressure at which escape occurs is dependent upon the width of the passage, the flexibility of the plastic material, the dimensions of the port 2t) and the outlet 22, the number of kinks Sti (and here the formation of artificial kinks can be used to predetermine the escape pressure) and finally upon the extent and nature of the passage.

amarre D) Thus a tortuous passage as shown in FTGURE will oder greater resistance to escape of gas than a single passage as shown in FIGURE 1.

Here a most important point must be mentioned. It is essential that the width of the passage 18 be such that when expanded to the maximum, that is when the passage approximates as closely as possible to cylindricality, the duct thus formed is considerably greater in diameter than a capillary tube, because if it be in the capillary range the duct is virtually impenetrable to fluid and the closure will not act as a pressure-relieving valve.

It should be mentioned that in the case of a beverage such as katiir beer the escaping gas is not in fact purely gaseous. It entrains froth and liquid particles with it, so that it is more a series of bubbles than a gas ilow that passes along the passage.

it can be taken in these circumstances that a capillary tube is one whose bore does not exceed about 4.0 mm., which means that the passage when collapsed must be considerably more than 6.2 mm. or say 1A in width. For practical purposes, this dimension should be above 3/5". At the same time, the passage should not be too wide, else resistance to flow is too low, and if the sachet be laid on its side liquid will leak through the passage. In practice a 9/16" width is satisfactory with 300 g. low density polythene to pass excess gas while obstructing ilow of liquid under normal conditions. Thus the iilled sachet can be safely handled without leakage and indeed can be inverted.

Emptying of the sachet can be achieved either by cutting away a top corner of the sachet to bypass the passage, or by taking advantage of the sachets elasticity and squeezing it, when the rise in pressure in the cavity will cause the liquid to be squirted through the passage. It will be realized that this is another and very cogent reason why the passage must be supracapillary. If it were not, the sachet would burst before liquid could be propelled along the passage.

If the packaged liquid be not gas-evolving, or if the gas evolution be not such that bursting pressures can be built up in the sachet under the most adverse conditions likely to be encountered in normal use (for instance if the liquid be wine or milk), then the embodiment of FIGURE 2 can be put to use. It so, then opening of theisachet consists in shipping oit one corner 34;, as indicated by the dotted line in FIGURE 2.

It is observed that, with still liquids, only a small kink is formed on iilling, but when pressure is applied by squeezing the sachet, the kink is immediately accentuated.

The passage 18, formerly closed to atmosphere, is now free to pass liquid under pressure produced by squeezing the sachet; but when the pressure is relaxed the sachet can be laid on its side without leakage, because the passage 1S is eiective to inhibit ow. The major objection to packaging of liquids in sachets-that once opened the sachet must be emptied or the sachet propped up-is thus removed. Spillage is avoided and the contents continue to be shielded from atmospheric contamination.

It is pointed out that a further field of application of the closure described lies in the eld of the storage of gases or of gas-evolving liquids other than beverages. In this case the closure constitutes a pressure-relief valve which is applied or secured to a container in which the gas or liquid is stored and which may be rigid. Dangerous pressures due for instance to temperature rise are automatically and continuously relieved by leakage of gas alonfY the passage 18. The pressure at which the Valve yields can be nicely predetermined by selecting the width of the passage, the multiplicity of its convolutions, and so on. Thus, by careful design any required pressure can be contained and maintained, provided the material will withstand that pressure.

I claim:

A bag comprising a pair of sheets of thin flexible thermoplastic sheet material joined by first and second parallel lines of heat sealing spaced apart at least 1% and extending along and lengthwise of an end of the bag, said first line having an interrupted portion providing a iirst opening, means for providing a second opening for bypassing said second line spaced a substantial distmce from said first opening, the area between the sheets and between the lines being connected to the interior of the bag through said first opening.

References Cited in the tile of this patent UNITED STATES PATENTS 2,541,67/1r Snyder Feb. 13, 1951 2,708,067 Paton May l0, 1955 2,800,269 Smith July 23, 1957 3,033,911 Daddy May 8, 1962 FOREIGN PATENTS 29,504 Finland lune 30, 1958 338,137 Switzerland June 15, 1959 1,096,827 Germany Jan. 5, 1961

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