Fluid container of the flexible wall capsule type

Abstract

A fluid container of the flexible wall capsule type in which the contents of the capsule may be discharged by applying pressure to the flexible walls of the capsule comprises two layers of sheet material of similar size and shape which form two opposed walls of the capsule and which are sealed together along marginal areas extending around the entire periphery of the capsule to provide a space between the unsealed areas of the walls of the capsule within which the fluid is confined. The major portion of said marginal areas is strongly sealed while a lesser portion thereof is weakly sealed, and a portion of the weakly sealed portion is modified to leave a sealed area of limited predetermined size at a predetermined location where, when pressure is applied to the unsealed areas of the walls of the capsule, the seal will be broken between said layers only within said limited area to provide an opening of limited predetermined size located at a predetermined position of the free edge of the capsule, whereby both the rate of flow and the location of the flow of fluid may be controlled.

Description

This invention relates to fluid containers of the flexible wall capsule type in which the fluid contents of the capsule may be discharged by applying pressure to the flexible walls of the capsule.

Flexible wall capsules are known which comprise two layers of sheet material of similar size and shape which form two opposed walls of the capsule, which said layers are sealed together along marginal areas extending around the entire periphery of the capsule to provide a space between the unsealed areas of the walls of the capsule within which the fluid contents are confined.

It is an object of the present invention to provide a portion of the said sealed marginal areas of the capsule which is of limited area and which is easily frangible when pressure is applied to the unsealed areas of the walls of the capsule to provide an opening of limited predetermined size located in a predetermined position through which the contents of the capsule may be discharged in a controlled manner.

It is a further object of the invention to provide a pad of spongy material capable of absorbing and holding liquids in suspension, which said body is contained within said space and, in combination with said opening of predetermined size, is capable of metering the flow of the contents of the capsule through said opening in accordance with the pressure applied to the unsealed areas of the walls of the capsule.

Other objects and advantages of the invention will appear hereinafter.

A preferred embodiment of the invention is shown in the accompanying drawings, in which,

FIG. 1 is a front elevation of a prior art capsule

FIG. 2 is a side elevation thereof

FIG. 3 is a front elevation of a capsule according to the invention

FIG. 4 is a side elevation thereof

FIG. 5 is a front elevation of a modified form of capsule according to the invention, and

FIG. 6 is an enlarged section on the line 6--6 of FIG. 5.

Referring to FIGS. 1 and 2 which disclose a known prior art fluid container of the flexible wall capsule type comprising two layers 1 and 2 of flexible sheet material of similar size and shape, usually rectangular. The choice of sheet material is determined by the nature of the contents of the capsule and may be of single ply or multi-ply construction. It must, of course, have adequate strength to prevent tearing or puncturing when subjected to reasonable use, and it must be impermeable to the contents of the capsule. Plastic films and impregnated paper are frequently used. Polyethylene film is particularly well adapted to use for containing a wide variety of fluids. If desired, one ply of a multi-ply sheet material may consist of metal foil such as tin or aluminum foil.

Preferably the sheet material is thermoplastic or heat sealable if used in single ply form, and in the case of multi-ply sheet material at least the innermost ply is preferably heat sealable. Alternatively, the sheet material may be coated with an adhesive material along those marginal areas which are to be sealed.

In the prior art capsules as illustrated in FIGS. 1 and 2, the marginal areas 3, 4, 5 and 6 are all sealed by any suitable method, but preferably by applying heat to the marginal areas of heat sealable thermoplastic material. The unsealed areas surrounded by the sealed marginal areas forms a space to confine the dispensable material. However, the seal along the three marginal areas 4, 5 and 6 which constitute the major portion of the sealed areas is strongly sealed while the seal along the shorter marginal area 3 is weakly sealed. This strengthening of the said marginal areas 4, 5 and 6 is usually effected by embossing the areas in any suitable pattern such as the crossed lines shown in FIG. 1 using conventional embossing tools and known embossing techniques.

The seal along the shorter marginal area 3, being weaker than the seal along the marginal areas 4, 5 and 6 is more easily susceptible to being broken when pressure is applied to the unsealed areas of the capsule. The difficulty is that both the location of the area where the seal will be broken and the extent of the area where the seal will be broken when pressure is applied to the unsealed areas is unpredictable, and in many cases, the entire weakly sealed area may be broken. As a consequence, the flow of liquid from the capsule is uncontrolled and undirected, and in most cases, the entire contents of the capsule will be discharged by a single application of pressure. This frequency results in waste of the contents of the capsule.

According to the present invention, a capsule is formed in a manner similar to the capsule of the prior art as shown in FIGS. 1 and 2, in that as shown in FIGS. 3 and 4, it comprises two layers 11 and 12 of sheet material of similar size and shape and of the general nature and characteristics above described with respect to the prior art capsules. As in the prior art, the marginal areas 13, 14, 15 and 16 are all sealed as previously described, and as in the prior art, the seal along the three marginal areas 14, 15 and 16 which constitute the major portion of the sealed areas is strongly sealed while the seal along the shorter marginal area 13 is weakly sealed. As previously described, the strengthened sealing of the three marginal areas 14, 15 and 16 is preferably accomplished by embossing those areas.

According to the present invention, however, a portion of the seal along the weakly sealed marginal area 13 is modified to leave a sealed area of limited predetermined size at a predetermined location where, when pressure is applied to the unsealed areas of the walls of the capsule, the seal will be broken between said layers only within the said limited area to provide an opening of limited predetermined size at the free edge of the capsule whereby both the rate of flow and the location of the flow of discharged fluid may be controlled.

Thus, as shown in FIGS. 3 and 4, the seal within the marginal area 13 is strengthened within spaced areas 17 and 18 thereof lying on both sides of the weakly sealed area 19 which leads to the intended opening 20, the size and location of which may be predetermined by the location of the areas 17 and 18 and the space therebetween. In the preferred embodiment illustrated, the strengthened areas 17 and 18 are formed by embossing as previously described, and they extend diagonally across the less strongly sealed area 13. Thereby, when pressure is applied to the unsealed areas of the capsule within the sealed marginal areas, the seal will be broken only at the weakest area, i.e., across the weakly sealed area 19 leading to the opening 20 which is formed at the marginal edge as the seal is broken. It will be understood that the flow through the opening 20 will be metered by and dependent on the size of the opening and may be varied as desired from drop by drop to a more copious flow. It will also be understood that the opening 20 will tend to close as soon as the pressure on the unsealed areas is released, thus preventing or at least restricting unintended discharge of fluid.

An alternative modification of the seal along the weakly sealed marginal area 13 is shown in FIG. 5 in which again the capsule is similar to the prior art in that it comprises two layers of sheet material of similar size and shape (see FIG. 4) of the characteristics previously described which have marginal areas 23, 24, 25 and 26 which are sealed as previously described. That is, the marginal areas 24, 25 and 26 are strongly sealed while the marginal area 23 is weakly sealed.

In the form of the invention shown in FIG. 5, however, the seal along the marginal area 23 is also modified to leave a sealed area of limited predetermined size at a predetermined location where, when pressure is applied to the unsealed areas of the walls of the capsule, the seal will be broken between the layers only within the said limited area to provide an opening of limited predetermined size at the free edge of the capsule.

Thus, as shown in FIG. 5, an unsealed area in the form of a notch 27 extends outwardly from the inner edge of the marginal area 23 toward the free outer edge thereof leaving only a narrow sealed area 28 therebetween which is quite weak. Thereby, when pressure is applied to the unsealed areas of the capsule within the sealed marginal areas, the seal will be broken at its weakest area, i.e. at the area 28 where the sealed area is very narrow.

The utility of the capsules and their ability to meter the dispensing of the contents may be further enhanced by the insertion of a pad 30 of spongy material into the space between the unsealed areas of the walls as shown in FIG. 6. The term "spongy material" as used herein is not limited to cellular or porous material but applied also to woven and unwoven fibrous and other materials which are capable of absorbing fluid contained within the capsule, and holding it in suspension awaiting application of pressure to release it. The combined metering effects of the opening of limited predetermined size and of the pad of spongy material makes possible exceedingly accurate control over the discharge of the contents of the capsule. This is especially true of liquids of low viscosity which, in the absence of such a pad, tend to leak from the capsule once the seal is broken. With such a pad, such liquids are held in suspension even after the seal is broken and the rate at which the liquid is discharged is easily controlled by varying the pressure applied to the pad.

Claims

What is claimed is:

1. A flexible wall capsule comprising two layers of sheet material of similar size and rectangular shape which form two opposed walls of a rectangular capsule, which said layers are sealed together along marginal areas extending around the entire periphery of the capsule to provide a space between the unsealed areas of the walls, the marginal areas of three sides of said rectangular capsule being more strongly sealed than the marginal areas of the fourth side, the marginal areas of said fourth side being modified by the provision of two strengthened sealed areas having edges extending diagonally in opposite directions across the less strongly sealed marginal areas of said fourth side from the two adjoining more strongly sealed marginal areas and terminating at the free edge of said fourth side, said diagonally extending edges of said strengthened sealed areas being spaced apart at the said free edge of said fourth side to leave a weakly sealed area of limited predetermined size at a predetermined location between said diagonally extending areas where, when pressure is applied to the unsealed areas of the walls of the capsule, the seal may be broken between said layers only within said limited area to provide an opening of limited predetermined size at the free edge of the capsule to meter the flow of material from said space.

2. A capsule according to claim 1 in which said strengthened sealed areas of the fourth side are strengthened by embossment.

3. A capsule according to claim 1 including a pad of spongy material confined within said space.