GB2110771A - Hand-held pump-type dispensers - Google Patents

Abstract

A small hand-held pump-type dispenser for liquids such as perfumes which must be kept out of contact with the atmosphere comprises a rigid closed container (4), fitted with a single-acting suction- delivery pump (3) with a capillary dip tube, sealed without access to atmosphere and filled at least partially with a liquid (11) under a pressure which is not greater than atmospheric pressure. The void space may contain an inert gas. There is an increasing depression in the container as the liquid is dispensed. Preferably the pump has a capilliary dip tube of less than half the useful volume of the pump. <IMAGE>

Description

SPECIFICATION Hand-held pump-type dispensers and their use This invention relates to small hand held dispensers of the pump-type for liquids that need to be shielded from atmospheric contamination.

The handling of liquids which are affected by atmospheric air, notably perfumes, presents a number of problems.

Such products are still often dispensed by atomisers operating under the action of a jet of air obtained, for example, from a rubber bulb. In this case the contamination by atmosphere is at a maximum.

Equally, suction and delivery pumps have been used, causing atomisation of the liquid by a mechanical swirl action. Contamination is a little less marked than with atomisers, but all the methods of handling of this type used hitherto assume that the liquid dispensed is to be replaced by fresh air introduced into the container. Thus they allow oxidation of the perfume or other product contained within the container.

To reduce this drawback it has been proposed to enclose the liquid in the container under the pressure of an inert gas, generally nitrogen, and to distribute it by means of a pump.

In this way the liquid is maintained out of contact with the air throughout the useful life of the container but the pressure of the gas injected into the container inhibits, at least at the start of use of the filled container, the efforts to actuate the pump, which a certain type of user could consider unacceptable.

Moreover the manufacture of this kind of dispenser is relatively troublesome as it involves the step of injecting gas under pressure into the interior of the container in addition to filling it with liquid.

The present invention has as its aim the reduction of the above-mentioned drawbacks in the known dispensers.

According to the invention a process for packaging and dispensing liquids to be dispensed from a hand-held container with a pump is characterised in that the liquid is contained in a rigid closed container, the container is fitted with a single-acting suctiondelivery pump without any provision for venting atmospheric air back into the interior of the container, and the liquid is dispensed by the pump with the progressive creation of an increasing depression within the container, below atmospheric pressure.

The invention also comprises a dispenser for putting the process into practice comprising a rigid container fitted with a single-acting suction-delivery pump, sealed without access from atmosphere, and filled at least partially with a liquid under a pressure not greater than atmospheric pressure.

Preferably the pump has a piston of a diameter between 3 and 10 mm.

The return spring for the piston of the pump on suction may have a force (at rest) of between 0.45 and 5 daN.

The dispenser according to the invention can be filled with liquid to an extent of more than 70% of its volume, and possible at least 90%.

In one preferred embodiment for handling perfumes or other products sensitive to oxidation, one could fill the void remaining in the container above the liquid with an inert gas having a density at least equal to that of the air, the gas being for example carbon dioxide, nitrogen, a chloro-fluoro hydrocarbon, nitrogen monoxide, butane or propane.

The dispensing of a liquid by means of a pump with the creation of an increasing depression inside the container, results in a number of advantages in simplicity of operation and flexibility in use.

The pressure which has to be exercised on the piston of the pump to obtain good atomisation is less than that necessary to actuate a pump of the standard kind in a dispenser that includes a vent from atmosphere to the interior of the container.

Moreover, for dispensing perfume, it is found that the dispenser having the pump working against a depression is better than the traditional equipment operating at atmospheric pressure.

In fact one notices a fresher and more lively fragrance than with the conventional kind of dispenser. It appears, in fact that the depression produced within the container has an added tendency to augment or increase the "note" of the perfume.

However, handling under a depression could in certain cases cause loss of priming in the pump at the end of a relatively short period of use, less than a single day.

The standard solution for avoiding loss of priming consists in fitting the pump inlet with a non-return valve. However such a valve has the drawback of adversely affecting the operation of a depression pump and necessitating the addition of extra components, which adversely affects the selling price.

It is generally admitted that a pump does not operate on the first dispensing stroke and that one obtains actual dispensing of the liquid only on the second, or at worst, on the third stroke.

The invention equally well allows a reduction in the drawback of loss of priming of a depression pump without necessitating extra components and without modifying the assembly of the equipment.

According to a further feature of the invention, the pump is fitted with dip tube at its inlet, leading from the bottom of the interior of the container, the internal volume of this tube being not more than half the useful volume of the pump.

Preferably the dip tube is a capillary dip tube of an inside diameter less than about 1 mm.

The invention will be better appreciated by reading the following detailed description in conjunction with the accompanying drawing which illustrates an embodiment of the invention by way of example.

The dispenser illustrated comprises essentially a rigid closed container 4 in the form of a metallic can of the kind currently used for so-called aerosol containers, preferably a container of coated sheet steel, as illustrated, or equally of aluminium or glass. The open end of this container is closed by a crimped metallic mounting cup 8 having a central opening 1 3 through which passes an actuating stem 1, integral with the operating piston 2 of a single-acting suction/delivery pump 3 of the standard kind, of which the pump body 5 has at its lower end a recess 6, to receive the upper end of a capillary dip tube 10 for admitting the liquid 11 to be dispensed. The body of the pump 5 terminates at its upper end in a collar 7 crimped into the mounting cup 8.A resilient gasket 9, compressed by an annular rib 12 on the body of the pump 5, provides a seal and isolates the interior of the container 4 from atmosphere.

A button 1 5 fitted on the end of the stem 1 of the pump allows the pump to be actuated against the action of a return spring 1 4 which effects the suction stroke of the piston 2 through the intermediary of a small auxiliary piston 1 7 of which the pointed upper end 1 8 forms a valve head blocking the internal discharge passage 1 9 of the stem 1 that leads to an atomiser nozzle 1 6 carried by the button 15.

This pump is of known construction and could be replaced by any other kind of pump, in particular of the type having a non-return valve of the type comprising a ball loaded by a spring.

A process of manufacture which is particularly practical and adaptable to the assembly lines designed for the assembly of standard dispensers consists in purging the air from the container 4 by injecting an inert gas of a density at least equal to that of air, then introducing into the container the desired quantity of liquid 11, putting the pump-carrying mounting cup 8, complete with the pump 3 and the button 1 5 in place, on the neck of the container, and crimping the cup to the container.

Thus the liquid is trapped in the interior of the container 4 in contact with the inert gas which fills the remaining void space 20 under a pressure which is initially in the neighbourhood of atmospheric pressure.

Progressively, as the liquid is dispensed by actuating the pump, the pressure falls in the space 20 without restricting the operation of the pump, a fact which is at first sight surprising because it is contrary to all assumptions.

The effort needed to actuate the pump decreases progressively as the container is emptied.

It is accepted that the efforts due to friction (f) are related to atmospheric pressure (Pa), to the cross-section (S) of the piston, and to the force (R) of the piston return spring by the equation: F < R - Pa.S Experience shows that these results are obtained in favourable conditions with a piston of a diameter between 3 and 10 mm, acted on by a return spring having a force between 0.45 and 5 daN, and that it is possible to utilise in practice the entire capacity of the container.

Progressively, as a depression is created inside the container as a consequence of the dispensing of the liquid there is a partial compensation of the pressure in the free space above the liquid, from the fact of the vapour pressure of the liquid contained.

In a practical example with a pump fitted with a capillary tube of 0.8 mm internal diameter, made of polyethylene or polypropylene, the internal volume of the pump is 11 8 mm3, the useful volume of the pump, that is to say the volume of the quantity of liquid dispensed at each stroke, is 75 mm3, and the internal volume of the passages in the button and the nozzle is 88 mm3.

With a capillary tube having a length of 8 cm, the internal volume of the tube is 20 mm3. The total priming volume is 226 mm3, comprising the volume of the dip tube, the pump and the button. The volume for repriming comprising only the pump and the dip tube is 1 38 mm3. Thus one can theoretically achieve priming of the pump in two or three strokes and re-priming in one or two strokes. In fact the first spray which is obtained does not necessarily correspond to the total useful volume.

Moreover by virtue of the capillarity inside the dip tube the liquid never descends inside the tube to the liquid level outside. For example, with the polypropylene tube having an inside diameter of 0.8 mm the capillarity creates a difference of 9 to 10 mm in the level of the liquid inside and outside the tube.

This difference in level offsets loss of priming and facilitates re-priming of the pump.

With a standard type of dip tube of 3mm inside diameter the loss of priming of the pump takes place very rapidly and re-priming requires at least one extra stroke of the pump for a dip tube length of 8 cm.

In the case of tall containers of a height of 1 6 cm for example, re-priming is always obtained in one or two strokes of the pump with a dip tube according to the invention, of which the internal volume does not exceed 40 mm3, as compared with 112 mm3 in a standard dip tube, such as to need more than two extra strokes of the pump.

Claims (10)

1. A process packaging and dispensing liquids to be dispensed from a hand-held container with a pump comprising trapping the liquid in a rigid closed container under pressure not greater than atomospheric pressure, sealing the container by fitting a singleacting suction-delivery pump without any provision for venting atmospheric air into the interior of the container, and dispensing the liquid by means of the pump with the creation of an increasing depression within the container.

2. A process according to claim 1 in which the pump is furthermore fitted with a feeding dip tube opening into the bottom of the container, the internal volume of this tube being not more than half the useful volume of the pump.

3. A pump-type dispenser for putting into practice the process of claim 1 or 2 comprising a rigid closed container fitted with a single-acting suction-delivery pump, sealed without access to atmosphere and filled at least partially with a liquid under pressure not greater than atmospheric pressure.

4. A dispenser according to claim 3 in which the pump has a piston of a diameter between 3 and 10 mm.

5. A dispenser according to claim 3 or claim 4 in which the piston has a return spring having a force (at rest) of between 0.45 and 5 daN.

6. A dispenser according to any one of claims 3 to 5 in which the degree of initial filling of the container with liquid is at least 70%.

7. A dispenser according to any one of claims 3 to 6 in which the residual space in the container above the liquid is filled with an inert gas of a density at least equal to that of air, the gas being carbon dioxide, nitrogen, a chloro-fluoro hydrocarbon, nitrous oxide, butane or propane.

8. A dispenser according to any one of claims 3 to 7 in which the pump is fitted with a capillary dip tube of which the internal volume is not more than half the useful volume of the pump.

9. A dispenser according to claim 8 in which the capillary tube has an internal diameter less than 1 mm.

10. A hand-held pump-type dispenser substantially as described with reference to the accompanying drawings.