Dispensing – Automatic control – Constant weight – volume or pressure control by output
Patent
1982-04-05
1984-12-11
Marmor, Charles A.
Dispensing
Automatic control
Constant weight, volume or pressure control by output
222 61, 222394, 222396, B67D 534
Patent
active
044873344
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to thrust control means, for use in the interior of a container under gas pressure, by means of which the amount, per unit of time, of product dischargeable from the container can be maintained at least approximately constant during the entire discharge time in spite of the internal pressure decreasing as the container is increasingly emptied.
The prohibition of aerosol cans which use chlorofluorinated hydrocarbons as propellant is, in various countries, the answer to the danger which these gases present to the protective ozone layer which encloses the Earth.
Practically half the number of sold spray cans has always been filled with a mixture of propane and butane gas which are no danger for the ozone layer as they are previously decomposed. However, as this propellant gas mixture is extremely combustible and explosive, at least 55% of the content of the spray can must be non-combustible due to the use of water, trichloroethane or methylene chloride.
In many countries, trichloroethane and methylene chloride are permitted for cosmetic products only in an amount of up to 35% of the product, and, as they can lead to a dangerous hydrolysis with water, the missing 20% of the non-combustible share cannot consist of water. To use only water as the non-combustible share would substantially decrease the quality of the cosmetic product, quite apart from the fact that water and propane/butane must be mixed by means of an emulsifier to form an emulsion, which requires shaking of the spray can before each use. In order to avoid that, after discharge of the non-inflammable portion, there remains in the spray can a pure, highly dangerous propellant gas mixture, but also, in order for the discharged aqueous product to contain a sufficiently large amount of propellant gas which, at detensioning in air, will disperse the water as fine droplets, whereby a sufficiently rapid vaporization is attained. As, however, the emulsifiers mostly contain oils and waxes, the expelled aqueous product has a smudgy character. It is therefore practically impossible to sell a water-based hair lacquer in countries such as Japan, England, Sweden etc., which have a humid climate, because the water-soluble resins of the hair lacquer cannot preserve the hairdo in humid weather.
One has tried to use carbon dioxide, nitrogen or laughing gas, or simply compressed air as propellant. However, in order to achieve an atomization quality which is acceptable up to complete emptying, and a constant discharge volume per second, new agents must be found, for these inert gases show a pressure drop which is directly proportional to the increasing empty volume of a spray can by the discharge of the product contents, which, however, does not permit maintaining constant the atomization quality of a conventional atomizer; it will become continuously worse during emptying, apart from the fact that the product discharge volume per unit of times becomes continuously smaller.
The applicant of the instant invention has developed a spray nozzle which has been described in the German Offenlegungsschrift No. 28 26 784 of Feb. 15th, 1979 under the designation of "Spray nozzle and device containing a spray nozzle and processes for their manufacture". Thanks to this spray nozzle it is possible to attain a good atomization quality with substantially lower pressure values than have been hitherto conventional, which means that the initial pressure of the spray can filled with inert gases, may lie at about 6 bar instead of 10 bar, because the above-mentioned spray nozzle releases an acceptable spray quality even at a terminal pressure of about 2 bar, especially, if the product involves an ethanol-methylene chloride mixture. If a higher initial pressure, for instance of 10.5 bar, is used, then the spray nozzle ejects a spray cloud of the finest particle size.
The above-mentioned spray nozzle can solve the problem of atomization from spray cans with inert gases as propellant only partially inasmuch as it has no influence at all on the unavoidable decre
Herzfeld Heinrich W.
Marmor Charles A.
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