Fluid sprinkling – spraying – and diffusing – Including supply holder for material – Fluid pressure discharge means
Reexamination Certificate
2003-01-24
2004-11-30
Doerller, William (Department: 3744)
Fluid sprinkling, spraying, and diffusing
Including supply holder for material
Fluid pressure discharge means
C239S354000
Reexamination Certificate
active
06824079
ABSTRACT:
FIELD OF THE INVENTION
The instant invention relates to an improved aerosol dispenser assembly that dispenses a liquid product as a fine spray having a reduced particle size, while reducing the amount of propellant required to dispense the liquid product from the container.
BACKGROUND OF THE INVENTION
Aerosol dispensers have been commonly used to dispense personal, household, industrial, and medical products, and to provide a low cost, easy to use method of dispensing a liquid product. Typically, aerosol dispensers include a container, which contains a liquid product to be dispensed, such as soap, insecticide, deodorant, disinfectant, or the like. A propellant is used to discharge the liquid product from the container. The propellant is under pressure and provides a force to expel the liquid product from the container when a user actuates the aerosol dispenser by, for example, pressing an actuator button.
The two main types of propellants used in aerosol dispensers today are liquefied gas propellants, such as hydrocarbon and hydrofluorocarbon (HFC) propellants, and compressed gas propellants, such as compressed carbon dioxide or nitrogen gas. To a lesser extent, chlorofluorocarbon propellants (CFCs) are also used. The use of CFCs is, however, being phased out due to the harmful effects of CFCs on the environment.
In an aerosol dispenser using the liquefied gas-type propellant (also known as a double phase propellant), the container is loaded with the liquid product and propellant, and pressurized to a pressure approximately equal to, or slightly greater than, the vapor pressure of the propellant. Since the container is pressurized to the vapor pressure of the propellant, a majority of the propellant is liquefied. However, a small portion of the propellant will remain in gaseous form. As the product is dispensed, the pressure within the container will decrease and more of the propellant will enter the gas phase. In a compressed gas aerosol dispenser, the propellant remains in gaseous form when the container is pressurized for use.
A conventional aerosol dispenser generally comprises a container (not shown) for holding a liquid product and a propellant, and a valve assembly for selectively dispensing a liquid product from the container. As illustrated in
FIG. 3
, the valve assembly
104
comprises a mounting cup
106
, a mounting gasket
108
, a valve body
10
, a valve stem
112
, a stem gasket
114
, an actuator cap
116
, and a return spring
118
. The valve stem
112
, stem gasket
114
, and return spring
118
are disposed within the valve body
110
and are movable relative to the valve body
110
to selectively control dispensing of the liquid product. The valve body
110
is affixed to the underside of the mounting cup
106
, such that the valve stem
112
extends through, and projects outwardly from, the mounting cup
106
. The actuator cap
116
is fitted onto the outwardly projecting portion of the valve stem
112
and is provided with an actuator orifice
132
. The actuator orifice
132
directs the spray of the liquid product into the desired spray pattern. A dip tube
120
is attached to the lower portion of the valve body
110
to supply the liquid product to the valve assembly
104
to be dispensed. As shown in
FIG. 2
, the whole valve assembly
104
is sealed to a container
102
by mounting gasket
108
.
In operation, when the actuator cap
116
of the dispenser
101
is depressed, the propellant forces the liquid product up the dip tube
120
and into the valve body
110
via a body orifice
122
. In the valve body
110
, the liquid product is mixed with additional propellant supplied to the valve body
110
through a vapor tap
124
. The vapor tap
124
helps to mix the liquid product and propellant in the valve body
110
, to thereby break up the product into smaller particles suitable to be dispensed. From the valve body
110
, the product is propelled through a stem orifice
126
, out the valve stem
112
, and through an actuator orifice
132
formed in the actuator cap
116
.
S. C. Johnson & Son, Inc. (S. C. Johnson) employs an aerosol valve similar to that shown in
FIG. 3
in connection with their line of Glade® aerosol air fresheners. The propellant used to propel the air freshener liquid product from the container is a B-Series propellant having a propellant pressure of 40 psig (B-40), at 70° F. (2.722 atm at 294.261 K). “Propellant pressure” refers to the approximate vapor pressure of the propellant, as opposed to “can pressure,” which refers to the initial gauge pressure contained within a full aerosol container. The B-40 propellant is a composition of propane, normal butane, and isobutane. By normal butane it is meant the composition denoted by the chemical formula C4H10, having a linear backbone of carbon. In order to effectively dispense this air freshener composition, the aerosol dispenser used by S. C. Johnson in connection with their line of Glade® aerosol air fresheners has a stem orifice diameter of 0.025″ (0.635 mm), a vapor tap diameter of 0.020″ (0.508 mm), a body orifice diameter of 0.062″ (1.575 mm), and a dip tube inner diameter of 0.060″ (1.524 mm). This current Glade® aerosol air freshener requires that the B-40 propellant be present in the amount of approximately 29.5% by weight of the contents of the dispenser assembly.
Hydrocarbon propellants contain Volatile Organic Compounds (VOCs). The content of VOCs in aerosol air fresheners is regulated by various federal and state regulatory agencies, such as the Environmental Protection Agency (EPA) and California Air Resource Board (CARB). S. C. Johnson continuously strives to provide environmentally friendly products and regularly produces products that exceed government regulatory standards. It is in this context that S. C. Johnson set out to reduce the content of VOCs in their line of Glade® aerosol air fresheners.
One way in which to reduce the VOC content in such aerosol air fresheners is to reduce the content of the hydrocarbon propellant used to dispense the liquid product. However, we have discovered that a reduction in the propellant content adversely affects the product performance. Specifically, reducing the propellant content in the aerosol air freshener resulted in excessive product remaining in the container at the end of the life of the dispenser assembly (product retention) and an increase in the size of particles of the dispensed product (increased particle size). It is desirable to minimize the particle size of a dispensed product in order to maximize the dispersion of the particles in the air and to prevent the particles from “raining” or “falling out” of the air. Thus, we set out to develop an aerosol dispenser assembly that can satisfactorily dispense an aerosol product that contains, at most, 25% by weight, of a double phase hydrocarbon propellant, while actually improving product performance throughout the life of the dispenser assembly.
The “life of the dispenser assembly” is defined in terms of the pressure within the container (i.e., the can pressure), such that the life of the dispenser assembly is the period between when the pressure in the container is at its maximum and when the pressure within the container is substantially depleted, i.e., equal to atmospheric pressure.
One known method of reducing the particle size of a dispensed liquid product is disclosed in U.S. Pat. No. 3,583,642 to Crowell et al. (the '642 patent), which is incorporated herein by reference. The '642 patent discloses a spray head that incorporates a “breakup bar” for inducing turbulence in a product/propellant mixture prior to the mixture being discharged from the spray head. Such turbulence contributes to reducing the size of the mixture particles discharged from the spray head.
SUMMARY OF THE INVENTION
Our invention provides an improved aerosol dispenser assembly that dispenses substantially all of a liquid product (i.e., reduces product retention) as a fine spray having reduced particle size, while at the same time reducing the amount of propellan
Kendrick Robert E.
Manderfield Cary E.
Moe Kevin J.
Samuelson Leon C.
Ali Mohammad
Doerller William
S. C. Johnson & Son Inc.
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