Aerosol dispenser assembly having VOC-free propellant and dispensing mechanism therefor

Abstract

An aerosol dispenser assembly is disclosed that includes a container holding a liquid product and a compressed gas propellant for propelling the liquid product from the container. A design methodology for the actuator body and swirl nozzle insert is disclosed for maintaining a small particle size or Sauter Mean Diameter (D[3, 2]) of less than 48 m at a suitable spray rate (1.5-2 g/s), while utilizing a compressed gas VOC-free propellant for an air freshener product. As obtaining reduced particle size to compete with LPG propellants may result in a reduced spray rate, it is anticipated that one or more nozzles may be designed into the actuator body to maintain a suitable spray rate.

Claims

1. An aerosol dispenser system having a volatile organic compound (VOC)-free propellant comprising: an enclosed container accommodating a liquid product under pressure; a valve assembly coupled to and in fluid communication with the container; an actuator body coupled to and in fluid communication with the valve assembly; and at least one swirl nozzle insert coupled to and in fluid communication with the actuator body, the at least one swirl nozzle insert comprising a cylindrical sidewall connected to an end wall, the cylindrical sidewall having a diameter D less than 4,000 m defining an open bottom, the end wall comprising a recess that defines a swirl chamber, the end wall further comprising an outlet orifice connected to the swirl chamber and the end wall further comprising at least one inlet slot extending inward from a junction of the cylindrical sidewall and end wall towards the swirl chamber, the outlet orifice having a diameter d.sub.o and an axial length L.sub.o, the axial length L.sub.o being less than 250 m, the swirl chamber having a diameter D.sub.s, the inlet slot comprising a width d.sub.p, a height L.sub.s, and a cross-sectional area d.sub.pL.sub.s defined by said width d.sub.p and height L.sub.s, a number of inlet slots N ranging from 1 to 6, d.sub.o, D.sub.s and a cumulative cross-sectional area of the N slots, d.sub.pL.sub.sN, being used to achieve a Sauter Mean Diameter D[3,2] of particles exiting the outlet orifice below a predetermined upper limit when the aerosol dispensing system is charged with an aqueous product.

2. The aerosol dispenser of claim 1 wherein the at least one swirl nozzle insert comprises from 2 to 4 swirl nozzle inserts having a cumulative output rate of at least 1.5 g/s.

3. The aerosol dispenser of claim 1 wherein d.sub.o is less than about 330 m.

4. The aerosol dispenser of claim 1 wherein D.sub.s is at least about 1100 m.

5. The aerosol dispenser of claim 1 wherein the cumulative cross-sectional area of the N slots, d.sub.pL.sub.sN, is less than about 170,000 m.sup.2.

6. The aerosol dispenser of claim 1 wherein the liquid is under an initial pressure from about 60 to about 140 psig.

7. An aerosol dispenser system having a volatile organic compound (VOC)-free propellant comprising: an enclosed container accommodating a liquid product under pressure; a valve assembly coupled to and in fluid communication with the container; an actuator body coupled to and in fluid communication with the valve assembly; and at least two swirl nozzle inserts coupled to and in fluid communication with the actuator body, the at least two swirl nozzle inserts comprising a cylindrical sidewall connected to an end wall, the cylindrical sidewall having a diameter D less than 4,000 m defining an open bottom, the end wall comprising a recess that defines a swirl chamber, the end wall further comprising an outlet orifice connected to the swirl chamber and the end wall further comprising at least one inlet slot extending inward from a junction of the cylindrical sidewall and end wall towards the swirl chamber, the outlet orifice having a diameter d.sub.o and an axial length L.sub.o, the swirl chamber having a diameter D.sub.s, the inlet slot comprising a width d.sub.p, a height L.sub.s, and a cross-sectional area d.sub.pL.sub.s defined by said width d.sub.p and height L.sub.s, a number of inlet slots N ranging from 1 to 6, d.sub.o, D.sub.s and a cumulative cross-sectional area of the N slots, d.sub.pL.sub.sN, being used to achieve a Sauter Mean Diameter D[3,2] of particles exiting the outlet orifice below a predetermined upper limit when the aerosol dispensing system is charged with an aqueous product.

8. The aerosol dispenser of claim 7 wherein the at least two swirl nozzle inserts have a cumulative output rate of at least 1.5 g/s.

9. The aerosol dispenser of claim 7 wherein d.sub.o is less than about 230 m.

10. The aerosol dispenser of claim 7 wherein D.sub.s is at least about 1100 m.

11. The aerosol dispenser of claim 7 wherein the cumulative cross-sectional area of the N slots, d.sub.pL.sub.sN, is less than about 170,000 m.sup.2.

12. The aerosol dispenser of claim 7 wherein the liquid is under an initial pressure from about 60 to about 140 psig.

13. The aerosol dispenser of claim 7 wherein the L.sub.o is less than about 250 m.

14. An aerosol dispenser and product assembly having a volatile organic compound (VOC)-free propellant comprising: a nozzle comprising X swirl nozzle inserts and an actuator body wherein X is an integer ranging from 1 to 4, each swirl nozzle insert comprising a cylindrical sidewall connected to an end wall, the cylindrical sidewall defining an open bottom and having an inner diameter D less than 4,000 m, the end wall comprising a recess that defines a swirl chamber having a diameter D.sub.s, the end wall further comprising an outlet orifice having a diameter d.sub.o connected to the swirl chamber and the end wall further comprising at least one inlet slot extending inward from a junction of the cylindrical sidewall and end wall towards the swirl chamber, the inlet slot comprising a width d.sub.p, a height L.sub.s, and a cross-sectional area d.sub.pL.sub.s, a number of inlet slots N ranging from 1 to 6, the at least one inlet slot entering the swirl chamber at an angle with respect to an axis of the outlet orifice, an inner surface of the swirl chamber encircling the outlet orifice and being disposed at an angle .sub.c with respect to the axis of the outlet orifice, the outlet orifice having an axial length L.sub.o, the axial length L.sub.o being less than 250 m, the end wall of the insert comprising an outer trumpet surface having an axial length L.sub.t extending beyond the outlet orifice, the trumpet surface having an angle .sub.t with respect to the axis of the outlet orifice; the actuator body being coupled to and in communication with a valve assembly that is coupled to an in communication with an enclosed container that accommodates under pressure a product that is a liquid at room temperature; and at least one parameter selected from the group consisting of X, d.sub.o, D.sub.s, a cumulative cross-sectional area of the N slots (d.sub.pL.sub.sN), L.sub.s, d.sub.p, , D, .sub.c, L.sub.o, L.sub.t, .sub.t, and N being used to achieve a Sauter Mean Diameter D[3,2] of particles exiting the outlet orifice below a predetermined upper limit.

15. The aerosol dispenser of claim 14 wherein the X swirl nozzle inserts have a cumulative output rate of at least 1.5 g/s.

16. The aerosol dispenser of claim 14 wherein d.sub.o is less than about 330 m.

17. The aerosol dispenser of claim 14 wherein D.sub.s is at least about 800 m.

18. The aerosol dispenser of claim 14 wherein the cumulative cross-sectional area of the N slots, d.sub.pL.sub.sN, is less than about 170,000 m.sup.2.

19. The aerosol dispenser of claim 14 wherein the liquid is under an initial pressure from about 60 to about 140 psig.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) For a more complete understanding of the disclosed methods and apparatuses, reference should be made to the embodiment illustrated in greater detail on the accompanying drawings, wherein:

(2) FIG. 1 is a partial cross-sectional perspective view of an aerosol dispenser assembly made in accordance with this disclosure.

(3) FIG. 2A is a front elevational view of an actuator body made in accordance with this disclosure.

(4) FIG. 2B is a front elevational view of another actuator body made in accordance with this disclosure.

(5) FIG. 2C is a front elevational view of yet another actuator body made in accordance with this disclosure.

(6) FIG. 2D is a front elevational view of still another actuator body made in accordance with this disclosure.

(7) FIG. 3A is a side elevational view of the actuator body shown in FIG. 2A.

(8) FIG. 3B is a side elevational view of the actuator body shown in FIG. 2D.

(9) FIG. 4 is a rear elevational view of the actuator body's shown in FIGS. 2A-3B.

(10) FIG. 5A side sectional view of an insert suitable for use with the actuator bodies of FIGS. 2A-3B.

(11) FIG. 5B is a perspective view of the insert shown in FIG. 5A.

(12) FIG. 6A is a rear plan view of the insert shown in FIG. 5, particularly illustrating one configuration with four inlet slots.

(13) FIG. 6B is a rear plan view of the insert shown in FIGS. 5A-5B, particularly illustrating configurations with two and three inlet slots.

(14) FIG. 7A is a chart with data points for various design parameters used in the disclosed methodology in the design of metal swirl nozzle inserts.

(15) FIG. 7B is a chart with data points for various design parameters used in the disclosed methodology in the design of plastic swirl nozzle inserts.

(16) It should be understood that the drawings are not to scale and that the disclosed embodiments are sometimes illustrated diagrammatically and in partial views. In certain instances, details which are not necessary for an understanding of the disclosed methods and apparatuses or which render other details difficult to perceive may have been omitted. It should be understood, of course, that this disclosure is not limited to the particular embodiments illustrated herein.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS

(17) As shown in FIG. 1, an aerosol dispenser assembly 10 includes a container 11 covered by a mounting cup 12. A mounting gasket (not shown) may be disposed between an upper rim of the container 11 and the underside of the mounting cup 12. A valve assembly 13 is used to selectively release the contents from the container 11 to the atmosphere. The valve assembly 13 comprises a valve body 14 and a valve stem 15. The valve stem 15 includes a lower end 16 that extends through a return spring 17. An actuator body 18 is mounted on top of the valve stem 15 and defines a primary passageway 19. The actuator body 18 is also connected to one or more nozzle inserts 21 that each define an exit orifice shown generally at 22 and which will be discussed in greater detail below.

(18) An upper rim 23 of the valve body 14 is affixed to the underside of the mounting cup 12 by a friction fit and the valve stem 15 extends through the friction cup 12. The actuator body 18 is frictionally fitted onto the upwardly extending portion 24 of the valve stem 15. The lower end 25 of the valve body 14 is connected to a dip tube 26. Gaskets may or may not be required between the valve body 14 and the mounting cup 12 and between the valve stem 15 and the mounting cup 12, depending upon the materials used for each component. Suitable materials will be apparent to those skilled in the art that will permit a gasket-less construction. Similarly, gaskets or seals are typically not required between the actuator body 18 and the upper portion 24 of the valve stem 15.

(19) While the dispenser assembly 10 of FIG. 1 employs a vertical action-type actuator body or cap 18, it will be understood that other actuator cap designs may be used such as an actuator button with an integral over cap, a trigger actuated assembly, a tilt action-type actuator cap or other designs.

(20) In operation, when the actuator body 18 is depressed, it forces the valve stem 15 to move downward thereby allowing pressurized liquid product to be propelled upward through the dip tube 26 and the lower portion 25 of the valve body 14 by the propellant. From the valve body 14, the product is propelled past the lower end 16 of the valve stem 14 through the channel 30 and through the stem orifice(s) 27, out the passageway 28 of the valve stem and into the primary passageway 19 of the actuator body 18. Preferably, two valve stem orifices 27 are employed as shown in FIG. 1 although a single valve stem orifice 27 or up to four valve stem orifices 27 may be used. Multiple valve stem orifices 27 provide greater flow and superior mixing of the product.

(21) The use of the inserts 21 and posts 29 within the actuator body 18 is illustrated in greater detail FIGS. 2A-6B below. Turning to FIGS. 2A-2B, front elevational views of four different actuator bodies 18a-18d are shown. Each actuator body 18a-18d includes a different number of secondary passageways and nozzles (i.e. nozzle chamber, post and swirl nozzle insert). The number of secondary passageways and nozzles will depend upon the desired spray rate and the effective spray rate of each nozzle. Generally speaking, when compressed gas propellant is used, lower particle sizes result in the lower spray rates. Thus, the four nozzle design of FIG. 2C is effective for boosting the spray rate for formulations where is difficult to reduce the particle size (thereby resulting in reduced spray rate per nozzle) while the design of FIG. 2D will be effective for formulations where particle size is not problematic and therefore the spray rate per nozzle is relatively high.

(22) In FIG. 2A, the actuator body 18a includes a primary passageway 19a that is connected to three different secondary passageways 31a-33a. In FIG. 2B, the primary passageway 19b of the actuator body 18b is connected to two secondary passageways 31b-32b. In FIG. 2C, the actuator body 18c includes a primary passageway 19c that is connected to four different secondary passageways 31c-34c while, in FIG. 2D, the primary passageway 19d may be directly connected to the nozzle chamber 37d. Again, the number of secondary passageways and nozzles may differ depending upon the particle size (Sauter Mean Diameter or D[3,2]) desired and the desired spray rate.

(23) The actuator body 18a of FIG. 2A includes three nozzle chambers 37a, 38a, 39a; the actuator body 18b of FIG. 2B includes two nozzle chambers 37b, 38b; the actuator body 18c of FIG. 2C includes four nozzle chambers 37c-40c; and the actuator body 18d of FIG. 2D includes a single nozzle chamber 37d. An inlet slot can be considered to be the transition between each secondary passage 31-34 and its respective nozzle chamber 37-40. Inlet slots are shown at 42a-44a, 42b-43b, 42c-45c and at 42d in FIGS. 2A-2D respectively. Essentially, a nozzle chamber 37a-39a, 37b-38b, 37c-40c, or 37d is the space disposed in the actuator body 18a-18d below the recessed outer surface 36a-36d and above the secondary passages 31a-33a, 31b-32b, 31c-34c or 31d. More specifically, the nozzle chamber 37a-39a, 37b-38b, 37c-40c, or 37d is the space disposed between the inlet slots 42a-44a, 42b-43b, 42c-45c or 42c and the recessed outer surface 36a-36d of the actuator body 18a-18d. Each nozzle chamber 37a-39a, 37b-38b, 37c-40c or 37d accommodates a post 47a-49a, 47b-48b, 47c-50c or 47d which receives one of the swirl nozzle inserts 21.

(24) Turning to FIG. 3A, a left side view of the actuator body 18a of FIG. 2A is shown. The connection between the primary passage 19a and the secondary passages 33a and 32a are shown as the secondary passage 31a (see FIG. 2A) is hidden from view in FIG. 3A. FIG. 3B illustrates the nozzle chamber 37d of the actuator body 18d and the matable engagement of the insert 21 over the post 47d. The construction of the insert 21 will be discussed in greater detail below connection with FIGS. 5-6B. Between the inlet slot 42d, the post 47d and the insert 21 is an additional longitudinal slot 52 that may be formed in the insert 21, the post 47d or combination of the two. The slot 52 provides communication between the primary passage 19d, the secondary passage 31d, the inlet slot 42d (which may simply be a portion of or an extension of the secondary passage 31d) and the underside of the insert 21 which, in combination with the post 47d forms the swirl chamber 53.

(25) FIG. 4 is a rear elevational view of one embodiment of an actuator body 18. An upper surface 54 may be provided with a plurality of transverse ridges or slots 55 for serving as a finger grip. As noted above, in addition to the disclosed button-type actuator 18, additional types of actuators can be employed such as an actuator button with an integral overcap, a trigger-actuated assembly or the like.

(26) Additional detail regarding the swirl nozzle inserts 21 is provided in FIGS. 5A-6B. Turning first FIGS. 5A and 5B, each insert 21 includes a cylindrical sidewall 61 connected to an end wall 62. An outer surface 63 of the sidewall 61 may include a lip or rim 63 for purposes of frictionally engaging the inner sidewalls of a nozzle chamber 37-40. The inserts 21 snap into place with a secure friction fit. As high pressures approaching 200 psig may be employed, a tight fit between the insert 21 and actuator body 18 is required. A longitudinal slot 52 is shown in phantom in FIG. 5A and, again, communication from the secondary passage 31-34 to the end wall 62 of the insert 21 may be provided by a slot 52 disposed in the insert 21 or a longitudinal slot disposed in the post 47-50 or a combination of the two. Other alternatives will be apparent to those skilled in the art.

(27) As discussed in greater detail in FIGS. 6A-6B, FIG. 5A nevertheless shows an inlet slot 64 in phantom lines. A better view of the inlet slots 64 is shown in FIG. 5B. The angular relationship between each inlet slot 64 and the axis 65 of the exit orifice 22 is best shown in FIG. 5B as the angle . In both FIGS. 5A and 5B, the angle is 90. While angles of greater than or less than 90 are not specifically shown in the drawings, such alternative angles are possible and considered within the scope of this disclosure.

(28) The end wall 62 of the insert 21 includes a plurality of recesses as best seen in FIGS. 6A-6B. Turning to FIG. 6A, the end wall 62 includes a central recess 53 that serves as a swirl chamber that surrounds the exit orifice 22. The swirl chamber 53 is in fluid communication with one or more inlet slots 64. As seen in FIGS. 6A and 6B, the number of inlet slots can vary. FIG. 6A illustrates an embodiment with four slots 64; FIG. 6B schematically illustrates a two slot configuration (see the slots labeled 64a) as well as a three slot configuration (see the slot on the left labeled 64a and the slots labeled 64b). A single inlet slot 64 embodiment is also envisioned as well as five and six inlet slot 64 configurations even though only 2, 3 and 4 slots configurations are specifically illustrated in FIGS. 6A-6B. The inlet slots 64 feed fluid flowing through one of the secondary passages 31-34, into one of the actuator body inlet slots 42-45 and past the posts 47-50 to the swirl chamber 53. Centralized within the swirl chamber 53 is the outlet orifice 22.

(29) The design dimensions and parameters of the insert 21 will now be described. The nomenclature for the design parameters discussed herein is consistent with the article by Xue et al., Effect of Geometric Parameters on Simplex Atomizer Performance, AIAA Journal, Vol. 42, No. 12 (December 2004), which is incorporated herein by reference. The design parameters discussed herein are directed toward typical commercial aerosol canned products utilizing a compressed gas propellant (VOC-free) provided at a pressure ranging from about 60 to about 140 psig, a target discharge or spray rate of 1.5-2 g/s and a formula that comprises primarily water, less than 7 wt % ethanol and about 0.3 wt % fragrance oil. The target Sauter Mean Diameter D[3,2] is less than 50 m.

(30) Referring back to FIG. 5A, the diameter D.sub.s of the swirl chamber 53 is the transverse internal diameter of the recess that forms the swirl chamber 53. Without being bound by any particular theory, it has generally been determined that a larger swirl chamber is useful for the typical aerosol air fragrance product using a compressed gas propellant as discussed above. In an embodiment, the swirl chamber diameter D.sub.s is preferably greater than 1100 m, although that value may vary depending upon the other parameters discussed herein.

(31) The exit orifice diameter d.sub.o is the internal diameter of the exit orifice 22. In an embodiment, the exit orifice diameter d.sub.o is less than about 210 m although the exit orifice diameter d.sub.o may approach 300 m, depending upon the values for the other design parameters. For example, (D[3,2]) values of 52.6 m have been achieved with an exit orifice diameter d.sub.o of 300 m and with a swirl chamber diameter D.sub.s of 1,776 m. Thus it is envisioned that a large orifice diameter d.sub.o of about 300 m employed with a larger swirl chamber diameter D.sub.s may provide the desired low particle size.

(32) Other parameters include the dimensions of the inlet slots 64 including the slot width d.sub.p, slot height L.sub.s, and number N of inlet slots 64. One particularly useful parameter is the cumulative cross-sectional slot 64 area, d.sub.pL.sub.sN. As too high of a cross-sectional area for these inlet slots 64 would reduce the flow rate into the swirl chamber 53, in an embodiment, the cumulative cross-sectional area of the inlet slots 64 (d.sub.pL.sub.sN) is preferably less than about 30,625 m.sup.2.

(33) Other important parameters for maintaining a Sauter Mean Diameter D[3,2] of less than 48 m at a spray rate of 1.5-2 g/s include, but are not limited to: the inner diameter D of the insert 21 (see FIG. 5A); the angle at which the inlet slot(s) 64 enter the swirl with respect to the axis 65 of the outlet orifice 22; and the angle .sub.c which is the angle between the inner or bottom surface of the swirl chamber 53 encircling the outlet orifice 22 and the axis 65 of the outlet orifice 22; the axial length L.sub.o of the outlet orifice 22; the axial length L.sub.t of the outer trumpet surface 66 of the end wall 62 of the insert 21 that extends beyond the outlet orifice 22; and the angle .sub.t of trumpet surface 66 with respect to the axis 65 of the outlet orifice 22. Any one or more of these parameters may be used to achieve the desired particle size (D[3,2]<50 m) at the desired spray rate (1.5-2 g/s).

(34) Data for all of the above-referenced parameters is presented in FIG. 7A for metal inserts 21 and FIG. 7B for plastic inserts 21. L.sub.s, d.sub.p, D, D.sub.s, L.sub.o, d.sub.o and L.sub.t are in micrometers; , .sub.c, .sub.t are in degrees (), PSIG is the internal container pressure (in psig), spray rate is in g/s and RSF is the relative diameter span factor which characterizes the particle diameter span or range with respect to the median diameter. The relative diameter span factor RSF is calculated from the formula: RSF=D.sub.0.9D.sub.0.1/D.sub.0.5 where D.sub.0.9 is the 90th percentile diameter from a diameter distribution curve, D.sub.0.1 is the 10th percentile diameter from the diameter distribution curve, and D.sub.0.5 is the median diameter from the diameter distribution curve. See, Bayvel be & Orzechowski, Liquid Atomization, p. 156-58 (1993).

(35) While only certain embodiments have been set forth, alternatives and modifications will be apparent from the above description to those skilled in the art. These and other alternatives are considered equivalents and within the spirit and scope of this disclosure and the appended claims.

INDUSTRIAL APPLICABILITY

(36) An improved aerosol dispenser is provided using a compressed gas propellant free of volatile organic compounds and that includes an actuator cap/swirl nozzle insert combination for providing a reduced particle size at the desired spray rates.