US 3896602 A
A method of manufacturing a low cost barrier package, wherein a controlled release coating is formed-in-place in such a manner as to be free of air entrapment, and is caused to peel therefrom to form a barrier between the product and propellant; the method also including control of deformation and permeability of the barrier.
Claims available in
Description (OCR text may contain errors)
I United States Patent 91 [1 3,896,602 Petterson July 29, 1975  METHOD OF MANUFACTURING OF A Everett ruee et a. BARRIER PACKAGE 3,415,425 12/1968 Knight et al. 222/386.5  inventor: Tor l-l. Petterson, 31248 Palos 3,471,349 10/1969 Cohen et a1. 117/97 Verdes Dr. West, Palos Verdes Peninsula, Calif. 90274 22 d: A 1 1973 Primary Examiner-Richard J. Herbst 1 1e Attorney, Agent, or Firm-Lyon & Lyon  Appl. No.: 384,738
Related U.S. Application Data  Continuation-in-part 0t Ser. No. 180,790, Sept. 15,
1971, abandoned.  ABSTRACT  U.S. Cl. 53/36; 29/458; 113/120 A; A method of manufacturing a low cost barrier pack- 53/43 age, wherein a controlled release coating is formed-in-  Int. Cl 1365b 31/00 place in such a manner as to be free of air entrapment,  Field of Search 113/120 A; 222/3865, 389; and is caused to peel therefrom to form a barrier be- 1 17/6, 97; 29/460, 458; 53/36, 43 tween the product and propellant; the method also including control of deformation and permeability of the  References Cited barrier.
UNITED STATES PATENTS 8/1958 Switzer ll3/120A 10 Claims, 23 Drawing Figures PATENTED JUL 2 9 975 JHLU Fill level in percent Full Fill level in percent Empty Fig.20
Empty SHEET 4 TENSILE/SHEAR STRENGTH REQUIRED DURING FILLING Tensile/shear strenth in ounces ---------r- Integral controlled release coating Unsupported bag (a) propellant injection point TENSILE/SHEAR STRENGTH REQUIRED AT VARIOUS FILL LEVELS UNDER DROP TEST CONDITIONS Tensile/shear strength in ounces --Integra1 controlled release coating Unsupported bag PATENTEUJULZSISYS 3,896,602
SHEET PERMEABILITY POTENTIAL OF A PACKAGE STORED FOR 21 MONTHS I 3 27 I D 24 I I Actuation-o 21 ..-L
15 E V g 12 w I 0. 9 l E? 2g 6 s g UJn-l 3 2O 4O 6O 80 100 Permeability potential R D ---Integral controlled release coating Unsupported bag syste s BARRIER AREA EXPOSED TO PRODUCT AND PROPELLANT DURING PRODUCT LIFE Full Propellant Inj ection ----p Filling Discharge Discharg Fill level Empty 2O 4O 6O Barrier area in percent exposed to both product and propellant---------) --Integral controlled release coating Unsupported bag or bellows system METHOD OF MANUFACTURING OF A BARRIER PACKAGE This application is a continuation-in-part of patent application Ser. No. 180,790 filed Sept. 15, 1971 and entitled: PRODUCT ISOLATED AEROSOL CON- TAINER AND METHOD OF MANUFACTURE, and is directed to the method of manufacture, now abancloned.
BACKGROUND OF THE INVENTION The well known aerosol dispensing package has achieved wide acceptance and success. At present, a great number of products are distributed in aerosol packages, many of the products being heretofore deemed unsuitable for aerosol dispensing. To name a few, paints, insecticides, beauty aids, powders, food products, window cleaners, etc., have all undergone revolutionary packaging changes and are now dispensed in aerosol packages. In a conventional aerosol dispensing package, a rigid tubular member, usually of metal, is partially filled with the product to be dispensed and a dispensing valve is attached to the open end of the package. Thereafter, a suitable propellant in the form of a gas is introduced into the package which exerts a force against the product tending to urge the product out of the package through the dispensing valve. Upon actuation of the dispensing valve, the force exerted by the propellant will urge the product from the aerosol package in the form of a fine mist or spray.
Since the foregoing described aerosol packages have achieved great acceptance in the consumer market and enjoys a high degree of success, increasing effort has been directed to the fabrication of packages of this type. In the matter of economics, the success of the item is diminished or even erradicated if the cost of the dispensing package is out of proportion to the cost of the product to be dispensed. That is to say, the convenience of an aerosol package may be overridden by economic considerations when, for example, a twentycent package is employed to dispense five cents worth of material.
Aerosol packages take many and varied forms and a primary consideratior is the possible reaction between the propellant and the product to be dispensed. In many cases relating to the dispensing of non-edible products, the selection of the propellant receives little attention. However, in the packaging of volatile products, highly reactive products, edible products, etc., much attention may be directed to the selection of the propellant since reactions between the propellant and the product may oftentimes occur. This reaction results in contamination and degradation of the product and as such, is, of course, highly undesirable and to be avoided.
Accordingly, the need has arisen for a barrier package which will maintain the propellant separated from the product and a surrounding, usually rigid, container body.
One approach is by use of a piston. This has not proved satisfactory because of the possibility, during handling, of the package becoming dented. Another approach involves the use of an elastic inner container forming a barrier between the product and the pressure fluid. Two examples of this approach are U.S. Pat. Nos. 3,393,842 and 2,953,304, both of which utilize a product filled bag the rim of which is clamped between metal parts of the package. Difficulty has been encountered in insuring a complete seal as the bag may be cut during assembly.
The other examples are US, Pat. Nos. 3,189,231 and 3,415,425, in which the product is contained in the package above an initially compacted and folded expansible barrier containing the pressure fluid. The first of these patents indicates the need of a piston as well as the barrier, with attendant increase in package size. Another example is U.S. Pat. NO. 3,549,058 wherein the metal package receives a liner having corrugated walls and a neck portion which fits into the neck of the package. While a rather complete liner is provided, difficulty is encountered in assembly as the liner neck sometimes slips into the package when the dispensing valve closure is secured. Examples of other barrier packages include U.S. Pat. Nos. 3,145,884, 3,393,842 and 3,54l,58l.
To date, barrier packages have had but limited commercial success which can be attributed at least in part to the difficulties in manufacturing, evidenced by high package failure rates and excessive package costs.
One difficult problem inherent in barrier dispensers involves premature closure of the outlet valveby the barrier so as to prevent full evacuation of the product, that is, a portion of the barrier may be forced over the outlet opening before all of the product has been discharged so that the remaining portion of the product is entrapped.
A second problem inherent in barrier dispensers involves permeability of the barrier. The nature of the barrier materials used, the propellants used, and the products to be dispensed require extensive efforts to avoid or reduce permeability. In addition, many of these products are required to have shelf lives in excess of 24 months.
A third problem inherent in barrier dispensers involves the integrity of the barrier under various condi tions including; filling and drop testing.
SUMMARY OF THE INVENTION The present invention and a companion application Ser. No. 180,790, Filed Sept. 15, 1971, entitled PROD- UCT ISOLATED AEROSOL CONTAINER AND METHOD OF MANUFACTURE are'directed to a barrier package and method of manufacture which solves the problems inherent in previous packages of this type and which may be manufactured at minimum cost while also minimizing the production of defective packages. The invention is summarized in the following objects:
First, to provide a barrier package and method of manufacture wherein appropriate walls of the package receive a formed-in-place controlled release coating, portions of which release from the inner surface of the package to form a barrier between the propellant and the product to be dispensed.
Second, to provide a product and method as indicated in the preceding object, wherein the coating may be applied by various coating application techniques such as pouring the coating material into the package, then draining excess material, or by spraying the material into the package, or by blow-molding the material until limited by the walls of the package.
Third, to provide a barrier package which may be so arranged that the controlled release coating or selected portions thereof may adhere with a predetermined force to the surface of the package, thereby necessitating application of a predetermined tension on the coating in order to release additional coating having controlled deformation to insure that the dispensing means does not become prematurely clogged by the released coating.
Fourth, to provide a barrier package and controlled release coating, with controlled deformation to insure continued communication between the product and the dispensing valve until the maximum quantity of the product has been dispensed.
Fifth, to provide a barrier package whose cost of manufacture is essentially no greater than conventional non-barrier pressure packages adaptable to mass production techniques.
Sixth, to provide unique and improved concepts in barrier package construction and to the structural incorporation of novel principles contributing to the unique function of the container components.
Seventh, to provide a barrier package that can be produced on manufacturing equipment presently in use and to utilize standard readily available components and raw materials.
Eighth, to provide a barrier package at an extremely low manufacturing cost, thereby making it practical to package many products that heretofore have not been available in pressurized packages.
Ninth, to provide a barrier package, at a low manufacturing cost, with controlled permeability to insure maximum barrier properties over the life of the product.
DESCRIPTION OF THE DRAWING FIG. 1 is a side view with a portion in section showing one embodiment of the barrier package.
FIG. 2 is an enlarged fragmentary sectional view taken within circle 2 of FIG. 1.
FIG. 3 is another enlarged fragmentary sectional view taken within circle 3 of FIG. 1.
FIG. 4 is an enlarged fragmentary sectional view similar to FIG. 3 showing a modified construction.
FIG. 5 is an enlarged fragmentary sectional view taken within 55 of FIG. 1.
FIG. 6 is a side view showing another embodiment of the barrier package.
FIG. 7 is an enlarged fragmentary sectional view taken within circle 7 of FIG. 6 showing the package in its initial condition.
FIG. 8 is a similar enlarged fragmentary sectional view showing the package in its depleted condition.
FIG. 9 is a side view of a further embodiment of the barrier package.
FIG. 10 is an enlarged transverse sectional view taken through 10-10 of FIG. 9.
FIG. 11 is an enlarged fragmentary transverse sectional view taken through 11-ll of FIG. 9 showing the condition when the package is depleted.
FIG. 12 is a fragmentary view partially in section of a further embodiment of the barrier package as it appears when prepared for application of a controlled release coating.
FIG. 13 is a fragmentary side view partially in section of the embodiment shown in FIG. 12 as it appears in condition for dispensing a product.
FIG. 14 is an essentially diagrammatical side view of the package in the course of receiving a liquid coating material.
FIG. 15 is a similar side view showing a package in the course of receiving a spray supplied coating.
FIG. 16 is a similar view of a package in the course of receiving an internal coating applied by a blowmolding technique.
FIG. 17 is an enlarged fragmentary sectional view taken through 17-17 of FIG. 16.
FIG. 18 is an enlarged fragmentary plan view taken from l8-18 of FIG. l6.-
FIG. 19 is a fragmentary elevational view taken from circle 1919 of FIG. 18.
FIG. 20 is a chart comparing the present invention with the prior art in regard to the tensile/shear strength required during filing.
FIG. 21 is a chart comparing the present invention with the prior art in regard to the tensile/shear strength required at various fill levels under drop test conditions.
FIG. 22 is a chart comparing the present invention with the prior art in regard to the permeability potential of a package stored for 21 months.
FIG. 23 is a chart comparing the present invention. with the prior art in regard to the barrier area exposed to product and propellant during product life.
DESCRIPTION OF THE EMBODIMENTS ILLUSTRATED Reference is first directed to FIGS. 1, 2, 3, and 5 which illustrates one embodiment of the barrier package. A metal container or package 1 is provided having upwardly concave bottom 2, a cylindrical side wall 3, and peripheral top wall 4. The container or package may be formed in a conventional manner by mold forming in a single piece or the bottom and top walls may be separate members and joined to the cylindrical wall in a conventional manner.
The peripheral top wall may receive a conventional closure member 5 join'ed hereto by conventional rolled connection 6. Mounted in the closure member 5 is a dispensing valve 7 which also may be conventional. Examples of such valves are disclosed in the following US. Pat. Nos. 2,615,597; 2,704,172; 2,739,841; 2,877,936; 2,906,449; 3,132,774; 2,678,147; 2,753,214; 2,772,819; 3,247,261; and 2,947,126. Fitted in the bottom wall is a conventional pressure fluid filler valve 8.
In the exercise of the present invention, the inner surfaces of the bottom wall 2, side wall 3 and peripheral top wall 4 receive formed-in-place, controlled release coating 9 which may be formed of a variety of materials. The composition of the material may vary substantially depending upon the product to be dispensed.
The package is filled with the product to be dispensed to a predetermined level. Thereupon the closure member 5 is secured to the top wall 4. Preferably a portion of the coating at least partially covers the top wall which receives the closure member 5 so as to be clamped therebetween within the rolled connections 6 and insure a good seal. After this is accomplished, a pressure fluid is injected through the filler valve 8. As
indicated previously, the filler valve may be conventional. The filler valve may be provided with a slit which may be opened by insertion of a small filler tube. After the container 1 is pressurized, the filler tube is withdrawn and the internal pressure forces the sides of the slit together so as to contain the pressure fluid. As the pressure fluid is introduced into the container or package, it releases coating 9 from a portion of the inner surface of the package. When the package is fully pressurized, a portion of the controlled release coating has released from the surface of the package to form barrier 10. It is preferred that the barrier assume a dome shape rather than merely wrinkle as it is displaced upward by the pressure fluid and the escape of the fluid product. This condition is enhanced by so formulating the controlled release coating 9 as to be semiadesive so that a predetermined force is required to release the coating from the dispenser wall and in doing so produce a folded margin 11.
If desired, a semi-adhesive lamination 12 may be applied to the inner surface of the package prior to application of the controlled release coating 9. The adhesive may be weak and therefore tend to separate from itself, or its bond with either the package surface or the controlled release coating surface may be weak so as to strip therefrom. One purpose for the semi-adhesive bond between the controlled release coating and the package wall or intervening semiadhesive is to minimize the chance that a portion of the barrier will be forced into contact with dispensing valve 7 and close the valve so that the remaining fluid product cannot be dispensed.
Another approach to this problem is indicated in FIGS. 6, 7 and 8. The construction is essentially the same as that in FIGS. 1, 2 and 3 except that the upper portion of the package is provided with an adhesive lamination 13. The adhesive 13 is intended to provide a permanent bond and is disposed under that portion of the controlled release coating 9 which need not release from the inner surface of the package, that is, if the barrier portion of the controlled release coating is folded within the remaining still intact portion of the controlled release coating, the intact portion will occupy approximately one half the total internal area of the package. By applying the adhesive to essentially one half the internal area of the package in an appropriate pattern, the possibility that the barrier will prematurely close the dispensing valve can be greatly reduced. One solution is to provide an inclined boundary edge 14 as indicated in FIGS. 6, 7 and 8. This may be done by dip coating the adhesive with the package placed at an angle.
Reference is now directed to the embodiment shown in FIGS. 9, l0 and 11. Another means of preventing premature closing of the dispensing valve 7 is to provide a stem 15 extending from the valve 7 to the bottom end of the package. The stem may be provided with longitudinally extending grooves 16 so proportioned that when the barrier collapses about the stern, as represented by 17 in FIG. 11, longitudinal passageways 18 are formed, which continue into the lower end of the dispensing valve 7 as indicated in FIG. 10.
The controlled release coating 9 is applied to the inner surface of the package in the previously described embodiments covers the entire surface of the package except for the closure member 5. Thus only the inner surface of the closure member need to be such as to be compatible to the product dispensed. That is, in the embodiments so far described the barrier and the internal surface of the controlled release coating from a product chamber, whereas the other side of the barrier and the internally exposed walls of the package form the propellant chamber.
Referring to FIGS. 12 and 13, these chambers may be reversed. This is accomplished by providing a separate bottom cap 19 joined to the cylindrical side walls 3 and by folded rim 20. If this is done, the controlled release coating 9 may be applied through the bottom end and a temporary plug 21 may close the top wall 4. When the product is introduced, the controlled release coating is released from the inner surface of the package until the required volume of product has been introduced. The controlled release coating doesnot, of course, cover the bottom cap as the cap is placed in position after the coating operation is completed. The propellant is introduced through the conventional filler valve 8.
The controlled release coating 9 may be introduced in several ways. A simple procedure is suggested in FIG. 14 wherein the liquid-coating is merely poured into the package as from a nozzle 22. The liquid may be caused to completely fill the package. Thereupon, the package is inverted to remove the liquid material, leaving the controlled release coating. Depending upon the nature of the coating, heat may be applied to effect solidification and produce a wall of the desired thickness.
Another procedure as shown in FIG. 15 involves the use of a spray head 23 suspended from a stem 24 for entrance through the top wall 4 or bottom end of the package as suggested in FIGS. 12 and 13. The spray head or the package 1 preferably rotates to effect a uniform coating. Here again heat may be applied to control the thickness of the controlled release coating.
Another procedure as suggested in FIGS. 16, 17 and 18 involves a blow-molding technique which may use a conventional blow-mold fitting 25, having a sleeve 26 to surround the axially extending top portion of the package, or to surround the bottom end of the package. The coating in the form of a bubble is introduced into the package 1 and is forced against the inner walls thereof, progressively forcing air out the top and bottom of the package. To prevent entrapment of air at the periphery of the bottom wall, the bottom wall may be provided with ribs 28 forming small air passages between channels 29 between the blow-molded coating and the channels communicating with a central opening 30, corresponding to the opening which receives the filler valve 8. During the loading operation, the central opening is closed by a plug 31 having passage communicating with the channels 29.
Once the controlled release coating has been applied, a filler valve similar to the filler valve 8 may be inserted. A sealing fit is provided by corrugating portions of the filler valve body to conform to the ribs 28 and channels 29.
The method which forms a part of this invention centers around the step of forming-in-place a controlled release coating within the container or package 1 and then causing the controlled release coating to release progressively from the walls as the product is dispensed or as the propellant is introduced into the package. The method also includes the alternative steps of filling the package with the coating material and pouring out excess material or by spray coating or by mold-blowing the controlled release coating into place.
A further method of effecting formed-in-place coating on the interior walls of the dispenser involves electrostatically charging the package and introducing the coating material in the form of fine particles. This may be accomplished by a suitable spray head inserted in the manner of the spray head 23 shown in FIG. 15, or merely directed inwardly at the mouth of the package, as the charged particles will be drawn to the surface. An even controlled release coating can be produced for the charge at any point diminishes as the coating increases.
Referring to FIG. 14, the liquid poured into the package may contain the coating in solution or as gas powder or a colloidal suspension.
Uniformity of the coating obtained by spraying or by pouring is enhanced by rotation of the package. Also, the package may be heated.
Suitable pressure packages of the invention comprises closed containers made of any appropriate material. For example, the package can be constructed of metal such as a conventional three-piece, tin-free steel aerosol package with a welded or soldered side seam, or onepiece drawn steel or aluminum package or a plastic package such as an injection molded copolymer of trioxane such as Celcon, or an injection blow molded acrylonitrile such as Barex, or an injection molded polyesters such as Valox. The package can be of many sizes and/or irregular shapes particularly the plastic packages. The invention is particularly useful for manufacturing irregularly shaped plastic barrier packages which are essentially non-permeable.
Propellants useful in the present invention are volatile organic compounds or materials, of which many exist in the form of a gas at ordinary temperatures and pressures. They can liquefy at lower temperatures or when under pressure in a package such as those described and claimed herein. Included among suitable propellants are aliphatic hydrocarbons, partially or wholly fluorinated and partially or wholly chlorofluorinated hydrocarbons which have vapor pressures ranging from about 5 to about 100 p.s.i.g. preferably to 50 p.s.i.g., at about 70F. Either a single compound or a mixture of two or more compounds can be used. And other homologs individually having vapor pressures outside the desired ranges set forth, can be used with other homologs, if the combined vapor pressure falls within such desired ranges. By way of illustration, kerosines and light mineral oils can be utilized. Gases such as carbon dioxide,nitrogen and air can be used. Thus, the term propellant used herein denotes liquefied gaseous materials, e.g., propane and non-liquefied materials, e.g. carbon dioxide.
Representative propellants are: aliphatic hydrocarbons, preferably saturated hydrocarbons, such as propane, butane, isobutane and cyclobutane; saturated fluorinated, and fluorinated and chlorinated, aliphatic hydrocarbons illustrated by: l,ldif1uoroethane; l,2dichloro-l,1,2,2-tetrachloroethane;trichlorotrifluoroethane; dichlorodifluoromethane; monochlorodifluoromethane; monofluoromonochloromethane; lmonochlorodifluoromethane; monofluoromonochloromethane; l-monofluoro l, l-difluoroethane; trifluoro ethyl chloride;and octafluorocyclobutane.
Regardless of which of the particular compounds or mixtures thereof are employed herein as propellants, it is not necessary to be concerned about the effect of the propellant on the physical or chemical properties of the dispensable product or their effect upon the surface or area to which the product is applied. This follows from the facts that the propellant or propellants are substantially completely isolated in the propellant section of the package, and that they do not come into contact with the product to be dispensed. Accordingly, in a pressurized package or container of a shaving preparation manufactured in keeping with this invention, those compounds set forth above as propellants which cause a tingling sensation to the skin or instability of lather can be employed as propellants since they are completely isolated from the dispensable product.
In addition to the foregoing, the propellant can be provided by decomposition of a solid or liquid which upon activation generates gas. Typical liquids for use in such a sytem will include aqueous hydrogen peroxide solutions containing a decomposition agent such as ferrous amoneum sulfate. Useful other gas-producing materials include carbonates and bicarbonates which react with acid to liberate carbon dioxide gas, lithum hydride, which generates gas on contact with water, solid carbon dioxide and the like.
The controlled release coating of the invention is formedin-place, integral with the inner surfaceof the package and substantially free from air entrappment. The coating is obtained using various application techniques,including:
a. Conventional hand techniques such as brush, roller, air and airless spray,
b. various spray applications such as electrostatic and flame sprays,
c. machine applications such as roller, knife and blade curtain, air knife and strip and coil coating,
(1. electrodeposition including anodic and cathodic process.
e. powder coating including fluidized bed and electrostatic spray f. non-aqueous dispersion coating, and
g. hot melts and high energy curing including gamma ray, electron beam, ultraviolet, infrared, microwave, and induction heating.
The raw materials for controlled release coating include: v I
a. Resins such as; vinyl acetate, homo and copolymerswith ethylene; acrylates dibutyl maleates fumarates, polyvinyl formal and polyvinyl butrayl; acrylic styrene, styrene-butadiene, polyvinyl chloride, alkyd polyesters, urethane, epoxy, polyamide, amino and phenolic, and
b. polymers such as: vinylidene chloride, olefin polymers and copypolymers; polyethylene, polypropylene, ethylene copolymers, polybutadiene, polyimides, polyamide, polyester-imides and various rubbers.
In a preferred embodiment of the invention the controlled release coating is a laminate of various polymers and/or resins, and mixtures thereof which provide optimum release properties with maximum strength and optimum barrier properties specifically low permeability.
The integrity, release and low permeability properties of the controlled release coatings can be further modified by the addition of various secondary binder components such as plasticizers, rheology control agents, driers, surfactants, heat stabilizers, crosslinking agents, pigments, extenders and fillers.
Solvents for the controlled release coatings include: aliphatics, aromatics, esters, ketones, and alcohols. Non-aqueous dispersions which use less organic solvent then solution coatings can be used.
Water based and solventless coatings are particularly attractive where pollution control is desired. Examples of the latter include: radiation cured one component fluids, two component liquid systems such as epoxies polyamides and powder coatings.
Controlled release coatings of the invention are characterized by a chemical/mechanical bond with the inner surface of the package. In a preformed embodiment, this bond is substantially free from air entrappment. The bond obtained is a function of the adhesive properties of the coating material and the nature of the inner surface of the package. For example, various portions of the inner surface can be pretreated with bond modifiers so as to selectively control the coating/inner surface bond. (See FIG. 3). Similarly, the coating can be constructed of laminates with that layer of the laminate that is in contact with the package inner surface having optimum bonding properties that compliment the inner surface pretreatment in order to obtain the desired release. (See FIG. 4).
Thus portions of the controlled release coating can be released with a minimal change in pressure such as shown in FIG. 4, while other portions of the coating remain integral with the inner surface irrespective of the change in pressure up to the total exhaustion of the contents of the package. (See FIG. 7).
The potential for permeability of either propellant, product or product components across the barrier is unexpectedly reduced with the controlled release coatings of the invention. The barrier which is formed with introduction of propellant comprises a small portion of the total surface area of the controlled release coating. This portion of the barrier is subjected to the severest permeability demands of any part of the controlled release coating since it is exposed to propellant longer than the remainder of the barrier formed when the product is dispensed. This initial barrier area, that is, that portion of the controlled release coating which is released from the package inner surface Upon the in troduction of propellant, can be further modified during the coating process to obtain improved anti-permeability properties. The anti-permeability control means which can be used include various additional layers of coating materials such as polyvinylchloride, polyimides, polyamides, polyesters, metallic films and the like and various combinations thereof. In a preferred embodiment of the invention the anti-permeability control means comprises a semi-rigid laminate of a coating material such as polyvinylchloride and an electrodeposited metal.
The heretofore unobvious advantages of the invention such as controlled release coatings and permeability control are particularly important to plastic barrier packages. That is, permeability of plastic package per se, has been one of the primary restrictions in the commercialization of plastic aerosol packaging. Additionally, the exposure of the entire plastic package to a constant pressure has resulted in many long term shortcomings of plastic aerosols including those problems related to cold flow-creep, and physical changes in structure and the like. The use of controlled release coatings in combination with initial barrier formation to define a limited area for propellant containment is particularly useful in plastic aerosol packages. Since the techniques employed to improve permeability of the initial barrier can also be used to improve the permeability of the plastic package in the area defining the propellant prior to dispensing. Additionally, the controlled release coatings of the invention offer substantial advantages to plastic aerosol packages in overall permeability performance.
In the preferred embodiment of the invention, the barrier is not defined during filling of the product. That is the controlled release coating is integral with essentially the entire inner surface of the package wall including the bottom wall 2 and substantially free from air entrapment. This is particularly critical to those embodiments of the invention which are useful in high speed underthe-cap filling methods, such as described in U.S. Pat. No. 2,947,626. Since there is no space between the coating and the inner surface of the package, the high pressures used to introduce product during filling will not rupture the coating of the invention which can occur with systems, characterized by bags or other means which are not integral with the package wall and have air entrapped between the inner surface of the package and the bag.
Reference is made to FIG. 20 which is a chart illustrating the advantages of the present invention which are obtained during filling of the package with a food toping at about 120 to I p.s.i.g. That is, a formed-inplace, controlled release, polyester modified coating of the invention which is integral with the dispenser inner surface and substantially free from air entrapment requires a maximum tensile shear/shear strength of about 10 oz. at approximately the fill level. In contrast, a bag barrier package which is supported at the valve cup requires a tensile/shear strength over 20 02. at about the 40% fill level and again at about the 80% fill level.
After the package is filled and the dispensing valve secured to the package, the barrier is defined by introducing the propellant through propellant filling means 8. Such methods of introducing propellant are described in detail in Drug and Cosmetic Industry, Au gust, 1967, and Canadian Pat. No. 751,725. At this time a portion of the controlled release coating releases from the package inner surface to define a container for the propellant. (See FIG. 3 or 4). Upon actuation of the dispensing valve a pressure increase is created across the barrier 12, the barrier being defined as that portion of the controlled release coating which is no longer integral with the package inner surface. The controlled release coating responds to this pressure increase by releasing from the inner surface of the package to the extent necessary so that there is substantially no pressure differential across the barrier. (See FIG. 8)
In another embodiment of the invention deformation of the barrier is controlled by the combination of the controlled release properties of the coating and the physical properties of the barrier, its elastomeric properties, and the inclusion of preferential deformation means such as the various ribs and the like.
Reference is now directed to FIG. 21 which is a chart illustrating the tensile/shear strength required at various fill levels under drop test conditions. This chart illustrates the unobvious advantages of the present invention which are obtained when a package constructed in accordance with the invention is drop tested at 10 g. That is, when a 7 oz. barrier package having a modified polyester controlled coating is filled with a tooth paste to various levels, charged with a hydrocarbon propellant and drop tested, the tensile/shear strength requirements of the integral coating of the present invention were slightly greater than 10 oz. at 60% fill level. In contrast, a bag barrier package in which the barrier is supported at the valve cup and filled with the same product and charged with the same propellant required a tensile/shear strength of over 20 02. at the 60% fill level.
Reference is now directed to FIG. 22 which is a chart illustrating the advantages in anti-permeability obtained with a barrier package of the present invention. That is, the potential for permeability occurring across the barrier is dramatically reduced in the controlled released coating of the invention. Until the package is actuated and a product dispensed approximately 9% of the controlled release coating has been released to form the barrier and contain the propellant. This portion of the controlled release coating could be further modified to control permeability. in contrast, a bag barrier package which is supported at the valve cup has up to 98 percent of the bag liner exposed to product and propellant prior to the first actuation. When the permeability potential of these two barrier packages are plotted over the average shelf life of a package (21 months) and during an average use period of three months, the advantages in reduced permeability potential of the invention is illustrated in FIG. 22.
FlG. 23 is a chart which illustrates the barrier area exposed to product and propellant during product life by use of the present invention in comparison to use of an unsupported bag or bellows system. More particularly, the percent of polyester modified coating re- Certain attributes of dispensers incorporating the present invention are compared to various commercially available dispensers in Table I which follows:
TABLE I FACTORS TO BE TYPE OF BARRlER PACKAGE COMPARED Package of the Invention POWR-FLO Package SEPRO Package US. 3,393,842 US. 3,451,592
Cost for 7 oz. 0.2-0.8 premium 2-4 premium over 4-6 premium over (Including over 3 piece package 3 piece package 3 piece package filling) Manufacturing Conventional package Special equipment Special equipment Characteristics coating equipment can required to Stuff to stuff bag into be adapted bag into package package and attach and attach to chime at valve cup. Barrier Coating applied to package Cut and formed bag Blow molded bag Formation inner wall-uniting with from sheet stock See photograph Means of attaching barrier to the wall as integral part see photograph stage 1 Coating bonded to & integral with with sealed bottom seam. See photograph Stage I Bag secured to upper chime of package &'
Stage 1 Bag secured at valve cup and package substantially all suspended in package. suspended in of the package inner See photograph Stage 1. package. See wall except for valve photograph area. See photograph Stage 1. Stage 1 Air/Propellant Less than about 207: Propellant/air surentrapment of barrier surface rounds approx. 70% Propellant/air is exposed to propellant. of bag surface. See surrounds over 80 Since coating is integral photograph Stage 1. per cent of bag with package inner wall surface. See there is substantially photograph Stage no air entrapment. See 1 Photograph Stage 1 Barrier Permeability controlled Permeability can be Most gases and Properties by type. number and amount improved with liquids diffuse of coatings. laminated stock. thru Conoloy bag wall will not contain peppermint flavor-nor will it restrict propellant from contaminating product Dispense of the Power Flo Sepro invention Barrier Anything that can be Limited to bag Limited to mold- Options sprayed to produce forming capabili ing capabilities a coating with ties and sheet & related liner controlled release stock availabiliforming techniques properties is ties. suitable. Deformation/ Controlled release Random deformation Convulutions discharge and controlled deforsee photograph, note molded into bag. potential mation result in Stage 3 approx. 9% see photograph approx. 1% by weight of product not discharged.
by weight of product cannot be discharged note Stage 3, l4% by weight of product cannot be discharged.
FACTORS TO BE TYPE OF BARRIER PACKAGE COMPARED Package of the Invention POWR-FLO Package SEPRO Package U.S. 3.393.842 U.S. 3.45l.592
Stress No stress areas Attachment at chime Attachment at Areas common to suspended area a performance valve cup area liners see FIG. 2i vulnerability See definitely a drop test performance performance in FIG. 21 vulnerability. See drop test performance described in FIG. 21 Filling High pressure. high Low pressure, low Low pressure.
speed. under-the-cap speed liquid filling. low speed, filling with no effect High pressure filling ilqUlCi filling ruptures attachment at chime. See FIG. 20 Filling speeds approx. 160 per min.
on barrier integrity. See H0. 20 Filling speeds up to 800 per min.
Equipment required for securing bag to chime requires extensive change parts to change diameter and/or length of bag Adaptable to any shape, size or material with slight modification to coating equipment Package size, Shape & type of material Controlled permeability Obtained by controlled release property of the invention.
See FIGS. 22 8t 23 & the photograph.
with spinning of packa e required for filling convulutions. High pressures rupture attachment at valve cup. See FIG. 20 Filling speeds approx. l40 per min. Limited by availability of molds for the bag. Each size package requires a new mold for bag Not obtainable as up to 80% of bag surface is exposed to propellant.
See H65. 22 8t 23 & the photograph.
The barrier packages of the present invention are particularly suitable for dispensing flowable materials such as liquids, pulps, pastes, powders and the like, including products such as food stuffs, cosmetics, pharmaceuticals, toothpastes, mouth wash, shaving cream, shampoo, antiperspirant, caulking compounds, adhesives and the like. lllustratiye examples of such products packaged in the dispensers of this invention are set out in Table ll below in which the products are. A
0 Prefoamed shaving cream; B. Toothpaste; Food topping; D. Skin cream; E." Cough medicine and F. Caulking compound:
Dispensed TABLE ll-Continued FACTORS TO BE COMPARED Prefoamed Shaving Toothpaste Food Topping Cream Barrier Controlled by a Circumferential Combination of annular Deformation series of longispiral rein and longitudinal retudinal reinforcements inforcements forcements Air Entrap- Less than 1% Insignificant Insignificant ment Permeability Insignificant, Insignificant. Insignificant,
7 oz. fill particularly as particularly as particularly as to after 24 to propellant to mint flavor flavor components months blend v r Percent 7- l 071 8 l 2% 9/( Coating i Exposed to Propcllant Before Actuation (initial Barrier) Permeability Multiple layers Electro- Laminate of polyimide Control Means of polyvinyldeposited and eleetrodepositcd chloride on a Barrier area metallic film over enetial barrier area metallic film (semirigid) metallic film Skin Cream Cough Medicine Caulking Compound Package Injection Molded injection/blow Three piece steel C elcon molded Celcon with side seam Controlled Acrylic styrene/ Dibutyl maleate/ Polyester laminate Release polyamide urethane/poly- Coating laminate propylene Coating Spray Spray Dip Application Method Coating 2-4 3-6 3-6 Thickness in MllS t Propellant Fluorinated/ Non-condensable Cg,-C hydrocarbon blend hydrocarbon/ gas r hydrocarbon blend l P.S.l.G. 30 7 9'0 '46 Percent 96-98 90494 90-92 Product Dispensed Barrier No special Pretreatment of Combination of pre- Deformation provisions portion of inner treatment of portion I surface/longiof dispersion inner tudinal reinsurface and reinforced forcements laminate Air Entrapinsignificant Insignificant Less than 1'7: ment Permeability Insignificant, Insignificant. insignificant, 7 oz. fill particularly as to particularly as particularly as to after 24 fragrance. to flavors and initiator and water months emollients and actives and water water Percent 20-3071 4-87: 5% Coating 'Exposed to Propellant Before Actuation (initial Barrier) Permeability Multiple layers Polyamide Rigid metallic film/ Control Means of polyvinyl laminates polyester laminate chloride and As the chart illustrates, the percent of controlled release coating ranged from to exposed to the propellant; whereas, the unsupported bag maintained an exposure greater than While particular embodiments of this invention have been shown and described, it is not intended to limit the same to the details of the construction set forth, but instead, the invention embraces such changes, modifications and equivalents of the various parts and their relationships as come within the purview of the appended claims.
1. The method of making a barrier package containing a propellant separated from a product to be dispensed, comprising the steps of:
a. forming a container having first and second walls and an intermediate wall extending therebetween;
b. covering at least about one-half of the inner surface of said container, including said second wall, with a substantially impermeable continuous coating in intimate contact with said inner surface;
c. adhesively bonding and sealing said coating to said inner surface, at least throughout substantially all of the area thereof covering said intermediate wall, the strength of said bond being less than the tensile strength of said coating;
d. placing a charge of product, less than the internal volume of said container, through said first wall and inside said coated container;
e. introducing a propellant through said second wall to separate an initial portion of said coating therefrom and push said separated coating toward said first wall, until said product and propellant substantially fill said container while leaving the remainder of said coating bonded to said container whereby permeation of product or propellant through said coating cannot occur through the bonded remainder thereof during shelf storage and whereby progressive release of product through said first wall will progressively strip said remainder of said coating from said intermediate wall and thereby control the permeability potential of said coating.
2. The method of making a barrier package as defined in claim 1, wherein:
a. the coating occupies in excess of one-half of the inner surface of the container, and comprises the further step of: permanently bonding to the container, that portion of the coating in excess of onehalf thereof.
3. The method of making a barrier package. as defined in claim 1, further characterized by:
a. spraying a liquid onto the inner surface of the container to form said coating. 4. The method of making a barrier package, as defined in claim 1, further characterized by:
a. spraying a particulate material onto the inner surface of the container while heating the container to the melting temperature to form said coating.
5. The method of making a barrier package. as defined in claim I, further characterized by:
a. pouring a liquid material into the container to form the coating, then pouring out excess liquid material.
6. The method of making a barrier package, as defined in claim 1, further characterized by:
a. blow molding the material forming the coating within the container. 7. The method of making a barrier package, as defined in claim 1, further characterized by:
a. attracting the material forming the coating to the surface of the container by an electro-static charge. 8. The method of making a barrier package, as defined in claim 1, further characterized by:
fined in claim 1, further characterized by:
a. applying to that portion of the coating to be released upon initial introduction of said propellant, a permeability reducing lamination.
10. The method of making a barrier package as defined in claim 1, further characterized by:
a. placing a charge of product through said first wall and inside said coated container at high pressure.