US20050242101A1

US20050242101A1 - Seal-coated plastic container for dispensing a pressurized product

Info

Publication number: US20050242101A1
Application number: US10/834,646
Authority: US
Inventors: Michael Skalitzky
Original assignee: Samsung Electronics Co Ltd
Current assignee: Samsung Electronics Co Ltd
Priority date: 2004-04-29
Filing date: 2004-04-29
Publication date: 2005-11-03
Also published as: CA2564261A1; WO2005108241A1

Abstract

A seal coated plastic container for dispensing a pressurized product such as an aerosol or pressurized liquid, gel, or foam. The seal coating is applied to the exterior surface of the plastic container and effectively inhibits migration of non-liquefiable gas propellants and oxygen through the walls of the container. The plastic bottle is composed of a gas permeable polymeric material such as a polyolefin, polyester, or nylon or polycarbonate, and the seal coating is composed of at least one layer of a barrier material which has a low permeability to the non-liquefiable gas used as the propellant, i.e. the seal coating exhibits a high resistance to the passage of the non-liquefiable gas therethrough. The preferred polymeric material for the plastic bottle is polyethylene terephthalate, and the preferred seal coating is an epoxy-amine. The seal coating provides a coating of the barrier material that is about 0.005 to about 0.025 mm thick, but yet can greatly extend the shelf life of pressurized products such as an aerosol.

Description

BACKGROUND OF THE INVENTION

The present invention relates to containers for dispensing pressurized products such as aerosols, and more particularly to a seal coated plastic container for dispensing a pressurized product such as an aerosol that effectively inhibits migration of carbon dioxide or similar propellants through the walls of the container.
The term “pressurized products” or “pressurized compositions” will be understood herein to encompass both aerosols, literally, as well as other liquid or flowable products that can be dispensed from pressurized containers in a manner comparable to aerosolized products and, unless a narrower meaning is clearly imposed by the context, “aerosol” herein shall be understood to include such other forms of “pressurized products.” Such pressurized products include but are not limited to foamed or gel preparations or to liquid products delivered in a non-aerosol stream. Typical examples of such pressurized products are insecticides, insect repellants, hairsprays, air fresheners, cleaning preparations, and shave preparations including foams and gels.
Containers for dispensing pressurized products such as aerosols are well known in the art, and are typically constructed of metal in order to withstand the inherent internal pressure created by the propellant. However, plastics have found increasing use as replacements for metal, especially when packaging pressurized products such as beverages, because plastics have many advantages over metal. Some of these advantages include the ease and economy of manufacture, thus resulting in potentially lower costs, as well as lighter weight, decreased breakage and aesthetic appeal to an end user.
Despite the desirability of using plastic containers, there are some disadvantages to utilizing plastic materials to contain pressurized products. For example, one of the most glaring shortcomings of plastic containers is that many polymeric materials, such as polyolefins, for example polyethylene (PE) or polypropylene (PP), as well as polyesters such as polyethylene terephthalate (PET), nylons and polycarbonates, are known to be very gas permeable. In other words, gasses such as carbon dioxide utilized as a propellant in pressurized products can migrate through the polymeric materials at an unacceptable rate thus substantially reducing the shelf life of the product. This especially is a problem with propellant gasses that are not liquid at common room temperatures and typical aerosol pressures (referred to herein as “non-liquefiable” gasses). Propellant gaseous pressure above a liquefied propellant, such as a butane or similar conventional hydrocarbon propellant, is renewed from the liquid reservoir when product is delivered from a conventional, metal aerosol can. However, when a propellant is a gas that is non-liquid at those temperatures and pressures, only the container's original charge of pressurized gas is available for use, with no reservoir to restore pressure after product is discharged, except perhaps for such small amounts of gas as may be dissolved in any remaining product. Such non-liquefiable gasses commonly used as propellants, either alone or in combination with other gasses, include carbon dioxide, nitrous oxide, nitrogen, air, and the like. For convenience, carbon dioxide propellant systems will be discussed herein, but only as an example of such gasses so that, unless the context clearly indicates the contrary, what is said with respect to carbon dioxide as a propellant also is intended to apply to other non-liquefiable propellant gasses.
As a result of the gas permeability problem, polymeric materials such as polyolefins, polyesters, nylons and polycarbonates have in the past had limited use for packaging of pressurized products that may be subjected to extended storage. Numerous barrier coatings have been developed for coating plastic containers in an attempt to reduce the carbon dioxide permeability of plastic containers. For example, U.S. Pat. No. 2,830,721 discloses a polyamide-epoxide coating for plastic containers. The purpose of the coating is to reduce the permeation of organic solvents through polyethylene containers. Other barrier coatings are described in U.S. Pat. No. 5,008,137, U.S. Pat. No. 5,300,541, U.S. Pat. No. 5,489,455, U.S. Pat. No. 5,491,204, and U.S. Pat. No. 5,573,819. While such barrier coatings have been moderately successful in the beverage industry in connection with soft drinks and beer, such coatings have not heretofore been utilized in connection with dispensers for pressurized products such as aerosols which are generally delivered from a pressurized container through a valve and actuator at higher pressures than soft drinks and/or beer and require significantly longer shelf life.

SUMMARY OF THE INVENTION

The present invention is directed toward a seal coated plastic bottle or container for dispensing a pressurized product such as an aerosol. The seal coating is applied to the exterior surface of the plastic bottle and effectively inhibits migration of carbon dioxide and other non-liquefiable propellant gasses through the walls from the interior to the exterior of the bottle. The seal coating also effectively inhibits migration of oxygen in the surrounding atmosphere through the walls into the bottle, which could affect the product if the product is oxygen sensitive. Thus, the plastic bottle is comprised of a relatively gas permeable polymeric material such as a polyolefin, a polyester, polyvinylchloride (PVC), copolymer PVC, a nylon, or a polycarbonate, and the seal coating disposed on the exterior surface of the bottle comprises at least one layer of a barrier material which has no or at least a low permeability to non-liquefiable gasses such as carbon dioxide and oxygen, i.e. the seal coating exhibits a high resistance to the passage therethrough of carbon dioxide or other non-liquefiable gas being used as a propellant or of oxygen. “Relatively gas permeable” materials are defined herein as materials that are permeable to carbon dioxide to at least about the same extent as are polyolefins such as polyethylene (PE) or polypropylene (PP), as polyvinylchloride (PVC) or copolymer PVC, or as polyesters such as polyethylene terephthalate (PET), nylons and polycarbonates. The preferred polymeric material for the plastic bottle is polyethylene terephthalate, and the preferred seal coating is an epoxy-amine, although other coatings, such as saran-based coatings, are also possible. Although the seal coating provides only about a thin coating of the barrier material, coating thicknesses ranging from 0.005 to 0.025 mm can greatly extend the shelf life of pressurized products such as an aerosol.
A thickness range from 0.006 to 0.009 mm is preferred, while a thickness of about 0.007 mm is most preferred as providing a useful and practical reduction of carbon dioxide or other non-liquefiable gas permeability at a tolerable cost for modestly-priced consumer products. A generally uniform thickness is preferred as providing the most predictable results, albeit useful results can be obtained even with seal coatings of variable thicknesses.
The principal advantage of plastic bottles or containers utilizing a seal coating in accordance with the present invention is the overall reduction in the migration of carbon dioxide or other non-liquefiable propellant gas through the container walls which results in a major increase in shelf life of the product. To achieve this advantage, however, it is not necessary that the entire surface area of the bottle be coated with the barrier material, and significant reductions in the loss of carbon dioxide propellant may be achieved with only about 50% or less of the bottle's outer surface covered by the seal coating. Coating the entire outer surface of the plastic bottle is most advantageous, but under some circumstances, coating only a portion of the outer surface area is advantageous in that the coating process may be simplified and may be more economic to manufacture if the seal coating is applied only onto areas of the bottle that are relatively easy to coat, such as the sidewalls of the bottle. Thus, sufficient reduction in carbon dioxide and/or oxygen migration may result with both total as well as partial coatings, depending upon the pressurized product being contained as well as the desired shelf life for the product.
In one particularly preferred embodiment, the present invention is directed toward a pressure resistant plastic bottle for containing and dispensing a pressurized product, such as an aerosol composition, wherein the plastic bottle is seal coated with the barrier material. In this embodiment, the plastic bottle is comprised of a hollow elongate body having a longitudinal axis and an outer wall. The outer wall is seal coated with a carbon dioxide barrier material over at least 50% of its exterior surface area, and defines a central portion, a top portion and an opposite bottom portion. The central portion has a circular cross-sectional configuration taken through a plane perpendicular to the longitudinal axis and has an inwardly projecting concave configuration extending along its longitudinal direction. Preferably, the central portion of the bottle has a hyperboloid configuration. The bottom portion of the elongate body is integral with the central portion and defines an outwardly projecting convexly shaped configuration extending along a direction transverse to said longitudinal axis. Preferably, the convexly shaped configuration comprises a base portion having a spherical end configuration and a side portion having a spherical segment configuration. The seal coating effectively reduces the migration of carbon dioxide and/or oxygen through the walls of the bottle to yield a major increase in the shelf life of the pressurized product. In addition, the seal coating protects the bottle and its contents from ultraviolet (UV) light degradation. Also, the design of the central portion and bottom portion of the plastic bottle effectively resists the internal pressures generated by an aerosol to minimize any deformation. Further, any deformation that may occur results in a substantially uniform change which can be accommodated by the top portion of the plastic bottle.
The top portion of the bottle is integral with the central portion and has an outwardly projecting convex configuration extending along its longitudinal direction, and defines a neck having an opening for receiving and dispensing the pressurized composition. A closure covers the opening and is sealingly attached to the neck to contain the pressurized composition within the plastic bottle. The closure includes a valve member having an axially extended valve stem which must be either depressed or tilted to release the pressurized composition contained in the plastic bottle. In order to accomplish this, a cap assembly includes an actuator operably associated with the stem to activate the valve member and dispense the pressurized composition.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:
FIG. 1 is an elevational view of a seal coated plastic bottle and cap assembly in accordance with the present invention used for containing and dispensing a pressurized composition; and
FIG. 2 is a cross-sectional view of the seal coated plastic bottle and cap assembly taken along the line 2-2 in FIG. 1 with a closure and valve shown only partially in section.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawings, there is illustrated a pressure resistant plastic bottle generally designated by the numeral 1 for containing and dispensing a pressurized product such as an aerosol composition. The outer surface of the plastic bottle 1 is seal coated with a layer 35 of barrier material which is composed of a polymeric material that substantially reduces the migration of carbon dioxide gas used as the propellant for the pressurized composition through the polymeric material from which the plastic bottle 1 is manufactured.
The plastic bottle 1 may be composed of any thermoplastic polymeric material that may be formed into the desired shape disclosed herein. Preferred polymeric materials include polyolefins such as polyethylene (PE) or polypropylene (PP) as well as polyesters such as polyethylene terephthalate (PET), nylons, polycarbonates, polyvinylchloride (PVC), and copolymer PVC. Examples of such materials include ethylene based polymers, including ethylene/vinyl acetate, ethylene acrylate, ethylene methacrylate, ethylene methyl acrylate, ethylene methyl methacrylate, ethylene vinyl acetate carbon monoxide, and ethylene N-butyl acrylate carbon monoxide, polybutene-1, high and low density polyethylene, polyethylene blends and chemically modified polyethylene, copolymers of ethylene and C1-C6 mono- or di-unsaturated monomers, polyamides, polybutadiene rubber, polyesters such as polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate; thermoplastic polycarbonates, atactic polyalphaolefins, including atactic polypropylene, polyvinylmethylether and others; thermoplastic polyacrylamides, polyacrylonitrile, copolymers of acrylonitrile and other monomers such as butadiene styrene; polymethyl pentene, polyphenylene sulfide, aromatic polyurethanes; styrene-acrylonitrile, acrylonitrile-butadiene-styrene, styrene- butadiene rubbers, acrylontrile-butadiene-styrene elastomers, polyphenylene sulfide, A-B, A-B-A, A-(B-A)_n-B, (A-B)_n-Y block polymers wherein the A block comprises a polyvinyl aromatic block such as polystyrene, the B block comprises a rubbery midblock which can be polyisoprene, and optionally hydrogenated, such as polybutadiene, Y comprises a multivalent compound, and n is an integer of at least 3, and mixtures of said substances. The most preferred thermoplastic material is polyethylene terephthalate (PET). PET is commercially available from numerous sources, and one such source is M&G, Inc. under the trade designation Traytuf®. Preferably, the thermoplastic polymer used to make the plastic bottle 1 is transparent, although opaque and partially opaque polymers would also function adequately.
The plastic bottle 1 may be formed by any conventional molding technique, such as two-stage blow molding. In two-stage blow molding, a pre-form of the plastic is made by injection molding. The pre-form provides the mass of material that eventually is blown into final shape, but it also may include in substantially final form such features as the bottle neck 11 and annular flange 19, described below. The pre-form is reheated, enclosed within the halves of a blow mold, and thereafter expanded in such mold. Under such a process, the plastic bottle 1 may be formed integrally in a one-piece construction which is the preferred construction. Blow molding techniques, as well as other techniques for manufacturing plastic bottle 1 are well known in the art and need not be further described herein.
Referring now to FIGS. 1 and 2, the plastic bottle 1 comprises a hollow elongate body having a longitudinal axis 2 and an outer wall 3. Outer wall 3 may vary in thickness from between about 0.25 mm to about 1.6 mm, but is preferably about 0.64 mm. Bottle 1 may be divided into three sections or portions, namely, central portion C, a top portion T and an opposite bottom portion B. As noted above, each of these portions is integral with the other and is formed as a one-piece construction. The transition between bottom portion B and central portion C is defined by a plane extending perpendicular to axis 2 and is represented by line 28 while the transition between central portion C and top portion T is also defined by a plane extending perpendicular to axis 2 and is represented by line 29. As shown best in FIG. 2, bottom portion B, central portion C and top portion T define an upper compartment 4 and a lower compartment 5 within the body of plastic bottle 1. Compartments 4 and 5 contain the aerosol composition (not shown) which is typically pressurized at an internal pressure of about 275.8 kPa to about 620.5 kPa with solubilized carbon dioxide (CO₂) as the propellant. Examples of typical aerosol compositions are insecticides, insect repellents, hairsprays, air fresheners, cleaning preparations, and shave preparations including foams and gels. The preferred aerosol is a shave preparation pressurized to about 585 kPa with solubilized carbon dioxide (CO₂) as the propellant, which provides adequate internal pressure for dispensing the aerosol upon actuation of the valve, as will hereinafter be described.
Each of compartments 4, 5 have a maximum diameter, and the maximum diameter of compartment 4 compared to the maximum diameter of compartment 5, or vice versa, ranges between a ratio of from about 2 to 1 to about 1 to 1. A ratio greater than 1 to 1 is preferred in that a ratio greater than 1 to 1 results in a single contact location between bottles 1 when multiple bottles are clustered on a conveyer belt or are otherwise being processed, moved, or packaged as a group. Other preferred features with respect to such a contact location are discussed, below. Preferably, the maximum diameter of upper compartment 4 is slightly greater than the maximum diameter of lower compartment 5 although just the opposite would also be effective. As shown best in FIG. 2, the maximum diameter of upper compartment 4 is located in top portion T above line 29, while the maximum diameter of lower compartment 5 is located in bottom portion B below line 28. The preferred diameter for upper compartment 4 is about 5.334 cm whereas the preferred diameter of compartment 5 is about 5.309 cm. The narrowest diameter, designed by the number 30 and which is located in the middle of central portion C, is approximately 4.57 cm. The overall length of the bottle is about 16.07cm. It should be noted that although in the preferred embodiment the upper compartment 4 has a diameter and a volume that is slightly greater than the diameter and volume of lower compartment 5, just the opposite could also be acceptable. In other words, the diameter and volume of lower compartment 5 could, in fact, be greater than upper compartment 4 if desired. Preferably, the central portion has a hyperboloid configuration which provides a very ergonomic structure which is easily handled by a user.
The bottom portion B of bottle 1 is integral with the central portion C and defines an outwardly projecting convexly shaped or dome shaped configuration extending along a direction transverse to the axis 2. The term “convexly shaped” or “convexly shaped configuration” refers to any curved or rounded shape projecting outwardly from the transverse plane defined by line 28. Examples of such shapes include a hemisphere, an ellipsoid, a hyperbola, a parabola, an arcuate shaped configuration, or an arcuate shaped configuration having multiple arcuate sections such as a combination of a spherical segment having one radius and a spherical end having a second different radius. This latter convexly shaped configuration is the preferred configuration for bottom portion B and is illustrated in FIGS. 1 and 2. Likewise, the term “concave configuration” refers to any curved or rounded shape projecting inwardly toward longitudinal axis 2. Examples of such shapes include a hemisphere, an ellipsoid, a hyperbola, a parabola, an arcuate shaped configuration, or an arcuate shaped configuration having multiple arcuate sections such as a combination of a spherical segment having one radius and a spherical end having a second different radius. As noted above, a hyperboloid is the preferred concave configuration for central portion C and is illustrated best in FIGS. 1 and 2. The convexly shaped bottom portion B in combination with the inwardly concave configuration of central portion C functions to enable bottle 1 to contain the pressure of an aerosol therein without any substantial deformation. It should be noted from FIG. 2 that central portion C and bottom portion B have smooth surfaces without any abrupt changes which limits stress concentration points and provides maximum resistance to distortion from internal pressures generated by the aerosol within bottle 1. Although smooth, curved surfaces that merely join without any abrupt changes in curve are within the scope of the invention, preferably all adjoining curves, especially in the bottom portion B, central portion C, and the area of transition from the central portion C to the top portion T, are tangent to each other, substantially eliminating stress concentration points. Furthermore, any distortion which may occur will be substantially uniform and radially symmetrical, and therefore will not be readily apparent from casual viewing of the bottle 1.
Bottom portion B includes a base portion 6 in the shape of a spherical end defined by a convexly shaped surface having radius R1, and a side portion 7 in the shape of a spherical segment and having an outwardly convexly shaped surface defined by the radius R2. The transition between base portion 6 and side portion 7 is defined by a plane extending perpendicular to axis 2 and is represented by line 31. As shown best in FIG. 2, the radius of curvature R1 has a focal point 8 which is located on longitudinal axis 2. As also shown in FIG. 2, the radius of curvature R2 has its focal point 9 located in the plane perpendicular to longitudinal axis 2 defined by line 28. Preferably, radius R1 is about 3.75 cm whereas radius R2 is about 1.9 cm, resulting in a ratio of about 2 to 1. However, the ratio of R1 to R2 may vary from about 1 to 1 to about 5 to 1 with the preferred ratio being 2 to 1. Preferably, R2 is no less than 0.75 of the radius of any bottle.
FIG. 2 also illustrates that the hyperboloid defining central portion C has a radius of curvature defined by R3. The focal point 10 of R3 is located at a point external to bottle 1 in a plane perpendicular to longitudinal axis 2 located midway between and parallel to the planes defined by lines 28 and 29. As the length of R3 increases, the side wall of central portion C becomes more cylindrical-like, and the more the outer wall of central portion C become cylindrical-like, the less resistance to internal pressure it provides. The preferred radius R3 is about 25.4 cm for a bottle of an approximate radius of 2.54 cm. A central portion C having any concentric and concave shape provides a pressure-containing advantage when combined with bottom portion B and top portion T, joined in the manner disclosed. However, the preferred ratio of R3 to the radius of the bottle is approximately 10 to 1.
The top portion T of bottle 1 is integral with the central portion C and has an outwardly projecting convex configuration extending along its longitudinal direction, and defines a cylindrical neck 11 having a tubular opening 12 for receiving and dispensing the aerosol composition. A closure 13 covers the opening 12 and is sealingly attached to neck 11 to contain the aerosol within the body of plastic bottle 1. Closure 13 includes a valve member 14 having an axially extending valve stem 15 which must be either depressed or tilted to release the aerosol composition contained within bottle 1. Valve member 14 and valve stem 15 are conventional components typically utilized in aerosol containers, and need not be further described herein as they are well known in the art. In order to affix closure 13 onto bottle 1, neck 11 includes an outwardly extending annular rim 16 adjacent opening 12, and closure 13 includes a depending flange 17 which is inwardly crimped about rim 16 to retain closure 13 on neck 11 of bottle 1.
As shown best in FIGS. 1 and 2, top portion T has a circular cross-sectional configuration taken through a plane perpendicular to longitudinal axis 2 and has an outwardly convex configuration extending along its longitudinal direction from a point where it merges with central portion C, i.e. line 29 to a point where neck 11 is formed. Midway between its length, i.e. between central portion C and neck 11, top portion T has a flat section 18 having a constant circular cross-section extending along its longitudinal direction to define a cylindrical configuration. Flat section 18 provides line contact (rather than point contact) between adjacent bottles as they are moved side-by-side down a conveyor belt in contact with each other. Bottles with touching curved surfaces, i.e. point contact, tend to slide up or down thus changing the spacing between bottles. In contrast, bottles having straight surfaces such as that provided by flat section 18 where they touch, i.e. line contact, tend not to slide vertically but instead maintain a desired spacing during manufacture and filling.
Top portion T of bottle 1 also includes an annular flange 19 which projects radially outwardly from neck 11 with respect to longitudinal axis 2. Flange 19 has a thickness sufficient to provide the strength and stability necessary to be an attachment point for the cap member 21, described below. Preferably flange 19 is about four times the minimum thickness of outer wall 3 and terminates at an outer edge 20, which is located at a point between a vertical plane parallel to axis 2 and defined by the outer surface of neck 11 and a vertical plane parallel to axis 2 and defined by the outer surface of wall 3 of top portion T. The outer edge 20 of flange 19 is used as one component in a releasable snap fit mounting arrangement for releasably mounting a cap member 21 to the top portion T of bottle 1, as will hereinafter be described.
As best seen in FIG. 2, cap member 21 has a top circular planar support surface 22 and a depending skirt 23 which is used to cover and surround neck 11 and closure 13. An actuator including a push button 24 hingedly mounted on skirt 23 is operatively associated with valve stem 15 to activate the valve member 14 and dispense aerosol composition in a conventional manner. As noted above, the mounting means for releasably mounting cap member 21 and the integral actuator to the top portion T comprises a releasable snap fit arrangement. The releasable snap fit arrangement comprises the outer edge 20 of annular flange 19 projecting from neck 11 and an annular groove 25 formed in skirt 23 of cap member 21 for receiving the outer edge 20 of flange 19. As shown best in FIG. 2, the annular groove 25 is formed by an inner lip 26 projecting radially inwardly from the inner surface of skirt 23, and a plurality of circumferentially-spaced bosses 27. The bosses 27 are spaced circumferentially from each other and each boss 27 is also spaced longitudinally from inner lip 26 to form groove 25. As shown, each boss 27 includes a tapered or beveled lower surface which permits the cap member 21 to be pushed downwardly until skirt 23 flexes slightly outwardly over outer edge 20 of flange 19. Once outer edge 20 passes over the bosses 27, it abuts against inner lip 26 and the upper surfaces of bosses 27 to be held in place. To remove cap member 21, one merely applies sufficient force to reverse the above snap fit process.
The use of flange 19 as an attachment point for the cap member 21 presents important advantages over attachment of the cap member to other locations on the bottle 1. Flange 19 effectively forms a part of the least flexible portions of the bottle 1. Furthermore, flange 19 is contiguous with the structures that define the neck 11. Consequently, when the bottle 1 is under elevated internal pressure, such as can be experienced when a filled and sealed bottle is warmed in the sun or in a hot shower or bath, and thus experiences some degree of deformation and expansion, the relationship of the bottle to the cap member 21 and of the cap member to a valve member 14 mounted within the neck 11 remains stable and virtually unchanged. If the bottle 1 distorts, it is by an extension of the lower, thinner portions of the bottle. Use of the flange 19 attachment location thus avoids such problems as disengagement of the cap member 21 from the bottle 1 or a bottle distortion-caused failure of the cap member to properly relate to the valve member 14.
As the bottom portion B of plastic bottle 1 is convexly shaped, and the central portion C of plastic bottle 1 is preferably a hyperboloid, planar support surface 22 provides a mechanism whereby plastic bottle 1 may stand upright when stored. In order to accomplish this, top support surface 22 is formed in a plane perpendicular to longitudinal axis 2. Also, top support surface 21 is circular in shape and has a diameter which is greater than the diameter of opening 12 in neck 11, but less than the diameter of top portion T. Support surface 22 thus provides sufficient amount of surface area to enable bottle 1 to stand upright during storage without easily tipping over.
Because plastic bottle 1 is preferably composed of a polymeric material such as a polyolefin (e.g. PE or PP), polyvinylchloride (PVC) or copolymer PVC, or a polyester such as PET, or a nylon or a polycarbonate, and such materials have relatively high carbon dioxide and/or oxygen permeability, the plastic bottle 1 is seal coated on its outer surface with a layer 35 of barrier material. The layer 35 is itself also preferably composed of a polymeric material that substantially reduces the migration of carbon dioxide gas through the polymeric material from which plastic bottle 1 is manufactured. Solubilized carbon dioxide gas is typically used as the propellant for the pressurized composition contained within bottle 1. The term “seal coating” or “barrier material” will be understood herein to encompass a material that has no or at least very low permeability to oxygen and/or carbon dioxide gases, i.e. the material exhibits a high resistance to the passage of oxygen and/or carbon dioxide through the material itself. Seal coatings or barrier materials utilized as layer 35 on plastic bottles containing a pressurized product such as an aerosol are intended primarily as carbon dioxide barriers and should exhibit a carbon dioxide permeability of less than about 5, preferably less than about 1, and more preferably less than about 0.5 measured as cubic centimeters of carbon dioxide gas permeating a 0.3 mm thick sample of material which is 650 square centimeters over a 24 hour period under a carbon dioxide partial pressure differential of one atmosphere at 23° C. and at a relatively humidity of 0. A wide variety of materials can be utilized as the seal coating or barrier material. Polymeric barrier materials, such as saran-based materials or epoxy amine coatings, are preferred as they are typically more economical than other systems. However, an amorphous carbon treatment applied via plasma deposition may also be used if desired. One such carbon treatment is available from Sidel Corporation under the Actis® trademark. Another coating that may be used for layer 35 is a silica dioxide treatment also believed to be applied by plasma deposition. One such silica dioxide treatment is available from The Coca-Cola Company under the Best PET® trademark. It has been found that polymeric material such as an epoxy amine coating available under the trademark Bairocade® from PPG Industries, Inc. is a particularly useful and desirable seal coating to be used for layer 35. This epoxy-amine coating composition is a reaction product of a polyepoxide with a polyamine. A more complete disclosure of the epoxy amine composition itself and the method of manufacturing this composition are described in U.S. Pat. No. 5,080,137, U.S. Pat. No. 5,300,541, U.S. Pat. No. 5,489,455, U.S. Pat. No. 5,491,204, and U.S. Pat. No. 5,573,819, the disclosures of which are specifically incorporated herein by reference.
The seal coatings or barrier materials of layer 35 can be applied as either solvent or aqueous based thermosetting compositions onto the exterior surface of plastic bottle 1 by any conventional means such as spraying, rolling, dipping, brushing or the like. Spray applications or roll applications are preferred, and convention spray techniques and equipment for applying curable coating components can be utilized.
As noted earlier, the principal advantage of layer 35 is the substantial reduction in the migration of carbon dioxide gas through the walls of bottle 1 to achieve a major increase in shelf life of the product. To achieve this reduction, it is typical that the entire outer surface area of bottle 1 be coated with layer 35. However, the seal coating or barrier materials are capable of significant reductions in carbon dioxide permeability even when only about 50% or less of the exterior surface area of bottle 1 is coated with layer 35. Thus, coating only a portion of the surface area of bottle 1 may be advantageous in those circumstances where it is desired to apply layer 35 only onto areas of a container that are relatively easy to coat, such as central portion C and top portion T as opposed to the bottom portion B of bottle 1. Thus, layer 35 may cover the entire surface area or only a portion of the surface area of bottle 1, but it is preferred that at least 50% of the outer surface of bottle 1 be coated with layer 35.
Permeation of carbon dioxide through layer 35 is also a function of the thickness of layer 35. Generally, it is desirable to provide a 0.007 mm coating of the barrier material on the external surface of bottle 1. However, either thinner or thicker layers may be applied, if necessary, depending upon the degree of resistance desired. Coatings ranging in thickness from 0.005 to 0.025 mm provide improved reduction in carbon dioxide permeation. In addition, multi layer barrier coatings may also be utilized, if desired. Thus, a combination of two different barrier materials may be applied depending upon the amount of permeability desired for the product and the shelf life that may be required.
Other modifications. of the plastic bottle 1 of the present invention will become apparent to those skilled in the art from an examination of the above description and drawings. Therefore, other variations of plastic bottle 1 may be made which fall within the scope of the following claims even though such variations were not specifically discussed and/or described above. In particular, various types of cap members and closures may be utilized in combination with bottle 1, whether the valve stem 15 is actuated by being tilted or by being depressed or in other ways. Thus, plastic bottle 1 may be suitable for any aerosol product such as insecticides, insect repellents, hairsprays, air fresheners, cleaning preparations, and shave preparations including foams and gels, and the like.

Claims

1. A plastic bottle for containing and dispensing a pressurized composition, comprising

a hollow plastic body composed of a polymeric material with relatively high gas permeability, said body containing therein a pressurized composition using a non-liquefiable gas as its propellant and further having a neck which defines an opening for receiving and dispensing the pressurized composition;

a closure covering said opening and sealingly attached to said neck for containing said pressurized composition within said body, said closure including a valve member that enables dispensing of said pressurized composition;

an actuator operably associated with said valve member to activate said valve member and dispense said pressurized composition; and

a sealing layer of a gas barrier material coating at least a portion of an outer surface of said body to inhibit migration of the non-liquefiable gas propellant through said plastic body.

2. The plastic bottle of claim 1 wherein said pressurized composition is an aerosol.

3. The plastic bottle of claim 1 wherein said pressurized composition is at a pressure of about 275.8 kPa to about 620.5 kPa within said body.

4. The plastic bottle of claim 1 wherein the polymeric material of the body is a polyolefin.

5. The plastic bottle of claim 1 wherein the polymeric material of the body is a polyester.

6. The plastic bottle of claim 1 wherein the polymeric material of the body is a polycarbonate.

7. The plastic bottle of claim 1 wherein the polymeric material of the body is a nylon.

8. The plastic bottle of claim 1 wherein the polymeric material of the body is polyethylene terephthalate.

9. The plastic bottle of claim 1 wherein the polymeric material of the body is polyvinylchloride.

10. The plastic bottle of claim 1 wherein said gas barrier material is a polymeric material comprising an epoxy-amine.

11. The plastic bottle of claim 1 wherein said sealing layer covers substantially the entire outer surface of said body.

12. The plastic bottle of claim 1 wherein said sealing layer has a thickness of from about 0.005 to about 0.025 mm.

13. The plastic bottle of claim 1 wherein said non-liquefiable gas is selected from the group consisting of carbon dioxide, nitrous oxide, nitrogen and air.

14. A plastic bottle for containing and dispensing a pressurized composition dispensed from a valve by operation of a cap member attached to the plastic bottle, the plastic bottle comprising:

a hollow elongate plastic body composed of a polymeric material with relatively high gas permeability, said body containing therein the pressurized composition using a non-liquefiable gas as its propellant, and having a longitudinal axis, an outer wall, and a top portion having a neck with an opening therein for receiving and dispensing a pressurized composition, the opening being closeable by a closure to be sealingly attached to said neck for containing said pressurized composition within said body, the closure including said valve actuatable via the cap member to deliver the pressurized composition; and

15. The plastic bottle of claim 14 wherein said pressurized composition is an aerosol.

16. The plastic bottle of claim 14 wherein said pressurized composition is at a pressure of about 275.8 kPa to about 620.5 kPa within said body.

17. The plastic bottle of claim 14 wherein the polymeric material of the body is a polyolefin.

18. The plastic bottle of claim 14 wherein the polymeric material of the body is a polyester.

19. The plastic bottle of claim 14 wherein the polymeric material of the body is a polycarbonate.

20. The plastic bottle of claim 14 wherein the polymeric material of the body is a nylon.

21. The plastic bottle of claim 14 wherein the polymeric material of the body is polyethylene terephthalate.

22. The plastic bottle of claim 13 wherein said gas barrier material is a polymeric material comprising an epoxy-amine.

23. The plastic bottle of claim 13 wherein said sealing layer covers substantially the entire outer surface of said body.

24. The plastic bottle of claim 13 wherein said sealing layer has a thickness of about 0.005 to about 0.025 mm.

25. The plastic bottle of claim 13 wherein said non-liquefiable gas is selected from the group consisting of carbon dioxide, nitrous oxide, nitrogen and air.

26. A pressure resistant plastic bottle for containing and dispensing a pressurized composition, comprising:

a hollow elongate plastic body composed of a polymeric material with relatively high gas permeability, said body containing therein a pressurized composition using a non-liquefiable gas as its propellant, and having a longitudinal axis and an outer wall, said outer wall defining a central portion, a top portion and an opposite bottom portion, said central portion having a circular cross-sectional configuration taken through a plane perpendicular to said longitudinal axis and having an inwardly projecting concave configuration extending along its longitudinal direction;

said bottom portion being integral with said central portion and defining an outwardly projecting convexly shaped configuration extending along a direction transverse to said longitudinal axis;

said top portion being integral with said central portion and having an outwardly projecting convex configuration extending along its longitudinal direction and defining a neck having an opening therein for receiving and dispensing the pressurized composition;

a closure covering said opening and sealingly attached to said neck for containing said pressurized composition within said body; and

a sealing layer of a polymeric gas barrier material coating at least a portion of an outer surface of said body to inhibit migration of the non-liquefiable gas propellant through said plastic body.

27. The plastic bottle of claim 26 wherein the convexly shaped configuration of said bottom portion comprises a base portion and a side portion, said base portion having a spherical end configuration defined by a radius R₁having its focal point on said longitudinal axis, and said side portion having a spherical segment configuration defined by a radius R₂having its focal point in a plane perpendicular to said longitudinal axis, and wherein R₂is less than or equal to R₁.

28. The plastic bottle of claim 26 wherein said central portion has a hyperboloid configuration.

29. The plastic bottle of claim 26 wherein said closure includes a valve member that enables dispensing of said pressurized composition.

30. The plastic bottle of claim 26 wherein said outer wall and said sealing layer are both composed of a transparent plastic material.

31. The plastic bottle of claim 26 wherein said neck portion includes an annular rim adjacent said opening and said closure is affixed to said rim.

32. The plastic bottle of claim 29, further including a cap assembly attached to the top portion of said body for covering said closure and valve member.

33. The plastic bottle of claim 32, wherein said cap assembly includes a cap member having a top support surface and a depending skirt, an actuator integral with said cap member and operably associated with said valve member to activate said valve member and dispense said aerosol composition, and mounting means for releasably mounting said cap member and actuator to the top portion of said body.

34. The plastic bottle of claim 26 wherein said pressurized composition is an aerosol.

35. The plastic bottle of claim 26 wherein said pressurized composition is at a pressure of about 275.8 kPa to about 620.5 kPa within said body.

36. The plastic bottle of claim 26 wherein the polymeric material of the body is a polyolefin.

37. The plastic bottle of claim 26 wherein the polymeric material of the body is a polyester.

38. The plastic bottle of claim 26 wherein the polymeric material of the body is a polycarbonate.

39. The plastic bottle of claim 26 wherein the polymeric material of the body is a nylon.

40. The plastic bottle of claim 26 wherein the polymeric material of the body is polyethylene terephthalate.

41. The plastic bottle of claim 26 wherein said polymeric gas barrier material is an epoxy-amine.

42. The plastic bottle of claim 26 wherein said sealing layer covers substantially the entire outer surface of said body.

43. The plastic bottle of claim 26 wherein said sealing layer has a thickness of about 0.005 to about 0.025 mm.

44. The plastic bottle of claim 26 wherein said non-liquefiable gas is selected from the group consisting of carbon dioxide, nitrous oxide, nitrogen and air.