WO2000018661A1

WO2000018661A1 - Aerosol packaging for anaerobic curing compositions

Info

Publication number: WO2000018661A1
Application number: PCT/US1999/022636
Authority: WO
Inventors: Hans Haas; Robert E. Montenieri
Original assignee: Loctite Corporation
Priority date: 1998-09-29
Filing date: 1999-09-29
Publication date: 2000-04-06
Also published as: AU6405799A

Abstract

An aerosol packaging receptacle (10) for anaerobic curing compositions such as adhesives which polymerize in the absence of oxygen is provided. The receptacle (10) includes a pressurized, sealed container (20) having an oxygen impervious wall (25), and a bladder (30) having an oxygen permeable wall (35) within the container. The oxygen permeable wall (35) of the bladder (30) and the oxygen impervious wall (25) of the container (20) define a space (28) therebetween, and an oxygen-rich propellant (29), such as compressed air is contained within the space (28). Oxygen from the oxygen-rich propellant (29) is permeable through the bladder wall (35) to contact the anaerobic composition contained therein, thus preventing polymerization of the anaerobic curing composition.

Description

AEROSOL PACKAGING FOR ANAEROBTC CURING COMPOSITIONS

FIELD OF THE INVENTION

The present invention is directed to a packaging container for curable compositions such as anaerobic curing compositions which polymerize in the absence of oxygen. More particularly, the present invention is directed to an aerosol packaging container capable of containing and dispensing anaerobic curing compositions such as adhesives for extended time periods while remaining fluid.

BACKGROUND OF THE INVENTION

Anaerobic curing compositions are well known curable compositions which remain stable and fluid in the presence of oxygen, such as air, and which polymerize and cure to a solid composition in the absence of air. Anaerobic compositions have found wide industrial use in the bonding of air-impervious substrate surfaces such as metal, and are particularly useful for locking threaded parts. For example, when an anaerobic curing composition is applied to a threaded bolt and a mating nut is screwed thereover, air, and therefore oxygen, is effectively excluded from the composition in the mated threads. Due to the absence of oxygen, the anaerobic composition begins to polymerize and cure, thereby effectively locking the nut onto the bolt.

Since they require oxygen for stability, anaerobic curing compositions are difficult to store. Commonly, anaerobic curing compositions are conventionally stored in containers which are permeable to atmospheric oxygen, such as a tube-type dispenser constructed of low density polyethylene (LDPE). The permeable nature of the container allows oxygen to pass through the walls of the container, which maintains the anaerobic curing composition in fluid form. While LDPE tubes and bottles provide adequate stability at moderate cost, there is a general need for more convenient packaging for certain applications. Furthermore, with certain compositions which are highly active, the LDPE tubes and bottles will not provide adequate shelf stability, and there is a need for containers for such highly active compounds.

Moreover, the accuracy of tube-type dispensers is limited, in that the flow rate of the composition from the tube is controlled by the user squeezing the tube, or by a mechanical dispenser such as a caulking gun. Further, such tube-type dispensers often permit air gaps or bubbles to form in the tube, which can interfere with the flow rate and dispensing of the composition. Such an inaccurate flow control rate poses difficulties in applications when dispensing of an accurate amount of the anaerobic curing composition is required, for example in flange sealant applications.

Aerosol containers are known for containing and dispensing various substances. Such aerosol containers typically include a substance packaged within a metal container under pressure with a propellant for release. For example, the substance can be contained within the container with a propellant mixed directly with the substance.

Alternatively, the substance may be contained within a separate, barrier-type pack within the container, with a propellant surrounding the barrier pack. In such an embodiment, the barrier pack is impervious to air and oxygen, such as an aluminum barrier pack, in order to prevent air and the propellant from contacting the contents of the barrier pack for preservation of the contents.

U. S. Patent No. 3,736,260 to O'Sullivan et al. is directed to an anaerobic curing composition stored in liquid aerosol form. In this patent, the anaerobic curing composition is contained within a conventional aerosol can, with the anaerobic curing composition being directly mixed with the propellant gas, and including oxygen mixed therein. The propellant may be compressed air or other suitable propellant, as long as sufficient oxygen is included to prevent curing of the anaerobic composition. When hydrocarbons are used as the propellant, however, the composition may undesirably react with the hydrocarbons, since the propellant is mixed directly therein. Also, clogging of the valve component of this aerosol dispenser occurs due to curing of the anaerobic composition within the valve, where oxygen contact is minimal.

Moreover, accelerated anaerobic curing compositions such as rapidly curing adhesives require large amounts of oxygen in order to prevent polymerization during storage. Such rapidly curing compositions cannot be effectively contained in tube- type dispensers, and aerosol dispensers as taught by U. S. Patent No. 3,736,260 have not gained commercial acceptance, as an aerosol spray of anaerobic materials have very limited application.

Accordingly, a need exists for an aerosol packaging container capable of containing anaerobic compositions such as adhesives for extended time periods while remaining fluid, and capable of accurately dispensing the compositions.

SUMMARY OF THE INVENTION Broadly speaking, the invention comprises an apparatus for packaging oxygen- stabilized compositions. The apparatus includes a pressurizable, sealed container having a container wall which is substantially impervious to oxygen. A collapsible bladder having an oxygen-permeable wall for containing an oxygen-stabilized composition therein is contained within the container, thus defining a space between the bladder wall and the container wall. An oxygen-containing stabilizer composition is contained within the first container at the space between the bladder wall and the container wall. As such, oxygen from the oxygen-containing stabilizer composition is permeable through the bladder wall to effectuate stabilization of the oxygen-stabilized composition contained within the bladder. The apparatus may further include a valve assembly for dispensing the oxygen-stabilized composition. Preferrably, the stabilizer composition is in the form of a propellant, such as compressed air, for dispensing the stabilized composition from the apparatus.

In more preferred aspects, the present invention provides a dispenser assembly for an anaerobic curing composition. The dispenser assembly includes a first container such as a metal canister defining a first cavity and an opening therein. An oxygen- permeable, collapsible second container, such as high density polyethylene, defines a second cavity which is supported within the first cavity. An oxygen-stabilized flowable material such as an anaerobic adhesive is contained within the second cavity of the second collapsible container. The first and second containers define a sealed pressurized region therebetween. A pressurized oxygen-containing propellant is contained in the first cavity, within this pressurized region. The propellant is preferably compressed air or a gaseous hydrocarbon/air mixture. A valve assembly is further provided which is in registry with the second cavity and in sealed engagement with the opening of the first container. The valve assembly provides meterable fluid communication with the contents of the second cavity of the second container. Thus, by opening the valve assembly, the propellant urges the flowable material through the valve assembly, thus dispensing the material from the dispenser assembly.

The invention further provides for a dispenser assembly including a first container defining a first cavity and an opening, and a permeable, collapsible second container supported within the first cavity and defining a second cavity, with the first and second containers defining a sealed pressurizable region therebetween. A valve assembly in registry with the second cavity and in sealed engagement with the second container at the opening of the first container provides meterable fluid communication with the second cavity.

A compressible propellant may be contained within the sealed pressurizable region between the first and second containers. Further, a flowable or dispensable material may be provided within the second cavity. Preferably, oxygen in the compressible propellant is permeable through the second container to interact with the dispensable material in the second container, for example, to stabilize the dispensable material. Accordingly, the present invention provides a packaging receptacle capable of containing anaerobic curing compositions such as adhesives in shelf-stable form for extended time periods without curing. Further, the present invention provides a packaging container capable of dispensing an accurate amount of a composition. Still further, the present invention provides an aerosol container capable of containing highly reactive anaerobic curing compositions.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a perspective view of a receptacle according to the present invention.

Figure 2 is a cross-sectional view of the receptacle of Figure 1 of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention is directed to an aerosol packaging apparatus and dispensing assembly for storing and dispensing oxygen-stabilized compositions, such as anaerobic curing adhesives which cure in the absence of oxygen. The apparatus includes a pressurized, sealed first container which has an oxygen impervious wall. The apparatus further includes a second container in the form of a bladder having an oxygen permeable wall, for containing the anaerobic curing composition therein. The bladder is contained within the first container, with a space between the wall of the container and the wall of the bladder. An oxygen-containing stabilizer composition is contained within the space between the wall of the container and the wall of the bladder. As such, oxygen from the oxygen-containing stabilizer composition is permeable through the bladder wall to contact the oxygen-containing stabilized composition, thus preventing polymerization of the composition due to the presence of oxygen. Preferably, the oxygen containing stabilizer composition is a propellant for dispensing the oxygen-stabilized composition from the container. As used herein, the terms "anaerobic composition" and "anaerobic curing composition" are used to refer to the combination of a polymerizable monomer and a free radical polymerization initiator therefor, with the mixture hardening by a free radical mechanism which is inhibited by oxygen at room temperature, but which composition will harden within a reasonable time, such as two hours at room temperature, when placed in the absence of oxygen (such as between facing metal plates). The term "anaerobic adhesive" is used to refer to such an anaerobic composition as used to adhere components together.

The anaerobic curing composition of the present application may be any known anaerobic curing composition. Typically, such compositions include a polymerizable monomer and a peroxy initiator therefor which is latent in the presence of oxygen, but which is capable of polymerizing the monomer at room temperature within a reasonable period of time after removal of the inhibiting effect of oxygen.

Preferred monomers for use in anaerobic compositions are polymerizable acrylate esters, preferably having a molecular weight of at least about 130. Preferably at least a portion of the (meth)acrylate monomer is a di- or other poly(meth)acrylate ester. These poly-functional monomers produce cross-linked polymers, which serve as more effective and more durable sealants and adhesives.

The poly(meth)acrylate esters may be represented by the formula

wherein R² is a radical selected from the group consisting of hydrogen, halogen and alkyl of from 1 to about 4 carbon atoms; q is an integer equal to at least 1, and preferably equal to from 1 to about 4; and X is an organic radical containing at least two carbon atoms and having a total bonding capacity of q plus 1. With regard to the upper limit for the number of carbon atoms in "X", workable monomers exist at essentially any value. As a practical matter, however, a general upper limit is about 50 carbon atoms, preferably 30, and most preferably about 20.

For example, X can be an organic radical of the formula

O O

II II

— Y1-O— C— Z— C— O— Y2

wherein each of Y¹ and Y² is an organic radical, preferably a hydrocarbon group, containing at least 2 carbon atoms, and preferably from 2 to about 10 carbon atoms, and Z is an organic radical, preferably a hydrocarbon group, containing at least 1 carbon atom, and preferably from 2 to about 10 carbon atoms. Other classes of useful polyacrylate ester monomers are the isocyanate-monoacrylate reaction products described in U.S. Pat. No. 3,425,988 to Toback and Gorman, issued Feb. 4, 1969, and the reaction products of di- or tri-alkylamines (e.g., ethanolamines or propanolamines) with acrylic acids, such as are disclosed in French Pat. No. 1,581,361.

The most highly preferred (meth)acrylate which can be used in the compositions disclosed herein are poly(meth)acrylate esters which have the following general formula

wherein R¹ represents a radical from the group consisting of hydrogen, lower alkyl of from 1 to about 4 carbon atoms, hydroxyl alkyl of from 1 to about 4 carbon atoms, and

O

II -CH₂-O— C— C=CH₂

R2

R² is a radical selected from the group consisting of hydrogen, halogen, and lower alkyl of from 1 to about 4 carbon atoms; R³ is a radical selected from the group consisting of hydrogen, hydroxyl, and

O II -O— C— C=CH₂ I R2

m is an integer equal to at least 1, e.g. from 1 to about 15 or higher, and preferably from 1 to about 8 inclusive; n is an integer equal to at least 1, e.g., 1 to about 40 or more, and preferably between about 2 and about 10; and/? is one of the following: 0, 1.

Typical examples of poly(meth)acrylate esters corresponding to the above general formula are di-, tri- and tetraethyleneglycol dimethacrylate; dipropyleneglycol dimethacrylate; polyethyleneglycol dimethacrylate; polypropyleneglycol dimethacrylate; di (pentamethyleneglycol) dimethacrylate; tetraethyleneglycol diacrylate; tetraethyleneglycol di (chloroacrylate); diglycerol diacrylate; diglycerol tetramethacrylate; butyleneglycol dimethacrylate; neopentylglycol diacrylate; and tri- methylolpropane triacrylate. While di- and other poly(meth)acrylate esters, and particularly the poly(meth)acrylate esters described in the preceding paragraphs, have been found particularly desirable, monofunctional acrylate esters (esters containing one acrylate group ) also may be used. When dealing with monofunctional acrylate esters, it is highly preferable to use an ester which has a relatively polar alcoholic moiety. Such materials are less volatile than low molecular weight alkyl esters and, more important, the polar group tends to provide intermolecular attraction during and after cure, thus producing more desirable cure properties, as well as a more durable sealant or adhesive. Most preferably the polar group is selected from the group consisting of labile hydrogen, heterocyclic ring, hydroxy, amino, cyano, and halogen polar groups.

Typical examples of compounds within this category are cyclohexyl methacrylate, tetrahydrofurfuryl methacrylate, hydroxyethyl acrylate, hydroxypropyl methacrylate, t-butylaminoethyl methacrylate, cyanoethylacrylate, and chloroethyl methacrylate.

As indicated above the anaerobic compositions as discussed herein are prepared by mixing hydroperoxide initiator with one or more acrylate esters as described above. While the nature of the hydroperoxides is not critical to the broad concept of this invention, the general class of common hydroperoxides can be represented by the formula R⁴(OOH). wherein R⁴ generally is a hydrocarbon group containing up to about 18 carbon atoms, and z is 1, 2 or 3. Preferably z is 1 and R⁴ is an alkyl, aryl or aralkyl hydrocarbon group containing from about 3 to about 12 carbon atoms. Naturally R⁴ can contain any substituent or linkage , hydrocarbon or otherwise, which does not affect the hydroperoxide adversely for the purpose disclosed herein. Typical examples of such hydroperoxides are cumene hydroperoxide, tertiary butyl hydroperoxide, methylethylketone hydroperoxide, and hydroperoxides formed by oxygenation of various hydrocarbons such as methylbutene, cetane, and cyclohexane, and various ketones and ethers, including certain compounds represented by the general formula (2) above. The hydroperoxide initiators can be used within wide ranges, e.g. up to about 20% by weight of the composition. Most commonly, however, they comprise no more than about 10% by weight of the composition since above that level adverse effects on the strength and durability of the cured composition may be experienced. While in some instances lower amounts can be used, about 0.1% by weight of the composition is a common lower limit. Preferably the hydroperoxide initiator comprises from about 0.1% to about .5% by weight of the composition.

Accelerated anaeorbic curing compositions are particularly well suited for the packaging and dispensing receptacle of the present invention. As noted, highly active anaerobic compositions such as accelerated anaerobic curing compositions require packaging capable of preventing cure of the compositions while maintaining shelf stability. The highly reactive nature of these accelerated compositions, however, makes them difficult to store for extended periods in any conventional packaging. The packaging and dispenser receptacle of the present invention has proven useful in storage of such accelarated compositions.

Various chemical accelerators are known for catalyzing the anaerobic cure and reducing the cure speed for such compositions to provide accelerated anaerobic compositions. Aromatic amines are known to be particularly useful in such applications. A non-limiting list of examples of useful accelerators includes saccharin [benzoic sulfimide], tributylamine, NN-dimethyl-p-toluidine, N-Aminorhodanine, 1- acetyl-2-phenylhydrazine, benzenesulfonylhydrazide, dibenzenesulfonamide, and mixtures thereof. Additionally, the reaction of sulfuryldiisocyanate with acetic acid produces a disulfonamide that is a useful accelerator, and similar reactions of p- toluenesulfonyl isocyanate and chlorosulfonyl isocyanate can be used to prepare many compounds useful as active accelerators for the present invention.

Other ingredients also can be used if desired to impart commercially desirable properties to the composition. Typical examples of such ingredients are thickeners, plasticizers, dyes, adhesive agents and thixotropic agents. Of particular value are free radical inhibitors to provide added stability. Such materials can be used in such combinations and proportions as is desired, provided they do not affect adversely the anaerobic nature of the composition. While exceptions may exist in some cases, these materials generally do not comprise more than about 50 percent by weight of the total composition, and preferably not more than about 20 percent by weight of the composition.

Referring specifically to the Figures, a dispenser assembly in the form of receptacle 10 is provided, as shown in Figure 1, including container 20 and valve assembly 40. While it is to be generally understood that the present invention can be used generally to contain and/or dispense a composition, the present description and Figures are directed to the preferred embodiment in terms of a dispenser for containing and aerosol-dispensing a composition. Container 20 may be any suitable container capable of use in aerosol applications, i.e., any shape or construction so as to contain material under super-atmospheric internal pressures for aerosol dispensing. Preferably, container 20 is a metal canister constructed of materials such as steel, aluminum, nickel, tin, and the like, and combinations thereof. Such materials may be coated or plated with metal or plastic materials for strength, corrosion resistance, etc., as is known in the art. Most preferably, container 20 is a metal canister constructed of tin-plated steel.

As noted, receptacle 10 is designed for containing and aerosol dispensing of the contents thereof. As such, container 20 is capable of maintaining the contents thereof in a sealed, pressurized environment, as is well known in conventional aerosol applications. As seen in Figure 2, container 20 includes a container wall 25, defining a first cavity within container 20. Container wall 25 defines the shape of container 20, for example, as depicted in Figure 2, a canister including bottom 21 and top 22. Since container 20 is meant to maintain the contents thereof under pressure, and to provide sufficient oxygen to prevent an anaerobic curing composition from curing, container wall 25 is impervious to oxygen.

Container 20 includes an oxygen-containing stabilizer composition contained therein, for preventing the anaerobic curing composition contained within receptacle 10 from curing. As is known in aerosol dispensing applications, a propellant may be used to maintain a pressurized environment within container 20. In preferred applications, the oxygen-stabilizer composition is in the form of the propellant. For example, as depicted in Figure 2, container 20 includes propellant 29 contained therein. Propellant 29 may be any known propellant as used in aerosol dispensing applications capable of maintaining a suitable internal pressure within container 20, provided that propellant 29 includes oxygen. Preferably, propellant 29 is compressed air. Alternatively, propellant 29 may be any known compounds used as aerosol propellants, for example, gases such as nitrogen, helium, carbon dioxide, neon, argon, and the like; liquid hydrocarbons such as chlorinated and fluorinated hydrocarbons including dichlorodifluoromethane, trichlorofluoromethane, chloropentafluoromethane and dichlorotetrafluoroethane; and saturated and unsaturated hydrocarbons, generally containing up to about 5 carbon atoms, such as ethane, ethylene and propane. When such alternate propellants other than compressed air are used, sufficient oxygen must be incorporated therein to maintain prolonged stability and prevent curing of the anaerobic curing composition. Preferably, such compounds include oxygen incorporated therein in an amount greater than about 10% by weight, and more preferably greater than about 20% by weight.

Receptacle 10 further includes a second container in the form of bladder 30 contained within container 20. Bladder 30 includes an oxygen permeable wall 35 which defines a second cavity, and is constructed to contain an anaerobic curing composition 39 therein. Preferably, bladder 30 is constructed of a polymeric material, such as high density polyethylene, low density polyethylene, polypropylene, fluorinated polymers, and the like, and mixtures thereof. In most preferred applications, bladder 30 is construted of high density polyethylene (HDPE), as this polymeric material has demonstrated proper oxygen permeability for maintaining the sufficient oxygen content with the anaerobic curing composition to prevent curing thereof. Other polymers, however, are contemplated for use in the present invention, provided their oxygen permeability is similar to or higher than that of HDPE. Bladder 30 is preferably constructed of pliable material capable of deforming in shape when pressure is exerted on bladder wall 35, for example, a pliable high density polyethylene bag.

Bladder 30 is contained within container 20, defining a gap or space such as gap 28 between container wall 25 and bladder wall 35, with propellant 29 contained within gap 28 to define a sealed, pressurized region. For example, bladder 30 may be a pliable polymeric bag attached to and suspended from top 22 at opening 23 of container 20, with gap 28 and propellant 29 surrounding bladder 30, as seen in Figure 2. As such, oxygen present in propellant 29 permeates through the oxygen permeable wall 35 of bladder 30, thereby providing constant oxygen contact with anaerobic curing composition 39 within bladder 30, to prevent curing thereof.

Receptacle 10 may further include valve assembly 40 for dispensing the contents of receptacle 10. As depicted in the Figures, valve assembly 40 is provided, for example, at the top 22 of container 20 at opening 23. Valve assembly 40 is attached to container 20 in a sealed engagement to maintain the contents of receptacle 10 under pressure. Valve assembly 40 is in registry with the second cavity within bladder 30 in a sealed engagement about the opening 23 of container 20, providing means for meterable fluid communication between anaerobic curing composition 39 contained within bladder 30 and the outside environment.

Valve assembly 40 may be any type of valve assembly as known for use in aerosol dispenser applications. For example, as seen in Figure 2, valve assembly 40 includes grommet 42 and nozzle 44. Grommet 42 is preferably constructed of an elastomeric material, such as rubber, in order to provide flexibility and maintain a sealed engagement. Nozzle 44 is preferably constructed of a rigid material, such as polypropylene. Valve assembly 40 further includes opening 47 extending through grommet 42 and nozzle 44. When valve assembly 40 is in a closed position, opening 47 is sealed, thereby maintaining the contents of receptacle 10 underpressure. When valve assembly 40 is in an open position, opening 47 provides fluid communication between the inside of receptacle 10 and the outside environment, thereby providing means for fluid flow therebetween.

In use, container 20 is provided including an oxygen-stabilizer composition as propellant 29 therein. Anaerobic curing composition 39 is provided in bladder 30.

Bladder 30 is further contained within container 20, with gap 28 present between container wall 25 and bladder wall 35 such that propellant 29 surrounds bladder 30 within container 20. Valve assembly 40 is provided at top 22 of container 20. Valve assembly 40 is attached to bladder 30, providing means for fluid communication between anaerobic curing composition 39 contained within bladder 30 and the outside environment.

Container 20 is sealed to the outside environment, and is pressurized through propellant 29. Oxygen within propellant 29 permeates through bladder wall 35, thereby providing a constant supply of oxygen to anaerobic curing composition 39 which is present within bladder 30. Accordingly, anaerobic curing composition 39 is prevented from curing and is maintained in fluid form.

Propellant 29 exerts a constant pressure on bladder 30 within container 20. Valve assembly 10 seals the contents of bladder 30, preventing flow thereof. When nozzle

44 of valve assembly 40 is activated, the seal between bladder 30 and the outside environment is removed with the internal pressure maintained within container 20 by propellant 29 exerting pressure on bladder 30, and the anaerobic curing composition 39 contained within bladder 30 flows through opening 47. Accordingly, anaerobic curing composition 39 is released in a metered amount from receptacle 10 for use in any known application.

In addition to the above named inert propellants, sufficient oxygen must be incorporated in the aerosol container to provide the requisite stability of the anaerobic composition. Stable compositions can be prepared with partial pressures of oxygen in the container as low as 0J lb. per square inch absolute. The upper limit is basically one of convenience, since oxygen theoretically can be used as the sole inert propellant. This generally is not desirable since it creates localized high concentrations of oxygen, which can create a hazard. A practical upper limit for the oxygen partial pressure is about 15 lbs. per square inch or about one-third of the total pressure in the interior of the aerosol container, whichever is higher. A preferred operating range for the oxygen is at a partial pressure from about 1 to about 10 lbs. per square inch, and most preferably from about 2 and about 5 lbs. per square inch.

The total internal pressure in the container is primarily a question of safety and convenience. As a general rule, however, internal pressures for such containers do not exceed about 160 pounds per square inch gauge, and preferably do not exceed about 75 pounds per square inch gauge. Minimum internal pressure again is a question of convenience, but should generally be at least about 5 pounds per square inch gauge, and preferably 15 pounds per square inch gauge, to permit dispensing.

To dispense the anaerobic composition in liquid aerosol form, the viscosity of the composition should not be excessively high. As a general rule, viscosities below 1,000,000 centipoise should be used. Desirably, the viscosity should be from about 1 to about 500,000 centipoise and most desirably from about 10 to about 100,000 centipoise. In these ranges, additional stability benefits are gained due to the fact that oxygen can more easily penetrate into the anaerobic compositions.

Accelerated anaerobic curing compositions, such as rapidly curing adhesives, are particularly well suited for the packaging receptacles of the present invention. Such accelerated anaerobic adhesives are difficult to stabilize in conventional anaerobic packaging, due to the limitations on the permeability of the container wall. For example, conventional tube-type dispensers do not permit sufficient exposure to oxygen through the wall of the tube in order to maintain adequate stability of the composition over prolonged periods of time. Thus, the shelf life for storage of such accelerated anaerobic curing compositions is very limited. Moreover, aerosol canisters such as disclosed in U.S. Patent No. 3,736,260, discussed herein, can create explosive mixtures within the container, due to the high pressurized propellant which includes oxygen being mixed directly with the highly reactive accelerated anaerobic curing composition.

The present invention proves very effective in safely packaging such accelerated anaerobic curing compositions, in that the pressure maintained within the container allows for increased oxygen exposure to the composition, and the bladder wall presents an effective barrier between the composition and the propellant, thus eliminating potentially explosive mixtures.

Reference is now made to the following examples.

EXAMPLE 1

Example 1 demonstrates an anaerobic curing composition in the form of a flange sealant, stored in a conventional aerosol receptacle using an impervious bladder.

An anaerobic curing flange sealant was prepared incorporating the following composition:

The anaerobic flange sealant was contained in an oxygen impervious nylon/HDPE bag as a bladder. The bladder was contained in a tin-plated steel canister, including a valve stem. The canister was sealed and pressurized to 120 psi with compressed air as a propellant.

To simulate shelf storage conditions, the canister was heat-aged at 38 C for 2 weeks. After 2 weeks of heat aging at 38 C, the anaerobic flange sealant composition was entirely cured within the aerosol receptacle, providing a product which was not useful.

EXAMPLE 2 Example 2 demonstrates the utility of the present invention using the anaerobic curing composition in the form of a flange sealant as in Example 1, but stored in an aerosol receptacle using an oxygen permeable bladder according to the present invention.

An anaerobic flange sealant composition was prepared according to the formulation of Example 1. The composition was contained in an oxygen permeable HDPE bag as a bladder. The bladder was contained in a tin-plated steel canister, including a valve stem. The canister was sealed and pressurized to 120 psi with compressed air as a propellant.

Prior to aging, the viscosity of the composition was determined to be 37,433 centipoise (cps). To simulate shelf storage conditions, the canister was heat-aged at 38 C for 2 weeks. After 2 weeks of heat aging at 38 C, the anaerobic flange sealant composition demonstrated no evidence of instability, and maintained a viscosity of 37,433 cps. After 4 weeks of heat aging at 38 C, the anaerobic flange sealant composition continued to demonstrate no evidence of instability, with a viscosity of 37,747 cps. After 8 weeks of heat aging at 38 C, the anaerobic flange sealant composition remained fluid within the aerosol receptacle.

EXAMPLE 3

Example 3 demonstrates another anaerobic curing composition in the form of a flange sealant, stored in a conventional aerosol receptacle using an impervious bladder.

The anaerobic curing flange sealant of Example 3 was prepared incorporating the following composition:

To simulate shelf storage conditions, the canister was heat-aged at 50 C for 4 weeks, demonstrating an equivalent shelf storage of 1 year at room temperature (23

C). After 4 weeks of heat aging at 50 C, the anaerobic flange sealant composition was entirely cured within the aerosol receptacle, providing a product which was not useful.

EXAMPLE 4

Example 4 demonstrates the utility of the present invention using the anaerobic curing composition in the form of a flange sealant as in Example 3, but stored in an aerosol receptacle using an oxygen permeable bladder according to the present invention.

An anaerobic flange sealant composition was prepared according to the formulation of Example 3. The composition was contained in an oxygen permeable HDPE bag as a bladder. The bladder was contained in a tin-plated steel canister, including a valve stem. The canister was sealed and pressurized to 120 psi with compressed air as a propellant.

To simulate shelf storage conditions, the canister was heat-aged at 50 C for 4 weeks. After 4 weeks of heat aging at 50 C, the anaerobic flange sealant composition demonstrated no evidence of instability, and remained fluid in the aerosol receptacle. After 8 weeks of heat aging at 50 C, the anaerobic flange sealant composition still remained fluid within the aerosol receptacle.

EXAMPLE 5

Example 5 demonstrates yet another anaerobic curing composition in the form of a flange sealant, stored in a conventional aerosol receptacle using an impervious bladder.

The anaerobic curing flange sealant of Example 5 was prepared incorporating the following composition:

To simulate shelf storage conditions, the canister was heat-aged at 50 C for 4 weeks, demonstrating an equivalent shelf storage of 1 year at room temperature (23 C). After 4 weeks of heat aging at 50 C, the anaerobic flange sealant composition was entirely cured within the aerosol receptacle, providing a product which was not useful.

EXAMPLE 6

Example 6 demonstrates the utility of the present invention using the anaerobic curing composition in the form of a flange sealant as in Example 5, but stored in an aerosol receptacle using an oxygen permeable bladder according to the present invention. An anaerobic flange sealant composition was prepared according to the formulation of Example 5. The composition was contained in an oxygen permeable HDPE bag as a bladder. The bladder was contained in a tin-plated steel canister, including a valve stem. The canister was sealed and pressurized to 120 psi with compressed air as a propellant.

EXAMPLE 7

Example 7 demonstrates an accelerated anaerobic curing composition in the form of an impregnation sealant which is known to rapidly cure.

The accelerated anaerobic curing composition of Example 7 was prepared according to the following composition:

The freshly mixed accelerated anaerobic curing composition was placed in a 10 ounce open HDPE beaker at room temperature (23 C). The composition cured to a gel state within 5.5 hours.

The freshly mixed accelerated anaerobic curing composition was also placed in a

2 ml open glass test tube at 55 C. The composition cured to a gel state within 16 minutes.

These curing rates demonstrate the instability and the rapid curing of this accelerated anaerobic curing composition.

EXAMPLE 8

Example 8 demonstrates the accelerated anaerobic curing composition of Example 7, stored in a conventional aerosol receptacle using an impervious bladder.

The accelerated anaerobic curing composition of Example 7 was contained in a 7.25 ounce oxygen-impervious nylon pack as a bladder. The bladder was contained in a tin-plated steel canister, including a valve stem. The canister was sealed and pressurized to 120 psi with compressed air as a propellant.

The canister was maintained at room temperature. The accelerated anaerobic curing composition exothermically cured to a gel state within 24 hours.

EXAMPLE 9 Example 9 demonstrates the utility of the present invention using the accelerated anaerobic curing composition of Example 7, stored in an aerosol receptacle using an oxygen permeable bladder according to the present invention.

The accelerated anaerobic curing composition of Example 7 was contained in a 7.25 ounce oxygen-permeable HDPE bag as a bladder. The bladder was contained in a tin-plated steel canister, including a valve stem. The canister was sealed and pressurized to 120 psi with compressed air as a propellant.

The canister was maintained at room temperature. After 11 weeks at room temperature, the accelerated anaerobic curing composition still remained fluid within the aerosol receptacle. Furthermore, the thus aged product was applied to 3/8 x 16 (grade 5) metal fasteners. After 24 hours at room temperature, the anaerobic curing composition cured, thus providing a useful accelerated curable composition.

Claims

WHAT IS CLAIMED IS:

1. A dispenser assembly comprising: a first container defining a first cavity and an opening; an oxygen-permeable, collapsible second container supported within said first cavity and defining a second cavity; said first and second containers defining a sealed pressurized region therebetween; a valve assembly in registry with said second cavity and in sealed engagement with said second container at said opening; said valve assembly providing meterable fluid communication with said second cavity; a pressurized oxygen-containing propellant within said pressurized region; an oxygen-stabilized flowable material contained within said second collapsible container; wherein upon opening of said valve assembly, said propellant urges said flowable material through said valve assembly.

2. A dispenser assembly as in claim 1 wherein said first container is a metal canister.

3. A dispenser assembly as in claim 1 wherein said second container is made from high density polyethylene.

4. A dispenser assembly as in claim 1 wherein said second container is made from a material selected from the group consisting of low density polyethylene, fluorinated polymers, polypropylene, and mixtures thereof.

5. A dispenser assembly as in claim 1 wherein said propellant is compressed air or a gaseous hydrocarbon/air mixture.

6. A dispenser assembly as in claim 1 wherein said oxygen-stabilized composition is an anaerobic adhesive.

7. An apparatus for packaging oxygen-stabilized compositions comprising: a pressurable, sealed container including a container wall being substantially impervious to oxygen; a collapsible bladder having an oxygen-permeable wall for containing an oxygen- stabilized composition therein, said bladder contained within said container, said bladder wall and said container wall defining a space therebetween; and an oxygen-containing stabilizer composition contained within said space between said bladder wall and said container wall; wherein oxygen from said stabilizer composition is permeable through said bladder wall to effectuate stabilization of said oxygen-stabilized composition.

8. An apparatus as in claim 7, further including a valve assembly for dispensing said oxygen-stabilized composition.

9. An apparatus as in claim 7, wherein said container is a metal canister.

10. An apparatus as in claim 7, wherein said bladder is high density polyethylene.

11. An apparatus as in claim 7, wherein said stabilizer composition is compressed air.

12. An apparatus as in claim 7, wherein said stabilizer composition is a hydrocarbon gas mixed with oxygen.

13. An apparatus for dispensing an oxygen-stabilized composition comprising: a pressurized, sealed container having an oxygen impervious wall; an oxygen-containing propellant contained within said sealed container; a collapsible bladder having an oxygen-permeable wall, said bladder containing an oxygen-stabilized composition therein, said bladder being suspended within said sealed container; and a valve assembly in fluid communication with said bladder for dispensing said oxygen-stabilized composition; wherein oxygen from said propellant permeates through said bladder wall to effectuate stabilization of said oxygen-stabilized composition.

14. An apparatus as in claim 13, wherein said valve assembly includes a grommet, and a valve stem.

15. A dispenser assembly comprising: a first container defining a first cavity and an opening; a collapsible second container supported within said first cavity and defining a second cavity, said second container being oxygen permeable; said first and second containers defining a sealed pressurizable region therebetween; and a valve assembly in registry with said second cavity and in sealed engagement with said second container at said first opening, said valve assembly providing meterable fluid communication with said second cavity.

16. A dispenser assembly as in claim 15, further including a compressible propellant within said sealed pressurizable region.

17. A dispenser assembly as in claim 16, further including a flowable material within said second cavity.

18. A dispenser assembly as in claim 17, wherein said compressible propellant is permeably through said second container.

19. A dispenser assembly as in claim 18, wherein said compressible propellant interacts within said flowable material in said second container.

20. A dispenser assembly as in claim 19, wherein said compressible propellant stabilizes said flowable material.