Method and apparatus for resealing containers of curable compositions

Abstract

The present invention provides a method for resealing an opened container of a curable material, the method comprising the steps of: a. providing opened container of curable material having a sealable

Description

This invention relates to a method and apparatus for resealing containers of curable compositions, in order to extend pot life of curable compositions which may be curable due to the influence of external factors such as atmospheric / moisture. Background A wide range of compositions, such as compositions used in the building industry are designed to be curable. My curable has meant that upon exposure to the or moisture a chemical transformation takes place in the product which enables it to transform into a finished state. Common examples are silicone sealants, urethane adhesives and some paints, such as urethane paints. Related to this is a more indirect form of curing where a solvent such as water or a hydrocarbon evaporates over time. Some curable products are provided in containers which are resealable to one degree or another but there is a general need for an ability to reseal product containers, particularly for curable compositions. Due to the wide variety of such compositions, such as in the building industry, any resealing mechanism should be versatile and adaptable. Most preferably any resealing mechanism would also retard or hinder any curing process so is to put up along the so termed “open time” only curable products what it has access to a curing mechanism. A further need is that such methods and apparatus for extending the life of opened curable products should be constructed of environmentally acceptable, such as biodegradable, or at least passive components. Relevant prior disclosures include CN208485031U which discloses a paint kettle with a replaceable lid and GB2456550A which discloses a flexible resealable bag for holding paint. The present invention addresses the aforementioned needs. The present invention The present invention in its various aspects is as set out in the appended claims. The present invention provides a method for resealing an opened container of a curable material, the method comprising the steps of: a. providing opened container of curable material having an opening; b. providing a resilient elastomeric sealing device consisting of; i. a flexible ring defining an aperture of such dimensions that upon resilient extension of the flexible ring and releasing of said ring the ring seals around said sealable aperture; ii. a membrane encompassing and integral with the flexible ring and spanning the face of the ring. c. Resiliently extending the flexible ring and placing it around the opening; d. releasing the ring such that the ring contacts and seals against a perimeter of the opening, such that the membrane then covers the sealable aperture. The method of the present invention provides a fast, convenient and efficient means for sealing containers once they have been open. For example, a paint can, a mastic sealant tube or other container of a curable composition. The method takes the sealing device, places it over an open container by stretching the elastically deformable device, placing it over the opening and then the device springs back as it is resilient, so as to seal the aperture around the edges. This is therefore a convenient means to place a seal around the open top of a paint can to stop the ingress of moisture such as may cure a urethane paint, or to hinder a loss of solvent, so as to cure a water-based paint, or a solvent-based paint. Similarly, the device may be configured for sealing around a nozzle of a mastic cartridge, or around the body of a mastic cartridge. The method of the present invention may provide that the resilient elastomeric sealing device comprises silicone rubber. This is particularly beneficial as the low surface energy of silicon rubber, such as a silicon rubber made of poly dimethyl siloxane, means that most paints do not adhere to the sealing device and therefore the sealing device can be readily removed, even if the sealing device is placed around the rim of a paint can where painters dripped down the side (and therefore will cure and set likely before the seal is are removed). This benefit is most clear when the sealing device consists of siloxane based silicon rubber,. The siloxane based silicon rubber may be poly dimethyl siloxane. The poly dimethyl siloxane is preferably a cross-linked poly do meet our siloxane, as this gives improved resilience and reduced likelihood of splitting upon stretching, i.e. resilient deformation. The method of the present invention may provide that the membrane is between one and five millimetres thick. For practical use the present invention requires that the membrane is in this thickness range as thinner material is easily pierced and split and is therefore ineffective in everyday use, particularly when dealing with curable compositions in the building trade were sharp and abrasive surfaces and items proliferate. The thickness is preferably in the range 1 to 2 mm, this provides a compromise between robustness, as mentioned above, and the force required for deformation, as a particularly thick material is hard to stretch more than a few percent whereas in this thickness range stretching in the order of 5 to 30% is practicable, although not significantly further. The method of the present invention may provide that said membrane and / or said flexible ring is metallised, this is beneficial as many curable compositions act in the presence of oxygen and a metallised coating acts as a barrier to gas permeability and therefore provides a more effective seal. The seal is preferably metallised by means of providing an aluminium coating. Particularly a coating on an outer surface of a previously prepared sealing device, more preferably a poly dimethyl siloxane based sealing device. This provides the most versatile and effective combination of features for a wide range of curable compositions. The method of the present invention may provide that said sealing device is coated with a viscous liquid composition for sealing the ring to a perimeter of the opened container. Placing a viscous liquid coating on the sealing device, and therefore forming part of the sealing device, enables small imperfections in a surface to be sealed thus improving the sealing effectiveness of the method and device of the present invention. The viscous liquid is preferably coated on the inside of the sealing device. The viscous liquid is very preferably not coated on the outside of the sealing device as this makes the device too slippy and removal of the device can be problematic. The viscous liquid is preferably a silicon oil, such as a poly dimethyl siloxane based silicon oil. This particular oil is particularly preferable in combination with a poly dime ethyl siloxane elastomer of the sealing device as there is no negative interactions so as to degrade the integrity of the polymer over time whilst enabling effective “wetting” of the liquid onto the solid and therefore an even coating is obtained. Use of hydrocarbon-based liquids is less preferable, particularly with a siloxane based elastomer since this can interact with low surface energy materials (such as hydrocarbon-based paints) and interfere with the curing capacity. Siloxane based means that the predominant (such as greater than 90%) repeat unit in the polymer, which is preferably cross-linked, is polydialkyl siloxane, most preferably poly dimethyl siloxane. The method of the present invention may provide that said ring is of greater thickness than said membrane. Whilst the sealing ring can be simply offset from the membrane, such as being moulded to be perpendicular to it and therefore providing a discontinuity for improved sealing and therefore defining a separate ring element ring element is preferably thicker than the membrane, this makes it more resilient to splitting or puncturing as the ring, in use, contact the periphery of the aperture of the container of the curable sealant (such as the tin of paint) or the mastic tube. The method of the present invention may provide that said ring is circular in crosssection. This is the more effective geometry for sealing a variety of typical containers of durable materials. Such as tins of paint and mastic tubes. The method of the present invention may provide that said sealing device in whole or in part is transparent. This is particularly for as it enables the user to see through the sealing device and see whether a curable sealant sealed by the device or method of the present invention is still, for example, fluid, evidencing that the method or device has been effective. This is particular useful after prolonged storage. The method of the present invention may provide that the sealing device is transparent in said membrane portion. This is particularly useful since the membrane is the portion preferably viewed through, whereas the ring is preferably opaque as this makes it more visible and facilitates visual identification and correct placement. The method of the present invention may provide that the membrane, in use, is in tension across said ring. The method of the present invention may provide that the membrane is in tension across said ring in the unused state, such that in use further stretching and tension occurs. This is achieved by moulding the original device in this configuration and has the advantage that as the membrane is pulled down over an aperture of a container of sealant the membrane will push against the edge of the sealant container providing secondary seal in addition to the seal achieved by the outer ring as that is released against the periphery of the aperture. The method of the present invention may provide that said membrane extends perpendicular to the plane of the ring, such as in a dome. In some circumstances this has been found to be an official over the planar membrane since stretching and pushing a membrane over the edges of a container can often puncture the membrane, even if the membrane is as thick as 1 to 2 mm, although membrane for a 5 mm thick is rarely punctured. The method of the present invention may provide that said ring or membrane includes a water sequestering agent. Whilst the method and sealing device of the present invention as previously described passively prevents curing of a credible composition, such as by preventing the ingress of moisture in this preferred adaptation of the invention the membrane has a capacity to actively sequester water and therefore to provide a dry atmosphere, such as in a space between the sealing device and the curable composition. The water sequestering agent may be present as a solid, such as mixed in with the elastomer in preparing a device of the invention and as such it is preferably present on, in use, in a side of the device. The method of the present invention may provide that only said membrane includes said water sequestering agent. This is particularly beneficial as the sequestering agent is not particular required on the ring portion, may tend to reduce the elasticity of an elastomer in which it is incorporated and also provide surface roughness. Therefore, for ease of preparation, i.e. manufacture, of the sealing device of the present invention the sequestering agent is only present on the membrane. A variety of sequestering agents may be used but it has been found that referred sequestering agents are selected from one or more of: Silica Gel, Activated Alumina, Calcium Chloride, Molecular Sieve, Bentonite Clay, Montmorillonite Clay, Anhydrous Calcium Sulphate and Calcium Oxide. The most preferred sequestering agent is calcium oxide as this is relatively basic and is advantageous in neutralising acid, such as produced during the curing of silicon adhesives, as may be present, for example in a tube of mastic. In addition, curing of some curable pain compositions can be retarded in a more alkaline environment. While such compositions are not generally suitable for contacting the skin devices of the present invention are not intended to contact the skin, any more than is present in an otherwise construction environment where solvents, paint et cetera are being used. The method of the present invention includes a method were in the method is carried out on a water curable composition, particularly in combination with the aforementioned water sequestrant. The method of the present invention may provide that said sequestering agent is present on one side of the membrane, configured for, in use being placed proximate to said sealable aperture. This is beneficial as mentioned previously. The method of the present invention may provide that the sealing device comprises a hydration indicator. As previously mentioned, the presence of water may act as a curate for paints, such as your offence, and sealants, such as silicon sealants and as such the presence of a hydration indicator indicates whether the sealant is likely to cure (i.e. go off) in the container. By and large most curable compositions curable by moisture are tolerant to a certain amount of moisture before they loose stability and hence the hydration indicator is an external signal that the composition is too damp. The method and apparatus of the present invention preferably provides that the hydration indicator is selected from one or more of: Copper(ll) Sulfate (CuS04 • 5H2O), Cobalt(ll) Chloride (CoCI2), Anhydrous Copper(ll) Chloride (CuCI2), Cobalt(ll) Sulfate (CoSO4), Cobalt(ll) Nitrate (Co(NO3)2), Cobalt(ll) Acetate (Co(CH3COO)2), Anhydrous Calcium Chloride (CaCI2), Phenolphthalein. The preferred hydration indicator is anhydrous calcium chloride as this can act both as the hydration indicator and the visual indicator of hydration and alternative preferred hydration indicator is Phenolphthalein as this can be admixed into the resilient elastomeric material of the sealing device during manufacture. The method of the present invention may provide that said side of the membrane remote from said sealable aperture is metallised. This is for the reasons as mentioned previously. The method of the present invention may provide that said ring or membrane includes a volatile solvent agent. A further method of curing of curable compositions is the loss of a volatile solvent to agent, for the purposes of the present invention a curable composition can include such curable compositions but very preferably excludes them and focuses purely on curable compositions curable by means of an external chemical agent, as this provides a modifying trigger and a more effective use of the present invention. Nevertheless, the presence of a volatile solvent in the sealing device of the present invention improves the method since, and this is an important feature, the volatile solvent is preferably a different volatile solvent than used in the curable composition, this means that the partial pressures of the different compositions (solvent in device, solvent in composition) mean that the vapour pressure of both the suppressed and therefore the rate of evaporation of both is suppressed. The volatile solvent for use in the present invention is preferably is selected from one or more of: Ethanol (Ethyl Alcohol), Isopropyl Alcohol (Isopropanol), Acetone, Methyl Acetate, Ethyl Lactate, D-Limonene, Terpenes (e.g., Pine Oil), Propylene Carbonate, Dimethyl Carbonate, Hexanediol Diacrylate (HDDA). The preferred volatile solvent agent is isopropyl alcohol. This is relatively volatile and enhances the aforementioned benefit. The method of the present invention may provide that the sealing device comprises a pH indicator configured to change colour from a neutral, unused products, pH to an acidic pH. Curable compositions can be cured due to a change in pH. Or may gave rise to a change in pH and punk curing (such as silicon sealants) therefore the presence of a pH indicator enables, for similar reasons mentioned previously for the moisture indicator, the potential shelf life of a curable composition and is particularly useful when dealing with use of the method of the present invention with sealant cartridges, particularly silicon mastic sealant cartridges. Drawings The present invention is illustrated by means of the following drawings in which like features are designated with like numerals. The figures provide: figure 1 shows a cross-section (circular in plan) of a planar sealing device of the present invention; figure 2 shows a cross-section (circular in plan) of a bowed sealing device of the present invention; figure 3 shows a cross-section (circular in plan) of a domed ceiling device of the present invention; figure 4 shows a cross-section (circular in plan) of a cylindrical sealing device of the present invention, the cylinder having an end; figure 5 shows in cross-section the interaction between a flexible ring of the present invention with a wall of a sealable container is evident when practising a method of the present invention; figure 6 shows in cross-section interaction between a flexible ring of the present invention and the further interaction between the membrane of the present invention with a sealable container is evident when practising a method of the present invention; figure 7 shows a perspective view of the elastomeric sealing device, i.e. the sealing device, as figure 4 to illustrate the three-dimensional appearance; figure 8 shows a side view of the elastomeric sealing device, sealing device, of the present invention in use in conjunction with a representative container, such as containing a curable composition; and figure 9 shows a cross-section through a membrane on the present invention in which various optional features of the structure making up the membrane are shown. The features of the drawings are listed as follows: 10 - sealing device of the present invention having planar membrane; 20 - sealing device of the present invention having bowed membrane; 30 - sealing device of the present invention having domed membrane; 40 - sealing device of the present invention having cylindrical membrane; 50 - interaction of sealing device with sealable aperture of container; 60 - additional interaction of sealing device with sealable aperture of container; 100 - flexible ring; 200, 220, 230, 240, 250 - flexible membrane; 240 - side wall of cylindrical membrane; 244 - end wall of cylindrical membrane; 248 - moulded corner of cylindrical membrane; 250, 252 - wall of flexible membrane; 254 - outer wall of flexible membrane; 256 - inner wall of flexible membrane; 260 - metallised layer of flexible membrane, optional; 262 - liquid layer of membrane, optional; 264 - water sequestering agent, particle; 266 - volatile solvent agent, notional presence; 268 - water sequestering particle comprising hydration indicator; 269 - particle in communication with inner wall of membrane; 300 - container wall, such as container of durable material; 310 - outer wall of sealable container; 320 - aperture space of sealable container, such as enabling access to curable material contained within the sealable container; 330 - contact area between sealing device, flexible ring and container wall and 340 - further contact area between sealing device, membrane, and container wall. Detailed description The present invention provides an elastomeric sealing device and the method of using the device. Figures 1,2, 3, 4 and 9 show features of the device. Figure 1 shows a planar elastomeric sealing device 10, comprising a flexible ring 100 and they membrane 200. In an undeformed state the ring is a circular ring and the membrane extends across the ring to form a planar face. The ring is between three and five millimetres in radius and the membrane is between one and two millimetres in thickness (in this figure showing a preferred example). Figure 2 shows a bowed elastomeric sealing device 20 comprising the flexible ring 100 and as formed during production a membrane 220 which is bowed relative to the flexible ring when the device in an undeformed state. Figure 3 shows a domed elastomeric sealing device 30 comprising a flexible ring 100 and as formed during production a membrane to 30 which is domed relative to the flexible ring when the device is in an undeformed state. Figure 4 shows 50 a cylindrical elastomeric sealing device 40 comprising a flexible ring 100 and as formed during production a membrane 210, having side walls 240, and Walt to 44 and moulded comers 248 such that the structure being formed during production as the form shown in figure 7. The vertical line on the left-hand side being a construction line to illustrate the geometry in an otherwise unshaded figure. Figure 5 shows 60 an elastomeric sealing device (such as 30, 40) of the present invention after application by the method of the present invention to a sealable aperture of a container, such as a container holding a curable material. As can be seen ring 100 is configured so that upon resilient expansion and placing over an aperture at 320 it resides against an external wall 310 of a container 300 so as to form a seal and thereby preserve the integrity of the curable material against atmospheric ingress, so as to carry out curing (or alternatively to hinder the escape of volatiles such as to also carry out a curing process). As can be seen in this figure the walls of the membrane adjacent to the ring do not necessarily contact the wall 310 of the container. Figure 6 shows elastomeric sealing device such as 10, 20, which is configured without a cylindrical wall to 40 or applied in such a manner that the sealing device is not play sufficiently far on the container that the membrane will abort the rim of the container. Therefore, with the planar or bowed sealing device the membrane to 50 abuts the rim of the container 340 to provide an additional seal to the seal forms were the ring 100 watts the wall of the container 310.320. This figure could also be interpreted in the scope of the sealing member having said cylindrical wall in which the moulded corner 248 of the membrane can abut the edge of the container at 340 is an alternative method to form an additional seal. A side view of the container with the sealing device (a.k.a. sealant device) in place such as achieved by the method of the present invention using the sealing device of a present invention is shown in figure 8. Figure 7 shows a perspective view of the sealing device 40 shown in figure 4 to illustrate the cylindrical, and Nature of the device, overview, from below (not shown in this figure would show an opening encompassed by the ring 100. Figure 9 shows 250 a cross-section through a membrane 252, which is illustrative of a membrane 200, 210, 220, 230, 240, 250 shown elsewhere. This view is intended to illustrate a composition of the membrane. Each of these features now described can be used individually or in combination with the other features mentioned with respect this figure. The membrane 252 as an outer wall 254 and an inner wall 256. The membrane 252 may have a metallised layer 260, such as an aluminium layer, this is shown as forming the outermost layer, hence wall, of the membrane 252 membrane 252 may have an innermost layer 262, being a liquid (and not therefore a wall) coating in a wall 256 of a sealing agent, such as a paraffin wax. The membrane may comprise, in addition to the elastomeric material particles having specific functions. These particles may be present in the bulk of the membrane 264, 266, 268, or may reside adjacent or forming part of the walls of the membrane 269. These particles are illustrative of materials having a functional effect such as a water sequestering particle 264, and a water sequestering particle 268 comprising an indicating agent. These particles may comprise a volatile solvent agent 266 which may be present as an identifiable unit may simply be infused into the elastomeric material of the sealing device. For clarity, as will be evident from the various figures whilst many of them show a cross-section the material of the cross-section is not shown in the conventional shaded format predominantly for clarity so it should be understood that these 5 drawings could be shaded to illustrate that they are a cross-section so the reader is therefore informed of this.

Claims

1. A method for resealing an opened container of a curable material, the method comprising the steps of:a. providing opened container of curable material having a sealable aperture;b. providing a resilient elastomeric sealing device consisting of;i. a flexible ring defining an aperture of such dimensions that upon resilient extension of the flexible ring and releasing of said ring the ring seals around said sealable aperture;ii. a membrane encompassing and integral with the flexible ring and spanning the face of the ring.c. resiliently extending the flexible ring and placing it around the sealable aperture;d. releasing the ring such that the ring contacts and seals against a perimeter of the sealable aperture, such that the membrane then covers the sealable aperture.

2. The method of claim 1 wherein the resilient elastomeric sealing device comprises silicone rubber, preferably consisting of polydimethyl siloxane based silicon rubber.

3. The method of claim 1 or claim 2 were in said membrane is between one and five millimetres thick.

4. The method of any preceding claim wherein said membrane and / or said flexible ring is metallised.

5. The method of any preceding claim wherein said sealing device is coated with a viscous liquid composition for sealing the ring to a perimeter.

6. The method of any preceding claim wherein said ring is of greater thickness than said membrane.

7. The method of any preceding claim wherein said ring is circular in crosssection.

8. The method of any preceding claim wherein said sealing device in whole or in part is transparent.

9. The method of claim 8 wherein said sealing device is transparent in said membrane portion.

10. The method of any preceding claim wherein said membrane extends perpendicular to the plane of the ring.11 .The method of any of claims 1 to 9 wherein said membrane is in tension across said ring.

12. The method of any preceding claim wherein said ring or membrane includes a water sequestering agent.

13. The method of claim 12 wherein only said membrane includes said sequestering agent.

14. The method of claim 13 wherein said water sequestering agent is selected from one or more of: Silica Gel, Activated Alumina, Calcium Chloride, Molecular Sieve, Bentonite Clay, Montmorillonite Clay, Anhydrous Calcium Sulfate and Calcium Oxide.

15. The method of claim 14 wherein said sequestering agent is present on one side of the membrane configured for, in use, being placed proximate to said sealable aperture.

16. The method of any of claims 12 to 15 wherein the sealing device comprises a hydration indicator.

17. The method of claim you will 16 wherein the hydration indicator is selected from one or more of: Copper(ll) Sulfate (CuS04 ■ 5H2O), Cobalt(ll) Chloride (CoCI2), Anhydrous Copper(ll) Chloride (CuCI2), Cobalt(ll) Sulfate (CoSO4), Cobalt(ll) Nitrate (Co(NO3)2), Cobalt(ll) Acetate (Co(CH3COO)2), Anhydrous Calcium Chloride (CaCI2), Phenolphthalein.

18. The method of claim 15 were said side of the membrane remote from said sealable aperture is metallised.

19. The method of any preceding claim wherein said ring or membrane includes a volatile solvent agent.

20. The method of claim 17 wherein said volatile solvent is selected from one or more of: Ethanol (Ethyl Alcohol), Isopropyl Alcohol (Isopropanol), Acetone, Methyl Acetate, Ethyl Lactate, D-Limonene, Terpenes (e.g., Pine Oil), Propylene Carbonate, Dimethyl Carbonate, Hexanediol Diacrylate (HDDA).21 .The method of any of claims 12 to 15 wherein the sealing device comprises a pH indicator configured to change colour from a neutral, unused products, pH to an acidic pH.

22. The sealing device for use in the method of any of claims 3 to 20.

23. The sealing device of claim 22 suitable for use in the method of claims 4 to 20.

24. The sealing device of claim 22 suitable for use in the method of claims 5 to 20.

25. The sealing device of claim 22 suitable for use in the method of claims 12 to 20.

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