Patent Application
20080060741
The preferred embodiments of the invention will hereinafter be described in conjunction with the appended drawings provided to illustrate and not to limit the invention, wherein like designations denote like elements, and in which:
Additionally, Table 1 provides as cross reference of all figure captions to the above figures and items illustrated within each figure.
The use of the terms “a,” “an,” “the,” and similar referents in the context of describing the invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise indicated.
The term “substance” is used to denote any chemical or physical substance, including substances in the form of liquids, solids, gases and/or vapors.
Further, article 100 may feature one or more polymeric membranes. In this embodiment of the invention, article 100 is made from a first polymeric membrane 102a and a second polymeric membrane 102b. Parts of the first polymeric membrane 102a and the second polymeric membrane 102b are bonded together using an ultrasonic welding process to produce an ultrasonic welded seal 104. The ultrasonic welding process is well known in the art and is used for producing ultrasonically welded seals between two or more polymeric membranes. Ultrasonic welded seal 104 includes a continuous bonded region 106 formed by the improved ultrasonic welding process of the present invention. Continuous bonded region 106 defines a boundary for a bonded compartment 108. Bonded compartment 108 provides an enclosed interior volume for containing the active substance. Ultrasonic welded seal 104 has a positive controlled permeability for the active substance and the movement of the active substance across ultrasonic welded seal 104 defines a controlled permeation of the active substance from an interior region of the article to an exterior environment in which article 100 is placed. To achieve the controlled permeation, in an embodiment of the present invention, ultrasonic welded seal 104 of article 100 features a plurality of tortuous free paths (the tortuous free paths are not shown in
The plurality of tortuous free paths are present within continuous bonded region 106 of ultrasonic welded seal 104, between first polymeric membrane 102a and second polymeric membrane 102b. The plurality of tortuous free paths controls the direction of movement and diffusion rate of the active substance across ultrasonic welded seal 104. The length and the size of the plurality of tortuous free paths in ultrasonic welded seal 104 determine the overall permeability and diffusion properties of article 100 with respect to the substance contained in bonded compartment 108.
In various embodiments of the present invention, ultrasonic welded seal 104 has a positive controlled permeability for the active substance in the range of about 0.033 bubble-inch per second to less than about 3.33 bubble-inch per second, when measured by Bubble Test Method. The Bubble Test Method may be suitably employed for quantifying the permeability of a membrane and a bonded seal comprising a permeable article. The procedure for carrying out the Bubble Test has been provided later in the ‘Tests and Examples’ section of the detailed description section.
In the given embodiment of the present invention, first polymeric membrane 102a and second polymeric second membrane 102b feature at least one polymeric material selected from the group consisting of polyethylene terephthalate (PET), polyamide, polyurethane (PU), polyester (PES), polyethylene (PE), polyvinyl chloride (PVC), chlorinated polyvinylidene chloride (CPVC), polyacrylamide (PAM), polystyrene (PS), polypropylene (PP), polycarbonate (PC), polyaryletherketone (PEK), poly(cyclohexylene dimethylene cyclohexanedicarboxylate), poly(cyclohexylene dimethylene terephthalate), poly(cyclohexylene dimethylene terephthalate) glycol, polyetherimide, polyethersulfone, poly(ethylene terephthalate) glycol, polyketone (PKO), poly(oxymethylene), polyformaldehyde, poly(phenylene ether), poly(phenylene sulfide), poly(phenylene sulfone), polysulfone, polytetrafluoroethylene (PTFE), poly(vinylidene fluoride), polyamide thermoplastic elastomer, polybutylene, polybutylene terephthalate, polypropylene terephthalate, polyethylene naphthalate (PEN), polyhydroxyalkanoate, polyacrylate (PAA), poly(methyl)methacrylate (PMMA), polytrimethylene terephthalate, polyvinylidene chloride, Tyvek™ and combinations thereof, and copolymeric materials polymerized from of one or more monomers selected from acrylate, acrylonitrile, butadiene, ethylene, formaldehyde, maleic anhydride, melamine, methacrylate, methyl methacrylate, phenol, propylene, styrene, urethane, and vinyl acetate.
In another embodiment of the present invention, polymeric membrane materials can alternatively be formed of thermoplastic elastomers. Examples of the thermoplastic elastomers include, but are not limited to, copolyester thermoplastic elastomer (TPC), olefinic thermoplastic elastomer (TPO), styrenic thermoplastic elastomer (TPS), urethane thermoplastic elastomer (TPU), thermoplastic rubber vulcanisate (TPV), rubber, neoprene, vinyl, silicone elastomer, and combinations thereof. In one embodiment of the invention, any one or combination of the polymeric materials in the form of a non-permeable (solid) polymeric sheet may be employed. In this particular embodiment, first polymeric membrane 102a and second polymeric second membrane 102b are non-permeable to the active substance, such that the overall permeation of the active substance with respect to the formed article 100 is a single mode diffusion rate solely determined by the permeability characteristics of the inventive ultrasonic weld seal formed by ultrasonic bonding of the first and second polymeric membranes.
In another embodiment of the invention, any one or combination of the polymeric materials in the form of one or more non-woven permeable polymeric membranes having effective pore sizes in the range of about 0.01 micrometers to about 100 micrometers can be used for manufacturing first polymeric membrane 102a and second polymeric second membrane 102b. In the given embodiment of the present invention, first polymeric membrane 102a and second polymeric second membrane 102b having effective pore sizes in the range of from about 0.01 micrometers to about 100 micrometers are preferred. In one embodiment, first polymeric membrane 102a and second polymeric second membrane 102b are both permeable to the active substance. Accordingly, in this embodiment, the overall permeability of the active substance with respect to the formed article 100 is a superposition of the permeability of the active substance with respect to the permeable membrane 102a and 102b and the permeability of the active substance with respect to the characteristics of the inventive ultrasonic weld seal formed by ultrasonic bonding of the first and second polymeric membranes. Thus, in this embodiment, a multimodal diffusion profile, by the superposition of permeability characteristics exhibited by first polymeric membrane 102a, second polymeric membrane 102b and ultrasonic welded seal 104 is manifested by the article with respect to the active substance contained with the bonded compartment 108 of article 100.
In other embodiments of the invention, an article may include polymeric membranes with uniform or non-uniform pore size in the desired range, to achieve a desired effect on the overall diffusion profile, represented by the superposition of permeability characteristics of the formed article 100 with respect to the active substance.
In other embodiments of the invention, an article may include polymeric membranes with selective permeability characteristics with respect to one or more substances contained within the bonded compartment such that permeation of the one or more substances from bonded compartment 108 to an exterior environment is controlled by the permeability characteristics of the respective polymeric membrane that provides permeability to one or more active substances. An example of this embodiment is an article 100 containing an active substance A and an active substance B wherein polymeric membrane 102a provides permeability to substance A only, polymeric membrane 102b provides permeability to substance B only, and ultrasonic weld seal 104 provides controlled permeability to substance A and B, resulting in an overall multimodal diffusion profile with respect to substances A and B that can be selectively determined by selection of the two polymeric membranes 102a and 102b and the characteristics of the ultrasonic weld seal 104 according to the methods of the present invention.
In other embodiments of the invention, one or both of first polymeric membrane 102a and second polymeric membrane 102b may be selected to have permeability with respect to an external substance not contained within article 100, while simultaneously being non-permeable with respect to an active substance contained within bonded compartment 108 within article 100. A non-limiting example is an article formed with a first water permeable membrane 102a and a non-water permeable membrane 102b that is placed into an aqueous environment during use, having characteristics that then enable water from the surrounding aqueous environment to diffuse into the bonded compartment 108 to activate the active substance to generate a reactive product within the bonded compartment that is released from the article at a controlled diffusion rate determined by the permeability characteristics of the ultrasonic welded seal 104 of the article.
One of the applications of article 100 is achieving desired movement of the active substance, both in terms of direction and diffusion rate, across ultrasonic welded seal 104. The controlled permeation of the active substance across ultrasonic welded seal 104 allows an accurate quantity of the active substance to be contained in article 100 and delivered with efficacy to the point of use of the article.
In various embodiments of the present invention, the active substance can be in the form of a gas, a saturated vapor, a liquid, a solid, a particulate and a solution. The active substance is selectively chosen to provide a controlled positive permeability across ultrasonic welded seal 104, with respect to at least one of a gas, saturated vapor, a liquid and a solution. The movement of the active substance across ultrasonic welded seal 104 can be activated by environmental factors, physical factors, chemical factors, thermal factors or any combinations thereof.
In various embodiments of the present invention, applications of the article include, but are not limited to, a vapor releasing article, an odor or liquid absorbing article, a liquid releasing pouch, a solid containing pouch that reacts with environmental water or water vapor to produce one or more of a gas, a liquid, a solution that permeates outward across an ultrasonically welded seal of the article. In various such embodiments, the article containing an active substance, is stored and transported in a non-permeable outer pouch, so that the article does not allow any release of the active substance until the outer pouch is removed. Further, the non-permeable outer pouch protects the article from any environmental and chemical changes. In various embodiments, an environmentally degradable coating on the exterior surface of the article is employed so that the article does not allow any release of the active substance until the outer environmentally degradable coating is removed. One non-limiting example is a coating of a water-soluble coating that is non-permeable with respect to the active substance contained within the article, but which dissolves when the article is placed into an aqueous environment and thus is effectively removed from the surface of the article at the point of use.
Examples of the active substances contained inside the article may include, but are not limited to, air-treating materials. Examples of the air-treatment substances include chlorine dioxide, vaporized hydrogen peroxide, and vaporized hypochlorous acid, which can be released into a room, an interior space of a car, a tumble dryer, or a fabric treatment device. The active substances may be selected to either produce a second active substance for release upon some appropriate trigger event at point of use, such as exposure to heat or water, for example, or alternatively two or more substances may be combined which generate an active substance in situ within the article upon an appropriate trigger event, so that the active substance is released at point of use. Further, the article may include fluid-treating compositions that release active substances such as a liquid solution, a gel, a powder, or a suspended powder in aqueous or non-aqueous medium. These fluid-treating compositions may be used for treating laundry, or hard surfaces, for example, and may include, but are not limited to, bleaches, oxidants, surfactants, solvents, fragrances, disinfectants, and combinations thereof. When the article containing the fluid-treating compositions is squeezed, pressurized, used as wiping article, or placed into water, such as into a water filled bucket or a washing machine, or is submerged in an aqueous or non-aqueous liquid media, the fluid-treating compositions are released into the surrounding medium to produce a treatment composition appropriate for a particular use.
According to the embodiment depicted in
In other embodiments of the invention, an article may feature at least one ultrasonically welded seal with a positive controlled permeability for an active substance. Further, the article may additionally include other bonded seals, wherein the other bonded seals may be non-permeable. The non-permeable bonded seals may or may not be bonded using an ultrasonic welding process. Where a non-permeable bonded seal is to be formed in an article of the present invention, any bonding process known to those in the art may suitably be employed to form such non-permeable bond.
In another embodiment of the invention, the article may feature a plurality of polymeric membranes. The plurality of polymeric membranes are welded together by a plurality of the ultrasonically welded seals to form a bonded region. The bonded region defines a bonded compartment for containing an active substance. Further, the plurality of the ultrasonically welded seals have different positive controlled permeability's for the active substance. This allows the article to exhibit a multiple mode permeation of the active substance. A first kind of the multiple mode permeation may be achieved when at least two of the plurality of the ultrasonically welded seals have different positive controlled permeability's for the active substance. The multiple mode permeation of the active substance allows a simultaneous movement of the active substances through two or more different paths at the same or different diffusion rates. The direction of the movement of the active substances may also vary for the different paths. For example, when a vapor releasing active substance is contained in a pouch, the vapor releasing active substance is able to chemically react with moisture around the pouch and releases the desired vapor. In a first step, the moisture surrounding the exterior of the pouch permeates inside the article through a first path. In a second step, a chemical reaction takes place between the moisture and vapor releasing active substance, and in a third step the vapor of the vapor releasing active substance permeates through a second path outward from the bonded compartment of the pouch to the exterior of the pouch, diffusing in a fourth step into the immediately surrounding environment.
In yet another embodiment of the present invention, the article features one type of polymeric membrane with a selected membrane permeability for the active substance. The article further features at least one ultrasonically welded seal having a positive controlled permeability for the active substance. In this embodiment, the movement of the active substance across the at least one ultrasonically welded seal and across the one type of polymeric membranes provide a second kind of mechanism for multiple mode permeation of the active substance, wherein the selected membrane permeability of the one polymeric membrane and the positive controlled permeability of the at least one ultrasonically welded seal are set at predefined diffusion rates. The permeation characteristics of the ultrasonically welded seal and the polymeric membrane can be same or different from each other to produce a single mode or dual mode diffusion rate of the active substance.
In another embodiment of the invention, the article may feature at least two polymeric membranes having different selected membrane permeability's for the active substance, and an ultrasonically welded seal having a positive controlled permeability for the active substance. In this embodiment, the movement of the active substance across the ultrasonically welded seal and across the at least two of the polymeric membranes provide a third kind of mechanism for multiple mode diffusion rates of the active substance.
In various other embodiments of the present invention, the polymeric membranes may be non-permeable in nature or treated, by any means known in the art, to exhibit a selected membrane permeability, or an adjustable membrane permeability that varies with respect to an external parameter such as for example, surrounding media temperature, electrolyte strength, solvent polarity, osmotic pressure, pH, alkalinity, and combinations thereof. One may select a non-permeable membrane, or any combination of non-permeable and permeable membranes, or alternatively any one or more combination of the permeable membranes to construct an article of the present invention. By selecting the appropriate membrane material, whether being non-permeable or exhibiting the selected membrane permeability, the article of the present invention can be constructed by employing an ultrasonically welded seal that exhibits either single mode permeation or multiple mode permeation characteristics with respect to one or more active substances contained within one or more bonded regions of the article.
In a variation of the above embodiment, the two actives substances A and B can be contained in an article comprising two polymeric membranes that define two bonded compartments. The two bonded compartments are defined by two non-adjacent ultrasonically welded seals and a common adjacent ultrasonically welded seal at the junction of the two bonded compartments. The adjacent ultrasonically welded seal is non-permeable. The two non-adjacent ultrasonically welded seals of the bonded compartments have a positive controlled permeability and at least one of the two polymeric membranes of the article has a selected membrane permeability. The movement of the active substances A and B across the non-adjacent ultrasonically welded seals and the polymeric membranes define a multi modal controlled permeation of the active substances A and B.
In another embodiment of the present invention, one or more polymeric membranes are ultrasonically bonded to form one or more continuous bonded regions that provide a plurality of bonded compartments for containing one or more active substances. The plurality of bonded compartments selectively contains the one or more active substances individually, or in any desired combination, and, optionally, further contains one or more non-active substances, such as for example a fluid carrier, solvent, water or the like. The one or more polymeric membranes can be optionally permeable to the one or more active substances. The at least one ultrasonically welded seal shared between two or more adjacent bonded compartments forms an adjacent bonded region, the adjacent bonded region being non-permeable with respect to the one or more active substances contained within the two or more adjacent bonded compartments. Further, the non-adjacent bonded regions of the plurality of bonded compartments feature the ultrasonically welded seals having positive controlled permeability with respect to the one or more active substances.
In another embodiment of the invention, one or more polymeric membranes of an article are ultrasonically bonded to form one or more continuous bonded regions. The one or more continuous bonded regions define a plurality of bonded compartments for containing one or more active substances. The plurality of bonded compartments selectively contains the one or more active substances individually, or in any desired combination. The polymeric membranes shared between any two adjacent bonded compartments are non-permeable with respect to the active substances contained in the adjacent bonded compartments. In this embodiment, a combination of the active substances released in the environment produce a desired effect.
In yet another embodiment of the present invention, the ultrasonic welding process is used to produce an article with an inner bonded compartment enclosed within an outer bonded compartment. The inner bonded compartment contains a first active substance, and the outer bonded compartment contains a second active substance. Further, ultrasonically welded seals forming the inner and outer bonded compartments have positive controlled permeability's with respect to the first and second active substances. In this embodiment, release of the first active substance occurs into the outer bonded compartment, enabling the first active substance and the second active substance to react and produce a third active substance, which is controllably released from the outer bonded compartment to the surrounding environment.
In other variations of this embodiment, an inner bonded compartment with a permeable ultrasonically welded seal is enclosed within an outer bonded compartment defined by a non-permeable seal with a tear perforation. The outer bonded compartment contains a first active substance and the inner bonded compartment contains a second active substance. The inner bonded compartment shares an ultrasonically welded seal with the outer bonded compartment, the ultrasonically welded seal of the inner bonded compartment having a controlled permeability for the second active substance. The outer bonded compartment can be opened by user to release the first active substance contained in it. The first active substance reacts with the environment and is capable of controlling the permeability of the second active substance present in the inner bonded compartment through the ultrasonically welded seal.
In an embodiment of the present invention, release of one or more active substances contained within an article across the ultrasonically welded seals is achieved, by use of the article on a hard surface, wherein the one or more active substances are released due to applied pressure. In another embodiment, the release of the one or more active substances is achieved by applied heat. In yet another embodiment, water is diffused into the article and the water reacts with the one or more active substance to cause a gaseous release of the active substances out of the article. In another embodiment of the present invention, the article is submerged in water, the release of the one or more active substance being achieved by hydrostatic pressure. In yet another embodiment, the article is submerged in water, water diffuses into the article, and the active substance is released into the water by permeation.
In an embodiment of the present invention, an ultrasonic weld station is used to form an article for containing and controllably releasing an active substance. The article includes one or more polymeric membranes for forming one or more bonded regions, the one or more bonded regions defining at least one bonded compartment, the at least one bonded compartment providing an enclosed interior volume for containing the active substance. In the present embodiment, parts of the one or more polymeric membranes are bonded together to obtain an ultrasonically welded seal. The ultrasonically welded seal provides a positive controlled permeability for the active substance. The desired selected permeability characteristics of the article are achieved by selecting suitable process parameters of the ultrasonic weld station. The suitable process parameters include a bonding pattern, weld energy, energy density, duration of welding and weld speed. The operation of creating the ultrasonically welded seal between the one or more polymeric membranes encompasses the creation of a plurality of tortuous free paths between the one or more polymeric membranes, the plurality of tortuous free paths allowing movement of the active substance across the ultrasonically welded seal in a controlled manner. Further, the ultrasonic weld station may produce the ultrasonically welded seals with a uniform positive permeability or a non-uniform positive permeability determined by the bonding pattern of the plurality of tortuous free paths in the ultrasonically welded seals.
In one embodiment, an ultrasonically welded seal is formed between two polymeric membranes by welding them between the mating surfaces of a horn and anvil, which may individually bear engraved, embossed or planar surface features that act in concert when brought into convergence with the polymeric membranes to form the desired bonding pattern. The bonding pattern is transferred to the polymeric membranes when the horn and anvil are engaged with the polymeric membranes between them so that their convergence forms a weld pattern that corresponds to the desired bonding pattern during an ultrasonic welding operation. The bonding pattern formed in the polymeric membranes consists of one or more ultrasonic weld seals across the bonded region where the polymeric membranes are welded. In one embodiment, a continuous ultrasonic weld seal that is contiguous across the bonded region is formed. In another embodiment, a discontinuous series of individual ultrasonic weld seals are formed that are not contiguous across the area of the bonded region. In this latter embodiment, the ultrasonic weld seals define a pattern of bonded areas and non-bonded areas within the bonded region to form a permeable interstitial bonded region featuring a plurality of tortuous paths formed by the non-bonded region being the interstitial area between the one or more bonded regions. The interstitial bonded region forms multiple tortuous paths within the interior region of the bonding area that are continuous from one side (an exterior side) of the bonded region to a second side (an anterior side) of the bonded region. During a welding operation, the polymeric membranes may be translated perpendicularly to the horn and anvil with a second welding operation so that a second bonded region immediately adjacent to the first bonded region is formed. This process can be repeated a multiple number of times to produce a series of ultrasonically welded seals defining a series of adjacent bonded regions forming a continuous pattern of bonded regions. Adjacent bonded regions may overlap so that the repeating bonding pattern forms a continuous ultrasonically welded seal across an area of the polymeric membranes.
In another embodiment, the desired bonding pattern, used to create a plurality of tortuous paths in the ultrasonically welded seal, can be formed by surface features present on either the anvil, or horn or both, such that the engagement of the horn and the anvil causes formation of a desired plurality of tortuous paths between welded parts of the polymeric membranes. In one embodiment, the bonding pattern is formed by a raised embossed pattern formed on the surface of the horn while the surface of the anvil is essentially planar. In another embodiment, the bonding pattern is formed by corresponding embossed and engraved patterns formed on the surface of the anvil and/or horn, so that the desired bonding pattern is formed by the convergence of the anvil and horn. In one embodiment, the bonding pattern is formed by the complementary pattern of embossed and engraved portions on either respective mating surface of the horn and anvil so as not to overlap during the welding process to form a series of ultrasonically welded seals in the pattern of multiple circular ultrasonically welded seals resembling “dots” form between the polymeric membranes. In other embodiments, the bonding pattern may take the form of a repeating series of geometric shaped areas, including circular, oval, triangular, rectangular, trapezoidal, square, fractal, polygonal and irregular areas, and combinations thereof. In an embodiment, subsequent adjacent bonding regions overlap to some extent within at least one adjacent bonding region or meet the adjacent bonding region on at least one common side of the two bonding regions so as to form a continuous bonding region between the two adjacent weld sites. In another embodiment, a multiple series of adjacent bonding regions define a continuous series of bonding areas in the form of discrete, repeating geometric shaped areas that extend across the polymeric membrane to form a continuous ultrasonic weld seal that features a series of non-contiguous bonded regions which define a permeable interstitial bonded region within the continuous repeating ultrasonically welded seal. In these embodiments, a continuous bonded region is formed between the polymeric membranes that extends in at least one direction with a dimensional size greater than a single bonded region defined by the size of the horn and anvil mating surface area.
In another embodiment, a rolling horn and anvil assembly may be employed where the bonding pattern to be formed is embossed on the mating surface on either or both the horn and anvil assembly so that upon translation of the assembly with respect to the two polymeric membranes positioned between the mating surfaces, a continuous ultrasonically welded seal is produced. In an alternate embodiment, an embossed bonding pattern is present on the surface of the horn in the shape of a spherocylindrical roller that bears the bonding pattern in a rotationally symmetrically loop configuration so that the bonding pattern defining the bonded region is formed upon one complete 360 degree rotation of the rolling horn perpendicular to the spherocylindrical axis of the anvil. In this present embodiment, a continuous or repeating contiguous bonded region may be formed between the two polymeric membranes in an uninterrupted ultrasonic bonding process during which the two membranes are translated in continuous step with the rotation of the rolling horn in the region between the mating surfaces of the anvil and horn. In one embodiment, the horn and anvil are both freely rotating spherocylindrical members whose mating surfaces can be brought into close proximity to each other and about the two polymeric membranes so as to facilitate forming of a continuous or repeating bonded region by feeding the membranes between them during a welding operation in which ultrasonic energy is fed to the horn member. In another embodiment, the anvil is an essentially planar surface supporting the two polymeric membranes for engagement with a rolling horn assembly that is translated in a direction perpendicular to the stationary membranes supported by the stationary anvil so as to form a continuous or contiguous bonding region during a welding process.
In another embodiment, an article may be formed where all ultrasonic weld seals are formed simultaneously across at least one continuous face of at least one polymeric membrane by employing an anvil and horn assembly with a bonding pattern that is sized appropriately to a corresponding size that encompasses all bonded regions of the formed article, so that formation of multiple ultrasonically welded seals defining a complete bonding region defining a completed sealed article is completed by application of a single welding operation upon that article.
Within bonded region 724, the repeating ultrasonic weld seal(s) 700 are positioned in an approximately parallel and rectolinear configuration represented by a series of uniformly spaced and offset weld areas formed by each individual weld seal 700 in the pattern illustrated in
The article represented in
Within bonded region 824, the repeating ultrasonic weld seal(s) 800 are positioned in an approximately parallel and rectolinear configuration represented by a series of uniformly spaced and offset weld areas formed by each individual weld seal 800 in the pattern illustrated in
In
In an alternative embodiment, a permeable ultrasonic weld seal can be formed wherein a plurality of tortuous paths are created by the inventive process within a continuous ultrasonically welded seal.
This embodiment illustrates bonded region 922 wherein permeability of a permeable continuous ultrasonically welded seal 900 is defined by a plurality of individual tortuous paths produced in an essentially random pattern across the width of the ultrasonic weld having a width dimension 906. In this embodiment the width dimension is represented by scale bar 912, having a value of approximately 8.21 mm. The plurality of individual tortuous paths are represented here by a first tortuous path 904, a second tortuous path 908 and a third tortuous path 910 that extend from an anterior side of bonded region 920 to an exterior side of bonded region 926. Additional tortuous paths produced during the ultrasonic welding process according to methods of the present invention are not visible in the photomicrograph of
Without being bound by theory, it is believed that in this and similar embodiments employing a continuous weld seam, selection of the welding parameters, including applied ultrasonic energy level, duration of applied energy and anvil to horn application pressure, may be optimally employed so as to produce incompletely bonded ultrasonic weld seals that are sufficiently porous in nature owing to a plurality of microscopic tortuous free paths that enable permeation of liquid and gaseous substances to pass through the imperfectly bonded region of the ultrasonic weld seam. Despite the porosity of the weld seams produced by the methods of the present invention, the welds are of sufficient bonding strength to secure the bonded polymeric membranes in bonded configuration to prevent physical separation or rupture of bonded regions of an article, even when significant internal pressures inside a bonded compartment are generated during use of gas or vapor releasing substances or composition within bonded compartments.
In these and other embodiments of the invention, the positive permeability of a finished article may be controlled by appropriate selection of the welding pattern, welding pattern size and spacing, extent of permeable weld seal region, and ultrasonic welding process parameters to generate an article having the desired permeability with respect to one or more substances or reactive products generated by substances within one or more bonded compartments of a finished article, by correlating to a Bubble Test Method parameter that measures positive permeability of a formed article, as described in the ‘Tests and Examples’ section.
At operation 606, the article is kept in an environment whereby the one or more active substances are released from each of the one or more bonded compartments at a rate determined by the positive controlled permeability of each respective bonded region formed by the at least one ultrasonically welded seal.
The method for manufacturing an article capable of storing and controllably releasing one or more active substance includes controlling the process parameters of the ultrasonic welding station. Further, the method also includes controlling one or more selected bonding patterns on the horn and the anvil of the ultrasonic welding station. The permeability of the article is tested using the Bubble Test method described in the ‘Tests and Examples’ section.
The various embodiments of the present invention provide the following advantages. One of the advantages is to provide controlled permeation of active substances contained in articles or pouches, to a desired point of use. This permeation allows effective and required amounts of active substances to be delivered at the desired point of use. Further, the present invention does not require any manual participation for controlling the permeation of the active substances. Another advantage of the present invention is to provide controlled permeation of active substances at a predetermined rate. Yet another advantage of the present invention is that the permeation characteristics of the active substances are controlled without affecting the strength of ultrasonically welded seals used to bond the articles or pouches. Further, the articles or pouches allow active substances in the form of gases, solids, solutions and liquids to be stored and permeated with controlled diffusion rate, for delivery to the point of use. The article can also be used for filtering of a gas, liquid, vapor, and combination thereof.
The Bubble Test method provides a means for quantifying positive controlled permeability of an ultrasonically welded seal.
Actual determination of the permeability coefficient of an active substance across an ultrasonically welded seal of an article is difficult to measure, particularly when low permeability is selected or an active substance is employed whose release rate is difficult to quantitatively determine. Accordingly, use of actual permeation rates of an active substance to provide feedback for setting of manufacturing and process parameters to produce the desired ultrasonically welded seal according to the present invention is generally cumbersome. To address this, the Bubble Test method is employed to more readily characterize the positive controlled permeability of the article, using a method that is easy to use during production and process control, so as to provide quick feedback to enable nearly real-time process control and setting of manufacturing and process parameters during manufacturing of the article. The Bubble Test method measurements can also be correlated against other test data, including for example a diffusion rate measurement of an active substance determined by some other means known in the art, to provide a means for optimizing and selecting process parameters for control of the ultrasonic welding process to achieve a desired positive permeation of a finished article with respect to the one or more active substances contained within one or more bonded compartments.
Following is a description and test method steps of the Bubble Test. The purpose of the test is to measure air permeation rate from trapped air within a test article comprising polymeric membranes bonded by the ultrasonic welding process of the present invention.
Apparatus required includes a vacuum pump, a bubble tester, a stop watch and optionally a video capture device or human operator to observe and count bubbles. A bubble tester is any closeable container that can releasable hold water, one or more test articles and has at least one transparent wall or window enabling observations of the interior space, and which may be depressurized to a value of about 5 torr with respect to atmospheric standard pressure. In one embodiment, a Nalgene vacuum desiccator of polycarbonate construction available from Cole-Parmer Instruments, Vernon Hills, Ill. is employed as a bubble tester
1. Seal the test article with a selected bonding pattern based on a first set of values of process parameters of the ultrasonic welding process, the article is sealed with a trapped air volume at predefined pressure. One or more similar pouches may be used for replicate purposes.
2. Remove covering of the bubble tester and fill with sufficient tap water to completely submerge the test article.
3. Submerge the prepared test article into the bubble tester, and if necessary keep it submerged using some weight.
4. Close and seal the bubble tester and connect the vacuum pump to the bubble tester.
5. Switch on the vacuum pump and observe the rate of release of air bubbles from the submerged test article using the stop watch.
6. Repeat steps 2-5 if necessary.
Despite the apparent simplicity of the Bubble Test, sacrificial test articles could rapidly be evaluated and used to adjust manufacturing and process parameters to produce multiple finished articles of very uniform characteristics matching a desired positive permeability for a selected active substance.
In the given embodiments of the present invention, the preferred range of the positive controlled permeability is greater or equal to about 1 bubble/30 seconds per linear inch of the bonded region (about 0.033 bubble-inch per second) and less than about 100 bubbles/30 seconds per linear inch of the bonded region (about 3.33 bubble-inch per second). A positive controlled permeability of less than about 0.033 bubble-inch per second may be achieved by relying on the characteristic permeation of the polymeric membrane itself, when such a permeable membrane material is optionally selected for use. A positive controlled permeability greater than about 3.33 bubble-inch per second is generally found to be too leaky to provide the most optimum controlled permeation. However, in other embodiments of the invention, depending on the characteristics of the active substance, the positive controlled permeability of the article can vary from these rates.
The bonding strength of the ultrasonically welded seal with a controlled permeability produced using the ultrasonic welding process has excellent bonding strength with respect to forming an article with ultrasonically welded seams being resistive to failure. To measure bonding strengths, a Peel Test method was developed that provides numeric peel resistance measurement values that can be used to adjust manufacturing and process parameters according to the present invention.
The Peel Test method can use any device capable of gripping and pulling apart a two layered test sample. An Instron Model 5565 was employed using opposed 2′ finger grip jaws in the upper and lower mandrels that were drawn apart at a constant rate while measuring peak (maximum) load in pounds of force (lbf) and energy at maximum peel extension in pounds of force per inch (in-lbf). A sacrificial test strip of two polymeric membranes bonded along the two longest sides (lengthwise) of an approximately 3 inch by 12 inch double layered test article is prepared using the desired repeating ultrasonic bond weld seal pattern to produce a continuous bonded region of approximately 10 inches in length along the two sides of the test article, and inwardly offset by about 0.50 inches from the edge, using the manufacturing and process control parameters to be evaluated for peel strength determination. This produces a test article that has two bonded regions running lengthwise, separated across the smallest side (widthwise) of the test article by about 2 inches, the two continuous bonded regions each being about 0.50 inches from each edge to minimize any edge effects during peel test strength determination. This produces a test article having two unbonded tongues of the polymeric membranes of about 2 inches in length that are sufficient in length so as to be gripped independently by the opposed finger grip jaws so that displacement of the mandrels will result in a perpendicular applied displacement force to the longitudinal welded seams of the test article, tearing it lengthwise from the unbonded end lengthwise along the bonded seam until the two polymeric membranes are nearly fully separated from one other. An ASTM 2737M 5.6 bond strength protocol was used on the instrument for numerical analysis, the mandrels displaced at a rate (strain rate) of about 12 inches/minute. Typically, about seven replicates produced under identical conditions are measured and an average value determined for the set.
Following are the method steps of carrying out the Peel Test. The purpose of the Peel Test Method is employed to readily characterize the strength of the welded seal of the article. The Peel Test method may be used during production and process control of making the ultrasonically welded seal, so as to provide a feedback to enable nearly real-time process control and adjustment of process parameters during the manufacturing of the article, enabling control to obtain both the desired positive permeability of the finished articles and an acceptable bonding strength for bond stability and integrity of the finished article during manufacture, storage, transportation to point of use.
Test strips prepared according to the “double line” repeating ultrasonic weld pattern described in
While the preferred embodiments of the present invention have been described, it will be clear that the invention is not limited to these embodiments only. Numerous modifications, changes, variations, substitutions and equivalents will be apparent to those skilled in the art without departing from the spirit and scope of the invention as described in the claims.
