Cross-Reference to Related Applications

[0001] The present application claims the benefit of U.S. Provisional Patent Application No.

60/790,261 filed March 15, 2013 and U.S. Provisional Patent Application No. 61/914,032 filed December 10, 2013, all of which are incorporated herein by reference in their entireties.

Field of the Invention

[0002] The present invention includes a recyclable sterilization indicator article. More particularly, polymeric based sterilization tape which is completely recyclable.

Background of the Invention

[0003] Most sterilization tape is paper based. However, paper based indicator tape renders blue-wrap waste non-recyclable. By changing the base of the typical sterilization tape to a recyclable polymer, hospitals can reduce the single biggest source of landfill waste produced.

Brief Summary of the Invention

[0004] The embodiments of the present invention described below are not intended to be exhaustive or to limit the invention to the precise forms disclosed in the following detailed description. Rather, the embodiments are chosen and described so that others skilled in the art may appreciate and understand the principles and practices of the present invention.

[0005] In accordance with one embodiment, a printed polymeric dual surface su bstrate is disclosed which includes at least one polymeric layer, a sterilization ink layer, and a release coating layer.

[0006] In accordance with another embodiment, a printed polymeric dual surface substrate is disclosed which includes at least two polymeric layers, a sterilization ink layer, and a release coating layer.

[0007] In accordance with another embodiment, sterilization tape comprises a printed polymeric dual surface substrate and at least one adhesive layer.

[0008] In accordance with another embodiment, a process for producing sterilization tape includes obtaining a suitable polymeric substrate, surface treating the polymeric substrate, printing the indicator artwork on the treated surface of the polymeric substrate using sterilization ink, applying a suitable release coating over the printed surface, and laminating the printed substrate to existing coated tape by applying the adhesive to the non-treated side of the printed laminate and removing the release layer.

[0009] In accordance with another embodiment, a process for producing sterilization tape includes obtaining a suitable polymeric substrate, surface treating the polymeric substrate, printing the indicator artwork on the treated surface of the polymeric substrate using sterilization ink, applying a suitable release coating over the printed surface, and applying the adhesive in one pass.

[0010] In accordance with another embodiment, a method of using sterilization tape includes placing medical equipment, such as surgical instruments, in a stainless steel tray, the tray is wrapped in wrap material, and the material is then folded over to enclose the instruments in the wrap. The indicator tape is then used to securely close the wrapped bund le. The bundle is then subjected to a sterilization cycle. During the cycle, the ink on the indicator tape changes color, this indicates that the bundle has been exposed to a hospital sterilization cycle and is ready for use. At the completion of the use, the wrap and tape material are discarded.

[0011] Other features and advantages of the present invention will become apparent to those skilled in the art from the following detailed description. It is to be understood, however, that the detailed description of the various embodiments and specific examples, while indicating preferred and other embodiments of the present invention, are given by way of illustration and not limitation. Many changes and modifications within the scope of the present invention may be made without departing from the spirit thereof, and the invention includes all such modifications.

Brief Description of the Drawings

[0012] These, as well as other objects and advantages of this invention, will be more completely understood and appreciated by referring to the following more detailed description of the presently preferred exemplary embodiments of the invention in conjunction with the accompanying drawings, of which:

[0013] FIGURE 1 depicts the conventional sterilization tape prior art.

[0014] FIGURE 2 depicts an exemplary embodiment of the printed polymeric dual surface substrate of the current invention.

[0015] FIGURE 3 depicts another exemplary embodiment of the printed polymeric dual surface substrate of the current invention.

[0016] FIGURE 4 depicts an exemplary embodiment of the sterilization tape of the current invention.

[0017] FIGURE 5 depicts another exemplary embodiment of the sterilization tape of the current invention. Detailed Description of the Invention

[0018] The apparatuses and methods disclosed in this document are described in detail by way of examples and with reference to the figures. Unless otherwise specified, like numbers in the figures indicate references to the same, similar, or corresponding elements throughout the figures. It will be appreciated that modifications to disclosed and described examples, arrangements, configurations, components, elements, apparatuses, methods, materials, etc. can be made and may be desired for a specific application. In this disclosure, any identification of specific shapes, materials, techniques, arrangements, etc. are either related to a specific example presented or are merely a general description of such a shape, material, technique, arrangement, etc. Identifications of specific details or examples are not intended to be, and should not be, construed as mandatory or limiting unless specifically designated as such. Selected examples of apparatuses and methods are hereinafter disclosed and described in detail with reference made to FIGURES.

[0019] Sterilization tape currently exists. Conventional sterilization tape is typically paper- based tape that uses temperature or chemical sensitive inks that change color when subjected to heat, humidity, and/or chemicals associated with sterilization cycles. Figure 1 shows a prior art sterilization tape embodiment. The prior art sterilization tape (11) can contain 4 separate layers. The first layer is a silicon release coating layer (10). Adjacent to the silicone release layer is a sterilization ink layer (20). Below, or beneath, the sterilization ink layer (20) is a paper substrate layer (30). Finally, adjacent to the paper substrate layer (30) is an adhesive layer (40). An optional release line may be added adjacent the adhesive layer.

[0020] Prior art sterilization tape is typically used in conjunction with polypropylene surgical wrap material. Surgical instruments are placed in a stainless steel tray, the tray is wrapped in wrap material, and the material is then folded over to enclose the instruments in the wrap. The indicator tape is then used to securely close the wrapped bundle. The bundle is then subjected to a sterilization cycle. During the cycle, the ink on the indicator tape changes color, this indicates that the bundle has been exposed to a hospital sterilization cycle and is ready for use in surgery. At the completion of the surgery, the polypropylene wrap and tape material are discarded. The polypropylene wrap can be easily recycled, but the paper-based tape contaminates the polypropylene because the tape burns when the polypropylene melts. Changing to a polymeric, plastic based tape will enable the wrap/tape combination to be easily recycled into the plastic hospital waste stream.

[0021] In accordance with one embodiment, a printed polymeric dual surface substrate which includes at least one polymeric layer, an ink layer and a release coating layer is disclosed. In accordance with another embodiment, the polymeric dual surface substrate includes at least two polymeric layers, an ink layer, and a release coating layer.

[0022] In order to integrate polymeric substrate into a traditionally paper based sterilization tape application, several factors have to be considered. The polymeric substrate needs to have distinct characteristics in order for it to be usable as a sterilization tape substrate.

[0023] One important feature of a polymeric carrier tape is that it be recyclable within the polypropylene waste stream generated by hospitals. A second important feature of the carrier is that each surface has the required characteristics to function effectively as a sterilization tape. The polymeric based sterilization tape must enable user to tear strips with a dispenser. Finally, the process used to produce the polymeric based sterilization tape must limit the exposure of the ink to heat to ensure it isn't activated too soon.

[0024] The polymeric carrier layer must have certain properties on each outer surface. The first surface must accept ink, accept the release coating layer, and must not let the ink travel through the layer. The tape surface is polymeric and must have non-polar properties. On the other hand, the first surface must also not repel polar substances, like steam. This first surface must also enable steam to travel to ink. The second surface must accept adhesive and prevent adhesive from migrating through the layer. It is important that the adhesive layer and ink/silicon layers do not interact. The polymeric layer will eventually be used as a tape, so it is also important that the surfaces work to be self-windable. The adhesive (attached to the second surface of the polymeric carrier layer) must adhere to the second surface of the film, but not the first surface. The polymeric dual surface can be a single layer, so long as both surfaces are present with these characteristics. The polymeric dual surface substrate can be any number of polymeric layers so long as the outer surfaces contain these properties. The polymeric dual surface substrate can be texturized on one or both surfaces to create these properties. In one embodiment the texturizing is embossing.

[0025] Any recyclable polymer or combination of recyclable polymers can be utilized as the substrate for the current invention. Recyclable polymers can be grouped into categories based on their numerical categorization. Recycling symbol 1 marks PET or PETE (polyethylene terephthalate) such as soft drink bottles. Recycling symbol 2 marks HDPE (high density polyethylene) such as milk jugs and trash bags. Recycling symbol 3 marks V (vinyl) or PVC (polyvinyl chloride) such as piping and some medical equipment. Recycling symbol 4 marks LDPE (low density polyethylene) such as dry cleaning bags. Recycling symbol 5 marks PP (polypropylene) such as medicine bottles and straws. Recycling symbol 6 marks PS (polystyrene) such as disposable plates and egg cartons. Recycling symbol 7 marks miscellaneous plastics such as polycarbonate and other non-commodity polymers.

[0026] In one embodiment, the polymeric layer is comprised of any one or combination of any of the recyclable polymers previously noted. In a preferred embodiment, the at least one polymeric layer is comprised of polypropylene polymer.

[0027] The polypropylene of the polymeric substrate of the sterilization tape can comprise a polypropylene homopolymer, a polypropylene copolymer, or a mixture of two or more of any of the foregoing polypropylene polymers. In an embodiment of the invention, the polypropylene copolymer comprises a random copolymer, a block copolymer, or a mixture of two or more of any of the foregoing copolymers.

[0028] Different grades of polypropylene can be used in the polypropylene substrate. In one embodiment, Isotactic, semicrystalline grades of polypropylene were used. Any other desired grade, including atactic and syndiotactic grades, can also work in the invention.

[0029] Additionally, a small percentage of additional polymer can be mixed with the polypropylene because polypropylene polymers are considered recyclable provided they are contaminated by no more than 2% of another polymer in addition to the polypropylene. The carrier can therefore be made from polymers other than polypropylene provided that the overall mass percentage of the other polymer remains below 2% in the hospital waste stream. In one embodiment, the polypropylene substrate of the sterilization tape contains up to 2% of an additional polymer. In another embodiment, the additional polymer is polyethylene. In a further embodiment, polyethylene terphthalate (PET) is the additional polymer. In another embodiment, the additional polymer is a previously listed recyclable polymer with a designated recycling symbol.

[0030] The polymeric layer or layers of the polymeric substrate may be any sheet forming, film forming, or substrate forming material, preferably a flexible material such as paper, synthetic paper, non-woven sheets, fabric sheets, polymeric film or sheets, and the like.

[0031] In one embodiment at least one polymeric layer includes a polyester film, particularly polyethylene terephthalate (PET) films, poly(ethylene 2,6-naphthalene dicarboxylate) (PEN) films, and polypropylene films. In a preferred embodiment, at least one polymer layer includes a polypropylene film layer.

[0032] In yet another specific embodiment of the invention, the polymer layer or layers may further incorporate a nonwoven web consisting of a web having an entangled structure of individual synthetic fibers, filaments, threads or staple length polymeric fibers composed of one or more thermoplastic polymers. The nonwoven web may also be provided as a lamina in the layered structure of the polymer layer or layers. Nonwoven webs may be formed from many processes such as, for example, meltblowing processes, spunbonding processes, and bonded carded web processes. The nonwoven web may consist of a multilayer laminate characterized by a combination of spundbond and meltblown layers. Common thermoplastic polymers used to form nonwoven webs include, but are not limited to, polyolefins such as polyethylene, polypropylene, polybutylene, polyamides such as nylon 6, nylon 6/6, nylon 10, and nylon 12, polyesters such as polyethylene terephthalate and polybutylene terephthalate, polycarbonates, polystyrenes, thermoplastic elastomers, fluoropolymers, vinyl polymers, and blends and copolymers thereof. In a preferred embodiment, the nonwoven is spunbond.

[0033] In a preferred embodiment, the polymeric substrate is two layers, nonwoven and film.

The nonwoven layer has the first surface properties and the film layer has the second surface properties. The two layers may be combined in any known ways. In a preferred embodiment, the two layers are laminated together. In another embodiment adhesive joins the two layers.

[0034] The polymer layer or layers must accept the sterilization ink. In a preferred embodiment, the ink is water based. The ink must color change at 134 C for 2 minutes. The ink is formulated to print best on substrates with surface energies between 38 and 44 dynes. The polymer layer or layers must be surface treated in order for this to achieve this surface energy. The polymer layer or layers may be treated with any acceptable technique to alter the surface. Suitable treatments include corona, plasma, flame and chemical treatments. In a preferable embodiment, corona treatments can be used to increase the surface energy of the polymer layer or layers to enable printing.

[0035] Corona treatment uses electrodes to apply an electric field across a film or sheet. The electric field generates a plasma from the air molecules between the electrodes and that plasma includes free electrons and other chemical species which interact with the web to increase the surface energy. [0036] The polymer layer or layers must also effectively allow steam to reach and activate the indicator ink during sterilization autoclave cycles. The transmission of water vapor is an important characteristic of the film and carrier layer to ensure functionality. In order to meet this characteristic, polymeric substrates may be composed of multiple layers which manage the transmission of liquid water and water vapor across the surface. Examples of such substrates are already used by Avery Dennison to serve the diaper, feminine care, and personal care markets. In one embodiment the polymer substrate is a single layer. The polymer layer or layers must enable user to tear strips with a dispenser. In order to accomplish this goal, the thickness and tear strength of the substrate must be considered.

[0037] One solution to increase tearability of the tape is adding scoring or perforations to the substrate. The scoring can be patterned or randomized. The frequency can be increased to improve tearability. Any accepted method of scoring or perforating known is the art can be chosen. A second way to increase tearability is to use a substrate that has inherently lower tear strength. Non-woven material is an example of such a substrate.

[0038] The thickness of the polymer substrate is important for the film. In one embodiment, the polymer layer or layers of substrate is from 2 mil to 15 mil thick. In a preferable embodiment, the polymer substrate or layers of substrates is between 3-7 mil thick.

[0039] Application of the appropriate release treatment is vital to the current invention. It is important to choose a treatment that will not react with the indicator ink and leads to a self-windable tape. In one embodiment, the treatment is a silicone treatment. Any silicone system known to those skilled in the art may be used provided it doesn't react with the ink and leads to a self windable tape.

[0040] Silicone systems, and the silicone treatment layer of the current invention, can include formulations with one, two, or three resin components. For the single resin coatings, heat is used to cure the system into a 3 dimensional network of chains. In the two component system, one resin consists of silicone oligomers with catalyst and the other a crosslinker resin that cures and extends the chains upon curing. In each system there can be multiple polymerization monomers, oligomers, functional groups, processes and catalysts known within the coatings field. Cures can be based on application of UV radiation or heat. A cure can be done at room temperature with times over 24 hours to temperatures over 150C and mere seconds. Most commercial curing processes take place between 1-5 minutes at temperatures between lOOC and 210C. In a preferred embodiment, the silicone curing is by application of UV radiation.

[0041] A platinum or tin catalyzed silicone may be used. The silicone can be 100% silicone or silicone in a resin. In one embodiment, the silicone is in the range of 0-20% in a resin. In one embodiment, the resin is a methacrlyate resin. In a preferred embodiment, a tin catalyzed silicone that can be used. In another embodiment, a platinum catalyzed silicone is used.

[0042] It is also important to apply the correct amount or thickness of silicone treatment to the laminate. The siliconization must be balanced such that the tape can be self wound and still not introduce so much silicone that the tape cannot be recycled. In one embodiment, the silicone layer is less than 30 gsm (grams per square meter). In a preferred embodiment the silicone release layer is less than 10 gsm.

[0043] Any sterilization indicator system known in the art can be used to indicate sterilization.

In a preferred embodiment, sterilization ink is used in the dual surface substrate and tape. Sterilization ink provides the color change that indicates when the bundle has experienced a sterilization cycle and ready for use. In one embodiment, the sterilization ink is water based. A possible ink for use in this invention is SSI-10-UBL supplied by Namsa, previously under the product name Sterisun 23048. SSI-10- UBI is classified as an ISO1140-1 class 1 process indicator for steam sterilization. Another possible ink is SSI-10-BBI. Any sterilization ink known in the art for this particular purpose can be readily used. [0044] Sterilization ink changes in color from time of application to after the tape has experienced a sterilization cycle. In one embodiment, the specific cycles used are outlined in ISO 11140- 102009. In a preferred embodiment the color change of the sterilization ink is from clear to black. In another embodiment, the color change of the sterilization ink is from blue to black. However, any desired color change can be used.

[0045] The sterilization ink can be applied to the polymeric layer or layers in any number of patterns and can be any desired size or shape. In one embodiment, the ink is applied in diagonal lines. The sterilization ink can also be applied to form letters or words. In one embodiment, the ink is applied to form the word "sterile." In one embodiment the sterilization ink is from 1-15 gsm. In another embodiment, the sterilization ink is from 1-5 gsm.

[0046] The ink may be applied by any means know to those in the art. The pattern could be formed by printing the ink. The printing may be any means that can form the pattern. Examples of useful printing means include gravure, lithographic, screen, flexographic printing, reverse gravu re, offset gravu re, various digital printing processes such as laser jet or ink jet printing, and any combination of these processes. In one embodiment, rotary screen printing, in which a rotating tubular screen is used to transfer the ink, is used to apply the ink. In another embodiment gravure printing is used to apply the ink. In one embodiment the ink being applied to the substrate may be heated or cooled to facilitate the coating process and to alter the coating thickness.

[0047] In accordance with one embodiment, a polymeric dual surface printed su bstrate which includes at least one polymeric layer, an ink layer, and a silicone release coating layer is disclosed.

[0048] Figure 2 shows the polymeric dual surface substrate (101). The first layer is a release coating layer (100). Adjacent to the release layer is a sterilization ink layer (200). Below, or beneath, the sterilization ink layer (200) is a polymeric layer (300). The polymeric substrate has two surfaces, first surface (111) and second surface (112). [0049] Figure 3 shows another embodiment of the polymeric dual surface substrate (103).

The first layer is a release coating layer (100). Adjacent to the release layer is a sterilization ink layer (200). Below, or beneath, the sterilization ink layer (200) is a polymeric substrate layer (300) with first surface (111). There is a second polymeric substrate layer (400) with second surface (112).

[0050] In accordance with an embodiment, the sterilization tape (104) comprises a printed dual surface substrate and an adhesive layer.

[0051] Figure 4 illustrates one embodiment of sterilization tape (104) of the current invention.

An adhesive layer (500) is added to the printed dual surface su bstrate (layers 100-300). The first layer is a release coating layer (100). Adjacent to the release layer is a sterilization ink layer (200). Below, or beneath, the sterilization ink layer (200) is a polymeric dual surface substrate layer (300). The polymeric dual surface substrate layer has two surfaces, first surface (111) and second surface (112). Below, or beneath, the polymeric dual surface substrate layer, adjacent to the second surface, is adhesive layer (500).

[0052] Figure 5 illustrates another embodiment of sterilization tape (105) of the current invention. The printed polymeric substrate (layers 100-400) has two polymeric substrate layers (300, 400). The first layer is a release coating layer (100). Adjacent to the release layer is a sterilization ink layer (200). Below, or beneath, the sterilization ink layer (200) is a polymeric substrate layer (300) with first surface (111). There is a second polymeric substrate layer (400) with second surface (112). At least one adhesive layer (500) is attached to the second surface (112) of the second polymeric substrate layer (400).

[0053] In any tape embodiment, an optional release liner may be added adjacent to the adhesive layer.

[0054] The problem associated with solvent coating an adhesive on a substrate already printed with sterilization indicator ink is that the coating process requires that the web be dried in-line at high temperature to remove all residual solvent from the web. This high temperature drying will cause the ink to change color irreversibly so that it cannot function as a sterilization indicator.

[0055] In one instance, the problem can be solved by using a laminate because it could print and siliconize at lower temperatures such that the ink was not activated prematurely. The construct is then laminated in place by a tape in a second pass. That lamination occurred after the drying section of the coater such that the web had cooled enough to prevent ink activation. Another approach to this problem, may be using a solvent free coating process, such as with UV curable adhesives or hot melt adhesives.

[0056] The single or double sided tape can be any known in the art. If using a double sided tape, the additional carrier layer is a propylene layer. In one embodiment, existing double coated tape MED 6408, produced by Avery Dennison, is used. MED 6408 is double coated tape used in surgical grounding pads based upon a PET removable liner layer, polypropylene carrier layer, and acrylic adhesives. In a preferred embodiment, a single coated transfer tape is used.

[0057] In one embodiment the problem can be solved by using a temperature controlled roll to support the laminate while the adhesive is applied at elevated temperatures.

[0058] The sterilization tape assembly of the current invention may contain a single adhesive layer or several adhesive layers. Each of these adhesive layers may include at least one type of adhesive. The adhesive used will have a strong bond to the polymeric material. The at least one adhesive may include a pressure sensitive adhesive. The pressure sensitive adhesive may be a hot melt adhesive, a solvent based adhesive, or an emulsion adhesive. The pressure sensitive adhesive may include a hot melt adhesive or an acrylic based emulsion adhesive to include copolymers of acrylic acid esters and optionally acrylic acid. The hot melt adhesive can be a styrene block copolymer hot melt or rubber hot melt adhesive. The pressure sensitive adhesive may also be a silicone adhesive. The adhesive may be a permanent adhesive. The permanent adhesive can be one of any of those known in the art including, but not limited to acrylate, epoxy or plastic polymers. Additionally, the at least one adhesive may be a thermally activatable or UV activatable adhesive. The thermally activatable adhesive may be any of those known in the art including, but not limited to, polyester, acrylic or polyamide adhesives. The UV activable adhesive may be any of those known in the art including, but not limited to acrylic based adhesives. One example of a possible UV cured medical grade adhesive is HPA 2922, produced by Avery Dennison. In a preferred embodiment, the adhesive layer or layers are hot melt rubber. One example of a hot melt rubber adhesive is T2700. Another is T2701, which is medical grade adhesive.

[0059] In one embodiment two different types of adhesive are used. In another embodiment, the same adhesive is used throughout. In a preferred embodiment, the same adhesive is used throughout the tape and it is acrylic based. In another preferred embodiment, a single rubber hot melt adhesive is used.

[0060] The thickness of the adhesive is dependent on specific substrate choice. In one embodiment the thickness of the adhesive is between 10 gsm (grams per square meter) and 250 gsm. In a preferred embodiment the thickness of the adhesive is between 10-80 gsm. In another preferred embodiment, the thickness of the adhesive is between 20-40 gsm.

[0061] In a specific embodiment utilizing the single coated transfer tape, the adhesive layer is between the unprinted side of the polymeric dual surface substrate and the release coating layer of the same substrate such that the final construction is a roll of self wound tape.

[0062] In one embodiment a specific process is used to produce a plastic sterilization tape based on a dual surface polymeric substrate. First, obtain a suitable polymeric substrate that can be torn to a desired length by the end user. It is preferable to obtain polymeric substrate that has been surface treated. But if not available, the polymeric substrate must be surface treated to accept sterilization indicator ink. [0063] Next, print the indicator artwork on the treated first surface of the polymeric substrate using sterilization ink. One example of suitable indicator ink is Sterisun ink, available from Sun Chemical. Any suitable indicator ink can be used.

[0064] Next, apply a suitable silicone treatment over the printed surface in order to give a release feature that enables the resulting tape to be self wound. It is important to choose a silicone treatment that will not react with the indicator ink. For example, one acceptable silicone treatment is I- 4180 silicone treatment used at Avery Dennison.

[0065] Next, cross link the silicone film. Suita ble methods include temperature cure, electron beam cure, and UV light cure. The preferred method is UV cure. It is important that the ink must not react chemically in the presence of the UV light used in this step. In a preferred embodiment, the curing takes place at room temperature and takes from a few second to up to several minutes.

[0066] Finally, laminate the printed substrate to an existing single or double coated tape by applying the first adhesive side to the underside (non-siliconized) side of the printed substrate. After the adhesive is applied, the release layer is removed. Any known laminating equipment can be used. Several examples include the Arsoma or Delta press.

[0067] In another embodiment, a single pass is utilized instead of the laminating step.

[0068] First, obtain a suitable polymeric substrate that can be torn to a desired length by the end user. It is preferable to obtain polymeric substrate that has been surface treated. But if not available, the polymeric substrate must be surface treated to accept sterilization indicator ink.

[0069] Next, print the indicator artwork on the treated first surface of the polymeric substrate using sterilization ink. One example of suitable indicator ink is Sterisun ink, available from Sun

Chemical. Any suitable indicator ink can be used.

[0070] Next, apply a suitable silicone treatment over the printed surface in order to give a release feature that enables the resulting tape to be self wound. It is important to choose a silicone treatment that will not react with the indicator ink. For example, one acceptable silicone treatment is I- 4180 silicone treatment used at Avery Dennison.

[0071] Next, cross link the silicone film. Suita ble methods include temperature cure, electron beam cure, and UV light cure. The preferred method is UV cure. It is important that the ink must not react chemically in the presence of the UV light used in this step. In a preferred embodiment, the curing takes place at room temperature and takes from a few second to up to several minutes.

[0072] Finally, apply the adhesive to the underside (non-siliconised) side of the printed substrate.

[0073] The printing, siliconizing , and adhesive application is done in a single coater pass where the silicone is cured by UV exposure. The UV exposure does not harm the ink. Since the silicone cures immediately, the adhesive can be applied in the same coating pass. The adhesive is applied while the silicone side of the substrate is in contact with a roll so that the ink is protected from heat required to apply the hot melt coating.

[0074] The resulting self wound roll of material can be further converted by such operations as slitting, die cutting, or otherwise to yield useful products.

[0075] In one embodiment, a method for indicating sterilization is used. Medical equipment, such as surgical instruments, are placed in an container, the container is wrapped in wrap material, and the material is then folded over to enclose the instruments in the wrap, in one embodiment the container is a stainless steel tray. The indicator tape is then used to securely close the wrapped bundle. The bund le is then subjected to a sterilization cycle. During the cycle, the ink on the indicator tape changes color, this indicates that the bundle has been exposed to a hospital sterilization cycle and is ready for use. At the completion of the surgery, the polypropylene wrap and tape material are discarded. [0076] in a preferred embodiment, the sterilization cycle is one of the accepted steam cycles included in ISO 11140-1 2009. The cycles in ISO 11140-1 2009 include steam tests at 121 °C and 134 °C. Per ISO 11140-1 2009., the tape must change at 2 min and 134 °C and 10 min and 121 °C, but not at .5 min and 134 °C and 3 min and 121 °C.

[0077] It will thus be seen according to the present invention a highly advantageous recyclable sterilization tape and a process for indicating sterilization has been provided. While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it will be apparent to those of ordinary skill in the art that the invention is not to be limited to the disclosed embodiment, and that many modifications and equivalent arrangements may be made thereof within the scope of the invention, which scope is to be accorded the broadest interpretation of the appended claims so as to encompass all equivalent structures and products.

[0078] The inventors hereby state their intent to rely on the Doctrine of Equivalents to determine and assess the reasonably fair scope of their invention as it pertains to any apparatus, system, method or article not materially departing from but outside the literal scope of the invention as set out in the following claims.