Applicator and manufacturing method thereof

Abstract

A liquid applicator for applying a liquid to a surface. The applicator comprises a hollow body including a wall defining an interior chamber having a closed end and an open end. The applicator further comprises a felted polyurethane foam connected to the open end of the hollow body and an alcohol-based disinfectant solution dispersed within the polyurethane foam. The polyurethane foam has a viscosity of at least 1.0 lb. f* in / (foam in 2 ) flatwise tensile strength.

Description

[Technical field]

[0001] FIELD OF THE DISCLOSURE The present disclosure relates to applicators for applying a liquid to a surface, such as surgical prep applicators. [Brief description of the drawings]

[0002] [Figure 1] 1 illustrates a side view of a liquid applicator according to some embodiments of the present disclosure. [Diagram 2] 1 shows tensile test results for foams according to some embodiments of the present disclosure and comparative foams. [Diagram 3] 1 shows the results of tensile testing of felted foam as a function of felting temperature. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0003] It is standard practice in industrialized countries to disinfect the skin prior to any invasive procedure, such as surgery, catheterization, or needle puncture, to reduce the risk of infection. These products are often referred to as skin preps or simply "preps." Antiseptic preparation of a patient's skin for such procedures traditionally involves scrubbing the affected area with an antiseptic soap solution for 30 seconds to 10 minutes. These solutions are often applied with an applicator that is a foam sponge at the end. The foam sponge is often saturated with the solution by dipping the foam sponge in the solution in an open pan or from a reservoir contained within a handle that is fluidly connected to the foam sponge. The antiseptic solution is often an alcohol-based solution that tends to cause swelling of the types of foam sponges typically used (e.g., open-cell polyester or polyether polyurethane foams) (as opposed to water-based solutions, which are fairly common in industrial applications of foam sponges and do not cause such swelling of foam sponges). Specifically, compressed (or felted) polyurethane foam can reversibly swell by about 10-15% in alcohol-based solutions, and this swelling is not expected to compromise the mechanical stability of the foam.

[0004] Felting refers to a post-foam generation process in which the foam is permanently compressed by placing it between two heated platens and compressing the foam until the compression is permanent. It is generally understood that the felting process increases capillarity, resulting in the foam being able to wick fluid better than a non-felted foam of the same foam composition. However, it has been discovered that conventional commercially available felted foams exhibit irreversible excessive swelling during the above-mentioned scrubbing process involving an alcohol-based solution, which results in delamination of the foam. More specifically, it has been discovered that during use on the skin, vigorous scrubbing with a foam-tipped applicator immersed in an alcohol-based solution can cause irreversible decompression of the felted foam, resulting in as much as 100% expansion. This decompressed foam bunches and rolls during scrubbing, thus losing its ability to scrub the skin efficiently. Furthermore, scrubbing with a swollen foam during application can cause the foam to lose its bond to the applicator (often referred to as delamination).

[0005] Thus, foam articles and related methods that provide improved dimensional stability and can consistently avoid delamination during vigorous scrubbing (even when immersed in alcohol-based solutions) are desired.

[0006] As used herein, the singular forms "a," "an," and "the" include plural referents unless the content clearly dictates otherwise. As used in this specification and the accompanying embodiments, the term "or" is used broadly to include "and / or" unless the content clearly dictates otherwise.

[0007] As used herein, the recitation of numerical ranges by endpoints includes all numbers subsumed within that range (eg, 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.8, 4, and 5).

[0008] Unless otherwise indicated, all numbers expressing quantities or ingredients, measurements of properties, and the like used in the specification and embodiments should be understood in all instances to be modified by the term "about". Thus, unless otherwise indicated, the numerical parameters set forth in the foregoing specification and accompanying list of embodiments may vary depending on the desired properties one of ordinary skill in the art would obtain utilizing the teachings of the present disclosure. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claimed embodiments, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.

[0009] In some embodiments, the present disclosure relates to a felted foam pad for applying liquid to a surface. In general, it has been discovered that certain felting process conditions result in foam articles that exhibit improved dimensional stability and resistance to delamination from the applicator handle during vigorous scrubbing. More specifically, it has been determined that a certain thermal window for felting polyurethane foam significantly improves the dimensional stability of foams soaked in alcohol-based solutions. The improved felted foam pad does not exhibit excessive swelling and stochastic delamination of the foam pad from the applicator during scrubbing procedures.

[0010] FIG. 1 illustrates a liquid applicator 100 according to some embodiments of the present disclosure. As illustrated, the liquid applicator 100 may include an elongated hollow body 110 including a wall 160 (which may serve as a handle for a user). The wall 160 may define a chamber 170 having a closed end 172 and an open end 174. The closed end 172 may be sealed in any of a variety of known ways to inhibit or prevent fluid contained within the chamber from leaking out through the closed end. For example, a cap, which may be press-fit, screwed, or otherwise attached, may seal the chamber forming the closed end 172. The open end 174 may include one or more orifices that allow fluid to flow out of the chamber 170. A pad 178 may be fluidly coupled to the open end 174 such that fluid flowing through the orifices contacts the pad 178 directly or indirectly. The pad 178 may be coupled (directly or indirectly) to the hollow body by a conventional fastening mechanism (e.g., adhesive or ultrasonic welding). Although the present disclosure has been described with respect to a particular applicator 100, it should be understood that the articles and methods of the present disclosure may be used with any applicator for facilitating scrubbing of a surface (e.g., skin) with a foam pad coupled to a handle (which may or may not be hollow) and which may have an antiseptic solution held therein.

[0011] In some embodiments, an alcohol-based (i.e., a solution having alcohol(s) present in an amount of at least 50% by weight based on the total weight of the solution) antiseptic solution can be contained within the chamber 170. Examples of suitable antiseptic solutions include the solutions described in U.S. Pat. No. 4,584,192 and U.S. Pat. No. 4,542,012. Other useful fluids include antiseptic preparations, such as iodophor skin tinctures, such as "Duraprep™ Surgical Solution" available from 3M. In some embodiments, the antiseptic solution can include an antibacterial agent, such as iodine, iodine complexes (e.g., iodophors), chlorhexidine, chlorhexidine salts (e.g., chlorhexidine gluconate and chlorhexidine diacetate), or combinations thereof. Other exemplary antimicrobial agents include C2-C5 lower alkyl alcohols, fatty acid monoesters of glycerin and propylene glycol, polymers containing (C12-C22) hydrophobes and quaternary ammonium groups, polyquaternary amines (e.g., polyhexamethylene biguanide), quaternary ammonium silanes, silver, silver salts (e.g., silver chloride), silver oxide and silver sulfadiazine, methyl, ethyl, propyl and butyl parabens, octenidene, peroxides (e.g., hydrogen peroxide and benzoyl peroxide), and the like, and combinations thereof.

[0012] In some embodiments, the pad 178 can be prepared from a variety of commercially available materials having a wide range of compression set ratios (i.e., densities) and porosities. By varying the compression set ratio and porosity of the foam sponge, the applicator can be constructed to apply a variety of antiseptic solution compositions, viscosities, and volumes.

[0013] In some embodiments, the pad 178 may include (or be formed from) a polyurethane foam (e.g., an open-cell polyester or polyether polyurethane foam). Polyurethane foams are generally prepared by the reaction of one or more active hydrogen-containing compounds (i.e., polyols), one or more polyisocyanates, usually at least one reaction catalyst, and a cell stabilizer in the presence of a blowing agent, such as water. The cellular polymer structure of polyurethane foam has a skeletal framework of relatively heavy strands that form the contours of the cellular structure. The skeletal framework is connected by very thin membranes that form the cell walls, often called windows. In open-cell foams, in each cell, some of the windows are open or ruptured, thus forming an interconnected network that is open to fluid flow (liquid or gas). In some embodiments, the foam may be of the type of material described in U.S. Pat. No. 6,841,586 or U.S. Pat. No. 8,247,466, the entireties of which are incorporated herein by reference.

[0014] In some embodiments, the porosity of the pad 178 may be selected so that the pad releases a uniform amount of liquid when pressed against the surface onto which the liquid is to be dispensed. In some embodiments, for surgical preparation applications, the porosity of the pad before felting may be about 10-150 pores per linear inch, or about 10-90 pores per linear inch.

[0015] A wide variety of pad shapes are known. Generally, pad 178 may be oval, square, or rectangular in shape and may be uniform (or substantially uniform) in thickness. In some embodiments, pad 178 may have a thickness of 0.1 inches to 5 inches, or 0.2 inches to 2 inches. In some embodiments, pad 178 may have a working surface area (i.e., the area of ​​the surface of the pad that is intended to contact the skin during scrubbing) of 0.1 square inches to 2 square inches, or 0.25 square inches to 1.5 square inches. These relatively small working surface areas may be particularly useful in situations where delamination of the foam pad from the applicator handle is a concern, since shear stress increases as a function of surface area (assuming a constant scrubbing force).

[0016] As mentioned above, felting refers to a post-process in which foam is permanently compressed, conventionally by placing a sheet between two heated platens and compressing the foam until the compression is permanent. Generally, felted foams have increased capillarity, which is known to allow the foam to wick fluids better than unfelted foams of the same foam composition. The compression ratio is calculated as the thickness before felting to the thickness after felting. The compression ratio is commonly referred to as hardness. For example, a foam compressed to one-third of its original thickness is a felt of hardness 3, and the compression ratio is 3. A foam compressed to one-fifth of its original thickness is a felt of hardness 5.

[0017] Traditionally, while compressed, the foam is heated to a temperature of 340-380°F (171-193°C) for 10-60 minutes to achieve felting. The resulting felted foam exhibits excellent dry internal strength and compression set that is difficult to reverse by normal mechanical means. Higher temperatures and times have generally been considered undesirable because they are not believed to provide additional value and may result in excessive thermal degradation. However, it has been unexpectedly discovered that compression of unfelted foam at temperatures above the traditional temperature range significantly improves the felting strength and the foam's resistance to reduced pressure when scrubbed with an alcohol-based disinfectant solution. Specifically, it has been discovered that compression of unfelted foam at temperatures of at least 430° F. (at felting temperatures below 430° F., the resulting foam does not have the desired increased internal strength) and up to 450° F. (at felting temperatures above 450° F., the foam begins to decompose) for at least 1 minute, at least 10 minutes, at least 20 minutes, or at least 30 minutes results in a felted foam pad with significantly improved felting strength and resistance to reduced foam pressure when scrubbing with an alcohol-based disinfectant solution.

[0018] In some embodiments, the foam pads of the present disclosure may be felted by compressing the foam to one-half (1 / 2) to one-twentieth (1 / 20) of its initial thickness, or to one-third (1 / 3) to one-eighth (1 / 8) of its initial thickness under the heating conditions described above. In some embodiments, felted foam pads having a compression ratio of 2 to 4 may be particularly useful as a result of the desired balance of fluid handling capabilities and comfort on the patient's skin during scrubbing.

[0019] In some embodiments, the foam pads of the present disclosure may be double felted. As used herein, double felting refers to a pad that is subjected to a first felting process in the conventional temperature range (temperatures of 340-380°F (171-193°C) for 10-60 minutes) and a second felting process in the temperature range of the present disclosure (430°F or higher and 450°F or lower for at least 1 minute, at least 10 minutes, at least 20 minutes, or at least 30 minutes). Such double felting may be achieved, for example, by subjecting a commercially available felted foam to a felting process employing the high temperature range of the present disclosure.

[0020] Internal felting strength, or resistance to felt inversion, can be described as the force required to pull the two faces of the foam apart along the felting axis, and is also called flatwise foam tensile strength. As used herein, the test method for determining flatwise foam tensile strength was adapted from ASTM C297 for use with soft foams. 1. A 1.5 x 1.5 inch piece of felted foam is glued between two flat metal T-plates. The plates are glued so that the felted axis of the foam is perpendicular to the flat surfaces of the plates. 2. Using a tensile tester, measure the force to pull the plates apart at 12 inches / minute until the foam reaches 125% of its felted thickness. 3. The total work, or integral of the force versus distance curve, is calculated. The result is divided by the cross-sectional area of ​​the foam sample. The total work required to separate the two foam faces is higher for a foam with a stronger felt for a given initial thickness and felt hardness.

[0021] In some embodiments, the felted foam pad has a resistance to at least 0.5 lbs according to the test method of the present disclosure. f* in / (foam in 2 ), at least 1.0 lb f* in / (foam in 2 ), or at least 1.5 lbs. f* in / (foam in2 ) flatwise tensile strength.

[0022] In some embodiments, the present disclosure may further relate to a method of manufacturing the foam pad described above. The method may include providing an unfelted or conventional felted polyurethane foam, such as an open-cell polyester or polyether polyurethane foam. The method may then include compressing the unfelted polyurethane foam, if unfelted, to 1 / 2 to 1 / 20 of its initial thickness (e.g., by placing it between two platens and applying a pressing force through the platens). The method may then include subjecting the compressed foam to a temperature of 430° F. or higher and 450° F. or lower for at least 1 minute, at least 10 minutes, at least 15 minutes, at least 20 minutes, or at least 30 minutes.

[0023] In some embodiments, the present disclosure may further relate to a method of using the applicator 100 described above to prepare a site (e.g., a surgical site) on a mammalian skin. The method may include introducing an alcohol-based solution to the foam pad 178 (e.g., such that the foam pad 178 is saturated or nearly saturated with the solution) and then contacting (e.g., scrubbing) the site with the foam pad for at least 30 seconds, at least 1 minute, at least 2 minutes, at least 3 minutes, at least 4 minutes, at least 5 minutes, at least 6 minutes, at least 7 minutes, at least 8 minutes, at least 9 minutes, or at least 10 minutes. For purposes of this application, "scrubbing" refers to any shear action that the foam pad undergoes while in contact with the skin site. For example, "scrubbing" can refer to applying a downward force in a direction perpendicular (or substantially perpendicular) to the skin site while simultaneously moving the pad in a direction parallel (or substantially parallel) to the skin site (e.g., a back-and-forth motion, a rotational motion, a combination of a back-and-forth motion and a rotational motion). As discussed above, as a result of the stronger "internal welds" of the felted foam of the present disclosure, during such extended scrubbing, the felted foam pad of the present disclosure resists reduced pressure (or reverse felting) and therefore resists delamination of the felted foam pad from the applicator handle.

[0024] The operation of the present disclosure will be further described with reference to the following detailed examples. These examples are provided to further explain the various embodiments and techniques. However, it should be understood that many variations and modifications may be made while remaining within the scope of the present disclosure. EXAMPLES

[0025] Foams manufactured by FXI Holdings, Inc. ("FXI", Radnor, PA) having product code FLTZ93MA were used in all examples. The method for making these foams can be found in U.S. Patent No. 6,371,606, assigned to FXI, column 4, lines 3-5, line 42. Briefly, the method involves forming a closed-cell polyurethane foam by reacting a polyether polyol with a polyisocyanate in the presence of a catalyst, a blowing agent, a foam stabilizer, and optionally other blowing aids, reticulating the foam by flame treatment, and felting by compressing between heated plates. EXAMPLES

[0026] Felted foam samples from two different processes (foam supplied by FXI and felted by UFP Technologies, Inc. (Newburyport, MA, "UFP")) were selected for the experiment. These two foam samples are referred to as untreated foam. Both foam samples were 0.395 inches thick and had a pore density of 93 pores per inch (ppi). The only difference was that the felting was done at a compression ratio or hardness of 3.8 and 4.0.

[0027] The foam was refelted (double felted) by lightly compressing it between two stainless steel plates at 0.12 pounds per square inch (PSI) pressure and placing it in a preheated oven at 455° F. The foam was heat treated for 45 minutes. At the end of the experiment, the temperature of the stainless steel plates was measured with an IR gun and determined to be approximately 355° F.

[0028] The dual-felted foams were found to have a thickness reduction of approximately 0.025-0.05 inches. This is believed to be due to internal melting and resintering of the flattened foam cells. The dual-felted foams were slightly darker in color than the untreated foams. After cooling, the dual-felted foams were attached to a 10.5 mL applicator using a hot glue gun. The dual-felted foams were each filled with 10.5 mL of a tinted 70% isopropanol solution and scrubbed for 2 minutes on a cardboard template using a back-and-forth and side-to-side motion covering an area of ​​1 inch by 5 inches. The untreated foams (foams that did not receive a second heat treatment) unfelted, rippled and knotted in less than 5 seconds. The dual-felted foams, on the other hand, held up throughout the entire 2 minute scrub. No knotting or visible unfelting of the treated foams was observed, although some ripples did occur. This test was repeated using excised porcine skin as the scrubbing substrate with identical results. Untreated foam felted at 4.0 swelled approximately 150%, while the double-felted foam swelled only 11%. EXAMPLES

[0029] As shown in Figure 2, tensile testing of treated and doubly felted foam (0.75 inch diameter circular pieces) in the z-direction (the horizontal or short axis of the foam) showed that the doubly felted foam samples had substantial improvements in both stiffness (slope of initial deformation) and yield strength (sharp change in slope). These data indicate that untreated felted foam had substantially improved internal strength due to thermal post-treatment under pressure. EXAMPLES

[0030] A single foam was dispensed by the FXI and felted by the FXI for 10 minutes at temperatures of 375° F., 413° F., and 450° F. Tensile tests of the foam (0.75 inch diameter circular pieces) in the z-direction (the transverse or short axis of the foam) show substantial improvements in both stiffness (slope of initial deformation) and yield strength (sharp change in slope), as shown in Figure 3. These data indicate that the internal strength of the foam increases proportionally with felting temperature. EXAMPLES

[0031] Foams were supplied by FXI and samples were felted at 375°F by UFP or 450°F by FXI (0.38-0.40 inch thickness, 3.8-4.0 hardness, 90-100 ppi porosity). Tensile testing of foams in the z-direction was performed according to ASTM C297 with some modifications. Briefly, foams were cut into 1.375 x 1.375 inch squares, attached between two flat metal plates with double-sided adhesive tape, and tensile testing in the felting axis was performed at a rate of 12 inches / min to a displacement of 0.5 inches, with values ​​reported as work per area of ​​foam (area under the force vs. displacement curve). Foams were tested either dry or saturated with 70% isopropanol. Results are presented in Table 1. These data indicate that the increased foam strength from high temperature felting is maintained after the foam is exposed to isopropanol.

[0032] [Table 1] EXAMPLES

[0033] The foam was supplied by FXI Corp. and felted at 375°F by UFP or 450°F by FXI. Foam samples (1.375 x 1.375 in. square, 0.38-0.40 in. thickness, 3.8-4.0 hardness, 90-100 ppi porosity) were attached to a plastic applicator using hot plate welding. The attached foam was filled with 10.5 mL of isopropanol and scrubbed on a cardboard substrate for up to 3 minutes. At the end of the scrubbing, the foam thickness was measured and compared to the foam thickness before scrubbing, and the percent thickness increase was calculated. If the foam separated (peeled off) from the applicator before 3 minutes, the time was recorded. The results are provided in Table 2.

[0034] [Table 2]

[0035] The data shows that increasing the felting temperature resulted in less foam swelling and less foam delamination from the applicator. EXAMPLES

[0036] Single foams were delivered by the FXI and felted by the FXI at various temperatures and times. The foams had a thickness of 0.38 inches, a hardness of 4.0, and a porosity of 90-100 ppi. Tensile testing of the foams in the z-direction was performed according to ASTM C297. Briefly, the foams were cut into 1.375 x 1.375 inch squares, attached between two flat metal plates with double-sided adhesive tape, and tensile testing in the felting axis was performed at a rate of 12 inches / min to a displacement of 0.5 inches, with values ​​reported as work per area of ​​foam (area under the force vs. displacement curve). Results are provided in Table 3.

[0037] [Table 3]

[0038] These data show that for a 10 minute felt time, a felt temperature of about 413° F. is preferred for increased scrubbing performance. At longer felt times, lower temperatures can achieve similar foam internal strength as the 10 minute higher temperature felting. EXAMPLES

[0039] Experiments were conducted designed to evaluate the performance of foams (FXI Corp) felted at various temperatures and times. The conditions are shown under foam type in Table 4. For example, the first foam was felted at a hardness of 3.8, had a thickness of 0.395 inches, the felting temperature was 375° F., and the felting time was 10 minutes.

[0040] The foam was attached to an applicator and used to topically apply 10.5 mL of 70% isopropanol to a 1 x 5 inch area of ​​ex-vivo porcine skin by vigorously scrubbing back and forth and side to side for a total of 2 minutes. After the scrubbing period was completed, the foam was evaluated for swelling, nodding and waviness.

[0041] [Table 4]

[0042] Increasing the felting temperature and increasing the time at the lower temperatures resulted in foams with minimal swelling (less than 20%) for foams felted for 30 minutes at 375° F., 10-30 minutes at 413° F., and 10 minutes at 450° F. The results are provided in Table 4. The double felted foam showed minimal swelling of about 12%.

[0043] Data for foam nodding and rippling followed the same trends as the swelling data. Foams felted at higher temperatures lasted the full 120 seconds without nodding or rippling. At lower temperatures (e.g., 375°F), the time to nodding and rippling extended from 20 seconds at 375°F / 10 minutes to just over 100 seconds at 375°F / 30 minutes as felting time increased. Increasing the temperature to 413°F with a shorter 10 minute felting time resulted in foams that nodulated and rippled in about 60 seconds. Dual felted foams did not nodulated or rippled at 120 seconds. Results are provided in Table 5.

[0044] [Table 5]

Claims

1. 1. A liquid applicator for applying a liquid to a surface, said applicator comprising: a hollow body including a wall defining an interior chamber having a closed end and an open end; a felted polyurethane foam connected to the open end of the hollow body; an alcohol-based disinfectant solution dispersed within the polyurethane foam; The polyurethane foam has a flatwise tensile strength of 1.0 lb. ｆ＊ in / (in of foam ２ ) or more, a liquid applicator.

2. The liquid applicator of claim 1 , wherein the felted polyurethane foam comprises an open-cell polyester or polyether polyurethane foam.

3. 3. The liquid applicator of claim 1, wherein the pad has a porosity of 10 to 150 pores per linear inch before felting.

4. 3. The liquid applicator of claim 1, wherein the antiseptic solution comprises iodine, an iodine complex, chlorhexidine, a chlorhexidine salt, a C2 to C5 lower alkyl alcohol, a fatty acid monoester of glycerin and propylene glycol, a C12 to C22 hydrophobic material and a polymer containing a quaternary ammonium group, a polyquaternary amine, a quaternary ammonium silane, silver, a silver salt, silver oxide, silver sulfadiazine, methyl, ethyl, propyl, or butyl paraben, octenidene, or peroxide.

5. The liquid applicator of claim 1 or 2, wherein the antiseptic solution comprises iodine, an iodine complex, chlorhexidine, or a chlorhexidine salt.

6. 1. A method of preparing a site on the skin of a mammal, the method comprising: Providing a liquid applicator according to claim 1 or 2; scrubbing said area with said felted polyurethane foam for at least 1 minute.

7. The method of claim 6 , wherein the site on the skin of the mammal comprises a surgical site.

8. 1. A method for producing a felted polyurethane foam, said method comprising: Providing a polyurethane foam; compressing the foam to one-half (1 / 2) to one-twentieth (1 / 20) of the foam's initial thickness; and subjecting the polyurethane foam to a temperature of at least 430°F and at most 450°F for at least 5 minutes.

9. The method of claim 8 wherein the polyurethane foam is an open-cell polyester or polyether polyurethane foam.

10. 1. A method of preparing a site on the skin of a mammal, the method comprising: Providing a felted polyurethane foam prepared according to the method of claim 8 or 9; connecting said felted polyurethane foam to a handle; introducing an alcohol-based disinfectant solution into the polyurethane foam; scrubbing the area with the felted polyurethane foam for at least 30 seconds.

11. 11. The method of claim 10, wherein the antiseptic solution comprises iodine, an iodine complex, chlorhexidine, a chlorhexidine salt, a C2-C5 lower alkyl alcohol, a fatty acid monoester of glycerin and propylene glycol, a C12-C22 hydrophobe and a polymer containing a quaternary ammonium group, a polyquaternary amine, a quaternary ammonium silane, silver, a silver salt, silver oxide, silver sulfadiazine, methyl, ethyl, propyl, or butyl paraben, octenidene, or peroxide.

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