Patent Application
20110077608
The present invention relates to an adhesive bandage to be applied onto the skin, particularly an adhesive bandage for use on skin wounds that are subjected to compressive force.
There are many types of wounds to the human body. They may be open or closed. Open wounds include incisions or incised wounds, lacerations, abrasions (grazes), puncture wounds, penetration wounds and gunshot wounds. Closed wounds include contusions (bruises), hematomas and crushing injuries.
Adhesive bandages intended for use on the skin, protecting the skin from injuries or the wound(s) from dirt and guaranteeing the efficacy of medicaments applied topically, typically include at least one film made of a liquid-impermeable material that also prevents contamination of the wound.
Conventionally, at least one pad comprising at least one absorbent material and at least one adhesive segment is associated to this film in order to enable fixation of the adhesive bandage to the user's skin. Preferably, the adhesive element is positioned on the adhesive bandage in such a manner that the region intended to be in contact with the wound (the pad) does not have adhesive, since the presence thereof could entail maceration at the wound upon removal or replacement of the adhesive bandage.
In order to accelerate the healing of the wound and enable skin respiration, the film is permeable to gas and may further contain a plurality of through bores.
With a view to increase more and more the efficacy and the comfort provided by the adhesive bandage, a number of improvements in this extremely efficient basic concept were developed, as for instance, the improvement of the materials used or the form of alterations in the coloration of the adhesive bandage.
In some cases, adhesive bandages are used where they are under a compressive force. For example, if a person has a wound under an article of clothing, the clothing will exert force on the bandage and wound, thus compressing the adhesive bandage.
Such is the case when a person has a blister. Blisters are small swellings of the skin that contains watery fluid. They are caused by friction from shoes or clothing which rubs repeatedly on the skin, thus causing friction burns. The body responds to the friction by producing fluid. The fluid builds up beneath the part of the skin being rubbed, causing pressure and pain.
Blisters are best treated by allowing them to be exposed to air, so that the area can dry and the blister be reabsorbed into the skin. Other wounds are often covered with adhesive bandages, protecting the wound(s) from dirt or contamination. In the case of blisters, most people do not have the time to wait for healing to occur and must wear clothing or shoes over the blister. To treat a blister when clothing or shoes are worn over it, a user often covers the blister with an adhesive bandage. The pad absorbs any fluid leaking from the blister and provides a cushion between the blister and the surface of the shoe or sock.
To avoid blisters, people “breaking in” new shoes will often wear athletic tape or adhesive bandages on their feet at the locations where the new shoes exert friction and pressure on the foot. There are several problems with these practices. Athletic tape prevents friction, but does not address the issue of cushioning the blister. Adhesive bandages with pads cushions the area, but the pad deforms under the pressure of the clothing or shoes, minimizing its ability to cushion the area.
In summary, adhesive bandages providing additional cushioning to wounds or areas of the skin that are subjected to compressive forces are needed.
The present invention relates to an adhesive bandage for use on wounds placed under compressive force, which includes a support layer having a top side and an opposing bottom side, an adhesive layer deposited onto the bottom side of the support layer, a substantially sealed cushion pad associated with the adhesive layer, and an absorbent pad bonded to the cushion pad.
The present invention will now be described in greater detail with reference to embodiments represented in the drawings.
a is a cross-sectional side view of a second cushion pad embodiment of the adhesive bandage of the present invention;
b is a top sectional view along plane C-C of the second cushion pad embodiment illustrated in
The support layer may have various shapes, e.g. rectangular, circular, oblong, etc. The shape of adhesive bandage 10 is defined by the shape of support layer 20. The composition of the support layer may vary, but it is preferably made from a polyolefin, polyurethane polymer, polyethylene, vinyl polyethylene acetate, polyurethane foam film, and may further be made from a textile non-woven fabric, rubber, or other materials known in the adhesive bandage arena.
By preference, polymers used to make the support layer exhibit viscosity of about 500 to 500,000 centipoises at temperatures lower than 190° C., or about 1,000 to 30,000 centipoises at temperatures lower than 190° C., or about 3,000 to 15,000 centipoises at temperatures lower than 190° C.
The support layer may be impermeable to liquid, but permeable to gas, which allows the wound and the skin to which the adhesive bandage 10 is adhered to breath. For this, the support layer has pores of such a size that will allow only the passage of gases, which have molecules of extremely size.
Finally, one can conceive a support layer that is perforated for more ventilation of the skin. However, the support layer may still be totally impermeable to gases, when necessary.
Adhesive layer 30 is associated with support layer 20. Bonding layer 35 may be in the form of an adhesive, and is associated with top side 54 of cushion pad 50. Adhesive layer 30 comprises an adhesive, so that it will be able to stick to the user's skin. Bonding layer 35 may comprise an adhesive to bond cushion pad 50 to absorbent pad 40.
In general, any of a variety of pressure-sensitive adhesives can be utilized as the adhesive layer and the bonding layer in the present invention. In particular, pressure-sensitive adhesives that are biocompatible with human skin are typically utilized. Moreover, an adhesive of the present invention is also either generally water soluble or generally insoluble, or dispersible in an aqueous environment. For instance, one preferred, commercially available dispersible pressure-sensitive adhesive is sold under the trade name of HL-9415-X and is available from H.B. Fuller Company. Another suitable adhesive includes about 10-75% by weight of a polyalkyloxazoline polymer, 10-75% by weight of a functional diluent comprising a hydroxy compound or a carboxylic acid compound, and 5-50% by weight of a tackifier.
The water-dispersible polymeric component can include, for example, surfactants such as poly(ethylene oxide) alkylphenyl ethers, such as those sold under the trade names IGEPAL.CO and IGEPAL.CA (available from Rhone-Poulenc, Inc.); poly(ethylene oxide) lauryl, cetyl, and oleyl ethers such as those sold under the trade name BRIJ (available from ICI Americas, Inc.); poly(ethylene oxide) laurate; poly(ethylene oxide) oleate; sorbitan oleate; ethylene oxide/propylene oxide block copolymers such as those sold under the trade names PLURONIC and TETRONIC (available from BASF Corporation); and organic phosphate esters, such as those sold under the trade name GAFAC PE-510 (available from International Specialty Products). Examples of other components include, but are not limited to, poly(acrylic acid); poly(vinyl alcohol); poly(N-vinyl pyrrolidone); poly(acrylamide); poly(alkoxyalkyl(meth)acrylates), such as 2-ethoxy ethyl acrylate, 2-ethoxy ethyl methacrylate, 2-(2-ethoxyethoxy) ethyl acrylate, and 2-methoxy ethyl acrylate (available from SARTOMER Company, Inc.); poly(vinyl methyl ether); poly(vinyl methyl ether: maleic anhydride), sold under the trade name GANTREZ (available from International Specialty Products); poly(ether polyols), such as poly(propylene glycol) and the like, such as those sold under the trade name SANNIX (available from Sanyo Chemical Industries); copolymers thereof, and the like. Copolymers of these and alkyl(meth)acrylate esters or vinyl esters are also suitable. Gums such as those derived from okra and guar may also be used.
Still another suitable pressure-sensitive adhesive includes about 10% to about 80%, by weight, of an alkali soluble polymer; about 0 to about 30%, by weight, of a poly(vinyl methyl ether); about 30% to about 70%, by weight, of a tackifying resin; and about 5% to about 30%, by weight, of a suitable plasticizer. Still other examples of suitable adhesives include HX 9236-01 or HX 9237-01 hot melt adhesives, which are obtainable from ATO Findley, Inc.
The adhesive layer and bonding layer may comprise hydrocolloids. The hydrocolloid element used may be any substance that has a good performance in this utilization, as for example, sodium carboxymethylcellulose, pectin, xanthan gum, polysaccharides, sodium or calcium alginates, chitosan, seaweed extract (cageenan), polyaspartic acid, polyglutamic acid, hyaluronic acid or salts and derivatives thereof, among others.
Hydrocolloids, just as sodium carboxymethylcellulose and pectin, among others, are agents that form gels as soon as they come into contact with the bodily fluids from the wound. When used in adhesive bandages, these hydrocolloids are combined with elastomers and/or adhesives. Preferably, the adhesive bandage should guarantee a humid environment but without saturation, cicatrisation, which is a situation suitable for acceleration of the healing,
Pectin is a complex-structure polysaccharide, extracted from vegetable species (as for example, peels from citric fruits or apple pulp), which has a highly hydrophilic structure and, as a result, associate easily with the water molecules of the bodily fluids from the wound, forming a viscous gel on the injury bed. Its chemical similarity with alginates causes the physical properties of absorption and gel formation to resemble each other.
Carboxymethylcellulose, in turn, is a cellulose derivative, formed by reaction of cellulose with alkalis (such as, for example, sodium, potassium, calcium, etc., hydroxide). It is the nature of combined alkali that imparts the ionic characteristic of carboxymethylcellulose (when sodium hydroxide is used, sodium carboxymethylcellulose is formed). Just as in the case of pectin, carboxymethylcellulose dissolves rapidly in the water coming from the liquids that emanate from the wound, forming a gel on the wound with controlled viscosity.
As an additional advantage of the use of hydrocolloids, it should be noted that both pectin and carboxymethylcellulose form a gel with acidic characteristics (pH of about 4), functioning as a bactericidal agent.
Before the use of adhesive the bandage, the hydrocolloid is substantially inert to water vapor; but, as soon as the gelling process begins, the adhesive bandage becomes progressively more permeable. The gelling process continues, provided that the injury continues to exude bodily fluids, until the whole hydrocolloid is used up, at which time saturation of the adhesive bandage is reached, and it should be replaced.
The adhesive element used may be any conventional adhesive know for such use, as for example pressure acrylic adhesives, among others. Additionally, such an adhesive may contain a resin for increasing adhesion, a cohesion increasing agent, an absorption agent (preferably a polyacrylate superabsorbent, a polyacrylate salt superabsorbent or a mixture thereof), a plasticizer and optionally a pigment. The adhesive layer may further be configured in discontinuous patterns, arranged in lines, screen, spray or any other which a person skilled in the art understands as discontinuous, composed by an elastomeric base. In some embodiments, the adhesive layer and the bonding layer are comprised of the same material.
Over the adhesive layer is positioned at least one cushion pad. The cushion pad is sized to cover less area than the support layer, so that in use the adhesive layer is in contact with the user's skin, but preferably does not contact the wound surface.
Over the cushion pad is positioned at least one absorbent pad, which substantially covers the wound area and is in contact with the wound surface. The absorbent pad is sized to cover less area than, or no more than up to, the area of the cushion pad. The bonding layer bonds the absorbent pad to the top side of the cushion pad.
The absorbent pad can be made from any type of material commonly used in the art in forming such pads. The absorbent pad can be made from cellulose fiber or non-biodegradable or biodegradable foam. Also, the absorbent pad may be wrapped or laminated with a cover of plastic or treated cellulose to prevent bonding to the wound tissue.
In some embodiments, the absorbent pad can also be dispersible in water to facilitate disposal of the adhesive bandage. Water-dispersible foam composites are one example of a suitable absorbent pad that can be used in the present invention. Other suitable materials that can be used for the absorbent pad include lightly cross-linked tissue structures, absorbent films, and the like.
In some embodiments, the absorbent pad can comprise hydrocolloids such as those described above. In these embodiments, the absorbent pad is in the form of an absorbent adhesive layer, and will directly bond with the cushion pad, thus serving the dual function of the bonding layer and the absorbent pad. The adhesiveness of the absorbent pad is controlled by the adhesiveness of above listed elastomers and adhesives, and the ratio of hydrocolloid to elastomers and/or adhesives in the absorbent pad. Blends of hydrocolloids and elastomers and/or adhesives are discussed in U.S. patent application Ser. No. 11/743,258, herein incorporated by reference.
The absorbent pad may comprise discontinuities selected from the group consisting of pores, slots, perforations, cracks, grooves, openings, holes or the like. The absorbent pads may comprise an open area, referring to the sum of the area of discontinuities within the absorbent pad, of about 10% to 90%, or of about 25% to 60% or still of about 30 to 40%. The pore area may be about 0.001 to 10 mm2, or from 0.1 to 1 mm2, or about 0.1 to 0.5 mm2.
The cushion pad provides cushioning to help protect a wound or blister, as well as to provide comfort for the user, specifically for wounds or blisters placed under compressive force. The cushion pad comprises a material that will deform when subjected to a compressive stress, but will recover its original shape when the stress is released. The cushion pad may be in the form of a foam comprised of polymers such as polystyrene, polyolefin, rigid polyurethane, flexible polyurethane, polystyrene and polyvinyl chloride. The foams have closed cell pores due to sealing of the cushion pads, usually filled with air. The volume of pores comprise about 80% to about 99%, or about 90% to about 97%, of the volume of the foam. Typical average pore diameter is about 0.1 mm to about 1.0 mm. One skilled in the art, after having the benefit of this disclosure will be able to ascertain many combinations of material (polymer chemistry, molecular weight), porosity and pore size that may be used to achieve the performance required for the cushion pad.
Top side 54, bottom side 52 and sides 56a and 56c of cushion pad 50 are substantially sealed, so as to provide closed pores, or cells within the body of the cushion pad. By substantially sealed, it is meant that the perimeter of the cushion pad is sealed or otherwise treated, so as to prevent air contained within pores or cells within the body of the cushion pad to be forced from the cushion pad upon subjection to compressive forces, to the extent that the average percent thickness recovery of such substantially sealed cushion pad is at least 80% when subjected to a force of 8 Newtons (N) for five minutes.
a illustrates a cross-sectional side view a second embodiment of a cushion pad of the present invention. Cushion pad 60 has top 64, bottom 62, sides 66a and 66c, and internal wall structure 68.
b is a top cross-sectional view along plane C—-C of the second cushion pad 60 embodiment illustrated in
The process of manufacturing the adhesive bandage 10 of the present invention may be any of those conventionally known to produce adhesive bandages. Support layer 20, cushion pad 50, absorbent pad 40, and first adhesive layer 30 can be obtained by any methods available at present. For example, an extrusion process may be used for obtaining support layer 20. In the same way, the adhesive layers 30 and 35 can be made in any known manner. A support layer as described herein is obtained and an adhesive layer as described herein is applied to the bottom surface of the support layer. The cushion pad is then associated to the adhesive layer. A bonding layer is then applied to the bottom side of the cushion pad. The absorbent pad is then associated with the bonding layer, thus bonding the absorbent pad to the cushion pad.
Support layer 120 and cushion pad 150 have been described earlier. In this embodiment, absorbent adhesive layer 140 comprises a hydrocolloid, and thus serves the dual function of absorbent and adhesive layers. As discussed above, hydrocolloids include, for example, sodium carboxymethylcellulose, pectin, xanthan gum, polysaccharides, sodium or calcium alginates, chitosan, seaweed extract (cageenan), polyaspartic acid, polyglutamic acid, hyaluronic acid or salts and derivatives thereof, among others.
As mentioned above, the hydrocolloids are blended with elastomers and/or adhesives to form absorbent adhesive layer 140. The adhesiveness of absorbent adhesive layer 140 is controlled by the adhesiveness of above listed elastomers and adhesives, and the ratio of hydrocolloid to elastomers and/or adhesives in absorbent adhesive layer 140. Blends of hydrocolloids and elastomers and/or adhesives are discussed in U.S. patent application Ser. No. 11/743,258, herein incorporated by reference.
In one embodiment, adhesive bandage 110 may have high adhesiveness to the skin in the peripheral region 142 (peripheral to cushion pad 150), combined with less adhesiveness in the pad region 144, thus combining healing capacity with comfort of the user at the time of replacement.
The adhesiveness in the pad region 144 may be 10% less than the adhesiveness in the peripheral region 142. For example, the adhesiveness value in the pad region 144 is may be at least 36N/cm2 and the adhesiveness value in the peripheral region 142 may be at least 40 N/cm2. More preferably, the adhesiveness value in the pad region 144 is of at least 25 N/cm2 and the adhesiveness value in the peripheral region 142 is of at least 36 N/cm2. Still more preferably, the adhesiveness value in the pad region 144 is preferably of at least 10 N/cm2 and the adhesiveness value in the peripheral region 142 is of at least 25 N/cm2. Other preferred adhesiveness values in the pad region 144 are 12 N/cm2, 8 N/cm2 and 4 N/cm2, and adhesiveness values in the peripheral region 142 are 15 N/cm2, 10/cm2 and 8 N/cm2, respectively. Still preferably, other adhesiveness values in the pad region 144 may be, at the most, 10 N/cm2, preferably 6 N/cm2 and more preferably 1 N/cm2.
The process of manufacturing the adhesive bandage 110 of the present invention comprises the steps of obtaining support layer 120 as defined before; obtaining absorbent adhesive layer 140; obtaining cushion pad 150; associating cushion pad 150 and support layer 120; and associating adhesive layer 140 with support layer 120 and cushion pad 150.
The adhesive bandages of the invention are ideally suited to deliver one or more active ingredients such as therapeutics to the surface of the skin. Illustrative classes of active ingredients that may be delivered to the skin via the adhesive bandages of the invention include, but are not limited to, antibiotics, analgesics, antipyretics, antimicrobials, antiseptics, antiallergics, anti-acne, anesthetics, anti-inflammatories, hemostats, cosmetics, vitamins, vasodilators, emollients, pH regulators, antipruritics, counterirritants, antihistamines and steroids. Specific active ingredients that may be delivered to the skin via the dressings of the invention include chlorhexidine, neomycin sulfate, polymyxin-B sulfate, zinc bacitracin, benzalkonium chloride, cetylpyridinium chloride, bupivacaine, tetracaine, cincaine, lidocaine, benzocaine, silver sulfadiazine, hydrocortisone, metandienone, trypsin, tolazoline, heparin, pramoxine, aloe vera, tretinoin, retinol, retinaldehyde, menthol, capsaicin, alpha hydroxy acids and vitamins such as Vitamin E.
When contained in the adhesive bandages of the invention, one or more active ingredients may be contained primarily or exclusively in the absorbent pad 40 of the adhesive bandage or primarily or exclusively in the absorbent adhesive layer 140.
Various embodiments of the invention have been set forth above. Each embodiment is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. For instance, features illustrated or described as part of one embodiment, can be used on another embodiment to yield a still further embodiment. Thus, it is intended that the present invention cover such modifications and variations as come within the scope of the appended claims and their equivalents.
The present invention may be better understood with reference to the following example.
Tables 1 and 2 show the thickness recovery for sealed cushion pads (closed cell) versus unsealed cushion pads (open cell).
The table shows an adhesive bandage with a closed cell cushion pad had an average thickness recovery of 82.4% and the adhesive bandage with open cell (sponge) cushion pad presented an average thickness recovery of 73.3%, which is statically different (p<0.01). The adhesive bandage with the closed cell pad presented a better thickness recovery than the adhesive bandage with the open cell (sponge) pad.
