CA1046373A

CA1046373A - Combination absorbent dressing and flexible cooling device

Info

Publication number: CA1046373A
Application number: CA219,705A
Authority: CA
Inventors: Theodore F. Kozak
Original assignee: Union Carbide Corp
Current assignee: Union Carbide Corp
Priority date: 1974-03-13
Filing date: 1975-02-10
Publication date: 1979-01-16
Also published as: SE406418B; DK99775A; DE2508520A1; NL7502945A; NO136738B; SE7502780L; CH600890A5; US3871376A; HK29378A; DK136098C; ATA190075A; NO136738C; JPS50127490A; FR2263788B1; DK136098B; IT1032297B; ZA751536B; NL167316C; GB1488413A; DE2508520B2

Abstract

A COMBINATION ABSORBENT DRESSING
AND FLEXIBLE COOLING DEVICE

ABSTRACT OF THE DISCLOSURE

A combination absorbent dressing and flexible cooling device which includes a cooling device super-imposed over a dressing composite, and an insulating material covering said cooling device and dressing composite.

S P E C I F I C A T I O N

1.

Description

93sg COLD THERAPY ADHES IVE BANDAGE

The invention relates to improvements in adhesive bandages and is particularly concerned with the construction and assembly of adhesive bandages having cold transmitting properties integrally associated therewith.
A wide variety of products are currently available on the market in the field of wound dressing~.
For example, sterile and medicated gauze-type dressings are widely employed in hospitals after ma~or surgery and also in the home for minor accidental in~uries.
However, in spite of their wide acceptance, the gauze-type dressings are not without their disadvantages.
For instance, frequent changes of such dressings are necessary in order to observe that the healing process ic proceeding as desired. These frequent changes are accompanied by discomfort to the patient since some adherence to the wound or wound exudate normally occurs. The gauze-type dressings also require removal to renew medication.
Various polymeric materials have also been investigated for use in the treatment of wounds, burns and other skin disorders. For example, collagen, poly-vinyl alcohol, gelatin and a wide variety of polymeric

2.

- . - - .. . .. , ~ .. - . ~ . , 10~3 73 materials have been disclosed in the literature as being useful in the treatment of accidental and surgical wounds. However, in most instances these materials are neither transparent, nor do they control the growth of bacteria. Moreover, many patients have been found to be allergic to these dressings which in many instances necessitated a return to the use of the gauze-type product.
Devices for lowering temperature at select sites are also widely employed in the treatment of animals and humans. Ice has been employed for many years and is well known for relieving the discomfort of pain and swelling and for injuries suffered accidentally, in athletics or as a result of other endeavors. However, while the well known ice pack may have a degree of flexibility it requires the crush-ing of ice, is cumbersome to use and does not provide a uniform cooling surface. Moreover, as the ice or the frozen water-alcohol mixtures attain room temperature, it reverts entirely to the liquid state and provides additional disadvantages in handling, particularly if the enclosing container is not completely leakproof.
It has long been recognized that there is a need for combining the advantages of a conventional gauze-type wound dressing with a device for lowering temperatures in one "overall" dressing or bandage.
Unfortunately however, prior art attempts have not been entirely sati~factory due to the attendant disadvantages ' ' ' ~ .:

~046373 which far outweighed any benefits received. For example, in the case where the absorbing material is placed directly over the wound with the cooling device over the absorbing material, there is a loss of cooling efficiency to the wound due to the insulating pro-perties of the absorbent material. Where ice or froze~ water-alcohol mixtures are utilized as the cooling medium, once the mixtures attain room temperature, they revert entirely to the liquid state and are subject to leakage in which case the absorbent dressing is a 180 sub;ect to saturation.
~t i8 therefore an object of the present invention to provide a novel, flexible adhesive bandage having fluid absorbing as well as cold transmitting properties integrally associated therewith. Another ob~ect is to provide a novel dressing that can act as both an absorbent for body fluid exudate from a wound or in~ury as well as a colt therapy to the involved area.
These and other ob~ects will become apparent from the following description of the invention taken in conjùnction with the accompanying drawings in which Fig. 1 is a perspective plan view partially cut away of the cold therapy adhesive bandage, exposing the constituents.
Fig. 2 is a cross-sectional view taken along the lines 2-2 of Fig. 1.
Fig. 3 is a bottom view with the release 4.

. .
.. . ..

.
.

strips pulled away exposing the dressing composite.
Fig. 4 is a view similar to Fig. 2 showing a broader aspect of the invention, i.e., without the outer covering and release strips.

Broadly contemplated, the present invention provides a combination ab~orbent dressin& and flexible cooling device comprising:
(a) a dressing composite comprising in com-bination, a hydrophobic top sheet for placement adjacent to the body and having a plurality of valvular open-ings therein, a substantially liquid impermeable backing sheet, and an absorbent material disposed between said top sheet and backing sheet and being characterized by its ability to absorb liquid passed through said openings, and a system of dimples disposed on said top sheet;
(b) a cooling device associated with said dressing composite comprising a flexible packaging material encompassing and sealing an insoluble hydrophilic gel; and (c) an insulating material covering said cooling device and said dressing composite.

.
. . ... .. , , ~ ............. ~: . ~
. ~ . ~ ' ~ 0~6 3 7 ~ 9359 Optionally, there is provided a release strip on the lower surface of the device as protection against contamination.
In a more specific aspect, the present invention provides a combination absorbent dressing and flexible cooling device comprising:
(a) an outer sheet having two end segments containing an adhesive material on the lower surfaces thereof and a middle segment;
(b) a dressing composite comprising in com-bination, a hydrophobic top sheet for placement adjacent to the body and having a plurality of valvular open-ings therein, a substantially liquid impermeable backing sheet, and an absorbent material disposed between said top sheet and backing sheet and being characterized by its ability to absorb liquid passed through said openings, and a system of dimples disposed on said top sheet;
(c) a cooling device disposed between said outer sheet and said dressing composite comprising a flexible packaging material encompassing and sealing an insoluble hydrophilic gel;
(d) an insulating material disposed between said cooling device and said outer sheet; and 6.

10~6373 (e) a release strip disposed on the lower surface of said combination absorbent dressing and flexible cooling device in adhesive engagement with said end segments.
For a cle~rer understanding of the invention, reference is made to the drawings and ~n partic~lar to Fig. 1 thereof. The combination absorbent dressing and flexible cooling device generally depicted by reference numeral 10 (and hereinafter referred to as cold bandage,) includes an outer sheet 11 which serves as the upper, outer covering for the cold bandage. The outer sheet 11, i8 preferably fabricated from a liquid impermeable material, such as an olefinic or vinyl material. The outer sheet 11, has two end segments 12 and 13 which are adhesively treated on the bottom surface and a middle segment 14 constituting the area between opposing end segments 12 and 13.
Referring to Fig. 2, it will be seen that situated below the middle segment 14 of the outer sheet 11 is a dressing composite including an absorbent material (pad) 15 substantially centrally located and sandwiched between a thin, flexible backing sheet 16 of liquid impermeable material, such as polyethylene or polyvinylidene chloride film, and a thin flexible top sheet 17 also of a normally liquid impermeable material. Top sheet 17 has a plurality of valvular openings or slits 18 therein and a system of depressed areas ~dimpleQ) 19 (both as shown in Fig. 3) which slits and dimples will be described in greater detail hereinafter.

.. , , . : . :

10 ~ 73 Backing sheet 16 and topsheet 17 are of approxi-mately equal size and are of a length and width slightly greater than the corresponding dimensions of absorbent pad 15. The edges of backing sheet 16 and topsheet 17 are sealed to each other around the entire periphery and iust outside the outermost edges of absorbent pad 15.
The sealing can be accomplished by any convenient means, such as the use of an adhesive, but heat sealing is preferred and is indicated by heat seal 22 around the periphery of the topsheet and backing sheet. As shown in Figs. 1 and 2, sitiuated between the outer sheet 11 and the dressing composite, is a cooling device containing a flexible packaging material 24 which encompasses and seals an insoluble hydrophilic ge~ 25. The cooling device when in the frozen state, is of the type which is easily moldable into various configurations without loss of dimensional stability, and when in the unfrozen state, the gel contained in said device does not flow.
The cooling device is insulated from the atmosphere by provision of an insulating material 26 which is disposed between the cooling device and the outer sheet.
It wiLl be noted that the overall dimensions of the insulating material are greater than the backing sheet 16, the topsheet 17 and the cooling device so that the insulating material can effectively blanket the cooling device and dressing composite. In order to prevent substantial displacement of the insulating material and the cooling device, the edges of the insulating material are adhered such as by heat sealing and the like to the edges of the 104ti373 topsheet 17 and the backing sheet 16. It will, of course, be understood that this is a preferred embodiment and that the insulating material need not be adhered as shown.
In order to protect the lower surface of the cold bandage from contamination, the cold bandage is provided with release strips 27. The release strips 27 are adhered to the lower surface of the end segments 12 and 13 and prior to affixing the cold bandage to a localized area, the release strips can be removed by pulling on end tabs 28 and 29 in a manner such as to remove the release strips from the cold bandage.
As mentioned previously, the outer sheet 11 is preferably fabricated from a liquid impermeable material such as a polyvinylchloride, or polyethylene film.
The thickness of the film can vary within a range of about ~05 to .2 mils. Various other type materials can be employed such as non-woven cloth, treated paper and the like, but are not as preferred as the film materials. The adhesive utilized on the lower surface of the end segments 12 and 13 can be of the pressure-sensitive type conventionally employed in the pressure-sensitive tape art. Thus, the pressure sensitive adhesive has more self cohesion and adhesion to ~he end segments than to either release strip or to thç skin so that it peels easily from the latter without depositing any adhesive. The material used in the fabrication of the topsheet and backing sheet 10~373 of the dressing composite of the present invention are also not limited to any particular chemical composition since it is their physical properties rather than their chemical properties which are important in the articles of the invention. These materials should, of course, be thin, flexible, self-supporting, and substantially water impermeable films. Preferably they are thermo-pl~stic materials which are capable of being heat sealed to each other.
The backing sheet 16 is preferably an olefinic or vinyl film. Polyethylene or polyvinlidene chloride film of a thickness of from about 0.4 to about 1.5 mils are most preferred. ~ -Any film which is useful as a backing sheet will also be useful as a topsheet for the absorbent dressing of the invention, It is preferable, however, to use a film for the topsheet which resembles cloth more closely in feel and appearance since it is this portion of the article which will come in contact with the skin of the user. One film which has been found particularly useful is ethylene-ethyl acrylate film, This copolymer is cloth-like, and soter than poly-ethylene film. The film should have a thickness of from about 0.4 to about 2.0 mils with about 1.0 to 1.5 mils being preferred.
A~ described above, the topsheet is made from a substantially liquid impenmeable film and must be provided with openings to be effective as the absorbent dressing composite of the present invention. These openings in the topsheet mu~t be capable of opening 10.

10~i373 to permit passage of liquid to the absorbent material.
The openings are preferably substantially straight slits as contrasted to circular openings, curved openings and the like, Thus, referring specifically to Fig. 3, it will be seen that the topsheet, has a system of openings (slits) identified by reference num~ral 18 and a system of depressed areas 19 (dimples). The slits 18 are arranged in longitudinal rows in a manner such that each row constitutes a longitudinal array of substantially parallel straight slits each angularly dispo8ed with respect to the longitudinal axis of the row, Ad~acent rows are similarly disposed except that the slits are arranged in a manner such that the end points of each slit lie in a line substantially between the end points of corresponding slits in the ad~acent alternate rows. The slits useful in the present invention are preferably substantially straight slits. The slits should each be from about 0.03 to zbout 0.50 inch in length. Preferably there are from about 10 to about 1000 slits per square inch, each of such slits being from about 0.07 to about 0.20 inch in length. The most preferredjfilm contains about 81 slits per square inch, each about 0.10 inch in length.
The slits can be formed according to the methods and apparatus disclosed in U.S. Patent 3,762,255 issued October 2, 1973 and assigned to Union Carbide Corporation.
The depressed areas (dimples) are distributed across the surface of the topsheet in the manner shown in Fig. 3. Thus, it will be seen that the topsheet 17 contains 10~373 a plurality of dimples arranged in staggered parallel rows along the surface of the topsheet 17 and which extend above the plane of the topsheet (Figures 2 and 3).
The configuration of these dimples can be circu-lar, eliptical, rectangular, diamond shaped, and the like, the important criteria being that they be formed in a manner such that topsheet is not broken during or after fabrication.
I have found that the full advantages of the present invention are not achieved if, during fabrication of the dimples, the topsheet is broken, cut or melted to any signiflcant extent. I have found that the preferred form of the dimple is circular as shown in Figures 2 and

3).
The dimples can be formed in the topsheet in a variety of ways. The easiest and therefore the most preferred method involves the use of a roller equipped with heating means and having a number of spikes or probes extending therefrom across the width of the roller and around its circumference, The spikes, pins, or probes, which have smooth, rounded end points, can be spaced as desired on the roller in order to provide the desired number of dimples to the dressing composite. The dimples are provided on the dressing composite preferably after the openings, but prior to complete fabrication of the dressing composite, and this operation can be effected by passing the dressing composite containing the openings in contact with the heated roller. In this technique, the dre~sing composi~e is supported on a resilient back-up member, such as an endless conveyor belt, or a resilient back-up roller, The depth of the dimple can be controlled by limiting the 12.

104~373 depth to which the probes depress the film. If desired, portions of the topsheet may be retained in their untreated (without the dimples) condition. This can be accomplished, for example, along a narrow strip near the periphery of the topsheet. Since the topsheet is thermoplastic, the amount of heat and pres~ure applied to the areas to be treated should be strictly controlled in order to avoid sub~tantially puncturing the topsheet. As a general rule, the amount of heat required should be enough to ~often the film, and the amount of pressure should be sufficient to plastically distort the film to the general contour of the probe. It will, of course, be understood that the correct heat and pressure conditions will depend (among othex variables) upon the residence time of the treated dressing composite, i.e., the length of time the topsheet is in contact with the roller; the thlckness of the dressing composite pad, etc. The correct conditions, however, can be easily ascertained by one skilled in the art and hence no further description of the conditions appears necessary.
Referring specifically to Figure 2, it will be seen that the dimples 19 extend above the plane of the topsheet 17 a short distance, and that the absorbent material 15 immediately above the dimples, is in a co~pressed stste. At the site where a dimple is formed over a portion of a slit, that slit will be opened to a much greater degree than corresponding slits situated remote from the dimples 19, However, because of the placement of the dimples, the slits disposed between corresponding dimples are opened to a greater extent than would be the case if no dimples were present. This is attributed to the fact that the pressure exerted on the surface of the topsheet by the dimples causes the slits to open slightly under the influence of the stretching of the topsheet. Portions of the compressed absorbent pad are associated with these opened slits, and because of this association, almost instantaneous wicking is achieved.
As the liquid is transferred to the absorbent pad 15, the absorbent pad absorbs the liquid throughout its entire area until either partial or full saturation.
The dimples can be arranged on the absorbent article in a variety of patterns. Thus, the overall design effect can be diamond shaped, curvilinear, herringbone and the like. The preferred design configuration is a system of substantially straight staggered, parallel rows along the surface of the topsheet. The number of dimples per square inch of absorbent pad area can be varied over a relatively wide range. Improvements have been noted utilizing as little as 1 dimple (having a diameter of .05 inch) per square inch of absorbent pad. I have further observed that good results are obtained when as many as 100 dimples (.05 inch diameter) per square inch of absorbent pad area are utilized. It wlll of course be understood that the number of dimples per square inch of absorbent pad area depends on the dimple size.
As a general rule, dimple size can be in the range of about .025 to about 0.250 inch diameter. From the standpoint of functional and aesthetic qualities, it is preferred that the dimpl~ size range from about .075 to about 0.150 inch diameter.
The absorbent pad 15 can be one or more layers of absorbent tissue paper or wadding stacked to the desired thickness.
14.

104~;373 Absorbent materials other than tissue and wadding will of course be useful in the diaper con-struction of the present invention. For example, absorbent non-woven pads can be fabricated to any desired thickness and substituted for the absorbent pads described above. One such absorbent pad which has been used extensively in disposable diapers is a wood pulp product commonly known as wood fluff and is prepared in the same manner as a non-woven fabric.
In addition, foam materials having the desired degree of absorbency can also be employed.
The only criteria for utility in the present invention are that the material be absorbent, be capable of being fabricated in the form of a pad, be compatible with the liquid with which it will come in contact and be non-irritating to the skin.
The flexible packaging material of the cooling device can be a common plastic bag which is sealed around the edges and is fabricated of a material which has appropriate heat transfer rates. Merely as illustrative, suitable materials for this purpose include films fabricated from polyethylene or polyvinylidine chloride. Disposed within the flexible plastic material is an insoluble hydrophilic gel.
The term "insolubilization" as employed throughout the specification and appended claims is utilized herein to define the formation of a gel which is essentially solid at temperstures below about 35-C. The insolubilization can be effected by a wide variety of methods and includes, 15.

.

but is not limited to, ionizing and nonionizing radiation, and chemical cross-linking through covalent and ionic bonding.
In practice a wide variety of hydrophilic gels can be employed in the preparation of the cooling device of this invention. The only requirements of the particular gel chosen is that it be capable of retaining relatively large quantities of a liquid which can easily be transformed from the liquid to solid state by simple cooling procedures.
If the liquid does not enter the solid state then it is impossible to take advantage of the latent heat of fusion.
Although numerous liquids can be employed, water is preferred in order to take advantage of the large heat of fusion (144 B.t.u. per pound). Water can be employed as the sole liquid, other liquids such as alcohols can be used, or mixtures of water and other liquids or solutes can be employed.
Illustrative hydrophilic gels which are useful in the cooling device of this invention can be prepared by appropriate techniques from the following starting materia~s, among others;
Poly(ethylene oxide), Polyvinyl wrrolidone, Polyacrylamide, Anionic polyacrylamide, Polyvinylalcohol, Maleic anhydride-vinylether copolymers, Polyacrylic acid, Ethylene-maleic anhydride copolymers, - 16.

Po lyviny lether, Dextran, Gelatin, Hydroxy propyl cellulose, Methyl cellulose, Carboxymethyl cellulose, Hydroxyethyl-carboxymethyl cellulose, Hydroxyethyl cellulose, Propyleneglycol alginate, Sodium alginate, Polyethyleneimine, Polyvinyl alkyl pyridinium halides, e.g. polyvinyl-n-butyl-pyridinium bromide, Polyproline, Natural starches, Casein, Proteins, Polymethacrylic acid, Polyvinylsulfonic acid, Polystyrene sulfonic acid, Polyvinylamine, Poly-4-vinylpyridine, polymerized monoesters of olefinic acids, polymerized diesters of olefinic acids, acrylamide and difunctional polymerizable materials, e.g. diacids, diesters or diamides, and the like.
It should be noted that the starting materials are not only those listed above, but includes copolymers of one or more of either the aforementioned compounds or materials similar to these. For example, copolymers of ethylene oxide and minor or major amounts of other 17.

104t;373 alkylene oxides can also be used.
In most instances, the gel need only contain the insoluble swollen polymer and the liquid, e.g., water.
If desired however, it can also include other materials to control the physical and chemical properties such as freezing point, chemical stability, color, smell, crystal size and growth rate.
Although a single reinforced layer exhibits optimum conformability to the object being cooled, it is sometimes neces~ary or de~irable to have a greater cooling capacity than can be conveniently obtained in a single layer. This can be achieved by the formation of a multilayer device.
It has been observed that the optimum flexibility and other desirable features are exhibited when the layers of gel are separated from each other by a thin film of an inert material. The frozen layers are then permitted to slide easily over each other and contribute even greater flexibility than that possessed by multilayers of the gel alone.
In practice, gels can be made of any practical ,;~
thickneRs, width or length. In one embodiment gels have been prepared as a continuous tape which measures 3 inches wide by one-eighth of an inch thick. "Dacron" (a registered trademark of DuPont Chemical Co., Inc.) gauzes, both 9 and 20 holes per inch, which can be implanted in the material as it i6 being insolubilized lend strength to the resulting gel. Before being packaged the gels may ~-~
be swollen to their maximum liquid content. The product i8 than cut into predetermined lengths, stacked, if a multilayer device i8 desired, and then packaged in a 18.
,.

10~373 9359 polyethylene bag of the appropriate thickness. OptLmum results are obtained when the gel layers have a separator to separate them. This film can be applied during the preparation of the gel. When cooling devices were made with gel without the backing, the result was some loss of flexibility when frozen.
Devices of 20 layers of gel and higher have been made and found to have good flexibility.
The type of separator used to separate the gel layers is not necessarily critical and a wide variety of materials can be utilized. The only requirement of the separator is that they be flexible at reduced temperature and essentially unreactive with the gel. They do not have to be a continuous film but can be perforated.
Moreover, the separator can be a material which is applied to the surface of the gel and which effectively prevents adhesion of the layers when stacked-such materials include silicone surfactants, cetyl alcohol and the like.
Any of the numerous products currently on the market can be employed with satisfactory results. For example, separators can be composed of polyethylene, polypropylene, polystyrene, polyvinylchloride, polyethylene terephthalate, metal foils, and the like. Similarly, the outer covering or enclosure in which the multilayers of gel are enclosed can be fashioned from commercially available films or other packaging materials.
The flexible cooling device of this invention can be manufactured as a single use, disposable product or as a 19.

reusable device. If the device is meant to be disposable the outer enclosure can be a laminate with insulating material, such as cloth, polymer foams, paper and the like, on the outside. The inner portion of the laminate can be a common plastic such as polyethylene, polypropylene, and the like, to affect sealing or to protect the gel. A
metal foil can be part of the laminate to prevent the device from drying out. The primary package can also have attaching devices at each end to provide a means of securing the cooling device to the area to be cooled. Finally, the product can be manufactured and shipped as a sterile item if desired.
A~ a re-usable cooling device, the outer enclosure can be a common plastic bag sealed around the edges. This unit can be supplied with an auxiliary bag into which the tape i8 placed. This outer bag would be of a material which hao appropriate heat transfer rates and may have strings attached at both ends to be used to secure the tape to the area to be cooled. Both types of product can be packaged as a unitized structure for example, quilt like in character. Appropriate performations can be inserted so that the device can be divided into smaller pieces.
In one preferred aspect, the novel cooling devices of this invention are comprised of a hydrophilic, polymeric gel of at least one insolubilized polymer of the formula:

~ IR3 IR4 ~ , . . ., -Rl---t C--C--~ R2 Rs R6 n 20.

wherein Rl and R2 are selected from the group consisting of hydrogen, alkyl radicals and alkyl substituted aryl radicals, and wherein R3 is hydrogen when R4 is selected from the group consisting of hydrogen, methyl, phenyl and vinyl radicals, R4 is hydrogen when R3 is selected from the group consisting of hydrogen, methyl, phenyl and vinyl radicals, R5 is hydrogen when R6 is selected from the group consisting of hydrogen, methyl, phenyl and vinyl radicals, and R6 is hydrogen when R5 is selected from the group con-sisting of hydrogen, methyl, phenyl and vinyl radicals, andn is greater than one.
These hydrophilic gels are polymeric compounds containing at least one of the structural units shown below:

IRl lR2 - 1 ~ - , H

H
_ - I C--C _ Rl R2 _ -H 7 l~ - - _ _ -C--C--O- _ wherein Rl i8 hydrogen when R2 is selected from the group consisting of hydrogen, methyl, phenyl and vinyl radicals;

21.

104~373 9359 R2 is hydrogen when Rl is selected from the group consisting of hydrogen, methyl, phenyl and vinyl radicals; R3 is hydrogen when R4 is selected from the group consisting of hydrogen, methyl, phenyl and vinyl radicals; and wherein R4 is hydrogen when R3 is selected from the group consisting of hydrogen, methyl, phenyl and vinyl radicals.
These hydrophilic polymerlc gel compounds may in-clude carbon to carbon cross-linking between straight chain carbon atoms and the carbon atoms of branch chain methyl groups and between the carbon atoms of branch chain methyl groups themselves. In addi~ion a very minor and insignificant number of bonds may include two oxygen atoms linking the carbon atoms.
The polymeric gel compounds may contain cross-linking bonds present as inter-molecular bonds (e.g. between two different molecules) and intramolecular bonds (e.g.
between carbon atoms of the same molecule), and combina-tions of intra and intermolecular cross^linking bonds.
The proce8s for producing these polymeric gels from poly(ethylene oxide) comprises preparing a homogene-ous water solution of at least one of the water soluble compounds selected from the following class of com-pounds:

~ IR3 IR4 t f f ~
R5 R6 n wherein Rl and R2 are selected from the group consisting of hydrogen, alkyl radicals and alkyl substituted aryl radicals~ R3 is hydrogen when R4 is selected from the group consisting of hydrogen, methyl, phenyl, and vinyl radicals, R4 is hydrogen when R3 is selected from the group consisting of hydrogen, methyl, phenyl and vinyl radicals, R5 is hydrogen when R6 is selected from the group consisting of hydrogen, methyl, phenyl and vinyl radical~, R6 is hydrogen when R5 is selected from the group consisting of hydrogen, methyl, phenyl and vinyl radicals, and n is greater than one; submitting the solution to ionizing radiation for a period of time sufficient to cause insolubilization of the polymer.
The pH of the solution apparently is not critical to the operability of the preparation of the polymeric gels although the time required to cause formation of the gel-like material can be considerably shortened by utilizing a starting solution having a pH of about 7Ø
Temperature apparently is not critical to the operability of the process since the gel-like material has been formed in solutions having a temperature of just above the freezing point of the starting solution.
In the treatment of polymers of ethylene oxide in accordance with the presentinvention it is preferred to utilize poly(ethylene oxide) having a molecular we~ght ranging from about lX10 to about 10 ; a starting water solution containing at least about 0.2 weight percent of poly(ethyl-ene oxide); and submitting the starting solution to a total 23.

irradiation dosage of at least about 52.OX10 rads to produce the gel-like material.
In general, after the hydrophilic polymeric gels have been prepared, they can be used directly or further modified by the addition of or the incorporation of various agents, or other additives, as hereinafter indicated. Moreover if a higher degree of flexibility of the frozen hydrophilic polymeric gels is desired, it can be accomplished by addition of small amounts of glycol such as ethylene glycol and the like.
In addition to the use of an inert material as a separator in the cooling device of this invention, the device itself can contain various strengthening materials throughout. For example, nylon gauze, rayon mesh, "Dacron"
(a registered trademark of DuPont Chemical Co., Inc.), cellulose or other textile products mesh can be embedded in the hydrophiLic gel, or fibers can be embedded in a random orientation.
In practice, the hydrophilic gel forming step 2Q employed in the preparation of the polymeric gels can be accomplished prior to, or simultaneously with the placement of the inert separators and/or the incorporation of an internal substrate or strengthening agent. An internal substrate can be incorporated by dipping a matrix prior to insoLubiLization into the aqueous poly(ethylene oxide~ solution and then exposing it to insolubilizing conditions. Other methods for placement of the substrate wilL readiLy become apparent to those skilled in the art.
The novel cooling device of this invention can be made with hydrophilic gels in a variety of thicknes~es 24. -1 0~ ~'73 9359 ranging from one reinforced layer of 1 mill~meter thickness or less, to 20 or more layers to give a total thickness of several inches, or m~ e.
The insulating material 26 should be of the type which i8 flexible, and has good insulating properties so as to retard the effect of the difference in temperature of the atmosphere and the cooling device Preferably, the insulating material is a cellular material such as rubber fo~m, polyurethane foam, polystyrene and the like Most preferably, the material is capable of being heat sealed to the backing sheet and top sheet of the absorbent composite.
The thickness of the insulating material would of course depend upon the degree of protection required, the thickness of the cooling device, the desired flexibility of the cold bandage and other obvious considerations. For these reasons, exact figures for the thickness of the insulating material are not readily statable Suffice it to state that the degree of thickness of the insulating ~aterial can be easily assertained by one skilled in the art depending on the above mentioned criteria.
The release (or protection) strips 27 can be formed from materials commonly used inthe adhesive dressing art.
The cold bandage of the present invention can be fabricated by a wide variety of techniques.
Merely a~ illustrative, the absorbent composite and cooling device can be independently fabricated and placet over each other with the cooling device on top of the ab~orbent composite, The insu~ting 25.

104f~373 material thereafter can be superimposed over the two and adhered such as by heat sealing to the absorbent composite as explained previously. Thereafter the middle segment of the outer sheet can be superimposed over the entire assembly and joined thereto. The release strip can be added as a last step.
I have found that the cold bandage is particularly suitable for the intended purpose. There is very little tendency for the ice bandage to "stick"
to the wound as in conventional dressings. This is partly attributable to the selection of materials for the top sheet with ethylene ethylacrylate being the preferred material. Moreover, absorption of body exudate through the slits by the wicking action of the absorbent material as enhanced by the dimples is extremely rapid. Pinpoint transmission of "cold"
to the wound site is accomplished through the dimples on the absorbent composite. I have found that the cold transmission is extremely rapid when the dimple contains some liquid on its surface. Thus, it will be evident that the cold bandage of the instant invention has fluid absorbing as well as cold trans-mitting properties integrally associated therewith without experiencing any of the disadvantages characterlstically prevalent in prior art devices.
It will, of course, be understood that f~r certain uses, it is not necessary that the cold 26.

93sg ~04~3 73 bandage be provided with the outer covering or strip as shown. For example, the outer strip or covering can be eliminated when the cold bandage is to be used with conventional gauze or other type coverings.
Thus referring to Fig. 4, where like parts are designated by like reference numerals, and where the choice of materials and constructional details can be the same as those utilized in the device of Fig. 1~ it will be seen that the outer covering has been eliminated together with the release strips.
If désired, however, release strips can be added and their point of attachment can be at the ends of the cold bandage.
The term "valvular" as used throughout the specification and in the claims i~ intended to refer to apertures in the top sheet which are capable of opening to permit passage of liquid under certain circumstances and reclosing to retard pa~sage of liquid under certain other circumstances.
The term "dimples" are employed to characterize the depressed areas and mean the depressed areas across the surface of the top sheet which extend below (or above) the plane of the top sheet and which are fabricated in a manner such that there is substantially no breaking, melting or cutting of the top sheet during or after fabrication in a manner which would hinder the controlled passage of liquid to the absorbent pad.

27.

lQ4t;373 It will also be understood that while the present invention has been set forth in some detail and descr~bed with particularity, it is susceptible to changes, modifications and alterations without departing from the scope and spirit of the invention as defined in the appended claims. For example, although the cold bandage has been shown as having a generally rectangular configuration, it will, of course, be understood that it can be circular, eliptical, diamond shapet or of any other desired practical configuration.

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Claims

WHAT IS CLAIMED IS:

1. A combination absorbent dressing and flexible cooling device comprising:
(a) a dressing composite comprising in com-bination, a hydrophobic topsheet for placement adjacent to the body and having a plurality of valvular open-ings therein, a substantially liquid impermeable backing sheet, and an absorbent material disposed between said topsheet and backing sheet and being characterized by its ability to absorb liquid passed through said openings, and a system of dimples disposed on said topsheet;
(b) a cooling device associated with said dressing composite comprising a flexible packaging material encompassing and sealing an insoluble hydrophilic gel; and (c) an insulating material covering said cooling device and said dressing composite.

2. A combination absorbent dressing and flexible cooling device according to claim 1 wherein said hydrophobic topsheet is an ethylene ethyl-acrylate film.

29.

3. A combination absorbent dressing and flexible cooling device according to claim 2 wherein said valvular openings are substantially parallel straight slits disposed in longitudinal rows, each slit being angularly disposed with respect to the longitudinal axis of each row.

4. A combination absorbent dressing and flexible cooling device according to claim 3 wherein said slits are from about .03 to about .20 inch in length.

5. A combination absorbent dressing and flexible cooling device according to claim 1 wherein said dimples have a frequency of at least 1 per square inch of absorbent area.

6. A combination absorbent dressing and flexible cooling device according to claim 1 wherein said dimples have a circular configuration with a diameter of from about .025 to about 0.25 inch.

7. A combination absorbent dressing and flexible cooling device according to claim 1 wherein said topsheet and said backing sheet are of substantially the same dimensions and are adhered to each other around their periphery to form an integral structure having the absorbent material substantially enclosed and sandwiched between the topsheet and backing sheet.

30.

8. A combination absorbent dressing and flexible cooling device according to claim 1 wherein said insoluble hydrophilic gel is insolublized poly (ethylene oxide)

9. A combination absorbent dressing and flexible cooling device according to claim 1 wherein said insulating material is adhered to said dressing composite and said cooling device.

10. A combination absorbent dressing and flexible cooling device comprising:
(a) an outer sheet having two end segments containing an adhesive material on the lower surfaces thereof and a middle segment;
(b) a dressing composite comprising in com-bination, a hydrophobic top sheet for placement adjacent to the body and having a plurality of valvular open-ings therein, a substantially liquid impermeable backing sheet, and an absorbent material disposed between said top sheet and backing sheet and being characterized by its ability to absorb liquid passed through said open-ings, and a system of dimples disposed on said top sheet;

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(c) a cooling device disposed between said outer sheet and said dressing composite comprising a flexible packaging material encompassing and sealing an insoluble hydrophilic gel;
(d) an insulating material disposed between said cooling device and said outer sheet;
and (e) a release strip disposed on the lower surface of said combination absorbent dressing and flexible cooling device in adhesive engagement with said end segments.

11. A combination absorbent dressing and flexible cooling device according to claim 10 wherein said hydrophobic topsheet is an ethylene ethylacrylate film.

12. A combination absorbent dressing and flexible cooling device according to claim 11 wherein said valvular openings are substantially parallel straight slits disposed in longitudinal rows, each slit being angularly disposed with respect to the longi-tudinal axis of each row.

13. A combination absorbent dressing and flexible cooling device according to claim 12 wherein said slits are from about .03 to about .20 inch in length.

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14. A combination absorbent dressing and flexible cooling device according to claim 10 wherein said dimples have a frequency of at least 1 per square inch of absorbent area.

15. A combination absorbent dressing and flexible cooling device according to claim 10 wherein said dimples have a circular configuration with a diameter of from about .025 to about 0.25 inch.

16. A combination absorbent dressing and flexible cooling device according to claim 10 wherein said topsheet and said backing sheet are of substantially the same dimensions and are adhered to each other around their periphery to form an integral structure having the absorbent material substantially enclosed and sandwiched between the topsheet and backing sheet.

17. A combination absorbent dressing and flexible cooling device according to claim 10 wherein said insoluble hydrophilic gel is insolubilized poly (ethylene oxide)

18. A combination absorbent dressing and flexible cooling device according to claim 10 wherein said insulating material is adhered to said dressing composite and said cooling device.

33.