A PRESSURE SENSITIVE ADHESIVE COMPOSITION

Abstract: A pressure sensitive adhesive composition suitable for medical purposes comprising a rubbery elastomeric base and one or more water soluble or water swellable hydrocolloids, said adhesive composition comprising a substantially homogeneous mixture of 15-60 % of a butyl rubber, 15-60 % of one or more tackifier resins, 1-10 % of a tackifying liquid constituent, 20-60 % of one or more hydrocolloids and 0-3 % of a pigment shows very good properties as an adhesive for ostomy appliances.

Description: TITLE A Pressure Sensitive Adhesive Composition. FIELD OF THE INVENTION The present invention relates to pressure sensitive adhesive compositions suitable for various medical applications and especially suitable for use for adhesion to the skin, in particular in the field of ostomy care. More specifically, this invention relates to adhesive compositions comprising a rubbery elastomeric base and one or more water soluble or water swellable hydrocoUoids dispersed therein, the use of such adhesive compositions for the preparation of a wound dressing or an adhesive wafer for an ostomy appliance, and to wound dressings or ostomy appliances comprising such adhesive composition. BACKGROUND OF THE INVENTION In connection with surgery for a number of diseases in the gastro-intestinal tract a consequence is, in many cases, that the colon, the ileum or the urethra has been exposed surgically and the patient is left with an abdominal stoma and the effluents or waste products of the body, which are conveyed through these organs, are discharged through the artificial orifice or opening and are collected in a collection bag, which is usually adhered to the skin by means of an adhesive wafer or plate having an inlet opening for accommodating the stoma. Also in connection with a fistula, the patient will have to rely on an appliance to collect the bodily material emerging from such opening. In connection with treatment of wounds, it is often desirable to cover and protect the wound with a skin barrier or dressing comprising a backing and an adhesive layer for contacting the wound and the surroundings for ensuring a bacteria-tight closure of the wound. Various skin adhesive agents are used today for the above mentioned purposes. Such adhesives should have a composition which is sufficiently tacky to secure the appliance or skin barrier to the abdomen, and a cohesion ensuring safe removal thereof without leaving residues on the skin. Furthermore, the adhesive should show a degree of elasticity to enable the adhesive layer of the appliance or barrier to follow the movements of the patient without slipping the skin and should also show a great resistance to erosion caused by aggressive exudates from an ostomy in order to minimise the risk of leakage. A very widespread embodiment of skin adhesive agents comprises a self- adhesive elastomeric matrix, in which water-absorbing, swelling particles, the so-called hydrocoUoids, are dispersed. Adhesive compositions comprising hydrocoUoids have been known for many years. US patent No. 3,339,549 discloses a blend of a rubbery elastomer such as polyisobutylene and one or more water soluble or water swellable hydrocol- loids such as a powdery mixture of pectin, gelatine and carboxymethylcellulose. The adhesive mass has a water-insoluble film applied to one surface. A composition of this type is available commercially from E.R. Squibb & Sons Inc. under the trademark "Stomahesive" and is used as a skin barrier around stomas to prevent skin breakdown by the corrosive fluids discharged by the stoma. In adhesive compositions of this type, the polyisobutylene is responsible for provision of the adhesive properties and the dispersed hydrocolloid powders absorb fluid and render the adhesive agent capable of also adhering to moist skin (wet tack). These compositions are also gaining increasing acceptance as wound dressings for dermal ulcers, burns and other exuding wounds. One major problem which has been encountered with conventional adhesive compositions comprising hydrocoUoids is their susceptibility to breakdown upon exposure to body fluids. When the compositions are used as skin barriers, e.g., around stomas, absorption of fluid is desirable, but excessive swelling causes the composition to lose its integrity opening for leaks and the barrier must be replaced more often than is desirable from a skin protection point of view, and very often, a residue remains on the skin, which in many cases is difficulty to remove. A number of attempts have been made to improve the properties of adhesive compositions in order to overcome the above-mentioned drawbacks. US Patent Nos. 4,192,785 and 4,551 ,490 describe incorporating into an adhesive composition of a cohesive strengthening agent such as a natural or synthetic fibrous material, finely divided cellulose, cross-linked dextran, cross- linked carboxymethylcellulose or a starch-acrylonitrile graft copolymer. The cohesive strengthening agent is stated to control the rate of hydration of the composition thereby increasing the resistance against breakdown by body fluids. US Patent No. 4,477,325 describes incorporation of a mixture of a copolymer resin of ethylene and vinyl acetate (EVA) into the adhesive composition. After mixing and moulding, the composition is subjected to ionising radiation to form a cross-linked polymer network of the EVA or comprising EVA and another cross- linked resin. The cross-linked matrix is said to provide a controlled swelling. US Patent No. 4,496,357 describes the incorporation of fumed silica into adhesive compositions to control swelling. EP Patent No. 0 122 344 B1 describes incorporation of one or more natural or synthetic polymers capable of developing elastomeric properties when hydrated, such as gluten and long chain polymers of methyl vinyl ether/maleic acid, into the adhesive composition. The adhesive composition is stated to be resistant to erosion by moisture and body fluids. EP Patent No. 0 340 945 B1 describes incorporation of some polycationic hydro- colloid particles into a hydrocolloid composition. The mixture of polycationic, polyanionic and neutral hydrocoUoids is stated to provide increased integrity without a concomitant decrease in absorbing capacity. In other embodiments, styrene copolymers have been incorporated which is disclosed in a number of patent references. In US Patent No. 4,231 ,369 Sorensen et al. disclose an ostomy skin barrier consisting of a physically cross-linked styrene copolymer having dispersed therein a water soluble hydrocolloid gum, a tackifier and optionally an oil extender. In US Patent No. 4,367,732 Poulsen et al. disclose an ostomy skin barrier consisting of a water soluble hydrocolloid dispersed in a continuous phase consisting of a physically cross-linked elastomer, a hydrocarbon tackifier, and a plasticizer, an antioxidant, and optionally an oily extender. US Patent No. 4,427,737 (Cilento et al.) discloses a breathable tape having a porous backing and a microporous adhesive layer comprising from about 30% to about 60% by weight rubbery elastomer selected from the group consisting of natural rubber, polyurethane rubber, and polyisobutylene, from 20% to about 65% by weight of one or more water soluble or water swellable hydrocoUoids and up to 35% by weight of one or more tackifiers, plasticizers, antioxidants and preservatives. In US patent No. 5,633,010, Chen discloses a hydrocolloid composition comprising a unsaturated aliphatic homopolymer (20 - 50%) cross-linked by gamma radiation, a compatible tackifier (20 - 60%) and at least one hydrocolloid absorbent (5 - 60%). US patent No. 5,006,401 (Frank) discloses a composite compression dressing comprising 5 - 30% by weight of one or more polyisobutylenes or a blend of one or more polyisobutylenes and butyl rubber, from 3 to 30% by weight of one or more styrene radial or block copolymers, from 8 to about 40% by weight mineral oil and from 15 to 65% by weight of one or more water soluble hydrocolloid gums and up to 15% by weight of one or more water swellable cohesive strengthening agents, from 7.5 to 15% by weight of a tackifier and up to about 5% by weight of optional ingredients. US Patent No. 4,551 ,490 (Doyle et al.) discloses medical grade pressure sensitive adhesive compositions comprising a homogeneous mixture of 5-30% of one or more polyisobutylenes, 3-20% of one or more styrene radial or block type copolymers, mineral oil, one or more water soluble hydrocolloid gums, and a tackifier. One or more water swellable cohesive strengthening agents, an antioxidant, and various other optional ingredients also may be included within the adhesive composition. EP patent publication No. 81907 discloses an ostomy appliance comprising a skin barrier (A) surrounding the stoma and a coupling element (B) including an outwardly extending flange permanently affixed to the skin barrier (A) and a microporous adhesive layer (C) having an upper porous layer. The skin barrier adhesive (A) comprises a homogeneous 30-70% of a blend of low molecular weight polyisobutylene and one or more optional thermoplastic elastomers selected from medium molecular weight polyisobutylene, butyl rubber, and styrene isoprene copolymers and having dispersed therein 35-65% of one or more water soluble hydrocoUoids and one or more water swellable or inert cohesive strengthening agents. Generally speaking, these prior methods are superior to improve the integrity of adhesive compositions. Nevertheless, need still exists for better adhesive composition having resistance to biological fluids as well as the properties of improved adhesion to the skin and strechability. Now it has been found that an improved adhesive composition having resistance to biological fluids as well as the properties of improved adhesion to the skin and strechability may be obtained. BRIEF DESCRIPTION OF THE INVENTION The present invention relates to a pressure sensitive adhesive composition suitable for various medical applications and especially suitable for use for adhesion to the skin, in particular in the field of ostomy care. More specifically, this invention relates to adhesive compositions comprising a rubbery elastomeric base and one or more water soluble or water swellable hydrocoUoids dispersed, ostomy appliances comprising such adhesive compositions and the use of such adhesive compositions for preparing wound dressings or ostomy appliances. DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pressure sensitive adhesive composition suitable for medical purposes comprising a rubbery elastomeric base and one or more water soluble or water swellable hydrocoUoids, said adhesive composition comprising a substantially homogeneous mixture of 15 - 60 % of a butyl rubber, 15 - 60% of one or more tackifier resins, 1 - 10 % of a tackifying liquid constituent, 20 - 60% of one or more hydrocoUoids and 0 - 3% pigment. The pressure sensitive adhesive compositions of the present invention differ from the compositions disclosed in US patent Nos. 4,231 ,369 4,427,737 and, 5,633,010 in that they comprise 15 - 60% butyl rubber and in that the compositions of the invention comprise 1 - 10% of a tackifying liquid. The pressure sensitive compositions of the invention differs from the compositions disclosed in US patent No. 5,006,401 in that they comprise 1 - 10% of a tackifying liquid and in that the tackifying component is present in an amount above 15%. The pressure sensitive adhesive compositions of the present invention differ from the compositions disclosed in US patent No. 4,367,732 in that they comprise butyl rubber and no physically cross-linked elastomer or polar plasti- cizer therefor. The adhesive compositions according to the invention show a very strong erosion resistance, and the new adhesive provide a significantly longer wear-time for those patients using appliances with the adhesive compositions of the invention. Without limiting the invention to any hypothesis it is believed that the combination of the rubbery elastomer, one or more tackifier resins and a tackifying liquid constituent in the proportions stated above provides extensibility and both rapid and complete recovery from modular strains to the composition. The combination of the adhesive properties of the rubbery elastomer and one or more tackifier resins and tackifying liquid constituent and the absorbing properties of the hydrocoUoids renders the adhesive composition of the invention especially suitable for use in ostomy appliances. The contents of butyl rubber in the compositions according to the invention is preferably from 15 to 45% and more preferably from 20 to 35%. The contents of tackifier resin is preferably 15 to 45% and more preferably from 20 to 35%. The amount of tackifying liquid in the compositions of the invention is suitably from 2 to 9%, more preferably from 3 to 8% and especially about 5%. In a preferred embodiment, the adhesive comprises a substantially homogeneous mixture of 20 - 30 % of butyl rubber, 20 - 30% of one or more tackifier resins, 3 - 8 % of a tackifying liquid constituent, and 30 - 55% of one or more hydrocoUoids The rubbery component is preferably a non-staining, medium unsaturated isoprene-isobutylene copolymer having a Mooney viscosity about 50 pts when determined according to ISO-289. The tackifying resin is preferably a hydrocarbon tackifier resin and is more preferably selected from the group comprising polymers and copolymers of cyclopentadiene, dicyclopentadiene, alpha-pinene or beta-pinene. The tackifying liquid constituent is suitably a liquid paraffin. Suitable hydrocoUoids for incorporation in the adhesive compositions of the invention are selected from naturally occurring hydrocoUoids, semisynthetic hydrocoUoids and synthetic hydrocoUoids. More particularly, the hydrocoUoids are preferably selected from guar gum, locust bean gum (LBG), pectin, alginates, gelatine, xanthan and/or gum karaya; cellulose derivatives (e.g. salts of carboxymethylcellulose such as sodium carboxy- methylcellulose, methylcellulose and hydroxypropylmethylcelluiose) and/or sodium starch glycolate and/or polyvinylalcohol and/or polyethylene glycol. It is preferred to use a combination of two or more hydrocoUoids. It is especially preferred to use a combination of pectin, gelatine and carboxymethylcellulose as the hydrocolloid component. The total amount of hydrocoUoids is preferably 40 - 50% of the total composition. An especially preferred composition according to the invention comprises 25% of butyl rubber, 25% of tackifying resin, 5% of tackifying oil and 45% of a mixture of hydrocoUoids comprising gelatine, pectin and CMC. The pigment optionally being present in the compositions according to the invention may be any pharmaceutically acceptable pigment such as zinc oxide or titanium dioxide. In a further aspect, the invention relates to the use of an adhesive composition comprising a rubbery elastomeric base and one or more water soluble or water swellable hydrocoUoids, said adhesive composition comprising a substantially homogeneous mixture of 15 - 60 % of a butyl rubber, 15 - 60% of one or more tackifier resins, 1 - 10 % of a tackifying liquid constituent, and 20 - 60% of one or more hydrocoUoids for securing ostomy appliances to the skin and for sealing around an ostomy, for securing wound dressings or wound drainage bandages to the skin, for securing devices for collecting urine to the skin , or for securing orthoses or prostheses to the skin. In a still further aspect, the invention relates to an ostomy appliance for placing on the abdomen of a patient for use in collecting discharge of visceral contents comprising an adhesive composition containing a substantially homogeneous mixture of 15 - 60 % of a butyl rubber, 15 - 60% of one or more tackifier resins, 1 - 10 % of a tackifying liquid constituent, and 20 - 60% of one or more hydrocoUoids. In yet another aspect, the invention relates to a method for securing an ostomy appliance to skin and for sealing around an ostomy , for securing a wound dressing or wound drainage bandage to skin, for securing a device for collecting urine to skin, or for securing an orthosis or prosthesis to skin comprising applying to the skin a pressure sensitive adhesive composition suitable for medical purposes comprising a rubbery elastomeric base and one or more water soluble or water swellable hydrocoUoids, said adhesive composition comprising a substantially homogeneous mixture of 15 - 60 % of a butyl rubber, 15 - 60% of one or more tackifier resins, 1 - 10 % of a tackifying liquid constituent, 20 - 60% of one or more hydrocoUoids and 0 - 3% pigment. An ostomy appliance according to the invention may be an open or a closed appliance suitable for use in connection with a colostomy, an ileostomy or a urostomy. It may be a one-piece appliance or a body side member or face plate forming part of a two-piece appliance comprising the body side ostomy member and a separate collection bag and optionally comprising a convex member. A separate collection bag may be attached to the body side member in any convenient manner known per se, e.g. via a coupling ring or by a flange covered with an adhesive. An ostomy appliance according to the invention may be made from materials conventionally used for the preparation of ostomy appliances in a manner known per se in the field. In a preferred embodiment of an ostomy appliance of the invention, the adhesive plate for securing the appliance to the abdomen of the user is of the kind comprising two different adhesives in a roll of the kind disclosed in WO 89/05619. All percentages stated in this specification are by weight unless otherwise stated. The invention is illustrated more in detail in the below Examples disclosing embodiments of the invention. MATERIALS AND METHODS Butyl Rubber: Polysar Butyl 101 -3 from Bayer AG Paraffin oil: PL-500 from Rode & Rode A/S Arkon P-90 from Arakawa Forest Chemical Industries Ltd. A hydrogenated cyclopentadiene tackifier. Gelatine: Gelatine P.S.98.240.233 available from ED. Geistlich Sohne AG. Pectin: Pectin LM 12CG Z or Pectin USP/100 from Copenhagen Pectin A/S. CMC: Sodium carboxymethylcellulose available from Akzo under the tradename Akucell® AF2881 A Z mixer Type LKB 025 from Herman-Linden was used. EXPERIMENTAL PART EXAMPLE 1 Preparation of an adhesive material according to the invention having the composition stated in the below Table 1 : Table 1 Ingredient Percent by weight Butyl rubber 25 Arkon P-90 20 Paraffin oil 5 Gelatine 20 Pectin 20 CMC 10 100 grams of butyl rubber was added in to Z-mixer at 160 °C and softened for about 5 minutes. Then 80 grams of Arkon P-90 and 20 grams of paraffin oil were added and mixing was continued at 160 °C and 50 mbar until the blend was homogeneous. The mass was cooled to 80 °C, and 100 grams of the mass was removed from the mixer. To the remained mass was added 40 grams of gelatine, 40 grams of pectin and 20 grams of CMC. Mixing is continued under 80 °C and 50 mbar until a homogeneous dough was formed. While still hot and soft, the resulting dough-like mass was then removed from the mixer and formed into sheet stock material having a thickness of approximately 1 mm by compression moulding the adhesive mass at approximately 90 °C and 100 Bar between two sheets of silicone release paper. The resultant flat plate was then cut into pieces having the desired shapes. The adhesive composition may be used for securing ostomy appliances to the skin and for sealing around an ostomy, for securing wound dressings or wound drainage bandages to the skin, for securing devices for collecting urine to the skin, or for securing orthoses or prostheses to the skin. The ostomy appliances or wound dressings may be any such product known per se and may be prepared in a manner analogous to the preparation of similar products using conventional adhesive compositions. EXAMPLES 2-8 Following the procedure disclosed in Example 1 adhesive compositions according to the invention having the compositions stated in the below Table 2 were prepared. Table 2 Table 2 Cont. EXAMPLE 9 Test of ostomy appliances having an adhesive plate according to the invention as compared to a commercially available ostomy appliance. A trial has been carried out in which 50 evaluable patients participated in the test, 29 ileostomates and 21 urostomates. The trial was carried out as a comparative, crossover test with two test products - an existing commercial product, Assura Wear-life collection and a correspond- ing a collection bag having an adhesive plate comprising the adhesive according to Example 2. The test results showed that the new adhesive based on butyl rubber performs significantly better regarding the parameter "the feeling of security" compared to Assura wear-life. Furthermore, the adhesive showed excellent properties with respect to adhesion and absorbing properties. Thus, the adhesive according to the invention showed stronger erosion resistance, and the new adhesive provided a significantly longer wear-time for those patients using these appliances, 95 hours compared to the 70 hours by the Assura wear-life (p<0.001) as appears from the below Table 3. Table 3 Wear Time in Hours for Ostomy Appliance According to the invention as Compared With Assura Wear-life.

Claims: CLAIMS 1. A pressure sensitive adhesive composition suitable for medical purposes comprising a rubbery elastomeric base and one or more water soluble or water swellable hydrocoUoids, said adhesive composition comprising a substantially homogeneous mixture of 15 - 60 % of a butyl rubber, 15 - 60% of one or more tackifier resins, 1 - 10 % of a tackifying liquid constituent, 20 - 60% of one or more hydrocoUoids and 0 - 3% of a pigment. 2. An adhesive composition as claimed in claim 1 wherein the butyl rubber is a non-staining, medium unsaturated isoprene-isobutylene copolymer having a Mooney viscosity about 50 pts when determined according to ISO-289. 3. An adhesive composition as claimed in claim 1 or 2 wherein the tackifying resin is a hydrocarbon tackifier resin. 4. An adhesive composition as claimed in claim 3 wherein the hydrocarbon tackifier resin is a polymer or copolymer of cyclopentadiene, dicyclopentadiene, alpha-pinene or beta-pinene. 5. An adhesive composition as claimed in any of claims 1 - 4 wherein the tackifying liquid constituent is a liquid paraffin. 6. An adhesive composition as claimed in any of claims 1 - 5 wherein the hydro- colloids are naturally occurring hydrocoUoids, semisynthetic hydrocoUoids or synthetic hydrocoUoids. 7. An adhesive composition as claimed in claim 6 wherein the hydrocoUoids are selected from guar gum, locust bean gum (LBG), pectin, alginates, gelatine, xanthan and/or gum karaya; cellulose derivatives (e.g. salts of carboxymethylcellulose such as sodium carboxymethylcellulose, methylcellulose and hydroxypro- pylmethylcellulose) and/or sodium starch glycolate and/or polyvinylalcohol and/or polyethylene glycol. 8. An ostomy appliance for placing on the abdomen of a patient for use in collecting discharge of visceral contents comprising an adhesive composition containing a substantially homogeneous mixture of 15 - 60 % of a butyl rubber, 15 - 60% of one or more tackifier resins, 1 - 10 % of a tackifying liquid constitu- ent, 20 - 60% of one or more hydrocoUoids and 0 - 3% of a pigment. 9. Use of an adhesive composition comprising a rubbery elastomeric base and one or more water soluble or water swellable hydrocoUoids, said adhesive composition comprising a substantially homogeneous mixture of 15 - 60 % of a butyl rubber, 15 - 60% of one or more tackifier resins, 1 - 10 % of a tackifying liquid constituent, 20 - 60% of one or more hydrocoUoids and 0 - 3% of a pigment for securing ostomy appliances to the skin and for sealing around an ostomy, for securing wound dressings or wound drainage bandages to the skin, for securing devices for collecting urine to the skin , or for securing orthoses or prostheses to the skin. 10. A method for securing an ostomy appliance to skin and for sealing around an ostomy , for securing a wound dressing or wound drainage bandage to skin, for securing a device for collecting urine to skin, or for securing an orthosis or prosthesis to skin comprising applying to the skin an adhesive composition as claimed in any of claims 1 - 7.

Inventors: CHEN FEI, CHEN, FEI
Applicants: COLOPLAST AS, COLOPLAST A/S
Application year: 1999
Main classification: C09J123
IPC codes: A61L15, A61L24, C08L57, C09J123