1. Field of the Invention
This invention relates to pressure-sensitive adhesives having the capacity to absorb moisture and therefore adhere to moist body surfaces for a prolonged period of time. More particularly, this invention relates to an improvement in such adhesives which affords them a combination of high plasticity and "wet-stick" adhesion at acceptable levels of moisture absorption over prolonged periods of time, which renders the adhesive particularly suitable for such applications as stoma seal adhesives. This invention also relates to surgical sheet materials such as adhesive tapes and to adhesive bandages and dressings, including plasters that are particularly suitable for use in connection with ostomy appliances as well as for coverings for cuts, abrasions and the like, which comprise a flexible backing member, one of whose major surfaces has adhered thereto a coating of a pressure-sensitive adhesive of the present invention.
Various types of pressure-sensitive adhesives have been proposed and utilized as the adhesive component in adhesive bandages, adhesive tapes and the like. Acrylate polymers, polyolefinic polymers and compounded systems based on natural or synthetic rubber polymers have all been tried or utilized as pressure-sensitive adhesives with varying degrees of success.
A pressure-sensitive adhesive must have certain characteristics to be useful. It must be sufficiently tacky, i.e., have sufficient "grab" or quick-stick," to adhere quickly to the surface to which it is to be adhered. It must also continue to adhere to that surface over extended periods of time. A pressure-sensitive adhesive composition should also have sufficient internal strength to prevent splitting and leaving particles of adhesive on a surface to which an article coated with the adhesive has been adhered when the article is removed. Where the pressure-sensitive adhesive is designed for application to the skin, the problems of adherence are substantially increased. Although the initial tack or stick may be good, adherence over an extended period of time for many pressure-sensitive adhesives requires relatively high shear adhesion to withstand movement of the underlying skin. Also, the adhesive must be tailored to accommodate the nature of the underlying skin surface, as where perspiration and other surface changes may occur. The problem is further complicated by the fact that any pressure-sensitive adhesive designed for application to the skin must release from the skin sufficiently readily to permit removal without skin damage. Where the adhesive is too strongly adhered to the skin and has substantial internal strength, small particles of the upper layer of skin are removed with the adhesive with resulting irritation to the skin. As a result, although many pressure-sensitive adhesives are available for various commercial uses, relatively few have been found which are suitable for articles for skin applications, particular in that many of those having desirable, high sheer adhesion, have an undesirably high resistance to removal, or peel adhesion. This problem is further complicated when the adhesive is intended in such applications as those involving ostomy appliances, where it is required to maintain adhesion for prolonged periods of time while in contact with body fluids, and at the same time to prevent leakage of such fluids therethrough.
A colostomy is the surgical creation of a new opening for the colon on the surface of the body, while an ileostomy is the surgical creation of an opening for the ileum. In an ileostomy the entire colon, the rectum, and sometimes a small portion of the ileum, is removed. In a colostomy the rectum, and sometimes a portion of the colon, is removed.
Both ileostomy and colostomy operations involve the creation of an artificial opening (stoma) in the abdomen to which the distal end of the healthy intestine is attached. Generally, the stoma is placed low on the abdomen and to one side. A related enterostomy for which the stoma seal adhesive of the present invention might be useful is the urinary diversion. It involves the formation of a permanent fistula through which the ureter may discharge its contents.
As a result of the ostomy procedure, means must be provided for conveniently and hygenically collecting human waste material from the resulting stoma. While there are many such ostomy appliances, a common problem experiences with them, as indicated above, is the establishment and maintenance of both good skin adhesion and an adequate seal to prevent waste material coming in contact with the patient's skin. This requires, inter alia, an adhesive material that has good adhesion to both dry and wet skin, adequate moisture absorptivity and sufficient elastic modulus or plasticity to prevent either inadvertent detachment from wet skin or inordinate difficulty or discomfort to the user when the device is intentionally removed.