Technology

POLYMERIC PRESSURE SENSITIVE ADHESIVES FOR MEDICAL APPLICATIONS

-By Mr. P A Mahanwar & Ms. Farhana Yasmeen, University Department of Chemical Technology, Matunga, Mumbai 

INTRODUCTION

A pressure semsotove adjesove )PSA) is generally defined as a material that will adhere to a substrate when a light pressure is applied and will leave no residue when removed.  Since the first patent issued more than 140 years ago, PSAs have found wide spread use in both industrial and consumer market.  It was not long before the potential of medical applications was recognized with the first applications of a tackified, zinc oxide filled natural rubber for hospital tape in 1899.  During world war II isbutylene and butene rubber based PSA were developed to replace the waning supply of natural rubber.  Acru;oc adjesives were developed in the post war years.  Since 1950 a great number of polymers have been developed and used as PSA, including a relative new comer, silicone adhesives.

Pressure sensitive adhesive products are widely used for medical, hospital, first aid, athletic protection and related applications.  Hospital tapes are the oldest pressure sensitive adhesive application.  Tapes are used to keep dressings in place, for strapping and movement restriction and other holding operations.  Other uses of pressure sensitive adhesive products include electrocardiogram and ostomy mounts; occlusive dressings; burn dressings; surgical drapes, protective pads, including various protective foot products; grounding pads for electrosurgery, and as transdermal drug delivery devices.  The use of pressure sensitive adhesives for medical applications is increasing, as evidenced from the growing number of patents in this particular area.1

The present article deals with the critical literature survey of the polymeric systems used in pressure sensitive adhesives for various medical applications.

Solution Adhesive :

These are still the most important category. Although they are been replaced nby both aqueous and hot melt adhesive.  The reasons for replacement are economical and environmental regulations which required removal of the solvent vapor from exhaust gases, thus increasing the investment in processing equipment, and by high and potentially unstable solvent prices.  Solution adhesives are the easiest to apply and are the most versatile in their properties.  

Hot melt adhesives :

These adhesives are based almost exclusively on block copolymers tackified with resins.  The advantages of hot melt application are high coating speeds and low floor space requirements; the disadvantage is low degree of versatility.

Aqueous Adhesive Emulsion :

This sector of the adhesives is fastest growing adhesive category.  Acrylic copolymers dominate these adhesive; butadiene styrene copolymers and natural rubber latex are also used in a more lomited way.

Calenderable Adhesives :

These adhesives are 100% solid compounded materials processable on calendering equipment.  The importance of calendered tapes is decreasing.  Significant amount of buty1 rubber based adhesive are calendered for cooorsion risistant tapes.

Radiation Curable Adhesive :

These are 100% solid reactive coatings, consisting of acrylic funtionality contianing oligomers and monomers.  These adhesives have a sufficiently low viscosity so that it can be applied by conventional coating equipment.  They cure upon ultraviolet (UV) or accelerated electron irradiation yieding a useful pressure sensitive adhesive.

Pressure sensitive adhesives are classified on the basis of main elastomer content such as ;

1. Natural Rubber

2. Styrene/Butadiene Latex - Based adhesives

3. Buty1 Rubber And Isobutylene

4. Acrylic

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