Medical balloon assembly and method of making a medical balloon

Abstract

A medical balloon includes an outer layer and an inner layer. The outer layer has a surface texture or formation, such as a scoring element. The inner layer is made of a reflow material which during production of the balloon from a raw tubing will soften and flow into internal recesses in the outer layer, thereby filling these recesses and providing support to the outer layer formations so as to avoid flattening of these formations during use of the balloon. The balloon can be manufactured in a single formation step from raw tubing having the outer and inner reflow layer coextruded.

We claim: 
     
         1 . A method of making a medical balloon, comprising:
 disposing a raw tubing of balloon material in a mold, the mold having an inner mold surface having a textured shape consistent with that of the balloon to be formed, the raw tubing having a wall formed of at least two layers overlying one another, an overlying layer formed of a material having a first melting temperature and an underlying layer formed of a material having a second melting temperature, wherein the second melting temperature is lower than the first melting temperature;   inflating the raw tubing simultaneously with subjecting the raw tubing to heat, causing the raw tubing to expand to the inner mold surface and to form the medical balloon;   wherein the heat causes melting of the underlying layer, whereupon material of the underlying layer flows into any recesses or cavities in the overlying layer, and the underlying layer has an inner surface which is generally round.   
     
     
         2 . The method according to  claim 1 , wherein the overlying layer has an expanse and the underlying layer extends across the entire expanse of the overlying layer. 
     
     
         3 . The method according to  claim 1 , wherein the overlying layer forms an outer layer of the balloon. 
     
     
         4 . The method according to  claim 1 , wherein the overlying layer forms an outermost layer of the balloon. 
     
     
         5 . The method according to  claim 1 , wherein the underlying layer forms an inner layer of the balloon. 
     
     
         6 . The method according to  claim 1 , wherein the underlying layer forms an innermost layer of the balloon. 
     
     
         7 . The method according to  claim 1 , wherein an inflation pressure into the raw tubing causes an outer surface of the underlying layer to have a shape which conforms to a shape of an inner surface of the overlying layer in the formed balloon. 
     
     
         8 . The method according to  claim 7 , wherein inflation pressure causes the outer surface of the underlying layer to extend into recesses or cavities in the inner surface of the overlying layer. 
     
     
         9 . The method according to  claim 1 , wherein an inflation pressure causes the underlying layer to have an inner surface which is smooth. 
     
     
         10 . A method of making a medical balloon, comprising:
 positioning a tube within a mold, the mold having a textured inner surface, and the tube comprising an overlying layer having a first melting temperature and an underlying layer having a second melting temperature which is less than the first melting temperature;   inflating the tube within the mold; and   heating the tube such that an outer surface of the overlying layer conforms to the shape of the textured inner surface of the mold and that the underlying layer melts into cavities formed in the overlying layer.   
     
     
         11 . The method of  claim 10 , wherein inflating the tube and heating the tube occur simultaneously. 
     
     
         12 . The method of  claim 10 , further comprising sealing the tube prior to inflating the tube. 
     
     
         13 . The method of  claim 12 , wherein inflating the tube comprises blowing air into the tube to a pressure such that the melted underlying layer forms a generally round inner surface. 
     
     
         14 . The method of  claim 10 , wherein the mold comprises a first neck which radially constrains a first end of the tube and a second neck which radially constrains a second end of the tube. 
     
     
         15 . A method of making a medical balloon, comprising:
 positioning a tube within a mold, the mold having a textured inner surface, and the tube comprising an overlying layer having a first melting temperature and an underlying layer having a second melting temperature which is less than the first melting temperature;   inflating the tube within the mold;   heating the overlying layer above a softening temperature of the overlying layer, such that an outer surface of the overlying layer conforms to the shape of the textured inner surface of the mold; and   heating the underlying layer above the second melting temperature such that the underlying layer melts into cavities formed in the overlying layer while heating the overlying layer.   
     
     
         16 . The method of  claim 15 , wherein inflating the tube and heating the overlying layer occur simultaneously. 
     
     
         17 . The method of  claim 15 , wherein inflating the tube and heating the underlying layer occur simultaneously. 
     
     
         18 . The method of  claim 15 , wherein heating the overlying layer forms the outer surface of the overlying layer to have a plurality of ribs. 
     
     
         19 . The method of  claim 15 , wherein heating the overlying layer forms the outer surface of the overlying layer to have a plurality of dimples. 
     
     
         20 . The method of  claim 15 , wherein heating the underlying layer forms an inner surface of the underlying layer which is generally round.