Production of elastomeric films

Abstract

A method for producing multi-layered elastomeric film or article, the method comprising: (i) dipping a mould into a composition for producing an elastomeric film having a total solids content of between 5%-40% to produce a layer of elastomeric film composition on the mould, (ii) partially drying the layer of elastomeric film composition on the mould to reduce the total water content of the elastomeric film composition to a level of not less than 22%, (iii) dipping the mould coated with the partially dried layer of elastomeric film composition into a composition for producing an elastomeric film having a total solids content of between 5%-40% to produce a further layer of elastomeric film composition on the mould, (iv) optionally repeating the partial drying step (ii) and the further dipping step (iii), and (v) drying and curing the layers of elastomeric film composition on the mould.

1 . A method for producing multi-layered elastomeric film or article, the method comprising:
 (i) dipping a mould into a composition for producing an elastomeric film having a total solids content of between 5%-40% to produce a layer of elastomeric film composition on the mould,   (ii) partially drying the layer of elastomeric film composition on the mould to reduce the total water content of the elastomeric film composition to a level of not less than 22%,   (iii) dipping the mould coated with the partially dried layer of elastomeric film composition into a composition for producing an elastomeric film having a total solids content of between 5%-40% to produce a further layer of elastomeric film composition on the mould,   (iv) optionally repeating the partial drying step (ii) and the further dipping step (iii), and   (v) drying and curing the layers of elastomeric film composition on the mould.   
     
     
         2 . The method of  claim 1 , wherein the partial drying step (ii) is controlled to reduce the water content to a level below 90%, but not less than 22%. 
     
     
         3 . The method of  claim 2 , wherein the partial drying step (ii) is controlled to reduce the water content to a level below 80% but not less than 22%. 
     
     
         4 . The method of  claim 3 , wherein the partial drying step (ii) is controlled to reduce the water content to a level below 80% but not less than 25%. 
     
     
         5 . The method of  claim 4 , wherein the partial drying step (ii) is controlled to reduce the water content to a level below 75% but not less than 25%. 
     
     
         6 . The method of  claim 4 , wherein the partial drying step (ii) is controlled to reduce the water content to a level below 77% but not less than 30%. 
     
     
         7 . The method of  claim 1 , wherein the partial drying step (ii) is controlled so that at the end of partial drying the film surface temperature of the elastomeric film composition on the mould is between 25° C.-85° C. 
     
     
         8 . The method of  claim 1 , wherein the partial drying step (ii) achieves a film surface temperature of between 30° C. and 80° C. 
     
     
         9 . The method of  claim 1 , wherein the partial drying step (ii) achieves a film surface temperature of between 40° C. and 80° C. 
     
     
         10 . The method of  claim 1 , wherein the partial drying step (ii) comprises subjecting the coated mould to drying conditions at a temperature above ambient. 
     
     
         11 . The method of  claim 10  wherein the partial drying step (ii) comprises applying drying radiation to the coated mould. 
     
     
         12 . The method of  claim 1 , wherein the mould is subjected to heating prior to dipping step (i). 
     
     
         13 . The method of  claim 12 , wherein the heating step comprises heating to raise the surface temperature to a temperature in the range of 25° C. to 85° C. 
     
     
         14 . The method of  claim 1 , further comprising the steps of:
 (a) dipping the mould into a coagulant containing multivalent ions in solution, and   (b) drying or partially drying the coagulant-dipped mould,   
       prior to step (i). 
     
     
         15 . The method of  claim 14 , wherein the mould is heated prior to dipping into the coagulant. 
     
     
         16 . The method of  claim 15 , wherein the mould is heated to a surface temperature in the range of 30° C. to 70° C. 
     
     
         17 . The method of  claim 14 , wherein the multivalent ions are multivalent metal ions. 
     
     
         18 . The method of  claim 1 , wherein the dwell time of the mould in the dipping tank in step (i) is between 1.0 to 10.0 seconds. 
     
     
         19 . The method of  claim 1 , wherein the temperature of the composition into which the mould is dipped in step (i) is within the range of 10° C. to 60° C. 
     
     
         20 . The method of  claim 1 , wherein the film or article has between 2 to 15 layers. 
     
     
         21 . The method of  claim 1 , wherein step (iv) of repeating the partial drying step (ii) and the further dipping step (iii), is performed at least once. 
     
     
         22 . The method of  claim 21 , wherein the film or article has between 3 and 15 layers. 
     
     
         23 . The method of  claim 1 , wherein each layer of the film constitutes between 6 and 90% of the total film thickness. 
     
     
         24 . The method of  claim 1 , wherein the composition for producing an elastomeric film comprises an elastomer-forming polymer and a cross-linking agent. 
     
     
         25 . The method of  claim 1 , wherein the mould is a glove-shaped mould, and the elastomeric article is a glove. 
     
     
         26 . A film or article produced by the method of  claim 1 .