Cellulose ether coating compositions and methods

Abstract

The present disclosure is directed to cellulose ether compositions for film-forming coating applications. A coating composition is provided which contains an aqueous solution of either a very low viscosity cellulose ether or a low-hydroxypropyl cellulose ether, the coating composition having low color. The low viscosity of the cellulose ether component enables the coating composition to contain a high concentration of cellulose ether. Provision of these high concentration cellulose ether coating solutions improves production efficiency by reducing the time required to coat a substrate.

1 . A composition comprising:
 an aqueous solution of a very low viscosity cellulose ether present in an amount of at least 10% by weight of the composition, the very low viscosity cellulose ether having a molecular weight such that a 2% by weight aqueous solution of it at 20° C. has a viscosity from 1.2 mPa·s to less than 2 mPa·s; and   a plasticizer.   
     
     
         2 . The composition of  claim 1  wherein the cellulose ether is a very low color cellulose ether. 
     
     
         3 .- 4 . (canceled) 
     
     
         5 . The composition of  claim 1  comprising a second cellulose ether. 
     
     
         6 . (canceled) 
     
     
         7 . The composition of  claim 1  wherein the composition has a total solids content from at least 10% by weight to about 40% by weight. 
     
     
         8 . The composition of  claim 1  wherein the viscosity of the composition is from 100 cP to 1000 cP. 
     
     
         9 . A coated composition comprising:
 a substrate; and   a coating on the substrate, the coating comprising a plasticizer and a very low viscosity cellulose ether present in an amount of at least 10% by weight of the coating, the very low viscosity cellulose ether having a molecular weight such that a 2% by weight aqueous solution of it at 20° C. has a viscosity from 1.2 mPa·s to less than 2 mPa·s.   
     
     
         10 .- 39 . (canceled) 
     
     
         40 . The composition of  claim 1  comprising the very low viscosity cellulose ether in an amount of at least 20% by weight of the composition. 
     
     
         41 . The composition of  claim 1  wherein the very low viscosity cellulose ether is a methylcellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxyethylmethyl cellulose, hydroxypropylmethyl cellulose, hydroxybutylmethyl cellulose, ethylhydroxyethyl cellulose, carboxymethyl cellulose, or carboxymethyl hydroxyethylcellulose. 
     
     
         42 . The composition of  claim 1  wherein the very low viscosity cellulose ether is a hydroxypropylmethyl cellulose. 
     
     
         43 . The composition of  claim 1  wherein the very low viscosity cellulose ether has an APHA color value of from 1 to 100. 
     
     
         44 . The composition of  claim 1  wherein the plasticizer is selected from the group consisting of polyethylene glycol, castor oil, dibutyl sebacate, diethyl phthalate, glycerol, polyethylene glycol methyl ether, triacetin, triethyl citrate, phospholipids, lecithin, propylene glycol and combinations thereof in an amount of from 1 to 10% by weight of the composition. 
     
     
         45 . The composition of  claim 1  wherein the composition has a total solids content from 20% by weight to about 40% by weight. 
     
     
         46 . A coated composition of  claim 9  wherein the substrate is selected from the group consisting of tablets for oral ingestion, food products, pharmaceutical capsules, medicaments, drugs, seeds, animal feed, granules, beads, powder, encapsulates, troches and fertilizers. 
     
     
         47 . The coated composition of  claim 9  wherein the substrate comprises a surface and an edge, and the coating covers the surface and the edge. 
     
     
         48 . The coated composition of  claim 9  comprising a uniform coating on the surface and the edge. 
     
     
         49 . The coated composition of  claim 9  wherein the coating is a single layer. 
     
     
         50 . The coated composition of  claim 9  wherein the very low viscosity cellulose ether is a methylcellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxyethylmethyl cellulose, hydroxypropylmethyl cellulose, hydroxybutylmethyl cellulose, ethylhydroxyethyl cellulose, carboxymethyl cellulose, or carboxymethyl hydroxyethylcellulose. 
     
     
         51 . The coated composition of  claim 9  wherein the very low viscosity cellulose ether is a hydroxypropylmethyl cellulose. 
     
     
         52 . The coated composition of  claim 9  wherein the very low viscosity cellulose ether has an APHA color value of from 1 to 100. 
     
     
         53 . The coated composition of  claim 9  wherein the plasticizer is selected from the group consisting of polyethylene glycol, castor oil, dibutyl sebacate, diethyl phthalate, glycerol, polyethylene glycol methyl ether, triacetin, triethyl citrate, phospholipids, lecithin, propylene glycol and combinations thereof in an amount of from 1 to 10% by weight of the coating.