Degradable Cigarette Filter

Abstract

A degradable cigarette filter includes a filter element of a bloomed cellulose acetate tow, a plug wrap surrounding the filter element, and either a coating or a pill in contact with the tow. The coating and/or pill may be composed of a material adapted to catalyze hydrolysis of the cellulose acetate tow and a water-soluble matrix material. The material may be an acid, an acid salt, a base, and/or a bacterium adapted to generate an acid. The coating may be applied to the tow, the plug wrap, or both. The pill may be placed in the filter element. When water contacts the water-soluble matrix material, the material adapted to catalyze hydrolysis is released and catalyzes the hydrolysis, and subsequent degradation, of the cellulose acetate tow. The foregoing is also applicable to articles made of cellulose esters.

1 - 20 . (canceled) 
     
     
         21 . A degradable cigarette filter comprising:
 a filter element comprising bloomed cellulose acetate tow;   a plug wrap; and   a pill comprised of a water-soluble matrix material that completely encapsulates a material adapted to catalyze hydrolysis of the bloomed cellulose acetate tow;   wherein the plug wrap surrounds the bloomed cellulose acetate tow and the pill.   
     
     
         22 . The filter of  claim 21 , wherein the water-soluble matrix material is selected from the group consisting of cellulose acetate having a degree of substitution of 0.8±0.2, carboxymethyl cellulose, ethyl cellulose, hydroxypropyl cellulose, hydroxypropyl methyl cellulose, methyl cellulose, polyethylene glycol, polyvinyl acetate, polyvinyl alcohol, starch, glucose, sucrose, lactose and combinations thereof. 
     
     
         23 . The filter of  claim 21 , wherein the material adapted to catalyze hydrolysis of the cellulose acetate comprises a material with a pK a <6 or a pK b <6. 
     
     
         24 . The filter of  claim 21 , wherein the material adapted to catalyze hydrolysis of the cellulose acetate is selected from the group consisting of: an acid, an acid salt, a base, bacterium adapted to generate an acid, and combinations thereof. 
     
     
         25 . The filter of  claim 24 , wherein the acid is selected from the group consisting of: acetic, ascorbic, ascorbyl-2-phosphate, ascorbyl-2-sulfate, aspartic (aminosuccinic), cinnamic, citric, folic, glutaric, lactic, malic (1-hydroxysuccinic), nicotinic (nician), oxalic, succinic, tartaric, boric, hydrochloric, nitric, phosphoric, sulfuric, and combinations thereof. 
     
     
         26 . The filter of  claim 24 , wherein the acid is a combination of a weak organic acid and a component that can be hydrolyzed to a strong acid. 
     
     
         27 . The filter of  claim 26 , wherein the compound that can be hydrolyzed to a strong acid is selected from the group consisting of: cellulose sulfate, dodecyl sulfate, ascorbyl-2-sulfate, ascorbyl-2-phosphate, phosphorus pentoxide, phosphorus pentoxide based esters, cellulose nitrate, 2-ethyl hexyl phosphate, and combinations thereof. 
     
     
         28 . The filter of  claim 24 , wherein the acid salt is a metal salt, wherein the metal is selected from the group consisting of: aluminum, potassium, sodium, or zinc, and the non-metal portion of the salt is selected from the group consisting of nitrates, dihydrogen phosphates, hydrogen phosphates, phosphates hydrogen sulfates, sulfates and combinations thereof. 
     
     
         29 . The filter of  claim 24 , wherein the base is selected from the group consisting of: metal hydroxides, calcium oxide (lime), urea, borax, sodium metasilicate, ammonium hydroxide, sodium carbonate, sodium phosphate tribasic, sodium hypochlorite, sodium hydrogen carbonate (sodium bicarbonate), and combinations thereof. 
     
     
         30 . The filter of  claim 24 , wherein the bacterium adapted to generate an acid is selected from the group consisting of: a bacterium that produces an acid and a bacterium that attacks and degrades the cellulose acetate directly. 
     
     
         31 . The filter of  claim 30 , wherein the bacterium that produces an acid is selected from the group consisting of: lactobacillus acidophilus, bifurdobacterium longum, acetobacterium woodii, acetobacter aceti (vinegar bacteria), and combinations thereof. 
     
     
         32 . The filter of  claim 30 , wherein the bacterium that attacks and degrades the cellulose acetate directly is selected from the group consisting of: rhizobium meliloti, alcigenes xylosoxidans, and combinations thereof. 
     
     
         33 . The filter of  claim 21 , wherein the cellulose acetate of the bloomed cellulose acetate tow has a degree of substitution in the range of 2.0 to 2.6. 
     
     
         34 . The filter of  claim 21 , wherein a weight ratio of the material adapted to catalyze hydrolysis of the cellulose acetate tow to the water-soluble matrix material is in the range of 0.75 to 4.0:1. 
     
     
         35 . The filter of  claim 24 , wherein the material adapted to catalyze hydrolysis of the cellulose acetate tow is a bacterium, and further wherein the bacterium comprises 1-5 billion colony forming units. 
     
     
         36 . The filter of  claim 24 , wherein the material adapted to catalyze hydrolysis of the cellulose acetate tow is an acid, and further wherein the acid is present in the range of 2 to 200% by weight of the cellulose acetate tow in the filter element. 
     
     
         37 . The filter of  claim 24 , wherein the material adapted to catalyze hydrolysis of the cellulose acetate tow is a base, and further wherein the base is present in the range of 50 to 500% by weight of the cellulose acetate tow in the filter element. 
     
     
         38 . A degradable article comprising:
 an article made of a cellulose ester,   a pill composed of a mixture of a water-soluble matrix material and a material adapted to catalyze hydrolysis of the cellulose ester, said mixture being applied to said article made of said cellulose ester,   whereby water dissolves the matrix material and exposes the material adapted to catalyze hydrolysis to the cellulose ester, and the material adapted to catalyze hydrolysis degrades the article made of the cellulose ester.   
     
     
         39 . The article of  claim 38 , wherein the material adapted to catalyze hydrolysis of the article made of cellulose ester is selected from the group consisting of: an acid, an acid salt, a base, a bacterium adapted to generate an acid, and combinations thereof. 
     
     
         40 . The article of  claim 38 , wherein the cellulose ester is selected from the group consisting of cellulose acetate (D.S. of 2.0 to 3.0), cellulose acetate butyrate, and cellulose acetate propionate.