Biodegradable nano-polymer compositions and biodegradable articles made thereof

Abstract

The invention relates to biodegradable nano-polymer compositions, or nanocomposites, comprising poly(lactic acid) and co-polyester polymer with adipic acid compounded with nanoparticles of a mineral material having a degree of purity of at least 99.9%, preferably 99.99%, selected from the group of silica and magnesium silicate. In addition, the present invention refers to a process for manufacturing the said compositions as well as biodegradable articles made on the basis of such compositions, such as molded, formed and extruded articles.

1 . A biodegradable composition, comprising:
 between 40 and 97% by weight of poly(lactic acid) polymer (PLA);   between 0.5 and 35% by weight of a co-polyester polymer with adipic acid; and   more than 0% and up to 6% by weight of nanoparticles of an extremely pure mineral material selected from the group consisting of silica and magnesium silicate, each on the basis of the total weight of the biodegradable polymer composition.   
     
     
         2 . The biodegradable polymer composition according to  claim 1 , wherein the nanoparticles of mineral material have a size comprised between about 20 and 500 nanometers. 
     
     
         3 . The biodegradable polymer composition according to  claim 1 , wherein the nanoparticles of mineral material have a degree of purity of at least 99.9%. 
     
     
         4 . The biodegradable polymer composition according to  claim 1 , comprising between 1 and 32% of particles of mineral filler comprising magnesium silicate or talc having a particle size comprised between about 0.2 and 4.0 microns. 
     
     
         5 . The biodegradable polymer composition according to  claim 1 , to which composition during its preparation more than 0% and less than 5% of an organic peroxide, on the basis of the total weight of the final biodegradable composition, has been added. 
     
     
         6 . The biodegradable polymer composition according to  claim 3 , wherein said organic peroxide is selected from the group consisting of diacetyl peroxide, cumyl-hydro-peroxide, and dibenzoyl peroxide, dialkyl peroxide, 2,5-methyl-2,5-di(terbutylperoxy)-hexane and mixtures thereof. 
     
     
         7 . A molded, extruded or thermoformed article comprising a biodegradable composition, said biodegradable composition comprising:
 between 40 and 97% by weight of poly(lactic acid) polymer;   between 0.5 and 35% by weight of co-polyester polymer with adipic acid; and   more than 0% and up to 6% by weight of nanoparticles of an extremely pure mineral material selected from the group consisting of silica and magnesium silicate, each on the basis of the total weight of the biodegradable polymer composition.   
     
     
         8 . The article according to  claim 7 , wherein the nanoparticles of mineral material have a size comprised between about 20 and about 500 nanometers. 
     
     
         9 . The article according to  claim 7 , wherein the nanoparticles of mineral material have a degree of purity of at least 99.9%. 
     
     
         10 . The article according to  claim 7 , said article being selected from the group consisting of utensils, food service-ware, forks, spoons, knives, chopsticks, containers, cups, plates and pots. 
     
     
         11 . The article according to  claim 7 , which further comprises particles of mineral filler comprising magnesium silicate or talc having the particle size comprised between about 0.2 and about 4.0 microns. 
     
     
         12 . The article according to  claim 7 , to which composition during its preparation more than 0% and less than 5%, of organic peroxide, on the basis of the total weight of the biodegradable composition, has been added. 
     
     
         13 . A method of producing an article comprising a biodegradable composition, said process comprising the steps of:
 (i) providing a biodegradable composition, said composition comprising between 40 and 97% by weight of poly(lactic acid) polymer, and between 0.5 and 35% by weight of co-polyester polymer with adipic acid, each on the basis of the total weight of the biodegradable composition, and more than 0% and up to 6% by weight of nanoparticles of an extremely pure mineral material selected from the group consisting of silica and magnesium silicate;   (ii) mixing the constituents of (i) so as to prevent the creation of aggregates;   (iii) heating the mixture to a temperature of from 95 to 135° C.; and   (iv) forming the resultant mixture to obtain a desired shape.   
     
     
         14 . The method according to  claim 13 , wherein the mineral nanoparticles are directly introduced into the barrel of the mixer/extruder. 
     
     
         15 . The method according to  claim 14 , wherein the mineral nanoparticles are introduced into the barrel of the mixer/extruder through a side feeder. 
     
     
         16 . The method according to  claim 13 , wherein the nanoparticles of mineral material have a size comprised between about 20 and about 500 nanometers. 
     
     
         17 . The method according to  claim 13 , wherein the nanoparticles of mineral material have a degree of purity of at least 99.9%. 
     
     
         18 . The method according to  claim 13 , which comprises adding to the biodegradable composition provided according to step i) between 1% and 32% of particles of mineral filler comprising magnesium silicate or talc having a particle size comprised between about 0.2 and about 4.0 microns. 
     
     
         19 . The method according to  claim 13 , which comprises adding to the biodegradable composition provided according to step i) more than 0% and less than 5% of organic peroxide. 
     
     
         20 . The method according to  claim 13 , wherein the step of forming includes subjecting said biodegradable composition to a process selected from the group consisting of injection molding, profile extrusion, and thermoform extrusion. 
     
     
         21 . The biodegradable polymer composition according to  claim 3 , wherein the degree of purity is 99.99%. 
     
     
         22 . The article according to  claim 9 , wherein the degree of purity is 99.99%. 
     
     
         23 . The method according to  claim 17 , wherein the degree of purity is 99.99%.