Barrier material with nanosize metal particles

Abstract

The incorporation of nanosized metal particles into cyclodextrin-containing material leads to a “reactive” barrier material having excellent barrier properties. Also, it has been found that the presence of nanosized metal or metal alloy particles in a barrier material such as thermoplastic material, wherein said material comprises cyclodextrin derivatives, may be advantageous in achieving excellent barrier properties. The barrier material of the present invention may provide improved barrier resistance to a variety of permeants and/or impurities. The diffusion of volatile substances through the barrier material may be prevented by adding compatible derivatized cyclodextrin and nanosized metal particles to the material used. Accordingly, the inventive material also is suitable for many applications including food-contact packaging, flexible packaging to dispose of adult and baby diapers, incontinent products, hospital and household waste and also for packaging pharmaceutical products, medical devices and dental materials.

1 . A method for manufacturing a barrier material comprising the steps of: 
 (a) providing a thermoplastic matrix material,    (b) physically mixing and dispersing an effective absorbing amount of modified cyclodextrin into the matrix material; wherein the cyclodextrin is free of an inclusion complex compound, and comprises an α-cyclodextrin, a β-cyclodextrin, a γ-cyclodextrin or mixtures thereof, having pendant moieties or substituents that render the cyclodextrin compatible with the matrix material,    (c) dispersing into the cyclodextrin-containing matrix material nanosized particles selected from the group of zinc, a similar reacting metal and similar reacting metal alloy, wherein said nanosized particles are essentially free of corresponding oxides.    
     
     
         2 . The method of  claim 1 , wherein the physically mixing and dispersing step of the modified cyclodextrin into the matrix material is carried out by extrusion.  
     
     
         3 . The method of  claim 2 , wherein the nanosized particles of zinc, a similar reacting metal or metal alloy to be added to the cyclodextrin material are ispersed in a thermoplastic material forming a masterbatch.  
     
     
         4 . The method of  claim 3 , further comprising the steps of dispersing the nanosized particles of zinc, a similar reacting metal or metal alloy to be added to the cyclodextrin material in mineral oil prior to dispersion into the thermoplastic material and stripping the mineral oil from the thermoplastic material using heat and vacuum.  
     
     
         5 . A method for producing a barrier material comprising the steps of: 
 (a) providing a thermoplastic matrix material,    (b) adding nanosized particles selected from the group of zinc, a similar reacting metal and a similar reacting metal alloy, wherein said nanosized particles are essentially free of corresponding oxides.    (c) subsequently adding and physically mixing and dispersing an effective absorbing amount of modified cyclodextrin into the matrix material; wherein the cyclodextrin is free of an inclusion complex compound, and comprises an α-cyclodextrin, a β-cyclodextrin, a γ-cyclodextrin or mixtures thereof, having pendant moieties or substituents that render the cyclodextrin compatible with the matrix material.    
     
     
         6 . A method for producing a container comprising the steps of: forming a container from a material including a barrier material; wherein the barrier material comprises a thermoplastic matrix material, an effective absorbing amount of a cyclodextrin free of an inclusion complex compound and including an α-cyclodextrin, a β-cyclodextrin, a γ-cyclodextrin or mixtures thereof, having pendant moieties or substituents that render the cyclodextrin compatible with the matrix material, and nanosized particle selected from the group consisting of zinc, similar reacting metal and a similar reacting metal alloy, and wherein the nanosized particles are essentially free of corresponding oxides.  
     
     
         7 . The method of  claim 6 , wherein the container is a plastic diaper pail having a tight lid.  
     
     
         8 . The method of  claim 6 , wherein the container is made of the barrier material or the container is coated with at least one film or one layer of the barrier material.  
     
     
         9 . A method for producing a disposable diaper having an outer layer or a backing layer, the method comprising the steps of: 
 applying a coating or film onto the outer layer or backing layer; wherein the coating or film is made with a material having improved barrier properties and comprising: a thermoplastic matrix material, an effective absorbing amount of a cyclodextrin free of an inclusion complex compound and comprises an α-cyclodextrin, a β-cyclodextrin, a γ-cyclodextrin or mixtures thereof, having pendant moieties or substituents that render the cyclodextrin compatible with the matrix material, and nanosized particle selected from the group consisting of zinc, similar reacting metal and similar reacting metal alloy, and wherein the nanosized particles are essentially free of corresponding oxides.    
     
     
         10 . A method of producing a packaging material, the method comprising the step of: 
 providing a barrier material in the packaging material, the barrier material comprising: a thermoplastic matrix material, an effective absorbing amount of a cyclodextrin free of an inclusion complex compound and comprises an α-cyclodextrin, a β-cyclodextrin, a γ-cyclodextrin or mixtures thereof, having pendant moieties or substituents that render the cyclodextrin compatible with the matrix material, and nanosized particle selected from the group consisting of zinc, similar reacting metal and similar reacting metal alloy, and wherein the nanosized particles are essentially free of corresponding oxides.    
     
     
         11 . The method of  claim 8 , wherein the packaging material is a food-contact packaging material.  
     
     
         12 . The method of  claim 1 , wherein the amount of cyclodextrin added to the matrix material is in the range from about 0.01 to 5 wt.-% or from about 0.1 to 1 wt.-%, based on the matrix material.  
     
     
         13 . The method of  claim 1 , wherein the cyclodextrin added to the matrix material has a low moisture content of about 1 wt.-%, based on the yclodextrin material.  
     
     
         14 . The method of  claim 5 , wherein the amount of nanosized particles of zinc added to the matrix material is in the range from about 0.01 to 5 wt.-% based on the matrix material.  
     
     
         15 . The method of  claim 1 , wherein the cyclodextrin material comprises at least one substituent selected from the group consisting of a silyl ether group, an alkyl ether group and an alkyl ester group.  
     
     
         16 . The method of  claim 15 , wherein the cyclodextrin material added comprises substituents having an alkyl ester group.  
     
     
         17 . The method of  claim 15 , wherein the substituents added and having the alkyl ester group comprise at least one moiety selected from the group consisting of acetyl moieties, propyl moieties and butyl moieties.  
     
     
         18 . The method of  claim 15 , wherein the cyclodextrin material comprises substituents having an alkyl ether group.  
     
     
         19 . The method of  claim 17 , wherein the substituents having the alkyl ether group comprise at least one moiety selected from the group consisting of methyl moieties, ethyl moeties and propyl moieties.  
     
     
         20 . The method of  claim 15 , wherein the cyclodextrin material comprises substituents having a silyl ether group.  
     
     
         21 . The method of  claim 20 , wherein the substituents having the silyl ether group comprise at least one moiety selected from the group consisting of methyl moieties, ethyl moieties, propyl moieties and butyl moieties.  
     
     
         22 . The method of  claim 1 , further comprising a step of producing barrier material in least two layers, wherein at least one first layer of the at least two layers includes the matrix material, the cyclodextrin material and the nanosized particles of zinc.  
     
     
         23 . The method of  claim 21 , wherein the at least one first layer of the at least two layers comprising the cyclodextrin material is a laminate film layer.  
     
     
         24 . The method of  claim 1 , further comprising the steps of layering the barrier material on a substrate resulting in a form selected from the group consisting of a monolayer- bilayer- or multilayer-film of barrier material with the cyclodextrin material being part of anyone of the said layer, a paperboard having one or more extrusion-coatings on at least one surface of the paperboard with the cyclodextrin material being part of one or more said extrusion coating, a metal foil having one or more extrusion coatings on at least one surface of the metal foil with the cyclodextrin material being part of the one or more said extrusion coating, and a cellulosic web/film laminate, with the cyclodextrin material being part of the film of said cellulosic web/film laminate.