Ethylene-vinyl alcohol copolymer composition, and powdery coating composition comprising it

Abstract

An ethylene-vinyl alcohol copolymer (EVOH) composition comprises 100 parts by weight of a powder (A) having a particle size of from 22 to 850 μm of an ethylene-vinyl alcohol copolymer (a) which has an ethylene content of from 2 to 60 mol % and has a degree of saponification greater than 95%, and from 0.0001 to 2 parts by weight of inorganic particles (B) having primary particles with a mean particle size of from 1 to 100 nm. The EVOH powder coating composition of the present invention forms a coating film having good uniformity when applied to a substrate as powder coating, even when it contains 1 part by weight or more water relative to 100 parts by weight of EVOH resin.

1 . A composition comprising: 
 100 parts by weight of a powder (A) having a particle size of 22 to 850 μm, and    0.0001 to 2 parts by weight of inorganic particles (B) having primary particles with a mean particle size of from 1 to 100 nm,    wherein powder (A) comprises an ethylene-vinyl alcohol copolymer (a) having an ethylene content of from 2 to 60 mol %, and a degree of saponification of more than 95%.    
     
     
         2 . The composition of  claim 1 , wherein the inorganic particles (B) adhere to the surface of the powder (A).  
     
     
         3 . The composition of  claim 1 , wherein the ethylene-vinyl alcohol copolymer (a) has an amount of carboxylic acid ranging from 10 to 5000 ppm, based on the weight of the ethylene-vinyl alcohol copolymer (a).  
     
     
         4 . The composition of  claim 3 , wherein the carboxylic acid is at least one carboxylic acid selected from the group consisting of acetic acid, propionic acid and lactic acid.  
     
     
         5 . The composition of  claim 1 , wherein the ethylene-vinyl alcohol copolymer (a) has an amount of alkali metal salt ranging from 5 to 500 ppm (expressed as ppm by weight of the elemental alkali metal in the ethylene-vinyl alcohol copolymer (a)).  
     
     
         6 . The composition of  claim 1 , wherein the ethylene-vinyl alcohol copolymer (a) has an amount of carboxylic acid ranging from 10 to 5000 ppm (based on the weight of the ethylene-vinyl alcohol copolymer (a)) and an amount of alkali metal salt ranging from 5 to 500 ppm (expressed as ppm by weight of the elemental alkali metal in the ethylene-vinyl alcohol copolymer (a)), and the ratio by weight of the carboxylic acid to the alkali metal salt ranges from 0.1 to 15.  
     
     
         7 . The composition of  claim 1 , wherein the ethylene-vinyl alcohol copolymer (a) has an amount of alkaline earth metal salt ranging from 5 to 250 ppm (expressed as ppm by weight of the elemental alkaline earth metal in the ethylene-vinyl alcohol copolymer (a)).  
     
     
         8 . The composition of  claim 1 , wherein the ethylene-vinyl alcohol copolymer (a) has an amount of carboxylic acid ranging from 10 to 5000 ppm (based on the weight of the ethylene-vinyl alcohol copolymer (a)) and an amount of alkaline earth metal salt ranging from 5 to 250 ppm (expressed as ppm by weight of the elemental alkaline earth metal in the ethylene-vinyl alcohol copolymer (a)), and the ratio by weight of the carboxylic acid to the alkaline earth metal salt ranges from 0.2 to 15.  
     
     
         9 . The composition of  claim 1 , wherein the ethylene-vinyl alcohol copolymer (a) has an amount of phosphate compound ranging from 1 to 300 ppm (expressed as ppm by weight of the total amount of phosphate groups in the ethylene-vinyl alcohol copolymer (a)).  
     
     
         10 . The composition of  claim 1 , wherein the et hylene-vinyl alcohol copolymer (a) is modified with a silicon-containing olefinic unsaturated monomer, and the degree of modification of the copolymer with the monomer ranges from 0.0002 and 0.5 mol % (based on the moles of monomer from which the ethylene-vinyl alcohol copolymer (a) was prepared).  
     
     
         11 . The composition of  claim 1 , wherein the inorganic particles (B) are silica and/or aluminum oxide.  
     
     
         12 . The composition of  claim 1 , wherein the inorganic particles (B) have a hydrophobic surface.  
     
     
         13 . A powder coating composition comprising the composition of  claim 1 .  
     
     
         14 . A multi-layer structure comprising a substrate coated with at least one layer of the powder coating composition of  claim 13 .  
     
     
         15 . The multi-layer structure of  claim 14 , wherein the substrate comprises a metal.  
     
     
         16 . A method for preparing the composition of  claim 1  comprising: 
 dry-blending 100 parts by weight of a powder (A) having a particle size of 22 to 850 μm, and 0.0001 to 2 parts by weight of inorganic particles (B) having primary particles with a mean particle size of from 1 to 100 nm,    wherein powder (A) comprises an ethylene-vinyl alcohol copolymer (a) having an ethylene content of from 2 to 60 mol %, and a degree of saponification of more than 95%.    
     
     
         17 . A method for preparing the composition of  claim 1  comprising: 
 dry-blending 100 parts by weight of an ethylene-vinyl alcohol copolymer (a) having an ethylene content of from 2 to 60 mol %, and a degree of saponification of more than 95%, and 0.0001 to 2 parts by weight of inorganic particles (B) having primary particles with a mean particle size of from 1 to 100 nm, and    grinding the dry-blended ethylene-vinyl alcohol copolymer (a) and inorganic particles (B).    
     
     
         18 . The composition of  claim 1 , further comprising a thermoplastic resin other than EVOH.  
     
     
         19 . The composition of  claim 1 , further comprising an additive selected from the group consisting of a plasticizer, an antioxidant, a pigment, a UV absorbent, and antistatic agent, a crosslinking agent, a filler, and a reinforcing agent.  
     
     
         20 . The composition of  claim 1 , further comprising a thermosetting resin.