Coating powders having enhanced electrostatic chargeability

Abstract

Inert nitrogen-containing compounds, such as melamine, urea, dicyandiamide, and benzoguanamine and derivatives of such compounds are added to thermosetting resin powder coatings to enhance the electrostatic charge of the powders. Such enhancement improves coating processes for non-conductive and conductive substrates.

I claim:  
     
         1 . A coating powder consisting essentially of an inert nitrogen-containing compound which is a member selected from the group consisting of melamine, urea, benzoguanamine, derivatives of melamine, derivatives of urea, and derivatives of benzoguanamine, said compound being present in an effective amount to enhance the electrostatic chargeability of said coating powder, balance essentially a thermosetting resin polymer.  
     
     
         2 . The coating powder of  claim 1 , wherein said thermosetting resin polymer is capable of curing at a temperature below about 300° F.  
     
     
         3 . The coating powder of  claim 1 , wherein said inert nitrogen-containing compound is present in an amount of at least 1 part by weight per 100 parts by weight of resin.  
     
     
         4 . The coating powder of  claim 3 , wherein said inert nitrogen-containing compound is present in an amount from about 1 to about 30 parts by weight per 100 parts by weight of resin.  
     
     
         5 . The coating powder of  claim 4 , wherein said inert nitrogen-containing compound is present in an amount from about 1 to about 20 parts by weight per 100 parts by weight of resin.  
     
     
         6 . The coating powder of  claim 5 , wherein said inert nitrogen-containing compound is present in an amount of from about 5 to about 20 parts by weight per 100 parts by weight of resin.  
     
     
         7 . The coating powder of  claim 1 , wherein said thermosetting resin polymer is a member selected from the group of epoxies, saturated polyesters, polyester-epoxy hybrids, unsaturated polyesters containing a surface curing initiator, acrylics, epoxy functional acrylics, and admixtures thereof.  
     
     
         8 . A coating powder consisting essentially of about 5 to about 20 parts by weight, based upon 100 parts by weight of thermosetting epoxy resin polymer of melamine, balance essentially a thermosetting epoxy resin capable of curing at a temperature below about 300° F.  
     
     
         9 . A process for coating a non-conductive substrate comprising: 
 a) Providing a coating powder consisting essentially of an inert nitrogen-containing compound which is a member selected from the group consisting of melamine, urea, benzoguanamine, derivatives of melamine, derivatives of urea, and derivatives of benzoguanamine, said compound being present in an effective amount to enhance the electrostatic chargeability of said coating powder, balance essentially a thermosetting resin polymer;    b) Applying an electrostatic charge to said coating powder;    c) Contacting a non-conductive substrate with said electrostatically charged powder to form a powder coating on said substrate; and    d) Curing said powder to form a cured coating on said substrate.    
     
     
         10 . The process of  claim 9 , wherein curing of said powder is conducted at a temperature below about 300° F.  
     
     
         11 . The process of  claim 9 , wherein said substrate is a member selected from the group consisting of wood, plastic, paper, and cardboard.  
     
     
         12 . The process of  claim 11 , wherein said inert nitrogen-containing compound is melamine and said substrate is wood.  
     
     
         13 . The process of  claim 9 , wherein said curing is thermal curing.  
     
     
         14 . The process of  claim 9 , wherein said curing is radiation curing.  
     
     
         15 . The process of  claim 9 , wherein said curing is radiation and thermal curing.  
     
     
         16 . The process of  claim 9 , wherein said inert nitrogen-containing compound is present in an amount of at least about 1 part by weight per 100 parts by weight of resin.  
     
     
         17 . The process of  claim 16 , wherein said inert nitrogen-containing compound is present in an amount of at least about 1 part by weight to about 30 parts by weight per 100 parts by weight of resin.  
     
     
         18 . The process of  claim 17 , wherein said inert nitrogen-containing compound is present in an amount of at least about 1 part by weight to about 20 parts by weight per 100 parts by weight of resin.  
     
     
         19 . The process of  claim 18 , wherein said inert nitrogen-containing compound is present in an amount of at least about 5 parts by weight to about 20 parts by weight per 100 parts by weight of resin.  
     
     
         20 . A powder coated article comprising a non-conductive substrate coated with a cured coating powder consisting essentially of an inert nitrogen-containing compound which is a member selected from the group consisting of melamine, urea, benzoguanamine, derivatives of melamine, derivatives of urea, and derivatives of benzoguanamine, said compound being present in an effective amount to enhance the electrostatic chargeability of said coating powder, balance essentially a thermosetting resin polymer.  
     
     
         21 . The powder coated article of  claim 20 , wherein said thermosetting resin polymer is capable of curing at a temperature below about 300° F.  
     
     
         22 . The powder coated article of  claim 20 , wherein said inert nitrogen-containing compound is present in an amount of at least about I part by weight per 100 parts by weight of resin.  
     
     
         23 . The powder coated article of  claim 22 , wherein said inert nitrogen-containing compound is present in an amount of at least about 1 part by weight to about 30 parts by weight per 100 parts by weight of resin.  
     
     
         24 . The powder coated article of  claim 23 , wherein said inert nitrogen-containing compound is present in an amount of at least about 1 part by weight to about 20 parts by weight per 100 parts by weight of resin.  
     
     
         25 . The powder coated article of  claim 24 , wherein said inert nitrogen-containing compound is present in an amount of at least about 5 parts by weight to about 20 parts by weight per 100 parts by weight of resin.  
     
     
         26 . The powder coated article of  claim 20  wherein said thermosetting resin polymer is a member selected from the group of epoxies, saturated polyesters, polyester-epoxy hybrids, unsaturated polyesters containing a surface curing initiator, acrylics, epoxy functional acrylics, and admixtures thereof.  
     
     
         27 . The powder coated article of  claim 20 , wherein said non-conductive substrate is a member selected from the group consisting of glass, ceramics, ceramic tile, carbon, and graphite.  
     
     
         28 . A powder coated article comprising a non-conductive substrate coated with a cured coating powder consisting essentially of about 1 to 30 parts by weight, based upon 100 parts by weight of thermosetting epoxy resin polymer, of melamine, balance essentially a thermosetting epoxy resin polymer capable of curing at a temperature below about 300° F.  
     
     
         29 . A coating powder consisting essentially of dicyandiamide in inert form, said dicyandiamide being present in an effective amount to enhance the electrostatic chargeability of said coating powder, balance essentially a thermosetting resin polymer which is a member selected from the group epoxies which do not contain a curing agent which catalyzes a curing reaction between said epoxies and dicyandiamide, saturated polyesters, polyester-epoxy hybrids, unsaturated polyesters containing a surface curing initiator, acrylics, epoxy functional acrylics, and admixtures thereof  
     
     
         30 . The coating powder of  claim 29 , wherein said thermosetting resin polymer is capable of curing at a temperature below about 300° F.  
     
     
         31 . The coating powder of  claim 29 , wherein said inert nitrogen-containing compound is present in an amount from about 1 to about 30 parts by weight per 100 parts by weight of resin.  
     
     
         32 . A process for coating a non-conductive substrate, comprising 
 a) Providing a coating powder consisting essentially of dicyandiamide in inert form, said dicyandiamide being present in an effective amount to enhance the electrostatic chargeability of said coating powder, balance essentially a thermosetting resin polymer which is a member selected from the group epoxies which do not contain a curing agent which catalyzes a curing reaction between said epoxies and dicyandiamide, saturated polyesters, polyester-epoxy hybrids, unsaturated polyesters containing a surface curing initiator, acrylics, epoxy functional acrylics, and admixtures thereof;    b) Applying an electrostatic charge to said coating powder;    c) Contacting a non-conductive substrate with said electrostatically charged powder to form a powder coating on said substrate; and    d) Curing said powder to form a cured coating on said substrate.    
     
     
         33 . The process of  claim 32 , wherein curing of said powder is conducted at a temperature below about 300° F.  
     
     
         34 . The process of  claim 32 , wherein said substrate is a member selected from the group consisting of wood, plastic, paper, and cardboard.  
     
     
         35 . The process of  claim 34  wherein said inert nitrogen-containing compound is melamine and said substrate is wood.  
     
     
         36 . The process of  claim 32 , wherein said curing is thermal curing.  
     
     
         37 . A powder coated article comprising a non-conductive substrate coated with a cured coating powder consisting essentially of dicyandiamide in inert form, said dicyandiamide being present in an effective amount to enhance the electrostatic chargeability of said coating powder, balance essentially a thermosetting resin polymer which is a member selected from the group epoxies which do not contain a curing agent which catalyzes a curing reaction between said epoxies and dicyandiamide, saturated polyesters, polyester-epoxy hybrids, unsaturated polyesters containing a surface curing initiator, acrylics, epoxy functional acrylics, and admixtures thereof.  
     
     
         38 . The powder coated article of  claim 37 , wherein said thermosetting resin polymer is capable of curing at a temperature below about 300° F.  
     
     
         39 . The powder coated article of  claim 37  wherein said inert nitrogen-containing compound is present in an amount from about 1 to about 30 parts by weight per 100 parts by weight of resin.  
     
     
         40 . The powder coated article of  claim 39 , wherein said inert nitrogen-containing compound is present in an amount from about 1 to about 20 parts by weight per 100 parts by weight of resin.  
     
     
         41 . A process for coating a conductive substrate comprising: 
 a) Providing a coating powder consisting essentially of an inert nitrogen-containing compound which is a member selected from the group consisting of melamine, urea, benzoguanamine, derivatives of melamine, derivatives of urea, and derivatives of benzoguanamine, said compound being present in an effective amount to enhance the electrostatic chargeability of said coating powder, balance essentially a thermosetting resin polymer;    b) Applying an electrostatic charge to said coating powder;    c) Contacting a conductive substrate with said electrostatically charged powder to form a powder coating on said substrate; and    d) Curing said powder to form a cured coating on said substrate.    
     
     
         42 . The process of  claim 41 , wherein curing of said powder is conducted at a temperature below about 300° F.  
     
     
         43 . The process of  claim 41 , wherein said substrte is metal.  
     
     
         44 . A process for coating a conductive substrate comprising: 
 a) Providing a coating powder consisting essentially of a metal, said compound being present in an effective amount to enhance the electrostatic chargeability of said coating powder, balance essentially a thermosetting resin polymer;    b) Applying an electrostatic charge to said coating powder;    c) Contacting a conductive substrate with said electrostatically charged powder to form a powder coating on said substrate; and    d) Curing said powder to form a cured coating on said substrate.    
     
     
         45 . A powder coated article comprising a conductive substrate coated with a cured coating powder consisting essentially of an inert nitrogen-containing compound which is a member selected from the group consisting of melamine, urea, benzoguanamine, derivatives of melamine, derivatives of urea, and derivatives of benzoguanamine, said compound being present in an effective amount to enhance the electrostatic chargeability of said coating powder, balance essentially a thermosetting resin polymer.  
     
     
         46 . A process for coating a conductive substrate, comprising 
 a) Providing a coating powder consisting essentially of dicyandiamide in inert form, said dicyandiamide being present in an effective amount to enhance the electrostatic chargeability of said coating powder, balance essentially a thermosetting resin polymer which is a member selected from the group epoxies which do not contain a curing agent which catalyzes a curing reaction between said epoxies and dicyandiamide, saturated polyesters, polyester-epoxy hybrids, unsaturated polyesters containing a surface curing initiator, acrylics, epoxy functional acrylics, and admixtures thereof,    b) Applying an electrostatic charge to said coating powder;    c) Contacting a conductive substrate with said electrostatically charged powder to form a powder coating on said substrate; and    d) Curing said powder to form a cured coating on said substrate.    
     
     
         47 . A powder coated article comprising a conductive substrate coated with a cured coating powder consisting essentially of dicyandiamide in inert form, said dicyandiamide being present in an effective amount to enhance the electrostatic chargeability of said coating powder, balance essentially a thermosetting resin polymer which is a member selected from the group epoxies which do not contain a curing agent which catalyzes a curing reaction between said epoxies and dicyandiamide, saturated polyesters, polyester-epoxy hybrids, unsaturated polyesters containing a surface curing initiator, acrylics, epoxy functional acrylics, and admixtures thereof.