Clear coating composition

Abstract

Provided are a clear coating composition which is used for top coats, the composition containing a crosslinking agent and a functional group-containing (meth)acrylate polymer formed by polymerization of a monomer component that includes an aromatic ring-containing (meth)acrylate and a functional group-containing monomer. Also provided is a clear coat composition which is used for top coats, the composition containing a crosslinking agent and a functional group-containing (meth)acrylate polymer formed by polymerization of a monomer component that includes a functional group-containing monomer and a fluorine atom-containing monomer. This clear coat composition has low colorability, has a high refractive index without the use of a filler, provides excellent glossy even when a filler is used, and can be applied to a thick film.

1 . A clear coating composition used for a top coat, comprising
 (A) a functional group-containing (meth)acrylate-based polymer made by the polymerization of a monomer component comprising   (i) a functional group-containing monomer represented by the formula (I):   
       
         
           
           
               
               
           
         
         wherein R 1  represents hydrogen atom or methyl group, and R 2  represents hydroxyl group, an alkyl group of 1 to 4 carbon atoms having hydroxyl group, carboxyl group, an alkyl group of 1 to 4 carbon atoms having carboxyl group, epoxy group, an alkyl group of 1 to 4 carbon atoms having epoxy group, a hydroxyalkyloxycarbonyl group having a hydroxyalkyl group of 1 to 4 carbon atoms or a group represented by the formula: 
       
       
         
           
           
               
               
           
         
         wherein n represents an integer of 3 to 20, 
         (ii) a fluorine atom-containing monomer represented by the formula (II): 
       
       
         
           
           
               
               
           
         
         wherein R 1  is the same as mentioned above, and R 3  represents an alkyl group of 1 to 12 carbon atoms having 3 to 8 fluorine atoms, and 
         (iii) another monomer other than the functional group-containing monomer and the fluorine atom-containing monomer in a content of 30% by mass or less in the monomer component, wherein said another monomer is at least one monomer selected from the group consisting of alkyl (meth)acrylates, N-substituted (meth)acrylamides and aliphatic (meth)acrylic monomers having a carbon-carbon unsaturated double bond, and 
         (B) a polyisocyanate as a crosslinking agent. 
       
     
     
         2 . The clear coating composition according to  claim 1 , further comprising at least one solvent selected from the group consisting of ketones, ethers and esters of acetic acid. 
     
     
         3 . A coating film formed from the clear coating composition according to  claim 1 . 
     
     
         4 . A coating film formed from the clear coating composition according to  claim 2 . 
     
     
         5 . A process for producing a clear coating composition according to  claim 1 , comprising:
 (A) dissolving a polyisocyanate as a crosslinking agent in an organic solvent selected from the group consisting of ketones, ethers and esters of acetic acid, to give a solution,   (B) adding a monomer component comprising the functional group-containing monomer, the fluorine atom-containing monomer and another monomer other than the functional group-containing monomer and the fluorine atom-containing monomer to the solution obtained in the above step (A), wherein the content of said another monomer in the monomer component is 30% by mass or less, and   (C) polymerizing the monomer component.   
     
     
         6 . A process for producing a clear coating composition according to  claim 2 , comprising:
 (A) dissolving a polyisocyanate as a crosslinking agent in an organic solvent selected from the group consisting of ketones, ethers and esters of acetic acid, to give a solution,   (B) adding a monomer component comprising the functional group-containing monomer, the fluorine atom-containing monomer and another monomer other than the functional group-containing monomer and the fluorine atom-containing monomer to the solution obtained in the above step (A), wherein the content of said another monomer in the monomer component is 30% by mass or less, and   (C) polymerizing the monomer component.