Primer coated amorphous plastic films

Abstract

Water-dissipative copolyesters are primer coatings for substantially amorphous polymeric films providing improved ink adhesion and improved slip characteristics. The primer coatings comprise copolyester having repeat units from a dicarboxylic acid component comprising 8 to 25 mole percent 5-sulfoisophthalic acid and 75 to 92 mole percent isophthalic acid and repeat units from a diol component comprising 25 to 100 mole percent diethylene glycol, 0 to 75 mole percent 1,4-cyclohexane-dimethanol, and 0 to 30 mole percent ethylene glycol, based on 100 mole percent dicarboxylic acid component and 100 mole percent diol component. The polymeric films are preferably polyester, polycarbonate or poly(vinyl chloride). These copolyesters primer coatings are generally dispersed in water or water/alcohol mixtures to a solids content of 20 to 35 weight percent.

We claim:  
     
       1. A method for improving slip characteristics of a polymeric film when contacted with other polymeric films and improving ink adhesion to the surface of the polymeric film comprising the steps of: 
       a) applying to a surface of a substantially amorphous polymeric film a sufficient amount of a primer coating to improve adhesion of inks to the surface of the film and reduce a coefficient of friction as compared to a film without the primer coating thereon, wherein the primer coating comprises (i) 95 to 100 weight percent copolyester having repeat units from a dicarboxylic acid component comprising 8 to 25 mole percent 5-sulfoisophthalic acid and 75 to 92 mole percent isophthalic acid and repeat units from a diol component comprising 25 to 100 mole percent diethylene glycol, 0 to 75 mole percent 1,4-cyclohexane-dimethanol, and 0 to 30 mole percent ethylene glycol, based on 100 mole percent dicarboxylic acid component and 100 mole percent diol component, and (ii) 0 to 5 weight percent wax, and the film comprises a copolyester having repeat units from a dicarboxylic acid component comprising at least 75 mole percent terephthalic acid or naphthalene dicarboxylic acid and repeat units from a diol component comprising 0.5 to 65 mole percent 1,4-cyclohexanedimethanol and 35 to 99.5 mole percent ethylene glycol, based on 100 mole percent dicarboxylic acid component and 100 mole percent diol component;  
       b) drying the primer coating; and  
       c) printing ink on the primer coated surface of the film.  
     
     
       2. The method of claim  1  wherein the primer coating is applied as a dispersion having a solids content of 15 to 40 weight percent 
     
     
       3. The method of claim  1  wherein the dispersion is prepared in water, a C 1 -C 4  alcohol or mixtures thereof. 
     
     
       4. The method of claim  1  wherein the primer coating is applied to a thickness of 0.1 to 0.2 mils. 
     
     
       5. The method of claim  1  wherein the step of drying the primer coating is at temperatures of 250 to 300° F. 
     
     
       6. The method of claim  1  wherein said primer coating comprises 9 to 15 mole percent of 5-sulfoisophthalic acid, 85 to 91 mole percent isophthalic acid, and 31 to 80 mole percent diethylene glycol. 
     
     
       7. The method of claim  1  wherein the coefficient of friction is reduced by at least 10 percent for the film having a primer coating thereon as compared to the same film without the primer coating. 
     
     
       8. A method for improving slip characteristics of a polymeric film when contacted with other polymeric films and improving ink adhesion to the surface of the polymeric film comprising the steps of: 
       a) applying to a surface of a substantially amorphous polymeric film a sufficient amount of a primer coating to improve adhesion of inks to the surface of the film and reduce a coefficient of friction as compared to a film without the primer coating thereon, wherein the primer coating comprises (i) 95 to 100 weight percent copolyester having repeat units from a dicarboxylic acid component comprising 8 to 25 mole percent 5-sulfoisophthalic acid and 75 to 92 mole percent isophthalic acid and repeat units from a diol component comprising 25 to 100 mole percent diethylene glycol, 0 to 75 mole percent 1,4-cyclohexane-dimethanol, and 0 to 30 mole percent ethylene glycol, based on 100 mole percent dicarboxylic acid component and 100 mole percent diol component, and (ii) 0.25 to 5.00 weight percent wax, and the film is selected from the group consisting of poly(ethylene terephthalate); poly(ethylene naphthalene dicarboxylate); polycarbonate and polyvinyl chloride;  
       b) drying the primer coating; and  
       c) printing an ink on the primer coated surface of the film.  
     
     
       9. A method for printing on a polymeric film, including the steps of applying an aqueous dispersion of a primer coating onto a polymeric substrate, drying the primer coating, and applying an ink to the coated polymeric substrate, wherein the improvement comprises utilizing the primer coating to improve ink adhesion such that said film exhibits 100 percent ink adhesion retention to the coated polymeric substrate, the polymeric substrate being a substantially amorphous polymer formed by melt extrusion, the primer coating having repeat units from a dicarboxylic acid component comprising 8 to 25 mole percent 5-sulfoisophthalic acid and 75 to 92 mole percent isophthalic acid and repeat units from a diol component comprising 25 to 100 mole percent diethylene glycol, 0 to 75 mole percent 1,4-cyclohexanedimethanol, and 0 to 30 mole percent ethylene glycol, based on 100 mole percent dicarboxylic acid component and 100 mole percent diol component. 
     
     
       10. The method of claim  9  wherein the primer coating comprises 9 to 15 mole percent of 5-sodioisophthalic acid, 85 to 91 mole percent isophthalic acid, and 31 to 80 mole percent diethylene glycol. 
     
     
       11. The method of claim  9  wherein the primer coating is further utilized to reduce the coefficient of friction of the polymeric film and further comprises up to 5 weight percent wax based on the total weight of the primer coating, and the polymeric substrate comprises a copolyester having repeat units from a dicarboxylic acid component comprising at least 75 mole percent terephthalic acid or naphthalene dicarboxylic acid and repeat units from a diol component comprising 0.5 to 65 mole percent 1,4-cyclohexanedimethanol and 35 to 99.5 mole percent ethylene glycol, based on 100 mole percent dicarboxylic acid component and 100 mole percent diol component; 
     
     
       12. The method of claim  9  wherein the primer coating is further utilized to reduce the coefficient of friction of the polymeric film and further comprises 0.25 to 5.00 weight percent wax based on the total weight of the primer coating and the polymeric substrate is selected from the group consisting of poly(ethylene terephthalate); poly(ethylene naphthalene dicarboxylate); polycarbonate and polyvinyl chloride.