Pre-treatments for publishing print media

Abstract

A pre-treatment coating composition can include an evaporable liquid vehicle and a pre-treatment coating matrix carried by the evaporable liquid vehicle. The pre-treatment coating matrix in this example can include from 30 wt % to 70 wt % multivalent organic salt including a multivalent metal acetate or a multivalent metal propionate, from 5 wt % to 30 wt % dispersed polymeric binder having a weight average molecular weight from 20,000 Mw to 1,000,000 Mw, from 0.5 wt % to 8 wt % of a high molecular weight polyvinyl alcohol binder, and from 10 wt % to 30 wt % of a low molecular weight polyvinyl alcohol binder. The low molecular weight polyvinyl alcohol binder and the high molecular weight polyvinyl alcohol binder in this example can be present in the pre-treatment coating matrix at a 3:1 to 15:1 weight ratio. Weight percentages in this example are based on dry weight of the pre-treatment coating matrix.

What is claimed is: 
     
         1 . A pre-treatment coating composition, comprising:
 an evaporable liquid vehicle; and   a pre-treatment coating matrix carried by the evaporable liquid vehicle, the pre-treatment coating matrix, comprising:
 from 30 wt % to 70 wt % multivalent organic salt including a multivalent metal acetate or a multivalent metal propionate, 
 from 5 wt % to 30 wt % dispersed polymeric binder having a weight average molecular weight from 20,000 Mw to 1,000,000 Mw, 
 from 0.5 wt % to 8 wt % of a high molecular weight polyvinyl alcohol binder, and 
 from 10 wt % to 30 wt % of a low molecular weight polyvinyl alcohol binder, 
   
       wherein the low molecular weight polyvinyl alcohol binder and the high molecular weight polyvinyl alcohol binder are present in the pre-treatment coating matrix at a 3:1 to 15:1 weight ratio, and wherein weight percentages are based on dry weight of the pre-treatment coating matrix. 
     
     
         2 . The pre-treatment coating composition of  claim 1 , wherein the multivalent salt includes a divalent metal selected from calcium, magnesium, iron, aluminum, zinc, or a combination thereof. 
     
     
         3 . The pre-treatment coating composition of  claim 1 , wherein the dispersed polymeric binder includes a dispersed polyurethane binder. 
     
     
         4 . The pre-treatment coating composition of  claim 4 , wherein the dispersed polyurethane binder has a weight average molecular weight from 30,000 Mw to 100,000 Mw. 
     
     
         5 . The pre-treatment coating composition of  claim 1 , further comprising a block copolymer surfactant that stabilizes components of the pre-treatment coating matrix by steric hindrance, and having a weight average molecular weight from 4,000 Mw to 12,000 Mw with an acid value from 5 mg KOH/g to 30 mg KOH/g. 
     
     
         6 . A publishing print medium, comprising:
 a media substrate having a basis weight of 50 gsm to 350 gsm; and   a first pre-treatment matrix layer on a first side of the media substrate and a second pre-treatment matrix layer on a second side of the media substrate, the first pre-treatment matrix layer and the second pre-treatment matrix layer independently comprising:
 from 30 wt % to 70 wt % multivalent organic salt, 
 from 5 wt % to 30 wt % dispersed polymeric binder having a weight average molecular weight from 20,000 Mw to 1,000,000 Mw, 
 from 0.5 wt % to 8 wt % of a high molecular weight polyvinyl alcohol binder, and 
 from 10 wt % to 30 wt % of a low molecular weight polyvinyl alcohol binder, 
   
       wherein the low molecular weight polyvinyl alcohol binder and the high molecular weight polyvinyl alcohol binder are present in the pre-treatment matrix layer at a 3:1 to 15:1 weight ratio, and wherein weight percentages are based on dry weight of the pre-treatment matrix layer. 
     
     
         7 . The publishing print medium of  claim 6 , wherein the multivalent organic salt includes a divalent metal cation selected from calcium, magnesium, iron, aluminum, zinc, or a combination thereof, and an anion selected from acetate, propionate, or a combination thereof. 
     
     
         8 . The publishing print medium of  claim 6 , wherein the dispersed polymeric binder includes a dispersed polyurethane binder. 
     
     
         9 . The publishing print medium of  claim 6 , wherein the dispersed polymeric binder includes a polymer or a copolymer including polyurethane, acrylic, vinyl acetate, polyester, vinylidene chloride, butadiene, styrene-butadiene, acrylonitrile-butadiene, or sulfonated styrene-butadiene. 
     
     
         10 . A method of preparing a publishing print medium, comprising: 
       coating a first side of media substrate with a first pre-treatment coating composition and a second side of media substrate with a second pre-treatment coating composition, the first and second pre-treatment coating compositions comprising an evaporable liquid vehicle and a pre-treatment coating matrix carried by the evaporable liquid vehicle, the pre-treatment coating matrix, comprising:
 from 30 wt % to 70 wt % multivalent organic salt, 
 from 5 wt % to 30 wt % dispersed polymeric binder having a weight average molecular weight from 20,000 Mw to 1,000,000 Mw, 
 from 0.5 wt % to 8 wt % of a high molecular weight polyvinyl alcohol binder, and 
 from 10 wt % to 30 wt % of a low molecular weight polyvinyl alcohol binder, 
 
       wherein the low molecular weight polyvinyl alcohol binder and the high molecular weight polyvinyl alcohol binder are present in the pre-treatment coating matrix at a 3:1 to 15:1 weight ratio, and wherein weight percentages are based on dry weight of the pre-treatment coating matrix;
 drying the first pre-treatment coating composition to remove evaporable liquid vehicle therefrom to form a first pre-treatment matrix layer; and 
 drying the second pre-treatment coating composition to remove evaporable liquid vehicle therefrom to form a second pre-treatment matrix layer. 
 
     
     
         11 . The method of  claim 10 , wherein the media substrate has a basis weight from 50 gsm to 350 gsm. 
     
     
         12 . The method of  claim 10 , wherein the first pre-treatment coating composition is applied to the first side at a basis weight from 0.1 gsm to 10 gsm, and the second pre-treatment coating composition is applied to the second side at a basis weight from 0.1 gsm to 10 gsm. 
     
     
         13 . The method of  claim 10 , further comprising printing on both sides of the publishing print medium. 
     
     
         14 . The method of  claim 10 , wherein coating the first side and the second side is carried out in-line with the printing. 
     
     
         15 . The method of  claim 10 , wherein the multivalent organic salt includes a divalent metal cation selected from calcium, magnesium, iron, aluminum, zinc, or a combination thereof, and an anion selected from acetate, propionate, or a combination thereof.