Printing primer composition for adjusting a substrate

A primer kit to adjust a surface of a substrate with a printing primer (P3), wherein said primer kit comprises:

• a first primer P1 comprising:
• a first polymeric component A1 having a first polar contribution pc1 of less than 20%;
• and a second component B1 comprising:
• an inorganic particle B1′ and/or a second polymeric binder component B1″;
• wherein said polymeric binder component B1″ has a second polar contribution pc2 equal or higher than 20%;
• a second primer P2 comprising:
• a third polymeric component A2 having a third polar contribution pc3 of less than 20%;
• and/or
• a fourth component B2, selected from one or more of:
• an inorganic particle B2′, and a fourth polymeric binder component B2″ having a fourth polar contribution pc4 equal or higher than 20%, wherein the first primer P1 is different from the second primer P2,
• such that
• the wt %-ratio of (A1+A2)/(B1+B2) in the printing primer P3 can be adjusted by mixing a first amount of first primer and a second amount of second primer, in order to adjust the surface of the substrate as desired by applying the printing primer P3 thus obtained thereon,
• wherein said first, second, third, and fourth polar contributions pc1, pc2, pc3, pc4 are determined by the following method:
• applying a 6 gsm dry layer of the respective components, respectively;
• applying a 1 μL droplet of ethylene glycol on the dry layer and measuring the contact angle CA1 after 10 seconds equilibrium time;
• applying a 1 μL droplet of diiodomethane on the dry layer and measuring the contact angle CA2 after 10 seconds equilibrium time;
• applying a 1 μL droplet of thiodiglycol on the dry layer and measuring the contact angle CA3 after 10 seconds equilibrium time;
• calculating the polar surface free energy, dispersive surface free energy and total surface free energy, wherein the total surface free energy is the sum of the polar surface free energy and the dispersive surface free energy, wherein the calculation is performed using the Owens-Wendt-Rabel-Kaelble method using contact angles CA1, CA2 and CA3 as input values;
• and
• wherein the polar contribution is the ratio of the polar surface free energy over the total surface free energy value as determined for the respective components, expressed as a percentage.

A method to obtain a printing primer P3 for adjusting ink receptibility of a substrate by applying said printing primer P3 thereon, said method comprising:

• providing a first primer P1 comprising:
• a first polymeric component A1 having a first polar contribution pc1 of less than 20%;
• and/or
• a second component B1 comprising:
• an inorganic particle B1′ and/or a second polymeric binder component B1″;
• wherein said polymeric binder component B1″ has a second polar contribution pc2 equal or higher than 20%;
• providing a second primer P2 comprising:
• a third polymeric component A2 having a third polar contribution pc3 of less than 20%;
• and/or
• a fourth component B2 comprising:
• an inorganic particle B2′ and/or a fourth polymeric binder component B2″;
• wherein said fourth polymeric binder component B2″ has a fourth polar contribution pc4 equal or higher than 20%;
• with the proviso that at least one of the primers P1, P2 includes a polymeric component having a polar contribution of less than 20% and that the other one of the primers P1, P2 include a component selected from one or more of:
• an inorganic particle, a polymeric component having a polar contribution of more than 20%;
• mixing a first amount p1 of the first primer P1 and a second amount p2 of the second primer P2 to form the printing primer P3;
• applying the printing primer P3 on a surface of the substrate;
• testing the ink receptibility by printing a test image;
• and if required adjust the first amount p1 and/or the second amount p2 to set wt %-ratio of (A1+A2)/(B1+B2) in the printing primer P3 based a characteristic of the printed test image,
• wherein said first, second, third, and fourth polar contributions pc1, pc2, pc3, pc4 are determined by the following method:
• applying a 6 gsm dry layer of the respective components, respectively;
• applying a 1 μL droplet of ethylene glycol on the dry layer and measuring the contact angle CA1 after 10 seconds equilibrium time;
• applying a 1 μL droplet of diiodomethane on the dry layer and measuring the contact angle CA2 after 10 seconds equilibrium time;
• applying a 1 μL droplet of thiodiglycol on the dry layer and measuring the contact angle CA3 after 10 seconds equilibrium time;
• calculating the polar surface free energy, dispersive surface free energy and total surface free energy, wherein the total surface free energy is the sum of the polar surface free energy and the dispersive surface free energy, wherein the calculation is performed using the Owens-Wendt-Rabel-Kaelble method using contact angle's CA1, CA2 and CA3 as input values;
• and wherein the polar contribution is the ratio of the polar surface free energy over the total surface free energy value as determined for the respective components, expressed as a percentage.