Piezo-jettable varnish composition
Herein is described a piezo-jettable varnish composition comprising a latex polymer having a weight averaged molecular weight Mw of greater than about 50 000, a polymeric salt derived from an acidic polymer having a weight averaged molecular weight Mw in the range of about 1000 to about 50 000, water, and a co-solvent, wherein, the latex polymer and polymeric salt are present in amounts such that the ratio of latex polymer to polymeric salt by weight is in the range of greater than about 1:1 to about 8:1.
1. A piezo-jettable varnish composition comprising:
a latex polymer having a weight averaged molecular weight Mw of greater than 50 000;
a polymeric salt derived from an acidic polymer having a weight averaged molecular weight Mw in the range of 1000 to 50 000;
water; and
a co-solvent,
wherein, the latex polymer and polymeric salt are present in amounts such that the ratio of latex polymer to polymeric salt by weight is in the range of greater than 1:1 to 8:1;
wherein the varnish composition has a total solids content in the range of 10 wt % to 50 wt %;
and wherein the varnish composition further comprises:
0.5 wt % to 5 wt % surfactant;
1 wt % to 10 wt % wax;
10 wt % to 85 wt % of the latex polymer; and
5 wt % to 50 wt % of the polymeric salt,
by total solids.
2. The varnish composition according to claim 1 , wherein the polymeric salt is derived from an acidic polymer having an acid number of greater than 100 mg KOH/g.
3. The varnish composition according to claim 1 , wherein the latex polymer and polymeric salt are present in amounts such that the ratio of latex polymer to polymeric salt by weight is in the range of 1.5:1 to 4:1, or the latex polymer and polymeric salt are present in amounts such that the ratio of latex polymer to polymeric salt by weight is in the range of 2.3:1 to 3:1.
4. The varnish composition according to claim 1 , wherein the latex polymer is an acrylic latex polymer and/or the acidic polymer is an acrylic polymer.
5. The varnish composition according to claim 1 , wherein the varnish composition has a minimum film formation temperature in the range of 10° C. to 30° C.
6. The varnish composition according to claim 1 , wherein the latex polymer has a weight averaged molecular weight Mw in the range of greater than 50 000 to 250 000, and the acidic polymer has a weight averaged molecular weight Mw in the range of 1000 to 25 000.
7. A piezo-jettable varnish composition comprising:
a latex polymer having a weight averaged molecular weight Mw of greater than 50 000;
a polymeric salt derived from an acidic polymer having a weight averaged molecular weight Mw in the range of 1000 to 50 000;
water; and
a co-solvent,
wherein, the latex polymer and polymeric salt are present in amounts such that the ratio of latex polymer to polymeric salt by weight is in the range of greater than 1:1 to 8:1;
and wherein the varnish composition further comprises:
0.1 wt % to 2 wt % surfactant;
0.1 wt % to 5 wt % wax;
5 wt % to 45 wt % of the latex polymer;
1 wt % to 25 wt % of the polymeric salt;
40 wt % to 90 wt % of the water; and
2 wt % to 60 wt % of the co-solvent,
by total weight of the composition.
8. A printing method comprising:
providing a printed substrate comprising a print substrate on which a printed image is disposed;
providing a piezo-jettable varnish composition;
jetting the piezo-jettable varnish composition onto the printed substrate to provide a varnish layer disposed on the printed image,
wherein the piezo-jettable varnish composition comprises:
a latex polymer having a weight averaged molecular weight Mw of greater than 50 000;
a polymeric salt derived from an acidic polymer having a weight averaged molecular weight Mw in the range of 1000 to 50 000;
water; and
a co-solvent,
wherein, the latex polymer and polymeric salt are present in amounts such that the ratio of latex polymer to polymeric salt by weight is in the range of greater than 1:1 to 8:1;
and wherein the varnish composition further comprises:
0.1 wt % to 2 wt % surfactant;
0.1 wt % to 5 wt % wax;
5 wt % to 45 wt % of the latex polymer;
1 wt % to 25 wt % of the polymeric salt;
40 wt % to 90 wt % of the water; and
2 wt % to 60 wt % of the co-solvent,
by total weight of the composition.
9. The printing method according to claim 8 , wherein providing the printed substrate comprises jetting an inkjet ink composition onto the print substrate.
10. The printing method according to claim 8 , wherein the print substrate comprises a corrugated board.
11. A piezo-actuatable printhead comprising:
a fluid chamber comprising a piezo-jettable varnish composition; and
an orifice in fluid communication with the fluid chamber such that the varnish composition is jettable from the orifice,
wherein, the piezo-jettable varnish composition comprises:
a latex polymer having a weight averaged molecular weight Mw of greater than 50 000;
a polymeric salt derived from an acidic polymer having a weight averaged molecular weight Mw in the range of 1000 to 50 000;
water; and
a co-solvent,
wherein, the latex polymer and polymeric salt are present in amounts such that the ratio of latex polymer to polymeric salt by weight is in the range of greater than 1:1 to 8:1;
and wherein the varnish composition further comprises:
0.1 wt % to 2 wt % surfactant;
0.1 wt % to 5 wt % wax;
5 wt % to 45 wt % of the latex polymer;
1 wt % to 25 wt % of the polymeric salt;
40 wt % to 90 wt % of the water; and
2 wt % to 60 wt % of the co-solvent,
by total weight of the composition.