Paper for inkjet recording
The present invention concerns a print medium for inkjet printing and a method of producing such a print medium. In particular, the present invention is directed to a print medium comprising a base layer having a first side and a reverse side, an absorptive layer being in contact with the first side of the base layer, and a topcoat being in contact with the absorptive layer.
1. A method for manufacturing a print medium comprising the following steps:
a) providing a base layer having a first side and a reverse side;
b) applying a liquid coating formulation comprising a pigment to form an absorptive layer on the first side of the base layer;
c) applying a liquid coating formulation comprising a pigment having a d 50 value in a range of from 0.01 to 1.0 μm and a BET specific surface area of 10 to 30 m 2 /g onto the absorptive layer to form a topcoat, wherein the pigment comprises calcium carbonate; and
d) drying the absorptive layer and the topcoat, wherein the absorptive layer and the topcoat are either dried simultaneously or the absorptive layer is dried after step b) and before applying the topcoat according to step c), and
wherein the topcoat has a permeability of greater than 5.0×10 −18 m 2 .
2. The method of claim 1 , wherein the base layer is a wood free paper or a wood containing paper.
3. The method of claim 2 , wherein the base layer has a basis weight of from 30 to 300 g/m 2 .
4. The method of claim 1 , wherein steps b) to d) are also carried out on the reverse side of the base layer to manufacture a print medium being coated on the first side and the reverse side.
5. The method of claim 1 , wherein the absorptive layer has an absorption rate from 1×10 −5 ms −0.5 to 1×10 −3 ms −0.5 and/or a volume uptake from 30 to 95% by volume relative to the total volume of the absorptive layer.
6. The method of claim 1 , wherein the pigment of the absorptive layer has a BET specific surface area of greater than 25 m 2 /g.
7. The method of claim 1 , wherein the pigment of the absorptive layer has a BET specific surface area of from 25 to 100 m 2 /g.
8. The method of claim 1 , wherein the pigment of the absorptive layer has a BET specific surface area of from 30 to 50 m 2 /g.
9. The method of claim 1 , wherein the pigment of the absorptive layer has a BET specific surface area of greater than 25 m 2 /g, a d 50 value from 0.3 to 3 μm and a porosity, when in form of a compacted bed, of greater or equal to 35%.
10. The method of claim 1 , wherein the pigment of the absorptive layer is a calcium carbonate, a plastic pigment, a polystyrene-based plastic pigment, titanium dioxide, dolomite, calcined clay, or any mixture thereof, or a mixture of one or more of calcium carbonate, titanium dioxide, dolomite, or calcined clay with one or more of talc, non-calcined clay or bentonite.
11. The method of claim 1 , wherein the pigment of the absorptive layer is a calcium carbonate.
12. The method of claim 1 , wherein the pigment of the absorptive layer is a modified calcium carbonate and/or a precipitated calcium carbonate.
13. The method of claim 12 , wherein the calcium carbonate is in acicular, prismatic, spherical, or rhombohedral form or any combination thereof.
14. The method of claim 1 , wherein the liquid coating formulation used to form the absorptive layer further contains a dispersant in an amount of 0.05 to 5 wt.-%, based on total weight of the pigment.
15. The method of claim 1 , wherein the absorptive layer further comprises a binder in an amount of 1 to 50 wt.-% based on the total weight of the pigment.
16. The method of claim 15 , wherein the binder is starch, polyvinyl alcohol, styrene-butadiene latex, styrene-acrylate latex, or polyvinyl acetate latex or any mixture thereof.
17. The method of claim 1 , wherein the absorptive layer has a coat weight in a range from 3 to 50 g/m 2 .
18. The method of claim 1 , wherein the absorptive layer has a coat weight in a range from 3 to 40 g/m 2 .
19. The method of claim 1 , wherein the absorptive layer has a coat weight in a range from 6 to 20 g/m 2 .
20. The method of claim 1 , wherein the pigment of the topcoat comprises calcium carbonate and one or more of titanium dioxide, dolomite, calcined clay and bentonite.
21. The method of claim 1 , wherein the pigment of the topcoat comprises ground calcium carbonate and/or a precipitated calcium carbonate.
22. The method of claim 1 , wherein the pigment of the top coat has a BET specific surface area of 10 to 20 m 2 /g.
23. The method of claim 1 , wherein the topcoat further contains a binder in an amount of 0.5 to 50 wt.-% based on the total weight of the pigment.
24. The method of claim 23 , wherein the binder is selected from starch, polyvinyl alcohol, styrene-butadiene latex, styrene-acrylate latex, or polyvinyl acetate latex or any mixture thereof.
25. The method of claim 1 , wherein the topcoat further comprises a rheology modifier in an amount of less than 1 wt.-% based on the total weight of the pigment.
26. The method of claim 1 , wherein the topcoat has a coat weight in a range from 1 to 50 g/m 2 .
27. The method of claim 1 , wherein the topcoat has a coat weight in a range from 3 to 40 g/m 2 .
28. The method of claim 1 , wherein the topcoat has a coat weight in a range from 6 to 20 g/m 2 .
29. The method of claim 1 , wherein the absorptive layer comprises calcium carbonate, polyvinyl alcohol, starch and a cationic additive, and the top layer comprises calcium carbonate, a styrene-butadiene latex and carboxymethylcellulose.