Ink jet recording method and ink jet recording apparatus
To provide an ink jet recording method using facedown discharge and capable of obtaining a recorded matter being suppressed a generation of minus curl. The method provided is an ink jet recording method including a step of recording an image on a recording medium having a first surface and a second surface by ejecting an aqueous ink from a recording head. This method further includes, after the recording step, a step of discharging the recording medium while placing the first surface or the second surface on which the image has been recorded last on a gravitationally lower side. In this method, the aqueous ink has a viscosity η 1 of 5.0 mPa·s or more and a difference η 2 −η 1 between a viscosity η 2 of an evaporated ink obtained by evaporating 20% by mass of the aqueous ink and the viscosity η 1 of the aqueous ink is 4.0 mPa·s or more.
1. An ink jet recording method comprising:
a step of recording an image on a recording medium having a first surface and a second surface, by ejecting an aqueous ink from a recording head; and
after the recording step, a step of discharging the recording medium while placing the first surface or the second surface on which the image has been recorded last on a gravitationally lower side,
wherein the aqueous ink has a first viscosity η 1 (mPa·s) of 5.0 mPa·s or more and an evaporated ink, which is obtained by evaporating 20% by mass of the aqueous ink, has a second viscosity η 2 (mPa·s), with a difference η 2 −η 1 (mPa·s) being 4.0 mPa·s or more.
2. The ink jet recording method according to claim 1 , wherein a content (% by mass) of water in the aqueous ink is 66.0% by mass or less based on a total mass of the ink.
3. The ink jet recording method according to claim 2 , wherein the content (% by mass) of water in the aqueous ink is 35.0% by mass or more based on the total mass of the ink.
4. The ink jet recording method according to claim 1 ,
wherein the aqueous ink comprises a polyhydric alcohol compound solid at 25° C., and
wherein a content (% by mass) of the polyhydric alcohol compound in the aqueous ink is 10.0% by mass or more based on the total mass of the ink.
5. The ink jet recording method according to claim 4 ,
wherein the aqueous ink comprises a resin particle having a unit containing an alkylene oxide group, and
wherein a percentage (% by mass) of the unit containing the alkylene oxide group in the resin particle is 3.0% by mass or more.
6. The ink jet recording method according to claim 5 , wherein the unit containing the alkylene oxide group is a unit derived from a monomer having 8 or more alkylene oxide groups.
7. The ink jet recording method according to claim 5 , wherein the resin particle has a surface charge amount (μmol/g) of 500 μmol/g or less.
8. The ink jet recording method according to claim 5 , wherein a mass ratio, in the aqueous ink, of a content (% by mass) of the resin particle to a content (% by mass) of the polyhydric alcohol compound is 0.25 times or more to 1.00 time or less.
9. The ink jet recording method according to claim 5 , wherein the percentage (% by mass) of the unit containing the alkylene oxide group in the resin particle is 10.0% by mass or less.
10. The ink jet recording method according to claim 4 , wherein the content (% by mass) of the polyhydric alcohol compound in the ink is 35.0% by mass or less based on the total mass of the ink.
11. The ink jet recording method according to claim 1 , wherein the first viscosity η 1 (mPa·s) of the aqueous ink is 15.0 mPa·s or less.
12. The ink jet recording method according to claim 1 , wherein the second viscosity η 2 (mPa·s) of the evaporated ink is the 9.0 mPa·s or more to 25.0 mPa·s or less.
13. The ink jet recording method according to claim 1 , wherein η 2 −η 1 is 15.0 mPa·s or less.
14. The ink jet recording method according to claim 1 , wherein the recording medium has a paper as a base material with no coating layer.
15. The ink jet recording method according to claim 1 , wherein the recording head is a line head.
16. An ink jet recording apparatus to be used for recording an image on a recording medium having a first surface and a second surface, by ejecting an aqueous ink from a recording head, the apparatus comprising:
a facedown discharge mechanism that discharges the recording medium while placing the first surface or the second surface on which the image has been recorded last on a gravitationally lower side,
wherein the aqueous ink has a first viscosity η 1 (mPa·s) of 5.0 mPa·s or more and an evaporated ink, which is obtained by evaporating 20% by mass of the aqueous ink, has a second viscosity η 2 (mPa·s), with a difference η 2 −η 1 (mPa·s) being 4.0 mPa·s or more.