1. A printing apparatus comprising:
first nozzles which discharge a dye ink;
second nozzles which discharge a pigment ink with the same color as the dye ink; and
a controller which controls the discharge of the inks from the first nozzles and the second nozzles,
wherein the controller executes a first discharging operation for discharging the dye ink from the first nozzles and then discharging the pigment ink from the second nozzles at predetermined positions on a medium and executes a second discharging operation for discharging the pigment ink from the second nozzles and then discharging the dye ink from the first nozzles at positions different from the predetermined positions on the medium, and
wherein a ratio of the dye ink to the pigment ink in the amount of ink discharged in the second discharging operation per unit area is less than a ratio of the dye ink to the pigment ink in the amount of ink discharged in the first discharging operation per unit area.
2. The printing apparatus according to claim 1, wherein the ratio of the dye ink to the pigment ink in the amount of ink discharged in the second discharging operation per unit area is set to be less than the ratio of the dye ink to the pigment ink in the amount of ink discharged in the first discharging operation per unit area, by decreasing the amount of dye ink discharged in the second discharging operation.
3. The printing apparatus according to claim 1, wherein the dye ink and the pigment ink are black.
4. The printing apparatus according to claim 1, further comprising:
a transport mechanism which transports the medium in a transport direction;
a head in which the first nozzles and the second nozzles are arranged side by side in a direction crossing the transport direction; and
a head movement mechanism which moves the head in both directions along the crossing direction,
wherein the first discharging operation is executed in movement of the head in one direction of both directions and the second discharging operation is executed in movement of the head in the other direction of both directions.
5. The printing apparatus according to claim 1, wherein:
the head includes a first nozzle array including the plurality of first nozzles arranged with a predetermined pitch along the transport direction and a second nozzle array including the plurality of second nozzles arranged with the predetermined pitch along the transport direction, and
the nozzles of the first nozzle array are arranged at positions shifted from the nozzles of the second nozzle array by a half of the predetermined pitch in the transport direction.
6. The printing apparatus according to claim 1, further comprising:
a transport mechanism which transports the medium in a transport direction;
a head in which the first nozzles and the second nozzles are arranged side by side in a direction crossing the transport direction; and
a head movement mechanism which moves the head in both directions along the crossing direction,
wherein the head includes a first nozzle array including the plurality of first nozzles arranged with a predetermined pitch along the transport direction and a second nozzle array including the plurality of second nozzles arranged with the predetermined pitch along the transport direction,
wherein the nozzles of the first nozzle array are arranged at positions shifted from the nozzles of the second nozzle array by a half of the predetermined pitch in the transport direction,
wherein the first discharging operation is executed in movement of the head in one direction of both directions and the second discharging operation is executed in movement of the head in the other direction of both directions,
wherein the ratio of the dye ink to the pigment ink in the amount of ink discharged in the second discharging operation per unit area is set to be less than the ratio of the dye ink to the pigment ink in the amount of ink discharged in the first discharging operation per unit area, by decreasing the amount of dye ink discharged in the second discharging operation, and
wherein the dye ink and the pigment ink are black.
7. A method of controlling a printing apparatus including first nozzles which discharge a dye ink, second nozzles which discharge a pigment ink of the same color as the dye ink, and a controller which controls the discharge of the inks from the first nozzles and the second nozzles, the method comprising:
executing a first discharging operation for discharging the dye ink from the first nozzles and then discharging the pigment ink from the second nozzles at predetermined positions on a medium, and
executing a second discharging operation for discharging the pigment ink from the second nozzles and then discharging the dye ink from the first nozzles at positions different from the predetermined positions on the medium, such that a ratio of the dye ink to the pigment ink in the amount of ink discharged in the second discharging operation per unit area is less than a ratio of the dye ink to the pigment ink in the amount of ink discharged in the first discharging operation per unit area.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A process for preparing a polycarbonate polyol, comprising polymerizing cyclic carbonate in the presence of DMC catalyst and chain-transfer agent, wherein the chain-transfer agent consists of polyether carbonate polyol and is prepared beforehand in a separate reaction step.
2. The process according to claim 1, wherein the cyclic carbonate is at least one compound selected from the group consisting of compounds of formulae (I) and (II)
wherein
R1, R4 and R5 independently of one another represent hydrogen or a linear or branched C1 to C12 alkyl radical or a C6 to C10 aryl radical, and
R2 and R3 independently of one another represent hydrogen or a linear or branched C1 to C12 alkyl radical or a C6 to C10 aryl radical or an allyloxymethyl radical.
3. The process according to claim 1, wherein the cyclic carbonate is at least one selected from the group consisting of trimethylene carbonate, neopentyl glycol carbonate, 2,2,4-trimethyl-1,3-pentanediol carbonate, 2,2-dimethyl-1,3-butanediol carbonate, 1,3-butanediol carbonate, 2-methyl-1,3-propanediol carbonate, 2,4-pentanediol carbonate, 2-methyl-butane-1,3-diol carbonate, TMP-monoallyl ether carbonate, pentaerythritol diallyl ether carbonate, propylene carbonate, phenylethylene carbonate and ethylene carbonate.
4. The process according to claim 1, wherein the DMC catalyst comprises zinc hexacyanocobaltate(III) which comprises as organic complex ligands tert-butanol and a polyether polyol having a number-average molecular weight of at least 500 gmol.
5. The process according to claim 1, wherein trimethylene carbonate is used as the cyclic carbonate.
6. The process according to claim 1, wherein polymerisation of the cyclic carbonate takes place in the presence of DMC catalyst and at least one chain-transfer agent at a reaction temperature of from 60 to 160\xb0 C.
7. The process according to claim 1, wherein the weight ratio of chain-transfer agent to cyclic carbonate is from 1:0.001 to 1:50.
8. The process according to claim 1, wherein
(i) H-functional starter substance, or a mixture of at least two H-functional starter substances, is placed in a reaction vessel, and water andor other readily volatile compounds are optionally removed by drying, wherein the DMC catalyst, the H-functional starter substance, or the mixture of at least two H-functional starter substances, are added before andor after the drying,
(ii) an alkylene oxide and carbon dioxide are added to the mixture resulting from (i) thereby comprising copolymerisation with formation of the polyether carbonate polyol chain-transfer agent,
(iii) to the mixture resulting from (ii), there is added a cyclic carbonate, which can be the same as or different from the cyclic carbonate contained in the mixture resulting from (ii), wherein the weight ratio of mixture resulting from (ii) to added cyclic carbonate is from 1:0.001 to 1:50, and a resulting mixture is reacted at a temperature of from 60 to 160\xb0 C.
9. The process according to claim 8, wherein no DMC catalyst is added in (iii).
10. The process according to claim 1, wherein there is used as the chain-transfer agent a polycarbonate which has been prepared by said process.
11. An aliphatic polycarbonate obtainable by a process according to claim 1.
12. The process according to claim 1, wherein the polycarbonate polyol has a content of primary OH groups of at least 80%.
13. The process according to claim 1, wherein the chain-transfer agent consists of a mixture of different polyether carbonate polyols.
14. The process according to claim 1, further comprising reacting the polycarbonate polyol with a diisocyanate andor polyisocyanate to form a polyurethane.