Ink composition for inkjet recording and inkjet recording process

Claim 2

An ink composition for use in an on-demand inkjet printer capable of printing on plain paper at a recording rate of 10 ips or higher, which ink composition comprises at least a pigment and non-pigment components including at least water and a thickening agent and shows a weight loss ratio at 25° C. and 60 RH (relative humidity) % for 30 minutes of 5 to 25% based on the total weight of the ink.

Claim 3

The ink composition as claimed in claim 1 , wherein said non-pigment components comprises: at least one of 7.5 to 40% by weight of a polyethylene glycol having an average molecular weight of 600 to 6,000 and 1 to 10% by weight of a polyethylene glycol having an average molecular weight of 20,000 to 70,000 as a thickening agent; 0 to 30% by weight of at least one of an ethylene glycol ether and a propylene glycol ether; and 0 to 30% by weight of glycerin.

Claim 4

The ink composition as claimed in claim 1 , having a viscosity at 25° C. of 5 to 15 mPa·s and a surface tension of 30 to 55 mN/m.

Claim 5

An on-demand inkjet recording process comprising: recording an image on plain paper by ejecting an ink composition at a recording rate of 10 ips or higher, wherein said ink composition is as claimed in claim 1 .

Claim 6

The process as claimed in claim 4 , wherein said non-pigment components, comprise: at least one of 7.5 to 40% by weight of a polyethylene glycol having an average molecular weight of 600 to 6,000 and 1 to 10% by weight of a polyethylene glycol having an average molecular weight of 20,000 to 70,000 as a thickening agent; 0 to 30% by weight of at least one of an ethylene glycol ether and a propylene glycol ether; and 0 to 30% by weight of glycerin.

Claim 7

The process as claimed in claim 4 , wherein said ink composition has a viscosity at 25° C. of 5 to 15 mPa·s and a surface tension of 30 to 55 mN/m.

Claim 8

The process as claimed in claim 4 , wherein said plain paper has a Stöckigt sizing degree of 55 or less.

Claim 9

An ink composition for use in an on-demand inkjet printer capable of printing on plain paper at a recording rate of 10 ips or higher, said ink composition, comprising: at least a pigment and non-pigment components, said non-pigment components including at least water and a thickening agent, wherein said ink composition shows a weight loss ratio, based on a total initial weight of said ink composition, of 5 to 25%, for 30 minutes at 25° C. and 60% RH (relative humidity) and, wherein said non-pigment components comprise: at least one of 7.5 to 40% by weight of a polyethylene glycol having an average molecular weight of 600 to 6,000 and 1 to 10% by weight of a polyethylene glycol having an average molecular weight of 20,000 to 70,000 as a thickening agent; 0 to 30% by weight of at least one of an ethylene glycol ether and a propylene glycol ether; and 0 to 30% by weight of glycerin.

Claim 10

An ink composition for use in an on-demand inkjet printer capable of printing on plain paper at a recording rate of 10 ips or higher, said ink composition, comprising: at least a pigment and non-pigment components, said non-pigment components including at least water and a thickening agent, wherein said ink composition shows a weight loss ratio, based on a total initial weight of said ink composition, of 5 to 25%, for 30 minutes at 25° C. and 60% RH (relative humidity) and, wherein said non-pigment components comprise: at least one of 7.5 to 40% by weight of a polyethylene glycol having an average molecular weight of 600 to 6,000 and 1 to 10% by weight of a polyethylene glycol having an average molecular weight of 20,000 to 70,000 as a thickening agent; 0 to 30% by weight of at least one of an ethylene glycol ether and a propylene glycol ether; and 0 to 30% by weight of glycerin.

Claim 11

The ink composition as claimed in claim 8 , having a viscosity of 5 to 15 mPa·s and a surface tension of 30 to 55 mN/m at 25° C.

Claim 12

An on-demand inkjet recording process comprising: recording an image on plain paper by ejecting an ink composition at a recording rate of 10 ips or higher, wherein said ink composition is as claimed in claim 1 , and wherein said non-pigment components, comprise: at least one of 7.5 to 40% by weight of a polyethylene glycol having an average molecular weight of 600 to 6,000 and 1 to 10% by weight of a polyethylene glycol having an average molecular weight of 20,000 to 70,000 as a thickening agent; 0 to 30% by weight of at least one of an ethylene glycol ether and a propylene glycol ether; and 0 to 30% by weight of glycerin.

Claim 13

The process as claimed in claim 10 , wherein said ink composition has a viscosity of 5 to 15 mPa·s and a surface tension of 30 to 55 mN/m at 25° C.

Claim 14

The process as claimed in claim 10 , wherein said plain paper has a Stöckigt sizing degree of 55 or less.

Claim 15

The ink composition as claimed in claim 1 , wherein said non-pigment components include at least one of 7.5 to 40% by weight of a polyethylene glycol having an average molecular weight of 600 to 6,000 and 1 to 10% by weight of a polyethylene glycol having an average molecular weight of 20,000 to 70,000 as a thickening agent.

Claim 16

The ink composition as claimed in claim 1 , wherein said non-pigment components include 0 to 30% by weight of at least one of an ethylene glycol ether and a propylene glycol ether.

Claim 17

The ink composition as claimed in claim 1 , wherein said non-pigment components include 0 to 30% by weight of glycerin.

Claim 18

The process as claimed in claim 4 , wherein said non-pigment components include at least one of 7.5 to 40% by weight of a polyethylene glycol having an average molecular weight of 600 to 6,000 and 1 to 10% by weight of a polyethylene glycol having an average molecular weight of 20,000 to 70,000 as a thickening agent.

Claim 19

The process as claimed in claim 4 , wherein said non-pigment components include 0 to 30% by weight of at least one of an ethylene glycol ether and a propylene glycol ether.

Claim 20

The process as claimed in claim 4 , wherein said non-pigment components include 0 to 30% by weight of glycerin.