Compositions: coating or plastic – Coating or plastic compositions – Marking
Reexamination Certificate
2002-04-04
2004-06-15
Bell, Mark L. (Department: 1755)
Compositions: coating or plastic
Coating or plastic compositions
Marking
C106S031590, C106S031860, C106S031890
Reexamination Certificate
active
06749675
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to aqueous ink compositions, particularly to quick-drying type aqueous ink compositions suitable for ink jet printing method.
BACKGROUND OF THE INVENTION
It has bee the common practice to add, to aqueous ink compositions, a surface active substance in order to (a) improve print quality (including adaptability to paper), (b) improve quick drying property and (c) prevent bleeding between adjacent colors upon multi-color printing.
Since a surface active substance to be added to aqueous ink compositions is required to have high penetration promoting effects into a recording medium and structural characteristic that does not cause defects such as bubbling during printing, a nonionic surfactant is often selected as the surface active substance. Particularly, surfactants such as acetylene alcohol compounds and acetylene glycol compounds have attracted attentions as surfactants capable of satisfying the above-described requirements. Among them, acetylene alcohol compounds have markedly high penetration promoting effects and they are known to provide excellent print quality even with a small addition amount (for example, Japanese Patent Laid-Open No. 139964/1988, Japanese Patent Laid-Open No. 239068/1992).
Acetylene alcohol compound based surfactants having a structure exhibiting stronger hydrophobicity are preferred because of their higher penetration promoting effects. They, however, have low solubility in water so that there may be the case where attention should be given to ejection property and clogging property.
SUMMARY OF THE INVENTION
The present invention has been made in view of the above-described problems, and an object of the present invention is to provide an aqueous ink composition excellent in (a) improvement of ejection stability, (b) improvement of print quality, (c) improvement in fixing property (scratch resistance), (d) reduction in running cost, and (e) improvement of adaptability to paper.
Another object of the present invention is to provide an ink cartridge having the aqueous ink composition contained therein.
Other objects and effects of the invention will become apparent from the following description.
The present inventors have investigated and studied improvement in solubility in water of an acetylene alcohol compound based surfactant of a strong hydrophobic structure (which may be hereinafter referred simply to “hydrophobic”). As a result, it was found that combined use, in an aqueous ink composition, of a specific acetylene alcohol based surfactant and a surface active substance capable of causing an effective amount of the acetylene alcohol based surfactant to dissolve in water makes it possible: to improve water solubility of the acetylene alcohol based surfactant, leading to improvement in ejection stability and clogging resistance without causing defects such as bubbling; to increase the addition amount of the acetylene alcohol based surfactant, so that improvement in print quality, improvement in adaptability to paper and reduction of a running cost can be attempted; and to improve penetration, thereby improving fixing property (scratch resistance) particularly when a pigment is used as a colorant. The invention has been completed based on the above-described findings.
The above-described objects of the invention have been achieved by providing an aqueous ink composition comprising at least: a colorant; water; 0.005 to 10 wt. %, based on the weight of the ink composition, of an acetylene alcohol compound represented by the following formula (1):
wherein R
1
, R
2
and R
3
each independently represents a hydrogen atom, an alkyl group which may be branched, or an alkylphenyl group; and a surface active substance capable of causing the acetylene alcohol compound of formula (1) to dissolve in water.
1) In a first preferred embodiment of the invention, the surface active substance comprises at least one compound selected from compounds represented by the following formulas (21a), (21b), (21c), (21d), (21e) and (21f):
wherein R
11
to R
15
each independently represents a C
1-15
alkyl group which may be branched, subscripts n1, m1, h1, k1, j1, a, b and c each independently stands for 1 to 30, and M
1
and M
2
each independently represents a hydrogen atom, an alkali metal or a base such as ammonium.
2) In a second preferred embodiment of the invention the surface active substance comprises at least one 1,2-alkyldiol compound represented by the following formula (22):
HO—CH
2
—CH(OH)—R
21
(22)
wherein R
21
represents a C
1-10
alkyl group.
3) In a third preferred embodiment of the invention, the surface active substance comprises at least one compound selected from the compounds represented by the following formulas (23a) and (23b):
wherein R
31
represents a C
1-15
alkyl group which may be branched, or an alkylphenyl group, and subscripts n3 and m3 each independently stands for 0 to 10.
4) In a fourth preferred embodiment of the invention, the surface active substance comprises at least one compound selected from phosphate ester compounds represented by the following formulas (24a) and (24b):
wherein R
44
, R
45
, and R
46
each independently represents a C
8-30
alkyl group which may be branched, or an alkylphenyl group, and subscripts n4, m41 and m42 each independently stands for 1 to 30.
5) In a fifth preferred embodiment of the invention, the surface active substance comprises at least one compound selected from:
highly water-soluble acetylene glycol compounds represented by the following formula (25a):
wherein R
54
, R
55
, R
56
and R
57
each independently represents a C
1-30
alkyl group which may be branched, or an alkylphenyl group, R
51
and R
52
each independently represents a hydrogen atom or a methyl group, and subscripts n5 and m5 each stands for an integer of 0 to 30; and
highly water-soluble acetylene alcohol compounds represented by the following formula (25b):
wherein R
58
, R
59
and R
50
each independently represents a hydrogen atom or an alkyl group which may be branched, R
53
represents a hydrogen atom or a methyl group, and a subscript h5 stands for an integer of 0 to 30, with the proviso that R
58
+R
59
+R
50
<5.
The present invention also relates to an ink cartridge having an ink container containing any one of the above-described aqueous ink compositions.
DETAILED DESCRIPTION OF THE INVENTION
Components used for the aqueous ink composition of the invention are described in detail below. The term “aqueous ink composition” as used herein means, for black-and-white recording, an aqueous black ink composition, while for color printing, it means a color ink composition, more specifically, an aqueous yellow ink composition, an aqueous magenta ink composition and an aqueous cyan ink composition, and further optionally, an aqueous black ink composition.
To the aqueous ink composition of the invention, a water soluble compound can be further added in order to improve recording stability such as writing properties and ejection properties. Addition of a proper water-soluble compound may impart writing things such as pen with smooth writing properties free of partial thinning and inkjet recording with more stable ejection properties. As such a water soluble compound, organic solvents and water soluble solids ordinarily employed for aqueous ink compositions can be used. Specific examples thereof include low-molecular-weight glycols such as ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol and dipropylene glycol; polyols such as 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,2,6-hexanetriol, pentaerythritol and glycerin; lower alcohols such as ethanol and propanol; cellosolves such as ethylene glycol monomethyl ether and ethylene glycol monoethyl ether; carbitols such as diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, and diethylene glycol monobutyl ether; lactams such as 2-pyrrolidone, N-methyl-2-pyrrolidone and &egr;-caprolactam; ureas such as urea, thiourea,
Bell Mark L.
Faison Veronica F.
Ladas & Parry
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