Note: Descriptions are shown in the official language in which they were submitted.
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SPECIFICATION
TITLE OF THE INVENTION
Aqueous Pigment Ink Composition for Ball-point
Pens
BACKGROUND OF THE INVENTION
(i) Field of the Invention
The present invention relates to an aqueous
pigment ink composition. Particularly, it relates to an
aqueous pigment ink composition suitable for ball-point
pens.
(ii) Description of the Related Art
In a conventional aqueous pigment ink for a ball-
point pen, a pigment is dispersed as a coloring agent,
and water or a water-soluble solvent such as glycol or
glycerin is used as a solvent which is the main component
for inhibiting the ink from drying (non drying
properties) at the tip of the ball-point pen. However,
such a conventional ink is poor in lubricating
properties, so that frictional resistance between a ball
and a ball seat is large when the ball is rotated at the
time of writing, and thus, there are the following
drawbacks. That is, the ball seat is worn and the ball
retracts, and the ball is loose or the flow of the ink is
ununiformed, with the results that a writing performance
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noticeably declines. For the purpose of removing these
drawbacks, it has been attempted to add a lubricating
improver such as an unsaturated fatty acid or potassium
oleate.
On the other hand, Japanese Patent Application
Laid-open No. 63-234073 discloses an ink for a ball-point
pen containing a dye and an adduct of polyglycerin with
ethylene oxide, and Japanese Patent Application Laid-open
No. 55-106273 discloses an aqueous ink composition for a
ball-point pen containing a dye, an adduct of sorbitol or
glycerin with polyoxyalkylene and a fluorine surface
active agent. In both the publications, it is described
that these inks for the ball-point pens are excellent in
lubricating properties and have a smooth writing
performance. However, when the dye is used together with
the adduct of the alkylene oxide, the lubricating
properties are excellent but there is a drawback that the
ink tends to blur. Furthermore, Japanese Published
Patent Application No. 62-10547 discloses a recording
liquid suitable for an ink jet recording system
containing an adduct of glycerin with alkylene oxide.
However, when the recording liquid is used for the ball-
point pen, there are drawbacks that the lubricating
properties are not always satisfactory and that the
dispersion of a pigment is not good.
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.
SUMMARY OF THE INVENTION
In the case of the above-mentioned conventional
methods, sufficient lubricating properties cannot be
obtained, and a writing impossible phenomenon takes place
owing to the wear of a ball seat. In addition, some
practical problems are also perceived. That is, even if
the enough lubricating properties can be obtained, the
surface tension of an ink noticeably deteriorates, and so
the written letters easily blur.
An object of the present invention is to provide
an aqueous pigment ink for ball-point pens which can
inhibit surface tension from extremely deteriorating to
protect written letters from blur and which is excellent
in non-drying properties and which has lubricating
properties enough to smoothly rotate a ball and to
decrease friction on a ball seat, whereby a writing
performance can be remarkably improved and a comfortable
writing performance can be given.
The present inventors have intensively researched
to solve the above-mentioned problems, and as a result,
they have found that when an adduct of a specific
polyhydric alcohol with an alkylene oxide is added to a
pigment ink composition, the above-mentioned object can
be accomplished. Thus, the present invention has been
completed on the basis of this knowledge.
~ 4 ~ 2 07573U
An aqueous pigment ink composition for ball-point
pens of the present invention is characterized by
comprising a pigment, a dispersant, water and at least
one adduct of one polyhydric alcohol with an alkylene
oxide selected from the group consisting of an adduct o
polyglycerin with an alkylene oxide, an adduct of
glycerin with an alkylene oxide in which 1 to 150 mols of
the alkylene oxide are added to 1 mol of glycerin, an
adduct of trimethylolpropane with an alkylene oxide, and
a mixture thereof.
The amount of the adduct of polyhydric alcohol with
the alkylene oxide is in the range of 0.5 to 40~ by
weight with respect to the total weight of the
composition.
The first aqueous pigment ink composition for
ball-point pens of the present invention is characterized
by comprising a pigment, a dispersant, water and an
adduct of polyglycerin with an alkylene oxide.
The preferable example of this ink composition is
an aqueous pigment ink composition which comprises 0.5 to
40% by weight of an adduct of polyglycerin with an
alkylene oxide in which 1 to 60 mols of the alkylene
oxide are added to 1 mol of polyglycerin having a degree
of polymerization of 2~4, 2 to 30% by weight of a
pigment, 0.1 to 10~ by weight of a dispersant, and 40 to
90% by weight of water with respect to the total weight
of the composition.
The second aqueous pigment ink composition for
ball-point pens of the present invention is characterized
~, . ,
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by comprising a pigment, a dispersant, water and an
adduct of glycerin with an alkylene oxide in which 1 to
150 mols of the alkylene oxide are added to 1 mol of
glycerin.
The preferable example of this ink composition is
an aqueous pigment ink composition which comprises 0.5 to
40% by weight of an adduct of glycerin with an alkylene
oxide, 2 to 30% by weight of a pigment, 0.1 to 10% by
weight of a dispersant, and 40 to 90% by weight of water
with respect to the total weight of the composition.
The third aqueous pigment ink for ball-point pens
of the present invention is characterized by adding an
adduct of trimethylolpropane with an alkylene oxide to an
aqueous pigment ink mainly comprising a pigment, a
dispersant, a water-soluble solvent and water.
The preferable example of this ink composition is
an aqueous pigment ink composition which comprises 0.5 to
40% by weight of an adduct of trimethylolpropane with an
alkylene oxide in which 1 to 60 mols of the alkylene
oxide are added to trimethylolpropane, 2 to 30% by weight
of a pigment, 0.1 to 10% by weight of a dispersant, and
40 to 90% by weight of water with respect to the total
weight of the composition.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
An adduct of polyglycerin with an alkylene oxide
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which is used in a composition of the present invention
is an adduct in which 1 to 60 mols of an alkylene oxide
are added to polyglycerin having the degree of
polymerization of 2~4, such as diglycerin and
triglycerin. For example, such an adduct can be obtained
by adding 1 to 60 mols of ethylene oxide, propylene oxide
or a mixture thereof to a polymer containing 1 mol of
polyglycerin having the degree of polymerization of 2~4,
and the content of the adduct of the polyglycerin with
the alkylene oxide is preferably from 0.5 to 40% by
weight, more preferably from 1 to 30% by weight based on
the total weight of the composition. When the content of
the adduct is less than 0.5% by weight, sufficient
lubricating properties cannot be obtained and so the
improvement of a writing performance cannot be expected.
Conversely, when it is more than 40% by weight, the
viscosity of the ink increases and the flow of the ink is
poor and improper.
The adduct of glycerin with the alkylene oxide
which is used in the ink composition of the present
invention is an adduct in which 1 to 150 mols of the
alkylene oxide are added to glycerin. For example, such
an adduct can be obtained by adding 1 to 150 mols of
ethylene oxide, propylene oxide or a mixture thereof to
glycerin. The content of the adduct of glycerin with the
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alkylene oxide is preferably from 0.5 to 40~ by weight,
more preferably from 1 to 30~ by weight based on the
weight of the composition.
When the content of the adduct is less than 0.5%
by weight, sufficient lubricating properties cannot be
obtained and so the improvement effect of a writing
performance cannot be expected. Conversely, when it is
more than 40~ by weight, the viscosity of the ink
increases and the flow of the ink is poor and improper.
The adduct of trimethylolpropane with the alkylene
oxide which is used in the ink composition of the present
invention is an adduct in which 1 to 60 mols of the
alkylene oxide are added to trimethylolpropane. For
example, such an adduct can be obtained by adding 1 to 60
mols of ethylene oxide, propylene oxide or a mixture
thereof to trimethylolpropane. The content of the adduct
of trimethylolpropane with the alkylene oxide is
preferably from 0.5 to 40~ by weight, more preferably
from 1 to 30% by weight based on the weight of the
composition.
When the content of the adduct is less than 0.5
by weight, sufficient lubricating properties and the
improvement effect of a writing performance cannot be
expected. Conversely, when it is more than 40~ by
weight, the viscosity of the ink increases and the flow
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of the ink is poor and improper.
The adduct of the specific polyhydric alcohol with
the alkylene oxide in the ink composition of the present
invention is prepared from alkylene oxide and the
specific polyhydric alcohol in an alkali-catalyzed
reaction in the presence of excess alkylene oxide.
This reaction proceeds such that firstly the
alkylene oxide reacts with the specific polyhydric
alcohol and then further polymerization of alkylene oxide
proceeds.
That is, in a pressure vessel, the inner
atmosphere of which is previously replaced with nitrogen,
is placed the specific polyhydric alcohol and alkali and
then the alkylene oxide is added thereto dropwise at a
pressure of about 10 kg/cm2 and a temperature of
100~140C.
In the ink composition of the present invention,
the adduct of the specific polyhydric alcohol with the
alkylene oxide may be mixed with a water-soluble organic
solvent. Examples of this solvent include water-soluble
polyhydric alcohols such as ethylene glycol, propylene
glycol, diethylene glycol and glycerin; cellosolves*such
as ethylene glycol monomethyl ether (methyl cellosolve)
and ethylene glycol monoethyl ether (ethyl cellosolve);
carbitols*such as diethylene glycol monomethyl ether
*trade-marks
9 20 75 730
(methyl carbitol) and diethylene glycol monoethyl ether
(ethyl carbitol); and glycol ether esters such as
ethylene glycol monoethyl ether acetate. These compounds
can improve the non-drying properties.
The amount of the solvent to be blended is usually
40~ by weight or less, preferably from 5 to 40~ by weight
based on the total weight of the composition.
No particular restriction is put on the kind of
pigment which can be used in the ink composition of the
present invention, and optional inorganic and organic
pigments can be used which have been conventionally
employed in the aqueous pigment ink composition.
Examples of this inorganic pigment include titanium
oxide, carbon black and metal powders; and examples of
the above-mentioned organic pigment include azo lakes,
insoluble azo pigments, chelate azo pigments,
phthalocyanine pigments, perylenes, perylene pigments,
anthraquinone pigments, quinacridone pigments, dye lakes,
nitro pigments and nitroso pigments.
Typical usable examples of the pigment include
Phthalocyanine Blue (C.I. 74260), Phthalocyanine Green
(C.I. 74260), Hansa Yellow 3G (C.I. 11670), Disazo Yellow
GR (C.I. 21100), Permanent Red 4R (C.I. 12335), Brilliant
Carmine 6B (C.I. 15850) and Quinacridone Red (C.I.
46500).
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These pigments may be used singly or in a
combination of two or more, and the amount of the pigment
to be used is usually from 2 to 30% by weight, preferably
from 5 to 15% by weight based on the total weight of the
composition.
The dispersant in the composition of the present
invention adheres to the surfaces of pigment particles
and permits the pigment to be dispersed in water. Exam-
ples of the usable dispersant include nonionic and anion-
ic surface active agents and water-soluble polymers, and
the latter water-soluble polymers are preferably used.
Examples of the nonionic surface active agents include
polyoxyalkylene higher fatty esters, higher fatty acid
partial esters of polyhydric alcohols and higher fatty
esters of saccharide.
Typical examples of the nonionic surface active
agents include fatty esters of glycerin, polyglycerin
fatty esters, propylene glycol fatty esters,
pentaerythritol fatty esters, polyoxyethylene sorbitan
fatty acid esters, polyoxyethylene sorbit fatty esters,
polyoxyethylene glycerin fatty esters, polyethylene
glycol fatty esters, polyoxyethylene alkylene ethers,
polyoxyethylene phytosterols, polyoxyethylene
polyoxypropylenealkyl ethers, polyoxyethylenealkylphenyl
ethers, polyoxyethylenecastor oil,
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11
polyoxyethylenelanolin, polyoxyethylenelanolin alcohol,
polyoxyethylenealkylamine, polyoxyethylene fatty acid
amides and polyoxyethylenealkylphenyl formaldehyde
condensates.
Examples of the anionic surface active agent
include alkylated sulfonates of higher fatty acid amides
and alkylallyl sulfonates, and typical examples thereof
include alkyl sulfates, polyoxyethylene alkyl ether
sulfates, salts of N-acyl amino acid, salts of N-acyl-
methyltaurine, polyoxyethylene alkyl ether acetates,
alkyl phosphates and polyoxyethylene alkyl ether
phosphates.
Examples of the water-soluble polymers include
polyacrylic acid, acrylic copolymers and maleic resins.
Typical examples of the water-soluble polymers
include water-soluble salts of resins such as an acrylic
resin, a styrene-acrylic resin and a styrene-maleic
resin. Typical examples of alkaline metals for the
formation of the salts are sodium and potassium. Exam-
ples of the amine include aliphatic primary, secondary
and tertiary amines such as mono-, di- and trimethylamin-
es; alcoholamines such as mono-, di- and tripropanolamin-
es, methyl ethanolamine, methyl propanolamine and dimeth-
yl ethanolamine; ammonia, morpholine and N-methylpholine.
The amount of the dispersant to be blended is from
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0.1 to 10% by weight based on the weight of the
composition.
No particular restriction is put on the amount of
water which is used in the composition of the present
invention, but it is suitably from 40 to 90% by weight
based on the weight of the composition.
In addition, if necessary, there may be blended a
lubricant such as potassium linoleate or sodium ricinole-
ate, potassium oleate or sodium oleate; an antiseptic
agent such as phenol or sodium benzoate; a rust preven-
tive such as benzotriazole, dicyclohexyl ammonium nitrite
or diisopropyl ammonium nitrite; and a pH adjustor such
as triethanolamine, monoethanolamine, diethanolamine or
ammonia.
The ink composition of the present invention is
excellent in lubricating properties and can improve a
writing performance. Its functional mechanism is not
clearly definite but can be presumed as follows: The
oxygen atoms in the hydroxyl group and the ether bond
portion in the structure of the adduct of the specific
polyhydric alcohol with the alkylene oxide used in the
present invention adhere to the surface of the metal, and
hydrocarbon chains are arranged on the side opposite to
the metal surface. Then, the adduct itself of the
specific polyhydric alcohol with the alkyleneoxide is
- 20~5~3
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viscous, and so a lubricating film is formed between a
ball and a ball seat, whereby the lubricating properties
are given.
It can be also supposed that the ink composition
of the present invention provides the good lubricating
properties with less blur owing to the suitable viscosity
of glycerin or the polymeric chain of ethylene oxide in
the adduct of the specific polyhydric alcohol with the
alkylene oxide and owing to the function of the
dispersant.
Additionally, in the ink in which the adduct of
the specific polyhydric alcohol with the alkylene oxide
is used, the dye easily blurs but the pigment scarcely
blurs, and this reason is not apparent but can be pre-
sumed to be due to different solubilities of the dye and
the pigment in the solvent.
The aqueous pigment ink composition for ball-point
pens of the present invention, when used in a ball-point
pen, scarcely blurs and gives good lubricating
properties, so that the friction on a ball seat
attributable to the rotation of a ball is controlled.
Thus, the proper flow of the ink can be maintained and
smooth writing feeling can be given.
Furthermore, the ink is inhibited from drying at
the tip of the ball-point pen, and so the effect of less
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scratch can be exerted.
Moreover, when the aqueous pigment ink composition
of the present invention is used, the drying up of the
ink at a pen tip and an orifice tip can be inhibited, and
clogging can be prevented and the blur of written letters
can be also controlled. In consequence, the aqueous
pigment ink composition of the present invention is also
very desirable as an ink for ink jet.
EXAMPLES
Now, the present invention will be described in
more detail in reference to examples, but the present
invention should not be limited to these examples.
Inks of Examples 1 to 6 and Comparative Examples 1
to 6 were obtained by stirring and mixing components in a
stirring machine for 3 hours, dispersing the mixture by a
sand mill for 5 hours, and then removing coarse particles
therefrom by a centrifugal separator.
Dye inks of Comparative Examples 7 and 8 were
obtained by stirring components at a temperature of 40 to
60'C for 1 hour, cooling and then filtering the mixture.
The inks obtained in the examples and comparative
examples were evaluated by the following writing test.
The results are set forth in Table 1.
In the writing test, the measurement of a ball
dent as well as the evaluation of a writing performance
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and the blur state of the written letters were carried
out as follows.
Ball Dent:
After writing was made as much as 500 m under
conditions of a writing angle of 60, a writing rate of
5.5 m/minute and a load of 100 g by a helical writing
tester, the deep of the worn portion of a ball seat,
i.e., the decreased length of the ball projecting from a
holder was measured.
Writing performance:
o: Smooth and stable writing performance
~: Scraggy and hard writing performance
x: Scraggy and hard writing performance, and
presence of line cut and directional
property
Blur of written letters:
o: Clear written letters without blur
~: Unclear written letters with blur
x: Very unclear written letters with noticeable
blur
Example 1
A black aqueous pigment ink for ball-point pens
was prepared from the following components.
Carbon black MA 100 8.0 wt~
[particle size 22 mu, oil absorption
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100 ml/lOOg (DBP), specific surface
area 134 m /g (BET), made by
Mitsubishi Kasei Co., Ltd.]
Ethylene glycol 10.0 wt~
Adduct of 1 mol of diglycerin with
30 mols of ethylene oxide
(viscosity 348 cps, hydroxyl
value 15 mgKOH/g) 5.0 wt%
Ammonium salt of styrene acrylic
acid resin 3.0 wt%Potassium linoleate 0.3 wt%
Triethanolamine 0.5 wt%
Phenol O.1 wt%
Benzotriazole O.1 wt%
Purified water 73.0 wt%
Total 100.0 wt%
Above-mentioned Ammonium salt was prepared by
neutralizing Styrene-Acrylic acid Copolymer having
weight-average molecular weight of 10000, acid value of
195, softening point of 143C, and glass transition point
of 70C, with ammonia.
Example 2
A blue aqueous pigment ink for ball-point pens was
prepared from the following components.
Phthalocyanine blue 8.0 wt%
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(Chromofine blue*4965, made by
Dainichiseika Co., Ltd.)
Glycerin 5.0 wt%
Adduct of 1 mol of triglycerin
with 20 mols of propylene oxide10.0 wt%
Ammonium salt of styrene maleate resin 3.0 wt%
Sodium ricinoleate 0.3 wt%
Triethanolamine 0.5 wt%
Phenol 0.1 wt%
Benzotriazole 0.1 wt%
Purified water 73.0 wt%
Total 100.0 wt%
Comparative Example 1
The same procedure as in Example 1 was repeated
except that 5.0 wt% of an adduct of diglycerin with 30
mols of ethylene oxide and 10.0 wt% of ethylene glycol
were replaced with 15% of ethylene glycol, to obtain a
black aqueous pigment ink.
Comparative Example 2
The same procedure as in Example 2 was repeated
except that 10.0% of an adduct of 1 mol of triglycerin
with 20 mols of propylene oxide and 5.0% of glycerin
were replaced with 15% of glycerin and that 0.5% of
sodium ricinoleate and 72.8% of purified water were used,
to obtain a blue aqueous pigment ink.
Example 3
A blue aqueous pigment ink for ball-point pens was
*trade-mark
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obtained by the use of the following components. The
results of a writing test are set forth in Table 1.
Phthalocyanine blue 7.0 wt%
(Chromofine blue 4965, made by
Dainichiseika Co., Ltd.)
Ethylene glycol 17.0 wt%
Adduct of 1 mol of glycerin with 40 mols
of ethylene oxide 3.0 wt%
Ammonium salt of styrene acrylate resin
(used in Example 1) 3.0 wt%
Patasium linoleate 0.3 wt%
Triethanolamine 0.5 wt%
Phenol 0.1 wt%
Benzotriazole 0.1 wt%
Purified water 69.0 wt%
Total 100.0 wt%
Example 4
A black aqueous pigment ink for ball-point pens
was obtained by the use of the following components. The
results of a writing test are set forth in Table 1.
Carbon black MA 100 8.0 wt%
(made by Mitsubishi Kasei Co., Ltd.)
Glycerin 5.0 wt%
Adduct of 1 mol of glycerin with 10 mols
of propylene oxide 5.0 wt%
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Ammonium salt of styrene maleate resin 3.0 wt%
Sodium ricinoleate 0.3 wt%
Triethanolamine 0.5 wt%
Phenol 0.1 wt%
Benzotriazole 0.1 wt%
Purified water 78.0 wt%
Total 100.0 wt%
Comparative Example 3
The same procedure as in Example 3 was repeated
except that an adduct of 1 mol of glycerin with 40 mols
of ethylene oxide was replaced with
ethylene glycol, to obtain a blue aqueous pigment ink.
The results of a writing test are set forth in Table 1.
Comparative Example 4
The same procedure as in Example 4 was repeated
except that an adduct of glycerin with 10 mols of
propylene oxide was replaced with 10% by weight of
glycerin and that 0.5% of sodium ricinoleate and 77.8% of
purified water were used, to obtain a black aqueous
pigment ink. The results of a writing test are set forth
in Table 1.
Example 5
A blue aqueous pigment ink for ball-point pens was
obtained by the use of the following components. The
results of a writing test are set forth in Table 1.
, .,
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Phthalocyanine blue 7.0 wt%
(Chromofine blue 4965, made by
Dainichiseika Co., Ltd.)
Ethylene glycol 17.0 wt%
Adduct of 1 mol of glycerin with 40 mols
of ethylene oxide 3.0 wt%
Polyoxyethylene (degree of polymerization
of 10) nonyl phenylether, (Nicol NP-10*
made by Nikko Chemicals Co., Ltd.;
having hydrophile-lipophile balance
of 16.5) 3.0 wt%
Patasium linoleate 0.3 wt%
Triethanolamine 0.5 wt%
Phenol 0.1 wt%
Benzotriazole 0.1 wt%
Purified water 69.0 wt%
Total 100.0 wt%
Example 6
A red aqueous pigment ink for ball-point pens was
prepared by the use of the following components. The
results of a writing test are set forth in Table 1.
Red pigment 8.0 wt%
(RED K*represented by the following
formula, made by Fuji Dyestuff Co., Ltd.)
*trade-marks
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SO3- HO COO~
H3C ~ N=N- ~ Ba~
Cl ~
Ethylene glycol 30.0 wt%
Ammonium salt of styrene acrylate resin
(used in Example 1) 3.0 wt%
Potassium linoleate 0.3 wt%
Adduct of 1 mol of trimethylolpropane
with 5 mols of ethylene oxide 2.0 wt%
Triethanolamine 0.5 wt%
Phenol 0.1 wt%
Benzotriazole 0.1 wt%
Purified water 56.0 wt%
Total 100.0 wt%
Example 7
A black aqueous pigment ink for ball-point pens
was prepared by the use of the following components. The
results of a writing test are set forth in Table 1.
Carbon black MA 100 8.0 wt%
(made by Mitsubishi Kasei Co., Ltd.)
Glycerin 10.0 wt%
Ammonium salt of styrene maleate resin 3.0 wt~
Sodium ricinoleate 0.3 wt%
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Adduct of trimethylolpropane
with 10 mols of propylene oxide 1.5 wt%
Triethanolamine 0.5 wt%
Phenol 0.1 wt%
Benzotriazole 0.1 wt%
Purified water 76.5 wt%
Total 100.0 wt~
Comparative Example 5
The same procedure as in Example 6 was repeated
except that an adduct of 1 mol trimethylolpropane with 5
mols of ethylene oxide was omitted and 58% of purified
water was used, to obtain a red aqueous pigment ink.
Comparative Example 6
The same procedure as in Example 7 was repeated
except that an adduct of 1 mol of trimethylolpropane with
10 mols of propylene oxide was omitted and that 0.5% of
sodium ricinoleate and 77.8% of purified water were used,
to obtain a black aqueous pigment ink.
Comparative Example 7
A black aqueous dye ink was obtained by the
use of the following components. The results of a
writing test are set forth in Table 1.
C.I. Direct Black #19 5.0 wt%
Ethylene glycol 10.0 wt~
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Adduct of 1 mol of diglycerin with
30 mols of ethylene oxide 5.0 wt%
Potassium linoleate 0.3 wt%
Triethanolamine 0.5 wt%
Phenol 0.1 wt%
Benzotriazole 0.1 wt%
Purified water 79.0 wt%
Total 100.0 wt%
Above-mentioned Direct Black #19 is represented by
the following formula.
NH2 H2N
H2N ~ N=N ~ N=N ~ N=N ~ N=N ~ NH2
NaO3S SO3Na
Comparative Example 8
A blue aqueous dye ink was obtained by the use
of the following components. The results of a writing
test are set forth in Table 1.
Blue No. 1 for food 6.0 wt%
(C. I. Acid blue 9)
Ethylene glycol 17.0 wt%
Adduct of glycerin with
40 mols of ethylene oxide 3.0 wt%
Potassium linoleate 0.3 wt%
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Triethanolamine 0.5 wt%
Phenol 0.1 wt%
Benzotriazole 0.1 wt%
Anionic fluorine-based surface
active agent 0.01 wt%
Purified water 72.99 wt%
Total 100.0 wt~
Above-mentioned Acid blue 9 is represented the
following formula.
SO3Na
C N(CzH5)CH
So3Q ~ N(C2H5)cHz- ~
SO3Na
Next, inks obtained in Examples 1 to 7 and Compar-
ative Examples 1 to 8 were used in ball-point pens, and a
writing test was then carried out by the use of these
ball-point pens to inspect a ball dent, a writing perfor-
mance and a writing blur. The results of the test are
set forth in Table 1.
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Table 1
Ball Dent Writing Blur of
(,um) PerformanceWritten Letters
Example 1 6 o o
Comp. Ex. 1 30 x o
Example 2 8 o o
Comp. Ex. 2 16 ~ x
Example 3 8 o o
Comp. Ex. 3 25 x o
Example 4 5
Comp. Ex. 4 20
Example 5 6 o
Example 6 6 o o
Comp. Ex. 5 45 x o
Example 7 8 o o
Comp. Ex. 6 22 ~ x
Comp. Ex. 7 6 o x
Comp. Ex. 8 8 o x
As is apparent from the above-mentioned results,
the aqueous pigment inks of the present invention have
the considerably less ball dent, the smooth writing
performance, and the less writing blur.
