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Description  |
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BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a recording liquid a (hereinafter referred
to as ink) for performing record on recording media such as paper, plastic
films, and the like by using an ink-jet recording system or a writing tool
such as a fountain pen, felt pen, or the like.
2. Description of the Prior Art
The ink-jet recording system comprises forming ink droplets by any of
various ink-discharging techniques and causing a portion or all of the
droplets to deposit on a recording medium such as paper or the like to
record an image thereon. Inks known and used for ink-jet recording systems
are solutions or dispersions of various water-soluble dyes or pigments in
liquid mediums such as water and mixtures thereof with water-soluble
organic solvents.
Similar inks are also in use for recording with writing tools such as
fountain pens, felt pens, and ball pens.
A variety of performance characteristics are naturally required for these
inks. The most greatly required characteristic, is liquid stability so as
not to form any precipitate that may clog a nozzle or an orifice of an
ink-jet recorder or may deposit on a pen point during recording or at an
intermission thereof for a short or long period. This characteristic is
especially important to an ink-jet recording system wherein thermal energy
is employed for discharging ink, since the temperature change therein
tends to cause deposition of foreign matter on the surface of the heating
heads However, inks of prior art: need incorporation of some additives in
order to satisfy various requirements on the discharge characteristics,
long-term storage stability, surface tension, and electrical properties of
the ink, the distinctness and optical density of recorced images, etc.
Moreover various impurities are contained in dyes used in prior art inks.
Accordingly, these inks involve a number of difficulties such as clogging
at nozzles or orifices of ink-jet recorders, deposit formation on the
surface of the heating heads, and emergence of precipitates during
prolonged storage of the inks. This is one of the reasons why inkjet
recording systems has not come into wide use even with their many superior
characteristics.
SUMMARY OF THE INVENTION
The primary object of the invention is to provide an ink which will
overcome the above noted shortcomings of inks of prior arts and which,
even at a high concentration, will exhibit such superior stability during
service and long-term storage as not to cause clogging of nozzles or
orifices and not to form any deposit on heating heads of ink-jet recorders
which are actuated by thermal energy.
According to one aspect of the invention, there is provided a liquid
composition containing a water-soluble dye and a solvent, wherein said
liquid composition has a total concentration of divalent and higher valent
metals at 20 ppm or less.
According to another aspect of the invention, there is provided a liquid
composition containing a water-soluble dye and a solvent, wherein said
liquid composition has a magnesium concentration of 4 ppm or less.
According to a further aspect of the invention, there is provided an
ink-jet recording method comprising forming droplets of ink to perform
recording, the ink comprising a liquid composition containing a
water-soluble dye and a solvent, wherein said liquid composition has a
total concentration of divalent and higher valent metals at 20 ppm or
less.
According to a still further aspect of the invention, there is provided an
ink-jet recording method comprising forming droplets of ink to perform
recording, the ink comprising a liquid composition containing a
water-soluble dye and a solvent, wherein said liquid composition has a
total concentration of divalent and higher valent metals at 20 ppm or
less.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
As a result of intensive studies to achieve the above and other objects, it
was discovered that the foregoing problems arise mainly from various
impurities (organic compounds and inorganic compounds, e.g. surfactants
and leveling agents) contained in the commercial dye used in the ink.
Further it was found that divalent and higher valent metal ions or
compounds, particularly magnesium ion, of the above impurities contained
in inks are most responsible for clogging of nozzles or orifices,
formation of precipitates during storage of inks, and in particular the
deposition of foreign matter on heating heads in ink-jet recording systems
utilizing thermal energy. The present invention is based on the above
finding.
Hereinafter the invention is described in more detail.
The fundamental components per se constituting ink of the invention are
already known. One of these components is a water-soluble dye, typical
examples of which are direct dyes, acid dyes, basic dyes, and reactive
dyes. Dyes specially suitable as components of the inks for ink-jet
recording and satisfactory in brightness, water-solubility, stability,
light resistance, and other required properties are, for example, C.I.
Direct Black 17, 19, 32, 51, 71, 108, and 146; C.I. Direct Blue 6, 22, 25,
71, 86, 90, 106, and 199; C.I. Direct Red 1, 4, 17, 28, and 83; C.I.
Direct Yellow 12, 24, 26, and 98; C.I. Direct Orange 34, 39, 44, 46, and
60; C.I. Direct Violet 47 and 48; C.I. Direct Brown 109; C.I. Direct Green
59; C.I. Acid Black 2, 7, 24, 26, 31, 52, 63, 112, and 118; C.I. Acid Blue
9, 22, 40, 59, 93,102, 104, 113, 117, 120, 167, 229, and 234; C.I. Acid
Red 1, 6, 32, 35, 37, 51, 52, 80, 85, 87, 92, 94, 115, 180, 256, 317, and
315; C.I. Acid Yellow 11, 17, 23, 25, 29, 42, 61, and 71; C.I. Acid Orange
7 and 19; C.I. Acid Violet 49; C.I. Basic Black 2; C.I. Basic Blue 1, 3,
5, 7, 9, 24, 25, 26, 28 and 29; C.I. Basic Red 1, 2, 9, 12, 13, 14, and
37; C.I. Basic Violet 7, 14, and 27; and C.I. Food Black 2. These examples
are particulary preferred dyes in the present invention but do not
restrict it.
Such water-soluble dyes are used generally at a concentration of about 0.1
to 20 % by weight in inks of prior art. In the present invention, these
dyes can be used, on the basis of discovery of the invention, not only in
the above concentration range but also in higher concentrations, the ink
of the invention even at a high dye concentration is superior in liquid
stability to inks of prior arts and forms no precipitate.
The liquid medium used in the ink of the present invention is water or
preferably a mixture of water with a water-soluble organic solvent such as
a polyhydric alcohol having the effect of retarding the drying of inks.
Desirably, water used herein is not common water containing various ions
but deionized water. Suitable watersoluble organic solvents for use in
mixture with water are; C.sub.1 -C.sub.4 alkyl alcohols, e.g. methanol,
ethanol, n-propanol, isopropanol, n-butanol, secbutanol, tert-butanol, and
isobutanol; amides, e.g. dimethylformamide and dimethylacetamide; ketones
or keto-alcohols, e.g. acetone and diacetone alcohol; ethers, e.g.
tetrahydrofuran and dioxane; polyalkylene glycols, e.g. polyethylene
glycol and polypropylene glycol; alkylene glycols having 2-6 carbon atoms
in the alkylene group, e.g. ethylene glycol, propylene glycol, butylene
glycol, triethylene glycol, 1,2,6-hexanetriol, thiodiglycol, hexylene
glycol, and diethylene glycol; glycerol; lower alkyl ethers of polyhydric
alcohols, e.g. ethylene glycol methyl (or ethyl) ether, diethylene glycol
methyl (ethyl) ether and triethylene glycol monomethyl (or monoethyl)
ether; N-methyl-2-pyrrolidone; and 1,3-dimethyl-2-imidazolidinone. Of
these various alcohols, preferred are polyhydric alcohols such as
diethylene glycol and lower alkyl ethers of polyhydric alcohols such as
triethylene glycol monomethyl (or monoethyl) ether.
The content of the water-soluble organic solvent in the ink is in a range
of generally 0 to 95%, preferably 10 to 80%, particularly preferably 20 to
50%, by weight based on the whole weight of the ink.
The water content in the ink is chosen from a wide range, depending on the
nature and composition of the ink medium and desired properties of the
ink, but is generally 10 to 100%, preferably 10 to 70%, particularly
preferably 20 to 70%, by weight based on the whole weight of the ink.
The ink of the present invention, having fundamental components as
described above, is characterized primarily in that the total content of
divalent and higher valent metals therein is 20 ppm or less.
According to the present invention, the stability of ink compositions, dyes
used in inks of prior arts, being produced originally for the purpose of
fiber dyeing, contain additives, e.g. surfactants and leveling agents, and
further diversified impurities such as sodium chloride, sodium sulfate,
and salts of alkaline earth metals, and such impurities are known to cause
various difficulties in ink-jet recording and writing with a pen or the
like. Ink compositions were prepared from dyes highly purified by removing
the impurities. These ink compositions, although reducing significantly
the above difficulties, were not satisfactory enough in preventing the
deposition of foreign matters on the heating heads in ink-jet recording
systems, particularly those actuated by thermal energy. The present
inventors further discovered that commercial dyes contain considerable
amounts (tens to hundreds of ppm) of divalent and higher valent metal ions
(e.g. calcium, magnesium, manganese, iron, aluminum, and silicon metal
ions) or compounds thereof (e.g. colloidal oxides and hydroxide), and that
these substances, magnesium in particular, are the primary cause for
formation of deposits on the surface of the heating heads and affect most
strongly the formation of foreign matter. This finding has led to the
present invention.
The total content of the above bothering substances in the ink is
controlled by the following procedure.
First a dye is precipitated from its aqueous solution at a desired
concentration by adding sodium sulfate. The precipitate is filtered,
washed with a saturated aqueous sodium sulfate solution, and dried. A
prescribed amount of the dried dye solid is dissolved in a water-soluble
organic solvent, and the solution is filtered. Any water-soluble organic
solvent may be used herein, as long as it is a poor solvent for sodium
sulfate and a good one for the dye. An optimum solvent depending on the
structure of the dye can be freely chosen arbitrarily. Usually alcohols,
glycols, and glycol ethers, as mentioned before, are favorable. The
obtained filtrate may be filtered again after standing for 1 to 3 days.
Subsequently the filtrate, combined with a prescribed amount of water, is
stirred and then passed through a layer of a cation exchange resin. An
additive is incorporated, as required, into the effluent with stirring to
prepare an ink. The contents of divalent and higher valent metals in the
ink is determined by atomic absorption spectrophotometry or the induction
plasma emission spectral analysis to ascertain the total contents being
not more than 20 ppm, and to put the ink into service.
The magnesium content in the ink may be adjusted as follows:
First a dye is percipitated from its aqueous solution of a desired
concentration by adding sodium sulfate. Then the precipitate is filtered,
washed with a saturated aqueous sodium sulfate solution, and dried. A
prescribed amount of the dried dye is dissolved in a water-soluble organic
solvent, and the solution is filtered. Also in this case, any
water-soluble organic solvent may be used, as long as it is a poor solvent
of sodium sulfate and a good solvent of the dye. An optimum solvent
depending on the structure of the dye can be arbitrarily chosen. Usually
alcohols, glycols, and glycol ethers, as mentioned before, are favorable.
Subsequently, the thus obtained filtrate, combined with a prescribed amount
of water, is stirred and then passed through a layer of a cation exchange
resin. The effluent, after proper pH adjustment, is left standing for 7 to
10 days and filtered. Then an additive is added, if necessary, to the
filtrate with stirring to prepare an ink. The ink is put into service
after the content of magnesium therein has been ascertained by atomic
absorption spectrophotometry or the induction plasma emission spectral
analysis to be not more than 4 ppm.
In the treatment procedure described above; the first salting-out treatment
is intended primarily to remove sodium chloride which is a representative
impurity contained in large amounts in usual commercial dyes; the second
treatment with a water-soluble organic solvent is intended primarily to
remove both of sodium sulfate originally contained as an impurity in the
dye and added in a large amount in the preceding salting-out treatment;
the long standing of the filtrate after filtration of the dye dissolved in
the organic solvent and the long standing of the liquid treated with a
cation exchange resin in the case of the magnesium content control, both
followed by filtration are intended primarily to remove the colloidal
substances containing divalent and higher valent metals and to remove
colloidal magnesium, respectively; and the treatment with a cation
exchange resin is intended to remove divalent and higher valent metal
ions, particularly magnesium ions.
A method for controlling the content of divalent and higher valent metals
or the content of magnesium, in the ink, has been described above. The
controlling method, however, is not limited to the above, and any other
method may be employed which permits removing said ions or colloidal
compounds of divalent and higher valent metals, particularly ions or
colloidal compounds of magnesium. Such other methods include, for example,
aeration, sedimentation by use of a flocculant, filtration, lime
softening, and electrolysis.
Besides the impurities contained in the dyes, those contained in the water
are considered as sources of the contamination of inks with ions or
compounds of divalent and higher valent metals, particularly ions or
compounds of magnesium. This contamination can be avoided by using
distilled water, deionized water, or both of them. The greatest source of
ink contamination with divalent and higher valent metals, particularly
magnesium are impurities contained in the dyes to be used. In particular
when the used dyes are unpurified commercial products, markedly large
amounts of such metals are often contained in the inks. For instance,
analysis showed as high as several thousand ppm of these impurities
contained in a certain dye powder.
While the above description has been given chiefly on the removal of
divalent and higher valent metals, particularly magnesium, contained in
inks, it is desirable in practice to remove them simultaneously with
various other inorganic salts such as sodium chloride and sodium sulfate.
Besides the basic components described above, the ink of the present
invention is allowed to contain various known additives, if necessary,
such as a dispersant, surfactant (cationic, anionic, or nonionic),
viscosity modifier (e.g. polyvinyl alcohol, cellulosic compound, or some
other water-soluble resin), surface tension modifier (e.g. diethanolamine
or triethanol amine), pH conditioner (e.g. a buffer solution), and
antimold agent.
An inorganic salt such as lithium chloride, ammonium chloride, or sodium
chloride is added as a resistivity modifier to inks which will be used in
a type of ink-jet recording system wherein electric charge is given to the
inks for the ejection thereof. For use in a type of ink-jet recording
system wherein inks are ejected by the action of thermal energy, thermal
properties (e.g. specific heat, coefficient of thermal expansion, and heat
conductivity) of the inks are conditioned occasionally.
The ink of the present invention, prepared as described above, is
sufficient for solving the problems of the prior art and is excellent and
balanced as such in recording characteristics (signal responsiveness,
stability of droplet formation, discharge stability, workability in
continuous recording for many hours, and discharge stability after a long
intermission), storage stability, fixability on recording media, light and
weathering resistance of resulting recorded images, and so forth. Thus,
the present ink is useful for various types of ink-jet recording systems
and for writing tools, particularly for the ink-jet recording systems
utilizing thermal energy, wherein the formation of deposits from inks is a
most undesirable matter.
The present invention is illustrated in more detail with reference to the
following examples. In these examples, parts and % are all by weight.
EXAMPLE 1a
Preparation of ink
Sodium sulfate was added to a saturated aqueous solution of a commercial
dye (Direct Fast Yellow R supplied by Sumitomo Chemical Co., Ltd.) with
stirring to precipitate the dye. This precipitate was filtered, washed
with a saturated solution of sodium sulfate in pure water, and dried. This
dried solid was weighed out in such a prescribed amount that the dye
concentration in the intended ink would be 3%, and was dissolved in a
mixture of ethylene glycol and N-methyl-2-pyrrolidone (3:1). This aqueous
solution was filtered under pressure through a Teflon filter having an
average pore diameter of 1 .mu.m. The filtrate was weighed in a plastic
container, allowed to stand in a cold dark room for 3 days, and filtered
again through a Teflon filter (avarage pore diameter 1 .mu.m). Then 60
parts of water was added to 40 parts of the filtrate with stirring to give
an ink. This ink was passed through a layer of a cation exchange resin
C464 (supplied by Sumitomo Chemical Co., Ltd.). The effluent was adjusted
to pH 9.8 with an 0.1 N aqueous NaOH, and measured for the total content
of divalent and higher valent metals by induction plasma emission spectral
analysis. The found content was 20 ppm. The following characteristics
T.sub.1 -T.sub.5 of the thus obtained ink were examined by using (for
T.sub.2 -T.sub.5) a recorder provided with on-demand type multiheads
(discharge orifice diameter 35 .mu.m, resistance of heat-generating
resistor 150 ohm, driving voltage 30 V, frequency 2 KHz) which perform
recording with ink droplets discharged by applying thermal energy to the
inks fed therein. The ink was found good in all the characteristics
T.sub.1 -T.sub.5.
(T.sub.1) Long-term stability: Samples of the ink, sealed in plastic bags,
were stored for 6 months at temperatures of -30.degree. C. and 60.degree.
C. In both the cases, neither insoluble matter nor change in physical
properties including color was observed.
(T.sub.2) Discharge stability: The discharge was conducted continuously for
24 hours in atmospheres of room temperature, 5.degree. C., and 40.degree.
C. Under all the conditions, high quality recording could be continued
steadily throughout the operation.
(T.sub.3) Discharge responsiveness: The discharge was conducted at
intervals of 2 sec and also conducted after 2 months' standing of a sample
of the ink. In both the cases, none of the orifices were clogged and
images were recorded uniformely and steadily.
(T.sub.4) Quality of recorded image: Images recorded on recording media
shown later in Table 1 were high in optical density and distinctness, and
percentages of decrease in the optical density were up to 1% after 6
months' exposure of the images to indoor light.
(T.sub.5) Fixability on various recording media:
An image was recorded on each of recording media shown later in Table 1a,
and 15 sec later, was rubbed with a finger, and the aberration and
blotting of the image were checked. On any of the recording media, neither
the aberration nor the blotting was observed. Thus the ink showed superior
fixability.
EXAMPLES 2a-5a
In the same manner as in Example 1a, inks were prepared from commercial
dyes shown later in Table 2a, and were tested for the characteristics
T.sub.1 -T.sub.5. All the inks gave superior results similarly to Example
1a.
EXAMPLE 6a
Inks of Examples 2a, 3a, 4a, and 5a were tested as yellow, magenta, cyan,
and black inks, respectively, for the characteristics T.sub.1 -T.sub.5 in
the same manner as in Example 1a except that recording was conducted by
using a recorder having an on-demand type head (discharge orifice diameter
50 .mu.m, driving voltage for piezoelectric oscillators 60 V, frequency 4
KHz) which discharges ink droplets by means of piezoelectric oscillators
to perform recording. All these inks gave superior results.
EXAMPLE 7a
Copies of a full-color photograph were made by using inks of Examples 2a,
3a, 4a, and 5a as yellow, magenta, cyan, and black inks, respectively and
by means of the ink-jet recorder used in Examples 2a-5a. The obtained
image was bright in each color and good in color reproduction.
EXAMPLE 8a
Felt pens were filled respectively with different-color inks prepared in
Examples 2a-5a, and were allowed to stand for 10 days with the caps
removed. With these pens, writing could be carried out smoothly without
being blurred.
COMPARATIVE EXAMPLE A
Sodium sulfate was added to a saturated aqueous solution of the same dye
(Direct Fast Yellow R) as used in Example 1a, with stirring to precipitate
the dye. This precipitate was filtered, washed with a saturated solution
of sodium sulfate in pure water, and dried. The dried solid was weighed
out in such a prescribed amount that the dye concentration in the intended
ink would be 3%, and was dissolved in a mixture of ethylene glycol and
N-methyl-2-pyrrolidone (3:1). This solution was filtered under pressure
through a Teflon filter (average pore diameter 1 .mu.m). Then 60% of water
was added to 40% of the filtrate to prepare the intended ink.
The content of divalent and higher valent metals in this ink was 30 ppm as
measured by atomic absorption spectrophotometry. The characteristics
T.sub.1 -T.sub.5 of this ink were examined in the same manner as in
Example 1a. As to T.sub.1, insoluble matter appeared in the ink after one
month's storage thereof. As to T.sub.2, the ink discharge stopped
frequently, hence requiring a change (increase) in the driving voltage. On
microscopic observation of the surface of a heating head, a brown deposit
was seen adhering thereto. As to T.sub.3, the ink left standing for one
month caused orifice clogging and the discharge of the ink was found
unstable.
Further, two inks were prepared from the above original dye by following
the treatment procedure of Example 1a except that the standing treatment
was neglected for one of the inks and the cation exchange treatment for
the other ink. The total content of divalent and higher valent metals was
found to be 23 ppm in the former ink and 25 ppm in the latter ink. Results
of the same T.sub.1 -T.sub.5 tests indicated that these inks were inferior
in these performance characteristics to the ink of Example 1a, i.e. the
ink prepared without neglecting any of the treatment steps of Example 1a.
EXAMPLE 1b
Preparation of ink
Sodium sulfate was added to a saturated aqueous solution of a commercial
dye (Direct Fast Yellow R, supplied by Sumitomo Chemical Co., Ltd.) with
stirring to precipitate the dye. This precipitate was filtered, washed
with a saturated solution of sodium sulfate in pure water, and dried. The
dried dyes was weighed out in such a prescribed amount that the dye
concentration in the intended ink would be 3%, and was dissolved in a
mixture of ethylene glycol and N-methyl-2-pyrrolidone (3:1). This aqueous
solution was filtered under pressure through a Teflon filter (average pore
diameter 1 .mu.m), and 60 parts of water was added to 40 parts of the
filtrate with stirring to give an ink. This ink was passed through a layer
of cation exchange resin C-466 (supplied by Sumitomo Chemical Co., Ltd.).
The effluent was adjusted to pH 9.8 with 0.1 N aqueous NaOH, allowed stand
for 10 days in a plastic container, and filtered again under pressure
through a Teflon filter (average pore diameter 1 .mu.m), thus preparing an
ink of the present invention.
The magnesium content in this ink was 3.8 ppm as measured by atomic
absorption spectrophotometry.
This ink was tested for the characteristics T.sub.1 -T.sub.5 in the same
manner as in Example 1a, giving similarly good results. In the Tests of
T.sub.4 and T.sub.5, recording was conducted on the same recording media
as used in Example 1a which are shown in Table 1a.
EXAMPLES 2b-5b
In the same manner as in Example 1b, inks were prepared from commercial
dyes shown later in Table 2b and and were tested for the characteristics
T.sub.1 -T.sub.5. All the inks gave superior results similarly to Example
1b.
EXAMPLE 6b
Inks of Examples 2b, 3b, 4b, and 5b were tested as yellow, magenta, cyan,
and black inks, respectively, for the characteristics T.sub.1 -T.sub.5 in
the same manner as in Example 1b except that recording was conducted by
using a recorder having an on-demand type head (discharge orifice diameter
50 .mu.m, driving voltage for piezoelectric oscillators 60 V, frequency 4
KHz) which discharges ink droplets by means of piezo-electric oscillators
to perform recording. All these inks gave superior results.
EXAMPLE 7b
Copies of a full-color photograph were made by using inks of Examples 2b,
3b, 4b, and 5b as yellow, magenta, cyan, and black inks, respectively, and
by means of the ink-jet recorder used in Examples 2b-5b. The obtained
image was blight in each color and good in color reproduction.
EXAMPLE 8b
Felt pens were filled respectively with different-color inks prepared in
Examples 2b-5b, and allowed to stand for 10 days with the caps removed.
With these pens, writing could be carried out smoothly without any
ink-deficient character.
COMPARATIVE EXAMPLE B
Sodium sulfate was added to a saturated aqueous solution of the same dye
(Direct Fast Yellow R) as used in Example 1b, with stirring to precipitate
the dye. This precipitate was filtered, washed a saturated solution of
sodium sulfate in pure water, and dried. The dried solid was weighed out
in such a prescribed amount that the dye concentration in the intended ink
would be 3%, and was dissolved in a mixture of ethylene glycol and
N-methyl-2-pyrrolidone (3:1). This solution was filtered under pressure
through a Teflon filter (average pore diameter 1 .mu.m). Then, 60% of
water was added to 40% of the filtrate to prepare the intended ink.
The magnesium content in the ink was 6.1 ppm as measured by atomic
absorption spectrophotometry. The characteristics T.sub.1 -T.sub.5 of this
ink were examined in the same manner as in Example 1b.
As to T.sub.1, insoluble matter appeared in the ink after one month's
storage thereof. As to T.sub.2, the ink discharge stopped frequently,
hence requiring a change (increase) in the driving voltage. On microscopic
observation of the surface of a heating head, a brown deposit was seen
adhering thereto. As to T.sub.3, the ink left standing for one month
caused orifice clogging and the discharge of the ink was found unstable.
Further, two inks were prepared from the above original dye one by
employing cation exchange treatnent and the othre by employing
electrostatic treatment, respectively in addition to the above-mentioned
treatment. The magnesium content was found to be 4.8 ppm in the former ink
and 5.1 ppm in the latter ink. Results of the same tests for T.sub.1
-T.sub.5 indicated that the perfomance characteristics of these inks were
insufficient for the practical use, though found to be improved to a
certain extent as compared with those of the ink subjected to none of the
above additional treatment.
TABLE 1a
______________________________________
Recording Nature of
medium recording
(tradename) medium Maker for recording medium
______________________________________
Ginkan High Sanyo Kokusaku Pulp Co.,
quality Ltd.
Seven Star High Hokuetsu Paper Mfg. Co.,
quality Ltd.
Hakubotan Medium Honshu Paper Mfg. Co.,
quality Ltd.
Toyo Filter non-sized Toyo Roshi Co., Ltd.
paper No. 4 paper
______________________________________
TABLE 2a
______________________________________
Total conc. of
Example divalent and higher
No. Dye valent metals in ink
______________________________________
2a Water yellow 6 19 ppm
3a Chugonol Fast Red 3B
20 ppm
4a Kayarus Turqoise
17 ppm
Blue GL
5a Special Black 7984
20 ppm
______________________________________
TABLE 2b
______________________________________
Example
No. Dye Mg content in ink
______________________________________
2b Water Yellow 6 3.9 ppm
3b Chugonol Fast Red 3B
2.1 ppm
4b Kayarus Turqoise
3.5 ppm
Blue GL
5b Special Black 7984
2.9 ppm
______________________________________
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