Liquid recording medium

A liquid recording medium for use in a recording process, wherein said recording medium is discharged from a discharge orifice in a recording head and spattered in the form of droplets for recording, and containing (a) a recording agent for forming recorded images and (b) a carrier liquid capable of dissolving or dispersing the recording agent. The recording agent is a compound having 2-8 sulfo groups per molecule and having the formula (A) ##STR1## where the Q.sub.1 radicals are similar or dissimilar members selected from phenylene and naphthylene, the Q.sub.2 radicals are similar or dissimilar members selected from phenyl and naphthyl, the Q.sub.1 radicals and the Q.sub.2 radicals may be unsubstituted or amino substituted, hydroxyl substituted or sulfo substituted, R.sub.1 -R.sub.6 are similar or dissimilar members selected from hydrogen, amino, hydroxyl and sulfo, and said sulfo groups as mentioned above are all in the form of sodium salt or quaternary ammonium salt.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to liquid recording medium suitable for use in a 
recording method which performs image recording by ejecting and spattering 
the liquid recording medium in the form of droplets from an orifice of a 
nozzle onto a recording member. More particularly, the invention is 
concerned with a novel liquid recording medium with various properties of 
remarkable improvement such as stability and responsiveness of the 
droplets at their ejection from the discharge orifice, stability in 
storage over a long period of time, affinity for recording members, 
quality of the image to be recorded, and so forth. 
2. Description of the Prior Arts 
So-called non-impact recording methods having recently drawn public 
attention, because uncomfortable noises during the recording operation 
could be reduced to a negligible order. Among these particularly important 
is the so-called ink jet recording method which allows high-speed 
recording on a plain paper without particular image-fixing treatment, and, 
in this particular field, there have been proposed various approaches 
including those already commercialized, and others still under 
development. 
Such ink jet recording method is to perform recording by spattering the 
liquid recording medium, or the so-called "ink", in the form of droplets 
and adhering the same onto the recording member. 
Such ink used for jet recording method is required to have various 
characteristics depending upon the recording mode as well as 
characteristics essential to liquid recording medium for printing such as 
offset printing or writing. 
With a view to satisfying such various conditions, there have heretofore 
been made various proposals. For instance, U.S. Pat. No. 4,106,027 
discloses a liquid recording medium having a low viscosity of 5 c.p. or 
below and an electrical conductivity of 10.sup.-4 ohm.sup.-1 cm.sup.-1 or 
above, and which is principally composed of an organic solvent. The liquid 
recording medium is used in a recording device of a type in which the 
droplets are charged. For the organic solvent, the prior patent uses, as 
its principal component, alkane or cycloalkane having the carbon content 
of from 5 to 8, lower alcohols, ethers (diethylether, dioxane, 
tetrahydrofuran), aromatic hydrocarbons, halogenated hydrocarbons, or 
esters. The recording agent components used in this system are 
solvent-soluble anthraquinone dyes, azo dyes, xanthene dyes, phenacine 
dyes, oxazine dyes and the like. 
On the other hand, there have also been known many kinds of liquid medium 
component system containing water. For example, U.S. Pat. No. 3,687,887 
discloses an aqueous system liquid recording medium consisting of an 
organic resin binder such as styrene-maleic anhydride, etc., ether of 
polyhydric alcohol (particularly, glycol), and a recording coloring agent 
(carbon black and dyestuff suspended in water) agent so as to obtain a 
recorded image having high image density and good image-fixing property on 
the image forming base such as gelatin, resin film, etc. The recording 
agent used here is a mixture of carbon black suspended in water and an 
orthochromatic dye (direct dye or acid dye). 
Further U.S. Pat. No. 3,705,043 teaches a liquid recording medium 
consisting of a recording agent, a wetting agent (polyhydric alcohol, 
alkyl ether of polyhydric alcohol, or a mixture thereof), and water, with 
a view to obtaining an infrared ray absorptive image, exhibiting 
appropriate viscosity value over a long period of time, and not bringing 
about clogging of the discharge orifice. As the recording agent, there are 
disclosed infrared absorbers such as water-soluble nigrosine dyes, 
spirit-soluble nigrosines, modified water-soluble nigrosine dyes, 
water-dispersed carbon black and mixtures thereof. 
U.S. Pat. No. 3,776,742 discloses an effective liquid recording medium 
having electric conductivity and surface tension of 35 to 70 dyn/cm, and 
consisting of a water soluble dyestuff, an electrically conductive 
substance (metal chlorides, etc.), a low molecular weight polyol, and a 
crystalline organic compound such as urea, etc. This aqueous system liquid 
recording medium is effective in quick image-fixing on a recording member 
such as paper which contains therein cellulose. As a water-soluble black 
dye, there may be mentioned direct dyes of a biphenyl derivative type, 
acid dyes of a metal complex type, reactive dyes having a pyrimidyl and 
the like. 
However, it is considerably difficult to obtain a liquid recording medium 
capable of satisfying various requisites simultaneously, and there remain 
problems to be solved. 
That is, this kind of recording method, i.e., ink jet recording method, 
comprises ejecting a liquid recording medium through a discharge orifice 
of a minute diameter (usually 10-20 .mu.m) in a recording head and 
spattering in the form of droplets for recording, and therefore, it is 
necessary that the method is of high signal responsiveness and high 
fidelity reproduction. 
In addition, there are requested various characteristics, that is, the 
liquid recording medium can pass through a nozzle at a speed corresponding 
to the recording speed; after recording, the liquid recording medium can 
be rapidly fixed to the recording member; after fixed, the recorded images 
are of high light resistance, high water resistance and high 
weatherability; the recorded images have a sufficient density; the shelf 
life is long; there occurs no clogging in orifices and nozzles; and so on. 
When an electric or electrostatic method is employed to form or control the 
liquid droplets, electric or electrostatic property of the liquid 
recording medium should be appropriately selected. In order to satisfy 
those conditions, viscosity, surface tension, resistivity, electric 
capacity, dielectric constant and the like of the liquid recording medium 
are appropriately adjusted. 
The liquid recording medium is fundamentally composed of two components, 
that is, a recording agent which serves to form recorded images and a 
carrier liquid which carries the recording agent. However, in practice, a 
recording agent affects the characteristics of the liquid recording medium 
to a great extent and therefore, it is very difficult to obtain a liquid 
recording medium of desired characteristics by using only two components. 
Therefore, various additives are added as third components so as to adjust, 
for example, viscosity, surface tension, resistivity and the like. 
However, it is not easy to adjust each of the various characteristics 
independently by adding the third component. For example, when a viscosity 
adjusting additive is added to a liquid recording medium which surface 
tension is adjusted to a desired value, for the purpose of adjusting the 
viscosity, the other physical properties, in particular, surface tension, 
are changed sometimes. 
Even if desirable characteristics of a liquid recording medium are obtained 
when it is prepared, it is often very difficult to maintain such desirable 
characteristics at the time of preparation after long use, long storage or 
long allowing to stand. 
In particular, concentration of non-volatile components such as the 
recording agent and the like increases as a result of vaporization of 
carrier liquid components and thereby the physical properties such as 
surface tension and the like vary to a great extent sometimes. As the 
result, good recording can not be effected and further, sometimes liquid 
droplets can not be formed at all because the liquid path in the device is 
clogged. 
In addition, it is desired to select density of recorded images at a wide 
range, or to select concentration of the recording agent in the liquid 
recording medium at a wide range without varying physical properties of 
the liquid recording medium for the purpose of improving reproducibility 
of half tones, sharpness and the like. 
In case of conventional recording agents, the concentration greatly affects 
surface tension which has a great effect on various important 
characteristics such as ejection stability, liquid droplet forming 
property, flowability in the conduit of the device, signal responsiveness 
and the like. Therefore, it is necessary to control the physical 
properties at each time when the liquid recording medium is prepared with 
a different concentration of the recording agent. 
Therefore, the recording agent should be such material that does not affect 
physical properties, in particular, surface tension, of the liquid 
recording medium upon adding or changing the concentration. In addition, 
the recording agent should have excellent light resistance, 
weatherability, fixability to recording members and high sharpness and 
further a property that it does not precipitate by crystallization or 
coagulation. 
SUMMARY OF THE INVENTION 
According to the present invention, there is provided a liquid recording 
medium for used in a recording process, wherein said recording medium is 
discharged from a discharge orifice in a recording head and spattered in 
the form of droplets for recording, and containing (a) a recording agent 
for forming recorded images and (b) a carrier liquid capable of dissolving 
or dispersing the recording agent, characterized in that said recording 
agent is a compound having 2-8 sulfo groups per molecule and having the 
formula (A) 
##STR2## 
where the Q.sub.1 radicals are similar or dissimilar members selected from 
phenylene and naphthylene, the Q.sub.2 radicals are similar or dissimilar 
members selected from phenyl and naphthyl, the Q.sub.1 radicals and the 
Q.sub.2 radicals may be unsubstituted or amino substituted, hydroxyl 
substituted or sulfo substituted, R.sub.1 -R.sub.6 are similar or 
dissimilar members selected from hydrogen, amino, hydroxyl, and sulfo, and 
said sulfo groups as mentioned above are all in the form of sodium salt or 
quaternary ammonium salt. 
An object of the present invention is to provide a liquid recording medium 
comprising a recording agent which does not or hardly affects the liquid 
physical properties, in particular, surface tension, of the liquid 
recording medium and has an excellent light resistance, weatherability, 
image density and fixability and neither crystallizes nor coagulates in 
the carrier liquid. 
Another object of the present invention is to provide a liquid recording 
medium comprising a recording agent, a dye compound as represented by the 
formula (A) above which shows excellent signal responsiveness, stability 
of forming liquid droplets, stability of ejection, fluidity in the 
conduit, fixability to a recording member and can be continuously fed 
through a nozzle for a long time at a speed sufficiently corresponding to 
the recording speed. 
A further object of the present invention is to provide a liquid recording 
medium which can produce recorded images of excellent light resistance, 
weatherability, water resistance, high image density and high sharpness, 
and free from satelite dot. 
Still another object of the present invention is to provide a liquid 
recording medium which contains, as a recording agent, the compound (A) 
which does not substantially affect physical properties, in particular, 
surface tension, of the liquid recording medium excluding the compound 
(A). 
DESCRIPTION OF THE PREFERRED EMBODIMENTS 
According to the present invention a dye compound used as the recording 
agent is a compound of the formula (A) above. 
It is preferable that the central naphthalene ring (2,7-naphthylene) of 
compound (A) has sulfo groups in the form of sodium salt or quaternary 
ammonium salt at the symmetrical positions. For example, it is preferably 
that the central naphthalene ring has a sulfo group in the form of sodium 
salt or quaternary ammonium salt at the 3- and 6-positions, and amino and 
hydroxyl groups at the 1- and 8-positions, respectively. 
The compound (A) usually has 2-8 sulfo groups, preferably 3-8 sulfo groups. 
More preferably, at least one of Q.sub.1 and Q.sub.2 has a sulfo group. 
And further it is preferable that the central naphthalene ring has sulfo 
groups all at the same side with respect to the long molecular axis of 
compound (A) and hydroxyl or amino groups at the opposite side with 
respect to the long molecular axis. 
The liquid recording medium containing a compound (A) having such 
substituents shows excellent results. 
As Q.sub.1 radicals, unsubstituted or substituted phenylene groups, or 
sulfo (in the form of sodium salt or quaternary ammonium salt) substituted 
phenylene groups are preferable. When sulfo group is in the form of 
quaternary ammonium salt, solubility of compound (A) in a carrier liquid 
composed of water and a solvent other than water such as a water-soluble 
solvent, for example, alcohols, is advantageously higher than the 
solubility of compound (A) having the sulfo group in the form of sodium 
salt. 
With respect to the structure of quaternary ammonium salt of sulfo group, 
it is preferable that hydrogen atom(s) adjacent to the N atom is 
substituted by C.sub.1 -C.sub.5 alkyl, --C.sub.2 H.sub.4 OH or 
##STR3## 
and in particular, 1-3 hydrogen atoms adjacent to the N atom are 
substituted by the above mentioned radicals. 
An amount of the dye of compound (A) to be used may be optionally 
determined depending upon the desired density of recorded images, type of 
recording system, kinds of other additives, desired liquid physical 
properties and the like. The amount is usually 0.1-15% by weight of the 
total amount of the liquid recording medium, preferably 0.5-10% by weight 
and more preferably 1-5% by weight. 
The dye of compound (A) as the recording agent used in the present 
invention does not or hardly affect the liquid physical properties, in 
particular, surface tension. Therefore, if physical properties of a liquid 
recording medium composed of various components except the compound (A) 
are preliminarily adjusted to desired values and then the compound (A) is 
added in various amounts, it is possible to obtain liquid recording media 
having desired concentration of the recording agent without changing the 
originally produced physical properties. 
Representative compounds (A) as the recording agent may be mentioned as 
shown below, dye compound Nos. 1-81, where 
##STR4## 
represents benzene ring, 
##STR5## 
represents naphthalene ring and 
##STR6## 
represents cyclohexane ring. 
##STR7## 
Among the dye compounds No. 1-No. 81 (polyazo dyes), dye compound No. 80 is 
known as C.I. Direct Black 19 (C.I. 35255). 
These dye compounds may be prepared by the methods of synthesis as 
disclosed in "Senryo Binran" (Handbook of Dyes), page 382, published by 
Maruzen K. K., Japan, Oct. 30, 1974: "Riron, Seizo, Senryo Kagaku" (Dye 
Chemistry-Theory and Practice), page 587, published by Gihodo, Japan, July 
15, 11968, and the like. 
As are well known in the art of organic synthesis, these methods are 
carried out by subjecting naphtholamines and aromatic amines (e.g. 
aniline, naphthylamine or derivatives thereof) corresponding to the end 
products, i.e., the desired dye compounds, to diazotization and coupling. 
For example, dye compound No. 80 above may be produced by using H-acid, 
p-nitroaniline and m-phenylenediamine well known as dye intermediates and 
following the procedures shown below. 
##STR8## 
Repeating the above mentioned method except that 
##STR9## 
are used in place of m-phenylenediamine, there are obtained dye compound 
No. 1-No. 3, respectively. 
When naphthylamine such as 
##STR10## 
is used in place of p-nitroaniline and 
##STR11## 
is used in place of m-phenylenediamine, dye compound No. 13 is obtained. 
Further, as known in the art of organic synthesis, when the dye compounds 
thus obtained are precipitated in a strongly acidic aqueous solution 
(SO.sub.3 Na group is converted to SO.sub.3 H group) and an amine is added 
thereto in an alcohol solvent to produce a salt compound of Nos. 56-71 
(quaternary ammonium salt). 
For example, dye compound 56 is obtained as shown below: 
##STR12## 
where D stands for the basic structure of the dye and R is methyl. 
In a similar way, dye compound Nos. 32-47 may be produced from K-acid 
##STR13## 
as an aminonaphthol, and appropriate aromatic amines. 
When these compounds are converted to quaternary ammonium salts to produce 
salt compounds of a type of No. 72-No. 75. 
Further, dye compound Nos. 48-55 may be produced from 
##STR14## 
aromatic amines. When these compounds are converted to quaternary ammonium 
salts to produce salt compounds of a type of dye compound Nos. 76-79. 
Among the above mentioned dye compounds, dye compound Nos. 1-31 and 5-71 
are preferable because the liquid recording medium containing one of those 
compounds shows a good fixability to recording members and less change of 
physical properties of the liquid caused by change of concentration of the 
recording agent. 
The liquid recording medium according to the present invention 
fundamentally comprises a dye compound represented by the formula (A) 
(supra) (recording agent) and a carrier liquid for dissolving or 
dispersing the recording agent. 
As the carrier liquid used in the present invention, there may be mentioned 
water and a mixture of water and a water-soluble organic solvent, 
preferably, content of water being more than that of the water-soluble 
organic solvent in the mixture. 
Representative examples of such water-soluble organic solvents are alkyl 
alcohols having 1 to 4 carbon atoms such as methyl alcohol, ethyl alcohol, 
n-propyl alcohol, iso-propyl alcohol, n-butyl alcohol, sec-butyl alcohol, 
tert-butyl alcohol, iso-butyl alcohol, etc.; amides such as dimethyl 
formamide, dimethyl acetamide, etc.; ketones or ketone alcohols such as 
acetone, diacetone alcohol, etc.; ethers such as tetrahydrofuran, dioxane, 
etc.; and substituted pyrrolidones such as N-methyl-2-pyrrolidone etc. 
An amount of the water-soluble organic solvent is selected in such a way 
that it does not adversely affect the resulting liquid recording medium. 
The amount of water-soluble organic solvent to be mixed with water is 
appropriately determined depending upon an amount of the recording agent, 
type of the organic solvent and type and amount of third components 
(infra) which may be added if desired, and the amount of water-soluble 
organic solvent is usually less than 0.7 parts by volume, preferably less 
than 0.5 parts by volume, per 1 part by volume of water. 
Third components may be added to the liquid recording medium so as to 
control more appropriately the recording agent and physical properties of 
the liquid. 
As the third components for adjusting physical properties of the liquid to 
desirable ranges, there may be mentioned viscosity regulating agents, 
surface tension regulating agents, pH regulating agents, resistivity 
regulating agents and the like, and further wetting agent and anti-fungal 
may be added to improve the liquid recording medium further. 
Such viscosity regulating agent and surface tension regulating agent are 
added principally for achieving a flowability in the nozzle at a speed 
sufficiently responding to the recording speed, for preventing dropping of 
recording medium from the orifice of nozzle to the external surface 
thereof, and for blotting (widening of spot) on the record-receiving 
member. 
For these purposes any known viscosity regulating agent or surface tension 
regulating agent is applicable as long as it does not provide undesirable 
effect to the carrier liquid and recording material. 
Examples of such viscosity regulating agent are polyvinyl alcohol, 
hydroxypropyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, 
methyl cellulose, watersoluble acrylic resins, polyvinylpyrrolidone, gum 
Arabic, starch etc. 
The surface tension regulating agents effectively usable in the present 
invention include anionic, and nonionic surface active agents, such as 
polyethyleneglycolether sulfate, ester salt etc.--as the anionic compound; 
and polyoxyethylenealkylether, polyoxyethylenealkylphenylether, 
polyoxyethylenealkylesters, polyoxyethylenesorbitan alkylester, 
polyoxyethylene alkylamines etc. as the nonionic compound. In addition to 
the above-mentioned surface active agents, there can be effectively 
employed other materials such as amine acids such as diethanolamine, 
propanolamine, morphole etc., basic compounds such as ammonium hydroxide, 
sodium hydroxide etc. 
These surface tension regulating agents may also be employed as a mixture 
of two of more compounds so as to obtain a desired surface tension in the 
prepared recording medium and within a limit that they do not undesirably 
affect each other or affect other constituents. 
The amount of said surface tension regulating agent is determined suitably 
according to the species thereof, species of other constituents and 
desired recording characteristics, and is generally selected, with respect 
to 1 part by weight of recording medium, in a range from 0.0001 to 0.1 
parts by weight, preferably from 0.001 to 0.01 parts by weight. 
The pH regulating agent is added in a suitable amount to achieve a 
determined pH value thereby improving the chemical stability of prepared 
recording meidum, thus avoiding changes in physical properties and 
avoiding sedimentation a prolonged storage. 
As the pH regulating agent adapted for use in the present invention, there 
can be employed almost any materials capable of achieving a desired pH 
value without giving undesirable effects to the prepared liquid recording 
medium. 
Examples of such pH regulating agent are lower alkanolamine monovalent 
hydroxides such as alkali metal hydroxide, ammonium hydroxyde etc. 
In case the recording is achieved by charging the droplets of liquid 
recording medium, the resistivity thereof is an important factor for 
determining the charging characteristics. In order that the droplets can 
be charged for achieving a satisfactory recording, the liquid recording 
medium is to be provided with a resistivity generally within a range of 
10.sup.-3 to 10.sup.11 .OMEGA.cm. 
Examples of resistivity regulating agent to be added in a suitable amount 
to achieve the resistivity as explained above in the liquid recording 
medium are inorganic salts such as ammonium chloride, sodium chloride, 
potassium chloride etc., water-soluble amines such as triethanolamine 
etc., and quaternary ammonium salts. 
In case of recording wherein the droplets are not charged, the resistivity 
of recording medium need not be controlled. 
As a particularly preferable third component, there may be mentioned 
conventional wetting agents. 
Examples of such wetting agent are polyalkylene glycols such as 
polyethylene glycol, polypropylene glycol etc.; alkylene glycols 
containing 2 to 6 carbon atoms such as ethylene glycol, propylene glycol, 
butylene glycol, hexylene glycol etc.; lower alkyl ethers of diethylene 
glycol such as ethyleneglycol methylether, diethyleneglycol methylether, 
diethyleneglycol ethylether etc.; glycerin; lower alkoxy triglycols such 
as methoxy triglycol, ethoxy triglycol etc.; N-vinyl-2-pyrrolidone 
oligomers etc. 
As amount of the wetting agent may be optionally selected so as to impart 
desired characteristics. It is usually 0.01-0.9 parts by weight, 
preferably 0.02-0.8 parts by weight, and more preferably 0.05-0.7 parts by 
weight per one part by weight of the liquid recording medium. 
The above-mentioned wetting agents may be used, in addition to single use, 
as a mixture of two or more compounds as long as they do not undesirably 
affect each other. 
In addition to the above mentioned various additives, the liquid recording 
medium according to the present invention may contain a water soluble 
polymer such as polyvinyl alcohol and the like for the purpose of 
improving film-shapeability when adhered to a recording member, in 
particular, to obtaining a high film strength. 
In order to produce a liquid recording medium possesing the above mentioned 
various recording characteristics, the liquid recording medium according 
to the present invention may be formulated is such a way that viscosity, 
surface tension, pH, resistivity in case of utilizing charged liquid 
droplets, and specific heat, thermal expansion coefficient and thermal 
conductivity in case of utilizing thermal energy for recording are within 
particular ranges. 
The above mentioned characteristics are closely connected to stability of 
droplet formation, signal responsiveness and fidelity, image density, 
chemical stability, fluidity in the conduit of the device and the like. 
Therefore, it is necessary to take the characteristics into consideration 
upon formulating the liquid recording medium. 
It is recommended to select the values of characteristics as shown in Table 
1 below. However, it is not always necessary to the values for all the 
characteristics mentioned in Table 1, but it is sufficient to select the 
values for some of the characteristics mentioned in Table 1 depending upon 
the requested recording characteristics. 
TABLE 1 
______________________________________ 
Physical More 
property (unit) 
Usually Preferably preferably 
______________________________________ 
Viscosity at 20.degree. C. 
(Centi poise) 0.3- 30 1- 20 1- 10 
Surface tension 
(dyn/cm) 10- 70 10- 60 15- 50 
pH 6- 12 8- 11 
Resistivity* 
(Ohm .multidot. cm) 
10.sup.-3 - 10.sup.11 
10.sup.-2 - 10.sup.3 
Specific heat 
(J/g .multidot. .degree.K.) 
0.1- 4.0 0.5- 2.5 0.7- 2.0 
Thermal expansion 
coefficient 0.1- 1.8 0.5- 1.5 
(.times. 10.sup.-3 deg.sup.-1) 
Thermal conductivity 
(.times. 10.sup.-3 W/cm .multidot. deg) 
0.1-50 1-10 
______________________________________ 
*The condition is employed when the liquid recording medium is used in th 
charged state.

EXAMPLE 1 
______________________________________ 
Deionized water 68.5 parts by weight 
Glycerine 30 parts by weight 
Dye compound No. 1 
1.5 parts by weight 
______________________________________ 
The above ingredients were charged into a vessel having a stirrer and mixed 
to form a uniform solution avoiding that air got mixed with the solution. 
The resulting solution was filtered through a glass filter having hole 
diameter of 0.5 microns and then degassed for one hour by a rotary pump. 
30 ml of the solution thus degassed was placed in a cassette vessel of 
polyvinyl chloride and sealed (Sample A.sub.1). This cassette vessel was 
set in an ink jet recording device of an demand type having a recording 
head comprising a nozzle having an orifice for ejecting the liquid 
recording medium and surrounded in a closely contacted state with a 
cylindrical piezoelectric element. 
And tests T.sub.1, T.sub.2 and T.sub.3 were conducted under the recording 
conditions in Table 2. There were obtained recorded images of a high 
quality. In particular, non-continuous recording was effected 30 times in 
test T.sub.2 and images recorded from the beginning of recording to the 
end of recording had very good quality. 
TABLE 2 
______________________________________ 
Orifice diameter 60 mictons 
Conditions for driving 
30V, 15 .mu.sec. 
piezoelectric element 
Maximum response 68 KHz 
frequency 
Recording member High grade paper 
(86.5 Kg) 
(supplied by Sanyo 
Kokusaku Pulp Co., 
trade name, Ginkan 
A-Sheet) 
Speed at which the 
recording member 
moves 330cm/sec 
______________________________________ 
Test T.sub.1 : Continuously recording for 36 hours. 
Test T.sub.2 : After conducting a continuous recording for 10 minutes, 
recording was stopped for one hour and this type of non-continuous 
recording was repeated. 
Test T.sub.3 : After a continuous recording for 10 minutes, the recording 
was stopped for 24 hours and then the recording was repeated again. 
EXAMPLE 2 
______________________________________ 
Deionized water 23.5 parts by weight 
Ethylene glycol 75 parts by weight 
Dye compound No. 4 
1.5 parts by weight 
______________________________________ 
These materials were charged into a vessel having a stirrer and mixed to 
form a uniform solution avoiding that air got mixed with the solution. 
The resulting solution was filtered through a glass filter having hole 
diameter of 0.5 microns and then degassed for one hour by a rotary pump. 
30 ml. of the solution thus degassed was placed in a cassette vessel of 
polyvinyl chloride and sealed (Sample A.sub.2). This cassette vessel was 
set in an ink jet recording device of on demand type having a recording 
head comprising a nozzle having an orifice for ejecting the liquid 
recording medium and surrounded in a closely contacted state with a 
cylindrical piezoelectric element. 
And tests T.sub.1, T.sub.2 and T.sub.3 shown in Example 1 were conducted 
under the recording conditions in Table 2. The recording were conducted 
stably as in Example 1. And images recorded from the beginning of 
recording to the end of the recording had very good quality. 
Concentration of dye compound No. 4 was changed in a range from 0.1 to 10% 
by weight and surface tension of each of the liquid recording medium was 
measured and it was found that all the measured surface tension were 48-49 
dyn/cm (25.degree. C.). 
This liquid recording medium was spotted to the above mentioned recording 
member and dried. This spotted image was measured with respect to 
reflection density by an optical densitometer to find 1.10. After this was 
soaked in top water for one hour, the reflection density was 1.04. That 
is, decrease in reflection density was very little. On the contrary, a 
liquid recording medium prepared by following the above mentioned 
procedures except that water-soluble nigrosine (C.I. 50420) was used in 
place of No. 4 dye compound was subjected to the same test as above. The 
original reflection density was 0.98 and after soaked in water, it became 
as low as 0.15. This comparison experiments show that water resistance of 
the liquid recording medium of the present invention is excellent. 
EXAMPLE 3 
Repeating the procedure of Example 1 except that dye compound Nos. 2, 4, 5, 
7, 8, 10, 12, 14, 18, 20, 24, 28, 32, 37, 42, 43, 45, 47, 50, 53, 57, 58, 
60, 62, 63, 65, 70, 73 and 80 were used in place of the dye compound used 
in Example 1, and each of the dye compounds was used in an amount of 0.1, 
0.5, 1, 3, 5, 10 and 12% by weight of the total amount of the liquid 
recording medium, there were prepared liquid recording media. 
The resulting liquid recording media were subjected to tests T.sub.1, 
T.sub.2 and T.sub.3 under the conditions of Table 2 and the recording 
media gave stable and excellent recorded images. 
In test T.sub.2 repeated 30 times, the resulting image quality was constant 
and excellent from the beginning of recording to the end of recording. 
Before conducting the test, surface tension of each of the liquid recording 
media was measured and it was found that these liquid recording media show 
substantially the same value of surface tension. The difference of the 
values was only within the range of error of measurement. This indicates 
that the surface tension is hardly changed by change of concentration of 
the recording agent. Therefore, it is possible to produce a liquid 
recording medium having almost the same liquid physical properties even if 
concentration of the recording agent is varied. Further, the resulting 
liquid recording media prepared by changing concentration of the recording 
agent can have excellent recording characteristics. 
EXAMPLE 4 
With the components and weight ratio as shown in Table 3, liquid recording 
media according to the present invention, A.sub.4a -A.sub.4f, were 
formulated and subjected to test T.sub.1 -T.sub.3 under the conditions of 
Table 2 by using the device as used in Example 1. All of the samples gave 
always stable recording and the resulting recorded images whether they are 
obtained at the beginning or at the end of recording, were sharp and of 
high contrast, high image density and high quality. 
TABLE 3 
______________________________________ 
Dye 
com- Main 
Sample 
pound carrier 
No. No.* liquid* Additives 
______________________________________ 
A.sub.4a 
6(7) Water Polyvinyl alcohol 
(90) (3) 
Methyl cellulose 
A.sub.4b 
13(4.9) Water Polyoxyethylene lauryl 
(85) ether (tradename, 
+ Emulgen 108, supplied 
ethyl by Kao Sekken Co.) 
alcohol (0.1) 
(10) 
A.sub.4c 
29(3.99) Water Polyoxyethylene sorbitan 
(96) tricleate (tradename. 
Tween 85, supplied by 
Kao Sekken Co.) 
(0.01) 
A.sub.4d 
40(2) Water Ethyleneglycol methyl 
(68) ether 
(30) 
A.sub.4e 
55(2) Water Polyvinyl alcohol (3) 
(70) Ethyleneglycol methyl 
ether 
(25) 
A.sub.4f 
75(3) Water Polyvinyl alcohol (2) 
(70) Ethyleneglycol (25) 
______________________________________ 
*Values in parentheses are in % by weight.