CA1315091C - Dyes containing tetramethylammonium cation for ink-jet printing inks - Google Patents
Dyes containing tetramethylammonium cation for ink-jet printing inksInfo
- Publication number
- CA1315091C CA1315091C CA 537301 CA537301A CA1315091C CA 1315091 C CA1315091 C CA 1315091C CA 537301 CA537301 CA 537301 CA 537301 A CA537301 A CA 537301A CA 1315091 C CA1315091 C CA 1315091C
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- Prior art keywords
- dye
- cations
- ink
- vehicle
- tetramethylammonium
- Prior art date
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Classifications
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
- C09D11/00—Inks
- C09D11/30—Inkjet printing inks
- C09D11/32—Inkjet printing inks characterised by colouring agents
- C09D11/328—Inkjet printing inks characterised by colouring agents characterised by dyes
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- Chemical & Material Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Wood Science & Technology (AREA)
- Organic Chemistry (AREA)
- Inks, Pencil-Leads, Or Crayons (AREA)
- Ink Jet Recording Methods And Recording Media Thereof (AREA)
Abstract
DYES CONTAINING TETRAMETHYLAMMONIUM
CATION FOR INK-JET PRINTING INKS
ABSTRACT OF THE DISCLOSURE
Inks used in ink-jet printing comprise a vehicle and a dye. The dye i typically an anionic dye, complexed sodium cations. Several properties of such inks are im-proved by replacing at least about one-fourth of the sodium cations with tetramethylammonium cations.
CATION FOR INK-JET PRINTING INKS
ABSTRACT OF THE DISCLOSURE
Inks used in ink-jet printing comprise a vehicle and a dye. The dye i typically an anionic dye, complexed sodium cations. Several properties of such inks are im-proved by replacing at least about one-fourth of the sodium cations with tetramethylammonium cations.
Description
DYES CONTAINING TETRAMETHYLAMMONIUM
CATIOh FOR INK-JET PRINTINC INKS
Tbe present invention relates to ink compoqitions for ink-jet printers, and, more particularly, to ink compo i-tions iD which the Qolubility of the dye i3 increased byreplacement of sodium cations.
BACKGROUND ART
The use of aqueous-based inks for ink-jet printers is well-known. Such composition~ are relatively inexpensive and easy to prepare; typically, the ink compriseq water and a glycol ether, usually diethylene glycol (commonly referred to as the vehicle), and a dye. Typically, the water and glycol ether are present in generally the same proportion ana the dye, for example, Food Black 2, is present up to about 6~ of the total composition, depending on tbe desired density of the print.
The prior art inks generally use exi~ting commercial dye salt~ (cation plus dye anion) as formea, which are aimply dis~olve~ in the ~ehicle and filtered to prepare the in~. Such dyes, whicb generally contain a plurality of sulfonate anion groups, are designea to form solids in paper or cloth, employing cations guch as sodium cations, which promote precipitation of the dye salt. Consequent-ly, the dyes do not easily remain liquid ln the orifice of an ink-Jet ~rinter.
, : ' .
CATIOh FOR INK-JET PRINTINC INKS
Tbe present invention relates to ink compoqitions for ink-jet printers, and, more particularly, to ink compo i-tions iD which the Qolubility of the dye i3 increased byreplacement of sodium cations.
BACKGROUND ART
The use of aqueous-based inks for ink-jet printers is well-known. Such composition~ are relatively inexpensive and easy to prepare; typically, the ink compriseq water and a glycol ether, usually diethylene glycol (commonly referred to as the vehicle), and a dye. Typically, the water and glycol ether are present in generally the same proportion ana the dye, for example, Food Black 2, is present up to about 6~ of the total composition, depending on tbe desired density of the print.
The prior art inks generally use exi~ting commercial dye salt~ (cation plus dye anion) as formea, which are aimply dis~olve~ in the ~ehicle and filtered to prepare the in~. Such dyes, whicb generally contain a plurality of sulfonate anion groups, are designea to form solids in paper or cloth, employing cations guch as sodium cations, which promote precipitation of the dye salt. Consequent-ly, the dyes do not easily remain liquid ln the orifice of an ink-Jet ~rinter.
, : ' .
2 ~3~509~
Thus, a persistent problem associated with aqueous-based inks is their propensity to crust over a period of time, eventually leading to plugging of the orifice in the printer mechanism from which droplets of ink are expelled in the printing operation. Crusting is the crystallization of the ink around the orifice in the print head, causing partial or full blockage of the orifice, leading to misdirection of the drop (partial blockage) or prevention of drop ejection (full blockage). The crusting problem arises from the evaporation of the water from the ink solvent (vehicle) and the consequent precipitation of the dye salt which has become substantially insoluble as a result of this water loss.
Attempts have been made to solve the crusting problem.
Hygroscopic agents have been added to reduce the rate of water evaporation by their ability to pick up water vapor from the air. Exemplary of such hygroscopic agents are water-soluble polymers, alkanol amines, amides and polyhydric alcohols.
While some improvement has been realizes with these hygroscopic agents, a total solution to the crusting prob-lems has not yet been achieved. Further, apparently no methods are known to prevent crusting of the anionic dyes in neutral to mildly acidic aqueous-based inks (pH 4 to 7).
Attempts are continuing to develop inks in which the dye solubility is increased.
Other approaches include developing new dyes for ink-jet inks. For example, U.S. Patent 4,557,761 discloses a variety of sulfonate-containing dyes with cations such as sodium, potassium, lithium, ammonium and amine salt cat-ions.
However, as shown above, dyes with sodium cations have ~, certain deficiencies. Dyes with potassium cations also suffer from certain deficiencies, notably evidencing crusting. Dyes with ammonium cations, on the other hand, ' ~
.
Thus, a persistent problem associated with aqueous-based inks is their propensity to crust over a period of time, eventually leading to plugging of the orifice in the printer mechanism from which droplets of ink are expelled in the printing operation. Crusting is the crystallization of the ink around the orifice in the print head, causing partial or full blockage of the orifice, leading to misdirection of the drop (partial blockage) or prevention of drop ejection (full blockage). The crusting problem arises from the evaporation of the water from the ink solvent (vehicle) and the consequent precipitation of the dye salt which has become substantially insoluble as a result of this water loss.
Attempts have been made to solve the crusting problem.
Hygroscopic agents have been added to reduce the rate of water evaporation by their ability to pick up water vapor from the air. Exemplary of such hygroscopic agents are water-soluble polymers, alkanol amines, amides and polyhydric alcohols.
While some improvement has been realizes with these hygroscopic agents, a total solution to the crusting prob-lems has not yet been achieved. Further, apparently no methods are known to prevent crusting of the anionic dyes in neutral to mildly acidic aqueous-based inks (pH 4 to 7).
Attempts are continuing to develop inks in which the dye solubility is increased.
Other approaches include developing new dyes for ink-jet inks. For example, U.S. Patent 4,557,761 discloses a variety of sulfonate-containing dyes with cations such as sodium, potassium, lithium, ammonium and amine salt cat-ions.
However, as shown above, dyes with sodium cations have ~, certain deficiencies. Dyes with potassium cations also suffer from certain deficiencies, notably evidencing crusting. Dyes with ammonium cations, on the other hand, ' ~
.
3 131509~
are not stable. Thus, the cations listed in U.S. Patent 4,557,761 cannot be considered to be equivalent.
Finally, many cations are not suitable for dyes employed in inks used in thermal ink-jet printing. In this instance, a problem known as kogation may occur.
Kogation is a coined term, unique to thermal ink-jet printing, and describes the extent of decomposition of the ink on the resistors of thermal ink-jet printers as a consequence of heating. Such heating is used to form droplets of ink, which are propelled toward the substrate.
While sodium-containing dyes evidence crusting problems, they also evidence superior kogation properties. Dyes containing other cations which evidence improved crusting also often evidence poor kogation.
DISCLOSURE OF INVENTION
Accordingly, it is an object of an aspect of the present invention to provide an ink composition 2~ evidencing increased dye solubility in the vehicle.
It is an object of an aspect of this invention to provide an ink in which the crusting problem is minimal.
It is an object of an aspect of this invention to provide an aqueous-based ink for ink-jet printers in which kogation of the dye in the ink solvent (vehicle) is not adversely affected by partial or total replacement of sodium cations.
It is an object of an aspect of this invention to provide an aqueous-based ink for ink-jet printers in which the solubility of anionic dyes in mildly acidic to mildly basic media is increased.
Various aspects of the invention are as follows:
An ink composition suitable for use in ink-jet printers comprising:
(a) a vehicle comprising about 5 to 95% water and the balance at least one glycol ether;
(b) a dye having at least one negatively charged functional group per molecule, present in an amount up to about 0.1 Molar of the vehicle composition, said dye , 3a having a plurality of anionic sites, originally complexed with sodium cations, at least a portion of said sodium cations being replaced with tetramethylammonium cations, said portion being in an effective amount to reduce crusting of said ink without affecting kogation.
A process for increasing dye solubility without adversely affecting kogation in an ink comprising a vehicle and a dye, said vehicle comprising about 5 to 95%
water and the balance at least one member selected from the group consisting of glycols and glycol ethers and said dye having at least one negatively charged functional group per molecule, said dye being present in an amount up to about 0.1 Molar of the vehicle composition and having a plurality of anionic sites, originally complexed with sodium cations, said process comprising replacing at least a portion of said sodium cations with tetramethylammonium cations.
By way of added explanation, the ink composition of the invention comprises a vehicle and an anionic dye containing a plurality of sodium cations associated with each dye molecule, at least about one-fourth of the ~odium cations being replaced by tetramethylammonium ~' ~IMA) cations.
: :~
, ,~
- ' ,...... ,' ~ B~
~ ~ :
~ ' , ~ 1315'091 1 The dye containing TMA catlon~ evidence~ increa3ea solubillty and reduced crusting ln inks commonly used in ink-~et printing, yet ~how~ no tendency toward kogation.
~EST MODE(S) FOR CARRYING OUT THE INVENTION
The ink compositions of the invention comprise an aqueous-based vehicle and a dye. The pH of the ink may be maintained in the both the acidic and ba~ic regions, ranging from about 4 to 9.
! The ~ehicle of the ink comprises water and at least one of the glycols and glycol ethers commonly employed in the ink~ used in ink-Jet printing. Example~ of suoh compound~ include diethylene glycol, triethylene glycol and polyethylene glycols. The water i9 pre~ent in an amount ranging from about 5 to 95~, the balance being at least one of the glycols and/or glycol etherq. Prefer-ably, the vehicle comprises about 50~ water and the bal-ance a glycol ether ~uch as diethylene glycol.
To the vehicle is added up to about 0.1 Molar of a dye, preferably an anionic dye. The amount of the dye added is a function of choi¢e, being largely dependent upon the solubility of the dye in the vehicle (which limits the upper range of dye ¢oncentration) and the ; 25 aesired density of the print achieved with the ink (which limits the lower range of dye ¢oncentration - typically about 0.005 Molar). Preferably, the concentration of the dye in the ink composition is about 0.065 Molar. For Food Bla¢k 2, a dye commonly used in ink-Jet inks, the corre-sponding con¢entration in wt~ ranges from about 0.5 to 10~, with aDout 6~ being preferred.
The dye to which the invention is suitably applied is an or~anic molecule having at least one negatively charged functional ~roup per molecule. Since sulfonate (S03-) ; groups are espeoially Denefitted from the practice of the invention, dyes having such group~ are preferrea. A don-':~
.
: , .
.
I ~` 5 13~ ~091 1 venlent dye ln this regard is Food Black 2 (FB2), which has a mixture of two, three and four sulfonate groups per molecule. (The effective value ls about 3.2 sulfonate groups per molecule for commercially available F82.) The negative charge of the 3ulfonate group i~ most commonly balancea by the presence of positively charged sodium (~a'). Other anionic dyes may also be suitably employed, since, aQ will be discussed in further detail below, the solubility of the anionic dyes is increased in acidic media by employing the teachings of the invention.
Example~ of other anionic dyes which may be employed in the ink composition disclosed herein include Direct Red 9, Direct Red 227, Acid Yellow 23, Direct Yellow 86, Acid Blue 9, Direct Blue 86, Direct Blue 199 and Acid Blue 185.
In accordance with the invention, an ink composition suitable for use in ink-jet printers i9 provided, compris-ing:
- ~ (a) a vehicle comprising about 5 to 95~ water and the balance at least one glycol ether; and (D) a dye having at lea~t one negatively charged functional group per molecule, present ln an amount up to 0.1 Molar of the ink composition, the dye haYing a plural-ity of anionic slte~, orlglnally complexed with sodium cations, at least a portion of the sodium cations being replaced wlth tetramethylammonium cations.
The presence of tetramethylammonium (T~A) cations increase-~ the solubility of the dye in the vehicle without adversely affecting ko~ation. The presence of TMA alqo reduces crusting of the ink around the oriflces of the ~0 ink-~et printer, sucn crusting being caused by evaporation of the water in the vehicle of the ink upon exposure to air, The partial or complete replacement of sodium cations by TMA cations may be accomplished by a variety of meth-ods, exemplary of which are ion exchange an~ reverseosmosis. In tne ion exchange reaction, the dye with : 1 ,,-' ', ':~' !
:" , : ' 6 131~091 1 ~odium cations l~ passed through an acid-loaaed lon ex-1 change resin. The sodium catlons are replaced wlth hydro-¦ gen cations. The lon-exchanged dye l~ then reacted wltn tetramethylammonium hydroxide (TMA+ OH-). The TMA cations replace the hydrogen cations, whlch react with the hydrox-ide anions to form water.
Preferably, at least acout one-fourth of the sodium cations muQt be replaced by the TMA cations ln order to obtain the benefits disclosed herein. However, most pref-erably, at least about one-half of the sodium cations are replaced in order to obtain the best combination of pro-perties.
It has been 4bserved that the more the TMA replace-ment for sodlum, the better the color density achievable.
Further, low temperature start-up (an indication Or the ability for the first drop of ink to fire when the printer has been idle for a period of t$me) is improved.
The presence of T~A permits a concentration of dye up to 0.100 Molar. Above thi~ level, the viscosity of the inK is too high. For practical purposes and economy, the maxlmum amount of TMA-dye i9 about 0.065 Molar; above this level, the color den~ity is at its maximum ana increases no further.
A ~light exces~ of TMA (about 5 to 10~) may be pre~-ent ln the ink to provlde the manufacturer wlth a marginwhen maklng the TMA form of the dye.
INDUSTRIAL APPLICA~ILITY
. ~
The TMA-substituted dyes provided in accordance with the invention flnd u~e in inks u~ed in ink-jet printing, particularly in thermal ink-jet printing.
..
, ' .
.. . .
, - ., ,. -- ..... .
, ~` 1315091 1 EXAhPLES
A ~erles of dyes were preparea, employing Food Black 2, which originally had all anionic sites complexed witn sodium cations. The vehicle compri~ed diethylene glycol (DEG) and water in the concentration~ given below. In the inks listed in Ta~le I below, the dye concentration is given in terms of millimolarity. Comparisons are made with ~ubstitutions of sodium cations ranging from no re-placement to partial replacement to full replacement bytetramethylammonium (TMA) cation. For comparison, full i replacement by ammonium cation (NH4) and potassium (K) are also given.
15- ---------------__________ _____~________________ TABLE I.
Example Cation S Na Replacement Concentration, mM
1 Na _- 39 TM~ 100 65 __________________________________________________________ The properties of solubillty, crustin~, room tempera-ture (RT) and low temperature (LT) start-up, kogation, storage and change in color den~ity (delta E) are listed ; in Table II below. The solubility is shown for two vehi-cle concentrations: 50/50 DEG/H20 and 90/10 DEG/H20.
Start-up is measured for pens exposea for a period of tlme to a temperature Lroom (RT) or 10C (LT)] at low relative humiaity (RH) to determine whether water loss ha~
, . ~ .
:,' .
. , .
1 been su~ficient to cause a signiflcant decrease ln the quallty of drop eJections, Storage referq to the stability of chemical and phy~-ical properties during ~torage.
Delta E i9 a meaqure of color denqity. If the color i~ measurea in CIELAB coordinateq, then E i9 given by E = L(L2 - L1)2, (a2 - a1)2 1 (b2 - b1)2]1/2 where L, a and b are the coordinate~ of reference in CIELAB space and 1 refer~ to the reference and 2 refers to the sample. De}ta E = E - Eo~ where Eo is for the lowest concentration ~tandard and E is for the sample.
- -----_________________________________________ TABLE II.
Exam- Solubility Cru~t- Start-up Koga- Storage Delta ple 50/50 90/10 ing RT LT tion E E G G G E
6 ' P
______________________________________________O___________ The foregolng relative observations are based on the following scale, with the definitions of each observation for each property as follows:
E ~ Excellent G = ~ooa F = Fair P = Poor.
:
.
- . .
9 131~091 1 A perusal of Table II above shows that solublllty lq enhanc~d ln both 50/50 DEC/H20 and 90/10 DEG/H20 for replacement of sodium cationq by tetramethylammonium cat-ions. Further, kogation is not adversely affected by such replacement. Other properties of the inks containing TMA-replaced dyes, ~uch aq crusting, start-up, ~torage and print quality are 3een to be at lea~t equlvalent to those of ink~ containing ~odium cation~. Finally, compari~on with replacement by other cations (K and NH4) point~ up the improvement achievea with the sub~tition of tetrameth-; ylammonium for ~odium.
Thu~, an ink compoqition for ink-jet printers ha~
been provided. The ink comprises an anionic dye in which at least a portion of the a~sociated ~odium cations are replaced with tetramethylammonium cations. Various changes and modification~ will be readily apparent to those of ordinary qkill in the art, and all ~uch changes and modifications are con~idered to be within the scope of this invention.
,''';
,, ~, , ..
- .
are not stable. Thus, the cations listed in U.S. Patent 4,557,761 cannot be considered to be equivalent.
Finally, many cations are not suitable for dyes employed in inks used in thermal ink-jet printing. In this instance, a problem known as kogation may occur.
Kogation is a coined term, unique to thermal ink-jet printing, and describes the extent of decomposition of the ink on the resistors of thermal ink-jet printers as a consequence of heating. Such heating is used to form droplets of ink, which are propelled toward the substrate.
While sodium-containing dyes evidence crusting problems, they also evidence superior kogation properties. Dyes containing other cations which evidence improved crusting also often evidence poor kogation.
DISCLOSURE OF INVENTION
Accordingly, it is an object of an aspect of the present invention to provide an ink composition 2~ evidencing increased dye solubility in the vehicle.
It is an object of an aspect of this invention to provide an ink in which the crusting problem is minimal.
It is an object of an aspect of this invention to provide an aqueous-based ink for ink-jet printers in which kogation of the dye in the ink solvent (vehicle) is not adversely affected by partial or total replacement of sodium cations.
It is an object of an aspect of this invention to provide an aqueous-based ink for ink-jet printers in which the solubility of anionic dyes in mildly acidic to mildly basic media is increased.
Various aspects of the invention are as follows:
An ink composition suitable for use in ink-jet printers comprising:
(a) a vehicle comprising about 5 to 95% water and the balance at least one glycol ether;
(b) a dye having at least one negatively charged functional group per molecule, present in an amount up to about 0.1 Molar of the vehicle composition, said dye , 3a having a plurality of anionic sites, originally complexed with sodium cations, at least a portion of said sodium cations being replaced with tetramethylammonium cations, said portion being in an effective amount to reduce crusting of said ink without affecting kogation.
A process for increasing dye solubility without adversely affecting kogation in an ink comprising a vehicle and a dye, said vehicle comprising about 5 to 95%
water and the balance at least one member selected from the group consisting of glycols and glycol ethers and said dye having at least one negatively charged functional group per molecule, said dye being present in an amount up to about 0.1 Molar of the vehicle composition and having a plurality of anionic sites, originally complexed with sodium cations, said process comprising replacing at least a portion of said sodium cations with tetramethylammonium cations.
By way of added explanation, the ink composition of the invention comprises a vehicle and an anionic dye containing a plurality of sodium cations associated with each dye molecule, at least about one-fourth of the ~odium cations being replaced by tetramethylammonium ~' ~IMA) cations.
: :~
, ,~
- ' ,...... ,' ~ B~
~ ~ :
~ ' , ~ 1315'091 1 The dye containing TMA catlon~ evidence~ increa3ea solubillty and reduced crusting ln inks commonly used in ink-~et printing, yet ~how~ no tendency toward kogation.
~EST MODE(S) FOR CARRYING OUT THE INVENTION
The ink compositions of the invention comprise an aqueous-based vehicle and a dye. The pH of the ink may be maintained in the both the acidic and ba~ic regions, ranging from about 4 to 9.
! The ~ehicle of the ink comprises water and at least one of the glycols and glycol ethers commonly employed in the ink~ used in ink-Jet printing. Example~ of suoh compound~ include diethylene glycol, triethylene glycol and polyethylene glycols. The water i9 pre~ent in an amount ranging from about 5 to 95~, the balance being at least one of the glycols and/or glycol etherq. Prefer-ably, the vehicle comprises about 50~ water and the bal-ance a glycol ether ~uch as diethylene glycol.
To the vehicle is added up to about 0.1 Molar of a dye, preferably an anionic dye. The amount of the dye added is a function of choi¢e, being largely dependent upon the solubility of the dye in the vehicle (which limits the upper range of dye ¢oncentration) and the ; 25 aesired density of the print achieved with the ink (which limits the lower range of dye ¢oncentration - typically about 0.005 Molar). Preferably, the concentration of the dye in the ink composition is about 0.065 Molar. For Food Bla¢k 2, a dye commonly used in ink-Jet inks, the corre-sponding con¢entration in wt~ ranges from about 0.5 to 10~, with aDout 6~ being preferred.
The dye to which the invention is suitably applied is an or~anic molecule having at least one negatively charged functional ~roup per molecule. Since sulfonate (S03-) ; groups are espeoially Denefitted from the practice of the invention, dyes having such group~ are preferrea. A don-':~
.
: , .
.
I ~` 5 13~ ~091 1 venlent dye ln this regard is Food Black 2 (FB2), which has a mixture of two, three and four sulfonate groups per molecule. (The effective value ls about 3.2 sulfonate groups per molecule for commercially available F82.) The negative charge of the 3ulfonate group i~ most commonly balancea by the presence of positively charged sodium (~a'). Other anionic dyes may also be suitably employed, since, aQ will be discussed in further detail below, the solubility of the anionic dyes is increased in acidic media by employing the teachings of the invention.
Example~ of other anionic dyes which may be employed in the ink composition disclosed herein include Direct Red 9, Direct Red 227, Acid Yellow 23, Direct Yellow 86, Acid Blue 9, Direct Blue 86, Direct Blue 199 and Acid Blue 185.
In accordance with the invention, an ink composition suitable for use in ink-jet printers i9 provided, compris-ing:
- ~ (a) a vehicle comprising about 5 to 95~ water and the balance at least one glycol ether; and (D) a dye having at lea~t one negatively charged functional group per molecule, present ln an amount up to 0.1 Molar of the ink composition, the dye haYing a plural-ity of anionic slte~, orlglnally complexed with sodium cations, at least a portion of the sodium cations being replaced wlth tetramethylammonium cations.
The presence of tetramethylammonium (T~A) cations increase-~ the solubility of the dye in the vehicle without adversely affecting ko~ation. The presence of TMA alqo reduces crusting of the ink around the oriflces of the ~0 ink-~et printer, sucn crusting being caused by evaporation of the water in the vehicle of the ink upon exposure to air, The partial or complete replacement of sodium cations by TMA cations may be accomplished by a variety of meth-ods, exemplary of which are ion exchange an~ reverseosmosis. In tne ion exchange reaction, the dye with : 1 ,,-' ', ':~' !
:" , : ' 6 131~091 1 ~odium cations l~ passed through an acid-loaaed lon ex-1 change resin. The sodium catlons are replaced wlth hydro-¦ gen cations. The lon-exchanged dye l~ then reacted wltn tetramethylammonium hydroxide (TMA+ OH-). The TMA cations replace the hydrogen cations, whlch react with the hydrox-ide anions to form water.
Preferably, at least acout one-fourth of the sodium cations muQt be replaced by the TMA cations ln order to obtain the benefits disclosed herein. However, most pref-erably, at least about one-half of the sodium cations are replaced in order to obtain the best combination of pro-perties.
It has been 4bserved that the more the TMA replace-ment for sodlum, the better the color density achievable.
Further, low temperature start-up (an indication Or the ability for the first drop of ink to fire when the printer has been idle for a period of t$me) is improved.
The presence of T~A permits a concentration of dye up to 0.100 Molar. Above thi~ level, the viscosity of the inK is too high. For practical purposes and economy, the maxlmum amount of TMA-dye i9 about 0.065 Molar; above this level, the color den~ity is at its maximum ana increases no further.
A ~light exces~ of TMA (about 5 to 10~) may be pre~-ent ln the ink to provlde the manufacturer wlth a marginwhen maklng the TMA form of the dye.
INDUSTRIAL APPLICA~ILITY
. ~
The TMA-substituted dyes provided in accordance with the invention flnd u~e in inks u~ed in ink-jet printing, particularly in thermal ink-jet printing.
..
, ' .
.. . .
, - ., ,. -- ..... .
, ~` 1315091 1 EXAhPLES
A ~erles of dyes were preparea, employing Food Black 2, which originally had all anionic sites complexed witn sodium cations. The vehicle compri~ed diethylene glycol (DEG) and water in the concentration~ given below. In the inks listed in Ta~le I below, the dye concentration is given in terms of millimolarity. Comparisons are made with ~ubstitutions of sodium cations ranging from no re-placement to partial replacement to full replacement bytetramethylammonium (TMA) cation. For comparison, full i replacement by ammonium cation (NH4) and potassium (K) are also given.
15- ---------------__________ _____~________________ TABLE I.
Example Cation S Na Replacement Concentration, mM
1 Na _- 39 TM~ 100 65 __________________________________________________________ The properties of solubillty, crustin~, room tempera-ture (RT) and low temperature (LT) start-up, kogation, storage and change in color den~ity (delta E) are listed ; in Table II below. The solubility is shown for two vehi-cle concentrations: 50/50 DEG/H20 and 90/10 DEG/H20.
Start-up is measured for pens exposea for a period of tlme to a temperature Lroom (RT) or 10C (LT)] at low relative humiaity (RH) to determine whether water loss ha~
, . ~ .
:,' .
. , .
1 been su~ficient to cause a signiflcant decrease ln the quallty of drop eJections, Storage referq to the stability of chemical and phy~-ical properties during ~torage.
Delta E i9 a meaqure of color denqity. If the color i~ measurea in CIELAB coordinateq, then E i9 given by E = L(L2 - L1)2, (a2 - a1)2 1 (b2 - b1)2]1/2 where L, a and b are the coordinate~ of reference in CIELAB space and 1 refer~ to the reference and 2 refers to the sample. De}ta E = E - Eo~ where Eo is for the lowest concentration ~tandard and E is for the sample.
- -----_________________________________________ TABLE II.
Exam- Solubility Cru~t- Start-up Koga- Storage Delta ple 50/50 90/10 ing RT LT tion E E G G G E
6 ' P
______________________________________________O___________ The foregolng relative observations are based on the following scale, with the definitions of each observation for each property as follows:
E ~ Excellent G = ~ooa F = Fair P = Poor.
:
.
- . .
9 131~091 1 A perusal of Table II above shows that solublllty lq enhanc~d ln both 50/50 DEC/H20 and 90/10 DEG/H20 for replacement of sodium cationq by tetramethylammonium cat-ions. Further, kogation is not adversely affected by such replacement. Other properties of the inks containing TMA-replaced dyes, ~uch aq crusting, start-up, ~torage and print quality are 3een to be at lea~t equlvalent to those of ink~ containing ~odium cation~. Finally, compari~on with replacement by other cations (K and NH4) point~ up the improvement achievea with the sub~tition of tetrameth-; ylammonium for ~odium.
Thu~, an ink compoqition for ink-jet printers ha~
been provided. The ink comprises an anionic dye in which at least a portion of the a~sociated ~odium cations are replaced with tetramethylammonium cations. Various changes and modification~ will be readily apparent to those of ordinary qkill in the art, and all ~uch changes and modifications are con~idered to be within the scope of this invention.
,''';
,, ~, , ..
- .
Claims (17)
1. An ink composition suitable for use in ink-jet printers comprising:
(a) a vehicle comprising about 5 to 95% water and the balance at least one glycol ether;
(b) a dye having at least one negatively charged functional group per molecule, present in an amount up to about 0.1 Molar of the vehicle composition, said dye having a plurality of anionic sites, originally complexed with sodium cations, at least a portion of said sodium cations being replaced with tetramethylammonium cations, said portion being in an effective amount to reduce crusting of said ink without affecting kogation.
(a) a vehicle comprising about 5 to 95% water and the balance at least one glycol ether;
(b) a dye having at least one negatively charged functional group per molecule, present in an amount up to about 0.1 Molar of the vehicle composition, said dye having a plurality of anionic sites, originally complexed with sodium cations, at least a portion of said sodium cations being replaced with tetramethylammonium cations, said portion being in an effective amount to reduce crusting of said ink without affecting kogation.
2. The ink composition of Claim 1 wherein said glycol ether is selected from the group consisting of diethylene glycol, triethylene glycol and polyethylene glycols.
3. The ink composition of Claim 2 wherein said vehicle consists essentially of diethylene glycol, present in an amount of about 50%, and the balance water.
4. The ink composition of Claim 1 wherein said dye includes at least one sulfonate functional group per molecule.
5. The ink composition of Claim 4 wherein said dye is one selected from the group consisting of Food Black 2, Direct Red 9, Direct Red 227, Acid Yellow 23, Direct Yellow 86, Acid Blue 9, Direct Blue 86, Direct Blue 199 and Acid Blue 185.
6. The ink composition of Claim 5 wherein said dye comprises Food Black 2.
7. The ink composition of Claim 1 wherein at least about one-fourth of said sodium cations on said dye are replaced with tetramethylammonium cations.
8. The ink composition of Claim 7 wherein at least about one-half of said sodium cations on said dye are replaced with tetramethylammonium cations.
9. A process for increasing dye solubility without adversely affecting kogation in an ink comprising a vehicle and a dye, said vehicle comprising about 5 to 95%
water and the balance at least one member selected from the group consisting of glycols and glycol ethers and said dye having at least one negatively charged functional group per molecule, said dye being present in an amount up to about 0.1 Molar of the vehicle composition and having a plurality of anionic sites, originally complexed with sodium cations, said process comprising replacing at least a portion of said sodium cations with tetramethylammonium cations.
water and the balance at least one member selected from the group consisting of glycols and glycol ethers and said dye having at least one negatively charged functional group per molecule, said dye being present in an amount up to about 0.1 Molar of the vehicle composition and having a plurality of anionic sites, originally complexed with sodium cations, said process comprising replacing at least a portion of said sodium cations with tetramethylammonium cations.
10. The process of Claim 9 wherein said at least member is selected from the group consisting of diethylene glycol, triethylene glycol and polyethylene glycols.
11. The process of Claim 10 wherein said vehicle consists essentially of diethylene glycol, present in an amount of about 50%, and the balance water.
12. The process of Claim 9 wherein said dye includes at least one sulfonate functional group per molecule.
13. The process of Claim 12 wherein said dye is one selected from the group consisting of Food Black 2, Direct Red 9, Direct Red 227, Acid Yellow 23, Direct Yellow 86, Acid Blue 9, Direct Blue 86, Direct Blue 199 and Acid Blue 185.
14. The process of Claim 13 wherein said dye comprises Food Black 2.
15. The process of Claim 9 wherein at least about one-fourth of said sodium cations on said dye are replaced with tetramethylammonium cations.
16. The process of Claim 15 wherein at least about one-half of said sodium cations on said dye are replaced with tetramethylammonium cations.
17. The process of Claim 9 wherein said dye is passed through an acid-loaded ion exchange resin to replace at least a portion of said sodium cations with hydrogen cations and said ion-exchanged dye is subsequently reacted with tetramethylammonium hydroxide to replace said hydrogen cations with tetramethylammonium cations.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US900,953 | 1978-04-28 | ||
| US90095386A | 1986-08-27 | 1986-08-27 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1315091C true CA1315091C (en) | 1993-03-30 |
Family
ID=25413355
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 537301 Expired - Fee Related CA1315091C (en) | 1986-08-27 | 1987-05-15 | Dyes containing tetramethylammonium cation for ink-jet printing inks |
Country Status (2)
| Country | Link |
|---|---|
| JP (1) | JPS6366270A (en) |
| CA (1) | CA1315091C (en) |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS53123208A (en) * | 1977-04-02 | 1978-10-27 | Dainippon Toryo Kk | Aqueous marking ink |
| JPS62149770A (en) * | 1985-12-25 | 1987-07-03 | Ricoh Co Ltd | Water based ink composition |
| JPS62197475A (en) * | 1986-02-26 | 1987-09-01 | Ricoh Co Ltd | Water-based ink composition |
| JPS62232472A (en) * | 1986-04-02 | 1987-10-12 | Ricoh Co Ltd | Water based ink composition |
-
1987
- 1987-05-15 CA CA 537301 patent/CA1315091C/en not_active Expired - Fee Related
- 1987-08-26 JP JP62212653A patent/JPS6366270A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| JPS6366270A (en) | 1988-03-24 |
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| Date | Code | Title | Description |
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| MKLA | Lapsed |