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United States Patent |
6,162,289
|
Tatum
,   et al.
|
December 19, 2000
|
Ink jet printer dispersion inks
Abstract
Ink jet printer dispersion inks are provided which contain a dispersant
having basic or acid groups and a non-destabilizing amount of a
neutralizer for said groups. The inks exhibit improved non-wetting
characteristics leading to lengthening of the duration of periods of
continuous printing that can be achieved before cleaning or replacement of
the nozzle plate of the ink jet print head is required.
Inventors:
|
Tatum; John Philip (Isleham, GB);
Woods; Jill (March, GB);
Griffin; Mary Catherine Ambrose (Cambridge, GB)
|
Assignee:
|
Xaar Technology Limited (Cambridge, GB)
|
Appl. No.:
|
052502 |
Filed:
|
March 31, 1998 |
Foreign Application Priority Data
Intern'l Class: |
C09D 011/00 |
Field of Search: |
106/31.13,31.6
|
References Cited
U.S. Patent Documents
4057436 | Nov., 1977 | Davies et al. | 106/504.
|
4155767 | May., 1979 | Specht et al. | 106/31.
|
4210566 | Jul., 1980 | Murray | 106/31.
|
5034508 | Jul., 1991 | Nishizaki et al. | 528/408.
|
5272201 | Dec., 1993 | Ma et al. | 524/505.
|
5352729 | Oct., 1994 | Birkhofer et al. | 524/549.
|
5372747 | Dec., 1994 | Uhrig et al. | 106/499.
|
Primary Examiner: Bell; Mark L.
Assistant Examiner: Faison; Veronica F.
Attorney, Agent or Firm: Marshall, O'Toole, Gerstein, Murray & Borun
Claims
We claim:
1. An ink jet printer dispersion ink containing a dispersant having either
basic or acid groups and a non-destabilising and receding meniscus
velocity (RMV)-improving amount of a neutraliser for said groups.
2. An ink as claimed in claim 1 in which the diluent is non-aqueous or
substantially non-aqueous.
3. An ink as claimed in claim 1 wherein the dispersant is present in an
amount of from 100% to 200% of the amount which yields an ink with minimum
viscosity, the nature and amounts of the other components of the ink being
unchanged.
4. An ink as claimed in claim 1, wherein the neutraliser is present in an
amount which is from 25% to 100% of the amount which yields ink with the
maximum receding meniscus velocity, the nature and amounts of the other
components of the ink being unchanged.
5. An ink as claimed in claim 1 wherein the dispersant is a polyamine and
the neutraliser is selected from Lewis acids, inorganic acids, organic
acids and phenols.
6. An ink as claimed in claim 5 wherein the neutraliser is selected from
alkyl partial esters of acids of phosphorus, phenols and polymeric
compounds containing phenolic groups.
7. An ink as claimed in claim 1 wherein it comprises a dispersant, a
pigment and a diluent and wherein the diluent has a polar solubility
parameter not greater than 7 MPa.sup.1/2.
8. An ink as claimed in claim 7 wherein the diluent comprises a mixture of
non-polar organic solvent and a minor amount, by weight, of a polar
organic solvent.
9. An ink as claimed in claim 1 wherein it comprises a dispersant, a
pigment and a diluent and wherein the diluent has a boiling point of at
least 200.degree. C., a viscosity not greater than 15 mPas and a freezing
point of not more than 7.degree. C.
10. A method of producing an ink jet printer dispersion ink as claimed in
claim 1, said method including the steps of
(a) forming a stable dispersion comprising colourant, a dispersant having
either basic or acidic groups, and a diluent; and thereafter
(b) adding a non-destabilising and receding meniscus velocity
(RMV)-improving amount of neutraliser for said groups.
11. A method as claimed in claim 10 in which the diluent is non-aqueous or
substantially non-aqueous.
12. A method as claimed in claim 10 wherein the dispersant is present in an
amount of from 100% to 200% of the amount which yields an ink with minimum
viscosity, the nature and amounts of the other components of the ink being
unchanged.
13. A method as claimed in claim 10 wherein the neutraliser is present in
an amount which is from 25% to 100% of the amount which yields ink with
the maximum receding meniscus velocity, the nature and amounts of the
other components of the ink being unchanged.
14. A method as claimed in claim 10 wherein the dispersant is a polyamine
and the neutraliser is selected from Lewis acids, inorganic acids, organic
acids and phenols.
15. A method as claimed in claim 14 wherein the neutraliser is selected
from alkyl partial esters of acids of phosphorus, phenols and polymeric
compounds containing phenolic groups.
16. A method as claimed in claim 10 wherein said ink comprises a
dispersant, a pigment and a diluent and wherein the diluent has a polar
solubility parameter not greater than 7 MPa.sup.1/2.
17. A method as claimed in claim 10 wherein the diluent comprises a mixture
of non-polar organic solvent and a minor amount, by weight, or a polar
organic solvent.
18. A method as claimed in claim 10 wherein said ink comprises a
dispersant, a pigment and a diluent and wherein the diluent has a boiling
point of at least 200.degree. C., a viscosity not greater than 15 mPas and
a freezing point of not more than 7.degree. C.
Description
This invention relates to ink jet printer dispersion inks.
In ink jet printing, a fluid ink is forced under pressure, and sometimes at
elevated temperature, through a very small nozzle in a printing head. In
one kind of printer, known as a "continuous" printer, ink droplets which
are produced continuously are passed through a charging area where
individual droplets receive an electrical charge in response to a signal
and are directed towards a substrate to be printed. The droplets then pass
through an electrical field causing them to be deflected by an amount
which is dependent on the intensity of the charge and the field. Droplets
not required to form print on the substrate are directed to a by-pass
gutter. Inks for use in such printers need to be conductive.
In another kind of printer, known as a "drop-on-demand" (DOD) printer, the
ink droplets are expelled from the nozzle of a print head only when
required during the printing process. Drop-on-demand printers can use an
electrostatically accelerated ink jet or droplet sequences ejected by
pressure impulse actuation. In the latter kind of DOD printer, each drop
of ink is individually ejected from a nozzle by means of pressure pulses
induced e.g. by use of a piezo-electric actuator acting on the ink in the
channel supplying the nozzle or by generation of a vapour bubble in
response to a thermal pulse.
In general, there are two classes of ink for use in such ink-jet printers,
namely solvent inks in which the colourant, usually a dye, is dissolved in
a solvent, and dispersion inks wherein the colourant, i.e. pigment, is
dispersed in a diluent. The present invention is concerned with the latter
class.
One particular problem that is encountered with continuous printing with an
ink jet printer is that a small amount of the tail of the droplet being
ejected tends to separate from the droplet and collect on the surface of
that part of the area of the nozzle plate immediately surrounding the
nozzle. In general, provided the surface energy of the plate is
sufficiently low this ink deposit will simply recede into the nozzle and
be ejected as part of a later droplet; however as the frequency of droplet
ejection is increased, there is less opportunity for the ink to recede
before ejection of the next droplet and a pool of ink commences to form on
the surface of the nozzle plate the size of which can increase until it
reaches a level at which it, or airborne dust or other contaminant which
is attracted to the thus- wetted nozzle plate, interferes with droplet
ejection and prevents reliable operation of the printer. The problem is
further exacerbated by the trend towards increasing the number of nozzles
per unit area of the nozzle plate and thus reducing internozzle spacing.
Moreover any residue of ink on the nozzle plate surface can be
disadvantageous where different coloured inks are being used because of
the risk of contaminating one colour with another. It thus becomes
necessary from time to time to clean the face of the nozzle plate, e.g. by
wiping. This is undesirable because it means interrupting the printing run
and because repeated wiping of the nozzle plate face can damage its
surface.
Improved treatment of the relevant part of the surface of the nozzle plate
of the printhead to reduce its surface energy, e.g. by provision of a
so-called non-wetting coating e.g. of fluorocarbon or fluorosilane, can
substantially reduce the problem and increase the duration of acceptable
operation before cleaning or replacement of the nozzle plate is required;
however, with commercial demands for ever increasing reliability and
reduced down time for servicing, still further improvement would be
welcomed and therefore the applicants have addressed not only the nature
of the surface of the printhead nozzle plate but also the nature of the
ink.
One class of inks which has proved particularly attractive for their print
quality and performance is dispersion inks. Of particular interest are
those which employ an ionic dispersant, more preferably a macromolecular
polyionic dispersant, to improve the stability of the disperse phase.
Ionic dispersants, as the term is used herein, describes dispersants
comprising molecules having acid or basic groups, and macromolecular
polyionic dispersants, as the term is used herein, comprise large
molecules, e.g. oligomers or polymers, sometimes of imprecisely known size
or structure, carrying a large number of either acidic or basic groups,
eg. in the form of repeating units having acid or basic groups in the
polymeric or oligomeric structure.
Ink jet printers employing dispersion inks based on ionic dispersants can
produce excellent print reliability for substantial periods; however, a
still further improvement in their performance, and in particular the
duration of the periods of continuous printing that can be achieved before
cleaning, eg. wiping, or replacement of the nozzle plate of the ink jet
print head, would be desirable.
We have now found in accordance with the present invention that such an
improvement may be obtained by including in the ink a non-destabilising
amount of a compound (hereinafter referred to as a neutraliser) containing
at least one group capable of neutralising the acidic or basic groups,
respectively, of the dispersant. Moreover, when using the ink in an ink
jet printer head of a drop-on-demand printer, greater negative ink supply
pressure can be withstood without ingesting air and greater short term
positive pressure surges, eg. due to acceleration or deceleration of the
print head on ashuttle, can be tolerated without flooding.
As the amount of dispersant included in a dispersion ink is increased from
zero, we have found from earlier work that the viscosity of the ink
decreases until it reaches a minimum and then commences to increase again
and that the optimum amount of dispersant from the point of view of
overall properties of ink is approximately that which results in the
minimum viscosity or slightly in excess thereof; e.g. from 100% to 200% of
that amount, and more generally from 100% to 150% of that amount. This
generally equates to about 0.1 to 1, more usually about 0.1 to 0.7 part,
per part of pigment, by weight. While not wishing to be bound by this
theory, it is believed that at this concentration of dispersant, the
acidic or basic groups provided by the dispersant are in excess of those
required to stabilise the dispersion of pigment in the diluent and that
the excess increases the ability of the ink to wet a surface. In any
event, it has been found that adding a small proportion of a compound
containing a moiety or moieties capable of neutralising the acidic or
basic groups of the dispersant increases the speed with which the ink
deposit left by the droplet on the surface of the nozzle plate recedes
into the nozzle and thus reduces the risk of forming a pool on the surface
of the nozzle plate. A direct indication of this property can be obtained
by measuring the dewetting or receding meniscus velocity (RMV) of the ink
on a surface.
For a discussion of dewetting velocity and its measurement, reference is
made to the article by Redon et al in Physical Review Letters, Vol 66, No.
6, Feb. 11, 1991, pages 715-718.
While the invention will be illustrated by reference to non-aqueous inks it
is believed that it is generally applicable to both aqueous and
non-aqueous inks. Particular attention, however, has been given to inks
wherein the diluent is non-aqueous or substantially non-aqueous (that is
to say, it contains less than 2% water by weight), and has a low polar
solubility parameter, e.g. of not greater than 7.0 MPa.sup.1/2. References
herein to polar solubility parameter are to the values obtained according
to the method of Hansen, C. M. and Skaarup, K., Journal of Paint
Technology, 39 No. 51, pp. 511-514 (1967) as detailed by Patton, T.C.
"Paint Flow & Pigment Dispersion" 2nd Ed., Wiley Interscience, 1979.
Particular examples of non-aqueous diluents with a low polar solubility
parameter eg. a polar solubility parameter of 7.0 MPa.sup.1/2 or less,
are non-polar organic solvents and mixtures thereof with polar solvents,
e.g. containing a minor amount by weight, preferably 5 to 40% by weight,
of polar solvent or solvents. Examples of polar solvents are alcohols,
esters including mixtures such as marketed under the trade name Coasol,
ketones and, especially, ethers, particularly mono- and di-alkyl ethers of
glycols and polyglycols, e.g. monomethyl ethers of mono-, di- and
tri-propylene glycols and the mono-n-butyl ethers of ethylene, diethylene
and triethylene glycols. Examples of suitable non-polar solvents are
aliphatic and aromatic hydrocarbons having at least six carbon atoms and
mixtures thereof including refinery distillation products and by-products.
While diluents with a low polar solubility parameter are preferred, other
diluents, e.g. consisting essentially of polar constituents, may be used.
The diluent, which should be single phase, preferably has the following
properties:
Boiling point: at least 100.degree. C., preferably at least 200.degree. C.;
Viscosity: not greater than 30 mPas, preferably not greater than 15 mPas,
more preferably not greater than 12 mPas measured at 30.degree. C. using a
Bohlin CS Rheometer with CP4/40 measuring system;
Freezing point: not more than 10.degree. C., preferably not more than
7.degree. C.;
Polar solubility parameter: up to 7 MPa.sup.1/2, more preferably 0.1 or 0.2
to 2 MPa.sup.1/2.
Particular examples of diluents are aliphatic hydrocarbon solvents such as
those sold under the trade names Exxsol, Solvesso, Exxon naphtha, Isopar,
Pegasol and Shellsol, mixtures of such solvents with alcohols, especially
long chain alcohols, e.g. containing 535 wt.% alcohol, and mixtures of
such solvents with alcohols, especially long chain alcohols, and ethers,
e.g. containing 90 to 45% by weight of the hydrocarbon. By a long chain
alcohol we mean an alcohol containing at least 10, eg. 10 to 30, carbon
atoms. In general, the diluent will form from 60 to 98.5%, and preferably
from 75 to 90%, by weight of the ink.
While the invention is applicable to any inks containing dispersants having
acid or basic groups and capable of stabilising the dispersion of the
chosen pigment in the chosen diluent, it is particularly applicable to
inks containing macromolecular polyionic dispersants. It is preferred that
the dispersant is soluble in the diluent or is so highly solvated that the
mixture of diluent and dispersant is substantially indistinguishable from
a true solution. Examples of dispersants for use in non-aqueous diluents
such as organic solvents e.g. having a polar solubility parameter less
than 7 MPa.sup.1/2 are polyester amine dispersants such as those sold by
Zeneca Colours under the trade name SOLSPERSE and dispersants sold under
the trade name EFKA. Mixtures of dispersants may also be used.
Any suitable pigment may be used provided it will form a stable dispersion
in the chosen diluent. Examples are phthalocyanines, quinacridones, Lithol
Rubine 4B toners, isoindolinones, and Rhodamine G lakes (triphenyl methane
derivatives). Preferred pigments are found amongst those characterised as
pigment dyes in The Colour Index. Preferably the pigment will be of a
primary subtractive hue. The pigment should be lightfast, and thermally
stable even with repeated warming. Carbon blacks may also be used. The
appropriate concentration of pigment will depend upon its nature but in
general will be in the range of from 2 to 20%, preferably from 4 to 15%,
by weight of the ink.
The nature of the active group of the neutraliser will depend upon whether
the dispersant has acidic groups or basic groups. For example, where the
dispersant is a polyamine, the neutraliser is suitably an acid. Any
suitable acid may be employed as a neutraliser provided it is compatible
with the ink and preferably soluble in the diluent; examples are Lewis
acids, inorganic acids, organic acids and phenols. The neutraliser may
also be a small molecule or a polymer. Examples are organic carboxylic
acids such as acetic, citric, tartaric, toluic and .beta.-naphthoic;
organic sulphonic acids such as 2-naphthalene sulphonic and p-toluene
sulphonic; simple phenols, e.g. resorcinol and 2-naphthol; alkyl phenols
e.g. nonyl phenol; alkyl partial esters of acids of phosphorus, e.g.
phosphoric acid and phosphinic acid; and polymeric compounds containing
phenolic groups, for example novolaks, e.g. having the repeating units
containing the following structure:
##STR1##
where R is an alkyl group e.g. as in butyl or octyl, e.g. Uravar FN5.
Where the dispersant contains acidic groups, the neutraliser may suitably
be an amine.
The most suitable neutraliser for a given ink and the amount required,
which will depend on its nature and its equivalent weight, can best be
determined by simple experiment, e.g. by plotting concentration against
the value obtained for the RMV of the resultant ink. In general, even a
small amount of neutraliser will provide an improvement and increasing the
amount increases the RMV up to a maximum after which further increases in
the amount of neutraliser employed may result in a reduction in the RMV.
However, an amount, which will vary with the nature of the compound
employed, will eventually be reached at which the ink will be
destabilized; that is to say, sedimentation and/or an increase in
viscosity is detected in the ink within 28 days of standing at 25.degree.
C. This amount is generally about equal to that which yields the maximum
value for RMV and thus the preferred amount of neutraliser is generally in
the range of about 25 to 100%, more preferably 50 to 95%, of that which
yields the maximum RMV value.
The dispersion inks according to the invention may be made by a method
including the steps of (a) forming a stable dispersion comprising
colourant, a dispersant having basic or acidic groups, and a diluent; and
thereafter (b) adding a non-destabilising amount of neutraliser.
The invention is now illustrated by the following Examples in which all
parts are expressed as parts by weight except where otherwise indicated.
EXAMPLE 1 (COMPARATIVE)
An ink jet ink was prepared having the following composition:
______________________________________
Diluent Exxsol D140 57.3 parts
Novol 17.75 parts
Dowanol TPM 10 parts
Pigment Regal Black 250R
11.0 parts
Dispersant Solsperse 13940
3.75 parts
Solsperse 5000 0.2 part.
______________________________________
Exxsol D140 is a mixture of aliphatic hydrocarbons having a boiling range
of 280.degree. C. to 317.degree. C. marketed by Exxon.
Novol is a substantially pure oleyl alcohol marketed by Croda.
Dowanol TPM is tripropyleneglycol monomethyl ether marketed by Dow.
Regal Black 250R is a carbon black marketed by Cabot Corporation.
Solsperse 13940 is a polyester amine hyperdispersant marketed by Zeneca
Colours and contains 40% by weight of active ingredient.
Solsperse 5000 is a substituted ammonium phthalocyanine marketed by Zeneca
Colours.
Exxsol, Novol, Dowanol, Regal Black and Solsperse are all trade marks.
The resultant ink composition was a stable ink having a viscosity of
approximately 10 mPas and gave high definition print of good optical
density on plain paper when printed from a multi-nozzle drop-on-demand
printer operating at multi-line and high speed. By "stable" is meant that
the ink did not precipitate or coagulate after 3 months at 65.degree. C.,
preferably 70.degree. C.
The receding meniscus velocity (RMV) of the ink was measured in the
following manner. A soft foam pad which has been soaked in the ink is
drawn across a non-wetting fluorosilane surface at a measured velocity.
The velocity at which the ink just fails to follow the foam pad and begins
to leave a trail upon the non-wetting coating is taken to be the RMV. The
non-wetting fluorosilane surface employed in the test was derived from a
one-step fluorosilane coating composition comprising methyl triethoxy
silane, 3-aminopropyl triethoxy silane and 1H,1H,2H,2H-perfluorooctyl
triethoxysilane and obtained by mixing together 30 parts ethanol, 0.9 part
glacial acetic acid, 2.0 parts hexanol and 5 parts hydrochloric acid (0.01
mol/dm.sup.3) and then adding 5 parts methyl triethoxysilane, 0.5 part
3-aminopropyl triethoxysilane and 0.5 part 1H,1H,2H,2H perfluorooctyl
triethoxysilane to the mixture. The solution so formed was then allowed to
age for 2 days to allow hydrolysis of the silicon compounds. A sheet of
Upilex-R polyimide was washed with about 1 mol/dm.sup.3 NaOH, rinsed well
with water and dried by wiping with a clean room wipe and the aged
solution was applied to the surface of the sheet using a meter bar to form
a wet coating approximately 4 microns thick. The coated sheet was allowed
to stand for 5 minutes and then placed in a humid atmosphere in an oven at
95.degree. C. for 3 hours. The resulting fluorosilane coating thickness
was of the order of 0.6 microns.
(Upilex-R is available from the Ube Chemical Company of Japan. Upilex is a
trade mark). The measured RMV was about 1.6 mm.sec.sup.-1.
EXAMPLES 2-29
A number of ink jet ink formulations were prepared having the same
formulation as in Example 1 but wherein some of the Exxsol D140 was
replaced by an equal amount, by weight, of a neutraliser for the
dispersant. The nature and amount of the neutraliser employed and the RMV
of the resultant ink composition, measured as described in Example 1, are
recorded in Table 1.
These inks had similar properties to that of Example 1 and gave print of
similar quality; however, they have higher RMV values and longer
uninterrupted printing times are obtained while maintaining a clean nozzle
plate. Moreover, when the inks are used in ink jet printer heads of
drop-on-demand printers, greater negative ink supply pressures can be
tolerated than in the case of the ink of Example 1 without ingestion of
air and also greater short term positive pressure surges can be withstood
without flooding.
TABLE 1
______________________________________
Example Amount Used RMV
No. Neutraliser (Parts by Weight)
(mm/s)
______________________________________
2 2-naphthalene sulphonic acid
0.5 3.1
3 2-naphthalene sulphonic acid
1 3.4
4 2-naphthalene sulphonic acid
1.5 4.3
5 2-naphthalene sulphonic acid
2 3.4
6 2-naphthalene sulphonic acid
2.5 4.9
7 2-naphthalene sulphonic acid
3 5.8
8 2-naphthalene sulphonic acid
4 6.5
9 2-naphthalene sulphonic acid
5 5.8
10 para-toluene sulphonic acid
0.5 3.1
11 para-toluene sulphonic acid
1 3.1
12 para-toluene sulphonic acid
1.5 3.7
13 para-toluene sulphonic acid
2 4.9
14 para-toluene sulphonic acid
2.5 4.3
15 para-toluene sulphonic acid
3 4.9
16 para-toluene sulphonic acid
3.5 5.9
17 Acetic Acid 0.15 2.1
18 Acetic Acid 0.3 2.7
19 Acetic Acid 0.45 2.5
20 Acetic Acid 0.6 3.4
21 Acetic Acid 0.75 3.7
22 Acetic Acid 0.9 4.6
23 Acetic Acid 1.02 4.6
24 Acetic Acid 1.2 3.4
25 iso octyl phosphate
1 5
26 iso octyl phosphate
2 7.5
27 iso octyl phosphate
3 7
28 iso octyl phosphate
4 6.5
29 iso octyl phosphate
5 5.9
______________________________________
EXAMPLES 30-38
A series of ink jet compositions were prepared containing, by weight
______________________________________
Diluent:
Exxsol D140 Various amounts as specified in Table 2
Novol 20 parts
Pigment:
Regal Black 250R
11 parts
Dispersant:
Solsperse 13940
3.75 parts
Solsperse 5000
0.2 part
Neutraliser:
Various as specified in Table 2
______________________________________
TABLE 2
______________________________________
Exxsol D140
Example (Parts by Amount Used
RMV
No. Weight) Neutraliser
Parts by Weight)
(mm/s)
______________________________________
30 64.55 resorcinol 0.5 6.3
31 64.05 resorcinol 1 7.9
32 63.05 resorcinol 2 8.4
33 62.05 resorcinol 3 8.2
34 64.05 2-naphthol 1 3
35 63.05 2-naphthol 2 3.9
36 62.05 2-naphthol 3 7.6
37 61.05 2-naphthol 4 9.3
38 60.05 2-naphthol 5 9.9
______________________________________
EXAMPLES 39 TO 46
A series of ink jet compositions were prepared containing, by weight
______________________________________
Diluent:
Exxsol D140 Various amounts as specified in Table 3
Novol 10 parts
Pigment:
Regal Black 250R
11 parts
Dispersant:
Solsperse 13940
3.75 parts
Solsperse 5000
0.2 part
Neutraliser:
Various as specified in Table 3.
______________________________________
TABLE 3
______________________________________
Exxsol D140
Example (Parts by Amount Used
RMV
No. Weight) Neutraliser
Parts by Weight)
(mm/s)
______________________________________
39 74.8 Uravar FN5 0.25 2.7
40 74.55 Uravar FN5 0.5 3.1
41 74.05 Uravar FN5 1 4.8
42 73.05 Uravar FN5 2 6.4
43 73.05 Nonyl phenol
2 4.2
44 72.05 Nonyl phenol
3 4.3
45 70.05 Nonyl phenol
5 6.3
46 67.55 Nonyl phenol
7.5 5.9
______________________________________
Uravar FN5 is an alkyl substituted novolak marketed by DSM of Netherlands.
EXAMPLES 47 TO 51
In Example 47 an ink jet ink was prepared having the following composition:
______________________________________
Diluent: Dowanol TPM 89 parts
Pigment: Regal Black 250R
6.6 parts
Dispersant: EFKA 47 4.1 parts
Neutraliser: Uravar FN5 0.3 parts.
______________________________________
EFKA 47 is a polyamine dispersant marketed by EFKA Chemicals. EFKA is a
trade mark.
The resultant ink, which was stable and gave high definition print of good
optical density when on plain paper using a drop-on-demand printer, had an
RMV, measured as described in Example 1, of 13.6 mm.sec.sup.-1.
In Examples 48 to 51, the ink composition of Example 47 was modified by
changing the concentration of diluent and neutraliser as indicated in
Table 4 which also records the inks so obtained.
TABLE 4
______________________________________
RMV
Example No.
Amount of Diluent
Amount of Neutraliser
(mm/s)
______________________________________
48 88.6 0.66 14.3
49 87.8 1.5 15.7
50 85.3 4 14.3
51 89.3 0 2.9
(Comparative)
______________________________________
EXAMPLE 52
An ink jet ink was prepared having the following composition:
______________________________________
Monastral Blue FGX (Pigment Blue 15.4)
5%
Solsperse 13940 5%
Solsperse 5000 0.5%
Novol 9%
Uravar FN5 1.2%
Exxsol D140 79.3%
______________________________________
EXAMPLE 53
An ink jet ink was prepared having the following composition:
______________________________________
Fanal Pink D4830
5%
Solsperse 13940 5%
Novol 22%
Uravar FN5 1.25%
Exxsol D140 68.75%
______________________________________
EXAMPLE 54
An ink jet ink was prepared having the following composition:
______________________________________
Paliotol Yellow D140
5%
Solsperse 13940 3.75%
Novol 18%
Uravar FN5 1.5%
Exxsol D140 71.75%
______________________________________
EXAMPLE 55
An ink jet ink was prepared having the following composition:
______________________________________
Paliotol Yellow D140
5
Solsperse 13940 3.75%
Uravar FN5 1%
Coasol 90.25%
______________________________________
Coasol is a liquid mixture of esters marketed by Chemoxy International Ltd.
EXAMPLE 56
An ink jet ink was prepared having the following composition:
______________________________________
Heliogen Blue TD7105
5%
Solsperse 5000 0.5%
Solsperse 13940 3.75%
Novol 10%
Uravar FN5 1%
Exxsol D140 79.75%
______________________________________
EXAMPLE 57
An ink jet ink was prepared having the following composition:
______________________________________
Monastral Blue FGX (Pigment Blue 15.4)
5%
Solsperse 13940 5%
Solsperse 5000 0.5%
Dowanol TPM 10%
Novol 15%
Uravar FN5 5%
Exxsol D140 59.5%
______________________________________
The RMV's of the ink jet inks of Examples 52 to 57, measured as described
in Example 1 were as follows
______________________________________
Example RMV (mm/s)
______________________________________
52 6.2
53 5.0
54 6.2
55 8.3
56 4.6
57 11.3
______________________________________
All the inks of Examples 30 to 50 and 52 to 57 exhibit greater values for
RMV than an ink of the same composition but wherein all the neutraliser
has been replaced by a corresponding amount of diluent and also exhibit
the improved properties reported for the ink of Examples 2 to 29.
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