The present invention relates to aqueous Suspension or disper¬ sion of carbon black and, more especially to an aqueous Suspension of carbon black the particles of hich are grafted with che ically bonded hydrosoluble polyolefinic chains, preferably polymers or cα- polymers of acrylic ironσmers and, more particularly, ammonium and alkali metal polyacrylates. In the present disclosure, the word "po- lyolefine" designates free radical polymer izable doubl e-bonded iro- o ers carrying water solubilizing functions. Details on such mono¬ mers are provi ed hereafter. The invention also concerns a method for preparing such an aque¬ ous Suspension and the use thereof for manufacturing ink composit- ions, namely inks for jet-printing with jet-printing machines.

It is well known that jet-printing imposes certain difficult to achieve contingencies upon the ink compositions to be used. For instance, such inks must have a high optical density, i.e. contain a relatively high concentration of carbon-black and simultaneously show a very low viscosity and surface tension, i.e. of the order of 1.5 to 10 cP and 30 to 50 dynes.cm, respectivel . Also, the carbon- black particles ought to be very fine so as to preferably pass fre e- ly through fine filters, e.g. 1 to 50 Λi mesh filters. Further, in such suspensions, the carbon-black particles should not settle with time, i.e . they should remain in Suspension for extended pe icds.

Carbon-black being essentially hydrophobic, attempts have been made to attain the above-mentioned proparties by grafting water so- luble polymeric radicals onto the carbon black particles thus mak- ing them water ompatible and freely dispersible in water.

Thus, in Japanese (opi) Patent Application 80 ,147561 (CA. 94_, 192963) there is disclosed the grafting of carbon black particles with acrylic acid in ethanol in the presence of ^c , ^ ^, -azoisobutyro- nitrile (AIBN) and under irradiation. ϊhe thermal grafting and po- lymerization of acrylate esters on carbon black is also disclosed in CA. 94, 48453. In Japanese (opi) Application 74

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disclosed the polymerization and grafting of styrene on carbon black in the presence of AIBN at 140°C (CA. _82, 163002) and in Japanese Patent Publication 74,11557 (CA. 81, 106311) there is disclosed the polymerization and grafting on carbon black of acrylonitrile in the presence of AIBN in DMF. In DOS 2.130.617 (CA. 76, 113947) , there is described the direct grafting on carbon black of prepolymerized monomers and in Japanese Patent Publication 71,26970 as well as in GB-A-1.191.872, there is described the anufacture of carbon black with grafted acrylic acid and butyl acrylate σopolymers in methyl-iso- butylketone and other organic solvents. Such grafted carbon black can be easily dispersed in aqueous am onia Solutions.

In GB-A 1.421.529 there is disclosed the Suspension polymeriza¬ tion into granules of olefinically unsaturated monomers in aqueous edia in the presence of carbon black and appropriate surfactants. After polymerization, the formed polymer beads having the carbon black incorporated therein are separated fron the water phase and expanded.

The above techniques are effective but they either provide no ho ogeneously dispersed hydrophilized carbon black particles or they rely on the use of organic or aqueous-organic solvants for undertak- ing the grafting of the carbon black particles. Yet, when such graft¬ ed particles must be used in aqueous jet-ink formulations, the or¬ ganic solvants must first be re oved and the particles must be re- dispersed in the aqueous media suitable for such inks. Now, it has been found that such method is tedious and that the grafted particles <3o not disperse sufficiently well in the jet-ink formulations for providing coπpositions suitable for being used in jet-printing a- chines.

Consequently, it was desirable that grafting and polymerizat¬ ion be carried out in water in such manner that a suitable aqueous dispersion or Suspension of grafted carbon black be obtainεd which, afterwards, can be directly converted into jet-ink composition by the addition of the usual additional jet-ink σomponents. It was further desirable that aqueous suspensions or dispersions of carbon black particles be obtained, the particles of which are rendered suf- ficiently hydrophilic to becoma highly water compatible and thus pro¬ vide very low viscosity Solutions even at high solid content. In such cases, the solubilizing power of the groups grafted on the particles

is so great that dispersions very near to real Solutions are involved. The aqueous Suspension of grafted carbon black of the invention has been obtained in this manner. It is characterized by the following Parameters: its concentration by weight of grafted carbon black is fron about 1 to 15% and its viscosity is from about only 2 to 30 cP at room terπperature. The weight amount of water solubilizing graft¬ ed polymer or copolymer chains is preferably from about 0.0001 to about 0.002 g (or 0.1 mg to 2 mg) per Square meter of the surface of the carbon black particles which is indeed an extremelly .mall amount relative to the teaching of the prior art. Since the weight required of carbon black particles for making 1 m^ varies from about 0.003 g to about 0.16 g, depending on the kind and grade, the weight of grafted material per gram of carbon black will be from about 0.0006 to 0.6 g; however, carbon blacks of graces ranging from 15 to 150 (i.e. 0.006 to 0.06 g/π are usually preferred. The number of mo- nomer units linked together in the grafted chains is preferably from about 20 to 200. The length of the grafted chains should be suffi- cient to therefore provide adequate "solubility in water" (i.e. re- markably good dispersibility of the grafted particles) but not too great to avoid too large molecular weights with consequent too high viscosity and filterability problems. This also contrasts with tha prior art where simultaneous graf ing and polymerization to high poly¬ mers occurs thus preventing the foππation of "near Solutions" of car¬ bon black in water like in the invention. With the above ränge of grafted chains, the present Suspension filters rapidly through a 10 U mesh screen and slowly but acceptably through a 1 α mesh screen (for instance at a rate of 0.1 to 10 ml/min depending on pore size) . It is believed that the polyacrylate chains do σrirπp or coil at short distance from the carbon black surface and pack over such surface with the carboxylate functions pointing radially toward the outsi- de thus providing the right solubility properties, this being so when the pH is kept preferably bet een about 5 and 9. Indeed, it has been shown that outside this pH ränge, the present dispersion looses so- mewhat its desirable properties (e.g. Sedimentation ay occur) . It is particularly re arkable that hydrophobic carbon black particles can be made so well dispersible, i.e. nearly soluble, in water with grafted quantities of acrylate as low as about a tenth of a milli-

gram per square meter of the carbon black. Naturally, the afore en- tion d parameters are not critically limiting and can exceed or fall Short of the above mentioned ranges without departing from the sco- pe of the invention. The method of preparation of the aqueous dispersion of graft¬ ed carbon black of the invention comprises treating carbon black in water with a water soluble peroxide and, after peroxidation, adding a water soluble acrylic monomar and a further amount of peroxide, whereby homogeneous free radical polymerization of the monomer and grafting on the carbon black particles will occur simultaneously. The reaction ay be carried out in the absence or in the presence of a free radical polymerization accelerator, for ins ance an a i- ne accelerator.

Regarding mechanistic considerations pertaining to radical graft- ing on carbon black, the following information can be provided.

Carbon black is essentially composed of carbon particles of ge- nerally spherical shape bearing boundary oxygenated functions such as carboxyliσ, phenolic and quinonic functions.

The phenolic and quinonic functions can act as polymerization quenchers as they will form, when reacting with initiators (for ins¬ tance C _j -C^R) , stabilized radicals (unreactive) viz.

©

_

In contrast, peroxides (for instance RCO-O-O-COR) will probab- ominantly react as follows:

©

O-vfPI -

The radicals formed in reaction (3) will therefore promote ole- finic polymerization instead of inhibiting it as in reactions and

The peroxides used in the present ethod are water soluble pe- roxides such as airmonium and alkali metal persalts, e.g. sodium, po- tassium and ammonium parsulfate and the corresponding perphosphates, perborates and the li e; alkali metal peroxides and hydrogen pero¬ xide can also be used. Other peroxide initiators suitable in the pre¬ sent invention are lissd in Eiicyclopedia of Polymer Science & Tech- nology, vol. 2, Interscience Publishers, p. 230 - 233, (1965) .

The polymerizabl≤ olefinic monomers usable in the present me¬ thod are preferably the water soluble acrylic monomers such as the alkali metal and ammonium acrylates and methacrylates unsubstitut- ed or substituted by water solubilizing functions such as hydroxy- lic, ketonic and nitrile functions. Of course, alkali metals inclu- de sodium, potassium, lithium and higher molecular weight alkali me-

+ + tals; ammonium includes the group NH. and NR, in which R can be hy¬ drogen or alkyl groups commonly found in current chemical practice. Substituted and unsubstituted acrylic and methacrylic acid compounds with unsalted free carboxylic groups are also usable but less pre- ferred as the visσosities of the resulting graft carbon black aque¬ ous dispersions thus obtained are not as low as when using the mono¬ mers in the alkali salt form. Furthermore, it was found that when treating such free COOH containing graft carbon black aqueous dis- persions with alkali metal hydroxide in view of obtaining dispersions identical with that obtained directly with the alkali salt monomers, viscosities increased quite unexpectedly instead of decreasing. In addition, other water soluble vinyl monomers such as acrylamide, me- thacrylamide, N-vinyl-pyrrolidone and hydroxyethyl acrylic acid are also possible preferably in admixture with the aforementioned acry¬ lates. Some further monomers usable in this invention are listed in the aforementiored Encyclopedia of Polymer Science & Technology re- ference.

The carbon black can be selected from various sources and in- clude the usual types of carbon black, namely Channel black, therm- al black, lamp black and furnace black. Furnace black is preferred. Referencε on carbon usable in this invention are: DCNNET and VOET:

Carbon Black Ehysics, Che istry and Elastomer Reinforce ent, Marcel Dekker Inc. , (1976) .

If accelerator s are used in the present ethod, commonly avail- able free radical polymerization acσelerators can be used; amine ac- celerators are σonvenient such as tetramethyl ethylenediamine, pen- ta ethyl diethylene tetramine, hexa ethyl triethylene pentamine and the like.

For carrying out the present simultaneous polymerization and grafting of carbon black with olefinic ironomers, it is preferable to agitate the ingredients in water at a te perature of 50°C to 100°C, preferably at reflux temperature . The reaction time is from about 1 hr to about 60 hrs at reflux temperature although longer reaction times are not harmful but not economical. After ccoling, the ungraft- ed homopolymer which is produced as a by product can be removed by usual techniques, e.g. freeze drying, centrifugation or dialysis but, for ost uses, this is not necessary, the presence of such homopo- lymers not being detrimental for further uses of the grafted carbon black dispersion in jet-ink compositions. On the contrary, the pre¬ sence of the homopoly ers in the solution will serve as a binder in- gredient useful for improving the adhesion of the ink on the prinfc- ed surfaces and the cohesion of the carbon black particles together. This factor was unexpected and surprising and provides a considera- ble advantage to the dispersion of the invention over the prior art compositions in jet-ink applications. The quantities of reagents to be used in the method of the in¬ vention are as follows: in the first peroxidation stage, there can be used for 100 g of carbon black from about 10 to 50 g of pεroxi- ä-? αounted as ₂ S2θg or mole-equivalents of other water soluble pe¬ roxides and, when an amine accelerator is used, about 0.1 to 5 g of such an amine, e.g. N-tetramethyl ethylenediamine (TEMΞD) or mole-equi- valent quantities of other amine accelerator s. These quantities are however not critical provided enough paroxidant is used. The pero¬ xidation can be carried out at 50 - 100°C under stirring in water for about 1 to 24 hrs but these conditions are not critical provid- ed that the reaction is allowed to go to completion.

In the second stage, i.e. the grafting stage, the quantities of olefinic monomers that can be used can vary from approxi ately

-3-

0.01 mole-equivalent to about 0.5 ole-equivalent per gram of car ^¬ bon black. The quantities of monomers to be used are obviously re- lated to the density of grafting sites on the carbon black particles that varies considerably from one type of carbon black to the other and is generally related to the quinone and phenol function area den¬ sity on the particles. Acσording to the data of the main manufactu- rers of carbon black, such quinone and phenol group densities can vary from about 1 to about 3000 u equiv./g of carbon black which, in view of the aforegiven ränge of area per gram values (depending on the kind of carbon black) will provide figures ranging from about 0.01 ι equiv./m ² to about 10 Λi equiv./ ² . Thus, the amount of mono¬ mer in the grafting stage will be adapted as a function of the graft¬ ing equivalence selected and the grafting site density of the car¬ bon black used. The amount of peroxide to be used in the polymerization graft¬ ing stages depends on the amount of monomer used and can be compris- ed from about 0.01 g to 0.1 g (counted as ϊ^S _j Og) per gram of the monomer. Equivalents of other peroxides are also usable. When using also an amine accelerator, for instance TEMED or equivalents of other amine acceLerators, quantities of the order of 0.01 to 1 g of TEMED per gram of peroxide (counted as K ₂ S ₂ 0g) are advantageously usable. All the above reagent ratios and quantities are not critical and can fall short of or exceed the given li its in so e cases, provided of course, that the amounts of respective reagents are enough for ac- complishing the reactions and not in such excess as becoming non eco- nomical.

The aqueous Suspension of grafted carbon black of this invent¬ ion is directly usable for making jet-ink compositions. For this, it is sufficient to add to the Suspension the suitable amounts of usual jet-ink additives, such as wetting agents, surfactants and vis¬ cosity Controlling agents, d^ s, mold inhibitors, oxygen absorbers, buffering agents, pH Controlling agents. In the present invention, a considerable and unexpected advantage is provided by the presen¬ ce of the residual homopolymer which was formed during polyme izat- ion and grafting. As surfactant products, non ionic compounds such as polyoxyethylene sorbitan ironolaurate and the like are prefer ed. As wetting agents, polyglyσols or glycolamines such as diethylene

glyσol, glycerine, cλ -thiodiglyool, triethanolamine and N,N-d__ etho- xyHnethyl-2-imidazolidone are suitable . The quantities of such ad¬ ditives will oonfor to usual practice.

As dyes, CI acid black Nös. 1, 24, 26, 48, 58, 60, 109, 119 and 131 can be used. As mold inhibitors, sodium dehydroace ate, 1,2-benz- isothiazolin-3-one , 6-acetoxy-2,4-dimethyl-m-dioxane or formaldehy- de can be used. As oxygen absorbers, sodium sulfite, sodium bisul- fite can be used. As pH Controlling agents, HC1 and NaOH can be used.

In addition to the aforementioned use in jet-printing inks, the aqueous dispersion of the invention can be used for many other pur- poses. Among such purposes, one may recite inks for fountainpen, ball- point pen, feit pen, intaglio, rotogravure, rotary printing, elas- tographic printing, typographic printing, rotary news-paper and the like . The following Examples illustrate the invention.

Exampia. 1 (comparativ )

Fourty three gram of carbon black (grade "Regal-R", quinone den- sity 2 i equi./g, CABOT Corp.) were agitated with 300 ml of water and 30 ml of ethanol. Then, 4.3 g of ammonium persulfate and 0.2 g of N-tetraethyl-ethylenediaraine (TEMED) were added and the ixture was stirred for 18 hrs at 90°C Then, 43.2 g of acrylic acid and 1 g of ( ^NH 4) 2 ^s 2°s ^were added and the mixture was stirred under reflux at 95 - 98°C for 24 hrs. After cooling, there was obtained a well dispersed Suspension of polyacrylic grafted carbon black the solid concentration of which was about 14% . The pH of this solution was about 2 and its viscosity about 45 cP. Dilution with about 200 ml of water provided carbon black dispersion of good opacity and much lower viscosity usable as a priπting jet-ink. Upon neutralization with dilute NaOH solution, the viscosity increased.

Example 2

Fifteen gram of carbon black (grade "Regal R") in 50 ml of H ₂ Q were agitated for 4 hrs at 95 ^β C with 1.5 g of (NH ) ₂ S ₂ O _g and 0.1 ml of TEMED after which a solution of 22.5 g of acrylic acid in 41.6 ml

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of 30% aqueous NaOH solution was added with 2 g of (NH ₄ ) ₂ S ₂ 0g and 0.1 ml of TEMED. The mixture was further agitated for 24 hrs at 95°C. Then it was oooled and provided a dispersion (JE) of about 20% solid grafted carbon black . The pH was 5.7 and the viscosity 7.1 cP. Iow- er visσosities with still accεptable opacity (blackness) were obtain¬ ed by dilution to approximately 10 - 15% dispersed solids.

The experiment was repeated as described but using 0.3 ml of TRIS-TEMED (TRIS eans tris-(hydroxyiiethyl) -aminomethans) instead of the TEMED in the peroxidation stage and no amine in the polyme- rization grafting stage. A dispersion (F) of coπparable solid con- centration was obtained with viscosity 4.9 cP and pH 5.5. It however settled after 3 min Sedimentation by centrifugation under 3300 rpm and was σonsidered unacceptable.

Dispersions (G and H) of corresponding concentrations were ma- de exactly as disclosed for dispersions E and F, respectiveLy, but replacing the "Regal-R" carbon black by type "Elftex-5" (Furnace black) carbon black. Dispersion G had a pH of 5.7 and a viscosity in undiluted form of 12.1 cP; it did not settle after 30 min centri¬ fugation. Dispersion H had a pH of 5.4 and a viscosity of 7.1 cP in undiluted form. It settled after 24 min centrifugation. There was no substantial precipitation after 1 year storage at rcom tempera¬ ture.

Examole 3

The experiment of Exa ple 2 was repeated four times (samples II - 14) using 100 g of water, 15 g of carbon black ("Elftex-5") 1.5 g of - 2 ^s _ ⁰ Qr °« ³ ml of TEMED and a temperature of 95°C in the pero¬ xidation stage, and 22.5 g of acrylic acid, 65 ml of 30% NaOH, 2 g of 1 ml of TEMED, and 35 - 40 hrs boiling temperature (98°C) in the polymerization grafting stage. The variable was the peroxi¬ dation duration which was 1 hr (II), 2 hrs (12), 4 hrs (13) and 6 hrs (14) . Wo significant differences between the results were found, all dispersions having a _ ^~ of 5.8 - 6.0 and visσosities of about 15 - 17 cP in undiluted form. Much lower viscosities, with still ac- ceptable opacities, were found with dispersions diluted down to about 5 - 10% grafted solids.

'

-i

Example 4

The expariments of Example 2 were repeated under the following conditions:

Bsroxidation stage: water 100 ml; carbon black ("Elftex-5") 15 g;

^K 2 ^S 2° _S ^and variable according to Table I below; 2 hrs at 95°C.

Grafting and polymerization stage: sodium acrylate from 22.5 g acrylic acid neutralized with 65 ml 30% NaOH; K2 ^S 2° ₈ ~ ^g; ' ^{IEMED x m} ---'

24 hrs at 98°C Ebur samples (Jl to J4) were prepared according to the further data in Table I below and gave corresponding dispersions with viscosities also given in the Table.

TAB] ffi I

Samples K2S203 (g) TEMED (ml) Viscosity (cP)

Jl 1.5 0.15 13.6

J2 2.25 0 .23 18.7

J3 3.0 0.30 15.3

J4 3.75 0 .38 18. 0

Upon dilution with water to provide 5 - 10% solid low viscosi¬ ty aqueous dispersions, the above samples still had acceptable opa- cities and settling times.

Example 5

Experiments (Kl to K4) similar to those reported in Example 4 were performed under the following conditions, except for the K ₂ S ₂ O _a

and TEMED used in the second stage which were as indicatsd in the next Table II.

Peroxidation stage: water 100 ml; carbon black ("Elftex-5") 15 g; K ₂ S ₂ 0g 3 g; TEMED 0.3 ml; 2 hrs at 95°C

Grafting and polymerization stage: Na acrylate from 22.5 g of acrylic acid neutralized with 65 ml of 30% NaOH solution; ^S _j Og and TEMED see Table II; 48 hrs at 98°C. The remaining data and results are recorded in the next Table.

TABEE II

Samples K2S2O8(g) TEMED (ml) Viscosity (cP)

Kl 1.0 0.5 10.4

K2 1.5 0.75 17.7

K3 2.0 1.0 19.6

K4 2.5 1.25 16.6

Upon centrifugation at 3300 rpm, the settling time for all samples was over 3.5 hrs.

Example 6

Experiments like in the previous Examples (samples Ll to L4) were carried out with variable amounts of acrylic monomer, K ₂ S ₂ O _a and TEMED in the polymerization grafting stage (see Table III below) . Moreover, the following conditions were used:

Peroxidation stage: water 100 ml; carbon black ("Ξlftex-5") 15 g;

^K 2 ^S 2°8 ^{3 g?} ' ^{IE D} °- ³ 9? ^{2 hrs} at 95°C.

and TE-

MED di b ion NaOH

OMPI

- I S ..

65 ml of aqueous solution containing required NaOH neutralizing equi- valent. The Sedimentation time after centrifugation at 3300 rpm is also shown in Table III.

TABIE III

Samples Acrylic K2S208 TEMED Viscosity Centrifugat¬

(g) ⁽ g) (ml) (cP) ion settling (min)

11 10 0.88 0.44 6.6 30

_. L2 15 1.33 0.67 5.7 30

13 22.5 2 1.0 13.7 > 90

L4 30 2.66 1.33 27.1 790

The grafting level for samples Ll and L2 was considered border- line to achieve optimal conditions of opacity and viscosities. (for opacity ireasurerrents, see for instance Example 9)

Example 7

The i-mportance of using carbon black types with a high densi¬ ty of grafting sites was evidenced by repeating the experiments of the previous examples with other grades of carbon black, i.e. "Re- gal-R" .(2 U equiv. of quinone sites/g) and "Vulcan 6" (70 /u equiv. of grafting sites/g) . Pertinent data on both the peroxidation and grafting stages are outlined below in Tables IV and V. In the Tables a previous sample (L3 from Example 6) is included for oomparison. Except for the specific data reported in the Tables, the other con¬ ditions wäre as disclosed in Example 5.

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TABLE IV

(peroxidation)

Sample Carbon black Quinone specific surface

(no) type and quantity conc. (m2/g)

⁽ g ⁾ Cueq./g)

3 Elf ex-5 (15) 18 74 5 Regal- (13.9) 2 80 6 Vulcan-6 (9.7) 70 115

M3 Vulcan-6 (15) 70 115

TABLE V

(Polymerization & Grafting)

Sample Viscosity of greifted Centrifugation Optical (No) solution (cP) settling at density 3300 rpm (hrs)

L3 13.7 >2.5 1.40-1.45 L5 6.3 <0.5 0.96-0.98 L6 6.7 72.5 1.15-1.22 M3 18.8 72.5 1.44-1.48

The data of Table V show that using carbon black with high spe¬ cific surfaces provides more favorable σombinations of high optic¬ al densiiy and low dispersion viscosity.

Example 8

Ä sample of grafted carbon black was prepared under the same conditions pertaining to sample L6 in Example 7 but varying the greift- ing and polymerization duration. The. other general reaction Parame¬ ters are listed below:

Peroxidation stage: water 100 g; carbon black ("Ξlftex-5") 15 g; ^K 2 ^S 2°8 ^{3 g; TEMED} °* ^{3 m1} ' ^{2 hrs at 95} ° ^c '

Grafting & Polymerization: acrylic acid 22.5 g; neutralization 30% NaOH 65 ml; K ₂ S ₂ 0g 2 g; TEMED 1 ml; temperature 98°C; duration see below.

Grafting and polymerization Viscosity of Suspension duration (hrs) (cP)

0 not measured

5 12.2

21 13.3

45 13.4

69 17.5

91 18.8

From the above data, it can be seen that accaptable viscosities (i.e. degree of grafting) are obtained after about 5 hrs reaction time. Reaction periods over about 60 - 70 hrs will unduly raise the viscosity without much i provement to the grafting yield.

Example 9

A sample of aqueous dispersion of grafted carbon black ("Elf- tex-5) " si ilar to sample L3 (see Example 6) was diluted with water until its content in grafted carbon black was approximately 5 - 15% by weight. Then various preparations of such sample were mixed with usual jet-printing ink ingredients acσording to Table VI below. The visoosity, optical density and surface tension parameters were mea¬ sured and are also gathered in Table VI. All Solutions passed quick- ly through a 10 mesh filter and slowly (but still acceptably) through a 1 ΛI mesh filter. Optical densities above about 0.80 are σonsidered ^' accaptable for a jet-print ink.

Opacities were measured as follows: about 0.5 to 1 g of the ink co position was placed on a piece of jet-print paper and spread to

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a layer of 15 ΛI with a suitably calibrated doctor's blade. The film w is allowed to dry in air at room temperature for about 30 see and the opacity was measured according to usual Standards with a McBeth densitometer.

TABLE VI

Sample of ink 132 131 L305

Solution (ml) 103 51.5 77.25

Ethylene glyσol (g) 8 4 2.75

Water (ml) — — 25

10% aqueous glycol (ml) — 55.5 "Bveen 20 (10% aqueous poly- alkylene sorbitan monolaurate) 16 10 15

Viscosity (cP at 21°C) 7.5 5.1 6.0

Surface tension (dyne/cm) 38 37 38 Optical density (15 ΛI wet ink film) 1.45 0.86-0.94 1.08-1.12.