CA1107004A - Process for the production of a pigment composition - Google Patents

Abstract

Case 3-11454/MA 1717 Canada A Process for the Production of a Pigment Composition Abstract of the Disclosure A process for the production of a non-dusting pigment composition by contacting an aqueous dispersion of an or-ganic pigment with a) a solution or dispersion of an alkaline soluble rosin acid derivative b) a sorbitan ester, and c) a water-insoluble organic carrier having a melting point below 100°C at a temperature above the melting point of both the sorbitan ester and the organic carrier, reducing the pH to below .epsilon., stirring the com-position until the pigment, rosin derivative, sorbi-tan ester and organic carrier are associated in gene-rally spherical granules and recovering the resulting granules.

Description

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, The present invention relates to a process for the production of a pigment composition in a non-dusting form.
The uS patent specification NO. ~ /015 ~ 999 describes a pigment composition in the form of ree-flowing, non-dusting, non-aggregating, non-sticky generally spherical be~ds which comprises from 40 to 80~ by weight of a pig-ment or a water insoluble dyestuff, from 5 to 40~ by weight of a water-insoluble organi~ carrier or mixture of carriers melting below 100C., from 2.5 to 25~ by weight of an organic acid and from 1.5 to 25~ by weight OL an organic base, the amount of acid plus base being from 5 to 35~ by weight, all percentages being based on the weight of the total composition.
These compositions are made by a process which com-prises contacting with agitation an aqueous dispersion of a pigment or water-insoluble dyestuff with a water-inso-luble organic carrier melting below 100C. at a tempera-ture at which the organic carrier is molten, in the pre-sence of an aqueous protective colloid and a mixture of an organic acid and an organic base rendered insoluble by making the pH of the mixture substantially neutral, and allowing the aqueous phase to become substantially free of pigment or water-insoluble dyestuff by its association with the organic carrier, and recovering the resulting pigment-ed beads, after cooling if necessary.
The acid compounds which can be used in the process of the s~id US-PS 4,015,999 include the resin acids and derivatives ~hereof. In many instances the use of pigment compositions containing rosin acids is desirable, but the presence of organic bases, particularly fatty amines, is not desirable. Such uses include pigmenting PVC products, which come into contact with foodstuffs. Also the presence of fatty amines has a detrimental effect on the electrical properties of plastic films.

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we have now found that if a sorbitan ester is used in place of the organic base, a high yield of beads are produced which have very good dispersibility in plastics such as PVC. Moreover, it is no longer necessary to use a protective colloid, although one can be used if desired.
Accordingly, the present invention provides a pro-cess for the production of a pigment composition in a non-dusting form which comprises contacting an aqueous dis-persion of an organic pigment with ` a) a solution or dispersion of an alkaline soluble rosin acid derivative having an appro~imate acid value in the range 100 - 250, at a pH of from 8 to 11.
b) a sorbitan ester, and c) a water-insoluble organic carrier having a melting point below 100C.
at a temperature above the melting point of both the sorbi-tan ester and the organic carrier, reducing the pH to be-low 8, stirriny the composition until the pigment, rosin derivative,sorbitan ester and organic carrier are associat-ed in generally spherical granules, and recovering the re-sulting granules, the amounts of the ingredients being ~0 - 75~ pigment, 5 - 25~ rosin acid, 5 - 40~ sorbitan ester and 5 - 50% carrier, all percentages being based on the weight of the total composition.
Suitable rosin acid derivatives are based on wood rosin or its hydrogenated derivative or disproportionated rosin; modified rosins such as phenolic, maleic or maleic ester condensates are also suitable. These compounds arP
; soluble in water as their alkali metal or ammonium salts or as salts with volatile amines.
Preferred alkali metals are lithium, sodium and po-tassium and a preferred volatile amine is morpholine. If an ammonium or volatile-amine salt is used, the ammonia or , . , ``' . .
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-volatile amine is removed from the co~position during the heating process, neutralisation and washing procedures.
Suitable sorbitan esters include those derived from ~atty acids having 12 to 22 carbon atoms. The estër may be a ~lono-, di or tri- ester. Preferred esters are he mono-, di and tri-laurate, -oleate and -stearate.
The organic c~rrier may be a single compound or it can be a mixture of compounds whlch give a mixed melting point below 100C., preferably in the range of ~0 to 100C. It is not necessary for the mixture of compounds to have a sharp melting point which, of course, a single com-pound would have, but it may melt over a range of a few degrees, e.g. over 15 - 20 centigrade degrees.
The choice of organic carrier will largely be governed by the needs Qf the system in which the granules are to be used to ensure adequate solubility in and compatibility with the solvent and resin or polymer respectively.
Examples of suitable water-insoluble organic carriers in-clude fatty alcohols, such as cetyl alcohol and stearyl alcohol; carboxylic acids such as stearic acid, behenic acid, N-dodecyl phthalamic acid, N-octyl phthalamic acid and N-stearyl phthalamic acid~ fatty esters such as cetyl palmitate; fatty amides such as oleamide and palmitamide;
fatty esters of polyols such as hardened castor oil; ben-zoic acid esters of polyols; phthalate esters such as dicyclohexyl phthalate; alkylimides such as N-dodecyl phthalimide and N-octyl phthalimide; and alkyl hydantoins such as 3-stearyl-5,5-dimethyl hydantoin and l-hydroxy-ethyl-e-stearyl-5,5-dimethyl hydantoin~
In addition to using single compounds, mixtures of compounds may be used, such as mixtures of those specified above and mixtures containing compounds which may melt above 100C., but give rise to mixtures which melt below 100C., e.g. a mixture with cholesterol and magnesium 79~

behenate. Resinous materials which soften to give highly immobile liquids cannot satisfactorily be used alone. How-ever, these compounds can be used in mixtures with the above organic carriers, especially the fatty amides and fatty alcohols. Such resinous materials which may soften above or below 100C. are typified by the following com-pounds - hydrocarbon resins such as Hercures ~.80, A.100, A.130 and A.150 (Hercures is a Trade Mark), zinc rosina~e and rosin esters.
If desired, an aqueous protective colloid may be added to the mixture to provide more uniform granule size ~ distribu~ion. If used, it may be added in such an amount '~ as will form a solution of 0.1 to 5~ w/w, but preferably 0.5 to 2% w/w based on the amount of pi~ment plus organic carrier. Suitable protective colloids include, for example, cellulose derivatives such as hydroxyethyl cellulose and hydroxypropyl cellulose, pvlyvinyl alcohol, polyethylene oxide, polypropylene oxide, copolymers of ethylene oxide and propylene oxide, adducts of ethylene oxide or propyle-ne oxide, vinyl pyrrolidone homo or copolymers or mixtures of these compounds. The preferred compounds are those o the hydroxyethyl cellulose type as exemplified by the Natrosol range of the Hercules Powder Company (NATROSOL
is a Trade Mark).
The aqueous pigment dispersion may be one obtained directly from an aqueous preparation, for example, an azo coupling. Alternatively, the dispersion may be a redispers-ed pigment powder. In any of these cases the rosin acid or a salt thereof may be present during the preparation of the aqueous pigment dispersion. Alkali metal rosinates can be used to aid the dispersion of a presscake or powder into water. In the dispersion the pigment concentration is preferably at about 5~ W/W in water.
Suitable pigments include azo, azo metal salts, azo-`,:

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methine, azomethine metal complexes, anthraquinone,phthalocyanine, nitro, perinone, perylene, dioxazine, thioindigo, isoindolinone or quinacridone pigments.
The. amounts of the various components may vary over a wide range. The amount of pigment may be from 40 - 75%, pre~erably from 50 - 60% by weight. The amount of rosin acid may be from 5 - 25%, preferably from 10 - 25% and more preferably from 10 - 20~ by weight. The amoun~ of sorbitan ester may be from 5 - 30~, preferably from 10 -20~ by weight. If high amounts of sorbitan esters are used then it is preferable to use the solid esters, es-pecially sorbitan tristearate. The amount of carrier may be from 5 - 50~, preferably from 20 ~ 30% by weight.
The process of the inventLon may be carried out in various ways, and the pigment dispersion may be contacted with the organic carriex and sorbitan ester before or after heating.
The rosin acid may be dissolved separately and then added to the pigment dispersion, or it may be dissolved in the presence of the pigment dispersion, using the appropriate amount of alkali in each case. The rosin is preferably added to the pigment dispersion before the other components. It is especially preferred that the pig-ment and rosin are contacted under alkaline conditions be-fore the pigment and organic carrier are contacted at a temperature above the melting point of the organic carrier.
The sorbitan ester, (which may be a liquid or a solid at ambient temperature) and the organic carrier may be ini-tially contacted with the pigment dispersion at a temperature above or below their melting points.
The pH may be lowered to below 8 at any time aftex the pigment and rosin derivative have been contacted at a - pH of 8 - 11. Preerably the rosin derivative and pigment are kept at a pH of 8 - 11 for at least 10 minutes before .~
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lowering the pH to below 8. The pH may be lowered at any time from when cold and before th~ addition of the other components to when hot and all the other components have been added. Preferably the pH is lowered at a temperature above the melting point of the sorbitan ester but beore the addition of the organic carrier.
If a protective colloid is used it may be added at any stage, but it is preferably added before the carrier and pigment are contacted at a temperature above the melt-ing point of the carrier. It is further pre~erred that the protective colloid is added after addition of the rosin acid derivative to the pigment dispersion but before the sorbitan ester or carrier have been added.
If desired, a soluble salt of a metal of Group II or III of the Periodic Table may be added before or after the pH has been lowered. The addition of the metal salt assists in the production of granules at higher pH values.
The particle size of the resulting granules may be up to 5 rnm diameter or larger, but is preferably from 0.1 to 2 mm diameter. The particle size can be controlled by varying the stirring rate of the mixture - more violent agitation gives faster formation of smaller granules.
Typical stirrer types are those known as paddle, propeller, gate or bar stirrers. Important features of the stirring are the rate of stirring, velocity of the outer edge ~tip velocity) and the degree of turbulence; the latter can also be influenced by the insertion of suitable baffles in the vessel.
High energy mixers of the rnixer/ernulsi~ier type such as those based on fast rotor blades in a shear head - e.g.
as manufactured by Silverson Machines Ltd., Bucks., Eng-land, can be used under certain circurnstances: the ~ap between rotor blades and shear head must be sufficient, at least 1 - 2 mrn. and any holes in the shear head should ;.

be ~ 1 mm: this avoids smearing and build-up of the com-position into a mass at the head. Such suitably modified heads produce e~cellent granules of small diameters - less than O.S mm. even in the absence of a protective colloid.
Such mixers are most efficient in achieving good rates of conversion at the higher ~ pigment compositions; they are also very effective in producing good yields of granules with the azo metal salts which give poor conversion to granules with less turbulent stirring.
The free flowing nature of the products may be fur-ther enhanced by the additinn of a small % - up to 2~ - of a finely divided silica or silicate; the finely divided silicas are preferred, especially the organic surface modi-fied silicas, e.g. Aerosil Ro972 ex Degussa. Such organic modified silicas are readily mixed with the granules after drying by simple shaking or tumbling. The addition of such silicas especially improves the products to storage under compaction and at temperatures above ambient.
The products of the present invention can be used in most areas for application of pigments, for example, in colouring plastics, inks, paints etc. They axe particular-ly suitable for pigmenting PVC, and of special interest for use in PVC is the combination of sorbitan tristearate and dicyclohexyl phthalate.
The invention is illustrated by the following Exam-ples in which parts are parts by weight. In E~amples 1 -40 paddle type stirrers were used, wheras in subsequent examples the modified mixer/emulsifier type of stirrer was used.
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Example 1 To 50 parts of C.I. Pigment Yellow 13 as prepared by a conventional aqueous azo coupling was added sufficient potassium hydroxide to raise the pH to 9, and then a solution of 10 parts of Staybelite resin as its potassium salt was added. The pH of the resulting mixture was 10.
10 parts of sorbitan tristearate powder and 0.2 part hydroxyethyl cellulose (Natrosol 250 H R~ were then added and the mixture was stirred and heated to 85C. The pH was then lowered to 5 by adding 2N hydrochloric acid and thereafter 30 parts of dicyclohexyl phthalate were added.
The mixture was stirred for 2 hours at 85C and the re-sulting granules were all recsvered by filtration on a 100 mesh tB.S.) sieve, washed with water to remove inor-ganig salts and dried at 50C. This product of size distribution between 0.5 mm and 1.5 mm diameter could be readily dispersed into a plasticised P.V.C. compound.
Com~arative Examples lA and lB
The procedure followed in Example 1 was repeated with the variations indicated in Table 1.
Table 1 __ . . _ Hydrogenated Sorbitan Dicyclo-Pigment Wood Trist- hexyl Rosin _ _ earate phthalate Example 1 50 10 10 30 " lA 50 10 __ 40 50 2.5 10 37.5 T~e products obtained from Examples 1~ and ls had in-,erior dispersion in P.V.C compared to products prepared as Example 1.
' The size distribution of the resulting granules in Example lA was extremely wide with up to 30~ passing through the 100 mesh sieve at filtration and consequently the recovery of product was low.

Examples 2 - ll The procedure following in Example 1 was repeated, except that the dicyclohexyl phthalate was replaced.by the carriers indicated in Table II. Granule size and proper-ties were similar to Example l.
Table II

. ~ . , . , Example 2 10% hydrogenated wood rosin *
90% hydrogenated tallow amide Exa~ple 3 50% hydrogenated wood rosin 50~ hydrogenated tallow amide Example 4 80~ hydrogenated wood rosin 20% hydrogenated tallow amide Example S fatty ester (Cithrol CSP ex Croda Chemicals) Example 6 Neopentyl glycol dibenzoate Example 7 Glyceryl tristearate Example 8 Ester (Voidox ex Guardian Chemical Corp.) Example 9 Oleamide (Crodamide 0 ex Croda Chemicals) Example 10 Stearic Acid Example 11 Triphenyl phosphate . ~ .
* In each case the hydrogenated wood rosin and the - hydrogenated tallow amide were melted together and then solidified befvre addiiion.

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Examples 12 - 14 The procedure followed in ~xample 1 was repeated, ex-cept that oleamide was used in place o~ the dicyclohexyl ph~halate and the partC. used were as shown in Table III.
Granule diameters were between 0.5 ~ 2.5 mm. The products could be dispersed into lithographic ink medium.
Table III

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Hydrogenated¦ Sorbitan ExamplePigment Wood trist- Oleamide Rosin earate 12 50 10 lO 7 13 50 lO 5 12 14 50 5 lO 12 ' Examples 15 - 17 ':, The procedure followed in Example 9 was repeated, ex-cept that the sorbitan tristearate was replaced with dif-ferent sorbitan fatty acid esters, as shown in Table IV.
Granule diameter was similar to that obtained in Example l; the products could be dispersed into a plasticised PVC compound.

Table IV

_ , . .... ...... __ ._. _ Example 15 Sorbitan monolaurate " 16 Sorbitan monostearate 17 Sorbitan mono-oleate , Exam~le 18 The procedure of Example 1 was repeated, except that the slurry of C.I. Pigment Yellow 13 was replaced by a slurry of C.I. Pigment Yellow 17. Similar results were obtained.

Example 19 The procedure of Example 1 was repeated, except that the slurry of C.I. Pigment Yellow 13 was replaced by a sluxry of C.I. Pigment Yellow 83. Similar results were obtained.
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Example 20 To 50 parts C.I. Pigment Yellow 93 in the form of a 25~ w/w aqueous presscake was added 600 parts water and the mixture stirred to homogenise, then a solution of 10 parts of Staybelite resin as its potassium salt added.
The resultant pH of the mixture was 9.5. 10 parts sorbi-tan tristearate powder and 0.5 parts hydroxy ethyl cel-lulose powder (Natrosol 250MR) were added and the mixture stirred and the temperature raised to 85C. The pH was adjusted to 5 with 2~7 hydrochloric acid and 30 parts of dicyclohexyl phthalate were added. The mixture was stirr-ed for 2 hours at 85~C. and the resultant granules reco-vered by filtration on a 100 mesh sieve washed with water to remove inorganic salts and dried at 50C. Granules of O.2 mm - 1 mm diameter were produced; these could be rea-dily dispersed into a plasticised PVC compound.

Example 21 The procedure followed in Example 20 was repeated, except tha~ the ammonium salt of Staybelite Resin was used instead or the potassium salt. The product was si~i-~ 7~

lar in appearance, but dispersibility into the plasticised PVC was slightly superior to Example 20.

xample 22 The procedure followed in Example 20 was repeated, except that the morpholine salt of Staybelite Resin was used instead of the potassium salt. The product appearance and performance were as Example 21.

Example 23 The procedure followed in Example 20 was repeated, except that C.I. Pigment Red 144 was used instead of C.I.
Pigment Yellow 93. The hydroxyethyl cellulose was reduced to 0.2 parts. A product of granule diameters 0.2 mm - 0.3 mm diameter was obtained; dispersion into plasticised PVC
was readily achieved.

Examole 24 , . . . .
To 50 parts C.I. Pigment Green 7 in the form of a 25% w/w aqueous presscake was added 600 parts water and the mixture stirred to homogenise, then a solution of 7.5 parts Staybelite Resin as its potassium salt added. The resultant pH of the mixture was 9.5. 7.5 parts of sorbi-tan tristearate powder, 0.5 parts hydroxyethyl cellulose powder tNatrosol 250HR) were added and the mixture stirr-ed and the temperature raised to 85C. The pH was adjust-ed to 5 with 2N hydrochloric acid and 25 parts dicyclohe-xyl phthalate added~ The mixture was stirred for 2 hours at 85C. and the resultant granules recovered by filtra-tion on a 100 mesh sieve, washed with water to remove inorganic salts and dried at 50C. Granules of 0.5 - ~ mm diameter were obtained: these could be readil~ incorporat-ed into an alcohol solvent nitrocellulose binder liquid 7~

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packaging ink.

Example 25 To 50 parts C.I. Pigment Blue 15.1 in the form of a 25% w/w aqueous presscake was added 600 parts water and the mix~ure stirred to homogenise, then a solution of 7,5 parts Staybelite Resin as its potassium salt added.
The resultant p~ of the mixture was 9.5. 15 parts af sox- --bitan tristearate powder, 0.5 parts hydroxyethyl cellulo-se powder (~atrosol 250MR) were added and the mixture stirred and the temperature raised to 85C. The pH was adjusted to 5 with 2N hydrochloric acid and 18.75 parts Stearic acid, and 18.75 parts dicyclohexyl phthalate added. The mixture was stirred for 2 hours at 85C. and the resultant granules recovered by filtration on a 100 mesh sieve, washed with water to remove inorganic salts and dried at 50C. The product of granule size range 0.5 mm - 1 mm diameter could be readily dispersed into plasti-cised PVC and rigid PVC compoundsO
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Example 26 The procedure followed in Example 25 was repeated except that the stearic acid was replaced with dicyclo-hexyl phthalate. Similar results were obtainedO

Example 27 The procedure followed in Example 26 was repeated except the C.I. Pigment Blue 15.3 was used in place of C.I. Pigment Blue 15.1. The granules of 1.5 mm - 2 mm diameter could be dispersed into lithographic ink medium.

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Example 28 To So parts C.I. Pigment Orange 34 as prepared by a conventlonal aqueous azo coupling was added sufficient potassium hydroxide to raise the pH to 9, and then a so-lution of 8 parts of Staybelite Resin as its potassium salt was added. The pH of the resulting mixture was 9.5.
10 parts of sorbi~an tristearate powder and 0.5 parts hy-droxy ethyl cellulose (Natrosol 250HR~ were then added and the mixture stirred and heated to 85C. The pH was then lowered to 5 by adding 2N hydrochloric acid and thereafter 32 parts of dicyclohexyl phthalate were added.
The mixture was stirred for 2 hrs. at 85C and the result-ing granules were recovered by filtration on a 100 mesh sieve, washed with water to remove inorganic salts and dried at ~0C. These granules of diameter O.5 mm - 2.5 mm diameter could be xeadily dispersed into a plasticised PVC compound.

Example 29 The procedure of Exam~le 28 was repeated e~cept that the 32 parts dicyclohexyl phthalate were replaced by a mixture of 16 parts stearic acid and 16 parts dicyclohexyl phthalate. The resultant granules o~ 005 mm - 1.5 mm dia-meter showed excellent dispersibility into a rigid PVC
compound.

Example 30 18 parts o~ a presscake of C.I. Pigment Red 166 were dispersed into 250 parts of water. 0.27 parts hydroxyethyl cellulose, 2.4 parts Staybelite resin (as a 10% parts by weight aqueous solution o~ its potassium salt) and 2.4 parts sorbitan tristearate were added and the mixture heated with stirring to 85C. The mi~ture was then ad-~7~

justed to pH5 and 7.2 parts dicyclohexyl phthalate added.
Stirring was continued for 4 hours at 85C. The product was then isolated on a 60 mesh B.S~ sieve, and dried at 50C; the granule at 60% parts by weight pigment could be readily incorpQrated into a plasticised PiV.C. compound.
At the isolation stage 90% of the input material (pigment, resin, sorbitan ester, and dicyclohexyl phthalate) was retained on the above 60 mesh sieve whilst 10~ passed through during isolation and washing; this 10~ was re-tained on a fine filter and returned to a granule prepa-ration as above at a known input of pigment and organic compounds.

Examples 31 - 32 The procedure of Example 20 was followed exactly except that the hydroxyethyl cellulose was replacedby 0.75 part (Example 31) and 3.75 parts (Example 32) of a poly-oxyethylene oxypropylene monostearate (G.2162 ex Honey-well Atlas). The product was granules of a generally spherical nature of size range shown 1 - 5 mm for Example 31 and 0.5 - 2 mm for Example 32.

Example 33 The procedure of Example 1 was repeated except that on reaching 85C the pH was adjusted to 8 instead of 5 and then a solutionof 7.5 parts of calcium chloride dihy-drate in 50 parts water was added. The temperature and stirring were maintained and 12 parts of dicyclohexyl phthalate added. Granules similar to Example 1 were ob-tained.
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` -17-Example 34 The procedure of Example 31 was repea~ed except that the pH was adjusted to 7 and a solution of 6 parts of zinc chloride in 50 parts of water was added. A product similar to Example 31 was obtained.

Examples 35 - 40 The procedure of Example 1 was followed except tha~ the hydroxyethyl cellulose was replaced by the listed non-ionic agent at the given amount.

Exam~leNon-lonic A~ent Parts 35poly(oxypropylene-oxyethylene)l 1.25 ~6poly(oxypropylene-oxyethylene)l 2.50 37poly(oxypropylene-oxyethylene)2 1.25 38 ethoxylated nonyl phenol3 1.25 39 ethoxylated fatty alcohol 2.50 ethoxylated fatty alcohol5 2.50 1) Supronic E.400 ex Allied Colloids L~d.

2) Supronic E.800 ex Allied Colloids Ltd.

3) Synperonic NP.9 ex I.C.I Ltd.

4) Synperonic A.9 ex I.C.I. Ltd.

5) Synperonic A.20 ex I.C.I. Ltd.

Example 41 To 50 parts of C.I. Pigment Yellow 13 as prepared in a conventional aqueous a~o coupling was added sufficient ammonia to give a pH of 8.5 and then a solut~on of 7.1 parts of Staybelite resin as its a~monium salt was added, The pH of the resultant mixture was 9.5. 8.9 parts sorbi-tan tristearate powder was then added and the mixture stirred using a modified mixer/emulsifier of the type . ~

descri~ed in the text, and heated to 75C. The pH was then lowered to 5 by adding 5N hydrochloric acid and the-reafter 28.3 parts of dicyclohexyl phthalate was added.
The mixture was stirred for 15 min. at 75C, and the re-sulting granules were recovered by filtration on a 200 mesh (B.S.) sieve, washed with water to remove inorganic salts and dried at 50C. The resulting non-dusting gra-nules of 0.1 - 0.5 mm diameter could be readily dispersed into a plasticised P.V.C. compound.

Example 42 To 50 parts dry weight of C.I. Pigment Yellow 93 presscake was added 600 parts water and the mixture stirred to homogenise, then a solution of 10 parts of Staybelite resin as its ammonium salt added. The resultant pH of the mixture was 9.5. 10 parts Sorbitan tristearate powder was then added and the mixture stirred using a modified mixer/emulsifier of the type described in the text, and heated to 85C. The pH was then lowered to 5.0 by adding 5N hydrochloric acid and thereafter 30 parts of dicyclohexyl phthalate was added. The mixture was stirred for 5 min. at 85C and the resulting granules were re-covered by filtration on a 200 mesh (B.S.) sieve, washed with water to remove inorganic salts and dried at 50C.
The product appearance and properties were similar to those of Example 41.
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Exam~le 43 To 50 parts dry weight of C.I. Pigment Red 144 was added 1000 parts water and the mixture stirred for 30 mins., then added 8 parts of Staybelite resin as its ammonium salt. The resultant pH of the mixture was 9.5.
10 parts Sorbitan tristearate powder and 0.1 parts hy-droxyethyl cellulose were then added and the mi~ture `:~
stirred using a modi~ied mixer/emulsifier of the type de-scribed in the text and heated to 90C, then held for 5 mins. The pH was then lowered to 5.0 by adding 5N acetic acid and thereafter 32 parts of dicyclohexyl phthalate wexe added. The mixture was stirred for 5 mins. at 90C
and the resulting granules were recovered by filtration on a 200 mesh (B.S.) sieve, washed with water ~o remove inorganic salts ard dried at 50~C. The product was fine granules o 0.1 - 0.5 mm diameter and was easily dispersed into a plasticised P.V.C. compound. Addition of 1% parts by weight of an organic surface treated silica - Aerosil R.972 (ex. Degussa) improved the free flowing nature of the granules and especially improved these properties to any change on storage.

Example 44 To 50 parts dry weight of C.I. Pigment Green 7 press-cake was added 2500 parts water and the mixture stirred for 30 min~. Then a solution of 7.5 parts of Staybelite resin as its potassium salt added and the mixture stirred for 2 hours using a modified mixer/emulsirier of the type described in the text, the resultant pH of the mlxture was 9.5. 7.5 parts sorbitan tristearate and 0.5 parts hydroxy-ethyl cellulose were added and it was heated to 85C. The pH was then low~red to 5.0 by adding 5N hydrochloric acid and thereafter 35 parts of dicyclohexyl phthalate was added. The mixture was stirxed for 1 min. at 85C and the resulting granules were recovered by filtration on a 200 mesh (B.S.) sieve, washed with water to remove inorganic salts and dried at 50C. The granules of 01 - 0.5 mm dia-meter were easily dispersed into a plasticised P.V.C.
compound.

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Example 45 The procedure in Example 44 was repeated increasing the Staybelite to lO parts and reducing the dicyclohexyl phthalate to 5 parts. The fine non-dusting product could be readily dispersed into a plasticised P.V.C. compound.

Examples 46 - 51 The procedure in Example 41 was repeated except that the ammonium salt of Staybelite resin was replaced by the potassium salt of resins indicated in the table. Granule size and properties were similar to Example 41.
8xam~1~ Resin ~y _ ~rade ~b~ Type Acid Value Supplier 46 Burez 421 Disproportion- 173 Tenneco Malros - ated 47 Pentalyn 255 Maleic conden- 210 ~ercules Powder sate Co.
48 Ennesin A.100 Phe~olic 100 Leon Frenkel Ltd.
49 Ennesin ~.57W Phenolic 120 Leon Frenkel ~td.
Albertol RP.692 Maleic conden- 115 Resinous Chemi-sate cals Ltd.
51 Kelrez 42-402 Phenolic 135 Croda Chemic~ls . Examples 52 - 53 The procedure in Example 42 was repeated except that the ammonium salt of Staybelite resin was replaced by the potassium salt of the resins indicated in the table. Gra-nule size and properties were similar to Example 42 .. Exam ~ ~ Resir~
: 52 Albertol KP.692 . 53 Kelrez 42-402 ~ ~ .

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Examples 54 -_55 The proc~dure of Examples 52 and 53 were rPpeated except that the resin was increased to 15 parts and the dicyclohexyl phthalate reduced to 25 par~s~ Similar pro ducts were obtained.

Exam~le Resin 54 Albertol KP.692 Kelrez 42-402 Example S6 To 50 parts of C.I. Pigment Yellow 17 as prepared in a conventional aqueous azo coupling was added sufficient potassium hydroxide to raise the pH to 7.5 and then a solution of lO parts of Kelrez 42~402 as its potassium salt was added. The pH of the resultant mixture was lO.
10 parts of Sorbitan tristearate powder was then added and the mixtllre stirred using a modified mixer/emulsifier of the type described in the text and heated to 70C. The pH was then lowered to 5 by adding 5N hydrochloric acid and thereafter 30 parts of dicyclohexyl phthalate was ` added. The mixture was stirred for 5 mins. at 70C and the resulting granules were recovered by filtration on a 200 mesh (B.S.) sieve, washed with water to remove in-organic salts and dried at 40C. The resulting non dusting granules of 0.1 - 0.5 mm diameter could be readily dis-c persed into a P.V.C. compound.

E~ample 57 The procedure in Example 54 was repeated except that C.I. Pigment Yellow 83 was used instead of C.I. Pigment Yellow 17. A product of granule diameters 0.1 - 0.5 mm diameter was obtained; dispersion into a pla~ticised ~ , :
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-2~-P.V.C. c~mpound was readily achieved.

Example 58 The procedure of Example 28 was followed except that the Staybelite resin was added as a solution of its ammo-nium salt and stirring was by the modified mixer/emulsi-fier. Granules of 0.1 - 0.5 mm diameter were produced, these could be easily dispersed into a plasticised,P.V.C
compound. 1% by weight of a finely divided silica (Cabo-sil M.5) was tum~led with the above granules: this treat-ment improved their free-flowing properties. When samples of the silica treated and untreated granules were stored at SQC for 5 days the untreated product showed a greater tendency to produce aggregates o granules; on cooling to ambient 18-20C the silica treated product was as free-flowing as before storage whereas the untreated pro-duct required several days to recover its properties.

Example 59 To 50 parts of C.I. Pigment Yellow 62 as a 3% parts by weight aqueous slurry, prepared by conventional coup-ling and addition of calcium chlcride, 12.5 parts sorbi-tan tristearate was added and the temperature raised to 85C while stirring with the modified mixer/emulsifier.
The temperature was maintained at 85C for 30 mins. and 37.5 parts of dicyclohexyl phthalate was added. Stirring was continued for a further 30 mins. before isolation of the granules of 0.1 - 0.5 mm diameter on a 200 mesh (B.S.) sieve, washing and drying at 50C. This product was readi-ly dispersed into a plasti;-ised P.V.C. compound or a low density polyethylene compound.

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Example 60 A pigment composition consisting of 86 parts C.I.
Pigment 48 (calcium salt) and 14 parts Staybelite xesin, prepared by a conventional coupling process in the pre-sence of the resin to give a 3.3~ parts by weight aqueous slurry of this composition, was stirred on the modified mixer/emulsifier with 1 part Natrosol 250M~ and 25 parts sorbitan tristearate. The mixture was then heated ~o 85C and 75 parts dicyclohexyl phthalate added; the stirr-ing was continued for 3 minutes and the product isolated by sieving etc. as for Example 59. The resultant granu-les of 0.1 - 0.5 mm diameter were readily dispersed into a plasticised P.V.C. composition.

Claims (9)

What we claim is:

1. A process for the production of a pigment composition in a non-dusting form which comprises contacting an aque-ous dispersion of an organic pigment with a) a solution or dispersion of an alkaline soluble rosin acid derivative having an approximate acid value in the range 100 - 250 at a pH of from 8 to 11 b) a sorbitan ester, and c) a water-insoluble organic carrier having a melting point below 100°C at a temperature above the melting point of both the sorbitan ester and the organic carrier, reducing th pH to below 8, stirring the com-position until the pigment, rosin derivative, sorbitan ester and organic carrier are associated in generally spherical granules, and recovering the resulting gra-nules, the amounts of ingredients being 40 - 75% pig-ment, 5 - 25% rosin acid, 5 - 40% sorbitan ester and 5 - 50% carrier, all percentages being based on the weight of the total composition

2. A process as claimed in Claim 1, in which the rosin acid derivative is based on wood rosin or its hydrogenated derivative or disproportionaled rosin.

3. A process as claimed in Claim 1, in which the sorbi-tan ester is derived from a fatty acid having 12 to 22 carbon atoms.

4. A process as claimed in Claim 1, in which the orga-nic carrier is a single compound or a mixture of compounds which give a mixed melting point below 100°C.

5. A process as claimed in Claim 1, in which a protec-tive colloid is added to the mixture.

6. A process as claimed in Claim 1, in which the amount of pigment is from 50 - 60% by weight of the total com-position.

7. A process as claimed in Claim 1, in which the amount of sorbitan ester is from 10 to 20% by weight of the to-tal composition.

8. A process as claimed in Claim 1, in which the amount of organic carrier is from 20 to 30% by weight of the to-tal composition.

9. A process as claimed in Claim 1, in which up to 2%
by weight of a finely divided silica or silicate is added to the mixture.