EP1720948A1

EP1720948A1 - Beta copper phthalocyanine composition and conditioning process leading thereto

Info

Publication number: EP1720948A1
Application number: EP05707798A
Authority: EP
Inventors: Thomas Healy; Ian Andrew Lambie; Laura Knight
Original assignee: Ciba Spezialitaetenchemie Holding AG; Ciba SC Holding AG
Current assignee: BASF Schweiz AG
Priority date: 2004-01-29
Filing date: 2005-01-19
Publication date: 2006-11-15
Also published as: TW200538516A; WO2005075577A1

Abstract

The invention relates to a process for preparing a phthalocyanine pigment, comprising heating to a temperature of from 50 to 200°C a slurry comprising: a phthalocyanine consisting of primary particles having an average particle size of maximally 0.5 µm, preferably an average particle size of from 0.01 to 0.3 µm; from 4 to 500% by weight, based on the weight of the phthalocyanine, of a neutral organic conditioning liquid capable of forming with water an azeotropic mixture which has a lower boiling point than water and comprises from 4 to 96% by weight of water in the gas phase at standard pressure; from 0.1 to 5% by weight, based on the weight of the phthalocyanine, of one or more compounds selected from the group consisting of non-aromatic hydrocarbons either unsubstituted or substituted by 1 or 2 hydroxy and /or ether groups, which compounds have at least 12 C atoms and a boiling point of from 150 to 350°C, preferably from 200 to 330°C, most preferred from 240 to 310°C; optionally up to 30% by weight, based on the amount of non-aromatic, unsubstituted or substituted hydrocarbons, of one or more aromatic, unsubstituted and/or optionally substituted hydrocarbons having at least 12 C atoms and a boiling point of from 150 to 350°C, preferably from 200 to 330°C, most preferred from 240 to 310°C; from 1 to 50 parts by weight, per part by weight of neutral organic conditioning liquid, of a basic aqueous solution having a pH value of ≥ 9, preferably having a pH value of from 10 to 13. The resulting compositions, preferably also comprising minor amounts of a resin and/or a phthalocyanine derivative, are also claimed. The compositions lead to an excellent flowability, especially at low shear in oil inks.

Description

Beta copper phthalocyanine composition and conditioning process leading thereto

The invention relates to a process for conditioning copper phthalocyanine so as to obtain pure β crystals in a columnar shape. The instant process consists in heating finely ground crude copper phthalocyanine in a basic, aqueous alcohol, ketone or ester further comprising a small quantity of low polar, low volatile, low aromatic ink solvents. The resulting highly concentrated pigment compositions are also an object of the invention, as well as their use for preparing coatings and inks.

US 2,857,400 discloses a process for the comminution of pigments by dry-milling under attrition and shear, followed by violent agitation slurried in an organic liquid. The pigment is then always isolated in dry powder form.

JP-A-11/60982 discloses a process for preparing printing inks by wet-milling crude copper phthalocyanine in a low-boiling aqueous solvent using beads of size from 0.2 to 0.5 mm. However, the maximal concentration of copper phthalocyanine reaches only 40% by weight.

US 2,982,666 discloses the kneading of crude pigments in the presence of organic conditioning agents and large quantities of salt. Under controlled conditions, it is possible to obtain nearly isometric crystals with high tinctorial strength, gloss and flowability. However, it is disclosed that the organic conditioning agents, which are selected from glycols or derivatives thereof, have no solvent action whatsoever and do not act to convert α to β crystals of copper phthalocyanine.

EP0638615A2 further discloses that excellent fluidity, gloss and tinting strength are obtained by kneading in the presence of copper phthalocyanine ammonium sulfonates, which prevent crystal growth and re-aggregation during kneading. However, EP0638615A2 does not enable the preparation of inks with a pigment concentration of more than 40% by weight.

EP 0699720 A1 discloses a process for preparing α-phase metal phthalocyanine pigments, wherein an acid treated crude metal phthalocyanine is dry-milled in the presence of a stabilizer, preferably aminoalkyl-sulfonamide substituted phthalocyanines, followed by finishing preferably in water-immiscible organic solvents such as esters of carboxylic acids, and final isolation of the α-phase metal pigment. Ketones, lower alcohols, glycols and esters thereof are disclosed not to form the β-phase under such conditions.

JP-A-10/001 619 discloses a copper phthalocyanine composition for rotogravure inks comprising a mixture of α and β copper phthalocyanines obtained by dry-grinding, and a dialkylamino or aminoalkyl-sulfonamide substituted phthalocyanine which is added after grinding. The fluidity and storage stability are disclosed to be improved, as compared with the products of the prior art treated with crystallisation solvents such as water, xylene, or aqueous alcohols.

EP 0422907 A2 discloses copper phthalocyanine pigment compositions comprising a mixture of α and β copper phthalocyanines obtained by dry-grinding crude copper phthalocyanine in the absence of a milling aid but in the presence of a very broad choice of phthalocyanine derivatives, amongst them bis-diethylaminomethyl copper phthalocyanine. EP 0629668 A1 slightly modifies this method by milling with only one part of the additive and adding the remaining part after milling. The products are disclosed to have excellent fluidity, tinting strength and dispersion stability in coating and ink compositions.

However, copper phthalocyanine in the pure β phase is much preferable and most desirable for coloristic and stability reasons.

JP-A-60/133065 discloses the preparation of β copper phthalocyanine by wet-milling crude copper phthalocyanine together with a phthalocyanine derivative, an inorganic salt, a conditioning liquid and a phase-directing solvent, thus increasing the specific surface area. For example, the conditioning liquid is a polyalkylene glycol and the phase-directing solvent is acetone or xylene. JP-A-07/310024 discloses a process for producing pure β copper phthalocyanine by dry grinding crude copper phthalocyanine so as to obtain a mixture of α and β phases, followed by treating with an organic solvent to obtain the β phase. Suitable solvents include lower alcohols, ketones and esters as well as mineral spirits, amides and mixtures therof. The preferred embodiment uses a ternary mixture of isopropyl alcohol, xylene and water in a ratio of about 10: 1 : 7. Essential are the addition of copper phthalocyanine derivatives, amongst them dialkylamino copper phthalocyanines, in order to suppress crystal growth, as well as a final mechanical dispersion step.

EP0317876A2 discloses a process for producing an aqueous dispersion of pigmentary, isometric β copper phthalocyanine, by dry-milling crude copper phthalocyanine together with a small amount of a phase-directing solvent, adding the milled product to an emulsion comprising a second phase directing solvent, wet milling the emulsion and isolating the pigment as an aqueous presscake. Suitable solvents are amongst many others aliphatic or aromatic hydrocarbons, aliphatic Ci-Cealcohols, C₃-Ceketones and C₂-C₄diols or ethers thereof. Mineral spirits and ethylene glycol monobutyl ether are preferred. Only solvents immiscible or only partially miscible with water are suitable as the second phase-directing solvents.

EP 0407831 A1 discloses a similar process, but granulates the product in a two- phase water/ butoxyethanol system instead of the second wet-milling step.

EP 0803545 A2 discloses a process for producing β copper phthalocyanine by dry- milling at high temperature followed by treating in a liquid mixture of water and an organic solvent. Suitable are many solvents and mixtures thereof (without any specific example of a mixture), amongst them mineral spirit and alcohols. The colour strength, clearness, fluidity and hue are disclosed to be improved as compared with conventional wet-milling with salt, and the aspect ratio is lower than when milled at lower temperatures. However, high temperature milling requires an inert gas and is also problematic in many other aspects. WO 99/54410 discloses a process for preparing β copper phthalocyanine by milling crude copper phthalocyanine together with a resin, isolating the milled mass and conditioning under various conditions, especially in azeotropic aqueous alcohols under basic conditions. Copper phthalocyanine derivatives may be added at any stage to improve the performance of the resulting pigments, for example dimethyl- aminomethyl copper phthalocyanine during the final processing stage. However, though this method gives excellent dispersibility, colour strength and gloss in inks, the acicular products are still not entirely satisfactory with respect to their rheology, as compared with isometric products obtained by salt kneading.

EP0819740A1 discloses a process for producing a printing ink comprising low aspect ratio β copper phthalocyanine by dry-milling crude copper phthalocyanine with 20-80% by weight of a resin and heating the mixture in a printing ink solvent.

It has now surprisingly been found, that the rheology of acicular β copper phthalocyanine can be considerably enhanced when pre-milled crude is conditioned under basic conditions in aqueous alcohols additionally comprising low polar, low volatile, low aromatic ink solvents. Especially the flowability at low shear and millbase viscosity are remarkable. Amazingly, both the gloss and the rheology are simultaneously improved.

Thus, the invention relates to a process for preparing a phthalocyanine pigment, comprising heating to a temperature of from 50 to 200°C a slurry comprising:

• a phthalocyanine consisting of primary particles having an average particle size of maximally 0.5 μm, preferably an average particle size of from 0.01 to 0.3 μm;

• from 4 to 500% by weight, based on the weight of the phthalocyanine, of a neutral organic conditioning liquid capable of forming with water an azeotropic mixture which has a lower boiling point than water and comprises from 4 to 96% by weight of water in the gas phase at standard pressure;

• from 0.1 to 5% by weight, based on the weight of the phthalocyanine, of one or more compounds selected from the group consisting of non-aromatic hydrocarbons either unsubstituted or substituted by 1 or 2 hydroxy and /or ether groups, which compounds have at least 12 C atoms and a boiling point of from 150 to 350°C, preferably from 200 to 330°C, most preferred from 240 to 310°C;

• optionally up to 30% by weight, based on the amount of non-aromatic, unsubstituted or substituted hydrocarbons, of one or more aromatic, unsubstituted and /or optionally substituted hydrocarbons having at least 12 C atoms and a boiling point of from 150 to 350°C, preferably from 200 to 330°C, most preferred from 240 to 310°C;

• from 1 to 50 parts by weight, per part by weight of neutral organic conditioning liquid, of a basic aqueous solution having a pH value of 9, preferably having a pH value of from 10 to 13.

The average particle size (length) is meant by weight distribution. Methods for determining the particle size distribution of particles are well-known in the art, for example from the light transmission of a highly dilute sample, by static light scattering (300-1500 nm) or by quasielastic light scattering (10-3000 nm). The relationship between the turbidity and particle radius of spheres is described by Mie's theory [M. Kerker The Scattering of Light and other Electromagnetic Radiation," in E. M. Loebl (ed.): Physical Chemistry, Academic Press, New York 1969)]. In any case, it is necessary first to obtain a good dispersion in order to avoid measuring aggregates instead of primary particles. Hence, the preferred method is to use transmission electron microscopy. The vast majority of the primary particles, such as > 95% by weight of the primary particles, has preferably a particle size of from 0.01 to 0.05 μm. Standard pressure is 1.01325 - 10⁵ Pa.

The phthalocyanine can be either unsubstituted or substituted by from 1 to 16 halogen atoms, especially chlorine and /or bromine, either metal-free or metallized, for example with copper, nickel or zinc. Preferred is copper phthalocyanine, especially unsubstituted copper phthalocyanine. There are in the art many well established processes for the preparation of phthalocyanines. Standard processes for the production of crude phthalocyanines are detailed in "Phthalocyanine Compounds" by Moser and Thomas, Rheinhold Publishing Corporation 1963, the disclosures of which are incorporated herein by reference. For example, crude copper phthalocyanine may be prepared by reaction of phthalic anhydride with urea and a copper salt in the presence of a catalytic amount of a transition metal compound such as ammonium molybdate, the reaction being carried out at elevated temperature in a high boiling aromatic solvent such as nitrobenzene or in the absence of a solvent in a "dry-bake" melt process.

Crude copper phthalocyanine generally has particles of size above 1 μm, typically ranging from 5 to 100 μm. Hence, such coarse crude phthalocyanines need to be milled before they can be used in the instant conditioning process. The milling technique is not particularly relevant, as long as it leads to a primary particle size within the instantly required range. Conventional grinding, attrition, kneading and other wet- or dry-milling methods with or without grinding auxiliaries are generally suitable. However, the preferred method is dry-milling, whereby it is understood that the phthalocyanine essentially retains the properties of a powder during milling. This is still the case when small quantities of liquids or low-melting materials are added, such as up to about 10% of liquids, based on the solid to be milled. It is most preferable to mill in the absence of any liquid.

It is not essential for the phthalocyanine consisting of primary particles having an average particle size of maximally 0.5 μm to have any particular crystal phase as starting material; on the contrary, any crystal phase can be used, such as mixtures of α and β crystal phases as usually obtained by dry-milling. It is preferable to use a phthalocyanine comprising at least 20% by weight of the α phase and at least 5% by weight of the β phase, most preferred from 45 to 65% by weight of the α phase. However, the phthalocyanine pigment obtained by the instant process is preferably essentially (at least about 90% by weight thereof, most preferred at least about 95% by weight thereof) in the β crystal phase.

As optional auxiliaries in the dry-milling step, resins and /or water-soluble salts are most suitable. It is preferable to use at least one kind of milling auxiliary, most preferable to use both resins and water-soluble salts, especially when the dry-milling method is used. Suitable equipment for dry-milling, such as for example rotating or vibrating ball mills, may work batchwise or continuously.

Grinding auxiliaries are materials used to aid the reduction in size of crude phthalocyanine using kneading, attrition, wet- or dry-milling technology. Grinding auxiliaries suitable for use in this invention include, for example, calcium chloride, sodium chloride, sodium sulfate, sodium formate, sodium acetate or other organic or any inorganic salt with or without crystal water, in particular alkali and earth alkali salts.

The preferred grinding auxiliaries are sodium chloride, sodium formate and sodium acetate. The grinding auxiliary is suitably used in an amount of up to 40% by weight, preferably from 1 to 30% by weight, most preferred from 5 to 20% by weight, based on the phthalocyanine weight. Generally, the grinding auxiliaries dissolve in the conditioning mixture, so that it is not necessary to remove them before conditioning. Higher amounts of grinding auxiliaries, such as the 2- to 10-fold of the phthalocyanine weight usual in the salt-kneading method, can also be used if desired. Generally, however, they will be removed or their amount reduced to an acceptable lower level for the conditioning step by usual methods, for example by washing with water.

Neutral organic conditioning liquids are polar hydrophilic solvents capable of forming a binary azeotropic mixture with water, with a suitable melting point below 25°C. Especially useful neutral organic conditioning liquids are at least partially miscible with water, with at least about 2 g of water soluble in 100 g of neutral organic conditioning liquid and preferably at least about 2 g of neutral organic conditioning liquid soluble in 100 g of water, each measured at 25°C. One can alternatively also use neutral organic conditioning liquids which are water-miscible in any ratio. The neutral organic conditioning liquid is generally used in an amount of from 4 to 500% by weight, based on the weight of the phthalocyanine, preferably from 10 to 200% by weight, in particular from 10 to 100% by weight, based on the weight of the phthalocyanine.

Thus, the neutral organic conditioning liquids are preferably selected from the group consisting of saturated and mono-unsaturated alcohols, ketones and esters having up to 8 C atoms, preferably from 2 to 6 C atoms, most preferred 3, 4, 5 or 6 C atoms. The azeotrope contains preferably from 20 to 80% by weight of water in the gas phase.

Suitable examples of neutral conditioning liquids comprise saturated or mono- unsaturated alcohols, ketones and esters, such as ethanol, n-propanol, isopropanol, n-butanol, isobutanol, amyl alcohol, cyclohexanol or other isomers of linear, branched or cyclic d-Cβ alcohols, ethyl acetate, butyl acetate, or other d-C^alcanoic Cι-C alkyl esters, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone or other dialkyl or cycloalkyl ketone, 2-methoxy ethanol, 2-ethoxy ethanol or other Cι-C₄alkoxy Cι-C₄alkyl alcohols. ^•'->

Preferred neutral organic conditioning liquids are ethanol, n-propanol, isopropanol, n-butanol, isobutanol and n-pentanol. Suitable weight ratios of neutral organic conditioning liquid to water in the conditioning aqueous slurry are from 50 : 50 to 1 : 99 by weight, preferably from 25 : 75 to 2 : 98 by weight, especially from 20 : 80 to 2 : 98% by weight, most preferred from 10 : 90 to 2 : 98% by weight. The respective amounts of neutral organic conditioning liquid and water are preferably chosen so that no phase separation occurs even when the miscibility with water is only partial. Suitable weight ratio of aqueous liquid (comprising water and organic conditioning liquid) to phthalocyanine is from 1 ^Λ : 1 to 20 : 1 by weight, preferably from 2 : 1 to 10 : 1 by weight, most preferred from 21 : 1 to 7 : 1 by weight.

The hydrophilic, neutral organic conditioning liquids are instantly used in combination with high boiling point, non-aromatic hydrocarbons and an aqueous base.

Non-aromatic hydrocarbons, either unsubstituted or optionally substituted by up to 2 hydroxy and /or ether groups, can be single compounds or preferably mixtures lacking or with a low content of aromatics, especially < 5% by weight, preferably < 2% by weight, most preferred < 1 % by weight of aromatics. Suitable non-aromatic hydrocarbons and oxygen-comprising derivatives thereof have at least 12 C atoms and a boiling point of from 150 to 350°C. Some of these are known as apolar high boiling ink solvents. Particularly useful examples thereof are petroleum distillates and aliphatic alcohols having at least 12 C atoms, preferably dodecanol ortridecanol and isomeric or homologue mixtures comprising them. However, diols and mono- or dialkyl ethers thereof also can be used. Non-aromatic hydrocarbons or oxygen-comprising derivatives thereof are generally used in an amount of from 0.1 to 6% by weight, preferably from 0.2 to 4% by weight, most preferred from 0.5 to 2% by weight, based on the phthalocyanine.

The instant apolar high boiling ink solvents have a suitable low volatility, so that they do at least in part remain in the pigment dispersion and do not disappear from the slurry into the azeotropic, gazeous phase. If the apolar high boiling ink solvent forms a ternary azeotrope with the conditioning liquid and water and the conditioning step is run at reflux, then it is necessary to increase its minimal amount accordingly, while the amount remaining in the final product should stay below the instant upper limit.

The presence of a non-aromatic, optionally substituted hydrocarbon is an essential point of the instant process; hence, it is critical it to be added sufficiently early before or during the conditioning process so that it can accomplish the desired effect. The best results are obtained when it is present throughout the solvent conditioning process. This is most easily obtained by adding the non-aromatic, optionally substituted hydrocarbon before the base, or eventually before the temperature reaches 50°C. Nevertheless, a minor but much weaker effect is still obtained by addition at a later stage, up to the azeotropic distillation of the neutral organic conditioning liquid. The instant low amount of non-aromatic, optionally substituted hydrocarbon may also already be added before or upon pre-milling.

In addition to the non-aromatic, optionally substituted hydrocarbons, there may optionally also be added aromatic hydrocarbons, which may if desired also be substituted. However, it is important that additional aromatic components do not signicantly alter the non-aromatic character of the mixture. Thus, it is adequate to add no more than about 30% by weight, based on the amount of non-aromatic, unsubstituted or substituted hydrocarbons, of one or more aromatic, unsubstituted and /or optionally substituted hydrocarbons. The optional aromatic hydrocarbons have suitably also at least 12 C atoms and a boiling point of from 150 to 350°C, preferably from 200 to 330°C, most preferred from 240 to 310°C.

Preferred aromatic hydrocarbons to be optionally added are such which are present in commercially available mixtures, which can therefore be used advantageously instead of non-aromatic hydrocarbons, provided their aromatic content is not higher than indicated above. Generally, most suitable hydrocarbon mixtures should contain < 15% CA, preferably with >60% CP and from 0 to 40% CN, as determined by DIN 51378. More preferred, however, is not to add any additional aromatic hydrocarbons but to use essentially aromatic-free hydrocarbons containing <3% CA (corresponding to about < 5% aromatic content), as determined by DIN 51378.

The aqueous medium is suitably adjusted to a pH value of > 9 by adding an adequate amount of a strong base to water. Suitable bases are for example alkali, earth alkali or ammonium hydroxides, preferably sodium hydroxide or potassium hydroxide. Instead of adjusting the pH value of the aqueous medium separately, it is also suitable to add water and the adequate amount of base separately to the conditioning vessel.

The slurry to be conditioned may additionally further comprise any suitable amount of other components known for use in phthalocyanine compositions, such as in particular resins and /or phthalocyanine derivatives. It may also comprise water- soluble grinding auxiliaries, generally in partially or fully dissolved form.

Resins are suitably added in an amount of from 0.1 to 20% by weight, preferably from 1 to 15% by weight, most preferred from 2 to 5% by weight, based on the phthalocyanine. Resins suitable for use in the process of the present invention are in particular rosin, the principal component of which is abietic acid; chemically modified rosins such as hydrogenated, dehydrogenated or disproportionated rosin; dimerised or polymerized rosin; partially esterified rosin; non-esterified rosin or partially esterified rosin; non-esterified or partially esterified maleic or phenolic modified rosin; nitrocellulose; polyamide; polystyrene or epoxy resin; thermoplastic resin and and mixtures thereof. Illustrative rosins include such commercially available materials as Staybelite™ resin (hydrogenated rosin), Recoldis™ A resin (disproportionated rosin) and Dymerex™ resin (dimerised rosin). Preferred resins for use in this invention are hydrogenated rosin and disproportionated rosin.

When it is desired to use a resin without it to be already present during dry-milling, then such resin should suitably be added before or during conditioning, latest when the-pigment has reached the desired conditioned form. Preferably, however, from Vβ to Yι of the total quantity of resin in the instant composition is used as dry-milling auxiliary and /or is present during whole conditioning.

During or after the conditioning stage is complete, a phthalocyanine derivative may be added to the pigment slurry, filtercake or dry powder. Suitable phthalocyanine derivatives used in this invention are in particular phthalocyanine derivatives having from 1 to 4 subsfrtuents comprising -N , -N- and /or -SO^- moieties in their molecule, for example dimethylaminomethyl phthalocyanine, phthalimido methyl phthalocyanine, aminomethyl phthalocyanine, sulfonated phthalocyanine, amine salts of sulfonated phthalocyanine and sulfonamides of phthalocyanine.

The phthalocyanine derivative's chromophore can optionally be further substituted by from 1 to 15 halogen atoms, especially chlorine and /or bromine, and can be either metal-free or metallized, for example with copper, nickel or zinc. Preferred are copper phthalocyanine derivatives, especially halogen-free copper phthalocyanine derivatives.

Especially preferred derivatives are dialkylaminoalkyl copper phthalocyanine, phthalimidomethyl copper phthalocyanine and salts of sulphonated copper phthalocyanine, wherein the average number of such substituents per molecule of copper phthalocyanine is from 0.5 to 2.0. Sulfonated phthalocyanines are preferably used in the form of their salts, especially their alkali or preferably ammonium salts, in particular their NH₄\ primary, secondary, tertiary or quaternary Cι-Cι₂alkyl ammonium salts.

Most preferred are mono or bis di-Cι-C4amino-Cι-C₃alkyl phthalocyanines, in particular mono- and bis-dimethylaminomethyl and mono- and bis-diethylaminomethyl copper phthalocyanine.

The phthalocyanine derivatives are suitably used in amounts of from 0.1 to 20% by weight, preferably from 0.3 to 10% by weight, most preferred from 0.5 to 3% by weight, based on the phthalocyanine, and can be added as slurry, filtercake or dry powder at any stage of the process. However, they are preferably added only after heating to the conditioning temperature, most preferably upon or after azeotropic distillation of the neutral organic conditioning liquid, particularly just before isolation of the conditioned pigment composition.

The presence of resins and /or phthalocyanine derivatives is not essential to perform the instant conditioning process. Nevertheless, it has been found that resins and /or phthalocyanine derivatives provide some additional advantages to the final products. In particular, there appears surprisingly to be a synergistic improvement of the flowability through the combined use of the instant non-aromatic hydrocarbon and phthalocyanine derivatives. Resins may be added at any stage, but adding a resin already for milling is preferable because it prevents reaggregation during milling and ensures a better homogeneity of the slurry then to be conditioned. On the other hand, though the phthalocyanine derivatives could in principle also be added already at the milling stage, it is much preferable to add them only during or after conditioning in order not to inhibit the desired particle growth.

For the instant conditioning step, the milled material is well wetted and dispersed into the solvent. The resulting slurry is then heated to the desired conditioning temperature as disclosed hereafter. The slurry is held in this temperature range for a sufficient time to allow conversion to the β crystal phase and achieve the required crystal ripening. After solvent conditioning, the neutral organic conditioning liquid is easily removed via azeotropic distillation with water. The pigmentary β phthalocyanine is then isolated, for example via filtration or centrifugation before drying the resulting filtercake, or by spray-drying.

The heating temperature is adequately from 50 to 200°C, optionally under reduced or elevated pressure of about from 5 ^• 10³ to 5 ^■ 10⁶ Pa. Preferably, the mixture is heated to a temperature from 60°C to 120°C, especially to a temperature range from 20°C below reflux temperature to reflux temperature, most preferred to reflux temperature. The temperature may be kept constant during the whole conditioning step or follow any programmed scheme, such as continuously or stepwise heating and /or cooling. The heating period depends on the desired result; from 10 minutes to 100 hours, preferably from 0.5 to 20 hours, are generally satisfactory for most purposes. The process can be operated batchwise, or wholly or partially continuously (continuous operation is especially suitable for the heat conditioning step).

Once the β crystal phase and the particle size are obtained to the desired degree, the conditioning step is suitably ended by decreasing the temperature of the mixture to 50°C or below, for example to from -20 to 40°C, preferably to from 0 to 30°C. The phthalocyanine derivative may also advantageously be added at this stage. Active cooling by a heat exchanger may prove useful. Before or while decreasing the temperature, it is preferable to separate the neutral organic conditioning liquid by azeotropic distillation with water, optionally in combination with a pression decrease. When the condensate separates into two phases, the water phase is preferably recycled in part. It is also possible to add more water, for example in the form of steam, liquid or ice, to better control the azeotropic distillation and /or cooling steps.

The pigmentary β phthalocyanine is then isolated and dried. The amount of residual neutral organic conditioning liquid in the recovered aqueous conditioning liquid (filtrate or spray-drying condensate) should in general be as low as economically achievable, depending on the capacity of the available sewage treatment plant. Part or all of the recovered neutral organic conditioning liquid may advantageously be recycled.

All above-mentioned preferences are independent from each other, though it is preferred to combine several or all of these preferences as shown by some of the following examples.

The β copper phthalocyanine product produced by the instant process has acicular or preferably rod-like crystals with an average particle length from 0.02 to 1 μm, preferably an average particle length of from 0.1 to 0.5 μm, and preferably with.an average aspect ratio of length to width of from 2 : 1 to 10 : 1 , most preferred from 3 : 1 to 7 : 1. Figure 1 is a picture taken by transmission electron microscopy (TEM), showing a product as typically obtainable be the instant process. Althought such shape is clearly not isometric and the crystals are well developed, there is amazingly an outstanding colouristic performance in oil inks, with significant and surprising improvements in millbase viscosity and low shear flow of the final ink, in particular in comparison to products obtained by the dry milling /solvent conditioning process disclosed in WO 99/54410.

The instantly obtainable compositions are new. Hence, the invention also pertains to a pigment composition comprising:

• from 74 to 99.7% by weight, preferably from 82 to 98% by weight, most preferred from 91 to 97% by weight, based on the weight of the composition, of a phthalocyanine pigment with an average particle length from 0.02 to 1 μm, preferably an average particle length of from 0.1 to 0.5 μm;

• optionally up to 30% by weight, based on the amount of non-aromatic, unsubstituted or substituted hydrocarbons, of one or more aromatic, unsubstituted and/or optionally substituted hydrocarbons having at least 12 C atoms and a boiling point of from 150 to 350°C, preferably from 200 to 330°C, most preferred from 240 to 310°C;

• from 0.1 to 20% by weight, preferably from 1 to 15% by weight, most preferred from 2 to 5% by weight, based on the phthalocyanine, of a resin; and

• from 0.1 to 20% by weight, preferably from 0.3 to 10% by weight, most preferred from 0.5 to 3% by weight, based on the phthalocyanine, of a phthalocyanine substituted by from 1 to 4 Cι-C₄aminomethyl, di-Cι-C₄amino- methyl, phthalimidomethyl, sulfonamido, Cι-C₄alkyl sulfonamido, di-Cι-C4alkyl- amino, CrC₄alkyl sulfonamido, di-Cι-C₄alkyl sulfonamido or sulfonato groups.

The ingredients of the instant composition and all preferences are the same as above. The instant composition can be used for any pigmenting purpose, preferably for coatings / paints and inks, most preferred for solvent based inks.

Printing inks comprise the pigment composition of the invention judiciously in a concentration of from 0.01 to 40% by weight, preferably from 1 to 25% by weight, with particular preference from 5 to 10% by weight, based on the overall weight of the printing ink. They may be used, for example, for gravure printing, flexographic printing, screen printing, offset printing, or continuous or dropwise inkjet printing on paper, board, metal, wood, leather, plastic or textiles, or else in special applications in accordance with formulations which are general knowledge, for example in publishing, packaging or freight, for marking purposes such as in logistics or in food, agro- chemical or pharmaceutical industry or on human or animal skin or medical equipment, in advertising, in security printing or else in the office sector for ballpoint, felt-tip or fibre-tip pens, inking pads, ink ribbons or inkjet printer cartridges.

The examples which follow illustrate the invention, without limiting it ("%" are by weight where not otherwise specified):

Example 1 : 62.9 g crude copper phtalocyanine, 10.6 g sodium chloride and 1.8 g hydrogenated resin (Staybelite™ resin) are dry-milled in a vibrating or rotating ballmill until the content of α phase reaches the range of from 45 to 65%.

0.62 g of petroleum distillate having a boiling range 280-310°C (1% aromatics, < 1% CA, 25% CN, 74% CP) and 75.3 g dry-milled copper phtalocyanine obtained as described above are added to a mixture of 18.4 g n-butanol and 208 g of water. 1.4 ml of 46% by weight caustic potash lye are further added before heating the mixture to reflux temperature (93°C) with agitation for a period of 4 hours. After conditioning is complete, 100 ml of cold water are added to the slurry, which is further cooled to about 30-35°C. 0.62 g of dimethylaminomethyl copper phthalocyanine is then added and the slurry is stirred for a short period of time, then acidified with hydrochloric acid and filtered. The presscake is washed salt and solvent free and dried at 75°C. A pigment composition having following composition is obtained: 95.8% β copper phthalocyanine, 2.7% hydrogenated resin, 1.0% dimethylaminomethyl copper phthalocyanine and 0.5% petroleum distillate. This composition leads to surprising advantages with respect to the millbase viscosity and low shear flow of inks prepared therefrom.

Example 2: It is proceeded according to example 1, with the difference that 1.24 g of the laurylamine salt of monosulphonated copper phthalocyanine are used instead of 0.62 g dimethylaminomethyl copper phthalocyanine.

Example 3: It is proceeded according to example 1 , with the difference that dimethylaminomethyl copper phthalocyanine is used in a double amount of 1.24 g.

Example 4: It is proceeded according to example 1, with the difference that 1.86 g phthalimidomethyl copper phthalocyanine are used instead of 0.62 g dimethylaminomethyl copper phthalocyanine.

Example 5: It is proceeded according to example 1, with the difference that 1.76 g copper phthalocyanine disulfonic acid and 0.72 g dimethylcocobenzyl ammonium chloride are finally added to the slurry instead of 0.62 g dimethylaminomethyl copper phthalocyanine.

Example 6: It is proceeded according to example 1 , with the difference that 1.23 g of the dimethylditallow ammonium salt of sulfonated copper phthalocyanine are used instead of 0.62 g dimethylaminomethyl copper phthalocyanine.

Example 7: It is proceeded accordihg to example 1 , with the difference that 0.62 g of dodecanol is used instead of 0.62 g of petroleum distillate.

Example 8: It is proceeded according to example 1 , with the difference that 1.8 g of fumarated resin (Pinerez™ resin) is used instead of 1.8 g of hydrogenated resin (Staybelite™ resin).

Example 9: It is proceeded according to example 1 , with the difference that 1.8 g of dimerised resin (Poly pale™ resin) is used instead of 1.8 g of hydrogenated resin (Staybelite™ resin).

Example 10: It is proceeded according to example 1, with the difference that a double amount (1.24 g) of petroleum distillate is used and 0.62 g of dodecylamine salt of monosulphonated copper phthalocyanine is used instead of 0.62 g of dimethylaminomethyl copper phthalocyanine. Example 11 : 75.3 g crude copper phthalocyanine dry-milled according to example 1 are added with agitation to a mixture of 106.7 g 81 % aqueous n-butanol (recycled upper layer of azeotrope), 110 g water and 0.62 g of petroleum distillate having a boiling range 280-310°C (1% aromatics, < 1% CA, 25% CN, 74% CP). 1.4 ml of 46% aqueous potassium hydroxide solution are added and the slurry heated to reflux temperature of 93°C for a period of 4 hours. After conditioning is complete, 100 ml of cold water are added to the slurry, which is further cooled to about 30-35°C. 0.62 g of dodecylamine salt of monosulphonated copper phthalocyanine is then added and the slurry is stirred for a short period of time, then acidified with hydrochloric acid, filtered, washed salt and solvent free, and dried at 75°C.

Example 12: It is proceeded according to example 1 , with the difference that the 0.62 g of dimethylaminomethyl copper phthalocyanine is added after 2 hours at reflux. After a further 2 hours conditioning is complete, 100 ml of cold water are added to the slurry, which is further cooled to about 30-35°C. The slurry is then acidified with hydrochloric acid, filtered, washed salt and solvent free, and dried at 75°C.

Examples 13-16: It is proceeded according to example 1 , with the difference that 0.62 g of dodecylamine salt of monosulphonated copper phthalocyanine is used instead of 0.62 g of dimethylaminomethyl copper phthalocyanine, and the following amounts of solvents are used:

In examples 13-15 the neutral organic conditioning liquid is distilled azeotropically before cooling down. In example 16, the neutral organic conditioning liquid is diluted before cooling down. 0.62 g of dodecylamine salt of monosulphonated copper phthalocyanine is then added and the slurry is stirred for a short period of time, then acidified with hydrochloric acid, filtered, washed salt and solvent free, and dried at 75°C.

Example 17: It is proceeded according to example 1 , with the difference that 0.62 g of petroleum distillate having a boiling range 240-270°C (20% aromatics, 12% CA, 22% CN, 66% CP) is used instead of 0.62 g of aromatic free petroleum distillate.

Example 18 (comparative): 75.3 g crude copper phthalocyanine dry-milled according to example 1 are added with agitation to a mixture of 18.4 g n-butanol and 208 g water. 1.4 ml of 46% potassium hydroxide solution are added and the slurry heated to reflux temperature of 93°C for a period of 4 hours. 100 ml cold water are added in order to cool the slurry, which is then acidified using hydrochloric acid, filtered, washed salt and solvent free, and dried at 75°C.

Example 19 (comparative): It is proceeded according to exampje 5, with the difference that no petroleum distillate is used.

Example 20: (evaluation in a typical oil ink application) 20 g of pigment composition obtained according to examples 1-19 are each premixed with 80 g of a heatset oil ink varnish containing a blend of modified phenolic resin, alkyd resin, petroleum distillate and from 0-5% of auxiliaries. 100 g of the premix are dispersed on a Bϋhler SDY- 200™ three roll mill at 23°C for 5 minutes. The ink base is then given two dispersion passes on the mill at 10⁶ Pa (10 bar). The ink properties are assessed by reducing the 2^nd pass from 20% to 14% pigmentation with the above varnish. The final ink is then printed using a Prufbau printing machine to give prints of differing film weights. The print density for each print is measured using a densitometer (Gretag D19C). The gloss is measured at equal film weight using an Erichsen mini glossmaster at 60°. The millbase viscosity is measured on the millbase ink using a Laray falling bar viscosi- meter. The low shear flow is measured on the final ink and defined as the distance travelled by the ink down an inclined plate at 60°. The results are as follows (standard 100% set for comparative example 18):

The pigment compositions of examples 1 to 17 all have a much better millbase viscosity, as compared with the pigment compositions of comparative examples 18 and 19. The pigment compositions of examples 1 to 17 also have a much better low shear flow, as compared with the pigment compositions of comparative example 18. The pigment compositions of examples 1 to 4 and 6 to 17 also have a better gloss than both pigment compositions of comparative examples 18 and 19. The pigment composition of example 5 has a better gloss than the pigment composition of comparative example 19.

Examples 21 -38: It is proceeded according to examples 1 - 17, with the difference that only 0.15 g of petroleum distillate are each time used.

Examples 39-56: It is proceeded according to examples 1 - 17, with the difference that petroleum distillate is each time used in an increased amount of 2.0 g.

Examples 57-109: It is proceeded according to examples 1 - 17 and 21 -56, with the difference that the petroleum distillate is mixed with the alcohol before adding the dry-milled crude and water.

Examples 110- 136: It is proceeded according to examples 1 - 17, with the difference that the phthalocyanine derivatives are added after 2% hours at reflux.

Examples 137- 153: It is proceeded according to examples 1 - 17, with the difference that the resin is only added after 214 hours at reflux.

Examples 154-303: It is proceeded according to examples 1 - 17 and 21 - 153, with the difference that no resin is used.

Examples 304 -453: It is proceeded according to examples 1 - 17 and 21 - 153, with the difference that crude copper phthalocyanine is wet-milled in a pearl-mill with the resin and water, filtered then used as a wet presscake for the instant conditioning step. Examples 454 - 1011: It is proceeded according to examples 1 - 17 and 21 -453, with the difference that the following amounts of following solvents are used:

Examples 3154-5303: It is proceeded according to examples 1 - 17, 21 -903 and 1804-3153, with the difference that the conditioning temperature is set to 80°C for a period of 10 hours and the neutral organic conditioning liquid is distilled azeotropically by reducing the pressure adequately.

Examples 5304-6203: It is proceeded according to examples 904- 1803, with the difference that the conditioning temperature is set to 100°C for a period of 1 hour under 4 ^• 10⁵ Pa nitrogen pressure, and the neutral organic conditioning liquid is distilled azeotropically after cooling down to about the boiling point of the azeotrope and then releasing the pressure.

Examples 6204- 12403: It is proceeded according to examples 1 - 17 and 21 -6203, with the difference that a mixture of Ci2-Cι₆alcohols is used instead of the petroleum distillate or pure dodecanol.

Examples 12404-24603: It is proceeded according to examples 1 - 17 and 21 - 12203, with the difference that 5.0 g of sodium formate are used as a grinding auxiliary instead of 10.6 g of sodium chloride.

Examples 24604-85603: It is proceeded according to examples 12204-24403, with the differences that crude copper phthalocyanine is replaced by crude Colour Index Pigment Blue 15:1, Pigment Blue 16, Pigment Green 7, Pigment Green 36 or zinc phthalocyanine, respectively, which instead of dry-milling are each wet-milled in a pearl mill with an aqueous medium and zirconium oxide balls of 0.3-0.4 mm diameter but without other grinding auxiliary and are used as wet filtercake, the quantity of added water ist adjusted according to the moisture in the filtercake, and the corresponding amount of finely divided resin is added at about 20-40°C just before starting to heat for conditioning.

The skilled artisan will routinely envisage many other easy embodiments of the inventive process, according to the characteristics of the equipment at his disposal and the product specifications to be met.

Claims

Claims:

1. A process for preparing a phthalocyanine pigment, comprising heating to a temperature of from 50 to 200°C a slurry comprising:

• from 1 to 50 parts by weight, per part by weight of neutral organic conditioning liquid, of a basic aqueous solution having a pH value of >9, preferably having a pH value of from 10 to 13.

2. A process according to claim 1 , wherein the phthalocyanine pigment is obtained essentially in the β crystal phase.

3. A process according to claim 1 or 2, wherein the phthalocyanine consisting of primary particles having an average particle size of maximally 0.5 μm is unsubstituted copper phthalocyanine.

4. A process according to claim 1 , 2 or 3, wherein the phthalocyanine consisting of primary particles having an average particle size of maximally 0.5 μm is a mixture of α and β crystal phases obtained by dry-milling, preferably dry-milling with at least one kind of milling auxiliary.

5. A process according to claim 1 , 2, 3 or 4, wherein the neutral organic conditioning liquid is selected from the group consisting of saturated and mono-unsaturated alcohols, ketones and esters having up to 8 C atoms, preferably from 2 to 6 C atoms, most preferred 3, 4, 5 or 6 C atoms.

6. A process according to claim 1, 2, 3, 4 or 5, wherein the non -aromatic hydrocarbons is selected from the group consisting of petroleum distillates and aliphatic alcohols having at least 12 C atoms.

7. A process according to claim 1, 2, 3, 4, 5 or 6, wherein there is additionally from 0.1 to 20% by weight, preferably from 1 to 15% by weight, most preferred from 2 to 5% by weight, based on the phthalocyanine, of a resin, and /or from 0.1 to 20% by weight, preferably from 0.3 to 10% by weight, most preferred from 0.5 to 3% by weight, based on the phthalocyanine, of a phthalocyanine derivative.

8. A process according to claim 7, wherein the phthalocyanine derivative is a phthalocyanine having from 1 to 4 substituents comprising -N , -N- and /or -SO^- moieties in its molecule.

9. A pigment composition comprising:

• from 74 to 99.7% by weight, preferably from 82 to 98% by weight, most preferred from 91 to 97% by weight, based on the weight of the composition, of a phthalocyanine pigment with an average particle length from 0.02 to 1 μm, preferably an average particle length of from 0.1 to 0.5 μm; • from 0.1 to 5% by weight, based on the weight of the phthalocyanine, of one or more compounds selected from the group consisting of non-aromatic hydrocarbons either unsubstituted or substituted by 1 or 2 hydroxy and /or ether groups, which compounds have at least 12 C atoms and a boiling point of from 150 to 350°C, preferably from 200 to 330°C, most preferred from 240 to 310"C;

• from 0.1 to 20% by weight, preferably from 0.3 to 10% by weight, most preferred from 0.5 to 3% by weight, based on the phthalocyanine, of a phthalocyanine substituted by from 1 to 4 Cι-C aminomethyl, di-Cι-C amino- methyl, phthalimidomethyl, sulfonamido, Cι-C alkyl sulfonamido, di-Cι-C₄alkyl- amino, Cι-C₄alkyl sulfonamido, di-Cι-C alkyl sulfonamido or sulfonato groups.

10. The use of a pigment composition according to claim 9 for the preparation of a coating or ink.