WO2012084824A1

WO2012084824A1 - PROCESS OF PREPARING PRODUCT BASED ON COPPER PHTHALOCYANINE (CuPc) PARTICLES

Info

Publication number: WO2012084824A1
Application number: PCT/EP2011/073238
Authority: WO
Inventors: Jai Won Park; Hyunsu Lee; Kisuck Jung; Eunha Jeong; Sangmin Han
Original assignee: Solvay Sa
Priority date: 2010-12-22
Filing date: 2011-12-19
Publication date: 2012-06-28
Also published as: CN103403101A; KR101343758B1; TW201241103A; KR20120130322A; JP2014503647A; KR20130086216A

Abstract

A process for preparing a product based on copper phthalocyanine (CuPc) particles, said process comprising adding, to the CuPc particles, during or after their preparation, at least one non-polar solvent in an amount of less than 10 % by weight of the CuPc particles.

Description

Process of Preparing Product Based on Copper Phthalocyanine (CuPc)

Particles

This application claims priority to European patent application

No. EP 10196463.3 filed on 22 Dec 2010, the whole content of this application being incorporated herein by reference for all purposes.

Technical Field

The present invention generally relates to copper phthalocyanine (CuPc) and processes of preparing the same. More particularly, the present invention relates to a new efficient and economical process for preparing CuPc pigments with better dispersibility, said CuPc pigments being especially suitable for the preparation of color filters used for displaying colour images, to the CuPc pigments prepared thereby, as well as to liquid crystal display devices in which the foregoing pigments are incorporated.

Background Art

Copper phthalocyanine blue (C.I. Pigment Blue 15) is without exception the most significant of any synthetic organic pigment produced today due to its excellent color strength and durability. It has a high molar absorption

coefficient (ca. 105), and its light fastness and weather fastness are superior to all other organic pigments. Additionally, its synthesis is readily performed from lower cost materials (phthalic anhydride, urea and copper salts), thereby making production of this complex molecule both facile and economic. Thus, it is typically employed as a blue colorant for paints or plastics. Among pigments, copper phthalocyanine is very stable and more desirable since it possesses a variety of fastness.

Copper phthalocyanine has many crystal forms. Among such crystal forms, those known to have actual applications include alpha, beta and epsilon crystal forms of copper phthalocyanine. It is a common practice to use the beta crystal form to impart a greenish blue colour, while using the alpha crystal form to impart a reddish blue colour. Further, the epsilon crystal form is employed when a blue colour, which is more reddish than that produced using the alpha crystal form, is required.

Copper phthalocyanine is commercially available in three crystal forms, namely, alpha, beta and epsilon. The alpha crystal, which uses the Colour Index nomenclature, is described as Pigment Blue 15, 15: 1 and 15:2, and is a clean, bright red shade blue. The beta crystal, which is described as Pigment Blue 15:3 and 15:4, is a clean green shade blue, and the important epsilon form is the most reddish shade of blue. Its halogenated derivatives are also used as important green pigments.

Typically, the commercially available "crude" copper phthalocyanine particles include various crystal forms, most of which exhibit beta- crystallographic form. There are many techniques available for the conversion of crude copper phthalocyanine into pigmentary form, e.g., by acid pasting to give 100 % alpha form, or salt-milling involving progressive conversion to the alpha form. It is preferred that they are prepared from copper phthalocyanine particles exhibiting a β crystallographic form by using an acid paste method. The beta crystal form copper phthalocyanine is commercially available from various companies such as Toyo Ink (Japan), Dainippon Ink & Chemicals Co. (Japan), etc. The beta crystal form copper phthalocyanine is subjected to crystal phase conversion into alpha crystal form by acid pasting, which is described, for instance, in Ullmann's Encyclopedia of Industrial Chemistry, Fifth Completely Revised Edition, 1992, Volume A20, pp. 225-226, incorporated herein by reference.

Copper phthalocyanine (CuPc) particles exhibiting an ε crystallographic form are typically prepared from CuPc particles with at least 50 wt % of the particles exhibiting an a crystallographic form as a starting material.

Various methods have been proposed for producing a phthalocyanine pigment with each crystal form. A typical process of producing epsilon crystal form copper phthalocyanine is the solvent salt milling process, wherein copper phthalocyanine particles exhibiting alpha crystal form and copper

phthalocyanine particles exhibiting epsilon crystal form are milled in an organic solvent.

For example, WO 2009/037233 discloses a process wherein CuPc particles exhibiting alpha-crystallographic form are subjected to heating in a solvent, optionally with milling beads, for crystallographic conversion to epsilon type. The heating is then followed by a kneading process for micronizing the epsilon type CuPc particles. In WO 2009/062995, after obtaining alpha-type CuPc particles from the acid-pasting step, the alpha-type CuPc particles are kneaded under different temperature conditions. During the kneading step, two CuPc derivatives are sequentially added. As to a process of preparing alpha form copper phthalocyanine from the beta form, pigmentation processes using sulfuric acid, which is one of the mineral acids, have been known in the art. That is, an acid pasting process (treating crude copper phthalocyanine when dissolved in a large amount of concentrated sulfuric acid) and an acid slurry process (treating crude copper phthalocyanine with a large amount of sulfuric acid having a concentration insufficient for dissolving the pigment to form a sulfate) are used.

However, the products obtained by the above processes are produced in the form of agglomerates, which do not display the desired performance properties.

In order to subsequently achieve optimum application properties, the so-called finish is carried out in, for example, solvents while adding surface- active agents as disclosed in GB 1096192A and GB2039290. EP1580239A1 also discloses a process for the production of an epsilon-crystal form copper phthalocyanine comprising heating a copper phthalocyanine in an organic solvent, such as t-amylbenzene, sulfolane, etc., in the presence of a Lewis acid.

WO 08/083799A discloses a pigment composition of copper

phthalocyanine exhibiting epsilon crystallographic form, which is produced with application of a wet grinding process, more particularly a salt kneading operation.

US 4239685A discloses a process for preparation of phthalocyanine pigments from a phthalocyanine press paste obtained by hydrolysis of a sulphuric solution of phthalocyanine, in which a small quantity of a water- insoluble crystallizing solvent, in the presence or absence of a non-crystallizing solvent, is incorporated with stirring in said press paste, and then the solvent or solvents is or are eliminated and the paste is dried, and the pigments thus obtained are collected.

US 3801591 A discloses a production of metal phthalocyanine pigment composed almost exclusively of the α I polymorph in which crude metal phthalocyanine is subjected to controlled precipitation in two sages followed by conditioning of the resultant slurry under intense agitation to generate an air/liquid interface and thereby facilitate flocculation, hence filtration.

GB 1411880A discloses a process for the production of copper

phthalocyanine in the form of the pure or practically pure ε-modification copper phthalocyanine which process comprises converting a-modification,

γ-modification and/or δ-modification copper phthalocyanine to an a-/ ε-modification mixture by grinding in a ball mill, treating the mixture with a liquid at a temperature at which no or substantially no conversion into the β-modification takes place (liquid-specific limiting temperature) to effect conversion of a-modification to ε-modification and to form a mixture of the liquid with pure or substantially pure ε-modification and optionally isolating the pure or substantially pure ε-modification of copper phthalocyanine.

However, the above-described methods of preparing copper

phthalocyanine particles have problems in that the resulting CuPc particles still lack dispersibility, which results in still to improve color filter pigments, for instance regarding the contrast ratio of the color filters prepared from the copper phthalocyanine particles. Thus, there has been a strong desire in the art to develop a method of effectively improving dispersibility of the resultant copper phthalocyanine particles to increase the performance of a final pigment for color filter, without the above-described drawbacks.

Disclosure of Invention

The purpose of the present invention is to resolve the problems of the conventional preparation process, e.g. relatively low dispersibility resulting in poor contrast ratios from the resultant color filter pigment.

The present invention therefore relates to a process for preparing a product based on copper phthalocyanine (CuPc) particles, said process comprising adding, to the CuPc particles, during or after their preparation, at least one non- polar solvent in an amount of less than 10 % by weight of the CuPc particles.

The inventors of the present invention have indeed discovered that the performance of the final color filter pigment for producing blue pigments may be improved when some non-polar solvents were added in an amount of less than 10 % by weight of the copper phthalocyanine particles during or after the preparation of copper phthalocyanine particles exhibiting epsilon form.

Hereinafter, the present invention is described in detail.

The present invention is directed to developing a new and more efficient process of preparing copper phthalocyanine-based products, which satisfies the above-mentioned features.

Copper phthalocyanine (CuPc) is typically developed for effective use as a blue pigment of color filters for LCDs. Such color filters must be highly transparent, homogeneous and be prepared in a layer with uniform thickness. These features are decided by several factors including chemical purity, crystallographic purity, primary particle size and particle size distribution of copper phthalocyanine particles. In this regard, the disclosure teaches a new and more efficient process of preparing copper phthalocyanine.

Even though any type of non-polar solvent known in the art may be used in the process of the present invention, it is preferable to use at least one non-polar solvent selected from alicyclic and aromatic compounds. Suitable examples of non-polar solvents are those selected from the group consisting of n-hexane, pentane, cyclopentane, petroleum ether, cyclohexane, benzene, naphthalene, toluene, or cumene, preferably cyclohexane, benzene or naphthalene.

The amount of the non-polar solvent is not limited but the non-polar solvent is generally added in an amount of at least 0.1 % by weight of the CuPc particles, particularly at least 0.5 % by weight, more particularly at least 1 % by weight. The non-polar solvent is commonly added in an amount of less than 10 % by weight of the CuPc particles, particularly at most 5 % by weight, more particularly at most 3 % by weight. The amount of non-polar solvent may typically be from 0.1 to less than 10 % by weight of the CuPc particles, preferably from 0.5 to 5 %, more preferably from 1 to 3 % by weight.

In a specific embodiment of the invention, the at least one non polar solvent may be combined with at least one polar solvent. The at least one polar solvent may be present preferably in an amount of from 3.3 to 20 % by weight of the CuPc particles, more preferably from 5 to 10 % by weight, in particular from 5 to less than 10 % by weight.

In another embodiment of the present invention, a surfactant acting as a dispersant may be added in the process of the invention, especially in the same process step as the non-polar solvent. Suitable surfactants include organic carboxylic or sulfonic acids, amines or ammonium compounds, or rosin and its derivatives, for instance lauric acid, capric acid, citric acid, oleic acid, stearic acid, dodecylbenzene sulfonic acid (DBSA), p-toluenesulfonic acid (pTSA), lauryl amine, benzylamine, hexadecylamine, dodecylamine, aniline,

6-aminohexanoic acid, 4-(aminomethyl)benzoic acid, cetyltrimethyl ammonium chloride, and combinations thereof, preferably cetyltrimethyl ammonium chloride, rosin and its derivatives, and combinations thereof.

Such surfactants are believed to form an electrical double layer through interaction with the surface of CuPc particles, which leads to better dispersion stability of the resultant dispersions by prevention of particle agglomeration. The interaction may be ionic or pi-pi-type interaction between the surfactant molecule and the surface of copper phthalocyanine particles. The term "rosin" is defined herein as a solid form of resin obtained from pines and some other plants, mostly conifers, which chiefly consists of different resin acids, especially abietic acid. Mixtures of this kind that are readily available and occur in nature include, but are not limited to, tall oil rosin, gum rosin or wood rosin. These natural mixtures may comprise rosin acids of the abietic type and/or the pimaric type such as abietic acid, palustric acid, neoabietic acid, levopimaric acid, pimaric acid, isopimaric acid or dehydroabietic acid, among others, in varying amounts. In addition to rosin acids with one carboxylic acid functionality, rosin acids with two or more carboxylic acid functionalities are also considered as rosin acids in the meaning of the present invention. The expression "rosin derivatives" is defined as any derivative of the rosin, for example, hydrogenated rosin, dimerized rosin, poly-pale rosin, rosin substituted by ester groups, etc.

When a surfactant is added, its amount is not limited but is in general from 0.1 to 25 % by weight of the CuPc particles, preferably from 0.5 to 20 % by weight, more preferably from 1 to 15 % by weight.

In a further embodiment, at least one of an akaline or alkaline earth metallic salt may be added during and/or after the kneading step. The alkaline metal of the alkaline metallic salt is typically selected from sodium, potassium and lithium, in particular sodium. The alkaline earth metal of the alkaline earth metallic salt is often selected from calcium and magnesium, most often calcium. The metallic salt is advantageously an alkaline earth metallic salt. Suitable examples of alkaline and alkaline earth metallic salts are alkaline and alkaline earth metal chlorides such as NaCl, KC1, LiCl, CaCl₂, MgCl₂ ; carboxylic acid salts such as CH₃COONa, (CH₃COO)₂Ca ; acidic or basic salts such as NaHC0₃, NaHS0₄, Na₂HP0₄, Ca(OH)Cl, Ba(OH)Cl, etc. ; especially CaCl₂ and MgCl₂.

When an alkaline or alkaline earth metallic salt is added, its amount is not limited, but it is generally added in an amount from 0.1 to 25 % by weight of the CuPc particles, preferably from 0.5 to 20 % by weight, more preferably from 1 to 15 % by weight.

In the present invention, it has surprisingly been found that by adding non- polar solvent in an amount of less than 10 % by weight, a better dispersibility of the pigment particles can be obtained. It has also been found that the resulting particles exhibit a rounder particle shape. This leads to an improved contrast ratio of the resultant color filter prepared from the pigment particles, as well as to an improved brightness of said color filters. The present invention therefore also relates to copper phthalocyanine (CuPc) particles having a round shape, in particularly to CuPc particles showing an average aspect ratio from 1 : 1 to 2: 1, preferably 1 : 1 to 1.5: 1, more preferably 1.1 to 1.3 : 1 , most preferably around 1 : 1. The aspect ratio is defined herein as the length of a pigment particle with respect to the width thereof. The aspect ratio is usually determined by an image analysis of pictures taken by transmission electron microscopy (TEM) or scanning electron microscopy (SEM). The mean length (L) can be determined by several methods including measurement of the maximal Feret diameter, the length of the rectangle in which the particle can be inserted or the length L. Likewise, the mean width of the particles can be determined according to the diameter of a circle of equivalent projection area, the minimal Feret diameter, the width of the rectangle in which the particle can be inserted or the width 1. Thus, the aspect ratio (L/l) corresponds to the ratio between a length (L) and the related width (1), especially the maximal Feret diameter on the minimal Feret diameter, the maximal Feret diameter on the diameter of a circle of equivalent projection area, the length of the rectangle in which the particle can be inserted on the width of the rectangle in which the particle can be inserted or the length measured directly on the width measured directly. The aspect ratio of a population of particles is defined as the mean of the aspect ratio of each particle. In a preferred embodiment, the aspect ratio is the averaged ratio of the length of particles measured directly on the width of particles measured directly, said lengths and widths being measured on images obtained by TEM.

The process of the present invention is especially suitable for preparing CuPc particles exhibiting an ε crystallographic form.

In one aspect of the present invention, the product (CuPc) particles exhibit an ε crystallographic form and the CuPc particles to which the at least one non- polar solvent is added comprise CuPc particles exhibiting an a crystallographic form. Preferably, the CuPc particles to which the at least one non-polar solvent is added comprise CuPc particles with at least 50 wt % of the particles exhibiting an a crystallographic form.

In a particular embodiment of this aspect, copper phthalocyanine particles exhibiting an ε crystallographic form are added, as seed particles, to the CuPc particles to which the at least one non-polar solvent is added, in an amount of from 10 wt % to 90 wt %, preferably 15 wt % to 50 wt % relative to the total amount of CuPc particles. In a first specific embodiment, copper phthalocyanine particles exhibiting an ε crystallographic form may be prepared by heating a starting material comprising at least 50 wt % of CuPc particles exhibiting an a crystallographic form at a temperature higher than or equal to 50°C in the presence of at least one organic liquid and optional milling in the presence of beads. The organic liquid may for instance be selected from the group consisting of N-methyl-2- pyrrolidone, sulfolane, Ν,Ν-dimethylformamide, glycols such as propylene glycol monomethyl ether acetate, diethylene glycol, alcohols such as diacetone alcohol, acetonitrile, monochlorobenzene, ethylene glycol butyl ether, ketones and quinolines. Milling, as defined herein, means a process by which the solids are subjected to attrition, grinding, etc. to achieve particle size reduction.

In a second specific embodiment, ε CuPc particles may be prepared by kneading a starting material comprising at least 50 wt % of CuPc particles exhibiting an a crystallographic form in the presence of at least one liquid and of at least one inorganic salt. The liquid is generally selected from the group consisting of N-methyl-2-pyrrolidone, sulfolane, N,N-dimethylformamide, diethylene glycol, diacetone alcohol, glycerin, ethylene glycol, propylene glycol, polypropylene glycol, 2-butoxy ethanol, methylene glycol, diethylene glycol monomethyl ether, triethylene glycol monomethyl ether, dipropylene glycol monomethyl ether, l-methoxy-2-propanol, l-ethoxy-2-propanol, ketones and quinolines. Preferably, kneading is conducted under temperature conditions such that the temperature profile as a function of time exhibits at least two derivatives of temperature with respect to time (dT/dt) being equal to 0. The two temperatures are associated with the derivatives equal to 0 differing by at least 10°C. In another embodiment, kneading is conducted under a constantly or stepwise changing temperature profile. Preferably, kneading is conducted at the first temperature and then at the second temperature, wherein the first temperature is 80-150°C (preferably 100-120°C) and the second temperature is 30-70°C (preferably 50-60°C). This embodiment provides modification of the temperature during the kneading step by which CuPc particles exhibiting a- crystallographic form is converted to ε crystallographic form and their particle size is significantly reduced.

The specific conditions of the kneading or heating step (e.g., duration, beads, inorganic salts, etc.) are described in International Patent Applications WO 2009/037233 and WO 2009/062995, all of which are incorporated herein by reference in their entirety. After preparation of copper phthalocyanine according to those methods, to remove byproducts and additives added in the previous step(s), the resultant mixture may be stirred for a period of time, and filtered. The filter cake may be washed by reslurrying several times in distilled water, optionally in the presence of an organic solvent.

The process of the present invention is also especially suitable for preparing CuPc pigment compositions comprising CuPc particles exhibiting an ε crystallographic form.

In another specific embodiment of the invention, the non-polar solvent may be added during preparation of a CuPc pigment composition comprising

CuPc particles exhibiting an ε crystallographic form. Specifically, the non-polar solvent may be added in a kneading step, or in a re-slurry step where the filter cake obtained after the kneading step is reslurried in a solvent such as water, a water-miscible solvent or a mixture thereof. In this embodiment, by adding the at least one non-polar solvent to CuPc particles exhibiting an ε crystallographic form, preferably during a re-slurry or kneading step (size reduction), a rounder shape of the CuPc particles can be obtained. In some further specific embodiments, a non-polar solvent may be added during the kneading step, and subsequently another non-polar solvent may be added during the re-slurry step. The present invention thus also relates to copper phthalocyanine (CuPc) pigment compositions comprising CuPc particles exhibiting an ε crystallographic form obtainable according to the process of the invention. Also, it is related to a color filter comprising copper phthalocyanine particles exhibiting the epsilon crystallographic form obtainable by the process of the present invention.

The present invention also relates to copper phthalocyanine (CuPc) particles exhibiting an ε crystallographic form, obtainable by the process of the invention.

In view of the above, another aspect of the present invention is related to the use, in preparing a product based on CuPc particles, of at least one non-polar solvent in an amount of less than 10 % by weight of the copper

phthalocyanine (CuPc) particles.

The present invention is further illustrated below without limiting the scope thereto.

Should the disclosure of any patents, patent applications, and publications which are incorporated herein by reference conflict with the description of the present application to the extent that it might render a term unclear, the present description shall take precedence.

Examples

Example 1 (Conversion of beta-CuPc to alpha-CuPc)

50 g of crude copper phthalocyanine were added to 500 g of 95 wt % sulfuric acid in a 2L glass beaker. Further, the resultant mixture was stirred by a stirring impeller (Teflon centrifugator, rotation speed of 300 rpm) at 30°C for 2 hours to prepare a suspension or solution of sulfate in the sulfuric acid. The suspension or the solution was poured twice into 5L of water to obtain an alpha crystal form copper phthalocyanine, which was then dried under hot air. After pulverizing the resulting solid, the alpha crystal form copper phthalocyanine was obtained almost quantitatively in terms of crystallographic yield, which was confirmed by a XRD study.

Example 2 (Conversion of alpha-CuPc to epsilon-CuPc in the presence of cyclohexane)

To a lab-scale kneader, 50 g of the copper phthalocyanine particles exhibiting an alpha crystallographic form, which were obtained in Example 1 and 12 g of epsilon-type copper phthalocyanine were added with 3.0 g of cyclohexane, 80 g of diethylene glycol and 400 g of sodium chloride. The mixture was kneaded for 6 hours at 130°C with a rotation speed of 50 rpm (1^st stage), and then for 8 hours at 80°C with an identical rotation speed

(2^nd stage). After kneading, the resultant particles were filtered and washed several times with distilled water.

The wet cake was reslurried in deionized water and then lOg of rosin were added while maintaining stirring, and a copper phthalocyanine composition was obtained. After the re-slurry step was completed, the slurry was purified by filtration, and dried at a temperature of 80°C and pressure of 104 Pa. The dried product was then pulverized and analyzed by a Transmission electron microscope (TEM). Fig. 1 illustrates a TEM image for the copper

phthalocyanine particles.

Example 3 (Conversion of alpha-CuPc to epsilon-CuPc in the presence of benzene)

Copper phthalocyanine particles exhibiting epsilon crystallographic form were obtained in an identical manner to that of Example 2, except that 3.0 g of benzene were added during the kneading step. Example 4 (Comparative - no addition of non-polar solvent and surfactant)

Copper phthalocyanine particles exhibiting epsilon crystallographic form were obtained in an identical manner to that of Examples 1 and 2, except that no non-polar solvent, no surfactant and no metallic salts were added. Upon analyzing some dried samples of the resultant copper phthalocyanine particles exhibiting epsilon crystallographic form with the transmission electron microscope (TEM), they were shown to exhibit more agglomeration in the image (Figure 2).

As shown in the TEM images of Figures 1 and 2, the epsilon-CuPc particles obtained according to the process of the present invention, in the presence of a non-polar solvent (Example 2), exhibit a higher dispersion level compared to the epsilon-CuPc particles produced according to Example 4, without addition of a non polar solvent. Further, the CuPc particles of the invention have an aspect ratio close to 1 : 1, which is advantageous for higher contrast ratio.

Examples 5 to 7 (Comparative - no addition of a non polar solvent)

Copper phthalocyanine particles exhibiting epsilon crystallographic form were obtained in an identical manner to that of Example 2, except that 0.5 g of rosin and 0.5 g of calcium chloride, or 1.5 g of rosin and 1.5 g of calcium chloride, or 10.0 g of rosin were respectively added during the re-slurry step. Example 8 (Conversion of alpha-CuPc to epsilon-CuPc in the presence of cyclohexane and no addition of surfactant)

Copper phthalocyanine particles exhibiting epsilon crystallographic form were obtained in an identical manner to that of Examples 1 and 2, except that no surfactant and no metallic salts were added. The dried product was then pulverized and the particle shape was better, compared to those of Example 4. Test of the particles in color filters

Color filters fabricated using the pigment from the ε form copper phthalocyanine pigment particles prepared according to Examples 2 and 3 yielded improvements in contrast ratio by approximately 8 % and 10 %, respectively, compared to those of Example 4, as shown in Table 1.

In Table 1, the CuPc pigment in which the non-polar solvent and optionally surfactant were added exhibited improved contrast ratio of the color filter pigment millbase. Such improvement would be derived from better dispersibility and optimized shape of the resultant CuPc particles. Thus, such increased dispersibility and good particle shape has led to the improved contrast ratio of the downstream color filter.

Table 1

Brief Description of Figures in the Drawings

Fig. 1 is an image from a Transmission Electron Microscope (TEM) for the copper phthalocyanine particles exhibiting epsilon crystallographic phase prepared by the method according to Example 2.

Fig. 2 is an image from a TEM for the copper phthalocyanine particles exhibiting epsilon crystallographic phase prepared by the method according to Example 4.

Should the disclosure of any patents, patent applications, and publications which are incorporated herein by reference conflict with the description of the present application to the extent that it may render a term unclear, the present description shall take precedence.

Industrial Application

It will be apparent to those skilled in the art that various modifications and variations can be made to the present invention without departing from the spirit and scope of the invention. Thus, it is intended that the present invention covers the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.

Claims

C L A I M S

1. A process for preparing a product based on copper

phthalocyanine (CuPc) particles, said process comprising adding, to the CuPc particles, during or after their preparation, at least one non-polar solvent in an amount of less than 10 % by weight of the CuPc particles.

2. The process according to Claim 1, wherein the at least one non-polar solvent is added in an amount from 0.1 to less than 10 % by weight of the CuPc particles, preferably from 0.5 to 5 %, more preferably from 1 to 3 %.

3. The process according to Claim 1 or 2, wherein the product (CuPc) particles exhibit an ε crystallographic form and the CuPc particles to which the at least one non-polar solvent is added comprise CuPc particles exhibiting an a crystallographic form.

4. The process according to any one of Claims 1 to 3 which further comprises adding to the CuPc particles to which the at least one non-polar solvent is added, CuPc particles exhibiting an ε crystallographic form, in an amount of from 10 wt % to 90 wt %, preferably 15 wt % to 50 wt % relative to the total amount of CuPc particles.

5. The process according to Claim 3 or 4, wherein the at least one non- polar solvent is selected from a group consisting of n-hexane, pentane, cyclopentane, petroleum ether, cyclohexane, benzene, naphthalene, toluene, cumene and mixtures thereof, preferably cyclohexane, benzene, naphthalene and mixtures thereof.

6. The process according to any one of Claims 1 to 5, wherein the at least one non polar solvent is combined with at least one polar solvent, said at least one polar solvent being present in an amount of from 3.3 to 20 % by weight of the CuPc particles, preferably from 5 to 10 % by weight, more preferably from 5 to less than 10 % by weight.

7. The process according to any one of Claims 1 to 6, wherein at least one surfactant is further added.

8. The process according to Claim 7, wherein the surfactant is at least one selected from the group consisting of rosin and its derivatives, lauric acid, capric acid, citric acid, lauryl amine, benzylamine, hexadecylamine,

dodecylamine, aniline, 6-aminohexanoic acid, 4-(aminomethyl)benzoic acid, cetyltrimethyl ammonium chloride, and combinations thereof, preferably from rosin and its derivatives, cetyltrimethyl ammonium chloride, and combinations thereof.

9. The process according to any one of Claims 1 to 8, wherein at least one of an alkaline or alkaline earth metallic salt is added.

10. The process according to any one of Claims 1 to 9, further comprising adding at least one organic liquid selected from the group consisting of

N-methyl-2-pyrrolidone, sulfolane, Ν,Ν-dimethylformamide, glycols such as propylene glycol monomethyl ether acetate, diethylene glycol, alcohols such as diacetone alcohol, acetonitrile, monochlorobenzene, ethylene glycol butyl ether, ketones and quinolines, or at least one liquid selected from the group consisting of N-methyl-2-pyrrolidone, sulfolane, Ν,Ν-dimethylformamide, diethylene glycol, diacetone alcohol, glycerin, ethylene glycol, propylene glycol, polypropylene glycol, 2-butoxy ethanol, methylene glycol, diethylene glycol monomethyl ether, triethylene glycol monomethyl ether, dipropylene glycol monomethyl ether, l-methoxy-2-propanol, l-ethoxy-2-propanol, ketones and quinolines, to the starting material.

11. The process according to any one of Claims 1 to 10 for preparing CuPc particles exhibiting an ε crystallographic form, said process comprising kneading CuPc particles containing at least 50 wt % of particles exhibiting an a crystallographic form as a starting material in the presence of the at least one non-polar solvent.

12. The process according to any one of Claims 1 to 10 for preparing a CuPc pigment composition comprising CuPc particles exhibiting an ε crystallographic form, wherein the at least one non-polar solvent is added to CuPc particles exhibiting an ε crystallographic form, preferably during a re-slurry or kneading step.

13. Copper phthalocyanine (CuPc) pigment composition comprising CuPc particles exhibiting an ε crystallographic form, said CuPc particles being prepared according to the process of Claim 11, or said composition being prepared according to the process of Claim 12.

14. Copper phthalocyanine (CuPc) particles exhibiting an

ε crystallographic form prepared according to the process of Claim 11.

15. Copper phthalocyanine (CuPc) particles exhibiting an ε

crystallographic form, the average aspect ratio of said particles being from 1 : 1 to 2: 1, preferably 1 : 1 to 1.5: 1, more preferably 1 : 1 to 1.3 : 1, most preferably around 1 : 1.