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��&�� ���� ����(11) EP 2 039 727 A1

(12) EUROPEAN PATENT APPLICATION

(43) Date of publication: 25.03.2009 Bulletin 2009/13

(21) Application number: 07116658.1

(22) Date of filing: 18.09.2007

(51) Int Cl.: �C09B 67/04 (2006.01) G03F 7/00 (2006.01)

C09B 67/12 (2006.01) C09B 67/22 (2006.01)

C09B 67/50 (2006.01)

(84) Designated Contracting States: AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HU IE IS IT LI LT LU LV MC MT NL PL PT RO SE SI SK TRDesignated Extension States: AL BA HR MK RS

(71) Applicant: SOLVAY (Société Anonyme) �1050 Bruxelles (BE) �

(72) Inventors: • Jung, KiSuck

Pusan (KR) �• Jeong, Eun- �Ha

Ulsan (KR) �

• Han, Sang- �MinPusan (KR) �

• Kim, Dong- �YoonUlsan (KR) �

• Jeong, Hyun- �SeokPusan (KR) �

• Choi, Il- �JoPusan (KR) �

(74) Representative: Vande Gucht, Anne et alSolvay S.A. Département de la Propriété Intellectuelle 310, rue de Ransbeek1120 Bruxelles (BE) �

(54) Preparation of epsilon copper phthalocyanine of small primary particle size and narrow particle size distribution

(57) A process of preparing copper phthalocyanineparticles exhibiting a ε crystallographic form, comprisinga heating step by heating at a temperature higher thanor equal to 50°C copper phthalocyanine particles withmore than 80 wt % of the particles exhibiting an α crys-

tallographic form and less than 20 wt % of particles ex-hibiting an ε crystallographic form in the presence of afirst organic liquid and optionally milling in the presenceof beads.

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Description

Technical field

�[0001] The present invention relates to a process ofpreparing epsilon crystal form copper phthalocyanine (ε-CuPc) particles of small particle size and narrow particlesize distribution, epsilon crystal form copper phthalocy-anine particles obtainable according to said process andthe use of the same for the preparation of blue filterspigments for the fabrication of liquid crystal display (LCD)devices.

Background art

�[0002] Among all pigments, copper phthalocyanine isespecially stable and is excellent in terms of a variety offastness. Further, the copper phthalocyanine has manycrystal forms. Of these crystal forms, those known to havealready found their actual use include alpha, beta andepsilon crystal forms of copper phthalocyanine. It is acommon practice to use the beta crystal form to imparta greenish blue colour and the alpha crystal form to imparta reddish blue colour. However, the epsilon crystal formis employed when the impartation of a blue colour, whichis more reddish than that available from the use of thealpha crystal form, is required.�[0003] The epsilon crystal form copper phthalocyaninehas a reddish hue, a high clearness and a high tintingstrength compared to the alpha crystal form. In addition,their solvent resistance against the crystal growth of pri-mary crystals is higher than that of the beta crystal form.Further, their solvent resistance against the crystal trans-formation into the beta crystal form is higher than that ofother polymorph copper phthalocyanines. Therefore, theepsilon crystal form copper phthalocyanine is a molecularaggregate having a crystal form, which has remarkablyexcellent properties with less apprehension about achange of hue and a decrease in tinting strength andclearness. Also, the thermodynamic stability of the epsi-lon crystal form is next to that of the beta crystal form,which is the most stable crystal form among polymorphcrystals.�[0004] It has repeatedly been disclosed that copperphthalocyanine (crystallographically crude or in the purealpha crystallographic phase) is easily convertible intoits beta crystal form, e.g., by salt grinding with a solvent,dry grinding in the presence or absence of a salt followedby solvent treatment, dry grinding with a solid binder inan inert atmosphere, or dry or aqueous grinding followedby conditioning.�[0005] Further, the typical process for the productionof epsilon crystal form copper phthalocyanine is the sol-vent salt milling process. In such a process, copperphthalocyanine particles having a crystal other than theepsilon crystal form and copper phthalocyanine particleshaving epsilon crystal form are milled in an organic sol-vent in the presence of beads by means of a strong me-

chanical force for a long time.�[0006] US 2005215780 describes a process for theproduction of epsilon crystal form copper phthalocya-nine. Such a process comprises heat-�treating copperphthalocyanine in a solvent at a temperature rangingfrom 80°C to 250°C in the presence of a Lewis acid.�[0007] JP 2005234009 discloses a blue pigment com-position for a colour filter containing epsilon crystal formcopper phthalocyanine fine pigment having 0.01 to 0.06Pm average particle diameter of primary particles (meas-ured by a transmission electron microscope). It also dis-closes a method of manufacturing the same by salt mill-ing. Said epsilon crystal form copper phthalocyanine finepigment contains a sulfonic acid amide derivative of cop-per phthalocyanine, a phthalimidemethyl derivative ofcopper phthalocyanine and a derivative containing a sul-fonic acid or its salt of phthalocyanine.�[0008] JP 2004244563 describes a method of produc-ing epsilon crystal form copper phthalocyanine pigment,wherein the pigment particles are micronized and sizedcomparable to the solvent salt milling method. In saidmethod, crude epsilon crystal form copper phthalocya-nine pigment with a greater average particle diameterthan 100 nm is added to pre-�pigment with an averageparticle diameter of 10-100 nm. The mixture is subjectedto dry grinding by adding a small amount of an organicsolvent. Particle size regulation is performed by sup-pressing a change of average particle diameter of the ε-CuPc pigment to 30 nm or less.�[0009] JP 2002121420 discloses a process of manu-facturing epsilon crystal form copper phthalocyanine finepigment. This process involves milling crude epsiloncrystal form copper phthalocyanine in the presence of anorganic solvent and a mineral salt. Such manufacturedepsilon crystal form copper phthalocyanine fine pigmenthas BET specific surface area of 95-150 m2/g in a nitro-gen absorption process. Further, it exhibits excellent dis-persibility and lightness.�[0010] US 2002014183 describes pigmentary solid so-lutions comprising copper phthalocyanine as a host andother blue to violet pigments as guests, wherein the pre-ferred hosts are the alpha, beta and epsilon crystal formsof copper phthalocyanine. Said method includes a con-version of copper phthalocyanine into epsilon crystalform by kneading with a crystalline inorganic salt or amixture of crystalline inorganic salts and an organic liq-uid.�[0011] EP 1130065 discloses a conversion of copperphthalocyanine into the epsilon crystal form. It also dis-closes a manufacture of pigment composition by wet anddry grinding of copper phthalocyanine, another polycyclicpigment and a copper phthalocyanine derivative.�[0012] KR 100215919B describes a method of manu-facturing epsilon crystal form copper phthalocyanine pig-ment using a novel copper phthalocyanine derivative.This process comprises adding 5-30 wt % of the copperphthalocyanine derivative with reference to alpha, gam-ma crystal form copper phthalocyanine or mixture thereof

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and mechanically kneading the mixture at 50-180°C torestrict crystal conversion into beta copper phthalocya-nine and derive stable crystal transition into epsilon crys-tal form copper phthalocyanine.�[0013] JP 4301648 discloses a material containingrod-�form epsilon crystal form copper phthalocyanine hav-ing 1/4-1/10 in average of the ratio of minor axis (S) tomajor axis (L). Said epsilon crystal form copper phthalo-cyanine is obtained by treating a mixture of alpha- andepsilon- crystal form copper phthalocyanines with organ-ic solvent, followed by a dry process.�[0014] JP 4252273 describes a method of producingepsilon form copper phthalocyanine, which comprisesdry grinding crude epsilon form copper phthalocyanineusing a hammer mill, etc., to give a mixture of epsilonand alpha form crystals. It also comprises heat treatingthe mixture in an organic solvent to provide the objectivecopper phthalocyanine pigment.�[0015] JP 57149358 discloses a production method ofepsilon crystal form copper phthalocyanine, which com-prises the steps of heating and stirring organic com-pounds capable of forming phthalocyanine rings, urea,Cu compounds and reaction catalysts. The improvementis that crystalline reforming agents and epsilon crystalform copper phthalocyanine crude pigment as a seedcrystal with specific surface areas of less than 35 m2/gare added at the beginning of such synthetic reaction.Said method provides pure copper phthalocyanine in aneconomic and safe manner.�[0016] FR 2278739 describes the use of a stabilizingcompound of the formula Pc-(X-- �A)n, wherein Pc is met-allized or unmetallized phthalocyanine radical, X is O, S,or -- �NH--, and A is 4-20 carbon straight or branched chainalkyl, an unsubstituted aryl, or an aryl substituted by hal-ogen, trifluoromethyl, alkyl, or alkoxy. The modified pig-ments are shown to improve the stability of unmodifiedphthalocyanine pigments towards phase transforma-tions.�[0017] FR 2174089 describes a method of isolatingpure or practically pure epsilon crystal form copperphthalocyanine by grinding alpha, beta and gamma crys-tal forms in a high energy grinder and treating with asolvent.�[0018] However, the foregoing methods of preparingepsilon crystal form copper phthalocyanine of the priorart have problems in that they need too much time forcrystal phase conversion and particle size reduction. Ithas thus been desired to develop a method of effectivelypreparing epsilon crystal form copper phthalocyaninewith reduced time for crystal phase conversion and par-ticle size reduction.

Disclosure of the invention

�[0019] It is thus a first object of the invention to providea process of preparing epsilon crystal form copperphthalocyanine, which comprises a conversion of copperphthalocyanine from alpha crystal form to epsilon crystal

form by chemical or milling treatment optionally followedby size reduction of the epsilon crystal form copperphthalocyanine by salt kneading.�[0020] Another object of the invention is to provide ep-silon crystal form copper phthalocyanine primary parti-cles of small size and narrow particle size distributionobtainable according to said process.�[0021] Still yet another object of the invention is to usesaid epsilon crystal form copper phthalocyanine particlesin the preparation of color filter pigments and in the fab-rication of liquid crystal display (LCD) devices.�[0022] Hereinafter, the present invention is describedin detail.�[0023] It is the purpose of the present invention to de-velop copper phthalocyanine (CuPc), which can be ef-fectively used as blue pigment of color filters for LCD.Such filters (e.g., phthalocyanine) must be highly trans-parent, homogeneous and able to be prepared in a layerwith a very uniform thickness. These features are decid-ed by chemical purity, crystallographic purity, primaryparticle size and particle size distribution of copperphthalocyanine. In this regard, the present invention isdirected to developing a new and more efficient processof preparing copper phthalocyanine, which satisfies theabove- �mentioned features.�[0024] The invention is therefore related to a processof preparing copper phthalocyanine particles exhibitinga ε crystallographic form, comprising a heating step byheating at a temperature higher than or equal to 50°Ccopper phthalocyanine particles with more than 80 wt %(preferably more than 85 wt %, more preferably morethan 90 wt %, the most preferably more than 95 wt %) ofthe particles exhibiting an α crystallographic form andless than 20 wt % (preferably less than 15 wt %, morepreferably less than 10 wt %, the most preferably lessthan 5 wt %) of the particles exhibiting an ε crystallo-graphic form as a seed in the presence of a first organicliquid and optionally milling in the presence of beads.�[0025] Milling, as defined herein, means a process bywhich the solids are subjected to attrition, grinding, etc.to achieve particle size reduction. Dry milling, as definedherein, means a process by which the solids are subject-ed to attrition, grinding etc. to achieve particle size re-duction while substantially free of liquid. However, a lowlevel of solvent may be added.�[0026] The process of the present invention is prefer-ably characterized by the following three steps: 1) crystalphase conversion of copper phthalocyanine from betacrystal form to alpha crystal form; 2) crystal phase con-version of copper phthalocyanine from alpha crystal formto epsilon crystal form; and 3) primary particle size re-duction of epsilon crystal form copper phthalocyanine.�[0027] The averaged primary particle size of copperphthalocyanine finally obtained by the process of thepresent invention is generally lower than or equal to 30nm, preferably lower than or equal to 20 nm, which issmaller than those of commercially available products.Since epsilon crystal form copper phthalocyanine having

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a smaller particle size causes a better contrast of colorfilter, they can be effectively used as blue filters for LCDdevices. The averaged primary particle size can be de-termined by selecting at least 50 primary particles in thetransmission electron microscope (TEM) image whichform aggregates and then obtaining an averaged valueof their longitudinal diameters.�[0028] The copper phthalocyanine particles exhibitingan α crystallographic form used in the process of theinvention can be prepared by any process. It is preferredthat they are prepared from copper phthalocyanine par-ticles exhibiting a β crystallographic form by using an acidpaste method. The beta crystal form copper phthalocy-anine is commercially available from various companiessuch as Toyo Ink (Japan), Dainippon Ink & ChemicalsCo. (Japan), etc. The beta crystal form copper phthalo-cyanine is subjected to crystal phase conversion into al-pha crystal form by acid pasting. Acid pasting refers tothe dissolution preferably complete of the pigment pref-erably crude in an acid followed by precipitation. Prefer-ence is given to using acids such as sulfuric acid, chlo-rosulfonic acid and polyphosphoric acid. The precipita-tion medium, which is employed, generally compriseswater, organic solvents or mixtures thereof. Precipitationtakes place preferably under turbulent flow conditions.Such a treatment is described for instance in Ullmann’sEncyclopedia of Industrial Chemistry, Fifth CompletelyRevised Edition, 1992, Volume A20, pp. 225-226.�[0029] In step 2, the alpha crystal form copper phthalo-cyanine is subjected to crystal phase conversion into ep-silon crystal form by chemical or milling treatment.�[0030] In the process of the invention, the alpha crystalform copper phthalocyanine is treated at a temperaturehigher than or equal to 50°C, preferably higher than orequal to 75°C, more preferably higher than or equal to100°C, yet more preferably higher than or equal to 125°C,and most preferably higher than or equal to 150°C. Thetemperature of the heating step is generally lower thanor equal to 210°C, preferably lower than or equal to200°C, more preferably lower than or equal to 190°C, yetmore preferably lower than or equal to 180°C, and mostpreferably lower than or equal to 170°C. When the tem-perature is lower than 50°C, the conversion from the al-pha crystal form into the epsilon crystal form does notoccur. When the temperature is higher than 210°C, dis-advantageously as a pigment, primary crystals grow andthe thermal energy tends to be wasted.�[0031] In the process according to the invention, theduration of the heating step is generally higher than orequal to 0.5 h, more preferably higher than or equal to 1h, yet more preferably higher than or equal to 2 h, andmost preferably higher than or equal to 3 h. That durationis generally lower than or equal to 12 h, preferably lowerthan or equal to 10 h, more preferably lower than or equalto 8 h, yet more preferably lower than or equal to 6 h,and most preferably lower than or equal to 4 h.�[0032] In the process of the invention, the heating stepis carried out in the presence of a first organic liquid. The

first organic liquid suitable for the use in the present in-vention may include, but is not limited to, N- �methyl-�2-pyrrolidone, sulfolane, N,�N-�dimethyl formamide, glycolsand glycols derivatives such as propylene glycol mono-methyl ether acetate, diethylene glycol, alcohols such asdiacetone alcohol, acetonitrile, monochlorobenzene,ethylene glycol butyl ether,� ketones and quinolines, pref-erably N-�methyl- �2-�pyrrolidone and any mixture of at leasttwo of them. The first organic liquid may further comprisewater.�[0033] In the process according to the invention, theheating step can be carried out under agitation or in theabsence of agitation. It is preferred to carry it out underagitation.�[0034] The proportion of the first organic liquid used inthe present invention to the alpha crystal form copperphthalocyanine by weight ratio is generally higher thanor equal to 0.033 and preferably higher than or equal to0.05. That ratio is usually lower than or equal to 0.2 andmore preferably lower than or equal to 0.1.�[0035] In the process according to the invention, theheating step optionally comprises milling in the presenceof beads.�[0036] In such embodiment, the alpha crystal form cop-per phthalocyanine is treated at a temperature higherthan or equal to 50°C, preferably higher than or equal to60°C, more preferably higher than or equal to 70°C, andmost preferably higher than or equal to 80°C. The tem-perature of the heating step is generally lower than orequal to 210°C, preferably lower than or equal to 180°C,more preferably lower than or equal to 150°C, yet morepreferably lower than or equal to 120°C, and most pref-erably lower than or equal to 100°C.�[0037] In such embodiment, the duration of the heatingstep is generally higher than or equal to 0.5 h, more pref-erably higher than or equal to 1 h, yet more preferablyhigher than or equal to 2 h, and most preferably higherthan or equal to 3 h. That duration is generally lower thanor equal to 12 h, preferably lower than or equal to 10 h,more preferably lower than or equal to 6 h, and mostpreferably lower than or equal to 4 h.�[0038] In such embodiment, the heating step is carriedout in the presence of a first organic liquid. The first or-ganic liquid suitable for the use in the present inventionmay include, but is not limited to, N-�methyl- �2-�pyrrolidone,sulfolane, N, �N-�dimethyl formamide, glycols such as pro-pylene glycol monomethyl ether acetate, diethylene gly-col, alcohols such as diacetone alcohol, acetonitrile,monochlorobenzene, ethylene glycol butyl ether, ke-tones and quinolines, preferably N-�methyl- �2-�pyrrolidone.The first organic liquid may further comprise water.�[0039] In such embodiment, the proportion of theamount of the first organic liquid used in the present in-vention to the amount of the alpha crystal form copperphthalocyanine by weight ratio is as defined hereaboveon page 7, lines 6 to 9.�[0040] The beads suitable for the use in the presentinvention as a milling media may include, but is not limited

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to, metallic beads, plastic beads, inorganic oxide beadssuch as zirconia and glass beads, preferably zirconiabeads. The proportion of the beads used in the presentinvention to the alpha crystal form copper phthalocyanineby weight ratio is generally higher than or equal to 0.01and preferably higher than or equal to 0.166. That pro-portion is usually lower than or equal to 0.5 and morepreferably lower than or equal to 0.333.�[0041] Through the heating treatment describedabove, the alpha crystal form copper phthalocyanine canbe effectively converted into the epsilon crystal form hav-ing a narrow particle size distribution, which was deter-mined from D10 and D90 percentiles measured by a Par-ticle Size Analyzer.�[0042] The process according to the invention may fur-ther comprise the following steps :�

a) a separation step by separating the copperphthalocyanine particles exhibiting a ε crystallo-graphic form from the first organic liquid and option-ally from the beads;b) a kneading step by kneading the copper phthalo-cyanine particles separated at step a) with at leastone inorganic salt and a second organic liquid; andc) a recovery step by recovering the copper phthalo-cyanine particles by removing the second organicliquid and the inorganic salt.

�[0043] The separation step can be carried out by anymeans, for instance filtration using any appropriate filter,decantation, centrifugation, etc. Preferably, filtration canbe used to separate the copper phthalocyanine particlesexhibiting a ε crystallographic form.�[0044] In order to reduce the primary particle size ofthe epsilon crystal form copper phthalocyanine convert-ed above, the step of kneading the same with salt is con-ducted in the presence of at least a second organic liquid.For the preferred salt kneading process, it is possible touse a typical continuous kneading unit well known in theart including a single kneading-�screw type and a twinkneading- �screw type. In a preferred embodiment, thepresent invention employs a salt- �kneading system as il-lustrated in Fig. 1.�[0045] The kneading step is carried out for a durationwhich is generally higher than or equal to 2 h, preferablyhigher than or equal to 3 h, more preferably higher thanor equal to 5 h and most preferably higher than or equalto 6 h. That duration is generally lower than or equal to36 h, preferably lower than or equal to 18 h, more pref-erably lower than or equal to 12 h and most preferablylower than or equal to 8 h.�[0046] The kneading step is carried out at a tempera-ture which is generally higher than or equal to 0°C andpreferably higher than or equal to 10°C and most prefer-ably higher than or equal to 50°C. That temperature isgenerally lower than or equal to 130°C, preferably lowerthan or equal to 80°C and more preferably lower than orequal to 60°C.

�[0047] The second organic liquid suitable for thekneading step may include, but is not limited to, N-�methyl-2-�pyrrolidone, sulfolane, N,�N-�dimethyl formamide, dieth-ylene glycol, N- �methyl formamide, diacetone alcohol,glycerin, ethylene glycol, propylene glycol, polypropyl-ene glycol, 2-�butoxy ethanol, triethylene glycol, diethyl-ene glycol monomethyl ether, triethylene glycol mono-methyl ether, dipropylene glycol monomethyl ether, 1-methoxy- �2-�propanol, �1-�ethoxy-�2-�propanol, ketones, qui-nolines, and any mixture of at least two of them, and thesecond organic liquid is preferably N- �methyl-�2-�pyrro-lidone. The second organic liquid may further comprisewater.�[0048] In the kneading step, the proportion of the sec-ond organic liquid to the epsilon crystal form copperphthalocyanine by weight ratio is generally higher thanor equal to 0.033 and more preferably higher than orequal to 0.050. That proportion is generally lower thanor equal to 1.0 and more preferably lower than or equalto 0.666.�[0049] In the kneading step of the process accordingto the present invention, the inorganic salt suitable forthe salt kneading process may include, but is not limitedto, aluminum sulfate, sodium sulfate, calcium chloride,potassium chloride or sodium chloride, preferably sodi-um chloride which may if desired and available containwater of crystallization. The proportion of the inorganicsalt to the epsilon crystal form copper phthalocyanine byweight ratio is generally higher than or equal to 0.067and preferably higher than or equal to 0.1. That proportionis generally lower than or equal to 1.0 and more prefer-ably lower than or equal to 0.2.�[0050] The inorganic salt has an average particle sizewhich is generally higher than or equal to 0.3 Pm. Thataverage particle size is generally lower than or equal to200 Pm, preferably lower than or equal to 50 Pm, whichwas measured by a Particle Size Analyzer. The inorganicsalt is generally soluble in water, preferably to the extentof at least 10 g/�100 ml of water.�[0051] The rotary speed of the salt kneading systemused in the present invention should be adjusted, takinginto account the cooling if necessary, in such a way thatthe kneaded composition is moved homogeneously un-der uniform share. It is preferable to maintain the rotaryspeed during the salt kneading to the range from 30 to150 rpm, more preferably from 50 to 120 rpm.�[0052] After the kneading step c), the copper phthalo-cyanine particles are recovered by removing the inorgan-ic salt and the second organic liquid. The removal canbe done by any means. It is preferred that it is done bywashing the inorganic salt and the second organic liquidaway with water, especially with demineralized water.�[0053] The process according to the invention maycomprise a further drying step after step c). The dryingstep is conducted preferably at a temperature higher thanor equal to -20°C and lower than or equal to 250°C for apressure higher than or equal to 10-1 Pa and lower thanor equal to 105 Pa, with very particular preference at a

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temperature around 80°C and for a pressure around 104

Pa.�[0054] In order to increase dispersability of the result-ant copper phthalocyanine particles exhibiting a ε crys-tallographic form, particles of copper phthalocyaninesubstituted by a functional group (dispersion aid) may befurther added during the acid pasting step and/or theheating step optionally in the presence of beads and/orduring the kneading step b) of the process according tothe invention. In addition, the process of the present in-vention may further comprise the step of dry- �blending,wherein particles of copper phthalocyanine substitutedby a functional group are further blended after the recov-ery step c).�[0055] The particles of copper phthalocyanine used asa dispersion aid in the present invention may be substi-tuted by at least one functional group selected from-SO3M, -SO2NR1R2 and -R3-NR4R5, wherein: R1 and R2are independent of one another and are hydrogen, alkyl,alkenyl, aryl or cycloalkyl; M is proton, ammonium cationor metal cation; R3 is single bond, alkylene, arylene, saidalkylene and arylene may be substituted by at least onesubstituent; and R4 and R5 are independent of one an-other and are hydrogen, alkyl, alkenyl, aryl or cycloalkyl,or collectively form a condensed structure containing atleast one of -CO-, -SO2- and -N=N-.�[0056] More preferably, the particles of copperphthalocyanine may be substituted by the functionalgroup of -SO3H, -SO2NHR1 , wherein R1 is hydrogen,alkyl, alkenyl, aryl, cycloalkyl or

�[0057] In a preferred embodiment, the process accord-ing to the invention comprises the following steps :�

1) preparing copper phthalocyanine particles withmore than 80 wt % of the particles exhibiting an αcrystallographic form from copper phthalocyanineparticles exhibiting a β crystallographic form by usingan acid paste method2) a heating step by heating at a temperature higherthan or equal to 50°C the copper phthalocyanine par-ticles with more than 80 wt % of the particles exhib-iting an α crystallographic form of step 1) and lessthan 20 wt % of the particles exhibiting an ε crystal-lographic form in the presence of a first organic liquidand optionally milling in the presence of beads3) separating the copper phthalocyanine particlesexhibiting a ε crystallographic form from the first or-ganic liquid and optionally the beads;4) kneading the copper phthalocyanine particlesseparated at step a) with at least one inorganic salt

and a second organic liquid; and5) recovering the copper phthalocyanine particles byremoving the second organic liquid and the inorganicsalt.

�[0058] In spite of reducing the kneading time comparedto the existing method in the art, the process of thepresent invention can obtain epsilon crystal form copperphthalocyanine having a smaller averaged primary par-ticle size, a narrower size distribution and a better primaryparticle shape.�[0059] The average primary particle size is generallylower than or equal to 30 nm, preferably lower than orequal to 20 nm.�[0060] The particle size distribution (PSD) is measuredby a Particle Size Analyzer (PSA). The narrowness ofthe particle size distribution is characterized from D10and D90 values measured by the PSA.�[0061] The primary particle shape of the CuPc particlesis preferably a spherical shape, when observed by theirTEM image.�[0062] It is believed that one embodiment of thepresent invention provides combination of the chemicalor milling treatment and kneading steps, by which CuPcparticles exhibiting α-�crystallographic form is convertedto ε-�crystallographic form easily and crystal purity is alsoimproved, and further the process reduces the time forcrystal phase conversion and particle size reduction.�[0063] The present invention provides a process ofpreparing epsilon crystal form copper phthalocyanineparticles, comprising a heating step by heating at a tem-perature of higher than equal to 50°C copper phthalocy-anine particles with more than 80 wt % of the particlesexhibiting an alpha crystal form and less than 20 wt % ofthe particles exhibiting an epsilon crystal form in the pres-ence of a first organic liquid and optionally milling in thepresence of beads.�[0064] The process of the present invention may fur-ther comprise the following steps :�

a) a separation step by separating the epsilon crystalform copper phthalocyanine particles from the firstorganic liquid and the beads, if used;b) a kneading step by kneading the copper phthalo-cyanine particles separated at step a) with at leastone inorganic salt and a second organic liquid to ob-tain the copper phthalocyanine particles having anaveraged particle size of less than 30 nm; andc) a recovery step by recovering the copper phthalo-cyanine particles by removing the second organicliquid and the inorganic salt.

�[0065] In the process of the present invention, the cop-per phthalocyanine particles with more than 80 wt % ofthe particles exhibiting an alpha crystal form may be pre-pared from copper phthalocyanine particles exhibiting abeta crystal form by using an acid paste method.�[0066] The first organic liquid used in the process of

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the present invention may include, but is not limited to,at least one liquid selected from the group consisting ofN-�methyl- �2-�pyrrolidone, sulfolane, N,�N- �dimethyl forma-mide, glycols such as propylene glycol monomethyl etheracetate, diethylene glycol, alcohols such as diacetonealcohol, acetonitrile, monochlorobenzene, ethylene gly-col butyl ether, ketones and quinolines. The first organicliquid may further comprise water.�[0067] The second organic liquid used in the processof the present invention may include, but is not limitedto, at least one liquid selected from the group consistingof N-�methyl- �2-�pyrrolidone, sulfolane, N,�N- �dimethyl for-mamide, diethylene glycol, diacetone alcohol, glycerin,ethylene glycol, propylene glycol, polypropylene glycol,2-�butoxy ethanol, triethylene glycol, diethylene glycolmonomethyl ether, triethylene glycol monomethyl ether,dipropylene glycol monomethyl ether, 1-�methoxy-�2-�pro-panol and 1-�ethoxy- �2- �propanol, ketones and quinolines.The second organic liquid may further comprise water.�[0068] The heating step in the process of the presentinvention may be conducted in the absence of beads ata temperature higher than or equal to 50°C and lowerthan or equal to 210°C. Alternatively, the heating stepmay be conducted in the presence of beads at a temper-ature higher than or equal to 50°C and lower than or equalto 210°C.�[0069] The beads used in the process of the presentinvention may include, but are not limited to, at least oneof metallic, plastic, inorganic oxide such as zirconia andglass beads.�[0070] It is preferable to further add the particles ofcopper phthalocyanine substituted by at least one func-tional group during the heating, acid paste step or knead-ing, wherein the functional group may be selected fromthe group consisting of -SO3M, -SO2NR1R2 and-R3-NR4R5, and wherein: R1 and R2 are independent ofone another and are hydrogen, alkyl, alkenyl, aryl or cy-cloalkyl; M is proton, ammonium cation or metal cation;R3 is a single bond, alkylene, arylene, said alkylene andarylene may be substituted by at least one substituent;and R4 and R5 are independent of one another and arehydrogen, alkyl, alkenyl, aryl or cycloalkyl, or collectivelyform a condensed structure containing at least one of-CO-, -SO2- and -N=N-.�[0071] Alternatively, the process of the present inven-tion may further comprise the step of dry- �blending,wherein the particles of copper phthalocyanine substitut-ed by at least one functional group are further blendedwith the copper phthalocyanine particles as a dispersionaid after the recovery step c), wherein the functionalgroup may be selected from the group consisting of-SO3M, -SO2NR1R2 and -R3-NR4R5, and wherein: R1and R2 are independent of one another and are hydro-gen, alkyl, alkenyl, aryl or cycloalkyl; M is proton, ammo-nium cation or metal cation; R3 is a single bond, alkylene,arylene, said alkylene and arylene may be substitutedby at least one substituent; and R4 and R5 are independ-ent of one another and are hydrogen, alkyl, alkenyl, aryl

or cycloalkyl, or collectively form a condensed structurecontaining at least one of -CO-, -SO2- and -N=N-.�[0072] Preferably, the particles of copper phthalocya-nine used as a dispersion aid in the present inventionmay be substituted by the functional group of -SO3H,-SO2NHR1 wherein R1 is hydrogen, alkyl, alkenyl, aryl,cycloalkyl or

�[0073] The present invention is also directed to epsiloncrystal form copper phthalocyanine particles obtainableaccording to the process of the present invention. Thepresent invention is further directed to the use of the samein the preparation of color filter pigments.�[0074] Further, the present invention is directed to col-our filter pigments comprising the epsilon crystal formcopper phthalocyanine particles prepared according tothe process of the present invention. Also, the presentinvention is directed to the use of the same in the fabri-cation of liquid crystal display devices.

Brief description of drawings

�[0075]

Fig. 1 shows a salt-�kneading system used in theprocess of the present invention.Figs. 2 and 3 show transmission electron micro-graphs of the epsilon crystal form copper phthalocy-anine particles obtained before and after the salt-kneading, respectively, according to the process ofthe present invention.Fig. 4 shows a transmission electron micrograph ofthe epsilon crystal form copper phthalocyanine par-ticles commercially available (purchased from Dain-ippon Ink & Chemicals Co. located in Japan).

Examples

Preparation of epsilon crystal form copper phthalo-cyanine

�[0076]

1) Crystal phase conversion of copper phthalocya-nine from beta crystal form to alpha crystal form80 parts by weight of the crude copper phthalocya-nine is added to 800 parts by weight of 95 wt % sul-furic acid. Further, the resultant mixture is stirred for3 hours to prepare a suspension or solution of sulfatein the sulfuric acid. The suspension or the solutionis poured to two times 8L of water to obtain an alpha

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crystal form copper phthalocyanine, which is thendried under hot air. After pulverizing the resulted sol-id, the alpha crystal form copper phthalocyanine isobtained almost quantitatively in terms of crystallo-graphic yield, which is confirmed by a XRD study.2) Crystal phase conversion of copper phthalocya-nine from alpha crystal form to epsilon crystal form60 parts by weight of the obtained alpha crystal formcopper phthalocyanine and 12 parts by weight of theepsilon- �type copper phthalocyanine are treated at130°C for 2 hours in 750 parts by weight of N-�methyl-2-�pyrrolidone. After separating the phase- �convertedcopper phthalocyanine particles by filtration and an-alyzing with a transmission electron microscope(TEM), copper phthalocyanine particles exhibiting apure ε crystallographic form are obtained, which isconfirmed by a XRD study showing no existence ofβ crystallographic form.3) Primary particle size reduction of epsilon crystalform copper phthalocyanineTo a lab-�scale kneader, 50 parts by weight of theobtained copper phthalocyanine particles exhibitinga ε crystallographic form are added with 80 parts byweight of diethylene glycol and 400 parts by weightof sodium chloride. The mixture is kneaded for 12hours at 80°C with rotation speed of 45 rpm. Afterkneading, the resultant particles are purified by fil-tration and dried at temperature of 80°C, pressureof 104 Pa. Upon analyzing the particles with TEM,the obtained copper phthalocyanine particles havesmaller primary particle size and better particleshape compared to those of commercially availablecopper phthalocyanine particles (purchased fromDainippon Ink & Chemicals Co. located in Japan).

Claims

1. A process of preparing copper phthalocyanine par-ticles exhibiting a ε crystallographic form, comprisinga heating step by heating at a temperature higherthan or equal to 50°C copper phthalocyanine parti-cles with more than 80 wt % of the particles exhibitingan α crystallographic form and less than 20 wt % ofparticles exhibiting an ε crystallographic form in thepresence of a first organic liquid and optionally mill-ing in the presence of beads.

2. The process of Claim 1, further comprising the fol-lowing steps : �

a) a separation step by separating the copperphthalocyanine particles exhibiting a ε crystal-lographic form from the first organic liquid andthe beads, if used;b) a kneading step by kneading the copperphthalocyanine particles separated at step a)with at least one inorganic salt and a second

organic liquid to obtain the copper phthalocya-nine particles having an averaged particle sizeof less than 30 nm; andc) a recovery step by recovering the copperphthalocyanine particles by removing the sec-ond organic liquid and the inorganic salt.

3. The process of Claim 1 or 2, wherein the copperphthalocyanine particles with more than 80 wt % ofthe particles exhibiting an α crystallographic form areprepared from copper phthalocyanine particles ex-hibiting a β crystallographic form by using an acidpaste method.

4. The process of any one of Claims 1 to 3, whereinthe first organic liquid is at least one liquid selectedfrom the group consisting of N-�methyl-�2-�pyrrolidone,sulfolane, N,�N-�dimethyl formamide, glycols such aspropylene glycol monomethyl ether acetate, diethyl-ene glycol, alcohols such as diacetone alcohol, ac-etonitrile, monochlorobenzene, ethylene glycol butylether, ketones and quinolines.

5. The process of any one of Claims 2 to 4, whereinthe second organic liquid is at least one liquid se-lected from the group consisting ofN-�methyl-�2-�pyr-rolidone, sulfolane, N, �N-�dimethyl formamide, dieth-ylene glycol, diacetone alcohol, glycerin, ethyleneglycol, propylene glycol, polypropylene glycol, 2-�bu-toxy ethanol, triethylene glycol, diethylene glycolmonomethyl ether, triethylene glycol monomethylether, dipropylene glycol monomethyl ether, 1-�meth-oxy-�2-�propanol, 1-�ethoxy- �2-�propanol, ketones andquinolines.

6. The process of any one of Claims 1 to 5, whereinthe heating step is conducted in the absence ofbeads at a temperature higher than or equal to 50°Cand lower than or equal to 210°C.

7. The process of any one of Claims 1 to 5, whereinthe heating step is conducted in the presence ofbeads at a temperature higher than or equal to 50°Cand lower than or equal to 210°C.

8. The process of any one of Claims 1 to 5 and 7, where-in the beads are at least one of metallic, plastic, in-organic oxide such as zirconia and glass beads.

9. The process of any one of Claims 1 to 8, whereinparticles of copper phthalocyanine substituted by atleast one functional group selected from the groupconsisting of -SO3M, -SO2NR1R2 and -R3-NR4R5,�wherein R1 and R2 are independent of one anotherand are hydrogen, alkyl, alkenyl, aryl or cycloalkyl;M is proton, ammonium cation or metal cation; R3 isa single bond, alkylene, arylene, said alkylene andarylene may be substituted by at least one substitu-

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ent; and R4 and R5 are independent of one anotherand are hydrogen, alkyl, alkenyl, aryl or cycloalkyl,or collectively form a condensed structure containingat least one of -CO-, -SO2- and -N=N-, �are further added during the heating, acid paste orkneading step.

10. The process of any one of Claims 2 to 8, further com-prising a step of dry- �blending wherein particles ofcopper phthalocyanine substituted by at least onefunctional group selected from the group consistingof -SO3M, -SO2NR1R2 and -R3-NR4R5, �wherein R1 and R2 are independent of one anotherand are hydrogen, alkyl, alkenyl, aryl or cycloalkyl;M is proton, ammonium cation or metal cation; R3 isa single bond, alkylene, arylene, said alkylene andarylene may be substituted by at least one substitu-ent; and R4 and R5 are independent of one anotherand are hydrogen, alkyl, alkenyl, aryl or cycloalkyl,or collectively form a condensed structure containingat least one of -CO-, -SO2- and -N=N-, �are further blended with the copper phthalocyanineparticles after the recovery step c).

11. The process of Claim 9 or 10, wherein the functionalgroup is -SO3H, -SO2NHR1, wherein R1 is hydrogen,alkyl, alkenyl, aryl, cycloalkyl, or

12. Copper phthalocyanine particles obtainable accord-ing to the process of any one of Claims 1 to 11.

13. Copper phthalocyanine particles according to claim12 having an averaged particle size lower than orequal to 30 nm, as measured by a transmission elec-tron microscope.

14. Color filter pigments comprising the copper phthalo-cyanine particles according to Claim 12 or 13.

15. Use of the copper phthalocyanine particles accord-ing to Claim 12 or 13 in the preparation of color filterpigments.

16. Use of the color filter pigments according to Claim14 in the fabrication of liquid crystal display devices.

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REFERENCES CITED IN THE DESCRIPTION

This list of references cited by the applicant is for the reader’s convenience only. It does not form part of the Europeanpatent document. Even though great care has been taken in compiling the references, errors or omissions cannot beexcluded and the EPO disclaims all liability in this regard.

Patent documents cited in the description

• US 2005215780 A [0006]• JP 2005234009 B [0007]• JP 2004244563 B [0008]• JP 2002121420 B [0009]• US 2002014183 A [0010]• EP 1130065 A [0011]

• KR 100215919 B [0012]• JP 4301648 B [0013]• JP 4252273 B [0014]• JP 57149358 B [0015]• FR 2278739 [0016]• FR 2174089 [0017]

Non-patent literature cited in the description

• Ullmann’s Encyclopedia of Industrial Chemistry.1992, vol. A20, 225-226 [0028]