MXPA97003122A

MXPA97003122A - Incorporation of pigment derivatives enprocedimientos de quinacrid

Info

Publication number: MXPA97003122A
Application number: MXPA/A/1997/003122A
Authority: MX
Inventors: Campos Margot; T Badejo Ibraheem; J Rice Daphne; j greene Michael
Original assignee: Bayer Corporation
Priority date: 1996-04-29
Filing date: 1997-04-29
Publication date: 1998-07-03

Abstract

The present invention relates to a process for the preparation of quinacridone pigments consisting of: (a) heating at a temperature of 80 ° C to 145 ° C, a reaction mixture consisting of: (i) 2,5-dianilinoterephthalic acid, an ester of acid 2 , 5-dianilino-6,13-dihydroterephthalic acid, a derivative of 2,5-dianilinoterephthalic acid or a 2,5-dianilino-6,13-dihydro-terephthalic acid ester having one or more substituents in at least one aniline ring or a mixture of these ii) 3 to 15 parts by weight, by component (a) (i), of a dehydrating agent, and iii) 0.1 to 15 percent by weight, based on component (a) (i) ), of one or more non-quinacridonic pigments, with the proviso that, if the component (a) (i) is a 2,5-dianilino-6,13-dihydroterephthalic acid ester or a derivative thereof, the reaction step ( a) additionally consists of an oxidation step, (b) drowning the reaction mixture of step (a) by adding said reaction mixture. ion of 3 to 15 parts by weight, by component (a) (i), of a liquid in which the quinacridone pigment is substantially insoluble, (c) isolating the quinacridone pigment, (d) eventually conditioning the quinacridone pigment, and e) optionally, mixing the quinacridone pigment with one or more quinacridic derivatives

Description

INCORPORATION OF PIGMENT DERIVATIVES IN QUINACRIDONE PROCEDURES BACKGROUND OF THE INVENTION This invention relates to a process for the preparation of quinacridone pigments having a reduced particle size, better coloristic properties, better rheological properties and lower manufacturing costs. The addition of certain pigments and / or their derivatives during the synthesis of quinacridone provides quinacridone pigments that have more intense and brighter dough tones and better transparency and rheological properties, as well as brighter and bluer metal shades and bluer dyes. Additionally, because a reduction in the melt viscosity allows higher loads of raw materials during ring closure, manufacturing costs are, in general, lower. Methods for the preparation of quinacridone are known. For example, S.S. Labana and L.L. Labana, "Quinacridones", in Chemical Review, 67, 1-18 (1967) and US Patents. 3,157,659, 3,256,285 and 3,317,539. The quinacridones thus obtained, known as crude quinacridones, are generally unsuitable for use as pigments and must undergo one or more additional finishing steps to modify the particle size, particle shape or crystal structure and achieve pigment quality. A preferred method for the preparation of quinacridones includes the thermal induction of the ring closure of intermediates 2, 5-dianilinoterephthalic acid, as well as known derivatives of the same aniline-substituted, in the presence of polyphosphoric acid. For example, U.S. Pat. 3,257,405. After completion of the ring closure, the melt is drowned by pouring it into a liquid in which the quinacridone, usually water and / or an alcohol, is substantially insoluble. The resulting crystalline pigment is then further conditioned by solvent treatment or milling in combination with solvent treatment. It is also possible to use 2,5-dianilino-6,13-dihydroterephthalic acid esters as the starting material in the reaction of the ring closure. The resulting dihydroquinacridone must, however, be oxidized to the corresponding quinacridone before isolation and conditioning. The final particle size of the quinacridone pigments can be controlled by the methods used in both the synthesis and the post-treatment. For example, quinacridone pigments can be made more transparent by reducing the particle size, or more opaque by increasing the particle size. In known methods, the particle size is generally controlled during pigment precipitation by immersion or during grinding or solvent treatment of the crude pigment. The dyeing strength and the transparency of the pigments can also be affected by the treatment with solvents. Often, reference is made to the post-treatment stages that manipulate the particle size of the raw pigments as conditioning methods. Several suitable conditioning methods are known. However, the most commonly employed methods include the grinding of dry crude quinacridones, generally in the presence of undesirably large amounts of an inorganic salt that must be subsequently removed. The pigment quinacridones can also be obtained by premixing the dry raw material first and then treating the ground material with an organic liquid. Other methods include a pre-grinding step, followed by another grinding step using water and small amounts of an organic liquid. The pigment quinacridones can also be obtained by heat treatment of the filter cake in large amounts of solvent. Various additives have been added during the grinding, solvent treatment or post-treatment with solvents stages to further improve the properties of the pigment. For example, US Pat. No. 4,455,173 discloses a process in which crude quinacridone pigments are acid-blasted or subjected to a ball mill and then ground into an organic liquid, preferably in the presence of a particle size growth inhibitor of 2-5%. phthalimidomethylquinacridone. U.S. Pat. No. 5,084,100 discloses a method in which crude quinacridone is subjected to a ball mill in the presence of aluminum sulfate and esters of alkanedicarboxylic acids. The addition of certain quinacridone derivatives to the ring closure stage has been discussed. For example, U.S. Pat. 5,368,641 describes the use of various quinacridone derivatives in the manufacture of 2,9-dimethylquinacridone. The present invention, on the other hand, uses pigment classes other than quinacridones as an additive. In addition, European Patent Application 643,110 describes the use of quinacridone derivatives during the oxidation of dihydroquinacridone (prepared from 2,5-dianilino-6,13-dihydroterephthalic acid) to quinacridone. The present invention, on the other hand, not only uses pigments other than quinacridones as additives, but also uses the pigment additives in the ring closure stage. Pigment derivatives other than those of quinacridones have been described as being useful for the treatment of various pigments, including quinacridone (e.g., U.S. Patents 4,310,359 and 5,472,494), but such derivatives have been typically added to fully formed quinacridone pigments. Although the physical properties of quinacridone pigments can often be improved in this way, the treatment of quinacridones with colored pigments other than quinacridones, including derivatives of said colored pigments, produces, in general, undesirable coloristic properties, at least in part , because quinacridone and pigment derivatives typically have different color properties. It has now been found, however, that the addition of specified amounts of pigments other than the quinacridones to the ring closure stage can provide quinacridone pigments which have desirable color properties and which can not be achieved otherwise, even when preparing the quinacridones in the presence of quinacridone derivatives. The present invention provides quinacridones of smaller particle size which have better rheological properties and transparency, by the addition of certain pigments and / or their derivatives to the step of ring closure of the synthesis of quinacridone. In addition, because the presence of the non-quinacridone pigment during ring closure (preferably in polyphosphoric acid) reduces the viscosity of the reaction melt, it is possible to increase the loads of raw materials without adverse side effects, thereby reducing the costs of manufacture. The addition of a non-quinacridone pigment during quinacridone synthesis (ie, ring closure) prior to precipitation results in a more intense and brighter pigment that has better transparency and rheological properties, as well as brighter metallic shades and more blues and bluer dyes. The process of the present invention is, in principle, applicable to all methods of manufacturing quinacridone pigments that include an "acid etching" step, but the greatest improvement is expected in the color properties for the methods of closing the ring, including the procedures used to prepare solutions of quinacridone solids. COMPENDIUM OF THE INVENTION This invention relates to a process for the preparation of quinacridone pigments which consists of: (a) heating, at a temperature of about 80 ° C to about 1 5 ° C (preferably 100 ° C to 130 ° C) ) (preferably for about one to about 24 hours), a reaction mixture consisting of (i) 2, 5-dianilinoterephthalic acid, an ester of 2,5-dianilino-6,13-dihydroterephthalic acid, a derivative of 2,5-dianilinoterephthalic acid or an ester of acid 2, 5 -dianilino-6, 13-dihydroterephthalic having one or more substituents in at least one aniline ring, or a mixture thereof; (ii) about 3 to about 15 parts by weight (preferably 3 to 10 parts by weight), on the part of component (a) (i), of a dehydrating agent (preferably, polyphosphoric acid), (iii) about 0.1 to 5 percent by weight (preferably 0.1 to 10 percent by weight, more preferably 0.1 to 5 percent by weight), based on component (a) (i), one or more non-quinacridone pigments (preferably as copper phthalocyanine, perylene or dioxazine), with the proviso that, if component (a) (i) is an ester of 2,5-dianilino-6, 13-dihydroterephthalic acid or a derivative thereof, the reaction stage (a) additionally includes an oxidation step (which converts the dihydroquinacridone intermediate initially formed into the corresponding quinacridone); (b) drowning the reaction mixture of step (a) by adding said reaction mixture at about 3 to about 15 parts by weight (preferably 5 to 10 parts by weight), on the part of component (a) (i), of a liquid in which the quinacridone pigment is substantially insoluble; (c) isolating the quinacridone pigment; (d) optionally, conditioning the quinacridone pigment, and (e) optionally mixing (preferably dry mix) the resulting quinacridone pigment with one or more quinacridone derivatives.

DETAILED DESCRIPTION OF THE INVENTION The quinacridone pigments (by which the unsubstituted quinacridone is understood, the quinacridone derivatives and the solid solutions thereof) are prepared according to the invention primarily by the ring closure of the acid intermediates 2, 5-dianilinoterephthalic, including the known aniline-substituted derivatives thereof, by heating said intermediates of terephthalic acid in the presence of a dehydrating agent (preferably polyphosphoric acid) and a non-quinacridone pigment according to the invention, or, less preferably , thermally inducing ring closure in a high boiling point solvent in the presence of a non-quinacridone pigment according to the invention. Quinacridone is then drowned and isolated by known methods. The quinacridone pigment is preferably also subjected to further conditioning steps to improve the pigment properties and, if desired, mixed with an additional quinacridone derivative. The process of the invention can be employed to prepare unsubstituted quinacridone or substituted quinacridone derivatives in the ring, depending on whether ring closure is carried out using 2,5-dianilinoterephthalic acid or derivatives thereof having one or more substituents on at least one of the two aniline rings. Although essentially any 2, 5-dianilinote-reftalic acid derivative known in the art can be used, particularly preferred 2,5-dianilinoterephthalic acid derivatives are those in which both aniline moieties are substituted (typically with the same substituent) in the position for groups such as halogen (preferably chlorine), C? -C6 alkyl (preferably methyl) and C? -C6 alkoxy (preferably methoxy). It is also possible to use 2, 5-dianilinoterephthalic acid derivatives in which both aniline residues are substituted in the ortho or meta positions. Examples of suitable derivatives of 2,5-dianilinoterephthalic acid include 2,5-di (4-chloroanilino) terephthalic acid, 2,5-di (4-methylane-lino) terephthalic acid, and 2,5-di (4-methyl) acid. -methoxyanilino) terephthalic. It is also possible to use mixtures containing 2,5-dianilinoterephthalic acid and one or more derivatives thereof or mixtures containing two or more derivatives of 2,5-dianilinoterephthalic acid. The use of such mixtures provides a particularly advantageous method for obtaining solid solutions of quinacridone. Mixtures containing 2, 5-dianilinote-reftalic acid and / or a derivative thereof in combination with a fully formed quinacridone pigment (generally in crude form) can also be frequently used. The step (a) of closing the ring is carried out in a dehydrating agent, particularly a strong acid such as polyphosphoric acid, acid esters of polyphosphoric acid or sulfuric acid. For example, U.S. Pat. 4,758,665 and S.S. Labana and L.L. Labana, "Quinacridones", in Chemical Reviews, 67, 1-18 (1967). In particular, polyphosphoric acid having a phosphate content equivalent to about 110-120% H3PO4 is preferred. When polyphosphoric acid is used, the weight ratio of polyphosphoric acid to the terephthalic acid intermediate is typically from about 3: 1 to about 10: 1 (preferably 4: 1 to 8: 1). The lower ratios can give high viscosity reaction masses. However, because the presence of pigment derivatives during ring closure tends to give lower melt viscosities, the lower ratios are generally effective. Moreover, even when the viscosities are relatively high, lower ratios are generally preferred due to cost considerations. It is sometimes preferable to use an ester of 2,5-dianilino-6,13-dihydroterephthalic acid (preferably, a C 1 -C 6 alkyl ester) or a derivative thereof as the starting material in the ring closure reaction, after of which the resulting dihydroquinacridone must be oxidized and collected. The present invention is also applicable to this variant of quinacridone synthesis. It is, of course, possible to use 2, 5-dianilino-6,13-dihydroterephthalic acid ester mixtures and / or derivatives thereof to obtain solid quinacridone solutions. A critical feature of the invention is the presence of a pigment other than a quinacridone (ie, a "non-quinacridonic pigment"), preferably a phthalocyanine of copper, perylene or dioxazine, during the ring closure reaction. As used herein, the term "non-quinacridonic pigment" refers to both unsubstituted pigments other than quinacridones and substituted derivatives thereof. Suitable non-quinacridonic pigments, although typically highly colored, do not necessarily need to exhibit good pigment properties. That is to say, that suitable non-quinacridonic pigments would not necessarily have a practical utility as pigments by themselves. For example, a relatively weak pigment or pigment derivative could still be suitable for use according to the invention. A crude pigment that does not have good pigment properties just because it has not yet been conditioned could also be suitable for use according to the invention. (Conditioned non-quinacridonic pigments can also be used, of course). Particularly preferred non-quinacridonic pigments will exhibit molar absorptions of approximately the same order of magnitude as those of the quinacridone pigments with which they are employed. Suitable non-quinacridonic pigments include compounds having the following formula (I): Q (A-Y) "(I) wherein Q represents a non-quinacridonic pi? Iment moiety; A represents bridge-forming groups -O-, -S-, -NRa- (where Ra is hydrogen, C1-C12 alkyl, C2-C2 alkenyl, cycloalkyl C5-C7, C6-C6o aryl or C7-C6 aralkyl), -S02-, -CO-, -Alq- (where -Alq- is C? -C8 alkylene, substituted C? -C8 alkylene, C5 cycloalkylene) -C7 or substituted C5-C7 cycloalkylene) or -Ar- (where -Ar- is C6-C? 0 arylene or C6-C? Substituted arylene), chemically reasonable combinations of said bridge forming groups or a direct bond between Q and Y (preferably, -S02-NH-Alk-, -CO-NH-Alk- or direct linkages); Y represents hydrogen, C1-C12 alkyl, C2-C2 alkenyl, C5-C7 cycloalkyl, C5-C7 cycloalkenyl, C6-C6 aryl, heteroaryl of five or six ring atoms (where at least one such ring is N, O, S or a combination thereof and which are optionally fused to one or more additional aromatic rings), C7-C16 aralkyl, 0Rb (where Rb is hydrogen, metal or C1-C-12 alkyl), - NRcRd (where Rc and Rd are independently hydrogen, C? -C? 2 alkyl, C2-C? 2 alkenyl, C5-C7 cycloalkyl, C6-C? Aryl or C7-C? 6 aralkyl, or Rc and R together are C-C6 alkylene forming a heterocyclic group or are aliphatic or aromatic dicarbonyl groups forming an imide and where Rc and Rd may optionally further contain heteroatoms such as N, 0 or S and, optionally, they may further be substituted with C alquilo-alkyl C 2, C 2 alkoxy, C 2 -C 2 alkenyl, C 5 -C 7 cycloalkyl, C 5 -C 7 cycloalkenyl, C 5 -C 7 cycloalkoxy, C 6 -C 0 aryl, C 6 -C 0 aryloxy, C 7 aralkyl -Cie, aralkoxy C7-C6, -OH, halogen, -CN, carboxyl, -CO-NRcRd or -S02-NRcRd), or halogen, and n is from about 0.01 to about 4. The fractional values for n indicate that the Pigment derivatives can be used as mixtures of compounds having varying degrees of substitution, including the same unsubstituted pigment (ie, QH). When more than one group -A-Y is present, the various groups A and Y may, of course, be the same or different from each other. The remaining pigment Q can be derived essentially from any kind of organic pigments other than quinacridone, including phthalocyanines, dioxazines (ie triphenyloxazines), perylenes (particularly, the diimides and dianhydrides of 3, 4, 9, 10-tetracarboxylic acid) ), 1,4-diketopyrrolopyrroles, anthrapyrimidines, antantrones, flavantrones, indatrones, isoindolines, isoindolinones, perinones, pyrantrones, thioindigos, 4,4'-diamino-1,1'-dian-traquinonyl or azo compounds. Preferred non-quinacri-donic pigments are phthalocyanines, perylenes and dioxazines. The remaining non-quinacridonic pigment itself may contain one or more substituents other than the -AY groups, including, for example, halogen (preferably, chloro), C?-C6 alkyl (preferably, methyl) and C?-C6 alkoxy. (preferably methoxy). Particularly preferred non-quinacridonic pigments are, however, copper phthalocyanines or perylenes having one or more -A-Y groups, but not other substituents, and dioxazines in which other substituents may be present. Such pigment derivatives are described, for example, in US Pat. 4,310,359 and in British Patent 784,843. As used herein, the term "C? -C? 2 alkyl" refers to straight or branched chain aliphatic hydrocarbon groups having from 1 to 12 carbon atoms. Examples of C 1 -C 12 alkyl are methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl and their isomeric forms. The term "C 1 -C 2 alkoxy" refers to straight or branched chain alkyloxy groups > which have from 1 to 12 carbon atoms. Examples of C 1 -C 2 alkoxy methoxy, ethoxy, propoxy, butoxy, pentyloxy, hexyloxy, heptyloxy, octyloxy, nonyloxy, decyloxy, undecyloxy, dodecyloxy and its isomeric forms are examples. The term "C2-C2 alkenyl" refers to straight or branched chain unsaturated aliphatic hydrocarbon groups having from 2 to 12 carbon atoms and a carbon-carbon double bond. Examples of C2-C? 2-ethenyl alkenyl are, propenyl, butenyl, pentenyl, hexenyl, heptenyl, octenyl, nonenyl, decenyl, undecenyl, dodecenyl and their isomeric forms. The term "C5-C7 cycloalkyl" refers to cycloaliphatic hydrocarbon groups having from 5 to -7 carbon atoms. Examples of C5-C7 cycloalkyl are cyclopentyl, cyclohexyl and cycloheptyl. The term "C5-C7 cycloalkoxy" refers to cycloalkyloxy groups having from 5 to 7 carbon atoms. Examples of C5-C7 cycloalkoxy are cyclopentyloxy, cyclohexyloxy and cycloheptyloxy. The term "C5-C7 cycloalkenyl" refers to cycloaliphatic hydrocarbon groups having from 5 to 7 carbon atoms and a carbon-carbon double bond. Examples of cycloalgenyl C5-C7 are cyclopentenyl, cyclohexenyl and cycloheptenyl. The term "C 6 -C 0 aryl" refers to phenyl and 1- or 2-naphthyl, as well as to phenyl and naphthyl groups substituted with alkyl, alkoxy, halogen, cyano and nitro as defined herein. The term "C6-C aryloxy" or "refers to phenoxy and 1- or 2-naphthoxy, where the aryl portion may be optionally substituted as described above for" aryl ". The term "heteroaryl" refers to five and six member aromatic groups in which at least one ring atom is N, O, S or a combination thereof and which may be optionally fused to one or more additional aromatic rings. Said heteroaryl groups are attached to group A at a ring carbon atom or, when chemically reasonable, at a ring nitrogen atom. Examples of heteroaryl are pyrrolyl, imidazolyl, pyrazolyl, furanyl, thiophenyl, isothiazolyl, pyridinyl, pyrazinyl, pyrimidinyl, pyridazinyl, and the like. The term "C 7 -C 6 aralkyl" refers to C 1 -C 6 alkyl substituted with C 6 -C 0 aryl, such that the total number of carbon atoms is from 7 to 16. Examples of C 7 aralkyl are C? 6 benzyl, phenethyl and naphthylmethyl. The term "C7-C6 aralkoxy" means C6-C6 alkoxy substituted with C6-C aryl or, such that the total number of carbon atoms is from 7 to 16. An example of C7 aralkoxy C? 6 is benzyloxy. The term "C?-C8 alkylene" refers to straight or branched chain difunctional aliphatic hydrocarbon groups having from 1 to 8 carbon atoms. Examples of C? -C8 alkylene are methylene, ethylene, propylene, butylene, pentylene, hexylene, heptylene and octylene, as well as their isomeric branched forms. The related term "C4-C6 alkylene" refers to straight or branched chain difunctional aliphatic hydrocarbon groups having from 4 to 6 carbon atoms and which are attached to the amide nitrogen atom through two different carbon atoms, to form a heterocyclic ring. Examples of C4-C6 alkylene are butylene (which forms a pyrrolidino substituent), optionally substituted with a methyl group, and pentylene (which forms a piperidino substituent). The term "C5-C7 cycloalkylene" refers to difunctional cycloaliphatic hydrocarbon groups having from 5 to 7 carbon atoms. Examples of C5-C7 cycloalkylene are cyclopentylene, cyclohexylene and cycloheptylene. The term "arylene C6-C? 0" refers to phenylene and disubstituted naphthalene, wherein the aryl portion may be optionally substituted as described above for "aryl". Examples of halogen are fluorine, chlorine, bromine and iodine. Suitable pigment derivatives are pigment sulfonic acids having the following formula (II): Q (S02-ORb) n (II) wherein Q represents a non-quinacridonic pigment residue, Rb is hydrogen or a metal and n is about 0 , 01 to approximately 4. As with the general formula (I), the fractional values for n indicate that the derivatives can be used as mixtures, including mixtures containing the unsubstituted pigment. Suitable metals include alkali metals (such as lithium, sodium and potassium), alkaline earth metals (such as magnesium, calcium and barium), aluminum, transition metals and other heavy metals (such as nickel)., iron, cobalt, manganese, copper and tin). The non-quinacridonic pigment residue Q present in sulfonic acids and salts of formula (II) may be the same as that described above for the compounds of formula (I). Preferred sulfonic acid pigment derivatives are copper phthalocyanines having from about 0.2 to about 2 sulfonic acid gs, more preferably a derivative in which the phthalocyanine ring is otherwise unsubstituted. Particularly preferred pigment derivatives include the pigment sulfonamides having the following formula (III): Q (S02-NH-Alk-NRcRd) n (III) wherein Q represents a non-quinacridonic pigment residue; Alk represents C? -C8 alkylene or C5-C7 cylkylene; R and Rd are independently hydrogen, C? -C? 2 alkyl, C2-C? 2 alkenyl, C5-C7 cylkyl, C6-C? Oo or C7-C? 6 aralkyl or Rc and Rd together are C4-C3 alkylene form a heterocyclic group, and n is from about 0.01 to about R may also contain heteroatoms such as N, O or S. As with the general formula (I), the fractional values for n indicate that the derivatives can be used as mixtures , including mixtures containing the unsubstituted pigment. The non-quinacridonic pigment residue Q present in the sulfonamides of formula (III) may be the same as that described above for the compounds of formula (I). Preferred sulfonamide pigment derivatives are copper phthalocyanines having from about 0.2 to about 2 sulfonamide groups, more preferably derivatives in which the phthalocyanine ring is otherwise unsubstituted. The non-quinacridonic pigments of the invention can be added at any point during or before the ring ure step (a). For example, the non-quinacridonic pigments can be added during the preparation of the intermediates of 2,5-dianilinoterephthalic acid, insofar as the non-quinacridonic pigments are stable under the conditions of the reaction. The reaction mixture of step (a) is heated to a temperature of about 80 ° C to about 145 ° C (preferably 100 ° C to 130 ° C), preferably for about 1 to about 24 hours (more preferably, during 1 to 12 hours).

After completion of the ring closure step (a), the quinacridone pigment is precipitated (i.e., "drowned") in step (b) by adding a strongly acidic melt to a liquid in which the quinacridone pigment is substantially insoluble, preferably water, a water-miscible solvent (such as methanol or other lower aliphatic alcohols) or mixtures thereof. Although it is possible to add the droplet liquid to the acid melt (for example, US Patent 3,265,699), the present invention is preferably carried out by adding the acid melt to the solvent (compare US Patent 4,100,162). ). Suitable droplet liquors include water and / or organic liquids miscible in water, including, for example, lower aliphatic alcohols, such as methanol; ketones and ketoalcohols, such as acetone, methyl ethyl ketone and diacetone alcohol; amides, such as dimethylformamide and dimethylacetamide; ethers, such as tetrahydrofuran and dioxane; alkylene glycols and triols, such as ethylene glycol and glycerol, and other organic liquids of this type known in the art. Other organic liquids may be used, but are generally less preferred. The temperature of the drowning liquid is usually between about 5 ° C and about 65 ° C. In general, lower drowning temperatures give pigments that have smaller particle sizes. However, since the cycle time of the process is also very important (due to the manufacturing cost), a shorter drowning time is preferred. The presence of pigment derivative (a) (iii), which acts in part as an inhibitor of particle growth, allows the temperature of the solvent to rise during the drowning process, thereby shortening the time without excessive growth in size of particle. It is possible, but less preferred, to include a portion of the pigment derivative in the drowning step. The drowned pigment is then isolated in step (c) using methods known in the art, such as filtration, and then dried if desired. Other collection methods known in the art are also suitable, such as centrifugation, microfiltration or even a simple decanting. The crystalline pigment obtained in step (c) can be conditioned in an eventual step (d) using methods known in the art, such as solvent treatment or milling in combination with solvent treatment. The final particle size of the pigment can be controlled by varying the post-treatment method. For example, the pigments can be made to be more transparent by reducing the particle size or more opaque by increasing the particle size. Suitable grinding methods include dry grinding methods, such as sand grinding, ball milling and similar, with or without additives, or wet milling methods, such as kneading with salt, grinding with beads and the like in water or organic solvents, with or without additives. It is possible, although generally less preferred, to include a portion of the non-quinacridonic pigment (preferably less than about 50% of the total amount of non-quinacridonic pigment) in the conditioning step (d). The dyeing strength and transparency of the pigment may also be affected by the solvent treatment carried out by heating a pigment dispersion, often in the presence of additives, in a suitable solvent. Suitable solvents include organic solvents, such as alcohols, esters, ketones and aliphatic and aromatic hydrocarbons and their derivatives and inorganic solvents, such as water. Suitable additives include compositions that decrease or prevent flocculation, increase the stability of the pigment dispersion and reduce the viscosity of the coating, such as polymeric dispersants (or surfactants). For example, US Pat. 4,455,173, 4,758,665, 4,844,742, 4,895,948 and 4,895,949. During or after the conditioning step it is often desirable to use various other eventual components that provide better properties. Examples of such optional components include fatty acids having at least 12 carbon atoms, such as stearic acid or behenic acid, or corresponding amides, esters or salts, such as magnesium stearate, zinc stearate, aluminum stearate or behenate. magnesium; quaternary ammonium compounds, such as tri [(C 1 -C 4) benzyl] ammonium salts; plasticizers, such as epoxidized soybean oil; waxes, such as polyethylene wax; resin acids, such as abietic acid, rosin soap, hydrogenated or dimerized rosin; C 2 -C 8 disulfonic paraffin acids; alkylphenols; alcohols, such as stearyl alcohol; amines, such as laurylamine or stearylamine, and aliphatic 1,2-diols, such as dodecane-1,2-diol. Said additives may be incorporated in amounts ranging from about 0.05 to 20% by weight (preferably 1 to 10% by weight), based on the amount of pigment. After having isolated the pigment and, optionally, having conditioned it, the pigment can be mixed (preferably by dry blending) with one or more quinacridone derivatives known in the art. Suitable quinacridone derivatives for step (e) include quinacridone sulfonic acids and sulfonamides analogous to the compounds of formulas (I), (II) and (III) above, except that Q represents a quinacridone residue. Compared to previously known processes, the pigments prepared according to the invention typically exhibit more intense (darker) and brighter dough tones, with better transparency together with brighter and bluer metal shades and bluer dyes, and Sometimes, they exhibit better rheological properties, all of which are highly desirable characteristics of quinacridone pigments, especially when used for automotive applications. Due to its stability against light and its migratory properties, the quinacridone pigments prepared according to the present invention are suitable for many different pigment applications. For example, pigments prepared according to the invention can be used as a colorant (or as one of two or more colorants) for pigmented systems very quickly, such as mixtures with other materials, pigment formulations, paints, printing ink, colored paper or materials macromolecular colored. It can be understood that the term "mixture with other materials" includes, for example, mixtures with inorganic white pigments, such as titanium dioxide (rutile) or cement, or other inorganic pigments. Examples of pigment formulations include pastes washed with organic liquids or pastes and dispersions with water, dispersants and, if appropriate, preservatives. Examples of paints in which the pigments of this invention may be used include, for example, physically or oxidatively drying lacquers, oven enamels, reactive paints, two-component paints, solvent or water-based paints, emulsion paints for coatings. Water proof and tempera paints. Printing inks include those known for use in printing on paper, textiles and tinplate. Macromolecular substances include those of natural origin, such as gum; those obtained by chemical modification, such as acetyl-cellulose, cellulose butyrate or viscose; or those produced synthetically, such as polymers, polyaddition products and polycondensates. Examples of synthetically produced macromolecular substances include plastic materials, such as polyvinyl chloride, polyvinyl acetate and polyvinyl propionate; polyolefin, such as polyethylene and polypropylene; high molecular weight polyamides; polymers and copolymers of acrylates, methacrylates, acrylonitrile, acrylamide, butadiene or styrene; polyurethanes, and polycarbonates. The materials pigmented with the quinacridone pigments of the present invention may have any desired shape. The pigments prepared according to this invention are highly resistant to water, resistant to oils, resistant to acids, resistant to lime, resistant to alkalis, resistant to solvents., quick to overcoat, fast to over spray, fast to sublimation, heat resistant and vulcanisation resistant and still give a very good dyeing performance and are easily dispersible (for example, in plastic materials). The following examples further illustrate the details for the process of this invention. The invention, which is established in the foregoing description, is not limited in its spirit or scope by these examples. Those skilled in the art will readily understand that known variations of the conditions of the following procedures can be used. Unless stated otherwise, all temperatures are degrees Celsius and all percentages are percentages by weight. EXAMPLES The pigments prepared according to the Examples were analyzed by transmission electron microscopy using a Zeiss EM 109 instrument. The data were collected under the following conditions: Acceleration voltage: 80 kV. Increase: 100,000 X, 40,000 X and 1,000 X. The particle size data were obtained by the BET method (ie, the method of St. Brunauer, PH Emmett and E. Teller, J. Amer. Chem. Soc, 60 , 309 (1938) The X-ray diffraction patterns for the pigments prepared according to the invention were obtained using a Siemens D-5000 Spectrometer The data were collected under the following conditions: Power: 50 kV to 40 mA Slots: 1 , 0 mm divergence, 1.0 mm antidispersion, 0.1 mm detector Step size: 0.01 ° Step time: 3 seconds Differences in hue and chromatility were measured using a Spectral Sensor Applied Color System (Hunt Associated Laboratories, Fairfax, Va.) Solvent Based Paints Tests Solvent-based paint assays were carried out using a generic alkyd melamine paint system, pigment dispersions were prepared using a mixture of a 33 Alkyd resin% AROPLAZ (R) 1453-X-50 (Reichhold Chemicals, Inc.), 63% xylene and 4% pigment, which gave a pigment-to-binder ratio of 4:33 and a total solids content of 37%. The pigment-to-binder ratio was reduced 1:10 by addition of 2.3% alkyd resin AROPLAZ (R) 1453-X-50 and 6.5% RESIMENE (R) 717 melamine resin (Monsanto Company ), which gave a total solids content of 40%. Mass tone and transparency measurements were made using films applied at 152 μm and 38 μm wet film thickness, respectively, and exposed at room temperature for 30 minutes and at 121 ° C for 30 minutes. Low-tone dye paints were prepared from the dispersion described above having a pigment-to-binder ratio of 4:33 by adding 31% of a dispersion prepared from 30% alkyd resin AROPLAZt®) 1453-X- 50, 20% xylene, 5% NUOSPERSE. { R | 657 (Hüls America) and 50% pigment Ti02 TI-PURE (R) R-960 (DuPont); 21% alkyd resin AROPLAZ (R) 1453-X-50, and 7% melamine resin RESIMENElR) 717, which gave a pigment-to-binder ratio of 1: 2, a total solids content of 50%. % and a Ti02-a-pigment ratio of 90:10. The color measurements were made using films applied at 76 μm thickness of wet film and exposed at room temperature for 30 minutes and at 121 ° C for 30 minutes. Metal paints were prepared from the dispersion described above having a pigment-to-binder ratio of 4:33 using an aluminum paste (available as 5251 AR from Silberline Manufacturing Co., Inc.), AROPLAZ alkyd resin (R1 1453 -X-50 and melamine resin RESIMENE <R> 717 in amounts that provided a pigment-to-binder ratio of 1: 9, an aluminum-to-pigment ratio of 20:80 and a total solids content of 41% . The color measurements were made using films applied at 76 μm thickness of wet film and exposed at room temperature for 30 minutes and at 121 ° C for 30 minutes.

Water-based paints tests Water-based paints tests were carried out using an aqueous-based coating system / clearcoat in solvents. Aqueous dispersions were prepared using a mixture of 12.4% AROLON acrylic resin (R1 559-G4-70 (Reichhold Chemicals, Inc.), 3.2% SOLSPERSE hyperdispersant (R1 27000 (Zeneca, Inc.), 1.6% 2-amino-2-methyl-1-propanol (Angus Chemical) and 18% pigment, which gave a pigment-to-binder ratio of 18:12 and a total solids content of 30%. % The pigment-to-binder ratio was then reduced to 10:40 with additional acrylic resin AROLON (R) 559-G4-70 (total amount 26%) and 25% melamine / formaldehyde resin CYMELlR | 325 (Cytec Industries), which gave a total solids content of 50% Mass mass and transparency measurements were made using films applied at 76 μm and 38 μm wet film thickness, respectively, and at rest at room temperature for fifteen minutes. minutes and at 100 ° C for five minutes, transparent layers were then applied containing a mixture of 80% alkyd resin AROPLAZ (R) 1453 -X-50 and 20% melamine / formaldehyde resin CYMEL (R) 325 at a total solids level of 57% on the base layer at a wet film thickness of 76 μm, was allowed to stand at room temperature during fifteen minutes and at 121 ° C for fifteen minutes. Low-tone dye paints were prepared from the reduced aqueous dispersion described above which has a pepper-to-binder ratio of 10:40 by adding additional AROLON (R) 559-G4-70 acrylic resin, melamine / formaldehyde CYMELtR) 325 and 35% white dispersion TINT-AYD (R) CW-5003 (Daniel Products Company), which gave a pigment-to-binder ratio of 1: 1.1, a total solids content 55% and a Ti02-a-pigment ratio of 90:10. The color measurements were made using films applied at 38 μm thickness of wet film and allowed to stand at room temperature for fifteen minutes and at 100 ° C for five minutes. Transparent layers were then applied and baked as described above. Metal paints were prepared from the dispersion described above having a pigment-to-binder ratio of 18:12 using a water dispersible aluminum pigment (obtainable as HYDRO PASTE (R) 8726 from Silberline Manufacturing Co., Inc.), acrylic resin AROLON (R) 559-G4-70 and melamine / formaldehyde resin CYMEL (R) 325 in amounts that provided a pigment-to-binder ratio of 1: 2, an aluminum-to-pigment ratio of 20:80 and a total solids content of 43%. Color measurements were made using films applied at 38 μm wet film thickness and baked as described above. Transparent layers were then applied and baked as described above. EXAMPLE 1 Pigment quinacridone according to the invention was prepared with the incorporation of approximately 1% by weight, relative to the quinacridone, of N- [3- (N, N-dimethylaminopropyl)] copper sulfonamide phthalocyanine in the closing reaction of the ring. The pigment resulting from quinacridone was used to prepare a solvent-based paint. To 250 g of polyphosphoric acid (117% phosphoric acid) heated to 90 ° C was added 0.8 g of N- [3- (N, N-dimethylaminopropyl)] copper sulfonamide phthalocyanine, followed by 83.3 g of acid 2, 5-dianilinotereftálico. The mixture was heated at 120-125 ° C for two hours. After the melting was cooled to 90-95 ° C, the acid strength was adjusted to 107% by dropwise addition of phosphoric acid. The resulting melt was stirred for 15 minutes and then poured slowly into 400 g of methanol at 24 ° C. During drowning, the temperature was allowed to rise to 55 ° C, controlling the temperature by external cooling and adjusting the speed of addition of the melt. The suspension was heated to reflux (68-72 ° C) for one hour, was diluted with water and stirred at 60 ° C for 30 minutes. The solid component was collected by filtration and washed with water until acid free. The resulting filter cake was resuspended in water. After adjusting the pH to more than 7, 7.5 g of 50% sodium hydroxide was added and the resulting suspension was heated at 83 ° C for one hour. The suspension was cooled, filtered and washed with water until alkali free and resuspended in water. After adjusting the pH to 9.0-9.5, 2.0 g of a cycloaliphatic carboxylic acid was added. The resulting suspension was heated at about 140-145 ° C for two hours in a closed system (for example, a pressure reactor), cooled, acidified with phosphoric acid and stirred. The solid component was collected by filtration and washed with water. The wet cake can be dried or used as such for specific applications. Here, the wet cake was dried in an oven at 60 ° C to give approximately 65.0 g of quinacridone as a bright violet pigment. An alkyd melamine enamel paint prepared as described above exhibited a more intense dye tone, a bluer dye and a higher metallic blue shade compared to a paint prepared using QUINDO (R1 Violet RV-6911 (from Bayer Corporation) Example 2 Pigment quinacridone according to the invention was prepared with the incorporation of approximately 1% by weight, relative to the quinacridone, of phthalocyanine of N- [3- (N, N-dimethylaminopropyl)] copper sulfonamide in the closure reaction The resulting quinacridone pigment was used to prepare a water-based paint: 300 g of polyphosphoric acid (117% phosphoric acid) heated to 90 ° C were added with 0.68 g of N- [3- (phthalocyanine N, N-dimethylaminopropyl)] copper sulfonamide, followed by 68.2 g of 2,5-dianilinoterephthalic acid The mixture was heated at 120-125 ° C for two hours, after cooling the melt at 90-95 ° C, the strength of the acid was adjusted to 112% m ed by the drip addition of phosphoric acid. The resulting melt was stirred for 15 minutes and then slowly poured into 453 g of methanol at 24 ° C. During drowning, the temperature was allowed to rise to 55 ° C, the temperature being controlled by external cooling and adjustment of the speed of addition of the melt. The suspension was heated at reflux (68-72 ° C) for one hour, diluted with water and stirred at 60 ° C for 30 minutes. The solid component was collected by filtration and washed with water until acid free. The resulting filter cake was resuspended in water. After adjusting the pH to more than 7, 7.5 g of 50% sodium hydroxide was added and the resulting suspension was heated at 90 ° C for one hour. The suspension was cooled, filtered and washed with water until acid free and resuspended in water. After adjusting the pH to 9.0-9.5, 3.2 g of cycloaliphatic carboxylic acid dissolved in alkaline water was added. The resulting suspension was heated at about 140-1 5 ° C for two hours in a closed system, cooled, acidified with phosphoric acid and stirred. The solid component was collected by filtration and washed with water. The wet cake can be dried or used as such for specific applications. Here, the wet cake was dried in an oven at 60 ° C to give approximately 53.0 g of quinacridone as a bright violet pigment. An alkyd malady enamel paint prepared as described above exhibited a much more intense and brighter mass tone, a bluer tint and a greater metallic blue hue and a higher gloss compared to a paint prepared using QUINDO (| Violet RV-6911. A water-based paint prepared as described above exhibited a more intense dough tone, greater blue tonality and chromaticity of the dye, and greater metallic blueness and brightness compared to a paint prepared using QUINDO (R >; Violet RV-6911. Example 3 Pigment quinacridone according to the invention was prepared with the addition of about 2% by weight, relative to the quinacridone, of phthalocyanine of N- [3- (N, N-dimethylaminopropyl)] copper sulfonamide in the closing reaction From the ring. To 250 g of polyphosphoric acid (phosphoric acid 117%) heated to 80-85 ° C was added 1.6 g of N- [3- (N, -dimethylaminopropyl)] copper sulfonamide phthalocyanine. The mixture was stirred for about ten minutes, after which 83.3 g of 2,5-dianilinoterephthalic acid was added at 85-120 ° C. The reaction mixture was then heated at 120-125 ° C for three hours. After the melting was cooled to 95 ° C, the strength of the acid was adjusted to 112% by the dropwise addition of phosphoric acid. The resulting melt was stirred for 30 minutes and then poured slowly into 400 g of methanol at 24 ° C. During drowning, the temperature was allowed to rise to 55 ° C, the temperature being controlled by external cooling and adjustment of the speed of addition of the melt. The suspension was heated at reflux for one hour, diluted with water and stirred at 60 ° C for 30 minutes. The solid component was collected by filtration and washed with water until acid free. The resulting filter cake was resuspended in water. After adjusting the pH to more than 7, 7.5 g of 50% sodium hydroxide was added and the resulting suspension was heated at 90 ° C for one hour. The suspension was cooled, filtered and washed with water until alkali free and resuspended in water. After adjusting the pH to 9.0-9.5, 3.2 g of a cycloaliphatic carboxylic acid was added. The resulting suspension was heated at about 140-145 ° C for two hours in a closed system, cooled, acidified with phosphoric acid and stirred at 70 ° C for one hour. The solid component was collected by filtration and washed with water. The wet cake can be dried or used as such for specific applications. Here, the wet cake was dried in an oven at 60 ° C to give approximately 61 g of quinacridone as a violet pigment. An alkyd melamine enamel paint prepared as described above exhibited a more intense dye tone and a bluer dye compared to a paint prepared using QUINDO (R) Violet RV-6911. Example 4 (comparison) Quinacridone was prepared in the absence of a pigment additive of the invention. To 300 g of polyphosphoric acid (phosphoric acid 117%) heated to 80 ° C was added 68.2 g of 2,5-dianilinoterephthalic acid. The reaction mixture was heated at 120-125 ° C for two hours. After the melting was cooled to 90-95 ° C, the acid strength was adjusted to 112% by dropwise addition of phosphoric acid. The resulting melt was stirred for * 20 minutes and then poured slowly into 453 g of methanol at 24 ° C. During drowning, the temperature was allowed to rise to 55 ° C, the temperature being controlled by external cooling and adjustment of the speed of addition of the melt. The suspension was heated to reflux (68-72 ° C) for one hour, diluted with water and stirred at 60 ° C for 30 minutes. The solid component was collected by filtration and washed with water until acid free. The resulting filter cake was resuspended in water. After adjusting the pH to about 7, 7.5 g of 50% sodium hydroxide was added and the resulting suspension was heated at 90-95 ° C for one hour. The suspension was cooled, filtered and washed with water until alkali-free and then resuspended in water (total 595 g, including water from the filter cake). After adjusting the pH to 9.0-9.5, 3.2 g of a cycloaliphatic carboxylic acid was added. The resulting suspension was heated at about 140-145 ° C for two hours in a closed system, cooled, acidified with phosphoric acid and stirred. The solid component was collected by filtration and washed with water. You can dry the wet cake or use it as is for specific applications. Here, the wet cake was dried in an oven at 60 ° C to give approximately 53 g of quinacridone as a violet pigment. An alkyd melamine enamel paint prepared as described above exhibited a very light dye tone and very yellow metallic dye and paint as compared to a paint prepared using QUINDO (R1 Violet RV-6911.

A water-based paint prepared as described above exhibited a very clear opaque dough tone and yellow metallic paint and dye as compared to a paint prepared using QUINDO (R) Violet RV-6911. Example 5 (comparison) Quinacridone was prepared according to the method described in Example 4 (ie, in the absence of pigment additive of the invention) and then dry mixed with N- [3- (N, N-dimethylaminopropyl) phthalocyanine )] copper sulfonamide. To 300 g of polyphosphoric acid (phosphoric acid 117%) heated to 90 ° C was added 68.2 g of 2,5-dianilinoterephthalic acid. The reaction mixture was heated at 120-125 ° C for two hours. After the melting was cooled to 95 ° C, the strength of the acid was adjusted to 112% by the dropwise addition of phosphoric acid. The resulting melt was stirred for 15 minutes and then slowly poured into 453 g of methanol at 24 ° C. During drowning, the temperature was allowed to rise to 55 ° C, controlling the temperature by external cooling and by adjusting the speed of addition of the melt. The suspension was heated to reflux (68-72 ° C) for one hour, diluted with water and stirred at 60 ° C for 30 minutes. The solid component was collected by filtration and washed with water until acid free. The resulting filter cake was resuspended in water.

After adjusting the pH to more than 7, 7.5 g of 50% sodium hydroxide was added and the resulting suspension was heated at 90 ° C for one hour. The suspension was cooled, filtered and washed with water until alkali free and resuspended in water. After adjusting the pH to more than 9.0-9.5, 3.2 g of a cycloaliphatic carboxylic acid was added. The resulting suspension was heated at about 140-145 ° C for two hours in a closed system (for example, a pressure reactor), cooled, acidified with phosphoric acid and stirred. The solid component was collected by filtration and washed with water. The wet cake was dried in an oven at 60 ° C to obtain approximately 54 g of quinacridone as a violet pigment. The quinacridone thus obtained was mixed with 0.5 g of N- [3- (N, N-dimethylaminopropyl)] copper sulfonamide phthalocyanine to obtain a violet pigment. A water-based paint prepared as described above exhibited a clear dough tone, a yellow dye with reduced chromaticity, and a lower metallic brightness and blue hue compared to paints prepared using the quinacridone of Example 2 according to the invention. EXAMPLE 6 Pigment quinacridone according to the invention was prepared with the incorporation of approximately 1% by weight, relative to the quinacridone, of phthalocyanine of N- [3- (N, N-dimethylaminopropyl)] copper sulfonamide in the closing reaction of the ring and subsequent use of an amine rosin in place of the cycloaliphatic carboxylic acid in the conditioning step. To 300 g of polyphosphoric acid (117% phosphoric acid) heated to 90 ° C was added 0.68 g of N- [3- (N, N-dimethylaminopropyl)] copper sulfonamide phthalocyanine, followed by 68.2 g of acid 2 , 5-dianilinotereftál? Co. The mixture was heated at 120-125 ° C for two hours. After the melting was cooled to 90-95 ° C, the acid strength was adjusted to 112% by the dropwise addition of phosphoric acid. The resulting melt was stirred for 15 minutes and then slowly poured into 453 g of methanol at 24 ° C. During drowning, the temperature was allowed to rise to 55 ° C, the temperature being controlled by external cooling and adjustment of the rate of addition of the melt. The suspension was heated to reflux (68-72 ° C) for one hour, diluted with water and stirred at 60 ° C for 30 minutes. The solid component was collected by filtration and washed with water until acid free. The resulting filter cake was resuspended in water. After adjusting the pH to more than 7, 7.5 g of 50% sodium hydroxide was added and the resulting suspension was heated at 88 ° C for one hour. The suspension was cooled, it was filtered and washed with water until it was alkali free and resuspended in water. The pH was adjusted to 3-4.5 and 3.3 g of an amine derivative of wood rosin dissolved in water was added. The mixture was stirred for 30 minutes, after which the pH was adjusted to 9.0-9.5. The resulting suspension was heated at about 140-145 ° C for two hours in a closed system. The solid component was collected by filtration and washed with water. The wet cake can be dried or used as such for specific applications. Here, the wet cake was dried in an oven at 60 ° C to obtain approximately 54.0 g of quinacridone as a violet pigment. An alkyd melamine enamel paint prepared as described above exhibited a much more intense and brighter mass tone, a bluer tint and a greater metallic blue and luster compared to a paint prepared using QUINDO (R1 Violet RV- 6911. A water-based paint prepared as described above exhibited a more intense and brighter dye tone and a bluer dye compared to a paint prepared using QUINDO (R) Violet RV-6911. EXAMPLE 7 Pigmented quinacridone was prepared according to the invention with the incorporation of approximately 1% by weight, in relation to the quinacridone, of phthalocyanine of N- [3- (N, N-dimethylaminopropyl)] copper sulfonamide in the ring closure reaction and subsequent dry mixing of a phthalimidomethylquinacridone after the conditioning step: To 300 g of polyphosphoric acid (phosphoric acid 117%) heated to 90 ° C was added 0.68 g of phthalocyanine of N- [3- (N, N- dimethylaminopropyl)] copper sulfonamide, followed by 68.2 g of 2,5-dianilinoterephthalic acid. The mixture was heated at 120-125 ° C for two hours. After the melting was cooled to 90-95 ° C, the acid strength was adjusted to 112% by dropwise addition of phosphoric acid. The resulting melt was stirred for 15 minutes and then slowly poured into 453 g of methanol at 24 ° C. During drowning, the temperature was allowed to rise to 55 ° C, controlling the temperature by external cooling and adjusting the speed of addition of the melt. The suspension was heated to reflux (68-72 ° C) for one hour, diluted with water and stirred at 60 ° C for 30 minutes. The solid component was collected by filtration and washed with water until acid free. The resulting filter cake was resuspended in water. After adjusting the pH to more than 7, 7.5 g of 50% sodium hydroxide was added and the resulting suspension was heated at 88 ° C for one hour. The suspension was cooled, filtered and washed with water until alkali free and resuspended in water. After adjusting the pH to 9.0-9.5, 3.2 g of a cycloaliphatic carboxylic acid dissolved in alkaline water was added. The resulting suspension was heated at about 140-145 ° C for two hours in a closed system, cooled, acidified with phosphoric acid and stirred. The solid component was collected by filtration and washed with water. The wet cake was dried in an oven at 60 ° C to obtain approximately 53.0 g of quinacridone as a violet pigment. The quinacridone thus obtained was mixed with 5.3 g of phthalimidomethylquinacridone (prepared according to US Pat. No. 3,275,637) to obtain a violet pigment. An alkyd melamine enamel paint prepared as described above exhibited a much more intense and brighter dye tone, a bluer dye with higher chromaticity and higher metallic blue and luster compared to a paint prepared using QUINDO (R) Violet RV-6911. A water-based paint prepared as described above exhibited a more intense dough tone, a blue tint and higher metallic blueness and brightness, as well as a reduction in viscosity, compared to a paint prepared using QUINDO (R) Violet RV-6911.

Example 8 A pigment solid solution of 2,9-dichloroquinacridone and 2,9-dimethoxyquinacridone (weight ratio of about 25:75) was prepared in the presence of N- [3- (N, N-dimethylaminopropyl)] phthalocyanine copper 5% sulfonamide. To 270 g of polyphosphoric acid (117% phosphoric acid) heated to 85 ° C was added 2.5 g of N- [3- (N, N-dimethylaminopropyl)] copper sulfonamide phthalocyanine, followed by 13.5 g of 2 , 9-dichloroquinacridone. The mixture was stirred at 113 ° C for 30 minutes, after which 40.5 g of 2,5-di (4-methoxyanilino) terephthalic acid was added. The resulting mixture was heated at 113 ° C for five hours. After cooling the melt at 95 ° C, the acid strength was adjusted to 113% by dropwise addition of phosphoric acid. The mixture was slowly poured into 470 g of methanol. The suspension was heated at reflux for two hours, diluted with water and stirred at 60 ° C for 30 minutes. The suspension was re-diluted with water, after which the solid component was collected by filtration and washed with water until acid-free. The resulting filter cake was resuspended in water (320 g total of water), the pH was adjusted to 8.5 with dilute aqueous sodium hydroxide and 320 g of methanol was added. The resulting suspension was then heated at 120 ° C for six hours in a closed system. After the suspension was cooled to 45-50 ° C, 4.8 g of wood rosin (as the sodium salt) was added. After stirring the mixture for 30 minutes, 10.0 g of CaCl2-2H20 (dissolved in water) was added, the suspension was stirred for one hour and the pH was acidified (if necessary) with phosphoric acid. The solid component was collected by filtration and washed with water. The wet cake can be dried or used as such for specific applications. Here, the wet cake was dried in an oven at 60 ° C to obtain approximately 48 g of quinacridone as an intense violet pigment. A water-based paint prepared as described above exhibited a much more intense and brighter mass tone, a much bluer dye, a greater metallic blue hue and a reduced viscosity compared to a paint prepared using QUINDO (R1 Violet RV -7051 (from Bayer Corporation).

Example 9 A pigment solid solution of 2,9-dichloroquinacridone and 2,9-dimethoxyquinacridone (weight ratio of about 25:75) was prepared in the presence of N- [3- (N, N-dimethylaminopropyl)] phthalocyanine copper at 1%. To 270 g of polyphosphoric acid (117% phosphoric acid) heated to 85 ° C were added 0.54 g of N- [3- (N, N-dimethylaminopropyl)] copper phthalocyanine, followed by 13.5 g of 2, 9-dichloroquinacridone. The mixture was stirred at 113 ° C for 30 minutes, after which 40.5 g of 2,5-di (4-methoxyanilino) terephthalic acid was added .. The resulting mixture was heated at 113 ° C for five hours. After the melting was cooled to 95 ° C, the acid strength was adjusted to 113% by dropwise addition of phosphoric acid. The mixture was slowly poured into 470 g of methanol. The suspension was heated at reflux for two hours, diluted with water and stirred at 60 ° C for thirty minutes. The suspension was re-diluted with water, after which the solid component was collected by filtration and washed with water until acid-free. The filter cake was resuspended in water (320 g of total water), the pH was adjusted to 8.5 with dilute aqueous sodium hydroxide and 320 g of methanol was added. The resulting suspension was heated at 120 ° C for six hours in a closed system (for example, a pressure reactor). After the suspension was cooled to 45-50 ° C, 4.8 g of wood rosin (as the sodium salt) was added. After stirring the mixture for 30 minutes, 10.0 g of CaCl2-2H20 (dissolved in water) was added, the suspension was stirred for one hour and the pH was acidified (if necessary) with phosphoric acid. The solid component was collected by filtration and washed with water. The wet cake can be dried or used as such for specific applications. Here, the wet cake was dried in an oven at 60 ° C to obtain approximately 48 g of quinacridone as an intense violet pigment. A water-based paint prepared as described above exhibited a very intense and shiny mass tone which had better viscosity, a much bluer dye and a greater metallic blue hue compared to a paint prepared using QUINDO (R) Violet RV- 7051 (from Bayer Corporation). Example 10 A solid pigmentary solution of unsubstituted 2,9-dichloroquinacridone and quinacridone (weight ratio of about 80:20) was prepared in the presence of copper phthalocyanine 1% sulfonic acid. To 350 g of polyphosphoric acid (phosphoric acid 117%) heated to 85 ° C were added 0.52 g of copper phthalocyanine sulphonic acid, followed by 10 g of 2,5-dianilinoterephthalic acid and 40 g of acid 2.5- di (4-chloroani-lino) terephthalic. The mixture was heated at 120-125 ° C for three hours. After the melting was cooled to 92 ° C, the acid strength was adjusted to 112% by dropwise addition of phosphoric acid. The resulting melt was stirred at 92 ° C for 30 minutes and then slowly poured into 657 g of methanol.

The suspension was heated at reflux for one hour, cooled to 60 ° C, diluted with water, collected by filtration and washed with water until free of acid. The resulting filter cake was resuspended in water (225 g of total water). After adjusting the pH to 7.0-7.7, 225 g of methanol was added. The resulting suspension was heated at about 120 ° C for six hours. The suspension was cooled, filtered and washed with water. The wet cake can be dried or used as such for specific applications. Here, the wet cake was dried in an oven at 60 ° C to obtain approximately 40 g of a solid solution of 2,9-dichloroquinacridone and an unsubstituted quinacridone as a magenta pigment. A water-based paint prepared as described above exhibited a more intense dye tone, a bluer dye and a greater metallic blue hue compared to a paint prepared using QUINDO (R1 Magenta RV-6853 (from Bayer Corporation). 11 Pigment 2,9-dichloroquinacridone according to the invention was prepared with the addition of 1% by weight, relative to the 2,9-dichloroquinacridone, of N, N-diethylaminopropylperylenesulfonamide in the ring closure reaction.

To 300 g of polyphosphoric acid (117% phosphoric acid) heated to 80 ° C was added 0.5 g of N, N-diethylami-nopropylperylenesulfonamide (prepared according to US Pat. No. 4,310,359), followed by 50 g of 2, 5-di (4-chloroanilino) terephthalic acid over a period of 40 minutes, keeping the temperature below 110 ° C by adjusting the speed of addition. The mixture was heated at 113 ° C for 4.5 hours. After the melting was cooled to 92 ° C, the strength of the acid was adjusted to 111% by dropwise addition of phosphoric acid. The resulting melt was slowly poured into 525 g of methanol, keeping the temperature below 64 ° C by external cooling and adjusting the rate of addition of the melt. The suspension was heated at reflux for one hour, cooled to less than 60 ° C, diluted with water, filtered and washed until free of acid. The filter cake was dried to obtain 43.8 g of crude dichloroquina-cridone, which was then ground with salt for three hours using 306 g of micron salt and 54.6 g of a glycol. The salt was extracted using a slightly alkaline aqueous suspension at 65 ° C for one hour. After filtering the suspension, the filter cake was resuspended in slightly acidic water and kept at 65 ° C for one hour. The solid component was collected by filtration and washed with water. The wet cake can be dried or used as such for specific applications. Here, the wet cake was dried in an oven at 60 ° C to obtain approximately 43 g of 2,9-dichloroquinacridone as a magenta pigment. A water-based paint prepared as described above exhibited a very intense and very bright mass tone with better transparency as compared to paint prepared using QUINDO (R | Magenta RV-6843 (from Bayer Corporation) .Example 12 , 9-dichloroquinacridone pigment according to the invention with the addition of 5% by weight, in relation to the 2,9-dichloroquinacridone, of N, N-diethylami-nopropylperylenesulfonamide in the ring closure reaction, 300 g of polyphosphoric acid (phosphoric acid 117%) heated to 80 ° C was added 2.5 g of N, N-diethylami-nopropylperylenesulfonamide, followed by 50 g of 2,5-di (4-chloroanilino) terephthalic acid over a period of 40 minutes, keeping the temperature below 110 ° C by adjusting the rate of addition. The mixture was heated at 113 ° C for 4.5 hours. After cooling the melt at 98 ° C, the strength of the acid was adjusted to 111% by dropwise addition of phosphoric acid. The resulting melt was slowly poured into 525 g of methanol, keeping the temperature below 64 ° C by external cooling and adjusting the rate of addition of the melt. The suspension was heated at reflux for one hour, cooled to less than 60 ° C, diluted with water, filtered and washed until free of acid. The filter cake was dried to obtain 44.1 g of crude dichloroquina-cridone, which was then ground with salt for three hours using 306 g of a micrometer salt and 57.9 g of a glycol. The salt was extracted using a slightly alkaline aqueous suspension at 65 ° C for one hour. After filtering the suspension, the filter cake was resuspended in slightly acidic water and kept at 65 ° C for one hour. The solid component was collected by filtration and washed with water. The wet cake can be dried or used as such for specific applications. Here, the wet cake was dried in an oven at 60 ° C to obtain approximately 43 g of 2,9-dichloroquinacridone as a magenta pigment. A water-based paint prepared as described above exhibited an extremely intense mass tone with better transparency, compared to a paint prepared using QUINDO (R) Magenta RV-6843. EXAMPLE 13 Pigment 2,9-dichloroquinacridone according to the invention was prepared with the addition of 10% by weight, relative to the 2,9-dichloroquinacridone, of N, N-diethyl-aminopropylperylenesulfonamide in the ring closure reaction. To 300 g of polyphosphoric acid (117% phosphoric acid) heated to 80 ° C was added 5 g of N, N-diethylamino-propylperylenesulfonamide, followed by 50 g of 2,5-di (4-chloroanilino) terephthalic acid throughout of a period of 40 minutes, keeping the temperature below 110 ° C by adjusting the rate of addition. The mixture was heated at 113 ° C for 4.5 hours. After cooling the melt at 97 ° C, the acid strength was adjusted to 11 L% by dropwise addition of phosphoric acid. The resulting melt was slowly poured into 525 g of methanol, keeping the temperature below 64 ° C by external cooling and adjusting the rate of addition of the melt. The suspension was heated at reflux for one hour, cooled to less than 60 ° C, diluted with water, filtered and washed until free of acid. The filter cake was dried to obtain 44.1 g of crude dichloroquinacridone, which was then ground with salt for three hours using 306 g of a micrometer salt and 54.9 g of a glycol. The salt was extracted using a slightly alkaline aqueous suspension at 65 ° C for one hour. After filtering the suspension, the filter cake was resuspended in slightly acidic water and kept at 65 ° C for one hour. The solid component was collected by filtration and washed with water. The wet cake can be dried or used as such for specific applications. Here, the wet cake was dried in an oven at 60 ° C to obtain approximately 44 g of 2,9-dichloroquinacridone as a magenta pigment. A water-based paint prepared as described above exhibited an extremely intense mass tone with better transparency, compared to a paint prepared using QUINDO (R) Magenta RV-6843. EXAMPLE 14 Pigmentary 2,9-dimethylquinacridone according to the invention was prepared with the addition of 0.1% by weight, relative to the 2,9-dimethylquinacridone, of phthalocyanine of N- [3- (N, N-dimethylaminopropyl) ] copper sulfonamide in the ring closure reaction. To 300 g of polyphosphoric acid (phosphoric acid 112%) heated to 88 ° C were added 0.07 g of N- [3- (N, N-dimethylaminopropyl)] copper sulfonamide phthalocyanine, followed by 68.2 g of 2, 5-di (4-methylaniline) ) terephthalic over a period of 35 minutes, keeping the temperature below 120 ° C by adjusting the speed of addition. The mixture was heated at 123 ° C for two hours. After cooling the melt at 93 ° C, it was slowly poured into 500 g of methanol, keeping the temperature below 64 ° C by external cooling and adjusting the rate of addition of the melt. The suspension was heated at reflux for one hour, cooled to less than 60 ° C, diluted with water, filtered and washed until free of acid. The resulting filter cake was resuspended in water. After adjusting the pH to more than 7, 5.5 g of 50% sodium hydroxide was added and the resulting uspension was heated at 90 ° C for one hour. The suspension was cooled, filtered and washed with water until free of alkali and then re-suspended in water. After adjusting the pH to 9.5, the suspension was heated at 143 ° C for two hours in a closed system (for example, a pressure reactor) and cooled to 40 ° C. After acidifying the suspension to a pH of 3.3, an emulsion of 2.2 g of an anionic surfactant, 30 g of a petroleum distillate and 80 g of water was added and the suspension was stirred for three hours. The solid component was collected by filtration and washed with water. The wet cake was dried in an oven at 60 ° C to give approximately 53 g of 2,9-dimethylquinacridone as a magenta pigment. A water-based paint prepared as described above exhibited a more intense and brighter shade of maa compared to QUINDO (R) Magenta RV-6832 (from Bayer Corporation). EXAMPLE 15 Pigmentless quinacridone according to the invention was prepared with incorporation of approximately 1% by weight, relative to the quinacridone, of copper phthalocyanine in the ring closure reaction. To 300 g of polyphosphoric acid (117% phosphoric acid) heated to 90 ° C was added 0.7 g of copper phthalocyanine, followed by 68.2 g of 2,5-dianilinoterephthalic acid. The mixture was heated at 120-125 ° C for two hours. After cooling the melt at 95 ° C, the strength of the acid was adjusted to 112% by the dropwise addition of phosphoric acid. The resulting fusion was stirred for 15 minutes and then slowly poured into 453 g of methanol at 24 ° C. During drowning, the temperature was allowed to rise to 55 ° C, the temperature being controlled by external cooling and adjustment of the rate of addition of the melt. The suspension was heated to reflux (68-72 ° C) for one hour, diluted with water and stirred at 60 ° C for 30 minutes. The solid component was collected by filtration and washed with water until acid-free. The resulting filter cake was resuspended in water. After adjusting the pH to more than 7, 7.5 g of 50% sodium hydroxide was added and the resulting suspension was heated at 90 ° C for one hour. The suspension was cooled, filtered and washed with water until free of alkali and then re-suspended in water. After adjusting the pH to more than 8.5, 3.2 g of cycloaliphatic carboxylic acid was added. The resulting suspension was heated to about 140-145 ° C for two hours in a closed system, cooled, acidified with phosphoric acid and stirred. The solid component was collected by filtration and washed with water. The wet cake can be dried or used as such for specific applications. Here, the wet cake was dried in an oven at 60 ° C to obtain approximately 54.0 g of quinacridone as a bright violet pigment. A water-based paint prepared as described above exhibited a more intense dough tone, a blue tint and a higher metallic blueness and brightness compared to a paint prepared using QUINDO (R) Violet RV-6911. Example 16 (comparison) Quinacridone was prepared in the absence of a pigment additive exactly as described in Comparative Example 5, except that the quinacridone was dry mixed with 1% copper phthalocyanine instead of N-phthalocyanine. 3- (N, N-dimethylaminopropyl)] copper sulfonamide. The untreated quinacridone (54 g) was mixed with 0.5 g of copper phthalocyanine to obtain a violet pigment.

A water-based paint prepared as described above exhibited a light mass tone, lower chromaticity and lower metallic gloss compared to paints prepared using the pigmentary quinacridone prepared according to Example 15 of the invention. Example 17 Pigment quinacridone according to the invention was prepared with approximately 0.25% incorporation, in relation to the quinacridone, of Carbazole Violet (a dioxazine pigment also known as Pigment Violet 23) in the ring closure reaction. To 240 g of polyphosphoric acid (phosphoric acid 116%) heated to 85 ° C was added 0.15 g of Carbazole Violet, followed by 60 g of 2,5-dianilinoterephthalic acid. The mixture was heated at 120-125 ° C for two hours. After the melting was cooled to 95 ° C, the strength of the acid was adjusted to 110% by the dropwise addition of phosphoric acid. The resulting melt was stirred for 15 minutes and then poured slowly into 400 g of methanol at 24 ° C. During drowning, the temperature was allowed to rise to 60 ° C, controlling the temperature by external cooling and adjusting the speed of addition of the melt. The suspension was heated to reflux (68-72 ° C) for one hour, diluted with water and stirred at 60 ° C for 30 minutes. The solid component was collected by filtration and washed with water until acid free. The resulting filter cake was resuspended in water. After adjusting the pH to more than 7, 7.5 g of 50% sodium hydroxide was added and the resulting suspension was heated at 90 ° C for two hours. The suspension was cooled, filtered and washed with water until free of alkali and then re-suspended in water. After adjusting the pH to more than 9.0-9.5, 3.2 g of a cycloaliphatic carboxylic acid was added. The resulting suspension was heated at about 140-145 ° C for four hours in a closed system, cooled to less than 45 ° C, acidified with phosphoric acid and stirred. The solid component was collected by filtration and washed with water. The wet cake can be dried or used as such for specific applications. Here, the wet cake was dried in an oven at 60 ° C to give approximately 50 g of quinacridone as a violet pigment. A water-based paint prepared as described above exhibited an intense and transparent mass tone, higher chromaticity in the subtone and higher metallic brightness compared to QUINDOtR) Violet RV-6911. Example 18 Pigment quinacridone was prepared exactly as described in Example 17 of the invention, except that 0.5% by weight, relative to the quinacridone, of Carbazole Violet was used in the ring closure reaction. Quinacridone (50 g) was obtained as a violet pigment. A water-based paint prepared as described above exhibited an intense and transparent mass tone, a greater chromaticity in the subtone and higher metallic brightness compared to QUINDO (R) Violet RV-6911. Example 19 (comparison) Quinacridone was prepared exactly as described in Example a 18, except that Carbazole Violet was omitted from the ring closure reaction, but was instead added by dry mixing after chemical synthesis of the quinacridone. The untreated quinacridone (50 g) was mixed with 0.5 g of Carbazole Violet to give a violet pigment. An erasure test was used to evaluate the color and appearance of the pigments of Examples 18 and 19. The dispersions were prepared in a Hoover Model M4 Automatic Mixer (Hoover Color Corporation, Hi assee, Virginia) equipped with glass plates. and a weight of 50 Ib (approximately 22.5 kg). For the dispersion of the dough tone, 200 mg of dry pigment was added to 240 mg of crude flaxseed oil (distributed by United Specialties of America, Orlando, Florida) and the mixture was placed in the bottom plate of the mixer. After putting the upper plate in contact with the lower plate, the bottom plate was allowed to rotate 50 revolutions. After separating the plates, the paste was removed from the upper plate with a spatula and added to the bottom plate. This dispersion procedure was repeated three times more. The resulting slurry was diluted with 480 mg of crude linseed oil and the dispersing process was repeated in the mixer twice. A small amount of the resulting bulk tone dissection was placed on a slide and evaluated in comparison with a comparative dispersion prepared by the same mixer dispersion process. The erasure test also included a subtone (dye) evaluation using 100 mg of the mass tone dispersion (final) and 2.0 g of Zinc Oxide Bleach White W-3689 (Superior Printing Inks, New York, NY). This mixing procedure was carried out using a spatula. The subtone was also compared to the comparative subtone dispersion. Based on the erasure test, the pigment of Comparative Example 19 exhibited a lighter mass tone and lower chromaticity in the subtone as compared to the pigment of Example 18 of the invention.

Claims

CLAIMS 1. A process for the preparation of quinacridone pigments consisting of: (a) heating, at a temperature of 80 ° C to 145 ° C, a reaction mixture consisting of: (i) 2,5-dianilinoterephthalic acid, a 2,5-dianilino-6,13-dihydroterephthalic acid ester, a derivative of 2,5-dianilinoterephthalic acid or a 2,5-dianilino-6,13-dihydroterephthalic acid ester having one or more substituents in at least one aniline ring or a mixture of these; (ii) 3 to 15 parts by weight, by component (a) (i), of a dehydrating agent, and (iii) 0.1 to 15 percent by weight, based on component (a) ( i), of one or more non-quinacridonic pigments; with the proviso that, if the component (a) (i) is an ester of 2,5-dianilino-6, 13-dihydroterephthalic acid or a derivative thereof, the reaction step (a) additionally comprises in one step of oxidation; (b) drowning the reaction mixture of step (a) by adding said reaction mixture to 3 to 15 parts by weight, per part of component (a) (i), of a liquid in which the quidine cridone pigment is substantially insoluble; (c) isolating the quinacridone pigment; (d) optionally, conditioning the quinacridone pigment, and (e) optionally mixing the quinacridone pigment with one or more quinacridone derivatives.
2. A process according to claim 1, wherein component (a) (i) is selected from the group consisting of 2,5-dianilin.-terephthalic acid, 2,5-di (4-methylanilino) terephthalic acid, 2-acid, 5-di (4-methoxyanilinyl) terephthalic acid, 2,5-di (4-chloroanilino) terephthalic acid and mixtures thereof.
3. A process according to Claim 1, wherein the reaction mixture is heated in step (a) at a temperature of 100 ° C to 130 ° C.
4. A process according to Claim 1, wherein the dehydrating agent (a) (ii) is polyphosphoric acid.
5. A process according to Claim 4, wherein from 3 to 10 parts by weight, based on component (a) (i), of polyphosphoric acid are used.
6. A process according to Claim 1, wherein the pigment (a) (iii) is a non-quinacridonic pigment having the formula: Q (A-Y) n, wherein: Q represents a non-quinacridic pigment moiety; A represents a bridging group -0-, -S-, -NRa-, -S02-, -CO-, -Alq- or -A: -, a chemically reasonable combination of said bridging groups or a direct link between Q and Y; Y represents hydrogen, C 1 -C 2 alkyl, C 2 -C 12 alkenyl, C 5 -C 7 cycloalkyl, C 5 -C 7 cycloalkenyl, C 6 -C 6 aryl, heteroaryl having five or six ring atoms wherein at least one such ring atoms is N, 0, S or a combination thereof, C7-C6 aralkyl, 0Rb or -NRcRd, or halogen; -Alq- is C? -C8 alkylene, substituted C? -C8 alkylene, C5-C7 cycloalkylene or substituted C5-C7 cycloalkylene; -Ar- is C 6 -C 0 arylene or C 6 -C 0 arylene substituted; Ra is hydrogen, C 1 -C 12 alkyl, C 2 -C 2 alkenyl, C 5 -C 7 cycloalkyl, C 6 -C 0 aryl, or C 7 -C 6 aralkyl; Rb is hydrogen, metal or C? -C12 alkyl; Rc and Rd are independently hydrogen, C x C 12 alkyl, C 2 -C 2 alkenyl, C 5 -C 7 cycloalkyl, C 6 -C 10 aryl or C 7 -C 6 aralkyl, or R c and R d together are C 4 -C 6 alkylene or are dicarbonyl groups aliphatics or aromatics and where Rc and Rd may optionally also contain heteroatoms such as N, 0 or S and, optionally, they may also be substituted with C 1 -C 12 alkyl, C 1 -C 12 alkoxy, C 2 -C 12 alkenyl, C 5 -C 7 cycloalkyl , C5-C7 cycloalkenyl, C5-C7 cycloalkoxy, C6-C10 aryl, C6-C10 aryloxy, C7-C16 aralkyl, C7-C16 aralkoxy, -OH, halogen, -CN, carboxyl, -C0-NRcRd O -S02-NRcRd , and n eß from 0.01 to 4.
7. A process according to Claim 1, wherein the non-quinacridonic pigment (a) (iii) is a phthalocyanine, dioxazine, perylene, 1,4-diketopyrrolopyrrole, anthrapyrimidine, antantron, flavantrone, indantrone, isoindoline, isoindolinone, perinone, pyrantrone, thioindigo, 4,4'-diamino-l, 1-diantraquinonyl or an azo pigment or a derivative thereof having a or more halogen substituents, Cx-Ce alkyl or C? -C6 alkoxy.
8. A process according to Claim 1, wherein the non-quinacridonic pigment (a) (iii) is a phthalocyanine pigment of copper, perylene or dioxazine or a derivative thereof substituted with one or more halogen, Cx-Ce alkyl or C-alkoxy. ? -C6.
9. A process according to Claim 1, wherein the pigment (a) (iii) is a non-quinacridonic pigment having the formula: Q (S02-OR) n, where: Q represents a non-quinacridic pigment residue, R is hydrogen or a metal and n is from 0.01 to 4.
10. A process according to Claim 1, wherein the pigment (a) (iii) is a phthalocyanine copper derivative of the formula: Q (S02-OR) n, where: Q represents copper phthalocyanine or copper phthalocyanine substituted with one or more halogen, C? -C6 alkyl or C? -C6 alkoxy; R is hydrogen or a metal, and n is from 0.2 to 1.
11. A process according to Claim 1, wherein the pigment (a) (iii) is a non-quinacridonic pigment of the formula: Q (S02-NH-Alki- NRcRd) n, where: Q represents a non-quinacridic pigment residue; Alk represents C 1 -C 8 alkylene or C 5 -C 7 cycloalkylene; Rc and Rd are independently hydrogen, C 1 -C 12 alkyl, C 2 -C 12 alkenyl, C 5 -C 7 cycloalkyl, C 6 -C 10 aryl or C 7 -C 16 aralkyl, or Rc and Rd together are C 4 -C 6 alkylene, and n is 0, 01 to 4.
12. A process according to Claim 1, wherein the pigment (a) (iii) is a phthalocyanine copper or perylene derivative having the formula: Q (S02-NH-A1q-NRcRd) n, where: Q represents a phthalocyanine residue of copper or perylene; Alk represents C? -C8 alkylene; Rc and Rd are independently hydrogen, C 1 -C 12 alkyl, C 2 -C 12 alkenyl, C 5 -C 7 cycloalkyl, C 6 -C 10 aryl or C 7 -C 6 aralkyl, or Rc and Rd together are C 4 -C 6 alkylene, and n is 0, 2 to 1.
13. A process according to Claim 1, wherein the reaction mixture of step (a) is drowned by adding said reaction mixture to water, a lower aliphatic alcohol or a mixture thereof.
14. A process according to claim 1, wherein the reaction mixture of step (a) is quenched by adding said reaction mixture to methanol.
15. A quinacridone pigment prepared by the process according to claim 1. SUMMARY OF THE DESCRIPTION This invention relates to a process for the preparation of quinacridone pigments (a) by heating, at a temperature of about 80 ° C to about 145 ° C, a reaction mixture containing (i) 2, 5-dianilinoterephthalic acid, an ester of 2,5-dianilino-6,13-dihydroterephthalic acid and / or a derivative thereof; (ii) about 3 to about 15 parts by weight, per part of component (a) (i), of a dehydrating agent, and (iii) about 0.1 to about 15 weight percent, based on the component (a) (i), of one or more non-quinacridonic pigments, with the proviso that, if the component (a) (i) is an ester of 2,5-dianyl-6,6-dihydroterephthalic acid or a derived therefrom, the reaction step (a) additionally consists of an oxidation step; (b) drowning the reaction mixture of step (a) by adding said reaction mixture to about 3 to about 15 parts by weight, per part of component (a) (i), of a liquid in which the pigment of quinacridone is substantially insoluble; (c) isolating the quinacridone pigment; (d) optionally conditioning the quinacridone pigment, and (e) optionally mixing the resulting pigment with one or more quinacridone derivatives.