MXPA97008779A - Incorporation of quinacridone durantela additives preparation of quinacrid - Google Patents

Abstract

This invention relates to a process for the preparation of quinacridone pigments (a) by heating a reaction mixture consisting of (i) a 2,5-dianilinoterephthalic acid, a 2,5-dianilino-6,13-dihydroterephthalic acid or an acid 2, 5-dianilino-3,6-dioxo-1,4-cyclohexadiene-1,4-dic arboxylic acid (ii) about 0.1 to about 15 weight percent, based on component (a) (i) , of one or more derivatives containing sulfonyl of 2,5-dianilinoterephthalic acid, 2,5-dianilino-6,13-dihydroterephthalic acid and / or 2,5-dianilino-3,6-dioxo-1,4-cyclohexadiene- 1,4-dic arboxylic, and (iii) about 3 to about 20 parts by weight, by component (a) (i), of a dehydrating agent (a) (i), of a dehydrating agent, with the proviso that if any of the components (a) (i) or (a) (ii) is a 2,5-dianilino-6,13-dihydroterephthalic acid or derivative thereof, the reaction step in an oxidation step; me The reaction mixture of step (a) with a liquid in which quinacridone pigment is substantially insoluble, and isolating the quinacrid pigment

Description

INCORPORATION OF QUINACRIDONE ADDITIVES DURING THE PREPARATION OF QUINACRIDONE BACKGROUND OF THE INVENTION This invention relates to a process for the preparation of quinacridone pigments having a reduced particle size, better color properties, better rheological properties and lower manufacturing costs. The inclusion of certain derivatives containing 2, 5-dianilino-terephthalic acid sulfonyl during the synthesis of quinacridone provides quinacridone pigments that have more intense and bright mass tones and better transparency and rheological properties, as well as brighter, more metallic dyes blue and more blue. Moreover, since a reduction in the viscosity of the melt allows higher loads of raw materials during ring closure, the manufacturing costs are, in general, reduced. Processes 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 to achieve pigment quality. A preferred method for preparing quinacridones involves the thermal induction of the ring closure of the 2,5-dianilinoterephthalic acid precursors, as well as known aniline-substituted derivatives thereof, in the presence of polyphosphoric acid. For example, US Pat. 3,257,405. After completion of the ring closure, the melt is drowned by pouring it into a liquid in which the quinacridone is substantially insoluble, usually water and / or an alcohol. The resulting crystalline pigment is then still conditioned by solvent treatment or milling in combination with solvent treatment. The quinacridonaquinones can be prepared in a similar manner, except for the use of 2, 5-dianilino-3,6-dioxo-1,4-cyclohexa-diene-1,4-dicarboxylic acid derivatives as starting materials in the reaction of the ring closure. For example, S.S. Labana and L.L. Labana, "Quinacridones", in Chemical Review, 67, 1-18 (1967) and W. Herbst and K. Hunger, Industrial Organic Pigments (New York: VCH Publishers, Inc., 1993), pages 452-453. It is also possible to use 2,5-dianilino-6,13-dihydroterephthalic acid derivatives as starting materials in the reaction of the ring closure. The resulting dihydro-quinacridones must, however, be oxidized to the corresponding quinacridones before conditioning. For example, S.S. Labana and L.L. Labana, "Quinacri-dones", in Chemical Review, 67, 1-18 (1967) and W. Herbst and K. Hunger, Industrial Organic Pigments (New YorK: VCH Publishers, Inc., 1993), pages 448-449. The final particle size of the quinacridone pigments can be controlled by the methods employed 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 drowning 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. Frequently reference is made to the post-treatment stages that manipulate the particle size of the raw pigments as conditioning methods. Several suitable methods of conditioning are known. However, the most commonly used methods include grinding dried crude quinacridones, usually in the presence of undesirably large of an inorganic salt that must be removed afterwards. The pigment quinacridones can also be obtained by premixing the dried raw material first and then treating the ground material with an organic liquid. Other methods include a premixing step followed by another milling step using water and small amounts of an organic liquid. Pigment quinacridones can also be obtained by heat treatment of the raw filter press in large amounts of solvent. Various additives have been added during the grinding stages, treatment with solvents or post-treatment with solvents to further improve the properties of the pigment. For example, U.S. Pat. No. 5,084,100 describes a method in which a crude quinacridone is milled in the presence of aluminum sulfate and esters of alkanedicarboxylic acids. U.S. Pat. No. 4,455,173 discloses a process in which crude quinacridone pigments are pulped with acid or ground with balls and then milled in an organic liquid, preferably in the presence of a particle size growth inhibitor of 2-phthalimidomethylquinacridone. . Various pigment derivatives have also been described for treating pigments, including quinacridone pigments, in US Pat. 3,386,843, 4,310,359 and 5,472,494. The addition of certain quinacridone derivatives to the ring closure stage has also been described. For example, U.S. Pat. 5,368,641 describes the use of various quinacridone derivatives in the manufacture of 2, 9-dimethylquinacridone and European Patent Application 643,110 discloses the use of quinacridone derivatives during the oxidation of dihydroquinacridone (prepared from 2,5-dianilino acid -6, 13-dihydrote-reftálico) to quinacridona. See also US Patent Applications. Serial No. 08 / 639,598 and 08 / 639,599. The method of the present invention, contrary to said known methods, does not introduce said pigment additives into the ring closure stage, but instead incorporates precursors of certain quinacridone additives containing sulfonyl during ring closure. . These precursors are converted into quinacridone additives containing sulfonyl at the same time that the quinacridone pigment itself is formed. The process of the present invention provides quinacridone pigments having desirable color properties, often at lower manufacturing costs. The present invention provides quinacridones with a smaller particle size that have better rheological properties and transparency by the addition of certain sulfonyl-containing derivatives of 2,5-dianilinoterephthalic acid to the ring closure step of the quinacridone synthesis. The addition of said derivatives during the ring closure stage results in a more intense and brighter pigment that has better transparency and rheological properties, as well as brighter, metallic bluer and bluer dyes. COMPENDIUM OF THE INVENTION The present 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 145 ° 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, 2,5-dianilino-6,13-dihydroterephthalic acid, 2,5-dianilino-3 acid, 6-dioxo-l, 4-cyclohexadiene-1-dicarboxylic acid, or a derivative thereof having one or more substituents on at least one anilino ring; a salt or ester of said acid or derivative thereof, or a mixture thereof; (ii) about 0.1 to about 15 percent by weight (preferably 0.1 to 10 percent by weight), based on component (a) (i), of a derivative containing 2, 5-dianilinoterephthalic acid sulfonyl which has the formula (I) a derivative containing sulfonyl of 2,5-dianilino-6,13-dihydroterephthalic acid having the formula (II) a derivative containing 2, 5-dianilino-3,6-dioxo-l, 4-cyclohexadiene-1, -dicarboxylic acid sulfonyl having the formula (III) or a mixture thereof, wherein X1 and X2 are independently ORa or NRbRc; Y1 and Y2 are independently hydrogen, halogen, alkyl Cj-Cg or alkoxy C -C • R1 and R2 are independently hydrogen, a metal, an ammonium or alkyl ion C? ~ C12; Ra is hydrogen, a metal, an ammonium ion or Cl-Cl 2 alkyl; Rb is hydrogen, C 1 -C 4 alkyl or substituted C 1 -C 4 alkyl, C 5 -C 7 cycloalkyl or substituted C 5 -C 7 cycloalkyl, C 6 -C 10 aryl, heteroaryl having 5 or 6 ring atoms (in 5 where at least one such ring atom is N, 0, S or a combination thereof and which are optionally fused to one or more additional aromatic rings) or C7-C16 aralkyl; Rc is hydrogen, C ^ C ^ alkyl or substituted alkyl, C5-C7 cycloalkyl or substituted C5-C7 cycloalkyl or C7-C16 aralkyl, or Rb and Rc, together with the nitrogen atom, form A heterocycle having 5 to 7 ring atoms, and m and n are independently 0 to 3, with the proviso that at least one of m or n is not 0 (preferably where Both m and n are 1), and (iii) about 3 to about 20 parts by weight (preferably 3 to 10 parts by weight), by part of component (a) (i), of a dehydrating agent (preferably acidic). polyphosphoric), with the proviso that, if any of the components (a) (i) or (a) (ii) is a 2,5-dianilino-6, 13-dihydroterephthalic acid or derivative thereof, the reaction step (a) additionally consists of 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-blending) the resulting quinacridone pigment with one or more pigment derivatives (preferably quinacridone derivatives). DETAILED DESCRIPTION OF THE INVENTION The quinacridone pigments (by which is meant non-substituted quinacridone, quina-cridone derivatives and solid solutions thereof) are prepared according to the invention primarily by ring closure of precursors of 2,5-dianilinoterephthalic acid , including its known aniline-substituted derivatives, as well as its metal or amine salts or its esters, by heating the precursors of 2,5-dianilinoterephthalic acid in the presence of a dehydrating agent (preferably polyphosphoric acid) and a derivative containing 2,5-dianilinoterephthalic acid sulfonyl according to the invention, or, less preferably, thermally inducing the ring closure in a high boiling point solvent in the presence of a sulfonyl derivative of 2,5-dianilinote-reftalic acid according to invention. The quinacridone-containing reaction mixture is then drowned and the resulting quinacridone pigment is isolated by known methods. The quinacridone pigment is preferably also subjected to further conditioning steps to improve the pigment properties and, if desired, is mixed with various additives. The ring closure step (a) 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, US Pat. 4,758,665 and S.S. Labana and L.L. Labana, "Quinacridones", in Chemical Reviews, 67, 1-18 (1967). Particularly preferred is polyphosphoric acid having a phosphate content equivalent to about 110-120% H3P04. When polyphosphoric acid is used, the weight ratio of polyphosphoric acid to the total amount of terephthalic acid precursors, including the amount of sulfonyl-containing derivatives, is typically from about 3: 1 to about 10: 1 (preferably 4: 1 to 8: 1). The reaction mixture of step (a) is heated to a temperature of from 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 a 12 hours) . The process of the invention can be used to prepare unsubstituted quinacridone or substituted quinacridone derivatives in the ring, depending on whether ring closure is carried out using unsubstituted 2,5-dianilinoterephthalic acid or a derivative thereof having one or more substituents in at least one of the two aniline rings. Although essentially any 2,5-dianilinoterephthalic acid derivative known in the art can be employed, particularly preferred derivatives of 2,5-dianilinoterephthalic acid are those in which both aniline moieties are substituted (typically with the same substituent) in the position for groups such as halogen (preferably chloro), C] -C6 alkyl (preferably methyl) and C6-alkoxy (preferably methoxy). It is also possible to use 2, 5-dianilinoterephthalic acid derivatives in which the aniline residues are substituted in the ortho or meta positions. The corresponding metal or amine salts (preferably alkali metal or alkaline earth salts) or esters (preferably alkyl esters) of each of the above compounds can, of course, be used. Examples of particularly suitable derivatives of 2,5-dianilinoterephthalic acid are 2, 5-di (4-chloroanilino) terephthalic acid, 2,5-di (4-methylanilino) terephthalic acid and 2,5-di (4) 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 said mixtures provides a particularly advantageous method for obtaining solid solutions of quinacridone. Mixtures containing 2,5-dianilinoterephthalic acid and / or a derivative thereof in combination with a fully formed quinacridone pigment (generally in crude form) can also be used. Although less preferred, it is possible to prepare quinacridonaquinones in a similar manner, except for the use of 2,5-dianilino-3,6-dioxo-1,4-cyclohexa-diene-1,4-dicarboxylic acid or a derivative thereof ( including corresponding salts or esters) as a starting material in the ring closure reaction. It is sometimes preferable to use a 2,5-dianilino-6,13-dihydroterephthalic acid (preferably as an alkyl ester or a derivative thereof as a starting material in the ring closure reaction (which may also include the corresponding derivatives containing sulfonyl), after which the resulting dihydroquinacridone must be oxidized by known methods (for example, using aromatic nitro compounds, chloroanil, anthraquinone-2-sulfonic acid or a salt thereof, anthraquinone-2,7-disulfonic acid or a salt of the same, air or other gases containing oxygen, halogens or electrolytic oxidation) to form the corresponding quinacridone, which are collected by known methods, for example, SS Labana and LL Labana, "Quinacridones", in Chemical Review, 67, 1- 18 (1967) (see pages 4-5) and Herbst and K. Hunger, Industrial Organic Pigments (New York: VCH Publishers, Inc., 1993), pages 448- 449. The present invention is also directed also to this variant of the quinacridone synthesis. Is, of course, it is possible to use mixtures of 2, 5-dianilino-6, 13-dihydroterephthalic acids and / or derivatives thereof to obtain solid quinacridone solutions. A critical feature of the invention is the presence of a sulfonyl-containing derivative (a) (ii) during the ring closure reaction, although the sulfonyl-containing derivatives can be added essentially at any point during or before the closure step of ring (a). Suitable sulfonyl-containing 2,5-dianilinoterephthalic acid derivatives can produce highly colored sulfonyl-containing quinacridone products. However, the utility of a precursor containing sulfonyl does not depend on the production of quinacridone products containing sulfonyl, which themselves exhibit good pigment properties. Suitable derivatives containing sulfonyl of 2,5-dianilinoterephthalic acid have the following formula (I) where X1 and X2 can independently be OH (ie, free sulfonic acid groups), 0"cation + (i.e., metal salts or various ammonium ions), 0-alkyl (i.e., alkyl esters of sulfonic acid) or NRbRc ( that is, several sulfonamides wherein each Rb may independently be hydrogen or an optionally substituted alkyl, cycloalkyl, aryl, heteroaryl or aralkyl and each Rc may independently be hydrogen or an optionally substituted alkyl, cycloalkyl or aralkyl or where Rb and Rc, together with the nitrogen atom, can form a heterocycle having from 5 to 7 ring atoms); Y1 and Y2 can independently be hydrogen, halogen, alkyl or alkoxy, and m and n can be from 0 to 3, provided that at least one of mon is not In the preferred embodiments, the groups Y1 and Y2 are identical (both preferably being hydrogen) and all the groups X1 and X2 are identical, as used herein, the term "C? -C12 alkyl" e refers to straight or branched chain aliphatic hydrocarbon groups having from 1 to 12 carbon atoms. Examples of C-L-C ^ alkyl are methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl and the isomeric forms thereof. The C1-Cu alkyl groups may also be substituted, for example, with one or more Cj-Cg alkoxy groups, C-Cg alkylthio or halogen. The term "C ^ Cg alkoxy" refers to straight or branched chain alkyloxy groups having from 1 to 6 carbon atoms. Examples of C2-C6-methoxy, ethoxy, propoxy, butoxy, pentyloxy, hexyloxy alkoxy and the isomeric forms thereof are examples. The term "alkylthio-C6-C6 '" refers to analogous groups in which a sulfur atom replaces the oxygen atom. 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 C5-C7 cycloalkyl groups may also be substituted, for example, with one or more alkylthio alkoxy or halogen groups. The term "C6-C6-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. 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 the nitrogen atom of the sulfonamide at a ring carbon atom. Examples of heteroaryl are pyrrolyl, imidazolyl, pyrazolyl, furanyl, thiophenyl, isothiazolyl, isoxazolyl, pyridinyl, pyrazinyl, pyrimidinyl, pyridazinyl and the like. The term "C7-C16 aralkyl" refers to C ^ Cg alkyl substituted with C6-C10 aryl, such that the total number of carbon atoms is from 7 to 16. Examples of C7-C16 aralkyl are benzyl, phenethyl and naphthylmethyl. The term "heterocycle", as used to describe compounds in which NRbRc is a heterocycle having from 5 to 7 ring atoms, includes groups in which Rb and Rc together are C4-C6 alkylene, alkenylene, alkadienylene or alktrienylene having one or more substituents (such as alkyl, alkoxy or halogen) and the nitrogen atom is always tertiary rather than quaternary. Suitable heterocycles also include groups in which one or more of the ring carbon atoms are substituted with N, 0 or S (the maximum number of ring double bonds being, of course, limited to the number giving chemically reasonable heterocyclic groups) ). Examples of suitable heterocycles include pyrrolidinyl, pyrrolinyl, imidazolidinyl, pyrazolidinyl, pyrazolinyl, piperidinyl, piperazinyl, morpholinyl, and the like. Examples of halogen are fluorine, chlorine, bromine and iodine. Although it is possible to use acid derivatives 2, 5-dianilinoterephthalic containing one or more substituents other than the sulfonyl groups, including, for example, halogen (preferably chloro), C 1 -C 6 alkyl (preferably methyl) and Cj-Cg alkoxy (preferably methoxy), the preferred derivatives of the 2, 5-dianilino-terephthalic acid do not contain substituents other than the sulfonyl groups. Particularly preferred 2, 5-dianilinote-reftalic acid derivatives are the "disulfonyl" compounds of formula (IV) where X1 and X2 are defined as before. Among the preferred sulfonyl-containing derivatives of 2,5-dianilinoterephthalic acid are sulfonic acids (or their salts) having the following formula (V) where Ra is defined as before. The preferred compounds of formula (V) are the free sulfonic acids (ie, where Ra is hydrogen), but it is also possible to use the corresponding metal or ammonium salts. 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), polyvalent metals being used in stoichiometrically appropriate amounts (ie, 1 / k moles of k-valent metal per mole of oxygen).

Suitable ammonium cations include NH / and various derivatives thereof N-alkyl, N-aryl and / or N-aralkyl-substituted. Although the strongly acidic conditions typically employed for ring closure can convert said salts to the corresponding free sulphonic acids, it can, however, be advantageous to add the sulfonyl-containing 2, 5-dianilinoterephthalic acid derivatives in salt form. Particularly preferred sulphonyl-containing 2, 5-dianilinoterephthalic acid derivatives include sulfonamides having the following formula (VI) wherein each Rb is independently hydrogen, alkyl or substituted alkyl, substituted cycloalkyl or cycloalkyl, aryl, heteroaryl or aralkyl and each Rc is independently hydrogen, alkyl or substituted alkyl, substituted cycloalkyl or cycloalkyl, or aralkyl or, somewhat less preferably, where Rb and Rc together with the nitrogen atom form a heterocycle having from 5 to 7 ring atoms. Preferred compounds of formula (VI) are those in which Rb and Rc are both hydrogen or both alkyl or wherein Rb is alkyl, aryl or heteroaryl and Rc is hydrogen. Although it is expected that the use of strongly acidic dehydrating agents (especially polyphosphoric acid) at high temperatures would convert many, if not all, of the sulfonamides of formula (VI) into the corresponding free sulfonic acids, it has surprisingly proved advantageous to use sulfonamides such as those of formula (VI) instead of free acids, salts or esters. Analogous sulphonyl-containing derivatives of 2,5-dianilino-6,13-dihydroterephthalic acid of formula (II) are also suitable, particularly when 2, 5-dianilino-6,13-dihydroterephthalic acids or derivatives thereof are used as pigmentary starting material (a) (i). The preferred derivatives of 2,5-dianilino-6,13-dihydroterephthalic acid the "disulfonyl" compounds of formula (VII) where X1 and X2 are defined as before. Particularly preferred derivatives of 2,5-dianilino-6,13-dihydrote-reftalic acid are those having substituents corresponding to those of the terephthalic derivatives of formulas (V) and (VI). The sulfonyl-containing dihydroquinacridones formed during ring closure can be oxidized to the corresponding sulfonyl-containing quinacridones under the same conditions used to oxidize the dihydroquinacridone intermediates of the main pigment component. The sulfonyl-containing derivatives of 2,5-dianilino-3,6-dioxo-1,4-cyclohexadiene-1,4-dicarboxylic acid having the formula (III) are also suitable, particularly when the acids are used. , 5-dianilino-3,6-dioxo-1,4-cyclohexadiene-1,4-dicarboxylics or their derivatives as pigmentary starting material (a) (i). Preferred derivatives of dioxocyclohexadienodicarboxylic acid are those having substituents corresponding to those of the terephthalic derivatives of formulas (IV), (V) and (VI). Although generally less preferred, it is possible to use any combination of pigment precursors (a) (i) with sulfonyl-containing precursors (a) (ii). For example, a quinacridone pigment can be prepared from 2,5-dianilinoterephthalic acid in the presence of a sulfonyl-containing 2,5-dianilino-6,13-dihydroterephthalic acid, with or without oxidation of the sulfonyl-containing quinacridone component of the product resulting. It is possible to add several various fully formed quinacridone derivatives, particularly sulfonyl-containing quinacridone products prepared from the sulfonyl-containing 2, 5-dianilinoterephthalic acid derivatives used in the invention, to the ring closure stage. However, it is generally cheaper and it takes less time not to use said additives. After completion of the ring closure stage (a), the quinacridone pigment is precipitated (i.e., "drowned") in step (b) by adding the 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 drowning liquid to the acid melt (e.g., 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 drowning liquids 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 can be used, but, in general, they are 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 time of the processing cycle 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, thus shortening the time without excessive growth of the particle size. 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 the 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 more transparent by reducing the particle size or more opaque by increasing the particle size. Suitable milling methods include dry milling methods such as sand milling, ball milling and the like, with or without additives, or wet milling methods such as salt kneading, pearl milling and the like in water or organic solvents. , with or without additives. The dyeing strength and transparency of the pigment may also be affected by a 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, which increase the stability of the pigment dispersion and reduce the viscosity of the coating, such as polymeric dispersants (or surfactants). For example, US Patents 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 optional ingredients that provide better properties. Examples of such optional ingredients 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. of magnesium; quaternary ammonium compounds, such as tri [(alkyl C] _ C4) 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; C12-C18 paraffinisulfonic 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 and, optionally, conditioned the pigment, the pigment can be mixed (preferably by dry mixing) with one or more pigment derivatives known in the art. Suitable pigment derivatives for step (e) include quinacridone derivatives, quinacridone sulfonic acids and quinacridone sulfonamides particularly known and quinacridone derivatives containing other substituents (such as phthalimide-containing substituents or heteroatomatic groups). Particularly preferred quinacridone derivatives correspond to the sulfonyl-containing quinacridone products formed by ring closure of the 2,5-dianilino-terephthalic acid-containing derivatives thereof used in the present invention. The pigments prepared according to the invention typically exhibit intense (dark), bright and transparent mass tones, together with bright dyes, blue and blue metallic, and sometimes exhibit improved rheological properties, all of which are highly desirable characteristics of the pigments. of quinacridone, especially when used for automotive applications. Due to their light stability and migration properties, the quinacridone pigments prepared according to the present invention are suitable for many different pigment applications. For example, the pigments prepared according to the invention can be used as a colorant (or as one of two or more colorants) for very rapidly pigmented systems, such as mixtures with other materials, pigment formulations, paints, printing ink, colored paper or colored macromolecular materials. 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, physical or oxidative drying lacquers, oven enamels, reactive paints, two-component paints, water-based or solvent-based paints, emulsion for waterproof coatings and tempera paints. Printing inks include those known for use in printing on paper, fabrics and tinplate. Macromolecular substances include those of natural origin, such as gum; those obtained by chemical modification, such as acetylcellulose, 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; polyolefins, 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 water resistant, oil resistant, acid resistant, lime resistant, alkali resistant, solvent resistant, overcoat stable, over spray stable, sublimation stable, heat resistant. and resistant to vulcanization and still provide 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 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 in degrees Celsius and all percentages are percentages by weight. EXAMPLES The differences in hue and chromaticity for the pigments prepared according to the Examples were measured using an Applied Color System Spectrum Sensor (Hunt Associated Laboratories, Fairfax, Virginia). Tests with solvent-based paints Tests were carried out with solvent-based paints using a generic alkyd melamine paint system. Pigment dispersions were prepared using a mixture of 33% alkyd resin AROPLAZ (R) 1453-X-50 (Reichhold Chemicals, Inc.), 63% xylene and 4% pigment, which gave a pigment ratio a binder of 4:33 and a total solids content of 37%. The pigment to binder ratio was reduced 1:10 by the addition of 2.3% alkyd resin AROPLAZ (R) 1453-X-50 and 6.5% RESIMENE melamine resin (R | 717 (Monsanto Company), which gave a total solids content of 40% .The mass tone and transparency measurements were made using films applied at a wet film thickness of 152 μm and 38 μm, respectively and flashed at room temperature for 30 minutes and at 121 C for 30 minutes Dye-dye paints were prepared from the dispersion described above with a pigment-to-binder ratio of 4:33 by adding 31% of a dispersion prepared from 30% alkyd resin AROPLAZÍR) 1453- X-50, 20% xylene, 5% NUOSPERSE (R1 657 (Hüls America) and 50% Ti02 pigment TI-PURE (R) R-960 (DuPont), 21% Alkyd resin AROPLAZ (R) 1453-X-50, and 7% RESIMENEÍR melamine resin) 717, which gave a pigment to binder ratio of 1: 2, n total solids content of 50% and a Ti02 to 90:10 binder ratio. Color measurements were made using films applied at a wet film thickness of 76 μm and flashed at room temperature for 30 minutes and at 121 ° C for 30 minutes. Metal paints were prepared from the dispersion described above, which had a pigment-to-binder ratio of 4:33, using an aluminum paste (available as 5251 AR from Silberline Manufacturing Co., Inc.), AROPLAZ (R) alkyd resin 1453-X-50 and RESIMENE melamine resin (R1 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%. were made using films applied at a wet film thickness of 76 μm and flashed at room temperature for 30 minutes and at 121 ° C for 30 minutes Water-based paints tests Water-based paints were performed using a basecoat system supported in water / solvent-borne transparent layer Aqueous dispersions were prepared using a mixture of a, 4% acrylic resin AROLON (R) 559-G4-70 (Reichhold Chemicals, Inc.), 3.2% hyperdispersant SOLSPERSE (R) 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 AROLON acrylic resin (additional RI 559-G4-70 (total amount 26%) and 25% melamine / formaldehyde resin CYMEL (R) 325 (Cytec Industries), which gave a total solids content of 50% The mass and transparency measurements were made using films applied at a wet film thickness of 76 μm and 38 μm, respectively, and which were allowed to stand at room temperature environment for fifteen minutes and at 100 ° C for five minutes, then transparent coats containing a mixture of 80% alkyd resin AROPLAZÍR >were applied; 1453-X-70 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, allowing to stand at room temperature for fifteen minutes and at 121 ° C for fifteen minutes. Low-tone dye paints were prepared from the reduced aqueous dispersions described above with a pigment-to-binder ratio 10:40 by adding additional acrylic resin AROLON (R) 559-G4-70, melamine / formaldehyde resin CYMEL | R) 325 and a 35% white dispersion TINT-AYD (R | C -5003 (Daniel Products Company), which gave a pigment to binder ratio of 1: 1.1, a total solids content of 55% and a Ti02 ratio to pigment of 90:10 Color measurements were made using films applied at a wet film thickness of 38 μm and allowed to stand at room temperature for fifteen minutes and at 100 ° C for five minutes.The transparent layers were then applied and baked as described above Metallic paints were prepared from the dispersion described above with a pigment to binder ratio of 18:12 using a water dispersible aluminum pigment (available 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%. The measurements were made using films applied at a wet film thickness of 38 μm and baked as described above. The transparent layers were then applied and baked as described above. Tests with pigmented plastics The pigment coloration of polyvinyl chloride ("PVC") was evaluated by comparing samples milled cold prepared according to the following procedures. A. Evaluation of the mass tone. For each sample studied, a 50 g portion of PVC was added to a hot two-roll mill (177 ° C) that had a roller contact thickness of 34 mils (about 0.8 mm) and was disintegrated until being uniform. A 0.050 g portion of the test pigment or the comparative pigment was sprayed onto the roller contact line over a period of about ten seconds, after which the disaggregated material was cut and ground in the mill for three hours. minutes The pigmented sheet was removed from the mill and placed in a cold two-roll mill (24 ° C) which had a roller contact line thickness of 17 mils (about 0.4 mm), was then bent and passed through the mill twelve times. The cold-milled sheet was broken again in the hot mill (contact line fixed at 17 mils) until smooth. The resulting sheet was used for the evaluation of the mass tone. B. Evaluation of the dye. The procedure described above for the evaluation of the mass tone was repeated, except for the addition of 1 g of 50% titanium dioxide paste to the PVC, which was then disintegrated until uniform before the addition of the pigment. The differences in hue and chromaticity were then measured. Preparation of Derivatives Containing Sulphonyl of 2,5-Dianilinoterephthalic Acid The sulfonyl-containing derivatives of 2,5-dianilinoterephthalic acid used in the Examples were prepared as follows: 2, 5-di (4-sulfamoilanilino) terephthalic acid To 200 g of methanol was added with stirring 31.2 g (137 mmol) of dimethylsuccinyl succinate, 61.2 g (355 mmol) of p-sulfanilamide (Aldrich Chemical Co., Milwaukee, Wisconsin) and 0.7 g of concentrated sulfuric acid. The reaction mixture was slowly heated to a temperature of 95 to 97 ° C and maintained at that temperature for five hours. After cooling the reaction mixture to 50 ° C, 34.4 g of sodium 3-nitrobenzenesulphonate, 31.8 g of water and 100 g of 45% aqueous potassium hydroxide were added slowly with stirring. The resulting mixture was then slowly heated to 90 ° C and maintained at that temperature for four hours. The reaction mixture was cooled to room temperature and added to 500 ml of water. Concentrated sulfuric acid was added slowly to produce a solid, which was collected by filtration and washed with water. The cake of the wet filter press was dried in an oven to obtain 56.4 g (81.3% of theory) of 2,5-di (sulfamoylanilino) terephthalic acid. The dried product contained only one major component, as determined by inverted phase high pressure liquid chromatography with a Waters 712 WISP system equipped with a Waters Nova C-18 cartridge, using tetrahydrofuran / water as eluent. 2, 5-bis [4- (3, 4-dimethyl-5-isoxazolyl) sulfamoylanyl-no] terephthalic acid To 150 g of methanol was added with stirring 20 g (87.6 mmol) of dimethylsuccinyl succinate, 53.9 g (201.6 mmol) of 4-amino-N- (3,4-dimethyl-5-isoxazolyl) benzenesulfonamide (Aldrich Chemical Co.) and 0.7 g of concentrated sulfuric acid. The reaction mixture was heated slowly to a temperature of 95 to 97 ° C and maintained at that temperature for five hours. After cooling the reaction mixture to 50 ° C, 26 g of sodium 3-nitrobenzenesulfonate, 2 g of water and 75 g of 45% aqueous potassium hydroxide were added slowly with stirring. The resulting mixture was then slowly heated to 90 ° C and maintained at that temperature for four hours. The reaction mixture was cooled to room temperature and added to 500 ml of water. Concentrated sulfuric acid was added slowly to produce a solid, which was collected by filtration and washed with water. The cake of the wet filter press was dried in an oven to obtain 43 g (70.4% of theory) of 2,5-bis [4- (3,4-dimethyl-5-isoxazoyl) sulfamoyl aniline acid. ] terephthalic. 2, 5-di [4- (N, N-diethylsulfamoyl) anilino] terephthalic acid To a mixture of 56.34 g (0.77 mol) of diethylamine in 150 ml of anhydrous acetone cooled to 10 ° C was added 60.0 g (0.26 mol) of acetamidobenzene sulfonyl chloride (Aldrich Chemical Co.) over a period of ten minutes. The reaction was exothermic and vigorous. After adding an additional 50 ml of acetone, the mixture was heated at reflux for two hours. The mixture was added, after being cooled to room temperature, to 1400 ml of water and stirred. The resulting solid was collected by filtration and washed with water until free of alkalines. The cake of the wet filter press was added to 150 ml of water, treated with 90 g of concentrated hydrochloric acid, heated to reflux with stirring for 45 minutes and cooled to room temperature. Concentrated ammonium hydroxide was slowly added to produce a solid, which was collected by filtration and washed with water until free of alkalines. The cake of the wet filter press was dried in an oven to obtain 51.0 g (86.6% of theory) of the intermediate compound 4-amino (N, N-diethyl) benzenesulfonamide (or p- (N, N -diethyl) sulfanilamide). To 150 g of methanol was added with stirring 20 g (87.6 mmol) of dimethylsuccinyl succinate, 46 g (201.6 mmol) of p- (N, N-diethyl) sulfanilamide and 0.7 g of concentrated sulfuric acid . The reaction mixture was slowly heated to a temperature of 95 to 97 ° C and maintained at that temperature for five hours. After cooling the reaction mixture to 50 ° C, 26 g of sodium 3-nitrobenzenesulfonate, 2 g of water and 75 g of 45% aqueous potassium hydroxide were slowly added with stirring. The resulting mixture was then slowly heated to 90 ° C and maintained at that temperature for four hours. The reaction mixture was cooled to room temperature and added to 500 ml of water. Concentrated sulfuric acid was added slowly to produce a solid, which was collected by filtration and washed with water. The cake of the wet filter press was dried in an oven to obtain 52.2 g (96.3% of theory) of 2,5-di [4- (N, N-diethylsulfamoyl) anilino] terephthalic acid. 2, 5-bis [4- (3-methoxypropyl-sulphonyl) anilino] -1,4-cyclohexadiene-1-dicarboxylic acid, dimethyl ester To a mixture of 40.11 g (0.45 mol) of methoxy-propylamine in 113 ml of anhydrous tetrahydrofuran were added with stirring 54.9 g of sodium carbonate. The mixture was cooled to 10 ° C, after which 104.9 g (0.45 mol) of acetamidobenzenesulfonyl chloride (Aldrich Chemical Co.) was added over a period of 45 minutes. The mixture was kept at 50 ° C for two hours and cooled to room temperature. After adding 21 g (0.525 mol) of sodium hydroxide, the reaction mixture was heated at reflux for one hour. The mixture was extracted, after being cooled to room temperature, with methylene chloride. The methylene chloride solution was washed with water, dried over magnesium sulfate, filtered and concentrated under reduced pressure to obtain 108 g (98%) of the intermediate compound 4-amino-N- (3-methoxypropyl) benzenesulfonamide. To 150 g of methanol was added with stirring 20 g (87.6 mmol) of dimethylsuccinyl succinate, 50 g (204.6 mmol) of 4-amino-N- (3-methoxypropyl) benzenesulfonamide and 1.0 g of acid concentrated sulfuric The reaction mixture was slowly heated to a temperature of 95 to 97 ° C and maintained at that temperature for five hours. The reaction mixture was added, after being cooled to room temperature, to 200 ml of water and stirred. The resulting solid was collected by filtration and washed with water. The cake of the wet filter press was dried in an oven to obtain 30 g of 2,5-bis [4- (3-methoxypropyl-sulfamoyl) anilino] -1,4-cyclohexadiene-1,4-dicarboxylic acid ester dimethyl Example 1 (comparative) Pigmented 2,9-dimethylquinacridone was prepared in the absence of a sulfonyl-containing derivative according to the invention. To 300 g of polyphosphoric acid (112% phosphoric acid) heated to 88 ° C was added 68.2 g of 2,5-di (4-methylanilino) terephthalic acid over a period of 35 minutes, the temperature below 120 ° C by adjusting the rate of addition. The reaction mixture was heated at 123 ° C for two hours. The melt was cooled to 93 ° C and then slowly poured into 494 g of methanol, the temperature being maintained below 64 ° C by external cooling and adjustment of 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, collected by filtration and washed with water until free of acid. The press of 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 suspension was heated at 90 ° C for one hour. The suspension was cooled, filtered and washed with water until free of alkali and then resuspended 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 pH 3.3, 2.2 g of an anionic surfactant, 30 g of a petroleum distillate and 80 g of water were added and the suspension was stirred for three hours. 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 60 g of 2,9-dimethylquinacridone as a magenta pigment. Example 2 (comparative) Pigment quinacridone was prepared in the absence of the sulfonyl-containing derivative according to the invention. To 270 g of polyphosphoric acid (117% phosphoric acid) heated to 80 ° C was added 60 g of 2,5-dianilinoterephthalic acid. The reaction mixture was heated at 123 ° C for four hours. After the melting was cooled to 94 ° C, the acid strength was adjusted to 110% by dropwise addition of phosphoric acid. The melt was stirred for 20 minutes and then poured slowly into 400 g of methanol, keeping the temperature below 60 ° C by external cooling and adjusting the rate of addition of the melt. The suspension was heated at reflux for one hour and diluted with water, after which the solid component was collected by filtration and washed with water until acid-free. The cake of the resulting filter press was resuspended in water. After adjusting the pH to about 7, 6 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 resuspended in water. After adjusting the pH to 9.3, 3.2 g of a cycloaliphatic carboxylic acid was added. The resulting suspension was heated at 142 ° 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 or used as such for specific applications. Here, the wet cake was dried in an oven at 60 ° C to give approximately 48.4 g of quinacridone as a violet pigment. EXAMPLE 3 Pigmentary 2,9-dimethylquinacridone was prepared exactly as described in Comparative Example 1, except that it was included in the ring closure reaction 2% by weight, relative to the 2,5-di-acid. (4-methylanilino) terephthalic acid, 2, 5-di (sulfamoyl-anilino) terephthalic acid (1.4 g). 2,9-dimethylquinacri-donose (58 g) was obtained as a magenta pigment. A water-based paint prepared as described above exhibited a more intense, brighter and more transparent mass tone and a higher metallic luster, with better rheological properties, compared to QUINDO | R1 Magenta RV-6832 (from Bayer Corporation) . An alkyd melamine enamel paint prepared as described above exhibited a more intense, brighter and more transparent mass tone, with better rheological properties, compared to a paint prepared using QUINDO (R) Magenta RV-6832. EXAMPLE 4 Pigmentary 2,9-dimethylquinacridone was prepared exactly as described in Comparative Example 1, except for the fact that 5% by weight, in relation to the 2,5-acid, was included in the ring closure reaction. di (4-methylanilino) terephthalic acid, 2, 5-di (sulfa-moilanilino) terephthalic acid (3.4 g). 2,9-dimethylqui-nacridone (59 g) was obtained as a magenta pigment. A water-based paint prepared as described above exhibited a more intense, brighter and more transparent mass tone and a higher metallic luster, with better rheological properties, compared to QUINDO (R) Magenta RV-6832. An alkyd melamine enamel paint prepared as described above exhibited a more intense, brighter and more transparent mass tone and a higher metallic luster, with better rheological properties, compared to a paint prepared using QUINDO (R) Magenta RV -6832. Example 5 Pigmentary 2,9-dimethylquinacridone was prepared exactly as described in Comparative Example 1, except for the fact that 10% by weight was included in relation to 2,5-di (4-methylanilino) terephthalic acid , of 2,5-di (sulfamoylanilino) terephthalic acid (6.8 g) in the ring closure reaction. 2,9-dimethylquina-cridone (59 g) was obtained as a magenta pigment. A water-based paint prepared as described above exhibited a more intense, brighter and more transparent mass tone and a higher metallic luster, with better rheological properties, compared to QUINDO (R) Magenta RV-6832. An alkyd melamine enamel paint prepared as described above exhibited a more intense, brighter and more transparent mass tone and a higher metallic luster, with better rheological properties, compared to a paint prepared using QUINDO (R) Magenta RV -6832. EXAMPLE 6 Pigment quinacridone was prepared exactly as described in Comparative Example 2, except for the inclusion in the reaction of the ring closure of 10% by weight, in relation to 2,5-dianilinoterephthalic acid, of acid 2, 5 -di (sulfamoylanilino) terephthalic (6 g). Quinacridone was obtained (50, 2 g) as a violet pigment.

A water-based paint prepared as described above exhibited a more intense, brighter and more transparent dye tone, dye and metallic blue and a higher metallic gloss compared to a paint prepared using the pigment of Comparative Example 1. Example 7 Pigmentary 2,9-dimethylquinacridone was prepared exactly as described in Example 1, except for the fact that 10% by weight was included in relation to 2,5-di (4-methylanilino) terephthalic acid. 2,5-bis [4- (3, 4-dimethyl-5-isoxazolyl) sulfamoylanilino] terephthalic (6.8 g) in the ring closure reaction. 2,9-Dimethylquinacridone (59 g) was obtained as a magenta pigment. A water-based paint prepared as described above exhibited a more intense, brighter and more transparent dye tone, dye and metallic blue and higher metallic luster as compared to a paint prepared using the pigment of Comparative Example 1. Example 8 prepared 2,9-dimethylquinacridone pigment exactly as described in Comparative Example 1, except that 10% by weight, in relation to 2,5-di (4-methylanilino) terephthalic acid, was included in the ring closure reaction, of 2,5-di [4- (N, N-diethylsul-famoyl) anilino] terephthalic acid (6.8 g). 2,9-Dimethyl-quinacridone (59 g) was obtained as a magenta pigment. A water-based paint prepared as described above exhibited a more intense, brighter and more transparent dye tone, dye and metallic blue and a higher metallic gloss compared to a paint prepared using the pigment of Comparative Example 1. Example 9 Pigmentary 2, 9-methylquinacridone was prepared exactly as described in Comparative Example 1, except for the fact that it included in the ring closure reaction 10% by weight, relative to the 2,5-di (4-) acid. methylanilino) terephthalic acid, 2,5-bis [4- (3-methoxypropyl sulfamoyl) anilino] -1,4-cyclohexadiene-1,4-dicarboxylic acid, dimethyl ester (6.8 g). 2,9-dimethylquinacridone (60.3 g) was obtained as a magenta pigment. Example 10 (comparative) Gamma-quinacridone was prepared from 2,5-dianilino-6,13-dihydroterephthalic acid in the absence of a sulfonyl-containing derivative. To 320 g of polyphosphoric acid (116.5% phosphoric acid) were added 64 g of 2,5-dianilino-6,13-dihydroterephthalic acid over a period of 45 minutes, keeping the temperature below 110 °. C. The reaction mixture was stirred at a temperature of 100 to 110 ° C for one hour and then allowed to cool to 85 ° C, after which the concentration of phosphoric acid was reduced to 85% by slow addition of cold water. The mixture was stirred at a temperature of 85 to 90 ° C for 30 minutes, then slowly poured into 1200 ml of ice / water and stirred at less than 30 ° C for a further hour. The solid component was collected by filtration and washed with water. The cake of the wet filter press was resuspended in 181.3 g of methanol and 73.9 g of water and stirred until uniform. After adding 37.3 g of 50% aqueous sodium hydroxide, the suspension was stirred at less than 35 ° C for one hour. The suspension was then heated to 60 ° C, diluted with 116.6 g of water and heated to reflux for 30 minutes. After allowing the suspension to cool to 60 ° C, 37.3 g of 92% sodium 3-nitrobenzenesulfonate and 31.6 g of water were added sequentially. After ten minutes, the suspension was heated at 88 ° C for three hours. Upon cooling to room temperature, the solid component was isolated by filtration and washed with water. The cake was dried from the wet filter press to give 42.5 g of gamma-quinacridone.

EXAMPLE 11 Gamma-quinacridone was prepared from 2,5-dianilino-6,13-dihydroterephthalic acid in the presence of a 2, 5-dianilino-6,13-dihydroterephthalic acid derivative containing sulfonyl according to the invention. To 320 g of polyphosphoric acid (116.5% phosphoric acid) were sequentially added 6, 8 g of 2,5-bis [4- (3-methoxypropylsulfamoyl) anilino] -1,4-cyclohexadiene-1,4-dicarboxylic acid, dimethyl ester, and 64 g of 2,5-dianilino-6, 13 acid -dihydroterephthalic over a period of 45 minutes, keeping the temperature below 110 ° C. The reaction mixture was stirred at a temperature of 100 to 110 ° C for one hour and then allowed to cool to 85 ° C, after which the concentration of the phosphoric acid at 85% was reduced by the slow addition of cold water. The mixture was stirred at a temperature of 85 to 90 ° C for 30 minutes, then slowly poured into 1200 ml of ice / water and stirred at less than 30 ° C for a further hour. The solid component was collected by filtration and washed with water. The cake of the resulting wet filter was resuspended in 181.3 g of methanol and 73.9 g of water and stirred until uniform. After adding 37.3 g of 50% aqueous sodium hydroxide, the suspension was stirred at less than 35 ° C for one hour. The suspension was then heated to 60 ° C, diluted with 12.6 g of water and heated to reflux for 30 minutes. After allowing the suspension to cool to 60 ° C, 37.3 g of 92% sodium 3-nitrobenzenesulfonate and 31.6 g of water were added sequentially. After ten minutes, the suspension was heated at 88 ° C for 15 hours. After cooling to room temperature, the solid component was isolated by filtration and washed with water. The cake of the wet filter press was resuspended in 357.1 g of methanol and 357.1 g of water (which includes the amount of water in the cake of the filter press). When the suspension became uniform, 95.2 g of 50% aqueous sodium hydroxide and an additional 60.0 g of 92% sodium 3-nitrobenzenesulfonate were added. The resulting suspension was heated in a sealed system at a temperature of 115 to 120 ° C for six hours. Upon cooling to room temperature, the solid component was isolated by filtration and washed with water. The cake was dried from the wet filter press to obtain 41.0 g of gamma-quinacridone. A pigmented PVC sample prepared as described above using the pigment of Example 11 of the invention exhibited a more transparent dough tone and a yellow dye than a pigmented PVC sample prepared using the pigment of Comparative Example 10.

Claims (14)

1. CLAIMS 1. A process for the preparation of quinacridone pigments consisting of: (a) heating, at a temperature of about 80 ° C to about 145 ° C, a reaction mixture consisting of: (i) 2,5-dianilinoterephthalic acid , 2, 5-dianilino-6, 13-dihydroterephthalic acid, 2,5-dianilino-3,6-dioxo-l, 4-cyclohexanediene-1,4-dicarboxylic acid or a derivative thereof having one or more substituents in at least one aniline ring; a salt or ester of said acid or derivative thereof, or a mixture thereof; (ii) about 0.1 to about 15 percent by weight, based on component (a) (i), of a sulfonyl-containing derivative of the 2,5-dianilinoterephthalic acid having the formula a derivative containing sulfonyl of 2,5-dianilino-6,13-dihydroterephthalic acid having the formula and / or a derivative containing sulfonyl of 2,5-dianilino-3,6-dioxo-l, 4-cyclohexadiene-1,4-dicarboxylic acid having the formula or a mixture thereof, wherein X1 and X2 are independently 0Ra or NRbRc; Y1 and Y2 are independently hydrogen, halogen, CX-C6 alkyl or C6-alkoxy; R1 and R2 are independently hydrogen, a metal, an ammonium ion or alkyl Ra is hydrogen, a metal, an ammonium ion or a C ^ C ^ alkyl; Rb is hydrogen, C 1 -C 12 alkyl or substituted C 1 -C 4 alkyl, cycloalkyl
2. C5-C7 or substituted C5-C7 cycloalkyl, C6-C10 aryl, heteroaryl having five or six ring atoms wherein at least one such ring atom is N, 0, S or a combination of 20, or C7-C16 aralkyl; Rc is hydrogen, C-C12 alkyl or substituted C2-C12 alkyl, C5-C7 cycloalkyl or substituted C5-C7 cycloalkyl, or C7-C16 aralkyl, or R and Rc, together with the nitrogen atom, form a heterocycle from 5 to 7 ring atoms, and m and n independently from 0 to 3, with the proviso that at least one of mon is not 0, and (iii) about 3 to about 20 parts by weight, per part of component (a) (i), of a dehydrating agent, with the proviso that, if any of components (a) (i) or (a) (ii) is a 2,5-dianilino-6, 13-dihydroterephthalic acid or same, 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) eventually mixing the pigment of quinacri dona with one or more pigment derivatives. 2. A process according to claim 1, wherein the component (a) (i) is selected from the group consisting of 2,5-dianilinoterephthalic acid, 2,5-di (4-methylanilino) terephthalic acid, 2-5- di (4-methoxyanilinyl) terephthalic acid, 2,5-di (4-chloroanilino) terephthalic acid and mixtures thereof.
3. 3. A process according to Claim 1, wherein component (a) (ii) is a derivative containing sulfonyl of 2,5-dianilinoterephthalic acid having the formula where X1 and X2 are independently ORa (where Ra is hydrogen, a metal, an ammonium ion or C1-C12 alkyl) or NRbRc (where Rb is hydrogen, C1-C12 alkyl or substituted C ^ C ^ alkyl, C5-C7 cycloalkyl or substituted C5-C7 cycloalkyl, C6-C10 aryl, heteroaryl having five or six ring atoms wherein at least one such ring atom is N, O, S or a combination thereof, or aralkyl C7 ~ ci6 YR ° is hydrogen, alkyl or substituted Cx-C12 alkyl, C5-C7 cycloalkyl or substituted C5-C7 cycloalkyl, or C7-C16 aralkyl, or where Rb and Rc, together with the nitrogen atom, form a heterocycle having from 5 to 7 atoms of ring).
4. 4. A process according to Claim 1, wherein component (a) (ii) is a derivative containing sulfonyl of 2,5-dianilinoterephthalic acid having the formula where Ra is hydrogen, a metal, an ammonium ion or C2- ^ -12 alkyl •
5. 5. A process according to Claim 1, wherein component (a) (ii) is a derivative containing sulfonyl of 2,5-dianilinoterephthalic acid which has the formula wherein each Rb is independently hydrogen, C1-C12 alkyl or substituted Cx-C12 alkyl, C5-C cycloalkyl or substituted C5-C7 cycloalkyl, C6-C10 aryl, heteroaryl having five or six ring atoms wherein at least one such ring atoms is N, 0, S or a combination thereof, or C7-C16 aralkyl and each Rc is independently hydrogen, C1-C12 alkyl, C5-C7 cycloalkyl or C7-C16 aralkyl, or where Rb and Rc, together with the nitrogen atom, form a heterocycle having 5 to 7 ring atoms.
6. 6. A method according to Claim 1, wherein component (a) (ii) is
7. 7. A process according to Claim 1, wherein component (a) (ii) is a derivative containing sulfonyl of 2,5-dianilino-6,13-dihydroterephthalic acid having the formula where X1 and X2 are independently ORa (where Ra is hydrogen, a metal, an ammonium ion or alkyl or NRbrR, C ' (wherein Rb is hydrogen, C 1 -C 12 alkyl or substituted C 1 -C 4 alkyl, C 5 -C 7 cycloalkyl or substituted C 5 -C 7 cycloalkyl, C 6 -C 12 aryl, heteroaryl having five or six ring atoms wherein at least one such ring atoms is N, O, S or a combination thereof, or aralkyl ct-ci6 YR ° is hydrogen, C 1 -C 12 alkyl or substituted C 1 -C 12 alkyl, C 5 -C 7 cycloalkyl or substituted C 5 -C 7 cycloalkyl, or C 7 aralkyl -C16, or where Rb and Rc, together with the nitrogen atom, form a heterocycle of 5 to 7 carbon atoms).
8. 8. A method according to Claim 1, wherein component (a) (ii) is
9. 9. A process according to Claim 1, wherein the reaction mixture is heated in step (a) at a temperature of 100 ° C to 130 ° C.
10. 10. A process according to claim 1, wherein the dehydrating agent (a) (iii) is polyphosphoric acid.
11. 11. A process according to Claim 10, wherein 3 to 10 parts by weight, based on component (a) (i), of polyphosphoric acid are used.
12. 12. A process according to Claim 1, wherein the reaction mixture of step (a) is quenched by adding said reaction mixture to water, an aliphatic alcohol or a mixture thereof.
13. 13. A process according to Claim 1, wherein the reaction mixture of step (a) is quenched by adding said reaction mixture to methanol.
14. 14. A quinacridone pigment prepared by the process according to claim 1. SUMMARY OF THE INVENTION This invention relates to a process for the preparation of quinacridone pigments (a) by heating a reaction mixture consisting of (i) a 2,5-dianilinoterephthalic acid, a 2, 5-dianilino-6, 13 acid. -thial dihydroteref or a 2,5-dianilino-3,6-dioxo-1,4-cyclohexadiene-1,4-dicarboxylic acid; (ii) about 0.1 to about 15 weight percent, based on component (a) (i), of one or more derivatives containing 2, 5-dianilinoterephthalic acid sulfonyl, acid 2 , 5-dianilino-6, 13-dihydroterephthalic and / or 2,5-dianilino-3,6-dioxo-1,4-cyclohexadiene-1,4-dicarboxylic acid, and (iii) about 3 to about 20 parts in weight, by component (a) (i), of a dehydrating agent, with the proviso that if any of components (a) (i) or (a) (ii) is a 2,5-dianilino- 6, 13-dihydroterephthalic or derivative thereof, the reaction step (a) further comprises an oxidation step; (b) drowning the reaction mixture of step (a) with a liquid in which the quinacridone pigment is substantially insoluble, and (c) isolating the quinacridone pigment.