Toning agent

Details Toning agent Toning agent

2000-06-16

2003-04-15

Kumar, Shailendra (Department: 1621)

Organic compounds -- part of the class 532-570 series

Organic compounds

Amino nitrogen containing

C564S153000, C562S467000, C560S056000, C430S105000, C534S841000, C534S842000

Reexamination Certificate

active

06548703

ABSTRACT:

TECHNICAL FIELD
The present invention relates to a novel toning agent comprising 2-hydroxynaphthalene-3,6-dicarboxylic acid and derivatives thereof. In more detail, the present invention relates to a toning agent for an azo pigment and a method for preparing an azo pigment with a modified tone.
BACKGROUND ART
Azo pigments are synthesized by coupling a diazonium salt with a coupler. Among the couplers employed in the coupling reaction, hydroxynaphthalene-mono-carboxylic acids and derivatives thereof are especially important compounds.
Hydroxynaphthalene mono carboxylic acids used as couplers include 2-hydroxynaphthalene-3-carboxylic acid, 2-hydroxynaphthalene-6-carboxylic acid and the like and 2-hydroxynaphthalene-3-carboxylic acid is popular.
Azo compounds synthesized with the coupler component of 2-hydroxynaphthalene-3-carboxylic acid include Brilliant Carmine 6B (Pigment Red 57) and Watchung Red (Pigment Red 48). They are prepared by diazotizing 6-amino-m-toluensulfonic acid and 6-amino-4-chloro-m-tolunensulfonic acid, respectively, and coupling the resulting diazonium salts with 2-hydroxynaphthalene-3-carboxylic acid.
In addition, an azo pigment which incorporate 2-hydroxynaphthalene-6-carboxylic acid as a coupler component has also been known (Japanese Patent Application Laid Open Nos. 302471/90 and 238231/95).
The azo pigments have been applied to various purposes, for example, printing ink, coating composition, paint composition, plastics and cosmetics. Depending on the application, a variety of performances are required for the pigment. For example, brightness and transparency are required for printing ink, durability and hiding effect are required for coating composition, and thermal resistance is required for plastics. In formulating even pigments comprising a compound having the same chemical structure, therefore, it may be necessary to formulate such pigments exhibiting properties or characteristics, which fit well with their intended application fields.
The color and other properties of a pigment are in principle the attributes of its chemical structure, but its characteristics, such as brilliance, transparency and hiding power, may change as well depending upon the physical parameters of the pigment, such as fineness, shape and surface conditions of the particles. The property of pigments can be altered to some extent by modifying the manufacturing steps, or utilizing such additives as wood rosin, for example, but cannot to a satisfactory degree. On the other hand, it is also known that the tone and physical properties of pigments can be modified by replacing a part of 2-hydroxynaphthalene-3-carboxylic acid, which is used as a coupling component, with a suitable amount of a toning agent (Japanese Patent Laid-Open No. 116753/1981). The present applicant disclosed several compounds which can modify the tone of an azo pigment (Japanese Patent Laid-Open Nos. 42662/1983, 181864/1986, 138560/1987 and 138561/1987).
SUMMARY OF THE INVENTION
Objects of the present invention are to provide a toning agent which enable to modify the tone of an azo pigment as desired, and also to provide a process for preparing an azo pigment with the modified tone.
The inventors studied intensively on toning agents which enable to modify the tone of an azo pigment as desired, and found that it could be modified by admixing 2-hydroxynaphthalene-3,6-dicarboxylic acid or a derivative thereof with the primary coupler component of the azo pigment.
Accordingly, the present invention provides a toning agent comprising a compound having the general formula [I];
wherein
Y is —(CONH)n-X or —COR,
Y′ is —(CONH)n-X′ or —COR′,
X and X′ are optionally branched alkyl groups having 1-20 carbon atoms, optionally substituted aromatic groups, or optionally substituted heterocyclic groups having conjugated double bonds,
n is an integer of 1 or 2,
R and R′ are hydroxy groups, optionally branched alkoxy groups having 1-6 carbon atoms, benzyloxy groups, phenyloxy groups or phenacyloxy groups, provided that when either R or R′ is a hydroxy group, said group may optionally form an acceptable salt,
R
2
is a hydrogen atom, an optionally branched alkyl group having 1-6 carbon atoms, an acyl group having 1-6 carbon atoms or a phenyl alkyl group,
Z is one or more atoms or groups selected from the group consisting of a hydrogen atom, an optionally branched alkyl group having 1-6 carbon atoms, an optionally branched alkoxy group having 1-6 carbon atoms, a halogen atom, a sulfo group, a nitro group, a nitroso group, and an amino group, provided that Z may be combined with either of the two rings of the naphthalene ring.
Further, the present invention also provide a process for preparing an azo pigment comprising the steps of admixing the toning agent represented by the above formula [I] with the primary coupler component for the azo pigment and, coupling the mixed coupler composition with a diazonium salt of an aromatic compound.
The term “toning” or “tone” as used in this invention denotes to provide pigments, by some means, with controlled properties or characteristics in terms of, for example, color, brilliance, transparency and hiding power.
The term “toning agent” as used in this invention, denotes a part of coupler composition used in preparing an azo pigment. A small amount of the toning agent may be admixed with a primary coupler component used in preparation of the azo pigment to provide the pigment with a modified tone than that obtained without the toning agent. Generally, the amount of the toning agent contained in the whole coupler composition used for preparing the desired azo pigment may be less than 50 mol %, preferably less than 10 mol %, and especially, less than 5 mol %. When said amount of the toning agent is admixed with the primary coupler component, an azo pigment with a modified tone, which is different from those obtained by mixing two azo pigments, each of which is obtained by means of respective couplers (i.e. the primary coupler and the toning agent) in the ratio of the amount of the respective couplers, can be obtained.
As described above, the toning agent used in this invention, i.e. the compound represented by the general formula [I], is a 2-hydroxynaphthalene-3,6-dicarboxylic acid, or ester, amide or ureide derivative thereof.
In the present invention, the amide or ureide derivative may be prepared by obtaining acid chloride of the starting compound by means of thionyl chloride or the like in a solvent such as xylene or sulfolane in a conventional manner, and then reacting the acid chloride with amine or urea. Alternatively, they can be prepared by reacting the starting compound directly with amine or urea in the presence of phosphorous trichloride, dicyclohexylcarbodiimide or the like.
Examples of the amines or ureas, i.e. starting materials which constitutes the group X or X′ in the Y and Y′ may include optionally branched alkyl groups having 1-20 carbon atoms, optionally substituted aromatic amino compounds such as aniline (X or X′ is a phenyl group), amino naphthalene (X or X′ is a naphthyl group), aminoanthracene (X or X′ is a anthryl group), aminopyrene (X or X′ is a pyrenyl group), amino fluorene (X or X′ is a fluororenyl group) or aminoanthraquinone (X or X′ is an anthraquinonyl group); and optionally substituted heterocyclic compounds having conjugated double bonds such as aminobenzimidazolone (X or X′ is a benzimidazolonyl group), aminocarbazole (X or X′ is a carbazolyl group), aminopyridine (X or X′ is a pyridyl group), aminothiazole (X or X is a thiazolyl group), aminobenzothiazole (X or X′ is a benzothiazolyl group), or aminoimidazole (X or X′ is an imidazolyl group) as well as aminoindole (X or X′ is an indolyl group), aminothiophene (X or X′ is a thiofuryl group), aminophenothiazine (X or X′ is a phenothiazinyl group), aminoacridine (X or X′ is an acridinyl group), and aminoquinoline (X or X′ is a quinolin

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