Diazo pigment composition

Abstract: A pigment composition capable of giving a printing ink having excellent fluidity, gloss and storage stability, and which contains: a diazo pigment obtainable by coupling a tetrazo compound of a dihalogenobenzidine and an acetoacetanilide, and a reaction product obtainable by coupling a tetrazo compound of a dihalogenobenzidine and an acetoacetylation product.

Description: The present invention provides a pigment composition which especially has excellent fluidity and storage stability and further has excellent gloss and tinting strength when used in various applications, e.g. in a printing ink. When a pigment is used in a printing ink, the pigment is required to have good gloss, tinting strength, fluidity and storage stability. As the pigment content in an ink is sometimes increased to densify the ink, the fluidity and storage stability of the pigment are especially important. When the fluidity is poor, the dilution ratio with a solvent is increased to achieve a suitable viscosity for printing, and the gloss and tinting strength are consequently degraded. Various attempts have been heretofore made to improve these properties of diazo pigments. For example, one attempt is found in a method where an activator, emulsion, etc., are added to improve the fluidity. In treatment of a pigment according to this method, however, pigment particles aggregate or grow to a larger size, and when the pigment is used in a printing ink, the gloss and tinting strength are lost. Another attempt is found in a method where a pigment is treated with an amine to improve the gloss and tinting strength (e.g. Japanese Patent Publications Nos. 1821/1973, 2753/1971 and 48587/1982). However, the defect of this method is that the properties of an ink containing the treated pigment change with time, and its gloss, tinting strength and fluidity are degraded. Still another attempt is found in a method in which the properties of an ink are improved by acetoacetylating the above amine, etc., mixing the aceto-acetylated amine, etc., with acetoacetanilides and coupling the mixture with a pigment (e.g. GB-A-1139294 and JP-A-246260/1986). However, this method is hardly satisfactory with regard to the gloss, tinting strength and fluidity. Further, for example, Japanese Patent Publication No. 49087/1980 discloses a diazo pigment obtained by a coupling reaction between a tetrazo compound of 3,3'-dichlorobenzene and acetoacetanilide, in which the coupling is carried out by using carboxylic acid-containing acetoacetanilide as part of a coupling component. Since, however, this diazo pigment has high selectivity to a dispersing medium, it sometimes gives poor gloss when used particularly in a gravure printing ink. The present invention seeks to provide an improved diazo pigment composition capable of giving a printing ink having excellent fluidity in which the amount of solvent for viscosity adjustment is decreased. The present invention further provides an improved diazo pigment composition capable of giving a printing ink having excellent gloss on an ink coating and excellent tinting strength. An improved diazo pigment composition according to the present invention is also capable of giving a printing ink having excellent storage stability. According to the present invention, there is provided a diazo pigment composition containing: (a) a diazo pigment obtainable by coupling a tetrazo compound of a dihalogenobenzidine with an acetoacetanilide, and (b) 0.3 to 30 mol%, based on the amount of acetoacetanilide in (a), of a reaction product obtainable by coupling a tetrazo compound of a dihalogenobenzidine with an acetoacetylation product of a compound of formula (1) H₂N-Q-NH₂ (1) wherein Q is a noncyclic saturated hydrocarbon moiety having 2 to 10 carbon atoms or is a group of formula (2) wherein R represents a hydrogen atom, an alkyl group, an aryl group or an aralkyl group, n represents an integer of from 2 to 4 and m represents an integer of from 0 to 5. The present invention uses, as coupling agents, an acetoacetylation product of the compound of formula (1) in addition to a substituted or unsubstituted acetoacetanilide, and the amount of the acetoacetylation product is 0.3 to 30 mol%, preferably 1 to 20 mol%,, based on the acetoacetanilide. If the amount of the acetoacetylation product is less than 0.3 mol%, any effect of the acetoacetylation product on improvement of fluidity is not obtained. Further, even if the amount is more than 30 mol%, any effect corresponding to the increased portion of the acetoacetylation product is not obtained, and an adverse effect is sometimes exerted on a printing ink. Examples of the acetoacetanilides which may be employed in the present invention inclulde, in addition to acetoacetanilide, acetoaceto-o-toluidide and acetoaceto-o-anisidide. Derivatives wherein at least one of a methyl group, a methoxy group, a nitro group or a halogen atom is substituted on the benzene nucleus of the anetoacetanilide for a hydrogen atom may be mentioned by way of example. Typical examples of the compound of formula (1) include 1,3-diaminopropane, 1,4-diaminobutane, 1,6-diamino-hexane, 1,8-diaminooctane, methyliminobispropylamine, phenyliminobispropylamine, benzyliminobispropylamine, iminobispropylamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine and pentaethylenehexamine. The acetoacetylation reaction of the compound of formula (1) is well known, and carried out in many ways. It is preferable that the acetoacetylation product is produced by adding diketene to a water solution or diluted acetic acid solution of said amine compound. The resultant acetoacetylation product of the compound of formula (1) is in a solution state. The degree of acetoacetylation is 2 when the compound of formula (1) is diamine since two terminals of the compound are acetoacetylated, and it is sometimes more than 2 when Q in formula (1) represents a compound of formula (2) since the secondary amine portion(s) of the resultant polyamine molecule is further acetoacetylated. In the present invention, 3,3′dichlorobenzidine or 3,3′dibromobenzidine is preferably usable as dihalogenobenzidine. In the present invention, 3,3′dichlorobenzidine is typically used as dihalogenobenzidine. The pigment composition of the present invention can be obtained by the following process which comprises: (1) carrying out a coupling reaction between a tetrazo compound of 3,3′dichlorobenzidine and an acetoacetanilide in the copresence of acetoacetanilides and an acetoacetylation product of the compound of formula (1) (mixture coupling), or (2) mixing a pigment composition obtained by reacting a tetrazo compound of 3,3′dichlorobenzidine with an acetoacetanilide and a pigment composition obtained by coupling such a tetrazo compound and the acetoacetylation product of the compound of formula (1), or (3) forming a monoazodiazonium compound in the form of A-N=N-B-N₂⁺ wherein A represents an acetoacetylation product moiety of the compound of formula (1), B represents a moiety of 3,3′dichlorobenzidine, and then carrying out its coupling reaction with acetanilides, or (4) mixing a pigment composition obtained by a reaction between a tetrazo compound of 3,3′-dichlorobenzidine and acetanilide, with the pigment composition obtained in the above (3). In view of the number of production steps and effect, the process mentioned in the above (1) is the most preferable. The pigment composition of the present invention may contain auxiliaries such as a surface active agent, amine, etc. The present invention will be illustrated by referring to Examples, in which part and % stand for part by weight and % by weight. When the pigment composition of the present invention is used in a printing ink, e.g. gravure ink, etc., the printing ink can give excellent fluidity, and the amount of a solvent for adjustment of the viscosity can be minimized. As a result, a printing ink using the pigment composition of the present invention exhibits excellent gloss on the ink coating and tinting strength, and further, it shows excellent storage stability. EXAMPLE 1 17.1 parts of 3,3′-dichlorobenzidine hydrochloride and 15.5 parts of 35 % hydrochloric acid were added to 200 parts of water. After the resultant slurry was cooled to 0°C, 38.5 parts of a 20 % sodium nitrite solution was added to the slurry, and mixture was stirred for 1 hour to give a solution. The solution was filtered, and a small amount of sulfamic acid was added to the filtrate to prepare a solution of tetrazotized 3,3′-dichlorobenzidine. Separately, 20 parts of acetoacet-o-toluidide and 9.2 parts of sodium hydroxide were added to and dissolved in 200 parts of water. Added gradually to this solution was 147 parts of a 10 % acetic acid solution to prepare a suspension. 0.75 part of an acetoacetylation product of triethylenetetramine was added to the suspension, and the mixture was stirred for 5 minutes. The above tetrazo solution was added to this mixture over 30 minutes, during which the coupling reaction was maintained at about 20°C. The resultant slurry was filtered, and a remaining solid was washed with water to give a pigment composition. The pigment composition was dried at 90°C. The acetoacetylation product of triethylenetetramine used in this Example was prepared by dissolving 15 parts of triethylenetetramine in 150 parts of water, gradually adding 31 parts of diketene, and then heating the resultant mixture to 60°C. EXAMPLE 2 A solution of tetrazotized 3,3′-dichlorobenzidine and a suspension of acetoaceto-o-toluidide were prepared in the same way as in Example 1, and a coupling reaction was carried out to give a slurry of a pigment composition. Separately, 0.92 part of sodium hydroxide, 14.7 parts of a 10 % acetic acid solution and 0.75 part of an acetoacetylation product of triethylenetetramine were added to 20 parts of water to prepare a solution. By using this solution and a solution of tetrazotized 3,3′-dichlorobenzidine, a coupling reaction was carried out to give a slurry of a pigment composition. These two slurries were mixed homogeneously. Then, the resultant homogenuous slurry was filtered, and a remaining solid was washed with water to give a pigment composition. The pigment composition was dried at 90°C. COMPARATIVE EXAMPLE 1 A pigment composition was prepared by repeating Example 1 except that no acetoacetylation product of triethylenetetramine was added. EXAMPLE 3 Example 1 was repeated to prepare a slurry of a pigment composition except the use of 20 parts of acetoaceto-p-toluidide in place of acetoaceto-o-toluidide and an acetoacetylation product of 1.0 part of tetraethylenepentamine in place of triethylenetetramine. The acetoacetylation product of tetraethylenepentamine was prepared in the same way as in Example 1. 4.2 parts of 3-beef tallow aminopropylamine was added to a diluted acetic acid solution and dissolved in the solution under heat. Then, the solution was added to the above coupled slurry, and the pH of the slurry was adjusted to about 11 by using a sodium hydroxide solution. The resultant slurry was filtered, and a remaining solid was washed with water and dried at 90°C to give a pigment composition. EXAMPLE 4 Example 2 was repeated to prepare slurries of pigment compositions except the use of 20 parts of acetoaceto-p-toluidide in place of acetoaceto-o-toluidide and an acetoacetylation product of tetraethylenepentamine in place of the acetoacetylation product of triethylenetetramine. The slurries were mixed, and then 4.2 parts of 3-beef tallow aminopropylamine was added in the same way as in Example 3, and the procedure of Example 3 was repeated to give a pigment composition. EXAMPLE 5 A solution of tetrazotized 3,3′-dichlorobenzidine was obtained in the same way as in Example 1. An acetoacetylation product of 1.0 part of tetraethylenepentamine was added to the tetrazo solution with stirring at 0 to 10°C, and the mixture was stirred for 30 minutes. A suspension was prepared in the same way as in Example 1 except the use of 20 parts of acetoaceto-p-toluidide in place of acetoaceto-o-toluidide. The above tetrazo solution containing the acetoacetylation product of tetraethylenepentamine was added to the suspension over about 30 minutes, during which the reaction was maintained at 20°C. Then, after the resultant slurry was heated to 50°C, 4.2 parts of 3-beef tallow aminopropylamine was added in the same way as in Example 3, and the procedure in Example 3 was repeated to give a pigment composition. COMPARATIVE EXAMPLE 2 Example 3 was repeated except that no acetoacetylation product of tetraethylenepentamine was added. EXAMPLE 6 A pigment composition was produced by repeating Example 3 except the use of 21.5 parts of acetoaceto-p-anisidide in place of acetoaceto-p-toluidide and 0.77 part of methyliminobispropylamine in place of tetraethylenepentamine. An acetoacetylation product of the methyliminobispropylamine was prepared in the same way as in Example 1. COMPARATIVE EXAMPLE 3 Example 6 was repeated except that no acetoacetylation product of methyliminobispropylamine was added. EXAMPLE 7 A pigment composition was produced by repeating Example 3 except the use of an acetoacetylation product of 0.6 part of hexamethylenediamine in place of the acetoacetylation product of tetraethylenepentamine. The acetoacetylation product of the hexamethylenediamine was prepared in the same way as in Example 1. COMPARISON TEST Gravure inks using the pigment compositions obtained in Examples and Comparative Examples were compared on fluidity, gloss and reflective density. With regard to each of the pigment compositions obtained in Examples 1 and 2 and Comparative Example 1, an ink was prepared by mixing 10 parts of the pigment composition with 70 parts of nitrocellulosebased varnish (nonvolatile content 31 %) and 20 parts of a solvent, and dispersing the mixture in a paint conditioner. Concerning each of the pigment compositions obtained in Examples 3, 4, 5, 6 and 7and Comparative Examples 2 and 3, an ink was prepared by mixing 10 parts of the pigment composition with 80 parts of lime rosin (nonvolatile content 50 %) and 10 parts of a solvent and dispersing the mixture in a paint conditioner. In the test, the prepared inks were examined after they were left to stand at 25°C for 10 days. A. Fluidity A BM model rotational viscometer was used to measure viscosities at 6, 12, 30 and 60 rpm (at a measurement temperature of 25±1°C), and the results were evaluated by using the following three grades. ○: excellent ▵: good X: poor B. Gloss and reflective density With regard to the above nitrocellulose-based inks, a solvent was added to each of them and adjusted so as to show 25±0.5 seconds in a No.3 Zahn cup. Then, each of these inks was used to carry out printing on a triacetate film on a printing machine. Concerning the above lime rosin-based inks, a solvent was added to each of them and adjusted so as to show 14±0.5 seconds in a No.3 Zahn cup. Then, each of these inks was used to carry out printing on wood free paper on a printing machine. Thereafter, the gloss and density of each of the prints were measured by using a glossmeter and a reflection densitometer. The results were evaluated by using the following three grades and are shown in Table 1. ○: excellent ▵: good X: poor Fluidity Gloss Reflective density Example 1 ○ ○ ○ Example 2 ▵ ▵ ▵∼ ○ C-Ex. 1 X X X Example 3 ○ ○ ○ Example 4 ▵∼ ○ ▵∼ ○ ○ Example 5 ▵∼ ○ ▵∼ ○ ▵ Example 6 ▵∼ ○ ○ ○ Example 7 ▵∼ ○ ▵∼ ○ ▵∼ ○ C-Ex. 2 X X X C-Ex. 3 X X X

Claims: A pigment composition containing: (a) a diazo pigment obtainable by coupling a tetrazo compound of a dihalogenobenzidine with a substituted or unsubstituted acetoacetanilide, and (b) 0.3 to 30 mol%, based on the amount of the acetoacetanilide in (a), of a reaction product obtainable by coupling a tetrazo compound of a dihalogenobenzidine with an acetoacetylation product of a compound of formula (1) H₂N-Q-NH₂ (1) wherein Q is a noncyclic saturated hydrocarbon moiety having 2 to 10 carbon atoms or is a group of formula (2) in which R is a hydrogen, an alkyl group, an aryl group or an aralkyl group, n is an integer of from 2 to 4 and m is an integer of from 0 to 5. A pigment composition according to claim 1 wherein Q in formula (1) is a group of formula (2) and R is a hydrogen atom. A pigment composition according to claim 1 or 2 wherein at least one hydrogen atom on the benzene nucleus of the acetoacetanilide is substituted by a methyl group, a methoxy group, a nitro group or a halogen atom. A pigment composition according to any one of claims 1 to 3 wherein the acetoacetylation product of a compound of formula (1) has at least two acetoacetylated terminal amines. A pigment composition according to any one of claims 1 to 4 which contains a pigment obtainable by coupling a tetrazo compound of a dihalogenobenzidine with an acetoacetanilide in the copresence of an acetoacetylation product of the compound of formula (1). A pigment composition according to any one of claims 1 to 4 which contains a mixture of separately prepared (a) and (b). A pigment composition according to any one of claims 1 to 6 wherein the dihalogenobenzidine is 3,3'dichlorobenzidine or 3,3'dibromobenzidine. A printing ink comprising a pigment composition as claimed in any one of claims 1 to 7.

Inventors: CHIBA ATARU TOYO INK MANUFACTU, KITAMURA KENJI TOYO INK MANUFA, MOCHIZUKI AKIMITSU TOYO INK MA, SUZUKI YOSHIE TOYO INK MANUFAC, CHIBA, ATARU TOYO INK MANUFACTURING CO., LTD., KITAMURA, KENJI TOYO INK MANUFACTURING CO., LTD., MOCHIZUKI, AKIMITSU TOYO INK MANUFACTURING CO.LTD., SUZUKI, YOSHIE TOYO INK MANUFACTURING CO., LTD.
Applicants: TOYO INK MFG CO, TOYO INK MANUFACTURING CO., LTD.
Application year: 1989
Main classification: C09B67
IPC codes: C09B67