ACETOACETYLARYLIDE SUSPENSIONS IN PIGMENT APPLICATIONS

Abstract: The invention provides a process for forming an acetoacetarylide slurry, comprising: (a) adding a solid acetoacetarylide to a homogenizer; (b) homogenizing the acetoacetarylide in the presence of water and one or more additives to form an acetoacetarylide slurry. The invention further provides a process for forming an acetoacetarylide-based pigment, comprising: (a) reacting a diketene with an amine to form an acetoacetarylide slurry; (b) separating the acetoacetarylide as a solid from the acetoacetarylide slurry; (c) adding the acetoacetarylide solid to a homogenizer; (d) homogenizing the acetoacetarylide in the presence of water and one or more additives to form an acetoacetarylide slurry; (e) pumping the acetoacetarylide slurry to a reaction tank; (f) adding an alkali or alkaline earth metal base to the slurry; (g) adding an acid to form a precipitate of the acetoacetarylide; and (h) reacting the precipitate with a diazonium salt, thereby forming an azo pigment. This invention also includes the pigments and intermediates thereto formed by the above processes.

Description: ACETOACETYLARYLIDE SUSPENSIONS IN PIGMENT APPLICATIONS This invention provides a method of suspending solid acetoacetarylide species in a solvent using additives and homogenation equipment in order to prepare a heterogeneous slurry having a concentration appropriate for use in pigment applications. It further provides a method of preparing acetoacetarylide-based pigments using said heterogeneous slurry. Acetoacetarylide-based pigments are well known. US-A-4 558 158, US-A-4 643 770, US-A-4 648 907 and US-A-4 885 033 disclose numerous examples of acetoacetarylide- based pigments. Methods of preparing acetoacetarylide-based pigments are also well known in the art and are disclosed in US-A-4 558 158, US-A-4 648 907 and US-A-4 885 033. Acetoacetarylide-based pigments are used in printing inks, paints, colored plastics, colored office articles, cosmetics, and colored paper because of their superior combination of rheology, stability, and color strength. Because of their widespread use, a simple, efficient synthesis of acetoacetarylide-based pigments would be of great commercial importance. Previous methods for forming acetoacetarylide-based pigments have been hampered by the fact that production of purified acetoacetarylides results in an acetoacetarylide solid that is bulky and difficult to handle. The transport of solid acetoacetarylide in bags, drums, or other containers, as performed in previous methods for forming acetoacetarylide-based pigments, is difficult, time consuming, and expensive. Further, the solid acetoacetarylide containers generate waste and the arylide itself generates dust which is an industrial hygiene concern. Consequently, the problem to be solved by this invention was to provide a simple and economical method for forming a flowable form of acetoacetarylides which is easy to handle. According to the invention, this problem has been solved by the process of claim 1. It has been found that a stable acetoacetarylide slurry can be prepared by: (a) adding a solid acetoacetarylide to a homogenizer, and (b) homogenizing the acetoacetarylide in the presence of water and one or more additives to form an acetoacetarylide slurry. Preferably, one or more of the additives of step (b) is a suspension additive (dispersant), more preferably, it is a N-alkyl amine oxide. Here and hereinbelow, N-alkyl amine oxides are to be understood as oxides of tertiary amines comprising at least one long-chain alkyl group, preferably a linear or branched C 8 _ 18 alkyl group. Especially preferred are C 8 _ι 8 -alkyl dimethyl amine oxides such as «-octyl dimethyl amine oxide, isononyl dimethyl amine oxide and H-decyl dimethyl amine oxide. These amine oxides are commercially available under the trademark Barlox ® from Lonza Inc, Fair Lawn, Ν.J.. The creation of a flowable form of acetoacetarylide prior to reaction with an alkali base, acetic acid, and a diazonium salt eliminates tedious steps from the pigment manufacturing process. Unlike prior art processes where addition of NaOH and/or acetic acid is used to create an acetoacetarylide slurry (see e.g. US-A-4 664 710), this invention creates an acetoacetarylide slurry prior to NaOH and acetic acid addition. Further, unlike previous methods that rely solely on solvents to dissolve acetoacetarylides, this invention utilizes additives and homogenization equipment to ensure that an acetoacetarylide slurry with the proper flow characteristics is formed. Unlike the present invention which introduces additives during or just prior to homogenization of the acetoacetarylide, prior acetoacetarylide-based pigment manufacturing processes introduce the additives later, usually during diazotization or afterwards (see e.g. US-A-4 664 710 and US-A-5 863 459). In addition, the use of additives in the subject invention during acetoacetarylide slurry formation can also confer unique and desirable properties on the finished pigment. Depending upon the additive, the improved properties may include: better rheology, stability, holdout, color strength, and/or gloss. Accordingly, this invention also comprises a process for forming an acetoacetarylide-based pigment, comprising: (a) homogenizing a mixture of an acetoacetarylide and one or more additives, thereby forming a slurry of the acetoacetarylide; and (b) reacting the slurry to form an acetoacetarylide-based pigment. Preferably, the mixture of step (a) is formed by: (i) adding an acetoacetarylide solid to a homogenizer containing water; and (ii) adding one or more suspension additives. Preferably, the reacting of step (b) comprises: (i) adding an alkali or alkaline earth metal base to the slurry; (ii) adding an acid to form a precipitate of the acetoacetarylide; and (iii) reacting the precipitate with a diazonium salt, thereby forming an azo pigment. More preferably, the alkali or alkaline earth metal base is a alkali metal hydroxide, in particular sodium hydroxide. Preferably, the acid is acetic acid. In one preferred embodiment, the additives used to homogenize the acetoacetarylide are suspension additives (dispersants). In another preferred embodiment, one or more of the additives is a surfactant to control the particle size and/or flowability of the pigment. Preferably, one or more of the additives of step (b) is a suspension additive (dispersant), more preferably, it is a N-alkyl amine oxide. In a preferred embodiment, the concentration of the acetoacetarylide slurry formed after homogenization is between 30 and 40 weight %. Preferably, the acetoacetarylide slurry formed after homogenization has a consistency suitable for pumping. In a preferred embodiment, the acetoacetarylide of step (a) is selected from the group consisting of acetoacetanilide, acetoacet-o-toluidide, acetoacet-p-toluidide, acetoacet-o- anisidide, acetoacet-m-xylidide, acetoacet-/?-phenetidide, acetoacet-p-anisidide and acetoacet-4-chloro-2,5-dimethoxyanilide. This invention also provides a process for forming an acetoacetarylide-based pigment, comprising: (a) reacting a diketene with an amine to form an acetoacetarylide slurry; (b) separating the acetoacetarylide as a solid from the acetoacetarylide slurry; (c) adding the acetoacetarylide solid to a homogenizer; (d) homogenizing the acetoacetarylide in the presence of water and one or more additives to form an acetoacetarylide slurry; (e) pumping the acetoacetarylide slurry to a reaction tank; (f) adding an alkali or alkaline earth metal base to the slurry; (g) adding an acid to form a precipitate of the acetoacetarylide; and (h) reacting the precipitate with a diazonium salt, thereby forming an azo pigment. Preferred acetoacetarylide slurries that may be formed in step (a) include: acetoacetanilide, acetoacet-o-toluidide, acetoacet- -toluidide, acetoacet-o-anisidide, acetoacet-w-xylidide, acetoacet-p-phenetidide, acetoacet-p-anisidide, and acetoacet-4-chloro-2,5- dimethoxyanilide. Preferably, the separating of step (b) is performed using a centrifuge. Numerous other separation methods are known to those skilled in the art, including: filter pressing, belt filtering, decanting, and nutsche filtering. In a preferred embodiment, the adding of step (c) comprises adding the acetoacetarylide solid step-wise to a homogenizer. Preferably, the homogenizer of step (c) is an in-line homogenizer or a batch homogenizer. In one preferred embodiment, the additives used to homogenize the acetoacetarylide in step (d) are suspension additives (dispersants). In a more preferred embodiment, one or more of the additives used to homogenize the acetoacetarylide is an N-alkyl amine oxide. In another preferred embodiment, one or more of the additives is a surfactant to control the particle size and/or flowability of the pigment. In another embodiment, one or more of the additives alter the color or consistency of the pigment, such as to achieve customer specified properties. In one embodiment, the acetoacetarylide slurry formed in the above process is heterogeneous. In a preferred embodiment, the concentration of the acetoacetarylide slurry formed after homogenization is between 30 and 40 weight %. In step (e), preferably a slurry pump capable of moving high solid content slurries without applying significant shear to the material is used to pump the acetoacetarylide slurry to a reaction tank. The percentage acetoacetarylide solid concentration can be monitored using a mass flow meter or a flow cell capable of measuring density or viscosity. In step (f), an alkali or alkaline earth metal base is added to the acetoacetarylide slurry. In a preferred embodiment, the base is added via a dip tube. A preferred base is sodium hydroxide. Other suitable bases include, but are not limited to, potassium hydroxide and lithium hydroxide. Buffering agents (e. g. sodium acetate-acetic acid) can also be used. In step (g), an acid is added to form a precipitate of the acetoacetarylide. In a preferred embodiment, the acid is added via a dip tube. A preferred acid is acetic acid. In another embodiment, the acid used to form a precipitate of the acetoacetarylide is formic acid or oxalic acid. In step (h), the precipitate is reacted with a diazonium salt, i. e., a diazotized amine, thereby forming an azo pigment. Several examples of diazonium salts that can be used to form a pigment include: diazotized dichlorobenzidine, o-dianisidine (3,3'-dimethoxy-l,l'-biphenyl-4,4'-diamine), o-ditoluidine, -chloro-o-nitroaniline, and/. -nitro-o-methoxyaniline. One skilled in the art would recognize that numerous other diazotized aromatic amines can be used. See e. g. US-A-4 254 025 and US-A-5 869 625. This invention also includes the pigments and intermediates thereto formed by the above processes. Numerous diketenes and amines can be reacted in step (a) to form an acetoacetarylide as exemplified below. Amine Diketene Acetoacetarylide Acetoacetarylide slurries that may be formed include: acetoacetanilide, acetoacet-o- toluidide, acetoacet-p-toluidide, acetoacet-o-anisidide, acetoacet-τn-xylidide, acetoacet-p- phenetidide, acetoacet-p-anisidide, and acetoacet-4-chloro-2,5-dimethoxyanilide. In the above scheme: • for an acetoacetanilide, R, R', and R" are hydrogen; • for an acetoacet-o-toluidide, R is methyl and R' and R"are hydrogen; • for an acetoacet-/?-toluidide, R and R" are hydrogen and R' is methyl; • for an acetoacet-o-anisidide, R is a methoxy and R' and R" are hydrogen; • for an acetoacet-^-anisidide, R and R" are hydrogen and R' is methoxy; • for an acetoacet-p-phenetidide, R and R" are hydrogen and R' is ethoxy; • for an acetoacet-m -xylidide, R and R' are methyl and R" is hydrogen; and • for an acetoacet-4-chloro-2,5-dimethoxyanilide, R and R" are methoxy and R' is chlorine. The following examples are intended to illustrate the invention but not to limit its scope. One skilled in the art would recognize numerous other embodiments of the invention. Example 1 Homogenizing an Acetoacetarylide to Prepare an Acetoacetarylide Slurry (General Procedure) 1. Thoroughly clean a 11,350 1 (3,000 gallon), 316 stainless steel reactor (Pfaudler, New York) with acetone and water washes. Preferable, the inside of the reactor is at atmospheric pressure - a vacuum is to be avoided under all circumstances. (A nitrogen pad is not required.) 2. Set cooling jacket of reactor to maintain product inside reactor at 25 °C. 3. Charge water to the reactor and start agitation at 50% of full scale. The amount of water charged should be 1,134 kg (2,500 lbs). 4. Open bottom valve of the reactor and start in-line mixer at 10% of full scale. 5. Add acetoacetarylide solids (addition #1) from drums through the solid addition chute of the reactor. Introduce about 25% (181 kg (400 lbs)) of the total charge of acetoacetarylide (726 kg (1600 lbs) on a 100% basis) through the solids addition chute (addition #1). Increase the in-line mixer speed to provide circulation of the material back into the reactor. 6. Once the material appears homogeneous, add the next 25% of acetoacetarylide (addition #2). Increase the in-line mixer and agitator speed. The temperature is maintained at 25 °C. 7. For additions three and four of acetoacetarylide, proceed as in step 5. Visually verify the mixture is homogeneous through the sight glass and that material is recirculating back through the in-line mixer to the reactor. 8. Slowly add between 0.15% and 2.5% of a surfactant (i.e. Barlox 121 = isononyl dimethyl amine oxide, available from Lonza Inc., Mapleton, IL, USA). (The amount will depend on the behavior of the material once sampled.) Prior and during the addition of the surfactant, agitation and in-line mixer speeds are immediately reduced to minimize foaming and cavitation of the mixer. 9. Allow the material to agitate and mix for two hours and then sample. The measurement of either the density or the viscosity is used to determine % solids. This number can be compared to a calibrated viscosity or density versus % solids curve to determine the % solids for the slurry. Example 2 Homogenization of an Acetoacetanilide to Prepare an Acetoacetanilide Slurry This example uses acetoacetanilide (AAA)-dry material, water, and a mixture of several N-alkyl amine oxide additives in water and a homogenizer to prepare a slurry of 30— 40 weight% concentration AAA (100% basis). In this process, water is added to the reactor and then the homogenizer (either in line or batch) is started with a low rpm setting. If the in-line homogenizer is used, then the reactor agitator is also started at its average speed. The dry AAA is added at a rate to permit the resulting slurry to mix well and also not to overload the mixing capability of the reactor and the homogenizer. During the addition of AAA, the homogenizer speed is increased for additional mixing. Once all the solid has been added, the additives are poured into the reactor. Vacuum suction of this material into the reactor may cause foaming to occur. As the additives are introduced into the reactor, the homogenizer speed can be reduced as the material is no longer thick: it becomes more fluid in nature. A combination of the homogenizer plus agitator in the reactor (if homogenizer is in-line) is used to keep material moving until it is transferred to a drum, tote, tank truck, iso container or railcar. Similar reaction conditions can be used to prepare slurries of acetoacet-o-toluidide, acetoacet-p-toluidide, acetoacet-o-anisidide, acetoacet-m-xylidide, acetoacet-p- phenetidide, acetoacet-p-anisidide, and acetoacet-4-chloro-2,5-dimethoxyanilide. Example 3 Synthesis of Pigment Yellow 12 Using Diketene and Amine Starting Materials Diketene and aniline in an approximately stoichiometric ratio are charged to a reactor containing a solvent blend ((diketene + aniline)/solvent ratio is 0.25) at 25 °C at atmospheric pressure. The reaction is exothermic and the temperature continues to rise to approximately 60 °C whereupon the reactor jacket is set to full cool to bring the temperature back to 25 °C in the reactor. During the cooling process, acetoacetanilide (AAA) crystallizes and falls out of solution and a mixture of AAA and solvent blend is made. This mixture, once cooled, is filtered, where the AAA is removed from the solvent and washed to remove impurities. The centrifuged AAA is analyzed for moisture content. The reactor (equipped with a high shear mixer on a recirculation line or as part of the agitator-batch mixer) for the slurry preparation is filled with water (1,134 kg (2500 lbs)). The reactor jacket is set so that the material inside the reactor remains at 25 °C and the agitator is set at 50% of full scale with the pressure on the reactor at atmospheric (no vacuum, no nitrogen). The filtered AAA is added in four portions, after each portion the rpms to the homogenizer (either in line or batch) is increased so that the material is fluid. After the fourth addition, the rpm should be at a maximum. The surfactant(s) are added slowly while decreasing the speed of the mixer to ! scale. After 2 hours, the homogenizer is stopped and the agitator is allowed to mix the slurry in the tank. Using a slurry pump to minimize shear and move the high % solids, this material is transferred to a shipping container (drums, totes, or tank trucks). A mass flowmeter or a scale can also be used to determine the amount of slurry transferred. The material is then shipped to a customer site where it is transferred into an agitated storage tank. From this storage tank the material is transferred via a slurry pump into the coupling storage tank where 50% caustic is added to dissolve the mixture. Ice is added to control the dissolution to a desired temperature. Once dissolution is complete, acetic acid (70%) is added to reprecipitate the arylide. This reprecipitated arylide is then pumped to a strike tank where it is mixed with diazotized dichlorobenzidine. The resulting mixture contains the pigment yellow 12 which is then finished according to the desired application.

Claims: Claims: 1. A process for forming an acetoacetarylide slurry, comprising: (a) adding a solid acetoacetarylide to a homogenizer; (b) homogenizing the acetoacetarylide in the presence of water and one or more additives to form an acetoacetarylide slurry. 2. A process as claimed in claim 1, wherein one or more of the additives of step (b) is a N-alkyl amine oxide. 3. An aqueous acetoacetarylide slurry, obtainable by the process of claim 1 or 2. 4. A process for forming an acetoacetarylide-based pigment, comprising: (a) homogenizing a mixture of an acetoacetarylide and one or more additives, thereby forming a slurry of the acetoacetarylide; and (b) reacting the slurry to form an acetoacetarylide-based pigment. 5. A process as claimed in claim 4, wherein the mixture of step (a) was formed by: (i) adding an acetoacetarylide solid to a homogenizer containing water; and (ii) adding one or more suspension additives. 6. A process as claimed in claim 4 or 5, wherein the reacting of step (b) comprises: (i) adding an alkali or alkaline earth metal base to the slurry; (ii) adding an acid to form a precipitate of the acetoacetarylide; and (iii) reacting the precipitate with a diazonium salt, thereby forming an azo pigment. 7. A process as claimed in claim 6, wherein the base is sodium hydroxide. 8. A process as claimed in claim 6 or 7, wherein the acid is acetic acid. 9. A process as claimed in any of claims 4 to 8, wherein one or more of the additives alters the color or consistency of the pigment. 10. A process as claimed in any of claims 4 to 9, wherein one or more of the additives is a surfactant to control the particle size and/or flowability of the pigment. 11. A process as claimed in any of claims 4 to 10, wherein one or more of the additives is an N-alkyl amine oxide. 12. A process as claimed in any of claims 4 to 11, wherein the concentration of the slurry is between 30 and 40 weight %. 13. A process as claimed in any of claims 4 to 12, wherein the slurry has a consistency suitable for pumping. 14. A process as claimed in any of claims 4 to 13, wherein the acetoacetarylide of step (a) is selected from the group consisting of acetoacetanilide, acetoacet-o-toluidide, acetoacet-p-toluidide, acetoacet-o-anisidide, acetoacet-m-xylidide, acetoacet-p- phenetidide, acetoacet- ? -anisidide and acetoacet-4-chloro-2,5-dimethoxyanilide. 15. A process for forming an acetoacetarylide-based pigment, comprising: (a) reacting a diketene with an amine to form an acetoacetarylide slurry; (b) separating the acetoacetarylide as a solid from the acetoacetarylide slurry; (c) adding the acetoacetarylide solid to a homogenizer; (d) homogenizing the acetoacetarylide in the presence of water and one or more additives to form an acetoacetarylide slurry; (e) pumping the acetoacetarylide slurry to a reaction tank; (f) adding an alkali or alkaline earth metal base to the acetoacetarylide slurry; (g) adding an acid to form a precipitate of the acetoacetarylide; and (h) reacting the precipitate with a diazonium salt, thereby forming an azo pigment. 16. A process as claimed in claim 15, wherein the acetoacetarylide of step (a) is selected from the group consisting of acetoacetanilide, acetoacet-o-toluidide, acetoacet-p- toluidide, acetoacet-o-anisidide, acetoacet-m-xylidide, acetoacet-p-phenetidide, acetoacet-p-anisidide and acetoacet-4-chloro-2,5-dimethoxyanilide. 17. A process as claimed in claim 15 or 16, wherein the separating of step (b) is performed using a centrifuge. 18. A process as claimed in any of claims 15 to 17, wherein the adding of step (c) comprises adding the acetoacetarylide solid step-wise to a homogenizer. 19. A process as claimed in any of claims 15 to 18, wherein the homogenizer of step (c) is an in-line homogenizer or a batch homogenizer. 20. A process as claimed in any of claims 15 to 19, wherein one or more of the additives of step (d) is a suspension additive. 21. A process as claimed in any of claims 15 to 20, wherein one or more of the additives of step (d) is a N-alkyl amine oxide. 22. A process as claimed in any of claims 15 to 21, wherein the concentration of the acetoacetarylide slurry formed in step (d) is between 30 and 40 weight%. 23. A process as claimed in any of claims 15 to 22, wherein the base of step (f) is sodium hydroxide. 24. A process as claimed in any of claims 15 to 23, wherein the acid of step (g) is acetic acid. 25. The product formed by the process of claim 21.

Inventors: MCCORMICK JAMES MICHAEL, ROSAS REBECCA LEE, MCCORMICK, JAMES, MICHAEL, ROSAS, REBECCA, LEE
Applicants: LONZA AG, MCCORMICK JAMES MICHAEL, ROSAS REBECCA LEE, MCCORMICK, JAMES, MICHAEL, ROSAS, REBECCA, LEE
Application year: 2000
Main classification: C09B41
IPC codes: B41M5, C07C235, C09B41, C09B69, D06P5