MXPA96006748A - Production of pigmen - Google Patents

Abstract

The present invention relates to a process for converting a crude non-pigment form of an organic pigment into a pigment form, which comprises: a) kneading the non-pigmentary form of an organic pigment in the presence of a liquid carboxylic acid that is tender to carbon atoms and optionally an organic or inorganic salt, b) separating the pigment produced from step (a) of the liquid carboxylic acid and the organic or inorganic salt option

Description

PRODUCTION OF PIGMENTS The present invention relates to a process for converting a crude pigment into a pigment form. Numerous methods are known for reducing the size of the particles of a crude pigment to a desired pigmentary size. These methods include salt grinding, ball milling, and kneading. GB Patent No. 1 38921 discloses a kneading process using a continuous kneading apparatus having at least two separate elements for adding a liquid. Suitable liquids for this process include phenol, aniline, but particularly polyhydric aliphatic alcohols such as glycols. The temperatures used are between 120 ° C and 350 ° C, preferably between 160 ° C and 280 ° C. We have now discovered, in a surprising way, that if certain carboxylic acids are used as the liquid in a continuous kneading apparatus, The process can be operated at lower temperatures, and it is not necessary to have at least two inputs for the liquid. In addition, the acid can be easily recovered and reused. The acid can be recovered by chemical means or by other methods, such as steam distiller. In some cases, the resulting product has a better concentration of color and gloss. According to the above. the present invention-. provides a process for converting a crude pigment into a pigment form, which comprises kneading the crude pigment in the presence of a liquid carboxylic acid, and optionally a salt. "Crude pigment" means pigments obtained from the synthesis in a highly aggregated state with a particle size not suitable for use as a pigment, or a pigment that has been ground to produce a product that is also added, and that has a particle size distribution wider than that obtained from the synthesis, but still unsuitable for use as a pigment. The mixer can be a batch kneader or a continuous kneader, which can be a double screw or four screw kneader, or a single screw kneader, which can perform oscillating movements. Preferably a twin screw extruder is used. When the kneader is a continuous kneader, it can have a length to diameter ratio of 10: 1 to 50: 1, preferably 20: 1 to 40: 1. It can have from 1 to 20 kneading areas, preferably from 5 to 10 kneading areas. The carboxylic acid must be liquid at the oxidizing temperature. Preferred is a liquid aliphatic carboxylic acid having from 4 to 20 carbon atoms, and more preferably, one having from 6 to 20 carbon atoms. Examples of suitable carboxylic acids include 2-ethylhexanoic acid, oleic acid. caproic acid, valeric acid, or enanthic acid. The operating temperature can be from 20 ° C up to the boiling point of the acid, preferably from 80 ° C to 120 ° C. The temperature can be controlled by a water jacket on the mixer. The water circulating through the water jacket can be cooled at low temperatures by passing it through a cooler. The carboxylic acid can be added to the mixer at one or more points along its length, but preferably through an inlet at the beginning of the screw, before the first kneading zone. The mixer can be one that puts the pigment and salt at a shear rate of 300 to 20,000 sec. preferably from 500 to 5,000 sec, for a period of 10 seconds to 15 minutes, preferably from 20 seconds to 6 minutes, in a kneading apparatus that operates continuously, the amount of liquid being selected in such a way that the energy consumed by its Kneading is from 0.2 to 15 Wh / kg of processed pigment, preferably between 0.4 and 8 kWh / kg. Examples of suitable inorganic and organic salts are sodium chloride, potassium chloride, sodium sulfate, zinc chloride, calcium carbonate, sodium format, sodium acetate, potassium sodium tartrate, calcium acetate, sodium citrate, calcium chloride, or mixtures thereof. The salt used must be selected in such a way that it does not react with the acid that is being used and forms a precipitate. The salt may have a particle size of 1 to 100 microns, preferably 10 to 50 microns, measured using a Malvern particle size analyzer "Mastersizer X" (with dry powder feed capable of measuring up to 2 millimeters). The amount of salt, if used, can be from 0.1 to parts by weight by pigment. The process of the invention is applicable to a wide variety of pigments that are subjected to a milling process as part of the finishing process. Examples of these pigments include phthalocyanines, such as copper, zinc, or nickel phthalocyanines, partially halogenated phthalocyanines, quinacridones, dioxazines, diketopyrrolopyrroles, and perylenes. After use, the carboxylic acid can be recovered by adding water and an alkali to the kneaded dough to convert the acid into a salt that is soluble. The pigment can then be filtered, and the filtrate can be acidified to release the free acid, which can then be recovered and reused. The pigments can be treated with pigment additives during or after kneading. Suitable additives include natural or synthetic resins, coloring materials, and especially in the case of phthalocyanine pigments, amine salts of phthalocyanine sulfonic acids.

The invention is illustrated by the following examples.

Example 1 A MP2030 twin-screw extruder of APv Newcastle-U-Lyme, United Kingdom, is fed with 2.09 kghr-1 of a crude copper phthalocyanine (CuPc) and 8.78 kghr-1 of NaCl. 1.63 kghr of 2-ethylhexanoic acid (2EHA) is fed through a single hole at the beginning of the screw. The ratio of 2-ethylhexanoic acid to the copper salt / phthalocyanine mixture is 15 percent. The resulting torque observed is 49 percent (3.68KW). The specific energy generated is 1.76 Kg CuPc. The shear force gradient is 1675 s. The screw is cooled over its entire length with water at 15 ° C. The dough is extruded from the screw at 100-110 ° C while the temperature in the kneading areas is between 20 ° C and 110 ° C. Add 200 grams of the kneaded dough to 400 grams of water. To the kneaded dough and water, add 12.33 grams of NaOH (40 percent) and 2.43 grams of NHOH (33 percent), and the mixture is stirred for 1 hour at 70 ° C. The mixture is filtered , and the mother liquor and the first 100 milliliters of the wash are collected before the press cake is washed to get rid of salt, with hot water. The press cake is dried in a circulating oven at 70-80 ° C. To the mother liquor and to the first 100 milliliters of washing, they are added 19.69 grams of concentrated HC1 (35.6 percent) in order to re-precipitate the 2-ethylhexanoic acid, which is separated from the aqueous layer using a gravity separation funnel. The recovered 2-ethylhexanoic acid can be reused for reducing the size of more crude CuPc in an extruder. The resulting pigment is in the ß modification, and shows excellent concentration, gloss, flow, and dispersion properties when incorporated into an ink oil vehicle.

Example 2 A Cu.sub.c. pigment is produced according to the method of Example 1. 200 grams of the kneaded dough are added to 440 grams of water. To the kneaded dough and water, add 12.33 grams of NaOH (47 percent) and 2.43 grams of NH ^ H (33 percent), and the mixture is stirred for 30 minutes at 70 ° C. At this point, 2.75 grams of copper dodecyl dodecyl amide salt of copper phthalocyanine, which have previously been dispersed in 100 grams of water for 15 minutes using a Silverson dispersion apparatus at 4000 rpm, are added to the mass dispersion. knead, and the mixture is continued for another hour at 70 ° C. The paste is filtered, and the mother liquor and the first 100 grams of the water wash are recovered and filtered before washing to liberate from the salt. The press cake e-forms again in a paste in 500 grams of water and 10 grams of HC1 (36 percent) at 70 ° C for 1 hour before filtering and washing to liberate from the salt. Then the press cake is dried in a circulating air oven at 70 ° C overnight. The 2-ethylhexanoic acid used to knead the pigment is recovered according to the procedure described in Example 1. The pigment shows excellent concentration, gloss, and dispersibility properties in a liquid ink varnish.

Example 3 A pigment is prepared in the manner of Example 1, except that 0.03 Kghr of polymerized rosin (trade name SYLVATAC 95), 2.01 Kghr-1 of CuPc, 8.46 Kghr-1 of NaCl, and 2.00 Kghr-1 are supplied to the extruder. of 2-ethylhexanoic acid. The pigment and the solvent are recovered according to the process described in Example 1. The resulting blue pigment shows excellent concentration, gloss, and dispersibility properties in oil inks.

EXAMPLE 4 A pigment is prepared in the manner of Example 1, except that after the washing step, the press cake is reformed into a paste in 500 grams of water using a paddle stirrer. The potassium salt of a polymerized rosin (trade name SYLVATAC 95) (2 percent by mass of the pigment) is added to the paste, with the subsequent addition of HC1 to precipitate the resin on the surface of the pigment. After filtration and washing, the pigment is dried at 70 ° C overnight in a circulating air oven. The resulting blue pigment shows excellent concentration, gloss, and dispersibility properties in oil inks.

Example 5 A CuPc pigment is prepared as in Example 1, except that the kneading solvent used is oleic acid. The oleic acid is recovered in a manner identical to the 2-ethylhexanoic acid of Example 1. The resulting pigment is in the β-modification, and exhibits excellent concentration, gloss, flow, and dispersion properties, when incorporated in an oil ink vehicle. .

Example 6 A crude dioxazine violet is converted to a pigment form using NaCl and 2-ethylhexanoic acid as in Example 1. The final pigment shows excellent concentration and purity properties when incorporated into an oil ink vehicle.

EXAMPLE 7 Chlorinated crude copper phthalocyanine is converted to a pigment form using NaCl and 2-ethylhexanoic acid as in Example 1. The final pigment shows excellent concentration, gloss, and purity properties when incorporated into an oil ink vehicle .

EXAMPLE 8 A CuPc pigment is prepared as in Example 1, except that the kneaded salt is KCl.The resulting pigment is in the β-modification, and exhibits excellent properties of concentration, brightness, flux, and dispersion, when incorporated into a oil ink vehicle.

Example 9 8 kilograms of crude CuPc and 1 kilogram of NaCl are milled in a ball mill for 5 hours. This mixture is then adjusted in such a way that the ratio of CuPc to NaCl is 1: 4.2. This mixture is then supplied to a twin screw extruder as in Example 1. Employing an identical recovery procedure, the finished pigment exhibits excellent concentration, gloss, and flow properties upon incorporation into an oil ink vehicle.

Example 10 250 grams of crude copper phthalocyanine are placed in a batch kneading apparatus (Winkworth 2Z, "Z" blade mixer, equipped with water cooling and 0.37 kw motor), together with 224 grams of 2-ethylhexanoic acid, and they mix well. After the sequential addition of 1.215 grams of NaCl, the mixture is kneaded for 6 hours at 100 ° C (+ 10 ° C), generating a specific energy of 2.2 KwHr kg "1. The kneaded mass is collected in 3716 grams of To the kneaded dough and water are added 119 grams of NaOH (47 percent) and 10 grams of NH4OH (33 percent), and the mixture is stirred for 1 hour at 70 ° C. The mixture is filtered, and the mother liquor and the first 800 milliliters of washing, are collected before the press cake is washed to get rid of salt with hot water.The press cake is dried in a circulating air oven at 70-80 °. C. To the mother liquor and to the first 800 milliliters of the washing, they are added 165 grams of HC1 (35.6 percent) in order to re-precipitate the 2-ethylhexanoic acid, which is separated from the aqueous layer using a funnel. gravity separation The resulting pigment is in the β modification, and shows excellent concentration properties n, gloss and flow dispersion when incorporated into an oil ink vehicle.

Example 11 8 grams of crude CuPc are milled in a ball mill for 5 hours. This material is then supplied to a twin-screw extruder of 2.0 kghr "1. Simultaneously 3.0 kghr" 1 of 2-ethylhexanoic acid is fed into a single hole at the beginning of the screw. The resulting torque observed is 63 percent (4.73 KW). The resulting pigment material is isolated from the carboxylic acid, and exhibits excellent concentration, gloss, and flux properties, and dispersibility upon incorporation into an oil ink vehicle.

Claims (13)

1. A process for converting a crude pigment into a pigment form, which comprises kneading the crude pigment in the presence of a liquid carboxylic acid, and optionally a salt.

2. A process as claimed in claim 1, wherein the carboxylic acid is one having from 4 to 20 carbon atoms.

3. A process as claimed in claim 2, wherein the carboxylic acid is 2-ethylhexapoic acid, oleic acid, caproic acid, valeric acid, or enanthic acid.

4. A process as claimed in any of the preceding claims, which is carried out at a temperature of 20 ° C up to the boiling point of the acid.

5. A process as claimed in any of the preceding claims, which is carried out at a temperature of 80 ° C to 120 ° C.

6. A process as claimed in any of the preceding claims, wherein the mixer is a mixer by batch or continuous mixer.

7. A process as claimed in claim 6, wherein a twin screw extruder is used.

8. A process as claimed in any of the preceding claims, wherein the acid is introduced into the kneader through an inlet at the beginning of the screw.

9. A process as claimed in any of the preceding claims, wherein the acid is recovered after use and recycled.

10. A process as claimed in any of the preceding claims, wherein a salt is present, and the amount of salt is 0.1 to 20 parts by weight of pigment.

11. A process as claimed in any of the preceding claims, wherein the pigment is a phthalocyanine, a partially halogenated phthalocyanine, a quinacridone, a dioxazine, a diketopyrrolopyrrole, or a perylene.

12. A process as claimed in any of the preceding claims, wherein the pigment is treated with a pigment additive during or after kneading.

13. A process as claimed in claim 12, wherein the pigment is a phthalocyanine, and the pigment additive is an amine salt of a phthalocyanine sulfonic acid.