CH642388A5 - METHOD FOR REFINING A CHINACRIDONE PIGMENT. - Google Patents

Description

The invention relates to a process for converting pre-ground y-quinacridone into the pigment form and in particular to a process in which pre-ground y-quinacridone is mixed with an aqueous, anionic, surface-active agent or surfactant or a combination of an anionic and non-ionic, surface-active agent or Surfactant is brought into contact at elevated temperature.

It is known to the person skilled in the art that quinacridones derived directly from synthesis, which are known as crude quinacridones, are unsuitable for many pigment applications and must be processed further in order to develop suitable pigment properties, e.g. Particle sizes, strength, phase etc. One of the most common processes for converting crude quinacridone into the pigment form is to grind the crude quinacridone with large amounts of inorganic salt and then to extract the resulting quinacridone with acid. Although the salt grinding process can lead to a satisfactory pigment, the total volume of grinding media or grinding elements and salt is so large that only a small amount of pigment can be ground per batch. In addition, the removal of large amounts of saline from the extraction stage poses potential pollution problems and adds significantly to the cost of manufacturing the pigment.

Attempts to avoid the use of salt in the premilling of crude quinacridone have been described, for example, in U.S. Patents 2857400 and 3017414, where crude quinacridone is ground without salt and the ground quinacridone with an organic liquid or an acidic, aqueous slurry is brought into contact with an organic liquid. The organic liquid is removed and the resulting quinacridone pigment is isolated in a conventional manner. The amounts of organic liquid used in these processes are generally at least 30% by weight based on the weight of the quinacridone to be processed and, like the salt, can lead to costly waste disposal problems.

Another approach, the need to avoid salt in the pre-grinding of crude quinacridone and to eliminate the use of organic liquids, is described in US Pat. No. 4,094,699. This process is directed to converting crude quinacridone to the pigment form by contacting the quinacridone that has been milled with an aqueous alkaline medium in the presence of a cationic or non-ionic surfactant.

Another method for producing pigmentary quinacridone from crude quinacridone, as described in US Pat. No. 3,287,147, is to heat a neutral, aqueous paste of quinacridones under pressure to temperatures of 150 to 300.degree. The quinacridones treated in this way can originate from the salt grinding of crude quinacridones or from the acidic paste formation of raw quinacridones. In any case, special equipment is required to withstand the high temperatures and pressures that are required.

The invention provides a process for converting crude y-quinacridone to pigment form without the need for large amounts of salt during milling, organic liquids and excessively high temperatures and pressures.

The invention is described in more detail below.

According to the invention, a method for converting crude y-quinacridone into the pigment form is provided by contacting ground quinacridone with an aqueous, anionic or a combination of anionic

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see and non-ionic, surface-active agents or surfactants at a temperature of at least 40 ° C. The process according to the invention leads to the production of a pigment which has a superior heat resistance in vinyl plastics in comparison with pigments which have been produced by processes involving cationic surface-active agents, as described in US Pat. No. 4,094,699. The process according to the invention leads to very reproducible coloring properties. The method according to the invention avoids the use of an organic liquid, and thus also avoids the problems which result therefrom, such as flammability and toxicity.

Accordingly, the invention relates to a process for converting crude y-quinacridone into the pigment form, which consists in dry grinding the crude y-quinacridone in the presence of 10-15% by weight of alum, based on the raw product until the 6.5 ° (20) X-ray diffraction line shows a broadening to 0.40 to 0.95 ° at half-maximum intensity, contact of the ground China-20 cridon with an aqueous, anionic, surface-active agent or surfactant , or a mixed anionic-non-ionic surface-active agent or surfactant, wherein at least 50% of the surface-active agent or surfactant is anionic, at a temperature of at least 40 ° C., 25 wherein the surface-active agent or surfactant, based on the milled quinacridone, 1-20 wt .-% is present and separating the resulting pigment-shaped quinacridone.

For the purposes of the present invention, the term “pre-ground” or “pre-ground” quinacridone used below is intended to encompass crude quinacridone which has been dry-ground using inert grinding media or grinding elements such as rods, spheres etc., with or without grinding aids , such as salts and surfactant 35 or surfactant. For example, pre-ground quinacridone means a quinacridone that was ground before the treatment. The conditions which can be used to carry out the preliminary grinding are familiar to the person skilled in the art or are customary. For example, for the preferred implementation of the invention, a mill feed that is essentially used for ball milling processes is used. The feed of the grinding elements or grinding media usually takes up about half the volume of the mill, and the raw quinacridone to be ground takes up considerably more than the vacancies 45 between these elements, so that the total feed into the mill is in the range of 60-65 % of the total volume of the mill. Milling media or milling elements that are used most frequently are, for example, steel rods, balls and nails. The grinding time depends on the particle size of the raw quinacridone to be ground, the feed to the mill and the type of mill used.

It is known to a person skilled in the field of pigment processing that the grinding time alone is not sufficient to define the degree of comminution of pigment particles. This can be influenced by various process parameters which influence the effectiveness of the grinding, such as the grinding speed, the loading / Pigment ratio, feed density, composition, shape, etc. 60

The course of the reduction in the particle size can expediently be followed by measuring the broadening of the X-ray diffraction of a suitably selected individual X-ray diffraction line. The mean dimension D of the crystallites in the milled powder is related to the pure X-ray diffraction broadening ß by the Scherrer equation in which K represents a proportionality constant,% the wavelength of the X-rays used, ß the width of the Represents the diffraction line after the correction for instrumental effects and 0 indicates the angle of the diffraction between the original X-ray beam and the diffraction plane of the crystal to be measured.

This equation is discussed in X-ray Diffraction Procédures, H.P. Klug and L.E. Alexander, John Wiley & Sons, New York, N.Y. 1974, chapter 9.

In practice, ß does not have to be determined, but an experimentally determined width B is obtained by simply measuring the width in degrees at half-maximum intensity of the chosen diffraction line. In the case of y-quinacridone, the width of the X-ray diffraction line at 6.5 (20) can be followed as a measure of the particle dimension. Prolonged grinding times result in higher values of B, which is a convenient way to track the progress of grinding regardless of the grinding method and is characteristic of the particles themselves. In the examples listed below, the starting raw material B has values of approximately 0.25-0.30 ° and the final ground values are typically 0.60-0.95 °. The following X-ray device was used: X-ray generator: Norelco, Cat. No. 12010100, 60 kvp-50 ma, X-ray tube or X-ray tube: Norelco, Cu (type 14000300), serial no. 31921. Data measurement system: DMS-30 1-C.

A pigment which is important for commercial purposes can be obtained by the process according to the invention from pre-ground y-quinacridone with a B value of 0.40-0.95 °. It has been found that when a ground y-quinacridone pigment with a B value in the lower part of the above range comes into contact with the aqueous surface-active medium according to the invention, a red pigment with a strong blue tone with a high coloring power is obtained. If ground y-quinacridone pigment with a B value in the higher portion of the above range is brought into contact with the aqueous medium according to the invention, a red with a more yellowish hue with a greater transparency of the full tone is obtained. B values below 0.40 ° are suitable, but not as blue. B values above 0.95 ° are suitable in the same way, but they tend to yellow and are weaker.

In the method according to the invention, no alum has to be present during grinding. However, in order to increase the energy required to ignite the ground powder, some alum is preferably used. The preferred amount of alum is 10-50% by weight, based on the crude quinacridone. Larger amounts can be used, but they are not advantageous. With amounts of 0-10% by weight alum, precautionary measures should be taken to avoid potential dust explosions.

In addition, further control of the pigment properties is possible by adjusting the ratio of anionic / non-ionic, surface-active agents or surfactants. Generally, a higher percentage of anionic surfactant than nonionic will result in a bluer product. Therefore, a preferred combination for grinding, which leads to a strong blue-tone red pigment, is to ground to a B value of 0.60-0.70 ° and then to bring it into contact with an aqueous medium, the 75-100 % contains anionic surfactant and 0-25% non-ionic surfactant. A preferred prer

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Grinding combination that leads to a yellow pigment is to grind to a B value of 0.80-0.95 ° and then to bring it into contact with an aqueous medium containing 50-75% anionic surfactant and 25- Contains 50% non-ionic.

In general, the grinding time varies very much. In most cases the grinding time varies from 2-50 hours, preferably 3-16 hours and particularly preferably 4-13 hours, provided that the phase purity is achieved and the particle size reduction is not carried out to an extreme value.

The term "quinacridone" used here is intended to mean the y-form of unsubstituted, linear quinacridone of the formula.

The pre-ground quinacridone is brought into contact with an aqueous solution of an anionic or anionic / non-ionic, surface-active agent or surfactant. The contact can be made in any convenient manner. For example, the pre-ground quinacridone can be added to the aqueous solution with stirring, or the solution can be added to the pre-ground quinacridone, or the surfactant may be present in the quinacridone during milling, in which case the ground quinacridone is or may be added to water the surfactant is partially present in the quinacridone during milling, and the remainder of the surfactant in aqueous solution is then added to the quinacridone. The amount of aqueous solution used to contact the pre-ground quinacridone should be sufficient to allow intimate contact with all of the quinacridone. In general, the weight of the aqueous solution should preferably be at least ten times the weight of the pre-ground quinacridone to ensure complete intimate contact.

Representative examples of anionic surface-active agents or surfactants according to the invention include salts of sulfate esters of long-chain, aliphatic alcohols, such as sodium lauryl sulfate; "Aerosol O.T.", a sodium salt of sulfosuccinate dioctyl ester; 5-6 membered cycloparaffinic acids such as naphthenic acid; "Dresi-nate X", a sodium salt of wood resin acid or wood rosin acid, which in principle is tetra-hydroabietic acid; Salts of dodecylbenzenesulfonic acid such as isopropylammonium dodecylbenzenesulfonate. The preferred anionic surfactants or surfactants are the amine salts of dodecylbenzenesulfonic acid. Most preferred is isopropylammonium dodecylbenzenesulfonate.

Representative examples of non-ionic surfactants according to the invention include "Pluronic P-94, a complex of poly (oxyethylene) / poly (oxypropylene) with an average or average molecular weight of 4600 and alkylphenoxypoly- (ethoxy ) - ethanols, such as nonylphenoxypolyethoxyethanols and octylphenoxypolyethoxyethanols. The preferred nonionic surfactants are

Alkylphenoxypoly-ethoxyethanols. The most preferred are octylphenoxypolyethoxyethanols and nonylphenoxypolyethoxyethanols. The most expedient is the use of "Igepal CO 630", which is nonylphenol polyethoxyethanol with a molecular weight of about 630 and "Triton X-100", which is octylphenoxypolyethoxyethanol with a molecular weight of about 630.

The amount of the surfactant which is generally used is 1-20% by weight, preferably 6-12% by weight, based on the weight of the pre-ground quinacridone. If combinations of anionic and non-ionic surfactants are used, the amount of anionic is generally 50% by weight or more, based on the combination. In the process according to the invention, the surface-active agent is generally at least 50% by weight anionic, the remainder 0-50% by weight being nonionic. When the surface active agent content exceeds 20% by weight, foaming and filtering difficulties arise in the process. If the content is less than 1% by weight, there is insufficient surfactant to destroy agglomerates and to disperse the pigments.

The concentration of surfactant in water can vary widely and is only limited by considerations regarding foaming and filtering difficulties. In general, it is convenient to use a surfactant and water concentration of 0.5-2 wt% surfactant.

After contact of the pre-ground quinacridone with the aqueous surfactant, the resulting slurry is brought to a temperature of at least 40 ° C, generally from 40 ° C to below the boiling point, and preferably from 80-90 ° C. The aqueous surfactant may optionally be heated to the desired temperature before contact to reduce or eliminate the heating time after contact with the pre-ground quinacridone. Higher temperatures are not necessary and boiling of the slurry should be avoided for safety reasons. The duration of the temperature contact can vary depending on the particular pre-ground quinacridone to be treated and the desired crystal growth, but is generally 30 minutes to 10 hours and preferably 1-2 hours.

When contact with the aqueous surfactant is complete, the slurry is acidified. Since the pre-ground quinacridone has generally been milled using iron or steel milling media or elements, iron filings are usually present in the pre-ground quinacridone. The usual practice is to add enough acid to the slurry to provide 0.5-2% by weight acid, calculated as sulfuric acid and based on the weight of the slurry. The quinacridone can come into contact with the surfactant under acidic neutral or basic conditions. If contact with the surfactants is carried out under acidic conditions, further acidification is not required. If the contact with the surfactant has been carried out under neutral or basic conditions, acidification is required to achieve the above acidity. The acidified slurry is held at a temperature of at least 85 ° C for 30 minutes to 2 hours to ensure dissolution of any iron that may be present.

The quinacridone pigment produced according to the invention can be subjected to various further treatments

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depending on the end purpose and the desired special properties. For example, as in U.S. Patent 3,368,843, the quinacridone pigment can be contacted with quinacridone monosulfonic acid while still in the slurry form, after which a metal salt is added to the slurry to form a composition comprising the quinacridone pigment and contains the metal salt of quinacridone sulfonic acid. Another treatment commonly used to increase the transparency of paints is to mix the quinacridone in aqueous slurry with a small amount of an anti-flocculant, e.g. with o-carboxybenzamido-methylquinacridone, as described, for example, in US Pat. No. 3,275,637.

The quinacridone is separated from the slurry by conventional methods. The quinacridone pigment can conveniently be obtained from the slurry by filtering, washing and drying. An acidic pH value ensures that salts can be washed free of the pigment. The quinacridone pigment can be used without further processing or, if desired,

it can be pulverized with or without an extender pigment, such as nickel carbonate, before use.

The quinacridone pigment produced according to the invention is suitable for the production of paints and colored plastics.

example 1

In this example, a particularly favorable embodiment of the method is described.

Crude y-quinacridone pigment was ground in a commercial mill with 136.2 kg (300 lbs.) Of alum and 408.6 kg (900 lbs.) Of y-raw material. About 2% by weight, based on the pigment, of isopropylammonium dodecylbenzenesulfonate was added to the mill feed. The grinding medium consisted of steel cylinders with a diameter of 1.27 cm x 2.54 cm and rail nails (railroad spikes). The starting raw materials had B values of 0.28-0.30 °. It was milled for about 7.5 hours, which resulted in a B value of 0.60 °.

A surfactant solution was prepared by mixing 300 g of water, 12 g of a 50% sodium hydroxide solution and 1.25 g of commercial isopropylammonium dodecylbenzenesulfonate, the total surfactant being up to 7.7% by weight based on that Pigment. The solution was heated to 50 ° C and 34.1 g of grinding powder was added to the solution with stirring. The resulting slurry was heated to 85 ° C and held for 1 hour. The slurry was then acidified by adding 28.7 g of 50% sulfuric acid (plus 21 g of water). The slurry was then heated to 90 ° C and held at this temperature for 2 hours. 200 ml of water were then added to bring the temperature to 70 ° C., the slurry was filtered and washed with hot water free of acid, dried at 85 ° C. and pulverized.

When examined by rubbing on a hoo-ver muller in lithographic varnish or lacquer (a known and customary test method for the coloring properties of colored pigments) and in commercially available universal dyes and paint systems,

the pigment obtained gave a red with a very strong blue tone with high coloring power.

Example 2

Crude y-quinacridone pigment was placed in a commercial mill with 136.2 kg (300 lbs.) Alum and 408.6 kg (900

lbs.) of the y raw material. About 2% by weight of the pigment of isopropylammonium dodecylbenzenesulfonate was placed in the mill feed. The grinding medium consisted of 1.27 cm diameter x 2.54 cm steel cylinders and rail nails. The starting raw materials had B values of 0.28-0.30 ° and the pigment was ground to a B value of 0.68 °.

A surfactant solution was prepared by mixing 300 g of water, 12 g of a 50% sodium hydroxide solution and 1 g of isopropylammonium dodecylbenzenesulfonate and 0.5 g of octylphenol (poly) - (ethoxy) ethanol with a molecular weight of 630 (Triton X-100). The total surfactant was 6.8% by weight anionic and 2.0% by weight non-ionic. This solution was heated to 50 ° C and 33.3 g of grinding powder, prepared as described above, was added to the solution with stirring. The resulting slurry was heated to 85 ° C and held for 1 hour. The slurry was then acidified by adding 28.7 g of 50% sulfuric acid (plus 21 g of water). The slurry was then heated to 90 ° C and held for 2 hours. Finally, 200 ml of water was added to bring the temperature to 70 ° C, the slurry was filtered and washed free of acid with hot water, dried at 85 ° C and pulverized.

When examined by rubbing on a Hoover Muller in lithographic varnish or varnish and in commercially available universal dyes and paint systems, the pigment obtained was red with a strong shade of blue, but not as blue as the product from Example 1.

Example 3

Crude y-quinacridone pigment was ground in a commercial mill with 136.2 kg (300 lbs.) Of alum and 408.6 kg (900 lbs.) Of the crude y product. The grinding medium consisted of steel cylinders with a diameter of 1.27 cm x 2.54 cm and rail nails. The starting raw materials had B values of 0.28-30 ° and the final B value was 0.65 °.

A surface active solution was prepared by mixing 300 g of water, 12 g of a 50% sodium hydroxide solution, 2.0 g of isopropylammonium dodecylbenzenesulfonate and 0.5 g of octylphenol (poly) - (ethoxy) ethanol with a molecular weight of 630 (Triton X-100). The total surfactant was 8% by weight anionic and 2% by weight nonionic. This solution was heated to 50 ° C and 33.3 g of the ground powder, prepared as described above, was added to the solution with stirring. The resulting slurry was heated to 85 ° C and held for 1 hour. About 0.25 g of an anti-flocculant, o-carboxybenzamido-methylquinacri-don, was added to the solution. The slurry was then acidified by adding 28.7 g of 50% sulfuric acid (plus 21 g of water). Finally, the slurry was heated to 90 ° C and held for 2 hours. Then 200 ml of water was added to bring the temperature to 70 ° C, the slurry was filtered and washed with hot water free of acid, dried at 85 ° C and pulverized.

The product was examined by rubbing and paint test and was less blue than that of Example 1, but had a greater color strength.

Example 4

Crude y-quinacridone pigment was ground in a commercial grinder with 136.2 kg (300 lbs.) Of alum and 408.6 kg (900 lbs.) Of the crude y product. The grinding medium

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consisted of 1.27 cm diameter x 2.54 cm steel cylinders and rail nails. This raw starting material had a B value of 0.28-0.30 ° and was ground to a B value of 0.88 °.

A surface active solution was prepared by mixing 300 g of water, 12 g of a 50% sodium hydroxide solution and 1.75 g of isopropylammonium dodecylbenzenesulfonate and 1.0 g of octylphenol (poly) - (ethoxy) ethanol with a molecular weight of 630 (Triton X-100). The total surfactant was 7% by weight anionic and 4% by weight nonionic. The solution was heated to 50 ° C and 33.3 g of the ground powder was added to the solution with stirring. The resulting slurry was heated to 85 ° C and held for 1 hour. The slurry was then acidified by adding 28.7 g of 50% sulfuric acid (plus 21 g of water). Finally, the slurry was heated to 90 ° C and held for 2 hours. Then 200 ml of water was added to bring the temperature to 70 ° C, the slurry was filtered and washed free of acid with hot water, dried at 85 ° C and pulverized.

The product was then examined by rubbing and paint tests and was found to be yellow, weaker in coloring, but with a greater transparency of the full tone than the product of Example 3.

Example 5

Crude y-quinacridone pigment was ground in a commercial grinder with 136.2 kg (300 lbs.) Of alum using 408.6 kg (900 lbs.) Of the crude y product. The grinding medium consisted of steel cylinders with a diameter of 1.27 cm x 2.54 cm and rail nails. The starting raw materials had B values of 0.28-30 °. The final B value was 0.65 °.

A surfactant solution was prepared by mixing 300 g water, 12.5 g 50% sulfuric acid, 2.0 g isopropylammonium dodecyl benzenesulfonate and 0.5 g octylphenol (poly) - (ethoxy) ethanol with a molecular weight of 630 ( Triton X-100). The total surfactant was 8% by weight anionic and 2% by weight nonionic. The solution was heated to 50 ° C and 33.3 g of the ground powder was added to the solution with stirring. The resulting slurry was heated to 90 ° C and held for 2 hours. 1 g of an anti-flocculant was added. Finally the slurry was filtered and washed free of acid with hot water, dried at 85 ° C and pulverized.

The product was examined by rubbing and paint tests and was less blue than in Example 1, but had a stronger coloring power.

Example 6

Crude y-quinacridone pigment was ground in a commercial mill with 136.2 kg (300 lbs.) Of alum using 408.6 kg (900 lbs.) Of the y-raw material. The grinding medium consisted of 1.27 cm diameter x 2.54 cm steel cylinders and rail nails. This starting raw material had a B value of 0.28-30 ° and was ground to a B value of 0.88 °.

20 A surface active solution was prepared by mixing 300 g water, 1.75 g isopropylammonium dodecyl benzenesulfonate and 1.0 g octylphenol (poly) (ethoxy) ethanol with a molecular weight of 630 (Triton X-100) . The total surfactant was 7 25% by weight anionic and 4% by weight non-ionic. The

Solution was heated to 50 ° C and 33.3 g of the ground powder was added to the solution with stirring. The resulting slurry was heated to 95 ° C and held for 3 hours. The slurry was then filtered and washed with hot water and dried and pulverized at 85 ° C.

When examined by rubbing and paint tests, the product turned out to be yellow, weaker in coloring, with a greater transparency in full tone than the product of Example 3.

Industrial applicability

The linear quinacridones in pigment form which can be prepared by the process according to the invention are suitable for 40 motor vehicle finishes or top coats and paints.

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Claims (14)

642 388 2nd PATENT CLAIMS 1. A process for converting crude y-quinacridone into the pigment form, characterized in that the crude y-quinacridone in the presence of 10-50 wt .-% Alum, based on the raw quinacridone, dry-milled until the 6.5 ° 20-X-ray diffraction line shows a broadening to 0.40-0.95 ° at half-maximum intensity that the ground quinacridone can be mixed with an aqueous, anionic , surfactant, or a mixed anionic nonionic surfactant in which at least 50% of the surfactant is anionic, at a temperature of at least 40 ° C, the weight percent of the surfactant being based on the milled quinacridone is 1-20% to form a slurry of pigmentary quinacridone and that the pigmentary quinacridone is separated from the liquid in the slurry. 2. The method according to claim 1, characterized in that isopropylammonium dodecylbenzenesulfonate is used as the anionic surface-active agent. 3. The method according to claim 1, characterized in that an octylphenol polyethoxyethanol is used as the non-ionic surface-active agent. 4. The method according to claim 1, characterized in that an amount of 6-12 wt .-% surfactant is used. 5. The method according to claim 1, characterized in that the dry grinding of the crude quinacridone is continued until the 6.5 ° 20 X-ray diffraction line shows a broadening of 0.60 to 0.70 degrees at half maximum intensity and the surfactant is a 75 to 100% anionic surfactant and 0 to 25% nonionic surfactant. 6. The method according to claim 1, characterized in that the dry grinding of the crude quinacridone is continued until the 6.5 ° 20 X-ray diffraction line shows a broadening of 0.80 to 0.95 degrees at half maximum intensity and the surfactant is 50 to 75% anionic surfactant and 25 to 50% nonionic surfactant. 7. The method according to claim 5, characterized in that isopropylammonium dodecylbenzenesulfonate is used as the anionic surface-active agent. 8. The method according to claim 5, characterized in that an alkylphenoxypolyethoxyethanol is used as the non-ionic surface-active agent. 9. The method according to claim 1, characterized in that the dry grinding of the crude quinacridone is continued until the X-ray diffraction shows a broadening to 0.80 to 0.95 ° at half-maximum intensity. 10. The method according to claim 9, characterized in that one works at a temperature of 80-95 ° C. 11. The method according to claim 9, characterized in that isopropyl ammonium dodecylbenzenesulfonate is used as the anionic surface-active agent. 12. The method according to claim 9, characterized in that an alkylphenoxy-polyethoxyethanol is used as the non-ionic surface-active agent. 13. The method according to claim 1, characterized in that one uses an anionic surface-active agent. 14. The method according to claim 1, characterized in that one uses a mixed anionic-nonionic surface-active agent.