| JP2001234209 | Ti SCRAP PULVERIZING METHOD |
| JP2000179003 | METHOD AND DEVICE FOR TREATING EARTH AND SAND |
| WO/2000/032165 | MILLING PROCESS FOR THE PRODUCTION OF FINELY MILLED MEDICINAL SUBSTANCES |
| 1. | ed are defined as follows: In a process in which a finely divided pigment is produced from a coarser crude pigment by grinding the coarse pigment In the presence of a water soluble inorganic salt and a water soluble condition¬ ing agent and thereafter separating the resulting fine¬ ly divided pigment from said salt and said condition¬ ing agent, the Improvement which comprises providing as the conditioning agent a water soluble material selected from the group consisting of corn syrup, corn syrup solids and molasses. |
| 2. | The process of Claim 1 wherein the con¬ ditioning agent is diluted with a diluent selected from the group consisting of water, glycols, polyglycols and mixtures thereof. |
| 3. | The process of Claim 1 in which the pro¬ portion of salt to pigment is up to 20 parts by weight of salt for each part by weight of pigment. |
| 4. | The process of Claim 3 in which the pro¬ portion of salt to pigment is between about 4 and 6 parts by weight of salt for each part by weight of pig¬ ment. |
| 5. | The process of Claim 1 in which the salt is NaCl. |
| 6. | The process of Claim 1 In which the pro¬ portion of conditioning agent to pigment is between 'about 1/2 and 4 parts by weight of conditioning agent to each part by weight of pigment. |
| 7. | The process of Claim 1 in which the pro¬ portion of conditioning agent is between 1 and 2 parts by weight of conditioning agent to each part by weight of pigmen . |
| 8. | The process of Claim 1 wherein the pigment is a crystalline material. |
| 9. | The process of Claim 1 wherein the pigment is a phthalocyanine. |
| 10. | The process of Claim 1 wherein the pigment, salt and conditioning agent are fed continuously Into a continuous mixer and the product is continuously with¬ drawn from said mixer. OMPI. |
PROCESS FOR SALT GRINDING OP PIGMENTS
This invention relates to the grinding of pig¬ ments using a minimum of energy and a minimum amount of grinding aids. The resulting pigments possess colors which are clean and strong and compare more than favor¬ ably with current commercially available ground pig¬ ments.
The properties of pigments depend in part on the fineness of the particles and on their shape and the art of comminuting pigments is highly developed- as may be seen from the following patents which are con¬ sidered representative of the art to which the present invention pertains: 4
Lang et al 2,402,167 issued June .18, 19 6 Graham 2,556,728 issued June 12, 1951
Ehrich et al 2,816,114 issued December 10, 1957 Huband et al 3,176, issued -April 6, 1965 Lucchini et al 3,313, 1 issued April 11, 1967 Akamatsu et al 3,748,164 issued July 24, 1973 Steel et al 3,950,182 issued April 13, 1976
(Reissued as RE 29,295)
As described, for example, in Ehrich 2,816,114. at least three distinct methods are recognized, namely: (1) acid pasting; (2) salt milling; and (3) solvent
milling.
Later developments of the salt milling techni¬ que include the addition of tackifying agents to imp¬ rove the process, e.g. as described in Akamatsu et al 3,748,164 and elsewhere in the patent literature.
The present invention is addressed to an imp¬ roved salt milling or salt grinding process wherein a viscous material such as corn syrup, corn syrup solids or molasses with or without the addition of either water or a glycol or both as viscosity modifying agents is added to the salt and pigment whereby the proportion of salt relative to the amount of pigment may be con¬ siderably diminished and the process may be carr-Lsd out more expeditiously.
One object of the Invention is to provide a process for the manufacture of a suitable pigment for the coloration of inks for paper and textile printing, for the coloration of plastic, fibers, paints, paper, etc., by grinding crude pigment crystals, using a water soluble inorganic salt as the grinding media and a viscous material corn syrup, corn syrup solids or molasses, as the grinding aid, the viscosity of these being modified if desired with either water, a glycol or a polyglycol.
Another object of the invention is to produce pigments with excellent color values by a salt grinding
process using a less than normal quantity of the salt and using much less energy than the conventional met¬ hods now being practiced.
A further object of the invention is to carry out the salt grinding process in a continuous mixer Instead of the double arm mixer which has been utili¬ zed in the past as described in United States Patent 3,748,164 and other patents, whereby a more uniform -product may be produced in large quantities over exten¬ ded time intervals with less energy consumption than is required by standard double arm mixers.
The salt used in the salt milling process of the present invention may be any of a number of inor¬ ganic salts including sodium chloride, sodium sul ate, sodium carbonate, and any of the other water soluble salts noted for example in United States Patent 3,176,925, the disclosure of which is incorporated by this reference. Because it is readily available and is inexpensive, the preferred grinding agent is NaCl. The proportions of salt to pigment may be as high as 20:1 and as low as 3:1 or even lower but since the salt must be washed out of the pigment product, proportions between about 4:1 and 6:1 are preferred to higher ones.
The conditioning agents which have been added to permit the use of smaller proportions of the
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salt used as a grinding aid include: a commercially available corn syrup (Globe Three Star 1132) which consists of 8θ solids, 20 water; corn syrup solids (A. F. Staley, dry corn syrup solids 42R) which con¬ sists of 96% solids; and ordinary commercially avail¬ able molasses. The conditioning agents may be modi¬ fied with water and/or a glycol, such as ethylene gly¬ col or propylene glycol, or a polygl col to produce a 'desired viscosity.
The proportion of conditioning agent may be between about 1/2 and 4 pounds per pound of pigment, a preferred range being between about 1 and 2 pounds per pound of pigment being processed.
The pigment was recovered from the charge in the mixer by dumping the contents of the mixer into a container and washing with water, while stirring, so that the salt and conditioning agent were dissolved. The mixture was filtered and the pigment was collected on ±he-fϋter.
The present invention possesses a number of advantages over the prior art salt milling processes known to Applicant, including the following:
1. smaller proportions of salt may be used, thereby requiring less water to remove the salt from the pigment product;
2. smaller amounts of energy are required
than when salt grinding without the conditioning agent and the grinding may be accomplished in a shorter time interval;
3. the process may be run as either a batch process or as a continuous process whereby a more uni¬ form product is obtainable;
4. no toxic solvents or other chemicals are added to the pigment to be ground;
5. both of the additives, salt and condition¬ ing agent are readily available as commercial products and relatively inexpensive.
The invention will be further understood from the Examples which follow which are intended to illus¬ trate preferred embodiments of the invention and are not intended to limit the same.
EXAMPLE I
Into a heavy duty laboratory double arm mixer with a capacity of 1 liter, driven by a 1 H.P. motor, the following were added in increments over a period of 15 minutes:
180 grams NaCl 60 grams crude copper phthalocyanine blue 80 grams corn syrup (Globe Three Star 1132)
The resulting mixture was ground for approxi¬ mately 1.5 hours. The mixer jacket was cooled to maintain a temperature of l4θ-l8θ°P in the mixer. The
grinding mass was a firm plastic dough. When grinding was complete the mixture was removed from the mixer and the salt and the corn syrup were removed by dissolving them in l6θ°F water. The pigment was filtered and washed until salt free. The filter cake had a solids content of 38£ to 2 and the color was a bright green shade of blue equal or superior to brands currently on the market.
The process can be speeded up by increasing the salt to pigment ratio .from 3 " to 1, for example up to 6 to 1 ratio.
EXAMPLE II Into a heavy duty laboratory double arm mixer of Example- I the following were added in increments as in the preceding Example:
180 grams sodium chloride 60 grams crude copper phthalocyanine blue 60 grams corn syrup (Globe Three Star 1132) 20 grams corn syrup solids (A. F. Staley 42R) The firmness of the resulting plastic dough was adjusted with small amounts of H2O or a glycol. After 1.5 hours the material was removed from the mixer and treated as in Example I to recover the pigment.
EXAMPLE III Into a Baker Perkins (MP 1295) continuous mix¬ er, turning at a speed of 70 rmp, powered by a 150 H.P.
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otor the following materials were fed continuously and simultaneously at the indicated .rates and with a resi¬ dence time of about nine minutes:
20 pounds salt (NaCl)/min.
3 pounds copper phthalocyanine blue crude/min.
4 pounds corn syrup (Globe Three Star)/min. The jackets and paddle shaft core were cooled so that the ground mixture exiting from the machine had a temperature of 120-l4θ°F. The ground material was placed in a tank with sufficient water to dissolve the corn syrup and the salt. It was then pressed and wash¬ ed free of salt and syrup. The resulting cake was app¬ roximately θ£ solids and was of excellent quality.
Although the present invention has been des¬ cribed with reference to milling crude phthalocyanine blue, it has also been successfully applied to grind the crude crystals of carbazole viole , copper phtha¬ locyanine green and flavanthrone with excellent results and can be used in connection with the grinding of other organic pigments having a crystalline structure with characteristics similar to those of the enumer¬ ated pigments.
Having described preferred embodiments of the invention, it is not intended that it be limited ex'cept as described in the appended claims.
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