Method for producing a crystalline solid from glycine-N, N-diacetic acid derivatives with sufficiently reduced hygroscopicity

Abstract

The present invention relates to a process for preparing a crystalline solid from glycine-N,N-diacetic acid derivatives (e.g., MGDA) of sufficiently low hygroscopicity, which is characterized in that at least one crystalline compound of the formula I is introduced as seed, and a spray granulation is carried out with at least one compound of the formula I, preferably followed by a heat treatment.

Claims

1. A process for preparing a crystalline solid, the process comprising spray granulating an aqueous solution of a liquid raw material on a crystalline seed material to obtain the crystalline solid, wherein the crystalline seed material, the liquid raw material, and the crystalline solid each comprise a glycine-N,N-diacetic acid derivative of formula (I) ##STR00004## wherein R is: a C.sub.1 to C.sub.30 alkyl or a C.sub.2 to C.sub.30 alkenyl, optionally having up to 5 substituents selected from a hydroxyl group, a formyl group, a C.sub.1 to C.sub.4 alkoxy group, a phenoxy group and a C.sub.1 to C.sub.4 alkoxycarbonyl group and optionally having up to 5 nonadjacent oxygen atoms; an alkoxylate moiety of formula (II)
(CH.sub.2).sub.kO-(A.sup.1O).sub.m-(A.sup.2O).sub.nY (II) in which A.sup.1 and A.sup.2 each independently are alkylene groups having 2 to 4 C atoms, Y is hydrogen, C.sub.1 to C.sub.12 alkyl, phenyl or C.sub.1 to C.sub.4 alkoxycarbonyl, k is 1, 2 or 3, and m and n are each integers of 0 to 50, a sum of m+n being at least 4; a phenylalkyl group having 1 to 20 C atoms in an alkyl part of the group; a five- or six-membered, unsaturated or saturated, heterocyclic ring having up to three heteroatoms from the group consisting of nitrogen, oxygen, and sulfur, which may additionally be benzofused, it being possible for any phenyl ring and heterocyclic ring of R additionally to have up to three substituents selected from the group consisting of a C.sub.1 to C.sub.4 alkyl group, a hydroxyl group, a carboxyl group, a sulfo group and a C.sub.1 to C.sub.4 alkoxycarbonyl group; or R is a radical of formula (III) ##STR00005## where A is a C.sub.1 to C.sub.12 alkylene bridge or a chemical bond, and each M independently is hydrogen, an alkali metal, an alkaline earth metal, ammonium or substituted ammonium in a corresponding stoichiometric amount.

2. The process according to claim 1, wherein the process is performed in a granulator and the process further comprises removing a part of the crystalline solid from the granulator, grinding the crystalline solid to obtain additional crystalline seed material, and introducing the additional crystalline seed material into the granulator.

3. The process according to claim 1, wherein R is C.sub.1 to C.sub.20 alkyl, C.sub.2 to C.sub.20 alkenyl or a radical of formula (III) ##STR00006##

4. The process according to claim 1, wherein the glycine-N,N-diacetic acid derivative is -alanine-N,N-diacetic acid (MGDA) or an alkali metal salt, an ammonium salt or a substituted amine salt thereof.

5. The process of claim 1, wherein R is C.sub.1 to C.sub.20 alkyl.

6. The process of claim 1, wherein R is C.sub.2 to C.sub.20 alkenyl.

7. The process of claim 1, wherein R is an alkoxylate moiety of formula (II)
(CH.sub.2).sub.kO-(A.sup.1O).sub.m-(A.sup.2O).sub.nY (II).

8. The process of claim 1, wherein R is a radical of formula (III) ##STR00007##

9. The process of claim 1, wherein A is hexamethylene, octamethylene, 1,2-ethylene, or 1,4-butylene.

10. The process of claim 1, wherein the spray granulating comprises an air feed temperature is 90-160 C.

11. The process of claim 1, wherein the spray granulating comprises an air departure temperature is 40-110 C.

12. The process of claim 1, wherein the crystalline solid temperature obtained by the spray granulating is 40-110 C.

13. The process of claim 1, wherein the spray granulating comprises a spraying air temperature is 70-110 C.

14. The process of claim 1, wherein the spray granulating comprises a spraying air pressure is 1-6 bar.

15. The process of claim 1, wherein the liquid raw material is at a temperature is 50-95 C.

16. The process of claim 1, wherein the obtained crystalline solid preserves its consistency as a powder or granules over a period of at least one day when stored at 25 C. and a relative humidity of 76%.

Description

EXAMPLE

(1) The procedure below was carried out in a fluid-bed spray granulator which is equipped with a cyclone, a filter, and a gas scrubber.

(2) The starting material (Trilon M, liquid, from BASF AG) was heated to 90 C. with continuous and intense mixing and was used at this temperature for the granulation. Under the following conditions, a stable granulating operation was achieved:

(3) TABLE-US-00001 Process parameters: Feed air temperature 125 C. Departing air temperature 65 C. Product temperature 65-70 C. Intake air volume 1300 m.sup.3/h Spraying air temperature 90 C. Spraying air pressure 3 bar Spraying solution temperature 80 C.

(4) In order to raise the crystallinity, the product prepared was aftertreated with a temperature profile commencing with a bed temperature of 70 C., then raising this temperature to around 110-120 C. over the course of around an hour, and subsequently holding at this temperature for around 60 minutes.

(5) Screening at 1000 microns and re-use of the ground coarse material as crystallization seeds for the granulation process led to a stable operation with a yield of about 20 kg of granules per hour in the desired quality. The introduction of comminuted material was advantageous for the process, in order to maintain the height of the bed, and in order to obtain the product in a crystalline form.