SOLIDIFICATION OF HEXYL 2-[4-(DIETHYLAMINO)-2-HYDROXYBENZOYL]BENZOATE

Abstract

The present invention relates to a process for the solidification of hexyl 2-[4-(diethylamino)-2-hydroxybenzoyl]benzoate (INCI diethylamino hydroxybenzoyl hexyl benzoate, DHHB), wherein the process comprises a step (a) of applying a shear rate of at least 400 s-1 to liquid hexyl 2-[4-5 (diethylamino)-2-hydroxybenzoyl]benzoate.

Claims

1-15. (canceled)

16. A process for the solidification of hexyl 2-[4-(diethylamino)-2-hydroxybenzoyl]benzoate (INCI diethylamino hydroxybenzoyl hexyl benzoate, DHHB), wherein the process comprises a step (a) of applying a shear rate of at least 400 s.sup.−1 to liquid hexyl 2-[4-(diethylamino)-2-hydroxybenzoyl]benzoate.

17. The process according to claim 16, wherein the liquid hexyl 2-[4-(diethylamino)-2-hydroxybenzoyl]benzoate is provided as a melt or a subcooled melt.

18. The process according to claim 17, wherein the melt has a temperature from more than 54 to 70° C., or the subcooled melt has a temperature from 15 to 54° C.

19. The process according to claim 16, wherein the applied shear rate is at least 500 s.sup.−1.

20. The process according to claim 16, wherein the step (a) is performed in an apparatus, which is cooled to a temperature of less than 54° C.

21. The process according to claim 16, wherein the step (a) is performed in an extruder, a scraped surface heat exchanger, a cooling disc crystallizer, or a stirred vessel with scraping agitator.

22. The process according to claim 16, wherein the step (a) is performed in an extruder and wherein the process comprises the steps of a1) heating hexyl 2-[4-(diethylamino)-2-hydroxybenzoyl]benzoate until a liquid melt is obtained; a2) feeding the liquid hexyl 2-[4-(diethylamino)-2-hydroxybenzoyl]benzoate into an extruder; a3) extruding the liquid hexyl 2-[4-(diethylamino)-2-hydroxybenzoyl]benzoate.

23. The process according to claim 22, wherein, in step (a1), a temperature of more than 54° C. is applied and/or wherein the step (a2) is performed under heating of the feed to a temperature of more than 54° C.

24. The process according to claim 22, wherein the extrusion step (a3) provides the hexyl 2-[4-(diethylamino)-2-hydroxybenzoyl]benzoate in the form of solidified strands.

25. The process according to claim 22, wherein the extrusion step (a3) provides the hexyl 2-[4-(diethylamino)-2-hydroxybenzoyl]benzoate in the form of a suspension, which is solidified by a further step of (a4i) cooling the suspension on a cooling belt or on a drum flaker at a temperature of less than 54° C. to obtain a solidified melt.

26. The process according to claim 25, wherein the process comprises a further step of (a5i) breaking the solidified melt into flakes or particles.

27. The process according to claim 22, wherein the extrusion step (a3) provides the hexyl 2-[4-(diethylamino)-2-hydroxybenzoyl]benzoate in the form of a suspension, which is solidified by a further step of (a4ii) forming drops of the suspension and cooling them on a cooling belt at a temperature of less than 54° C. to obtain solidified pastilles.

28. The process according to claim 22, wherein the extruder is a single screw extruder or a twin screw extruder.

29. The process according to claim 22, wherein the process is performed as a continuous process, wherein the liquid hexyl 2-[4-(diethylamino)-2-hydroxybenzoyl]benzoate is continuously fed into the extruder and the hexyl 2-[4-(diethylamino)-2-hydroxybenzoyl]benzoate is continuously collected from the extruder in the form of solidified strands or in the form of a suspension.

30. The process according to claim 16, wherein the step (a) is performed in a scraped surface heat exchanger, a cooling disc crystallizer, or a stirred vessel with scraping agitator and wherein the process comprises the steps of (a1r) heating hexyl 2-[4-(diethylamino)-2-hydroxybenzoyl]benzoate until a liquid melt is obtained; (a2r) cooling the liquid hexyl 2-[4-(diethylamino)-2-hydroxybenzoyl]benzoate to obtain a subcooled melt of hexyl 2-[4-(diethylamino)-2-hydroxybenzoyl]benzoate; (a3r) feeding the subcooled melt of hexyl 2-[4-(diethylamino)-2-hydroxybenzoyl]benzoate into an apparatus and (a4r) applying shearing on the subcooled melt of hexyl 2-[4-(diethylamino)-2-hydroxybenzoyl]benzoate.

Description

EXAMPLES

Comparative example

[0059] Solidification of DHHB was tested under the following conditions

TABLE-US-00001 TABLE 1 Temperature Solidification time Room temperature 2-3 weeks Refrigerator (4° C.) 1 week Freezer (−18° C.) 2-3 days

[0060] The results show that the solidification kinetics for DHHB are very slow.

Example 1

[0061] Solidification of DHHB in a rheometer

[0062] Shearing was applied to a subcooled melt of DHHB having a temperature of 25° C. by a rotating cone.

[0063] Start of nucleation was determined by observing the shear rate and the viscosity. Nucleation starts when the shear rate drops and the viscosity increases.

[0064] It was observed that with increasing shear rates, the time period until nucleation started shortened. The nucleation then initiates the solidification of the DHHB. The results for different shear rates are summarized in Table 2.

TABLE-US-00002 TABLE 2 Shear rate until Start of Solidification nucleation nucleation time [1/s] [min] [min]  570 162 12 1000 102 10 1080  76 12

Example 2

[0065] Solidification of DHHB in an extruder

[0066] An extruder without a die head was used. For melting the DHHB, a heating cabinet at a temperature of 70° C. was used. The feeding unit was heated at a temperature of 60° C. The extruder was cooled using a cryostat. The rotational speed of the screw was adapted as indicated in table 3. The throughput of the extruder and the temperature of the extrusion mass were adapted as indicated in table 3. The results for the solidification time are provided in table 3.

TABLE-US-00003 TABLE 3 Average Temperature Screw shear of the Solidification speed rate extrusion Throughput time [rpm] [1/s] mass [° C.] [kg/h] [min]  100 nd 14 2 30  100 nd  8 1 10 1000 400 17 1  5 1000 400 18 2 10 1000 400 19 2 10