Process for the Production of Solid Cooling Agents

Abstract

Suggested is a process for the production of solid cooling agents, wherein a pre-scraped melt, i.e., a melt of menthol compounds with added seed crystals is applied to a pre-cooled area by even deposition of drops.

Claims

1. A process for the production of a solid cooling agent, wherein a pre-scraped melt, i.e., a melt of menthol compounds with added seed crystals, is placed onto a pre-cooled area by even deposition of drops.

2. The process of claim 1, wherein seed crystals are used which were formed by treatment of the melt to be used in a scraped surface heat exchanger.

3. The process of claim 1, wherein the menthol compounds are selected from the group consisting of Menthol, Racemic Menthol, Menthol Methyl Ether, Menthone Glyceryl Acetal (FEMA GRAS 3807), Menthone Glyceryl Ketal (FEMA GRAS 3808), Menthyl Lactate (FEMA GRAS 3748), Menthol Ethylene Glycol Carbonate (FEMA GRAS 3805), Menthol Propylene Glycol Carbonate (FEMA GRAS 3806), Menthyl-N-ethyloxamate, Monomethyl Succinate (FEMA GRAS 3810), Monomenthyl Glutamate (FEMA GRAS 4006), Menthoxy-1,2-propanediol (FEMA GRAS 3784), Menthoxy-2-methyl-1,2-propanediol (FEMA GRAS 3849) and the menthane carboxylic acid esters and amides WS-3, WS-4, WS-5, WS-12, WS-14 and WS-30 and mixtures thereof.

4. The process of claims 1, wherein a pre-scraped melt of menthol compounds is used, which has a temperature in the range of from about 40 to about 60° C.

5. The process of claim 1, wherein a pre-scraped melt is used, containing from about 0.1 to 12 wt. % seed crystals.

6. The process of claim 5, wherein a pre-scraped melt is used, containing from about 0.1 to about 12 wt. % seed crystals of L-menthol.

7. The process of claim 1, wherein the melt is cooled on a steel belt, whereby the cooling zones independently of one another each have temperatures below the respective melting point, for L-menthol in the range of from 15 to about 42° C.

8. A cooling agent in solid form, obtained according to the process of claim 1.

9. The cooling agent of claim 8, comprising (i) a proportion of fines of particles with an average diameter smaller than 1.6 mm of less than 5 wt. %; and/or (ii) an alpha-menthol content of at least 80 wt. %; and/or (iii) a surface-to-volume ratio of less than 2:1/mm; and/or (iv) curved surfaces, so that the ratio of plane surface to the total surface of the particle is 60 maximum.

10. Menthol particles in pastille form with a curved and a flat side, and comprising (i) a proportion of fines of particles with an average diameter smaller than 1.6 mm of less than 5 wt. %; and/or (ii) an alpha-menthol content of at least 80 wt. %; and/or (iii) a surface-to-volume ratio of less than 2:1/mm; and/or (iv) curved surfaces, such that the ratio of plane surface to the total surface of the particle is 60 maximum.

11. The particles of claim 10, comprising a proportion of fines of particles with an average diameter smaller than 1.6 mm of less than 2 wt. %.

12. The particles of claim 10, comprising an α-menthol content of from about 85 to about 99 wt. %.

13. The particles of claim 10, having a surface-to-volume ratio of less than 1.5:1/mm.

14. The particles of claim 10, having curved surfaces, such that the ratio of plane surface to the total surface of the particle is less than 50%.

15. A cosmetic or pharmaceutical preparation or food comprising the solid cooling agent of claim 8.

16. A cosmetic or pharmaceutical preparation or food comprising the menthol particles of claim 10.

Description

EXAMPLES

[0062] Examples of Production

[0063] In the following examples of embodiment it was intended to determine how the production of pastilles with an optimum surface-to-volume ratio and good caking properties are to be produced and examined. Also, it was intended to determine process conditions ensuring the production of completely crystallised material. Any post-crystallisation in the packaged state should be avoided.

[0064] Test Set Up And Performance of the Process

[0065] The tests were performed on a steel belt cooler with a Rotoformer and an upstream scraped surface heat exchanger as schematically illustrated in Figure A. Here, the reference signs mean the following:

TABLE-US-00001 1 Educt container 2 Educt pump 3 Extruder 4 Heat exchanger 5 Valve 6 Re-feeding of educt 7 Rotoformer 8 Cooling belt with three cooling zones T1, T2, T3 9 Granulator 10 Product deposition

[0066] In doing so, a melt that has been pre-scraped in the scraped surface heat exchanger (i.e., a suspension of seed crystals in menthol) was deposited onto a pre-cooled steel belt by means of a Rotoformer. The length of the cooling belt was 12.5 m, the width of the belt was 600 mm. The cooling belt had three cooling zones which could be tempered independently of one another. Scraping from the cooling belt was performed by knife, either after a single cooling period or with the aid of of the belt rewind near the deposition location. In doing so, the material was subjected to additional cooling on the 12.5 m of the belt rewind. The speed of operation of the cooling belt (and thus the capacity of the cooling belt) was changed only insignificantly in the course of the tests, as a result of which an output in the range of from 150-165 kg/h during the tests was obtained. The material obtained was separated from attached fines by means of a vibrating screen (company Allgaier; sieve hole width: 1.6 mm and 1.25 mm). The deposition temperature of the material was determined by measurement in a Dewar vessel using a thermocouple element. The change of temperature after scraping from the belt will in the following be referred to as post-crystallisation heat. Output was determined with a stopwatch and a scale at the middle part of a test run. For each test, about 20 to 30 kg pastilles were removed as initial forerunnings. The materials obtained were packed into F1cardboard boxes with a PE inner bag—(Symrise standard packaging means for compacted menthol) during the test.

Example 1

[0067] A starting temperature of 30° C. was selected for T1 and T2, as this temperature of the metal belt is near the congelation temperature of the α-form (see FIG. 1) and only a small amount of γ-form could be expected at a superposed spontaneous crystallisation. The congelation temperature in the pastille should be higher as a result of an inferior heat transfer through the congealed menthol and should thus, preferably, lead to the formation of the α-form. At T3, 15° C. were selected to increase the heat transfer through the already solidified menthol thus ensuring a complete crystallisation. The test conditions are reflected in Table 1.

TABLE-US-00002 TABLE 1 Test conditions Temperature zones of the T1: 30° C.; T2: 30° C.; T3: 15° C. cooling belt Temperature of the scraped 41.5° C. surface heat exchanger Output 150 kg/h Weights (cardboard boxes) 15.6 kg/12.45 kg/19.50 kg/21.05 kg/20.6 kg Fines 41.8 g per 89.2 kg (469 g/t pastilles) Deposition temperature 25.2° C. Post-crystallisation heat 1° C. over 1 h Room temperature: 27° C.

[0068] After removing small forerunnings, pure white pastilles were obtained (FIG. 1). The pastilles were completely crystallised and difficult to split with a spatula/knife.

Example 2

[0069] After passing the cooling belt, the pastilles were not completely crystallised at T2. At the end of the cooling belt at T3, the pastilles were slightly soft at the upper end and easily splittable with a knife. The test conditions are reflected in Table 2; the pastilles are shown in FIG. 2.

TABLE-US-00003 TABLE 2 Test conditions Temperature zones of the T1: 30° C.; T2: 30° C.; T3: 18° C. cooling belt Temperature of the scraped 41.4-41.6° C. surface heat exchanger Output 165 kg/h Weights (cardboard boxes) 19.82 kg/20.48 kg/20.93 kg/20.27 kg Fines 106.4 g per 81.5 kg (1305 g/t pastilles) Deposition temperature 24.4° C. Post-crystallisation heat 1° C. over 30 min Room temperature: 27° C.

Example 3

[0070] In the course of test 3, the scraper knife at the end of the cooling belt was removed. The belt rewind was used as an additional post-cooling section. The pastilles were hard and fully crystallised after scraping. The test conditions are reflected in Table 3; the pastilles are shown in FIG. 3.

TABLE-US-00004 TABLE 3 Test conditions Temperature zones of the cooling belt T1: 30° C.; T2: 30° C.; T3: 18° C.; belt rewind post- cooling Temperature of the scraped surface heat 41.4-41.6° C. exchanger Output 165 kg/h Weights (cardboard boxes) 20.57 kg/20.49 kg/19.36 kg Fines 48.6 g per 60.42 kg (804 g/t pastilles) Deposition temperature 24.4° C. Post-crystallisation heat 1° C. over 30 min Room temperature: 27° C.

Example 4

[0071] The pastilles were comparable to example 1. The test conditions are reflected in Table 4; the pastilles are shown in FIG. 4.

TABLE-US-00005 TABLE 4 Test conditions Temperature zones of T1: 30° C.; T2: 30° C.; T3: 15° C. the cooling belt Temperature of the scraped 41.5-41.6° C. surface heat exchanger Output 150 kg/h Weights (cardboard boxes) 18.85 kg/18.75 kg/19.45 kg/19.65 kg Fines 106.1 g per 76.7 kg (1383 g/t pastilles) Deposition temperature 25.2° C. Post-crystallisation heat 1.0° C. over 30 min Room temperature: 28° C.

Example 5

[0072] In the course of example 5, the scraper knife at the end of the cooling belt was removed. The belt rewind was used as an additional post-cooling section. The pastilles were hard and fully crystallised after scraping. The test conditions are reflected in Table 5; the pastilles are shown in FIG. 5.

TABLE-US-00006 TABLE 5 Test conditions Temperature zones of the cooling belt T1: 30° C.; T2: 30° C.; T3: 15° C.; belt rewind post-cooling Temperature of the scraped surface heat 41.4-41.6° C. exchanger Output 165 kg/h Weights (Kartons) 15.4 kg Deposition temperature 22.2° C. Post-crystallisation heat 1.0° C. over 30 min Room temperature: 28° C.

Example 6

Comparison Example V1

[0073] Example 1 was repeated, cooling, however, was performed by means of a double belt cooler with cooled steel surfaces and a gap width of 0.3 cm (length 12 m, width 35 cm). The double belt cooler also had 3 cooling zones (30° C., 30° C., 15° C.); the product was scraped off in the form of flakes by means of a knife.

[0074] 5 kg each of the pastilles of example 1 according to the invention (diameter: 5 mm) and of the comparison example V1 were filled into bags of synthetic material which were stored in cardboard boxes at 20° C. for a period of 6 weeks. The results are summarised in Table 6.

TABLE-US-00007 TABLE 6 Storage tests Storage time Example 1 Comparison example V1 1 week Material easily separable at the Material easily separable at the surface. surface. No agglomeration. No agglomeration. 2 weeks Material easily separable at the Material separable at the surface. In the surface. In the centre of the filling, a centre of the filling there are small amount cakes to form agglomerations which are separable by agglomerations which are manually means of a shovel. separable. 3 weeks Material easily separable at the Material separable at the surface. In the surface. In the centre of the filling, a centre of the filling there are distinct small amount cakes to form agglomerations which are separable by agglomerations which are manually means of a shovel. separable. 4 weeks Material easily separable at the Material is separable at the surface. In surface. In the centre of the filling, a the centre of the filling there are distinct small amount cakes to form agglomerations which are separable by agglomerations which are manually means of a shovel. separable. 5 weeks Material is separable at the surface. In Material difficult to separate at the the centre of the filling there are surface. In the centre of the filling there agglomerations which are separable are distinct agglomerations, which are by means of a shovel. separable by means of a shovel. At the surface, slight formation of needles due to sublimation. 6 weeks Material is separable at the surface. In 80% is agglomerated, distinct formation the centre of the filling there are of needles due to sublimation. distinct agglomerations, which are separable by means of a shovel. At the surface, slight formation of needles due to sublimation.

Example 7

[0075] In order to prove that the crystal form alone is not decisive for the inclination to cake, 20 kg of 8 L-menthol that had been stored for 8 months and which was completely present in its α-form, were comminuted by means of a seave mill with a 3 mm sieve hole insert to obtain crystal powder. In doing so, no increase in temperature as a result of the comminution process was measured. Subsequently, the crystal powder was stored again. Already after two weeks the powder was caked, forming a block which could only be loosened locally by heavy kneading.