PROCESS FOR PRODUCING MICROPARTICLES LADEN WITH AN AROMA CHEMICAL

Abstract

The present invention relates to a process for producing polymer microparticles laden with at least one aroma chemical, which comprises i. dissolving the at least one aroma chemical and an organic polymer composition, which contains at least one polyester as a main constituent, in a volatile organic solvent having a boiling point lower than the boiling point of the aroma chemical and having a solubility in water of at most 100 g/L at 20° C. and 1013 mbar, whereby a solution of the aroma chemical and the organic polymer composition is obtained; ii. emulsifying the solution obtained in step i. in an aqueous medium containing at least one dispersant; iii. removing the volatile organic solvent from the emulsion by evaporation at a temperature of below 80° C. and at a pressure below atmospheric pressure, whereby an aqueous suspension of the laden polymer microparticles is obtained. The present invention also relates to microparticles laden with an aroma chemical, obtainable by the process described herein and to products containing the microparticle composition. The compositions are useful as additives for imparting a scent or flavour to a product. The compositions allow for controlled release of the aroma chemicals.

Claims

1.-15. (canceled)

16. A process for producing polymer microparticles laden with at least one aroma chemical, which comprises: i. dissolving the at least one aroma chemical and an organic polymer composition, which contains at least one polyester as a main constituent, in a volatile organic solvent having a boiling point lower than the boiling point of the aroma chemical and having a solubility in water of at most 100 g/L at 20° C. and 1013 mbar, whereby a solution of the aroma chemical and the organic polymer composition is obtained; wherein the concentration of the organic polymer composition in the solution is in the range of 1 to 250 g/kg, based on the total weight of the solution; and the weight ratio of the aroma chemical to organic polymer composition is in the range of 1:50 to 2:1; ii. emulsifying the solution obtained in step i. in an aqueous medium containing at least one dispersant; iii. removing the volatile organic solvent from the emulsion by evaporation at a temperature of below 80° C. and at a pressure below atmospheric pressure, whereby an aqueous suspension of the laden polymer microparticles is obtained.

17. The process of claim 16, where the organic solvent has a boiling point at 1013 mbar in the range of 35 to 85° C.

18. The process of claim 17, where the organic solvent is selected from the group consisting of dichloromethane, trichloromethane, ethyl acetate, benzene, n-hexane, cyclohexane, n-pentane, diethyl ether, methyl tert.-butyl ether, diisopropyl ether and mixtures thereof with 2-butanone.

19. The process of claim 16, where the weight ratio of the aroma chemical to organic polymer composition is in the range of 1:20 to 1.5:1 or 1:20 to 1:1.5.

20. The process of claim 16, where the dispersant contained in the aqueous phase is selected from the group consisting of polysaccharides, polyvinyl alcohols, polymers bearing sulfonate groups, polyvinylpyrolidone copolymers of vinylpyrrolidone and inorganic pickering stabilizers.

21. The process of claim 16, where in step ii. the relative weight of the solution obtained in step i. and the aqueous medium is in the range of 1:5 to 1:1.

22. The process of claim 16, where emulsification comprises mixing the solution of step i. with the aqueous phase and homogenization of the mixture.

23. The process of claim 22, wherein the homogenization is carried out until the average droplet size of the emulsion is at most 400 μm.

24. The process of claim 16, where the evaporation of the solvent is carried out until the concentration of the microparticles in the aqueous suspension is in the range of 2 to 30% by weight, based on the total weight of the suspension.

25. The process of claim 16, wherein the polymer composition comprises at least one aliphatic polyester or at least one semi-aromatic polyester or a combination of at least one semi-aromatic polyester with at least one thermoplastic polymer which is not a semi-aromatic polyester.

26. The process of claim 16, which further comprises the isolation of the microparticles from the aqueous suspension.

27. A composition of microparticles laden with an aroma chemical, obtainable by a process according to claim 16.

28. A product comprising a composition according to claim 27 in a proportion of 0.01% to 80% by weight based on the total weight of the product.

29. The use of the composition according to claim 27 as an additive for imparting a scent or a flavour to a product selected from perfumes, washing and cleaning products, cosmetic products, personal care products, hygiene articles, foods, food supplements, fragrance dispensers and fragrances.

30. The use of the composition according to claim 27 for controlled release of aroma chemicals.

Description

[0380] Preference is likewise given to the use of compositions of the invention for controlled release of actives such as crop protecting agents and pharmaceutical agents.

[0381] FIG. 1: Microphotography obtained by scanning electron microscopy of the laden microparticles of example 1 after storage for 20 days at ambient temperature at 3800-fold magnification.

[0382] FIG. 2: Microphotography obtained by scanning electron microscopy of the freshly prepared laden microparticles of example 2 at 3000-fold magnification.

[0383] FIG. 3: Microphotography obtained by scanning electron microscopy of the freshly prepared laden microparticles of example 3 at 3600-fold magnification.

[0384] FIG. 4: Microphotography obtained by scanning electron microscopy of the freshly prepared laden microparticles of example 4 at 5000-fold magnification.

[0385] FIG. 5: Microphotography obtained by scanning electron microscopy of the freshly prepared laden microparticles of example 5 at 4100-fold magnification.

[0386] FIG. 6: Microphotography obtained by scanning electron microscopy of the freshly prepared laden microparticles of example 6 at 5100-fold magnification.

EXAMPLES

[0387] Materials

[0388] Unless stated otherwise, the following materials and components were used: [0389] Polybutylene sebacate terephthalate (PBSeT): Ecoflex™ FS Blend A1300, melting point in the range of 100-140° C., glass transition temperature of −33° C. (BASF SE); [0390] Polycaprolactone (PCL) having a hydroxyl number of 2 mg KOH/g and a melting point in the range of 58 to 60° C.: product Capa6506 of Perstorp; [0391] Semicrystalline copolyester having a hydroxyl number of 27 to 34 mg KOH/g, a melting point of 65° C., as determined by DSC, and a softening point of 73° C., as determined according to DIN EN ISO 4625:2020-11: Dynacoll® 7381 of Evonik industries; [0392] Polyvinylalcohol: degree of hydrolysis of 88 mol %, a viscosity of a 4% by weight aqueous solution at 20° C. of 25 mPa*s and proportion of carboxyl groups of 3 mol %; [0393] 50 wt. % colloidal silica dispersion in water: Bindzil 50/80 of AkzoNobel; [0394] Methylhydroxypropylcellulose: Culminal MHPC 400 R of Ashland; [0395] Medium sulfonated kraft lignin dispersant: Reax® 910 of Ingevity; [0396] defoamer: combination of modified non-ionic fats and hydrophobic silica in [0397] aroma chemical composition: fruity floral odor with woody-spicy note characterized by the following evaporation rate at 30° C. and 1 bar:

TABLE-US-00001 TABLE 1 Time [hours] Aroma chemical mixture Δ M [%]* 0 0 3 5 5 7 7 10 24 22 48 30 72 36 168 41 336 56 *Decrease in mass of the aroma chemical mixture in % by weight normalized to the starting value

[0398] Methods

[0399] Particle diameter: The particle diameter of the o/w emulsion or the particle suspension is determined by static laser light scattering according to ISO 13320:2009 (laser diffraction) with a Malvern Mastersizer 2000 from Malvern Instruments, England, Hydro 2000S sample dispersion unit, by a standard test method documented in the literature.

[0400] Scanning electron microscopy: Close-up images were taken from a probe of the microparticles, these were retrospectively automatically measured using the ProSuite (FibreMetric) software from Phenom.

[0401] The amount of dichloromethane in the aqueous suspension of microparticles was assessed by determining the chlorine content. The chlorine content was determined by complete incineration of the organic matter and determining the amount of formed hydrochloric acid by coulometric titration.

Example 1

[0402] i. In a glass vessel 5.4 g of the aroma chemical, 6.48 g of PCL and 15.12 g of PBSeT were dissolved at room temperature in 270 g of dichloromethane with stirring until a clear solution of the polymer composition and the aroma chemical in dichloromethane was obtained. [0403] ii. 34.6 g of a 10% by weight aqueous solution of the polyvinyl alcohol, 0.26 g of the defoamer and 388.4 g of deionized water were charged to a 2 L vessel. To this mixture the solution of the polymer composition and the aroma chemical in dichloromethane was added within 30 s with stirring by means of an Ultra Turrax T25 at a rotation speed of 5000 rpm. Then, the mixture was homogenized for 3 minutes by means of the Ultra Turrax at 5000 rpm. The thus obtained o/w emulsion had an average droplet size of less than 15 μm. [0404] iii. Then the Ultra turrax was replaced by an anchor stirrer. A vacuum of 400 mbar was applied, and the vessel was warmed to 45° C. (bath temperature) and solvent was evaporated for 6 h with stirring at 250 rpm. The resulting suspension contained less than <10 ppm dichloromethane.

[0405] The mean particle diameter D[v, 0.5] determined from the aqueous suspension was 9.1 μm, the D[v, 0.1] was 1.4 μm and the D[v, 0.9] was 20 μm.

[0406] FIG. 1 shows a microphotography of the laden microparticles of example 1 after isolation from the suspension by centrifugation and storage for 20 days at ambient temperature which was obtained by scanning electron microscopy (SEM) of the microparticles at 3800-fold magnification. The microphotography shows that the microparticles have an almost spherical shape with shallow depressions on their surfaces but with no visible pores.

Example 2

[0407] The process was carried out as described for example 1 except for the homogenization, which was carried out at 10.000 rpm for 3 minutes.

[0408] The mean particle diameter D[v, 0.5] determined from the thus obtained aqueous suspension was 3.5 μm, the D[v, 0.1] was 1.1 μm and the D[v, 0.9] was 8.9 μm.

[0409] FIG. 2 shows a microphotography of the freshly prepared laden microparticles of example 2 after their isolation from the suspension by centrifugation. The microphotography was obtained by scanning electron microscopy of the microparticles at 3000-fold magnification. The microphotography shows that the microparticles have an almost spherical shape with shallow depressions on their surfaces but with no visible pores.

Example 3

[0410] The process was carried out as described for example 2 except for that no defoamer was used.

[0411] The mean particle diameter D[v, 0.5] determined from the aqueous suspension was 2.9 μm, the D[v, 0.1] was 1.1 μm and the D[v, 0.9] was 8.3 μm.

[0412] FIG. 3 shows a microphotography of the freshly prepared laden microparticles of example 3 after their isolation from the suspension by centrifugation. The microphotography was obtained by scanning electron microscopy of the microparticles at 3600-fold magnification. The microphotography shows that the microparticles have an almost spherical shape with shallow depressions on their surfaces but with no visible pores.

Example 4

[0413] The process was carried out as described for example 2 except for that an alternative dispersant 1 (Blindzil 50/80 and culminal M HPC 400 R) was used in the step ii) instead of polyvinyl alcohol and no defoamer was used. Thereby, pH was adjusted by addition of citric acid to improve the efficiency of the alternative dispersant system. Thus, the step ii) of example 4 is carried out as follows:

[0414] ii. 8.1 g of a 50% by weight aqueous solution of the Blindzil 50/80, 0.38 g of a 5% by weight aqueous solution of culminal M HPC 400 R and 415.95 g of deionized water were charged to a 2 L vessel. The pH of the water phase was set to 2.5 by addition of citric acid solution. To this mixture the solution of the polymer composition and the aroma chemical in dichloromethane was added within 30 s with stirring by means of an Ultra Turrax T25 at a rotation speed of 10000 rpm. Then, the mixture was homogenized for 3 minutes by means of the Ultra Turrax at 10000 rpm. The thus obtained o/w emulsion had an average droplet size of less than 15 μm.

[0415] The mean particle diameter D[v, 0.5] determined from the aqueous suspension was 8.1 μm, the D[v, 0.1] was 1.9 μm and the D[v, 0.9] was 12.7 μm.

[0416] FIG. 4 shows a microphotography of the freshly prepared laden microparticles of example 4 after their isolation from the suspension by centrifugation. The microphotography was obtained by scanning electron microscopy of the microparticles at 5000-fold magnification. The microphotography shows that the microparticles have an almost spherical shape with shallow depressions on their surfaces but with almost no visible pores.

Example 5

[0417] The process was carried out as described for example 2 except for that another alternative stabilizer 2 (Reax 910) was used in the step ii) instead of polyvinyl alcohol and no defoamer was used. Thus, the step ii) of example 5 is carried out as follows: ii. 1.35 g of Reax 910 was dissolved in 416.6 g of deionized water and the solution was charged to a 2 L vessel. To this mixture the solution of the polymer composition and the aroma chemical in dichloromethane was added within 30 s with stirring by means of an Ultra Turrax T25 at a rotation speed of 10000 rpm. Then, the mixture was homogenized for 3 minutes by means of the Ultra Turrax at 10000 rpm. The thus obtained o/w emulsion had an average droplet size of less than 15 μm.

[0418] The mean particle diameter D[v, 0.5] determined from the aqueous suspension was 3.3 μm, the D[v, 0.1] was 1.1 μm and the D[v, 0.9] was 10 μm.

[0419] FIG. 5 shows a microphotography of the freshly prepared laden microparticles of example after their isolation from the suspension by centrifugation. The microphotography was obtained by scanning electron microscopy of the microparticles at 4100-fold magnification. The microphotography shows that the microparticles have an almost spherical shape with shallow depressions on their surfaces but with almost no visible pores.

Example 6

[0420] The process was carried out as described for example 2 except for that an alternative polymer system (Dynacoll® 7381) was used in the step i) instead of PCL and PBSeT, and no defoamer was used. Thus, the step i) of example 1 is carried out as follows:

[0421] i. In a glass vessel 5.4 g of the aroma chemical, 21.6 g Dynacoll® 7381 were dissolved at room temperature in 270 g of dichloromethane with stirring until a clear solution of the polymer composition and the aroma chemical in dichloromethane was obtained.

[0422] The mean particle diameter D[v, 0.5] determined from the aqueous suspension was 6 μm, the D[v, 0.1] was 1.3 μm and the D[v, 0.9] was 8.9 μm.

[0423] FIG. 6 shows a microphotography of the freshly prepared laden microparticles of example 6 after their isolation from the suspension by centrifugation. The microphotography was obtained by scanning electron microscopy of the microparticles at 5100-fold magnification. The microphotography shows that the microparticles have an almost spherical shape with some shallow depressions on their surfaces but with almost no visible pores.

[0424] Following table 2 summarizes important ingredients used in step i) and ii) and results of examples 1 to 6.

TABLE-US-00002 TABLE 2 Step Exp. 1 Exp. 2 Exp. 3 Exp. 4 Exp. 5 Exp. 6 i) Polymer PCL + PBSeT PCL + PBSeT PCL + PBSeT PCL + PBSeT PCL + PBSeT Dynacoll ® 7381 Aroma aroma chemical aroma chemical aroma chemical aroma chemical aroma chemical aroma chemical chemical of table 1 of table 1 of table 1 of table 1 of table 1 of table 1 ii) Dispersant polyvinyl alcohol polyvinyl alcohol polyvinyl alcohol Bindzil 50/80 + Reax ® 910 polyvinyl alcohol culminal MHPC 400 R Defoamer Defoamer given Defoamer given No defoamer No defoamer No defoamer No defoamer in materials in materials Homoge- No carried out at carried out at carried out at carried out at carried out at carried out at nization homoge- 10.000 rpm for 10.000 rpm for 10.000 rpm for 10.000 rpm for 10.000 rpm for 10.000 rpm for nization 3 min. 3 min. 3 min. 3 min. 3 min. 3 min. Result almost almost almost almost almost almost (SEM) spherical shape spherical shape spherical shape spherical shape spherical shape spherical shape shallow shallow shallow shallow shallow some shallow depression depression depression depression depression depression no visible pore no visible pore no visible pore no visible pore no visible pore no visible pore