PROCESSES FOR PRODUCING PARTICLES OF AT LEAST ONE POLYHYDROXYALKANOATE (PHA)

Abstract

A process for producing particles of at least one polyhydroxyalkanoate (PHA), the particles having an average diameter (d50) greater than or equal to 0.1 μm and less than or equal to 100 μm, may include: providing an aqueous suspension of the at least one PHA; and subjecting the aqueous suspension of the at least one PHA to a process of atomization by spray drying. A process for producing particles of at least one PHA, the particles having an average diameter (d50) greater than or equal to 0.1 μm and less than or equal to 100 μm, may include: atomizing an aqueous suspension of the at least one PHA by spray drying the aqueous suspension.

Claims

1-17. (canceled)

18. A process for producing particles of at least one polyhydroxyalkanoate (PHA), the particles having an average diameter (d50) greater than or equal to 0.1 microns (μm) and less than or equal to 100 μm, the process comprising: providing an aqueous suspension of the at least one PHA; and subjecting the aqueous suspension of the at least one PHA to a process of atomization by spray drying.

19. The process of claim 18, wherein the process of atomization by spray drying comprises: passing the aqueous suspension of the at least one PHA into a distribution ring, wherein the distribution ring is provided with a plurality of nozzles from which the aqueous suspension of the at least one PHA comes out in a form of micro-droplets; and impinging the micro-droplets using a jet of hot gas to form the particles of the at least one PHA.

20. The process of claim 19, wherein the hot gas comprises air.

21. The process of claim 19, wherein the hot gas comprises nitrogen.

22. The process of claim 18, wherein the at least one PHA comprises particles having a spherical shape.

23. The process of claim 18, wherein the particles of the at least one PHA have the average diameter (d50) greater than or equal to 1 μm and less than or equal to 50 μm.

24. The process of claim 18, wherein the particles of the at least one PHA have the average diameter (d50) greater than or equal to 5 μm and less than or equal to 30 μm.

25. The process of claim 18, wherein the particles of the at least one PHA have a value of (d90−d10)/d50 ratio (span) greater than or equal to 1.0 and less than or equal to 2.5.

26. The process of claim 18, wherein the particles of the at least one PHA have a measured value of surface area, using the Brunauer-Emmett-Teller (BET) method, greater than or equal to 0.5 m.sup.2/g and less than or equal to 20 m.sup.2/g, according to International Organization for Standardization (ISO) standard ISO 9277:1995.

27. The process of claim 18, wherein the particles of the at least one PHA have a measured value of surface area, using the Brunauer-Emmett-Teller (BET) method, greater than or equal to 1 m.sup.2/g and less than or equal to 10 m.sup.2/g, according to International Organization for Standardization (ISO) standard ISO 9277:1995.

28. The process of claim 18, wherein the particles of the at least one PHA have a measured value of oil absorption (linseed oil) greater than or equal to 30 g of oil/100 g of polymer and less than or equal to 300 g of oil/100 g of polymer, according to International Organization for Standardization (ISO) standard ISO 787-5:1980.

29. The process of claim 18, wherein the particles of the at least one PHA have a measured value of oil absorption (linseed oil) greater than or equal to 70 g of oil/100 g of polymer and less than or equal to 130 g of oil/100 g of polymer, according to International Organization for Standardization (ISO) standard ISO 787-5:1980.

30. The process of claim 18, wherein the particles of the at least one PHA have a structure in a form of hollow capsules.

31. The process of claim 18, wherein the at least one PHA is selected from: poly-3-hydroxybutyrate (PHB); poly-3-hydroxyvalerate (PHV); poly-3-hydroxyhexanoate (PHH); poly-3-hydroxyoctanoate (PHO); poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV); poly(3-hydroxybutyrate-co-3-hydroxyexanoate) (PHBH); poly(3-hydroxybutyrate-co-4-hydroxybutyrate); poly(3-hydroxyoctanoate-co-3-hydroxyundecen-10-enoate) (PHOU); poly(3-hydroxybutyrate-co-3-hydroxyvalerate-co-4-hydroxyvalerate) (PHBVV); or mixtures thereof.

32. The process of claim 18, wherein the at least one PHA has a weight average molecular weight (M.sub.w) greater than or equal to 10,000 Daltons (Da) and less than or equal to 1,000,000 Da.

33. A process for producing particles of at least one polyhydroxyalkanoate (PHA), the particles having an average diameter (d50) greater than or equal to 0.1 microns (μm) and less than or equal to 100 μm, the process comprising: atomizing an aqueous suspension of the at least one PHA by spray drying the aqueous suspension.

34. The process of claim 33, wherein the atomizing of the aqueous suspension of the at least one PHA comprises: forming micro-droplets of the aqueous suspension of the at least one PHA; and impinging the micro-droplets using hot gas to form the particles of the at least one PHA; wherein the hot gas comprises air or nitrogen.

35. The process of claim 33, wherein the atomizing of the aqueous suspension of the at least one PHA comprises: using hot gas to transform the aqueous suspension of the at least one PHA into the particles of the at least one PHA.

36. The process of claim 35, wherein the hot gas comprises air.

37. The process of claim 35, wherein the hot gas comprises nitrogen.

Description

EXAMPLE 1

[0079] An aqueous dispersion of PHA (concentration of about 20% by weight), obtained from the bacterial fermentation process and previously subjected to purification and bleaching, was subjected to atomization with a high pressure spray dryer, in an open loop configuration. The drying gas was air, with an inlet temperature of 200° C. and flow of 1 m.sup.3/min. The PHA powder thus obtained had the following features: [0080] average diameter (d50)=10 μm (ISO 13320:2009) [0081] “span”=(d90−d10)/d50=1.4 (ISO 13320:2009); [0082] absorption of linseed oil=106 g of oil/100 g of polymer (ISO 787-5:1980).

EXAMPLE 2

[0083] The ability to adsorb oily substances by PHA particles prepared according to Example 1 was evaluated.

[0084] The tests were carried out by placing a known amount of PHA in powder, deposited on an aluminum sheet, in contact with the oil, which was added dropwise until the PHA powder was able to absorb it. When it was observed that the mixture exuded oil, the test was terminated and the powder mixture of PHA and oil was weighed, so as to determine the amount of oil absorbed by difference.

[0085] The results are shown in the following Table 1, where the oil adsorbent capacity is measured as grams of oil adsorbed per 100 grams of PHA.

TABLE-US-00001 TABLE 1 ADSORBENT CAPACITY OIL (g/100 g) caprylic/capric triglyceride 174.4 dicapril ether 178.8 paraffin 90.0 dimethicone 82.4

EXAMPLE 3

[0086] The compatibility of the powder PHA of Example 1 with some viscosizing agents commonly used in cosmetic formulations was evaluated.

[0087] The tests were carried out by adding increasing amounts of PHA in powder (Example 1) to the viscosizing agent dispersed in water. The resulting suspension, maintained at a temperature of 25° C., was evaluated by a Brookfield RVT viscometer (speed gradient: 5.0 rpm), equipped with Helipath accessory for Brookfield viscosity measurement. The results are shown in Table 2.

TABLE-US-00002 TABLE 2 PHA Brookfield viscosity Viscosizing agent (% by weight) (mPa .Math. sec) hydroxypropylguar 0 6320 (1% by weight) 1 5880 5 7080 10 13000 carrageenan 0 1502 (1% by weight) 1 1200 5 1328 10 1216 hydroxyethylcellulose 0 936 (1% by weight) 1 800 5 744 10 1880 xanthan gum 0 3760 (0.5% by weight) 1 2272 5 2600 10 5216

[0088] As can be seen from the data shown in Table 2, the addition of the powdered PHA did not lead to an excessive increase in the viscosity of the gel, confirming the high compatibility of the PHA itself with the viscosizing agent.

EXAMPLE 4

[0089] Some lipsticks were prepared with the following base formulation (% by weight with respect to the total weight of the base formulation):

TABLE-US-00003 Ricinus communis seed oil 15.30% diisostearyl maleate 15.00% phenyltrimethicone 5.00% titanium dioxide (CI 77891) 4.00% iron oxides (CI 77491) 3.00% red pigment 57 (CI 15850) 1.00% octyldodecyl ricinoleate 15.00% butylated hydroxytoluene (BHT) 0.10% polyethylene 2.00% Limnanthes alba seed oil 10.00% Butyrospermum parkii butter extract beeswax 6.80% Candelilla wax 9.00% ceresin wax (ozokerite) 6.80% C10-C30 esters of cholesterol/lanosterol 6.50% tocopheryl acetate

[0090] The base formulation was compared to the same formulation admixed with 1% by weight and 3% by weight (with respect to the total weight of the composition) of powdered PHA obtained according to Example 1. With the three different formulations lipsticks in stick were produced, which were evaluated for: [0091] writing characteristics; [0092] breaking load; [0093] drop point.

[0094] The writing characteristics were empirically evaluated by applying the lipstick on the inside of the forearm; the parameters considered were smoothness (absence of friction), homogeneity of the stroke (uniformity of pigmentation) and opacity (ability to cover the skin coloring). The results are shown in Table 3, compared to the base formulation without PHA.

TABLE-US-00004 TABLE 3 Parameter PHA 1% PHA 3% Smoothness improved much improved Homogeneity of the stroke improved much improved Opacity improved much improved

[0095] The breaking load was evaluated empirically by fixing one end of the stick, to which an increasing weight was applied by the gradual filling of a beaker hanging from the median part of the stick by adhesive tape, until the stick itself breaks. A load of about 200-300 g is generally considered satisfactory, while a load of less than 200 g is an indication of stick fragility. Breaking load values above 300 g are generally indicative of poor pastel softness. The results are shown in Table 4.

TABLE-US-00005 TABLE 4 PHA Average breaking load (g) ± (% weight) standard deviation 0 207 ± 19.3 1 132 ± 122.0 (p < 0.05) 3  268 ± 27.9 (p = 0.15)

[0096] As can be seen from the results shown in Table 4, the addition of PHA in small amounts (1% by weight) reduced the mechanical resistance of the stick, while for higher amounts (3% by weight) a significant strengthening was observed.

[0097] The drop point is the temperature at which the stick passes from the semi-solid to the semi-liquid phase and starts to drip (determinable by the AOCS Standard Procedure Cc 18-80 method). Usually it is believed that a drop point between 65° C. and 72° C. is optimal as it avoids excessive softening in conditions of high ambient temperatures, while higher values may indicate poor applicative properties due to excessive hardness at room temperature. The results obtained are shown in Table 5.

TABLE-US-00006 TABLE 5 PHA Drop point (% weight) (° C.) 0 60 1 65 3 68

EXAMPLE 5

[0098] Some mascara composition were prepared with the following base formulation (% by weight with respect to the total weight of the base formulation):

TABLE-US-00007 water 54.65% water, trisodium ethylenediamine 0.30% Disuccinate triethanolamine 1.50% methoxymethylbutanol 3.00% magnesium aluminum silicate 1.50% hydroxyethyl cellulose 0.20% isostearic acid 1.00% butyleneglycol dicaprylate/dicaprate 3.00% stearic acid 3.00% glyceryl stearate SE 1.20% PVP/eicosene copolymer 5.00% microcrystalline wax 4.20% Candelilla wax 4.20% synthetic beeswax 4.20% butylated hydroxytoluene (BHT) 0.05% methyl paraben 0.15% ethylparaben 0.15% polysorbate-20 0.50% black ferrous/ferric oxide (CI 77499) 10.00% phenoxyethanol 0.60% o-cimen-5-ol 0.10% mica 0.50%

[0099] The base formulation was compared to the same formulation admixed with 2% by weight and 4% by weight (with respect to the total weight of the composition) of powdered PHA obtained according to Example 1. The three different mascara formulations were evaluated by Brookfield viscosity measurements at 25° C. as described in Example 3, using two different velocity gradients (2.5 rpm and 5.0 rpm). The results are shown in Table 6.

TABLE-US-00008 TABLE 6 Brookfield Brookfield PHA viscosity @ 2.5 rpm viscosity @ 5.0 rpm (% weight) (mPa .Math. sec) (mPa .Math. sec) 0 290,000 150,000 1 220,000 120,000 3 290,000 150,000

[0100] As can be seen from the results shown in Table 6, small amounts of PHA induced a slight decrease in viscosity, which increased with higher percentages.

[0101] The same mascara compositions were also evaluated empirically and the results of the compositions containing PHA are shown in Table 7, compared with the PHA-free composition.

TABLE-US-00009 TABLE 7 Parameter PHA 2% PHA 4% Macroscopic appearance more shiny and fluid more shiny Voluminizing effect unchanged unchanged Lenghtening effect a little higher higher Drying speed unchanged unchanged Curling effect unchanged higher

[0102] As can be seen from the results shown in Table 7, the introduction of PHA in the mascara composition significantly improves the shine, the lengthening effect and the curling effect thereof, especially with a higher amount of PHA (4% by weight).