Method for producing porous particles of polyhydroxyalkanoate (PHA), porous particles obtainable by said method and cosmetic composition containing same

Abstract

The present invention relates to a method for producing porous particles of polyhydroxyalkanoate (PHA), comprising the steps of: providing a spray-drying atomization chamber heated to an operating temperature between 50°C and 300°C; providing an aqueous suspension containing the PHA and a swelling agent that decomposes at the operating temperature of the atomization chamber to form at least one gaseous compound; and injecting the aqueous suspension into the atomization chamber provided at the operating temperature, thereby causing instantaneous evaporation of the aqueous suspension and decomposition of the swelling agent, resulting in the formation of the porous PHA particles. The particles obtained by the method can be used to obtain cosmetic compositions that are pleasant to the touch, have high oil absorption capacity, and high fluidity, and can produce a uniform filling effect on wrinkles and skin grooves, making the skin more radiant and compact.

Description

[Technical field]

[0001] The present invention relates to a method for producing porous particles of polyhydroxyalkanoates (PHA), in particular to a method for producing porous particles of polyhydroxyalkanoates (PHA) by means of atomization (spray drying); to the porous particles obtainable by this method and to cosmetic compositions comprising said particles. [Background technology]

[0002] Polymers represent a class of products that are widely used in cosmetics, especially in the preparation of emulsions, creams and suspensions for the skin. For example, hydrophilic polymers are used as rheology modifiers and thickeners in oil-in-water emulsions, as well as stabilizers, emulsifiers and moisturizers.

[0003] When these polymers are used in the form of fine powder, another function that they may fulfill is that of a texturizing agent (also called skin feel enhancer), i.e. an agent that improves the tactile sensation felt by the consumer when applying the product to the skin.The function of these agents is in fact to improve the flowability and spreadability of the product, reduce the oily sensation on the skin, and thus make the consumer feel more comfortable when applying the product, giving the consumer the sensation of a "rich" formulation, which is more suitable for its intended purpose.In other words, the texturizing agent must ensure that the consistency of the cosmetic product is improved, that it has good properties of flowability, and that it reduces the oiliness of the skin.

[0004] The texturing agents incorporated into the cosmetic product are selected depending on the type of cosmetic product to be produced (hydrogel, lipogel, emulsion, etc.) and may be polymeric compounds such as nylon, polymethyl methacrylate (PMMA), polyurethane, silicone, etc., or inorganic compounds such as silica, talc, boron nitride, borosilicate, etc.

[0005] Patent application WO2018 / 178899, filed in the name of the same applicant, concerns the use of polyhydroxyalkanoates (PHA) added in the form of particles obtained by spray drying as a texturizing agent in cosmetics. In particular, WO2018 / 178899 describes a cosmetic composition comprising: 70% to 99.9% by weight of a cosmetically acceptable base formulation constituting an oily phase; 0.1% to 30% by weight of at least polyhydroxyalkanoates (PHA) in the form of particles with a mean diameter (d50) of 0.1 μm to 100 μm; these percentages are expressed relative to the total weight of the composition. The PHA in particulate form acts as a texturizing agent, giving consistency to said cosmetic composition, improving its flowability during application and reducing the sensation of oiliness on the skin. The PHA particles in fact have the capacity to absorb oily substances, minimizing the effect of oiliness. They absorb the excess sebum secreted by the skin, thereby reducing the shine of the skin. The PHA particles also contribute to the so-called "soft focus" effect, i.e. they have the effect of filling wrinkles and skin grooves evenly, making the skin look more radiant and compact. Summary of the Invention [Problem to be solved by the invention]

[0006] The applicant was faced with the challenge of improving the capacity of the PHA particles to absorb oily substances in order to further reduce the unpleasant sensation of greasiness on the skin and ensure a more pronounced "soft focus" effect, without adversely affecting the flowability of the product. [Means for solving the problem]

[0007] The Applicant has now found that this problem, and others as better exemplified herein, can be solved using a method for producing porous particles of polyhydroxyalkanoates (PHA) by means of atomization (spray drying) in the presence of a swelling agent, as better defined herein. [Brief description of the drawings]

[0008] [Figure 1] 1A-1D show particles produced by the method according to the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] According to a first aspect, the present invention therefore provides a method for producing a method for treating a cancer comprising the steps of: - providing a spray-drying atomization chamber heated to an operating temperature comprised between 50°C and 300°C; - providing an aqueous suspension comprising the PHA and a swelling agent that decomposes at the operating temperature of the atomization chamber with formation of at least one gaseous compound; - injecting said aqueous suspension into an atomization chamber provided at said operating temperature, thereby causing instantaneous evaporation of said aqueous suspension and decomposition of said blowing agent, with the formation of said porous PHA particles. The present invention relates to a method for producing porous particles of polyhydroxyalkanoate (PHA), comprising:

[0010] In the context of this specification and the appended claims, "expansion agent" refers to a substance capable of thermally decomposing with the production of at least one gaseous substance, thereby causing the formation of pores in a polymeric material.

[0011] Preferably, the operating temperature of the atomization chamber is between 100°C and 200°C.

[0012] According to the objectives of the present invention, said swelling agent is preferably a carbonate or bicarbonate of an alkali metal or alkaline earth metal, or of ammonium. Even more preferably, said swelling agent is selected from ammonium bicarbonate, ammonium carbonate, sodium bicarbonate, calcium carbonate, magnesium carbonate, or mixtures thereof. Ammonium bicarbonate is especially preferred.

[0013] In the method according to the invention, the PHA is preferably present in the aqueous suspension at a concentration comprised between 1% w / v and 50% w / v, more preferably between 1% w / v and 50% w / v, % being expressed by weight relative to the total volume of the suspension. The swelling agent is preferably present in the aqueous suspension at a concentration comprised between 0.5% w / v and 30% w / v, more preferably between 1% w / v and 25% w / v, % being expressed by weight relative to the total volume of the suspension.

[0014] As is known, atomization by spray drying is the conversion of solids in suspension in a liquid medium, usually an aqueous medium, into a dry product in the form of particles with a controlled particle size distribution. Such a process generally involves the injection of a liquid suspension under high pressure into an atomization chamber, in particular into a distribution ring, which is provided with a number of nozzles from which the suspension leaves in the form of minute droplets. When these droplets are injected with hot gas, typically air or nitrogen, the liquid evaporates almost instantly and dry particles are formed which are collected at the bottom of the device. Further details are described, for example, in the manual "Handbook of Industrial Drying" by Arun S. Mujumdar, CRC Press, 4th Edition (2014).

[0015] The particles produced by the method according to the invention, as can be seen in the attached Figures 1A-1D, have a porous structure, and in some cases may have cavities and even through-holes, forming substantially toroidal porous particles, which further improves the absorption capacity of oily substances and modifies the light reflection properties, as better illustrated in the embodiments described below.

[0016] A second aspect of the invention concerned porous particles of polyhydroxyalkanoates (PHA) obtainable by means of the process described above.

[0017] As is known, polyhydroxyalkanoates (PHAs) are polymers produced by microorganisms isolated from natural environments or genetically modified microorganisms, and are characterized by high biodegradability. They are produced and accumulated by various species of bacteria under unfavorable growth conditions and in the presence of an excess of carbon sources. PHAs are synthesized and accumulated by about 300 different microbial species, including more than 90 species of Gram-positive and Gram-negative bacteria, such as Bacillus, Rhodococcus, Rhodospirillum, Pseudomonas, Alcaligenes, Azotobacter, and Rhizobium.

[0018] Within cells, PHA is stored in the form of microgranules, the size and number of which vary among different species, and when viewed under an electron microscope, appear as refractive inclusions with diameters of 0.2-0.7 μm.

[0019] For the purposes of the present invention, the PHA obtained from the microbial synthesis in the form of an aqueous suspension is subjected to an atomization process via a spray dryer.

[0020] From the process according to the invention it is possible to obtain porous PHA particles with a mean diameter (d50) preferably between 1 μm and 150 μm, more preferably between 3 μm and 30 μm. The porous particles of PHA according to the invention generally have a low polydispersity of particle size distribution, which can be calculated as the "span", i.e. the ratio (d90-d10) / d50, where d90 is the diameter value at which 90% by weight of the particle population is found, d10 is the diameter value at which 10% by weight of the particle population is found and d50 is the diameter value (median value) at which 50% by weight of the particle population is found. Such a ratio (span) preferably has a value of 1 to 3.

[0021] In the context of this specification and the appended claims, "average particle size" is, unless otherwise indicated, the diameter d50 (median value), i.e. the value of the diameter below which 50% by weight of the particle population is located (see "A Guidebook to Particle Size Analysis" published by Horiba Instruments Inc. - 2016, available at https: / / www.horiba.com / fileadmin / uploads / Scientific / eMag / PSA / Guidebook / pdf / PSA_Guidebook.pdf). It can be determined by laser diffraction methods according to ISO 13320:2009.

[0022] As regards said PHA, this is preferably a polymer comprising repeat units of the formula: -O-CHR1-(CH2) n -CO- (I) During the ceremony: R1 is selected from the following: C1-C4 alkyl, optionally substituted with at least one group selected from halogen (F, Cl, Br), -CN, -OH, -COOH, -OR, -COOR (R = C1-C4 alkyl, benzyl). 12 Alkyl, C4-C 16 Cycloalkyl, C2-C 12 Alkenyl; n is 0 or an integer from 1 to 6, preferably 1 or 2.

[0023] Preferably, R1 is methyl or ethyl and n is 1 or 2.

[0024] PHAs can be either homopolymers, copolymers or terpolymers. In the case of copolymers or terpolymers, they can consist of different repeat units of formula (I) or at least one repeat unit of formula (I) in combination with at least one repeat unit derived from a comonomer copolymerizable with hydroxyalkanoates, such as lactones or lactams. In the latter case, the repeat unit of formula (I) is present in an amount corresponding to at least 10% by mole, relative to the total number of repeat units.

[0025] Particularly preferred repeat units of formula (I) are those derived from: 3-hydroxybutyrate, 3-hydroxyvalerate, 3-hydroxyhexanate, 3-hydroxyoctanoate, 3-hydroxyundec-10-enoate, 4-hydroxyvalerate.

[0026] Particularly preferred PHAs are: poly-3-hydroxybutyrate (PHB), poly-3-hydroxyvalerate (PHV), poly-3-hydroxyhexanate (PHH), poly-3-hydroxyoctanoate (PHO), poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), poly(3-hydroxybutyrate-co-3-hydroxyhexanate) (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), polyhydroxybutyrate-hydroxyvalerate copolymer, or mixtures thereof.

[0027] For the purposes of the present invention, the PHA is preferably a homopolymer, copolymer or terpolymer, more preferably a homopolymer, and even more preferably polyhydroxybutyrate (PHB).

[0028] Preferably, the PHA has a weight average molecular weight (M) in the range of 10,000 to 1,000,000 Da. w )(Mw).

[0029] As regards the production of PHA, this is preferably obtained from the microbial fermentation of an organic substrate (e.g. carbohydrates or other fermentable substrates such as glycerol) using a strain of a microorganism capable of producing PHA, followed by recovery of said PHA from the cell mass. For further details, see, for example, patent applications WO99 / 23146, WO2011 / 045625 and WO2015 / 015315. Substrates suitable for the production of PHA by fermentation can in particular be obtained from the processing of plants, such as juice, molasses, pulp obtained from the processing of sugar beets and sugar cane. These substrates contain, in addition to carbohydrates such as sucrose, organic growth factors, which are nutrients necessary for the growth of cells, and minerals such as nitrogen and phosphorus. There is also glycerol, a low-cost organic carbon source, as a by-product of biodiesel production, which can also be used in a mixture with levulinic acid (see, for example, US Patent 8 956 835 B2).

[0030] According to a preferred embodiment of the invention, the particles produced by the method according to the invention have a bulk density value, measured by means of the method described in the European Pharmacopoeia 7.0-2.9.34, comprised between 0.1 g / ml and 0.5 g / ml, preferably between 0.2 g / ml and 0.4 g / ml.

[0031] The bulk density of a particulate sample is the ratio of the uncompressed mass of the sample to its volume, including the volume of voids between the particles. The bulk density therefore depends on the actual density of the product and on the packing of the particles that make up the sample. The bulk density is expressed in grams per ml (g / ml) and is measured at room temperature (20°C).

[0032] Preferably, the particles according to the invention have a value of tap density, measured by means of the method described in the European Pharmacopoeia 7.0-2.9.34, comprised between 5% and 15%, preferably between 9% and 11%.

[0033] As described in the method, the tap density is the density measured after compressing the particles, obtained by tapping a container containing a sample of the particles. The measurement is carried out at ambient temperature (20° C.).

[0034] As can be seen better in the examples given below, the particles produced by the method according to the invention advantageously have significantly lower tapped and bulk density values ​​than similar particles substantially free of porosity and cavities. In practice, these values ​​characterize light-feeling volatile particles with high flowability.

[0035] Furthermore, advantageously according to a preferred embodiment of the present invention, said particles have an oil (linseed oil) absorption value, measured according to ISO 787-5:1980, preferably comprised between 1 ml / g and 4 ml / g, preferably between 1.2 ml / g and 2.2 ml / g, where ml / g is the amount of absorbed oil expressed in ml per gram of particle.

[0036] In cosmetics, shiny, light-reflecting skin is an indication of greasy or oily (hyperseborrheic) skin and is perceived as unpleasant. The ability of the particles produced by the method according to the invention to absorb oily substances may be advantageously used, for example, in skin cleansing products to remove excess skin sebum. The particles produced by the method according to the invention may be advantageously used, for example, to remove excess skin sebum by the combined mechanical action of the hands and the particles, or in cosmetics (make-up) that take advantage of their sebum absorption ability to ensure a matte effect even in the presence of sebum and / or sweat.

[0037] Therefore, determination of the oil (linseed oil) absorption value of a particle is generally required to estimate the potential sebum absorption effect of the product when spread on the skin.

[0038] The appearance of skin wrinkles is the most noticeable sign of skin aging. Wrinkles are defined as lines, slight grooves or creases in the skin at the points of thinning. Generally, wrinkles appear in various areas of the face, such as under the eyes, on the forehead, around the lips, etc.

[0039] Advantageously, the particles according to the invention have a softening / filling effect when applied to the skin.

[0040] The first thing that becomes apparent is the effect of filling empty spaces. To better understand the optical properties associated with the particles of the invention, let us assume that the incident light (for example at an angle of incidence of 30°) does not hit the wrinkle from the front, but from the side. The cone of light that the profile of the illuminated edge necessarily creates is hidden, since the particle morphology does not allow direct reflection of the light, but scatters it in various directions. Moreover, the refractive index (IR) of the PHA is similar to that of the stratum corneum of the skin (IR=1.55), which means that the light refracted by the particles will resemble the color of the skin.

[0041] According to another aspect, the present invention relates to a cosmetic composition comprising porous particles of polyhydroxyalkanoates (PHA) obtainable by means of a process as described above, and a cosmetically acceptable base formulation.

[0042] Preferably, the cosmetically acceptable base formulation comprises an oily phase, preferably present in an amount between 50% and 100% by weight, more preferably in an amount of 70% to 90% by weight, relative to the weight of the cosmetically acceptable base formulation.

[0043] Preferably, the oily phase consists of at least one fatty substance, generally of vegetable, mineral or synthetic origin, which may be in liquid form (oil) or solid form (wax) at ambient temperature (25°C). Preferably, the oily phase consists of at least a non-volatile oil that provides an emollient effect on the skin. "Non-volatile oil" refers to a fatty substance that is liquid at room temperature (25°C), that can remain on the skin for at least one hour after application, and in particular that has a vapor pressure at atmospheric pressure at 25°C of 0.01 mmHg (1.33 Pa) or less.

[0044] Typically, the oily phase is composed of hydrocarbon-based, silicon-based or fluorinated compounds, especially fatty acids, fatty alcohols, fatty acid esters, such as: cetearyl isononanoate, isotridecyl isononanoate, isopropyl isostearate, isopropyl myristate, cetearyl isononanoate, isotridecyl isononanoate, isostearyl isostearate, isopropyl isostearate, isopropyl myristate, isopropyl palmitate, butyl stearate, ethyl laurate, isononyl isononanoate. glycerol or triglyceride triisostearate, tocopheryl acetate, myristic acid, palmitic acid, stearic acid, behenic acid, oleic acid, linoleic acid, linolenic acid, isostearic acid, dimethicone, decanoic acid / capric acid triglyceride, oleyl alcohol, avocado oil, camellia oil, castor seed oil, macadamia nut oil, turtle oil, mink oil, soybean oil, grape seed oil, sesame oil, corn oil, rapeseed oil, sunflower oil, cotton seed oil, jojoba oil, peanut oil, olive oil, and mixtures thereof.

[0045] Mineral oils may also be used, although these are less preferred from an environmental standpoint, such as light paraffin, squalene, petroleum gel, and mixtures thereof.

[0046] The oily phase may also contain at least a volatile oil, which is a fatty substance that is liquid at room temperature (25° C.) and that evaporates within one hour after application to the skin, and in particular has a vapor pressure at atmospheric pressure at 25° C. of at least 0.01 mmHg (1.33 Pa), generally at most 300 mmHg (40,000 Pa). The volatile oil may be, for example, a silicone oil, and contributes to reducing the oiliness of the fatty phase.

[0047] The cosmetically acceptable base formulation may also contain an aqueous phase, preferably present in an amount of up to 50% by weight, more preferably between 10% and 30% by weight relative to the weight of the base formulation. In addition to water, the aqueous phase may contain water-miscible products, such as primary and secondary alcohols (e.g., ethanol or isopropanol); polyols (e.g., glycerol, propylene glycol, butylene glycol, dipropylene glycol, diethylene glycol); glycol ethers (e.g., mono-, di- or tri-propylene glycol); mono-, di- or tri-ethylene glycol-C1-C4-alkyl ethers; carboxylic acids (e.g., benzoic acid); or mixtures thereof.

[0048] The aqueous phase may also contain stabilizers such as sodium chloride, aluminum oxide, magnesium dichloride, magnesium sulfate, zinc dichloride, and the like.

[0049] The aqueous phase may also contain other products that are compatible with the aqueous phase, such as gelling agents, filming agents, thickening agents, surfactants, and mixtures thereof.

[0050] The cosmetically acceptable base formulation may also contain other products commonly used in cosmetics and having a purely pharmaceutical function, depending on the particular product being prepared, such as, for example: Anionic, cationic, amphoteric or nonionic surfactants, which disperse the aqueous phase in the oily phase or vice versa, in order to obtain stable water-in-oil or oil-in-water emulsions; Preservatives, such as parabens and phenoxyethanol; Thickening agents such as gums and waxes, for example, hydroxypropyl guar, carrageenan, hydroxyethyl cellulose, xantham gum, guar gum, beeswax, candelilla wax, ceresin; Chelating agents, such as ethylenediaminetetraacetic acid (EDTA). Colour formers and pigments.

[0051] The cosmetically acceptable base formulation may also contain at least active ingredients with specific biological activity, for example: Hydrant and nutrients, such as amino acids or proteins (glycine, alanine, threonine, citrulline, serine, casein, elastin), alpha-hydroxy acids, sugars (lactose, mannose, fructose, galactose, pectin), vitamins (e.g. vitamin A, D or E); Astringents, for example, aluminium salts; Preservatives, such as trichlorocarbanilide (TCC), dichlorophen, bromochlorophenol, essential oils; Anti-inflammatory and anti-irritant agents, such as bisabolol, dipotassium glycyrrhizinate, rosemary extract; Antibacterial, bacteriostatic, bactericidal, fungicidal or antifungal agents, for example zinc salts; Anti-cellulite agents, such as caffeine or its derivatives, escin, lecithin, carnitine; Antiseborrheic agents, such as iminodibenzyl or fluorene derivatives, glucuronic acid, niacinamide, salicylic acid; Keratolytic or desquamating agents, such as alpha-hydroxy acids, beta-hydroxy acids, alpha-keto acids, beta-keto acids, retinoids; Opathic agents, such as clay, kaolin, antilipase agents, ethyl lactate; Anti-wrinkle agents, such as proteins and their hydrolysates, collagen, hyaluronic acid; Antioxidants such as butylated hydroxytoluene (BHT), butylated hydroxyanisole (BHA), propyl gallate, octyl gallate, carotenoids (including β-carotene, lycopene or canthaxanthin), ubiquinone, vitamin E, vitamin C; Anti-free radical agents, e.g., vitamin E, caffeine, mannitol, enzymes; Sun filters (including agents, pigments and nanopigments that absorb UV-A and / or UV-B rays); Vasoconstrictors; microcirculation reactivator; Decongestants; deodorants, perfumes and antiperspirants; 13. Depilatories, such as Thioglycols and Thiolactates.

[0052] The cosmetic composition according to the invention can be used to prepare a wide range of cosmetic products, including, inter alia: Facial makeup products, such as foundation, eyeshadow, mascara, eyeliner, lipstick, etc.; Face and body care products, such as creams, milks, lotions, detergents, deodorants, antiperspirants, shaving products, depilatories, etc.; Hair care products, such as shampoos, gels, anti-dandruff products, products for hair loss control, hair dye products and bleach products, etc.; Perfumes, especially milk and cream.

[0053] The following embodiment examples are provided solely for the purpose of illustrating the invention and should not be understood as limiting the scope of protection defined by the appended claims. EXAMPLES

[0054] [Example 1: Method for producing porous particles of PHB by means of atomization (spray drying)] The atomization chamber of the spray dryer was heated to a temperature of 200° C. An aqueous suspension of 20% w / v PHB was prepared, the percentage being expressed by weight relative to the total volume of the suspension. Ammonium bicarbonate was added to the suspension in an amount of 10% w / v, the percentage being expressed by weight relative to the total volume of the suspension. Ammonium bicarbonate decomposes at 35° C. to produce carbon dioxide and ammonia, and therefore acts as a blowing agent according to the present invention.

[0055] A PHB suspension containing ammonium bicarbonate was nebulized from an injection nozzle in an atomization chamber. Droplets of the PHB suspension were obtained by nebulization. When an air stream at 200 °C was applied to the dropped PHB suspension, the water in the suspension evaporated instantly and the ammonium bicarbonate decomposed to generate carbon dioxide and ammonia. The generation of these gases led to the formation of the porous and hollow structure of the PHB particles. Figures 1A-1D show the PHB particles obtained according to the described process (micrographs obtained with a SEM electron microscope).

[0056] [Example 2: Characterization of the particles in Example 1] (Apparent density) The analysis to determine the bulk density of the particles in Example 1 was carried out in triplicate. The particles in Example 1 were sieved using a sieve with a 1.0 mm mesh. 50 g of the particles in Example 1 were slowly poured into a 250 mL graduated glass cylinder (tolerance ±2 mL). The analysis was carried out according to the method labelling of "European Pharmacopoeia 7.0-2.9.34". Table 1 shows the average value of the three analyses carried out. The bulk density is expressed in grams of particles in milliliters of the volume occupied by the particles (g / mL), and the bulk density value is expressed in relation to the average diameter (d50) of the particles analysed.

[0057] [Table 1]

[0058] Table 2 shows the bulk density values ​​obtained by analyzing samples of PHB particles obtained by spray drying using the same procedure as described in Example 1, but without the swelling agent (ammonium bicarbonate).

[0059] [Table 2]

[0060] Comparing the values ​​in the two tables it becomes clear how the particles obtained from the process according to the invention are characterized by a low bulk density.

[0061] (Tap density) The analysis to determine the tap density of the particles in Example 1 was carried out in triplicate. The particles in Example 1 were sieved using a 1.0 mm mesh sieve. 50 g of the particles in Example 1 were slowly poured into a 250 mL graduated glass cylinder (tolerance ±2 mL). The analysis was carried out according to the method labelling of "European Pharmacopoeia 7.0-2.9.34". Table 3 shows the average value of the three analyses carried out; the tap density is expressed as a percentage obtained by the following formula:

number

[0062] [Table 3]

[0063] Table 4 shows the tap density values ​​obtained by analyzing samples of PHB particles obtained by spray drying using the same procedure as described in Example 1, but without the swelling agent (ammonium bicarbonate).

[0064] [Table 4]

[0065] Comparing the values ​​in the two tables it becomes clear how the particles obtained from the process according to the invention are characterized by a low tap density.

[0066] (Oil absorption (linseed oil)) The analysis to determine the oil absorption value of the particles in Example 1 was carried out in duplicate according to standard ISO 787-5:1980.

[0067] The analysis was carried out on a circular concave glass support, approximately 17 cm in diameter, on which 1 g of particles from Example 1 was weighed. Periodically, 4 / 5 drops of linseed oil were added to the particles using a 10 mL burette (measurement error equal to 0.02 mL) to obtain a compact, smooth, non-sticky paste without lumps or cracks. Oil was then added drop by drop until the consistency required by the standard was reached. After each addition of oil, the particles were carefully mixed to ensure proper absorption of the oil.

[0068] The oil absorption values ​​were expressed as milliliters of oil absorbed per gram of particles (mL / g), and the results are shown in Table 5.

[0069] [Table 5]

[0070] Table 6 shows the linseed oil absorption values ​​obtained by analyzing samples of PHB particles obtained by spray drying using the same procedure as described in Example 1, but without the swelling agent (ammonium bicarbonate).

[0071] [Table 6]

[0072] Comparing the values ​​in the two tables, it can be seen that there is a net increase in oil absorption values ​​with the particles obtained by the method according to the invention compared to non-porous and non-hollow particles of the same particle size (d50).

[0073] A similar analysis was performed to assess the absorption capacity of another oil, isopropyl myristate.

[0074] The oil absorption values ​​were expressed as milliliters of oil absorbed per gram of particles (mL / g), and the results are shown in Table 7.

[0075] [Table 7]

[0076] Table 8 shows the absorption values ​​of isopropyl myristate obtained by analyzing samples of PHB particles obtained by spray drying using the same procedure as described in Example 1, but without the swelling agent (ammonium bicarbonate).

[0077] [Table 8]

[0078] Comparing the values ​​in the two tables, it can be seen that the particles obtained by the method according to the invention have a net increase in oil absorption value compared to non-porous and non-hollow particles of the same particle size (d50).

[0079] Example 3: Cosmetic composition containing the particles in Example 1 Table 9 shows the cosmetically acceptable base formulations used to prepare the cosmetic compositions. The amounts are expressed as %p / p based on the total weight of the composition.

[0080] [Table 9]

[0081] After weighing, both the aqueous phase, composed of water and Sepigel 305, and the oily phase, composed of 99 and Montanov 68, were heated to a temperature of 80°C. Once the required temperature was reached and the substances were in a liquid state, the two phases were combined and homogenized with a turbo emulsifier at 3200 rpm for 5 minutes. The emulsion thus obtained was slowly cooled to a temperature of 40°C. Benzyl alcohol (preservative) was then added. The particles of Example 1 were added to this formulation in an amount equivalent to 2% p / p, where % is expressed as a percentage of the total weight of the cosmetic composition.

[0082] Example 4: Gloss index of the cosmetic composition in Example 3 In cosmetics, the analysis for determining the gloss index is used to characterize cosmetic compositions containing particles, each of which may in fact interact differently with visible light, according to its own chemical and physical characteristic properties.

[0083] The gloss index refers to a value obtained by using a glossmeter, which is an instrument that can measure the reflection of light, i.e., the intensity of light defined within a limited area around the same angle of reflection as the incident light.

[0084] The gloss index is measured according to standard BS EN ISO 2813:2014. A low index corresponds to a cosmetic composition that is able to cause diffraction of light rather than reflection, thereby creating an even and filling effect on wrinkles and skin grooves, contributing to making the skin more radiant and compact.

[0085] The gloss index was determined by measuring a film of the cosmetic composition of Example 3, 150 μm thick, spread on a sheet of Byk Chart gloss paper (Byk-Gardner, Germany) using a film applicator (Byk-Gardner, Germany) with a gloss meter. The analysis was carried out 2 hours after the film was spread on the sheet of paper. The gloss meter (Micro-TRI-gloss, Byk-Gardner, Germany) was set at an incidence angle of 60°, then 85°. The gloss index shown in Table 10 is the average result of 5 measurements taken at different points on the film for different particle sizes (d50). The gloss index is expressed as the average value and its standard deviation (STD) by choosing an incidence angle of 60° for the first measurement, and if the value was less than 10 GU (gloss units), the measurement was repeated at an incidence angle of 85°.

[0086] [Table 10]

[0087] Table 11, on the other hand, shows the gloss index values ​​obtained analyzing a cosmetic composition consisting of PHB particles that are porous and non-hollow (and therefore not obtained by the method according to the invention).

[0088] [Table 11]

[0089] From the analysis of the results obtained at 60°, comparing the composition without particles with the composition of Example 3, it is possible to see a gradual decrease in the gloss index as the particle size (d50) increases.

[0090] In conclusion, the particles according to the invention can be used to obtain cosmetic compositions that are pleasant to the touch, have a high oil absorption and are highly fluid, and can create a uniform filling effect on wrinkles and skin grooves, making the skin more lustrous and compact.

Claims

1. A method for producing porous particles of polyhydroxyalkanoate (PHA) comprising: - providing a spray-drying atomization chamber heated to an operating temperature comprised between 50°C and 300°C; a step of: - the PHA decomposes at the operating temperature of the atomization chamber to produce at least one gaseous compound; providing an aqueous suspension comprising a swelling agent with which the product is formed; - injecting said aqueous suspension into an atomization chamber provided at said operating temperature, thereby The aqueous suspension is evaporated instantaneously and the swelling agent is decomposed, so that the porous PHA particles are A process involving formation.

2. The swelling agent may be a carbonate or salt of an alkali or alkaline earth metal or of ammonium. or bicarbonate.

3. The leavening agent is ammonium bicarbonate, ammonium carbonate, sodium bicarbonate, carbonate 3. The composition of claim 2, wherein the inorganic filler is selected from calcium carbonate, magnesium carbonate, or a mixture thereof. How to.

4. The operating temperature of the atomization chamber is between 100° C. and 200° C.

2. The method according to any one of claims 1 to 11.

5. The PHA is present in the aqueous suspension at a concentration comprised between 1% w / v and 50% w / v. (wherein the percentages are expressed by weight relative to the total volume of the suspension) 2. The method according to any one of claims 1 to 11.

6. The PHA is present in the aqueous suspension at a concentration between 15% w / v and 25% w / v. % is expressed by weight relative to the total volume of the suspension. Method of posting.

7. The swelling agent is present in the aqueous suspension at between 0.5% and 30% w / v. %, wherein the percentage is expressed by weight relative to the total volume of the suspension.

7. The method according to any one of claims 6 to 6.

8. The swelling agent is present in the aqueous suspension at a concentration between 1% w / v and 25% w / v. (wherein the percentages are expressed by weight relative to the total volume of the suspension) How to.

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