Process for preparing spherical polymer particles for cosmetic applications

Abstract

A process for preparing spherical polymer particles of a polymer containing at least two fillers dispersed in a polymer matrix, wherein up to 50% of the particle's weight is made up of the fillers. The process involves melt-blending a polymer matrix containing at least two fillers with a continuous phase and an active ingredient that is not miscible with the polymer matrix to form an emulsion. The emulsion is then extruded, cooled, and a solvent for the continuous phase is added to recover the spherical particles. The fillers can impart different properties to the spherical particles, which can be used, for example, for cosmetic applications, specifically for preventing and / or reducing the signs of skin aging.

Description

Technical Field

[0001] The present invention relates to a process for preparing spherical polymer particles containing at least two mineral fillers dispersed in a polymer matrix, wherein up to 50% of the weight of the particles is constituted by the fillers. The process involves melt-blending a polymer matrix containing at least two fillers with a continuous phase compound and an agent to form an emulsion, cooling, solubilizing the continuous phase, and recovering the spherical particles. The present invention also relates to the use of such spherical polymer particles for cosmetic applications, specifically for preventing and / or reducing signs of skin aging.

[0002] The present invention relates to a process for producing spherical polymer particles containing fillers.

[0003] The subject of the present invention is also the use in the cosmetic field of such spherical polymer particles having biostimulating properties for preventing or reducing signs of skin aging.

Background Art

[0004] Spherical particles as added carriers can be used in various applications including cosmetics, paints, coatings, selective laser sintering, adhesives, waxes, lubricants, and paper.

[0005] Polymers in powder form, particularly in the form of spherical particles having a controlled diameter generally less than 1 mm, preferably less than 100 μm, can improve some properties in several applications. These spherical particles can be used as additives in paints, for example, for coating the floors of sports halls that must have anti-slip properties, and can also be introduced into cosmetics such as sunscreens, creams for body or face care, and makeup remover products. They can also be used in the fields of inks and paper.

[0006] Various techniques are used to control the sphericity of polymer particles.

[0007] Some techniques are used to prepare spherical polymer particles with a diameter of less than 1 micron. For example, it is known that polymer powders such as polyamide powders can be obtained by anionic polymerization of lactams in a soluble state. However, this technique is limited in terms of the properties of the polymer, and controlling the particle size is difficult due to the high reactivity of anionic monomers.

[0008] The published PCT application, International Publication No. 2005 / 000456, discloses a technique used for producing spherical particles made of polyamide. Spherical particles with a size of less than 100 microns were obtained using emulsion polymerization. However, the control of particle size is limited.

[0009] Herve et al.'s U.S. Patent Application Publications 2010 / 009189 and 2009 / 072424 disclose a process that makes it possible to obtain spherical particles with controlled size with respect to polyamides. The process uses the High Inner Phase Emulsion (HIPE) principle, in which the soluble material is the continuous phase. The particles are obtained from a molten blend between polymer particles and a soluble polymer, and the application of mixing energy in the extruder allows for the formation of separate particles of thermoplastic material dispersed in a continuous phase formed by the soluble polymer. The molten blend is cooled, and the particles are separated by the solubilization of the continuous phase. However, these processes are well carried out with respect to polyamides using appropriately developed additives that have the properties of the same polyamide in a hyperbranched form, which are labor-intensive and expensive additives. When the properties of the polymer change, the continuous phase changes, and many drawbacks are faced in still obtaining spherical particles with controlled size.

[0010] U.S. Patent Application Publication No. 2015 / 0147364 discloses a cosmetic composition containing spherical polyamide particles in which a mineral filler is dispersed. The process for preparing the described polyamide particles uses the HIPE principle and appropriate proprietary additives that have the properties of the same polyamide in a hyperbranched form, which are expensive additives obtained through labor-intensive processes.

[0011] The ability to obtain high-volume-fraction dispersed droplets in a low-volume-fraction continuous phase has made HIPE a fascinating technology for use in a wide range of fields, serving as a template for porous materials used in various applications such as organic semiconductors, filter membranes, scaffolds for tissue engineering, food products, and drug delivery systems. In this case, the dispersed droplets are composed of soluble polymers, which are removed after the co-extrusion process, resulting in a porous material. [Overview of the project]

[0012] Despite advances in technology for the controlled production of polymer particles, there is a need to provide a process that can control the shape and size of the particles, which can be applied to different types of polymers and simultaneously allow the particles to have good dispersibility in the polymer matrix and also serve as additives as fillers.

[0013] In pursuing research in this field, the applicant has hereby discovered a unique process for preparing fine spherical polymer particles having a controlled sphere, which is applicable to different types of polymers and ensures that the filler remains dispersed in the polymer matrix.

[0014] Therefore, a first object of the present invention is to provide a process for producing spherical polymer particles that can contain at least two fillers dispersed in a polymer matrix, up to 50%.

[0015] The process of the present invention enables the production of spherical particles from any polymer thermoplastic material, both synthetic and biodegradable, the latter having the advantage of being sustainable.

[0016] Therefore, the present invention relates to a thermoplastic polymer matrix M, a process for preparing spherical particles comprising a thermoplastic polymer matrix M comprising at least two types of fillers F dispersed in the thermoplastic polymer matrix M. A - A mixture, a) At least one thermoplastic polymer matrix M comprising at least two fillers F dispersed therein in a concentration of up to 50%; b) At least one compound P selected from the group comprising polyglycols, polysaccharides, polyolefins, polyvinyl alcohols, silicones, waxes and mixtures thereof, which is different from at least one thermoplastic polymer M and is not miscible with at least one thermoplastic polymer matrix M, and c) At least one active substance C, which is an amphiphilic compound having a first structural portion that can react chemically or physically with a thermoplastic polymer matrix M and a second structural portion that can react chemically or physically with compound P, wherein the first structural portion does not contain a polymer chain identical to that of the thermoplastic polymer matrix M. A step of melt-blending a mixture containing the following: B - A step of cooling the molten blend obtained in step A to a temperature below the blend's softening temperature. C - A step of solubilizing compound P and active substance C by placing the cooled blend in a solvent in which compound P and active substance C are soluble. D - A step of recovering spherical particles containing a thermoplastic polymer matrix M and at least two types of fillers F dispersed therein. It provides a process that includes this.

[0017] Through such a process, it is possible to obtain spherical polymer particles according to the present invention, which contain at least two types of fillers dispersed in a polymer matrix.

[0018] Therefore, the present invention provides a process implemented by using the HIPE principle.

[0019] Creating HIPEs with controlled small droplets and the ability to maintain additives as fillers inside the droplets is a major challenge.

[0020] The present invention is based on the discovery that including a unique active substance C in an emulsion formed by blending a dispersed thermoplastic polymer matrix M, a filler F, and a continuous phase, a compound P, not only effectively stabilizes the emulsion but also ensures proper dispersion of the filler F in the thermoplastic polymer matrix M.

[0021] According to the present invention, spherical particles of different types of polymers are provided by using the same active substance C.

[0022] In fact, the applicant has surprisingly discovered that an active substance C that does not contain a polymer chain identical to the thermoplastic polymer matrix M, as part of its structure, stabilizes the sphericity of the polymer particles and ensures that the filler F remains dispersed in the thermoplastic polymer matrix M during the co - extrusion process.

[0023] Another challenge is to ensure that the affinity between the compound P and the thermoplastic polymer matrix M is sufficient to enable emulsion formation due to the ideal viscosity difference between the phases contributing to stress sharing.

[0024] "Affinity" shall mean the similarity of properties suggesting possible chemical or physical reactions / interactions between different compounds or mixtures of compounds.

[0025] ]The viscosity of a fluid such as an emulsion is a measure of its resistance to a given rate of deformation. Generally, the processes of emulsification and rupture of the discrete droplets depend on the viscosity ratio between the internal and external phases and the mechanical shear stress. A small droplet size is preferred to increase the external phase viscosity. On the other hand, the increased viscosity requires more energy to form the emulsion.

[0026] Therefore, the viscosity of the external phase can play an important role in both the emulsification process and the viscosity of the final emulsion. During emulsification, a higher viscosity will result in a lower final droplet size. However, there is a critical external polymer viscosity / internal polymer viscosity ratio at which it is difficult to obtain the droplet size and shape.

[0027] According to the present invention, the use of the appropriate agent C is important through its effect on the continuous phase rheology related to the time-dependent deformation of an object under the influence of the interface properties and the applied stress.

[0028] A second object of the present invention is the use for preventing and / or reducing signs of skin aging, particularly in the cosmetic field, of the functional biostimulating effect of the obtained spherical polymer particles, which can be provided by different fillers.

[0029] By methods known per se, the term "signs of skin aging" refers to the marks present on the skin resulting from the aging phenomenon that change the appearance of the skin, particularly wrinkles and age spots, and are generally considered unattractive.

[0030] The above advantages will be apparent to those skilled in the art from the figures.

Brief Description of the Drawings

[0031] [Figure 1] Shows a scanning electron microscopy (SEM) image (SEI, 15 kV, 230×) obtained for polyamide 6.6 spherical particles produced by the coextrusion process of the present invention. [Figure 2]The image shows a scanning electron microscope (SEM) image (SEI, 15kV, 450×) obtained for polyhydroxybutyrate (PHB) spherical particles produced by the co-extrusion process of the present invention. [Modes for carrying out the invention]

[0032] definition Throughout this specification, including the claims, all process terms should be understood to be synonymous with the term method.

[0033] According to the ASTM definition, the term "biodegradable polymer" refers to the decomposition caused by the action of natural microorganisms such as bacteria, fungi, and algae. As a result, biodegradable materials break down into biomass, carbon dioxide, and methane, which possess special properties such as non-toxicity, biocompatibility, and biodegradability. When biodegradation occurs in a marine environment, the polymer is called a marine biodegradable polymer.

[0034] As used herein, the term “biostimulatory effect” refers to a biological effect on skin integrity that improves the appearance of the skin and soothes skin conditions.

[0035] As used herein, the term "soluble" refers to the recovery of 99% of compound P and active substance C at a temperature of 25°C.

[0036] "Amphiphilic" is a term used to describe chemical compounds that possess both hydrophilic and hydrophobic properties. Such compounds are called amphiphilic or amphipathic.

[0037] An "emulsion" is a suspension of a first liquid in a phase composed of a second liquid, where the first liquid is not miscible with the second liquid. A discontinuous phase within a continuous phase is obtained in this case.

[0038] The present invention is based on a process for preparing spherical particles comprising a thermoplastic polymer matrix M and at least two mineral fillers F dispersed therein.

[0039] In one embodiment, the thermoplastic polymer matrix M may be selected from the group including, in particular, polymers based on cellulose esters such as polyester, polyolefin, cellulose acetate, cellulose propionate and polymers of the same family, acrylic polymers and copolymers, polyamides such as polyhexamethylene adipoamide (PA66), polycaprolactam (PA6), polyamide 5.6, PA6.10, PA10.10 and PA12, copolymers of these polymers in any ratio, and blends of any of these polymers.

[0040] According to one preferred embodiment, the thermoplastic polymer matrix M preferably consists of polyamides selected from polyamide 6, polyamide 66, polyamide 56, and copolymers of polyamide 6 / polyamide 66, polyamide 6 / polyamide 56, and polyamide 66 / polyamide 56 in any ratio.

[0041] In another embodiment, the thermoplastic polymer matrix M is, for example, - Polyhydroxybutyrate (PHB), - Polyhydroxybutyrate-co-valerate (PHBV), - Polylactic acid (PLA), - Polylactic acid-co-glycolic acid (PLGA), - Polyhydroxyalkanoate (PHA), - Thermoplastic starch (TPS), - Poly(butylene succinate) (PBS), - Poly(butylene succinate adipate) (PBSA), - Polybutylene adipate (PBA), - Blends such as polybutylene adipate terephthalate (PBAT) or polylactic acid (PLA) / polycaprolactone (PCL), and - Thermoplastic polymers manufactured with biodegradable additives. It consists of marine biodegradable polymers, which refer to any polymer that possesses its own unique biodegradability.

[0042] Examples of additives that impart biodegradability to thermoplastic polymers include, for example, commercially available additives named BioSphere® 201 and Ecopure® CNY-EP-04C-NY.

[0043] According to one preferred embodiment, the thermoplastic polymer matrix M preferably consists of a polyhydroxyalkanoate (PHA) selected from polyhydroxybutyrate (PHB) and polyhydroxybutyrate-co-valerate (PHBV).

[0044] According to the present invention, a thermoplastic polymer matrix M containing up to 50% dispersed filler F is used in solid form, particularly as granules.

[0045] Generally, granules that are pre-extruded and contain polymers and at least two types of fillers F are prepared before melt blending.

[0046] According to one embodiment, the granules are present in the molten blend emulsion in an amount less than 80% by weight and more than 15% by weight, preferably less than 50% by weight and more than 20% by weight, based on the total weight of the emulsion.

[0047] Filler F: According to the present invention, the filler F is dispersed in a thermoplastic polymer matrix M. The term “dispersed” means that the filler F is incorporated primarily within the thermoplastic polymer matrix M and / or within spherical particles. In particular, the filler is trapped within the polymer matrix and / or particles. Therefore, they are not mineral fillers deposited on the polymer, for example, in the form of a coating on the polymer surface.

[0048] In one embodiment, the filler F may be introduced into a thermoplastic polymer matrix M, for example, by an extrusion process, and then made into granules, or it may be introduced during the polymerization process, preferably at the end of polymerization. It is also possible to introduce the filler F into a molten polymer.

[0049] In one embodiment, the process of the present invention advantageously yields spherical polymer particles having at least two fillers F dispersed in a thermoplastic polymer matrix M, which can promote a biostimulant effect.

[0050] According to the present invention, the biostimulating effect can be provided by organic or inorganic fillers, which have the ability to absorb / emit radiation in the infrared region and are incorporated into a polymeric substrate. Preferably, the mineral filler F has far-infrared emission (FIR) properties in the region of 3 to 20 μm, and more preferably in the region of 3 to 15 μm.

[0051] The infrared absorption spectrum can be measured by any method known to those skilled in the art. One possible method has a resolution of 4 cm. -1 This involves using a Bruker Equinox 55 instrument. In this case, the resulting spectrum is in the form of ATR ("attenuated total internal reflection") using a ZnSe crystal.

[0052] The mineral filler F usable according to the present invention can be selected from the following combinations of groups: oxide group, sulfate group, carbonate group, silicate group, and phosphate group.

[0053] Preferably, the oxide is selected from titanium dioxide, silicon dioxide, and magnesium oxide.

[0054] The sulfate can be advantageously selected from barium sulfate, calcium sulfate, and strontium sulfate.

[0055] Preferably, the carbonate is selected from calcium carbonate or sodium carbonate.

[0056] The phosphate can be advantageously selected from zirconium phosphate, calcium phosphate, hydroxyapatite, apatite, magnesium phosphate, sodium phosphate, potassium phosphate, and other possible phosphates.

[0057] Preferably, the silicate is selected from actinolite, mica, tourmaline, serpentine, kaolin, montmorillonite, zeolite, and other aluminum silicates, and is preferably tourmaline.

[0058] In one embodiment, at least one mineral filler F is a silicate, preferably selected from the group consisting of actinolite, mica, tourmaline, serpentine, kaolin, montmorillonite, zeolite, and other aluminum silicates and mixtures thereof, and more preferably tourmaline.

[0059] In another embodiment, the mineral filler F is preferably selected from the group consisting of oxides, sulfates, and silicates, and more preferably titanium dioxide, barium sulfate, and tourmaline.

[0060] According to one embodiment of the present invention, the weight ratio of the filler F to the total weight of the spherical particles is 1% or more, preferably 5% or more, and more preferably 15% or more.

[0061] In another embodiment, the weight ratio of the filler F to the total weight of the spherical particles is 50% or less, preferably 35% or less, and more preferably 30% or less.

[0062] Compound P According to the process of the present invention, compound P is different from at least one thermoplastic polymer M and is not miscible with at least one thermoplastic polymer matrix M.

[0063] In one embodiment, compound P is selected from the group comprising polyglycols, polysaccharides, polyolefins, polyvinyl alcohols, silicones, waxes, and mixtures thereof.

[0064] Preferably, the selected polyglycol was polyethylene glycol (PEG).

[0065] Advantageously, compound P is selected from the group consisting of polyoxyethylene (POE) and polyalkylene glycol (PAG), and is preferably polyethylene glycol (PEG).

[0066] According to one embodiment, the specific polymer used as compound P of the present invention is polyethylene glycol (PEG) having a molecular weight in the range of 1500 to 60000 g / mol, preferably 6000 to 35000 g / mol.

[0067] In another embodiment, the weight ratio of compound P to the weight of the blend of the present invention is 15 to 80% by weight of compound P, preferably PEG, and more preferably 40 to 70% by weight.

[0068] Agent C: According to the process of the present invention, the active substance C is an amphiphilic compound having a first part of its structure that can react chemically or physically with a thermoplastic polymer matrix M and a second part of its structure that can react chemically or physically with compound P, wherein the first part of its structure does not contain polymer chains that are identical to those of the thermoplastic polymer matrix M.

[0069] As an example of the present invention, the active substance C is an ethoxylated / propoxylated block copolymer.

[0070] In preferred embodiments, the active substance C used in the present invention, an ethoxylated (EO) / propoxylated (PO) block polymer (EO / PO), has a suitable HLB and molecular weight. These types of polymers are amphiphilic molecules consisting of a hydrophilic ethylene oxide (EO) block and a hydrophobic propylene oxide (PO) block. Therefore, the amphiphilicity of molecules such as EO / PO block copolymers can be characterized by their hydrophilic-lipophilic balance (HLB). Several experimental and numerical methods have been developed over many years to measure the HLB number.

[0071] A suitable EO / PO copolymer having the desired molecular weight and HLB enables the formation of a stable HIPE for emulsions containing a polyester (such as polyhydroxybutyrate-PHB, polyhydroxybutyrate-co-valerate-PHBV, or polyhydroxyalkanoate-PHA) as the dispersed phase and a continuous phase such as polyethylene glycol (PEG). The EO block derived from the copolymer appears to be solubilized in a more polar polymer (compound P), while the PO block appears to be solubilized in a less polar phase, a dispersed thermoplastic polymer matrix M.

[0072] An increase in the EO ratio of active ingredient C leads to an increase in the HLB value, which directly affects the stability of HIPE and consequently influences the final spherical polymer particle formation.

[0073] The lipophilic portion of active substance C interacts more strongly with the thermoplastic polymer matrix M, creating a type of barrier that yields two benefits. Firstly, it inhibits the movement of the filler F, and secondly, it reduces interfacial tension, thereby mitigating deformation of the formed droplets.

[0074] However, the affinity of the filler F in compound P must be reduced toward the thermoplastic polymer matrix M in order to ensure its maximum content in the matrix M.

[0075] The active substance C, which is advantageously selected for the process of the present invention, is an ethoxylated / propoxylated block copolymer (EO / PO) of a suitable HLB and molecular weight.

[0076] In particular, the active substance C of the present invention is an ethoxylated / propoxylated block polymer having a molecular weight in the range of 500 to 10000 g / mol, preferably 3000 to 7000 g / mol.

[0077] In one embodiment, the active substance C is an ethoxylated (EO) / propoxylated (PO) block polymer having a PO / EO ratio in the range of 2 to 10, preferably 5 to 7.

[0078] According to another embodiment, the weight ratio of active substance C to the weight of the blend of the present invention is selected from 1 to 20% by weight, preferably 5 to 10% by weight.

[0079] According to a preferred embodiment, step A of the melt blend is carried out at a temperature greater than 100°C and less than 300°C, preferably greater than 160°C and less than 270°C.

[0080] In particular, the molten blend of the present invention is processed by extrusion in an extruder selected from an endless screw mixer or a stirrer mixer, preferably a twin-screw extruder or a multi-screw extruder.

[0081] Typically, the extrusion process of the present invention is carried out by a rotary extruder operating at approximately 100 to 600 rpm, more specifically 200 to 500 rpm.

[0082] Step B, which involves cooling the molten blend obtained in step A, is most frequently carried out by any suitable means at a temperature below the softening temperature of the blend. Air cooling or rapid cooling in a liquid may be specifically mentioned.

[0083] In a preferred embodiment, in a blend where the thermoplastic polymer matrix M is PHB or PA6.6, compound P is PEG, and active substance C is an ethoxylated / propoxylated (EO / PO) block copolymer, step B is carried out at a temperature in the range of 15 to 40°C.

[0084] Step C of the present invention is typically carried out by immersing the cooled blend obtained in Step B in a bath containing a solvent in which compound P and active substance C are soluble, thereby providing solubilization of compound P and active substance C.

[0085] Alternatively, cooling step B and solubilization step C can be carried out with the same solvent.

[0086] It is strongly recommended that compound P and active substance C have low solubility and high mismatch with the thermoplastic polymer matrix M. In this way, the solubilization process of compound P and active substance C can be carried out without loss of spherical polymer particles, increasing the process yield.

[0087] Typically, the solvent used in step C is selected from the group consisting of water, methanol, ethanol, isopropanol, and butanol, and is preferably water.

[0088] Such solubilization by step C makes it possible to obtain a dispersion of particles that can be isolated, for example, by filtration, separation by sedimentation, centrifugation, or spraying.

[0089] During the solubilization process C, mechanical forces such as friction, shearing, crushing, ultrasonic treatment, or torsion can be applied as needed.

[0090] Step D of the present invention is carried out by recovering spherical particles containing a thermoplastic polymer matrix M and at least two types of fillers F dispersed therein.

[0091] Advantageously, the spherical particles are then dried after step D. The drying process can be carried out, for example, in a device such as a furnace at a temperature range of 30 to 110°C.

[0092] In an advantageous embodiment, the process of the present invention comprises a molten blend mixture of step A, which includes the following: a) A thermoplastic polymer matrix M+F comprising 15-80% by weight, preferably 20-50% by weight, which is PHB or PA6.6 containing three fillers F, preferably titanium dioxide, barium sulfate, and tourmaline; b) Compound P comprising 15-80% by weight, preferably 40-70% by weight, and preferably PEG; c) Active substance C comprising 1 to 20% by weight, preferably 5 to 10% by weight, wherein the active substance C is an ethoxylated / propoxylated block copolymer.

[0093] The process of the present invention enables the preparation of polymer particles with regular shapes and sizes.

[0094] As used herein, the term "particle" refers to an individualized entity.

[0095] The particles of the present invention can be characterized by their bulk, which means they can be characterized by their large quantity.

[0096] According to a first preferred embodiment of the present invention, the polymeric composition particles are substantially spherical as measured by scanning electron microscopy (SEM), that is, the particles have a shape similar to that of a sphere, and they may be, to varying degrees, regularly, for example, ellipsoids and / or ellipsoids.

[0097] The particles of the present invention can be characterized by their particle size distribution D50 (simply put, "D50"), also known as the median diameter or median of the particle size distribution, where 50% of the particles in the sample are larger and 50% are smaller. Particle size analysis can be performed, for example, with a Malvern Mastersizer 3000 laser particle size analyzer.

[0098] According to one embodiment, the spherical particles of the present invention exhibit an average particle size D50 in the range of 5 μm to 60 μm, preferably 10 μm to 40 μm.

[0099] Filler F that moves away from the particles The main advantage of the present invention is that the majority (more than 50%) of the filler F is located within the spherical particles, which means that the filler F is dispersed in the thermoplastic polymer matrix M.

[0100] The content of filler F migrated from the thermoplastic polymer matrix M to the surface of particles, such as PHB and PA6.6, can be estimated from particle size analysis data using the volume difference between the particles of the thermoplastic polymer matrix M and the free filler F particles. Inorganic filler F has anti-aging effects and is expensive; therefore, avoiding its loss during the extrusion mixing process makes it possible to have an economical process.

[0101] In one embodiment, the migrated filler F parameter found with respect to particles changes with the amount of active substance C added during the melt blending process, ranging from 20 to 5000 mg / kg with the addition of active substance C, and reaching 140000 mg / kg without the addition of active substance C.

[0102] In one embodiment, the amount of filler F migrated from the particles is 5000 mg / kg or less, preferably 3000 mg / kg or less, and more preferably 2260 mg / kg or less.

[0103] spherical factor The process of the present invention makes it possible to obtain spherical particles.

[0104] The spherical shape of particles can be demonstrated by scanning electron microscopy (SEM), which allows for the direct observation of the microstructure features of surfaces, interfaces, and the interior of bulk materials. A scanning electron microscope (SEM) is a type of electron microscope that produces an image of a sample by scanning the surface with a focused beam of electrons. Electrons interact with atoms in the sample, yielding various signals that include information about the surface topography and the composition of the sample.

[0105] The procedure for evaluating the sphericity of polymer particles is performed by scanning electron microscopy (SEM) using the long and short axes passing through the center of the particle, and the resulting ratio reflects the sphericity factor ratio.

[0106] In one embodiment, the spheroidal factor ratio of the present invention is selected from 0.5 to 1.0, preferably from 0.75 to 1.0.

[0107] Usage: The spherical polymer particles of the present invention can preferably be used in a variety of applications for preventing or reducing signs of skin aging, particularly for cosmetic compositions.

[0108] The following examples illustrate the present invention and should not be considered as limiting the invention to its details. [Examples]

[0109] The present invention will be explained by the following embodiments.

[0110] In the examples, the various abbreviations have the following meanings:

[0111] PHB: Polyhydroxybutyrate polymer. PHB is obtained from BIOMER under the name BIOMER biopolyester.

[0112] PHB+FIR: Polyhydroxybutyrate polymer plus far-infrared absorbing / emitting filler F.

[0113] PA6.6: Polyamide 6.6 polymer. PA6.6 is manufactured by Solvay and marketed under the name Polyamide 6.6 Brilliant.

[0114] PA6.6+FIR: Polyamide 6.6 plus far-infrared absorbing / emitting filler F.

[0115] Filler F was obtained from Venator and Microservice under the names titanium dioxide, barium sulfate, and tourmaline.

[0116] PEG: Polyethylene glycol polymer. PEG is obtained by Sigma-Aldrich under the name polyethylene glycol.

[0117] PEG 6000, PEG 20000, and PEG 35000: Polyethylene glycol polymers with molecular weights of 6000, 20000, and 35000 g / mol, respectively.

[0118] The active substance C is an ethoxylated / propoxylated block copolymer, which is commercially available from Solvay under the name Antarox L 101.

[0119] d(0.1) = 10% of the total volume is represented by particles with a diameter smaller than d(0.1).

[0120] d(0.5) = 50% of the total volume is represented by particles with a diameter smaller than d(0.5).

[0121] d(0.9) = 90% of the total volume is represented by particles with a diameter smaller than d(0.9).

[0122] Twin-screw extruder system: Co-rotating twin-screw Polylab OS Rheodrive 7 / HAAKE Rheomex OS Extruder PTW16 type, L / D 16mm, connected to Thermo Scientific Torque Rheometer.

[0123] Particle size analysis was performed using a Malvern Mastersizer 3000 laser particle size analyzer.

[0124] Scanning electron microscopy was performed using a JEOL JSM-6610LV SEM / EDX microscope.

[0125] The content of filler F migrated from the particles was measured by particle size data analysis using a Malvern Mastersizer 2000 laser particle size analyzer and ethanol as the dispersion medium.

[0126] Example 1 The blend was prepared according to Table 1.

[0127] The trial composition was prepared using granules of PHB + 30% filler F(FIR) prepared in advance using a twin-screw extruder SHJ20. The granules of PHB and 30% by weight of FIR additive were obtained by a melt extrusion process in which 69% by weight of PHB was mixed with 1.0% by weight of citric acid, 15.75% by weight of tourmaline, 10.5% by weight of barium sulfate, and 3.75% by weight of titanium dioxide. The extruder temperature profiles in various zones of the extruder during the process were 173°C to 151°C, and the rotation speed was 65 rpm.

[0128] Next, the granules were introduced together with the active substances C and PEG into a twin-screw extruder rotating at 300 rpm to prepare a molten blend.

[0129] The introduction was carried out by supplying raw materials by weight. The active substance C, which was in the liquid phase, was pre-mixed with PHB. PHB and PEG were in solid form as granules and pellets, respectively.

[0130] During the first stage, an appropriate screw profile is required to facilitate efficient blending of the materials. Subsequently, screw and temperature profiles were applied according to the properties of the product and a sufficient residence time to allow for the rupture of droplets formed from the HIPE emulsion.

[0131] The extruder conditions used during the process were a rotation speed of 300 rpm, temperatures of 166-170°C in various zones of the extrusion screw, and a throughput of 0.4 kg / hour.

[0132] The molten blend is cooled in water, and the solubilization of PEG from the blend occurs instantaneously in most experimental compositions.

[0133] [Table 1]

[0134] The final particles were collected by centrifugation and dried overnight at 100°C.

[0135] In Trial 1, the cooled blend did not decompose immediately when introduced into water. In this trial, the thermoplastic polymer M remained in the continuous phase, and therefore, spherical particles were not obtained in this trial.

[0136] Example 2: The particle size distribution of the trial composition in Example 1 was analyzed, and the results are shown in Table 2.

[0137] The particle size distribution of the sample was measured using a Malvern Mastersizer 3000 laser particle size analyzer connected to a Hydro LV accessory, which enables analysis in solvent dispersions. The Mastersizer 3000 uses laser diffraction to measure the particle size and particle size distribution of a material. It measures the intensity of scattered light as the laser beam interacts with the dispersed particles of the sample.

[0138] The test compositions were analyzed immediately after being added to a particle size analyzer using ethanol as the dispersion medium.

[0139] [Table 2]

[0140] The results found in the trial compositions analyzed for particle size distribution showed a D50 in the range of 6 μm to 50 μm.

[0141] Example 3 Scanning electron microscopy: The sphericity of spherical polymer particles was evaluated using scanning electron microscopy (SEM) with the long and short axes passing through the center of the particle. Each particle identified by SEM was collected, and the axes intersecting each other at right angles were measured. The sphericity factor was calculated as the ratio of the short axis to the long axis. At least 100 measurements (50 particles) were performed for each assay.

[0142] The results for the trial composition of Example 1 are shown in Table 3.

[0143] [Table 3]

[0144] As shown in Table 3, adding active ingredient C during the extrusion mixing process resulted in a shape factor higher than 0.75 and the formation of spherical particles. When active ingredient C was not added during the extrusion mixing process, spherical particles were not observed.

[0145] Example 4 Filler F migrated from the particles: The filler F migrated from the thermoplastic polymer matrix M was measured by particle size distribution data according to the volume difference between the total particles and the free filler F, and calculated using the mass ratio between filler F and the total particles. Assuming the same density for all particles, the mass was calculated using the volume of particles with a diameter smaller than 1.5 μm represented by the free filler F.

[0146] The results obtained for the trial composition of Example 1 are shown in Table 4.

[0147] [Table 4]

[0148] When active substance C was added, the parameter of the migrated filler F found in the spherical particles varied from 23 to 2260 mg / kg, but when active substance C was not added, the migrated filler F reached 140,000 mg / kg.

[0149] Example 5 Using the manufacturing process according to Example 1, blends were obtained according to Table 5.

[0150] The trial composition was prepared using granules of PA6.6 + 30% filler F(FIR) prepared in advance using a twin-screw extruder SHJ20. The granules of PA6.6 and 30 wt% FIR additive were obtained by a melt extrusion process in which 70 wt% PA6.6 was mixed with 15.75 wt% tourmaline, 10.5 wt% barium sulfate, and 3.75 wt% titanium dioxide. The extruder temperature profile in various zones of the extruder during the process was 265°C to 284°C, and the rotational speed was 460 rpm.

[0151] Next, the granules were introduced into a twin-screw extruder along with the active substances C and PEG. The temperature profiles of various zones during the process were 250°C to 270°C at 300 rpm, and a molten blend was prepared.

[0152] The introduction was carried out by supplying raw materials by weight. The active substance C, which was in the liquid phase, was pre-mixed with PA6.6+FIR. PA6.6+FIR and PEG were in solid form, specifically granules and pellets, respectively.

[0153] During the first stage, an appropriate screw profile is required to facilitate efficient blending of the materials. Subsequently, screw and temperature profiles were applied according to the properties of the product and a sufficient residence time to allow for the rupture of droplets formed from the HIPE emulsion.

[0154] The extruder conditions used during the process were a rotation speed of 300 rpm, temperatures of 250-270°C in various zones of the extrusion screw, and a throughput of 0.4 kg / hour.

[0155] The molten blend is cooled in water, and the solubilization of PEG from the blend occurs instantaneously in most experimental compositions.

[0156] [Table 5]

[0157] The final particles were collected by centrifugation and dried overnight at 100°C.

[0158] Example 6: The particle size distribution of the trial composition in Example 5 was analyzed, and the results are shown in Table 6.

[0159] The particle size distribution of the sample was measured using a Malvern Mastersizer 3000 laser particle size analyzer connected to a Hydro LV accessory, which enables analysis in solvent dispersions. The Mastersizer 3000 measures the particle size and particle size distribution of a material using laser diffraction. It measures the intensity of scattered light as the laser beam interacts with the dispersed particles of the sample.

[0160] [Table 6]

[0161] The results found in the trial compositions analyzed regarding particle size distribution showed a D50 in the range of 20 μm to 40 μm.

[0162] Example 7 Scanning electron microscopy: The sphericity of spherical polymer particles was evaluated using scanning electron microscopy (SEM) with the long and short axes passing through the center of the particle. Each particle identified by SEM was collected, and the axes intersecting each other at right angles were measured. The sphericity factor was calculated as the ratio of the short axis to the long axis. At least 100 measurements (50 particles) were performed in each trial.

[0163] The results for the trial composition of Example 5 are shown in Table 7.

[0164] [Table 7]

[0165] As can be seen in Table 7, the shape factor of PA6.6+FIR particles using active ingredient C resulted in spherical particles.

[0166] Example 8 Filler F migrated from the particles: The filler F migrated from the thermoplastic polymer matrix M was measured by particle size distribution data according to the volume difference between the total particles and the free filler F, and calculated using the mass ratio between filler F and the total particles. Assuming the same density for all particles, the mass was calculated using the volume of particles with a diameter smaller than 1.5 μm represented by the free filler F.

[0167] The results for the trial composition of Example 5 are shown in Table 8.

[0168] [Table 8]

[0169] The migration of filler F was less than 1%, meaning it did not exhibit significant values.

[0170] Therefore, surprisingly, it was found that processes using the same active ingredient C and different types of polymers can produce spherical polymer particles containing filler F dispersed in a polymer matrix in a manner that controls shape and size, and that such processes can ensure the persistence of filler F within the thermoplastic polymer matrix M during the co-extrusion process.

[0171] It should be understood that the present invention is not limited by the above description and is limited by the claims appended herein.

Claims

1. A process for preparing spherical particles comprising a thermoplastic polymer matrix M, wherein the thermoplastic polymer matrix M comprises at least two types of fillers F dispersed in the thermoplastic polymer matrix M, A - A mixture, a) At least one thermoplastic polymer matrix M comprising at least two fillers F dispersed therein in an amount of up to 50% by weight; b) At least one compound P selected from the group including polyglycols, polysaccharides, polyolefins, polyvinyl alcohols, silicones, waxes and mixtures thereof, which is different from the at least one thermoplastic polymer M and is not miscible with the at least one thermoplastic polymer matrix M, and c) At least one active substance C which is an amphiphilic compound having a first portion of its structure that can react chemically or physically with the thermoplastic polymer matrix M and a second portion of its structure that can react chemically or physically with the compound P, wherein the first portion of its structure does not contain a polymer chain identical to that of the thermoplastic polymer matrix M. A step of melt-blending a mixture containing the following: B - A step of cooling the molten blend obtained in step A to a temperature below the softening temperature of the blend. C - A step of solubilizing compound P and active substance C by placing the cooled blend in a solvent in which compound P and active substance C are soluble. D - A step of recovering spherical particles containing the thermoplastic polymer matrix M and the at least two types of fillers F dispersed therein. A process that includes this.

2. The process according to claim 1, wherein the thermoplastic polymer matrix M is selected from synthetic or biodegradable polymers.

3. The process according to claim 2, wherein the thermoplastic polymer matrix M is a synthetic polymer and is selected from at least one member of the group consisting of polyester, polyolefin, cellulose ester-based polymers, acrylic polymers and copolymers, polyamides, copolymers of the polymers in any ratio, and mixtures thereof.

4. The process according to claim 3, wherein the thermoplastic polymer matrix M is a polyamide.

5. The thermoplastic polymer matrix M is a biodegradable polymer, and Polylactic acid (PLA), Polylactic acid-co-glycolic acid (PLGA), Polyhydroxyalkanoate (PHA), Thermoplastic starch (TPS), Poly(butylene succinate) (PBS), Poly(butylene succinate adipate) (PBSA), Polybutylene adipate (PBA), Polybutylene adipate terephthalate (PBAT) or polylactic acid (PLA) / polycaprolactone (PCL), and Thermoplastic polymers containing additives that provide biodegradability. The process according to claim 2, selected from at least one member of the group consisting of the following.

6. The process according to claim 5, wherein the thermoplastic polymer matrix M is polyhydroxyalkanoate (PHA), polyhydroxybutyrate (PHB), or polyhydroxybutyrate-co-valerate (PHBV).

7. The process according to any one of claims 1 to 6, wherein the filler F comprises at least two mineral fillers having absorption and / or emission properties in the far-infrared region in the range of 2 μm to 20 μm.

8. The process according to claim 7, wherein the mineral filler F is selected from the group consisting of oxides, sulfates, carbonates, phosphates, and silicates.

9. The process according to claim 8, wherein the mineral filler F is selected from the group consisting of oxides, sulfates, and silicates.

10. The process according to claim 9, wherein the mineral filler F is a silicate selected from the group consisting of actinolite, mica, tourmaline, serpentine, kaolin, montmorillonite, zeolite, and mixtures thereof.

11. The process according to any one of claims 1 to 10, wherein the weight ratio of the filler F to the total weight of the spherical particles is 1% or more.

12. The process according to any one of claims 1 to 11, wherein the weight ratio of the filler F to the total weight of the spherical particles is 50% or less.

13. The process according to any one of claims 1 to 12, wherein compound P is selected from the group consisting of polyoxyethylene (POE) and polyalkylene glycol (PAG).

14. The process according to claim 13, wherein the compound P is polyethylene glycol having a molecular weight in the range of 1,500 to 60,000 g / mol.

15. The process according to any one of claims 1 to 14, wherein the active substance C is an ethoxylated / propoxylated block polymer having a molecular weight in the range of 500 to 10,000 g / mol.

16. The process according to claim 15, wherein the active substance C is an ethoxylated (EO) / propoxylated (PO) block polymer having a PO / EO ratio in the range of 2 to 10.

17. The process according to any one of claims 1 to 16, wherein the solvent used in step C is selected from the group consisting of water, methanol, ethanol, isopropanol, and butanol.

18. The process according to any one of claims 1 to 17, wherein the spherical particles are dried after step D.

19. The melted blend in step A is a) A thermoplastic polymer matrix M+F comprising 15 to 80% by weight, wherein the thermoplastic polymer matrix M+F contains three types of fillers F, which are titanium dioxide, barium sulfate, and tourmaline; b) 15-80% by weight of compound P; c) Active substance C in an amount of 1 to 20% by weight, wherein the active substance C is an ethoxylated / propoxylated block copolymer. The process according to any one of claims 1 to 18, including the process described in any one of claims 1 to 18.

20. The process according to any one of claims 1 to 19, wherein step A of the melt blend is carried out at a temperature greater than 100°C and less than 300°C.

21. The process according to any one of claims 1 to 20, wherein the molten blend is processed by extrusion in an extruder selected from an endless screw mixer or a stirrer mixer.

22. The process according to any one of claims 1 to 21, wherein the particles contain the migrated filler F in an amount of 5000 mg / kg or less.

23. Spherical polymer particles that can be obtained or obtained by the process described in any one of claims 1 to 22.

24. The particle according to claim 23, wherein the average particle size D50 is in the range of 5 μm to 60 μm.

25. The particle according to claim 23 or 24, having a sphericity factor ratio selected from 0.5 to 1.

0.

26. Use of the particles according to any one of claims 23 to 25 for a cosmetic composition.

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