A N ε Fatty acyl lysine-coated natural starch microspheres, process for their preparation and use

Abstract

This invention discloses an N ε This paper describes the encapsulation of natural starch microspheres with fatty acyl lysine, its preparation method, and its application, belonging to the field of cosmetic technology. The method involves encapsulating natural starch microspheres with N-fatty acyl lysine. ε - Fatty acyl lysine dissolves in the presence of an acid-co-solvent to yield N ε - Acidic solution of fatty acyl lysine; slowly add N dropwise to starch gelatinization solution. ε Acidic solution of -fatty acyl lysine was added dropwise. After addition, the solution was kept warm and stirred to induce crystallization. Then, the pH and temperature were adjusted to allow for further crystallization. The precipitated crystals were separated by filtration, centrifugation for dehydration, drying, and pulverization to obtain N. ε Natural starch microspheres are encapsulated with fatty acyl lysine. These microsphere powders have excellent hydrophobic properties, good powder flowability, good powder molding properties, strong skin adhesion, and long-lasting makeup effect. They can be widely used in the fields of makeup, skin care, and daily chemical products.

Description

Technical Field

[0001] This invention relates to starch microspheres, and particularly to an N... ε The invention relates to the encapsulation of natural starch microspheres with fatty acyl lysine, as well as their preparation methods and applications in color cosmetics, skin care, or personal care products, and belongs to the field of cosmetic technology. Background Technology

[0002] Traditional plastic microbeads are now restricted by regulations in many countries. Natural starch, as a natural biomass polymer, is derived from common agricultural crops such as corn, cassava, and potatoes, making it widely available. Furthermore, starch is a food-grade safe raw material, non-toxic and non-irritating, completely biodegradable, and exhibits excellent biocompatibility and skin-friendliness. Its use in daily chemical products is highly safe, and it has good compatibility with various excipients in cosmetic systems, making it an ideal green raw material to replace petrochemical-based plastic microbeads. However, unmodified natural starch still has significant drawbacks. It has poor water resistance, easily swells and disintegrates in aqueous systems, lacks structural stability, and has weak thermal stability. Under high temperatures, it easily agglomerates, making it difficult to maintain a regular particle shape. Additionally, the starch powder lacks surface smoothness, has a rough feel, poor flowability and spreadability, and is highly hygroscopic, easily becoming damp and clumping. Its storage stability is poor, and surface functionalization modification is difficult, severely limiting its application in cosmetics, high-end personal care, and other daily chemical fields.

[0003] Existing methods for modifying starch microspheres mainly employ chemical modification, physical encapsulation, microencapsulation, and nano-encapsulation. For example, Chinese patent applications (publication number: CN114957731A) and (publication number: CN118845530A) respectively utilize silane coupling agent activation and dry blending to modify starch and encapsulating materials. Existing modification processes generally suffer from high production costs, demanding requirements for specialized equipment, and difficulties in mass production. Furthermore, conventional physical encapsulation struggles to achieve tight encapsulation of the starch microsphere surface, easily leading to phase separation and component separation between the coating layer and the starch microspheres, reducing the powder's skin feel, adhesion, and formulation application performance. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the first objective of this invention is to provide an N ε - Fatty acyl lysine encapsulates natural starch microspheres, which have good hydrophobic properties, delicate and silky skin feel, strong skin adhesion, long-lasting makeup, excellent powder pressing and powder picking performance, and can be used as a green functional powder to replace cosmetic plastic microbeads.

[0005] The second object of the present invention is to provide an N ε A method for preparing natural starch microspheres encapsulated with fatty acyl lysine, wherein the method achieves N through solution crystallization encapsulation. ε- The interface between fatty acyl lysine and natural starch is tightly bound, which solves the technical pain points of traditional encapsulation, such as easy delamination, poor powder texture and stability. Moreover, the process is simple to operate and the conditions are mild, which meets the requirements of industrial production.

[0006] The third objective of this invention is to provide an N ε - Application of fatty acyl lysine-encapsulated natural starch microspheres, N ε - Fatty acyl lysine-encapsulated natural starch microspheres exhibit excellent hydrophobic properties while also possessing good powder flowability and compressibility, and contain N ε - Fatty acyl lysine encapsulates natural starch microspheres in cosmetics, skincare, and personal care products, resulting in strong skin adhesion and long-lasting makeup effects.

[0007] To achieve the above technical objectives, the present invention provides an N ε The preparation method of natural starch microspheres encapsulated with fatty acyl lysine includes the following steps:

[0008] 1) Gelatinize the natural starch aqueous solution to obtain a transparent starch gelatinized liquid;

[0009] 2) N ε - Fatty acyl lysine dissolves in an organic solvent under the action of an acidic solubilizer to give N ε -Acidic solution of fatty acyl lysine;

[0010] 3) Control the temperature of the starch gelatinization solution within the range of 30–75°C, and slowly add N dropwise to the starch gelatinization solution. ε - After the acidic solution of fatty acyl lysine is added dropwise, first keep it warm and stir to precipitate crystals, then adjust the pH of the solution system to the range of 6 to 8, and at the same time cool it down to below 15°C to allow for crystallization.

[0011] 4) The precipitated crystals are separated by filtration, and then subjected to centrifugation, dehydration, drying, and pulverization to obtain N. ε - Fatty acyl lysine encapsulates natural starch microspheres.

[0012] The N of the present invention ε The key to the preparation method of natural starch microspheres encapsulated with fatty acyl lysine lies in: on the one hand, the present invention selects N ε - Fatty acyl lysine, as a coating and modifying material for starch, has the following advantages: It has good biological properties and will not harm human skin; Its outstanding hydrophobicity significantly enhances makeup staying power and oil control. The crystals exhibit a layered structure, giving the starch microspheres a low coefficient of friction and a silky, smooth feel. Having polar ends, it can be adsorbed and assembled on the starch surface to form a tight package, improving the skin feel and adhesion of starch microspheres; It exhibits good compatibility with commonly used cosmetic excipients, improving the performance of formulation applications. Furthermore, this invention controls N by adjusting temperature and pH. ε The dissolution and crystallization process of -fatty acyl lysine to achieve N ε - Fatty acyl lysine is tightly and uniformly coated on the surface of natural starch. More specifically, based on N ε - Fatty acyl lysine is almost insoluble in water and common organic solvents, making it difficult to disperse as a powder. This invention addresses this by heating and acidifying N... ε -Protonation of fatty acyl lysine to improve N ε - The solubility of fatty acyl lysine, and since natural starch is usually negatively charged, while N ε - The protonated amino group in fatty acyl lysine forms a tightly bound interface with the surface of natural starch through electrostatic interactions and the carboxyl group through hydrogen bonding, while N ε - Long-chain alkyl groups carried by fatty acyl lysine self-assemble on the surface of natural starch to form a dense hydrophobic layer, which is then cooled and the pH is adjusted to neutral to achieve N ε The complete crystallization of fatty acyl lysine forms a dense layered crystal on the surface of natural starch, achieving perfect encapsulation of natural starch.

[0013] As a preferred embodiment, the mass concentration of the natural starch aqueous solution is 1% to 15%. The concentration of the natural starch aqueous solution mainly affects the size of the microspheres and the content of natural starch encapsulated within the microspheres; the lower the concentration, the smaller the resulting microspheres and the lower the starch content encapsulated within them. The mass concentration of the natural starch aqueous solution is further preferably 8% to 12%.

[0014] As a preferred embodiment, the natural starch includes at least one of tapioca starch, corn starch, potato starch, wheat starch, rice starch, glutinous corn starch, pea starch, and sweet potato starch.

[0015] As a preferred embodiment, the gelatinization treatment is performed at a temperature of 50–100°C. Heating to an appropriate temperature allows the starch granules to fully absorb water, expand in volume, break hydrogen bonds, and disrupt the crystalline structure, forming a uniform gel, which is beneficial for the subsequent formation of uniform microspheres. The gelatinization temperature is further preferably 75–95°C.

[0016] As a preferred option, the N ε - In fatty acyl lysine, the fatty acyl group is C8~C6. 18 Acyl group. C8~C 18The acyl group is primarily introduced as a hydrophobic group. Specific examples include octanoyl, decanoyl, lauroyl, myristoyl, palmitoyl, stearoyl, oleoyl, etc. It should also be noted that if the carbon chain is too long, it will lead to N... ε - Fatty acyl lysine has poor solubility and is difficult to adapt to the preparation of microspheres. If the carbon chain is too short, the effect of hydrophobic modification on the surface of microspheres will be poor.

[0017] As a preferred embodiment, the acid co-solvent includes at least one of hydrochloric acid, sulfuric acid, acetic acid, and citric acid.

[0018] As a preferred option, the N ε -N fatty acyl lysine in acidic solution ε -The mass of fatty acyl lysine is 0.5% to 25% of the mass of natural starch in the aqueous solution of natural starch; if N ε If the amount of -fatty acyl lysine is too low, it is difficult to form uniformly coated microspheres. If N ε Excessive use of -fatty acyl lysine can lead to spontaneous aggregation and agglomeration, making it difficult to encapsulate natural starch. Further preferably, the N... ε -N fatty acyl lysine in acidic solution ε -The mass of fatty acyl lysine is 10% to 22% of the mass of natural starch in the aqueous solution of natural starch;

[0019] As a preferred option, the N ε -The pH of the acidic solution of fatty acyl lysine is 3~5.

[0020] As a preferred option, the N ε The mass percentage concentration of the acidic solution of fatty acyl lysine is 1~8%.

[0021] As a preferred embodiment, the organic solvent includes at least one of methanol, ethanol, isopropanol, dichloromethane, ethyl acetate, and propyl acetate.

[0022] The alkali used in this invention to adjust pH is at least one of sodium hydroxide, potassium hydroxide, and triethanolamine.

[0023] This invention provides an N ε - Fatty acyl lysine encapsulates natural starch microspheres, which are obtained by the preparation method described above.

[0024] The present invention also provides an N ε - The application of fatty acyl lysine-encapsulated natural starch microspheres, which are used as functional powder spheres in cosmetics, skin care or daily chemical products.

[0025] Compared with existing technologies, the beneficial technical effects of the present invention are as follows:

[0026] The N of the present invention ε - Fatty acyl lysine-encapsulated natural starch microspheres have good hydrophobic properties, a delicate and silky feel, strong skin adhesion, long-lasting makeup, and excellent powder pressing and powder picking performance. They can be widely used as green functional powders in daily chemical products such as makeup, skin care, and personal care.

[0027] The N of the present invention ε The preparation process of natural starch microspheres encapsulated with fatty acyl lysine is simple, mild, and inexpensive, making it easy to industrialize. Attached Figure Description

[0028] Figure 1 N in Examples 1-6 ε - Comparison of the hydrophobicity of natural starch microspheres encapsulated with fatty acyl lysine and cassava starch microspheres in Comparative Example 1.

[0029] Figure 2 N in Examples 1-6 ε - Comparison of the skin adhesion effects of fatty acyl lysine-encapsulated natural starch microspheres and cassava starch microspheres in Comparative Example 1. Detailed Implementation

[0030] The following specific embodiments are intended to further illustrate the content of the present invention, rather than to limit the scope of protection of the claims.

[0031] Unless otherwise specified, all reagents used in the following specific embodiments are conventional commercial reagents.

[0032] Comparative Example 1

[0033] 15 g of cassava starch was dissolved in 135 g of water and heated to 95 °C for 10 min to gelatinize. The temperature was then lowered to 68 °C for later use. 0.5 g of 32% hydrochloric acid solution was dissolved in 60 g of ethanol and heated to 50 °C to prepare an acidic ethanol solution. This acidic ethanol solution was slowly added dropwise to the gelatinized cassava starch solution over 100 min. After stirring for 30 min, 6% sodium hydroxide solution was added dropwise to adjust the pH of the system to 7.0. The temperature was then lowered to 15 °C and maintained for 30 min. After centrifugation, filtration, drying, and pulverization, 12.1 g of cassava starch microspheres were obtained.

[0034] Example 1

[0035] Add 1.67g N to 60g ethanol ε - Lauroyl lysine and 0.5 g of 32% hydrochloric acid solution are heated to 50°C and stirred until dissolved. 15 g of tapioca starch is dissolved in 135 g of water and heated to 95°C for 10 minutes to gelatinize. The mixture is then cooled to 68°C. N... εA lauroyl lysine ethanol acidic solution was slowly added dropwise to a gelatinized cassava starch solution over 100 minutes. After stirring for 30 minutes, a 6% sodium hydroxide solution was added dropwise to adjust the pH of the system to 7.0. The temperature was then lowered to 15°C and maintained for 30 minutes. After centrifugation, filtration, drying, and pulverization, N was obtained. ε - 15.80 g of cassava starch microspheres encapsulated with lauroyl lysine.

[0036] Example 2

[0037] Add 1.67g N to 60g ethanol ε - Lauroyl lysine and 0.5 g of 32% hydrochloric acid solution are heated to 50°C and stirred until dissolved. 15 g of corn starch is dissolved in 135 g of water and heated to 95°C for 10 minutes to gelatinize. The mixture is then cooled to 68°C. N... ε A lauroyl lysine ethanol acidic solution was slowly added dropwise to a gelatinized corn starch solution over 100 minutes. After stirring for 30 minutes, a 6% sodium hydroxide solution was added dropwise to adjust the pH of the system to 7.0. The temperature was then lowered to 15°C and maintained for 30 minutes. After centrifugation, filtration, drying, and pulverization, N was obtained. ε - 15.60 g of corn starch microspheres encapsulated with lauroyl lysine.

[0038] Example 3

[0039] Add 1.67g N to 80g ethanol ε - Lauroyl lysine and 0.5 g of 32% hydrochloric acid solution are heated to 50°C and stirred until dissolved. 15 g of tapioca starch is dissolved in 115 g of water and heated to 90°C for 10 minutes to gelatinize. The mixture is then cooled to 68°C. N... ε A lauroyl lysine ethanol acidic solution was slowly added dropwise to a gelatinized cassava starch solution over 100 minutes. After stirring for 30 minutes, a 6% sodium hydroxide solution was added dropwise to adjust the pH of the system to 7.0. The temperature was then lowered to 15°C and maintained for 30 minutes. After centrifugation, filtration, drying, and pulverization, N was obtained. ε - 15.00 g of cassava starch microspheres encapsulated with lauroyl lysine.

[0040] Example 4

[0041] Add 1.67g N to 60g methanol. ε - Lauroyl lysine and 0.4 g concentrated sulfuric acid are heated to 50°C and stirred until dissolved. 15 g of tapioca starch is dissolved in 135 g of water and heated to 95°C for 10 minutes to gelatinize. The mixture is then cooled to 68°C. N... εA lauroyl lysine ethanol acidic solution was slowly added dropwise to a gelatinized corn starch solution over 90 minutes. After stirring for another 30 minutes, a 6% sodium hydroxide solution was added dropwise to adjust the pH of the system to 7.0. The temperature was then lowered to 15°C and maintained for 30 minutes. After centrifugation, filtration, drying, and pulverization, N was obtained. ε 15.10 g of cassava starch microspheres encapsulated with lauroyl lysine.

[0042] Example 5

[0043] Add 3.34g N to 80g ethanol. ε - Lauroyl lysine and 0.5 g hydrochloric acid are heated to 50°C and stirred until dissolved. 15 g of corn starch is dissolved in 135 g of water and heated to 95°C for 10 minutes to gelatinize. The mixture is then cooled to 68°C. N... ε A lauroyl lysine ethanol acidic solution was slowly added dropwise to a gelatinized corn starch solution over 90 minutes. After stirring for another 30 minutes, a 6% sodium hydroxide solution was added dropwise to adjust the pH of the system to 7.0. The temperature was then lowered to 15°C and maintained for 30 minutes. After centrifugation, filtration, drying, and pulverization, N was obtained. ε - 16.87 g of corn starch microspheres encapsulated with lauroyl lysine.

[0044] Example 6

[0045] Add 1.67g N to 60g ethanol ε -Octayl lysine and 0.5 g hydrochloric acid are heated to 50°C and stirred until dissolved. 15 g of tapioca starch is dissolved in 135 g of water and heated to 95°C for 10 minutes to gelatinize. The mixture is then cooled to 68°C. N... ε -Octayl lysine ethanol acidic solution was slowly added dropwise to the gelatinized corn starch solution over 100 min. After stirring for 30 min, 6% sodium hydroxide solution was added dropwise to adjust the pH of the system to 7.0. The temperature was then lowered to 15℃ and maintained for 30 min. After centrifugation, filtration, drying, and pulverization, N was obtained. ε 13.34 g of cassava starch microspheres encapsulated with octanoyl lysine.

[0046] I. Hydrophobicity Test:

[0047] N in Examples 1-6 ε - When natural starch microspheres coated with fatty acyl lysine and the tapioca starch microspheres in Comparative Example 1 were added to water, the following phenomena were observed: Figure 1 As shown. N in Examples 1-6 ε - Fatty acyl lysine-coated natural starch microspheres float on the water surface, while the tapioca starch microspheres in Comparative Example 1 disperse in the water, indicating that natural starch, if coated with N... εThe α-fatty acyl lysine is encapsulated, which has poor hydrophobicity, is prone to absorbing water, swelling and disintegrating, and has insufficient structural stability.

[0048] II. Powder Adhesion Performance Test:

[0049] N from Examples 1-6 ε - Fatty acyl lysine-encapsulated natural starch microspheres and cassava starch microspheres of Comparative Example 1 were respectively packed into 50mL glass bottles with an inner diameter of 30mm and a height of 80mm, with a uniform packing density of 0.65g / cm³ and a powder packing height of 50mm. A 22mm×22mm square clean coverslip was used and inserted into the powder to a depth of 40mm at a 90° vertical angle and a speed of 10mm / s. After standing in contact for 30s, it was pulled out at the same speed. The coverslip was placed vertically 10cm from the table and gently shaken 3 times to remove floating powder. The mass of the coverslip before and after the test was measured and the mass of the attached powder was calculated. Each group of samples was tested 5 times. After removing abnormal data, the average value was taken as the final test result. The ambient temperature was controlled at 25°C and the relative humidity at 50% throughout the process.

[0050] The results show that: after N ε - Natural starch microspheres coated with fatty acyl lysine exhibit significantly better adhesion than unmodified starch microspheres, effectively improving the staying power of makeup.

[0051] III. Tests on the impact strength and powder extraction performance of compressed powder:

[0052] The powder compact formulation (parts by weight) was as follows: 42 parts talc, 22 parts mica, 10 parts spherical silica, 10 parts test powder, 4 parts nylon-10 / 10, 6 parts composite skin-tone pigment, 6 parts isoamyl cocoate, 3 parts polydimethylsiloxane, and 2 parts magnesium stearate. Only the test powder was replaced in each group. The raw materials were sieved through a 120-mesh screen and then mixed evenly at high speed. A φ30mm powder compact mold was used to press the powder compact into a thickness of 2.5 mm (±0.1 mm) under a pressure of 5 MPa for 2 seconds. Impact strength was tested using a crushing strength tester equipped with a φ2mm cylindrical flat-head indenter. The powder was pressed vertically at a rate of 1.0 mm / s until it broke. The maximum breaking force was recorded and the impact strength per unit thickness (g / mm) was calculated. Powder picking performance was tested using a standard blush brush (8mm bristle length, 10mm diameter). After cleaning, drying and weighing, the brush was used to pick up powder from the powder surface 20 times in a straight line under a constant pressure of 80 g, with a stroke of 20 mm. The amount of powder picked up (mg) was represented by the difference in mass of the brush before and after the test. Each test was performed in parallel for 5 times, and outliers were removed and the average value was taken.

[0053] Table 1 N in Examples 1-6 ε - Fatty acyl lysine-encapsulated natural starch microspheres and in Comparative Example 1

[0054] Note: Formulas 1-7 (parts by weight): talc 42 parts, mica 22 parts, spherical silica 10 parts, starch microspheres 10 parts, nylon-10 / 10 4 parts, composite skin-colored pigment 6 parts, isoamyl cocoate 6 parts, polydimethylsiloxane 3 parts, magnesium stearate 2 parts. Wherein, the starch microspheres in formulas 1-6 are respectively the N... ε - Fatty acyl lysine encapsulates natural starch microspheres; the starch microspheres in Formula 7 are the same as the tapioca starch microspheres in Comparative Example 1.

[0055] The results show that the N of the present invention ε - Fatty acyl lysine-encapsulated natural starch microspheres, when used in powder formulations, can simultaneously achieve excellent anti-shattering and molding properties as well as powder-collecting and makeup-applying performance, resulting in a comprehensive effect far superior to unmodified natural starch.

Claims

1. A kind of N ε A method for preparing natural starch microspheres encapsulated with α-fatty acyl lysine, characterized in that: Includes the following steps: 1) Gelatinize the natural starch aqueous solution to obtain a transparent starch gelatinized liquid; 2) N ε - Fatty acyl lysine dissolves in an organic solvent under the action of an acidic solubilizer to give N ε -Acidic solution of fatty acyl lysine; 3) Control the temperature of the starch gelatinization solution within the range of 30–75°C, and slowly add N dropwise to the starch gelatinization solution. ε - After the acidic solution of fatty acyl lysine is added dropwise, first keep it warm and stir to precipitate crystals, then adjust the pH of the solution system to the range of 6 to 8, and at the same time cool it down to below 15°C to allow for crystallization. 4) The precipitated crystals are separated by filtration, and then subjected to centrifugation, dehydration, drying, and pulverization to obtain N. ε - Fatty acyl lysine encapsulates natural starch microspheres.

2. The N according to claim 1 ε A method for preparing natural starch microspheres encapsulated with α-fatty acyl lysine, characterized in that: The mass concentration of the natural starch aqueous solution is 1% to 15%.

3. An N according to claim 1 or 2 ε A method for preparing natural starch microspheres encapsulated with α-fatty acyl lysine, characterized in that: The natural starch includes at least one of tapioca starch, corn starch, potato starch, wheat starch, rice starch, glutinous corn starch, pea starch, and sweet potato starch.

4. An N according to claim 1 ε A method for preparing natural starch microspheres encapsulated with α-fatty acyl lysine, characterized in that: The conditions for the gelatinization process are: a temperature of 50–100°C.

5. An N according to claim 1 ε The method for preparing α-fatty acyl lysine natural starch microspheres is characterized by: The N ε - In fatty acyl lysine, the fatty acyl group is C8~C6. 18 Acyl group.

6. An N according to claim 1 ε A method for preparing natural starch microspheres encapsulated with α-fatty acyl lysine, characterized in that: The acid co-solvent includes at least one of hydrochloric acid, sulfuric acid, acetic acid, and citric acid.

7. An N according to claim 1 ε A method for preparing natural starch microspheres encapsulated with α-fatty acyl lysine, characterized in that: The N ε -N fatty acyl lysine in acidic solution ε The mass of -fatty acyl lysine is 0.5% to 25% of the mass of natural starch in the aqueous solution of natural starch.

8. An N according to claim 1 ε A method for preparing natural starch microspheres encapsulated with α-fatty acyl lysine, characterized in that: The N ε -The pH of the acidic solution of fatty acyl lysine is 3~5; The N ε The mass percentage concentration of the acidic solution of fatty acyl lysine is 1~8%; The dripping time of the starch gelatinization solution is controlled between 60 and 180 minutes.

9. A kind of N ε - Fatty acyl lysine encapsulates natural starch microspheres, characterized by: It is obtained by the preparation method described in any one of claims 1 to 8.

10. The N according to claim 9 ε The application of -fatty acyl lysine-encapsulated natural starch microspheres is characterized by: As a functional powder ball, it is used in makeup, skincare, or personal care products.

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