An oil-based cleansing composition, its preparation and use

Abstract

The application discloses an oily skin cleansing composition and a preparation method and application thereof, and relates to the technical field of surfactants. The oily skin cleansing composition comprises linear polyglycerol medium-chain fatty acid ester, linear polyglycerol long-chain fatty acid ester, an oil agent and an auxiliary agent, the linear polyglycerol medium-chain fatty acid ester is obtained by esterification of linear polyglycerol with medium-chain fatty acid, and the linear polyglycerol long-chain fatty acid ester is obtained by esterification of linear polyglycerol with long-chain fatty acid, wherein the average polymerization degree of the linear polyglycerol is 6-40, and the branching degree of the linear polyglycerol is less than 0.20; the proportion of the primary hydroxyl group in all hydroxyl groups in the linear polyglycerol is greater than or equal to 90%, the linear MCFE (linear polyglycerol medium-chain fatty acid ester) and the linear LCFE (linear polyglycerol long-chain fatty acid ester) can form micelles with a highly unified structure, and perfect balance between the cleaning power and the easy rinsing property is achieved at a low addition amount.

Description

Technical Field

[0001] This invention relates to the field of surfactants, and in particular to an oily cleansing composition, its preparation method, and its application. Background Technology

[0002] Polyglycerol fatty acid esters, as nonionic surfactants, are highly safe and biodegradable, and are widely used in the food and cosmetic industries. In the cosmetics field, they can be incorporated into cleansing oils and gels to dissolve, solubilize, and remove makeup residue and sebum.

[0003] Existing technologies typically achieve the solubilizing and cleansing functions of cleansing compositions by incorporating a high proportion of polyglycerol medium-chain fatty acid esters (MCFE). However, because traditional polyglycerol fatty acid esters have poor molecular arrangement regularity and low surface activity efficiency, they are difficult to form stable micelle structures or achieve efficient oil solubilization at low addition levels. Therefore, to achieve the expected cleansing power and emulsion stability, existing formulations are often forced to significantly increase the amount of surfactant used. However, the addition of large amounts of such surfactants can significantly alter the rheological properties of the system, leading to excessive foaming during product use, and a sticky, difficult-to-rinse feel after washing, severely impacting the user experience of cosmetics.

[0004] Therefore, how to reduce the amount of surfactant used while ensuring cleaning efficiency and improving the user experience caused by high addition levels is a technical problem that urgently needs to be solved. Summary of the Invention

[0005] The main objective of this invention is to provide an oily cleansing composition, its preparation method, and its application, aiming to address the shortcomings of existing technologies where the amount of surfactant used in the preparation of non-linear polyglycerol is too large, and where the use of large amounts of surfactant results in deficiencies in terms of user experience and cleansing power.

[0006] To achieve the above objectives, the present invention proposes an oily cleansing composition comprising linear polyglycerol medium-chain fatty acid ester, linear polyglycerol long-chain fatty acid ester, oil, and additives. The linear polyglycerol medium-chain fatty acid ester is formed by esterification of linear polyglycerol with medium-chain fatty acids, and the linear polyglycerol long-chain fatty acid ester is formed by esterification of linear polyglycerol with long-chain fatty acids. The linear polyglycerol has an average degree of polymerization of 6–40, and the linear polyglycerol has a branching degree of <0.20. The primary hydroxyl groups in the linear polyglycerol account for ≥90% of all hydroxyl groups.

[0007] In one embodiment, the medium-chain fatty acid has 6 to 10 carbon atoms; and / or, The medium-chain fatty acids include at least one of caprylic acid, capric acid, and isononanoic acid.

[0008] In one embodiment, the long-chain fatty acid has 12 to 22 carbon atoms; and / or, The long-chain fatty acids include at least one of lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, isostearic acid, and ricinoleic acid.

[0009] In one embodiment, the oily cleansing composition comprises, by weight percentage: Linear polyglycerol medium-chain fatty acid esters: 1%~30%; Linear polyglycerol long-chain fatty acid esters: 0.5%~15%; Oil content 60%~98.5%; The remainder are additives.

[0010] In one embodiment, the mass ratio of the linear polyglycerol medium-chain fatty acid ester to the linear polyglycerol long-chain fatty acid ester is 5:1 to 1:2.

[0011] In one embodiment, the mass of the linear polyglycerol medium-chain fatty acid ester is m1, the mass of the linear polyglycerol long-chain fatty acid ester is m2, and the mass of the oily cleansing composition is m, satisfying that (m1+m2) / m<20%.

[0012] In one embodiment, the oiling agent comprises at least one selected from natural oils, hydrocarbon oils, ester oils, glyceryl ester oils, and silicone oils; and / or, The additives include at least one of the following: humectants, emulsifiers, preservatives / antibacterial agents, antioxidants, fragrances, chelating agents, and light stabilizers.

[0013] This invention provides a method for preparing an oily cleansing composition, the method comprising: Linear polyglycerol was prepared by reacting the linear polyglycerol with medium-chain fatty acids and long-chain fatty acids respectively to obtain linear polyglycerol medium-chain fatty acid esters and linear polyglycerol long-chain fatty acid esters. The oil, the linear polyglycerol medium-chain fatty acid ester, and the linear polyglycerol long-chain fatty acid ester are mixed, stirred, and heated to obtain a mixture. After cooling the mixture, it is mixed with the additives, filtered, and an oily cleansing composition is obtained.

[0014] In one embodiment, the preparation steps for linear polyglycerol include: Under inert gas protection, a glycerol derivative is subjected to ring-opening polymerization in an initiator and solvent to obtain the first intermediate; The first intermediate was stirred in an acidic aqueous solution to obtain the second intermediate; The second intermediate was purified to obtain linear polyglycerol.

[0015] In one embodiment, the glycerol derivative includes at least one of EEGE, tBGE, and AGE; and / or, The acidic aqueous solution includes hydrochloric acid solution.

[0016] This invention provides an application of the oily cleansing composition as described above or the oily cleansing composition prepared by the method described above, the application field including skin care products or cosmetics.

[0017] In the technical solution of this invention, by limiting the average degree of polymerization, branching degree, and proportion of primary hydroxyl groups among all hydroxyl groups of the linear polyglycerol, a highly regular "linear unbranched polyglycerol" is obtained. This serves as a rigid framework, ensuring the uniformity of fatty acid introduction sites. That is, linear MCFE (linear medium-chain fatty acid ester) and linear LCFE (linear long-chain fatty acid ester) can form micelles with highly uniform structures. This inherent "order" guarantees that product performance remains highly consistent under all production conditions, achieving excellent performance. With reproducibility and precise control, short-chain MCFE can quickly dissolve and swell stubborn makeup and sebum, while long-chain LCFE ensures that oil particles are efficiently dispersed and do not stick back during the rinsing stage. This deep interaction of long and short chain molecules, combined with other components, not only significantly reduces the critical micelle concentration (CMC) required to form a stable cleaning structure, resulting in a significant reduction in the total amount of surfactant added, but also fundamentally solves the problem that traditional oil-based cleaning products cannot achieve both "high cleaning power" and "clean and residue-free after washing", achieving a perfect balance between cleaning power and easy rinsing with low additive levels. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0019] Figure 1 Here are five structural diagrams of polyglycerol; Figure 2 The 13C-NMR spectrum of polyglycerol prepared in Example 1 of this invention; Figure 3 The 13C-NMR spectrum of polyglycerol prepared in Example 2 of this invention; Figure 4 The 13C-NMR spectrum of polyglycerol prepared in Example 3 of this invention; Figure 5 The 13C-NMR spectrum of polyglycerol prepared in Example 4 of this invention; Figure 6 The 13C-NMR spectrum of polyglycerol prepared in Example 5 of this invention; Figure 7 The 13C-NMR spectrum of polyglycerol prepared in Example 6 of this invention; Figure 8 The 13C-NMR spectrum of polyglycerol prepared in Example 7 of this invention.

[0020] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0022] It should be noted that if the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a specific posture. If the specific posture changes, the directional indicators will also change accordingly.

[0023] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the use of "and / or" or "and / or" throughout the text includes three parallel solutions. For example, "A and / or B" includes solution A, solution B, or a solution where both A and B are satisfied simultaneously. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0024] Existing technologies typically achieve the solubilizing and cleansing functions of cleansing compositions by incorporating a high proportion of polyglycerol medium-chain fatty acid esters (MCFE). However, because traditional polyglycerol fatty acid esters have poor molecular arrangement regularity and low surface activity efficiency, they are difficult to form stable micelle structures or achieve efficient oil solubilization at low addition levels. Therefore, to achieve the expected cleansing power and emulsion stability, existing formulations are often forced to significantly increase the amount of surfactant used. However, the addition of large amounts of such surfactants can significantly alter the rheological properties of the system, leading to excessive foaming during product use, and a sticky, difficult-to-rinse feel after washing, severely impacting the user experience of cosmetics.

[0025] Therefore, how to reduce the amount of surfactant used while ensuring cleaning efficiency and improving the user experience caused by high addition levels is a technical problem that urgently needs to be solved.

[0026] In view of this, the present invention proposes an oily cleansing composition comprising linear polyglycerol medium-chain fatty acid ester, linear polyglycerol long-chain fatty acid ester, oil and adjuvants, wherein the linear polyglycerol medium-chain fatty acid ester is formed by esterification of linear polyglycerol with medium-chain fatty acids, and the linear polyglycerol long-chain fatty acid ester is formed by esterification of linear polyglycerol with long-chain fatty acids, wherein the average degree of polymerization of the linear polyglycerol is 6-40, the degree of branching of the linear polyglycerol is <0.20, and the proportion of primary hydroxyl groups in the linear polyglycerol is ≥90% of all hydroxyl groups.

[0027] In the technical solution of this invention, by limiting the average degree of polymerization, branching degree, and proportion of primary hydroxyl groups among all hydroxyl groups of the linear polyglycerol, a highly regular "linear unbranched polyglycerol" is obtained. This serves as a rigid framework, ensuring the uniformity of fatty acid introduction sites. That is, linear MCFE (linear medium-chain fatty acid ester) and linear LCFE (linear long-chain fatty acid ester) can form micelles with highly uniform structures. This inherent "order" guarantees that product performance remains highly consistent under all production conditions, achieving excellent performance. With reproducibility and precise control, short-chain MCFE can quickly dissolve and swell stubborn makeup and sebum, while long-chain LCFE ensures that oil particles are efficiently dispersed and do not stick back during the rinsing stage. This deep interaction of long and short chain molecules, combined with other components, not only significantly reduces the critical micelle concentration (CMC) required to form a stable cleaning structure, resulting in a significant reduction in the total amount of surfactant added, but also fundamentally solves the problem that traditional oil-based cleaning products cannot achieve both "high cleaning power" and "clean and residue-free after washing", achieving a perfect balance between cleaning power and easy rinsing with low additive levels.

[0028] Furthermore, the linear polyglycerol medium-chain fatty acid esters and linear polyglycerol long-chain fatty acid esters used have regular structures, are linearly arranged, have very few branches, and have minimal steric hindrance. Their interfaces are tightly and orderly arranged. When combined with other oils and additives, the resulting oily cleansing composition can achieve highly effective cleansing and emulsification with low dosage.

[0029] It should be noted that, using the polyglycerol fatty acid ester of this invention as a substitute for PEG-based surfactants, PGFE allows for free control of the HLB value by adjusting the degree of polymerization of polyglycerol, fatty acid chain length, and esterification degree, enabling its wide application in systems ranging from low-HLB oily systems to high-HLB aqueous systems. Furthermore, PGFE does not generate harmful byproducts such as 1,4-dioxane that may be produced by PEG-based surfactants during its synthesis, and all its raw materials are derived from renewable vegetable oils, thus resulting in a low environmental impact. Polyglycerol is synthesized through the dehydration polymerization of glycerol, followed by esterification or transesterification reactions with fatty acids to produce PGFE. This synthesis method does not require high temperatures or organic solvents, making it safe and sustainable.

[0030] It should be noted that the linear polyglycerol medium-chain fatty acid ester is formed by the esterification of linear polyglycerol with medium-chain fatty acids.

[0031] Understandably, the presence of branched chains in nonlinear polyglycerols complicates the steric hindrance within the molecule. Although primary hydroxyl groups are generally more reactive than secondary hydroxyl groups, the abundance and varied positions of secondary hydroxyl groups in nonlinear structures inevitably lead to fatty acids attaching to the "branches" of the backbone. This results in extremely complex ester molecular structures, with the fatty acid chains distributed haphazardly along the glycerol backbone, failing to form a uniform "comb-like" or "linear" arrangement.

[0032] This invention utilizes linear polyglycerol with high structural uniformity, resulting in the introduction of subsequent fatty acids primarily into the terminal primary hydroxyl groups. The introduction of hydrophobic groups is uniform, and this highly ordered arrangement forms micelles or microemulsions with uniform radius and stable structure. The fluctuations in micelle radius and critical micelle concentration (CMC) are small, thus improving the reproducibility of surface activity. Furthermore, because the backbone of linear polyglycerol is linear, short-chain MCFE and long-chain LCFE can form a specific core-shell layered structure at the interface, similar to "bristles of varying lengths" (MCFE rapidly penetrates the outer layer, while LCFE anchors oil stains in the inner layer). Therefore, although medium-chain fatty acid esters (linear MCFE) can form fine O / W emulsions or microemulsions when used alone, when combined with long-chain linear polyglycerol fatty acid esters (linear LCFE) as described later, an even finer and more uniform interfacial structure can be formed, further enhancing cleaning power.

[0033] Furthermore, the average degree of polymerization of the linear polyglycerol is 6 to 40, or it can be 6, 8, 10, 11, 13, 20, 22, 25, 32 or 40. Any value within the above range can be used. The nonionic surfactant obtained by partially or completely esterifying the above linear polyglycerol with medium-chain fatty acids will have insufficient surface activity if the average degree of polymerization is too low, and excessive viscosity if it is too high, resulting in a reduced user experience.

[0034] It should be noted that the degree of polymerization of polyglycerol directly determines the number of hydrophilic hydroxyl groups in its molecule. The higher the degree of polymerization, the stronger the hydrophilicity. By controlling the average degree of polymerization within the range of 6 to 40, the hydrophilic-lipophilic balance (HLB value) of the final esterification product can be flexibly adjusted to balance its hydrophilicity and lipophilicity.

[0035] Furthermore, the degree of branching of the linear polyglycerol is <0.20, that is, it can be 0.1, 0.215, 0.18, or 0.2. Strictly controlling the degree of branching below 0.20 means that the molecular skeleton is highly linearized. This regular structure allows fatty acid ester molecules to be tightly arranged at the interface like "neatly arranged soldiers," forming an extremely thin and tough interfacial film. Therefore, only a very low amount of addition is needed to achieve the emulsification and solubilization effects that traditional branched polyglycerol requires a large amount of addition, fundamentally solving the problem of "large dosage."

[0036] In some embodiments, the primary hydroxyl groups in the linear polyglycerol account for ≥90% of all hydroxyl groups, specifically 90%, 92%, 95%, or 99%. Among the three hydroxyl groups in glycerol, the steric hindrance of the primary hydroxyl groups (located at both ends of the carbon chain) is much smaller than that of the secondary hydroxyl groups (located in the middle of the carbon chain), resulting in extremely high chemical reactivity. In polyglycerol prepared by traditional processes, the proportion of primary hydroxyl groups is often only 30%–70%, and a large number of inactive secondary hydroxyl groups can lead to incomplete esterification or disordered product structures. Increasing the proportion of primary hydroxyl groups to 90% or more not only greatly improves the efficiency and conversion rate of the esterification reaction, but more importantly, it ensures that the fatty acid chains can be grafted onto both ends of the polyglycerol backbone in a highly uniform and directional manner. This highly uniform molecular structure ensures that the emulsion particle size and micelle structure of each batch of product are extremely stable, resulting in excellent performance reproducibility and a stable user experience.

[0037] Understandably, the molecular structure of traditional polyglycerol contains 1,2-bonds, 1,3-bonds, and branched structures, with primary hydroxyl groups accounting for 30-70%, secondary hydroxyl groups for 70-30%, and branched glycerol units for 10-30%. This structural heterogeneity leads to differences in the location and number of hydrophobic groups introduced into surfactants after fatty acid esterification. This results in fluctuations in emulsion particle size and micelle structure, leading to insufficient reproducibility in user experience and cleaning power. Furthermore, high-HLB long-chain fatty acid esters (LCFEs) are difficult to disperse uniformly in oily compositions when used alone, and excessive addition in large quantities can lead to excessive foaming and cleaning power, resulting in a poor user experience.

[0038] In some embodiments, the linear polyglycerol medium-chain fatty acid ester is formed by esterification of linear polyglycerol with medium-chain fatty acids: wherein the medium-chain fatty acid has 6 to 10 carbon atoms; and the medium-chain fatty acid includes at least one of caprylic acid, capric acid, and isononanoic acid.

[0039] Medium-chain fatty acids with 6-10 carbon atoms have shorter structures and weaker intermolecular forces. This results in esters with excellent fluidity and spreadability, feeling extremely light and non-greasy on the skin, spreading quickly and providing a refreshing "instant absorption" experience. Furthermore, the chain structure has excellent affinity and dissolving power for oils in makeup, sunscreens, and sebum secreted by the skin. It can quickly penetrate and break down stubborn makeup residue, greatly improving the efficiency of makeup removal and cleansing.

[0040] In some embodiments, the linear polyglycerol medium-chain fatty acid ester is formed by esterification of linear polyglycerol with long-chain fatty acids: wherein the long-chain fatty acid has 12 to 22 carbon atoms; the long-chain fatty acid includes at least one of lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, isostearic acid and ricinoleic acid.

[0041] This is because long-chain fatty acids with 12-22 carbon atoms have stronger lipophilic (hydrophobic) properties. These long carbon chains can penetrate deeper into the oil phase, forming a strong and dense interfacial protective film. This film effectively locks in oil droplets, preventing oil-water separation and significantly improving the emulsification stability and temperature resistance of the entire system. It primarily provides the formulation with "stable emulsification and moisturizing properties." In some embodiments, the oily cleansing composition comprises, by weight percentage: Linear polyglycerol medium-chain fatty acid esters: 1%~30%; Linear polyglycerol long-chain fatty acid esters: 0.5%~15%; Oil content 60%~98.5%; The remainder are additives.

[0042] In the technical solution of this invention, a high proportion of oil (60%~98.5%) is used to dissolve dirt, which is then thoroughly emulsified by a low-dosage but highly efficient linear surfactant and rinsed away with water. The micelles formed by the linear structure are extremely small and uniform in size, leaving no greasy film on the skin surface during rinsing (no residue). At the same time, because the amount of surfactant is small, it does not excessively strip the skin of its own physiological lipids, leaving the skin soft and moisturized after washing, without any tightness. A very small amount of surfactant can form an extremely dense and stable emulsion film. This directly solves the problems of stickiness, eye irritation, difficulty in rinsing, and damage to the skin barrier caused by excessive surfactant in traditional products. The high proportion of oil ensures that the product mainly uses a physical dissolution method of "oil dissolves oil," which is extremely gentle on the skin.

[0043] Further, preferably, the oily cleansing composition comprises, by weight percentage: Linear polyglycerol medium-chain fatty acid esters: 2%–15%; Linear polyglycerol long-chain fatty acid esters 5%~15%; Oil content 70%~95%; The remainder are additives.

[0044] Further, by weight percentage, the oily cleansing composition comprises: Linear polyglycerol medium-chain fatty acid esters: 2%–15%; Linear polyglycerol long-chain fatty acid esters 5%~15%; Oil content 70%~95%; The remainder are additives.

[0045] In some embodiments, the mass ratio of the linear polyglycerol medium-chain fatty acid ester to the linear polyglycerol long-chain fatty acid ester is 5:1 to 1:2.

[0046] It should be noted that while a higher proportion of medium-chain fatty acid esters results in faster makeup removal and a refreshing feel, the emulsification system may be less stable, and the skin may feel dry after washing. Conversely, a higher proportion of long-chain fatty acid esters, while providing high moisturization and stable emulsion, can lead to a heavy and greasy feel, slower cleansing and dissolution, and a stronger hydrophobicity due to the longer chain length of long-chain fatty acids. The HLB level is adjusted by controlling the mass ratio of the linear polyglycerol medium-chain fatty acid esters to the linear polyglycerol long-chain fatty acid esters to improve the user experience. In this invention, a medium HLB level is selected. (7-15), giving it moderate hydrophilicity, thus balancing stable dispersibility in oily compositions with a refreshing feeling when washed with water. When used alone, linear LCFE is difficult to disperse in oil, but when used in combination with linear MCFE, the interfacial orientation is optimized, and even a small amount can exert a strong emulsifying and cleansing power. In particular, the oily cleansing composition prepared by using the above-mentioned specific mass ratio of the two ensures extremely strong cleansing power and emulsification stability, while perfectly balancing a light and non-greasy skin feel and a comfortable experience of moisturizing and not tight after washing.

[0047] Further, the mass of the linear polyglycerol medium-chain fatty acid ester is m1, the mass of the linear polyglycerol long-chain fatty acid ester is m2, and the mass of the oily cleansing composition is m, satisfying that (m1+m2) / m<20%.

[0048] Within the aforementioned quality range, only a very small amount of additive is needed to achieve excellent emulsification and cleansing effects, thereby completely solving the problems of sticky skin, eye irritation, difficulty in rinsing, and easy irritation of the skin barrier caused by excessive amounts of surfactants in traditional oily cleansing products (usually more than 30%). While ensuring makeup removal power, it greatly improves the gentleness, refreshingness, and storage stability of the formula.

[0049] In some embodiments, the oil agent includes at least one of natural oils, hydrocarbon oils, ester oils, glyceryl ester oils, and silicone oils; the oil agent (C) is the main component constituting the cleansing oil base, used to dissolve linear MCFE and linear LCFE, and the use of the oil agent can regulate the viscosity, solubility, and post-wash skin feel of the product.

[0050] Specifically, this invention can select oil-based base materials that are highly compatible with linear MCFE and linear LCFE, and can improve the user experience and stability. Representative oils include: natural oils such as olive oil, camellia oil, jojoba oil, rice germ oil, avocado oil, and shea butter; hydrocarbon oils such as squalane and mineral oil; ester oils such as isononyl isononanoate, C12-15 alkyl benzoate, and neopentyl glycol didecanoate; glyceryl ester oils such as medium-chain triglycerides, macadamia nut oil, and coconut oil; and silicone oils such as dimethyl silicone oil, phenyltrimethylsiloxane, and cyclopentamethoxysiloxane. These oils can be used alone or in combination. In the oil-based cleansing composition of this invention, by adjusting the type and proportion of oils, the user experience, such as viscosity, spreadability, absorption, and cooling / warming sensation, can be finely designed, thereby enabling product development tailored to target users and seasons.

[0051] For example, natural oils and glycerides (such as jojoba oil and olive oil) provide excellent skin affinity and moisturization, replenishing the lipids needed by the skin.

[0052] Ester oils and hydrocarbon oils (such as synthetic esters, squalane, and mineral oils): offer lightweight spreadability and excellent makeup dissolving ability, while being cost-effective and extremely stable.

[0053] Silicone oils (such as polydimethylsiloxane): give products a silky smooth feel, fill in fine pores, and have excellent waterproof and sweatproof properties.

[0054] To enhance cleansing performance, stability, and user experience, in some embodiments, the additives include at least one of moisturizers, emulsifiers, preservatives / antibacterial agents, antioxidants, fragrances, chelating agents, and light stabilizers. Using these additives can further improve the safety and stability of the product. For example, antioxidants and preservatives are beneficial because the formulation contains extremely high levels of oils, which are highly susceptible to oxidative rancidity. Adding antioxidants can significantly extend the product's shelf life and prevent the development of off-odors; preservatives ensure the product's microbiological safety during use.

[0055] This invention provides a method for preparing the oily cleansing composition described above, the method comprising: Linear polyglycerol was prepared by reacting the linear polyglycerol with medium-chain fatty acids and long-chain fatty acids respectively to obtain linear polyglycerol medium-chain fatty acid esters and linear polyglycerol long-chain fatty acid esters. The oil, the linear polyglycerol medium-chain fatty acid ester, and the linear polyglycerol long-chain fatty acid ester are mixed, stirred, and heated to obtain a mixture. After cooling the mixture, it is mixed with the additives, filtered, and an oily cleansing composition is obtained.

[0056] The technical solution of this invention involves heating and mixing linear polyglycerol medium-chain fatty acid esters and long-chain fatty acid esters in an oil-based agent. The heat energy drives the two ester molecules to diffuse fully in the oily matrix, forming a highly ordered and stable microemulsion or micelle prototype. Subsequently, the mixture is cooled, mixed with additives, and filtered. This not only effectively avoids the side reactions that surfactants may undergo at high temperatures and ensures the chemical stability and appearance uniformity of the active ingredients in the final composition, but also maximizes the retention and utilization of the synergistic effect of long and short chain molecules at the microscopic interface. As a result, the final polyglycerol ester composition possesses extremely high cleaning power, excellent rinsing properties after washing, and highly stable product reproducibility between batches.

[0057] In some embodiments, the step of preparing linear polyglycerol includes: Under inert gas protection, a glycerol derivative is subjected to ring-opening polymerization in an initiator and solvent to obtain the first intermediate; The first intermediate was stirred in an acidic aqueous solution to obtain the second intermediate; The second intermediate was purified to obtain linear polyglycerol.

[0058] Because glycerol molecules are very reactive, direct polymerization can easily produce disordered side chains. However, by using glycerol derivatives and the above preparation method, the secondary hydroxyl groups on the glycerol backbone can be locked, thus ensuring that the polymerized main chain is straight. After polymerization, highly regular linear polyglycerol can be obtained by acid washing and purification.

[0059] In some embodiments, the glycerol derivative includes at least one of EEGE, tBGE, and AGE. The chemical structure of these glycerol derivatives is equivalent to protecting the secondary hydroxyl group (-OH) of a glycerol molecule with a "protecting group." The function of this protecting group is to prevent glycerol from randomly grafting and forming branches during polymerization, thereby ensuring the final synthesis of a straight, regular linear polyglycerol backbone. The preparation process using EEGE (ethoxyethyl glycidyl ether) is simple and easy to operate.

[0060] The acidic aqueous solution includes a hydrochloric acid solution. Under acidic conditions, the glycerol derivative with the protecting group is very sensitive to acid. After polymerization, the protecting group can be efficiently removed under mild acidic conditions (such as adding a little dilute hydrochloric acid) to reduce the clean linear polyglycerol.

[0061] This invention provides an application of the oily cleansing composition as described above or the oily cleansing composition prepared by the method described above, the application fields including skin care products and cosmetics.

[0062] The technical solution of the present invention will be further described in detail below with reference to specific embodiments and accompanying drawings. It should be understood that the following embodiments are only used to explain the present invention and are not intended to limit the present invention.

[0063] Preparation of experimental materials Preparation Example 1 A linear polyglycerol is provided, and the preparation steps of the linear polyglycerol are as follows: Under a nitrogen atmosphere, 8.2 g (0.031 mol) of tetrabutylammonium hydroxide as an initiator was added to a dry three-necked flask, followed by 100 g of anhydrous tetrahydrofuran (THF), and the mixture was cooled to 0 °C. In this system, 91.8 g (0.62 mol) of ethoxyethyl glycidyl ether (EEGE) was added dropwise over 2 hours, and the mixture was then stirred for 4 hours at room temperature to 50 °C to confirm that the monomer was almost completely converted.

[0064] After the reaction was complete, a 20% dilute hydrochloric acid solution was added to neutralize the residual alkali, and the organic layer was separated. After removing the solvent by vacuum distillation, the obtained poly(EEGE) was dissolved in methanol, and salts were removed using a strongly acidic cation exchange resin. The solvent was removed again by vacuum distillation to obtain a colorless to pale yellow viscous liquid poly(EEGE) (yield 91%).

[0065] 100 mL of 1 mol / L hydrochloric acid aqueous solution was added to the obtained poly(EEGE), and the mixture was stirred at room temperature to 40°C for 24 hours to perform acidic deprotection of the 1-ethoxyethyl protecting group. After the reaction, the reaction solution was concentrated under reduced pressure, diluted with a large amount of ethanol, and then passed through an anion exchange resin to remove the acid. The solvent was removed by distillation, and the residue was dried under reduced pressure to obtain linear polyglycerol with all glycerol units mainly consisting of primary hydroxyl groups, as a colorless viscous liquid (yield 87%).

[0066] Preparation Example 2 A linear polyglycerol is provided, and the preparation steps of the linear polyglycerol are as follows: Under a nitrogen atmosphere, 15.1 g (0.058 mol) of tetrabutylammonium hydroxide as an initiator was added to a dry three-necked flask, followed by 100 g of anhydrous tetrahydrofuran (THF), and the mixture was cooled to 0 °C. In this system, 84.9 g (0.58 mol) of ethoxyethyl glycidyl ether (EEGE) was added dropwise over 2 hours, and the mixture was then stirred for 4 hours at room temperature to 50 °C to confirm that the monomer was almost completely converted.

[0067] After the reaction was complete, dilute hydrochloric acid was added to neutralize the residual alkali, and the organic layer was separated. After removing the solvent by vacuum distillation, the obtained poly(EEGE) was dissolved in methanol, and salts were removed using an ion exchange resin. The solvent was removed again by vacuum distillation to obtain a colorless to pale yellow viscous liquid poly(EEGE) (yield 90%).

[0068] 100 mL of 1 mol / L hydrochloric acid aqueous solution was added to the obtained poly(EEGE), and the mixture was stirred at room temperature to 40°C for 24 hours to perform acidic deprotection of the 1-ethoxyethyl protecting group. After the reaction, the reaction solution was concentrated under reduced pressure, diluted with a large amount of ethanol, and then passed through an anion exchange resin to remove the acid. The solvent was removed by distillation, and the residue was dried under reduced pressure to obtain linear polyglycerol with all glycerol units mainly consisting of primary hydroxyl groups, as a colorless viscous liquid (yield 85%).

[0069] Preparation Example 3 Preparation Example 3 provides a linear polyglycerol. The preparation steps are similar to those of Preparation Example 1, except that the amount of tetrabutylammonium hydroxide initiator added is 0.010 mmol. The final yield of the linear polyglycerol described in Preparation Example 3 is 89%.

[0070] Preparation Example 4 Preparation Example 4 provides a linear polyglycerol. The preparation steps are similar to those of Preparation Example 1, except that the amount of tetrabutylammonium hydroxide initiator added is 0.0015 mmol. The final yield of the linear polyglycerol described in Preparation Example 4 is 82%.

[0071] Preparation Example 5 Preparation Example 5 provides a nonlinear polyglycerol, the preparation steps of which are as follows: Under a nitrogen atmosphere, 92 g (1 mol) of glycerol was added to a dry reactor, and the temperature was raised to 120 °C. In this system, 1407 g (19 mol) of glycidyl ether and 20 g of phosphoric acid were added dropwise over 12 hours. After the addition was complete, the mixture was stirred further at 120 °C for 4 hours. After the reaction was complete, the reaction solution was cooled to room temperature to obtain pale yellow polyglycerol 2 (yield 80%).

[0072] Preparation Example 6 A nonlinear polyglycerol is provided, and the preparation steps of the nonlinear polyglycerol are as follows: Under a nitrogen atmosphere, 92 g (1 mol) of glycerol was added to a dry reactor, and the temperature was raised to 120 °C. In this system, 666.7 g (9 mol) of glycidyl ether and 10 g of phosphoric acid were added dropwise over 12 hours. After the addition was complete, the mixture was stirred further at 120 °C for 4 hours. After the reaction was complete, the reaction solution was cooled to room temperature to obtain pale yellow polyglycerol 4 (80% yield).

[0073] Preparation Example 7 A nonlinear polyglycerol is provided, and the preparation steps of the nonlinear polyglycerol are as follows: 100.0 g of glycerol was added to a four-necked flask, and 0.5 g of sodium hydroxide was added under a nitrogen atmosphere. A mechanical stirrer, thermometer, and reflux condenser with a Dean-Stark water separator were installed. The temperature was raised to 140°C and heated continuously to remove the generated water, while reacting for 6 hours. After the reaction, the system was cooled, and the residual acid was neutralized with an aqueous sodium carbonate solution. Water and volatile components were removed by vacuum distillation, and the resulting viscous liquid was filtered to remove solid components derived from the catalyst, yielding a light brown polyglycerol 5 (80% yield).

[0074] The test results of the polyglycerols obtained in Preparation Examples 1-7 above are shown in Table 1. The test methods are as follows: 1. Average degree of polymerization: The formula for calculating the average degree of polymerization is: Average degree of polymerization = (112.2 × 10) 3 -18×hydroxyl value) / (74×hydroxyl value-56.1×10 3 ); The hydroxyl value was determined using the phthalic anhydride method: based on the esterification reaction between phthalic anhydride and hydroxyl groups, excess phthalic anhydride was titrated with a standard sodium hydroxide solution, using phenolphthalein as an indicator, and the hydroxyl value was calculated based on the volume of sodium hydroxide solution consumed. The specific procedure was as follows: approximately wg (calculated by dividing 561 by the estimated hydroxyl value, unit: g) of sample was weighed and placed in an Erlenmeyer flask, and 25 mL of phthalic anhydride acylation reagent (GB / T 12008.3-2009) was added. The flask was shaken until the sample dissolved. An air condenser was attached to each Erlenmeyer flask, and the flask was placed in an oil bath at (105±2)℃ for 30 min. After heating, the apparatus was removed from the oil bath and cooled to room temperature. The condenser was rinsed with 30 mL of pyridine and then removed. Using phenolphthalein as an indicator, titration was performed with 0.5 mol / L potassium hydroxide solution; and a blank test was conducted under the same conditions. Let the volume of titrant consumed in the blank test be a (mL), the volume of titrant consumed in the sample solution be b (mL), and the sample volume be w (g). The hydroxyl value was calculated by hydroxyl value = (ab) × 28.05 / w. 2.¹³C-NMR Analysis: 200 mg of polyglycerol was dissolved in 0.6 mL of heavy water. A 100 MHz¹³C-NMR instrument was used for analysis in single-pulse¹H decoupling mode. Pulse repetition time: ≥10 seconds; cumulative count: ≥256; internal standard: acetone (30.89 ppm). Based on the carbon signal integral values ​​corresponding to the bonding modes with the polyglycerol backbone (including 1,3-bonded main chain, 1,2-bonded and branched structures), the degree of branching, primary hydroxyl ratio, and secondary hydroxyl ratio were calculated.

[0075] Specifically, the five structures of polyglycerol are as follows: Figure 1As shown, D, L13, L14, T1, and T2 are represented. The aforementioned polyglycerol will exhibit peaks A through H in its carbon NMR spectrum, which are identified as carbon atoms at specific positions within each structure. The proportions of the five structures D, L13, L14, T1, and T2 are calculated using the integral ratios of each peak.

[0076] The proportion of D-structures: D = {C}, where {C} is the integral area of ​​peak C; The proportion of L13 structure: L13 = {I}, where {I} is the integral area of ​​peak I; The proportion of L14 structure: L14 = {D} / 2, where {D} is the integral area of ​​peak D; The degree of branching is calculated by the following formula: DB = 2D / (2D + L13 + L14); based on the presence ratio of each structure of polyglycerol, the presence ratio of primary hydroxyl groups is: L13 / ( L13+L14), and the presence ratio of secondary hydroxyl groups is: L14 / ( L13+L14).

[0077] The specific test results are shown in Table 1.

[0078] Table 1

[0079] Synthesis example 1 This embodiment provides a method for preparing polyglycerol fatty acid esters, and the preparation steps are as follows: 63.1 g (0.043 mol) of polyglycerol 2 prepared in Example 1 and 36.9 g (0.256 mol) of decanoic acid were added to a stainless steel reactor, along with 0.2 g of sodium hydroxide as a catalyst. The reactor was heated to 240 °C under a nitrogen atmosphere with stirring. Water generated in the reaction system was removed by nitrogen purging, and the reaction was continued for 5 hours. The reaction was continued until the acid value dropped below 2 mg KOH / g. After the reaction was complete, the reaction solution was cooled, neutralized with acetic acid, filtered to remove salt, and unreacted fatty acids and solvent were removed by vacuum distillation. The resulting polyglycerol-20 decanoate was a pale yellow viscous liquid with a yield of 90%.

[0080] It should be noted that in Synthesis Example 1, linear polyglycerol with a degree of polymerization of 20 as in Preparation Example 1 was esterified with decanoic acid, and the average degree of esterification was 6. Therefore, the product was officially named polyglycerol-20 hexadecanoate. However, since the polyglycerol involved can be linear or non-linear, the technical name is "linear polyglycerol-20 hexadecanoate" to distinguish it. The other naming rules are similar.

[0081] Synthetic Examples 2-8 were prepared using methods similar to those of Synthetic Example 1, with the differences shown in Table 2. The test methods for each item in Table 2 are as follows: HLB value: The HLB value was determined using the formula HLB=20(1-S / A); where S is the saponification value of the surfactant sample obtained from the synthesis example, and A is the acid value of the fatty acid of the raw material used to synthesize the surfactant. The specific test results are as follows: S is determined by the following steps: Weigh a certain amount of sample m3 (2-10g) into an Erlenmeyer flask, add 25mL of ethanol and 25mL of potassium hydroxide ethanol solution. Attach a reflux condenser and maintain boiling for 60min (2h for samples difficult to saponify). After slightly cooling, add 1mL of phenolphthalein indicator, and titrate the blank and sample to the phenolphthalein endpoint with standardized 0.5mol / L hydrochloric acid solution. The volume difference (V0-V) between the hydrochloric acid used to neutralize the blank and the sample is the amount of potassium hydroxide consumed by the sample. The number of milligrams of potassium hydroxide required per gram of sample is the saponification value. Saponification value S = (V0-V) × 28.05 / m3.

[0082] A was determined by the following steps: A certain amount of sample m4 (5g~6g) was weighed into the conical flask mentioned above, and the mass of the sample was recorded to an accuracy of 0.1g; (50±10)mL of isopropanol and 1mL of phenolphthalein indicator were added to the conical flask; the solution in the conical flask was stirred or shaken until the sample was completely dissolved; the sample solution was titrated with 0.02 mol / L potassium hydroxide-methanol standard solution until a light pink color was obtained, and the titration was maintained for 30s as the endpoint, and the volume consumed was recorded as V. The acid value A = 1.122×V / m4, and the test results are shown in Table 2.

[0083] Table 2

[0084] Example 1 An oily cleansing composition is provided, the formulation of which is weighed according to the proportions of each component in Example 1 in Table 3. The preparation steps of the oily liquid cleansing composition include: 1. Add the oil and additives (skin-moisturizing oils and humectants) to a mixing container, heat at 50°C and mix evenly.

[0085] 2. Weigh polyglycerol medium-chain fatty acid ester (A) and polyglycerol long-chain fatty acid ester (B) in another container, and gently stir to mix them evenly to form a homogeneous surfactant mixture.

[0086] 3. Add the homogeneous surfactant mixture formed in the above steps to the oil in batches according to the mass in the table, and adjust the stirring speed to 150 rpm to disperse and dissolve it.

[0087] 4. After all the ingredients have dissolved evenly, cool to below 60°C.

[0088] 5. After cooling to room temperature, degas or filter again as needed to obtain a transparent, oily liquid or semi-solid oily cleansing composition.

[0089] Examples 1 to 7 and Comparative Examples 1 to 5 were prepared using similar steps to Example 1, except that the components and / or amounts of the oily cleansing compositions were different, as detailed in Table 3.

[0090] Table 3

[0091] Performance testing 1. The oily cleansing compositions obtained in Examples 1-7 and Comparative Examples 1-5 were tested. The tests included cleansing power test, rinseability test, and skin compatibility evaluation. The specific test methods are as follows: ① Cleaning power test: The artificial leather was cut into fixed specifications, and a certain amount of lipstick was evenly applied to the central area and dried to form a test area; during cleaning, 0.4g of the test cleansing composition was applied to the test area, massaged with fingertips for 30 seconds, rinsed with warm water for 10 seconds and dried; then, the test area was divided into several fine squares by covering it with transparent grid paper, and the area of ​​the squares covered by residual lipstick was counted; finally, the removal rate was calculated according to the formula, where the removal rate = (1 - residual lipstick area / total area of ​​the original test area) × 100%, and a removal rate of ≥85% was used as the criterion for good cleaning power.

[0092] ② Rinse-off test: A group of 10 subjects actually used the synthetic oil-based cleansing composition and evaluated the residual oiliness of the skin after cleansing on a 5-point scale. The criteria are shown in Table 4 below. Table 4

[0093] ③ Spreadability evaluation: At room temperature, approximately 50 μL of each test sample of the oily cleansing composition was applied to the inner arm of 10 subjects to define the test area. Subjects rated the smoothness and spreading resistance on a 5-point scale, and the average score was taken. A score of 4.0 or higher was considered good. The specific scoring criteria are shown in Table 5. Table 5 The test results of the above tests are recorded in Table 6.

[0094] Table 6 Test results of Examples 1 to 7 and Comparative Examples 1 to 5

[0095] As can be seen from Table 6, the oily cleansing compositions of the present invention (Examples 1-7) exhibit comprehensive and excellent technical effects in terms of cleansing power, easy rinsing upon contact with water, and ease of application.

[0096] In contrast, when esters derived from nonlinear polyglycerol skeletons are used (Comparative Examples 1-5), not only is the ability of the composition to dissolve and encapsulate makeup for cleaning significantly weakened, but also the low proportion of primary hydroxyl groups and large steric hindrance result in a severely delayed spontaneous emulsification rate when the system comes into contact with water, which manifests as extremely difficult rinsing and a severe suffocating feeling.

[0097] In Example 3, the total amount added was significantly reduced to an extremely low level (10% of the total amount), but the cleaning power test of Example 3 was still as high as 95%. In contrast, in Comparative Example 2, with the same low addition amount of 10%, the cleaning power dropped sharply to 37% due to the use of a non-linear framework. This shows that the linear high primary hydroxy ester of the present invention achieves high cleaning power at low concentrations. Furthermore, the spreadability scores of the high surfactant addition amount (20%) in Examples 1 and 2 are close to 5 points, indicating that there is no stickiness or astringency caused by traditional high surfactant addition amounts.

[0098] The above are merely preferred embodiments of the present invention and do not limit the patent scope of the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the patent protection scope of the present invention.

Claims

1. An oil-based cleansing composition, characterized in that, The product comprises linear polyglycerol medium-chain fatty acid esters, linear polyglycerol long-chain fatty acid esters, oils, and additives. The linear polyglycerol medium-chain fatty acid esters are formed by esterification of linear polyglycerol with medium-chain fatty acids, and the linear polyglycerol long-chain fatty acid esters are formed by esterification of linear polyglycerol with long-chain fatty acids. The average degree of polymerization of the linear polyglycerol is 6–40. The degree of branching in the linear polyglycerol is <0.20; the proportion of primary hydroxyl groups in the linear polyglycerol is ≥90% of all hydroxyl groups.

2. The oily cleansing composition as described in claim 1, characterized in that, The medium-chain fatty acids contain 6 to 10 carbon atoms; and / or, The medium-chain fatty acids include at least one of caprylic acid, capric acid, and isononanoic acid.

3. The oily cleansing composition as described in claim 2, characterized in that, The long-chain fatty acids have 12 to 22 carbon atoms; and / or, The long-chain fatty acids include at least one of lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, isostearic acid, and ricinoleic acid.

4. The oily cleansing composition as described in claim 1, characterized in that, The oily cleansing composition comprises, by weight percentage: Linear polyglycerol medium-chain fatty acid esters: 1%~30%; Linear polyglycerol long-chain fatty acid esters: 0.5%~15%; Oil content 60%~98.5%; The remainder are additives.

5. The oily cleansing composition as described in claim 1, characterized in that, The mass ratio of the linear polyglycerol medium-chain fatty acid ester to the linear polyglycerol long-chain fatty acid ester is 5:1 to 1:

2.

6. The oily cleansing composition as described in claim 1, characterized in that, The mass of the linear polyglycerol medium-chain fatty acid ester is m1, the mass of the linear polyglycerol long-chain fatty acid ester is m2, and the mass of the oily cleansing composition is m, satisfying that (m1+m2) / m<20%.

7. The oily cleansing composition as described in claim 1, characterized in that, The oiling agent includes at least one selected from natural oils, hydrocarbon oils, ester oils, glyceryl ester oils, and silicone oils; and / or, The additives include at least one of the following: humectants, emulsifiers, preservatives / antibacterial agents, antioxidants, fragrances, chelating agents, and light stabilizers.

8. The method for preparing the oily cleansing composition according to any one of claims 1 to 7, characterized in that, The method for preparing the oily cleansing composition includes: Linear polyglycerol was prepared by reacting the linear polyglycerol with medium-chain fatty acids and long-chain fatty acids respectively to obtain linear polyglycerol medium-chain fatty acid esters and linear polyglycerol long-chain fatty acid esters. The oil, the linear polyglycerol medium-chain fatty acid ester, and the linear polyglycerol long-chain fatty acid ester are mixed, stirred, and heated to obtain a mixture. After cooling the mixture, it is mixed with the additives, filtered, and an oily cleansing composition is obtained.

9. The method for preparing the oily cleansing composition according to claim 8, characterized in that, The steps for preparing linear polyglycerol include: Under inert gas protection, a glycerol derivative is subjected to ring-opening polymerization in an initiator and solvent to obtain the first intermediate; The first intermediate was stirred in an acidic aqueous solution to obtain the second intermediate; The second intermediate was purified to obtain linear polyglycerol.

10. The method for preparing the oily cleansing composition according to claim 9, characterized in that, The glycerol derivatives include at least one of EEGE, tBGE, and AGE; and / or, The acidic aqueous solution includes hydrochloric acid solution.

11. The application of an oily cleansing composition prepared by any one of claims 1 to 7 or any one of claims 8 to 10, wherein the application field includes skin care products or cosmetics.

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