A bicontinuous phase sunscreen spray composition and method of making same

Abstract

The application discloses a double-continuous-phase sunscreen spray composition without traditional emulsifiers and a preparation method thereof, and belongs to the technical field of cosmetics. The double-continuous-phase sunscreen spray composition without traditional emulsifiers is composed of the following components in percentage by mass: 20-35% of oil-soluble sunscreen agents, 10-16% of propylene glycol laurate, 40-60% of ethanol, 1-10% of polyethylene glycol-8 and 1-10% of water. The application applies propylene glycol laurate as a double-continuous-phase inducer to the field of sunscreen sprays, successfully prepares a stable double-continuous-phase system under the condition of not adding traditional emulsifiers through the synergistic effect of the unique molecular structure of propylene glycol laurate and ethanol, solves the transparent co-solubility problem of high-concentration oil-soluble sunscreen agents and water, and has excellent skin feel, high-efficiency sun protection, atomization effect and simple process, and has significant innovation and practical value.

Description

Technical Field

[0001] This invention relates to the field of cosmetic technology, specifically to a dual continuous phase sunscreen spray composition and its preparation method. Background Technology

[0002] Sunscreen sprays have become an important category in the sunscreen cosmetics market due to their ease of use and refreshing feel. However, existing sunscreen sprays have the following technical shortcomings: (1) Traditional oil-based sunscreen spray: The main solvent is oil. Although it can dissolve oil-soluble sunscreen agents well, the product is greasy and the skin is shiny after spraying, resulting in a poor user experience. In addition, the spray atomization effect is not good, and it is easy to form large droplets with uneven distribution.

[0003] (2) Traditional water-based sunscreen spray: It feels refreshing on the skin, but it is difficult to dissolve oil-soluble sunscreen agents, thus limiting its sun protection effect.

[0004] (3) Existing bicontinuous phase technology: It is currently mainly used in makeup removal products, and there are no reports of its system being applied to sunscreen sprays; moreover, the existing bicontinuous phase system relies on high concentrations of emulsifiers, which has the following problems: emulsifier residues may irritate sensitive skin; some emulsifiers have the potential to cause acne.

[0005] (4) Difficulty of the oil / water / ethanol ternary homogeneous transparent system: It is difficult to achieve the current technology to dissolve oil-soluble sunscreen agent and water into a transparent homogeneous system without adding traditional emulsifiers, as the oil and water will quickly separate.

[0006] Based on this, the present invention proposes a dual continuous phase sunscreen spray composition and its preparation method. Summary of the Invention

[0007] To address the shortcomings of the prior art, this invention provides a dual-continuous-phase sunscreen spray composition and its preparation method. This composition achieves transparent co-solubility of high-concentration oil-soluble sunscreen agents with water, eliminating the need for traditional emulsifiers. It yields a spray product that combines a refreshing feel with highly effective sun protection, achieving excellent atomization and producing uniform and fine droplets. Furthermore, it provides a simple preparation method that does not require emulsification equipment.

[0008] To achieve the above objectives, the present invention provides the following technical solution: A bicontinuous phase sunscreen spray composition comprising the following components by weight percentage: 20-35% oil-soluble sunscreen agent, 10-16% propylene glycol laurate, 40-60% ethanol, 1-10% polyethylene glycol-8, and 1-10% water.

[0009] Furthermore, the bicontinuous phase sunscreen spray composition comprises the following components in weight percentage: 25-30% oil-soluble sunscreen agent, 12-15% propylene glycol laurate, 45-50% ethanol, 5-8% polyethylene glycol-8, and 3-8% water.

[0010] Furthermore, the bicontinuous phase sunscreen spray composition comprises the following components in weight percentage: 30% oil-soluble sunscreen agent, 13% propylene glycol laurate, 45% ethanol, 6% polyethylene glycol-8, and 6% water.

[0011] Furthermore, the oil-soluble sunscreen agent is one or more of the following: homosalate, ethylhexyl salicylate, ethylhexyl methoxycinnamate, and octocrylene.

[0012] Furthermore, the oil-soluble sunscreen agent is a mixture of homosalate, ethylhexyl salicylate, ethylhexyl methoxycinnamate, and octocrylene.

[0013] Furthermore, the mass ratio of homosalate, ethylhexyl salicylate, ethylhexyl methoxycinnamate to octocrylene is (3-6):(3-5):(7-11):(7-13).

[0014] Furthermore, the mass ratio of homosalate, ethylhexyl salicylate, ethylhexyl methoxycinnamate, and octocrylene is 5:5:10:10.

[0015] This invention also provides a method for preparing a bicontinuous phase sunscreen spray composition, comprising the following steps: Step 1: Add the oil-soluble sunscreen agent and propylene glycol laurate to a container and stir at room temperature until completely dissolved and homogeneous to obtain a mixture; Step 2: Add ethanol to the mixture from Step 1 and continue stirring until transparent and homogeneous; Step 3: Under stirring conditions, slowly add polyethylene glycol-8 and water, and stir for 10-20 minutes until completely transparent and homogeneous; Step 4: Fill into spray bottles.

[0016] This invention discloses a dual-continuous-phase sunscreen spray composition and its preparation method, which have the following beneficial effects: This invention utilizes the unique molecular structure and physicochemical properties of propylene glycol laurate to successfully prepare a thermodynamically stable, transparent, and homogeneous bicontinuous phase system composed of an oil-soluble sunscreen agent, ethanol, and water without adding traditional emulsifiers.

[0017] When the proportions of each component fall within the specific range of this invention, the spontaneous curvature of the system approaches zero, and the interfacial tension is reduced to a minimum. The oil phase and the aqueous phase no longer exist in the form of "droplet dispersion," but instead form their own continuous and interwoven network structures in three-dimensional space—that is, "bicontinuous phases," which macroscopically appear as completely transparent homogeneous liquids.

[0018] This invention applies propylene glycol laurate as a bicontinuous phase inducer to the field of sunscreen sprays. Through its unique molecular structure and synergistic effect with ethanol, a stable bicontinuous phase system was successfully prepared without the addition of traditional emulsifiers. This solves the problem of transparent co-solubility of high-concentration oil-soluble sunscreens with water. It has excellent skin feel, high-efficiency sun protection, atomization effect and simple process, and has significant innovation and practical value. Attached Figure Description

[0019] Figure 1 The diagram shows the ternary phases of propylene glycol laurate / ethanol / water. Figure 2 These are photographs of the appearance of the products in Examples 1-5; Figure 3 A photograph of the product in Comparative Example 1; Figure 4 Here is a photograph of the appearance of the product in Comparative Example 2; Figure 5 Here is a photograph of the appearance of product 3 (Comparative Example 3); Figure 6 Photographs showing the spray effect of the product in Example 1; Figure 7 The image shows the spray effect of the product in Example 2. Detailed Implementation

[0020] The present invention will be described in detail below with reference to specific embodiments.

[0021] A bicontinuous phase sunscreen spray composition comprising the following components by weight percentage: 20-35% oil-soluble sunscreen agent, 10-16% propylene glycol laurate, 40-60% ethanol, 1-10% polyethylene glycol-8, and 1-10% water.

[0022] The propylene glycol laurate in this invention, acting as a bicontinuous phase inducer, is composed of a lipophilic long-chain lauric acid (C12) backbone and a hydrophilic propylene glycol group. The long-chain lauric acid (C12) exhibits strong lipophilicity, achieving infinite miscibility with oil-soluble sunscreens and ensuring complete dissolution of the oil phase. The propylene glycol group contains an active hydroxyl group (-OH), which can act as a hydrogen bond donor. With a topological polar surface area (TPSA) of 46.5 Ų, its moderate polarity allows for hydrogen bonding with water molecules without being excessively hydrophilic and causing precipitation from the oil phase. This molecular structure of "lipophilic long chain + hydrophilic head group capable of forming hydrogen bonds" is the molecular basis for its ability to function as a "bicontinuous phase inducer," fundamentally different from traditional emulsifiers.

[0023] The "traditional emulsifier-free" aspect of this invention refers to the absence of high molecular weight, high HLB value conventional emulsifiers that primarily function by forming classic micelles, such as PEG-20 glyceryl stearate and Tween-80. Existing technologies often rely on high-concentration emulsifier formulations, mechanically emulsifying to form droplet dispersion, resulting in poor atomization, large droplet formation, uneven distribution, and a poor user experience. Furthermore, high-concentration emulsifier formulations can leave residues, potentially irritating sensitive skin and posing a potential acne-causing risk. In contrast, propylene glycol laurate in this invention acts as a "structure inducer," with a fundamentally different mechanism of action compared to traditional emulsifiers. It does not rely on micelle formation but rather induces the formation of a continuous phase network, thus avoiding the irritation, acne-causing properties, and atomization interference associated with traditional emulsifiers.

[0024] In a ternary system composed of oil, ethanol, and water, propylene glycol laurate exhibits unique interfacial behavior: (1) Low interfacial tension. When the concentration of propylene glycol laurate is 10-16%, its molecules spontaneously accumulate at the oil-water micro-interface; its molecular structure can effectively reduce the interfacial tension between oil and water, even bringing it close to zero, which is a prerequisite for the formation of a bicontinuous phase. (2) Formation of a dynamic and flexible interfacial film. Unlike the rigid interfacial film of traditional emulsifiers, propylene glycol laurate forms a highly dynamic and flexible molecular film at the oil-water interface, which allows water and ethanol molecules to penetrate or approach the interfacial region to a certain extent, causing the oil and water phases to interweave and permeate at the interface. (3) Spontaneous curvature approaches zero. When the components reach the specific proportions of this invention, the spontaneous curvature of the interfacial film approaches zero, and the system no longer forms O / W or W / O droplets, but evolves into a bicontinuous phase. (See attached diagram) Figure 1 As shown, in the propylene glycol laurate / ethanol / water system, there is a significant large-area single-phase transparent region. When the proportion falls into this region, a stable, transparent, and homogeneous system can be formed.

[0025] In this invention, ethanol acts as a volatile solvent and skin feel modifier, providing a refreshing feel and promoting rapid drying of the spray. It also serves as a "molecular bridge" to dissolve both the oil and water phases. Ethanol in this invention is not only a solvent but also works synergistically with propylene glycol laurate. As an amphiphilic solvent, ethanol dissolves both the oil and water phases simultaneously, eliminating the polarity difference between them. Ethanol molecules insert into the interfacial membrane, increasing its fluidity and facilitating the formation of a bicontinuous phase. The presence of ethanol significantly expands the single-phase transparent region. The synergistic effect of propylene glycol laurate and ethanol allows the system to form a stable bicontinuous phase structure without the addition of traditional emulsifiers.

[0026] In this invention, polyethylene glycol-8 serves as a cosolvent and humectant, which can adjust the skin feel and improve the stability of the bicontinuous phase sunscreen spray composition system.

[0027] Existing technologies (such as Korean Patent KR100648535B1) disclose the preparation of stable emulsions and cosmetic compositions containing polycaprolactone-polyethylene glycol (PCL-PG) copolymers by increasing the solubility of PCL-PG copolymers. This involves dissolving the PCL-PG copolymer in a mixture selected from liquid organic sunscreens and propylene glycol fatty acid esters. The PCL-PG copolymer acts as an emulsion stabilizer, improving the stability of the emulsion. However, the resulting product is a white, opaque emulsion, which is inherently thermodynamically unstable, and the preparation process requires mechanical emulsification. In contrast, the method of this invention requires no heating, high-pressure homogenization, or complex emulsification equipment. It can be prepared simply by mixing at room temperature, resulting in a spontaneously formed continuous network, a transparent and homogeneous liquid, and thermodynamic stability.

[0028] In some embodiments, the bicontinuous phase sunscreen spray composition comprises the following components by weight percentage: 25-30% oil-soluble sunscreen agent, 12-15% propylene glycol laurate, 45-50% ethanol, 5-8% polyethylene glycol-8, and 3-8% water.

[0029] In one embodiment, the bicontinuous phase sunscreen spray composition comprises the following components by weight percentage: 30% oil-soluble sunscreen agent, 13% propylene glycol laurate, 45% ethanol, 6% polyethylene glycol-8, and 6% water.

[0030] In some embodiments, the oil-soluble sunscreen agent is one or more selected from homosalate, ethylhexyl salicylate, ethylhexyl methoxycinnamate, and octocrylene. The sunscreen agents selected in this invention are widely used in cosmetics, have high safety, and provide good sun protection.

[0031] In some embodiments, the oil-soluble sunscreen agent is a mixture of homosalate, ethylhexyl salicylate, ethylhexyl methoxycinnamate, and octocrylene.

[0032] In some embodiments, the mass ratio of homosalate, ethylhexyl salicylate, ethylhexyl methoxycinnamate to octocrylene is (3-6):(3-5):(7-11):(7-13).

[0033] In one embodiment, the mass ratio of homosalate, ethylhexyl salicylate, ethylhexyl methoxycinnamate, and octocrylene is 5:5:10:10.

[0034] This invention also provides a method for preparing a bicontinuous phase sunscreen spray composition, comprising the following steps: Step 1: Add the oil-soluble sunscreen agent and propylene glycol laurate to a container and stir at room temperature until completely dissolved and homogeneous to obtain a mixture; Step 2: Add ethanol to the mixture from Step 1 and continue stirring until transparent and homogeneous; Step 3: Under stirring conditions, slowly add polyethylene glycol-8 and water, and stir for 10-20 minutes until completely transparent and homogeneous; Step 4: Fill into spray bottles.

[0035] The preparation method of this invention requires no heating, no high-pressure homogenization, and no complex emulsification equipment; it can be prepared simply by mixing at room temperature. The process is simple, energy-efficient, and easy to industrialize.

[0036] The composition of this invention contains ethanol. It is recommended to operate under ventilation and explosion-proof conditions that meet national standards during production, which is the routine production requirement for cosmetics containing ethanol.

[0037] Examples 1-5 A dual-phase sunscreen spray is composed of the raw materials shown in Table 1 below: Table 1

[0038] The preparation methods of Examples 1-5 above include the following steps: Add homosalate, ethylhexyl salicylate, ethylhexyl methoxycinnamate, octocrylene, and propylene glycol laurate to a mixing tank and stir at room temperature until completely dissolved; add ethanol and continue stirring until transparent; while stirring, slowly add polyethylene glycol-8 and water, and stir for 10-20 minutes until completely transparent and homogeneous; fill into spray bottles.

[0039] Stability tests were conducted on Examples 1-5, and the results are shown in Table 2 below.

[0040] Table 2

[0041] As shown in Table 2, the sunscreen sprays prepared in Examples 1-5 are completely transparent, homogeneous liquids, such as... Figure 2 As shown (Examples 1-5 are arranged from left to right). The sunscreen sprays prepared in Examples 1-5 remained transparent and uniform, without sedimentation or layering, under conditions of 6 months at room temperature, 1 month at 45°C, and 1 month at 4°C, indicating that the sunscreen sprays prepared in Examples 1-5 have excellent stability. The SPF values ​​of Examples 1-5 are all above 30, indicating good sun protection effects. Spray tests were conducted on Examples 1-2, and the spray effects were as follows... Figures 6-7 As shown, the atomization is uniform and fine, and the spray atomization effect is good.

[0042] Comparative Example 1 The difference from Example 1 is that propylene glycol laurate was not added in Comparative Example 1, the amount of ethanol added was 50%, the amount of polyethylene glycol-8 added was 10%, and the amount of water added was 10%.

[0043] The preparation method of Comparative Example 1 was the same as that of Example 1, but propylene glycol laurate was omitted. In the preparation steps, turbidity appeared immediately after the addition of water, and clear separation occurred after standing for 10 minutes. Figure 3 As shown, a homogeneous system cannot be formed. This indicates that ternary cosolubility of oil, water, and alcohol cannot be achieved without the addition of propylene glycol laurate.

[0044] Comparative Example 2 The difference from Example 1 is that in Comparative Example 2, propylene glycol laurate was replaced with PEG-20 glyceryl isostearate.

[0045] The preparation method for Comparative Example 2 was the same as that for Example 1, but PEG-20 glyceryl isostearate was used instead of propylene glycol laurate. In the preparation steps, turbidity appeared immediately upon addition of water, and clear separation occurred after standing for 10 minutes. Figure 4 As shown, a homogeneous system could not be formed. This indicates that conventional emulsifiers cannot replace propylene glycol laurate to achieve a long-term stable, transparent, and homogeneous system.

[0046] Comparative Example 3 The difference from Example 1 is that in Comparative Example 3, propylene glycol laurate was replaced with caprylic / capric glyceride.

[0047] The preparation method of Comparative Example 3 was the same as that of Example 1, but glyceryl caprylate was used instead of propylene glycol laurate. In the preparation step, turbidity appeared immediately after the addition of water, and clear separation occurred after standing for 10 minutes. Figure 5 As shown, a homogeneous system could not be formed. This indicates that conventional oil substitutes for propylene glycol laurate cannot achieve a long-term stable, transparent, and homogeneous system.

[0048] Comparative Examples 1-3 show that without propylene glycol laurate, the oil and water quickly separate into layers (Comparative Example 1); when a conventional emulsifier (PEG-20 glyceryl isostearate) is used instead of propylene glycol laurate, a transparent system cannot be formed, and the system immediately becomes cloudy and separates into layers upon the addition of water (Comparative Example 2); when a conventional oil (GTCC) is used instead of propylene glycol laurate, cloudy separation also occurs (Comparative Example 3). This demonstrates that propylene glycol laurate has a unique and irreplaceable function.

[0049] This invention applies propylene glycol laurate as a bicontinuous phase inducer to the field of sunscreen sprays. Through its unique molecular structure and synergistic effect with ethanol, a stable bicontinuous phase system was successfully prepared without the addition of traditional emulsifiers. This solves the problem of transparent co-solubility of high-concentration oil-soluble sunscreens with water. It has excellent skin feel, high-efficiency sun protection, atomization effect and simple process, and has significant innovation and practical value.

[0050] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A dual-continuous-phase sunscreen spray composition, characterized in that, It is composed of the following components by weight percentage: 20-35% oil-soluble sunscreen agent, 10-16% propylene glycol laurate, 40-60% ethanol, 1-10% polyethylene glycol-8, and 1-10% water; wherein the oil-soluble sunscreen agent is a mixture of homosalate, ethylhexyl salicylate, ethylhexyl methoxycinnamate, and octocrylene.

2. The dual continuous phase sunscreen spray composition according to claim 1, characterized in that, It consists of the following components by weight percentage: 25-30% oil-soluble sunscreen, 12-15% propylene glycol laurate, 45-50% ethanol, 5-8% polyethylene glycol-8, and 3-8% water.

3. The dual continuous phase sunscreen spray composition according to claim 2, characterized in that, It consists of the following components by weight percentage: 30% oil-soluble sunscreen, 13% propylene glycol laurate, 45% ethanol, 6% polyethylene glycol-8, and 6% water.

4. The dual continuous phase sunscreen spray composition according to claim 1, characterized in that, The mass ratio of homosalate, ethylhexyl salicylate, ethylhexyl methoxycinnamate and octocrylene is (3-6):(3-5):(7-11):(7-13).

5. The dual continuous phase sunscreen spray composition according to claim 4, characterized in that, The mass ratio of homosalate, ethylhexyl salicylate, ethylhexyl methoxycinnamate and octocrylene is 5:5:10:

10.

6. A method for preparing the bicontinuous phase sunscreen spray composition according to any one of claims 1-5, characterized in that, Includes the following steps: Step 1: Add the oil-soluble sunscreen agent and propylene glycol laurate to a container and stir at room temperature until completely dissolved and homogeneous to obtain a mixture; Step 2: Add ethanol to the mixture from Step 1 and continue stirring until transparent and homogeneous; Step 3: Under stirring conditions, slowly add polyethylene glycol-8 and water, and stir for 10-20 minutes until completely transparent and homogeneous; Step 4: Fill into spray bottles.

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