Color-protecting integrated lipstick with multiphase structure and preparation method of color-protecting integrated lipstick

Abstract

The invention relates to a color-protecting integrated lipstick with a multiphase structure and a preparation method of the color-protecting integrated lipstick. The lipstick comprises an outer phase makeup layer and an inner phase nursing layer which are coaxial in the axial direction, an outer phase is composed of hydroxypropyl starch phosphate, pullulan, vegetable oil, a wax composition, a pigment system and a small amount of water and polyhydric alcohols, and an inner phase is composed of pullulan, hydroxypropyl starch phosphate, polyhydric alcohols, water, vegetable oil and a modified starch thickening agent. And the ratio of polysaccharide in the two phases, the content of water and polyhydric alcohols and the range of storage modulus at 32 DEG C are limited. The preparation process comprises the following steps: melting and shearing an outer phase, dissolving an inner phase into gel, injecting the inner phase to form a semi-cured inner core, coating the outer phase, and cooling and molding in sections. According to the invention, mechanical matching and interface stability of the makeup layer and the nursing layer are realized, the formability and storage stability of the rod body are improved, and smooth smearing and moisturizing effects are achieved.

Description

Technical Field

[0001] This invention relates to the technical field of applications of natural polysaccharides and their modified products, and in particular to a multiphase structure integrated color-protecting lipstick and its preparation method. Background Technology

[0002] Lipstick products are typically composed of oils, waxes, pigments, and film-forming agents. These components are melted, mixed, and then molded to achieve makeup effects such as color development, film formation, lubrication, and coverage. Most existing lipstick formulas employ a homogeneous single-phase structure, with the components exhibiting a relatively uniform distribution throughout the stick, providing a certain level of basic performance in terms of color rendering, mechanical strength, and application feel. In recent years, some products have attempted to introduce lipstick cores or dual-color structures, incorporating a different composition inside the stick than the outer layer to provide additional moisturizing or repairing effects. However, such structures generally suffer from significant differences in mechanical properties between the inner and outer phases, insufficient interfacial adhesion, a tendency for core misalignment or breakage after cooling and molding, and asynchronous deformation of the two phases during use. It is difficult to simultaneously achieve good performance in terms of color layer stability, application smoothness, and moisturizing properties.

[0003] In addition, hydrophilic ingredients such as polysaccharide derivatives, hyaluronic acid, and polyols have been used in lip care products to improve adhesion and moisturizing capabilities; wax systems and pigment systems are used in lipsticks to provide structure and color rendering. However, when these ingredients are applied to multiphase stick products, factors such as the proportion of ingredients in different phases, changes in water and polyol content, interactions between different film-forming components, and differences in the mechanical properties of inner and outer layers can all affect the stick's forming quality, interface stability, deformation behavior during application, and the final skin feel.

[0004] Therefore, there is an urgent need for a color-protecting lipstick that can combine stable color rendering, structural integrity, and moisturizing properties in a single stick, and that can solve the problems of existing multiphase lipsticks in terms of interfacial adhesion, mechanical consistency, and stability in use. Summary of the Invention

[0005] The purpose of this invention is to overcome the above-mentioned problems existing in the prior art and provide a multiphase structure color-protecting integrated lipstick and its preparation method, so that the lipstick has good overall formability, interface stability and structural consistency during use in the structural form of the coexistence of color layer and protection layer, and realizes the combination of makeup and protection functions in the same stick.

[0006] To achieve the above objectives, the first aspect of the present invention provides a multiphase structure integrated color and care lipstick, wherein the lipstick comprises an outer phase makeup layer and an inner phase care layer coaxially arranged along the axial direction: the outer phase makeup layer matrix comprises, by weight, 10-35 parts hydroxypropyl starch phosphate; 2-10 parts pullulan; 15-35 parts vegetable oil; 10-25 parts wax composition; 5-20 parts pigment system, including inorganic pigments and organic pigments; 0.1-2 parts sodium hyaluronate; 5-25 parts polyol moisturizer; 5-20 parts water; the inner phase care layer comprises, by weight, 5-20 parts pullulan; 0.1-3 parts sodium hyaluronate; 5-20 parts polyol moisturizer; 1-8 parts polyol moisturizer; 1-5 parts water; 5-20 parts vegetable oil; 1-8 parts modified starch thickener; wherein: a) The mass ratio of hydroxypropyl starch phosphate to pullulan in the outer phase makeup layer is 2–6:1; b) The mass ratio of pullulan to hydroxypropyl starch phosphate in the inner phase protective layer is 1:0.2–1; c) The mass ratio of total polysaccharide derivatives in the outer phase makeup layer to total polysaccharide derivatives in the inner phase protective layer is 0.5–1.5:1.

[0007] As a further improvement of the present invention, the degree of substitution of the hydroxypropyl starch phosphate is 0.05 to 0.25, the weight-average molecular weight is 20,000 to 300,000, and the molecular weight distribution index is 1.5 to 3.0.

[0008] As a further improvement of the present invention, the pullulan has a weight-average molecular weight of 50,000 to 800,000, and the mass ratio of pullulan to sodium hyaluronate in the outer phase makeup layer is 3:1 to 15:1, while the mass ratio of pullulan to sodium hyaluronate in the inner phase protective layer is 2:1 to 10:1.

[0009] As a further improvement of the present invention, the wax composition includes beeswax, carnauba wax and microcrystalline wax, wherein beeswax accounts for 20-40 wt%, carnauba wax accounts for 15-35 wt%, and microcrystalline wax accounts for 30-60 wt%, and the dropping point of the outer phase cosmetic layer is 65-80°C.

[0010] As a further improvement of the present invention, the inorganic pigments in the outer phase cosmetic layer include mica, titanium dioxide and iron oxide, wherein the particle size D50 of the titanium dioxide is 80-200 nm, and the mass ratio of inorganic pigments to organic pigments is 2:1-10:1.

[0011] As a further improvement of the present invention, the polyol moisturizer in the inner phase protective layer includes at least two of glycerin, propylene glycol and butylene glycol, with a total mass fraction of 10-30% by mass, and the total mass fraction of water and polyol in the inner phase protective layer is 20-45% by mass, while the total mass fraction of water and polyol in the outer phase makeup layer does not exceed 10% by mass.

[0012] The second aspect of the present invention provides a method for preparing a multiphase structured color-protecting lipstick as described above, comprising the following steps: (1) preparing an external phase makeup matrix: Hydroxypropyl starch phosphate, pullulan, vegetable oil, and wax composition are heated and melted at 80-90°C and stirred for 10-40 minutes to obtain a homogeneous melt; pigment system and sodium hyaluronate are added at 70-80°C, and shear dispersion is performed at 3000-6000 rpm for 2-6 minutes to obtain an external phase cosmetic melt; (2) Preparation of the internal phase maintenance substrate: Pullulan, sodium hyaluronate, polyol humectant, vegetable oil, and modified starch thickener are stirred and dissolved at 60–75°C for 10–30 min to obtain an internal phase protective melt. (3) Molding: The inner phase protective melt is injected into the central area of ​​the lipstick mold cavity at a temperature of 35-45°C and left to stand for 10-60 seconds to form a semi-solidified inner core; then, an outer phase makeup melt at a temperature of 70-80°C is injected into the mold to cover it. (4) Cooling and curing: The molded system was first cooled at 15–25°C for 10–30 min, and then cooled a second time at 0–8°C for 20–60 min. The resulting multiphase structure color-protecting integrated lipstick was then demolded.

[0013] As a further improvement of the present invention, after the shearing and dispersion in step (1) is completed, the external phase makeup melt is kept at 70-75°C for 3-10 minutes, and then cooled to 60-65°C at a cooling rate of 1-3°C / min before injection molding.

[0014] As a further improvement of the present invention, in step (3), the amount of the inner phase protective melt injected accounts for 10-40% of the total mass of the lipstick, and the surface hardness of the inner phase protective melt during the stage of forming a semi-solidified inner core is 0.03-0.2 N / mm. 2 .

[0015] As a further improvement of the present invention, the storage modulus G' of the outer phase makeup layer at 32°C and 1Hz is 1×10⁻⁶. 4 ~8×10 4The storage modulus G' of the inner phase protective layer under the same conditions is 0.4 × 10 Pa. 4 ~4×10 4 Pa, and the overall shaft diameter of the lipstick stick measured at 32℃. The present invention, using the above technical solution, has the following beneficial effects: This invention relates to a multiphase structure lipstick that integrates color and lip care. It constructs a coaxial outer phase makeup layer and an inner phase nourishing layer, introducing different types and proportions of polysaccharide derivatives, water, and polyol moisturizers into both phases to create a stable core-shell gradient system. The outer phase makeup layer, composed primarily of hydroxypropyl starch phosphate and pullulan, forms a polysaccharide network combined with wax compositions and pigment systems, providing the necessary stick strength, film-forming properties, and colorfastness. The inner phase nourishing layer, mainly composed of pullulan, sodium hyaluronate, and a high content of polyols and water, forms a soft, water-rich moisturizing network. The two phases are designed holistically at the formulation level by considering the differences in polysaccharide types, proportions, and the content of water and polyols, resulting in a core-shell structure with controlled differences in hardness and modulus. This allows for the simultaneous achievement of color rendering and lip care effects in a single lipstick.

[0016] The parameter windows of the polysaccharide system and the aqueous polyol system in the outer phase makeup layer and the inner phase nourishing layer are key to achieving the comprehensive performance of this invention. The mass ratio of hydroxypropyl starch phosphate to pullulan in the outer phase makeup layer is limited to a specific range, while the total polysaccharide content and the total content of water plus polyols in the outer phase are restricted to a lower range, resulting in an outer phase with a performance of 1×10⁻⁶ at 32°C. 4 ~8×10 4 The high storage modulus G' and apparent hardness of Pa provide stable structural support and good color adhesion during application. The mass ratio of pullulan to hydroxypropyl starch phosphate, and the total mass fraction of water and polyol in the inner phase protective layer are limited to a range higher than that of the outer phase, resulting in a storage modulus G' of 0.4 × 10⁻⁶ under the same conditions for the inner phase. 4 ~4×10 4 Pa is significantly lower than that of the outer phase, forming a soft, easily flowing moisturizing core. By limiting the G' ratio of the outer and inner phases to a specific range and ensuring that the hardness difference between the two ends of the entire lipstick does not exceed a given percentage, this invention ensures the overall mechanical stability of the stick while enabling the color-developing layer and the nourishing core to deform and migrate synchronously during application, avoiding the problems of core collapse, shell breakage, or phase separation commonly found in existing core-shell lipsticks.

[0017] The molecular weight distribution parameters of the polysaccharide derivative further ensure the feasibility and stability of the aforementioned structure and rheological window. By controlling the degree of substitution and weight-average molecular weight of hydroxypropyl starch phosphate within a specific range and limiting its molecular weight distribution index (PDI) to 1.5–3.0, the polysaccharide backbone simultaneously contains a certain proportion of long-chain and short-chain components. The long-chain portion forms a skeletal network supporting the external phase and interface, while the short-chain portion improves the fluidity of the melt system and the wettability of the pigment. Outside this distribution range, the polysaccharide is either too monodisperse, resulting in insufficient rod strength and decreased pigment dispersion stability, or highly polydisperse, leading to phase separation and uneven cooling shrinkage in the melt system. This invention, through precise definition of the polysaccharide molecular weight structure, combined with the content windows of water and polyols in the two phases and the G' parameter, improves the forming process and long-term storage stability of the core-shell structure.

[0018] The pigment and wax systems are further coordinated with the polysaccharide network and core-shell structure to achieve a balance between color rendering and durability. By selecting a pigment system including mica, titanium dioxide, iron oxide, and cosmetic-grade organic pigments in the external phase, and limiting the mass ratio of inorganic to organic pigments and the particle size range of titanium dioxide, a high-coverage, high-saturation color rendering layer is formed under given polysaccharide network and modulus conditions, while also considering gloss and smoothness. The proportions of beeswax, carnauba wax, and microcrystalline wax in the wax composition are controlled within a specific range, so that the dropping point and yielding behavior of the external phase synergize with the aforementioned polysaccharide network, forming a rod-like surface that neither collapses nor lacks smoothness around 32°C.

[0019] The temperature and shearing steps in the preparation method provide the necessary process assurance for the realization of the above structure. The outer phase cosmetic layer is prepared by melting polysaccharides, oils, and waxes at 80–90℃, introducing pigments at 70–80℃ and shearing and dispersing them at 3000–6000 rpm, and then controlling the cooling to a specific injection temperature to ensure that the polysaccharide network remains flowable while the pigments are uniformly wetted. The inner phase protective layer is prepared by dissolving polysaccharides, water, and polyols at 60–75℃, and first injecting them into the mold at a lower temperature to form a semi-cured core with a surface hardness within a set window. Then, the injected outer phase melt is encapsulated. Through a two-stage cooling and solidification process (high temperature followed by low temperature), the core-shell interface is solidified while the core still retains a certain degree of adhesion. These overall process parameters avoid problems such as the core being washed away, drifted, or deformed during the encapsulation process, and also avoid voids and debonding caused by asynchronous shrinkage of the shell and core. This ensures that the polysaccharide network, water-polyol distribution, and pigment distribution are spatially solidified and stabilize the core-shell structure.

[0020] In summary, this invention, by synergistically regulating the types and molecular weight distribution of polysaccharides, the content of water and polyols, the composition of the pigment system, and the G' modulus window in the outer phase makeup layer and the inner phase nourishing layer, and in conjunction with specific injection molding and cooling processes, enables the lipstick to achieve comprehensive performance of structural stability, long-lasting color, smooth application, and high moisturizing properties in the same stick. Detailed Implementation

[0021] The following provides a detailed description of specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0022] Unless otherwise defined, all scientific and technical terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art.

[0023] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all 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.

[0024] Unless otherwise specified, all materials and reagents used in the following examples are commercially available.

[0025] The present invention will now be described in detail with reference to specific embodiments, which are intended to understand rather than limit the invention.

[0026] The main functional raw materials used in the embodiments of this invention are all commercially available cosmetic-grade materials with clear sources and well-defined structures, as detailed below: 1. Hydroxypropyl starch phosphate The product used is STRUCTURE® XL, manufactured by Nouryon, a cosmetic-grade pregelatinized hydroxypropyl starch phosphate, INCI name Hydroxypropyl Starch Phosphate. With a degree of substitution of approximately 0.1–0.2, it is suitable for use in makeup and emulsion systems.

[0027] 2. Pruland The product uses cosmetic-grade Pullulan from Nagase Viita Co., Ltd. of Japan. Pullulan is a high-purity fermented polysaccharide with the INCI name Pullulan, and its weight-average molecular weight can be selected from 5 × 10⁻⁶. 4 ~8×10 5 Within the range.

[0028] 3. Sodium hyaluronate Using Bloomage Biotech's cosmetic-grade sodium hyaluronate (MW 8×10) 5 ~1.5×10 6 ).

[0029] 4. Modified starch-based thickeners The FARMAL® MS 6135 (INCI: Calcium Starch Octenylsuccinate) from Ingredion is used.

[0030] 5. Pigment system (cosmetic grade) Mica, titanium dioxide, and iron oxide are selected from Merck's Timiron® pearlescent powder and cosmetic-grade Fe2O3 / FeOOH series. All are publicly available models for use in makeup.

[0031] Other ingredients such as glycerin, propylene glycol, butylene glycol, vegetable oils, beeswax, carnauba wax, microcrystalline wax, caprylic / capric triglyceride, sweet almond oil, and jojoba oil are all common cosmetic-grade raw materials that can be identified and obtained directly by those skilled in the art without requiring a specific type.

[0032] Example 1: The hydroxypropyl starch phosphate used in this example is Nouryon's STRUCTUREXL (INCI name: Hydroxypropyl Starch Phosphate); pullulan is cosmetic grade pullulan produced by Nagase Viita Co., Ltd.; sodium hyaluronate is cosmetic grade sodium hyaluronate produced by Bloomage Biotechnology (weight average molecular weight approximately 1×10⁻⁶). 6 The modified starch thickener is Ingredion's FARMAL MS 6135 (INCI: Calcium Starch Octenylsuccinate). All raw materials are cosmetic grade.

[0033] The outer phase makeup layer of the multiphase structure color-protecting integrated lipstick prepared in this embodiment includes, by weight, the following components: 22 parts hydroxypropyl starch phosphate, 5 parts pullulan, 14 parts sweet almond oil, 10 parts caprylic / capric triglyceride, 7 parts beeswax, 5 parts carnauba wax, 8 parts microcrystalline wax, 4 parts mica (silica-coated type, Merck Timiron series), 4 parts titanium dioxide (particle size D50 of 80-200nm), 3 parts iron oxide pigment, 1 part organic pigment, 0.5 parts sodium hyaluronate, 4 parts glycerin, 4 parts propylene glycol, and 8.5 parts water.

[0034] The inner phase protective layer, by weight, comprises: pullulan 14 parts, hydroxypropyl starch phosphate 3 parts, sodium hyaluronate 0.8 parts, glycerin 12 parts, butylene glycol 6 parts, water 9 parts, jojoba oil 6 parts, shea butter 4 parts, and FARMALMS 61355 parts. The inner phase injection volume accounts for approximately 30 wt% of the final lipstick's total weight.

[0035] The preparation method is as follows: (1) Preparation of the external phase makeup matrix: 22 parts of hydroxypropyl starch phosphate, 5 parts of pullulan, 14 parts of sweet almond oil, 10 parts of caprylic / capric triglyceride, 7 parts of beeswax, 5 parts of carnauba wax, and 8 parts of microcrystalline wax were added to a vacuum melting vessel equipped with stirring and heating functions. The mixture was heated at 85°C and stirred for 25 min to completely melt the polysaccharide and oil / wax components and form a uniform and transparent mixed system. The system was then cooled to 75°C, and a premixed pigment system (including 4 parts of mica, 4 parts of titanium dioxide, 3 parts of iron oxide pigment, and 1 part of organic pigment) and 0.5 parts of sodium hyaluronate were added under continuous stirring. The mixture was then dispersed using a high-speed homogenizer at a shear rate of 4500 rpm for 4 min to fully wet and uniformly disperse the pigments in the external phase. After shearing, the system was kept at 72°C for 5 min to allow the polysaccharide segments to rearrange appropriately to form a stable continuous phase network. The system was then cooled to 62°C at a rate of approximately 2°C / min, which was used as the molding temperature for the outer phase makeup layer melt, for later use.

[0036] (2) To prepare the inner phase protection matrix, 12 parts glycerol, 6 parts butanediol, and 9 parts water were added to another stirred tank and stirred at room temperature for 5 min to form a homogeneous aqueous phase. Then, 14 parts pullulan, 3 parts hydroxypropyl starch phosphate, 0.8 parts sodium hyaluronate, and 5 parts modified starch FARMALMS6135 were added, and the system was heated to 65°C and stirred for 20 min to completely dissolve the polysaccharides and modified starch to form a homogeneous high-viscosity solution. After that, 6 parts jojoba oil and 4 parts shea butter were added, and stirring was continued for 10 min to form a homogeneous and stable inner phase melt.

[0037] (3) Molding: Preheat the metal lipstick mold to 40°C. Inject the inner phase protective melt into the central area of ​​the mold cavity using a metered injection method, with the injection volume accounting for approximately 30 wt% of the total product mass. After injection, let the mold stand for 30 seconds to allow the inner phase temperature to drop to approximately 45°C. At this point, the surface hardness of the semi-cured inner phase structure is measured to be approximately 0.08 N / mm. 2 The coating conditions are met. In this semi-cured state, the external phase makeup melt at 62°C is injected along the mold axis until the mold cavity is completely filled.

[0038] (4) Cooling and solidification: Place the mold with the injection completed in a 20°C environment for 20 minutes to allow the outer and inner phases to shrink synchronously and initially set; then transfer the mold to a 5°C environment and continue cooling for 40 minutes to allow the core-shell structure to fully solidify and form a stable adhesion at the interface. Finally, restore the mold to room temperature and demold to obtain a complete multiphase structure color-protecting integrated lipstick.

[0039] Performance test results of this embodiment: Under conditions of 32℃ and 1Hz, the external phase storage modulus measured by a rheometer is 4.5×10⁻⁶. 4 Pa, internal phase storage modulus is 1.6 × 10⁻⁶. 4 Pa. The hardness difference between the top and bottom of the product stick at 32°C, measured using a hardness tester, was approximately 12%. After storage at 25°C and 50% relative humidity for 3 months, no shell collapse, core shift, interface cracking, or delamination was observed. In artificial skin model testing, skin moisture content increased by approximately 22% 4 hours after application.

[0040] Example 2: The difference between this example and Example 1 is the increased content of internal phase polyols and water, as detailed below: The outer phase makeup layer, by weight, comprises: 24 parts hydroxypropyl starch phosphate, 4 parts pullulan, 23 parts vegetable oil (including 14 parts sweet almond oil and 9 parts caprylic / capric triglyceride), 21 parts wax composition (8 parts beeswax, 4 parts carnauba wax, and 9 parts microcrystalline wax), 11 parts pigment system (4 parts mica, 4 parts titanium dioxide, 2 parts iron oxide pigment, and 1 part organic pigment), 0.5 parts sodium hyaluronate, 7 parts polyol (4 parts glycerin and 3 parts propylene glycol), and 9.5 parts water.

[0041] The inner phase protective layer, by weight, comprises: pullulan 16 parts, hydroxypropyl starch phosphate 4 parts, sodium hyaluronate 1.0 part, polyol 22 parts (glycerin 14 parts, butylene glycol 8 parts), water 12 parts, vegetable oil 8 parts (jojoba oil 5 parts, squalane 3 parts), and FARMAL MS 6135 5 parts. The inner phase accounts for 25 wt% of the total weight of the lipstick.

[0042] Tests showed that the external phase storage modulus was 5.2 × 10⁻⁶ at 32℃ and 1 Hz. 4 Pa, internal phase storage modulus is 1.2 × 10⁻⁶. 4 Pa; the hardness difference between the two ends of the rod at 32℃ is about 15%; no structural defects occurred after storage for 3 months at 25℃ and 50% relative humidity; artificial skin model test showed that its water content increased by about 26% after 4 hours.

[0043] Example 3: The difference between this example and Example 1 is that the proportions of the multiphase structure color-protecting lipstick are different, as follows: The external phase by weight includes: 26 parts of hydroxypropyl starch phosphate, 5 parts of pullulan, 12 parts of castor oil, 8 parts of caprylic / capric triglyceride, 24 parts of wax composition (9 parts of beeswax, 7 parts of carnauba wax, and 8 parts of microcrystalline wax), 15 parts of pigment system (5 parts of mica, 6 parts of titanium dioxide, 3 parts of iron oxide pigment, and 1 part of organic pigment), 0.5 parts of sodium hyaluronate, 4 parts of polyol, and 5.5 parts of water.

[0044] The internal phase, by weight, comprises: pullulan 12 parts, hydroxypropyl starch phosphate 3 parts, sodium hyaluronate 0.8 parts, polyol 16 parts (10 parts water-soluble glycerol, 6 parts butylene glycol), water 8 parts, vegetable oil 12 parts (7 parts sweet almond oil, 5 parts squalane), and FARMAL MS 6135 4 parts. The internal phase accounts for approximately 20 wt% of the total mass.

[0045] Example 4: The difference between this example and Example 1 is that the proportions of the multiphase structure color-protecting lipstick are different, as follows: The external phase by weight includes: 20 parts of hydroxypropyl starch phosphate, 5 parts of pullulan, 26 parts of vegetable oil (16 parts of sunflower seed oil, 10 parts of caprylic / capric triglyceride), 19 parts of waxes (7 parts of beeswax, 5 parts of carnauba wax, 7 parts of microcrystalline wax), 11 parts of pigment system, 0.5 parts of sodium hyaluronate, 6 parts of polyol and 12.5 parts of water.

[0046] The internal phase consisted of: pullulan 13 parts, hydroxypropyl starch phosphate 3 parts, sodium hyaluronate 0.8 parts, polyol 15 parts (glycerol 9 parts, butanediol 6 parts), water 8 parts, vegetable oil 16 parts (jojoba oil 10 parts, squalane 6 parts), and FARMAL MS 6135 4 parts. The internal phase accounted for 35 wt% of the total mass.

[0047] Comparative Example 1: Except for the ratio of water and polyol in the external phase, the raw materials, apparatus, and operating conditions in this comparative example are exactly the same as in Example 1. In this comparative example, the polyol in the external phase is adjusted to 18 parts and the water is adjusted to 14.5 parts, with the total reaching 32.5 wt%, which is significantly higher than the external phase limit of no more than 10 wt% specified in this invention.

[0048] Due to the excessive softness of the outer phase, the storage modulus of the outer phase decreases to 0.9 × 10⁻⁶. 4 Pa, with an internal phase storage modulus of 1.6 × 10⁻⁶. 4 Pa no longer forms a gradient, causing the shell to collapse and the interface to delaminate after cooling and solidification. About 30% of the samples showed structural instability after one month of storage, and the integrity of the color development layer was significantly insufficient.

[0049] Comparative Example 2: In this comparative example, the external phase hydroxypropyl starch phosphate was increased to 30 parts and pullulan was reduced to 3 parts, so that the ratio reached 10:1. The proportions of other raw materials and steps (1)-(4) were the same as in Example 1.

[0050] Due to insufficient pullulan, the continuous polysaccharide phase in the outer phase is disrupted, reducing pigment wettability. Fine pigment aggregates can still be observed after high-speed shearing, resulting in uneven color development. The storage modulus of the outer phase of the finished product is increased but it becomes brittle and hard, easily flakes off during application, and its adhesion to the inner phase is significantly worse. Cracks appear at the interface after cooling, resulting in poor overall core-shell stability.

[0051] Comparative Example 3: In this comparative example, the amount of internal phase hydroxypropyl starch phosphate was increased to 10 parts, while pullulan was only 14 parts. All other conditions were the same as in Example 1.

[0052] During internal phase molding, the rate of decrease in semi-curing temperature slows down, and the surface hardness increases to 0.25 N / mm. 2 This is higher than the upper limit set by this invention by 0.2 N / mm. 2 This results in the internal phase failing to form a sufficient adhesion interface with the external phase during injection. After demolding, slight core misalignment and voids are visible, and the misalignment further increases after two months of storage.

[0053] Comparative Example 4: In this comparative example, the total amount of water and polyol in the internal phase was adjusted to only 15 wt%, and the rest of the operation was exactly the same as in Example 1.

[0054] Due to insufficient water and polyols, the internal phase cannot form a soft, water-rich moisturizing network, and its storage modulus rises to approximately 3.2 × 10⁻⁶. 4 Pa, being close to the external phase, cannot form a gradient structure. During application, insufficient deformation of the internal phase leads to asynchronous sliding of the color layer and the internal phase, resulting in longitudinal cracks; simultaneously, moisturizing properties are significantly reduced, with skin hydration increasing by less than 8% after 4 hours.

[0055] Comparative Example 5: In this comparative example, the total mass of the external phase wax composition was adjusted to 32 parts (12 parts beeswax, 10 parts carnauba wax, and 10 parts microcrystalline wax) to make the external phase dropping point close to 92°C. All other conditions were the same as in Example 1.

[0056] The outer phase becomes too hard and difficult to flow, resulting in insufficient fluidity during injection molding at 62°C. Uneven shell wall thickness and interface voids occur during the coating process. The final product has a dry feel, poor application smoothness, and the outer phase becomes brittle after 30 days of accelerated aging.

[0057] Comparative Example 6: In this comparative example, the mold temperature was raised to 55°C and the external phase was immediately injected without allowing it to stand for 30 seconds, ensuring that the internal phase remained in a fully fluid state and the surface hardness was less than 0.03 N / mm. 2 The remaining conditions are the same as in Example 1.

[0058] During the encapsulation process, the inner phase is squeezed and drifts due to the external fluid phase. After demolding, the inner core is noticeably eccentric, and in some samples, the inner phase is even squeezed out to the shell boundary. The core-shell structure cannot be stably formed, and the interface separation rate is as high as 40% or more during storage.

[0059] Performance Testing: I. Storage Modulus (G') Determination Method: The storage modulus was tested using a rheometer with a cone-plate measurement system. The outer phase, the cosmetic layer, and the inner protective layer of the sample were cut separately and subjected to small-amplitude oscillation scanning at a frequency of 1 Hz under 32°C. The storage modulus G' value of the sample was recorded using the rheometer.

[0060] II. Hardness Difference Measurement Method: The hardness test was conducted using an indentation hardness tester. The surface hardness of the top and bottom of the lipstick stick was measured at 32℃. The test was repeated three times at each location, and the average value was used to calculate the percentage hardness difference.

[0061] III. Structural stability test method: The samples were stored in an environment of 25℃ and 50% relative humidity for 3 months. During this period, the appearance of the samples was checked every 7 days, with a focus on observing for instability phenomena such as core displacement, shell cracks, interface delamination, color layer collapse, or top deformation. The proportion of structural defects is expressed as the percentage of samples with visible defects out of the total number after 3 months.

[0062] IV. Moisturizing Performance Testing Method: Moisturizing function testing was conducted using an artificial skin model. The sample was applied to the artificial skin surface with the same force and speed, and the moisture content changes at 0 h, 2 h, and 4 h after application were recorded using a skin stratum corneum moisture meter. The percentage increase in moisture content at 4 h was used as the moisturizing performance indicator; a higher increase in moisture content indicates a stronger water-retaining and water-binding capacity of the protective layer.

[0063] The test results are shown in Table 1 below: Table 1 ;

[0064] In Examples 1-4, the storage modulus of the external phase was consistently higher than that of the internal phase, with the ratio between the two controlled between approximately 2.3 and 3.6. The hardness difference was controlled within the range of 12% to 18%, and the proportion of structural defects was 0 for three months. This indicates that the formulation and process window set by this invention can stably form a core-shell structure with a reasonable gradient and maintain good integrity during long-term storage and use. In Comparative Examples 1-6, when the content of water and polyol in the external phase exceeded the limit, the polysaccharide ratio in the external phase was unbalanced, the polysaccharide structure in the internal phase was too hard or too dry, the wax content in the external phase was too high, or the internal phase did not reach the semi-cured state as required, abnormal storage modulus gradient, significantly increased hardness difference, and increased proportion of structural defects were observed, and the moisturizing performance also decreased to varying degrees.

[0065] The above description is merely a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A multiphase structure lipstick that integrates color and skin care, characterized in that, The lipstick comprises an outer phase makeup layer and an inner phase nourishing layer coaxially arranged along its axis. The outer phase makeup layer matrix, by weight, comprises: 10-35 parts hydroxypropyl starch phosphate; 2-10 parts pullulan; 15-35 parts vegetable oil; 10-25 parts wax composition; 5-20 parts pigment system, including inorganic and organic pigments; 0.1-2 parts sodium hyaluronate; 5-25 parts polyol moisturizer; and 5-20 parts water. The inner phase nourishing layer, by weight, comprises: 5-20 parts pullulan; 0.1-3 parts sodium hyaluronate; 5-20 parts polyol moisturizer; 1-8 parts polyol moisturizer; 1-5 parts water; 5-20 parts vegetable oil; and 1-8 parts modified starch thickener. Wherein: a) the mass ratio of hydroxypropyl starch phosphate to pullulan in the outer phase makeup layer is 2-6:1; b) The mass ratio of pullulan to hydroxypropyl starch phosphate in the inner protective layer is 1:0.2-1; c) The mass ratio of total polysaccharide derivatives in the outer cosmetic layer to total polysaccharide derivatives in the inner protective layer is 0.5-1.5:

1.

2. The multiphase structure color-protecting integrated lipstick according to claim 1, characterized in that, The hydroxypropyl starch phosphate has a degree of substitution of 0.05 to 0.25, a weight-average molecular weight of 20,000 to 300,000, and a molecular weight distribution index of 1.5 to 3.

0.

3. The multiphase structure color-protecting integrated lipstick according to claim 1, characterized in that, The pullulan has a weight-average molecular weight of 50,000 to 800,000, and the mass ratio of pullulan to sodium hyaluronate in the outer phase makeup layer is 3:1 to 15:1, while the mass ratio of pullulan to sodium hyaluronate in the inner phase protective layer is 2:1 to 10:

1.

4. The multiphase structure color-protecting integrated lipstick according to claim 1, characterized in that, The wax composition includes beeswax, carnauba wax, and microcrystalline wax, with beeswax accounting for 20-40 wt%, carnauba wax accounting for 15-35 wt%, and microcrystalline wax accounting for 30-60 wt%, and the dropping point of the outer phase cosmetic layer is 65-80℃.

5. The multiphase structure color-protecting integrated lipstick according to claim 1, characterized in that, The inorganic pigments in the outer phase makeup layer include mica, titanium dioxide, and iron oxide. The particle size D50 of the titanium dioxide is 80-200 nm, and the mass ratio of inorganic pigments to organic pigments is 2:1-10:

1.

6. The multiphase structure color-protecting integrated lipstick according to claim 1, characterized in that, The polyol moisturizer in the inner phase protective layer includes at least two of glycerin, propylene glycol and butylene glycol, with a total mass fraction of 10-30% by mass, and the total mass fraction of water and polyol in the inner phase protective layer is 20-45% by mass, while the total mass fraction of water and polyol in the outer phase makeup layer does not exceed 10% by mass.

7. A method for preparing a color-protecting integrated lipstick using the multiphase structure according to any one of claims 1 to 6, characterized in that, The process includes the following steps: (1) Preparation of the external phase makeup matrix: Hydroxypropyl starch phosphate, pullulan, vegetable oil, and wax composition are heated and melted at 80-90°C and stirred for 10-40 min to obtain a homogeneous melt; pigment system and sodium hyaluronate are added at 70-80°C and sheared and dispersed at 3000-6000 rpm for 2-6 min to obtain the external phase makeup melt; (2) Preparation of the internal phase nourishing matrix: Pullulan, sodium hyaluronate, polyol moisturizer, vegetable oil, and modified starch thickener are stirred and dissolved at 60-75°C for 10-30 min to obtain the internal phase nourishing melt; (3) Molding: The internal phase nourishing melt is injected into the center area of ​​the lipstick mold cavity at 35-45°C and left to stand for 10-60 s to form a semi-solidified inner core; then, it is wrapped in the mold and injected at 70-80°C. (4) Cooling and solidification: The system after injection molding is cooled for 10-30 minutes at 15-25°C for the first time, and then cooled for 20-60 minutes at 0-8°C for the second time. The multiphase structure of the integrated color care lipstick is obtained by demolding.

8. The method for preparing the multiphase structure color-protecting integrated lipstick according to claim 7, characterized in that, After the shearing and dispersion in step (1) is completed, the external phase makeup melt is kept at 70-75℃ for 3-10 minutes, and then cooled to 60-65℃ at a cooling rate of 1-3℃ / min before injection molding.

9. The method for preparing the multiphase structure color-protecting integrated lipstick according to claim 7, characterized in that, In step (3), the amount of the inner phase protective melt injected accounts for 10-40% of the total mass of the lipstick, and the surface hardness of the inner phase protective melt during the stage of forming a semi-solid inner core is 0.03-0.2 N / mm. 2 .

10. The method for preparing the multiphase structure color-protecting integrated lipstick according to claim 7, characterized in that, The storage modulus G' of the outer phase makeup layer at 32℃ and 1Hz is 1×10⁻⁶. 4 ~8×10 4 The storage modulus G' of the inner phase protective layer under the same conditions is 0.4 × 10 Pa. 4 ~4×10 4 Pa, and the difference in hardness between the two ends of the axial direction of the lipstick stick measured at 32℃ does not exceed 20%.