A pearling agent and a pearling paste using the same, and a method for preparing the pearling paste

Abstract

The present application provides a kind of pearlescent agent and the pearlescent paste using it, the preparation method of pearlescent paste, the pearlescent agent includes ethylene glycol stearate, the preparation method of ethylene glycol stearate includes the following operations: esterification is carried out under the catalysis of enzyme to ethylene glycol and stearic acid, obtain the crude product containing ethylene glycol stearate, enzyme includes Rhizopus oryzae lipase and Candida antarctica lipase B.The preparation method used by the pearlescent agent is green and environmental protection, and the pearlescent agent shows good stability during storage, has good pearlescent effect.

Description

Technical Field

[0001] This invention relates to the field of additive materials technology, specifically to a pearlescent agent and a pearlescent paste using the same, and a method for preparing the pearlescent paste. Background Technology

[0002] Pearlescent agents are functional raw materials that impart a soft, pearl-like luster to products. Their mechanism of action primarily relies on ingredients such as ethylene glycol stearate in the formulation. These ingredients, after being heated and dissolved in a surfactant system, precipitate lens-like crystals during cooling. These crystals reflect light through the thin film, creating a unique pearlescent effect. Besides creating a visually sophisticated look, pearlescent agents often also act as thickeners and conditioners, improving the feel of the product on the skin. Therefore, they are widely used in liquid cleansing and skincare products such as shampoos, shower gels, and facial cleansers.

[0003] With the upgrading of consumption, people's pursuit of daily necessities has long surpassed the basic cleaning function, and they are paying more attention to the sensory experience and psychological satisfaction that products bring. This pearlescent effect with its own light luxury texture makes washing and care products look more gentle and nourishing, satisfying many consumers' yearning for a quality life.

[0004] However, despite such strong market demand, commercially available pearlescent agents still have some unresolved issues in practical applications. For example, traditional pearlescent agent products often require cumbersome heating operations during production, which not only consumes a lot of energy but also places higher demands on production equipment. In addition, some pearlescent agents have poor stability in formulations, easily leading to delamination or a decline in pearlescent effect, making it difficult to maintain a uniform appearance of the product over a long period.

[0005] More noteworthy is that, with green and environmentally friendly practices becoming the mainstream trend, developing pearlescent agents that conform to the concepts of naturalness and sustainability while maintaining excellent pearlescent effects has become a challenge that the industry urgently needs to overcome. Summary of the Invention

[0006] To address the problems and shortcomings of existing technologies, this invention provides a pearlescent agent, a pearlescent paste using the same, and a method for preparing the pearlescent paste. The preparation method employed for this pearlescent agent is green and environmentally friendly, and the pearlescent agent exhibits good stability during storage and possesses excellent pearlescent effects.

[0007] According to a first aspect of the present invention, a pearlescent agent is provided, comprising ethylene glycol stearate, wherein a method for preparing ethylene glycol stearate comprises the following operations: subjecting ethylene glycol and stearic acid to an esterification reaction under the catalysis of an enzyme to obtain a crude product containing ethylene glycol stearate, wherein the enzyme comprises Rhizopus oryzae lipase and Candida antarctica lipase B.

[0008] The pearlescent agent proposed in this scheme employs an enzymatic synthesis route, utilizing a specific enzyme combination to catalyze the efficient reaction between ethylene glycol and stearic acid. Compared to traditional high-temperature acid-catalyzed processes, this preparation method is not only milder and requires less sophisticated equipment, but also aligns better with the development of green chemistry. Furthermore, the enzymatic catalysis allows for more precise control of the reaction process, making it easier to achieve the desired pearlescent effect in the final product. It also effectively regulates the reaction mechanism between ethylene glycol and stearic acid, resulting in a pearlescent paste with excellent stability during storage, less prone to coarsening or stratification, and able to maintain its superior pearlescent effect even in diverse daily chemical products. In addition, this pearlescent agent has a refreshing and moisturizing feel on the skin, leaving minimal residue and enhancing the consumer experience.

[0009] Preferably, the Rhizopus miltiorrhiza lipase includes the lipase with the brand name Lipozyme RM IM.

[0010] Preferably, the Antarctic Candida lipase B includes the lipase with the brand name Novozym 435.

[0011] Preferably, the crude product containing ethylene glycol stearate has an acid value ≤ 5 mg KOH / g.

[0012] Preferably, the enzyme addition amount is 2-3 wt%. Limiting the enzyme addition amount to this range helps to achieve a good balance between reaction efficiency and cost control. At this dosage, the enzyme catalytic activity can be fully utilized, promoting a stable and complete esterification reaction between ethylene glycol and stearic acid, reducing the possibility of side reactions, and thus making the composition of the obtained ethylene glycol stearate more stable and controllable. This ratio also helps to ensure that the final pearlescent agent forms a uniform and stable crystal structure in the system, making it easier to achieve ideal pearlescent effect and storage stability. In addition, controlling the enzyme dosage within this range helps to reduce raw material costs, improve the economic applicability of the process, and facilitate its promotion and application in actual production.

[0013] Preferably, the molar ratio of ethylene glycol to stearic acid is 1:0.9~2.0, and / or the mass ratio of Rhizopus niger lipase to Candida antarcticis lipase B is 1:3~5.

[0014] Preferably, the mass ratio of Rhizopus niger lipase to Candida antarcticis lipase B is 1:3 to 3.8; and / or, the molar ratio of ethylene glycol to stearic acid is 1:0.9 to 1.1. Preferably, the mass ratio of Rhizopus niger lipase to Candida antarcticis lipase B is 1:4.0~5; and / or, the molar ratio of ethylene glycol to stearic acid is 1:1.6~2.0.

[0015] By further adjusting the enzyme blending ratio and combining it with the molar ratio of ethylene glycol to stearic acid, the esterification reaction can proceed in different directions, thereby obtaining ethylene glycol stearate products with varying ester compositions. This differentiated control method provides flexible options for optimizing the performance of pearlescent agents in different application scenarios.

[0016] When the mass ratio of Rhizopus oryzae lipase to Candida antarcticis lipase B is 1:3~3.8, and the molar ratio of ethylene glycol to stearic acid is 1:0.9~1.1, the reaction system is conducive to the formation and enrichment of monoesters. Because Rhizopus oryzae lipase has excellent affinity for long-chain saturated fatty acids, it can rapidly initiate esterification reactions to generate monoesters, allowing the monoesters to accumulate stably in the system. The resulting pearlescent product has a high monoester content. Pearlescent agents with high monoester content typically exhibit a finer, softer pearlescent texture, making them suitable for personal care products that require a smooth, skin-feeling finish.

[0017] When the mass ratio of Rhizopus miltiorrhiza lipase to Candida antarcticis lipase B is 1:4.0~5, and the molar ratio of ethylene glycol to stearic acid is 1:1.6~2.0, under these conditions, Candida antarcticis lipase B, due to its highly efficient catalytic properties, can strongly promote the conversion of monoesters to diesters. In addition, the appropriate excess of stearic acid substrate provides favorable conditions for diester formation, causing the reaction equilibrium to shift towards diester formation. The pearlescent agent products prepared in this way have advantages in applications such as shampoos and shower gels.

[0018] Therefore, the two preferred schemes mentioned above, by synergistically regulating the enzyme ratio and substrate molar ratio, achieve targeted control of the ratio of monoesters to diesters in the product, which can respectively meet the different market demands for the delicate texture or strong visual effect of pearlescent agents, and provide a flexible process basis for the diversified application of the product.

[0019] Preferably, the esterification reaction time is 2 to 4 hours; and / or, the esterification reaction temperature is 60 to 80°C.

[0020] By further controlling the reaction temperature and time within the aforementioned specific range, a stable and mild working environment is provided for the enzyme catalysis system. Within this temperature range, enzyme activity is well maintained, the reaction process is stable and controllable, which is conducive to the full contact between ethylene glycol and stearic acid and the completion of the esterification reaction, thereby improving conversion efficiency. Simultaneously, an appropriate reaction time ensures that the reaction reaches the expected degree, making the ratio of monoester to diester in the product more stable and reducing the formation of byproducts. The obtained ethylene glycol stearate has good purity and pearlescent properties, which helps the pearlescent agent form a uniform and stable crystal structure in subsequent applications, improving its pearlescent performance and storage stability in daily chemical products. The mild process conditions also help reduce energy consumption during production, aligning with the concept of green and environmentally friendly preparation.

[0021] According to another aspect of the present invention, a pearlescent paste is provided, comprising an aqueous solvent, an additive, and the aforementioned pearlescent agent.

[0022] After further formulation into a pearlescent paste, the aforementioned pearlescent agent exhibits even more outstanding comprehensive performance in practical applications. Since the core pearlescent agent component is prepared via an enzyme-catalyzed process, its ester composition and crystal morphology are already relatively stable. Even after dispersion in an aqueous solvent and with the addition of additives, it maintains good crystal structure integrity and is not prone to aggregation or sedimentation due to changes in the external environment. This allows the pearlescent paste to maintain a uniform appearance and stable pearlescent effect even under long-term storage or temperature fluctuations.

[0023] Thanks to the control of the ratio of monoesters to diesters through enzymatic catalysis, pearlescent pastes can exhibit a multi-layered pearlescent luster, ranging from delicate and soft to more pronounced, according to different formulation requirements, with a natural and uniform texture. Furthermore, due to fewer side reactions and higher purity during the preparation of the pearlescent agent, the formulated pearlescent paste feels refreshing and comfortable on the skin when used in daily chemical products, without easily causing stickiness or residue. In addition, this pearlescent paste exhibits good compatibility with various surfactant systems and additives, allowing it to be easily integrated into the production processes of various washing and care products such as shampoos, shower gels, and facial cleansers, providing a pleasant appearance while also supporting the mildness and stability of the formulation system.

[0024] Preferably, the pearlescent paste comprises, by weight percentage, 55% to 65% aqueous solvent, 20% to 30% pearlescent agent, 1% to 5% humectant, 1% to 5% dispersant, 1% to 5% thickener, and 9% to 20% surfactant.

[0025] By further limiting the mass percentage of each component in the pearlescent paste, the overall stability and user experience of the pearlescent paste can be further improved while fully leveraging the performance advantages of the pearlescent agent. Controlling the amount of pearlescent agent between 20% and 30% helps form a uniformly distributed crystal structure in the aqueous system, ensuring the pearlescent effect is neither too faint nor too high, which could affect the system's fluidity or cause agglomeration. The addition of a dispersant promotes full wetting and spreading of the pearlescent agent in the solvent, resulting in a more uniform paste state. The appropriate addition of a thickener provides suitable rheological properties, helping the pearlescent particles maintain suspension stability during long-term standing and reducing sedimentation or stratification. The introduction of humectants and surfactants makes the pearlescent paste more convenient to use as a semi-finished product in daily chemical products. Humectants improve the skin feel of the final product, providing a refreshing and moisturizing experience; surfactants ensure good compatibility between the pearlescent paste and the detergent matrix in subsequent formulations, facilitating direct integration into the production processes of shampoos, shower gels, and other products, reducing the need for additional formulation adjustments. The proportion of aqueous solvent maintains an appropriate solid content in the entire system, providing a stable dispersion medium for the pearlescent crystals and ensuring good flowability of the pearlescent paste, facilitating storage and pumping transfer. Overall, pearlescent pastes within this formulation range maintain stable pearlescent effects and uniform appearance while also ensuring skin comfort and flexibility in subsequent formulation adaptation, effectively meeting the requirements for raw material stability and ease of application in the development of daily chemical products.

[0026] Preferably, the moisturizer includes glycerin.

[0027] Preferably, the dispersant includes octylphenol polyoxyethylene ether (OP-10).

[0028] Optionally, the dispersant includes octylphenol polyoxyethylene ether of type OP-10.

[0029] Preferably, the thickener includes coconut oil fatty acid monoethanolamide (CMEA).

[0030] Preferably, the surfactant includes sodium fatty alcohol polyoxyethylene ether sulfate.

[0031] Optionally, the sodium fatty alcohol polyoxyethylene ether sulfate includes at least one of the surfactants MES-30 and AES.

[0032] Optionally, the pearlescent paste may contain 1% to 5% of a surfactant of type MES-30, calculated as a percentage by weight.

[0033] Optionally, the pearlescent paste includes 8% to 15% of a surfactant of type AES, calculated as a percentage by weight.

[0034] According to another aspect of the present invention, a method for preparing the above-mentioned pearlescent paste is provided, characterized in that it includes the following operations: mixing raw materials for preparing pearlescent paste, stirring and emulsifying at 75~80°C, cooling to 25~30°C, and aging.

[0035] Preferably, during the cooling process, when the temperature drops to 50~60°C, a salt solution is added to the reaction system, and the cooling continues.

[0036] Introducing a salt solution during the preparation of pearlescent paste provides a more flexible means of controlling the paste's viscosity. When the emulsion system cools down from 75-80°C to the 50-60°C range, the pearlescent agent crystals are in a critical stage of formation and growth. Adding a salt solution at this point can appropriately adjust the ionic strength in the dispersion medium, allowing for a gentle increase in system viscosity. This adjustment helps establish suitable rheological properties in the paste before the crystal network is fully formed, making it easier to maintain a uniform suspension during long-term storage.

[0037] Because the timing of the salt solution addition is closely coordinated with the cooling process, the growth of pearlescent crystals is not drastically disturbed, and they can still maintain a relatively regular crystalline morphology. This allows the final pearlescent paste to maintain a uniform and natural pearlescent effect even with an appropriate increase in viscosity, without the gloss being obscured by thickening. After viscosity adjustment, the pearlescent paste exhibits better operational adaptability during transportation, pumping, and subsequent mixing with daily chemical product base materials. It is less prone to sedimentation of the pearlescent agent due to excessive thinness, and its mixing efficiency is not affected by excessively high viscosity.

[0038] Preferably, the stirring speed is 600~1200 rpm and the cooling rate is 0.1~0.5℃ / min.

[0039] In the preparation of pearlescent paste, the coordinated control of stirring speed and cooling rate provides more operational flexibility for adjusting the nucleation and growth environment of pearlescent crystals. When the emulsion system begins to cool from 75~80℃, adjusting the appropriate stirring speed helps to uniformly disperse the pearlescent agent in the system, avoiding local over-concentration or agglomeration, thus laying a good foundation for subsequent crystal growth. Combined with an appropriate cooling rate, the crystal formation process can be made more stable, which is conducive to obtaining pearlescent grains with a more concentrated size distribution. This grain structure imparts a more uniform and natural luster to the paste when giving it a pearlescent effect. The process parameters can be adjusted according to actual needs to achieve flexible switching between a delicate, soft luster and a more obvious pearlescent texture.

[0040] Because the grain forming efficiency is optimized, the aging time required after the system is cooled to 25-30°C also has a certain degree of flexibility. When the stirring speed and cooling rate are properly matched, the crystal network can stabilize in a shorter time, which helps to shorten the production cycle and improve equipment turnover efficiency. Attached Figure Description

[0041] Figure 1 This is a schematic diagram of the pearlescent paste provided in this solution; Figure 2 This is a schematic diagram of the flow state of the pearlescent paste provided in this solution. Detailed Implementation

[0042] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions of this invention will be clearly and completely described below with reference to the embodiments and accompanying drawings. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this invention.

[0043] Example 1 1. Pearlizing agent The raw materials for preparing the pearlescent agent include: ethylene glycol, stearic acid, and enzymes. Stearic acid with an iodine value ≤0.2 is selected, and ethylene glycol is selected that exhibits good thermal stability and does not change color at 190℃. The acid value of the finished pearlescent agent is ≤5 mgKOH / g. The molar ratio of ethylene glycol to stearic acid is 1:1. The enzymes include Rhizopus oryzae lipase and Candida antarcticis lipase B in a mass ratio of 1:3.5. The enzyme addition amount is 2.5 wt%.

[0044] The preparation process of pearlescent agents includes the following steps: Stearic acid and ethylene glycol were mixed and heated in a 70°C water bath until completely melted. Then, an enzyme was added to catalyze an esterification reaction between the ethylene glycol and stearic acid. The mixture was stirred and reacted for 2.5 hours to obtain a crude pearlescent agent containing ethylene glycol stearate. After the reaction, the crude product was washed with distilled water at least three times to remove unreacted ethylene glycol, stearic acid, and lipase, and then dried.

[0045] 2. Pearlescent paste: The pearlescent paste comprises, by weight percentage, 58% water, 25% of the above-mentioned pearlescent agent, 1% glycerol, 2% octylphenol polyoxyethylene ether of type OP-10, 1% coconut oil fatty acid monoethanolamide (CMEA), 3% surfactant of type MES-30, and 10% surfactant of type AES.

[0046] The preparation process of pearlescent paste includes the following steps: First, heat the water to 80±5℃, then mix the water with glycerin, OP-10, pearlescent agent and CMEA. After complete mixing, continue to add MES-30 and AES to the system and stir at 77±2℃ for 1 hour to fully emulsify the system. Then, cool the system to 60℃ at a cooling rate of 0.5℃ / min and add the salt solution to the reaction system. Then, cool the system to 25℃ at a cooling rate of 0.3℃ / min and age it for 24 hours.

[0047] The resulting pearlescent paste is like Figure 1 , Figure 2 As shown.

[0048] Example 2 Experimental group 1A This experimental group prepared a pearlescent paste according to the preparation method provided in Example 1. The difference between this experimental group and Example 1 is that in the preparation of the pearlescent paste, the mass ratio of Rhizopus niger lipase to Candida antarctica lipase B was 1:2.5, and the amount of stearic acid added was adjusted so that the molar ratio of ethylene glycol to stearic acid was 1:0.9. The remaining raw material ratios and preparation methods were strictly consistent with those in Example 1, especially the total amount of enzymes added.

[0049] Experimental group 2A This experimental group prepared a pearlescent paste according to the preparation method provided in Example 1. The difference between this experimental group and Example 1 is that the mass ratio of Rhizopus oryzae lipase to Candida antarcticis lipase B was 1:3 during the preparation of the pearlescent paste. The remaining raw material ratios and preparation methods were strictly consistent with those in Example 1, especially the total amount of enzymes added.

[0050] Experimental group 3A This experimental group prepared a pearlescent paste according to the preparation method provided in Example 1. The difference between this experimental group and Example 1 is that in the preparation of the pearlescent paste, the mass ratio of Rhizopus niger lipase to Candida antarctica lipase B was 1:3.8, and the amount of stearic acid added was adjusted so that the molar ratio of ethylene glycol to stearic acid was 1:1.1. The remaining raw material ratios and preparation methods were strictly consistent with those in Example 1, especially the total amount of enzymes added.

[0051] Experimental group 4A This experimental group prepared a pearlescent paste according to the preparation method provided in Example 1. The difference between this experimental group and Example 1 is that in the preparation of the pearlescent paste, the mass ratio of Rhizopus niger lipase to Candida antarctica lipase B was 1:4, and the amount of stearic acid added was adjusted so that the molar ratio of ethylene glycol to stearic acid was 1:1.5. The remaining raw material ratios and preparation methods were strictly consistent with those in Example 1, especially the total amount of enzymes added.

[0052] Experimental group 5A This experimental group prepared a pearlescent paste according to the preparation method provided in Example 1. The difference between this experimental group and Example 1 is that in the preparation of the pearlescent paste, the mass ratio of Rhizopus oryzae lipase to Candida antarctica lipase B was 1:4.5, and the amount of stearic acid added was adjusted so that the molar ratio of ethylene glycol to stearic acid was 1:1.6. The remaining raw material ratios and preparation methods were strictly consistent with those of Example 1, especially the total amount of enzymes added.

[0053] Experimental group 6A This experimental group prepared a pearlescent paste according to the preparation method provided in Example 1. The difference between this experimental group and Example 1 is that in the preparation of the pearlescent paste, the mass ratio of Rhizopus niger lipase to Candida antarctica lipase B was 1:5, and the amount of stearic acid added was adjusted so that the molar ratio of ethylene glycol to stearic acid was 1:2. The remaining raw material ratios and preparation methods were strictly consistent with those in Example 1, especially the total amount of enzymes added.

[0054] Experimental group 7A This experimental group prepared a pearlescent paste according to the preparation method provided in Example 1. The difference between this experimental group and Example 1 is that in the preparation of the pearlescent paste, the mass ratio of Rhizopus niger lipase to Candida antarctica lipase B was 1:5.5, and the amount of stearic acid added was adjusted so that the molar ratio of ethylene glycol to stearic acid was 1:2.2. The remaining raw material ratios and preparation methods were strictly consistent with those in Example 1, especially the total amount of enzymes added.

[0055] Comparative Example 1 This comparative example uses the preparation method provided in Example 1 to prepare a pearlescent paste. The difference between this comparative example and Example 1 is that, in the preparation of the pearlescent paste, an equal mass of Rhizopus niger lipase is used instead of Candida antarcticis lipase B in Example 1. The remaining raw material ratios and preparation methods are strictly consistent with those in Example 1, especially the total amount of enzyme added.

[0056] Comparative Example 2 This comparative example uses the preparation method provided in Example 1 to prepare a pearlescent paste. The difference between this comparative example and Example 1 is that, in the preparation of the pearlescent paste, an equal mass of *Candida antarcticis* lipase B is used instead of *Rhizopus oryzae* lipase in Example 1. The remaining raw material ratios and preparation methods are strictly consistent with those in Example 1, especially the total amount of enzyme added.

[0057] Comparative Example 3 This comparative example uses the preparation method provided in Example 1 to prepare a pearlescent paste. The difference between this comparative example and Example 1 is that the pearlescent agent is catalyzed by acid. The remaining raw material ratios and preparation methods are strictly consistent with those in Example 1, especially the total amount of enzyme added.

[0058] The preparation process of pearlescent agents includes the following steps: Stearic acid and ethylene glycol were mixed and heated in a 70°C water bath until completely melted. Then, p-toluenesulfonic acid was added as a catalyst, and the reaction system was heated to 120°C to allow the ethylene glycol and stearic acid to undergo an esterification reaction under acid catalysis. The mixture was stirred and reacted for 4 hours to obtain a crude pearlescent agent containing ethylene glycol stearate. After the reaction, the crude product was washed with distilled water at least three times to remove unreacted ethylene glycol, stearic acid, and lipase, and then dried.

[0059] Test Example 1 Test subjects: pearlescent pastes provided in Examples 1-2 and Comparative Examples 1-3.

[0060] Test items and test methods: (1) Pearlescent effect: Dilute the pearlescent paste to a surfactant aqueous solution of similar viscosity at a ratio of 10wt%, and record the pearlescent effect by visual inspection against a black background. When the system has a uniform flow of light under illumination and no graininess, it is considered excellent and recorded as level 4; when the pearlescent effect is obvious and evenly distributed, and there are no large, visible sparkling points, it is considered good and recorded as level 3; when the system has an obvious pearlescent effect, but under strong light, the side view shows weak, uneven sparkling points or a slight hazy feeling, it is considered passable and recorded as level 2; when the system has almost no pearlescent effect, or there are visible flaky crystals, flocculent precipitates, and large areas of uneven bright spots, it is considered unqualified and recorded as level 1.

[0061] (2) Storage stability: Refer to the test methods in GB / T 29665-2013 Skin Care Emulsions to record the storage stability of the pearlescent paste. When the system has no stratification, oil-water separation or flocculent matter, and the pearlescent effect is not visibly reduced compared with the untreated sample, it is considered excellent and recorded as level 4. When the system has no stratification, there may be very slight oil rings or water precipitation (which disappears after light shaking) or a very small amount of dispersible sediment, no flocculent matter, and the pearlescent effect is only slightly weakened, it is considered good and recorded as level 3. When the system shows slight reversible stratification or visible oil-water precipitation (which basically disappears after light shaking), or a small amount of fine flocculent matter, and the pearlescent effect is significantly reduced to a moderate degree, it is considered acceptable and recorded as level 2. When the system shows severe or irreversible stratification, obvious oil-water separation (which cannot be homogenized after light shaking), a large amount of flocculent matter / clumps, or the pearlescent effect is severely reduced or even disappears, meeting any one of these conditions is considered unacceptable and recorded as level 1.

[0062] Heat resistance and storage stability: Place the pearlescent agent in a constant temperature incubator at (40±1)℃ for 24 hours. After removal, allow it to stand at room temperature for 30 minutes. Check for any signs of stratification, oil-water separation, flocculation, or significant reduction in pearlescent effect.

[0063] Cold-resistant storage stability: Place the pearlescent agent in a constant temperature incubator at (-8±2)℃ for 24 hours. After removal, allow it to stand at room temperature for 30 minutes. Check for any signs of stratification, oil-water separation, flocculation, or significant reduction in pearlescent effect.

[0064] Stability of the pearlescent agent under thermal cycling: Place the pearlescent agent in a constant temperature incubator at (40±1)℃ for 12 hours, then allow it to rest at room temperature for 30 minutes; then place the pearlescent agent in a constant temperature incubator at (-8±2)℃ for 12 hours, then allow it to rest at room temperature for 30 minutes. This constitutes one cycle. After two cycles, remove the agent and allow it to rest at room temperature for 30 minutes. Check for any signs of stratification, oil-water separation, flocculent matter, or significant reduction in pearlescent effect.

[0065] Test results: The variables for this test case are shown in Table 1, and the test results for this test case are shown in Table 2.

[0066] Table 1. Variable parameters of the test subjects in this test case.

[0067] Table 2. Test results of the participants in this test case.

[0068] Results analysis: According to the test results of Examples 1, Experimental Groups 1A-7A, and Comparative Examples 1-3 in Table 2, it can be seen that when the molar ratio of ethylene glycol to stearic acid is controlled within the range of 1:0.9-2.0, and the mass ratio of Rhizopus oryzae lipase to Candida antarcticis lipase B is controlled within the range of 1:3-5, the prepared pearlescent agent can achieve relatively ideal performance in terms of pearlescent effect and storage stability. Within this preferred range, the pearlescent pastes provided in Examples 1 and Experimental Groups 2A-6A all achieve excellent or good pearlescent effects, and the heat resistance, cold resistance, and thermal cycling stability of the pearlescent pastes are generally good or above, showing that this range has good process adaptability.

[0069] Within the aforementioned preferred range, by further adjusting the enzyme compound ratio and substrate molar ratio, the esterification reaction can proceed in different directions, thereby obtaining ethylene glycol stearate products with different ester compositions, providing a flexible selection space for optimizing the performance of pearlescent agents in different application scenarios.

[0070] For example, in the preparation of pearlescent agents in Examples 1, Experimental Group 2A, and Experimental Group 3A, the mass ratio of the two lipases was 1:3~3.8, and the molar ratio of ethylene glycol to stearic acid was 1:0.9~1.1. This reaction system is conducive to the formation and enrichment of monoesters. Rhizopus niger lipase has excellent affinity for long-chain saturated fatty acids, enabling it to rapidly initiate esterification reactions to generate monoesters, which then accumulate stably in the system, resulting in a high monoester content in the final pearlescent agent. Pearlescent agents with high monoester content typically exhibit a more delicate and softer pearlescent texture, making them suitable for personal care products that require a high level of skin feel. In the preparation of pearlescent agents in experimental groups 5A and 6A, the mass ratio of the two lipases was 1:4.0~5, and the molar ratio of ethylene glycol to stearic acid was 1:1.6~2.0. Due to its highly efficient catalytic properties, Antarctic Candida lipase B can effectively promote the conversion of monoester to diester. In addition, the appropriate excess of stearic acid substrate creates favorable conditions for diester formation, causing the reaction equilibrium to shift towards diester formation. The pearlescent agent prepared in this way has advantages in applications in products such as shampoo and shower gel.

[0071] Example 3 Experimental group 1B This experimental group prepared a pearlescent paste according to the preparation method provided in Example 1. The difference between this experimental group and Example 1 is that the amount of enzyme added during the preparation of the pearlescent paste is 1.5 wt%. The other raw material ratios and preparation methods are strictly consistent with those in Example 1.

[0072] Experimental group 2B This experimental group prepared a pearlescent paste according to the preparation method provided in Example 1. The difference between this experimental group and Example 1 is that the amount of enzyme added during the preparation of the pearlescent paste is 2 wt%. The other raw material ratios and preparation methods are strictly consistent with those in Example 1.

[0073] Experimental group 3B This experimental group prepared a pearlescent paste according to the preparation method provided in Example 1. The difference between this experimental group and Example 1 is that the amount of enzyme added during the preparation of the pearlescent paste is 3 wt%. The other raw material ratios and preparation methods are strictly consistent with those in Example 1.

[0074] Experimental group 4B This experimental group prepared a pearlescent paste according to the preparation method provided in Example 1. The difference between this experimental group and Example 1 is that the amount of enzyme added during the preparation of the pearlescent paste is 4 wt%. The other raw material ratios and preparation methods are strictly consistent with those in Example 1.

[0075] Comparative Example 4 This comparative example uses the preparation method provided in Example 1 to prepare a pearlescent paste. The difference between this comparative example and Example 1 is that, in the preparation of the pearlescent paste, an equal mass of Rhizopus niger lipase is used instead of Candida antarctica lipase B in Example 1, and the amount of enzyme added is adjusted to 1.5 wt%. The remaining raw material ratios and preparation methods are strictly consistent with those in Example 1.

[0076] Comparative Example 5 This comparative example uses the preparation method provided in Example 1 to prepare a pearlescent paste. The difference between this comparative example and Example 1 is that, in the preparation of the pearlescent paste, an equal mass of Rhizopus niger lipase is used instead of Candida antarctica lipase B in Example 1, and the amount of enzyme added is 2 wt%. The remaining raw material ratios and preparation methods are strictly consistent with those in Example 1.

[0077] Comparative Example 6 This comparative example uses the preparation method provided in Example 1 to prepare a pearlescent paste. The difference between this comparative example and Example 1 is that, in the preparation of the pearlescent paste, an equal mass of Rhizopus niger lipase is used instead of Candida antarcticis lipase B in Example 1, and the amount of enzyme added is 3 wt%. The remaining raw material ratios and preparation methods are strictly consistent with those in Example 1.

[0078] Comparative Example 7 This comparative example uses the preparation method provided in Example 1 to prepare a pearlescent paste. The difference between this comparative example and Example 1 is that, in the preparation of the pearlescent paste, an equal mass of Rhizopus niger lipase is used instead of Candida antarcticis lipase B in Example 1, and the amount of enzyme added is 4 wt%. The remaining raw material ratios and preparation methods are strictly consistent with those in Example 1.

[0079] Test Example 2 Test subjects: pearlescent pastes provided in Examples 1, 3, and Comparative Examples 4 to 7.

[0080] Test items and test methods: (1) Pearlescent effect: Dilute the pearlescent paste to a surfactant aqueous solution of similar viscosity at a ratio of 10wt%, and record the pearlescent effect by visual inspection against a black background. When the system has a uniform flow of light under illumination and no graininess, it is considered excellent and recorded as level 4; when the pearlescent effect is obvious and evenly distributed, and there are no large, visible sparkling points, it is considered good and recorded as level 3; when the system has an obvious pearlescent effect, but under strong light, the side view shows weak, uneven sparkling points or a slight hazy feeling, it is considered passable and recorded as level 2; when the system has almost no pearlescent effect, or there are visible flaky crystals, flocculent precipitates, and large areas of uneven bright spots, it is considered unqualified and recorded as level 1.

[0081] (2) Storage stability: Refer to the test methods in GB / T 29665-2013 Skin Care Emulsions to record the storage stability of the pearlescent paste. When the system has no stratification, oil-water separation or flocculent matter, and the pearlescent effect is not visibly reduced compared with the untreated sample, it is considered excellent and recorded as level 4. When the system has no stratification, there may be very slight oil rings or water precipitation (which disappears after light shaking) or a very small amount of dispersible sediment, no flocculent matter, and the pearlescent effect is only slightly weakened, it is considered good and recorded as level 3. When the system shows slight reversible stratification or visible oil-water precipitation (which basically disappears after light shaking), or a small amount of fine flocculent matter, and the pearlescent effect is significantly reduced to a moderate degree, it is considered acceptable and recorded as level 2. When the system shows severe or irreversible stratification, obvious oil-water separation (which cannot be homogenized after light shaking), a large amount of flocculent matter / clumps, or the pearlescent effect is severely reduced or even disappears, meeting any one of these conditions is considered unacceptable and recorded as level 1.

[0082] Heat resistance and storage stability: Place the pearlescent agent in a constant temperature incubator at (40±1)℃ for 24 hours. After removal, allow it to stand at room temperature for 30 minutes. Check for any signs of stratification, oil-water separation, flocculation, or significant reduction in pearlescent effect.

[0083] Cold-resistant storage stability: Place the pearlescent agent in a constant temperature incubator at (-8±2)℃ for 24 hours. After removal, allow it to stand at room temperature for 30 minutes. Check for any signs of stratification, oil-water separation, flocculation, or significant reduction in pearlescent effect.

[0084] Stability of the pearlescent agent under thermal cycling: Place the pearlescent agent in a constant temperature incubator at (40±1)℃ for 12 hours, then allow it to rest at room temperature for 30 minutes; then place the pearlescent agent in a constant temperature incubator at (-8±2)℃ for 12 hours, then allow it to rest at room temperature for 30 minutes. This constitutes one cycle. After two cycles, remove the agent and allow it to rest at room temperature for 30 minutes. Check for any signs of stratification, oil-water separation, flocculent matter, or significant reduction in pearlescent effect.

[0085] Test results: The variables for this test case are shown in Table 3, and the test results for this test case are shown in Table 4.

[0086] Table 3. Variable parameters of the test subjects in this test case.

[0087] Table 4. Test results of the subjects in this test case.

[0088] Results analysis: Based on the test results in Tables 3 and 4, it can be seen that, according to the test results of Example 1 and Experimental Groups 1B-4B, when using a mixture of Rhizopus niger lipase and Candida antarcticis lipase B, with their mass ratio controlled within the range of 1:3-5, the total amount of enzymes added has a significant regulatory effect on the pearlescent effect and storage stability. When the total amount of enzymes added is 2wt%-3wt%, the pearlescent effect reaches an excellent level, and the results of various storage stability tests are generally good or above. This indicates that, under this compound system, controlling the amount of enzymes added at 2wt%-3wt% helps to fully utilize the synergistic catalytic efficiency of the two enzymes, making the esterification reaction more stable and controllable, thereby obtaining better overall performance.

[0089] In contrast, based on the test results of Comparative Examples 1 and 4-7, in the comparative examples using only a single type of lipase, even with the same adjustment of the enzyme addition amount from 1.5 wt% to 4 wt%, the improvement in pearlescent effect and storage stability was relatively limited. Specifically, the pearlescent effect of the pearlescent pastes provided by Comparative Examples 1 and 4-7 mostly reached only a passable or good level, and in cold resistance or thermal cycling stability tests, they repeatedly only achieved a passable level, failing to achieve stable and excellent performance over a wider range of addition amounts as the two-enzyme compound system. This indicates that the single-enzyme catalytic system, limited by the singularity of its catalytic characteristics, cannot effectively guide the reaction of ethylene glycol and stearic acid towards the ideal ester composition by simply adjusting the enzyme dosage, thus having a relatively limited effect on improving the final pearlescent agent performance. When Rhizopus niger lipase and Candida antarcticis lipase B are combined in a ratio of 1:3 to 5, the fine adjustment of the enzyme addition amount has more significant practical implications. It can effectively optimize the reaction process and product composition through synergistic catalysis, thereby enabling the pearlescent agent to achieve more ideal performance in terms of pearlescent effect and storage stability.

[0090] 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 pearlescent agent, characterized in that, The product includes ethylene glycol stearate, and the preparation method of the ethylene glycol stearate includes the following operations: ethylene glycol and stearic acid undergo an esterification reaction under the catalysis of an enzyme to obtain a crude product containing the ethylene glycol stearate, wherein the enzyme includes Rhizopus niger lipase and Candida antarcticis lipase B.

2. The pearlescent agent as described in claim 1, characterized in that, The amount of enzyme added is 2-3 wt%.

3. The pearlescent agent as described in claim 1, characterized in that, The molar ratio of ethylene glycol to stearic acid is 1:0.9~2.0, and / or the mass ratio of Rhizopus miltiorrhiza lipase to Candida antarcticis lipase B is 1:3~5.

4. The pearlescent agent as described in claim 1, characterized in that, Includes either the following feature (1) or feature (2): (1) The mass ratio of the Rhizopus miltiorrhiza lipase to the Candida antarcticis lipase B is 1:3~3.8; and / or, the molar ratio of the ethylene glycol to the stearic acid is 1:0.9~1.1; (2) The mass ratio of the Rhizopus miltiorrhiza lipase to the Candida antarcticis lipase B is 1:4.0~5; and / or the molar ratio of the ethylene glycol to the stearic acid is 1:1.6~2.

0.

5. The pearlescent agent as described in claim 1, characterized in that, The esterification reaction takes 2 to 4 hours; and / or the esterification reaction takes 60 to 80°C.

6. A pearlescent paste, characterized in that, Includes aqueous solvents, additives, and pearlescent agents as described in any one of claims 1 to 5.

7. The pearlescent paste as described in claim 6, characterized in that, The pearlescent paste comprises, by weight percentage, 55% to 65% aqueous solvent, 20% to 30% pearlescent agent, 1% to 5% humectant, 1% to 5% dispersant, 1% to 5% thickener, and 9% to 20% surfactant.

8. A method for preparing the pearlescent paste according to any one of claims 6-7, characterized in that, The process includes the following steps: mixing the raw materials used to prepare the pearlescent paste, stirring and emulsifying at 75-80°C, cooling to 25-30°C, and aging.

9. The method for preparing pearlescent paste as described in claim 8, characterized in that, During the cooling process, when the temperature drops to 50~60℃, a salt solution is added to the reaction system, and the temperature continues to drop.

10. The method for preparing pearlescent paste according to claim 8, characterized in that, The stirring speed is 600~1200 rpm, and the cooling speed is 0.1~0.5℃ / min.

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