Production process and application of pearl powder

Abstract

The invention belongs to the field of personal care products, and particularly discloses a production process and application of pearl powder, and the process comprises the following steps: heating and melting glycol distearate, mixing with preheated nanocellulose gel, stirring at a low speed, dispersing at a high speed in an aqueous solution with a specific pH value, performing ultrasonic treatment, and finally performing spray drying to obtain a powdery pearling agent. The content of glycol distearate in the pearl powder is high (gt, 90%), and the water content is low (lt, 5%). The pearl powder prepared by the process can be directly used for a cold preparation process, is stably dispersed in personal care products such as shampoo, hair conditioners and the like with low viscosity (1t, 3000 cps), is not layered after being centrifuged, and shows an excellent pearl effect. The process is simplified, the energy consumption is low, and the obtained product is convenient to feed and good in stability.

Description

Technical Field

[0001] This invention belongs to the field of personal care products, specifically relating to a production process of pearlescent powder and its application. Background Technology

[0002] Ethylene glycol distearate (EGDS) is a common pearlescent agent (or opacifier), which is a soft, flaky wax at room temperature. Its pearlescent effect is achieved by dispersing EGDS in the formulation to form tiny, uniform, leaf-like crystals that reflect light to create a pearly luster. EGDS typically has a melting point between 65-70°C. Therefore, in traditional production processes, it needs to be heated to approximately 75°C to melt, and then the cooling rate and stirring speed are precisely controlled to allow it to crystallize and form a stable pearlescent effect. This thermal processing method is not only energy-intensive and time-consuming, but also sensitive to process parameters. Improper control of cooling or stirring can make it difficult to obtain a stable and delicate pearlescent effect.

[0003] To facilitate use in cold compounding processes, existing technologies typically pre-disperse EGDS in a surfactant system to create pearlescent pastes (i.e., EGDS dispersions). For example, commercially available Euprial® series pearlescent concentrates are paste-like products composed of EGDS and surfactants. However, these pearlescent pastes have several significant drawbacks: First, their viscosity is usually very high (often exceeding 12,000 cps at 25°C), causing inconvenience in feeding, conveying, and dispersing during production; second, the stability of this paste system is poor, with EGDS particles easily agglomerating and separating, resulting in a product shelf life of only about 12 months; furthermore, due to the high water content in the paste, preservatives such as benzoic acid and its salts, formic acid and its salts, are often required, which not only increases the complexity of the formulation but also affects the product's environmental friendliness.

[0004] Therefore, there is a need in this field for a green and environmentally friendly pearlescent product that can take into account the convenience of feeding materials, low energy consumption in preparation, high stability, and no need to add preservatives. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides a production process and application of pearlescent powder. By combining nanocellulose with a specific particle size range (diameter of 10-20 nm and length of 100-200 nm) with ethylene glycol distearate (EGDS) in different diester / monoester ratios, and then processing it into a powdered pearlescent agent through a specific process, this invention solves the technical problems of existing pearlescent paste products, such as high viscosity, inconvenient feeding, unstable system, need for preservatives, and high energy consumption and difficult control of traditional thermal processing.

[0006] More specifically, the present invention aims to propose a green and environmentally friendly pearlescent powder production process. This process involves mixing EGDS (with a diester to monoester mass ratio ranging from 95:5 to 40:60, especially with a ratio of 60:40 to 50:50) in a molten state with preheated nanocellulose gel, followed by dispersion, ultrasonication, and spray drying to obtain pearlescent powder with high EGDS content (>90%), low moisture content (<5%), and direct use in cold compounding processes. Surprisingly, the present invention has found that even when the diester content in EGDS is lower than the conventional standard requirement (e.g., 80%), the pearlescent powder obtained by combining this process with nanocellulose still exhibits superior dispersion stability and pearlescent effect compared to traditional high diester content pearlescent pastes in low-viscosity personal care products.

[0007] To achieve the objectives of this invention, the invention includes the following technical solutions:

[0008] A process for producing pearlescent powder includes the following steps:

[0009] (1) Heat ethylene glycol distearate to 75-80°C until it is completely melted;

[0010] (2) Prepare a nanocellulose gel with a mass percentage of 0.8-1.2% and heat it to 75-80℃;

[0011] (3) Pour the molten ethylene glycol distearate obtained in step (1) into the nanocellulose gel in step (2) and mix for 10-20 minutes under low speed stirring to form a uniform mixture;

[0012] (4) The mixture obtained in step (3) is put into an aqueous solution with a pH of 5.0-7.0, and first dispersed at high speed for 10-20 minutes to make the material initially uniformly distributed. Then, it is subjected to ultrasonic treatment for 20-40 minutes to further refine the particles and promote the formation of a stable structure.

[0013] (5) Spray dry the suspension after step (4), control the inlet temperature to be 150-160℃ and the outlet temperature to be 40-50℃, and finally obtain dry and loose ethylene glycol distearate powder.

[0014] As a further improvement of the present invention, the nanocellulose in step (2) is preferably of a diameter of 10-20 nm and a length of 100-200 nm. Nanocellulose within this size range can provide good spatial stability without significantly increasing the viscosity of the system. The nanocellulose is more preferably of plant origin to conform to the trend of green environmental protection.

[0015] As a further improvement of the present invention, in the ethylene glycol distearate described in step (1), the mass ratio of diester to monoester can be in a wide range of (95:5) to (40:60). Surprisingly, even when the diester content is lower than the conventional standard (e.g., 80%), the pearlescent powder prepared by the process of the present invention, especially when the mass ratio of diester to monoester is in the preferred range of (60:40) to (50:50), still exhibits exceptionally excellent pearlescent luster in end applications.

[0016] The present invention also provides a pearlescent powder produced by any of the above-described production processes. The pearlescent powder contains ethylene glycol distearate at a mass content greater than 90%, nanocellulose at a mass content less than 10%, and moisture at a mass content less than 5%. This product form fundamentally changes the traditional waxy or high-viscosity paste-like physical state of EGDS, giving it excellent flowability and ease of measurement.

[0017] This invention further provides specific applications of the aforementioned pearlescent powder in personal care products. For example, it includes a low-viscosity pearlescent shampoo prepared using a cold-blending process, comprising, by weight percentage, 12.0% surfactant, 1.5% pearlescent powder, 2.5% sodium chloride, 0.6% preservative, and the balance being water; the product has a viscosity of less than 3000 cps at 25°C. Similarly, this invention also provides a low-viscosity pearlescent conditioner prepared using a cold-blending process, comprising, by weight percentage, 5.5% emulsifier, 5.5% oil, 5.0% humectant, 1.5% pearlescent powder, 1.0% conditioning agent, 0.6% preservative, and the balance being water; the product viscosity is also less than 3000 cps. In these low-viscosity systems, the pearlescent powder can be stably dispersed, showing no stratification after centrifugation at 3000 rpm for 30 minutes.

[0018] Compared with the prior art, the present invention has the following outstanding advantages:

[0019] 1. Product form optimization: The traditional waxy or high-viscosity slurry EGDS is transformed into a powder with good flowability, which greatly facilitates storage, transportation and precise feeding in production.

[0020] 2. Energy-saving and simplified process: Pearl powder is obtained directly through spray drying, avoiding the complex cooling and crystallization control process in traditional thermal processing, thus reducing energy consumption and production complexity.

[0021] 3. Excellent application performance: The obtained pearlescent powder can be used directly in the cold preparation process. It can still maintain excellent dispersion stability in low viscosity systems (viscosity <3000 cps) and there is no stratification after high-speed centrifugation (3000rpm / 30min).

[0022] 4. Significant pearlescent effect: Even when using EGDS raw materials with relatively low diester content, the pearlescent powder produced by combining it with specific nanocellulose can still exhibit a pearlescent luster superior to traditional high-viscosity pearlescent paste in the final product.

[0023] 5. Formulation friendly: Pearl powder itself has low water content, so there is no need to add extra preservatives, and its high activity content (>90%) means that it can be added in small amounts (e.g., 1.5%), which helps to simplify the formulation of end products. Attached Figure Description

[0024] Figure 1 These are optical microscope images (400×) comparing the dispersion of pearlescent agents in low-viscosity shampoos of the embodiments and comparative examples of the present invention; Comparative Example A: Shampoo sample formulated using commercially available 20% EGDS pearlescent paste (Euperlan® PK 1200); Application Example 2A: Shampoo sample formulated using pearlescent powder of Example 2 of the present invention (EGDS diester / monoester mass ratio of 80:20); Application Example 7A: Shampoo sample formulated using pearlescent powder of Example 7 of the present invention (EGDS diester / monoester mass ratio of 60:40). Detailed Implementation

[0025] The technical solutions in the embodiments of the present invention will be clearly and completely described below. 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 skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] Examples 1-10

[0027] Table 1. Raw Material List

[0028] Prepare EGDS slurry according to Table 2. The preparation steps are as follows:

[0029] (1) Heat EGDS to 75-80℃ until melted, according to Table 1.

[0030] (2) Prepare 500g of 1% nanocellulose gel with purified water and heat it to 75-80℃.

[0031] (3) Pour the melted EGDS into the nanocellulose gel and stir at low speed for 10-20 minutes.

[0032] (4) Add the mixture obtained in step (3) to 500g of aqueous solution with pH 5.0-7.0, disperse at high speed for 10-20min, and sonicate for 30min.

[0033] (5) Spray drying, with the feed inlet temperature at 150-160℃ and the discharge outlet temperature at 40-50℃, and the moisture content controlled below 5%, to obtain EGDS powder.

[0034] Table 2. EGDS Powder Formulation (g)

[0035] EGDS(X:Y)* -- refers to the mass percentage of diesters and monoesters in EGDS, where X is the diester content and Y is the monoester content. For example, EGDS(90:10) means that the diester content is 90% and the monoester content is 10%.

[0036] EGDS content** -- refers to the percentage of EGDS by mass in the example.

[0037] Test Example 1

[0038] Stability tests of examples and comparative examples in low-viscosity products

[0039] To compare the effects of the present invention, comparative examples were set up. Comparative Example A (for shampoo) and Comparative Example B (for conditioner) used commercially available 20% EGDS pearlescent paste (BASF, Euperlan® PK 1200) as the pearlescent agent, and the recommended addition amount was calculated to ensure that the actual amount of EGDS added in the final formula was consistent with that in the embodiments of the present invention (both were 1.5%).

[0040] Low-viscosity shampoo and conditioner were prepared using the cold-mixing process according to Tables 3 and 4. The results were compared with the example and a commercially available 20% EGDS pearlescent paste (Euperlan® PK 1200), centrifuged at 3000 rpm for 30 min, and are shown in Tables 5 and 6.

[0041] Table 3. Low-viscosity shampoo formulation (cold compounding process, viscosity less than 3000 cps, 25℃)

[0042] Shampoo cold-mixing process: Mix SLES-30 and purified water evenly, add sodium chloride and dissolve completely, add pearlescent agent, and stir for 10 minutes. Finally, add preservative and mix evenly to obtain the shampoo.

[0043] Table 4. Pearl Conditioner Formula (cold mixing process, viscosity less than 3000cps, 25℃)

[0044] Pearlescent conditioner cold-mix process: Glycerin and water are mixed evenly to form the aqueous phase; jojoba oil, polyglycerol-10 oleate, and polyglycerol-6 caprylate are mixed evenly to form the oil phase; the oil phase is added to the aqueous phase and stirred for 10 minutes; the pearlescent agent is added and stirred for 10 minutes. Finally, PQ-39 and preservatives are added and mixed evenly to obtain the final product.

[0045] Table 5. Stability test results of low viscosity shampoos

[0046] Table 6. Stability test results of low viscosity conditioner

[0047] As can be seen from the results in Tables 5 and 6, the examples applied to low-viscosity products have better stability and can be stably suspended in low-viscosity formulations under high-speed centrifugation.

[0048] Test Example 2

[0049] Evaluation of pearlescent effect in low viscosity products in examples and comparative examples

[0050] Take 10g each of shampoo and conditioner, and apply them evenly to a 6cm x 6cm flat surface. Use a spatula to scrape back and forth three times, being careful not to create air bubbles. Use a BYK AG-4446 gloss meter to measure the gloss three times at a 60° angle, and take the average value. The results are shown in Table 7.

[0051] Table 7. Test results of pearlescent effect in application examples, in GB.

[0052] As shown in Table 7, with the same amount of EGDS added, the pearlescent effect in the product from the examples was better than that from the pearlescent paste. Examples 4, 5, 7, and 10 exhibited significantly stronger pearlescent effects. Furthermore, the pearlescent agent with 60% diester content showed a better pearlescent effect than the one with 80% diester content. The pearlescent effect was best in the application examples when the ratio of diester to monoester was between 60:40 and 50:50. However, when the ratio of diester to monoester decreased further to 50:50, the pearlescent effect weakened in the application examples.

[0053] It is speculated that this is because the -OH groups in the EGDS monoester and the -OH groups in the nanocellulose form hydrogen bonds, making the EGDS particles more stable and uniformly dispersed in the nanocellulose network. This allows the embodiment to be stable in a low-viscosity system and have a better pearlescent effect. When the EGDS monoester content is greater than 50%, although the particle distribution is more uniform, the content of the diester with the pearlescent effect is too low, so the pearlescent effect will be weakened.

[0054] Test Example 3

[0055] To verify the physical morphology of the pearlescent powder of the present invention and its dispersion stability in the application system at the microscopic level, an optical microscope was used to observe the low viscosity shampoos (i.e., application examples 2A and 7A) prepared from Comparative Example A (commercially available 20% EGDS pearlescent paste) and Example 2 of the present invention (corresponding to an EGDS diester / monoester ratio of 80:20) and Example 7 (corresponding to an EGDS diester / monoester ratio of 60:40), and to directly compare them with Comparative Example A.

[0056] 1. Observation method:

[0057] Instrument: An upright optical microscope equipped with a digital imaging system.

[0058] Sample preparation: Take a small amount of shampoo samples from Comparative Example A, Application Example 2A, and Application Example 7A respectively, drop them onto a clean glass slide, and gently cover with a coverslip to avoid generating air bubbles, thus preparing a temporary observation slide.

[0059] Observation conditions: The morphology, size, and distribution of pearlescent particles in the samples were observed under bright field at 400x magnification. At least five fields of view were randomly selected for observation and recording for each sample.

[0060] 2. Observation results are as follows Figure 1 As shown:

[0061] Comparative Example A (commercially available pearlescent paste): The EGDS particles exhibit uneven size, with numerous large plate-like crystals (mostly larger than 50 μm) and obvious aggregates. The particle distribution is uneven, with some areas showing signs of particle aggregation and sedimentation, indicating poor microscopic dispersion. This is consistent with the stratification observed in the macroscopic centrifugation test.

[0062] Application Example 2A (In this invention, diester 80%): EGDS particles exhibit a finer and more uniform flaky or needle-like crystal morphology, with the main particle size distribution between 10-30 μm. Particle dispersibility is good, agglomeration is significantly reduced, and the distribution in the field of view is relatively uniform.

[0063] Application Example 7A (of this invention, diester 60%): Optimal microdispersion was observed. The EGDS particles were small and uniform, with most particles ranging in size from 5 to 20 μm, and large aggregates were almost invisible. The particles exhibited good suspension and dispersion in water, clearly separated from each other, forming a uniform and stable dispersion system.

[0064] 3. Conclusion:

[0065] Microscopic observation clearly shows that, compared to commercially available pearlescent paste (Comparative Example A), the pearlescent powder prepared using the process of this invention, when applied to low-viscosity shampoo, exhibits smaller and more uniform EGDS particle size and significantly suppressed agglomeration. In particular, the particle dispersion is optimal when using EGDS raw materials with a diester content of 60% (Example 7). This microstructural explanation explains why the pearlescent powder of this invention achieves excellent suspension stability (no macroscopic centrifugal separation) in low-viscosity systems, and contributes to a stronger pearlescent visual effect due to the formation of more and more uniform light-reflecting surfaces. This result corroborates the gloss data from Test Example 2.

[0066] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the above embodiments do not limit the present invention in any way, and all technical solutions obtained by equivalent substitution or equivalent transformation fall within the protection scope of the present invention.

Claims

1. A production process for pearlescent powder, characterized in that, Includes the following steps: (1) Heat ethylene glycol distearate to 75-80°C until it melts; (2) Prepare a nanocellulose gel with a mass percentage of 0.8-1.2% and heat it to 75-80℃; (3) Pour the ethylene glycol distearate melted in step (1) into the nanocellulose gel in step (2), stir at low speed for 10-20 min to obtain a mixture; (4) The mixture obtained in step (3) is put into an aqueous solution with a pH of 5.0-7.0, first dispersed at high speed for 10-20 min, and then subjected to ultrasonic treatment for 20-40 min; (5) Spray dry the material after step (4), control the inlet temperature to be 150-160℃ and the outlet temperature to be 40-50℃, and obtain ethylene glycol distearate powder.

2. The production process according to claim 1, characterized in that, The nanocellulose in step (2) has a diameter of 10-20 nm and a length of 100-200 nm.

3. The production process according to claim 1 or 2, characterized in that, The nanocellulose mentioned in step (2) is plant-derived nanocellulose.

4. The production process according to claim 1, characterized in that, In step (1), the mass ratio of diester to monoester in the ethylene glycol distearate is (95:5)-(40:60).

5. The production process according to claim 4, characterized in that, The mass ratio of the diester to the monoester is (60:40) to (50:50).

6. A pearlescent powder, characterized in that, The pearlescent powder is produced by the production process described in any one of claims 1-5, wherein the mass content of ethylene glycol distearate is greater than 90%, the mass content of nanocellulose is less than 10%, and the mass content of moisture is less than 5%.

7. A low-viscosity pearlescent shampoo, characterized in that, Prepared using a cold mixing process, the product comprises the following components by mass percentage: 12.0% surfactant, 1.5% pearlescent powder as described in claim 6, 2.5% sodium chloride, 0.6% preservative, and the balance being water; the low-viscosity pearlescent shampoo has a viscosity of less than 3000 cps at 25°C.

8. A low-viscosity pearlescent hair conditioner, characterized in that, Prepared using a cold compounding process, the product comprises the following components by mass percentage: 5.5% emulsifier, 5.5% oil, 5.0% humectant, 1.5% pearlescent powder as described in claim 6, 1.0% conditioning agent, 0.6% preservative, and the balance being water; the low-viscosity pearlescent conditioner has a viscosity of less than 3000 cps at 25°C.

9. The low-viscosity pearlescent shampoo according to claim 7 or the low-viscosity pearlescent conditioner according to claim 8, characterized in that, The pearlescent powder is stable when dispersed in the shampoo or conditioner and does not separate into layers after centrifugation at 3000 rpm for 30 minutes.

10. The application of the pearlescent powder as described in claim 6 in the preparation of personal care products, characterized in that, The personal care product is prepared using a cold-mixing process, and the viscosity of the final product is less than 3000 cps.

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