Silicone oil-free sulfate-free weak cation system shampoo and preparation method thereof

Abstract

The invention relates to the technical field of daily chemical cleaning and nursing, and discloses a silicone oil-free sulfate-free weak cation system shampoo and a preparation method thereof.According to the formula of the shampoo, lauramide propyl betaine, sodium lauroyl sarcosinate and other multi-element surfactants are compounded; a weak cation conditioning system cooperatively constructed by matching phytosterols, cationic cellulose and cationic guar gum does not contain silicone oil and sulfate components; gradient temperature change and segmented pH regulation and control processes are adopted for preparation. The product has a pH value of 5.0-6.0, conforms to the scalp environment, does not have harmful residues such as D4 and dioxane, has acute eye irritation of slight irritation, has a cleaning rate of 91-97%, is fine and smooth in foam and easy to wash, can significantly improve the smoothness of wet and dry hair and reduce frizz, has stable performance after being placed at 60 DEG C for 4 months, has mild property, cleaning power, repairing effect and use experience, and is suitable for various hair qualities.

Description

Technical Field

[0001] This invention relates to the field of daily chemical cleaning and care technology, and in particular to a silicone-free, sulfate-free, weakly cationic shampoo and its preparation method. Background Technology

[0002] In the current hair care product market, balancing cleansing power, repair effects, and gentleness is a core technological challenge. To meet consumer demand for safe and gentle products, silicone-free and sulfate-free shampoos are gradually becoming a hot research topic in the industry. Currently, these products often rely on a single type of surfactant to ensure cleansing power, depend on a small amount of conditioning ingredients to compensate for the lack of smoothness resulting from being silicone-free, and some products also add traditional thickeners to adjust the texture, aiming to approximate the user experience of traditional shampoos.

[0003] However, existing silicone-free and sulfate-free shampoos still have significant limitations. Firstly, it's difficult to balance cleansing power and gentleness. Some products reduce surfactant content in pursuit of gentleness, resulting in insufficient cleansing power and an inability to thoroughly remove scalp oil and dirt; others, due to improper surfactant formulation, still cause scalp irritation and tightness after washing. Secondly, conditioning effects are poor. Most products lack a scientifically designed conditioning system, either lacking smoothness and causing significant resistance when combing wet or dry hair, or relying on excessive cationic ingredients, leading to flat, limp hair and a lack of cleanliness. Thirdly, system stability is poor. Active ingredients in some products are difficult to disperse evenly, easily causing problems such as layering and discoloration, and the lather is often not rich or fine enough, affecting the user experience. Fourthly, repair efficacy is limited. Existing products often simply add moisturizing or repairing ingredients, but due to the lack of effective solubilizing and penetration carriers, the ingredients cannot fully exert their effects, resulting in poor repair effects on damaged hair and failing to meet consumers' needs for multi-functional care.

[0004] Therefore, developing a silicone-free and sulfate-free shampoo that can achieve a unified balance of cleansing power, gentleness, smoothness, and repair effects, and has a stable system, has become an urgent problem for the industry. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the existing technology by proposing a silicone-free, sulfate-free, weakly cationic shampoo and its preparation method.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A silicone-free, sulfate-free, weakly cationic shampoo, by weight percentage, comprises the following components: lauramidopropyl betaine 20-38%, sodium lauroyl sarcosinate 10-28%, disodium lauroamphodiacetate 2-4%, phytosterols 0.2-0.6%, cationic cellulose 0.1-0.2%, cationic guar gum 0.05-0.1%, preservatives 0.3-0.6%, fragrance 0.1-0.5%, trimethylglycine 0-0.8%, glutamic acid 0-1.0%, alkyl glycosides 0-2%, lactic acid 0-0.5%, and deionized water to 100%. The shampoo is free of silicone oils and sulfate surfactants. The silicone oils include, but are not limited to, polydimethylsiloxane and amino silicone oils, while the sulfate surfactants include, but are not limited to, sodium lauryl sulfate and sodium laureth sulfate. The weakly cationic conditioning function of the shampoo is synergistically achieved by cationic cellulose and cationic guar gum.

[0008] Preferably, the preservative is one or more of phenoxyethanol and ethylhexylglycerin.

[0009] Preferably, the phytosterols are phytosterol fatty acid esters with a number average molecular weight of 700-900 Da.

[0010] Preferably, a method for preparing a silicone-free, sulfate-free, weakly cationic shampoo includes the following steps:

[0011] Step 1: Add the prescribed amount of deionized water to the mixing pot and heat it to 45-50℃; mix cationic cellulose and cationic guar gum according to the formula ratio, slowly sprinkle them into the water, and stir at 300-400r / min for 30-40min to form a homogeneous and transparent liquid.

[0012] Step 2: Keep the temperature of the homogeneous and transparent liquid system at 40-45℃, add sodium lauroyl sarcosinate, stir at 250-300r / min for 20-25min, adjust the pH of the system to 7.0-8.0, and continue stirring for 10-20min to form an alkaline transparent body;

[0013] Step 3: Cool the alkaline transparent body to 35-40℃, add phytosterols, and stir at 200-250r / min for 15-20min until completely soluble. Then add preservatives and continue stirring for 10-20min to form a soluble, transparent, and homogeneous body.

[0014] Step 4: Keep the temperature of the solubilization and transparent homogenization system at 35-40℃, selectively add trimethylglycine and glutamic acid, stir at 200-250 r / min until completely dissolved, selectively add lactic acid to control the pH of the system, and continue stirring for 10-20 min to form an acidic transparent body;

[0015] Step 5: Keep the temperature of the acidic transparent body at 35-40℃, slowly add lauramidopropyl betaine and disodium lauroamphodiacetate, and then selectively add alkyl glycosides. Stir at 250-300 r / min for 25-30 min to form a uniform, transparent, viscous liquid.

[0016] Step 6: Keep the temperature of the viscous liquid at 25-30℃, add the flavoring, stir at 100-200r / min for 10-15min, take a sample for testing and after it meets the standard, discharge the material to obtain the finished product.

[0017] Preferably, in the fourth step, the pH of the control system is 5.0-6.0.

[0018] Preferably, in step six, the standard is that the total surfactant content (active ingredient) is 12-20%, the pH value is 5.0-6.0, and the viscosity is 3000-5000 mPa·s.

[0019] Preferably, the mechanism of action of each component in this formula and the principle of its preparation steps are explained as follows:

[0020] I. Mechanism of Action of Each Component

[0021] 1. Sodium lauroyl sarcosinate: As an amino acid-based anionic surfactant, the amide bond in its molecular structure increases the hydrophilicity of the molecule, enabling it to maintain good foaming properties even in hard water. Under alkaline conditions (pH 7-8), it can form stable micelles, serving as a key carrier for solubilizing fat-soluble components (such as phytosterols) in this system.

[0022] 2. Lauroamide propyl betaine: As an amphoteric surfactant, it has good compatibility. In a slightly acidic environment (pH 5-6), its molecules exhibit cationicity, enabling it to form complexes with anionic surfactants, increasing the viscosity of the system and enhancing the softness of hair during washing.

[0023] 3. Disodium lauroamphodiacetate: A mild amphoteric surfactant, primarily used for auxiliary cleaning and foam stabilization. Its unique molecular structure effectively reduces the denaturing effect of single anionic surfactants on scalp proteins, further enhancing the product's gentleness.

[0024] 4. Phytosterols: As lipophilic active ingredients, they are poorly soluble in water. In this system, they are mainly solubilized within the micelle cores formed by surfactants. When the shampoo comes into contact with the hair and scalp, phytosterols are released and penetrate, exerting their repairing, moisturizing, and anti-inflammatory effects.

[0025] 5. Cationic cellulose and cationic guar gum: Both are cationic conditioning polymers. When dissolved in water, they carry a positive charge and deposit on the negatively charged hair surface (especially the negatively charged sites on damaged hair strands) through electrostatic adsorption. This adsorption not only neutralizes static electricity and reduces frizz, but also provides a lubricating layer on the hair surface, significantly improving wet and dry combing performance. Due to the extremely low dosage, this film is thin and breathable, and will not make the hair feel heavy.

[0026] 6. Trimethylglycine and glutamate: Trimethylglycine is a natural osmotic regulator that helps scalp keratinocytes maintain moisture balance and alleviates osmotic pressure irritation that surfactants may cause. Glutamate, as an amino acid-based moisturizer, participates in the composition of the skin's natural moisturizing factors, enhancing the formula's moisturizing effect. Together, they form a moisturizing buffer system in the formula, reducing the "tight feeling after washing."

[0027] 7. Alkyl glycosides: Nonionic surfactants with a structure of "one end hydrophilic (sugar ring) and one end lipophilic (alkyl chain)". They can increase the number and diversity of micelles in the system, improve the emulsification ability of oil stains, and due to their nonionic properties, they are not sensitive to changes in the ionic strength of the system, which helps to maintain the stability of the formulation.

[0028] 8. Lactic acid: Primarily used as a pH adjuster. Adjusting the system from alkaline to slightly acidic (pH 5.0-6.0), a pH value close to the isoelectric point of human scalp and hair, helps close the hair cuticle, making hair shinier, while inhibiting the growth of harmful bacteria on the scalp.

[0029] II. Principle of Preparation Steps:

[0030] This preparation process employs a strategy combining gradient temperature control and segmented pH regulation. First, the cationic polymer is fully swollen at 45-50℃ to ensure complete hydration. Then, sodium lauroyl sarcosinate is added at 40-45℃, and the pH is adjusted to 7.0-8.0 to construct a micelle-rich, alkaline, transparent environment as a solubilizing carrier for subsequent hydrophobic components. After cooling to 35-40℃, the phytosterols are solubilized and their activity is maintained using this micelle system. Subsequently, an amino acid-based moisturizer is added, and lactic acid is used to adjust the pH of the system to 5.0-6.0, establishing a scalp-friendly, weakly acidic environment while optimizing the system's charge balance. Finally, lauramidopropyl betaine and alkyl glycosides are added at 35-40℃, and a complex of multiple surfactants is used to induce micelle structural transformation to achieve thickening and maintain system transparency. Fragrance is added at a low temperature of 25-30℃ to reduce volatilization, ultimately yielding a standard-compliant and stable finished product.

[0031] Its core principle is as follows:

[0032] 1. Construct a "mild and clean" multi-surfactant compound system

[0033] This formulation abandons traditional sulfate surfactants and instead adopts a compounding strategy of "amino acid anionic surfactant + amphoteric surfactant + nonionic surfactant".

[0034] The primary cleaning power is provided by sodium lauroyl sarcosinate, an amino acid-based anionic surfactant with excellent degreasing and foaming properties, and significantly lower irritation to the skin and eyes compared to sulfates.

[0035] The foaming and foaming effects are provided by lauramidopropyl betaine and disodium lauroyl amphoteric diacetate. These two types of amphoteric surfactants can not only significantly improve the richness and fineness of the foam, but also reduce the irritation of the main surfactant and enhance the mildness of the formula.

[0036] The synergistic effect is achieved by introducing alkyl glycosides (APG), a nonionic surfactant derived from natural oils, which has excellent mildness and eco-friendliness, and can further balance the cleaning power and mildness of the system.

[0037] 2. Constructing a "weakly cationic" conditioning system to achieve silicone-free smoothness: To provide a smooth feel without using silicone oil, this invention designs a unique "weakly cationic system":

[0038] It utilizes extremely low levels of cationic cellulose and cationic guar gum as the conditioning agents. These positively charged polymers can adhere to the negatively charged hair cuticle surface during shampooing, forming an extremely thin protective film that provides anti-static and smooth effects.

[0039] Because the amount of cationic polymer used is extremely small, and the system is still dominated by anionic / nonionic surfactants, the overall system charge is weakly cationic or electrically neutral. This design avoids the problems of "excessive deposition and flat hair" caused by traditional high-cationic conditioners, and achieves a balance of "refreshing after washing, easy to comb when wet, and smooth when dry".

[0040] 3. Moisturizing strategy of replacing silicone oil with "active oils"

[0041] Use phytosterols instead of traditional silicone oil. Phytosterols have a structure similar to skin sebum, which can not only repair damaged hair and scalp barrier, but also be evenly dispersed in the formula through the solubilizing effect of surfactant micelles, providing a moisturizing but non-greasy feel.

[0042] Compared with the prior art, the beneficial effects of the present invention are:

[0043] 1. This invention is gentle and safe, with no harmful residues, and meets the needs of scalp health. The formula eliminates silicone oil and sulfate surfactants, and no harmful substances such as D4 and dioxane were detected. It has only mild acute eye irritation, is gentle on the scalp and eyes, and has no obvious irritation, making it suitable even for sensitive scalps. The system's pH value is controlled within a slightly acidic range of 5.0-6.0, which is close to the isoelectric point of human scalp and hair. This helps to close hair cuticles, enhance hair shine, inhibit the growth of harmful bacteria on the scalp, and reduce tightness after washing. Furthermore, compared with mainstream control products on the market, the silicone oil-free, sulfate-free, and weakly cationic shampoo developed in this invention has achieved a comprehensive upgrade in terms of cleansing power, gentleness, conditioning effect, repair function, and user experience. It successfully solves the core pain points of existing similar products, such as "imbalance between cleansing and gentleness, contradiction between smoothness and refreshing feeling, and limited repair effect," giving it stronger market competitiveness.

[0044] 2. This invention utilizes a multi-surfactant compound consisting of amino acid anionic surfactant, amphoteric surfactant, and nonionic surfactant. While ensuring a cleansing rate of 91-97%, it produces rich, fine foam that is easy to rinse and leaves no residue. The weak cationic conditioning system is synergistically constructed from cationic cellulose and cationic guar gum. With precise dosage, it forms a thin, breathable protective film on the hair surface through electrostatic adsorption, significantly reducing combing resistance, improving the smoothness of wet and dry hair, and reducing frizz, without causing the hair to become flat and heavy. This achieves a balance between "cleansing and refreshing + smooth and anti-frizz."

[0045] 3. This invention uses phytosterols instead of traditional silicone oil. Phytosterols have a structure similar to skin sebum and, after being solubilized by surfactant micelles, can effectively penetrate hair strands, providing repair, moisturizing, and anti-inflammatory effects while avoiding the greasy feeling caused by silicone oil residue. Combined with moisturizing ingredients such as trimethylglycine and glutamic acid, a moisturizing buffer system is constructed to further enhance the moisturizing effect, reduce scalp dryness and discomfort, and also has a good repairing effect on dyed and permed hair.

[0046] 4. This invention utilizes a gradient temperature and segmented pH control preparation process to ensure full hydration of the cationic polymer and complete solubilization of the active ingredients. The product remains stable in viscosity and active ingredient content even after being stored at 60°C for four months without stratification or significant discoloration. The precise dosage of each component allows for stable production without complex equipment, and the production process generates no additional harmful substances, combining practicality and environmental friendliness. Attached Figure Description

[0047] Figure 1 This is a process flow diagram of the silicone-free, sulfate-free, weakly cationic shampoo prepared according to the present invention. Detailed Implementation

[0048] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with existing known technologies. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0049] Example 1: A silicone-free, sulfate-free, weakly cationic shampoo, comprising the following components by mass percentage: lauramidopropyl betaine 20%, sodium lauroyl sarcosinate 10%, disodium lauroamphodiacetate 2%, phytosterols 0.2%, cationic cellulose 0.1%, cationic guar gum 0.05%, phenoxyethanol 0.3%, fragrance 0.1%, trimethylglycine 0%, glutamic acid 0%, alkyl glycosides 0%, lactic acid 0%, and deionized water 67.25%.

[0050] A method for preparing a silicone-free, sulfate-free, weakly cationic shampoo includes the following steps:

[0051] Step 1: Add the prescribed amount of deionized water to the mixing pot and heat it to 45°C; mix cationic cellulose and cationic guar gum according to the formula ratio, slowly sprinkle them into the water, and stir at 300 r / min for 30 min to form a homogeneous and transparent liquid;

[0052] Step 2: Keep the temperature of the homogeneous and transparent liquid system at 40℃, add sodium lauroyl sarcosinate, stir at 250r / min for 20min, adjust the pH of the system to 7.0, and continue stirring for 10min to form an alkaline transparent body;

[0053] Step 3: Cool the alkaline transparent body to 35°C, add phytosterols, stir at 200 r / min for 15 min until completely soluble, then add phenoxyethanol and continue stirring for 10 min to form a soluble transparent homogeneous body;

[0054] Step 4: Maintain the temperature of the solubilization and clearing homogenization mixture at 35℃, stir at 200r / min for 10min, add citric acid to adjust the pH, and form an acidic clear mixture;

[0055] Step 5: Keep the temperature of the acidic transparent body at 35°C, slowly add lauramidopropyl betaine and disodium lauroamphodiacetate, and stir at 250 r / min for 25 min to form a uniform, transparent, viscous liquid;

[0056] Step 6: Keep the temperature of the viscous liquid at 25℃, add the flavoring, stir at 100r / min for 10min, take a sample for testing and if it meets the standard, the finished product is obtained by discharging.

[0057] Example 2: A silicone-free, sulfate-free, weakly cationic shampoo, comprising the following components by mass percentage: lauramidopropyl betaine 23%, sodium lauroyl sarcosinate 15%, disodium lauroamphodiacetate 2.5%, phytosterols 0.3%, cationic cellulose 0.15%, cationic guar gum 0.06%, phenoxyethanol 0.4%, fragrance 0.3%, trimethylglycine 0.3%, glutamic acid 0.4%, alkyl glycosides 0.5%, lactic acid 0.2%, and deionized water 56.89%.

[0058] A method for preparing a silicone-free, sulfate-free, weakly cationic shampoo includes the following steps:

[0059] Step 1: Add the prescribed amount of deionized water to the mixing pot and heat it to 46°C; mix cationic cellulose and cationic guar gum according to the formula ratio, slowly sprinkle them into the water, and stir at 320 r / min for 32 min to form a homogeneous and transparent liquid;

[0060] Step 2: Keep the temperature of the homogeneous and transparent liquid system at 42℃, add sodium lauroyl sarcosinate, stir at 260r / min for 21min, adjust the pH of the system to 7.2, and continue stirring for 12min to form an alkaline transparent body;

[0061] Step 3: Cool the alkaline transparent body to 36℃, add phytosterols, stir at 220r / min for 16min until completely soluble, then add phenoxyethanol and continue stirring for 16min to form a soluble transparent homogeneous body;

[0062] Step 4: Keep the temperature of the solubilization and clearing homogenization body at 36℃, add trimethylglycine and glutamic acid, stir at 210 r / min until completely dissolved, control the pH of the system to 5.2 with lactic acid, and continue stirring for 12 min to form an acidic clear body;

[0063] Step 5: While maintaining the temperature of the acidic transparent body at 36°C, slowly add lauramidopropyl betaine, disodium lauroamphodiacetate and alkyl glycoside, and stir at 260 r / min for 26 min to form a uniform, transparent, viscous liquid;

[0064] Step 6: Keep the temperature of the viscous liquid at 26℃, add the flavoring, stir at 130r / min for 12min, take a sample for testing and if it meets the standard, the finished product is obtained by discharging.

[0065] Example 3: A silicone-free, sulfate-free, weakly cationic shampoo, comprising the following components by mass percentage: lauramidopropyl betaine 25%, sodium lauroyl sarcosinate 18%, disodium lauroamphodiacetate 3.0%, phytosterols 0.4%, cationic cellulose 0.16%, cationic guar gum 0.07%, phenoxyethanol 0.45%, fragrance 0.35%, trimethylglycine 0.4%, glutamic acid 0.5%, alkyl glycoside 1.0%, lactic acid 0.3%, and deionized water 50.37%.

[0066] A method for preparing a silicone-free, sulfate-free, weakly cationic shampoo includes the following steps:

[0067] Step 1: Add the prescribed amount of deionized water to the mixing pot and heat it to 47°C; mix cationic cellulose and cationic guar gum according to the formula ratio, slowly sprinkle them into the water, and stir at 330 r / min for 35 min to form a homogeneous and transparent liquid;

[0068] Step 2: Keep the temperature of the homogeneous and transparent liquid system at 43℃, add sodium lauroyl sarcosinate, stir at 270r / min for 22min, adjust the pH of the system to 7.5, and continue stirring for 15min to form an alkaline transparent body;

[0069] Step 3: Cool the alkaline transparent body to 38℃, add phytosterols, stir at 230r / min for 18min until completely soluble, then add phenoxyethanol and continue stirring for 17min to form a soluble transparent homogeneous body;

[0070] Step 4: Keep the temperature of the solubilization and clearing homogenate at 37°C, add trimethylglycine and glutamic acid, stir at 220 r / min until completely dissolved, control the pH of the system to 5.3 with lactic acid, and continue stirring for 15 min to form an acidic clear body;

[0071] Step 5: While maintaining the temperature of the acidic transparent body at 38°C, slowly add lauramidopropyl betaine, disodium lauroamphodiacetate and alkyl glycoside, and stir at 270 r / min for 28 min to form a uniform, transparent, viscous liquid.

[0072] Step 6: Keep the temperature of the viscous liquid at 28℃, add the flavoring, stir at 150r / min for 13min, take a sample for testing and if it meets the standard, the finished product is obtained by discharging.

[0073] Example 4: A silicone-free, sulfate-free, weakly cationic shampoo, comprising the following components by mass percentage: lauramidopropyl betaine 30%, sodium lauroyl sarcosinate 20%, disodium lauroamphodiacetate 3.5%, phytosterols 0.5%, cationic cellulose 0.18%, cationic guar gum 0.08%, phenoxyethanol 0.5%, fragrance 0.4%, trimethylglycine 0.5%, glutamic acid 0.8%, alkyl glycosides 1.5%, lactic acid 0.4%, and deionized water 41.64%.

[0074] A method for preparing a silicone-free, sulfate-free, weakly cationic shampoo includes the following steps:

[0075] Step 1: Add the prescribed amount of deionized water to the mixing pot and heat it to 48°C; mix cationic cellulose and cationic guar gum according to the formula ratio, slowly sprinkle them into the water, and stir at 360 r / min for 38 min to form a homogeneous and transparent liquid;

[0076] Step 2: Keep the temperature of the homogeneous and transparent liquid system at 44℃, add sodium lauroyl sarcosinate, stir at 280r / min for 23min, adjust the pH of the system to 7.8, and continue stirring for 18min to form an alkaline transparent body;

[0077] Step 3: Cool the alkaline transparent body to 39°C, add phytosterols, stir at 240 r / min for 19 min until completely soluble, then add phenoxyethanol and continue stirring for 19 min to form a soluble transparent homogeneous body;

[0078] Step 4: Keep the temperature of the solubilization and clearing homogenate at 38℃, add trimethylglycine and glutamic acid, stir at 240r / min until completely dissolved, control the pH of the system to 5.5 with lactic acid, and continue stirring for 18min to form an acidic clear body;

[0079] Step 5: While maintaining the temperature of the acidic transparent body at 39°C, slowly add lauramidopropyl betaine, disodium lauroamphodiacetate and alkyl glycoside, and stir at 280 r / min for 29 min to form a uniform, transparent, viscous liquid.

[0080] Step 6: Keep the temperature of the viscous liquid at 29℃, add the flavoring, stir at 180r / min for 14min, take a sample for testing and if it meets the standard, the finished product is obtained by discharging.

[0081] Example 5: A silicone-free, sulfate-free, weakly cationic shampoo, comprising the following components by mass percentage: lauramidopropyl betaine 38%, sodium lauroyl sarcosinate 28%, disodium lauroamphodiacetate 4%, phytosterols 0.6%, cationic cellulose 0.2%, cationic guar gum 0.1%, phenoxyethanol 0.6%, fragrance 0.5%, trimethylglycine 0.8%, glutamic acid 1.0%, alkyl glycosides 2%, lactic acid 0.5%, and deionized water 23.7%.

[0082] A method for preparing a silicone-free, sulfate-free, weakly cationic shampoo includes the following steps:

[0083] Step 1: Add the prescribed amount of deionized water to the mixing pot and heat it to 50°C; mix cationic cellulose and cationic guar gum according to the formula ratio, slowly sprinkle them into the water, and stir at 400 r / min for 40 min to form a homogeneous and transparent liquid;

[0084] Step 2: Keep the temperature of the homogeneous and transparent liquid system at 45℃, add sodium lauroyl sarcosinate, stir at 300r / min for 25min, adjust the pH of the system to 8.0, and continue stirring for 20min to form an alkaline transparent body;

[0085] Step 3: Cool the alkaline transparent body to 40℃, add phytosterols, stir at 250r / min for 20min until completely soluble, then add phenoxyethanol and continue stirring for 20min to form a soluble transparent homogeneous body;

[0086] Step 4: Keep the temperature of the solubilization and clearing homogenate at 40℃, add trimethylglycine and glutamic acid, stir at 250r / min until completely dissolved, control the pH of the system to 6.0 with lactic acid, and continue stirring for 20min to form an acidic clear body;

[0087] Step 5: While maintaining the temperature of the acidic transparent body at 40°C, slowly add lauramidopropyl betaine, disodium lauroamphodiacetate and alkyl glycoside, and stir at 300 r / min for 30 min to form a uniform, transparent, viscous liquid;

[0088] Step 6: Keep the temperature of the viscous liquid at 30℃, add the flavoring, stir at 200r / min for 15min, take a sample for testing and if it meets the standard, the finished product is obtained by discharging.

[0089] Comparative Example 1: Based on Example 3, the difference is that the shampoo formula contains 1.2% phytosterols and 49.57% deionized water, while the rest is the same as in Example 3.

[0090] Comparative Example 2: Based on Example 3, the difference is that the shampoo formula contains 0.5% alkyl glycoside and 50.87% deionized water, and the rest is the same as in Example 3.

[0091] Comparative Example 3: Based on Example 3, the difference is that the shampoo formula contains 15% lauramidopropyl betaine and 60.37% deionized water, with the rest being the same as in Example 3.

[0092] Comparative Example 4: Based on Example 3, the difference is that the shampoo formula contains 6% disodium lauroamphodiacetate and 47.37% deionized water, with the rest being the same as in Example 3.

[0093] Comparative Example 5: Based on Example 3, the difference is that the shampoo formula contains 8% sodium lauroyl sarcosinate and 60.37% deionized water, with the rest being the same as in Example 3.

[0094] Comparative Example 6: Based on Example 3, the difference is that the shampoo formula contains 1.5% glutamic acid and 49.37% deionized water, and the rest is the same as in Example 3.

[0095] Comparative Example 7: Based on Example 3, the difference is that the shampoo formula contains 0.05% cationic cellulose and 50.48% deionized water, and the rest is the same as in Example 3.

[0096] Comparative Example 8: Based on Example 3, the difference is that the shampoo formula contains 0.15% cationic guar gum and 50.29% deionized water, with the rest being the same as in Example 3.

[0097] Comparative Example 9: Based on Example 3, the difference is that the shampoo formula contains 0.8% lactic acid and 49.87% deionized water, and the rest is the same as in Example 3.

[0098] Comparative Example 10: Based on Example 3, the difference is that in the shampoo formula, "phytosterols" are replaced with "polydimethylsiloxane", and the rest is the same as in Example 3.

[0099] Comparative Example 11: Based on Example 3, the difference is that in the shampoo formula, "sodium lauroyl sarcosinate" is replaced with "sodium lauryl ether sulfate", and the rest is the same as in Example 3.

[0100] Comparative Example 12: Based on Example 3, the difference is that "lauramidopropyl betaine and sodium lauroyl sarcosinate" are replaced with "sodium laureth sulfate and sodium lauryl sulfate", respectively, and the rest is the same as Example 3.

[0101] Comparative Example 13: Based on Example 3, the difference is that "cationic cellulose and cationic guar gum and phytosterols" are replaced with "polydimethylsiloxane and quaternary ammonium salt-73", and the rest is the same as Example 3.

[0102] Comparative Example 14: Based on Example 3, the difference is that the alkyl glycoside is replaced with the synthetic nonionic surfactant "fatty alcohol polyoxyethylene ether (AEO-9)", otherwise it is the same as Example 3.

[0103] Comparative Example 15: Based on Example 3, the difference is that the preparation steps are changed. Specifically, the steps are as follows: First step: Add the amount of deionized water in the formula to the mixing pot and heat to 38°C; add all the components in the formula to the deionized water at once; Second step: Stir at 270 r / min for 40 min without adjusting the pH; Third step: Cool down to 28°C, add the fragrance, stir for 13 min, take a sample for testing, and the rest is the same as in Example 3.

[0104] Test Example: The shampoo products prepared in Examples 1-5 and Comparative Examples 1-15 were used as samples. The reference standard was the commercially leading Zhiguan Amino Acid Silicone-Free Shampoo. The following test items were performed:

[0105] 1. Viscosity test: An NDJ-1 rotational viscometer was used, with rotor size 3, rotation speed of 12 rpm / min, and measurement temperature of 25℃. The value was read after 3 minutes of instrument operation, and three consecutive measurements were taken. The error range was controlled within 5%, and the average value was used.

[0106] 2. pH value determination: After shaking the sample well, place it in a constant temperature environment of 25℃ for 10 minutes, and then measure it using a pH meter.

[0107] 3. Determination of Active Ingredient Content: The determination was performed according to Section 4.2, "Determination of Active Ingredient Content (Gravity Method)," of GB / T 13173-2021 "Test Methods for Surfactants and Detergents." The specific procedure was as follows: Take 10.00 g of sample, dissolve it in ethanol, transfer it to a 250 mL volumetric flask, dilute to volume, filter, and use 50 mL of the filtrate for subsequent determination. Operating conditions were: evaporation temperature 105℃, drying time 2 h, constant weight until the difference between two weighings was ≤0.0002 g.

[0108] 4. Detection of D4 (cyclotetramethylsiloxane) and dioxane content: Gas chromatography-mass spectrometry was used for detection.

[0109] 5. Foam Height Detection: A Roche foam apparatus and a No. 3 dropper were used. A 1% (w / w) solution was prepared and equilibrated at 25°C for 30 minutes. The dropper was placed 50 cm high, and the solution was poured from the top of the graduated tube. The initial foam height (0 min) and the foam height after 5 min were recorded, and the average value of three parallel tests was taken.

[0110] 6. Combing Power Test: A combing instrument was used for testing. Natural, undyed, black hair, 20cm in length, was selected, with 5g per strand. After rinsing with deionized water, the hair was equilibrated at 25℃ and 50% humidity for 24 hours. The hair samples were then immersed in 37℃ deionized water for 1 minute and allowed to air dry until the moisture content was ≤10% before testing.

[0111] 7. Stability test: Each group of shampoo samples was placed at 60℃ for 4 months to check the properties of the samples before and after storage under different conditions.

[0112] 8. Cleaning Power Test: First, prepare artificial sebum according to the composition of human scalp sebum. Prepare analytical balance, constant temperature water bath, and other instruments and reagents. After ultrasonic cleaning and drying, accurately weigh the standard glass slide. Melt the artificial sebum and keep it at 37°C for later use. Simultaneously, prepare a 1% shampoo test solution and keep it at a constant temperature. Use a pipette to evenly apply the artificial sebum to the designated area of ​​the glass slide. After curing at 37°C, weigh it to calculate the actual amount applied. Immerse the glass slide in the 37°C shampoo test solution and stir and clean it for 5 minutes at 200 rpm. Then, use a 37°C shampoo test solution to clean it. Rinse with deionized water; then place the glass slide into a stoppered colorimetric tube, add ethanol and sonicate to extract residual sebum. Take the extract and react it with Sudan III ethanol solution for color development. Determine the concentration and mass of residual sebum using a spectrophotometer combined with a standard curve. Set up 3 parallel tests and blank control for each sample. Finally calculate the residual rate and cleanliness rate. The results are judged as follows: cleanliness rate ≥90% is excellent, 80%-89% is good, 70%-79% is qualified, and <70% is unqualified. The test process must strictly control the temperature, speed and other conditions to ensure that the reagents are freshly prepared and the equipment is clean and uncontaminated.

[0113] Residual rate (R): R = (m residue / m grease) × 100%; Cleaning rate (C): C = (1 - R) × 100% = [1 - (m residue / m grease)] × 100%.

[0114] 9. Acute eye irritation test: Two bottles of shampoo were tested for each group. The test was conducted in accordance with the Cosmetic Safety Technical Specifications (2015 Edition).

[0115] 9.1 Animal Model: Three healthy New Zealand white rabbits, weighing 2.0-2.5 kg, were selected. The cornea, iris, and conjunctiva were examined 24 hours before the experiment and no abnormalities were found.

[0116] 9.2 Administration of the test substance: 0.1 mL of the test substance was instilled into the left eye of each rabbit, and 0.1 mL of physiological saline was instilled into the right eye as a control. After closing the eyes for 1 min, the eyes were rinsed with 37℃ physiological saline for 30 s at a flow rate of 10 mL / min.

[0117] 9.3 Scoring Criteria: Scoring was conducted according to Table 1, pp. 494-495, of the "Cosmetic Safety Technical Specifications" (2015 Edition). Evaluation was based on the mean score of the stimulation response of the animal's cornea, iris, or conjunctiva at 24h, 48h, and 72h after administration of the test substance, and the recovery time.

[0118] 9.4 Result Judgment Criteria: The intensity of eye stimulation caused by the test substance shall be determined according to the eye stimulation response grading in Table 3 of P495 of the specification.

[0119] 10. Sensory Evaluation Test: 30-50 participants aged 18-45 years with different hair types (including those damaged by dyeing and perming), excluding those with allergies and scalp diseases, were randomly and evenly grouped. Each shampoo sample was numbered and individually packaged. Unscented towels, wide-tooth combs, and constant-temperature shower equipment (38±1℃) were provided. An independent and undisturbed testing environment was set up. Participants discontinued using hair care products and washed their hair thoroughly for 3 days prior to the test. Approximately 5mL of the sample was taken, lathered, and washed for 2 minutes using the usual method. The sample was then rinsed with 38±1℃ warm water for 30 seconds and gently patted dry. The immediate experience of foam fineness and ease of rinsing was evaluated 10 minutes after washing, the smoothness and anti-frizz effect after drying was evaluated 4 hours later, and the fragrance longevity and freshness were evaluated 24 hours later. The scale was filled out independently on a scale of 1-5. After collection, invalid data were removed, and the average score of each dimension and the overall score was calculated. The result was judged as ≥4.0 as excellent, 3.5-3.9 as good, 3.0-3.4 as qualified, and <3.0 as unqualified. The operating conditions were strictly uniform during the test. If scalp discomfort occurred, the test was stopped immediately and the relevant data was excluded.

[0120] Table 1. Test Results of Basic Performance of Shampoo Products

[0121] Note: "-" indicates not detected.

[0122] Table 2 Supplementary Test Results of Core Performance of Shampoo Products

[0123] Table 3. Results of the acute eye irritation test of the test substance on rabbits (rinse for 30 seconds).

[0124]

[0125]

[0126] Table 4. Sensory evaluation test results

[0127] Analysis of the data in Tables 1-4 shows that the silicone-free, sulfate-free, weakly cationic shampoos prepared in Examples 1-5 are characterized by their mildness, safety, balanced and stable performance, and excellent user experience. They exhibit significant advantages over the leading-selling control shampoos on the market. Their pH value matches the slightly acidic environment of the human scalp, their viscosity is suitable for easy use, they contain sufficient active ingredients and no harmful components were detected, demonstrating outstanding safety. They produce rich and delicate foam, making both wet and dry hair easy to comb. They exhibit good long-term storage stability, excellent cleansing power, and only mild acute eye irritation, being gentle and non-irritating to the scalp and eyes. They demonstrate outstanding performance in key usage dimensions such as foam fineness, ease of rinsing, and smoothness and anti-frizz properties, successfully achieving an organic balance between cleansing power, gentleness, and conditioning effects.

[0128] I. Comparative Analysis of Ingredient Dosage Adjustments

[0129] Compared with Example 3, these comparative examples did not change the types of ingredients in the original formula, but only adjusted the amount of a single ingredient. The result was a decrease in product performance, highlighting the precise compatibility of the amount of each ingredient in the original formula with the system.

[0130] Comparative Example 1: Increasing the amount of phytosterols decreased cleaning power and smoothness, and the system showed slight discoloration. Excessive phytosterols exceeded the solubilizing capacity of the surfactant micelles, and the unsoluble components disrupted the system's stability.

[0131] Comparative Example 2: Reducing the amount of alkyl glycosides resulted in a decrease in foam performance, cleaning power, and smoothness. Insufficient alkyl glycoside usage led to a reduction in the number and diversity of micelles in the system, and a weakened ability to emulsify oil stains.

[0132] Comparative Example 3: Reducing the amount of lauramidopropyl betaine resulted in decreased viscosity and foam stability, slight layering and discoloration, and reduced cleaning power and smoothness. Insufficient dosage of this ingredient disrupted the synergistic balance of the multiple surfactants.

[0133] Comparative Example 4: Increasing the amount of disodium lauroamphodiacetate resulted in an abnormal increase in viscosity, increased combing resistance, significant discoloration of the system, and decreased cleaning power. Excessive use of this component led to a charge imbalance in the system, disrupting the synergistic effect between surfactants.

[0134] Comparative Example 5: Reducing the amount of sodium lauroyl sarcosinate resulted in a decrease in the active ingredient content, a drop in viscosity, noticeable stratification and discoloration, insufficient cleaning power, and increased irritation. Insufficient dosage of this ingredient disrupted the system's stability and the balance of surfactant ratios.

[0135] Comparative Example 6: Increasing the amount of glutamic acid did not significantly improve core performance, but the system showed slight discoloration, resulting in a decreased user experience. Excessive glutamic acid affects the charge balance of the system.

[0136] Comparative Example 7: Reducing the amount of cationic cellulose resulted in decreased viscosity, increased combing resistance, and slight stratification and discoloration. Insufficient dosage of this component weakened its thickening and stabilizing effects on the system.

[0137] Comparative Example 8: Increasing the amount of cationic guar gum resulted in an abnormal increase in viscosity, and the smoothness did not improve with the increase in dosage but instead slightly decreased. Excessive use of this component caused abnormal viscosity in the system, and excessive cationic polymers tended to entangle with each other.

[0138] Comparative Example 9: Increasing the amount of lactic acid caused the pH value to deviate from the suitable range for the scalp, increasing combing resistance and causing a noticeable discoloration of the system. Excessive lactic acid caused pH imbalance in the system, compromising the stability of the surfactant.

[0139] II. Comparative Analysis of Core Component Replacement Categories

[0140] Compared to Example 3, these comparative examples replaced the core functional ingredients of the original formula, resulting in a decline in product safety, mildness, or user experience, highlighting the innovative advantages of the original formula's ingredient selection.

[0141] Comparative Example 10: Replacing phytosterols with polydimethylsiloxane revealed harmful components, resulting in decreased cleaning and conditioning effectiveness and reduced safety. Silicone oils cannot be effectively solubilized by surfactant micelles, leaving residues and posing potential safety risks.

[0142] Comparative Example 11: Replacing sodium lauroyl sarcosinate with sodium laureth sulfate increased irritation, reduced smoothness and user experience, and caused significant discoloration of the system. Sulfate surfactants are significantly more irritating than amino acid-based surfactants and exhibit poor synergistic compatibility with amphoteric surfactants.

[0143] Comparative Example 12: Replacing lauramidopropyl betaine and sodium lauroyl sarcosinate with two sulfate surfactants revealed harmful components, significantly increased irritation, noticeable layering and discoloration, and a substantial decrease in cleaning power and user experience. Sulfate-based compound systems are highly irritating, prone to producing harmful substances, and exhibit poor stability.

[0144] Comparative Example 13: Replacing cationic cellulose, cationic guar gum, and phytosterols with polydimethylsiloxane and quaternary ammonium salt-73 revealed harmful components, increased combing resistance, and slight stratification. The combination system of silicone oil and quaternary ammonium salt failed to achieve a weak cationic conditioning effect, and the system stability was poor.

[0145] Comparative Example 14: Replacing alkyl glycosides with synthetic nonionic surfactants resulted in a decrease in both viscosity and user experience. Synthetic nonionic surfactants exhibit poor compatibility and synergy with other surfactants, affecting the balance between system viscosity and cleaning power.

[0146] III. Comparative Analysis of Preparation Process Changes

[0147] Compared with Example 3, this type of comparative example only changed the preparation steps of the original formula without adjusting the types and amounts of ingredients. As a result, the product performance declined across the board, highlighting the rationality and necessity of the original preparation process.

[0148] Comparative Example 15: By changing the preparation steps, adding the materials all at once without adjusting the pH, the pH value became unbalanced, the viscosity decreased significantly, and obvious stratification and discoloration occurred. The cleaning power was insufficient, and the irritation increased. Because a gradient temperature and segmented pH control strategy was not adopted, the cationic polymer did not swell and hydrate sufficiently, the surfactant could not form stable micelles, and the active ingredient was not completely solubilized, leading to an imbalance in the system's charge and stability.

[0149] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A silicone-free, sulfate-free, weakly cationic shampoo, characterized in that, By weight percentage, the shampoo comprises the following components: lauramidopropyl betaine 20-38%, sodium lauroyl sarcosinate 10-28%, disodium lauroamphodiacetate 2-4%, phytosterols 0.2-0.6%, cationic cellulose 0.1-0.2%, cationic guar gum 0.05-0.1%, preservatives 0.3-0.6%, fragrance 0.1-0.5%, trimethylglycine 0-0.8%, glutamic acid 0-1.0%, alkyl glycosides 0-2%, lactic acid 0-0.5%, and deionized water to 100%. The shampoo is free of silicone oils and sulfate surfactants, including but not limited to polydimethylsiloxane and amino silicone oils, and sulfate surfactants including but not limited to sodium lauryl sulfate and sodium laureth sulfate. The shampoo's weak cationic conditioning function is synergistically achieved by cationic cellulose and cationic guar gum.

2. The silicone-free, sulfate-free, weakly cationic shampoo according to claim 1, characterized in that, The preservative is one or more of phenoxyethanol and ethylhexylglycerin.

3. The silicone-free, sulfate-free, weakly cationic shampoo according to claim 1, characterized in that, The phytosterols are phytosterol fatty acid esters with a number average molecular weight of 700-900 Da.

4. A method for preparing a silicone-free, sulfate-free, weakly cationic shampoo as described in claim 1, characterized in that, Includes the following steps: Step 1: Add the prescribed amount of deionized water to the mixing pot and heat it to 45-50℃; mix cationic cellulose and cationic guar gum according to the formula ratio, slowly sprinkle them into the water, and stir at 300-400r / min for 30-40min to form a homogeneous and transparent liquid. Step 2: Keep the temperature of the homogeneous and transparent liquid system at 40-45℃, add sodium lauroyl sarcosinate, stir at 250-300r / min for 20-25min, adjust the pH of the system to 7.0-8.0, and continue stirring for 10-20min to form an alkaline transparent body; Step 3: Cool the alkaline transparent body to 35-40℃, add phytosterols, and stir at 200-250r / min for 15-20min until completely soluble. Then add preservatives and continue stirring for 10-20min to form a soluble, transparent, and homogeneous body. Step 4: Keep the temperature of the solubilization and transparent homogenization system at 35-40℃, selectively add trimethylglycine and glutamic acid, stir at 200-250 r / min until completely dissolved, selectively add lactic acid to control the pH of the system, and continue stirring for 10-20 min to form an acidic transparent body; Step 5: Keep the temperature of the acidic transparent body at 35-40℃, slowly add lauramidopropyl betaine and disodium lauroamphodiacetate, and then selectively add alkyl glycosides. Stir at 250-300 r / min for 25-30 min to form a uniform, transparent, viscous liquid. Step 6: Keep the temperature of the viscous liquid at 25-30℃, add the flavoring, stir at 100-200r / min for 10-15min, take a sample for testing and after it meets the standard, discharge the material to obtain the finished product.

5. A method for preparing a silicone-free, sulfate-free, weakly cationic shampoo as described in claim 4, characterized in that, In the fourth step, the pH of the control system is 5.0-6.

0.

6. A method for preparing a silicone-free, sulfate-free, weakly cationic shampoo as described in claim 4, characterized in that, In step six, the standard is that the total surfactant content (active ingredient) is 12-20%, the pH value is 5.0-6.0, and the viscosity is 3000-5000 mPa·s.

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