A softening laundry soap containing a cation-polyol complex and a method for making the same

Abstract

The present application relates to the technical field of daily chemical washing products, and discloses a softening laundry soap containing a cation-polyol compound and a preparation method thereof, which comprises the following components in percentage by mass: soap particles: 92-98%; cation-polyol compound: 2-5%; essence: 0.3-1%; and other additives: 0.1-2%. The cation-polyol compound is prepared by shearing emulsification and cooling of a cationic surfactant, a polyol and water, and the mass ratio of the cationic surfactant to the polyol is 1:2-4. The cation-polyol compound is constructed to pre-integrate the cationic softening agent in a stable structure, which is then introduced into the soap base, so as to effectively improve the compatibility, storage stability of the cation and the soap base, and ensure efficient release during washing, and realize long-acting and stable softening function of the laundry soap.

Description

Technical Field

[0001] This invention relates to the technical field of daily chemical washing products, and in particular to a softening laundry soap containing a cationic-polyol complex and its preparation method. Background Technology

[0002] Traditional laundry soaps, primarily composed of sodium fatty acids, offer strong detergency but lack versatility, often leaving fabrics feeling stiff and dry after washing, lacking a soft and smooth feel. To impart softening properties to laundry soaps, the art often involves adding cationic surfactants (such as quaternary ammonium salts). However, directly mixing cationic surfactants with the anionic surfactants (sodium fatty acids) in the soap base presents the following problems: charge neutralization leads to soap structure damage (softening, cracking), system instability (precipitation, flocculation), and the cationic components are easily hydrolyzed and deactivated in the alkaline environment of the soap (pH 9.5-10.5), resulting in low release rates during washing and ineffective adsorption onto fabrics, leading to short-lived and unreliable softening effects.

[0003] Patent CN107446732A discloses a softening and whitening laundry soap composition and its preparation method. By compounding nonionic / anionic surfactants such as fatty alcohol polyoxyethylene ether and alkyl glycosides, and adding molding agents such as sodium carboxymethyl cellulose, the compatibility between surfactants and soap particles is improved, indirectly reducing soap scum deposition, thereby alleviating the problem of fabrics becoming stiff after washing to a certain extent. However, this solution has the following shortcomings: (1) It does not use cationic components as the core of the softening function, relying on surfactant compounding and molding agent assistance, resulting in limited softening effect; (2) It does not solve the compatibility problem between cationic and anionic systems; (3) The softening function is achieved by reducing soap scum deposition, rather than true cationic adsorption softening, so the effect is not lasting. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a softening laundry soap containing a cationic-polyol complex and its preparation method. By constructing a cationic-polyol complex, the cationic softener is pre-integrated into a stable structure and then introduced into the soap base, thereby effectively improving the compatibility and storage stability of the cationic and soap base, as well as ensuring efficient release during washing, thus achieving a long-lasting and stable softening function of the laundry soap.

[0005] The objective of this invention is achieved through the following technical solution: In a first aspect, the present invention provides a softening laundry soap containing a cationic-polyol complex, comprising the following components by mass percentage: soap granules: 92-98%; cationic-polyol complex: 2-5%; fragrance: 0.3-1%; other additives: 0.1-2%; wherein the cationic-polyol complex is prepared by shearing emulsification and cooling of a cationic surfactant, a polyol, and water; and the mass ratio of the cationic surfactant to the polyol is 1:2-4.

[0006] In the cationic-polyol complex, the polyol forms a strong hydrogen bond network with water molecules through hydrogen bonding and solvation during the pre-composite process. This creates a local microenvironment around the cation, forming a dynamic "hydrophilic protective shell" that encapsulates the active cationic center. Water molecules act as "bridge" molecules, forming a hydrogen bond network with the polyol's hydroxyl groups and cationic head groups, enhancing the stability of the composite system. They also reduce the system's viscosity, improve dispersibility, promote the formation of a lamellar liquid crystal phase, and result in a more regular micelle structure.

[0007] During the soap base mixing stage, this protective shell physically isolates the cations from direct contact with the sodium fatty acid anions, fundamentally preventing system damage caused by charge neutralization. Simultaneously, this hydrophilic protective shell, composed of numerous hydroxyl groups, forms an extensive hydrogen bond network with the polar heads of the soap molecules, physically anchoring the complex within the three-dimensional structure of the soap. This effectively buffers the impact of the external alkaline environment on the internal cations, ensuring the quaternary ammonium cations remain in a relatively stable chemical state during soap storage. This prevents hydrolytic deactivation caused by direct exposure to high pH environments and also prevents migration, aggregation, or phase separation during storage, ensuring long-term product stability.

[0008] During the washing process, a large number of water molecules rush in, rapidly disrupting the hydrogen bond network and dissolving the hydrophilic polyol shell, allowing the encapsulated cationic surfactant to be released quickly and completely into the washing liquid. Because the released cations are highly active and undamaged, they can immediately and efficiently adsorb onto the negatively charged fabric fiber surface through electrostatic interaction, forming a softening film, thus achieving an immediate and significant softening effect.

[0009] Preferably, the shear emulsification temperature is 55~65℃, the rotation speed is 2000~4000 rpm, and the time is 15~25 min; more preferably, the shear emulsification temperature is 58~62℃, the rotation speed is 3000~3500 rpm, and the time is 18~22 min; the particle size D50 of the emulsion after shear emulsification is 200-500 nm.

[0010] Preferably, the cationic surfactant is at least one of dioctadecyl dimethyl ammonium chloride (D1821), behenyltrimethyl ammonium chloride, and ester-based quaternary ammonium salt (TEP-90A).

[0011] Preferably, the polyol is at least one of glycerol, sorbitol and dipropylene glycol.

[0012] Glycerin molecules are small and contain three highly reactive hydroxyl groups. The high density of hydroxyl groups and extremely high water solubility allow them to rapidly form a dense hydrogen bond network with water molecules and cationic head groups, creating a tight, dynamic hydrophilic protective shell around the cationic surfactant. The small molecule exhibits excellent penetration and encapsulation properties, efficiently organizing the layered liquid crystal micelle structure and reducing system viscosity. Simultaneously, it readily forms hydrogen bond anchoring sites with the polar head of soap molecules, buffering the soap in highly alkaline environments, resulting in good storage stability. Upon washing, it readily dissolves in water, releasing cationic compounds and exhibiting a rapid softening response.

[0013] Sorbitol contains six hydroxyl groups, has a large molecular weight, long carbon chain, and more hydrogen bond cross-linking sites. This allows it to penetrate the three-dimensional structure of the soap and form strong multi-point hydrogen bond anchoring, without creating excessive steric hindrance due to its long chain. This prevents molecular entanglement and aggregation during shear emulsification, hindering the formation of a homogeneous emulsion and resulting in slow cationic release and diminished immediate smoothing effect. Furthermore, sorbitol has good water solubility, readily using water molecules as "bridges" to build hydrogen bond networks, promoting the formation of lamellar liquid crystal phases, regulating micelle structure, reducing system viscosity, and improving complex dispersibility. It also exhibits strong chemical stability and enhanced alkali buffering capacity, making it suitable for improving long-term product storage stability and inhibiting cationic migration, aggregation, and phase separation.

[0014] Dipropylene glycol contains hydroxyl and ether bonds, exhibiting both hydrophilicity and weak hydrophobicity, along with high molecular flexibility. The hydroxyl groups participate in constructing a hydrogen-bonded protective shell, and the hydrophobic carbon chain can match the hydrophobic tails of cationic surfactants, resulting in superior system compatibility. The flexible molecule forms a dynamic and reversible hydrogen bond network, ensuring structural stability during storage and rapid dissociation upon contact with water during washing. The ether bonds provide enhanced alkali resistance, resisting degradation in the high pH environment of the soap, providing long-term protection against cationic hydrolysis, and improving the compatibility of the complex with soap particles, preventing phase separation.

[0015] Preferably, the amount of water added is 0.25 to 0.5 times the mass of the cationic surfactant; the amount of water added is 5 to 15% of the mass of the cationic-polyol complex; more preferably, the amount of water added is 8 to 12% of the mass of the cationic-polyol complex.

[0016] Preferably, the other additives include at least one of pigments, metal ion chelators, antioxidants, and fillers.

[0017] Preferably, the metal ion chelating agent includes at least one of sodium citrate and tetrasodium ethylenediaminetetraacetate.

[0018] Preferably, the antioxidant includes butylated hydroxytoluene (BHT).

[0019] Preferably, the filler comprises calcium carbonate.

[0020] Secondly, the present invention also provides a method for preparing a softening laundry soap containing a cationic-polyol complex, comprising the following steps: S1. Vacuum dry the soap granules to a moisture content of 20-25%, and then extrude and cut them into granules; S2. Stir the soap granules, fragrance, and other additives until they are evenly mixed. S3. Add the cationic-polyol complex and continue stirring until the mixture is homogeneous; S4. The resulting mixture is refined, three-roll milled, vacuum extruded, and finally rolled, cut into pieces and packaged.

[0021] Preferably, the particle size of the extruded pellets is controlled between 0.5 and 1.0 cm.

[0022] Preferably, the stirring is carried out at room temperature for 3-5 minutes.

[0023] Preferably, the temperature for continued stirring is 35~40℃ and the time is 5~10min.

[0024] Preferably, the three-roll mill has a gap of ≤0.5mm and a roll surface temperature of <45℃.

[0025] Compared with the prior art, the present invention has the following beneficial effects: (1) Excellent compatibility: The soap has a uniform and dense texture, without cracking or softening. After accelerated aging test (40℃, RH75%, 90 days), the soap structure is intact, without water leakage, deformation, cracking, etc. (2) High cationic release rate and activity retention: The bromophenol blue spectrophotometric method was used to determine that the cationic active ingredient release rate of the laundry soap of the present invention was ≥88% under standard washing conditions. After accelerated aging at 40℃ / RH75% for 90 days, the cationic activity retention rate was ≥80%. According to the Arrhenius empirical formula, accelerated aging at 40℃ / 90 days is equivalent to about 24 months of storage at room temperature (25℃), indicating that the softening function of the product is stable during the shelf life. (3) Long-lasting softening function: According to GB / T 18318-2021 "Sensory test method for determination of softness of textiles", a professional sensory evaluation team conducted a blind evaluation (out of 10) on a standard pure cotton fabric after washing. The product of this invention scored consistently between 7.5 and 8.8 points, while ordinary laundry soap scored only 4.2 to 5.5 points. After the same pure cotton fabric was washed 20 times, the softness score could still maintain more than 75% of the initial level, proving that the softening effect is long-lasting. (4) Simple process: No special equipment or lengthy curing cycle is required throughout the process, and continuous and stable production can be achieved using existing soap production lines. Detailed Implementation

[0026] The technical solution of the present invention will be illustrated below with specific embodiments, but the scope of protection of the present invention is not limited thereto.

[0027] Test method: (1) Determination of cationic detergent release rate: The content of cationic surfactants in the detergent solution was determined by bromophenol blue spectrophotometry. The specific operation is as follows: Weigh 3g of the laundry soap to be tested, dissolve it in 250 ppm hard water at a bath ratio of 3:1000 (g / mL), and wash at 30℃ for 10 min with stirring. After filtration, take 10 mL of the filtrate, add 2 mL of bromophenol blue indicator solution (0.04%) and 5 mL of citrate-disodium hydrogen phosphate buffer (pH=7.2), shake well, add 10 mL of chloroform, shake vigorously for 2 min, let stand for layering, take the organic phase, and measure the absorbance at a wavelength of 605 nm. Calculate the cation concentration in the detergent solution according to the standard curve, and calculate the release rate according to the formula: Release rate (%) = (mass of cations measured in the detergent solution / total theoretical cation mass in the soap) × 100%.

[0028] (2) Softness test: Refer to GB / T 18318-2021 "Sensory test of softness of textiles", a professional evaluation group of 5 people conducted a blind evaluation (10 points) on the washed pure cotton standard fabric and took the average value.

[0029] (3) Soap stability: The sample was placed in a constant temperature and humidity chamber at (40±2)℃ and 75% relative humidity for 90 days to accelerate storage. The appearance, hardness and whether cracking, water leakage, deformation and other phenomena were observed were observed.

[0030] (4) Determination of detergency: The determination of detergency and recycle performance of detergents for clothing was carried out in accordance with GB / T 13174-2021. The detergency ratio was calculated based on the detergency result of Diaopai transparent soap charcoal black cloth (ratio 1.00).

[0031] (5) Determination of cationic activity retention rate: Referring to the determination method of quaternary ammonium salt active ingredients (GB / T 5174-2004 "Cationic Surfactants Direct Two-Phase Titration Method"), the cationic activity content of the laundry soap was determined at the initial stage and after 90 days of accelerated aging at 40℃ / RH75%. The retention rate was calculated according to the formula: Retention rate (%) = (content after aging / initial content) × 100%. The retention rate directly reflects the storage stability of cationic components in the alkaline environment of the soap. Based on the Arrhenius empirical formula, with Q10 = 2.5, the accelerated aging at 40℃ / 90 days is equivalent to about 24 months of storage at room temperature (25℃), which can effectively predict the stability of the softening function within the shelf life.

[0032] Preparation of cationic-polyol complexes PQ-1~PQ-7 and PQ-9: Cationic surfactants and polyols were mixed at a certain mass ratio, and deionized water was added as a co-solvent. The mixture was heated to a certain temperature for shear emulsification at a speed of 3200 rpm for 20 min to form a uniform composite micelle system. After cooling to room temperature, a translucent to milky white paste-like composite was obtained.

[0033] Preparation of cationic-polyol complex PQ-8: Cationic surfactants and polyols were mixed at a certain mass ratio and heated to a certain temperature for shear emulsification at a speed of 3200 rpm for 20 min to form a uniform composite micelle system. After cooling to room temperature, a translucent to milky white paste-like composite was obtained.

[0034] Examples 1-5

[0035] S1. Vacuum dry the soap granules to a moisture content of 20-25%, then extrude and cut them into granules with a particle size controlled at 0.5-1.0 cm. S2. Stir the soap granules, fragrance, and chelating agent at room temperature until they are evenly mixed, for 5 minutes. S3. Add the cationic-polyol complex and continue stirring at 35°C until the mixture is homogeneous, for 10 minutes. S4. The resulting mixture is passed sequentially through a refining machine, a three-roll mill (roll gap ≤ 0.5 mm, roll surface temperature < 45℃), a vacuum extruder, and finally rolled, cut into pieces and packaged.

[0036] Comparative Example 1 (existing technical solution, refer to CN107446732A, the formula does not contain cationic surfactants, but adds AEO-9 nonionic surfactants) S1. Vacuum dry the soap granules to a moisture content of 20-25%, then extrude and cut them into granules with a particle size controlled at 0.5-1.0 cm. S2. Stir the soap granules, fragrance, and chelating agent at room temperature until they are evenly mixed, for 5 minutes. S3. Add AEO-9 and continue stirring at 35℃ until the mixture is homogeneous, which takes 10 minutes. S4. The resulting mixture is passed sequentially through a refining machine, a three-roll mill (roll gap ≤ 0.5 mm, roll surface temperature < 45℃), a vacuum extruder, and finally rolled, cut into pieces and packaged.

[0037] Comparative Example 2 Commercially available Diaopai transparent soap (ordinary laundry soap, without fabric softening properties).

[0038] Comparative Example 3 S1. Vacuum dry the soap granules to a moisture content of 20-25%, then extrude and cut them into granules with a particle size controlled at 0.5-1.0 cm. S2. Stir the soap granules, fragrance, and chelating agent at room temperature until they are evenly mixed, for 5 minutes. S3. Add dioctadecyl dimethyl ammonium chloride (D1821) and glycerol in a mass ratio of 1:3, and continue stirring at 35°C until the mixture is homogeneous for 10 minutes. S4. The resulting mixture is passed sequentially through a refining machine, a three-roll mill (roll gap ≤ 0.5 mm, roll surface temperature < 45℃), a vacuum extruder, and finally rolled, cut into pieces and packaged.

[0039] Comparative Examples 4-8 S1. Vacuum dry the soap granules to a moisture content of 20-25%, then extrude and cut them into granules with a particle size controlled at 0.5-1.0 cm. S2. Stir the soap granules, fragrance, and chelating agent at room temperature until they are evenly mixed, for 5 minutes. S3. Add the cationic-polyol complex and continue stirring at 35°C until the mixture is homogeneous, for 10 minutes. S4. The resulting mixture is passed sequentially through a refining machine, a three-roll mill (roll gap ≤ 0.5 mm, roll surface temperature < 45℃), a vacuum extruder, and finally rolled, cut into pieces and packaged.

[0040] Table 1. Composition of cationic-polyol complexes Table 2. Formulation composition of laundry soaps in Examples 1-5 Table 3. Formulation composition of laundry soaps in Comparative Examples 1-8 Performance test results Table 1 shows the composition of cationic-polyol complexes PQ-1 to PQ-9. Tables 2 and 3 show the composition of laundry soap formulations of Examples 1-5 and Comparative Examples 1-8. The laundry soaps obtained in Examples 1-5 and Comparative Examples 1-8 were tested for performance according to the test methods described above, and the results are summarized in Tables 4 and 5.

[0041] Table 4 Performance test results of Examples 1-5 Table 5 Performance test results of Comparative Examples 1-8 Results analysis: (1) Advantages compared with existing technologies: As shown in Tables 4 and 5, compared with existing technologies (Comparative Examples 1-2), the present invention demonstrates a significant advantage in softening effect (sensory score), proving that the function achieved through cationic compounds far surpasses the solution that improves hand feel solely through surfactant compounding. The detergency of Examples 1-5 in the present invention remains at a high level (≥0.94), indicating that the present invention retains the core cleaning properties of laundry soap while adding a powerful softening function. Comparative Example 1 has a slightly higher detergency (1.02) because it does not contain cationic components, but lacks softening function, demonstrating the functional balance of the present invention.

[0042] (2) The key role of pre-composite treatment: In this invention, Examples 1-5 are significantly better than Comparative Example 3 (direct addition of cationic surfactant and polyol) in terms of soap stability, cationic release rate and softness score, indicating that "pre-composite treatment" is the key technical feature of this invention. In addition, comparing Example 1 with Comparative Example 4, it can be seen that the addition of water during the pre-composite treatment can form a good synergistic effect with polyol, enhance the stability of the composite system, promote the formation of layered liquid crystal phase, make the micelle structure more regular, and thus have a higher cationic activity retention rate.

[0043] The ratio of cationic surfactants and polyols, as well as the shear emulsification temperature, in the pre-composite process all affect the pre-composite effect. Comparing Example 5 with Comparative Examples 6-7, it can be seen that Comparative Examples 6-7 used complexes (PQ-5 and PQ-6) exceeding the preferred mass ratio range of this invention. In Comparative Example 6, insufficient polyol prevented the formation of a complete protective shell, resulting in a significant decrease in soap stability and softening effect. In Comparative Example 7, excessive polyol led to a loose protective shell structure, increased system viscosity, and damaged the soap's solidified structure, causing the laundry soap to easily absorb moisture and soften. Furthermore, excessive polyol diluted the effective cationic content, further reducing softening performance. Comparing Example 1 with Comparative Example 5, it can be seen that in Comparative Example 5, the excessively high shear emulsification temperature in the pre-composite process caused demulsification of the complex. The resulting non-homogeneous system could not be uniformly mixed with the soap particles, leading to localized enrichment and complete failure of material compatibility. The soap was prone to white spots, white patches, streaks, localized softening, and the precipitation of oily substances; therefore, its performance was comparable to or even worse than that of Comparative Example 3 with direct addition.

[0044] The "hydrophilic protective shell" constructed by the polyol-water hydrogen bond network effectively blocks the damage of cations by the alkaline environment of the soap, overcoming the technical challenge of pH incompatibility between quaternary ammonium salt cations and soap base. Based on the Arrhenius empirical formula, accelerated aging at 40℃ for 90 days is equivalent to approximately 24 months of storage at room temperature (25℃), indicating that the product's softening function remains stable and reliable within its shelf life.

[0045] (3) Influence of Polyol Type: Comparing Example 5 with Comparative Example 8, it can be seen that the present invention can form a better synergistic effect with cationic surfactants by selecting specific types of polyols. However, Comparative Example 8 used a PQ-9 complex prepared with propylene glycol (not a polyol limited to the present invention), and the resulting soap was in a paste state after accelerated aging, with low cationic release rate and activity retention rate. This is because propylene glycol contains only two hydroxyl groups and cannot form a sufficiently strong and dense hydrogen bond network with cationic surfactants and water, resulting in a loose "hydrophilic protective shell" structure that cannot effectively block the alkaline environment of the soap and protect the cationic active center. At the same time, propylene glycol cannot induce the formation of a regular layered liquid crystal phase, and the micelle encapsulation ability is weak. Quaternary ammonium cations are directly exposed to the alkaline environment, rapidly hydrolyze and deactivate, and the softening function fails prematurely. The complex has poor dispersibility in the soap base and cannot anchor the complex in the soap structure. During storage, the cations are very easy to migrate, precipitate, turn white, and separate.

[0046] In summary, this invention successfully solves the problem of incompatibility between cationic and soap bases by constructing a cationic-polyol complex, achieving long-lasting and stable softening function in laundry soap. Moreover, the process is simple and suitable for industrial production.

[0047] The above are merely preferred embodiments of the present invention and do not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made using the present invention specification, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A softening laundry soap containing a cationic-polyol complex, characterized in that, It includes the following components by mass percentage: Soap granules: 92~98%; Cationic-polyol complex: 2~5%; Fragrance: 0.3~1%; Other additives: 0.1~2%; The cationic-polyol complex is prepared by shearing emulsification and cooling of cationic surfactant, polyol and water; the mass ratio of cationic surfactant to polyol is 1:2~4.

2. The softening laundry soap containing a cationic-polyol complex according to claim 1, characterized in that, The cationic surfactant is at least one of dioctadecyl dimethyl ammonium chloride, behenyltrimethyl ammonium chloride, and ester-based quaternary ammonium salt; the polyol is at least one of glycerol, sorbitol, and dipropylene glycol.

3. The softening laundry soap containing a cationic-polyol complex according to claim 1, characterized in that, The shear emulsification process is carried out at a temperature of 55-65°C, a rotation speed of 2000-4000 rpm, and a time of 15-25 min.

4. The softening laundry soap containing a cationic-polyol complex according to claim 1, 2, or 3, characterized in that, The amount of water added is 0.25 to 0.5 times the mass of the cationic surfactant; the amount of water added is 5 to 15% of the mass of the cationic-polyol complex.

5. The softening laundry soap containing a cationic-polyol complex according to claim 1, characterized in that, The other additives include at least one of pigments, metal ion chelators, antioxidants, and fillers.

6. The softening laundry soap containing a cationic-polyol complex according to claim 5, characterized in that, The metal ion chelating agent includes at least one of sodium citrate and tetrasodium ethylenediaminetetraacetate.

7. The softening laundry soap containing a cationic-polyol complex according to claim 5 or 6, characterized in that, The antioxidant includes butylated hydroxytoluene.

8. The softening laundry soap containing a cationic-polyol complex according to claim 5 or 6, characterized in that, The filler includes calcium carbonate.

9. A method for preparing a softening laundry soap containing a cationic-polyol complex as described in any one of claims 1-8, characterized in that, Includes the following steps: S1. Vacuum dry the soap granules to a moisture content of 20-25%, and then extrude and cut them into granules; S2. Stir the soap granules, fragrance, and other additives until they are evenly mixed. S3. Add the cationic-polyol complex and continue stirring until the mixture is homogeneous; S4. The resulting mixture is refined, three-roll milled, vacuum extruded, and finally rolled, cut into pieces and packaged.

10. The preparation method according to claim 9, characterized in that, The particle size of the extruded pellets is controlled at 0.5~1.0cm; the temperature of the continued stirring is 35~40℃, and the time is 5~10min.

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