Highly active dilutable self-thickening laundry liquid concentrate and method of making same

Abstract

The present application relates to the technical field of daily chemical industry, disclose a kind of high-activity dilutable self-thickening concentrated laundry liquid and its preparation method, according to the total mass of concentrated laundry liquid 100%, the concentrated laundry liquid includes: 75-90% active material, 0.15-1% hydrogenated castor oil and water;Wherein, active material includes the following components: 10-40% anionic surfactant, 30-50% non-ionic surfactant, 5-10% polyethylene glycol double fatty acid ester, 0-10% the EO number is 2-5 fatty alcohol polyoxyethylene ether, 1-5% fatty acid.The concentrated laundry liquid with high active material content can maintain good fluidity at room temperature by specific component compounding, and it is very stable after long-term observation, i.e. not stratified and not precipitated.And it can still maintain relatively high viscosity after dilution by 6-8 times, without adding any thickening agent.

Description

Technical Field

[0001] This invention relates to the technical field of daily chemical products, and in particular to a highly active, dilutable, self-thickening concentrated laundry detergent and its preparation method. Background Technology

[0002] Compared to regular detergents, concentrated detergents are more environmentally friendly in terms of production, packaging, transportation, storage, and use. Promoting detergent concentration has become an important direction for high-quality development in the industry. From a consumer psychology perspective, there is a close relationship between the viscosity of liquid detergents and consumers' perception of product quality. Studies show that consumers often subjectively associate the viscosity of detergent products with the content of active ingredients, believing that products with a certain viscosity are "reliable." However, existing concentrated laundry detergent products generally have shortcomings in controlling viscosity after dilution. On the one hand, highly concentrated detergents usually appear as low-viscosity, fast-dissolving liquids, and the viscosity is often even lower after dilution. This is because when the active ingredient content is significantly increased, the concentration of surfactants in the formula increases sharply, and the system often exhibits low-viscosity fluid characteristics. When consumers dilute the product to the active ingredient content of regular laundry detergent according to the usual dosage, the viscosity of the diluted solution decreases further, creating a significant gap between consumers' psychological expectations of the "ideal viscosity" of laundry detergent. On the other hand, some companies add large amounts of solubilizers or water-soluble growth promoters such as sodium xylenesulfonate, ethanol, and propylene glycol to reduce the viscosity of the original solution in order to overcome the gelation problem caused by high-concentration formulas. While these additives can improve the fluidity of the concentrate, they do not have a positive effect on viscosity control after dilution. Instead, they increase product costs and do not substantially improve washing performance.

[0003] Therefore, existing concentrated laundry detergent products have significant shortcomings in viscosity control after dilution. Developing a super-concentrated laundry detergent concentrate with high active ingredient content and adjustable viscosity after dilution—where the system viscosity can be flexibly adjusted according to consumer needs or different usage scenarios—is not only an important direction for the concentration development of the detergent industry, but also has urgent market demand and significant technological innovation value.

[0004] However, the main technical difficulties are as follows: 1. When the content of active ingredients exceeds a certain threshold, the formulation system is prone to gelation. Traditional anionic surfactants such as linear alkylbenzene sulfonate (LAS) and sodium fatty alcohol polyoxyethylene ether sulfate (AES) have limited solubility at room temperature (usually not exceeding 30%). Although nonionic surfactants such as fatty alcohol polyoxyethylene ether (AEO) have higher solubility, they are very easy to form non-flowing gels at high concentrations. At the same time, nonionic surfactants have excellent viscosity-reducing effects, which makes thickening after dilution more difficult. 2. High-activity formulas also face the problem of poor high and low temperature stability - they are prone to precipitation and stratification at low temperatures, and phase separation may occur at high temperatures. How to effectively solve the high and low temperature stability of the formula is the core technical challenge in the research and development of concentrated laundry detergent. 3. In order to achieve the effect of thickening after dilution, it is inevitable to add functional thickening raw materials to the formula. This further increases the instability of the high-activity formula system. The liquid may separate and precipitate in just a few hours, and even gelation may occur during the sampling process. Therefore, it can be said to be even more difficult.

[0005] Patent CN 117384712 B discloses a weakly acidic, alcohol-free solvent-based concentrated detergent and its preparation method. It uses fatty acids and polyethylene glycol fatty acid esters for thickening, resulting in a concentrated laundry detergent with an active ingredient content of 40-70%, exhibiting high viscosity after dilution 4-5 times. However, the patent also mentions that dilution 2-3 times is common, but dilution 4-5 times is more difficult, making it even more challenging to maintain high viscosity after dilution 6-8 times. Furthermore, to increase the active ingredient content while maintaining good fluidity at room temperature, most of the added active ingredients must be non-ionic, as non-ionic substances have excellent viscosity-reducing effects, further increasing the difficulty of thickening. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides a highly active, dilutable, self-thickening concentrated laundry detergent and its preparation method. By using a synergistic blend of fatty acids, polyethylene glycol difatty acid esters, and fatty alcohol polyoxyethylene ethers with an EO number of 2-5 as thickening components, and adding hydrogenated castor oil as a stabilizing component, the concentrated laundry detergent with a high active ingredient content (75-85%) maintains good fluidity at room temperature and exhibits excellent stability over long-term testing, meaning it does not separate or settle. Furthermore, even after dilution 6-8 times, it maintains a high viscosity (viscosity > 200 mPa·s) without the need for any additional thickeners.

[0007] The objective of this invention is achieved through the following technical solution: In a first aspect, the present invention provides a highly active, dilutable, self-thickening concentrated laundry detergent, wherein, based on 100% of the total mass of the concentrated laundry detergent, the concentrated laundry detergent comprises: 75-90% active ingredient, 0.15-1% hydrogenated castor oil, and water; wherein the active ingredient comprises the following components: 10-40% anionic surfactants, 30-50% nonionic surfactant, 5-10% polyethylene glycol difatty acid ester, 0-10% fatty alcohol polyoxyethylene ethers with an EO number of 2-5 1-5% fatty acids; The nonionic surfactants do not include fatty alcohol polyoxyethylene ethers with an EO number of 2-5.

[0008] The thickening components used in this invention include fatty acids and polyethylene glycol difatty acid esters. The thickening mechanism of this combination is that when the molecular weight of the polyethylene glycol chain is large, the compound exhibits the characteristics of a high molecular weight compound. The ether bonds (-O-) on the long chains of polyethylene glycol difatty acid esters can bind a large number of water molecules through hydrogen bonds, forming a large hydration layer, which then interweaves into a three-dimensional network structure, encapsulating surfactant micelles and making the overall structure thick. Fatty acid molecules can insert into the micelles formed by the surfactant, changing the curvature of the micelles and promoting their transformation from spherical to rod-shaped (worm-like) structures. Longer micelles are more likely to entangle with each other, thus significantly increasing viscosity. At the same time, fatty acids themselves can also participate in and strengthen the gel or hydration network constructed by polyethylene glycol difatty acid esters, acting as a "crosslinking agent" or "structural reinforcing agent," making the overall structure more stable and thicker. This combination can indeed increase viscosity; self-thickening can be achieved by diluting 4-5 times with the same active ingredient content, but it is far from sufficient to maintain a high viscosity when diluted 6-7 times.

[0009] Furthermore, the inventors discovered that in concentrated systems with higher active ingredient content, the water content is already very low, and fatty acids have very low solubility in water. High concentrations of fatty acids exceed the system's stability capacity, easily leading to precipitation and stratification. In addition, thickeners such as polyethylene glycol dicarboxylic acid esters, when used in high amounts, can easily cause excessive gelation or a "jelly-like" texture in certain areas of the system. This uneven gel structure manifests macroscopically as stratification. Therefore, if additional fatty acids and polyethylene glycol dicarboxylic acid esters are added to achieve self-thickening at higher dilution ratios, the system's solubility limit is exceeded, causing some components to fail to be stably "encapsulated" in micelles. This results in the undispersed components precipitating out when the system's "accommodation" capacity reaches its limit, forming visible sediment or stratification. Therefore, this invention incorporates hydrogenated castor oil into the composition to disperse and suspend the system. The three-dimensional network structure formed by the self-assembly of hydrogenated castor oil during system cooling "locks" insoluble particles within it, thus resisting sedimentation or buoyancy caused by gravity and achieving a stable system.

[0010] Meanwhile, the inventors also discovered that if only polyethylene glycol difatty acid esters and fatty acids are used as thickeners in the composition, more polyethylene glycol difatty acid esters and fatty acids need to be added to the composition to achieve a high dilution ratio. The suspension effect of hydrogenated castor oil deteriorates with the increase of these two raw material contents. This may be because, due to the highly concentrated system, the three-dimensional network space formed by hydrogenated castor oil is limited, and even with increased addition, a superior suspension effect cannot be achieved, leading to stratification and sedimentation of the liquid. This invention improves thickening efficiency by adding fatty alcohol polyoxyethylene ethers with an EO number of 2-5 to synergistically thicken the fatty acids and polyethylene glycol difatty acid esters. This achieves a higher dilution self-thickening effect while stabilizing the appearance of the liquid, resulting in a 1+1+1>3 effect.

[0011] The significant synergistic thickening effect of fatty alcohol polyoxyethylene ethers lies in their unique structure with an EO addition number of 2-5. This structure provides them with a perfect balance of hydrophilicity and lipophilicity. The long-chain structure of fatty alcohol polyoxyethylene ethers with an EO number of 2-5 can be embedded in the gel network constructed from polyethylene glycol difatty acid esters, acting as a crosslinking agent or network filler. It can more tightly connect different components in the network through intermolecular forces (such as hydrophobic interactions and hydrogen bonds), making the entire three-dimensional network structure more stable and larger, thereby binding more water and micelles and significantly increasing viscosity. Therefore, the addition of fatty alcohol polyoxyethylene ethers with an EO number of 2-5 deeply synergistically amplifies the original thickening effect of fatty acids and polyethylene glycol difatty acid esters through multiple mechanisms, including optimizing the mixed micelle morphology, reinforcing the three-dimensional network structure, and enhancing the system's hydration capacity. Ultimately, this results in a significant increase in viscosity after dilution of the composition by 6-8 times, and both the detergent solution before and after dilution have passed long-term stability tests.

[0012] Preferably, the total mass percentage of the polyethylene glycol difatty acid ester and fatty acids is ≤12%; and the mass percentage of the hydrogenated castor oil is ≥1.5% of the total mass percentage of the polyethylene glycol difatty acid ester and fatty acids.

[0013] Preferably, the concentrated laundry detergent comprises, based on a total mass of 100%, 75-90% active ingredients, 0.15-0.5% hydrogenated castor oil, and water.

[0014] Preferably, based on 100% of the total mass of the concentrated laundry detergent, the active ingredients include the following components by mass percentage: 10-40% anionic surfactant; 30-50% nonionic surfactant; 5-10% polyethylene glycol difatty acid ester; 3-10% fatty alcohol polyoxyethylene ether with an EO number of 2-5; and 1-5% fatty acids.

[0015] Under these mixing conditions, the laundry detergent can still maintain a high viscosity (viscosity > 200 mPa·s) after being diluted 7-8 times.

[0016] Preferably, the fatty alcohol polyoxyethylene ether with an EO number of 2-5 has 8-12 carbon atoms.

[0017] Preferably, the nonionic surfactant is a polyoxyethylene type nonionic surfactant; the nonionic surfactant is selected from one or more of linear fatty alcohol polyoxyethylene ethers, branched fatty alcohol polyoxyethylene ethers, isomeric fatty alcohol polyoxyethylene ethers, and modified oil ethoxylates (obtained by ethoxylation modification of natural oils as raw materials).

[0018] Preferably, the anionic surfactant is selected from one or more of the following: sodium fatty alcohol polyether sulfate, sodium alkylbenzene sulfonate, sodium fatty alcohol sulfate, sodium fatty alcohol polyether carboxylate, modified oil ethoxylate sulfonate, sodium fatty acyl glutamate, sodium fatty acyl glycine, sodium fatty acyl sarcosine, sodium fatty acyl alanine, and sodium fatty acyl taurate.

[0019] Preferably, the fatty acid has 8-22 carbon atoms.

[0020] Preferably, the fatty acid is a natural fatty acid or a mixture of fatty acids from natural sources; the natural fatty acid is selected from lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, etc.; the mixture of fatty acids from natural sources is selected from arachidic acid, palm kernel oil, coconut oil oil, etc.

[0021] Preferably, the polyethylene glycol difatty acid ester is synthesized by esterification of polyethylene glycol with two saturated or unsaturated natural fatty acids having ≥16 carbon atoms. The polyethylene glycol difatty acid ester is selected from common commercially available polyethylene glycol difatty acid ester raw materials, such as polyethylene glycol 6000 distearate.

[0022] Preferably, the polyethylene glycol is selected from one or more polyethylene glycols with an average molecular weight of 400-20000. The polyethylene glycol is selected from PEG400, PEG800, PEG6000, PEG20000, etc.

[0023] Preferably, the concentrated laundry detergent further includes 0-5 wt% of an alkalinity regulator; the alkalinity regulator includes one or more of sodium hydroxide, potassium hydroxide, sodium carbonate, and potassium carbonate.

[0024] Preferably, the concentrated laundry detergent also includes 0-5 wt% of other functional additives; the other functional additives include one or more of enzyme preparations, color protectants, antibacterial agents, fabric softeners, anti-redeposition agents, chelating agents, and preservatives.

[0025] Preferably, the concentrated laundry detergent has a pH of 6.0-8.0.

[0026] Preferably, the concentrated laundry detergent has a maximum dilution ratio of 8 times, and the viscosity of the diluted solution is >200 mPa·s.

[0027] Preferably, the concentrated laundry detergent is diluted by adding water to obtain a diluted solution.

[0028] Preferably, the diluent can be used directly.

[0029] Preferably, the mass ratio of the water to the concentrated laundry detergent is ≤8.

[0030] Preferably, the mass of the water is 6-8 times the mass of the concentrated laundry detergent.

[0031] Preferably, the mass of the water is 7-8 times the mass of the concentrated laundry detergent.

[0032] Secondly, the present invention also provides a method for preparing a highly active, dilutable, self-thickening concentrated laundry detergent, comprising the following steps: S1: Add water, nonionic surfactant, and fatty alcohol polyoxyethylene ether with an EO number of 2-5 to the container; S2: Add fatty acids and anionic surfactants to the container and stir until homogeneous; S3: Raise the temperature of the liquid to 80-90℃, add hydrogenated castor oil and stir well; S4: Reduce the temperature of the liquid to 55-65℃, add polyethylene glycol difatty acid ester and stir until homogeneous.

[0033] Preferably, the method for preparing the concentrated laundry detergent includes the following steps: S1: Add water, nonionic surfactant, and fatty alcohol polyoxyethylene ether with an EO number of 2-5 to the container; S2: Add fatty acids, alkalinity regulator and anionic surfactant to the container and stir until homogeneous; S3: Raise the temperature of the liquid to 80-90℃, add hydrogenated castor oil and stir well; S4: Reduce the temperature of the liquid to 55-65℃, add polyethylene glycol difatty acid ester and other functional additives, and stir evenly.

[0034] Compared with the prior art, the present invention has the following beneficial effects: (1) By using fatty acids, polyethylene glycol difatty acid esters and fatty alcohol polyoxyethylene ethers with EO number of 2-5 as thickening components, and by adding hydrogenated castor oil as stabilizing components, the concentrated laundry detergent with high active ingredient content (75-85%) maintains good fluidity at room temperature. After long-term observation, it is very stable, that is, it does not separate or precipitate. (2) This concentrated laundry detergent can be diluted to different ratios according to actual needs and can thicken itself. It can be diluted up to 6-8 times to achieve self-thickening without adding any thickener. It can still maintain a high viscosity (viscosity > 200 mpa·s). The operation method is very simple. At the same time, the diluted laundry detergent has been observed to be very stable over a long period of time, that is, it does not separate into layers or precipitate. Detailed Implementation

[0035] 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.

[0036] Based on 100% of the total mass of concentrated laundry detergent, the highly active dilutable self-thickening concentrated laundry detergent of this invention comprises: 75-90% active ingredients, 0.15-1% hydrogenated castor oil, 0-5 wt% alkalinity regulator, 0-5 wt% other functional additives, and water; wherein, the active ingredients comprise the following components: 10-40% anionic surfactant, 30-50% nonionic surfactant, 5-10% polyethylene glycol difatty acid ester, 0-10% fatty alcohol polyoxyethylene ether with an EO number of 2-5, and 1-5% fatty acids.

[0037] In a specific embodiment of the present invention, the anionic surfactant is selected from one or more of the following: sodium fatty alcohol polyether sulfate, sodium alkylbenzene sulfonate, sodium fatty alcohol sulfate, sodium fatty alcohol polyether carboxylate, modified oil ethoxylate sulfonate, sodium fatty acyl glutamate, sodium fatty acyl glycine, sodium fatty acyl sarcosine, sodium fatty acyl alanine, and sodium fatty acyl taurate.

[0038] In a specific embodiment of the present invention, the nonionic surfactant is a polyoxyethylene type nonionic surfactant. The nonionic surfactant is selected from one or more of the following: linear fatty alcohol polyoxyethylene ether, branched fatty alcohol polyoxyethylene ether, isomeric fatty alcohol polyoxyethylene ether, and modified oil ethoxylates (obtained by ethoxylation modification of natural oils as raw materials).

[0039] In a specific embodiment of the present invention, the polyethylene glycol difatty acid ester is synthesized by esterification of polyethylene glycol with two saturated or unsaturated natural fatty acids having ≥16 carbon atoms. The polyethylene glycol is selected from one or more polyethylene glycols with an average molecular weight of 400-20000, specifically PEG400, PEG800, PEG6000, PEG20000, etc. The fatty acids are natural fatty acids or naturally sourced mixed fatty acids. Natural fatty acids are selected from lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, etc.; naturally sourced mixed fatty acids are selected from arachidic acid, palm kernel oil acid, coconut oil acid, etc.

[0040] In a specific embodiment of the present invention, the fatty alcohol polyoxyethylene ether with an EO number of 2-5 has 8-12 carbon atoms. The fatty acid has 8-22 carbon atoms.

[0041] In specific embodiments of the present invention, the alkalinity regulator includes one or more of sodium hydroxide, potassium hydroxide, sodium carbonate, and potassium carbonate. Other functional additives include one or more of enzyme preparations, color-protecting agents, antibacterial agents, softeners, anti-redeposition agents, chelating agents, and preservatives.

[0042] The method for preparing concentrated laundry detergent in this invention includes the following steps: S1: Add water, nonionic surfactant, and fatty alcohol polyoxyethylene ether with an EO number of 2-5 to the container; S2: Add fatty acids, alkalinity regulator and anionic surfactant to the container and stir until homogeneous; S3: Raise the temperature of the liquid to 80-90℃, add hydrogenated castor oil and stir well; S4: Reduce the temperature of the liquid to 55-65℃, add polyethylene glycol difatty acid ester and other functional additives, and stir evenly.

[0043] The reagents used in the examples and comparative examples are as follows: LAS: Sodium linear alkylbenzene sulfonate, with a raw material content ≥99%; AES: Sodium fatty alcohol polyoxyethylene ether sulfate, with a raw material content of 70% by mass. AEO9: Fatty alcohol polyoxyethylene ether with an EO number of 9, and a raw material mass content of ≥99%; AEO3: Fatty alcohol polyoxyethylene ether with an EO number of 3, and a raw material mass content of ≥99%; SOE: Modified oleic acid ethoxylates, with a raw material content ≥99%; 638: Polyethylene glycol difatty acid ester, raw material mass content ≥99%.

[0044] The performance tests of the concentrated laundry detergents prepared in the examples and comparative examples are as follows: (1) Active ingredient mass content: the sum of the mass fractions of anionic surfactants, nonionic surfactants and thickening components in the laundry detergent formula.

[0045] (2) Long-term stability test: The prepared laundry detergent concentrate and the concentrate obtained by diluting the laundry detergent concentrate were placed at room temperature and 45°C oven for 3 months respectively to observe whether precipitation and stratification occurred in the appearance of the concentrate. "No precipitation or stratification occurred in the concentrate after 3 months at room temperature and after 3 months at 45°C" is considered as qualified.

[0046] (3) Viscosity after dilution by n times: Take concentrated laundry detergent, add water as needed, the mass of water is n times the mass of concentrated laundry detergent, stir evenly and test its viscosity.

[0047] Examples 1-6 and Comparative Examples 1-10 The preparation method of concentrated laundry detergent includes the following steps: S1: Add water, nonionic surfactant, and fatty alcohol polyoxyethylene ether with an EO number of 2-5 to the container; S2: Add fatty acids, alkalinity regulator and anionic surfactant to the container and stir until homogeneous; S3: Raise the temperature of the liquid to 85°C, add hydrogenated castor oil and stir well; S4: Reduce the temperature of the liquid to 60°C, add polyethylene glycol difatty acid ester and other functional additives (such as preservatives), and stir until homogeneous.

[0048] Table 1. Raw material formulation and performance test results of concentrated laundry detergents in Comparative Examples 1-5

[0049] As shown in Table 1, a comparison of the experimental results of Comparative Examples 1-4 clearly shows that as the proportion of nonionic surfactants in the formulation gradually increases, the flowability of the laundry detergent composition at room temperature exhibits a continuously improving trend. This is because nonionic surfactants, with their hydrophobic carbon chains and hydrophilic polyoxyethylene chains, can embed themselves within the long-range rod-shaped micelle structure assembled by anionic surfactants in the system, weakening the hydrophobic interactions and entanglement effects between micelles, disrupting the three-dimensional network structure formed by the high-concentration surfactant system, and effectively reducing the internal frictional resistance and overall apparent viscosity of the system. The higher the proportion of nonionic surfactants, the more significant this effect of micelle depolymerization and reduction of system cohesion becomes, thus steadily improving the system's room temperature flowability. As shown in Comparative Example 5, when the content of nonionic surfactants reaches 30% or more, the laundry detergent composition can exhibit a flowable liquid state at room temperature. However, the storage stability of the system at this ratio has significant defects, and stratification occurs within a short time at room temperature. This is because an excessively high proportion of nonionic surfactants will disrupt the hydrophilic-hydrophobic balance of the mixed surfactant system, causing the phase stability threshold of the mixed micelles to be exceeded. The micelles will then macroscopically aggregate and gradually separate, ultimately resulting in system stratification, which affects the product's appearance and uniformity of use.

[0050] Meanwhile, data from Comparative Example 5 showed that although the system, after being blended with polyethylene glycol dicarboxylic acid esters and fatty acids, could achieve a viscosity of 243 mPa·s through a self-thickening effect after a 6-fold dilution, the system essentially lost its viscosity when the dilution factor was increased to 7 times. During the dilution process, fatty acids and polyethylene glycol dicarboxylic acid esters synergistically assembled to form a worm-like micelle network, thereby achieving self-thickening. However, after a 7-fold dilution, the total surfactant concentration was below the critical micelle aggregation concentration, which could not support a continuous micelle network structure. Therefore, the thickening component could not contribute effectively to the viscosity, resulting in a significant decrease in the system viscosity.

[0051] Table 2. Raw material formulation and performance test results of concentrated laundry detergents in Comparative Examples 6-7 and Example 1

[0052] As shown in Table 2, a comparison of the experimental results of Comparative Example 6 and Comparative Example 7 shows that adding hydrogenated castor oil to the laundry detergent formula to construct a suspension system can maintain the homogeneity of the composition at room temperature and avoid stratification. However, the amount of hydrogenated castor oil added in Comparative Examples 6-7 is too low, and the suspending force it forms is insufficient to counteract the sedimentation or floating tendency caused by polyethylene glycol difatty acid esters and fatty acids in the system. Therefore, in the long-term stability test at 45℃, the system showed poor stability and was prone to phase separation. From the perspective of the mechanism of action, the suspension stabilizing effect of hydrogenated castor oil originates from the needle-like microcrystals precipitated in the surfactant system. When the amount of hydrogenated castor oil added is insufficient, a continuous and complete crystal network cannot be formed, and the system can only barely maintain homogeneity at room temperature (when the intensity of molecular thermal motion is low). However, at a high temperature of 45°C, the molecular thermal motion is significantly intensified, the driving force for phase separation of components is greatly increased, and the network strength of hydrogenated castor oil microcrystals decreases with increasing temperature. The weak suspension structure is insufficient to counteract the sedimentation or floating tendency caused by polyethylene glycol difatty acid esters and fatty acids, ultimately leading to the instability of the system under long-term high-temperature storage.

[0053] In Example 1, the amount of hydrogenated castor oil added was more sufficient, which enabled the construction of a dense and continuous three-dimensional suspension network within the system, effectively limiting the migration and aggregation of various functional components. Therefore, the resulting concentrated laundry detergent exhibited excellent system stability under both room temperature and high temperature conditions. At the same time, the sufficient amount of hydrogenated castor oil did not disrupt the self-assembly thickening mechanism of the surfactant. Even after a 6-fold dilution, the system could still achieve self-thickening through the synergistic micelle assembly of polyethylene glycol difatty acid esters and fatty acids, maintaining a high viscosity level.

[0054] Table 3. Raw material formulation and performance test results of concentrated laundry detergents in Examples 2-6

[0055] As can be seen from the experimental data in Table 3, comparing Example 1 with Examples 2 and 4, it is evident that increasing the total content of the thickening component (a compound system of polyethylene glycol difatty acid esters and fatty acids) in the formula does indeed effectively increase the viscosity of the laundry detergent after a 6-fold dilution. However, simply increasing the proportion of this compound component is insufficient to achieve effective self-thickening after a 7-8 fold dilution. This is because higher dilution ratios significantly reduce the total concentration of surfactants in the system. When the concentration falls below the critical aggregation threshold for worm-like micelle formation, a continuous micelle entanglement network cannot be constructed, and the system viscosity decreases sharply.

[0056] Further comparison of the results of Examples 2 and 3, and Examples 4 and 5, reveals that the thickening efficiency of the laundry detergent system is significantly improved after introducing AEO3 as a synergistic thickening component. Even after 7-8 times dilution, an effective self-thickening effect can still be achieved. This is because the addition of fatty alcohol polyoxyethylene ethers with an EO number of 2-5 can deeply synergistically amplify the original thickening effect of fatty acids and polyethylene glycol difatty acid esters through multiple mechanisms such as optimizing the mixed micelle morphology, reinforcing the three-dimensional network structure, and improving the hydration capacity of the system. Thus, a stable thickening structure can be maintained even at higher dilution ratios and lower total surfactant concentrations, ultimately achieving a significant increase in viscosity after the composition is diluted 6-8 times. Furthermore, both the laundry detergent solution before and after dilution passed long-term stability tests.

[0057] Furthermore, the experimental results of Example 6 show that by increasing the proportion of the compound thickening components (polyethylene glycol dicarboxylic acid ester, fatty acids and AEO3), the density and structural strength of the micelle network can be further enhanced, resulting in better thickening performance and ultimately significantly improving the viscosity level of the laundry detergent after dilution by 7-8 times.

[0058] Table 4. Raw material formulation and performance test results of concentrated laundry detergents in Comparative Examples 8-10

[0059] As shown in Table 4, compared to Example 5, Comparative Example 8, which only used polyethylene glycol dicarboxylic acid ester and fatty acid thickeners, did achieve a viscosity of approximately 200 mPa·s after an 8-fold dilution when the total content of thickening components was increased, but the resulting concentrated laundry detergent exhibited stratification and precipitation during long-term observation at room temperature. This is because in concentrated systems with higher active ingredient content, the water content is already very low, and fatty acids have very low solubility in water. High concentrations of fatty acids exceed the system's stability capacity, making it prone to precipitation and stratification. In addition, when thickeners like polyethylene glycol dicarboxylic acid ester are used in high amounts, they can easily lead to the formation of excessive gels or a "jelly-like" structure in localized areas of the system. This uneven gel structure manifests as stratification on a macroscopic scale. Therefore, if additional fatty acids and polyethylene glycol dicarboxylic acid ester are added to achieve self-thickening at higher dilution ratios, the solubility limit of the system will be exceeded, causing some components to be unable to be stably "encapsulated" in micelles. This results in the undispersed components precipitating out when the system's "accommodation" capacity reaches its limit, forming visible precipitation or stratification.

[0060] Adding hydrogenated castor oil (comparative examples 9-10) to Comparative Example 8 also failed to achieve a stable suspension effect. This may be because, due to the highly concentrated system, the total amount of polyethylene glycol difatty acid esters and fatty acids added was too high (>12%). The three-dimensional network space formed by hydrogenated castor oil was limited, and even if more hydrogenated castor oil was added, it could not achieve a better suspension effect, and the liquid would re-separate and precipitate.

[0061] Therefore, this invention adds fatty alcohol polyoxyethylene ether with an EO number of 2-5 to concentrated laundry detergent with high active ingredient content to assist in thickening. This can improve the thickening efficiency of polyethylene glycol difatty acid ester and fatty acid, achieving a self-thickening effect after dilution of 6-8. At the same time, by adding hydrogenated castor oil for suspension stabilization, both higher thickening ratios and system stability can be achieved.

[0062] 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 highly active, dilutable, self-thickening concentrated laundry detergent, characterized in that, Based on 100% of the total mass of the concentrated laundry detergent, the concentrated laundry detergent comprises: 75-90% active ingredients, 0.15-1% hydrogenated castor oil, and water; wherein the active ingredients include the following components: 10-40% anionic surfactants, 30-50% nonionic surfactant, 5-10% polyethylene glycol difatty acid ester, 0-10% fatty alcohol polyoxyethylene ethers with an EO number of 2-5 1-5% fatty acids; The nonionic surfactants do not include fatty alcohol polyoxyethylene ethers with an EO number of 2-5.

2. The highly active, dilutable, self-thickening concentrated laundry detergent according to claim 1, characterized in that, The total mass percentage of the polyethylene glycol difatty acid ester and fatty acids is ≤12%; the mass percentage of the hydrogenated castor oil in the total mass percentage of the polyethylene glycol difatty acid ester and fatty acids is ≥1.5%.

3. The highly active, dilutable, self-thickening concentrated laundry detergent according to claim 1, characterized in that, The fatty acid has 8-22 carbon atoms.

4. The highly active, dilutable, self-thickening concentrated laundry detergent according to any one of claims 1-3, characterized in that, The polyethylene glycol difatty acid ester is synthesized by esterification of polyethylene glycol with two saturated or unsaturated natural fatty acids having ≥16 carbon atoms.

5. The highly active, dilutable, self-thickening concentrated laundry detergent according to claim 1, characterized in that, The fatty alcohol polyoxyethylene ether with an EO number of 2-5 has 8-12 carbon atoms.

6. The highly active, dilutable, self-thickening concentrated laundry detergent according to claim 1 or 5, characterized in that, The nonionic surfactant is a polyoxyethylene type nonionic surfactant.

7. The highly active, dilutable, self-thickening concentrated laundry detergent according to claim 1, characterized in that, The concentrated laundry detergent also includes 0-5 wt% of an alkaline regulator; the alkaline regulator includes one or more of sodium hydroxide, potassium hydroxide, sodium carbonate, and potassium carbonate.

8. The highly active, dilutable, self-thickening concentrated laundry detergent according to claim 1 or 7, characterized in that, The concentrated laundry detergent also includes 0-5 wt% of other functional additives; the other functional additives include one or more of the following: enzyme preparations, color protectants, antibacterial agents, fabric softeners, anti-redeposition agents, chelating agents, and preservatives.

9. The highly active, dilutable, self-thickening concentrated laundry detergent according to claim 1, characterized in that, The concentrated laundry detergent has a pH of 6.0-8.

0.

10. The highly active, dilutable, self-thickening concentrated laundry detergent according to claim 1 or 9, characterized in that, The maximum dilution ratio of the concentrated laundry detergent is 8 times, and the viscosity of the diluted solution is >200 mPa·s.

11. A method for preparing a highly active, dilutable, self-thickening, concentrated laundry detergent as described in any one of claims 1-10, characterized in that, Includes the following steps: S1: Add water, nonionic surfactant, and fatty alcohol polyoxyethylene ether with an EO number of 2-5 to the container; S2: Add fatty acids and anionic surfactants to the container and stir until well mixed; S3: Raise the temperature of the liquid to 80-90℃, add hydrogenated castor oil and stir well; S4: Lower the temperature of the liquid to 55-65℃, add polyethylene glycol difatty acid ester and stir until homogeneous.

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