In concentrated detergent formulations, the technical challenges of formulation stability are often faced due to the gel compartment of most nonionic surfactants and the limited solubility of anionic surfactants. By exploring two special straight-chain alcohol alkoxylates, EcoSense EP2308 and EP2325, in comparison with AEO-9 and isomeric alcohol ethers in concentrated detergents, it was found that EP2308 and EP2325 can significantly enhance the sebum detergency of concentrated detergents and improve the low-temperature stability of the formulations. The use of EP2325 can increase the percentage of anionic surfactants in the formulation, allowing more flexibility in formulation design.
Concentration of detergents is a trend in the industry. Compared with ordinary detergents, concentrated detergents are more environmentally friendly in terms of production, packaging, transportation, storage and emission. Currently, the industry standard requires that the total active ingredient content of ordinary laundry detergents should be 15% and above, and the total active ingredient content of concentrated laundry detergents should be 25% and above.
Formulation with special nonionic surfactants to improve formulation stability. In this paper, we will explore two special straight-chain alcohol alkoxylates, EcoSense EP2308 and EP2325, in comparison with AEO-9 and isomeric alcohol ethers in concentrated detergents to provide a reference for designing concentrated detergent formulations.
Performance comparison in triple concentrated laundry detergents triple concentrated, formulation A1 is the formulation base, the nonionic surfactant is 22% A EO-9, formulations A2 to A4 are 4% EP2308, EP2325, isomeric alcohol ether L were used to replace the 4% AEO-9 in the base (Formulation A1), to compare the difference in detergency, appearance and viscosity from A1 to A4. The detergency test uses the formulation matrix as the standard, i.e., Formulation A1, and when the detergency ratio value is greater than 1.0, it indicates that the detergency of the formulation is better than that of the formulation matrix. The test method refers to GB/ T 13174-2021, the test concentration are 0.67g/L.
For the cleaning of carbon black soiled fabrics, there was little difference in carbon black removal performance between formulations A1 and A4; for the cleaning of protein soiled fabrics, formulations A2, A3, and A4 all showed a small increase, with formulations A2 and A3 showing a slightly larger increase than A4, with a stronger protein stain removal performance; for the cleaning of sebum soiled fabrics, formulations A2 and A3 showed a very significant increase, while formulation A4 showed no significant increase. The test results illustrate that the use of 4% EP2325 or EP2308 to replace 4% AEO-9 in this triple-concentrated laundry detergent formulation slightly improves the protein detergency of the formulation, and improves the sebum detergency by a large margin.
Formulations A1 to A4 were tested for viscosity and stability when placed at 5°C for 1 month. From the results, it can be seen that the viscosities of formulations A2 to A4, which have been replaced by nonionic surfactants, have decreased; after 1 month at 5°C, formulations A1 and A4 have a cloudy appearance, while formulations A2 and A3 can remain transparent. The experimental results indicate that the use of 4% EP2325 or EP2308 to replace 4% AEO-9 in this triple-concentrated laundry detergent formulation reduces the viscosity of the formulation and improves the low temperature stability of the formulation.
Performance comparison of concentrated laundry detergents with high anionic surfactant content
The solubility of the commonly used anionic surfactants sulfonic acid and AES is limited, and therefore the amount of sulfonic acid and AES added in highly concentrated detergent formulations is also restricted. The triple concentrated laundry detergent formulations with high anionic surfactant content were designed to investigate whether the special nonionic surfactants improved the stability of the formulations.The formulations and room temperature appearance are shown in Table 3.The anionic surfactants of the formulations were 16% sulfonic acid and 18% AES, the nonionic surfactant of the formulation B1 was 18% AEO-9, and the formulas B2 and B3 were replaced with 4% isoparaffinic acid ether L and EP2325 to replace the 4% AEO-9. From the results, it can be seen that Formulation B1 and Formulation B2 have a cloudy appearance at room temperature and Formulation B3 has a clear appearance. Replacement of 4% AEO-9 with 4% EP-2325 improved the stability of the highly anionic surfactant concentrated formulations and was superior to that of isopropyl alcohol ether L. The results of this study show that the stability of the highly anionic surfactant concentrated formulations was improved by the use of 4% EP-2325.
Keeping the total active content of the formulations constant and continuing to increase the percentage of anionic surfactants, Formulations B4 and B5 have a cloudy appearance, while Formulation B6 remains clear.
Continuing to keep the total active content of the formulation unchanged, the two anionic surfactants were each increased by 1% of the active content, and the nonionic surfactant was decreased by 2%, the formulation and appearance are shown in Table 5. As can be seen from Table 5, the appearance of the formulation sample was turbid after the 4% replacement of formulation B8, i.e., the use of EP2325, and the appearance of the formulation sample was turbid when the replacement of EP2325 was increased to 10%, i.e., the formulation was clarified and transparent; formulation B9 used the isomeric alcohol ether L 10% replacement, and the appearance of the formulation was turbid. When the amount of EP2325 was increased to 10%, i.e., formulation B10, the appearance of the formulation was clarified and transparent; in formulation B9, 10% replacement of isopropyl ether L was used and the appearance of the formulation was turbid.
Performance Comparison in Laundry Gel
Laundry gel is a kind of concentrated detergent, the active content is usually more than 50%, and the water content is usually required to be less than 15%. Therefore, under the condition of high active content and low water content, special nonionic surfactants such as isomeric alcohol ether are often added in order to stabilize the formulation with excellent detergency performance. In this experiment, we will compare the effects of special nonionic surfactants EP2308, EP2325, and isomeric alcohol ether L, as well as the commonly used nonionic surfactant AEO-9, on the detergency of laundry gel formulations.
The nonionic surfactant in formulation C1 is 30% AEO-9, and formulations C2 to C4 replace 8% AEO-9 with 8% EP2308, EP2325, and isopropyl alcohol ether L, respectively.
There was no significant difference in the carbon black detergency of formulations C1 to C4, which were all better than that of standard laundry detergents; the protein detergency of formulations C1 to C4 was closer to that of standard laundry detergents; and the sebum detergency of formulations C1 to C4 were all significantly better than that of standard laundry detergents, with the strongest sebum detergency of formulation C3, followed by formulation C2, and the sebum detergency of formulations C1 and C4 were closer to that of standard laundry detergents.
The test results show that by replacing 8% AEO-9 with 8% EP2308 or EP2325 in the formulation, there is no significant improvement in carbon black and protein detergency, and sebum detergency can be significantly improved, with EP2325 showing a greater improvement; if isopropyl alcohol ether L is used as a replacement, there is no significant improvement in carbon black, protein, or sebum detergency.
Comparison of Different Substitution Levels in Laundry Gel Formulations
In order to understand the effect of EP2325 on the detergency of laundry gel beads in more detail, the detergency of laundry gel bead formulations was tested for changes in detergency using unequal amounts of EP2325 to replace AEO-9. The test formulations are shown in Table 7, the nonionic surfactant of formulation D1 is 30% AEO-9, and formulations D2 to D5 use 3%, 4%, 5%, and 6% EP2325 to replace 8% AEO-9, respectively, and the test results are shown in Fig. 3. From the test results, it can be seen that the stain removal power of carbon black of formulations D1 to D5 is close to the standard laundry detergent, with no obvious difference; the protein stain removal power of formulation D2 is lower, and the protein stain removal power of other formulations and standard laundry detergents are not as high as that of the standard laundry detergent. Formulation D2 has lower protein detergency, while the other formulations have protein detergency close to that of standard laundry detergents. Formulation D2 and D3 have lower sebum detergency due to a significant reduction in the total surfactant content, while formulations D1 and D4 have sebum detergency close to that of standard laundry detergents and better than that of standard laundry detergents, and formulation D5 has the strongest sebum detergency. From the test results, it can be seen that using 3% or 4% EP2325 to replace 8% AEO-9, the detergency of the laundry gel will decrease; when EP2325 is raised to 5%, the detergency of the laundry gel is close to that of the standard laundry detergent; when EP2325 is raised to 6%, the detergency of the laundry gel in terms of sebum detergency is significantly increased.
This paper explores the application of special nonionic surfactants EP2308 and EP2325 in concentrated detergents. Compared with fatty alcohol polyoxyethylene ether AEO-9 and isomeric alcohol ether L, in triple-concentrated laundry detergents, EP2325 and EP2308 can improve the low-temperature stability of formulations and significantly increase the sebum detergency, and EP2325 can increase the content of anionic surfactants in formulations and EP2325 increases the anionic surfactant content of the formulation, allowing for more flexibility in formulation design. In laundry gel formulations, EP2325 and EP2308 improve the sebum detergency of the formulation. The sebum detergency was significantly improved when 6% EP2325 was used to replace 8% AEO-9 in the bead formulation.
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