Surfactants with improved emulsifying properties

Abstract

The present disclosure relates to a nonionic surfactant having a nonionic block copolymer structure of Formula I: R-[A] x-[B] y, Formula I wherein R is a C8 to C30 alkyl group; x is 8 to 20; y is 2 to 20; the [A] x block is formed from propylene oxide; the [B] y block is formed from ethylene oxide; and the nonionic surfactant has a cloud point higher than 15 DEG C.

Description

Technical Field

[0001] Embodiments of the present disclosure relate to surfactants and, in particular, to surfactants having improved emulsification properties. Background Art

[0002] The emulsification properties of surfactants are important in many fields such as cleaning, detergency, and soil removal. The emulsification properties for vegetable or animal oils are very important for detergency and degreasing properties. To improve emulsification properties, surfactants with different structures have been developed and commercialized, but there is still a need in the art for surfactants that can provide improved emulsification properties, especially when dealing with vegetable oils and / or animal oils. One way to improve cleaning performance is to use alkaline compounds in detergent formulations. However, for applications such as dishwashing by hand, these compounds can cause skin irritation. Therefore, improving the emulsification properties of surfactants has proven to be a better option than using alkaline compounds. Accordingly, there is a need in the art for a type of extended nonionic surfactant that can provide strong emulsification properties, especially for vegetable or animal oils.

[0003] An interesting area in improving emulsification properties is the so-called "extended surfactants". Compared with conventional surfactants, extended surfactants include an intermediate polar spacer group, such as a block formed by propylene oxide (PPO) or PPO - polyethylene oxide (PEO), which is inserted between the hydrophilic head and the hydrophobic tail. Studies have shown that the PO group with weak lipophilic characteristics can provide a smooth polar transition region between the hydrophobic tail and the hydrophilic head, which can provide better emulsification than traditional surfactants without a PO segment. However, which structure of extended surfactant can provide the best emulsification properties remains unknown, and thus there is still a need in the art. Summary of the Invention

[0004] The present disclosure relates to the structure - property relationship of nonionic surfactants in terms of their emulsification properties for vegetable and animal oils, wherein the identified nonionic surfactant structures exhibit improved emulsification properties compared to other surfactants. Such improvements in the emulsification properties of nonionic surfactants may be advantageous in applications such as cleaning, detergency, and soil removal.

[0005] To this end, the present disclosure provides a nonionic surfactant comprising a nonionic block copolymer structure of Formula I:

[0006] R - [A] x - [B] y Formula I

[0007] wherein R is an alkyl group having 8 to 30 carbon atoms; x is 8 to 20; y is 2 to 20; [A] x the block is formed by propylene oxide; [B]y The block is formed from ethylene oxide; and the nonionic surfactant has a cloud point above 15 °C. For various embodiments, R can be a C12 to C18 alkyl group. For various embodiments, R can be a straight-chain alkyl group. For various embodiments, x can be from 8 to 10. For various embodiments, y can be from 4 to 10. For various embodiments, R can be C12-C14, x can be 8, and y can be 7. For various embodiments, R can be C12-C14, x can be 8, and y can be 9. For various embodiments, R can be 2-ethylhexyl, x can be 8, and y can be 4. For various embodiments, R can be C8-C14, x can be 8, and y can be 4. For various embodiments, R can be C16-C18, x can be 10, and y can be 10. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1A and Figure 1B The emulsifying properties of a formulation comprising EX 1, ethylene glycol phenyl ether solvent, and MIPA / DIPA amine according to the present disclosure are provided.

[0009] Figure 2A and Figure 2B The emulsifying properties of a formulation comprising CE I, ethylene glycol phenyl ether solvent, and MIPA / DIPA amine according to the present disclosure are provided. DETAILED DESCRIPTION

[0010] The present disclosure relates to the emulsifying properties of nonionic surfactants for mineral oils, vegetable oils, and animal oils (hereinafter referred to as "oils"), wherein the nonionic surfactant structure has improved emulsifying properties relative to other surfactants. In applications such as cleaning, detergency, and decontamination, such improvements in the emulsifying properties of nonionic surfactants can be advantageous. Specifically, the nonionic surfactants of the present disclosure can be used in emulsions for removing oils from textile materials (such as, but not limited to, fabrics, yarns, or other woven materials comprising natural or artificial fiber networks). For example, the nonionic surfactants of the present disclosure can be used in various cleaning processes, such as scrubbing or laundry washing (i.e., cleaning), which are used to treat or pretreat textile material fabrics. To obtain effective cleaning performance (i.e., effectively remove oils), the nonionic surfactant composition should have effective emulsifying properties as well as other characteristics. Such characteristics allow the surfactant to penetrate the textile material and surround the oil to remove the oil.

[0011] Unless otherwise specified, numerical ranges (such as "2 to 10") are real numbers and include the values defining the range (e.g., 2 and 10).

[0012] Unless otherwise specified, ratios, percentages, parts, etc. are by weight.

[0013] As described above, the present disclosure provides a nonionic surfactant comprising a nonionic block copolymer structure of Formula I:

[0014] R-[A] x -[B] y Formula I

[0015] wherein R is an alkyl group having 8 to 30 carbon atoms; x is 8 to 20; y is 2 to 20; [A] x the block is formed from propylene oxide (PO); [B] y the block is formed from ethylene oxide (EO); and the nonionic surfactant has a cloud point above 15 °C. For various embodiments, preferably the cloud point of Formula I is above 20 °C. The propylene oxide used to form [A] x the block may be 1,2-propylene oxide.

[0016] For various embodiments, R may be straight-chain or branched-chain. For various embodiments, R may be a straight-chain alkyl group. Preferably, R is an alkyl group not shorter than C8. More preferably, R is an alkyl group not shorter than C12. In additional embodiments, R may be an alkyl group having 12 to 18 carbon atoms. For various embodiments, R may be an alkyl group having 12 to 14 carbon atoms. For various embodiments, R may be an alkyl group having 16 to 18 carbon atoms. For various embodiments, R may be 2-ethylhexyl.

[0017] For various embodiments, x is not less than 8. For various embodiments, x may be 8 to 10. For various embodiments, y is greater than 2. For various embodiments, y may be 4 to 10. In more specific embodiments, R may be an alkyl group having 12 to 14 carbon atoms, x may be 8, and y may be 7. For various embodiments, R may be C12-C14, x may be 8, and y may be 9. For various embodiments, R may be 2-ethylhexyl, x may be 8, and y may be 4. For various embodiments, R may be C8-C14, x may be 8, and y may be 4. For various embodiments, R may be an alkyl group having 16 to 18 carbon atoms, x may be 10, and y may be 10.

[0018] The nonionic block copolymer structures of formula I can be obtained in a conventional manner by reacting an alcohol with alkylene oxides such as ethylene oxide (EO) and propylene oxide (PO) in the presence of a catalyst. The polymerization can be bulk polymerization or solution polymerization. Catalysts suitable for alkylene oxide polymerization can be found in the literature, for example, F.E. Bailey, Jr., Joseph V. Koleske, "Alkylene Oxides and Their Polymers", Marcel Dekker, New York, 1991, page 35, including anionic or basic catalysts, acidic or cationic catalysts, and coordination catalysts such as potassium hydroxide (KOH), boron trifluoride, or double metal cyanide complex (DMC) catalysts such as zinc hexacyanocobaltate.

[0019] The alkylene oxide is typically fed to a reactor containing a dry initiator and catalyst at a temperature of 50 °C to 160 °C. The polymerization is generally considered complete when the pressure in the reactor returns to approximately the same pressure as before the alkylene oxide was fed. Depending on the product and application, the catalyst can be neutralized, removed by known means such as filtration, adsorption, and ion exchange, or left in the product.

[0020] The present disclosure also includes a surfactant composition comprising the nonionic surfactant of the present disclosure. For various embodiments, the surfactant composition can comprise, but is not limited to, the nonionic surfactant of the present disclosure, water, one or more amines, and / or one or more solvents. For various embodiments, the surfactant composition can comprise from 5 weight percent (wt%) to 30 wt% of the nonionic surfactant of the present disclosure; from 70 wt% to 80 wt% of water; from 0 wt% to 25 wt% of one or more amines; from 0 wt% to 25 wt% of one or more solvents, where wt% is based on the total weight of the surfactant composition. Embodiments of the surfactant composition also include those where water is initially absent, where the surfactant composition is subsequently mixed with water to produce an aqueous solution having, for example, a surfactant composition solution of 0.1 wt% to 10 wt%.

[0021] For various embodiments, the one or more amines can include, but are not limited to, alkanolamines, alkylalkanolamines, and combinations thereof. For example, the one or more amines can be selected from the group consisting of mono-isopropanolamine (MIPA), di-isopropanolamine (DIPA), monoethanolamine (MEA), triethanolamine (TEA), diethylethanolamine (DEEA), dimethylethanolamine (DMEA), methyldiethanolamine (MDEA), n-methylethanolamine (NMEA), and combinations thereof.

[0022] For various embodiments, one or more solvents can include, but are not limited to, glycol ethers such as ethylene glycol phenyl ether, propylene glycol phenyl ether, diethylene glycol butyl ether, dipropylene glycol methyl ether, 1-(2-butoxy-1-methylethoxy)propan-2-ol, 1-methoxy-2-propyl acetate, [2-(2-methoxymethylethoxy)methylethoxy]propanol, ethylene glycol monobutyl ether, diethylene glycol monohexyl ether, diethylene glycol monobutyl ether, ethylene glycol monohexyl ether, and combinations thereof.

[0023] The surfactant composition can also contain other optional additives. Examples of such additives include those that do not interfere with the emulsifying properties of the nonionic surfactant of the present disclosure and / or the surfactant composition comprising the nonionic surfactant of the present disclosure. Examples of such additives include, but are not limited to, bases such as sodium hydroxide, oxidizing agents such as hydrogen peroxide, and other surfactants such as ionic surfactants and nonionic surfactants, ethoxysulfated alcohols, linear alkylbenzene sulfonates, alkyl diphenyl ether disulfonates, and other additives known in the art.

[0024] For various embodiments, the surfactant composition of the present disclosure can be used in the process of cleaning and / or scrubbing an oil-soiled article as provided herein. Such processes can be carried out at a temperature of 0 °C to 100 °C and a pressure of 0.5 kPa to 1.5 kPa. For example, the surfactant composition of the present disclosure can be used to scrub textile materials by bringing the textile into contact with a surfactant composition comprising a nonionic surfactant.

[0025] Example

[0026] The examples below are provided for illustration only and are not intended to limit or restrict the embodiments in any way. In the examples of the present invention (EX) and comparative examples (CE), various terms and names of materials were used, and these terms and names include, for example, the following:

[0027] Table 1 - Materials

[0028]

[0029] Table 2: Examples (EX) and Comparative Examples (CE)

[0030]

[0031]

[0032]

[0033] a: Cloud point measured in a 10 wt% aqueous solution.

[0034] Synthesis Example 1: Synthesis of nonionic surfactant represented by the following formula: L-C 12-14 -(PO)8-(EO)7, where L-C 12-14 refers to the straight-chain C 12-14 portion. 1 mole of L-C 12-14 alcohol and an aqueous potassium hydroxide solution (45 wt% to 50 wt%) are charged into a reactor. Based on the weight of the final product, a KOH content of about 0.17 wt% is added. The mixture is heated to about 50 °C to 60 °C for 30 minutes. After vacuum stripping at about 80 °C, the water content is controlled to less than 1000 ppm, and then the mixture is maintained at about 110 °C to 140 °C. Then, 8 moles of the first portion of PO (corresponding to 8 molar equivalents of L-C 12-14 alcohol) are slowly fed into the reactor. When the pressure in the reactor returns to approximately the same as the pressure before the PO feed, 7 moles of EO (corresponding to 7 molar equivalents of L-C 12-14 alcohol) are slowly fed into the reactor, and the reactor temperature is maintained at 110 °C to 140 °C. When the reactor returns to approximately the same as the pressure before the EO feed, the reaction is maintained at 110 °C to 140 °C for another 2 hours to ensure complete consumption of EO. After purging with N2 to remove residual oxides, the reactor is cooled to about 60 °C at ambient pressure. Then, acetic acid is added to the reactor to neutralize the KOH catalyst. After cooling to about 40 °C, the desired product is obtained.

[0035] Synthesis Example 2 : Synthesis of nonionic surfactant represented by the following formula: L-C 12-14 -(PO)8-(EO)9, where L-C 12-14 -refers to the straight-chain C 12-14 -portion

[0036] Synthesis Example 2 is carried out similarly to Synthesis Example 1, but in Step 1, L-C 12-14 alcohol is used as the starting alcohol, and the amounts of PO and EO fed into the reactor are changed accordingly.

[0037] Synthesis Example 3 : Synthesis of nonionic surfactant represented by the following formula: 2-ethylhexyl-(PO)8-(EO)6

[0038] Synthesis Example 3 is carried out similarly to Synthesis Example 1, but in Step 1, 2-ethylhexanol is used as the starting alcohol, and the amounts of PO and EO fed into the reactor are changed accordingly.

[0039] Synthesis Example 4 : Synthesis of nonionic surfactant represented by the following formula: L-C 8-14 -(PO)8-(EO)4, where L-C 8-14- refers to a straight-chain C 8-14 - moiety

[0040] Synthesis Example 4 was carried out in a similar manner to Synthesis Example 1, but L-C 8-14 alcohol was used as the starting alcohol in Step 1, and the amounts of PO and EO fed into the reactor were changed accordingly.

[0041] Synthesis Example 5 : Synthesis of a nonionic surfactant represented by the following formula: L-C 16-18 -(PO) 10 -(EO) 10 , where L-C 16-18 - refers to a straight-chain C 16-18 - moiety

[0042] Synthesis Example 5 was carried out in a similar manner to Synthesis Example 1, but L-C 16-18 alcohol was used as the starting alcohol in Step 1, and the amounts of PO and EO fed into the reactor were changed accordingly.

[0043] Synthesis Example 6 : Synthesis of a nonionic surfactant represented by the following formula: L-C 12-14 -(PO) 12 -(EO)6, where L-C 12-14 - refers to a straight-chain C 12-14 - moiety

[0044] Synthesis Example 6 was carried out in a similar manner to Synthesis Example 1, but L-C 12-14 alcohol was used as the starting alcohol in Step 1, and the amounts of PO and EO fed into the reactor were changed accordingly.

[0045] Evaluation of Emulsifying Performance of Formulations

[0046] To test the emulsification performance, 400 μL of surfactant solution (1 wt% aqueous surfactant solution) was dispensed into a 1 mL vial, and then 150 μL of liquid oil was added on top of the solution. After capping, the vial was vibrated for 60 seconds at intensity 7 by an automatic vibrator in a PICAII robot (an internal imaging robot with a vial shaker), and then an image of the sample was taken after vibration. The gray value of the aqueous part of the vial was measured using ImageJ [1. Rasband, W.S., ImageJ, U.S. National Institutes of Health, Bethesda, Maryland, USA, https: / / imagej.nih.gov / ij / , 1997 - 2018.] to quantify the emulsification performance of the formulation. The higher the gray value (indicating a whiter appearance of the emulsion), the better the emulsification performance. For this test, unless otherwise specified, the liquid oil is a mixture of corn oil: peanut oil: sunflower oil in a weight ratio of 1:1:1.

[0047] Soiling Procedure - Detergent Testing

[0048] The detergency performance (detergent test) of different surfactant solutions was also evaluated using a polyester fabric with olive oil stains. The detergency test used a Tergotometer (Model TRG 800i, Copley) with the following process parameters: dosage: 0.4 g / L; temperature: 30 °C; agitation rotation speed: 120 rpm; washing time: 20 minutes; water: water hardness 120 ppm; sample: The samples used in this study are listed in Table 1 (size 5 cm × 5 cm)

[0049] The color of the dried samples was measured by a spectrophotometer (Konica Minolta spectrophotometer CM - 3600A) before and after washing. The soiled side of each piece was measured. The output of the color measurement includes L*, a*, and b*. The detergency was calculated based on the following formula:

[0050]

[0051] Using a standard polyester fabric with olive oil stains, the details of the stained fabric are shown in Table 3.

[0052] Table 3. Details of Polyester Fabrics with Stains

[0053] Sample Name Code Soil / Fabric Supplier POP W-30B Pigment, Olive Oil / Polyester WFK

[0054] Examples for demonstrating the emulsification performance of surfactants

[0055] Table 4. Comparison of Emulsifying Performance

[0056]

[0057] Compared with the comparative examples, EX 1 to EX 6 shown in Table 4 exhibit better emulsifying properties, where the higher the gray value, the better the performance. From this data, it can be determined that a nonionic surfactant having a nonionic block copolymer structure of formula I as provided herein:

[0058] R-[A]x-[B]y Formula I

[0059] can provide better emulsifying properties for vegetable oils. For example, in the case of having the same hydrophobic tail, a more hydrophobic surfactant (lower cloud point) tends to provide better emulsifying properties for vegetable oil mixtures. However, there are some differences between the triblock structure (R-[EO]z-[PO]x-[EO]y) and the diblock counterpart (R-[PO]x-[EO]y) of the present disclosure. In the case of similar hydrophobicity (similar cloud points), the surfactant having a diblock structure tends to provide better emulsifying properties. For example, EX 2 (C12-14-PO8-EO9) with a cloud point of 40 °C (1 wt% aqueous solution) provides better performance than CE D (C12-14-EO4-PO8-EO4, cloud point = 34 °C, 1 wt% aqueous solution) and CE E (C12-14-EO4-PO8-EO6, cloud point = 42 °C, 1 wt% aqueous solution), indicating that introducing an internal EO block may impair the emulsifying properties.

[0060] The comparison between CE I and EX 3 shows that when only a longer internal PO chain segment is introduced, a smaller improvement is observed (the number of PO units in CE I is 5 and the number of PO in EX 3 is 8). This comparison shows that both a longer hydrophobic tail and a longer PO chain segment in the general formula structure are beneficial for providing good emulsifying properties; in addition, it is advantageous that the PO chain segment is directly connected to the hydrophobic tail without an additional EO unit. If there is an additional internal EO unit, even with a longer hydrophobic tail such as CE G (C16-18-EO4.42-PO13.74-EO5, cloud point 28 °C), the surfactant tends to provide lower emulsifying properties.

[0061] The non-ionic surfactants of the present disclosure are further supported by comparison with CE P and CE Q surfactants. Since CE P and CE Q surfactants have a longer hydrophobic tail (linear C8-14 alcohol with an average carbon number of about C10) than CE I surfactant (2-ethylhexanol), when a longer PO block is introduced, if we compare the performance among CE Q, CE M and CE O, a more significant improvement in emulsification performance is observed. For example, the performance of CE O (12 PO units) is greater than that of CE M (8 PO units), and CE M is greater than CE Q (3 PO units), which is very consistent with the number of PO units.

[0062] The removal of vegetable oil on polyester also demonstrates the better performance of the surfactant of the present invention having the structure of formula I, as further demonstrated in Table 5, and the results in Table 5 also confirm the positive emulsification performance in detergency, especially for polyester fabrics.

[0063] As shown in Table 5, EX 1 and EX 2 provide much better detergency performance than CE I, CE P and CE Q.

[0064] Table 5. Vegetable Oil Removal Performance (Olive Oil Stains on Polyester)

[0065]

[0066] To further demonstrate the performance of the non-ionic surfactants of the present disclosure, their performance in the above-prepared system was compared with other surfactants, solvents and amines. 1% aqueous solutions containing surfactants, solvents and amines were prepared according to the dosages in Table 6, and the solution samples were thoroughly mixed at room temperature (23 °C) to form a homogeneous solution, and then their emulsification performance was evaluated using the same procedure as described in "Evaluation of Emulsification Performance of Formulations".

[0067] Table 6. Combinations of Surfactants, Solvents and Amines

[0068]

[0069]

[0070]

[0071] In Figure 1A and Figure 1B , the higher the value (the axis on the right side of the figure) indicates better performance, so the closer the data point is to the axis on the right side of the figure, the better the emulsification.

[0072] In contrast, the performance of another extended non-ionic surfactant CE I was also evaluated and shown in Figure 2A and Figure 2B as well.

[0073] In Figure 1A - 1B and Figure 2A - 2B it can be clearly seen that the formulations with the surfactant of the present invention can provide good emulsification performance over the entire dose range; while for the traditional extended non-ionic surfactant CE I, only the formulations with a higher amine dose can provide good performance; as a result, the performance comparison here demonstrates the excellent performance of the extended non-ionic surfactant of the present invention having the general formula structure 1.

[0074] From the above results, it can be concluded that the non-ionic surfactant satisfies the following three structural features: a longer hydrophobic tail (carbon number >= 8, more preferably >= 12); a longer propylene oxide (PO) unit (>= 8), and the PO unit is directly connected to the hydrophobic tail.

Claims

1. A non-ionic surfactant, the non-ionic surfactant comprising: A non-ionic block copolymer structure of Formula I: R-[A] x -[B] y Formula I wherein R is an alkyl group having 8 to 30 carbon atoms; x is 8 to 20; y is 2 to 20; [A] x The block is formed of propylene oxide; [B] y The block is formed of ethylene oxide; and the nonionic surfactant has a cloud point higher than 15 °C.

2. The non-ionic surfactant according to claim 1, wherein R is a C12 to C18 alkyl group.

3. The non-ionic surfactant according to any one of claims 1 to 2, wherein R is a straight-chain alkyl group.

4. The non-ionic surfactant according to any one of claims 1 to 3, wherein x is 8 to 10.

5. The non-ionic surfactant according to any one of claims 1 to 4, wherein y is 4 to 10.

6. The non-ionic surfactant according to claim 1, wherein R is C12-C14, x is 8, and y is 7.

7. The non-ionic surfactant according to claim 1, wherein R is C12-C14, x is 8, and y is 9.

8. The non-ionic surfactant according to claim 1, wherein R is 2-ethylhexyl, x is 8, and y is 4.

9. The non-ionic surfactant according to claim 1, wherein R is C8-C14, x is 8, and y is 4.

10. The non-ionic surfactant according to claim 1, wherein R is C16-C18, x is 10, and y is 10.

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