Multifunctional green surfactant and preparation method thereof

Abstract

The invention discloses a multifunctional green surfactant, and belongs to the field of fine chemicals. The surfactant disclosed by the invention is obtained by reacting polybasic acid or polybasic acid anhydride with long-chain fatty alcohol and then salifying; the fatty alcohol refers to fatty alcohol of C8-22. Alpha, beta-unsaturated double bond polybasic acid or anhydride reacts with long-chain fatty alcohol and then salification is performed to obtain the surfactant, the prepared surfactant can play a role in protecting free sulfydryl groups of hair through Michael addition, meanwhile, the surfactant further has a cleaning function and a foam increasing function, and the surfactant has wider application and is worthy of popularization and application. And a new thought is provided for the research of the surfactant.

Description

Technical Field

[0001] The invention belongs to the field of fine chemicals, and in particular relates to a multifunctional green surfactant and a preparation method thereof. Background Art

[0002] Surfactants are important fine chemical products, widely used in the fields of industry, agriculture, daily chemicals, etc. With the development of economic level and the improvement of ecological protection awareness, people's demand for green surfactants is growing. Green surfactants use natural oils and fermentation products to replace traditional chemical raw materials, thereby reducing energy consumption and toxicity in the preparation process, and emphasize their biodegradability, that is, they can be decomposed by microorganisms in the natural environment to reduce pollution to the environment. At present, the development of green surfactants is concentrated on washing raw materials. Alkyl glycosides, amino acid surfactants and other varieties have been widely used throughout the country. In comparison, the development of multifunctional green surfactants is still relatively lacking. Multifunctional surfactants refer to not only a single cleaning and washing function, but also include many other functions such as sterilization, skin care, and hair care, which can meet consumers' demand for product versatility in daily chemical products.

[0003] Currently, there is no multifunctional green surfactant, so it is urgent to develop green surfactants with multifunctional functions. Summary of the invention

[0004] In view of the shortcomings of the prior art, the present invention provides a multifunctional green surfactant and a preparation method thereof. The surfactant of the present invention is obtained by reacting a polyacid or anhydride with an α, β-unsaturated double bond with a long-chain fatty alcohol and then forming a salt. The prepared surfactant can protect the free thiol groups of the hair through Michael addition, achieving the surface cleaning function and the hair care function at the same time.

[0005] The technical solution of the present invention is as follows:

[0006] The present invention firstly protects a multifunctional green surfactant, which is obtained by reacting a polyacid or a polyacid anhydride with a long-chain fatty alcohol and then forming a salt; the long-chain fatty alcohol refers to a C8-22 fatty alcohol.

[0007] Preferably, the polyacid is a polyacid with α, β-unsaturated double bonds; and the polyacid anhydride is an acid anhydride with α, β-unsaturated double bonds.

[0008] Preferably, the polyacid includes maleic acid and fumaric acid; the polyacid anhydride includes itaconic anhydride;

[0009] Preferably, the long-chain fatty alcohol is a C12-18 fatty alcohol.

[0010] Preferably, the long-chain fatty alcohol includes at least one of n-octanol, lauryl alcohol, myristyl alcohol and oleyl alcohol, and the long-chain fatty alcohol is preferably lauryl alcohol.

[0011] The second aspect of the present invention protects a method for preparing the surfactant described in the first aspect, wherein the preparation method is:

[0012] S1: Mix the polyacid, long-chain fatty alcohol and catalyst, heat and stir to react, add solvent I to the reaction solution and stir again, cool, filter and obtain a solid, recrystallize and purify to obtain an intermediate product.

[0013] S2: After mixing the intermediate product with alkaline solution, adding solvent II to heat and react, evaporating the solvent to obtain a surfactant.

[0014] Preferably, in step S1, the unit molar ratio of the polyacid to the long-chain fatty alcohol is 2:1-1:1, preferably 1.8:1-1.2:1, and most preferably 1.25:1; the amount of the catalyst is 0.75%-1.25% of the total mass of the polyacid and the fatty alcohol, preferably 0.9%-1.1%, and most preferably 1%; the catalyst is sodium acetate; the heating and stirring temperature is 40-80°C, preferably 70°C; the heating and stirring time is 1-6h, preferably 3h.

[0015] Preferably, in step S1, the solvent I is selected from at least one of n-heptane, isohexane, n-hexane, n-octane and petroleum ether; the mass volume ratio g / mL of the reaction solution to the solvent I is 0.5-1.5:1; the mass volume ratio g / mL of the reaction solution to the solvent I is preferably 0.75-1.25:1, and the mass volume ratio g / mL of the reaction solution to the solvent I is most preferably 1:1; the re-stirring time is 8-12 min, preferably 10 min.

[0016] Preferably, in step S2, the molar ratio of the intermediate product to the alkali solution is 1:0.95-1:1.05, most preferably 1:1; and the alkali solution is sodium hydroxide.

[0017] Preferably, in step S2, the mass volume ratio of the intermediate product and the alkali solution to the solvent II is 10-100:1 in mg / mL; the solvent II is selected from at least one of ethanol, methanol and distilled water; and the solvent II is preferably ethanol.

[0018] Preferably, in step S2, the temperature of the heating reaction is 50-70°C, preferably 60°C; the time of the heating reaction is 20-40 min, preferably 30 min.

[0019] The beneficial technical effects of the present invention are:

[0020] The present invention obtains a surfactant by reacting a polyacid or anhydride having an α, β-unsaturated double bond with a long-chain fatty alcohol and then forming a salt. The preparation method is simple, and the prepared surfactant can be combined with free thiol groups of hair through Michael addition to achieve a hair care function. At the same time, the surfactant also has a cleaning function and a foaming function, that is, the present invention successfully prepares a multifunctional green surfactant. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The potassium salt of lauryl itaconate prepared in Example 6 of the present invention, the infrared spectrum of the raw material and the physical schematic diagram of the potassium salt of lauryl itaconate.

[0022] In the figure: (a) is an infrared spectrum; (b) is the actual potassium salt of lauryl itaconate.

[0023] Figure 2 Comparison of friction coefficients of surfactants prepared in Examples 6-11 of the present invention.

[0024] Figure 3 Comparison of contact angles of surfactants prepared in Examples 6-11 of the present invention. DETAILED DESCRIPTION

[0025] The present invention is described in detail below in conjunction with the accompanying drawings and embodiments.

[0026] The present invention firstly provides a multifunctional green surfactant, wherein the surfactant is obtained by reacting a polyacid or a polyacid anhydride with a long-chain fatty alcohol and then forming a salt; the long-chain fatty alcohol refers to a C8-22 fatty alcohol.

[0027] In some embodiments, the polyacid is a polyacid with α, β-unsaturated double bonds; and the polyacid anhydride is an acid anhydride with α, β-unsaturated double bonds.

[0028] In some embodiments, the long-chain fatty alcohol is a C12-18 fatty alcohol.

[0029] In some embodiments, the long-chain fatty alcohol includes at least one of n-octanol, lauryl alcohol, myristyl alcohol, and oleyl alcohol, and the long-chain fatty alcohol is preferably lauryl alcohol. It is understood that the present invention utilizes polyacids (anhydrides) with α, β-unsaturated double bonds to react with long-chain fatty alcohols and then form salts to obtain new surfactants. Such molecules can protect the free thiol groups of hair through Michael addition. At the same time, the obtained product contains long chains, carboxyl groups, etc. The long chains are inserted into the oily dirt, and the carboxyl groups combine with water, thereby bringing the dirt into the water during the washing process to achieve decontamination. In addition, the surfactant prepared by the present invention can also have a foaming effect.

[0030] In some embodiments, the polyacid includes maleic acid and fumaric acid; the polyacid anhydride includes itaconic anhydride. It is understood that when the polyacid anhydride is itaconic anhydride, the obtained surfactant is a potassium salt of itaconate, which can form a ring with amino groups in hair to further improve the protection of hair.

[0031] After the polyacid or anhydride of the present invention is mixed with fatty alcohol, an intermediate product can be obtained through esterification reaction, and then a surfactant with cleaning function, foaming property and hair care can be obtained through salt formation.

[0032] When the polyacid anhydride is itaconic anhydride, its synthesis route is as follows:

[0033]

[0034] Where R = C n H 2n±1 , n is an integer from 7 to 17.

[0035] It can be seen that since itaconic anhydride can bind at different sites, two types of substances can be obtained after reacting with fatty alcohols. After salt formation, a mixture of two products of structural formula (1) and structural formula (2) is finally obtained. The obtained product of structural formula (2) can form a ring with amino groups in hair and be used for bleaching hair.

[0036] The second aspect of the present invention provides a method for preparing the surfactant described in the first aspect, the preparation method comprising:

[0037] S1: Mix the polyacid, long-chain fatty alcohol and catalyst, heat and stir to react, add solvent I to the reaction solution and stir again, cool, filter and obtain a solid, recrystallize and purify to obtain an intermediate product.

[0038] S2: After mixing the intermediate product with alkaline solution, adding solvent II to heat and react, evaporating the solvent to obtain a surfactant.

[0039] In some embodiments, in step S1, the unit molar ratio of the polyacid to the long-chain fatty alcohol is 2:1-1:1, preferably 1.8:1-1.2:1, and most preferably 1.25:1; the amount of the catalyst is 0.75%-1.25% of the total mass of the polyacid and the fatty alcohol, preferably 0.9%-1.1%, and most preferably 1%; the catalyst is sodium acetate; the heating and stirring temperature is 40-80°C, preferably 70°C; the heating and stirring time is 1-6h, preferably 3h.

[0040] In some embodiments, in step S1, the solvent I is selected from at least one of n-heptane, isohexane, n-hexane, n-octane, and petroleum ether; the mass volume ratio of the reaction liquid to the solvent I g / mL is 0.5-1.5:1; the mass volume ratio of the reaction liquid to the solvent I g / mL is preferably 0.75-1.25:1, and the mass volume ratio of the reaction liquid to the solvent I g / mL is most preferably 1:1; the re-stirring time is 8-12 min, preferably 10 min.

[0041] In some embodiments, in step S2, the molar ratio of the intermediate product to the alkali solution is 1:0.95-1:1.05, most preferably 1:1; and the alkali solution is sodium hydroxide.

[0042] In some embodiments, in step S2, the mass volume ratio of the intermediate product and the alkali solution to the solvent II is 10-100:1 in mg / mL, including but not limited to 10:1, 20:1, 30:1, 40:1, 50:1, 60:1, 70:1, 80:1, 90:1, and 100:1; the solvent II is selected from at least one of ethanol, methanol, and distilled water; and the solvent II is preferably ethanol.

[0043] In some embodiments, in step S2, the temperature of the heating reaction is 50-70°C, preferably 60°C; the time of the heating reaction is 20-40 min, preferably 30 min.

[0044] It is understandable that the present invention proposes to use long-chain fatty alcohols and itaconic anhydride to prepare green functional surfactants, wherein the fatty alcohols are derived from natural oils and fats, and itaconic acid and the like can be produced by biological fermentation, which is conducive to replacing the surfactant raw materials from petrochemical sources. At the same time, the multifunctional green surfactant molecules proposed by the present invention contain Michael active groups, which can react with thiol groups in hair. Furthermore, when the raw material is itaconic anhydride, the potassium salt of itaconate obtained can also form a ring with amino groups in hair to achieve hair care effects, further improving the hair care effects of the surfactants.

[0045] The present invention will be further described below by way of examples and the like.

[0046] Example 1

[0047] The intermediate product molecule used to prepare the surfactant is prepared as follows;

[0048] According to the molar ratio of itaconic anhydride to lauryl alcohol of 1.25:1, the reactants itaconic anhydride and lauryl alcohol are accurately weighed on a balance, and then the catalyst sodium acetate is prepared and added to a three-necked flask together, so that the amount of sodium acetate is 1% of the total mass of itaconic anhydride and lauryl alcohol, and then stirred at 70°C for 3 hours. After the reaction is completed, n-hexane is added according to the mass volume ratio of the above reaction solution (the "system" in Table 1) to n-hexane of 1g:1mL, and then stirred for 10 minutes, then cooled and filtered, and the solid is recrystallized three times with ethanol to purify the intermediate product molecule. The yield of the obtained product is shown in Table 1. The yield is calculated as follows: For the system after the reaction, assuming that the reaction is complete, the theoretical mass m1 of the product is calculated according to the stoichiometric coefficient, and the mass m2 of the product is finally obtained by experiment, and the yield is wt (%). , then the yield calculation formula is as follows:

[0049] wt = (m2 / m1)*100% (Formula 1).

[0050] Example 2

[0051] An intermediate molecule for preparing a surfactant, the preparation method of which is basically the same as that of Example 1, except that the polyacid used is maleic acid, and the other conditions are shown in Table 1 or Example 1.

[0052] Example 3

[0053] An intermediate molecule for preparing a surfactant, the preparation method of which is basically the same as that of Example 1, except that the polyacid used is fumaric acid, and the other conditions are shown in Table 1 or Example 1.

[0054] Example 1′

[0055] An intermediate molecule for preparing a surfactant, the preparation method of which is basically the same as that of Example 1, except that the molar ratio of itaconic anhydride to lauryl alcohol in this example is 1:1, and the other conditions are shown in Table 1 or Example 1.

[0056] Example 2′

[0057] An intermediate molecule for preparing a surfactant, the preparation method of which is basically the same as that of Example 1, except that the molar ratio of itaconic anhydride to lauryl alcohol is 1.5:1 in this example, and the other conditions are shown in Table 1 or Example 1.

[0058] Example 3′

[0059] An intermediate molecule for preparing a surfactant, the preparation method of which is basically the same as that of Example 1, except that the content of sodium acetate is 0.75%. The other conditions are shown in Table 1 or Example 1.

[0060] Example 4′

[0061] An intermediate molecule for preparing a surfactant, the preparation method of which is basically the same as that of Example 2, except that the content of sodium acetate is 1.25%. The other conditions are shown in Table 1 or Example 2.

[0062] Example 5′

[0063] An intermediate molecule for preparing a surfactant, the preparation method of which is basically the same as that of Example 2, except that the mass volume ratio of the mixed system of polyacid, fatty alcohol and sodium acetate to n-hexane is 0.5 g / mL, and the other conditions are shown in Table 1 or Example 2.

[0064] Example 6′

[0065] An intermediate molecule for preparing a surfactant, the preparation method of which is basically the same as that of Example 2, except that the mass volume ratio of the mixed system of polyacid, fatty alcohol and sodium acetate to n-hexane is 1.5 g / mL, and the other conditions are shown in Table 1 or Example 2.

[0066] Example 7′

[0067] An intermediate molecule for preparing a surfactant, the preparation method of which is basically the same as that of Example 3, except for the stirring reaction time. In this example, the stirring reaction time is 6 hours, and the other conditions are shown in Table 1 or Example 3.

[0068] Example 8′

[0069] An intermediate molecule for preparing a surfactant, the preparation method of which is basically the same as that of Example 3, except for the stirring reaction time. In this example, the stirring reaction time is 1 hour, and the other conditions are shown in Table 1 or Example 3.

[0070] Example 9′

[0071] An intermediate molecule for preparing a surfactant, the preparation method of which is basically the same as that of Example 3, except for the temperature of the stirring reaction. In this example, the temperature of the stirring reaction is 40° C. The other conditions are shown in Table 1 or Example 3.

[0072] Table 1 shows the conditions and yields of the intermediate products prepared in the examples.

[0073]

[0074] As shown in Table 1, compared with other conditions, Examples 1-3 have the highest yield of the obtained product. However, Example 1' has a low yield due to too low acid dosage; Example 2' has a low yield due to too much acid dosage; Example 3' has a low yield due to too much catalyst dosage; Example 4' has a low yield due to too low catalyst dosage; Example 5' has a low yield due to too low dissolving dosage; Example 6' has a low yield due to too much solvent dosage; Example 7' has a low yield due to too long reaction time; Example 8' has a low yield due to too short reaction time; Example 9' has a low yield due to too low reaction temperature.

[0075] Therefore, the optimal reaction conditions are: 酸 :n 醇 =1.25:1, reaction time 3h, reaction temperature 70°C. Different from other α, β-unsaturated double bond polyacids (anhydrides), itaconic acid also has the function of forming a ring with amino groups, so itaconic anhydride is further selected and mixed with different alcohols to prepare intermediate products. See Examples 4 and 5 for details.

[0076] Example 4

[0077] The same as Example 1, except that lauryl alcohol is replaced by myristyl alcohol, and the other conditions are the same as Example 1 or see Table 2.

[0078] Example 5

[0079] The same as Example 1, except that lauryl alcohol is replaced by oleyl alcohol, and the other conditions are the same as Example 1 or see Table 2.

[0080] Table 2 Reaction materials and conditions of Examples 1, 4, and 5

[0081]

[0082] From the yield results of each example in Table 1-2, it can be seen that the conditions of the examples are more favorable for esterification. The obtained lauryl itaconate, myristic itaconate and oleyl itaconate were used for the next step of salt formation.

[0083] Then, the intermediate product of the above example is further salted with alkali to prepare a surfactant, as shown in Examples 6-8.

[0084] Example 6

[0085] A green surfactant, the preparation method of which is as follows: the molar ratio of the intermediate product prepared in Example 1 to potassium hydroxide is 1:1, the intermediate product prepared in Example 1 and potassium hydroxide are accurately weighed with a balance, mixed, ethanol is added, reacted at 60° C. for 30 minutes, and the solvent is evaporated to obtain a green surfactant. The mass volume ratio of the total mass of the intermediate product and potassium hydroxide to the mass volume of ethanol is 60 mg / mL.

[0086] Example 7

[0087] A green surfactant, the preparation method of which is as follows: the molar ratio of the intermediate product prepared in Example 4 to potassium hydroxide is 1:1, the intermediate product prepared in Example 1 and potassium hydroxide are accurately weighed on a balance, mixed, ethanol is added, reacted at 60° C. for 30 minutes, and the solvent is evaporated to obtain a green surfactant. The mass volume ratio of the total mass of the intermediate product and potassium hydroxide to the mass volume of ethanol is 60 mg / mL.

[0088] Example 8

[0089] A green surfactant, the preparation method of which is as follows: the molar ratio of the intermediate product prepared in Example 4 to potassium hydroxide is 1:1, the intermediate product prepared in Example 1 and potassium hydroxide are accurately weighed on a balance, mixed, ethanol is added, reacted at 60° C. for 30 minutes, and the solvent is evaporated to obtain a green surfactant. The mass volume ratio of the total mass of the intermediate product and potassium hydroxide to the mass volume of ethanol is 60 mg / mL.

[0090] Example 10′

[0091] A green surfactant, whose preparation method is basically the same as that of Example 6, except that the molar ratio of lauryl itaconate to KOH is changed. In this embodiment, the molar ratio of lauryl itaconate to KOH is 1:1.05.

[0092] Example 11′

[0093] A green surfactant, whose preparation method is basically the same as that of Example 7, except that the type of solvent is changed. In this example, the solvent used is methanol, and the amount used is the same as that of Example 7.

[0094] Example 12′

[0095] A green surfactant, whose preparation method is basically the same as that of Example 8, except that the reaction temperature is changed. In this example, the reaction temperature is 50°C.

[0096] Example 13′

[0097] A green surfactant, whose preparation method is basically the same as that of Example 7, except that the reaction time is changed. In this example, the reaction time is 20 minutes.

[0098] Example 14′

[0099] A green surfactant, whose preparation method is basically the same as that of Example 7, except that the type of solvent is changed. In this example, the solvent used is distilled water, and the amount used is the same as that of Example 7.

[0100] Example 15′

[0101] A green surfactant, whose preparation method is basically the same as that of Example 8, except that the molar ratio of lauryl itaconate to KOH is changed. In this embodiment, the molar ratio of lauryl itaconate to KOH is 1:0.95.

[0102] Example 16′

[0103] A green surfactant, whose preparation method is basically the same as that of Example 6, except that the reaction temperature is changed. In this example, the reaction temperature is 70°C.

[0104] Example 17′

[0105] A green surfactant, whose preparation method is basically the same as that of Example 7, except that the reaction time is changed. In this example, the reaction time is 40 minutes.

[0106] The raw materials and yields corresponding to each embodiment are shown in Table 3.

[0107] Table 3 Salt-forming raw materials, conditions, and yields of the examples

[0108]

[0109]

[0110] From the salt yields in the above table, it can be seen that Examples 6-8 have the highest salt formation efficiency, while Example 10′ has a low yield due to excessive use of alkali; Example 11′ has a low yield due to a change in solvent; Example 12′ has a low yield due to too low a reaction temperature; Example 13′ has a low yield due to too short a reaction time; Example 14′ has a low yield due to a change in solvent; Example 15′ has a low yield due to too little use of alkali; Example 16′ has a low yield due to too high a reaction temperature; Example 17′ has a low yield due to too long a reaction time.

[0111] Therefore, the optimal process for salt formation is n 酯 :n KOH =1:1, the solvent is ethanol, the reaction temperature is 60°C, and the reaction time is 30min.

[0112] The above method combined with the optimal process conditions was used to synthesize the potassium salt of lauryl maleate (recorded as Example 9), the potassium salt of myristic maleate (recorded as Example 10), and the potassium salt of oleyl maleate (recorded as Example 11). All products were white solids. Taking the potassium salt of lauryl itaconate as an example, Figure 1 The infrared spectra of the molecule and its two main raw materials, itaconic anhydride and lauryl alcohol (see Figure 1(a) in the middle), the physical display of the product is shown in Figure 1 Middle (b) figure.

[0113] The esterification conditions in Examples 9-11 are the same as those in Example 1, and the salt formation conditions are the same as those in Example 6 except for the raw materials used.

[0114] Performance Testing:

[0115] 1. Performance test of surfactant:

[0116] According to the optimal conditions of esterification reaction and the optimal conditions of salt formation, the potassium salt of lauryl itaconate in Example 6, the potassium salt of myristic itaconate in Example 7, the potassium salt of oleyl itaconate in Example 8, and the surfactants in Examples 9-11 were prepared respectively, and their foaming properties and emulsifying properties were tested. The test method is as follows:

[0117] (1) Foam performance

[0118] The test method is: weigh 0.149g of magnesium sulfate heptahydrate and 0.132g of calcium chloride dihydrate respectively, add deionized water to dissolve, transfer to a 1000mL volumetric flask, dilute to the scale and shake well to prepare 150mg / kg hard water.

[0119] Weigh 3 g of sample in a small beaker, dissolve it in 150 mg / kg hard water, transfer it to a 1000 mL volumetric flask, dilute to the mark, and shake well.

[0120] Determine foam height using the Roche foam meter:

[0121] ① Turn on the constant temperature water bath device, and after reaching the predetermined temperature, start the circulating water pump to stabilize the water temperature in the jacket of the foam measuring device at (40±1)℃.

[0122] ② Rinse the inner wall of the graduated measuring tube with deionized water or distilled water. Rinse thoroughly and then rinse with the test solution.

[0123] ③ Close the piston at the bottom of the graduated tube, use a 50mL pipette to transfer 50mL of test solution preheated to 40℃, and let it flow down along the inner wall of the graduated tube. After it has been left still for 5 minutes, observe the position of the liquid level and increase or decrease the amount appropriately so that the test solution level is exactly at the 50mL scale.

[0124] ④ Fill the dropper with 200mL of test solution, close the piston, and install it to the upper end of the measuring device, so that the outlet of the dropper is placed on the 900mL scale line and in the center of the graduated measuring tube B, and ensure that the dropper is perpendicular to the cross section of the graduated measuring tube B.

[0125] ⑤ Open the piston of the dropper, let the test solution flow down along the center line of the graduated tube B, and foam will be generated. When the test solution has finished flowing, start the stopwatch immediately and record the height of the foam, which reflects the foaming ability; then record the height of the foam after 5 minutes, which reflects the foam stabilization ability. The test results are shown in Table 4.

[0126] (2) Emulsification performance

[0127] Test method: Use a measuring cylinder to accurately weigh 40mL of 1g / L sample solution and put it into a stoppered measuring cylinder. Then use another measuring cylinder to accurately weigh 40mL of GTCC and put it into the same stoppered test tube. Put in a glass stopper, vibrate up and down violently 5 times, let it stand for 1min, then vibrate 5 times again, let it stand for 1min, and repeat this 5 times. Stand on the test bench and immediately record the time with a stopwatch. At this time, the water and oil phases gradually separate, and the water phase slowly appears. When 10mL of the water phase is separated, record the separation time. The test results are shown in Table 4.

[0128] Table 4 Foam and emulsification properties of multifunctional green surfactants

[0129]

[0130]

[0131] It can be seen from the above table that the above six surfactants all have good foaming and emulsifying power.

[0132] 2. Hair care performance test

[0133] (1) Principles of hair care

[0134] Taking maleic acid as an example, the repair mechanism of potassium salt of common α, β-unsaturated double bond polyacid esters is introduced. The specific reaction route is as follows:

[0135]

[0136] Where R = C n H 2n±1 , n is an integer from 7 to 17.

[0137] It can be seen that the potassium salt of common α, β-unsaturated double bond polyacid esters (maleic acid, fumaric acid type, etc.) can achieve the repair of hair by reacting with the thiol group of hair.

[0138] When the surfactant is a potassium salt of itaconate, its working principle is as follows:

[0139]

[0140]

[0141] Where R = Cn H 2n±1 , n is an integer from 7 to 17.

[0142] In the synthetic route (a), the potassium salt of itaconate has two structures, which can react with sulfhydryl groups to protect the sulfhydryl groups, thereby protecting the hair, and the further formed CS bonds can improve the strength of the hair. In the synthetic route (b), the potassium salt of itaconate with the structural formula (2) can also form a ring with the amino groups in the hair to repair the hair.

[0143] (2) Test of thiol repair rate

[0144] The test method is as follows: the multifunctional green surfactant of the above-mentioned Examples 6-11 is dissolved in water to prepare a 0.5wt% repair solution, and the damaged hair is repaired in the repair solution at 40°C for 20 minutes, and the reaction pH is 7. The restored hair bundle is obtained by incubating healthy Asian black hair (Shanghai Canyu Trading Co., Ltd., 18cm long healthy hair) with 5% thioglycolic acid at pH=9 for 30 minutes, and the bleached hair bundle is obtained by incubating healthy Asian black hair (Shanghai Canyu Trading Co., Ltd., 18cm long healthy hair) with 8% hydrogen peroxide at pH=10 for 40 minutes.

[0145] The free thiol groups of the reduced hair react with excess DNTB at room temperature to generate colored substances, which absorb at 412nm ultraviolet light. mol =13600, according to Lamber-Beer law, A = E mol ·C·L, and L=1. The actual concentration of thiol groups can be obtained by measuring the absorbance (A). This method is the Ellman method, which can quantify the free thiol groups in different hair bundles. The specific operation is as follows: Accurately measure 20 mg of sample hair and soak it in 1.0 mL of reaction buffer composed of 8M urea, 10mM DTNB, 3mM ethylenediaminetetraacetic acid (EDTA) and 0.2M Tris-HCl, pH 8.0. The sample is incubated under N2 for 15 minutes. After centrifugation at 8000rpm for 10 minutes, the supernatant is taken and its absorbance is read at 412nm in the test results of the ultraviolet spectrophotometer. The experiment was repeated 3 times for each group, and the final result was averaged. The thiol content was calculated using the following equation:

[0146] Thiol content (mmol*g -1 )=A*V / (13600*m)*100%.

[0147] Where: A is absorbance, mmol / L; V is volume of clear solution, in L; m is mass of clear solution, in g.

[0148] The thiol content of the damaged hair bundle is a, and the thiol content of the hair bundle after repair by various raw materials is b. The protection rate (%) is calculated using the following equation, as shown in the following formula:

[0149] Protection rate = (ab) / a*100%.

[0150] The content of free thiol groups after different hair sample treatments is shown in Table 5:

[0151] Table 5 Hair care properties after surfactant treatment prepared in Example

[0152]

[0153]

[0154] As can be seen from the above table, the above six surfactants are all very effective in repairing restored hair strands, and the maleic acid type and itaconic acid type have similar effects on thiol repair.

[0155] (3) Friction coefficient test

[0156] The test method is as follows: 40 hairs are randomly selected from each group of the restored hair bundles and bleached hair bundles treated with the surfactants prepared in Examples 6-11 in the above (2) thiol repair rate test experiment, 20 of which are tested using an XCF-1A fiber friction coefficient tester, and the average value of each group is calculated based on the dynamic friction coefficient obtained in the test, which is used as a reflection of the smoothness of each group of hair. The results are as follows: Figure 2 shown.

[0157] From the test results of single fiber friction, it can be seen that the reactive surfactant synthesized in the present invention has a highly significant effect on restoring the smoothness of hair. In addition, itaconate-type surfactants are slightly better than maleate-type surfactants in restoring the smoothness of hair surface. In addition, itaconate-type surfactants have a significant repair effect on bleached hair (maleate-type surfactants have no repair effect), which we attribute to the fact that itaconate-type surfactants have an additional cyclization effect with amino groups in hair compared to maleate-type surfactants.

[0158] (4) Hydrophobic performance test

[0159] The test method is as follows: 20 hairs are randomly selected from each group of the reduced hair bundles and bleached hair bundles treated with the surfactants prepared in Examples 6-11 in the above (2) thiol repair rate test experiment, and their contact angles are measured using an OCA 40 optical contact angle meter and the average value is calculated. The average degree is used as the embodiment of its hydrophobic performance. The test results are shown in Figure 3 .

[0160] From the comparison results of the contact angles, it can be seen that the reactive surfactant synthesized by the present invention has a highly significant effect in restoring the hydrophobicity of hair. Compared with maleic acid esters, itaconates have an additional reaction with amino groups in hair, which makes itaconates more effective in restoring the hydrophobicity of hair, and it also has the additional function of repairing the hydrophobicity of bleached hair.

[0161] In the present invention, the protection rate of potassium salt of itaconate for reduced thiol groups is comparable to that of potassium salt of maleate, but due to the additional cyclization reaction of potassium salt of itaconate with amino groups in hair, the improvement of hydrophobicity and smoothness of hair is more significant, and the repair of bleached hair is achieved.

[0162] The above is only a preferred embodiment of the present invention, and the present invention is not limited to the above embodiments. It is understood that other improvements and changes directly derived or associated by those skilled in the art without departing from the spirit and concept of the present invention should be considered to be included in the protection scope of the present invention.

Claims

1. A multifunctional green surfactant, characterized in that: The surfactant is obtained by reacting a polyacid or a polyacid anhydride with a long-chain fatty alcohol and then forming a salt; The polyacid is a polyacid with α, β-unsaturated double bonds; The polyacid anhydride is an anhydride of α, β-unsaturated double bonds; The long-chain fatty alcohol refers to a C8-22 fatty alcohol.

2. The multifunctional green surfactant according to claim 1, characterized in that: The polyacid includes at least one of maleic acid and fumaric acid; and the polyacid anhydride includes itaconic anhydride.

3. The multifunctional green surfactant according to claim 1, characterized in that The long-chain fatty alcohol is a C12-18 fatty alcohol.

4. The multifunctional green surfactant according to claim 1, characterized in that The long-chain fatty alcohol includes at least one of n-octanol, lauryl alcohol, myristyl alcohol and oleyl alcohol, and the long-chain fatty alcohol is preferably lauryl alcohol.

5. A method for preparing the surfactant according to any one of claims 1 to 4, characterized in that: The preparation method is: S1: Mix the polyacid, long-chain fatty alcohol and catalyst, heat and stir to react, add solvent I to the reaction solution and stir again, cool, filter and obtain a solid, recrystallize and purify to obtain an intermediate product; S2: After mixing the intermediate product with alkaline solution, adding solvent II to heat and react, evaporating the solvent to obtain a surfactant.

6. The preparation method according to claim 5, characterized in that: In step S1, the unit molar ratio of the polyacid to the long-chain fatty alcohol is 2:1-1:1, preferably 1.8:1-1.2:1, and most preferably 1.25:1; the amount of the catalyst is 0.75%-1.25% of the total mass of the polyacid and the long-chain fatty alcohol, preferably 0.9%-1.1%, and most preferably 1%; the catalyst is sodium acetate; the heating and stirring temperature is 40-80°C, preferably 70°C; the heating and stirring time is 1-6h, preferably 3h.

7. The preparation method according to claim 5, characterized in that: In step S1, the solvent I is selected from at least one of n-heptane, isohexane, n-hexane, n-octane, and petroleum ether; the mass volume ratio of the reaction solution to the solvent I g / mL is 0.5-1.5:1; the mass volume ratio of the reaction solution to the solvent I g / mL is preferably 0.75-1.25:1, and the mass volume ratio of the reaction solution to the solvent I g / mL is most preferably 1:1; the re-stirring time is 8-12 min, preferably 10 min.

8. The preparation method according to claim 5, characterized in that: In step S2, the molar ratio of the intermediate product to the alkali solution is 1:0.95-1:1.05, most preferably 1:1; the alkali solution is sodium hydroxide.

9. The preparation method according to claim 5, characterized in that: In step S2, the mass volume ratio of the intermediate product and the alkali solution to the solvent II is 10-100:1 in mg / mL; the solvent II is selected from at least one of ethanol, methanol, and distilled water; and the solvent II is preferably ethanol.

10. The preparation method according to claim 5, characterized in that: In step S2, the temperature of the heating reaction is 50-70°C, preferably 60°C; the time of the heating reaction is 20-40min, preferably 30min.

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