| Gemini surfactants consist of two amphiphilic molecules linked covalently by a spacer at the head groups, or very closed to them. It has good properties as wetting agent or penetrating agent. It is a good idea to introducing the design idea of Gemini surfactant in leather fatliquoring agent. It will play an important role in development and utilization of innovative leather chemical products.In this paper, lauryl alcohol maleic acid monoester was prepared from lauryl alcohol and maleic under the catalysis of sodium acetate anhydrous. Three kinds of fatty acid, including using lauric acid, oleic acid, stearic acid, were used to prepare fatty acid monoethanolamides with maleic anhydride under the catalysis of sodium methoxide. Two hydrophobic chains were formed by esterification reaction of fatty monoethanol amide and lauryl alcohol maleic acid monoester. Then, three kinds of fatty monoethanol amide maleic acid diesters (F-MMD) were obtained. In order to introduce hydrophilic group in F-MMD, F-MMD and sodium bisulfite were used to prepare three kinds of fatty acid monoethanolamine sulfosuccinate diester salts (F-GSS).Acid value was selected as evaluation index to optimize process parmeters of the single esterification reaction, including the ratio of lauryl alcohol and maleic anhydride, reaction temperature and reaction time. Acid value was selected as evaluation index to optimize process parmeters of the double esterification reaction, including the ratio of fatty monoethanol amide and lauryl alcohol maleic acid monoester, reaction temperature and reaction time. Sulfonated rate was selected as evaluation index to optimize process parmeters of the sulfonation reaction, including the ratio of F-MMD and sodium bisulfite, dosage of phase transfer agent, reaction temperature and reaction time. The dodecanoic acid monoethanolamine sulfosuccinate diester salts (D-GSS) was obtained. According to the synthesis processes of D-GSS, oleic acid monoethanolamine sulfosuccinate diester salts (O-GSS) and stearic acid monoethanolamine sulfosuccinate diester salts (S-GSS) were also obtained. The single esterification reaction processes were as following:mole ratio of lauryl alcohol and maleic anhydride was 1:1.05, reaction temperature was 85 ℃, and reaction time was 4 h. The amidation reaction processes were as following:mole ratio of monoethanolamine and fatty acid was 0.8:1, reaction temperature was 160 ℃, reaction time was 5 h, adding 0.25 times of monoethanolamine based on the usage of fatty acid with 0.2% sodium methoxide, reaction time was 3 h at 90 ℃. Fatty monoethanol amide was obtained. The double esterification reaction processes were as following:mole ratio of fatty monoethanol amide and lauryl alcohol maleic acid monoester was 1:1, reaction temperature was 140 ℃, and reaction time was 5 h. The sulfonation reaction processes were as following. mole ratio of F-MMD and sodium bisulfite was 1:1.05, reaction temperature was 150 ℃ (D-GSS was 150 ℃, O-GSS and S-GSS was 160 ℃), dosage of phase transfer agent was 10%, reaction time was 5 h. The structures of the products were characterized by FT-IR and 1H NMR. The results showed that the products were prepared successfully. The surface tension, foaming performance, emulsifying power and permeability of the products were measured. And the results showed that the products can significantly reduce the surface tension, good emulsification ability and permeability, poor foaming performance.According to the synthesis route of F-GSS, rapeseed oil was modified to obtain Gemini fatliquoring agent (GSSF), and synthesis processes were optimized. The amidation reaction processes were as following. Mole ratio of monoethanolamine and rapeseed oil was 3.1:1. Reaction temperature was 160 ℃. Reaction time was 5 h. The dosage of sodium methoxide was 0.2%. Rapeseed oil monoethanol amide was obtained. The double esterification reaction processes were as following. Mole ratio of rapeseed oil monoethanol amide and lauryl alcohol maleic acid monoester was 1:3.1, reaction temperature was 150 ℃, and reaction time was 5 h. The sulfonation reaction processes were as following. Mole ratio of rapeseed oil amides maleic acid diester (C-MMD) and sodium bisulfite was 1:3.5, reaction temperature was 150 ℃, dosage of phase transfer agent was 10%, and reaction time was 4.5 h.The structure of the GSSF was characterized by FT-IR and 1HNMR. GSSF was characterized by emulsion stability, DLS and TEM. Emulsion stability tests showed a satisfied stability of fatliquoring agent. DLS test and TEM test showed that average particle size of fatliquouing agent emulsion was about 30-120 nm. GSSF was applied in the leather fatliquoring process of goatskin garment. The performances of fatliquored leather were measured. The results showed that the physical and mechanical properties of fatliquored leather were comparable with commercial fatliquoring agent. BOD5 and COD of the fatliquoried bath were tested. The results showed that GSSF was easily biodegradable compared with commercial fatliquoring agent. |
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