CA2071957A1

CA2071957A1 - Process for making salts of sulphonated fatty acid glycerine esters

Info

Publication number: CA2071957A1
Application number: CA002071957A
Authority: CA
Inventors: Bernd Fabry; Frank Wangemann; Michael Schaefer
Original assignee: Individual
Current assignee: Henkel AG and Co KGaA
Priority date: 1989-12-15
Filing date: 1990-12-07
Publication date: 1991-06-16
Also published as: ES2073158T3; DE3941365A1; DE59009306D1; EP0594574B1; JPH05502221A; EP0594574A1; WO1991009009A1; DK0594574T3; ATE124036T1

Abstract

Aqueous solutions of alkaline, alkaline earth, ammonium and/or amine salts of sulphonated fatty acid glycerine esters are obtained by converting fatty acid glycerine esters with iodine numbers lower than 5 with gaseous sulphur trioxide in reactors operating on the continuous falling film principle followed by neutralisation with aqueous bases and are suitable for the manufacture of surface-active agents.

Description

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;1 `` ` 2C~7~9~7WO 9l/o9eo9 PCT/EP90J02130 A proce~s for tha pro~uat~o~ o~ ~alt~ o~ ~ulfonated ~atty acid glycerol e~ters This invention relates to a procless for the production of aqueous solutions of alkali metal, alkalin~ earth metal, ammonium and/or amine salts of sulfonated fatty acid glycerol esters by reaction of fatty acid glycersl esters having iodine values below 5 with gaseous sulfur trioxide in reactors operating on the continuous falling film principle and subsequent neutralization with aqueous bases and to the use of the sulfonation products for the produc-tion of surfactants.
Sulfonation products of saturated fatty acid glycerol esters are important as textile, fiber and leather auxilia-ries. They are usually produced from vegetable or animal fats of low iodine value which are reacted with sulfuric acid or oleum. However, this process is attended by the serious disadvantage that, after the sulfonation reaction, not only the sulfonic acid formed, but also the sulfuric acid used as solvent has to be neutralized which leads to an undesirably high electrolyte level in the products and to unfavorable performance properties, for example in regard to corrosion behavior.
Accordingly, there has been no shortage of attempts in the past to find another solution to the problem of sul-- fonating saturated fatty acid glycerol esters. For ex-ample, German patents DB 1 186 051 and DE 1 ~43 992 de-scribe two processes in which mixtures of saturated trigly-cerides and lower alkyl esters are subjected to a common discontinuous reaction with gaseous sulfur trioxide. In ; addition to sulfonated triglycerides, the sulfonation products obtained contain ~-sulfofatty acid alkyl esters and have a performance profile which differs unfavorably from that of products obt~ined by sulfonation of triglycer-,..
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95, ~O 91/09009 2 PCT/~P90/02130 ides with oleum. It is specifically pointed out in thepatent specifications that the direct gas-phase sulfonation of saturated triglycerides is not possible on account of the excessive viscosity of the sulfonation products and intensive foaming.
AccordingIy, the problem addressed by the present invention was to provide a process which would enable saturated triglycerides to be directly sulfonated with gaseous sulfur trioxide and which would not ba attended by the disadvantages mentioned above.
The present invention relates to a process for the production of aqueous solutions of alkali metal, alkaline earth metal, ammonium and/or amine salts of sulfonated fatty acid glycerol esters by reaction of fatty acid glycerol esters having iodine values below 5 with gaseous sulfur trioxide in reactors operating on the continuous falling film principle and subsequent neutralization with aqueous bases.
By fatty acid glycerol esters are meant the mono-, di-and triesters and mixtures thereof which are obtainedduring production by esterification of 1 mol glycerol with 1 to 3 mol fatty acid or by the transesterification of tri-glycerides with 0.5 to 2 mol glycerol. Particularly suitable fatty acid glycerol esters are those derived from 2S saturated fatty acids containing 8 to 22 carbon atoms, for example caproic acid, caprylic acid, capric acid, myristic acid, lauric acid, palmitic acid, stearic acid or behenic acid.
Where fats and oils, i.e. natural mixtures of dif-ferent ~atty acid glycerol esters, are used as starting material, the starting products have to be substantially saturated with hydrogen in known manner before the sulfona--~ tion reaction, i.e. hydrogenated to iodine values below 5 and preferably below 2, because otherwise the sulfonation products obtained would show inadequate color quality.

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WO 9~/09009 3 PC~/BP90/02130 Typical examples of suitable starting materials are palm oil, palm kernel oil, olive oil, rapeseed oil, coriander oil, sunflower oil, cottonseed oil, peanut oil, linseed oil, lard oil or lard. However, it has proved to be of particular advantage to use coconut oil or beef tallow as starting material by virtue of their high natural per-centage content of saturated fatty acid~.
The reaction of fatty acid glycerol esters having iodine values b~low 5 with gaseous sulfur trioxide is carried out in reactors operating on the continuous falling film principle. The key feature of reactors of this type is that the starting material to be sulfonated is intro-duced into the reactor by means of suitable fittings, for example in the form of a nozzle or an overflow, in such a way that it runs down the wall of the reactor in the form of a thin film while the gaseous sulfur trioxide can be introduced either horizontally or vertically thereto. By virtue of the rapid mass transfer and the large sur~ace available for cooling, sulfonation in continuous falling film reactors takes place under moderate conditions and generally leads to a particularly light-colored products.
Reactors of this type are known, for example, from DE 2 138 038; a comprehensive description can also be found in J.
Falbe (Ed.), "Surfactants in Consumer Products", Springer Verlag, Berlin, 1987, pages 61 0t ~g. However, in addi-tion to this known advantage of continuous falling film reactors, it has surprisingly been found that such substan-ces as, for example, saturated fatty acid glycerol esters, which do not lend themselves to discontinuous sulfonation, for example in stirred tanks, on account of viscosity and foaming problems, can be reacted with gaseous sulfur tri-oxide.
For gas-phase sulfonation in the continuous falling film reactor, the sulfur trioxide is diluted with an inert ~ 35 gas, preferably air or nitrogen, and is used in the form of :
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a gas mixture containing th~ sulfonating agent in a concen-tration of 1 to 8% and, more particularly, 2 to 5% by volume.
The gaseous sulfur trioxide is used in a ratio of 0.5 to 5.0 mol to 1 mol fatty acid glycerol ester. However, it is of advantage to use the S03 in ratios of 2.0 to 3.0 mol to 1 mol ester because products having unsatisfactory sur-face-active properties are obtained alt lower concentrations of the sulfonating agent while unsatisfactory S03 absorption by the ester is observed at higher c:oncentrations.
The sulfonation reaction is carried out at tempera-tures of 25 to 98C. However, since the starting materials are generally prsent as solids or viscous liquids at room temperature, it is advisable to select reaction tempera-tures of 50 to 85C because adequate pumpability and the formation of a thin falling film in the reaction are both guaranteed in this way.
The acidic sulfonation products obtained during the sulfonation reaction are neutralized with aqueous bases, the pH value being kept between 6.5 and 7.5. Suitable bases for neutralization are alkali metal hydroxides, such as sodium, potassium and lithium hydroxide, alkaline earth metal oxides and hydroxides, such as magnesium oxide, calcium oxide and calcium hydroxide, ammonia, mono-, di-and tri-C2~-alkanolamines, for example mono-, di- and tri-ethanolamine and also primary, secondary or tertiary C14 alkyl amines. The neutralization bases are used in par-ticular in the form of 25 to 50% by weight aqueous solu-tions, sodium hydroxide solutions being preferred.
In one preferred embodiment of the process according to the invention, the acidic sulfonation products may be subjected before neutralization to an additional after-reaction over a period of 5 to 60 minutes and pre~erably 15 to 30 minutes at a temperature of 25 to 90-C and preferably at a temperature of 50 to 80-C. A reductioD in the unsul-, , .

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WO 91/09009 5 PC~/~P9~/0~130 fonated components can be obtained in this way.
The sulfonation product is a complex mixture which essentially contains mono-, di- and triglyceride sulfonates with a sulfonic acid group in the ~-position. ~-Sulfonated fatty acids, glyceride sulfates, glycerol sulfates, glycer-ol and soaps are formed as secondary produ~ts.
After neutralization, the sulfonation products are present in the form o~ light-colored, cream-like pastes so that bleaching is generally unnecessary. However, the products can be further lightened in color in known manner by addition of hydrogen peroxide or sodium hypochlorite solution. 0.2 to 2.0% by weight hydrogen peroxide, expr~s-sed as 100% by weight substance, or corresponding quan-tities of sodium hypochlorite, based on the solids content in the solution of the sulfonation products, may be used for this purpose. The pH value of the solutions may be kept constant using suitable buffers, for example sodium phosphate or citric acid. In addition, preservatives, for example formaldehyde solution, p-hydroxybenzoate, sorbic acid or other known preservatives, may be adcled to stabil-ize the solutions against bacterial contamination.
The products are distinguished by the distinct reduc-tion in the surface tension of water and promote the wetting of solid interfaces with water. They are also suitable for emulsification of fats and oils in aqueous systems.
Accordingly, the invention also relates to the use of ; the reaction products of fatty acid glycerol esters having iodine values below 5 with gaseous sulfur trioxide obtain-able by the process described above for the production of surfactants.
The following Examples are intended to illustrat~ the invention.
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Average composition of the triglycerides (educts) us~d after hydrogenation; percentages in % hy weight -Fatty acid HCHP~ HP ffR HBT
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- 10 ' . . _ _ Caproic acid 1 1 - - -Caprylic acid 8 4 - - -Capric acid 7 5 Lauric acid 48 50 2 - -Myristic acid 17 15 42 1 3 Palmitic acid 9 7 56 4 25 Stearic acid 10 18 - 95 72 Iodine value 2 2 2 2 Legend: HC = hydrogenated coconut oil HPK = hydrogenated palm kernel oil ~ HP = hydrogenated palm oil .` 25 HR = hydrogenated new rapeseed oil HBT = hydrogenated beef tallow ~xample3 1 to 5 General proaedure for the co~tinuous sulfonation of ~atu-rated fatty acid glycerol esters In a con~inuous falling film reactor (length 120 cm, cross-section 1 cm, educt throughput 600 g/h) with jacket cooling and lateral introduction of S03 gas, 5 mol of a -! fatty acid glycerol ester having an iodine value below 5 were reacted with 5.0 to 15.0 mol gaseous sulfur trioxide at T = 30 to 80C. The fatty acid ~lycerol ester was sprayed into the reactor through a nozzle having a 0.2 cm . .

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~O 91~09009 7 PCT/BP90/02130 diameter orifice in such a way that the educt formed a continuous thin film (layer thickness less than 0.1 cm) along the wall of the reactor. The sulfur trioxide was driven out by heating from a corresponding quantity of 65%
by weight oleum, diluted with nitrogen to a concentration o~ 2~ by volume and introduced laterally at the head of the reactor. The acidic sulfonatio~ product was then continu-ously neutralized with aqueous 25% by weight sodium hydrox-ide at pH 6.5 to 7.5. ~he chara,cteristic data o~ the Examples are set out in Table 2.
~he anionic surfactant content (WAS) and the unsul fonated components (US) were determined in accordance with the DGF-Einheitsmethoden (DGF Standard Methods), Stuttgart 1950-1984, H~ 10 and G~ 6b. The sulfate content was calculated as sodium sulfate while the water content was determined by the Fischer method. The Klett color value was determined without bleaching. The measurement was carried out at a concentration of 5% by weight anionic surfactant and at pH 7 using a 1 cm round cuvette and a blue filter (400 to 465 nm).

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Characteristic data of Examples 1 to 5 .
Percentages as % by weight ~
Ex. Educt SO3 T WAS US So~2 H20 Color mol C mEqJg % % % Xlett 1.1 HC 1.0 30 0.032 23.7 2.6 56.9 30 1.2 HC 1.0 80 0.042 25.9 0.9 54.6 35 1.3 HC 2.0 30 0.014 6.2 1.8 84.7 41 1.4 HC 2.0 80 0.028 8.4 2.0 77.0 44 1.5 HC 3.0 80 0.039 6.8 3.6 73.6 51 2.1 HPK 1.0 30 0.035 24.1 2.4 57.1 28 2.2 HPK 2.0 80 0.026 8.9 2.1 76.7 39 3.1 HP 2.0 80 0.049 8.0 1.1 60.4 41 3.2 HP 3.0 80 0.050 4.0 2.1 71.0 51 4.1 HR 1.0 80 0.040 9.9 1.5 50.5 39 4.2 HR 2.0 80 0.047 8.0 1.7 61.9 49 5.1 HBT 1.0 80 0.043 9.2 0.7 50.9 32 5.2 HBT 2.0 80 0.050 7.4 1.0 62.5 44 5.3 HRT 3.0 80 0.048 3.9 2.2 70.1 51 Legend: S03 = Quantity of S03 used in mol/mol fatty acid ester , ~ :. . , ~ ,:

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Example 1.2 was repeated. However, the crude sulfona-tion product was after-reacted for 30 minutes at 80C after leaving the sulfonation reactor and before neutralization.
The neutralized and after-reacted product had a reduced content of unsulfonated components of 16.7% by weight compared with the non-after-reacted product.

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Claims

WO 91/09009 10 PCT/EP90/02130

1. A process for the production of aqueous solutions of alkali metal, alkaline earth metal, ammonium and/or amine salts of sulfonated fatty acid glycerol esters, charac-terized in that fatty acid glycerol esters having iodine values below 5 are reacted with gaseous sulfur trioxide in reactors operating on the continuous falling film principle and are subsequently neutralized with aqueous bases.

2. A process as claimed in claim 1, characterized in that mono-, di- and triglycerides or mixtures thereof having iodine values below 5 and containing C8-22 fatty acids are used as starting material.

3. A process as claimed in at least one of claims 1 and 2, characterized in that fatty acid glycerol ester and sulfur trioxide are used in a molar ratio of 1:0.5 to 1:5.

4. A process as claimed in at least one of claims 1 to 3, characterized in that the sulfonation reaction is carried out at a temperature of 25 to 90°C.

5. A process as claimed in at least one of claims 1 to 4, characterized in that, before neutralization, the acidic sulfonation product is subjected to an after-reaction for 5 to 60 minutes at a temperature of 25 to 90°C.

6. The use of the aqueous solutions of alkali metal, alkaline earth metal, ammonium and/or amine salts of sulfonated fatty acid glycerol esters having iodine below 5 obtained by the process claimed in any of claims 1 to 5 for the production of surfactants.