Note: Descriptions are shown in the official language in which they were submitted.
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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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~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
% ~ % % %
- 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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2~7~95~
~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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Tabl~ 2:
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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