CAPROLACTAM-BASED FATTY AMIDE AS HYDROGELLING ADDITIVE
The present invention relates to a fatty amide additive carrying a carboxylic acid
ending or in the salt form which is used as hydrogelator for aqueous compositions, in
particular for coatings or adhesives or treatment of fibres or textiles or for detergents,
stripping agents, depolluting agents or flocculating agents.
Various systems which can gel in water are already known and used in various
applications.
FR 2976948 describes a ternary combination of an acid of boron, such as boric
acid, with an N-alkylaidonamide, in particular N-dodecyl-D-glucoanamide, and a
monovalent salt, such as NaCI, in order to obtain gels in a (saline) aqueous medium for
various applications and in particular in detergency.
The known hydrogelators include those based on lysine derivatives, as described
by M.Suzuki et al. in Chem. Soc. Rev., 2009, 38, 967-975, where derivatives used as
organogelators are also described. A description is given, among these derivatives, of
diurea-esters, diamide-esters or amide-urea-esters, starting from lysine.
A review of hydrogelators was carried out by L.A.Estroff et al. in Chemical Reviews,
2004, 104, 3, 1201-1217, with an inventory of the characterization methods and structures
which are known. Conventional amphiphilic derivatives having a hydrophilic head and one
or two hydrophobic chains, bolaamphiphiles having two hydrophilic heads bonded via a
hydrophobic chain, surfactants having a double ionic head separated by a rigid spacer
with two flexible end chains, systems derived from sugars, are singled out, inter alia. It is
recognized that there is no applicable general rule which makes it possible to discover a
satisfactory compromise between hydrophilicity and hydrophobicity of a molecule and
consequently there is no general rule either between the ability to form a gel in an
aqueous medium and the tendency to prevent the precipitation of fibres.
The disadvantage of these hydrogelators is the fact that they are based on amino
acids, which can undergo side reactions and in particular uncontrolled chain elongations,
according to the conditions for the preparation of the said gelators, and can thus affect
their fine structure and consequently their performance of gelator. Furthermore, none of
the documents cited describes or teaches how to obtain amide additives modified by
caprolactam and with improved performance which is a subject-matter of the present
invention to overcome the disadvantages of the state of the art.
Specifically, the present invention is attempting to develop novel amide additives
modified by a caprolactam structure (equivalent to a C6 amino acid) without having
recourse to amino acids condensed with themselves or to acids and amines which react

by polycondensation with by-products to be removed. These modified amides make
possible the use of a preparation process which is simple and practical to carry out; with
the controlled opening of the ring of the caprolactam, in order to avoid side reactions
which are difficult to avoid with an equivalent amino acid and without needing stages of
separation and/or purification of the final product, which exhibits a satisfactory rheological
performance in an aqueous medium, without affecting the performance specific to the
aqueous binders which may be used in association with it.
The first subject-matter of the invention is a hydrogelating additive based on fatty
amide, which additive is the product of the addition reaction (without by-products, as in
polycondensation) of a fatty acid R1CO2H with caprolactam and (which product) carries an
end carboxyl functional group in the acid form or in the form salified by a neutralizing
agent, the said additive consisting of or comprising the mixture of 3 different amide
compounds resulting from the said reaction and which are characterized by the number n
of caprolactam units incorporated, which number is respectively 1, 2 and 3, with a mean
number n of units (mean per molecule) ranging from 0.8 to 3, preferably from 0.9 to 2.75
and more preferably from 0.9 to 2.5. More particularly, the said 3 compounds can be
defined according to the following formula (I) and respectively correspond to n = 1, n = 2
and n = 3
R1-C(=O)-[NH(CH2)5C(=O)-]n-1-NH(CH2)5-CO2M (I)
with M being -H or a cation in the case of the said salified form, the said cation being
related to the said neutralizing agent.
The said fatty acid R1CO2H comprises a number of carbon atoms ranging from 10
to 24, which means that R1 is an alkyl comprising from 9 to 23 carbon atoms which is
preferably linear.
Mention may be made, as suitable examples of R1CO2H, of fatty monoacids, such
as decanoic acid to undecanoic acid, dodecanoic or lauric acid, tridecanoic acid,
tetradecanoic (or myristic) acid, pentadecanoic acid, hexadecanoic acid (palmitic acid),
heptadecanoic acid, octadecanoic acid (stearic acid) or their isomers and their mixtures.
The fatty acid R1CO2H can also comprise, in its structure, an ethylenic
unsaturation, as is the case with oleic acid (9-octadecenoic acid).
R1CO2H can comprise, in its structure, a hydroxyl functional group, that is to say
can be a fatty hydroxy acid, such as 12-hydroxystearic acid, 9-hydroxystearic acid and/or
10-hydroxystearic acid or 14-hydroxyeicosanoic acid, preferably 12-hydroxystearic acid
alone or partially replaced with 9-hydroxystearic acid and/or 10-hydroxystearic acid or 14-
hydroxyeicosanoic acid. R1C2H can simultaneously comprise an ethylenic unsaturation
and an OH functional group, such as for example, ricinoleic acid (or 12-hydroxy-9-

octadecenoic acid) or 14 hydroxyeicosenoic acid. Preferably, the said fatty acid R1CO2H
does not comprise any hydroxyl (OH )or amine functional group or other functional groups
which can react with the caprolactam, in order to avoid any potential side reaction and to
better control the final structure and composition of the said amide additive according to
the invention.
According to a possible option, the said amide additive is in the salified form (form
of carboxylic acid salt) and the said neutralizing agent is selected from organic or
inorganic bases. Mention may be made, as examples of organic bases, of primary,
secondary or tertiary amines, preferably tertiary amines, in order to form a cation M which
is a quaternary ammonium, the counteranion being the carboxylate carried by the amide
chain. Mention may be made, as inorganic base, of an alkali metal hydroxide, such as
LiOH, NaOH or KOH, or an alkaline earth metal hydroxide, such as Ca(OH)2, Mg(OH)2 or
Ba(OH)2.
More particularly, the additive of the invention can be in the form of a micronized
powder, preferably have a volume-average size of less than 50 µm, preferably less than
25 µm. This particle size distribution can be determined directly on the dry powder by
laser diffraction, such as, for example, on the Mastersizer® S from Malvern. This technique
is based on the principle that particles passing through a laser beam diffract the light
according to a different angle as a function of their size: particles having small sizes
diffract at large angles, whereas particles having larger sizes diffract at small angles.
The said additive of the invention can be used in particular in the gel form in water
or as hydrogelator and more preferably at a content by weight of less than 5% and more
preferably still at a content not exceeding 1% by weight, this percentage being defined
with respect to the weight of the water + additive.
The second subject-matter of the invention is a process for the preparation of the
hydrogelating additive according to the invention, which process comprises a stage of an
addition reaction between a fatty acid R1CO2H and caprolactam with a molar ratio of the
said caprolactam with respect to the said fatty acid ranging from 0.8 to 3, preferably from
0.9 to 2.75 and more preferably from 0.9 to 2.5, the said process not comprising any
separation or purification stage.
This reaction is a bulk addition reaction in the molten state which can take place at
a temperature ranging from 200°C to 300°C and under an inert atmosphere or under
pressure ranging from a few bar to a pressure of less than 30 bar. A catalyst can be used
for this reaction, such as, for example, a Lewis acid. After cooling, the product obtained is
micronized by mechanical grinding or by an air jet at a temperature lower than the melting

distribution with a volume-average size of less than 50 µm, preferably less than 25 µm,
measured by laser diffraction, such as, for example, on the Mastersizer® S from Malvern.
Another subject-matter of the invention is an aqueous composition which
comprises, as hydrogelator, at least one additive as defined above or as obtained by the
described process of the invention.
Such an aqueous composition can be an aqueous composition with or without
binder. Without binder, this can correspond to a simple dispersion of the said additive in
the water which operates as hydrogelator. The hydrogelating effect is displayed by an
increase in viscosity with the achievement of a gel, by the fact of the molecular
combinations in the fibrous system formed, with the hydrogelation being a compromise
between the molecular hydrophobicity/hydrophilicity of the additive, on the one hand, and,
on the other hand, between the level of dissolution (limited but sufficient) and a tendency
towards precipitation to be avoided. This can also correspond to a solution or dispersion
of aqueous dispersant or surfactant for the requirements of detergency or of dispersion of
an oily product (oils of vegetable or mineral or hydrocarbon origin) or solid product which
is finely divided (dispersion of resins in particulate form).
The said aqueous composition can be a composition of organic binder which can
be reactive or non-reactive, single-component or two-component, monomer or oligomer or
resin or polymer or mixture of monomers and oligomers or resins or polymers. As it
concerns an aqueous medium, the said binders can be water-soluble, water-dispersible
via their own structure or dispersible in water using a surfactant or dispersant specific for
an aqueous medium.
In particular, the pH of the aqueous composition is basic, preferably of at least 9,
more preferably of at least 10. This pH is adjusted by excess addition of a base, that is to
say addition beyond the simple neutralization of the said end carboxylic acid functional
group of the said additive, and this remains equally valid for the additive in the gel form in
water.
According to a first preferred option, the said composition is an aqueous binder
composition and preferably an aqueous coating composition, in particular an aqueous
varnish, paint or ink composition, or an adhesive composition or a cosmetic composition
or a composition for the treatment of fibres or textiles, with the said hydrogelating additive
being used as rheology additive.
According to another option, the said aqueous composition is a surfactant
composition, in particular a detergent or stripping agent or depolluting agent or flocculating
agent composition. As in the aqueous binder compositions, the said amide additive is

present as hydrogelator in order to gel the applicative composition for reasons specific to
the final use planned for theapplicativecomposition.
Another subject-matter of the invention is the use of an additive as defined above
according to the invention as hydrogelating additive in aqueous compositions. Such a use
has already been described above, in particular in aqueous binder compositions, more
particularly in aqueous coating or adhesive or cosmetic compositions or composition for
the treatment of fibres or textiles, in particular as rhedlogy additive. Another use in
aqueous compositions concerns surfactant compositions and in particular detergent,
stripping agent, depolluting agent or flocculating agent compositions. Finally, the finished
products resulting from the use as hydrogelator of the said additive of the invention, in
particular selected from: a coating or an adhesive or a cosmetic or a treated fibre or a
treated textile or a detergent or a stripping agent or a depolluting agent or a flocculating
agent, are also covered by the invention. The hydrogel as product which results from
these uses is also covered by the invention.
The examples which follow are presented by way of illustration of the invention and
its performance and do not in any way limit this coverage.

II - Examples of the preparation of the caprolactam-based hvdrogelators
Example 1: preparation of the amide A1 by reaction of 1 mol of stearic acid with 1 mol of
caprolactam:
113.16 g of caprolactam (1 mol) and 284.48 g of stearic acid (1 mol) are
introduced, under a stream of nitrogen, into a 1 litre reactor equipped with a thermometer,
a condenser and a stirrer. The mixture is subsequently heated to 250°C, still under a
stream of nitrogen. The reaction is monitored by the viscosity. After 15 hours, the viscosity

value becomes constant (> 0.32 poises or > 32 mPa.s, measured on a Brookfield®
CAP1000 at 120°C) andlhe reaction mixture is cooled to 150°C and then discharged into
a silicone mould. Once cooled to ambient temperature, the product is micronized
mechanically by grinding. A sieving is carried out in order to obtain a fine and controlled
particle size distribution with an average size obtained of 7 µm.
Example 2 : preparation of amide A2 by reaction of 1 mol of stearic acid with 2 mol of
caprolactam:
226.32 grams of caprolactam (i.e., 2 mol) and 284.48 grams of stearic acid (i.e.,
1 mol) are introduced, under a stream of nitrogen, into a 1 litre reactor equipped with a
thermometer, a condenser and a stirrer.
The remainder of the procedure is identical to that described for Example 1.
Ill - Evaluation of the hydroqelatinq performance
1. Formulation for the evaluation of the hydroqelators
99 grams of demineralized water, 1 gram of ground or micronized additive as
prepared according to Examples 1 and 2 (hydrogelator) to be tested and then a few drops
of concentrated sodium hydroxide solution in an amount greater than 4 times, in
equivalence, the carboxylic acid of the hydrogelator to be tested are introduced into a
Erlenmeyer flask equipped with a magnetic bar. The Erlenmeyer flask is subsequently
closed. The mixture is then stirred for more than 5 hours at 85°C in order to have
complete dissolution of the hydrogelating additive and a milky but precipitate-free mixture.
Finally, the mixture is introduced into a test tube and then left standing at 25°C for
24 hours.
Under these preparation conditions, 3 formulations were produced with the amide
A1 of Example 1, the amide A2 of Example 2 and also with stearic acid as comparison
reference. These 3 tests are summarized in the following Table 2.


2. Evaluation of the gel
The 3 formulation tests were evaluated in two ways: first according to the
appearance of the formulations prepared in the test tubes after 24 hours (see Table 3)
and subsequently and in particular according to their viscosities at different shear rates on
a Brookfield® viscometer (see Table 4).



* By way of indication, it should be noted that the results shown for Comparative Test 1
are not very reproducible, given that the formulation is not homogeneous.
In contrast to stearic acid, the formulations obtained with 1% of amide A1 or A2
exist in the gel form characteristic of a hydrogelator.
With regard to the viscosity results, they clearly show that the formulation
comprising the amide A1 (Test 2) is thixotropic but also more viscous than the water or
the formulation comprising the stearic acid.

CLAIMS
1. Hydrogelating additive based on fatty amide, characterized in that it is the product
of the addition reaction of a fatty acid R1CO2H with caprolactam and carries an end
carboxyl functional group in the acid form or in the form salified by a neutralizing agent
and in that the said additive consists of or comprises the mixture of 3 different amide
compounds resulting from the said reaction and which are characterized by the number n
of caprolactam units incorporated, which number is respectively 1, 2 and 3, with a mean
number n of units (mean per molecule) ranging from 0.8 to 3, preferably from 0.9 to 2.75
and more preferably from 0.9 to 2.5.
2. Additive according to Claim 1, characterized in that the said 3 compounds are
defined according to the following formula (I) and respectively correspond to n = 1, n = 2
and n = 3
R1-C(=O)-[NH(CH2)5C(=O)-]n-1-NH(CH2)5-CO2M (I)
with M being -H or a cation in the case of the said salified form, the said cation being
related to the said neutralizing agent.
3. Additive according to Claim 1 or 2, characterized in that the said fatty acid
comprises a number of carbon atoms ranging from 10 to 24.
4. Additive according to one of Claims 1 to 3, characterized in that the said additive is
in the form of a micronized power, preferably having a volume-average size of less than
50 µm, preferably less than 25 µm.
5. Additive according to one of Claims 1 to 4, characterized in that it is in the salified
form and in that the said neutralizing agent is selected from organic or inorganic bases.
6. Additive according to one of Claims 1 to 5, characterized in that it is in the gel form
in water or as hydrogelator and more preferably at a content by weight of less than 5%
and more preferably still at a content not exceeding 1% by weight.
7. Process for the preparation of an additive as defined according to one of Claims 1
to 6, characterized in that it comprises a stage of an addition reaction between a fatty acid
R1CO2H and caprolactam with a molar ratio of the said caprolactam with respect to the

said fatty acid ranging from 0.8 to 3, preferably from 0.9 to 2.75 and more preferably from
0.9 to 2.5, the said process not comprising any separation or purification stage.
8. Aqueous composition, in particular aqueous binder composition, characterized in
that it comprises, as hydrogelator, at least one additive as defined according to one of
Claims 1 to 6 or as obtained by the process as defined according to Claim 7.
9. Composition according to Claim 8, characterized in that it has a basic pH,
preferably a pH of at least 9, more preferably of at least 10.
10. Composition according to Claim 8 or 9, characterized in that it is an aqueous
binder composition, preferably an aqueous coating composition, in particular an aqueous
varnish, paint or ink composition, or an adhesive composition or a cosmetic composition
or a composition for the treatment of fibres or textiles, with the said hydrogelating additive
being used as a rheology additive.
11. Composition according to Claim 8 or 9, characterized in that it is a surfactant
composition, in particular a detergent or stripping agent or depolluting agent or flocculating
agent composition.
12. Use of an additive as defined in one of Claims 1 to 6 as hydrogelating additive in
aqueous compositions.
13. Use according to Claim 12, characterized in that the said additive is used in
aqueous binder compositions, more particularly in aqueous coating or adhesive or
cosmetic compositions for the treatment of fibres or for the treatment of textiles, in
particular as rheology additive.
14. Use according to Claim 12, characterized in that the said additive is used in a
surfactant composition, in particular a detergent or stripping agent or depolluting agent or
flocculating agent composition.
15. Hydrogel, characterized in that it is the product resulting from the use as defined
according to one of Claims 12 to 14 of an additive as defined according to one of Claims 1
to 6 or obtained by a process as defined according to Claim 7.

16. Finished product resulting from the use as hydrogelator of at least one additive as
defined according to one of Claims 1 to 6 or obtained by the process as defined according
to Claim 7, in particular selected from: coating or adhesive or cosmetic or treated fibre or
treated textile or detergent or stripping agent or depolluting agent or flocculating agent.