US 8,188,171 B2  10  9  The pKa of the organic or inorganic cations is advanta› geously between 8 and 12.  The cations and, in particular, the amines corresponding to  the ammoniums advantageously do not have a surfactant  property; however, it is desirable for them to have good solu- bility, sufficient in any case to provide at the concentration of  use the surfactant property of said compounds comprising an  anionic group and advantageously an aqueous-phase polyeth› ylene glycol chain fragment.  The tertiary amines having at most 12 carbon atoms,  advantageously at most 10 carbon atoms, preferably at most 8  carbon atoms per "onium" group (it will be noted that it is  preferred that there is just one onium group per molecule), are  preferred. The amines may comprise other groups and, in  particular, the groups corresponding to the groups of the  amino acids and cyclic ether groups, such as N-methylmor› pholine, or non-cyclic groups. These other groups are advan› tageously in a form which does not react with the isocyanate  groups and do not significantly alter the solubility in the  organic phase.  When the composition according to the invention com› prises the surfactant in anionic form, said surfactant is  capable of reacting with the isocyanate groups. It may thus be  advantageous to use the anionic surfactant according to the  present invention in a neutralised form so the pH induced  during dissolution or bringing-into-contact in water is at least  equal to 3, advantageously to 4, preferably to 5 and at most  equal to 12, advantageously to 11, preferably to 10. However,  this neutralisation is not necessary if most of the isocyanate  groups of the (poly)isocyanate composition are masked, as  will be mentioned hereinafter.  when E represents phosphorus, it is desirable to use  monoester and diester mixtures in a molar ratio of between  ‰o and 10, advantageously between… and 4. Such mixtures  may further comprise from 1 % to approximately 20%, but  preferably no more than 10%, by mass of phosphoric acid,  and from  O  to 5% of pyrophosphoric acid esters. Advanta› geously, the phosphoric acid is at least partly salified so as to  fall within the recommended pH ranges.  In monoesters and diesters, a portion of the oxyethylene  groups may be replaced with oxypropylene groups. Never› theless, the majority of the groups are preferably oxyethylene  groups.  The presence of triester compounds is possible, provided  that these compounds are not too light. In general, at least one  of the three ester groups has to have a carbon number greater  than 5, preferably greater than 6, or at least two of the three  ester groups have to have a carbon number greater than 2.  The surfactants of the above-defined Formula  (I) may be  kept in their acid form (the charge o- in this case being  replaced by the OH group) if they are introduced into the  polyisocyanate formulation after the isocyanate group mask› ing reaction.  According to a second embodiment, the surfactant is a  nonionic surfactant.  In general, if a nonionic surfactant is used, it has hydro› philic groups such as, for example, oxyethylene groups in  sufficient number, generally greater than about 10. This sur› factant also has a hydrophobic portion which may be selected  from the aromatic groups carrying aliphatic chains or simply  from aliphatic chains having a number of carbon atoms  between 8 and 50. Other hydrophobic units such as silicone or  fluorinated units may also be used for specific applications.  There may be cited, by way of non-limiting examples, the  derivatives of polyoxyalkylene esters of fatty acids, ethoxy- Generally, the preferred (poly )isocyanates are the products  ofhomocondensation or heterocondensation of the following  The compounds may, for example, be polyisocyanates sold  by Rhodia under the name "Tolonatefi".  The polyisocyanate compounds may also comprise true  carbamate groups (R---0-C(=O)-NH$_{2}$ )  or preferably  cyclic epoxy groups or carbonate groups.  The preferred (poly)isocyanates are selected from the  homocondensation or heterocondensation products of alky› lene diisocyanate including, in particular, "biuret"-type and  "trimer" -type products or even "prepolymers" having an iso- cyanate group including, in particular, urea, urethane, allo› phanate, ester, amide, acylurea, isocyanurate, oxadiazinetri› one, imino-dimer, imino-trimer, (iminotriazadione), imino› oxadiazinedione (also known as asymmetrical trimer),  diazetidinedione (also known as dimer) groups and from the  mixtures containing the same.  The (poly)isocyanate composition included in the compo- sition according to the invention consists of any isocyanate  and polyisocyanate, alone or mixed with one or more isocy› anates and/or polyisocyanates. The term "(poly)isocyanate"  must be understood in this context as encompassing the terms  "isocyanate" and "polyisocyanate".  Thus, the ratio by mass between the composition of (poly)  isocyanates and said surfactant( s) is advantageously at least  equal to 1 %, preferably 2%, advantageously 4%, and at most  equal to 30%, preferably to 20%, advantageously to 10%.  Thus, this ratio by mass is advantageously between 1  % and  30%, preferably between 2% and 20%, advantageously  between 4% and 10%.  If the surfactant corresponds to one of the above-defined  Formulae  (I), (II), (II’) or (III), it is also desirable for the  amount of said surfactant(s) present in the composition  according to the invention to correspond to a value ofbetween  10-$^{2 }$and 1, advantageously between 5. 10-$^{2 }$and 0.5 atoms of  E per litre of solution.  Said amount is at least equal to 0.1 %, preferably at least  equal to 0.25%, more particularly at least equal to 5% by  weight based on the weight of the composition of (poly)  isocyanates.  Thus, the amount of surfactant or the mixture of surfactants  has to be relatively low in relation to the composition of  (poly)isocyanates. This amount is advantageously less than  20% by weight based on the composition of (poly)isocyan› ates, preferably less than 15% by weight, and more preferably  less than 10%, for example less than 8% by weight, or even  less than 6% by weight.  As indicated hereinbefore, the presence of surfactant in the  composition according to the invention allows the impact  resistance properties to be improved and the hardness/flex› ibility compromise to be optimised. In the present invention,  the object of the surfactant is therefore not to obtain an emul- sion, still less to obtain a stable emulsion.  According to the invention, use may also be made of a  mixture of (neutralised or non-neutralised) anionic surfac› tants and/or nonionic surfactants.  Particularly preferred is a surfactant selected from one of  the condensates of poly( ethylene oxide) and/or poly(propy› lene oxide) with alcohols, polyols, alkylphenols, fatty acid  esters, fatty acid amides and fatty amines, and sugars, in  particular sugar esters.  lated alkylphenols, ester-phosphates having a polyalkyloxy  alkylene glycol chain (such as polyethoxy and/or propoxy  ethylene glycols, for example) and tristyrylphenols having a  polyethylene oxide chain. 