FR2712896A1 - Detergent compsns. contg. polyimide builder - Google Patents

Abstract

Detergent compsns. contain a polyimide (I) or a hydrolysate of (I), where (I) has a COO<-> charge density of 0 to 5x10<-4> mole/g, is capable of acquiring a COO<-> charge density of at least 10<-3> mole/g in a wash liquor and is prepd. by thermal polycondensation of one or more amino acids (II) in the presence of an acid catalyst (III), the (III):(II) molar ratio being at least 0.001:1. (III) is selected from: (a) mineral or organic acids with a pKa of 5 or less and precursors of such acids; (b) salts of the acids of (a) with amino acids which may be the same as (II) or different; (c) salts of the acids of (a) with polyimides produced by polycondensation of amino acids which may be the same as (II) or different; and (d) Lewis acids.

Description

The present invention relates to a detergent composition containing a polyimide as it is, capable of generating by hydrolysis within the washing medium a biodegradable polypeptide "builder", or a hydrolyzate of said polyimide, hydrolyzate in the form of a salt or d. 'a polypeptide acid.

The term “builder” is understood to mean any constituent which improves the performance of the surfactants of a detergent composition. Generally speaking, a builder has multiple functions.

- it ensures the removal of unwanted ions, in particular alkaline earth metal (calcium, magnesium) within a washing medium, by sequestration, complexation or precipitation to prevent the precipitation of anionic surfactants,
- it provides a reserve of alkalinity and ionic strength,
- it keeps the dirt extracted in suspension,
- it prevents mineral encrustation in the laundry.

Detergent compositions containing a polyimide obtained in particular by polycondensation of aspartic acid, capable of generating by hydrolysis within the washing medium a polypeptide "builder", or containing a hydrolyzate of said polyimide are already known.

It has been observed that the hydrolysates of the polysuccinimides obtained by polycondensation of aspartic acid, used in these compositions, exhibit a biodegradability in natural medium generally not exceeding 75% (EP-A-. 511 037).

The Applicant has now found detergent compositions exhibiting excellent primary and secondary detergency properties, compositions containing a polyimide, in particular a polyimide derived from aspartic acid, or a hydrolyzate of said polyimide which is at least 90% biodegradable.

The term “detergent composition” denotes according to the invention washing machine detergents, dishwasher detergents or any other washing product for household use.

The term “laundry bath” or “washing medium” is understood to mean the aqueous solution of laundry (detergent composition) present in the washing machine during the washing cycles; the amount of detergent present is that recommended by the manufacturer; this is generally less than 20 g / liter; the pH of such a solution is greater than 9.

According to the invention, it is a detergent composition containing a polyimide having a load density COO- which may range from 0 to 5 x 0 ~ 4 mole / g of polymer and capable of acquiring a load density in the washing bath. COO- at least equal to 10-3 mole / g of polymer or a hydrolyzate of said polyimide, polyimide derived from thermal polycondensation of at least one amino acid, then optionally hydrolysis, said composition being characterized in that said polyimide is obtained by polycondensation thermal of at least one amino acid in the presence of at least one "acid catalyst" consisting of an inorganic or organic acid of pk, less than or equal to 5, preferably less than or equal to 3, of a precursor of a of these acids, of a salt of these acids and of an amino acid similar to or different from that or those used, of a salt of these acids and of a polyimide derived from the polycondensation of at least one amino acid similar to or different from that or those implemented o u from an acid of
Lewis, according to an “acid catalyst” I amino acid molar ratio of at least 0.001, preferably of the order of 0.005 to 10 and very particularly of the order of 0.01 to 5.

The term “acid precursor” is understood to mean any product which releases at least one of the above acids under the polycondensation operating conditions; this release can be obtained thanks to the temperature or by the action of the water forming in situ.

In the definition of the mole of acid or acid equivalent, the proton will be taken as elementary entity in the case of acids, acid precursors or acid salts; in the case of an amino acid or polyimide salt, the elementary entity considered will be the NH3 + function; in the case of Lewis acids, the elementary entity considered will be the molecule.

In the definition of the amino acid mole, the molecule will be taken as the elementary entity.

The term “acids” will be understood hereinafter to mean the acids, the acid precursors and the acid salts not derived from amino acids mentioned above as catalysts; The term “amino acid salts” or “aspartic acid salts” will be understood to mean the salts derived from inorganic or organic acids and from amino acids or from aspartic acid; the term “polyimide salts” will be understood to mean the salts derived from mineral acids or organic and a polyimide derived from the polycondensation of amino acids.

Among the amino acids which can be used to carry out the invention, there may be mentioned aspartic acid or glutamic acid taken alone or as a mixture with one another in any proportions or as a mixture with another amino acid (for example up to 15% by weight, preferably less than 5% by weight of glycine, alanine, valine, leucine, isoleucine, phenylalanine, methionine, histidine, proline, lysine, serine, threonine, cysteine, ...)
The preferred amino acid is aspartic acid. When an "amino acid salt" is used, this is preferably an "aspartic acid salt".

Among the “acid catalysts” which can be used, mention may be made of
anhydrous or hydrated sulfuric acid, oleum, SO3, sulfurous acid, acid sulphates such as acid sulphates of potassium, lithium, sodium, quaternary ammonium, etc.
sulfonic acids such as methanesulphonic, benzene sulphonic, trifluoromethanesulphonic, dodecylbenzenesulphonic, paratoluenesulphonic ... amino acids bearing a strong non-carboxylic acid function, such as cysteic acid (amino acid bearing a sulphonic function) phosphoric acid, Phosphoric anhydride, P205, phosphorous acid, acid phosphates such as potassium, sodium, lithium and quaternary ammonium hydrogenphosphates, etc.

. Hydrochloric acid, PC 13, POl5, POOl3 ... nitric acid, hydrofluoric acid halosilanes such as SiC 13, CH3SiCl3 ..

. phosphonic acids such as phosphomethylglycine ...

. salts of aspartic acid and hydrochloric acid, sulfuric, methane sulfonic, paratoluenesulfonic acid polysuccinimide hydrochloride (hydrochloride of polyanhydroaspartic acid) ...

AlOI3, BF3, ZnCI2
The thermal polycondensation operation can be carried out at a temperature of the order of 100 to 250 "C, preferably at a temperature of the order of 150 to 220" C.

Said operation can be carried out at a selected temperature or according to a pre-established temperature profile.

This thermal polycondensation operation can be carried out in bulk or in a solvent medium, at atmospheric pressure, under pressure (preferably up to 20 bar) or under vacuum (preferably greater than 1 mbar).

Thus a mass operation can be carried out, for example. from the amino acid plus the "acid", the "amino acid salt" or the "polyimide salt"; the "acid", "amino acid salt" or the "polyimide salt" can be introduced hot or cold, at atmospheric pressure or under pressure, in the solid or liquid state;. from the amino acid with passage of the "acid" in gaseous form optionally diluted in an inert gas, if said "catalyst acid "is sufficiently volatile at the polycondensation temperature.

The thermal polycondensation operation can also be carried out in a solvent medium, for example. from the amino acid suspended in a solvent, with the addition of the "acid", the "amino acid salt or the" polyimide salt "; the" acid ", the" amino acid salt "or" polyimide salt "can be introduced cold or hot, at atmospheric pressure or under pressure, in solid, liquid or gaseous form (optionally diluted in an inert gas); from the" acid ", the" salt of 'amino acid "or" polyimide salt "suspended or dissolved in a solvent, with the addition of the amino acid.

Among the solvents which can be used, mention may be made of those which are inert with respect to the “acid catalyst” and whose boiling point is greater than or equal to the reaction temperature, such as dibutyl phthalate, diphenyl ether, decaline, tetraline ...

An alternative embodiment of the thermal polycondensation operation in bulk or in a solvent medium consists in using, as the sole constituent of the reaction, an “amino acid salt” instead of an amino acid / “acid catalyst” mixture or an amino acid mixture I "amino acid salt"; said “amino acid salt” is therefore present in bulk or in suspension in a solvent.

A very particularly advantageous embodiment of the thermal polycondensation operation consists in carrying out the latter in bulk, in the presence of an "acid catalyst" chosen from those allowing the reaction medium not to remain in pulverulent form for the entire duration. polycondensation; the polycondensation operation can then be carried out in a single step using simple equipment.

Among the “acid catalysts” allowing this embodiment, mention may be made of potassium and sodium acid sulphates, potassium or sodium hydrogenphosphates.

The polyimide thus obtained can be if necessary separated, filtered, purified and dried.

Depending on the nature of the “acid catalyst” and of the medium, the catalyst can be if necessary separated from the polyimide by washing with water or with the aid of a solvent for said “acid catalyst” and not a solvent for the polyimide.

The polyimide can be purified by solubilization using an aprotic polar solvent (dimethylformamide, formamide, dimethylsulfoxide, etc.) then reprecipitation using a non-solvent compound for said polyimide (water, ether, ethanol, acetone. ..)
The polyimide obtained, separated or not, can then be hydrolyzed preferably by adding a basic agent (alkaline base, alkaline-earth, alkali or alkaline-earth carbonate, etc.) in the presence of water if necessary, in a medium. homogeneous or biphasic; in the case of polysuccinimide derived from aspartic acid, the hydrolyzate thus obtained consists of polyaspartate (sodium for example).

The acid form of the hydrolyzate can be obtained, for example, by neutralization of the salt obtained above by alkaline hydrolysis, using an organic or inorganic acid (in particular HCl); in the case of polysuccinimide derived from aspartic acid,
The hydrolyzate thus obtained consists of polyaspartic acid.

The term “hydrolyzate” is understood to mean, according to the invention, the product obtained by partial or total hydrolysis (by the action of water) of the polyimide formed; this hydrolysis leads, by opening the imide rings, to the formation of amide functions on the one hand and of carboxylic acid functions or carboxylic acid salts on the other hand.

The polyimides or their hydrolysates forming part of the composition of the invention can have a weight average molecular mass of the order of 2000 to 107 and generally of the order of 3500 to 60,000.

The amount of polyimide or hydrolyzate of said polyimide entering into the detergent composition which is the subject of the invention can range from 0.2 to 80%, preferably from 2 to 10%, of the weight of said detergent composition.

Besides this polyimide or polyimide hydrolyzate, there is present, in the detergent composition, at least one surfactant, in an amount which may range from 2 to 50%, preferably from 6 to 30%, of the weight of said detergent composition. .

Among the surfactants entering into the detergent composition which is the subject of the invention, there may be mentioned: - anionic surfactants of the soap and alkali metal type (alkali salts of Cg-C24 fatty acids), alkali sulphonates (C8 - 13 alkylbenzene sulphonates C12 - C16 alkyl sulphonates, sulphated C6 - C16 fatty alcohols, C8 alkylphenols
C13 sulphates), alkali sulphosuccinates (C12 alkyl sulphosuccinates - .......

- nonionic surfactants of the polyoxyethylenated C6 - C12 alkylphenols, oxyethylenated Cg - C22 aliphatic alcohols, ethylene oxide - propylene oxide block copolymers, optionally polyoxyethylene carboxylic amides.

- amphoteric surfactants of the alkyl dimethylbetaine type ...

- catonic surfactants of the type chlorides or bromides of alkyltrimethylammonium, of alkyldimethylammonium, etc.

Various constituents can also be present in the detergent composition of the invention in order to obtain detergents or powdered cleaning products.

May thus additionally be present. in the detergent composition described above: - "builders" of the type
. phosphates at a rate of less than 25% of the total formulation weight,
zeolites up to about 40% of the total formulation weight,
sodium carbonate up to about 80% of the total formulation weight,
. silicates or cogranules of silicate and sodium carbonate up to approximately 40% of the total formulation weight,
. nitriloacetic acid up to approximately 10% of the total formulation weight,
. citric acid, tartaric acid up to approximately 20% of the total formulation weight, the total amount of "builder" corresponding to approximately 0.2 to 80%, preferably 20 to 45% of the total weight of said detergent composition, - bleaching agents of the perborates, chloroisocyanates, N, N, N ', N' tetraacetylethylenediamine (TAED) type up to about 30% of the total weight of said detergent composition, - anti-redeposition agents of the carboxymethylcellulose, methylcellulose, copolymers type polyethylene terephthalate - polyoxyethylene terephthalate having a polyethylene terephthalate / polyoxyethylene terephthalate molar ratio of 25/75 to 90/10, preferably 50/50 to 90/10 derivatives of polyethylene glycol with a molar mass of the order of 600 to 5000, in amounts which may range up to approximately 5% of the total weight of said detergent composition, - anti-incrustation agents of the copolymer type of acrylic acid and maleic anhydrous in an amount which may range up to approximately 10% of the total weight of said detergent composition, - fillers of the sodium sulfate type in an amount which can range up to 50% of the total weight of said detergent composition.

The detergent composition which is the subject of the invention exhibits good efficiency whether in primary detergency or in secondary detergency.

In addition, the incorporation of the polyimide as prepared or its hydrolyzate guarantees the claimed detergent composition a total (at least 90%) and easy biodegradability of this compound at the outlet of the washing machine, during discharges into the natural environment.

The present invention also extends to the uses of the claimed composition.

The following examples are given by way of indication and cannot be considered as a limit of the field and the spirit of the invention.

The viscosity index (IV) given in these examples is measured using a SCHOTT AVS 350 capillary viscometer from a quantity of polysuccimide (PSI) dissolved in 0.5N sodium hydroxide so as to have a concentration of 0.002 g / ml at a temperature of 25 "C.

In these examples, the biodegradability of the hydrolysates (sodium polyaspartate) is measured according to the AFNOR T90-312 standard (in accordance with the international standard
ISO 7827 of October 15, 1984).

The test is carried out using: - an inoculum obtained by filtration of the inlet water from the urban station of Saint
Germain au Mont d'Or (Rhône), as is or after adaptation - of a test medium containing 4x105 bacteria / ml - of a quantity of product to be tested such that the test medium contains an organic carbon concentration of the order of 40ml / g.

The rate of biodegradability is measured as a function of time under the conditions of discharge into river water.

For this measurement, the samples tested were obtained by hydrolysis with a dilute sodium hydroxide solution of the polysuccinimides prepared, until a solution of approximately 6% of sodium polyaspartate was obtained, with a pH of the order of 9 to 11.

The level of biodegradability is characterized by the following two parameters:
. the maximum rate of biodegradation (TMB)
. the time required to go from a rate of biodegradation of 10% to a rate of 90% of the maximum rate of biodegradation (t 10-90).

Example 1
In a 10 liter evaporator flask are introduced - 4009 of aspartic acid Chemie Linz - 2009 of phosphoric acid (85% marketed by Prolabo)
The reagents are heated to 1800C (temperature of the oil bath) at atmospheric pressure.

The temperature is maintained for 4h30mn.

The reaction mass is washed with 101 of water, then with 6 × 4 liters of water and finally with 1 olitres of water.

During the last 7 washes, the medium is stirred using an Ultra Turrax 6 stirrer
After drying under vacuum (4000Pa) for 30 h at 75 ° C., 2909 of polysuccinimide (PSI) are recovered, which corresponds to a yield of 99.4%).

The PSI obtained has a molar mass by weight of the order of 9500.

This polysuccinimide is hydrolyzed as indicated above; the biodegradability of the hydrolyzate is as follows:
TMB: 95%
t 10-90: 8 days
Example 2
In a 2-liter rotary evaporator flask are introduced - 5009 of L aspartic acid - 55.59 of KHSO4
The polycondensation operation is carried out at atmospheric pressure for 7 hours at a bath temperature of 200 ° C.

The product obtained is washed 6 x 61 of water, then dried under vacuum (44 h at 6000 Pa at 70 "C)
310 g of PSI are recovered, which corresponds to a yield of 85%.

The PSI recovered has a viscosity index of 10.89 ml / g.

This polysuccinimide is hydrolyzed as indicated above; the biodegradability of the hydrolyzate is as follows:
TMB: 90%
t 10-90: 28 days
Example 3
Formulation of a polysuccinimide washing machine detergent composition with Dartir obtained in the preceding examples
By dry mixing the various additives, the following solid detergent composition is obtained:

<tb><SEP> COMPOSITION <SEP> OF <SEP> LA <SEP> LAUNDRY <SEP>% <SEP> EN <SEP> WEIGHT
<tb><SEP> Alkylbenzene <SEP> sulfonate <SEP> linear <SEP> 7.5 <SEP>
<tb><SEP> CEMUSOL <SEP> LA <SEP> 90 # <SEP>(<SEP> lauric acid <SEP> 4
<tb><SEP> polyoxyethylenated <SEP> marketed <SEP> per
<tb><SEP> SFOS)
<tb><SEP> Zeolite <SEP> 4 <SEP> A <SEP> 24 <SEP>
<tb> Silicate <SEP> of <SEP> Na <SEP> (SiOp / NavO <SEP> = <SEP> 2) <SEP> 1.5
<tb><SEP> Carbonate <SEP> of <SEP> Na <SEP> 10
<tb><SEP> TAED <SEP> 2
<tb><SEP> Perborate <SEP> of <SEP> Na <SEP> 15
<tb><SEP> Ethylenediamine <SEP> tetraacetic <SEP> 0.1
<tb><SEP> PSI <SEP> 3
<tb><SEP> Tiponal <SEP> DMSXM # <SEP><SEP> 0,1
<tb><SEP> Tiponal <SEP> SOP # <SEP> (brighteners <SEP> marketed <SEP> 0.1
<tb><SEP> by <SEP> CIBA-CEIGY) <SEP>
<tb><SEP> Anti <SEP> silicone <SEP> foam <SEP> 0.2
<tb><SEP> Alcalase <SEP> ll <SEP><SEP> 0.15
<tb><SEP> Savinase <SEP> (enzymes) <SEP> 0.15 <SEP>
<tb><SEP> Sulfate <SEP> of <SEP> Na <SEP> qsp <SEP> 100% <SEP>
<tb>
We will call "control detergent" a detergent of the above composition but not containing
no PSI.

Example 4
The performance of a detergent containing one or the other of the PSI synthesized in Examples 1 and 2, were tested in mineral anti-encrustation.

This effect was measured after 20 washes carried out in the presence of the following test pieces of fabrics: cotton textiles Tesffabric 405 (4). Cotton Krefeld 1 2A (8)
The mineral encrustation is calculated from the ash content (in% relative to the total weight of the cotton) of the fabrics washed, dried and burnt at 950 ° C. for 3 hours.

The incrustation inhibitory effect is assessed by the ratio of ash content with additives / ash content without additives, which appears under the letter T in Table I below.

Table 1
laundry containing the PSI of T% on T% on
Example Testfabric 405 Krefeld 1 2A
1 29 59
2 28 58
Example 5
This example demonstrates the capacity for sequestering calcium ions,
PSI of Examples 1 and 2 after hydrolysis in situ.

The calcium ion sequestration capacity is measured using an electrode having a selective membrane permeable to calcium ions.

First, a calibration curve is drawn using 1 00ml of a solution of
NaCl at 3g / l of pH 10.5 in which quantities of calcium ions varying from 10-5 to 3x10-3 mole / l are added and the potential curve delivered by the electrode is plotted as a function of the ion concentration Ca2 + free.

The PSI is hydrolyzed with a concentrated sodium hydroxide solution until a 20% solution by weight of Na polyaspartate, of pH = 10.5, is obtained. The solution obtained is called a "hydrolyzate".

This solution is diluted until 1009 of an aqueous solution of polyaspartate with a concentration equivalent to 10 g / l of PSI is obtained; ; the pH is adjusted to 10.5 with a concentrated sodium hydroxide solution. 0.39 powdered NaCl is added.

We draw the line [Ca2 +] free / [Ca2 +] fixed = f ([Ca2 +] free).

From this straight line one determines - the complexation constant K of the calcium ions of the polymer - the number So of complexation sites of the polymer, defined by
[Ca2 +] free 1 1
--------------------- = ---- + ---- [Ca2 +] free
[Ca2 +] fixed KSo So
According to this evaluation method, it is found that the polyaspartate obtained by hydrolysis of the PSI of Examples 1 and 2 has the characteristics given in Table 2.

Table 2
PSI of the example So (sites./g of polymer) Log K
1 3.7x10-3 3.2
2 3.6x10-3 3.4
Example 6
This example demonstrates the capacity of PSI to disperse calcium carbonate, after hydrolysis in situ.

In a 100cm3 test tube (height 26cm; diameter 3cm), 29 of precipitated calcium carbonate are dispersed in 100ml of an aqueous solution of pH 10.5 (NaOH) containing 3g / l of NaCl, 3x10-3 mol / l of CaCl2 and the hydrolyzate as prepared in Example 5, at different concentrations.

The level of the sedimentate in cm 3 is measured at the end of 1 mn and the level curve of the sedimentate is plotted as a function of the concentration in ppm of the polymer (expressed in sec).

The curve in FIG. 1 first shows a flocculation phenomenon (too low coverage rate of the polymer particles) then re-stabilization.

This ability to stabilize mineral particles is particularly advantageous since it is known that the latter are at the origin of the encrustation phenomena due to deposits which accumulate on the cotton.

Claims (26)

1) Detergent composition containing a polyimide having a COO- load density which can range from 0 to 5x10-4 mole / g of polymer and capable of acquiring in the washing bath a COO- load density at least equal to 10-3 mole / g of polymer or a hydrolyzate of said polyimide, polyimide derived from the thermal polycondensation of at least one amino acid, then optionally hydrolysis, said composition being characterized in that said polyimide is obtained by thermal polycondensation of at least one amino acid in the presence of 'at least one "acid catalyst" consisting of an inorganic or organic acid of pk, less than or equal to 5, preferably less than or equal to 3, a precursor of one of these acids, a salt of these acids and an amino acid similar to or different from that or those used, a salt of these acids and a polyimide derived from the polycondensation of at least one amino acid similar to or different from that or those used work or a Lewis acid, according to a "acid catalyst" / amino acid molar ratio of at least 0.001. 2) A detergent composition according to claim 1) characterized in that the "acid catalyst" / amino acid molar ratio is of the order of 0.005 to 10. 3) A detergent composition according to claim 2) characterized in that the "acid catalyst" / amino acid molar ratio is of the order of 0.01 to 5. 4) A detergent composition according to any one of claims 1) to 3) characterized in that the "acid catalyst" is. Anhydrous or hydrated sulfuric acid, oleum, SO3, sulfurous acid, potassium acid sulfate, lithium, sodium, quaternary ammonium methane sulphonic acid, benzene sulphonic, trifluoromethanesulphonic, dodecylbenzenesulphonic, paratoluene sulphonic, cysteic acid phosphoric acid, phosphoric anhydride, P205, phosphorous acid, potassium hydrogen phosphate, sodium, lithium, quaternary ammonium. Hydrochloric acid, PC 13, PC 15, POC13. Nitric acid, hydrofluoric acid SiCl3 CH3SiCl3 phosphomethylglycine salts of aspartic acid and hydrochloric acid, sulfuric acid, methane sulfonic acid, paratoluene sulfonic acid polysuccinimide hydrochloride. ICI3, BF3, ZnCI2 5) Detergent composition according to any one of claims 1) to 4) characterized in that the amino acid used is aspartic acid or glutamic acid taken alone or as a mixture with each other in any proportions or as a mixture with another amino acid. 6) A detergent composition according to any one of claims 1) to 5) characterized in that the thermal polycondensation operation is carried out at a temperature of the order of 100 to 250 "C. 7) Detergent composition according to any one of claims 1) to 6) characterized in that the thermal polycondensation operation is carried out in bulk or in a solvent medium. 8) Detergent composition according to any one of claims 1) to 7) characterized in that is used as the only constituent of the reaction an "amino acid salt" instead of an amino acid mixture I "acid catalyst ". 9) Detergent composition according to any one of claims 1) to 8) characterized in that the polycondensation operation is carried out in bulk, in the presence of "an" acid catalyst "chosen from those allowing the reaction medium to remain in the form powdery throughout the duration of the polycondensation. 10) A detergent composition according to claim 9) characterized in that the "acid catalyst" is potassium or sodium acid sulfate, potassium or sodium hydrogen phosphate. 11) Detergent composition according to any one of claims 1) to 10) characterized in that the polyimide obtained by thermocondensation is hydrolyzed into a salt by addition of a basic agent, said salt then being optionally neutralized into an acid by addition of a mineral or organic acid. 12) Detergent composition according to any one of claims 1) to 11) characterized in that the polyimide or its hydrolyzate represents of the order of 0.2 to 80% by weight of said detergent composition. 13) Detergent composition according to any one of claims 1) to 12) characterized in that a surfactant is present in an amount of the order of 2 to 50% by weight of said detergent composition. 14) Use in powdered detergent compositions of a polyimide having a COO- load density which may range from 0 to 5x10'4 mole / g of polymer and capable of acquiring in the washing bath a COO load density at least equal at 10-3 mol / g of polymer or a hydrolyzate of said polyimide, polyimide derived from the thermal polycondensation of at least one amino acid, then optionally hydrolysis, said use being characterized in that said polyimide is obtained by thermal polycondensation of at least an amino acid in the presence of at least one "acid catalyst" consisting of a mineral or organic acid of pk, less than or equal to 5, preferably less than or equal to 3, of a precursor of one of these acids, d 'a salt of these acids and of an amino acid similar to or different from that or those used, of a salt of these acids and of a polyimide derived from the polycondensation of at least one amino acid similar to or different from the one or those implemented or a cide of Lewis, in an "acid catalyst" I amino acid molar ratio of at least 0.001. 15) Use according to claim 14) characterized in that the "acid catalyst" I amino acid molar ratio is of the order of 0.005 to 10. 16) Use according to claim 15) characterized in that the "acid catalyst" / amino acid molar ratio is of the order of 0.01 to 5. 17) Use according to any one of claims 14) to 16) characterized in that the "acid catalyst" is. Anhydrous or hydrated sulfuric acid, oleum, SO3, sulfurous acid, potassium acid sulfate, lithium, sodium, quaternary ammonium methane sulphonic acid, benzene sulphonic, trifluoromethanesulphonic, dodecylbenzenesulphonic, paratoluene sulphonic, cysteic acid phosphoric acid, phosphoric anhydride, P205, phosphorous acid, potassium hydrogen phosphate, sodium, lithium, quaternary ammonium. Hydrochloric acid, PCl3, PCl5, POCI3. Nitric acid, hydrofluoric acid. SiCI3, CH3SiCI3 . phosphomethylglycine . salts of aspartic acid and of hydrochloric, sulfuric, methanesulphonic or paratoluenesulphonic acid. polysuccinimide hydrochloride. AlCI3, BF3, ZnCI2 18) Use according to any one of claims 14) to 17) characterized in that the amino acid used is aspartic acid or glutamic acid taken alone or as a mixture with each other in any proportions or as a mixture with another amino acid. 19) Use according to any one of claims 14) to 18) characterized in that the thermal polycondensation operation is carried out at a temperature of the order of 100 to 250 "C. 20) Use according to any one of claims 14) to 19) characterized in that the thermal polycondensation operation is carried out in bulk or in a solvent medium. 21) Use according to any one of claims 14) to 20) characterized in that an "amino acid salt" is used as the sole component of the reaction instead of an amino acid / "acid catalyst" mixture. . 22) Use according to any one of claims 14) to 21) characterized in that the polycondensation operation is carried out in bulk, in the presence of "an" acid catalyst "chosen from those allowing the reaction medium to remain in powder form throughout the duration of the polycondensation. 23) Use according to claim 22) characterized in that the "acid catalyst" is potassium or sodium acid sulfate, potassium or sodium hydrogen phosphate. 24) Use according to any one of claims 14) to 23) characterized in that the polyimide obtained by thermocondensation is hydrolyzed into a salt by addition of a basic agent, said salt then being optionally neutralized into an acid by addition of a mineral or organic acid. 25) Use according to any one of claims 14) to 24) characterized in that the polyimide or its hydrolyzate represents of the order of 0.2 to 80% by weight of powdered detergent composition. 26) Use according to any one of claims 14) to 25) characterized in that a surfactant is present in an amount of the order of 2 to 50% of the weight of powdered detergent composition.