EP0915955B1 - Dishwasher detergent composition containing an anticorrosive agent - Google Patents

Abstract

A detergent composition containing alkali-metal silicate with an average molar ratio of SiO2/M2O of 1-4.2, preferably 2.5-4.2, wherein M is an alkali metal, the composition being non-corrosive to glass, crystal, porcelain and decorative prints thereon upon repeated washing. The composition being such that when disposed in a washing medium at a normal working concentration, a protonated silicic monomer Si(OH)4 is produced in a concentration of at least 2.5x10-3 mol/liter of the washing medium.

Description

The subject of the present invention is a detergent composition for a dishwasher, based on alkali metal silicate, non-corrosive to glass, crystal, glass porcelain and decorations; it also relates to the use of said composition non-corrosive dishwasher detergent, as well as the dishwasher washing process implementing it.

One of the major problems encountered in the use of dishwashers is the irreversible corrosion of dishes (glass, crystal, porcelain) observed at following repeated washing.

In the case of glass, this irreversible corrosion first results in a iridescence phenomenon, then by a frosted white appearance of the glass; it is accompanied loss of mass.

The phenomenon of glass corrosion by aqueous solutions was the subject studies, in particular in the field of the stability of inerting glasses for nuclear waste ("Corrosion of Glass, ceramics and ceramic superconductor, Principles, testing, characterization and Application, edited by D. E. Clark and B. K. Zoitos, Noyes Publications, 1992). In this type of application, the attack conditions of the glass do not correspond to those encountered during washing in a dishwasher, whether at the pH of the solutions, the temperature or the character dynamics of corrosion in the dishwasher.

• celles très alcalines à base de métasilicate développant un pH de l'ordre de 12 à 13, donnant peu de corrosion visible du verre blanc, mais conduisant à un endommagement des articles décorés et des glaçures
• et celles modérément alcalines développant un pH de l'ordre de 9 à 11,5 , permettant une protection efficace des articles décorés et des glaçures, mais provoquant une forte corrosion visible du verre blanc.

L'utilisation de ces deux types de formules conduit à une perte en masse et à un endommagement des articles.The use of silicates as a detergency builder in detergent compositions for dishwashers is well known; some authors mention their ability to limit the corrosion of glass, porcelain and the glaze of articles (EJ Schuck, Proc. Mid-Year Meet, Chem. Spec. Manuf. assoc. (1972), vol. 58, pp 82-85; M. Hellsten, Tenside detergents, 9, Heft 4, pp 178-182 (1972); US-A-3,494,868; WO 96/17047).
In this context, two types of formulas must be distinguished (W. Buchmeir, Glatech. Ber. Glass Sci. Tecnol. (1996) No. 6, pp 159-167),

• those very alkaline based on metasilicate developing a pH of the order of 12 to 13, giving little visible corrosion of the white glass, but leading to damage to the decorated articles and glazes
• and those moderately alkaline developing a pH of the order of 9 to 11.5, allowing effective protection of the decorated articles and glazes, but causing strong visible corrosion of the white glass.

The use of these two types of formulas leads to a loss in mass and to damage of the articles.

Dishwasher compositions comprising lamellar alkali silicates largely insoluble in water have been described in EP-A-0 416 366.

Application WO 96/17047, already mentioned above, proposes compositions for dishwashers comprising mixtures of metasilicate and silicate with an SiO ₂ / M ₂ O molar ratio greater than 1, for cleaning and caring for glass articles .

An in-depth study of the corrosion mechanisms of glass and tableware has shown that corrosion of glass and dishes is due in particular to the hydrolysis of glass network accompanied by a phenomenon of leaching of ions from the glass to the bath.

The Applicant has found a solution making it possible to resolve at the same time the two problems, namely loss of mass and damage to articles.

The Applicant has hypothesized that the implementation of a detergent bath comprising in its chemical composition a "silicate part" analogous to that of glass silica network would eliminate the phenomenon of hydrolysis and thus limit, or even eliminate, corrosion of the glass at the hydrolysis stage by rupture of Si-O-Si links in the glass network.

It has found that the phenomenon of corrosion of glass by repeated washing in dishwashers is greatly reduced, or even stopped by the presence in the detergent bath of a sufficient quantity of protonated silicic monomer Si (OH) ₄ ; she found that this performance is also obtained on porcelain, glass or porcelain decorations and crystal.

A first object of the invention consists in the use, for eliminating or limiting corrosion of articles in glass, crystal, porcelain and decorations on glass or porcelain by repeated washing in the dishwasher, of a detergent composition generating a medium detergent having a concentration of protonated silicic monomer Si (OH) ₄ of at least 2.5 x 10 ^-3 mole / liter of detergent medium, preferably at least 3 x 10 ^-3 mole / liter of detergent medium, all particularly of the order of 3 x 10 ^-3 to 9 x 10 ^-3 mole / liter of detergent medium.

A second object of the invention consists of a process for the non-corrosive washing in a dishwasher of glass, crystal and porcelain articles, possibly decorated, by using a detergent composition generating a detergent medium having a concentration of protonated silicic monomer Si (OH) ₄ of at least 2.5 x 10 ^-3 mole / liter of detergent medium, preferably of at least 3 x 10 ^-3 mole / liter of detergent medium, very particularly of the order from 3 x 10 ^-3 to 9 x 10 ^-3 mole / liter of detergent medium.

Said detergent medium preferably has a pH greater than 9.8, while particularly around 9.9 to 11.1.

One means of obtaining this sufficient concentration of protonated silicic monomer Si (OH) ₄ in the detergent bath consists in using, via a detergent composition, a sufficient quantity of at least one alkali metal silicate in order to obtain a high SiO _{2 content} capable of generating said monomer and of promoting the formation of said monomer by adjusting the pH of the bath by choosing the nature of said silicate and of the other ingredients of the composition according to the chosen silicate.

All of the amorphous or crystalline soluble alkali metal silicates with a SiO ₂ / M ₂ O ratio of the order of 1 to 4.2 make it possible to achieve the desired objective. Preferably, these are soluble amorphous silicates.
A particularly preferred means consists in using in the detergent composition at least one soluble alkali metal silicate, with an average SiO ₂ / M ₂ O molar ratio of the order of 2.5 to 4.2, preferably amorphous, allowing d '' obtain a high SiO ₂ content in the detergent bath and favor a low pH of the bath compatible with an adequate content of protonated silicic monomer Si (OH) ₄ .
The term “soluble” silicate is understood to mean any silicate of which at least 50% of the silicon network is dissolved in the washing medium after 10 minutes under the washing conditions.
The term “average” SiO ₂ / M ₂ O molar ratio is understood to mean the ratio of the total number of moles of SiO ₂ to the total number of moles of M ₂ O originating from the alkali metal silicate (s) present in the detergent composition.

A third subject of the invention consists of a detergent composition for a dishwasher, based on at least one alkali metal silicate, with an average SiO ₂ / M ₂ O molar ratio of the order of 1 to 4.2. , preferably of the order of 2.5 to 4.2, M representing an alkali metal, non-corrosive towards glass, crystal, porcelain and decorations, generating, at the concentration of use, a detergent medium having a concentration of protonated silicic monomer Si (OH) ₄ of at least 2.5 x 10 ^-3 mole / liter of detergent medium, preferably at least 3 x 10 ^-3 mole / liter of detergent medium, especially of the order of 3 x 10 ^-3 to 9 x 10 ^-3 mole / liter of detergent medium.

To facilitate reading, the expression "alkali metal silicate" is understood below to mean both an alkali metal silicate alone and a mixture of several alkali metal silicates which may have molar ratios SiO ₂ / M ₂ O different; the expression "average SiO ₂ / M ₂ O molar ratio" therefore corresponds either to a silicate alone, when a single silicate is present, or to a mixture of silicates, when several silicates of different molar ratios are present.

• "pH" représente le pH du milieu lessiviel à 25°C
• "pK1" représente la première constante d'acidité pKa de l'acide silicique correspondant à l'équilibre Si(OH)₄ <===> (SiO₄H₃)^- ; pk1 est égal à 9,8 à 25°C, selon la littérature (R. H. Iler, "The chemistry of silica", A. Wiley - Interscience Publication 1979)
• "pK2" représente la deuxième constante d'acidité pKa de l'acide silicique correspondant à l'équilibre (SiO₄H₃)^- <===> (SiO₄H₂)^2- ; pK2 est égal à 12,2 à 25°C, selon la littérature (R. H. Iler, "The chemistry of silica", A. Wiley - Interscience Publication 1979).

The concentration of protonated silicic monomer Si (OH) ₄ in the washing medium is a function of the concentration of total soluble SiO ₂ in the washing medium and the pH of the bath.
It is measured at 25 ° C and expressed in moles / liters, according to the following equation (I): [Si (OH) 4 ] = [SiO 2 total detergent medium] / {1 + 10 (PH pK1) + 10 (2pH-pK1 pK2-) } equation in which:

• "pH" represents the pH of the washing medium at 25 ° C
• "pK1" represents the first acidity constant pKa of the silicic acid corresponding to the equilibrium Si (OH) ₄ <===> (SiO ₄ H ₃ ) ^- ; pk1 is equal to 9.8 at 25 ° C, according to the literature (RH Iler, "The chemistry of silica", A. Wiley - Interscience Publication 1979)
• "pK2" represents the second acidity constant pKa of the silicic acid corresponding to the equilibrium (SiO ₄ H ₃ ) ^- <===> (SiO ₄ H ₂ ) ^2- ; pK2 is equal to 12.2 at 25 ° C, according to the literature (RH Iler, "The chemistry of silica", A. Wiley - Interscience Publication 1979).

The term "concentration of total soluble SiO ₂ in the washing medium" means the amount of SiO ₂ soluble in the washing medium, originating from the soluble alkali metal silicate used.

Equation (I) can also be written as follows. [Si (OH) 4 ] = [SiO 2 total detergent medium] / {1 + 10 (PH-9.8) + 10 (2pH-22 }

• à droite de la courbe (a), une zone correspondant à une concentration en monomère silicique protoné Si(OH)₄ inférieure à 2,5 x 10^-3 mole/litre de milieu lessiviel;
• entre les deux courbes, une zone correspondant à une concentration en monomère silicique protoné Si(OH)₄ comprise entre 2,5 x 10^-3 et 3,0 x 10^-3 mole / litre de milieu lessiviel ;
• à gauche de la courbe (b), une zone correspondant à une concentration en monomère silicique protoné Si(OH)₄ supérieure à 3,0 x 10^-3 mole / litre de milieu lessiviel.

Les zones à gauche de la courbe (b) et entre les deux courbes correspondent donc à des concentrations en monomère silicique protoné Si(OH)₄ dans le domaine de l'invention, la zone à gauche de la courbe (b) correspondant au domaine préférentiel de l'invention.FIG. 1 represents the concentration of total soluble SiO ₂ according to this equation as a function of pH, for a concentration of protonated silicic monomer Si (OH) ₄ chosen.
Curve (a) corresponds to a concentration of protonated silicic monomer Si (OH) ₄ of 2.5 × 10 ^-3 mole / liter of detergent medium; curve (b) corresponds to a concentration of protonated silicic monomer Si (OH) ₄ of 3 × 10 ^-3 mole / liter of detergent medium.
Three zones are delimited by these two curves:

• to the right of curve (a), a zone corresponding to a concentration of protonated silicic monomer Si (OH) _{4 of} less than 2.5 × 10 ^-3 mole / liter of detergent medium;
• between the two curves, an area corresponding to a concentration of protonated silicic monomer Si (OH) ₄ of between 2.5 x 10 ^-3 and 3.0 x 10 ^-3 mole / liter of detergent medium;
• to the left of curve (b), an area corresponding to a concentration of protonated silicic monomer Si (OH) ₄ greater than 3.0 x 10 ^-3 mole / liter of detergent medium.

The areas to the left of curve (b) and between the two curves therefore correspond to concentrations of protonated silicic monomer Si (OH) ₄ in the field of the invention, the area to the left of curve (b) corresponding to the area preferential of the invention.

In a particularly preferred manner, the concentration of protonated silicic monomer Si (OH) ₄ in the detergent medium is of the order of 3 × 10 ^-3 to 9 × 10 ^-3 mole / liter of detergent medium.

Said detergent composition can be in solid form (powder, tablets), in liquid or gel form.

The concentration of use of a detergent composition for dishwashers is generally of the order of 3 to 12 g / liter of detergent bath. This is more precisely of the order of 4 to 10 g / liter for a powder composition, of the order of 3 to 6 g / liter for a composition in tablet form and of the order of 4 to 12 g / liter for a liquid or gel composition.

The pH of the washing medium is regulated by the nature and the amount of the alkali metal silicate and of the other additives influencing the pH present in the composition.
This is preferably set to a value greater than 9.8, in particular to a value of the order of 9.9 to 11.1.

• à droite de la courbe (A), une zone correspondant à une concentration en monomère silicique protoné Si(OH)₄ inférieure à 2,5 x 10^-3 mole / litre de milieu lessiviel ;
• entre les deux courbes, une zone correspondant à une concentration en monomère silicique protoné Si(OH)₄ comprise entre 2,5 x 10^-3 et 3,0 x 10^-3 mole / litre de milieu lessiviel ;
• à gauche de la courbe (B), une zone correspondant à une concentration en monomère silicique protoné Si(OH)₄ supérieure à 3,0 x 10^-3 mole / litre de milieu lessiviel.

Les zones à gauche de la courbe (B) et entre les deux courbes correspondent donc à des concentrations en monomère silicique protoné Si(OH)₄ dans le domaine de l'invention, la zone à gauche de la courbe (B) correspondant au domaine préférentiel de l'invention.Curves (A) and (B) corresponding to a concentration of protonated silicic monomer Si (OH) ₄ of 2.5 x 10 ^-3 mole / liter and 3 x 10 ^-3 mole / liter respectively of detergent medium, given in the figures 2 to 4 allow, for a usage concentration of 6 g / l of detergent composition in the detergent medium, to define, as a function of the pH of the detergent medium, which quantities of sodium silicate, respectively of average molar ratio SiO ₂ / Na ₂ O = 1 (FIG. 2), SiO ₂ / Na ₂ O = 2.1 (FIG. 3) and SiO ₂ / Na ₂ O = 3.3 (FIG. 4), can be used in the detergent composition for realize the invention.
Three zones are delimited by these two curves:

• to the right of curve (A), a zone corresponding to a concentration of protonated silicic monomer Si (OH) _{4 of} less than 2.5 × 10 ^-3 mole / liter of detergent medium;
• between the two curves, an area corresponding to a concentration of protonated silicic monomer Si (OH) ₄ of between 2.5 x 10 ^-3 and 3.0 x 10 ^-3 mole / liter of detergent medium;
• to the left of curve (B), an area corresponding to a concentration of protonated silicic monomer Si (OH) ₄ greater than 3.0 x 10 ^-3 mole / liter of detergent medium.

The areas to the left of curve (B) and between the two curves therefore correspond to concentrations of protonated silicic monomer Si (OH) ₄ in the field of the invention, the area to the left of curve (B) corresponding to the area preferential of the invention.

• à droite de la courbe (A), une zone correspondant à une concentration en monomère silicique protoné Si(OH)₄ inférieure à 2,5 x 10^-3 mole / litre de milieu lessiviel ;
• entre les deux courbes, une zone correspondant à une concentration en monomère silicique protoné Si(OH)₄ comprise entre 2,5 x 10^-3 et 3,0 x 10^-3 mole / litre de milieu lessiviel;
• à gauche de la courbe (B), une zone correspondant à une concentration en monomère silicique protoné Si(OH)₄ supérieure à 3,0 x 10^-3 mole / litre de milieu lessiviel.

Les zones à gauche de la courbe (B) et entre les deux courbes correspondent donc à des concentrations en monomère silicique protoné Si(OH)₄ dans le domaine de l'invention, la zone à gauche de la courbe (B) correspondant au domaine préférentiel de l'invention.Curves (A) and (B) corresponding to a concentration of protonated silicic monomer Si (OH) ₄ of 2.5 x 10 ^-3 mole / liter and 3 x 10 ^-3 mole / liter respectively of detergent medium, given in the figures 5 to 7 correspond to a usage concentration of 4 g / l of detergent composition in the detergent medium with respective average molar ratios SiO ₂ / Na ₂ O = 1 (FIG. 5), SiO ₂ / Na ₂ O = 2, 1 (Figure 6) and SiO ₂ / Na ₂ O = 3.3 (Figure 7) of sodium silicate.
Three zones are delimited by these two curves:

• to the right of curve (A), a zone corresponding to a concentration of protonated silicic monomer Si (OH) _{4 of} less than 2.5 × 10 ^-3 mole / liter of detergent medium;
• between the two curves, an area corresponding to a concentration of protonated silicic monomer Si (OH) ₄ of between 2.5 x 10 ^-3 and 3.0 x 10 ^-3 mole / liter of detergent medium;
• to the left of curve (B), an area corresponding to a concentration of protonated silicic monomer Si (OH) ₄ greater than 3.0 x 10 ^-3 mole / liter of detergent medium.

The areas to the left of curve (B) and between the two curves therefore correspond to concentrations of protonated silicic monomer Si (OH) ₄ in the field of the invention, the area to the left of curve (B) corresponding to the area preferential of the invention.

The amount by dry weight of alkali metal silicate generally represents, depending on the form of detergent composition chosen, of the order of 5 to 55%, preferably of the order of 10 to 40% of the dry weight of said composition.
More specifically, for a solid detergent composition (powder or tablet) the amount of silicate represents of the order of 5 to 55%, preferably of the order of 10 to 40% of the dry weight of said composition, for a liquid composition or in the form of a gel, the amount of silicate represents of the order of 5 to 40%, preferably of the order of 10 to 30% of the dry weight of said composition.

• pour une composition détergente utilisée à une concentration de 6 g/litre, avec un pH du milieu lessiviel par exemple de 10,5 , l'usage dans ladite composition détergente
  • d'au moins 30% environ, de préférence d'au moins 36% environ de métasilicate de sodium
  • d'au moins 22% environ, de préférence d'au moins 27% environ de disilicate de sodium
  • d'au moins 20% environ, de préférence d'au moins 24% environ de silicate de rapport molaire SiO₂/Na₂O moyen de 3,3.
• pour une composition détergente utilisée à une concentration de 4 g/litre, avec un pH du milieu lessiviel par exemple de 10,5 , l'usage dans ladite composition détergente
  • d'au moins 45% environ, de préférence d'au moins 55% environ de métasilicate de sodium
  • d'au moins 33% environ, de préférence d'au moins 40% environ de disilicate de sodium
  • d'au moins 30% environ, de préférence d'au moins 35% environ de silicate de rapport molaire SiO₂/Na₂O moyen de 3,3 .

Those skilled in the art can, by analysis of FIGS. 2 to 7, define which conditions are best suited to carrying out the invention, depending on the nature of the silicate chosen and the form of detergent composition sought.
Those skilled in the art can also, for concentrations of use different from those mentioned above and / or for silicates of molar ratio SiO ₂ / Na ₂ O other means, by general study of FIG. 1 and / or using equation (I) to determine the best conditions for carrying out the invention.
This analysis allows you to advise

• for a detergent composition used at a concentration of 6 g / liter, with a pH of the detergent medium for example of 10.5, the use in said detergent composition
  • at least about 30%, preferably at least about 36% of sodium metasilicate
  • at least about 22%, preferably at least about 27% of sodium disilicate
  • at least about 20%, preferably at least about 24% of silicate with an average SiO ₂ / Na ₂ O molar ratio of 3.3.
• for a detergent composition used at a concentration of 4 g / liter, with a pH of the detergent medium for example of 10.5, the use in said detergent composition
  • at least about 45%, preferably at least about 55% of sodium metasilicate
  • at least about 33%, preferably at least about 40% sodium disilicate
  • at least about 30%, preferably at least about 35% silicate with an average SiO ₂ / Na ₂ O molar ratio of 3.3.

Once the nature and quantity of the alkali metal silicate have been fixed, the pH of the medium detergent is then adjusted by the choice and quantities of the other ingredients influencing on the pH of the detergent composition.

• des additifs alcalinisants solubles dans le milieu lessiviel comme
  • les phosphates de métaux alcalins (orthophosphates, pyrophosphates, polyphosphates comme les tripolyphosphates notamment)
  • les carbonates et percarbonates de métaux alcalins
  • les borates et perborates de métaux alcalins
  • les hydroxydes de métaux alcalins ...
• des additifs acidifiants solubles dans le milieu lessiviel comme
  • les acides carboxyliques ou polycarboxyliques engendrant dans le milieu lessiviel des composés séquestrants ou dispersants (acides citrique, glutamique, glutarique, gluconique, taririque, les acides polyacryliques ou leurs copolymères, les acides gras ...)
  • les bicarbonates et sesquicarbonates de métaux alcalins
  • les acides phosphoriques et polyphosphoriques
  • les acides sulfoniques
  • les esters phosphoriques à caractère acide
  • les phosphonates à caractère acide
  • l'acide borique
  • les bisulfates de métaux alcalins ...

The usual additives present in detergent compositions for dishwashers and making it possible to influence the pH of the detergent medium are mainly

• alkalizing additives soluble in the detergent medium such as
  • alkali metal phosphates (orthophosphates, pyrophosphates, polyphosphates such as tripolyphosphates in particular)
  • alkali metal carbonates and percarbonates
  • alkali metal borates and perborates
  • alkali metal hydroxides ...
• acidifying additives soluble in the detergent medium such as
  • carboxylic or polycarboxylic acids generating sequestering or dispersing compounds in the washing medium (citric, glutamic, glutaric, gluconic, tariric acids, polyacrylic acids or their copolymers, fatty acids ...)
  • bicarbonates and sesquicarbonates of alkali metals
  • phosphoric and polyphosphoric acids
  • sulfonic acids
  • acidic phosphoric esters
  • acidic phosphonates
  • boric acid
  • alkali metal bisulphates ...

• les agents tensioactifs anioniques du type savons de métaux alcalins (sels alcalins d'acides gras en C₈-C₂₄), sulfonates alcalins (alcoylbenzène sulfonates en C₈-C₁₃, alcoylsulfonates en C₁₂-C₁₆), alcools gras en C₆-C₁₆ oxyéthylénés et sulfatés, alkylphénols en C₈-C₁₃ oxyéthylénés et sulfatés, les sulfosuccinates alcalins (alcoylsulfosuccinates en C₁₂-C₁₆)...
• les agents tensioactifs non ioniques du type alcoylphénols en C₆-C₁₂ polyoxyéthylénés, alcools aliphatiques en C₈-C₂₂ polyoxyéthylénés et/ou polyoxypropylénés, les copolymères bloc oxyde d'éthylène - oxyde de propylène, les amides carboxyliques éventuellement polyoxyéthylénés ...,

Ces agents tensioactifs sont de peu d'influence sur le pH du milieu lessiviel.The detergent compositions for dishwashers comprise at least one surfactant in an amount which can range from 0.5 to 10%, preferably of the order of 1 to 5%, by weight of said detergent composition expressed as dry matter.
Among these we can cite:

• anionic surfactants such as alkali metal soaps (alkali salts of C ₈ -C ₂₄ fatty acids), alkali sulfonates (C ₈ -C ₁₃ alkylbenzene sulfonates, C ₁₂ -C ₁₆ alkyl sulfonates), C fatty alcohols ₆ -C ₁₆ oxyethylenated and sulphated, C ₈ -C ₁₃ alkylphenols oxyethylenated and sulphated, alkali sulphosuccinates (C ₁₂ -C ₁₆ alkyl sulphosuccinates) ...
• non-ionic surfactants of the polyoxyethylenated C ₆ -C ₁₂ alkylphenols type, polyoxyethylenated and / or polyoxypropylenated C ₈ -C ₂₂ aliphatic alcohols, block copolymers of ethylene oxide - propylene oxide, optionally polyoxyethylenated carboxylic amides ... ,

These surfactants have little influence on the pH of the washing medium.

• des "builders" (agents améliorant les propriétés de surface des tensioactifs) du type :
  • phosphates minéraux solubles de métaux alcalins, en particulier les tripolyphosphates de métaux alcalins à raison de 0 à 70% du poids total de composition détergente exprimé en matière sèche ;
  • phosphonates organiques comme ceux de la gamme DEQUEST® de MONSANTO à raison de 0 à 2% du poids total de composition détergente exprimé en matière sèche ;
  • acide nitriloacétique, acide N,N-dicarboxyméthyl-2-aminopentane dioïque, acide éthylènediamine tétraacétique, acide diéthylènetriamine pentaacétique, à raison de 0 à 10 % du poids total de composition détergente exprimé en matière sèche ;
  • acide citrique, acide gluconique ou acide tartrique ou leurs sels à raison de 0 à 10% du poids total de composition détergente exprimé en matière sèche ;
• des agents de blanchiment du type perborates, percarbonates associés ou non à des activateurs de blanchiment acétylés comme la N, N, N', N'-tétraacétyléthylènediamine (TAED) ou des produits chlorés du type des chloroisocyanurates pour les compositions solides, ou des produits chlorés du type hypochlorites de métaux alcalins pour les compositions liquides, à raison de 0 à 30 % du poids total de ladite composition détergente exprimé en matière sèche ;
• des agents auxiliaires de nettoyage du type copolymères d'acide acrylique et d'anhydride maléïque ou des homopolymères d'acide acrylique à raison de 0 à 10 %, du poids total de ladite composition détergente exprimé en matière sèche ;
• des agents alcalins comme les borates, carbonates, bicarbonates, sesquicarbonates de métaux alcalins, à raison de 0 à 50% du poids total de ladite composition exprimé en matière sèche ;
• des charges du type sulfate de sodium, chlorure de sodium pour les détergents en poudre à raison de 0 à 50 % du poids total de ladite composition exprimé en matière sèche ; ces charges sont de peu d'influence sur le pH ;
• d'autres additifs divers comme des enzymes dans le cas des compositions solides, en quantité pouvant aller jusqu'à 10 % du poids total de ladite composition exprimé en matière sèche, parfums, colorants, agents inhibiteurs de corrosion des métaux ...

Among the other usual additives used in the formulation of detergent compositions for washing in a dishwashing machine, mention may be made in particular

• "builders" (agents improving the surface properties of surfactants) of the type:
  • alkaline soluble mineral phosphates, in particular alkali metal tripolyphosphates in an amount of 0 to 70% of the total weight of detergent composition expressed as dry matter;
  • organic phosphonates such as those of the DEQUEST® range from MONSANTO at a rate of 0 to 2% of the total weight of detergent composition expressed as dry matter;
  • nitriloacetic acid, N acid, N-dicarboxymethyl-2-aminopentane dioic acid, ethylenediamine tetraacetic acid, diethylenetriamine pentaacetic acid, at a rate of 0 to 10% of the total weight of detergent composition expressed as dry matter;
  • citric acid, gluconic acid or tartaric acid or their salts in an amount of 0 to 10% of the total weight of detergent composition expressed as dry matter;
• bleaching agents of the perborate type, percarbonates associated or not with acetylated bleaching activators such as N, N, N ', N'-tetraacetylethylenediamine (TAED) or chlorinated products of the chloroisocyanurate type for solid compositions, or products chlorinated alkali metal hypochlorites for liquid compositions, at a rate of 0 to 30% of the total weight of said detergent composition expressed as dry matter;
• auxiliary cleaning agents of the acrylic acid and maleic anhydride copolymer type or homopolymers of acrylic acid in an amount of 0 to 10%, of the total weight of said detergent composition expressed as dry matter;
• alkaline agents such as borates, carbonates, bicarbonates, sesquicarbonates of alkali metals, at a rate of 0 to 50% of the total weight of said composition expressed as dry matter;
• fillers of the sodium sulfate, sodium chloride type for powdered detergents at a rate of 0 to 50% of the total weight of said composition expressed as dry matter; these charges have little influence on the pH;
• other various additives such as enzymes in the case of solid compositions, in an amount which can range up to 10% of the total weight of said composition expressed as dry matter, perfumes, dyes, agents for inhibiting corrosion of metals, etc.

As already mentioned above, any type of alkali metal silicate soluble can be used in the detergent composition of the invention.

Thus the anhydrous and / or hydrated metasilicates (SiO ₂ / M ₂ O molar ratio of 1) in the form of powder or granules can be present according to the invention in a detergent composition in powder or in tablets. The pH of the detergent bath can be adjusted to a pH greater than 9.8, preferably of the order of 9.9 to 11.1 by the presence in said composition of an acidifying agent or additive such as citric acid. , sodium bicarbonate, sodium sesquicarbonate or any other acidifying agent.

The amorphous "disilicates" (average SiO ₂ / M ₂ O molar ratio greater than 1 and less than 2.5) may be present, in atomized form compacted in a detergent composition in powder or in tablets, in the form of a concentrated solution generally about 45% dry matter in a liquid detergent composition or in gel form; they can also be present in the form of solid preformulation in a powder or tablet composition, preformulation, preferably in the form of cogranules, obtained by adsorption and / or absorption of a concentrated solution of alkali metal silicate generally at about 45% dry matter on a soluble mineral support of the alkali metal tripolyphosphate type and / or alkali metal carbonate and / or alkali metal bicarbonate and / or alkali metal sesquicarbonate and / or alkali metal sulfate, the amount of water remaining associated with the silicate corresponding to a water associated with silicate / silicate ratio expressed as dryness of at least 20/100, preferably at least 30/100.
The term "water associated with silicate" means the water of the supported solution which is not combined with the mineral support, in particular in the form of crystallized hydrate. This can be measured in particular by X-ray diffraction, NMR of the solid, proton, phosphorus, etc.).
The pH of the detergent bath can be adjusted to a pH greater than 9.8, preferably of the order of 9.9 to 11.1 by the presence in said composition of an acidifying agent or additive such as citric acid. , sodium bicarbonate, sodium sesquicarbonate or any other acidifying agent.

Preferably, the alkali metal silicate, in particular sodium, used in the detergent compositions of the invention, is amorphous and has an average SiO ₂ / M ₂ O molar ratio of the order of 2.5 to 4.2.
Its mode of implementation within a detergent composition depends on the form of the detergent composition for which it is intended, namely a solid detergent composition (powder or tablets) or a liquid or gel detergent composition.
Said alkali metal silicate having an average SiO ₂ / M ₂ O molar ratio of the order of 2.5 to 4.2 can be very particularly used in the form of a concentrated aqueous solution generally at about 25 to 50% dry matter or a liquid preformulation in a liquid detergent or gel composition, or in the form of a solid preformulation in a powder or tablet composition.

When it is intended for a solid detergent composition, it can preferably be used in the form of a solid preformulation, in particular in the form of cogranules, obtained by adsorption and / or absorption of a concentrated solution of alkali metal silicate. on at least one non-water-soluble or preferably water-soluble mineral support, the amount of water remaining associated with the silicate corresponding to a water-associated silicate / silicate ratio expressed as dry of at least 20/100, preferably at least 30/100.
Among the non-water-soluble mineral supports, mention may be made of natural or synthetic, amorphous or crystalline sodium silicoaluminates, calcium carbonate, clays, magnesium, calcium silicates, silica, etc.
Among the water-soluble mineral supports, mention may be made of alkali metal tripolyphosphates, alkali metal carbonates, alkali metal bicarbonates, alkali metal sesquicarbonates, alkali sulfates, etc.
If necessary, the pH of the detergent bath can be adjusted to a pH greater than 9.8, preferably of the order of 9.9 to 10.8, by the presence in said composition of an alkalizing agent or additive or of an acidifying agent or additive.
A first type of solid preformulation consists of cogranules obtained by adsorption and / or absorption of a concentrated solution of alkali metal silicate molar ratio SiO ₂ / M ₂ O mean of the order 2.5 to 4.2, preferably of the order of 2.6 to 3.5, adsorbed and / or absorbed on at least one water-soluble mineral support compatible with the desired pH, in particular of the sodium sesquicarbonate type and / or mixtures of sodium carbonate and sodium bicarbonates and / or preferably sodium tripolyphosphate, the weight ratio, expressed in dry terms, silicate / mineral support being of the order of 20/80 to 60/40, preferably of the order of 25/75 to 50/50, and optionally drying until the amount of water present in said preformulation represents of the order of 10 to 35% of the weight of said preformulation, and the amount of water remaining associated with the silicate corresponds to a water ratio associated with silicate / silicate expressed at least dry s 20/100, preferably at least 30/100.
A first particular type of solid detergent composition which is the subject of the invention consists of a solid detergent composition as described above, in which the alkali metal silicate has a molar SiO ₂ / M ₂ O ratio of l '' order 2.5 to 4.2, preferably of the order 2.6 to 3.5, and is implemented via said first type of solid preformulation, preformulation whose pH at its concentration in the medium detergent is greater than 9.8, preferably of the order of 9.9 to 10.8, and this in accordance with equation (I) mentioned above.
A second type of solid preformulation consists of cogranules obtained by adsorption and / or absorption of a concentrated solution of alkali metal silicate molar ratio SiO ₂ / M ₂ O means of the order of 3 to 4.2, preferably of 3.3 to 4, adsorbed and / or absorbed on sodium carbonate, the weight ratio, expressed as dry, silicate / carbonate being of the order of 40/60 to 80/20, preferably of the order of 50/50 to 70/30, and optionally drying until the amount of water present in said preformulation represents of the order of 15 to 35% of the weight of said preformulation, and the amount of water remaining associated with silicate corresponds to a water ratio associated with silicate / silicate expressed as dryness of at least 20/100, preferably at least 30/100.
A second particular type of solid detergent composition which is the subject of the invention consists of a solid detergent composition as described above, in which the alkali metal silicate has a molar ratio SiO ₂ / M ₂ O average of 1 '' order 3 to 4.2, preferably of the order 3.3 to 4, and is implemented via said second type of solid preformulation, preformulation whose pH at its concentration in the washing medium is greater than 9.8, preferably of the order of 9.9 to 10.8, and this in accordance with equation (I) mentioned above.

When said silicate is intended for a liquid detergent composition or in the form of a gel, the latter has an average SiO ₂ / M ₂ O molar ratio of the order of 2.5 to 3.5, preferably of the order of 2, 6 to 3.3; it is used in the form of a concentrated aqueous commercial solution containing approximately 25 to 50% of dry matter, or of a liquid preformulation in the form of a dispersion in said concentrated solution of silicate of a water-soluble mineral compound.
One type of liquid preformulation consists of a dispersion, in a concentrated silicate solution, of average SiO ₂ / M ₂ O molar ratio of the order of 2.5 to 3.5, preferably of the order of 2.6 to 3.3 to about 25 to 50% of dry matter, of a water-soluble mineral compound sodium tripolyphosphate, preferably atomized, and / or sodium carbonate, the weight ratio, expressed as dry, silicate / water-soluble mineral compound being l '' from 70/30 to 30/70, preferably from 60/40 to 35/65, the amount of water present in said preformulation representing around 40 to 65% of the weight of said preformulation .
A particular type of liquid detergent composition which is the subject of the invention consists of a liquid detergent composition as described above, in which the alkali metal silicate has a molar ratio SiO ₂ / M ₂ O of the medium. on the order of 2.5 to 3.5, preferably on the order of 2.6 to 3.3, and is implemented via said type of liquid preformulation, preformulation whose pH at its concentration in the washing medium is greater than 9.8, preferably of the order of 9.9 to 10.9, and this in accordance with equation (I) mentioned above.

The following examples are given by way of illustration.

Examples 1-2 GLASS CORROSION AND GLASS DECOR TEST DISHWASHER

The two formulations for dishwashers are prepared, the composition of which is given in Table 1, by respectively introducing a mixture (A) consisting of sodium silicate of ratio R = SiO ₂ / Na ₂ O of 2.1 atomized and of sodium tripolyphosphate RHODIAPHOS LV and cogranules (B) consisting of sodium silicate with a ratio R = SiO ₂ / Na ₂ O of 3.11 supported by sodium tripolyphosphate (TPP), cogranules the composition of which is as follows Co-granulated (B) constituents % in weight TPP (dry) 52 silicate R = 3.11 (dry) 28 water 20 pH of the cogranules (B) at their concentration in the washing medium 10.3

The concentration of Si (OH) ₄ is calculated in accordance with equation (I), from the measurement of the pH of the washing medium and the amount of total SiO ₂ .

Assessment of visible corrosion:

We perform 50 wash-rinse-dry cycles with a household machine BOSCH® SMS 7086.

In the upper basket there are 2 different types of glasses without decorations and 2 types decorated glasses (see table 1).

The temperature cycle chosen is 65 ° C; the dose of detergent composition used each wash is 30g for a volume of wash water of 5 liters; after each washing-rinsing-drying cycle, the door is left closed for 10 minutes then open for 10 minutes.

Corrosion evaluation is done visually with a scale ranging from 1 to 5 points, in taking as reference the glasses in new condition, by 9 trained people.

• 1 point correspond à un état parfait
• 2 points correspondent à un endommagement à peine visible (traces blanches ou colorées sur les verres sans décors ; matification du décor du verre)
• 3 points correspondent à un endommagement très net, spontanément visible (verres sans décors globalement colorés ou blanchis, avec éventuellement la présence de défaut locaux ; les décors de verre sont mats, avec ternissement des couleurs).
  • 4 points correspondent à un endommagement très important (les verres sans décors présentent aussi de larges taches blanches ; les décors de verre ont partiellement disparu).
  • 5 points correspondent à des surfaces totalement dégradées (la surface est entièrement endommagée ; les décors ont disparu).

Points are distributed as follows:

• 1 point corresponds to a perfect state
• 2 points correspond to barely visible damage (white or colored traces on the glasses without decorations; matification of the glass decoration)
• 3 points correspond to very clear, spontaneously visible damage (glasses without globally colored or bleached decorations, possibly with the presence of local defects; the glass decorations are dull, with tarnishing of colors).
  • 4 points correspond to very significant damage (glasses without decorations also have large white spots; the glass decorations have partially disappeared).
  • 5 points correspond to totally degraded surfaces (the surface is completely damaged; the decorations have disappeared).

Mass loss assessment:

Measuring the relative mass loss (PM) of the samples makes it possible to quantify the thickness of the damaged (dissolved) surface; it is expressed in thousands of%.

This corresponds to PM = [(mass after test - initial mass) / initial mass] x 100,000. The results are given in Table 1.

They show that the use of cogranules (B) of sodium silicate of ratio 3.11 supported by sodium tripolyphosphate, under conditions corresponding to a concentration of Si (OH) ₄ of 3.75 mmol / liter of detergent medium results in a total inhibition of the corrosion of the glass and of the glass decorations, observed by the absence of visible corrosion and a practically zero loss in mass. On the other hand, a very large and heterogeneous iridescence of the glass surface without decorations and damage to the glass decorations is observed, with the same amount (in dry) of mixture (A) of sodium silicate of ratio 2.1 and tripolyphosphate sodium corresponding to Si (OH) 4 concentration conditions of 1.1 mmol / liter of detergent medium; this visible corrosion is confirmed by a significant loss in mass of the glass.

Examples 3-8 SOLID DETERGENT FORMULATIONS CONTAINING TPP - TEST OF CORROSION OF GLASS IN DISHWASHER -

• mélange (C) constitué de tripolyphosphate de sodium RHODIAPHOS LV et de cogranulés de métasilicate de sodium (rapport R = SiO₂ / Na₂O de 1) anhydre et de métasilicate de sodium (rapport R = SiO₂ / Na₂O de 1) hydraté commercialisés par RHÔNE-POULENC sous la dénomination de GA5 ;
• mélange (D) constitué de tripolyphosphate de sodium RHODIAPHOS LV et de silicate de sodium de rapport R = SiO₂ / Na₂O de 2,1 atomisé ;
• cogranulés (E) constitués de silicate de sodium de rapport R = SiO₂ / Na₂O de 3,11 supportés par du tripolyphosphate de sodium (TPP) contenant 26% de leur poids d'eau ;
• cogranulés (F) constitués de silicate de sodium de rapport R = SiO₂ / Na₂O de 3,11 supportés par du tripolyphosphate de sodium (TPP) contenant 20% de leur poids d'eau.

Six solid formulations for a dishwasher are prepared, the composition of which is given in Table 2 by the introduction of one of the following mixtures (C) and (D) or of the following co-granules (E) and (F):

• mixture (C) consisting of RHODIAPHOS LV sodium tripolyphosphate and sodium metasilicate cogranules (ratio R = SiO ₂ / Na ₂ O of 1) anhydrous and sodium metasilicate (ratio R = SiO ₂ / Na ₂ O of 1) hydrate marketed by RHÔNE-POULENC under the name GA5;
• mixture (D) consisting of RHODIAPHOS LV sodium tripolyphosphate and sodium silicate of ratio R = SiO ₂ / Na ₂ O of 2.1 atomized;
• cogranules (E) consisting of sodium silicate of ratio R = SiO ₂ / Na ₂ O of 3.11 supported by sodium tripolyphosphate (TPP) containing 26% of their weight of water;
• cogranules (F) consisting of sodium silicate with a ratio R = SiO ₂ / Na ₂ O of 3.11 supported on sodium tripolyphosphate (TPP) containing 20% of their weight of water.

Corrosion tests are carried out as described above, on white glasses standard (wine and fruit flask, round).

The results obtained (average ratings and mass losses) are shown in table 2.

These results show that visible corrosion is greatly reduced in the case of the formulation of Example 7 (concentration of Si (OH) ₄ of 2.61 mmol / l) and nonexistent in the case of that of Example 8 ( Si (OH) ₄ concentration of 3.25 mmol / l).

Likewise, it is found that the loss in mass becomes negligible as soon as the concentration of Si (OH) ₄ reaches 2.61 mmol / l.

Examples 9-11 LIQUID DETERGENT FORMULATIONS CONTAINING TPP - TEST OF CORROSION OF GLASS IN DISHWASHER -

Three liquid formulations L1, L2 and L3 are prepared by suspending atomized TPP in a concentrated solution of silicate with different ratios R = SiO ₂ / Na ₂ O, and by adding sodium hypochlorite as bleaching agent and a non-foaming surfactant compatible with sodium hypochlorite.

Their composition is shown in Table 3.

The composition of the L3 formulation is close to that of the commercial formulations.

The three compositions are used at a rate of 32 g per wash.

Corrosion tests are carried out as described above, on white glasses standard (wine and fruit flask, round) and on standard decorated glasses (patterned cherry and red stripe pattern), after 100 washing cycles.

The results obtained (average ratings and mass losses) are shown in table 3.

There is an absence of corrosion by the formulations L1 and L2 according to the invention.

Examples 12-14 GLASS CORROSION TEST

This simplified glass corrosion test reproduces certain washing conditions for dishwasher machines, in particular washing, rinsing and drying cycles.

Nature of glass

Si: 21-43% en poids

Ca : 2,8-5,8% en poids

Mg : 1,6-3,4% en poids

Na : 6,8-14,2% en poids

Al : 0,3-0,7% en poids

The glass used is made up of microscopy slides of dimension 2.5 × 7.5 cm, previously cleaned with ethanol, slides whose composition given below is close to that of table glasses.

If: 21-43% by weight

Ca: 2.8-5.8% by weight

Mg: 1.6-3.4% by weight

Na: 6.8-14.2% by weight

Al: 0.3-0.7% by weight

Procedure

200 ml of an aqueous washing solution containing 6 g / l of product to be tested. The container is introduced and kept in an oven at 65 ° C for 1 hour. In this container, a glass slide is completely immersed in position inclined. The container is then closed, then placed in an oven at 65 ° C. The blade is take out of the container after 4 p.m., rinsed twice on each side with deionized water using a wash bottle, touched with your finger to remove any film that may have formed, air-dried for 2 hours.

At the end of the test, the slide is weighed after cooling to room temperature and the change in relative mass (in% x 1000) is calculated. The test is reproduced another times for confirmation of results.

Corrosion visible to the eye is evaluated, compared to a non-subject reference blade to the test.

Finally, the pH of the solutions is measured at room temperature before the immersion of the blade and end of experience.

This simplified test quickly reproduces the different types of corrosion glass obtained by repeated washing in a dishwasher, the succession of wash-rinse-dry, under conditions of concentration and temperature close to those used in dishwashers.

• teneur en TPP (en poids) = 51,7%
• teneur en silicate (en poids) = 22,2%
• teneur en eau (en poids) = 26,2%

comme agents alcalins dans une composition de formulation pour lave-vaisselle donnée au tableau IV.Formulations for dishwashers are prepared by the introduction of cogranules consisting of TPP and sodium silicate with an SiO ₂ / Na ₂ O ratio = 3.3, cogranules the general composition of which is as follows:

• TPP content (by weight) = 51.7%
• silicate content (by weight) = 22.2%
• water content (by weight) = 26.2%

as alkaline agents in a formulation composition for dishwashers given in Table IV.

The above glass corrosion test is carried out. The results are shown in Table IV.

Examples 15-18

• teneur en carbonate (en poids) = 25,5%
• teneur en silicate (en poids) = 31,1%
• teneur en eau (en poids) = 37,4%

comme agents alcalins dans une composition de formulation (sans tripolyphosphate de sodium) pour lave-vaisselle donnée au tableau V.Formulations for dishwashers are prepared by the introduction of cogranules consisting of sodium silicate with an SiO ₂ / Na ₂ O ratio = 3.9 and of light sodium carbonate, cogranulated, the general composition of which is as follows:

• carbonate content (by weight) = 25.5%
• silicate content (by weight) = 31.1%
• water content (by weight) = 37.4%

as alkaline agents in a formulation composition (without sodium tripolyphosphate) for dishwashers given in Table V.

The above glass corrosion test (described in Examples 12-14) is carried out for 65 hours (instead of 16 hours).

The results are given in Table V. Example (mixture or co-granulated) Formulation 1 (mixture A) comparison 2 (co-granulated B) RHODIAPHOS LV (TPP Na at 7% water) as is 37 TPP Na (expressed in sec) 34.4 atomized silicate R 2.1 (20% water) as is 23.1 silicate R 3.11 (expressed in sec) 18.5 nonionic surfactants 2 2 bleaching system (perborate, 1 H ₂ O + TAED ) 10 10 enzyme 2 2 sodium sulfate 25.9 20 water (qs 100) 0 13.1 pH 10.8 10.24 Si (OH) ₄ (mmol / l) 1.1 3.75 Corrosion Visible aspect / (notation) Relative mass loss (1000%) Visible aspect / (notation) Relative mass loss (1000%) standard wine balloon glasses strong iridescence
(2.5) 9.6 new look
(1) -1.1 standard fruit glasses, round strong iridescence
(2.5) 9.9 new look
(1) 3.4 Cherry glasses Matt decor
(2.5) 49.3 new look
(1) 0.6 red stripe pattern glasses Matt decor
(2.5) 18.8 new look
(1) -0.8 Example (mixture or co-granulated) Formulation 3 (C) comp. 4 (D) comp. 5 (E) comp. 6 (F) comp. 7 (E) 8 (E) RHODIAPHOS LV (TPP Na at 7% water) as is 30.0 34.4 TPP Na (expressed in sec) 35.0 34.5 35.0 35.0 metasilicate GA5 53.3 atomized silicate R 2.1 (20% water) as is 30.0 silicate R 3.11 (expressed in sec) 14.2 11.3 14.2 14.2 sodium carbonate 0 8.7 20.0 5 5 0 sodium sulfate 0 4.7 1.5 22.9 16.5 21.3 nonionic surfactants 2 2 2 2 2 2 bleaching system (perborate, 1 H ₂ O + TAED ) 10 10 10 10 10 10 enzyme 2 2 2 2 2 2 water qs 100 qs 100 qs 100 qs 100 qs 100 qs 100 pH 12.42 10.85 10.52 10.26 10.29 10.16 Si (OH) ₄ (mmol / l) 0.02 1.60 1.69 2.19 2.61 3.25 Corrosion notation 1.2 3.8 3.3 2.3 1.6 1.0 Relative mass loss (1000%) 44.4 23.9 18.2 11.6 1.8 1.2 Example 1 Formulation 9
L1 10
L2 11
L3
comparative. TPP Na (expressed in sec) 23.0 23.5 23.0 silicate R = 3.13 (expressed in sec) 23.0 silicate R = 2.73 (expressed in dry) 23.5 silicate R = 2 (expressed in dry) 23.4 surfactant 0.6 0.5 1.6 bleaching agent 1.5 1.5 2 water 51.9 51.0 50.0 pH 10.28 10.42 11.14 Si (OH) ₄ (mmol / l) 4.14 3.26 0.60 Corrosion white glass - Rating - 1.00 1.00 4 white glass - Relative mass loss (1000%) - 0 0 18.59 decorated glass - Rating - 1.00 1.00 2.62 decorated glass - Relative mass loss (1000%) - 0 0 39.42 Example Formulation 12 13
comparative 14 1 comparison co-granulated TPP / silicate 67.7 67.7 67.7 sodium carbonate 0 10 15 sodium sulfate 21.3 11.3 6.3 nonionic surfactants 1 1 1 bleaching system (perborate, 1 H ₂ O + TAED ) 10 10 10 pH 10.16 10.37 10.45 Si (OH) ₄ (mmol / l) 3.48 2.41 2.08 Corrosion notation 1 2.5 3 Relative mass loss (1000%) 0.00 46.84 48.80 Example
Formulation 15 16 17 18 carbonate / silicate co-granulates 60 60 60 60 citrate 17 0 17 0 sodium sulfate 0 17 4.5 21.5 polyacrylate 6 6 6 6 paraffin 0.5 0.5 0.5 0.5 nonionic surfactant 2 2 2 2 bleaching system (perborate, 1 H ₂ O + TAED ) 10 10 10 10 phosphonate 4.5 4.5 0 0 pH 10.28 10.25 10.25 10.25 Si (OH) ₄ (mmol / l) 3.85 4.06 4.06 4.27 Corrosion notation 1 1 1 1 Relative mass loss (1000%) 0.00 -1.06 0.00 1.05

Claims (15)

1. Use, to eliminate or limit the corrosion of glass, crystal or porcelain articles and patterns on glass or porcelain by repeated washing in a dishwasher, of a detergent composition which generates a washing medium with a concentration of protonated silicic monomer Si(OH)₄ of at least 2.5 × 10^-3 mol/litre of washing medium, preferably of at least 3 × 10^-3 mol/ litre of washing medium, most particularly from about 3 × 10^-3 to about 9 × 10^-3 mol/litre of washing medium.
2. Use according to Claim 1, characterized in that the washing medium has a pH of greater than 9.8, preferably from about 9.9 to about 11.1.
3. Use according to Claim 1 or 2, characterized in that the said detergent composition comprises at least one soluble alkali metal silicate, which is preferably amorphous, with an average SiO₂/M₂O molar ratio from about 1 to about 4.2, preferably from about 2.5 to about 4.2, M representing an alkali metal.
4. Process for the non-corrosive washing in a dishwasher of glass, crystal or porcelain articles which may be patterned, by using a detergent composition which generates a washing medium with a concentration of protonated silicic monomer Si(OH)₄ of at least 2.5 × 10^-3 mol/litre of washing medium, preferably of at least 3 × 10^-3 mol/litre of washing medium, most particularly from about 3 × 10^-3 to about 9 × 10^-3 mol/litre of washing medium.
5. Process according to Claim 4, characterized in that the washing medium has a pH of greater than 9.8, preferably from about 9.9 to about 11.1.
6. Process according to Claim 4 or 5, characterized in that the said detergent composition comprises at least one alkali metal silicate, which is preferably amorphous, with an average SiO₂/M₂O molar ratio from about 1 to about 4.2, preferably from about 2.5 to about 4.2, M representing an alkali metal.
7. Dishwasher detergent composition based on soluble, preferably amorphous, alkali metal silicate(s) with an average SiO₂/M₂O molar ratio from about 1 to about 4.2, preferably from about 2.5 to about 4.2, M representing an alkali metal, this composition being non-corrosive towards glass, crystal, porcelain and patterns and generating, at the working concentration, a washing medium with a concentration of protonated silicic monomer Si(OH)₄ of at least 2.5 × 10^-3 mol/litre of washing medium, preferably of at least 3 × 10^-3 mol/litre of washing medium, most particularly from about 3 × 10^-3 to about 9 × 10^-3 mol/litre of washing medium.
8. Detergent composition according to Claim 7, characterized in that the washing medium has a pH of greater than 9.8, preferably from about 9.9 to about 11.1.
9. Detergent composition according to Claim 7 or 8 or implementation for the use forming the subject of Claim 3 or for carrying out the process forming the subject of Claim 6, characterized in that the amount, by dry weight, of alkali metal silicate(s) represents from about 5 to about 55%, preferably from about 10 to about 40%, of the dry weight of the said composition.
10. Detergent composition according to Claim 9 or implementation for the use forming the subject of Claim 3 or for carrying out the process forming the subject of Claim 6, characterized in that the alkali metal silicate is a metasilicate in the form of powder or granules.
11. Detergent composition according to Claim 9 or implementation for the use forming the subject of Claim 3 or for carrying out the process forming the subject of Claim 6, characterized in that the alkali metal silicate is an amorphous disilicate in the form of a solid preformulation, preferably in the form of cogranules, which is obtained by adsorption and/or absorption of a concentrated alkali metal silicate solution generally containing about 45% solids onto a soluble inorganic support such as an alkali metal tripolyphosphate and/or alkali metal carbonate and/or alkali metal bicarbonate and/or alkali metal sesquicarbonate and/or alkaline sulphate, the amount of water remaining bound to the silicate corresponding to a ratio: silicate-bound water/silicate expressed as solids of at least 20/100, preferably of at least 30/100.
12. Detergent composition according to Claim 9 or implementation for the use forming the subject of Claim 3 or for carrying out the process forming the subject of Claim 6, characterized in that the alkali metal silicate has an average SiO₂/M₂O molar ratio from about 2.5 to about 4.2 and is used in the form of a concentrated aqueous solution containing from about 25 to about 50% solids, or in the form of a liquid preformulation in a liquid or gel detergent composition, or in the form of a solid preformulation in a composition in powder or tablet form.
13. Solid detergent composition according to Claim 12 or implementation for the use forming the subject of Claim 3 or for carrying out the process forming the subject of Claim 6, characterized in that the alkali metal silicate has an average SiO₂/M₂O molar ratio from about 2.5 to about 4.2, preferably from about 2.6 to about 3.5, and is used via a solid preformulation consisting of cogranules obtained by adsorption and/or absorption of a concentrated alkali metal silicate solution with an average SiO₂/M₂O molar ratio from about 2.5 to about 4.2, preferably from about 2.6 to about 3.5, which is adsorbed and/or absorbed onto at least one watersoluble inorganic support which is compatible with the desired pH, chosen from sodium sesquicarbonate and/or mixtures of sodium carbonate and sodium bicarbonates and/or, preferably, sodium tripolyphosphate, the silicate/inorganic support weight ratio, expressed as solids, being from about 20/80 to about 60/40, preferably from about 25/75 to about 50/50, and optionally drying until the amount of water present in the said preformulation represents from about 10 to about 35% of the weight of the said preformulation, and until the amount of water remaining bound to the silicate corresponds to a ratio: silicate-bound water/silicate expressed as solids of at least 20/100, preferably of at least 30/100, the pH of this preformulation at its concentration in the washing medium preferably being greater than 9.8, most particularly from about 9.9 to about 10.8.
14. Solid detergent composition according to Claim 12 or implementation for the use forming the subject of Claim 3 or for carrying out the process forming the subject of Claim 6, characterized in that the alkali metal silicate has an average SiO₂/M₂O molar ratio from about 3 to about 4.2, preferably from about 3.3 to about 4, and is used via a solid preformulation consisting of cogranules obtained by adsorption and/or absorption of a concentrated alkali metal silicate solution with an average SiO₂/M₂O molar ratio from about 3 to about 4.2, preferably from about 3.3 to about 4, which is adsorbed and/or absorbed onto sodium carbonate, the silicate/carbonate weight ratio, expressed as solids, being from about 40/60 to about 80/20, preferably from about 50/50 to about 70/30, and optionally drying until the amount of water present in the said preformulation represents from about 15 to about 35% of the weight of the said preformulation, and until the amount of water remaining bound to the silicate corresponds to a ratio: silicate-bound water/silicate expressed as solids of at least 20/100, preferably of at least 30/100, the pH of this preformulation at its concentration in the washing medium preferably being greater than 9.8, most particularly from about 9.9 to about 10.8.
15. Liquid detergent composition according to Claim 12 or implementation for the use forming the subject of Claim 3 or for carrying out the process forming the subject of Claim 6, characterized in that the alkali metal silicate has an average SiO₂/M₂O molar ratio from about 2.5 to about 3.5, preferably from about 2.6 to about 3.3, and is used via a liquid preformulation consisting of a dispersion, in a concentrated silicate solution with an average SiO₂/M₂O molar ratio from about 2.5 to about 3.5, preferably from about 2.6 to about 3.3, containing from about 25 to about 50% solids, of a watersoluble inorganic sodium tripolyphosphate, which is preferably sprayed, and/or sodium carbonate compound, the silicate/water-soluble inorganic compound weight ratio, expressed as solids, being from about 70/30 to about 30/70, preferably from about 60/40 to about 35/65, the amount of water present in the said preformulation representing from about 40 to about 65% of the weight of the said preformulation, the pH of this preformulation at its concentration in the washing medium preferably being greater than 9.8, most particularly from about 9.9 to about 10.8.

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