EP0444415B1 - Detergent composition comprising partially dehydrated disilicate - Google Patents

Description

The invention relates to a phosphate-free detergent with 5 to 50% by weight, preferably 10 to 30% by weight, at least one surfactant, 0.5 to 60% by weight of a builder and conventional washing aids.

It has been state of the art for more than 80 years to incorporate sodium silicates into detergent formulations, usually in the form of their aqueous solution, also known as water glass.

Sodium silicates have long been used as builders in detergents, especially in conjunction with soda, but in the course of modern detergent development they have been used with substances with better builder properties, e.g. condensed phosphates, detached.

Due to the restrictive detergent phosphate legislation that has come into force in many countries in Europe and the USA, zeolite 4A in combination with polycarboxylates is the basic builder for many detergent products. The addition of amorphous sodium disilicate in the form of water glass or as a powder in an amount of around 5% by weight is still common today in the majority of the detergents produced. The task assigned to sodium disilicate is not limited to its corrosion-inhibiting effect. It also serves as a builder with good absorption properties for liquid components and improves the dirt-carrying capacity of the wash liquor due to its dispersing effect. It also binds some of the hardness in the wash water and thereby also favors the washing result.

Amorphous, anhydrous sodium disilicates are also a component of phosphate-containing cleaners for use in automatic dishwashers (cf. US Pat. Nos. 4,077,897, 4,199,468 and EP-A-0 256 679).

As has now surprisingly been found, the washing properties of commercially available sodium disilicate, which normally have water contents of 15-23% by weight, can be significantly increased if a partial dewatering of these products is carried out.

For the partial dewatering of such sodium disilicate to amorphous sodium disilicate with water contents of 0.3 to 6% by weight, preferably 0.5 to 2% by weight, e.g. the powdery amorphous sodium disilicate with a water content of 15 to 23 wt .-% in an inclined, equipped with equipment for moving solid rotary kiln in which it is flue gas at temperatures of 250 to 500 ° C for 1 to 60 minutes Treated countercurrent, the rotary kiln is insulated so that the temperature of its outer wall is less than 60 ° C. The amorphous sodium disilicate emerging from the rotary kiln can be comminuted to grain sizes of 0.1 to 12 mm using a mechanical crusher. The comminuted sodium disilicate is preferably milled to a grain size of 2 to 400 »m, the mill being operated at a peripheral speed of 0.5 to 60 m / s.

In detail, the phosphate-free detergent of the present invention is now characterized in that it contains an amorphous, low-water sodium disilicate with a water content of 0.3 to 6% by weight, preferably 0.5 to 2% by weight, as a builder.

Starting from a commercially available sodium disilicate with a water content of 18% by weight, the following partially dewatered products were produced: example Water content (% by weight H₂O) I (starting product) 18th II 0.3 III 0.7 IV 1.5 V 3.1 VI 5

Detergents were produced according to the basic formulation below using the individual sodium disilicate species (NaDS; Examples I - VI):

2.5 g and 4.5 g of the Na disilicates according to Examples I - VI were dissolved in 1000 ml of water with a hardness of 18 ° dH to determine their water hardness binding capacity (remaining water hardness), the solution exactly 1 / Stirred for 2 hours at 60 ° C using a magnetic stirrer at approx. 500 rpm, then quickly cooled to 2 ° C in ice water and then freed from the insoluble residue using a membrane filter with a pore size of 0.45 »m. The same procedure was also carried out with the water used at 18 ° dH without the addition of Na disilicate in order to eliminate the error which would result from a possible precipitation of Ca and Mg as carbonate.

In the same way, 10 g of the detergents based on the above basic formulation were dissolved with Na disilicate in accordance with Examples I-VI in water at 18 ° dH and the solutions were treated as described above. The basic formulation without the addition of Na disilicate was included as a blank in the test series.

In the filtrates of the individual solutions and in the identically treated and filtered water without addition, the residual contents of calcium and magnesium were determined by means of atomic absorption, which are summarized in Table 1:

The values found for the residual water hardness clearly show the superiority of the partially dewatered sodium disilicates (Example II-VI) compared to the starting products with 18% by weight H₂O (Example I).

Since generally a higher ability to bind the water hardness can also be expected to improve the washing results, washing tests (type A) which were equipped with the individual Na disilicate species in accordance with Examples I-VI were carried out in one test Household washing machine carried out under the following conditions: Washing machine: Miele TMT Temperature: 60 ° C Water hardness: 18 ° dH Ballast: 3.75 kg of unpolluted test fabric Program: Soaking process Detergent dosage: 175 g

Test fabrics used:

• a) Für Primärwaschwirkung (Schmutzentfernung und Bleiche):
  EMPA BW 101 (Standard-Anschmutzung)
  EMPA PE/BW 104 (Standard-Anschmutzung)
  WFK BW 10C (Standard-Anschmutzung)
  WFK BW 10G (Tee-Anschmutzung)
  WFK PE/BW 20G (Tee-Anschmutzung)
• b) Für Sekundärwaschwirkung:
  EMPA - Baumwolle
  WFK - Frottee

Die Prüfung der Primärwaschwirkung wurde mittels optischer Remissionsmessung vorgenommen und in Form der Remissionsdifferenz ausgedrückt, die sich aus der Differenz der Werte nach und vor dem Waschen ergibt:

${\text{ΔR = R}}_{\text{n}}{\text{- R}}_{\text{v}}$

ΔR

= Remissionsdifferenz (%)

R_n

= Remission nach dem Waschen (%)

R_v

= Remission vor dem Waschen (%)

Der Aschewert, als Maß für die Gewebeinkrustation, wurde nach 25 Waschgängen bestimmt, indem der prozentuale Glührückstand bei 800°C ermittelt wurde.(EMPA = Federal Material Testing Institute St. Gallen, Switzerland;
WFK = laundry research Krefeld)

• a) For primary washing effects (dirt removal and bleaching):
  EMPA BW 101 (standard soiling)
  EMPA PE / BW 104 (standard soiling)
  WFK BW 10C (standard soiling)
  WFK BW 10G (tea soiling)
  WFK PE / BW 20G (tea soiling)
• b) For secondary washing action:
  EMPA - cotton
  WFK - Terrycloth

The primary washing effect was checked by means of optical reflectance measurement and expressed in the form of the reflectance difference, which results from the difference between the values after and before washing:

${\text{ΔR = R}}_{\text{n}}{\text{- R}}_{\text{v}}$

ΔR

= Reflectance difference (%)

R _n

= Remission after washing (%)

R _v

= Remission before washing (%)

The ash value, as a measure of the tissue incrustation, was determined after 25 washes by determining the percentage of the residue on ignition at 800 ° C.

Table 2 summarizes the washing results obtained with the detergents (type A) based on the Na disilicate in accordance with Examples I-VI. As expected, the detergents (type A) equipped with partially dewatered sodium disilicate show a clear superiority over the detergent formulation based on the starting product (example I, sodium disilicate with 18% H₂O).

The detergents (type A) prepared on the basis of Examples I-VI were also subjected to a test for determining the storage stability. The individual detergent samples were sealed in closed cardboard boxes (wax cardboard, water vapor permeability: approx. 10 gm⁻² day ⁻¹) in a climatic cabinet at 37 ° C and 70% rel. Humidity stored for 4 weeks. The flowability was assessed in accordance with Table 3. As can be seen in Table 3, the detergents (type A) based on the partially dewatered products according to the invention (Examples II-VI) are clearly superior in that they more or less retain their pourability, while the commercially available Na disilicate (Example I) is below the selected storage conditions completely hardened.

Anionic surfactants are to be understood as meaning the water-soluble salts of higher fatty acids or resin acids, such as sodium or potassium soaps from coconut, palm kernel or turnip oil, and from tallow and mixtures thereof. These also include higher alkyl-substituted aromatic sulfonates, such as alkylbenzenesulfonates with 9 to 14 carbon atoms in the alkyl radical, alkylnaphthalenesulfonates, alkyltoluenesulfonates, alkylxylenesulfonates or alkylphenolsulfonates; Fatty alcohol sulfates (R-CH₂-O-SO₃Na; R = C₁₁₋₁₇) or fatty alcohol ether sulfates, such as alkali lauryl sulfate or alkali hexadecyl sulfate, triethanolamine lauryl sulfate, sodium or potassium oleyl sulfate, sodium or potassium salts of with 2 to 6 moles of ethylene oxide ethoxylate. Other suitable anionic surfactants are secondary linear alkane sulfonates and α-olefin sulfonates with a chain length of 12-20 C atoms.

Schließlich umfassen Tenside mit zwitterionischem (ampholytischem) Charakter folgende Verbindungen:
Derivate von aliphatischen, sekundären und tertiären Aminen oder quaternären Ammoniumverbindungen mit 8 bis 18 C-Atomen und einer hydrophilen Gruppe im aliphatischen Rest, wie z.B. Natrium-3-dodecylaminopropionat, Natrium-3-dodecylaminopropansulfonat, 3-(N,N-Dimethyl-N-hexadecyl-amino)-propan-1-sulfonat oder Fettsäureaminoalkyl-N,N-dimethylacetobetain, wobei die Fettsäure 8 bis 18 C-Atome und der Alkylrest 1 - 3 C-Atome enthält.Nonionic surfactants are understood to mean those compounds which have an organic, hydrophobic group and a hydrophilic radical, for example the condensation products of alkylphenols or higher fatty alcohols with ethylene oxide (fatty alcohol ethoxylates), the condensation products of polypropylene glycol with ethylene oxide or propylene oxide, the condensation products of ethylene oxide with the Reaction product from ethylenediamine and propylene oxide, as well as long-chain tertiary amine oxides

Finally, surfactants with a zwitterionic (ampholytic) character include the following compounds:
Derivatives of aliphatic, secondary and tertiary amines or quaternary ammonium compounds with 8 to 18 carbon atoms and a hydrophilic group in the aliphatic radical, such as sodium 3-dodecylaminopropionate, sodium 3-dodecylaminopropanesulfonate, 3- (N, N-dimethyl-N -hexadecyl-amino) -propane-1-sulfonate or fatty acid aminoalkyl-N, N-dimethylacetobetaine, where the fatty acid contains 8 to 18 carbon atoms and the alkyl radical contains 1 to 3 carbon atoms.

Suitable washing auxiliaries according to the invention are weakly acidic, neutral or alkaline inorganic or organic salts, in particular inorganic or organic complexing agents.

Useful, weakly acidic, neutral or alkaline-reacting salts are, for example, the bicarbonates or carbonates of the alkalis, furthermore the alkali salts of organic, non-capillary-active sulfonic acids, carboxylic acids and sulfocarboxylic acids containing 1 to 8 carbon atoms. These include, for example, water-soluble salts of benzene, toluene or xylene sulfonic acid, water-soluble salts of sulfoacetic acid, sulfobenzoic acid or salts of sulfodicarboxylic acids as well as the salts of acetic acid, lactic acid, citric acid, tartaric acid, oxydiacetic acid (HOOC-CH₂-O-CH₂-COOH) acid, oxydib , 1,2,3,4-cyclopentanetetracarboxylic acid, polycarboxylates, polyacrylic acid and polymaleic acid. The organic complexing agents include, for example, nitrilotriacetic acid, ethylenediaminetetraacetic acid, N-hydroxyethylethylenediaminetriacetic acid or polyalkylene-polyamine-N-polycarboxylic acids.

Washing aids according to the invention also include products such as the alkali or ammonium salts of sulfuric acid, boric acid, alkylene, hydroxyalkylene or aminoalkylenephosphonic acid, as well as bleaching agents, stabilizers for peroxide compounds (bleaching agents) and water-soluble organic complexing agents.

In particular, the bleaching agents include sodium perborate or tetrahydrate, sodium percarbonate, the alkali metal salts of peroxomono- or peroxodisulfuric acid, the alkali metal salts of peroxodiphosphoric acid (H₄P₂O₈), and alkali metal salts of peroxocarboxylic acids, such as diperoxododecanedioic acid. Examples of stabilizers for these bleaching agents are water-soluble, precipitated magnesium silicate, organic complexing agents such as the alkali salts of iminodiacetic acid, nitrilotriacetic acid, ethylenediaminetetraacetic acid, methylene diphosphonic acid, 1-hydroxyethane-1,1-diphosphonic acid and nitrilotrismethylenephosphonic acid.

Washing aids that increase the dirt-carrying capacity of washing liquors, such as carboxymethyl cellulose, carboxymethyl starch, methyl cellulose or copolymers of maleic anhydride with methyl vinyl ether or acrylic acid, foam regulators, such as mono- and dialkyl phosphoric acid esters with 16 to 20 carbon atoms in the alkyl radical, and optical brighteners, disinfectants and enzymes, such as proteas , Amylases, lipases can also be additional components of the detergent of the invention.

Claims (4)

1. A process for the production of a phosphate-free detergent which comprises intensively mixing 5 to 50 % by weight of at least one surfactant and 0.5 to 60 % by weight of amorphous low-water sodium disilicate having a water content of 0.3 to 6 % by weight as matrix substance together with standard laundry aids.
2. The process as claimed in claim 1, wherein the amorphous sodium disilicate contains 0.5 to 2 % by weight of water.
3. The process as claimed in claim 1 or 2, wherein the amorphous low-water sodium disilicate has been produced by partial dehydration of commercial powdered amorphous sodium disilicate having a water content of 15 to 23 % by weight.
4. The process as claimed in claim 3, wherein the amorphous low-water sodium disilicate has been obtained by introducing the powdered amorphous sodium disilicate having a water content of 15 to 23 % by weight into a rotary tubular kiln arranged at an angle and fitted with devices for agitating solid, by treating it for 1 to 60 minutes in the rotary tubular kiln in countercurrent with furnace gas at temperatures from 250 to 500°C, the rotary tubular kiln having been insulated in a manner such that the temperature of its outside wall was less than 60°C, and by comminuting the amorphous sodium disilicate emerging from the rotary tubular kiln to a particle size of 0.1 to 12 mm with a mechanical crusher and then grinding to a particle size of 2 to 400 »m.