Machine dishwashing detergent

Details Machine dishwashing detergent Machine dishwashing detergent

1999-11-24

2003-04-01

Gupta, Yogendra N. (Department: 1751)

Cleaning and liquid contact with solids

Processes

Work handled in bulk or groups

C134S025200, C134S039000, C134S040000, C134S042000, C510S220000, C510S221000, C510S222000, C510S232000, C510S466000, C510S511000

Reexamination Certificate

active

06539954

ABSTRACT:

FIELD OF THE INVENTION
The invention relates to a liquid to paste machine dishwashing detergent, to a process for its preparation and to its use.
DESCRIPTION OF THE RELATED ART
Solid detergents for machine dishwashing are largely supplied in powder or granular form (agglomerates). A serious disadvantage of this type of solid detergents is that there is a strong tendency towards caking or clumping due to the hygroscopicity of individual raw materials when small amounts of moisture enter. This can sometimes lead to a loss in cleaning action and additionally leads the user to believe that the quality is reduced for optical reasons.
Liquid dishwashing detergents, as are used especially in the large-scale commercial sector, are unsuitable for use in automatic household dishwashing machines in the domestic sector primarily because of their insufficiently low viscosity and their high alkalinity, since these products must be characterized as “irritant” and thus represent a great safety risk in the home. In addition, retention of the dishwashing detergent in standard domestic dosing devices is not ensured in most cases.
Standard commercial gelatinous or thixotropic dishwashing detergents comprise greater or lesser amounts of alkali metal silicates, generally in the form of aqueous solutions (water glass), for example in the ratio Na
2
O:SiO
2
of 1:2 to 1:3.3, which are used to achieve the desired alkalinity and as corrosion inhibitors for the glaze and decoration on porcelain.
It has, however, been found that dishwashing detergents with such decoration and glaze protection have the disadvantage that they form deposits of varying severity on the remainder of the ware, particularly on glasses; they form initially in bright tarnish colors, and subsequently in whitish-opaque bluish adherent films and can only be removed with extremely strong acids, for example a hydrofluoric acid/sulfuric acid mixture. Such dishwashing detergents are therefore unsuitable for use over a prolonged period.
The object of the invention is therefore to provide a non-solid machine dishwashing detergent which, as well as having a good cleaning action, results in less corrosion, in particular on glasses and porcelain plates, and produces fewer deposits compared with the prior art.
SUMMARY OF THE INVENTION
This object is achieved by a machine dishwashing detergent of the type mentioned in the introduction, which, in addition to customary machine dishwashing detergent ingredients, comprises a crystalline, layered silicate of the formula
a
A
2
O.
b
BO.
c
C
2
O
3
.d
D
2
O
5
.e
SiO
2
.f
H
2
O,
in which A is an alkali metal and/or hydrogen, B is an alkaline earth metal, C is an element from the third main group of the Periodic Table, and D is an element from the fifth main group of the Periodic Table, and the following also apply: 0≦a≦1; 0≦b≦0.5; 0≦c/e≦0.05; 0 ≦d/e≦0.25; 1.9≦e≦4; 0≦f≦20.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The machine dishwashing detergent preferably comprises from 1 to 50% by weight of the crystalline layered silicate.
The machine dishwashing detergent particularly preferably comprises from 5 to 30% by weight of the crystalline layered silicate.
The crystalline layered silicate is preferably essentially disodium disilicate.
The disodium disilicate is preferably layered crystalline disodium disilicate which consists of at least one of the polymorphic phases of disodium disilicate and of sodium silicates of a nonphyllosilicatic nature.
The layered crystalline disodium disilicate preferably consists of (the following data refer to percentages by weight) from 1 to 40% of alpha-disodium disilicate, from 0 to 50% of beta-disodium disilicate, from 50 to 98% of delta-disodium disilicate and from 0 to 40% of nonphyllosilicatic sodium silicates.
In another embodiment of the invention, the layered crystalline disodium disilicate consists of from 0 to 40% of alpha-disodium disilicate, from 20 to 98% of beta-disodium disilicate, from 0 to 40% of delta-disodium disilicate and from 0 to 50% of nonphyllosilicatic sodium silicates.
In another embodiment of the invention, the layered crystalline disodium disilicate consists of from 20 to 98% of alpha-disodium disilicate, from 0 to 40% of beta-disodium disilicate, from 0 to 50% of delta-disodium disilicate and from 0 to 50% of nonphyllosilicatic sodium silicates.
The definitions of alpha-, beta- and delta-disodium disilicate are known and can be found, for example, in EP 0 164 514.
The crystalline layered silicate in the machine dishwashing detergent according to the invention preferably comprises up to 10 mol % of boron, based on SiO
2
.
The crystalline layered silicate in the machine dishwashing detergent according to the invention preferably comprises up to 50 mol % of phosphorus, based on SiO
2
.
The machine dishwashing detergent preferably also comprises at least a surfactant and/or a bleach and/or a rheological additive and/or a dispersant and/or a dispersion medium.
The machine dishwashing detergent preferably comprises, as surfactants, block polymers of long-chain aliphatic alcohols with ethylene oxide or propylene oxide groups, modified fatty alcohol polyglycol ethers, mono- and dialkylsulfates, alkanesulfonates, amine oxides and/or fatty acid methylpolyglycol esters.
The machine dishwashing detergent preferably comprises, as bleach, active chlorine carriers and/or active oxygen carriers.
The machine dishwashing detergent preferably comprises, as rheological additive and/or dispersant, carboxymethylcellulose, polycarboxylates, phosphonates and/or synthetic clays.
The machine dishwashing detergent preferably comprises, as dispersion medium, ethylene glycols, cooligomers/copolymers of propylene oxide and ethylene oxide and/or water.
In addition to the customary machine dishwashing detergent ingredients, the machine dishwashing detergent preferably comprises
from 2.5 to 50% by weight of crystalline layered sodium disilicate
from 0 to 20% by weight of surfactant
from 0 to 40% by weight of sodium tripolyphosphate
from 0 to 20% by weight of bleach
from 0.1 to 15% by weight of rheological additive and/or dispersant
from 50 to 80% by weight of dispersion medium as other ingredients.
In addition to the customary machine dishwashing detergent ingredients, the machine dishwashing detergent preferably comprises
from 5 to 30% by weight of crystalline layered sodium disilicate
from 0 to 20% by weight of surfactant
from 15 to 30% by weight of sodium tripolyphosphate
from 5 to 15% by weight of bleach
from 0.1 to 10% by weight of rheological additive and/or dispersant
from 50 to 70% by weight of dispersion medium as other ingredients.
In addition to the customary machine dishwashing detergent ingredients, the machine dishwashing detergent preferably comprises
from 5 to 30% by weight of crystalline layered sodium disilicate
from 5 to 15% by weight of bleach
from 0 to 20% by weight of surfactant
from 0.1 to 10% by weight of rheological additive and/or dispersant
from 30 to 70% by weight of dispersion medium as other ingredients.
In addition to the customary machine dishwashing detergent ingredients, the machine dishwashing detergent preferably comprises
from 10 to 40% by weight of crystalline layered sodium disilicate
from 0 to 20% by weight of surfactant
from 15 to 30% by weight of sodium tripolyphosphate
from 0.1 to 15% by weight of rheological additive and/or dispersant
from 30 to 70% by weight of dispersion medium as other ingredients.
In addition to the customary machine dishwashing detergent ingredients, the machine dishwashing detergent preferably comprises
from 10 to 50% by weight of crystalline layered sodium disilicate
from 0 to 20% by weight of surfactant
from 0.1 to 15% by weight of rheological additive and/or dispersant
from 30 to 70% by weight of dispersion medium as other ingredients.
In the case of the abovementioned preferred compositions, the sodium disilicate is essentially disodium disilicate.
The machine dishwashing detergent according to the invention preferably has corrosion-inhibiting properties.
The machine dishwas

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