Clear rinsing agents

Details Clear rinsing agents Clear rinsing agents

2002-11-25

2004-05-11

Mruk, Brian P. (Department: 1751)

Cleaning and liquid contact with solids

Processes

Work handled in bulk or groups

C134S025300, C134S039000, C134S040000, C134S042000, C510S220000, C510S356000, C510S360000, C510S421000, C510S422000, C510S470000, C510S475000, C510S505000, C510S506000, C510S514000, C510S524000

Reexamination Certificate

active

06732748

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to rinse agents for dishwashing machines containing hydroxy mixed ethers and alkyl and/or alkenyl oligoglycosides, optionally other nonionic surfactants, water and other auxiliaries and additives, to the use of such mixtures in rinse agents and to a process for rinsing and cleaning hard surfaces.
PRIOR ART
Today, machine-washed tableware has to meet stricter requirements than hand-washed tableware. Thus, even tableware completely free from food residues is regarded as unsatisfactory when, after dishwashing, it still has whitish stains which are attributable to water hardness or other mineral salts and which come from water droplets that have remained on the tableware through lack of wetting agent and dried.
Accordingly, to obtain bright, spotless tableware, rinse agents have to be used. The addition of liquid or solid rinse agent ensures that the water drains completely from the tableware so that the various surfaces are bright and free from residues at the end of the dishwashing program.
Commercially available rinse agents are mixtures of nonionic surfactants, solubilizers, organic acids and solvents, water and optionally preservative and perfumes. The function of the surfactants in these compositions is to influence the interfacial tension of the water in such a way that it is able to drain from the tableware as a thin, coherent film so that no droplets of water, streaks or films remain behind during the subsequent drying process (so-called wetting effect). Another function of the surfactants is to suppress the foam generated by food residues in the dishwashing machine. Since the rinse agents generally contain acids to improve the clear drying effect, the surfactants used also have to be relatively hydrolysis-resistant towards acids.
Rinse agents are used both in the home and in the institutional sector. In domestic dishwashers, the rinse agent is added after the prerinse and wash cycle at 40 to 65° C. Institutional dishwashers use only one wash liquor which is merely replenished by addition of the rinse agent solution from the preceding wash cycle. Accordingly, there is no complete replacement of water in the entire dishwashing program. Because of this, the rinse agent is also expected to have a foam-suppressing effect, to be temperature-stable in the event of a marked drop in temperature from 85 to 35° C. and, in addition, to be satisfactorily resistant to alkali and active chlorine.
It is known from hitherto unpublished DE 19851453 that alkoxylated fatty acid lower alkyl esters and in particular mixtures with other nonionic surfactants, such as hydroxy mixed ethers and alkyl and/or alkenyl oligoglycosides, satisfy the performance requirements a commercial product is expected to meet. However, no preferred mixing ratios of hydroxy mixed ethers and alkyl and/or alkenyl oligoglycosides are disclosed in that document.
DE-A 19738866 describes surfactant mixtures of hydroxy mixed ethers and nonionic surfactants, such as optionally end-capped fatty alcohol polyethylene glycol/polypropylene glycol ethers, which have favourable foaming behavior and show good clear rinse effects in rinse agents.
The problem addressed by the present invention was to provide rinse agents which, at one and the same time, would show favorable drainage behavior through improved wetting behavior, would have a foam-suppressing effect and would be distinguished by high material compatibility and in particular by very good plastic compatibility of the rinsed surfaces.
The problem stated above has been solved by a combination of hydroxy mixed ethers and alkyl and/or alkenyl oligoglycosides in the ratio by weight according to the invention. High plastic compatibility and—through the very favorable wetting behavior—a spotless shine of the surfaces to be rinsed are obtained in this way. It should be emphasized that the rinse agents according to the invention generate little foam of their own despite the alkyl and/or alkenyl oligoglycosides which are known to be highly surface-compatible, but have no foam-suppressing effect. It has also been found that the use of the petrochemical solubilizer, cumenesulfonate, can be reduced by up to 75% through the use of hydroxy mixed ethers, particularly in combination with alkyl and/or alkenyl oligoglycosides.
DESCRIPTION OF THE INVENTION
The present invention relates to rinse agents containing
a. hydroxy mixed ethers (HMEs) corresponding to formula (I):
R
1
O[CH
2
CHR
2
O]
x
[CH
2
CHR
3
O]
y
CH
2
CH(OH)R
4
  (I)
in which R
1
is an alkyl and/or alkenyl group containing 4 to 22 carbon atoms,
R
2
is hydrogen or a methyl or ethyl group,
R
3
is hydrogen or a methyl or ethyl group,
R
4
is an alkyl group containing 2 to 22 carbon atoms,
x=0 or 1 to 30,
y=0 or 1 to 30, x+y>=1,
b. alkyl and/or alkenyl oligoglycosides (APGs) corresponding to formula (II):
R
5
O—[G]
p
  (II)
in which R
5
is an alkyl and/or alkenyl group containing 4 to 22 carbon atoms,
G is a sugar unit containing 5 or 6 carbon atoms,
p is a number of 1 to 10,
c. other nonionic surfactants,
d. optionally water,
e. optionally auxiliaries and additives,
HMEs and APGs being present in the rinse agents in a ratio by weight of 10:0.1 to 1:10.
Hydroxy Mixed Ethers
Hydroxy mixed ethers corresponding to formula (I) are known from the literature and are described, for example, in German patent application DE 19738866. They are prepared by reaction of 1,2-epoxyalkanes (R
4
CHOCH
2
), where R
4
is an aliphatic saturated, linear or branched alkyl group containing 2 to 22 and more particularly 6 to 16 carbon atoms, with alkoxylated alcohols. Hydroxy mixed ethers preferred for the purposes of the invention are those derived from alkoxylates of monohydric alcohols with the formula R
1
—OH containing 4 to 18 carbon atoms, R
1
being an aliphatic, saturated, linear or branched alkyl group, more particularly containing 6 to 16 carbon atoms. Examples of suitable straight-chain alcohols are butan-1-ol, caproic alcohol, oenanthic alcohol, caprylic alcohol, pelargonic alcohol, capric alcohol, undecan-1-ol, lauryl alcohol, tridecan-1-ol, myristyl alcohol, pentadecan-1-ol, palmityl alcohol, heptadecan-1-ol, stearyl alcohol, nonadecan-1-ol, arachidyl alcohol, heneicosan-1-ol, behenyl alcohol and the technical mixtures thereof obtained in the high-pressure hydrogenation of technical methyl esters based on fats and oils. Examples of branched alcohols are so-called oxo alcohols which generally contain 2 to 4 methyl groups as branches and are produced by the oxo process and so-called Guerbet alcohols which are branched in the 2-position by an alkyl group. Suitable Guerbet alcohols are 2-ethyl hexanol, 2-butyl octanol, 2-hexyl decanol and/or 2-octyl dodecanol.
The alcohols are used in the form of their alkoxylates which are prepared in known manner by reaction of the alcohols in any order with ethylene oxide, propylene oxide and/or butylene oxide. Alkoxylates of alcohols formed by reaction with 10 to 50 mol ethylene oxide (R
2
and R
3
=hydrogen and x+y=1-50) are preferably used. Both alkoxylates obtained by reaction of alcohol with 1 to 10 mol propylene oxide (R
2
=methyl, x=1-10) and 10 to 30 mol ethylene oxide (R
3
=hydrogen, y=10-30) and those obtained by reaction of alcohol with 10 to 30 mol ethylene oxide (R
2
=hydrogen, x=10-30) and 1 to 10 mol propylene oxide (R
3
=methyl, y=1-10) are preferred.
Particularly suitable hydroxy mixed ethers are those corresponding to formula (I), where R
2
is a methyl group and R
3
is hydrogen, which have advantageously been produced by reaction of alcohol with 1 to 3 mol propylene oxide (x=1-3) and then with 10 to 25 mol ethylene oxide (y=10-25).
Alkyl and/or Alkenyl Oligoglycosides
The rinse agents according to the invention contain alkyl and/or alkenyl oligoglycosides corresponding to formula (II) as compulsory components. They may be obtained by the relevant methods of preparative or

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