DE3133529A1 - Phosphate- and silicate-free low-foaming dishwashing compositions and aqueous concentrates thereof - Google Patents

Abstract

A phosphate-free dishwashing composition contains at least one partially neutralised amino polycarboxylic acid, alkali metal salts of (co)polymers which are free of nitrogen and contain carboxyl groups, alkoxylated H-active compounds whose cloud point is below the temperature of the washing liquor, and, where appropriate (di)alkylbenzenesulphonates and glycols or glycol ethers, where the aqueous solutions of the composition have a pH of from 6 to 8.5. The dishwashing compositions can be employed as aqueous 10 to 70% by weight concentrates.

Description

Low-foaming detergents free of phosphates and silicates

and aqueous concentrates thereof. The invention relates to novel aqueous concentrates Solution almost neutral dishwashing detergents, especially for dishwashers, which can also be handled as aqueous concentrates.

The monograph Catalysts, Surfactants and Mineral Oil Additives, published by J. Falbe and U. Hasserodt, Georg Thieme Verlag Stuttgart, 1978, page 170, column 2 describes machine dishwashing detergents, which are made up of, among other things, low-foam nonionic Surfactants, e.g. fatty alcohol ethoxylates with terminal propylene oxide groups, pentasodium triphosphate ("STP") and sodium metasilicate build up, and which react strongly alkaline, whereby it is clearly indicated that STP and silicates are the main components.

For particularly intensive formulations, such as those in dishwashers because of the short contact times between dirty Items to be washed and cleaning rags are required in the said literature reference an even stronger alkalinity by adding caustic soda or soda is recommended.

DE-OS 27 15 351 describes liquid detergent formulations, which are phosphate-free and, in addition to low-foaming surfactants, the trisodium salt contain nitrilotriacetic acid as a cleaning component.

The disadvantage of phosphate-containing detergents is that they that according to the legislation in many countries the phosphate levels are far too high are, and on the other hand, that the strong alkalinity of these agents unites 'chemical Attack particularly on sensitive items such as glasses or ceramic materials with sensitive glazes that are not highly fired, and finally in that with such agents the high electrolyte content - their handling (transport and storage) as aqueous concentrates, because under these conditions the low-foam nonionic surfactants, which have a low cloud point, are not soluble and precipitate immediately.

The phosphate-free agent according to DE-OS 27 15 351 has these disadvantages to a lesser extent, it still reacts as an aqueous concentrate too strongly alkaline (up to pH = 12), and thus still too aggressive against the mentioned ones sensitive materials, and moreover it must in order to dissolve to a satisfactory extent significant amounts of solubilizers such as sodium cumene sulfonate to be held (approx. 25% - based on non-aqueous components -) and approx. 20% by weight of alkanolamines contain, which naturally means a dilution of the preparations in terms of active ingredient.

The aim of the invention consisted in low-foaming phosphate-free Dishwashing detergents that make the items to be washed as chemically as possible. not attack and anyway show an optimal cleaning effect.

Another goal was to develop such detergents, those even without the compulsory addition of solubilizers or with at most a small amount The addition of such auxiliary substances in the form of aqueous formulations is stable and therefore stable can also be handled in a much better metered form.

This aim was achieved by means as defined in the claims are defined.

In anhydrous form, the agents thus contain a synergistic effective three-way combination in the given proportions, the latter so too are chosen so that aqueous solutions have pH values of 6 to 8.5, i.e. in general react almost neutrally, and it has been shown that this is a chemical attack warts on the items to be washed - for example cloudiness of glass or the appearance of color burns Porcelain or earthenware - can largely be avoided.

The triple combination, which is also exclusive to the non-aqueous Can represent portion of the detergent, contains as component a) - in the following for the sake of simplicity so-called - partially neutralized aminopolycarboxylic acids or Mixtures thereof.

Partial neutralization can be achieved as follows: One can add free aminopolycarboxylic acid directly to alkalis, such as NaOH, to the extent that that the ratio of the neutralized to the free carboxyl groups 5: 1 to 1: 1 amounts to. But you can also use the free aminopolycarboxylic acid with its alkali metal salt Mix in such a way that the mixture obtained also has the same ratio having.

Preferably the ratio of the neutralized to the free Carboxyl groups are 4: 1 to 1: 1. As "AHllnopolycarbonsäuren" come such with 1 to 4 nitrogen atoms, e.g. nitrilotriacetic acid (NTA), ethylenediaminetetraacetic acid (EDTA), diethylenetriaminepentaacetic acid (DETPA) or hydroxyethylenediamine triacetic acid '(HEDTA) into consideration. Technically of particular interest are NTA and EDTA as defined t-neutralized form, for example the disodium salt of NTA, the trisodium salt the EDTA or corresponding mixtures of NTA and its trisodium salt or EDTA and their tetrasodium salt.

The partially neutralized acids are in the triple combination of 2.5 to 20 parts by weight, preferably 2.5 to 15 parts by weight, present. The amount the component a) is within the set limits according to the ratio of the neutralized and free carboxyl groups, i.e. with a higher proportion of free carboxyl groups If it is lower, it should be set higher with lower proportions, so that the above-mentioned pH conditions can be met, and finally the proportion of the below component b) described must be observed. - The optimization of the proportions can be easily achieved through routine preliminary testing.

Component b) is replaced by alkali metal - preferably sodium salts - Represented by carboxyl-containing polymers of the definition according to the claims.

These polymers should be linear and can be homopolymers or copolymers but must be on average per carboxyl-containing monomer unit at least carry a carboxyl group. The carboxyl-containing monomer units can have a total of 3 to 6 carbon atoms. If copolymers are used, they must such comonomer units may be included which increase the water solubility of the component b) do not interfere, i.e. should not have more than 6 carbon atoms.

Examples of suitable polymers are: polyacrylic acids, Polymethacrylic acids, polymaleic acids, 1: 1 copolymers of maleic acid with C1 - to C4-alkyl vinyl ethers, ethylene, acrylic acid or methacrylic acid.

The polymers are in the three-part combination of 0.5 to 10 parts by weight, preferably 1 to 5 parts by weight present.

The component c) is defined by the nonionic Surfactants shown.

These are alkoxylation products of active hydrogen atoms carrying ('! H-active ") organic compounds that have a cloud point, which should be below the wash liquor temperature. Usually a temperature difference is enough to choose from 5 to 100.

Surfactants that meet these requirements are, on the one hand, those that contain a polyethylene oxide residue bound to a longer hydrophobic residue, which in turn is end-capped with a short hydrophobic group. These are, for example, C8 to C22 alkanols, C8 to C12 alkylphenols, or mixtures thereof, primarily octanol, nonanol, decanol, dodecanol, hexadecanol, Stearyl alcohol, C, -C11-oxo alcohol, C13-Cl5 - oxo alcohol, C12-C14 brick alcohol, C16-018 Ziegler alcohol, octyl-, nonyl-, dodecylphenol, all with 2 to 30 mol Ethoxylated ethylene oxide and end-capped with certain groups. Such groups are e.g. one or two propylene oxide groups, butylene oxide groups, Acetal groups (e.g. by reacting the terminal group with vinyl ethers), the Benzyl group, the isopropyl group (propylene end cap) or a short chain Glycerine ether grouping (obtained by reacting the ethoxylate with short-chain Glycidyl ethers).

Other surfactants, which are important for low foam conditions are, for example, block copolymers of ethylene oxide (EO) and propylene oxide (PO), which have the structure (EO) (PO) (EO) where x and z mostly x g numbers of 5 denotes b-is 40 and g denotes above 5 to 40.

There are also adducts of EO and PO with ethylenediamine into consideration, and finally also with the abovementioned alkanols or alkanol mixtures Etherified E0 / P0 block copolymers suitable as component c).

Select the right surfactants for the respective wash temperatures, is an easy task for the expert - he just has to do the appropriate determine the cloud points corresponding to the definition according to the invention.

The alkanol ethoxylates mentioned are preferably used as surfactants c) one made with propylene, propylene oxide, or butylene oxide (1 to 2 moles per ethoxylate) are end-capped, or the abovementioned block copolymers of EO and PO and their ethers with the alkanols mentioned.

The combination can also have small proportions of d) an oil to C4 mono- or dialkylbenzenesulfonate, such as cumene sulfonate as solubilizers, in amounts of up to 10 parts by weight, preferably 2 to 6 parts by weight, and also (e) up to 6, preferably 1 to 3 parts by weight of a glycol or Glycol ethers with up to 6 carbon atoms, such as glycol monobutyl ether, propylene glycol kol, 1,4-butylene glycol or 1,6-hexylene glycol as a detergent booster.

The agents obtained can be put in the dishwasher in an anhydrous form are given and expediently in a concentration of 0.1 to 3 g per liter of washing liquor.

However, they are preferably formulated as aqueous concentrates, with the concentrate contains 10 to 70% by weight, preferably 10 to 40% by weight, of the agents.

The new agents unfold even without solubilizers and cleaning enhancers an optimal cleaning power at almost neutral pH values, despite the proportion storage-stable on the low-foam surfactants and require - this is also remarkable - Despite the low pH value, no addition of anti-corrosive agents, what per se was not to be expected, since it is known that aminopolyearboxylic acids, such as NTA, are so far they are not fully neutralized, have a highly corrosive effect.

The following examples illustrate the invention.

Examples Formulation 1 5 parts of sodium polyacrylate (molecular weight approx. 20,000) 2 parts Na3-NTA 0.6 parts NTA 2 parts C13 / C15 fatty alcohol + 3.5 EO + 2.5 PO) (average) (cloud point 2200) 3 parts cumene sulfonate 2 parts butyl diglycol 85.4 parts of water pH 7.7 Formulation 2 0.5 parts sodium polyacrylate (Molecular weight approx. 6,000) 13 parts Na3-NTA 4 parts NTA 8 parts C13 / Cl5 fatty alcohol + 8 EO + 1.5 BuO (average) (cloud point 300C) 8 parts cumene sulfonate 6 parts Butyl diglycol 60.5 parts water pH = 7.4 These liquid formulations are stable and therefore easy to transport and dose.

For comparison, an alkaline formulation according to DE-OS 27 15 351 (Example 1) tested: 20 parts Na-NTA 1.2 parts fatty alcohol + 5 EO + 13 PO 0.7 parts of nonylphenol + -20 EO (acetalized at the end group) 10 parts of cumene sulfonate 8 parts of triethanolamine 60.1 parts of water pH = 10.7 Our test showed that this liquid formulation already became cloudy at approx. 25 to 300C.

When increasing the surfactant content to a total of 2.5 parts instead of of 1.9 parts, the formulation was only available as a cloudy liquid (too high Alkalinity).

Testing the cleaning effect: 20 parts were used under practical conditions in 3 passes, each time new soiling, with the formulations mentioned washed.

The plates were soiled by adding a potato flour water mixture applied to the plates and left to dry out in the drying cabinet. After each round 3 plates were taken out and with iodine starch indicator for the increase in the starch layer build-up checked. These plates were replaced with 3 new freshly layered plates.

The starch load was therefore the same for every wash cycle.

The starch residues left on the plates were judged after the 3 rounds. In addition, streaking was checked by frozen spinach was added to the wash liquor.

A stronger cleaning effect was achieved with the formulations according to the invention achieved than with those according to the prior art.

The results are shown in the table below.

Table formulation streaking residual strength 1 no streaks 21 2 no stripes 22 according to DE-OS 27 15 351 example 1. slightly streaked 35 Further it turned out that -with the new formulations, even sensitive types of glass, without them becoming cloudy, and dishes with sensitive color burns without loss the paint can be rinsed under maximum load ("BIO" gear).

Claims (3)

Claims 1. Phosphate-free, low-foaming dishwashing detergent, characterized by a content of a) 2.5 to 20 parts by weight of at least one aminopolycarboxylic acid with 1 to 4 nitrogen atoms partially neutralized with alkalis or a mixture of at least one free aminopolycarboxylic acid with 1 to 4 Nitrogen atoms and at least one alkali metal salt of amino polyearboxylic acid, where the ratio of the neutralized to the free carboxyl groups in both Cases 5: 1 to 1: 1, b) 0.5 to 10 parts by weight of water-soluble alkali metal salts a linear, nitrogen-free polymer or copolymer containing carboxyl groups, the monomer units carrying carboxyl groups on two chain carbon atoms contain at least one bonded carboxyl group and a total of 3 to 6 carbon atoms contain. c) 0.5 to 8 parts by weight of at least one by alkoxylation nonionic surfactant obtained from H-active compounds, its cloud point is below the wash liquor temperature, with the proviso that aqueous solutions of the agent have a pH of 5 to 8.5. 2. Means according to claim 1, characterized by an additional Content of (d) up to 10 parts by weight of at least one C1 to C4 mono- or di-alkylbenzenesulfonate and (e) up to 6 parts by weight of at least one glycol or glycol ethers with up to 6 carbon atoms. 3. Containing aqueous concentrate - based on the weight of the concentrate 10 to 70% by weight of agents according to claims 1 or 2.