EP0236900B1 - Powdery chlorine-active mechanical applicable dishcleaning agent - Google Patents

Description

Detergents for automatic dishwashing, especially in households, are known to contain alkali phosphates, alkali silicates as well as small amounts of alkali carbonates and / or alkali sulfates as the main ingredients effective for cleaning. In addition, small amounts of active chlorine-releasing compounds are usually contained, which are specially designed for bleachable soiling, e.g. Tea, coffee or fruit and vegetable juices work. Until now, these most important of all active ingredients can hardly be dispensed with.

• a) nicht- beziehungsweise schwachschäumende nichtionische Tenside, die zur besseren Benetzung der zu reinigenden Oberflächen führen und dadurch einen verbesserten Zutritt der reinigungswirksamen Hauptbestandteile an diese ermöglichen,
• b) schauminhibierende Verbindungen, die in der Lage sind, den durch Speisereste in der Haushaltgeschirrspülmaschine hervorgerufenen Nahrungsmittelschaum zu beseitigen, der die Maschinenmechanik beeinträchtigen und den weiteren Reinigungsmittelzutritt zu den Geschirroberflächen erschweren kann, oder gegebenenfalls auch
• c) reinigungsverstärkende Zusatzstoffe auf Basis von organischen Verbindungen, die gezielt bei der Verwendung moderner Haushaltgeschirrspülmaschinen (HGSM) mit herabgesetzter Temperatur im Reinigungsprogramm Einsatz finden.

However, additions of other active ingredients such as in particular are also desirable

• a) non-foaming or low-foaming nonionic surfactants, which lead to better wetting of the surfaces to be cleaned and thereby enable better access to the cleaning-active main components,
• b) foam-inhibiting compounds which are able to remove the food foam caused by food residues in the domestic dishwasher, which can impair the machine mechanics and can make further cleaning agent access to the dish surfaces difficult, or possibly also
• c) cleaning-enhancing additives based on organic compounds, which are specifically used in the cleaning program when using modern household dishwashers (HGSM) with reduced temperature.

Theoretically, it would be possible to combine all of the active ingredients mentioned under a) to c) in a single dishwashing detergent, but certain selection criteria are necessary from an application point of view because active chlorine-releasing compounds and the active ingredients a) to c) already interact with one another during storage and are not all compatible with one another are. For example, a combination with a), even with its targeted selection of active chlorine, again and again both to an increased reduction in the active chlorine content and to a decomposition of the surfactant. This becomes noticeable with increasing storage time, among other things through increased foaming when using the dishwashing detergent. Although this increased foam formation does not necessarily lead to the detergent being unusable, the foam in the cleaning liquor considerably delays the ability of the detergent to be rinsed out of the dosing device of the HGSM, which leads to a loss in performance of the detergent. Especially on machines with a low fleet level, air can be drawn in by the cleaner circulation pump through increased foaming, which causes the pump pressure to drop and the cleaning performance to be reduced. The combination with b) also leads to an increased degradation of active chlorine with a simultaneous loss of the foam-inhibiting action, the added benefit of the foam-inhibiting compounds being almost canceled out by the presence of compounds which release active chlorine. Finally, the combination with c) leads to mutual influence and cancellation of the individual effects. This has repeatedly led to the search for a solution to this problem. The most varied of paths have been followed and described.

The object of the invention was therefore to demonstrate a new way which makes it possible to stabilize at least the additional active substances mentioned with respect to the compounds which release active chlorine. From German Auslegeschrift 16 17 088 it is known that the addition of white paraffin oil to dry mixtures of alkali phosphates and silicates, nonionic surfactants and active chlorine carriers improves the storage stability of the cleaning agents, which is achieved in particular by good, i.e. low foam values are documented.

According to the teaching of European patent 54094 a corresponding result is characterized .zielt ER- that the active chlorine carrier in granular form, is coated with a thin hydrophobic layer of a diester of phthalic acid or adipic acid with a C ₄ - _is -Aikano), is used.

Surprisingly, it has now been found that the addition of small amounts of certain polysaccharides to the powdery constituents of active chlorine-containing dishwashing detergents brings about an unexpectedly good protective function for active chlorine-unstable compounds.

The invention therefore relates to powdery, active chlorine-containing, zeolite-free, machine-applicable dishwashing detergents based on alkali metal triphosphates, alkali metal silicates and / or alkali metal carbonates and / or alkali metal sulfates, low-foaming nonionic surfactants and optionally other active chlorine-sensitive compounds, which are characterized in that they contain an addition of 0.005 to 0 , 5, preferably 0.01 to 0.15 percent by weight, based on the total cleaning agent, of polysaccharides.

As polysaccharides, those with molecular weights of 100,000 to 10,000,000, such as alginates and preferably xanthan gum, can be used. The amount added is thus at the lower limit or far below the amounts which are customarily used in the known addition of these substances as thickeners for liquid or liquefied active chlorine-free cleaning agents (for example US Pat. No. 4,260,528, US Pat. No. 4,226,736, WO 83 / 3621, DE-OS 33 01 577). The addition is made by dry mixing the powdered detergent components together in known devices.

"Xanthan gum" is based on Römpps Chemie-Lexikon, 7th edition (1973), pages 1355 and 1356 and Kirk-Othmer "Encyclopedia of Chemical Technology", 3rd edition (1980), volume 12, pages 62 to 64 understood a product that is known under the Anglo-Saxon name "Xanthan Gum".

Xanthan gum is a high molecular weight polysaccharide, i.e. an exocellular heteropolysaccharide with a molecular weight of about 2,000,000 to 10,000,000 and higher, which is produced by various types of Xanthomonas, for example Xanthomonas campestris. They are hydrophilic colloids. Numerous publications deal with their production by aerobic propagation and cultivation of bacteria of the genus Xanthomonas in aqueous nutrient media. The basic work is described in U.S. Patent 3,000,790.

Such products are commercially available and are for example from Kelco Comp. Oklahoma / USA sold under the name Kelzan ^@ and described in Kelco "Xanthan Gum", 2nd edition (1975).

Alginates, preferably the sodium salts of alginic acid with molecular weights of about 100,000 to 240,000, are also used, among others. by Kelco Comp. sold under the name Kelco-gel @.

The protection of the organic additives from the attack of active chlorine compounds in alkaline cleaning agents is all the more surprising since it is known for Kelzan ₀ that the polysaccharide is very well tolerated with nonionic surfactants, but is degraded by compounds with a strong oxidizing effect such as per compounds or hypochlorites.

The alkali metal salts of pentaalkali metal tri-phosphate, in particular pentasodium triphosphate, are used anhydrous or as hexahydrate and any mixtures of the two forms in amounts of 5 to 60, preferably 10 to 55, percent by weight, based on the total mixture of the cleaning agent, as alkali metal triphosphates. The alkali metal silicates, the use of which is necessary in order to impart to the cleaning agents the alkaline pH of 11 to 14 necessary for the cleaning action and also to suppress the corrosion action of the triphosphates, are usually described as Na ₂ 0: Si0 ₂ = 1: 1 compounds , used both as anhydrous sodium metasilicate and hydrate water. Their proportion in the total mixture of the cleaning agent is 10 to 60, preferably 15 to 50 percent by weight, based on the anhydrous compounds.

Small amounts of alkali carbonates are usually added as additional alkali donors. The amount used is 0 to 15, preferably 1 to 10 percent by weight. Here too, the sodium salt is preferably used.

In order to stretch the formulation, small amounts of inorganic salts such as alkali metal sulfates, preferably sodium sulfate, which are inactive for cleaning can also be added. The amounts are then from 0 to 15, preferably from 1 to 10, percent by weight.

DE-OS 3 408 040 discloses storage-stable, free-flowing, aqueous zeolite suspensions which, in order to optimize their storage and transport stability as stabilizers, contain an addition of 0.01 to 0.25 percent by weight, based on the total aqueous zeolite suspension to be stabilized , containing xanthan gum. These suspensions can be incorporated into detergent formulations. Even though these amounts of xanthan gum are within the scope of the amounts used here according to the invention, it was not possible to derive the teaching from this prior art that xanthan gum additions to powdery zeolite-free active chlorine-containing detergent compositions are suitable for protecting organic compounds from the attack of active chlorine.

The active chlorine-releasing compounds include the chlorine derivatives of isocyanuric acid, preferably trichloroisocyanuric acid and sodium dichloroisocyanurate and its dihydrate. The amounts added are 0.2 to 5, preferably 0.2 to 2.5 percent by weight.

Known low-foaming nonionic surfactants a) suitable for the preparation of the cleaning agents according to the invention are addition products of ethylene oxide with alkylphenols and preferably fatty alcohols based on coconut oil or tallow fat, i.e. with an alkyl chain length of 12 to 18 carbon atoms and their analog, petrochemically obtained compounds which have preferably been reacted with ethylene oxide and optionally also with propylene oxide. They are used in amounts of 0.2 to 3, preferably from 0.2 to 2.0 percent by weight.

Possible foam-inhibiting compounds b) to be added are the paraffin-containing defoaming compositions mentioned in German Offenlegungsschrift 34 00 003. These are physical mixtures of pyrogenic hydrophobicized silica and paraffin waxes which are solid at room temperature or paraffin wax mixtures as a dispersion in liquid or as a composition on solid support materials. Their concentration is 0 to 5, preferably 0.05 to 5 and in particular 0.5 to 5 percent by weight.

Suitable cleaning-enhancing additives c), which can optionally also be added, are the compounds mentioned in German Offenlegungsschriften 34 28 833, 34 28 834 and 34 28 848 of the type of the terminal or internal epoxyalkanes which are reacted with mono- or diethanolamine and where appropriate, have also been ethoxylated or propoxylated, of the primary, straight-chain or branched-chain Cs-Cio-alkanols, which may or may not be propoxylated, or primary C _B -C _1B -alkylamines, which may optionally be alkoxylated or quaternized. Their amount then amounts to 0.1 to 10, preferably 0.2 to 5 percent by weight.

All weight data relate to 100% total weight of the cleaning agents according to the invention.

Examples

• 38 Gew.-% Pentanatriumtriphosphat, wasserfrei
• 45 Gew.-% Natriummetasilikat, wasserfrei
• 7 Gew.-% Natriumcarbonat, wasserfrei
• Rest Wasser

The following recipe was used as a basic recipe for all examples:

• 38% by weight pentasodium triphosphate, anhydrous
• 45% by weight sodium metasilicate, anhydrous
• 7% by weight sodium carbonate, anhydrous
• Rest of water

The raw materials were mixed together with water in a Lödige mixer until a homogeneous agglomerate was formed, which was then dried in an air stream of 80 _° C. to the stated water and residual moisture content. In principle, this recipe can also be mixed with granular, possibly water-containing raw materials.

The liquid components were sprayed onto this basic formulation in a known manner. The powdery polysaccharide was added before the powdery or granulated active chlorine carrier was added.

example 1

In order to test the active chlorine stability of a formulation containing xanthan gum compared to a formulation free of it, the following cleaning agent mixtures were stored:

Recipe a

• 99% by weight basic recipe
• 1% by weight of trichloroisocyanuric acid

Recipe b

• 98.9% by weight basic recipe
• 1% by weight of trichloroisocyanuric acid
• 0.1 wt .-% xanthan gum Kelzan ^®

The storage took place under different climatic conditions: 40 ° C in the drying cabinet, in the climate cabinet at 40 ° C / 80% relative humidity and in the laboratory climate, ie at 65% humidity and 22 _° C. The active chlorine contents were determined iodometrically. The following active chlorine losses were determined after 24 weeks of storage:

The example shows that active chlorine losses tend to be obtained for the polysaccharide-containing formulation b) as for the free variant a). Due to the sensitivity of Kelzan ° to oxidation, these known losses were somewhat increased.

Example 2

This example shows in the foaming behavior of the detergent formulations that if an active chlorine carrier and a nonionic surfactant are present at the same time, the latter is significantly less destroyed in the presence of a polysaccharide.

The following cleaning agent formulations were mixed according to the above scheme:

Recipe a

• 99% by weight basic recipe
• 1 wt .-% reaction product of 1 mol C ₁₂ - ₁ s fatty alcohol with 5 Moi ethylene oxide

Recipe b

• 98% by weight basic recipe
• 1% by weight surfactant (as recipe a)
• 1% by weight of trichloroisocyanuric acid

Recipe c

• 97.9% by weight basic recipe
• 1% by weight surfactant (as recipe a)
• 1% by weight of trichloroisocyanuric acid
• 0.1% by weight of Kelzan xanthan gum

These detergent compositions were also stored under the various climatic conditions specified in Example 1. During the storage of the cleaning agents, the surfactant reacted with the active chlorine carrier, which was evident from the fact that the reaction products or their intermediates led to relatively strong foaming of the agent. However, this is very undesirable in machine cleaning because it results in a pressure drop at the detergent circulation pump, which is synonymous with a reduced mechanical effect of the machine.

During the storage of the cleaning agents, their foaming behavior and their active chlorine content were checked at certain intervals. A Miele HGSM was used for this. The results are shown in Tables 2 and 3 below.

The values for the foam behavior given in Table 2 are relative values, based on the pressure behavior of the HGSM with active chlorine-free cleaner 2 b (= 100%). In terms of foaming behavior, the xanthan gum-containing cleaning agent behaved significantly more favorably than the xanthan gum-free one. In some cases, the values were almost as favorable as for the active chlorine-free formulation 2 a.

The values in Table 3 clearly show that no increased active chlorine loss was again obtained for the xanthan gum-containing formulation.

Example 3

To demonstrate that the reduction of foam formation · by a polysaccharide is not tensidspezifisch, the tests were expanded to include other cleaning agents usual surfactants, namely the reaction product of 1 mole of C _12-18 alcohol with 2 moles ethylene oxide and 4 moles propylene oxide and 1 mole of Nonylphenol with 3 moles of ethylene oxide.

These two surfactants are known to tend to produce a lot of foam in the presence of commercially available HGSM cleaning agents in the presence of active chlorine compounds. According to recipe variant 2 c, both surfactants were incorporated into a recipe containing xanthan gum.

Recipe a

• 97.9% by weight basic recipe
• 1% by weight of nonylphenol ethoxylate
• 1% by weight of trichloroisocyanuric acid
• 0.1% by weight xanthan gum

Recipe b

• 97.9% by weight basic recipe
• 1 wt .-% C _12-18 alcohol-ethoxy-propoxylate
• 1% by weight of trichloroisocyanuric acid
• 0.1% by weight xanthan gum

After 24 weeks of storage, the pressure drop at the cleaner pump was measured when a cleaning program was run. The values for the foam behavior given again in Table 4 below are relative values, based on the pressure behavior of the HGSM without the use of cleaning agents (maximum pressure).

The results in Table 4 show the same finding as in Example 2: xanthan gum has a surfactant-stabilizing effect.

Example 4:

• Na-dichlorisocyanurat-Dihydrat
• Trichlorisocyanursäure

In previous experiments, trichloroisocyanuric acid was used as the active chlorine carrier. This example is intended to show that when other chlorine carriers are used, the surfactant is also stabilized with comparable chlorine stability. The following were used as chlorine carriers: Na dichloroisocyanurate

• Na dichloroisocyanurate dihydrate
• Trichloroisocyanuric acid

The following recipes were produced with these chlorine carriers, all of which had the same active chlorine content:

Recipe a

• 97.6% basic recipe
• 1% surfactant (in all examples like recipe 2a)
• 1.4% Na dichloroisocyanurate

Recipe b

• 97.5% basic recipe
• 1% surfactant
• 1.4% sodium dichloroisocyanurate
• 0.1% xanthan gum

Recipe c

• 97.4% basic recipe
• 1% surfactant
• 1.6% Na dichloroisocyanurate dihydrate

Recipe d

• 97.3% basic recipe
• 1% surfactant
• 1.6% Na dichloroisocyanurate dihydrate
• 0.1% xanthan gum

Recipe e

• 98.0% basic recipe
• 1% surfactant
• 1% trichloroisocyanuric acid

Recipe

• 97.9% basic formulation
• 1% surfactant
• 1% trichloroisocyanuric acid
• 0.1% xanthan gum

The cleaning agents were stored in the drying cabinet at 40 _° C and in the climate cabinet at 40 _° C and 80% RH for 24 weeks. The active chlorine content was checked after storage. The results are summarized in Table 5 below.

For these active chlorine carriers, too, no increased active chlorine loss was found in the xanthan gum-containing variants.

In addition, the foam behavior was checked in the HGSM after storage. The results are summarized in Table 6 below.

In a direct pair comparison, with otherwise the same composition, more favorable foaming behavior was observed for the xanthan gum-containing (Kelzan ^@ ) formulations.

Example 5

This example shows that a polysaccharide can also stabilize other cleaning agent components that are normally attacked by the active chlorine carrier. The following recipe variants were produced and stored under different climatic conditions:

Recipe a

• 98% basic recipe
• 1% trichloroisocyanuric acid
• 1% defoamer

Recipe b

• 97.9% basic formulation
• 1% trichloroisocyanuric acid
• 1% defoamer
• 0.1% xanthan gum

The defoamer was liquid and consisted of 95.0 parts by weight of 2-n-octyldecanol, 0.5 part by weight of petroleum jelly, 1.7 parts by weight of paraffin wax with a setting point of 42 to 44 _° C, 2.2 parts by weight of a microcrystalline wax with a setting point of 85 to 86 ° C and 0.6 part by weight of hydrophobicized silica, as described in DE-OS 34 00 003.

To check the effectiveness of the defoamer, 30 g whole egg was added to the cleaning agent solution in the HGSM cleaning cycle; As a result, a stable foam was generated in the machine when the detergent fleet was circulated. This foam was so stable that after a short circulation time it had built up so strongly that the machine over-foamed.

• a) die bereits beschriebene Messung des Pumpendruckes;
• b) kurzes Öffnen der HGSM und visuelle Beobachtung des Schaumzerfalls: Instabile Schäume zerfallen wenige Sekunden nach Beendigung der Umwälzung. Stabile Schäume können bis in den Minutenbereich hinein existent bleiben.

The addition of the defoamer did not prevent the formation of foam, but the foam was so destabilized (unstable) that a certain foam volume was not exceeded during the entire cleaning cycle. The stability of this food foam could be measured using two methods:

• a) the measurement of the pump pressure already described;
• b) briefly opening the HGSM and visually observing the foam disintegration: unstable foams disintegrate a few seconds after the circulation has ended. Stable foams can remain in the minute range.

The results are summarized in Table 7 below.

From Table 7 it can be seen that with the xanthan gum-containing formulation, the destabilizing effect of food foam was fully retained during a storage period of 24 weeks, while significant losses in performance were observed with the xanthan gum-free formulation.

An increased loss of active chlorine was not found.

Claims (5)

1. Powder-form, zeolite-free, active-chlorine-containing detergent for dishwashing machines based on alkali triphosphates, alkali metasilicates and/or alkali carbonates and/or alkali sulfates, low-foaming nonionic surfactants and, optionally, other compounds sensitive to active chlorine, characterized in that they contain an addition of 0.005 to 0.5% by weight and preferably 0.01 to 0.2% by weight, based on the detergent as a whole, of polysaccharides.

2. Detergents as claimed in claim 1, characterized in that they contain xanthan gum as the polysaccharide.

3. Detergents as claimed in claims 1 and 2, characterized in that they additionally contain 0 to 5% by weight, preferably 0.05 to 5% by weight and more preferably 0.5 to 5% by weight of foam-inhibiting compounds.

4. Detergents as claimed in claims 1 to 3, characterized in that they contain paraffin-containing compositions as the foam-inhibiting compound.

5. Detergents as claimed in claims 1 to 4, characterized in that they additionally contain 0.1 to 10% by weight and preferably 0.2 to 5% by weight of detergency-boosting compounds.