DE3300243C2 - Dishwashing detergent - Google Patents

Description

The invention relates to a dishwashing detergent aqueous base for automatic dishwashers.

Commercial detergents for common household dishwashers are in powder form and have the disadvantage that they are composed unevenly are relatively expensive to manufacture, cake in moisture and poorly dispersible Form lumps or dust in dry form and create allergies. Liquid dishwashing detergent can be used in automatic dishwashers because of the strong foaming, the extremely low Viscosity and excessively high alkalinity bad use.

The more recent development has been on gel-shaped or concentrated thixotropic mixtures, such as Abrasives and dishwashing detergents in the form of thixotropes Pastes. However, these products are as dishwashing detergents unsuitable because of their too high viscosity, because they hang in the dishwasher dispenser stay and spotty on the dishes and glasses Form deposits. Ideally, thixotropes Cleaning agents must be highly viscous in the idle state or present in the plastic Bingham state and proportionate have high flow values. Under shear stress These products are supposed to shake, for example in the container or when squeezing through an opening  liquefy quickly and if the expended ceases to exist Shear force quickly returned to the highly viscous or plastic state to return to Bingham. Furthermore, the stability of these products is regarding Phase separation or exudation of components of considerable importance when standing for a long time.

The detergents available so far in gel form for automatic dishwashers with those mentioned above Properties result especially in the usual Household dishwashers have trouble. It is for such detergents for automatic dishwashers generally recommended that they use sodium tripolyphosphate (NaTPP) to soften the water or for binding the salts and the water hardness for emulsifying and / or peptizing dirt and also sodium silicate to effect the desired Alkalinity for effective cleaning and protection for the glaze and decor of porcelain, as well as preferably Sodium carbonate to increase alkalinity, furthermore a chlorine donor for better removal of dirt stains or water stains, and ultimately should contain a foam depressant / surfactant to prevent foaming to reduce and thus the effectiveness of support mechanical cleaning process and around ultimately to provide the required cleaning effect; this is for example in "SDA Detergents in Depth, - Formulations Aspects of Machine D shwashing "by Thomas Oberle (1974). Detergents constructed in this way are mostly liquids or powders. The combination of these ingredients in gel form for household dishwashers are likely to have significant Difficulties.

Generally, these Mean the hypochlorite bleach is omitted as it with other chemically active ingredient and in particular  the surfactant reacts and thereby the suspending agent or decomposes the thixotropic agent and its effectiveness impaired and so, for example, discloses the US-PS 41 15 308 thixotropic pastes for dishwashing detergents, which have a suspending agent such as carboxymethyl cellulose, synthetic clays or the like and also inorganic salts such as silicates, phosphates, Polyphosphates and small amount of a surfactant and one Foam trigger included, but from a bleach foresee. From US-PS 41 47 650 is a similar Product known to use hypochlorite as a bleach contains; however, this product lies as a detergent slurry in front.

From US-PS 39 85 668 abrasives are gel-like Consistency known to be a suspending agent and preferably Smectite and attapulgite types of colloid-forming Clays and abrasives such as quartz sand or pearlite and ultimately fillers such as powdered polymers less Contain dense or expanded pearlite show a certain buoyancy and thus the mixture stabilize and also act as fiber while replacing the water that would otherwise be an unwanted one protruding stratification due to exudation or would result in a phase impairment. In addition to these basic ingredients, such abrasives still hypochlorite bleach, bleach-stable Surfactants and buffer substances, silicates, carbonates and Contain monophosphates and builders such as NaTPP, to support the builder effect of the buffer substances. The amount of such builders is less 5 wt .-%, based on the total composition. The The desired pH is set above 10 through the buffer or builder components, whereby the high pH of decomposition of the chlorine bleach  and an undesirable interaction between bleach and counteract surfactant. If necessary NaTPP present is limited to 5% by weight; Foam presser are not included in these products.

From US 41 16 849 compositions for the pretreatment of Kitchenware known as pans, which contain sodium silicate, bleach-resistant surfactants, sodium hypochlorite, clay-like May contain thickeners and sodium hydroxide. Regarding surfactants, which are considered and which are to be avoided, it is said expressly states that the surfactant material has no functionalities like ether bridges, unsaturation, certain aromatic Structures or hydroxyl groups may have an oxidation due to the hypochlorite compounds used can. Particularly suitable for the purposes of this U.S. Patent become alkyl sulfates, water-soluble betaine surfactants and alkyl phosphonates specified. The surfactants selected according to the invention the group of linear and branched alkali mono- and / or -di-C₈- to C₁₄-alkyldiphenyloxide monosulfates or disulfonates are not mentioned.

From GB 15 86 067 are dishwashing detergents for automatic dishwashers known which is a non-ionic surfactant, a bismuth or Salt containing antimony and a pH above 9. These Dishwashing detergents usually contain alkaline builders such as phosphates and silicates and preferably a chlorine bleach. Usually these dishwashing detergents also contain Foam damper in an amount of 0.05 to 3%, being monostearyl phosphate is called.

Although the use of non-ionic surfactants is not should be excluded, as stated on page 2, lines 9/10, it is found at the same time that the non-ionic Surfactant is usually the only surfactant in the composition is and there are only examples using exclusively non-ionic surfactants.  

From US 42 84 524 are alkaline dishwashing detergents known for dishwashers, which are essentially tripolyphosphates, Pyrophosphates, orthophosphates, carbonates and mixtures thereof; Alkali silicate; Chlorine bleach; a little foaming non-ionic Surfactant and water soluble polyacetal carboxylate polymer contain.

About the use of special anionic surfactants, phosphoric acid esters as a foam presser as well as the need for one Certain TI or clay thickener is not said.

The older application DE 31 38 425 discloses the use of a thixotropic cleaner in automatic dishwashers that at least a compound of the group consisting of polyphosphates, aluminosilicates, Silicates, hydroxides and carbonates of sodium or Contains potassium, as well as an active chlorine compound and one with it compatible thickener. As optional components come with low ionic surfactants Foaming power. Anionic surfactants not suggested.

Also phosphoric acid defoamers are not mentioned.

US 41 16 851, a further development of US 41 16 849, discloses thickened compositions containing bleach for treating dirt that is difficult to remove on kitchen ware. These compositions contain a clay thickener, Alkali silicate and to improve Security, dispersibility and cleaning power a water-insoluble Mineral oil with more than 20 carbon atoms, saturated Fatty acid esters, dialkyl ethers and mixtures thereof, and Hypohalite, being one Viscosity of 100 to 1,000,000 cps should be given. Bleach resistant Surfactants can be present, these  Surfactants too no unsaturation, no aromatic structures, none Amide, aldehydic, methyl keto or hydroxyl groups can be oxidized by hypochlorite.

Dishwashing detergents are known from US 38 99 436, which at least a condensed phosphate salt, at least one other Salt as a condensed phosphate salt, at least one citrate and optionally a chlorine-releasing substance and various Contain surfactants. As Surfactants become low-foaming, non-foaming or defoaming Surfactants proposed, being typical such surfactants are non-ionic surfactants.

The object of the invention is to create a new one Dishwashing detergent for automatic dishwashers propose that has thixotropic properties, improved chemical and physical stability shows and that easily and in the washing liquid disperses quickly to clean porcelain, Carry out glass and dishes effectively. In particular a dishwashing detergent is proposed be suitable for household dishwashers and in addition to the thixotropic or gel-like structure contains each of the various ingredients required for effective cleaning in such automatic Dishwashers are required, however Dishwashing detergent is a correspondingly good physical Stability without phase separation even after a long time Standing shows, even with a strongly alkaline setting of the detergent, which is effective for Cleaning power is required; furthermore the new Dishwashing detergent should be designed so that no unwanted Interaction between the chemically active Components occur or these only slightly appear. Furthermore, the new dishwashing detergent have better rheological properties and a higher viscosity with less shear stress and a lower viscosity at higher shear loads possess so that it is advantageous in the dispenser the dishwasher can be used. Ultimately, the new dishwashing detergent is said to be low Foaming behavior, improved cleaning power and faster dispersibility in the dishwasher demonstrate. The object of the invention is also a method to propose to manufacture the dishwashing detergent.

To solve these tasks, a dishwashing detergent according to the main claim and a method for producing the same proposed according to claim 10. Particularly suitable Composition result from subclaims 2 to 9.

The dishwashing detergent according to the invention for automatic Dishwashers have low foaming, are both chemical and physical stable and dissolve quickly in the washing liquid on and are particularly effective at the pH values that result in an improved cleaning effect, namely at pH values in the range from 10.5 to 13.5. The invention Mixtures usually have a gel consistency, d. H. they are very viscous, opaque jelly-like Products with a Bingham plasticity and therefore have relatively high flow values. Accordingly, one is certain shear force required to drain to effect or reinforce as you would in a Dispenser of an operated or switched on automatic dishwasher. Under these conditions the mixture according to the invention becomes fast brought into a fluid state and easily released. If the shear force is interrupted, the fluid mixture returns quickly in their highly viscous state or in the plastic Bingham state and takes hers earlier consistency.

In general, the effectiveness of the invention Dishwashing detergent is available directly depending on the available standing chlorine, the alkalinity, the solubility in the washing medium and the low foaming, it is also essential that the pH of the mixture according to the invention in a range of 10.5 to 13.5 and preferably at least 11.5. The use of NaOH is essential because without NaOH the pH would be below 10.5. With such a  The pH value of the product is too viscous or almost solid and can be found among those prevailing in the dispenser Shear forces no longer easily in one bring fluid state; such a remedy pays then its thixotropic properties. In this Case, the addition of NaOH is essential to the pH to increase and improve the flow properties. The presence of carbonate is usually necessary as it maintains the required buffering substance pH range guaranteed. Excess of carbonate should be avoided, otherwise needle-like Form carbonate crystals, which the stability and the Impair the effectiveness of the product; it serves furthermore, the existing foam presser, namely neutralize the phosphoric acid ester.

Other criteria when choosing to achieve one stable and effective dishwashing detergent with thixotropic Features are the following: The NaTPP should have no heavy metal content, because these contribute to the decomposition of sodium hypochlorite. On average, the NaTPP contains about 5 to 15 wt .-% water corresponding to an average Degree of hydration from 1 to 5. If only the hexahydrate is used, the detergent is liquid and has hardly any thixotropic properties. If only anhydrous NaTPP is used, one gets too thick and therefore unsuitable product. Excellent Dishwashing detergent compositions according to the invention contain, for example, a mixture of anhydrous NaTPP and the corresponding hexahydrate in a weight ratio from 0.5: 1 to 2: 1, with a weight ratio of 1: 1 is particularly preferred. The foam presser is essential to effectiveness to increase the dishwasher and to destabilize  Prevent effects due to excessive Foaming can occur during use. The free In the mixtures according to the invention, chlorine is eliminated by the sodium hypochlorite is provided and not through the otherwise in powdery cleaning agents usual dichloroisocyanurates.

The product according to the invention exhibits improved rheological behavior, in particular with regard to the viscosity as a function of the shear forces. The investigations confirmed that the mixtures according to the invention show a higher viscosity at low shear force and a lower viscosity at higher shear force, that is to say that a more effective conversion into the fluid state and better gelation are made possible at the shear forces which occur in conventional dishwashers . This means in practice that the smooth delivery and handling of the products is better and that at the same time these products cannot undesirably emerge from the delivery device, as is the case with the usual liquid dishwashing detergents. With the shear forces occurring from 3 to 30 rpm. Brookfield viscosities ranging from 15,000 to 30,000 cPs up to about 3000 to 5000 cPs at room temperature are obtained with an LVT Brookfield viscometer after 3 minutes with a # 4 spindle. A shear rate of 7.4 sec. ^-1 corresponds to a spindle revolution per minute of approximately 3. An approximately 10-fold increase in the shear rate results in an approximately 6 to 7-fold reduction in viscosity. In the case of the known gel-type dishwashing detergents, the corresponding reduction in viscosity is only about two times the value. In addition, the starting viscosity of these known mixtures is about 3 rpm. only about 2500 to 2700 cps.

The mixtures according to the invention show a threshold value fluidization at lower shear rates and to a much greater extent of the proportional increase the shear rate versus the proportional reduction the viscosity. This property of the invention Products is identified by the Thixotropy Index (TI) expressed the ratio of the actual viscosity at 3 rpm. to the actual viscosity at 30 rpm. corresponds. The mixtures according to the invention have a TI of about 2.5 to 10 and preferably from 6 to 8. All mixtures according to the invention showed a complete and quick return to their previous ones Hibernation with appropriate consistency when no more shear forces are applied.

In the preparation of the mixtures according to the invention you should first all inorganic salts, namely the Carbonates, silicates and tripolyphosphates in the aqueous Dissolve or disperse the medium and the thickener add as the last component. The foam suppressant Phosphoric acid ester is originally considered to be aqueous Dispersion, just like the thickener, added. The ester dispersion, the sodium hydroxide and the inorganic Salts are first at elevated temperature in aqueous solution and preferably in deionized water prepared with constant stirring and then cooled. Then the bleach, the surfactant and the dispersion of the thickener added to the cooled to about 25 to 35 ° C solution. The amount of water is such that the concentration the active ingredients in the invention Product 35 to 75% by weight and preferably 50 to 65% by weight is.  

The inorganic salts are based on the total weight the mixture used so that about 5 to 35% by weight and preferably 20 to 30% by weight of NaTPP, 2.5 up to 20 wt .-% and preferably 10 to 15 wt .-% sodium silicate with a Na₂O: SiO₂ weight ratio of about 0.3 to 0.5 and up to 9% by weight, preferably 4 up to 7% by weight of alkali carbonate, preferably sodium carbonate available. The total salt concentration is in a range from about 20 to 50 and preferably 35 up to 45% by weight.

The bleach is sodium hypochlorite, one NaOCl solution with 13% available chlorine; the bleach is used in amounts of about 3 to 20 and preferably 7 to 12 wt .-% used.

The sodium hydroxide should be present in such an amount that a pH of 10.5 to about 13.5 and preferably a pH of 11.5 to 12.7 is achieved, which in generally achieved by additions of 0.5 to 3 wt .-% becomes; in any case at least as much sodium hydroxide be used that the phosphoric acid ester, the is present as a foam pusher is neutralized.

The foam pusher is a mono and / or Di-C₁₆ to C₁₈ alkyl esters of phosphoric acid, which in Amounts from 0.1 to 0.5 and preferably 0.15 to 0.3 wt .-% is present, the exact amount of this component partly from the amount of surfactant present depends.

The used in the agents according to the invention Surfactants must be in the presence of hypochlorite bleaches be stable and are anionic products, namely linear or branched alkali mono- and / or -di-C₈- bis C₁₄-Alkyldiphenyloxidmonosulfate or disulfonates. They are in quantities of  about 0.1 to 5, and preferably from 0.3 to 0.8 wt .-% used. Adequate foam squeeze it is expedient to achieve the ratio from surfactant to foam depressant in a range of 10: 1 up to 1: 1 and preferably 1.5: 1 to 4: 1.  

The thickeners or suspending agents are in the general inorganic colloidal clays of the Smectite and / or attpulgite type, the former preferred becomes. These components influence the rheological Properties of the mixtures according to the invention and are used in amounts of about 2.5 to 4% by weight, in any case, the amount should be sufficient for the To convey the desired Bingham plasticity. Smectittone record among other things montmorillonite (bentonite) including the preferred varieties like hectorite, Saponite and the like. These products are under the trade names "Thixogel No. 1" and "Gelwhite GP" expelled and are Montmorillonite. As an attapulgite clay can be found under the trade name "Attagel" such as "Attagel 40 "," Attagel 50 "and" Attagel 150 " be preserved.

Mixtures of smectite and attapulgite in a weight ratio from 4: 1 to 1: 5 are suitable.  

Suspending agents of this type are known and for example described in US Pat. No. 3,985,668.

Other ingredients for the dishwashing detergent according to the invention dyes are appealing to achieve colored products, in particular chlorinated phthalocyanines and polysulfides of aluminosilicates are preferred that give green or blue colors.

The following is intended to illustrate the invention by means of examples are explained in more detail, with all quantities unless otherwise stated refer to the weight.

Example 1

It became a starting dispersion I with a foam pusher made of a 2: 1 mixture of mono- and di- (C₁₆-C₁₈) alkyl esters of phosphoric acid in one Contained 0.16 g in 6 g of water; it was 30 minutes mixed with a disc stirrer at 60 ° C.

There was another dispersion II from a smectite (Gelwhite GP) in an amount of 3 g in 17 g of water prepared, taking 10 minutes at one temperature of 70 ° C was mixed with a Z-blade mixer.

The following ingredients were in a Giusti mixer mixed at 50 to 60 ° C:  

The anhydrous NaTPP contained about 0 to 5 and in usually 3% by weight moisture.

This mixture was brought to 25 with constant stirring cooled to 30 ° C and then at room temperature mixed with the following components:

A sodium monodecyl / didecyl disulfonated was used as the surfactant Diphenyl oxide with 45% active ingredients used. It became an opaque gel-like mixture with about 40% active ingredients that get one TI of about 7 or a viscosity of 28,000 cps at 3 rpm. and 4000 cPs at 30 rpm. In an automatic dishwasher with dispenser showed the mixture according to the invention excellent cleaning behavior; she let herself deliver easily and quickly. The dishwashing detergent according to the invention showed no foam. After long storage  of the product in a closed container no or practically no phase separation was observed. The pH of the detergent was 1% aqueous solution 11.6. Behavior under shear conditions was excellent; after removal of shear forces the product quickly regained consistency of the resting state, which shows that the flow behavior have not been influenced under the given stress was. There was no discernible difference either when delivering the product from a tube with the delivery from the dispenser of a dishwasher.

When the composition of the product changes according to Example 1, which is a total concentration of polyphosphate, Contained about 37% carbonate and silicate, by changing the total concentration of these salts within the specified ranges, were the best Results with a combined salt concentration of at least about 30% by weight, in particular if the concentration of sodium tripolyphosphate is at least was about 20%. Higher silicate concentrations to achieve better protection of the porcelain glaze and the decor lead to a higher alkalinity, which can be compensated for by the fact that the NaOH concentration decreased or the concentration the sodium carbonate acting as a buffer accordingly sets. The composition speaks for changes the NaTPP concentration clearly in the sense that a higher concentration gives more effective products; it also speaks clearly on the degree of hydration at. Require changes in the concentration of surfactants generally a corresponding and direct change the concentration of the foam presser to the desired one maintain low foam area.  

A decrease in pH below 10.5 leads to a noticeable decrease in effectiveness and fluidity.

If, for a mixture according to Example 1 Attapulgitton uses or a 2: 1 Mixture of montmorillonite and attapulgite clay (for example Attagel 50) similar results are obtained. By adding smaller amounts of 0.003 to 0.05% by weight chlorinated phthalocyanine or aluminosilicate paints become appealing green or blue colored mixtures receive. The dyes come with the thickening dispersion II added or the chilled solution on Added end.  

The following experiments were carried out to ensure superiority the dishwashing detergent according to the invention, which as an anionic Surfactants from the group consisting of linear and branched alkali mono- and / or -di-C₈- to C₁₄-alkyldiphenyloxide monosulfates or disulfates (Dowfax 2A1, Example I) included those which, as an anionic surfactant, have a secondary C₁₀- to C₁₄- Contain alkyl sulfonate sodium (Hostapur SAS 60, Example II), to show.

Test report

In the comparative examples, equivalent amounts of the active ingredients of the commercial products Hostapur SAS 60 and Dowfax 2A1.

The compositions of Comparative Examples I and II are as follows specified:

The pH of both compositions was approximately 12.2. Dowfax 2A1 is a mixture of sodium salts of a diphenyloxide disulfonate, that is mono- and disubstituted with a branched C₁₂ alkyl group is:

Dowfax 2A1

Hostapur SAS 60 is the sodium salt of a paraffin sulfonate:

Hostapur SAS 60

The hydrated gel white GP clay was made by put the clay in demineralized water and at room temperature subjected to shear in a homogenizer.

The not very water soluble stearyl phosphate ester was the demineralized water added, which was heated to 65 ° C.  

The other components were used as supplied except of Na₂CO₃ and hydrated tripolyphosphate, which too Powders have been pulverized.

The rheological properties of the above compositions were determined using a Haake Rotovisco viscometer with a rotary cylinder MV III, head 50 with speed reducer (1/10), speed index from 18 to 54. The rheograms of the specific viscosity as a function of time at a specific shear rate are recorded in the two accompanying diagrams 1 and 2 . Although the shear rate was not specified, both the composition containing Dowfax 2A1 (Example I) and the composition containing Hostapur SAS 60 (Example II) were subjected to identical shear conditions. Diagrams 1 and 2 thus allow a direct comparison of the rheological behavior of the two compositions.

Diagram 1 , A shows a rheogram of viscosity versus time of the composition of Example I. In this experiment the composition was subjected to constant shear. According to Rheogram A, the viscosity decreases over time and then reaches a constant minimum value within 3 minutes. Rheograms B, C and D show the recovery (increase) in viscosity after stopping and shear and immobilization of the composition during ½, 1 and 15 minutes, which shows thixotropic behavior.

Chart 2 shows a rheogram of viscosity versus time for Example II. When this composition is subjected to the same shear conditions as described above, up to 6 minutes, the measured viscosity increases somewhat, indicating that there is no thixotropic behavior.

From these experiments it appears that the selected ones above mentioned anionic surfactants of the invention a significant improvement  the thixotropic behavior towards conventional anionic surfactants guarantee.

Claims (10)

1. Water-based dishwashing detergent for automatic dishwashers, characterized by a content of

• (a) 5 to 35 weight percent alkali tripolyphosphate with an average degree of hydration of about 1 to 5;
• (b) 2.5 to 20% by weight sodium silicate;
• (c) 0 to 9% by weight of water-soluble alkali carbonate;
• (d) about 0.1 to 5% by weight of a water-dispersible, bleach-resistant organic surfactant from the group consisting of linear or branched alkali mono- and / or di-C₈ to C₁₄ alkyldiphenyloxide monosulfonates or disulfonates;
• (e) 0.1 to 0.5% by weight of a mono- and / or di-C₁₆ to C₁₈ alkyl ester of phosphoric acid as a foam depressant;
• (f) 3 to 20% by weight of a NaOCl solution with about 13% available chlorine;
• (g) 1.5 to 10% by weight of an inorganic colloidal clay thickener and
• (h) sodium hydroxide to adjust the pH from 10.5 to 13.5,

wherein the amount of the phosphoric acid ester is sufficient to produce one low foaming and the amount of sodium hydroxide at least sufficient to the phosphoric acid ester neutralize, and that the thixotropy index of the detergent is about 2.5 to 10.   2. Dishwashing detergent according to claim 1, characterized in that the weight ratio of surfactant to foam depressant about 10: 1 to 1: 1. 3. Dishwashing detergent according to claim 1, characterized in that that the total concentration of tripolyphosphate, silicate and Carbonate is at least 20 wt .-%. 4. Dishwashing detergent according to claim 3, characterized in that the concentration of tripolyphosphate is about 20 to Is 30% by weight. 5. Dishwashing detergent according to claim 1, characterized in that the tripolyphosphate in a mixture of essentially anhydrous tripolyphosphate and a tripolyphosphate hexahydrate in a weight ratio of about 1: 2 to 2: 1 and preferably 1: 1. 6. Dishwashing detergent according to claim 1, characterized in that there is a dye in sufficient amount for coloring contains. 7. Dishwashing detergent according to claim 1, characterized in that that the thickener is a smectite and / or attapulgite clay is. 8. dishwashing detergent according to claim 1, characterized in that the tripolyphosphate is a sodium tripolyphosphate, the Carbonate is a sodium carbonate and the surfactant is a mixture from mono- and di- (C₈ to C₁₄ alkyl) diphenyloxide disulfonate and that the thickener is bentonite. 9. Dishwashing detergent according to claim 8, characterized in that the pH is 11.5 to 12.7 and the thixotropy Index has a value from 6 to 8.