FI85599C - Detergent for automatic dishwashers - Google Patents

Description

1 85599

Detergent for automatic dishwasher

One aspect of this invention relates to an aqueous thixotropic automatic dishwasher detergent comprising a liquid phase comprising water containing dissolved tripolyphosphate, silicate and alkali metal ions and dispersed non-swellable clay as a thickener (preferably attapulgite) is mainly sodium tripolyphosphate.

The mixture preferably also contains a chlorine bleach (preferably dissolved sodium hypochlorite) and a bleach-resistant anionic surface tension reducing agent. It preferably also contains alkali metal carbonate.

It has now been found that considerably improved results are obtained by adding a limited amount of a water-soluble potassium compound, for example a potassium salt (or KOH), to the mixture so that the weight ratio of K: Na is between about 0.04 and 0.5, preferably about 0.07- 0.4, such as about 0.08 or about 0.15. The product thus obtained is much more stable, so that it has less tendency to adversely thicken or separate as the mixture ages, for example at about 38 ° C. Also, replacing a portion of the sodium salt with the same amount of the corresponding potassium salt results in a significant reduction in viscosity (e.g., as measured by a Brookfield HATD viscometer at 25 ° C, 20 rpm, using rotation # 4), better stability against separation (e.g. at room temperature) and prevents the formation of relatively large crystals during storage. The reduction in viscosity makes the manufacturing equipment easier to handle, easier to dispense and easier for the user to break the thixotropic structure of the product (by shaking the container in which it is packed) so that it can be freely poured into the detergent container or tank of a household automatic dishwasher. .

____: In the present invention, the ranges of the proportions of the substances in the weight percentages of 2,85599, e.g. by weight, are approximately as follows: a) 8-35% alkali metal tripolyphosphate, b) 2.5-20% sodium silicate, c) 0-9% alkali metal carbonate, d) 0.1-5 % chlorine bleach-resistant, water-dispersible organic active detergent, e) 0-5% chlorine bleach-resistant antifoam, f) chlorine bleach compound in an amount such that the amount of active chlorine becomes about 0.2-4%, and g) a sufficient amount of thixotropic thickener, so that the thixotropic index of the mixture becomes about 2.5-10.

The essential features of the invention are set out in the appended claims.

The compositions shown preferably have a sodium tripolyphosphate content of greater than 15% (preferably between about 20-25 or 30%), a sodium silicate content of at least about 4% (such as between about 5-10 or 15%), an alkali metal carbonate content of about 2-6, or 7%, the proportion of chlorine bleach is such that the proportion of active chlorine becomes more than 0.5% (e.g. about 1-2% of active chlorine), the proportion of active detergent is between 0.1-0.5%. Calculated as SiO 2, the preferred proportion of sodium silicate is about 3.5-7% SiO 2.

The proportion of water in the mixtures (measured with a "Cenco moisture analyzer" in which the sample is heated by means of an infrared lamp until it reaches a constant weight) is preferably between about 40-50%, more preferably about 43-48%, such as about 44 or 46%.

. The compositions disclosed herein generally have pH values above 11 or 12. In the preferred type of recipe, the pH of the composition is, after dilution with water to a concentration of 0.75%, between about 10.7-11.3.

The compositions disclosed herein are preferably adjusted for viscosity such that viscosities (measured on a Brookfield HATD viscometer at 25 ° C, 20 rpm with rotator # 4) are less than about 8,000 centipoise, and more preferably between about 3,85599 sem. 2000 or 3000-7000 centipoise, such as about 4000-6000 centipoise. Viscosity and other properties can be measured several days (e.g., one week) after the mixture is prepared; a good practice is to shake the sample before measuring its viscosity and first allow the viscometer to rotate for about 90 s before taking the reading.

The compositions described herein have yield values well above 200 dynes per cm and are preferably formulated to have flow values below 1100 2 dynes / cm and above 300 dynes / cm, more preferably below about 900 2 dynes / cm, such as about 400-600 dynes / cm. The fluidity value indicates the shear rate at which the thixotropic structure breaks. It is measured with a Haake RV 12 or RV 100 rotary viscometer using MVIP rotation at 25 ° C at a shear rate that rises linearly from zero to 20 seconds in 5 minutes (5 min after a rest period). ^ · The Haake viscometer cuts a thin layer of material between the rotating cylinder and the surrounding tank. between the adjacent cylindrical wall. Figures 1-3 are graphical representations obtained by testing the materials of the three examples indicated in the figures in this manner, and peaks Y show fluidity values.

* ··: Another factor measured by the said Haake viscometer is the value to which the thixotropic structure of the mixture returns. In one measurement technique, after 5 min of the above step: V cutting speed is increased, rotation is decelerated to zero during 5: min, then after 30 s resting phase, rotation is accelerated again and cutting speed is linearly increased within 5 min from zero to 20 seconds. This gives ____: second fluidity value, i.e. peaks Y 2 in Figure 1. This second ... (recovered) fluidity value is preferably at least 200 dynes / * * · 2 cm, for example 50%, 75% or more of the initially calculated fluidity value.

Figure 4 is a photomicrograph (on the scale shown in the figure) of the mixture of Example 4.

4,85599

The following examples are provided to further illustrate the invention.

These examples include Attagel § 50 ground attapulgite clay (supplied by Engelhard Minerals & Chemicals, whose commercial brochures state that it contains about 12% by weight free moisture, measured by heating to 104 ° C, and has a BET surface area of about 210 m2 / g calculated on a moisture-free product); Graphtol Green is a dye; LPKN 158 is an antifoam agent manufactured by American Holchst (Knapsack) containing a 2: 1 mixture of mono- and di- (C 1 -C 4) alkyl esters of phosphoric acid, sodium silicate having a ratio of Na 2 O: SiO 2 = 1: 2, 4; Dowfax 3B2 is a 45% aqueous solution of Na-monodecyl / didecyl diphenyloxide disulfonates, a bleach-resistant anionic surfactant; STPP is sodium tripolyphosphate. Unless otherwise indicated, STPP is added in the form of a finely divided commercial anhydrous substance having a water content of about 0.5%, such substance typically containing about 4.5-6.5% of the substance in the form of a pyrophosphate. The water used is deionized water unless otherwise stated.

Example 1

The following ingredients are added to the vessel in the order given in the list and mixed with a conventional propeller-type laboratory mixer. The temperatures and mixing times at the various stages are also given below: Λ »*» • · • a · «· 5 85599

Weight Temperature

(q) (bO

10% Graphtol green (color) 5 54 ° C water 1746 molten LPKN 158 (antifoam) 8

Dowfax 3B2 (surface tension reducing agent) 40 52 (2 min)

Mixture of Attagel # 50 and TiO2 white dye in a ratio of 9: 1,180 50 (1 min) 49 (3 min)

Soda ash 275 K2CO3 75 57 (1 min) 56 (3 min)

Finely ground STPP hexahydrate 750 53 (1 min) 52 (3 min) 51 (5 min) 47.5% aqueous solution of sodium silicate 421 premixed with 50% aqueous NaOH 150 48 (3 min) 13% aqueous NaOCl 500; 42 (3 min) TI Finely ground STPP hexahydrate 750 42 (1 min)

A total of 5,000 41.5 (5 min)

The viscosity of the mixture, measured as indicated above, is about 5,000 centipoise after aging the mixture for 3 weeks at 38 ° C and about 4800 centipoise after aging for 3 months at 38 ° C.

In this example, the particle size distribution of STPP hexahydrate is approximately as follows: 6 85599 U.S.S. sieve on # 10 0 on # 40 0 on # 100 25.4 on # 200 31.5 on # 325 16.5 passes # 325 25.9

Example 2

Mixtures according to the following recipes were prepared and their properties were measured as follows:

The ingredients are mixed in the following order: water, paint, clay, half phosphate, antifoam, hypochlorite, sodium carbonate, potassium carbonate, NaOH, silicate, one half phosphate, surface tension reducing agent.

Ingredients Contributions a b c d

Savi (attagel 50) 3,285 3,285 3,285 3,285 3,285 STPP 23.0 23.0 17.01 16.5 23.0

Potassium tripolyphosphate - - - 6.5

Potassium pyrophosphate - - 5.99 - 0

Sodium carbonate 5.0 to 5.0 5.0 2.5

Potassium carbonate - 5.0 - - 2.5

Sodium hypochlorite V rite (12%) 9,375 9,375 9,375 9,375 9,375

Sodium hydroxide (50%) 2.05 2.05 2.05 2.05 2.05

Sodium silicate (47.5%) 10.53 10.53 10.53 10.53 10.53 ·: | Surface tension reducing agent (Dowfax 3B-2) 0.80 0.80 0.80 0.80 0.80

Foaming condition: Knapsack Lp Kn 0.16 0.16 0.16 0.16 0.16: T: Color 0.381 0.381 0.381 0.381 0.381

Water Remaining 7 85599

Properties Capillary emptying time (min) 8.2 12.1 10.9 11.4 11.2

Viscosity (cP) at 38 ° C with aging 1 week 9080 3100 2900 5120 5400 2 weeks 9200 3480 2820 6340 5240 3 weeks 9300 3600 3040 6700 6560

Capillary emptying time is a conventional test in which a 6.8 cm diameter circle is drawn on a 15 cm diameter Whatman plate, filter paper size 41, a plastic ring (3.5 cm inside diameter, 4.2 cm outside diameter, 6.0 cm high) is placed vertically, from a concentric circle with filter paper and the ring is filled with the mixture to be tested. The liquid in the mixture is then absorbed into the filter paper and slowly spreads into the drawn circle. The time taken for the liquid to touch the circle is measured at three predetermined points and the average value is calculated.

Example 3

Mixtures according to the following recipes were prepared by mixing the ingredients in the order indicated. The mixtures are then centrifuged at 275 G until no more (continuous) increase in the volume of the clear, separated liquid phase occurs, and the resulting liquid is analyzed:

Deionized water 27,106> Color 0,016>; Sodium carbonate 6 420

Potassium carbonate 0 246 STPP 21,106>

Deionized water 14,184>

Attagel # 50 4.00> T-jO 0.444>::: 50% NaOH solution 2.5>, *. 47.5% sodium silicate solution 13.68 4> 'I Anti-foaming agent 0.16> 13% NaOCl solution 10.0> 45% surface tension reducing agent solution 0.8 ->:: 100 , 00 s 85599

The mixtures are thus identical except for their K: Na ratios.

Product properties a b c d Viscosity after 1 day at room temperature 8320 5520 4200 2120 After 3 weeks at room temperature 8550 6200 4500 2420 after aging for 7 weeks at 38 ° C 9400 8000 5600 3400 Specific gravity 1.37 1.37 1.40 1.39

Properties of the liquid obtained by centrifugation

Viscosity at 25 ° C relative to water 1 cP 4.4 4.4 4.8 6.3% soluble silicate (calculated at a molar ratio

Na 2 O: SiO 2 = 1,2.4) 7.5 7.3 7.3 7.1% carbonate (calculated

As Na 2 CO 2) 8.8 8.5 7.4 6.6% phosphate (calculated

Na 5 P 3 O 10) 1.7 2.5 3.1 6, L

Specific Gravity 1.257 1.262 1.276 1.30 The viscosities of the material in this example have been measured with a Brookfield RVT viscometer, rotator # 5, at 26.7 ° C.

Examples 4-6 below illustrate a new and useful method for preparing the products described above (containing limited amounts of potassium).

The method can also be used for the preparation of other products of the type described above (for example, those which do not contain a potassium compound), as well as other detergent suspensions containing very small particles. water-soluble inorganic builder salts dispersed in water containing dissolved builder salt, clay or other colloidal thickener and a surface tension reducing agent. In Examples 4-6 (where the particles of the 9,85599 builder salt of the product are largely STPP hexahydrate plus sodium carbonate hydrate), a mixture of a highly viscous (viscosity, e.g., 20,000-60,000 cP) with a limited amount of water, a strongly alkaline impregnated builder salt is formed. and insoluble water-soluble enhancer salt particles as the main component. This viscous mixture is placed in a top-speed dispersing device in which insoluble particles are ground, followed by the addition of solid particles of thickening clay and the mechanical removal of clay agglomerates; the remainder of the recipe ingredients (e.g., other liquids or substances that are readily soluble or dispersible in the liquid phase containing the high electrolyte content can then be mixed in. The mixture can then be re-treated by mechanical shear to remove clay agglomerates. this method eliminates the need to pre-disperse the clay in an aqueous medium.

The solid particles of the clay are easily dispersed, although the medium is very strongly alkaline. The grinding of the particles of insoluble builder salts takes place much more efficiently and faster in the substantial absence of clay.

In the process described in Examples 4-6, a builder salt is added which forms the majority of the insoluble particles, preferably in an aqueous solution already containing such a high concentration of other dissolved builder salt that this addition causes the builder salt to be expelled from solution V (e.g. by ordinary ionic action). again as very small crystals.

Another important feature of the mixing method shown in Examples 4-6 is that it makes it possible to remanufacture batches with reproducible properties using "the rest" of the batch prepared above as an ingredient in each successive batch.

As previously reported, not the examples shown in Examples 4-6 ’; the use of this method is not limited to the preparation of mixtures containing potassium salts ίο 8 5 599. Although its greatest utility has hitherto been found in the preparation of mixtures in which the clay is attapulgite, it can also be used in mixtures in which all or even part of the clay is of the swellable type, for example a smectic clay type such as bentonite (e.g. Gelwhite GP) or hectorite.

Example 4 32.0 parts of deionized water mixed with a small amount of dye (i.e. 0.028 parts of Graphtol green, aqueous paste containing 28% of dye) is completely dissolved in 2.0 parts of K 2 CO 3 (having a solubility in water of more than 100 parts per 100 parts of water up to At 0 ° C, and 5.0 parts of granular sodium carbonate (having a solubility in water of about 45 parts per 100 parts at 35 ° C.) The temperature of the solution is about 32 ° C. 23.116 parts of powdered STPP containing about 0.5% water of hydration, and at the same time the mixture is dispersed at a very high speed, the amount of STPP is much higher than the amount soluble in the amount of water present, its solubility in water is about 20 g per 100 ml at 25 ° C. In this example, there is a product from STPP Olin Corp. with a phase I content of about 50%, a sodium sulfate content of about 2% and a very fine particle size; it is a powdery anhydrous, known as: "wet process mixture of STPP and powdered STPP hexahydrate. When STPP is added to the solution, it hydrates rapidly to form hard crystalline clumps which are STPP hexahydrate. (Note that 23 parts of STPP are able to absorb about 7 parts of water when forming the hexahydrate). The mixture is first a thin suspension of insoluble STPP in a liquid that is a supersaturated solution.

The temperature rises due to the hydration reaction, reaching a peak of 60 ° C. After about 3-4 minutes, the mixture becomes very much viscous; its viscosity rises above 20,000 cP (such as about 40,000 to 50,000 cP measured at the suspension temperature, e.g., with a Brookfield RVT, at rotator # 6, 10 rpm). During the process, it is believed that sodium carbonate crystallizes (in the form of very fine crystals) from the solution phase due to the usual ionic action (sodium of STPP).

i, 11 85599

Once the mixture has become viscous, the high speed disperser grinds the particles (e.g. TPP hydrate) to a very small particle size and the grinding effect is firstly seen by the increased energy consumption of the disperser and the further rise in temperature (e.g. 66 ° C fine when cooled). This grinding is continued for about 5 minutes after thickening at the beginning of the suspension; during grinding, the visible clumps disappear from the substance and the particle size of the insoluble particles decreases so that practically all the particles are believed to have a diameter of less than 40 μm. An additional 9,367 parts of water is then added, reducing the viscosity to less than 10,000 cP (e.g., close to 5,000 cP, as measured above), followed by the addition of 3.3 parts of Attagel # 50 and 0.732 parts of white TiCl 2 (anatase) dye. solution (having a pH well above 9, e.g. 10.5) while dispersing the mixture at high speed with a device that disperses the clay (removes agglomerates) very efficiently so that the thick mixture becomes homogeneous and uniform in appearance. Then 2.70 parts of a 50% aqueous NaOH solution, 0.16 parts of an antifoam agent (Knapsack LPKN 158), 10.53 parts of a 47.5% aqueous sodium silicate solution (with a Na 2 O: SiO 2 ratio of 1: 1) are added. 2.4), 10.0 parts of a 12% aqueous solution of sodium hypochlorite and 0.8 parts of a 45% bleach-resistant anionic surfactant (Dowfax 3B2); these additions can be made under any desired mixing conditions, for example by simple mixing (although it may be advantageous for Y to continue high speed shear dispersion for this mixing). The mixture is then subjected to grinding, such as by passing it through an in-line grinder such as the Tekmar "Dispax Reactor" (operating at a top speed of 22 m per s), where the mixture is subjected to very fast cutting for a relatively short time ("residence time" -sa may be only two seconds or less). The main effect of this is to further decompose the agglomerates of the clay particles, which is reflected in a clear increase in the fluidity value, for example i2 85599 the fluidity value of the mixture increases by about 33%.

The resulting mixture is thixotropic. It is believed that the particle size of the solid particles dispersed therein is so small that about 80% by weight, or more, of its own particle size is less than 10. The temperature of the mixture is about 49-54 ° C (at this temperature its viscosity is higher than about 21 ° C). It is poured out of the mixing vessel (e.g., through a bottom valve when the vessel has a conical bottom, or through the lower side valve of a nearly flat-bottomed vessel). About 10% of the mixture remains as a "final residue" in the container; due to its flow properties, it is difficult to remove the entire mixture from the vessel.

The whole of the above procedure is then repeated over and over again in the same vessel without the final batches being removed at all.

The high-speed dispersing device may comprise a circular horizontal plate with alternately upward and downwardly directed teeth on the circumference, and the plate is mounted (on a vertical downwardly directed arm) so that it rotates so rapidly that the circumferential speed of the (teeth) exceeds 22.88 m per second (for example, 27.45 m per second). The Covles high-speed dispersing device is suitable for laboratory work. For larger-scale work, the Myer model 800 series of high-speed dispersing devices can be used. These high-speed dispersing devices reduce the particles by impact grinding by means of a toothed plate and by means of a laminar shear load on the mixture. Cutting generates heat in the charge in addition to the heat generated by dissolution, hydration, etc. At the resulting relatively high temperature, the components dissolve more and crystallization upon cooling gives relatively small particles that do not settle quickly, if at all. High-speed dispersing device. induces "rotation" of the mixture, i.e. the path of the mixture is downwards * 1 in the middle of the vessel, outwards along the side of the rotating plate, upwards along the walls of the vessel and inwards on the upper surface of the mixture.

: During this movement, it preferably takes place without exiting, *: *: i.e. air (which always enters when powders are added) leaves the mixture during its inward part of the cycle.

i3 85599

After the preparation of the above mixture, there is apparently an increase in the size of the crystals to form several larger and relatively uniform crystals (as seen in the photomicrograph). Figure 4 shows that crystals with diameters of about 80 μm are included. These crystals appear to contain polyphosphate, but have not yet been fully identified.

Example 5

Example 4 is repeated except that the STPP powder is Monsanto's anhydrous STPP prepared according to a known "dry method" and contains anhydrous STPP moistened to such an extent that its hydrate has a water content of 1/2% (or slightly higher, for example 1 1/2%). It has a phase I content of about 20%. This STPP was also used in Example 3.

Example 6

Example 4 is repeated except that the relative proportion of water is initially 28.0 parts, the second part is 13.637 parts, and 1.11 parts of a 45% aqueous solution of sodium polyacrylate (Acrysol LMW-45N having a molecular weight of about 4,500) are added before the addition of atta-pulgite clay. The amount of K 2 CO 2 in this case is 3 parts and the amount of N 2 CO 2 is 4 parts.

The following typical properties were observed with the products of Examples 4-6:

Example: £ 56

Viscosity (cP) 4000 6000 4400 2

Flow value (dynes / cm)

Capillary emptying time .. (min) 8.2 5.6 6.1

Separation by centrifuge (%) 16 26.3 12: Thixotropic index 5 4.3 4.1 "Centrifuge separation" is measured by centrifugation at 275 G as described in Example 3 above and by measuring the volume of the clear liquid layer relative to the total volume.

n 85599 "Thixotropic index" is the ratio of viscosity at 30 rpm to viscosity at 3 rpm measured at room temperature on a Brookfield HATD viscometer, rotation # 4.

Example 6 contains a soluble chlorine bleach resistant polymer in the blend. It has been found that the presence of the polymer improves the strength against separation during standing or centrifugation of the product without a corresponding large increase in the viscosity of the product. It should be noted that the polymer is present in this case in a highly concentrated (saturated) electrolyte solution. It has also been found that the presence of polymer provides better protection for the glazing of the surface of the containers (fine porcelain). To date, these effects have been observed with polyacrylic acid salts, which have been found to be well compatible with chlorine bleach and clay in this system, for example the concentration of active chlorine has remained the same and the viscosity has remained the same. Polymers of different molecular weights can be used; for example, the polymer may have a molecular weight of less than 10,000 or 100,000 or more. Preferred molecular weights are 1,000 to 500,000. Molecular weights of about 1,000 to 50,000 are particularly practical in that they provide less film on the glass. The proportion of polymer can be between 0.01 and 3%, of which a lower concentration is more suitable for higher molecular weight polymers (e.g. 0.06% for a polymer with a molecular weight of 300,000). Other bleach-resistant polymers can also be used, for example Tancol 731, a sodium salt of a polymeric carboxylic acid having a molecular weight of about 15,000.

In the present invention, all parts are by weight unless otherwise indicated. Atmospheric pressure is used in the examples unless otherwise indicated.

• · »

It is to be understood that the foregoing detailed description *: "is provided solely for the purpose of illustration and that modifications may be made without departing from the spirit of the invention.

• I »·» *

Claims (8)

1. Aqueous thixotropic detergent composition for use in automatic dishwashers, characterized in that it comprises about 8-35% by weight of alkali metal tripolyphosphate, clay thickeners in an amount sufficient to give a thixotropy index of about 2.5-10. a chlorine-bleaching compound in an amount which gives the amount of active chlorine of about 0.2-4% by weight and from about 0.01 to about 3% by weight of water-soluble polymeric carboxylic acid salt, and the remainder water. 2. A composition according to claim 1, characterized in that said polymeric carboxylic acid salt is polyacrylate. 3. A composition according to claim 2, characterized in that the polyacrylate is sodium polyacrylate having a molecular weight of approx. 1,000 - 500,000. 4. A composition according to claim 3, characterized in that the polyacrylate has a molecular weight of 1,000 to 50,000. 5. A composition according to claim 4, characterized in that an alkali metal carbonate is present. 6. A composition according to claim 5, characterized in that the metal metal carbonate is a potassium carbonate. 7. A composition according to claim 1, characterized in that it comprises potassium tripolyphosphate. Composition according to claim 1, characterized in that it comprises potassium pyrophosphate.