LU86041A1 - DETERGENT FOR A DISHWASHER - Google Patents

Description

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One aspect of the present invention relates to a thixotropic aqueous detergent for an automatic dishwashing machine, comprising a liquid phase which is water containing, in solution, tripolyphosphate, sili- ions. 5 cate and alkali metal and, in dispersion, a thickener of the non-swelling clay type (preferably of the attapulgite type) and a solid phase which consists mainly of sodium tri-polyphosphate. The composition preferably also contains a chlorine bleach (preferably dissolved sodium hypochlorite) and an anionic surfactant resistant to the bleach. It also preferably contains an alkali metal carbonate. United States patent application 497,615 (= FR.83.11811) filed on May 24, 1983 describes certain compositions of this type.

It has now been found that greatly improved results are achieved by including a limited proportion of a water-soluble potassium compound, for example a potassium salt (or KOH) in the composition to obtain a K weight ratio: Na which is in the range of about 0.04 to 0.5, preferably about 0.07 to 0.4, for example about 0.08 to about 0.15. The resulting product is much more stable in the sense that it has less tendency to thicken unfavorably or separate on aging, for example at 38 ° C. Likewise, the replacement of part of the sodium salt with the same weight of the corresponding potassium salt results in a considerable reduction in viscosity (for example as measured using a Brookfield HATD viscometer at 25 ° C. at 20 rpm using spindle # 4), greater stability against separation upon aging (e.g., at room temperature), and inhibition of the growth of relatively large crystals to aging. The reduction in viscosity facilitates handling in the production plant, distribution in service, and helps the consumer to destroy the thixotropic structure of the product (by shaking the container in which it is contained), so that it can be easily poured into the detergent compartment (s) of a ma-

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r Γ 2 domestic automatic china for washing dishes.

In a formulation of the product, the proportions and the ingredients indicated in the aforementioned United States patent application No. 497,615 can be used.

In this application, a series of ranges of proportions is approximately, by weight: (a) 8 to 35% of alkali metal tripolyphosphate, (b) 2.5 to 20% of sodium silicate, (c) 0 to 9 % of alkali metal carbonate, 10 (d) 0.1 to 5% of an active material of the organic detergent type dispersible in water and stable with respect to a chlorine bleach * (e) 0 to 5% of foam depressant stable vis-à-vis a chlorine bleach, 15 (f) a chlorine compound as a bleach, in a proportion which can provide about 0.2 to 4% of available chlorine , and (g) a thixotropic thickener in a proportion sufficient to give the composition a thixotropy index of approximately 2.5 to 10.

Preferably, in the compositions described here, the proportion of sodium tripolyphosphate is greater than 15% (better still in the range of about 20 to 25 or 30%), the proportion of sodium silicate is at least about 4% (for example in the range of about 5 to 10 or 15%), the proportion of alkali metal carbonate is about 2 to 6 or 7%, the proportion of chlorine bleach is such that it provides more than 0.5% of available chlorine (for example about 1 to 2% of available Cl), the proportion of active detergent material is in the range of 0.1 to 0.5% . Calculated as SiO 4, a preferred range of proportions of sodium silicate is about 3.5 to 7% of SiO 4 in the composition.

The proportion of water in the compositions (measured using a Cenco humidity analyzer (in which the sample is heated by an infrared lamp, up to 3 § r 3 t what it reaches constant weight) is preferably in the range of about 40 to 50%, more preferably about 43 to 48%, for example about 44 or 45%.

The compositions described herein generally have a pH much greater than 11 or 12. In a preferred type of formulation, the composition, when diluted with water to a concentration of 0.75%, has a pH in the range of about 10.7 to 11.3.

The compositions described herein are preferably formulated to exhibit viscosities (measured with a Brookfield HATD viscometer at 25 ° C at 20 rpm using a pin # 4) of less than about 8000 mPa.s and more preferably in the interval of approximately 2000 or 3000 15 § 7000 mPa.s, for example approximately 4000 to 6000 mPa.s. The cosity screw, and other properties, can be measured a few days (for example a week) after the composition has been prepared; an advantageous practice is to shake the sample before measuring its viscosity and to let the viscometer run for about 90 seconds before taking the reading.

The compositions described here have indices of eeou-. much higher than 20.0 Pa (200 dyne / cm2) and are preferably formulated to have flow indices less than S approximately 110.0 Pa and greater than approximately 30, OPa, more preferably less than approximately 90.0 Pa, for example about 40.0 to 60.0 Pa. The flow index is an indication. the shear rate at which the thixotropic structure collapses. It is measured with a 30 Haake RV 12 or RV 100 rotary viscometer using an MVIP spindle at 25 ° C with a shear speed which increases linearly in 5 minutes (after a rest period of 5 minutes) from zero to 20 seconds "^. In Haake's viscometer, a thin layer of the material is sheared between a rotating cylinder and the immediately adjacent cylindrical wall of the container surrounding it, Figures 1-3 are graphs o.

obtained with such a test on the products of the three examples

Ir t f ♦ magpies indicated, the crests Y showing the flow indices.

Another factor measured with the aforementioned Haake viscometer is the degree to which the composition recovers its thixotropic structure. In a measurement technique after the 5-minute period of increasing the shear speed mentioned above, the rotation is decelerated to zero in 5 minutes, then after a rest period of 30 seconds, the rotation is still accelerated to make the shear speed increase linearly in minutes from zero to 20 seconds ”^. This gives a second flow index, that is to say Yr in FIG. 1. Preferably, this second flow index (recovered) is at least 20.0 Pa, for example 50%, 75 % or more of the flow index initially measured.

FIG. 4 is a photomicrograph (taken on the scale indicated in this figure) of the composition of example 4.

The following nonlimiting examples are given by way of illustration of the present invention.

In these examples, Attagel No. 50 is powdered attapulgite clay (from Engelhard Minerais & Chemicals, whose commercial literature indicates that, as produced, it contains about 12% by weight of free moisture, as measured by heating to 104 ° Cf and has a BET specific surface area of approximately 210 mz / g calculated on a basis free from hunridity); Graphtol Green is a coloring agent; LPKN 158 is an anti-foaming agent from American Hoechfet (Knapsack) comprising a 2: 1 mixture of mono- and dialkyl esters of C ^ gC ^ g of phosphoric acid, sodium silicate has a ratio ^ OîSiO ^ of 1: 2.4; Dowfax 3B2 is a 45% aqueous solution of sodium monodecyl- / didecyl-diphenyl oxide disulfonates, an anionic surfactant resistant to bleaching agents; STPP is sodium tripolyphosphate. Unless otherwise specified, STPP is added as the finely divided commercial anhydrous material of which

Ir i ♦ 'water content is about 0.5%; in this material, in general about 4.5 to 6.5% of the material is present * in the form of pyrophosphate. The water used is deionized water unless otherwise specified.

5 * EXAMPLE 1

The following ingredients are introduced into a container in the order shown below while mixing with a conventional laboratory stirrer of the paddle type. The temperatures and the mixing times at the various stages are also indicated below:

Mass Temperature (g) (° C) ·

Graphtol green at 10% (dye) 5

Water at 54.4 ° C 1746 LPKN 158 (defoamer) 8

Dowfax 3B2 (surfactant) 40 52.2 (2 min) 9: 1 mixture of Attagel ND50 and TiO ^ as white pigment 180 20 50.0 (1 min) 48.9 (3 min)

Anhydrous sodium carbonate 275 K2C03 "75 56.7 (1 min) ^ 56.6 (3 min) STPP hexahydrate fine powder 750 52.8 (1 min) 51.7 (3 min) 51.1 (5 min)

Aqueous solution at 47.5% of sodium silicate 421 previously mixed with an aqueous solution & 50% of NaOH 150 47.8 (3 min) 35 Aqueous solution at 13% of NaOCl 500 42.2 (3 min) 6

T

t STPP hexahydrate fine powder 750 42.2 (1 min)

Total 5,000 g 41.7 (5 min)

The viscosity of the mixture, measured as indicated above, is approximately 5,000 mPa.s after 3 weeks aging at 38 ° C, and approximately 4,800 mPa.s after aging of 3 months at 38 ° C.

In this Example, the STPP hexahydrate has the following approximate particle size distribution:

Rest on a mesh screen of: 10 (m) (*) 2.00 0 0.42 0 0.149 25.4 0.074 31.5 15 0.044 16.5

Passes through a 0.044 mm mesh screen 25.9 EXAMPLE 2

The following formulations are prepared and their properties are measured as indicated below:

The ingredients are mixed in the following order: water, dye, clay, half of the phosphate, antifoam, hypochlorite, sodium carbonate, potassium carbonate, NaOH, silicate, the second half of the phos- 25 phate, the surfactant.

Ingredients Proportions a_ b c d

Clay (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 30 - - 6.5

Potassium pyrophosphate - - 5.99 - 0

Sodium carbonate 5.0 - 5.0 5.0 2.5

Potassium carbonate - 5.0 - - 2.5 35. 3 f 7 "1 b c d

Sodium hypochlorite (12%) 9.375 9.375 9.375 9.375 9.375

5 sodium hydroxide (50 X) 2.05 2.05 2.05 2.05 2.05

Sodium silicate (47.5%) 10.53 10.53 10.53 10.53 10.53

Surfactant (Dowfax 3B-2) 0.80 0.80 0.80 0.80 0.80

Defoamer 10 (Knapsack LPKN) 0.16 0.16 0.16 0.16 0.16

Dye 0.381 0.381 0.381 0.381 0.381

Water the rest

Properties Flow time 15 capillary (min) 8.2 12.1 10.9 11.4 11.2

Viscosity (mPa.s) after aging at 38 ° C

1 week 9080 3100 2900 5120 5400 2 weeks 9200 3480 2820 6340 5240 20 3 weeks 9300 3600 3040 6700 6560

The capillary flow time is a conventional test in which a circle with a diameter of 6.8 cm is drawn on a sheet of 15 cm-diameter of filter paper

Whatman size 41, a plastic ring · 25 (inside diameter 3.5 cm, outside diameter 4.2 cm, height 6.0 cm) is placed vertically, concentrically with the circle, on the fi ltr paper, and the ring is filled with the composition to be tested. The liquid from the composition is thus absorbed on the filter paper and slowly spreads to the traced circle. The time which elapses until the liquid comes into contact with the circle is measured at three predetermined points and an average value is calculated. This prediction role test indicates the relative stability of these systems. Thus, composition 35 (b) has a lower viscosity and greater stability than composition (a) above.

D

18 EXAMPLE 3

The following formulations are prepared by mixing the ingredients in the order indicated. The compositions are then centrifuged at 275 g until there is no more increase in the volume of the clear (continuous) separated liquid phase and the resulting liquid is analyzed: a £ d

Deionized water 27,106 îd id id

Dye 0.016 10 Sodium carbonate 6 420

Potassium carbonate 0 246 STPP * 21.106 id. there 1d

Deionized water 14,184 id id id

Attagel N ° 50 4.00 id id id 15 T i Op 0.444 id id id

50% NaOH solution 2.5 id id id

Sol uti on with 47.5% sodium silicate 13.684 id id id

Defoamer 0.16 id id id

13% NaOCl solution 10.0 id id id

45¾ solution of active surf 0.8 id id id 100.00 "**

Thus, the compositions are identical except for their K: Na ratios.

25 Product Properties a. b c (i

Viscosity (mPa.s) after 1 day at room temperature 8,320 5,520 4,200 2,120 after 3 weeks 30 at room temperature 8,550 6,200 4,500 2,420

After aging at 38 ° C for 7 weeks 9400 8000 5600 3400

Density 1.37 1.37 1.40 1.39 35 i> »9

Properties of the liquid obtained by centrifugation .a b c d

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

Na20: Si02 of 1: 2.4) 7.5 7.3 7.3 7.1% carbonate (calculated as Na ^ CO,) 8.8 8.5 7.4 6.6 10% of phosphate (calculated as Na5P3010) 1.7 2.5 3.7 6.1

Density 1,257 1,262 1,276 1,30

The viscosities of the product in this example are measured with a Brookfield RVT viscometer, pin # 5, at 26.7 ° C.

Examples 4 to 6 below illustrate a new and useful process claimed in a parallel patent application of the Applicant filed the same day for the manufacture of the products described above (containing limited quantities of potassium). It can also be used to manufacture other products of the type indicated in the patent application of the United States of America No. 497 615 • mentioned above (for example in which the compound of potas-25 sium is absent) as well as other detergent suspensions comprising fine particles of water-soluble mineral detergency builder salts dispersed in water containing in solution the detergency builder salt, clay or other colloidal thickener, and the surfactant. In these examples (in which the particles of the detergency builder salt contained in the product consist largely of STPP hexahydrate plus hydrated sodium carbonate), a very viscous mixture is formed (for example with a viscosity of 20 000 to 60,000 mPa.s) of a limited amount of water, a highly alkaline saturated solution of detergency builder salts and, as the dominant constituent, undissolved particles of adjuvant salt. t of water-soluble detergency. This viscous mixture is subjected to grinding of the undissolved particles using a high-speed dispersing device after which the solid particles of the clay thickener are added and the clay is mechanically deagglomerated. then the rest of the ingredients of the formula (for example other liquids or materials which dissolve or disperse easily in the liquid phase with a high electrolyte content) can be mixed there. be subjected to another mechanical action of high shear to further deagglomerate the clay. It has been found that with this process, the prior dispersion of the clay in an aqueous medium is not necessary. Solid clay particles are easily dispersed even if the medium is strongly alkaline. The grinding of the particles of undissolved detergency builder salt takes place much more efficiently and quickly in the almost total absence of clay.

In the process illustrated by Examples 4 to 6, the 2nd detergency builder salt which constitutes the dominant part of the undissolved particles is preferably added to an aqueous solution which already contains such a concentration of other builder salts detergency dissolved as this addition results in the adjuvant detergency salt being rejected from the solution (eg by a common ion effect) and thus recrystallized as tiny crystals.

Another important feature of the mixing process illustrated in Examples 4-6 is the fact that it makes it possible to manufacture repeated batches having reproducible properties using the whole "heel" of the batch previously formed as an ingredient in each successive batch.

As indicated above, the use of the process illustrated in Examples 4 to 6 is not limited to the manufacture of compositions containing potassium salts. Although it has so far found its greatest use

It is used in the manufacture of formulations in which the clay is attapulgite, it can also be used for compositions in which all or part of the clay is of the swelling type, for example a clay of the type smectite such as bentonite (for example Gelwhite GP) or hectorite.

EXAMPLE 4

2.0 parts of deionized water mixed with a small amount of a pigment (i.e. 0.028 part of 10 Graphtol green, an aqueous paste containing 28% pigment) is completely dissolved in 2.0 parts of KgCOj (whose solubility in water is more than 100 parts per 100 parts of water even at 0 ° C and 5.0 parts of granular sodium carbonate (whose solubility in water is about 15 (45 parts per 100 to 35 ° C.) The solution has a temperature of approximately 32.2 ° C. Then 23.116 parts of powdered STPP containing approximately 0.5% water of hydration are added, while continuing to subject the mixture to the action of a high speed dispersing apparatus, the amount of STPP is much greater than that which is soluble in the amount of water present; its solubility in water is about 20 g per 100 ml -at 25 ° C. In this example, • STPP is a product of Olin Corp. having a phase 1 content of approximately 50%, a sodium sulphate content of approximately 25%, and a very small particle size; it is a mixture of anhydrous STPP in powder made by the known "wet prooed" and of STPP in hexahydrate powder. When STPP is added to the solution, it hydrates rapidly to form hard crystal lumps comprising STPP hexahydrate. (Note that 23 parts of STPP can, by forming the hexahydrate, absorb up to about 7 parts of water). The mixture is first of all a dilute suspension of STPP not dissolved in a liquid which is a supersaturated solution. The temperature rises.

Due to the hydration reaction, reaching a maximum of about 60 ° C. In about 3 to 4 minutes, the mixture becomes much more viscous; its viscosity is more than 20,000 mPa.s (for example around 40,000-50,000 mPa.s, as measured at the temperature of the suspension, for example with a Brookfield 5 RVT viscometer, pin No. 6 at 10 rpm). It is believed that during the process, the sodium carbonate separates from the solution phase by crystal ionization (in the form of very fine crystals) due to the effect of common ions (sodium from STPP). When the mixture has become viscous, the high speed dispersing apparatus 10 acts to grind the particles (for example hydrated STPP) to a fine particle size; the grinding action is indicated on the one hand by the increased energy consumption of the dispersing apparatus and on the other hand by an additional rise in temperature (for example up to 65.6ec, which causes increased dissolution of the detergency builder salts; these, in turn, recrystallize as fine crystals by cooling). This grinding is continued for about 5 minutes after the initial thickening of the suspension; during grinding, visible lumps of material disappear and the particle size of the undissolved particles is reduced so that it is assumed that almost all of the particles have diameters less than 40 micrometers. Then another 9.367 parts of water are added, lowering the viscosity to less than 10 000 mPa.s (for example in the vicinity of 5000 mPa.s, measured as indicated above), after which 3.3 are added. parts of Attagel No. 50 and 0.732 parts of white T i O2 (anatase) as a pigment with a highly alkaline mixture 30 (whose pH is much higher than 9, for example 10.5) while the mixture is continuously subjected to the action of the high-speed dispersing device, which disperses (deagglomerates) the clay to a great extent, so that the thick mixture becomes homogeneous and smooth in appearance.

35 then added 2.70 parts of 50% aqueous NaOH solution, 0.16 part of antifoam (Knapsack LPKN 158), 10.53 to 13 parts of 47.5% aqueous sodium silicate solution (of which the ratio ^ OîSiC ^ is 1: 2.4), 10.0 parts of a 12% aqueous solution of sodium hypochlorite and 0.8 part of a 45% aqueous solution of an anonic surfactant resistant to bleach (Dowfax 3B2); these additions can be made under any desired mixing conditions, for example by simple stirring (although it may be convenient to continue the high shear dispersing action for such a mixture). The mixture is then subjected to a grinding action, for example by passing it through a continuous mill such as "Dispax Reactor" from Tekmar which operates at a top speed of 22 meters per second) which subjects the mixture to a high rate of shear for a relatively short time (for example the "residence time" in the mill can be as little as two seconds or less). The main effect of this is to further disaggregate the clay particles, as indicated by a marked increase in the flow index, for example by raising the flow index of the mixture by about 33%.

The resulting mixture is thixotropic. The particle size of the dispersed solid particles contained therein is believed to be so small that about 80% by weight or more has particle sizes of less than 25 microns. The mixture is at a temperature in the region of 49-54.5 ° C (at this temperature, its viscosity is higher than, for example, 21.1 ° C). It drips from the mixing container (for example from a lower valve when the container has a conical bottom, or from a lower side valve of a mixing container with a substantially flat bottom). About 10% of the mixture remains as a "bead" in the container; due to its flow characteristics, it is difficult to remove the entire composition of the container.

The procedure described above is then repeated in its entirety many times in the same way as the recipient of the mixture without ever removing the heel.

The high speed dispersing apparatus may include a circular horizontal plate having circumferential teeth alternating up and down, which plate is mounted (on a vertical shaft directed downward) so as to rotate quickly enough so that the circumferential speed (of the teeth) is greater than about 22.86 m / s (for example 24.5 m / s).

For laboratory scale operation, a Cowles high speed dispersion apparatus is suitable; for larger scale operation, a Myers model 800 high speed disperser can be used. These high speed dispersers reduce particles by grinding, impact, tooth plate and laminar shear force exerted on the mixture. Shear generates heat in the load, in addition to the heat generated by dissolution, hydration, etc. At the resulting relatively high temperature, the ingredients are more soluble and, after crystallization on cooling, give relatively small particles which dissolve only slowly, if not completely. The high-speed dispersing apparatus causes the mixture to "roll", that is to say that the path of movement of the mixture descends in the center of the container, outwards along the rotary plate, upward along the side walls of the container, and inward at the top surface of the mixture. During this movement, a desirable deaeration occurs, that is, the air (which is always introduced when the powders are added) leaves the mixture during its inward journey.

Apparently, after processing the composition described above, crystal growth appears giving many crystals of larger and relatively uniform size (as indicated by the photomicrographs). Thus, Figure 4 indicates the presence of crystals with a diameter on the order of 80 micrometers. These crystals appear to contain polyphosphate but have not, however, been fully identified.

EXAMPLE 5 Example 4 is repeated with the difference that the STPP powder is an anhydrous STPP from Monsanto manufactured by the known "dry process" and comprises anhydrous STPP humidified insofar as its water content of hydration is 0.5% (or slightly more, for example 1.5%). Its phase I content is approximately 20%. This STPP is also used in Example 3.

EXAMPLE 6

Example 4 is repeated with the difference that the initial proportion of water is 28.0 parts, the second proportion of water is 13.637 parts, and before the addition of attapulgite clay, we add 1.11 part of an aqueous solution at 45% of sodium polyacrylate (Acrysol LMW-45N, having a molecular weight of approximately 4500). The amount of I ^ CO ^ here is 3 parts and the amount of 20 ^ 2 ^ 2 is 4 parts.

It was found that the products of Examples 4 to 6 had the following characteristics:

Example 4 5 6 25 Viscosity (mPa.s) 4000 6000 4400

Flow index (Pa) 45. 60 45

Capillary flow time (min) 8.2 5.6 6.1 Separation by centrifugation (%) 16 26.3 12 30

Thixotropy index 5 4.3 4.1

The "separation by centrifugation" is measured by centrifugation at 275 g as described in Example 3, above, and by measuring the volume of the transparent liquid phase compared to the total volume.

The "thixotropy index" is the ratio of the viscosity at 30 rpm to that at 3 rpm, measured at room temperature 16 with a Brookfield HADT viscometer, pin No. 4, as described in said patent application No. 497 615.

In Example 6, a soluble polymer resistant to 5 chlorine bleaches was present. It has been found that the presence of the polymer improves the resistance to separation of the product at rest or by centrifugation, without imparting a proportionally greater increase in the viscosity of the product. Note that the polymer is present here in a very highly concentrated (saturated) electrolyte solution. It is also noted that the presence of the polymer results in better protection of the glaze layer of the dishes (fine porcelain). In fact, heretofore, these effects have been observed with polyacrylic acid salts, which have been shown to be fully compatible with chlorine bleaches and the clay of this system; for example the content of active chlorine is maintained, as well as the viscosity. Polymers of different molecular weights can be used; for example, the polymer may have a molecular weight of less than 10,000, or a molecular weight of 100,000 or more. Preferred molecular weight ranges are from about 1,000 to 500,000. Molecular weights of about 1,000 to 50,000 are particularly noted to achieve less film formation on the glass. The proportions of polymer can be from 0.01 to 3%, the lower proportions being more suitable for polymers of high molecular weight (for example 0.05% for a polymer of molecular weight of 300,000). Other polymers resistant to bleaching agents can be used, for example Tancol 731 which is a sodium salt of a polymeric carboxylic acid having a molecular weight of about 15,000.

In the present application, all the proportions are expressed by weight unless otherwise indicated. In the examples, atmospheric pressure is used, unless f 17 otherwise specified.

It goes without saying that the invention is not limited to the embodiments described and that it is capable of various variants without departing from its scope.

Claims (7)

118 CLAIMS 1 - A thixotropic aqueous composition for an automatic dishwashing machine, characterized in that it comprises a liquid phase which is water containing, in solution, alkali metal tripolyphosphate, alkali metal silicate and, in dispersion, a non-swelling clay as a thickener and a solid phase which consists mainly of sodium tripolyphosphate, the weight ratio K: Na being about 0.04 to 0.5. 2. Composition according to claim 1, characterized in that it has a flow index of at least 20.0 Pa. 3. Composition according to claim 2, characterized in that it contains a bleaching agent of the chlorine type, an alkali metal carbonate and a surfactant resistant to the bleaching agent. 4. Composition according to claim 1, characterized in that said composition contains about 20 to 25% of sodium tripolyphosphate. 20 5 - Composition according to claim 3, characterized by the presence of potassium carbonate. 6. Composition according to claim 3, characterized by the presence of potassium potassium triphosphate. 7. Composition according to claim 3, character-sized in that it comprises potassium pyrophosphate. *