FR2619574A1 - AQUEOUS THIXOTROPIC CLAY COMPOSITIONS, PROCESSES FOR IMPROVING STABILITY THEREOF AND METHOD OF USING THEM FOR CLEANING DISHES - Google Patents

Abstract

The invention relates to improving the physical stability of an aqueous thixotropic composition containing clay as a thixotropic agent. Incorporation of a small amount, for example 0.1 to 0.2 percent by weight, of a polycarboxylic acid or a metal or ammonium salt of polycarboxylic acid, in such a composition significantly improves its long-term physical stability while retaining its thixotropic properties, possibly allowing the use of less thixotropic agent. The composition is used in particular as a thixotropic aqueous detergent product for automatic dishwashers and then contains, in addition, an alkali metal tripolyphosphate, sodium silicate, an optional alkali metal carbonate, a detergent, an optional foam inhibitor, pH adjusting agents and optionally a chlorine bleach, and water. Field of application: detergents for automatic dishwashing.

Description

12- The present invention relates to an aqueous suspension of clay

  thixotropic whose physical stability

  is improved. More particularly, the invention

  the use of polycarboxylic acids and their metal salts as physical stabilizers

  only for aqueous suspensions of thixotropic clays.

  The present invention relates to any spe-

  washing detergent compositions.

  than dishes with thixotropic properties

  spikes, better physical and chemical stability and increased apparent viscosity, and which are easy to disperse in the washing medium to efficiently clean plates, glasses, china, etc.

  Commercial detergents for dishwashers

  the automatic: <domestic that are provided in form

  many disadvantages, for example

  a non-uniform composition; the operations

  which are necessary for their manufacture; a tendency to become en masse when stored under high humidity, which results in the formation of

  large pieces that are difficult to disperse; a CA-

  dusty character which is a source of irritation

  particular for users suffering from

  gies; and a tendency to agglomerate in the distribution

scorer of the dishwasher.

  Recent research and development activity

  concentrated on the "gel" or "thixotropic" form

  such compositions, for example the products

  scrubbing cleaners and dishwashing products

  saddle, which are characterized as being

  thixotropic pastes. Products for dishwashers

  the so provided are mainly subject to criticism by the fact that they are insufficiently viscous to remain "anchored" in the dispenser compartment of the dishwasher, and they leave moreover small residual stains on the plates, the glasses, the

  porcelain, etc. Ideally, the cleaning compositions

  your thixotropes should be viscous at rest, have a Bingham plastic nature, and present

  relatively high flow limits. How-

  when they are subject to

  shearing, for example by being shaken in a

  container or expressed by an orifice, these compositions

  should be rapidly fluidized and, when

  shear stresses ceases to be applied, reve-

  quickly develop into a state of high viscosity / plasticity

  Bingham. Stability is also important

  this means that there must be no obvious sign of phase separation or seepage

after a long rest.

  French patent application 86 08287, de-

  submitted on 9 June 1986 by the Applicant, concerns

  detergent compositions for washing the dishes

  the, which are aqueous suspensions of thixo-clays

  tropes, containing polyvalent metal salts of

  long-chain fats, such as aluminum stearate

  nium, as agents of physical stability. The com

  positions of the application N 86 08287 offer an improvement

  the physical stability of the detergent composition and an improvement against phase separation with respect to clay compositions which do not

  contain no aluminum stearate.

  Obtaining washing machine compositions

  automatic gel saddle with the properties described above, except for the improvements described in the aforementioned application

  N 86 08287, has proved extremely problematic

  particularly with regard to the compositions

  for use in automatic dishwashers

  mestic. For an effective job, it is generally

  It is recommended that automatic dishwashing detergent, also referred to as DLVA hereafter, contain: (1) sodium tripolyphosphate (NaTPP) to soften water or retain mineral substances from

  hard water and to emulsify and / or peptize the

lissures;

  (2) sodium silicate to bring alkali

  necessary for a good detergent action and for

  provide protection for the varnishes and patterns of

  fine celain; (3) sodium carbonate, generally considered optional, to enhance alkalinity;

  (4) a chlorine releasing agent to assist in

  elimination of small soiling that leads to the formation of water spots; and (5) an anti-foam / surfactant combination to provide the required detergency and reduce the

  foam, which increases the efficiency of the machine.

  See, for example, SDA Detergents in Depth, "For-

  Aspects of Machine Dishwashing ", Thomas

  Oberle (1974). The cleaning products that come

  compositions described above are essential.

  usually liquids or powders. It has proved difficult to associate these ingredients in a form of

  gel suitable for use in a domestic machine.

  In general, these compositions do not contain hypochlorite-type bleaching agents because they have

  tendency to react with other chemical ingredients

  active ingredients, especially surfactants. So, the

  U.S. Patent No. 4,115,305 discloses

  xotropes for automatic dishwashers, containing

  a suspending agent, for example a carboxymethylcellulose

  lose, synthetic or other clays,

  including silicates, phosphates and poly-

  phosphates; a small amount of surfactant and a foam inhibitor. There is no mention of bleach. U.S. Patent No. 4,147,650

  is a bit similar, a chlorine bleaching agent

  re (hypochlorite) being optionally included, but neither organic surfactant nor foam inhibitor. The

  product is further described as a suspension

  tergente thick, devoid of thixotropic properties

apparent issues.

  U.S. Patent 3,985,668 discloses scrubbing abrasive cleaners having a gel consistency, which contain:

  (1) a suspending agent, preferably

  smectites and attapulgite types; (2) an abrasive, for example, siliceous sand or perlite; and (3) a low polymeric filler

  reduced density to powder, expanded perlite or

  very, which has buoyancy and thus has a stabilizing effect on the composition, besides the fact that it serves as a bulking agent thus replacing water that would otherwise be available to form

  undesirable supernatant layer as a result of

  and phase destabilization. Inputs

2 6 1 9 5 74

  previous ones are essential. Ingredients

  culturatives include a bleaching hypochlorite, a surfactant stable to the bleaching agent and a buffer, for example silicates, carbonates and monophosphates. Detergent adjuvants, such as

  NaTPP, may be included as optional ingredients

  additional resources to assume or complete the

  adjuvant function not ensured by the buffer, the

  portion of such a detergency builder not exceeding 5% of the total composition, according to this patent. The desired PH values (above pH) are maintained by the buffer / adjuvant components of

  detergency. It is said that a high pH minimizes the

  composition of the chlorine bleach and an undesirable interaction between the surfactant and the agent

  whitening. There is no mention of

foam.

  In United Kingdom patent applications

  GB-2 116 199A and GB-2 140 450A, in the name of Colgate-Pal-

  molive, there are described liquid DLVA compositions which have properties characterizing advantageously

  a thixotropic structure of the gel type which includes

  the various ingredients necessary for

  effective detergent action in a dishwasher

  tomatic. The aqueous detergent composition for

  Automatic dishwasher, normally in the gel state,

  endowed with thixotropic properties, includes

  following ingredients, on a weight basis: (a) 5 to 35% of alkali metal tripolyphosphate; (b) 2.5 to 20% sodium silicate; (c) 0 to 9% alkali metal carbonate;

  (d) 0.1 to 5% organic detergent material

  persistant in water, stable against chlorine bleach; ;

  (e) 0 to 5% styrofoam stably

screw bleaching agent;

  (f) a chlorine bleaching agent in one

  portion capable of providing approximately 0.2 to 4% of available chlorine

  tif; (g) a thixotropic thickener in a proportion sufficient to impart a thixotropic index of about 2.5 to 10 to the composition; (h) sodium hydroxide, as needed, to adjust the pH; and

(i) the additional water.

  The DLVA compositions thus formulated are low foaming and readily soluble in the washing medium, and their effectiveness is greatest at the most favorable pH at the best performance of the washing medium.

  cleaning, that is to say at pH 10.5-14. These composi-

  normally have the consistency of a gel, that is,

  that is to say that they are opaque gelatinous products, very viscous, having a plastic character according to

  Bingham, and their flow limits are therefore

  latively high. Therefore, it is necessary to

  increase or increase their flow a shear force

  It can be determined in the distributor compartment while stirring a dishwasher in operation. Under these conditions, the composition fluidifies rapidly and disperses easily. When shear force ceases

  to be applied, the fluid composition quickly returns

  in a state of high viscosity and plasticity

  Bingham very close to its former consistency.

  U.S. Patent No. 4,511,487 discloses

  a low foaming detergent paste for dishwashers.

  The thixotropic cleaning product described in this patent

  has a viscosity of at least 30 Pa.s at 20 C,

  determined by means of a rotary viscometer at a

  spindle speed of 5 revolutions per minute. The composition

  is based on a mixture of sodium metasilicate

  finely divided hydrate of a chlorine-containing compound

  re active and a thickening agent which is a hectorite-type laminated silicate. It is possible to use

  small amounts of non-ionic surfactants

  and carbonate and / or alkali metal hydroxides

lins.

  The formation of organic clays by the

  clay (such as bentonite and

  torite) with organic compounds such as quaternary ammonium salts has also been described (W.

  Tuesdays, JAOCS, Vol. 61, No. 2, page 382 (1984)).

  Although these liquid DLVA compositions

  described below are not subject to or are

  subject to a lesser degree to one or more of the

  As described above, it has been found that further improvements in physical stability, at lower costs, are desirable to increase the shelf life of the product in store and promote

  thus its acceptance by the consumer.

  Although the combination of a thickener ar-

  gileux and a stabilizer of the type of fatty acid salt of

  polyvalent metal, described in the above-mentioned application

  N 86 08287, have proved satisfactory for

  long-term stability, for example the ab-

  phase separation during periods

  up to 12 weeks or longer, it is often

  desirable to further improve stability in order to avoid phase separation during periods of

up to six months or more.

  In addition, the use of stabilizers

  known products, for example salt stabilizers

  of polyvalent metal fatty acids, and thick

  clay, imposes a definite order of addition of the various ingredients, and a close control of

  operating conditions during the manufacture of the

  position is decisive for getting the properties

  thixotropic and low-moss characteristics

desired age.

  At the same time, it would be very desirable

  to increase the physical stability of other composi-

  liquid thixotropic compositions based on clay, such as

  scouring products, dental pastes,

"liquid", etc.

  Accordingly, a purpose of this invention

  tion is to provide anti-sedimentation

  for aqueous suspensions of thixotropic clays.

  Another object of the invention is to provide

  liquid DLVA compositions possessing proprietary

  thixotropic species together with better

  rheological properties and better physical stability

  that, at lower costs, by using polycarboxylic acids and their metal salts with

  the place of the more expensive salts of polyvinyl

slow fatty acids.

  Yet another object of the invention is to provide thixotropic liquid DLVA compositions.

  containing reduced levels of thixotropic

  without adversely affecting viscosities

  latively high at low shear rates and relatively low viscosities at high rates

  which are characteristic of the properties

desired thixotropic

  More generally, an aim of the present

  The purpose of the invention is to improve the stability of clay-based aqueous thixotropic compositions, especially liquid dishwashing detergent pastes or gels.

  automatically by incorporating into the water suspension

  a minor proportion of a polycarboxylic acid

  boxylic acid and one of its metal salts, effective

  to increase the apparent viscosity of the composition

  and to inhibit particle sedimentation

  in suspension and prevent phase separation.

  Unlike polyvalent metal salts

  long-chain fatty acids, the poly-

  carboxylic acids and their metal salts according to

  The present invention can easily be incorporated into the product, for example by emulsifying them with surfactants, or by adding them directly.

  at the manufacturing expense. Operating conditions

  to make the composition are not critical.

  c. Polycarboxylic acids and their metal salts

  are easily dispersed in the composi-

  tion. The addition of the polycarboxylic acids and their metal salts makes it possible to reduce the quantity

  of clay that would be necessary in the absence of

  polycarboxylic and their metal salts.

  In addition, the rheological properties of the product can

  be finely adjusted by acting on the quantity

  of polycarboxylic acids and their salts

  metal which is added to the composition.

  These and other aims of the present

  invention will be better off from the description

  detailed description of the invention and its forms

  preferred embodiments, and they are achieved by

  body in an aqueous liquid composition, normally

  in gel state, a small but effective amount of a physical stability agent which is composed of polycarboxylic acids and their metal salts. More particularly, according to a particular and preferred embodiment of the invention. , it is provided a detergent composition for automatic dishwasher, normally in the state

  gel, in which are incorporated

  lycarboxylic acids and their metal salts in a quantity

  effective to increase the apparent viscosity of the composition and to inhibit sedimentation of suspended particles, such as particles

  of detergency builder and thixotropic clay.

  In this particular aspect, the present

  The invention provides an aqueous detergent composition for automatic dishwashers, normally in the state

  of gel, endowed with thixotropic properties, which

  takes, on a weight basis: (a) 5 to 35% of alkali metal tripolyphosphate; (b) 2.5 to 20% sodium silicate; (c) 0 to 9% alkali metal carbonate;

  (d) 0.1 to 5% of organic detergent

  persistant in water, stable with respect to the chlorine bleaching agent;

  (e) 0 to 5% foam inhibitor, stable vis-à-vis

  chlorine bleach screw;

  (f) a chlorine bleach, in one

  sufficient portion to provide about 0.2 to 4% of active chlorine; (g) a thixotropic thickener in a proportion sufficient to impart a thixotropic index of about 2.5 to 10 to the composition; (h) 0 to 8% sodium hydroxide;

  (i) polycarboxylic acids and their salts

  in a proportion effective to increase the apparent viscosity and physical stability of the composition; and

(j) the additional water.

  In connection also with this aspect parti-

  In accordance with the present invention, the invention provides a method for cleaning dishwashing in an automatic dishwasher with an aqueous wash bath containing an effective amount of the automatic dishwashing liquid detergent composition (DLLVA) as described herein.

  above. According to these aspects of the invention, the composi-

  DLLVA can easily be added to the

  the automatic dishwasher dispenser and, in just a few seconds, rapidly thicken to its normal pasty or gel-like state so as to remain firmly in the dispenser compartment until shear forces are present. again applied, as by the jet

  of water delivered by the automatic dishwasher.

  The present invention is based on the discovery

  surprising and unexpected that

  rheological properties and physical stability,

  ie resistance to phase separation, to the

sedimentation, etc., identical or improved by

  The liquid aqueous DLVA compositions of the prior art can be obtained more economically and without any particular manufacturing requirement.

  by adding to the composition a quantity with a static effect

  bilayer of polycarboxylic acids and their metal salts

  instead of the polyvalent metal salt of

  fat. At the same time, improvements can be

  as to the training characteristics of

  or sail (that is, fewer spots and

  less sail formation). Surprisingly

  For example, compositions prepared with, for example, 0.03 to 0.2% of the polycarboxylic acids and their metal salts have excellent properties.

  rheological and stable storage

  periods of up to six months.

  In general, the effectiveness of the DLLVA is

  directly related to: (a) active chlorine levels; (b) alkalinity; (c) solubility in the washing medium; and (d) inhibiting the foam. It is preferable in the present case that the pH of the DLLVA composition is at least about 9.5, preferably about

  , 5 to 14.0, and more preferably at least about 11.5.

  The presence of carbonate is also often required here because it acts as a buffer that helps maintain the desired pH. However, it is necessary to avoid an excess of carbonate, because it can result in the formation of acicular crystals of carbonate, which alters the

  stability and the ability of the product to be

  tribute, for example from

  pressible. Caustic soda (NaOH) fulfills the function

  to neutralize the inhibitor of

  phosphoric or phosphoric acid ester foam

  when present. Typical proportions

  approximately 0.5 to 6% by weight of NaOH and

  2 to 9% by weight of sodium carbonate in the DLLVA composition, although it should be noted that sufficient alkalinity can be provided by

NaTPP and sodium silicate.

  NaTPP, which is used in the composition of

  In a proportion of about 8 to 35% by weight, preferably about 20 to 30% by weight, the DLLVA should preferably be free of heavy metal which has a tendency to decompose or inactivate the preferred sodium hypochlorite or the others. chlorine bleaching agents. The NaTPP can be anhydrous or hydrated, including stable hexahydrate having a degree of hydration of 6 corresponding to about 18% by weight of water or more. Particularly preferred DLLVA components are obtained using, for example, a weight ratio of 0.5: 1 to 2: 1 anhydrous NaTPP to hydrated NaTPP, ratios of about 1: 1

  being particularly preferred.

  Inhibition of the foam is important

  to increase the efficiency of the dishwasher and half

  the destabilizing effects that might

  come during use because of the presence of excess foam in the machine. The foam can be sufficiently reduced by appropriate choice of the type and / or proportion of detergent substance, which is the main foam-producing component. The degree of foaming also depends to some extent on the hardness of the wash water contained in

  the machine, so that a good adjustment of the

  tions of NaTPP, which exerts a softening effect

  water, can help to achieve the desired degree of

  bition of the foam. However, one can in a way

  optimal include a foam inhibitor or anti-

  Stable foam vis-à-vis the bleach when one wishes to obtain a composition low DLLVA

  foaming. Foam inhibitors particularly ef-

  are the alkylphosphonic acid esters of the formula:

= E0 - P - R

I

-RO- P - R

GOLD

  available, for example, from BASF-

  Wyandotte (PCUK-PAE) and in particular the phosphoric esters

  alkyl acids of the formula: Fi II

HO- P --R

  I OR available, for example, from the companies Hooker (SAP) and Knapsack (LPKn-158); one or both of the R groups in each of these ester types may independently be C12-C20 alkyl groups. Mixtures of these two types, or any other types which are stable to the bleaching agent, or mixtures of mono- and diesters of the same type may be used. Particularly preferred is a mixture of acidic phosphoric esters of mono- and di-C₁--C₁ alkyle alkyl such as monostearyl / distearyl acid phosphates at 1.2 / 1 (Knapsack) or 4/1.

  (Ugine-Kulhplan). If used, typical proportions

  foam inhibitor peaks in the composition are from 0.1 to 5% by weight, preferably from about 0.1 to

  0.5% by weight, the weight ratio of the component de-

  tersif (d) to the foam inhibitor (e) lying generally

  typically from about 10: 1 to 1: 1 and preferably from

  5: 1 to 1: 1. Other anti-foam agents that can be used include, for example, known silicones. In addition, an advantageous feature of the present invention is that a large number of

  polycarboxylic acids and their metal salts

  stabilizers act as destruc-

  is. Although any chlorine bleaching agent can be used in the compositions

  of the present invention, for example a dichloroiso-

  cyanurate, dichloro-dimethyl hydantol or phosphorus

  chlorinated trisodium phate, a metal hypochlorite

  Cullet, for example potassium, lithium, magnesium and in particular sodium, is preferred. The composition should contain sufficient chlorine bleach to provide about 0.2 to 4.0% by weight of active chlorine as determined, for example, by acidifying 100 parts of the composition with an excess of hydrochloric acid . A solution containing about 0.2 to 4.0% by weight of sodium hypochlorite contains or

  provides approximately the same percentage of chlorine

  tif. A level of about 0.8 to 1.6% by weight of active chlorine is particularly preferred. For example, we

  can advantageously use a hypochlorine solution

  sodium rite (NaOCl) at about 11 to about 14% active chlorine in amounts of about 3 to 20%,

  preferably about 7 to 12% by weight.

  Sodium silicate, which gives alkalinity

  and protects the hard surfaces, such as varnishes and patterns of fine porcelain,

  is used in the composition in a proportion

  from about 2.5 to 20% by weight, preferably from about 5 to 15% by weight. Sodium silicate is generally added in the form of an aqueous solution, the ratio Na 2 O: OSiO 2 is preferably

from about 1: 2 to 1: 2.8.

  The detersive substance that can be used here must be stable in the presence of the chlorine bleaching agent, especially a bleaching hypochlorite, and the water-dispersible surfactants of the organic anionic, amine oxide or phosphine oxide type are preferred. sulfoxide or betaine, the anionic surfactants mentioned first being the most preferred. They are used in amounts ranging from about 0.1 to 5%, preferably from about 0.3 to 2.0%. Particularly preferred surfactants herein are mono- and / or di-C8-C14 straight or branched chain alkyl- (diphenyl) -mono- and / or

  disulfates or disulfonates available in the

  merce, for example under the trademarks DOWFAX (registered trademark) 3B-2 and DOWFAX 2A-1. In addition, the surfactant must be compatible with the other ingredients of

  the composition. Other suitable surfactants

  take the alkyl sulphates, alkyl sulphonates and alkyl

  primary aryl sulfonates and sec-alkylsulfates.

  Examples thereof are C10-C18 sodium alkyl sulphates such as sodium dodecyl sulphate and

  (tallow alcohol) sodium sulfate; alkanesulfo-

  C10-C18 sodium nitrates such as hexadecyl-1-

  sodium sulfonate; and alkylbenzenesulfonates

  of C12-C18 sodium, such as dodecylbenzenesulphonyl

  sodium fonates. We can also use

corresponding potassium salts.

  Other suitable surfactants or detergents include surfactants of the amine oxide type which have

  typically the R2R structure N-O where each R is a lower alkyl group, for example methyl, and R1 represents a long-chain alkyl group having 8 to 22 carbon atoms, for example a lauryl, myristyl, palmityl or cetyl group. Instead of an amine oxide, it is possible to use an R2R1PO phosphine oxide or a corresponding surfactant RR 1SO 2 sulfoxide. The beta-type surfactants typically have the structure R2R1N-R'COO-, where each R is a lower alkylene group

  having 1 to 5 carbon atoms. Specific examples

  These surfactants are the lauryl-dimeric

  thylamine, myristyl dimethylamine oxide, the corresponding phosphine and sulfoxide oxides, and the corresponding beta-amines, including

  dodecyl dimethyl ammonium, tetradecan pentanoate

  cyl-diethyl-ammontum, hexadecyl-hexanoate

  thylammonium, etc. To ensure biodegradability,

  the alkyl groups of these surfactants must be

  and such compounds are preferred.

  Surfactants of the foregoing types, all of which are well known in the art, are described, for example, in U.A.

3,985,668 and 4,271,030.

  Thickeners with thixotropic effect, ie thickeners or suspending agents

  which confer thixotropic properties on a

  aqueous place, are known in the art and they can be organic or inorganic, water-soluble, water-dispersible or colloidogenic, and monomers or polymers, and they obviously have to

  be stable in the present compositions, that is,

  for example stable vis-à-vis the strong al-

  and chlorine bleaching agents such as sodium hypochlorite. Particularly preferred thixotropic thickeners generally include mineral clays.

  colloidogens of the smectite and / or attapulgite types.

  These materials have been generally used in

  proportions of about 1.0 to 10% by weight, preferably

  1.2 to 5% by weight, to confer the properties

  thixotropic elements and the character of plasticity Bin-

  The above-described patent applications GB-2,116,199A and GB-2,140,450A of the Applicant have previously been described. One of the advantages of the DLLVA compositions of this

  The invention resides in that the thixotropic properties

  and the desired Bingham plasticity character can be obtained in the presence of the stabilizers of the

  polycarboxylic acids and their metal salts

  with smaller amounts of thickeners to ef-

  thixotropic fetus. For example, proportions of ar-

  colloidogenic mineral oils of the smectite and / or attapulgite types, in the range of about 0.1 to 3%, preferably 0.1 to 2.5%, and especially 0.1 to 2%, are generally sufficient to obtain the

  thixotropic properties and the plastic character

  desired when used in association with

  with the Physical Stability Officer.

  Smectite-type clays include

  montmorillonite (bentonite), hectorite, attap-

  cottage, smectite, saponite and others. Clays

  montmorillonite type are preferred and are available

  under trademarks such as Thixo

  gel (Trade Mark) Na 1 and Gelwhite (Trade Mark) GP, H, etc., from Georgia Kaolin Company; and ECCAGUM (registered trademark) GP, H, etc., from

  from Luthern Clay Products. Clays of the attapul-

  include the materials available in the

  under the trade mark Attagel (trade mark

  Attagel 40, Attagel 50 and Attagel, from Engelhard Minerals and Chemicals

  Corporation. Mixtures of the smectite and

  pulgite, in weight ratios of 4: 1 to 1: 5, are

  also useful here. Thickeners or sus-

  The foregoing types are well known in the art, and are, for example, described in the aforementioned U.S. Patent No. 3,985,668. Avoid

  abrasives or polishing agents in the composi-

  DLLVA, as they can damage the surface of fine crockery, crystal, etc.

  The proportion of water contained in these constituents

  Obviously, the conditions must not be so great as to produce viscosity and fluidity abnormally

  low, or too small to produce a viscous

  abnormally high level and low ability to

  flow, the thixotropic properties being in each case diminished or suppressed. This proportion

  is easily determined by experimenting with

  in any particular case, and is generally from about 30 to 75% by weight, preferably from about 65% by weight and more preferably from about 35 to 45%

  in weight. In addition, the water must preferably be

softened or softened.

  So far, the product description DLLVA,

  Unless otherwise noted, is consistent with that of the compositions described in the aforementioned UK patent applications GB-2,116,199A and GB-2,140.

450A of the Applicant.

  The DLLVA products of these patent applications

  prior art GB-2 116 199A and GB-2 140 450

  have improved rheological properties, such as

  evaluated by measuring the viscosity of the product in

  shear rate. These compositions

  felt a higher viscosity at a rate of

  low sanding and lower viscosity at a high shear rate, with results

  efficient fluidification and gelation

  within the limits of shear rates

  encountered in a standard dishwasher. In practical terms, these results reflect better payout and implementation characteristics as well as lower leakage

  the dispenser compartment of the dishwasher,

  on liquid DLVA products or gel

  the prior art. For shear rates applied

  corresponding to 3 to 30 rpm; the viscosities (Brookfield) ranged from about 10,000 to 30,000 mPa.s at about 3,000 to 7,000 mPa.s as measured at room temperature using a Brookfield LVT viscometer after 3 minutes using N-pin 4. A shear rate of 7.4 s-1 corresponds to a spindle speed of about 3 rpm. An increase of about

  ten times the shear rate produces a reduction

  about 3 to 9 times the viscosity. With the

  DLVA gels of the prior art, the reduction corresponding to

  viscosity was only about twice.

  In addition, with these compositions, the initial viscosity measured at about 3 rpm was only about 2500

  at 2,700 mPa.s. The compositions of the invention

  The Applicant Company therefore had fluidification thresholds at lower shear rates and a significantly greater amplitude in terms of incremental rate increase.

  shear as a function of incremental decay

  mential viscosity. This property of the products

  DLLVA of the previous invention is summarized by a

  thixotropy dice (IT) which is the ratio of visco-

  apparent at 3 rpm and 30 rpm. The components

  of the prior invention have an IT of 2 to 10.

  The DLLVA compositions being tested showed

  a quick and important return to the consistency of the

  anterior rest state when the shearing force

was no longer applied.

  The present invention is based on the discovery of

  green that physical stability, that is,

  the resistance to phase separation, to the separation

  etc., of DLVA liquid aqueous compositions of United Kingdom Patent Applications GB-2,116,199A and GB-2,140,450A and French Patent Application 86,028,887, can be substantially improved, or at least not be adversely affected

  while at the same time significantly increasing visco-

  apparent and improving the physical stability of the compositions for a lower cost, by adding

  the composition a small but effective amount of a-

  polycarboxylic acids and their metal salts.

  As an example of improving property

  It has been found that at low shear rates, for example at a spindle speed of about 3 rpm, apparent viscosities can

  often be increased two to three times

  corporation as small as 0.2%

  or less, for example 0.15%, polycarboxylic acids,

  and their metal used as stabilizers. At the same time, the physical stability can be improved to such an extent that even after a long time, for example 6 months of

  aging at 20 C (TA), the compositions contain

  stabilizers of the polycarboxylic acid type

  their metal salts do not undergo any

visible separation of phases.

  Detailed Description of Stabilizing Agents

  Physical Stability Agents Used

  according to the present invention are polycarboxylic acids.

  boxyl and their metal salts. More specifically

  firstly, gabilizers are carboxylic acids

  low molecular weight compounds and their salts of

  monovalent and polyvalent metal levels.

  Polycarboxylic Acids The polycarboxylic acids that can be used according to the present invention are dimers and trimers of fatty acids, preferably unsaturated fatty acids. Acids can be used

  fat in C8 to C22. Dimers and trimers are prepared

  preferably from C12 to C20 fatty acids, and more preferably from unsaturated fatty acids.

  in C16 to C20. The particular dimer and trimer acids

  are preferably prepared from unsaturated C18 fatty acids, for example oleic acid and

linoleic acid.

  Monovalent metal salts and polyvalent metal salts of dimers and trimers of fatty acids, preferably unsaturated fatty acids,

  may also be used in this

  vention. Ammonium salts of dimers and trimers

  unsaturated fatty acids may also be used

in the present invention.

  A particular preferred group of polyhydric

  carboxylic acids consists of dimers and trimer

  of unsaturated C18 fatty acids which are available

  from Emery Industries, Division of National

  Distillers & Chemical Corp. These materials are available

  are the following trade names Dimers Trimer Polyacid

Empol 1010 Empol 1040 Empol 1052.

  Empol 1018 Empol 1041 Empol 1022 Empol 1024 The products Empol 1040 and Empol 1052 are of particular interest, the Empol 1040 trimer contains typically 80% polyacids, 18% diacid and 2% monoacid. 1052 contains 63% triacids, tetraacids and

  higher order acids with about 34% diacid

  of. In addition to the dimeric and trimeric acids, it is also possible to use as stabilizing agents,

  in the present invention, the polycarboxylic acids

  adipic and azelaic acid and their monovalent metal and ammonium salts and their polyvalent metal salts. Monovalent Metal and Ammonium Salts of Polycarboxylic Acids The monovalent metal salts that can be used are the Group IA metals of the Periodic Table of Elements, and in particular the alkali metal salts. The monovalent metals of Group IA in question are Li, Na, K, Rb, Cs and Fr. The preferred monovalent alkali metals are Na and K.

  Ammonium cation can also be used

  NH4 as an alkali metal. However, it is not necessary

  Do not use chlorine bleaches with fatty acid ammonium salt stabilizers because they are not compatible with these agents and chlorine bleaching. In compositions where fatty acid ammonium salt stabilizers are used, the chlorine bleaching agent can be omitted or an oxidizing enzyme substituted therefor. Redox enzymes, also known as oxidoreductases, can be used in

  present invention. These enzymes catalyze reduc-

  chemical oxidation and oxidation and are involved in the chemical decomposition of food residues on dishes, cutlery and utensils to be cleaned. Suitable enzymes that can be used are glycose oxidase enzymes,

catalase and lipoxidase.

  In the compositions of the present invention

  tion, proteomeric enzymes can also be used.

  lytic and amylolytic agents and mixtures thereof. The

  Suitable proteolytic zymes include liquid, powdered or suspension enzyme preparations. Liquid enzyme preparations

  "Alcalse" and "Esperase",

  by Novo Industries, Copenhagen, Denmark. Liquid protease and amylase can be used

  liquid. Liquid enzymatic preparations of

  pha amylase are those sold by Novo

  Industries and Gist-Brocades under the trade marks

  caiaes "Termamyl" and "Maxamyl", respectively.

  Enzymes can be used in

  proportions of about 0.5 to 3%, preferably about

  0.5 to 2.0%, and more preferably about 0.5 to 1.5%.

  Polyvalent metal salts of polycarboxylic acids

* The preferred polyvalent metals are the metals

  polyvalent levels of Groups IIA, IIB and IIIB, such as magnesium, calcium, aluminum and zinc, although other polyvalent metals including those of Groups IIIA, IVA, VA, VIA, VIIA may also be used , IB, IVB, VB, VIB, VIIB and VIII of the Periodic Table of the Elements. Particular examples of these other polyvalent metals include Ti, Zr, V, Nb, Mn, Fe, Co, Ni, Cd, Sn, Sb, Bi, etc. In general, the metals may be present in the divalent or pentavalent state. The metal salts are preferably

  used in their higher oxidation states. N / A-

  turally, for the DLLVA compositions, as well as for all other applications where the composition of the invention must or may come into contact with articles used for handling, storing or

  serve food products or enter from

  be in contact with human beings or animals or to be consumed by them, the metal salt must be chosen taking into account the toxicity of the

  metal. For this purpose, the calcium and magnesium salts

  sium are particularly preferred as being

  Globally harmless food additives.

  Obviously, for the DLLVA compositions, as well as for all other applications where the composition of the invention must or may come into contact with articles used to handle, store or serve food products or otherwise enter into contact with some beings

  humans or animals or to be consumed by them, the use

  of polycarboxylic acids and their salts

  metal as a stabilizing agent is of

  especially because of their low toxicity. As such, the polycarboxylic acids as such, for example the C18 unsaturated fatty acid dimers and trimers, the Na and K monovalent metal salts and NH4 and the polyvalent metal salts Ca and Mg are particularly preferred as being generally harmless because of their known low toxicity and / or known use as additives

  food. Another distinct advantage of using

  polycarboxylic acids and their metal salts.

  as stabilizers is their low combined price.

  on the polyvalent metal salts of fatty acids.

  There is a large commercial

  of polycarboxylic acids and their metal salts

  lic. For example, dimers and trimers of

  unsaturated C18 fatty acids, and adipic and

  azelalks are readily available.

  The proportion of polycarboxylic acids and their metal salts used as stabilizers for achieving stability improvement

  and the increase in apparent viscosity de-

  depending on factors such as the nature of the

  polycarboxylic and their metal salts, the nature and proportion of the thixotropic agent, the detersive compound, the inorganic salts, in particular TPP, the other ingredients of the DLLVA, as well as

  conditions for storage and transport.

  In general, however, proportions of the polycarboxylic acids and their metal salts used as stabilizers are in the range of about 0.001 to 1%, preferably 0.01%.

  at 0.2%, and more preferably from about 0.05 to 0.2%,

  the increase in apparent viscosity and the

  long-term stability, as well as the absence of phase separation at rest or during transport, at both low and high temperatures,

  way that is needed for a commercial product-

acceptable.

  From the examples which are set out below

  afterwards, it will be seen that, according to the quantities, proportions and types of physical stability agents and thixotropic agents, the addition of the polycarboxylic acids and their metal salts not only increases

  physical stability, but also produces

  simultaneous increase in apparent viscosity.

  The process for preparing the compositions

is not critical.

  1. According to a method of manufacturing such composi-

  first, all mineral salts, ie carbonate, must be dissolved or dispersed

  (if it is used), silicate and tripolyphos-

  phate, in the aqueous medium. The thick agent is added

  last. The foam inhibitor (if used) is previously prepared as an aqueous dispersion, as is the thickening agent. Firstly, the foam inhibitor dispersion, the caustic soda (if it is

  is used) and mineral salts at elevated temperatures

  dissolved in an aqueous solution (deionized water), then cooled, stirring during all this time. To the

  cooled solution (25-35 C), the

  bleaching agent, the polycarboxylic acid and its stabilizing metal salt and the agent dispersion

  thickener at room temperature. Exception

  chlorine bleach, the concentration of

  total salts (NaTPP, sodium silicate and

  carbonate) in the composition is usually about

  20 to 50 percent by weight, preferably about

at 40 percent by weight.

  2. A preferred method for mixing the ingredients of the DLLVA compositions is to first form a mixture of water, antifoaming agent (if used), detergent, polycarboxylic acid and the like. its physical stabilizing metal salt and of

  the thixotropic agent, that is clay. We are

  mix these ingredients together under high shear conditions, preferably starting at

  room temperature, to achieve a uniform dispersion

  form. To this premixed portion, the remaining ingredients are incorporated under low shear mixing conditions. For example, we introduce the

  required amount of the premix in a blender with

  shear, then add the remaining ingredients

  while mixing, one after the other,

  all at once. Preferably, the

  grinds one after the other, although it is not

  necessary to complete the addition of an entire

  given before starting to add the ingredient

  next. In addition, one or more

  ingredients in portions that are added at different times. Good results are obtained by adding the remaining ingredients in the following order of succession: sodium hydroxide, alkali metal carbonate, sodium silicate, tripolyphosphate

  alkali metal (hydrated), aluminum tripolyphosphate

  hull (anhydrous or containing not more than 5% water), bleaching agent (preferably sodium hypochlorite)

and sodium hydroxide.

  3. According to another process for carrying out the present invention, the ingredients are simply added to each other, with moderate stirring, in the order established below. % by weight Deionized water 34-45 Coloring agent 1-3 Clay 0.2-4 Polycarboxylic acid and its salts 0.01-0.2

stabilized ammonium and

  Detergent Organic Substance 0.1-5 Defoaming Agent 0.1-5 NaOH 0.5-6 Sodium Carbonate (Anhydrous) 2-9 Sodium Silicate 5-15 Sodium Tripolyphosphate 20-30 Sodium Hypochlorite (13) % of 0.2-4 active chlorine)

  The particular order of addition of the ingredients

dients is not critical.

  In each of the three processes above, polycarboxylic acids, metal salts specific for polycarboxylic acids or

  mixtures of polycarboxylic acids and / or

  salts of metal salts of polycarboxylic acids.

  Other ingredients may be included

  in these compositions in small proportions, genera-

  less than about 3 percent by weight, for example a perfume, hydrotropic agents such as sodium benzene, toluene, xylene and cumene sulfonates, preservatives, dyestuffs and the like.

  pigments, etc., all obviously having to be sta-

  the chlorine bleaching agent and the high alkalinity (properties common to all components). In the compositions containing an ammonium salt of fatty acid as a stabilizer, it is possible to use enzymes such as glucose oxidase,

  catalase, lipoxidase and proteolytic enzymes

  and amylolytics, in place of the white-collar

  Chlorine chime. For coloring, we prefer

  especially chlorinated phthalocyanines and

  aluminosilicate lysulphides which produce, respec-

  beautiful green and blue hues. TiO2 can be used to whiten or neutralize

degraded shades.

  The liquid DLVA compositions of the present

  The invention is easy to use in a known manner for washing dishes, plates, cooking utensils and the like in an automatic dishwasher, equipped with a suitable detergent dispenser, in

  an aqueous wash bath containing an effective amount of

cace of the composition.

  Although the invention was particularly

  described in terms of its application to

  automatic liquid dishwashers, those skilled in the art will readily appreciate that

  advantages obtained by the addition of polycarboxylic acids

  boxes and their metal and ammo-

  nium, ie increased apparent viscosity and

  better physical stability of the thixo-suspension

  clay-based trope, apply just as well to other clay-based thixotropic suspensions,

  such as scouring paste compositions described

  in the above-mentioned U.S. Patent No. 3,985,668.

  tioned. The invention can be practiced

  various ways and non-limitative examples followed

  examples are illustrative of a certain number of

  many of its particular embodiments.

  All quantities and proportions mentioned

  born here are expressed in weight by weight

  of the composition, unless otherwise indicated.

EXAMPLE 1

  In order to highlight the effect exercised

  by a stabilizing agent of the polycarboxylic acid type

  that a composition is prepared in the following manner

  Liquid DLVA containing a trimer of a fatty acid

  saturated, for example Empol 1040 (Empol 1040 is the tri-

  mother of an unsaturated C18 fatty acid and is supplied by Emery Industries, Div. of National Distillers &

Chemical Corp).

  Percent Deionized Water 41.10 Caustic Soda Solution 2.20 (50% NaOH) Sodium Carbonate Anhydrous 5.00 Sodium Silicate (15.74 to 47.5% Na 2 O: SiO 2 = 1: 2, 4) TPP sodium (substantially anhydrous, 12.00 ie 0 to 5%, especially 3%, moisture) (Thermphos NW) Sodium TPP (hexahydrate) 12.00 (Thermphos N hexa)

  The mixture is cooled to 25-30 by hand

  continuously stirring, and the following ingredients are added at room temperature: Per cent Sodium hypochlorite solution 9.00 (11% active chlorine) 0.18 DOWFAX 3B-2 monostearyl phosphate (aqueous solution a 0.80 45% monodecyl / didecyl (31-diphenyl ether) -sodium disulfonate) Physical Stability Agent X (fatty acid or fatty acid salt) Pharmagel H 2.00

  Three compositions are prepared in which

  the X = 0%, X = 0.10% of aluminum stearate and X = 0.2% of Empol 1040 trimer acid.

  100% compositions by adjusting the water content.

  The foam inhibitor monostearyl phosphate (if used), the Dowfax 3B-2 detergent compound and the Empol 1040 stabilizer are added to the mixture just prior to the Pharmagel H thickener. Experiment 1 corresponds to a composition

  control which contains the monostearyl phosphate

  me antifoam agent, but that does not contain acid

  polycarboxylic acid or a metal salt thereof

  lisants. Experiment 2 corresponds to a control composition identical to that of Experiment 1 to which

  alumina stearate was added as a stabilizing agent.

  reading the aforementioned patent application No. 86 08287

  born. Experiment 3 corresponds to a composition of the present invention in which trimer acid

  Empol 1040 is used as a stabilizing agent.

  The apparent viscosities are measured at 3 and rpm of each of the liquid DLVA compositions as shown in Table 1. The results

  obtained are also shown in Table 1.

  According to the results reported on the

  1, we reach the following conclusions: - the incorporation of 0.1% of aluminum stearate

  in a formula containing 2% of Pharmagel H in the Ex-

  Perience 2 (control) leads to an increase in apparent viscosity compared to Experiment 1

  moin). the incorporation of 0.2% of Empol 1040 trimer acid in a formula containing 2% of Pharmagel H. Experiment 3 (invention) leads to a significant increase in apparent viscosity relative to

  to both Experiments 1 and 2.

TABLE 1

  Brookfield Viscosity Experience Composition (1) HATD, 20 rpm

1 H20 = 41.10%

  (control) Monostearyl phosphate = 0.16% Stabilizer = 0% Phannagel. = 2.0%

2 H20 = 41.0%

  (Control) Monostearyl Phosphate = 0.16% o000 Aluminitumn Stearate = 0.1% Pharmnnagel H = 2.0%

3 H20 = 41.0%

  (Invention) Monostearyl phosphate = 0.16% il 000 Empol 1040 = 0.2% Pharmaqel H = 2.0%

  1) Measured with an N 4 pin after three minutes

  at 20 rpm on 24 hour samples.

EXAMPLE 2

  The liquid liquid DLVA composition is prepared

  xotrope in the following gel by simply mixing the

  ingredients in the order they are listed.

  % by weight Deionized water 42.983 Color 0.007 Clay 1,000 Glass H (1) 0.120 Sodium salt of trimer acid 0.200 Empol 1040 Dowfax 3B-2 (2) 0.800

LPKN-158 (3) 0.160

  Caustic soda solution 2,400 (50% NaOH) Sodium carbonate (anhydrous) 6,990 Sodium silicate, 47.5% solution 13,730 ratio Na20: SiO2 = 1: 2,4 Sodium tripolyphosphate 24,000 Sodium hypochlorite solution 7.610 (11% active chlorine), 000 (1) Glass H is a linear polyphosphate containing about 26 phosphate groups, (2) Dowfax 3B-2 is a 45% aqueous solution of monodecyl / didecyl- (diphenyl) disulfonate oxide

sodium.

  (3) LPKN-158 is an anti-foaming agent consisting of a

  mixture at a 2: 1 molar ratio of

  and di (C1-C18) alkyl of phosphoric acid.

  In order to compare the stability

  of the composition, similar compositions are prepared

  in which the sodium salt of the trimeric acid Empol 1040 is omitted or replaced by alumina stearate or stearic acid. The compositions are tested to determine the

  percentage that separates from the solution by sedimenta-

26195 74

  after six weeks of rest at 37.8 C and after

  rest for six months at room temperature (20 C).

  The results obtained are reported below on

Table 2.

TABLE 2

  in weight Stability on Stability on% by weight of stabilizer 6 weeks 6 months

(37.8 C) (20 C)

  No stabilizer (1) - 8.0 7.0 Aluminum stearate 0.20 0.0 0.0 Stearic acid 0.20 0.0 0.0 (1) 100% complete by adjusting the amount of 'water. In order to determine the effect exerted by the amount of clay used in the composition, the above composition is prepared, using 0.2%

  sodium tartrate and by varying the proportion

  clay content between 0.5 and 2.0%, the results

  States obtained are reported below in Table 3.

TABLE 3

  % by weight (l)% by weight of salt Stability on Stability on 6 weeks sodium clay 6 months Errmpol acid 1040 (37.8 C) (20 C) 0.50 0, 20 t 1.0 1.0

0.75 0.20 1, O 1.0

1.00 0.20 0.0 0.0

1.25 0.20 0.0 0.0

1.50 0.20 0.0 0.0

1.75 0.20 0.0 0.0

2.00 0.20 0.0 0.0

2.00 - 8.0 7.0

  (1) 100% complete by quantity adjustment

S05 of water.

  The results reported in Table 3 show that the addition of a small amount of salt

  Sodium Trimer Acid Empol 1040 makes it possible to

  hold substantially identical stability effects

  or better by using smaller quantities of

gile.

EXAMPLE 3

  The liquid thixotropic DLVA product is prepared

  next gel by simply mixing the ingredients

  in the order in which they are listed.

  Amount,% by weight Sodium silicate (13.74 solution 47.5% Na 2 O: SiO 2 = 1: 2.4) Monostearyl phosphate 0.16 Dowfax 3B-2 0, 36 Thermphos NW 12.0 Thermphos N hexa 12.0 Enpol calcium salt 1040 0, 2 Sodium carbonate anhydrous 5.0 Sodium hydroxide solution (50% of 2.40 NaOH) Pharmagel H 1.0 Sodium hypochlorite solution 1.0 (11.1% )

Water the complement.

  Minor proportions of perfume, dye, etc. can also be added to the composition.

  The composition is tested and

  it is stable and has good

thixotropic tees.

EXAMPLE 4

  Following the procedure of Example 2, formulations are prepared using the dimers of a C18 unsaturated fatty acid, as such, and the K and Na salts of the trimers of a C18 unsaturated fatty acid and the Al, Zn, Ca and Mg salts of the trimers of a

  unsaturated C18 fatty acid, and formulas are obtained.

  have good rheological and

xotropiques.

EXAMPLE 5

  The procedure of Example 2 is followed and a formulation is prepared in which about 1% of the glucose oxidase enzyme is used in place of the bleaching hypochlorite and using the trimer ammonium salt. unsaturated C18 fatty acid stabilizer. We put the formulations to

  the test and we see that they have good

  rheological and thixotropic properties.

EXAMPLE 6

  The procedure of Example 2 is followed and formulations are prepared using the sodium salt of adipic acid and the disodium salt of

  azelaic acid, respectively, as stabilizers.

  The formulations are tested and found to have good rheological and

thixotropic.

  In addition to the superior characteristics of physical stability, thixotropy and performance

  of cleaning, the present invention offers the

  the added benefit of not imposing any order

  of particular addition of the respective ingredients.

  All ingredients can be added in any

  what order or at the same time in a single

  dron, mixer or other, and stirred until

  uniform homogeneous mixture. The mixing operation can be carried out at room temperature or at elevated temperature. It is not necessary to premix any of the ingredients, nor to use

  mixing conditions under different shears.

Claims (30)

  An aqueous thixotropic liquid composition comprising a clay as thixotropic agent, at least one polycarboxylic acid or a metal or ammonium salt of such acid, as a stabilizer, in one   effective amount for increasing the viscosity   rent and physical stability of the composition, water and at least one additional ingredient chosen   among organic detergents, modifying agents   pH, bleaching agents, enzymes, detergency builders, sequestering agents,   foam inhibitors and mixtures thereof.   2. Composition according to claim 1, characterized in that the polycarboxylic acid is a dimer or trimer of an unsaturated fatty acid in C8-C22   3. Composition according to claim 1, characterized in that the stabilizer comprises a salt   of monovalent metal or ammonium of a dimer or tri-   mother of an unsaturated C8 to C22 fatty acid.   4. Composition according to claim 1, characterized in that the stabilizer comprises a polyvalent metal salt of a dimer or trimer of a C to C22 unsaturated fatty acid. 5. Composition according to claim 1, characterized in that the stabilizer is present in   an effective amount of about 0.001 to 1% by weight.   6. Composition according to claim 1, characterized in that the stabilizer is present in   an effective amount of about 0.01 to 0.5% by weight.   7. Method for cleaning dishwashing equipment   characterized in that it consists in putting the   dirty dishes placed in an automatic dishwasher   tick, in contact with an aqueous wash bath in   which is dispersed an effective amount of the position according to claim 1.   A process for improving the stability of a gel-like aqueous thixotropic composition containing a small but effective amount of a clay-type thixotropic agent, characterized in that   it consists in including in the composition a quantity   stabilizing effect of a dimer or trimer of a C8 to C22 unsaturated fatty acid or a metal salt or ammonium of this acid.   9. Thixotropic aqueous composition for washing   automatic dishware, comprising approximately, by weight; (a) 5 to 35% alkali metal tripolyphosphate; (b) 2.5 to 20% sodium silicate; (c) 0 to 9% alkali metal carbonate;   (d) 0.1 to 5% organic detergent material   persistant in water and stable against chlorine bleach;   (e) 0 to 5% styrofoam stably   chlorine bleach screw;   (f) a chlorine bleaching agent in one   portion capable of providing about 0.2 to 4% of active chlorine; (g) a thixotropic thickener in a proportion sufficient to impart a thixotropic index of about 2 to 10 to the composition; (h) 0 to 8% sodium hydroxide; (i) a dimer or trimer of a C8 to C22 unsaturated fatty acid as a physical stability agent in one   effective proportion to increase the viscosity   rent and to increase the physical stability of the composition; and (j) the additional water.   10. Composition according to claim 9,   characterized in that the polycarboxylic acid used   se as physical stability agent (i) is present   in a proportion of about 0.01 to 0.5%.   11. Composition according to claim 9,   characterized in that the polycarboxylic acid used   se as physical stability agent (i) is present   in a proportion of about 0.05 to 0.2%.   12. Composition according to claim 9, characterized in that the polycarboxylic acid is chosen from dimers and trimers of fatty acids. unsaturated C16 to C20.   13. Composition according to claim 1,   characterized in that the polycarboxylic acid take adipic acid.   14. Composition according to claim 1,   characterized in that the polycarboxylic acid take azelic acid.   15. Composition according to claim 9, characterized in that the proportion of clay thickener is in the range of about 0.1 to 2.5% by weight.   16. Thixotropic aqueous composition for   automatic dishwasher comprising, approximate   by weight: (a) 5 to 35% of alkali metal tripolyphosphate; (b) 2.5 to 20% sodium silicate; (c) 0 to 9% alkali metal carbonate; (d) 0.1 to 5% of a water-dispersible organic detersive material stable to the chore-bleaching agent;   (e) 0 to 5% styrofoam stably   chlorine bleach screw;   (f) a chlorine bleaching agent in one   portion capable of providing approximately 0.2 to 4% of available chlorine   tif; (g) a thixotropic thickener in a proportion sufficient to impart a thixotropic index of about 2 to 10 to the composition; (h) 0 to 8% sodium hydroxide;   (i) a monovalent metal salt of a dimer or trimer   mother of a stabilized C16 to C20 unsaturated fatty acid, in an effective proportion to increase   the apparent viscosity and increase the phy- the composition; and (j) the additional water.   17. Thixotropic aqueous composition for washing   automatic dish comprising, approximately, by weight: (a) 5 to 35% of alkali metal tripolyphosphate; (b) 2.5 to 20% sodium silicate; (c) 0 to 9% alkali metal carbonate;   (d) 0.1 to 5% of organic detergent material,   persistant in water; (e) 0 to 5% foam inhibitor; (f) a thixotropic thickener in a proportion sufficient to impart a thixotropic index of about 2 to 10 to the composition; (g) 0 to 8% sodium hydroxide; (h) a monovalent metal or ammonium salt of a dimer or trimer of a C16 unsaturated fatty acid to   C20 as a stabilizing agent, in an effective proportion   to increase the apparent viscosity and increase   the physical stability of the composition; and (j) the additional water.   18. Composition according to claim 16, characterized in that the monovalent metal salt comprises a metal of Group IA of the Periodic Table.   Elements and is present in a proportion of about 0.01 to 0.5% by weight.   19. Composition according to claim 18, characterized in that the monovalent metal salt comprises an alkali metal.   20. Composition according to claim 18,   characterized in that the monovalent metal salt comprises   takes a metal chosen between Na and K. 21. Composition according to claim 20, characterized in that the monovalent metal salt is present in a proportion of about 0.05 to 0.2% by weight. 22. Composition according to claim 16, characterized in that the proportion of clay thickener is in the range of about 0.1 to 2.5% by weight.   23. Thixotropic aqueous composition for   automatic dishwashing machine comprising, approximate by weight:   (a) 5 to 35% of alkali metal tripolyphosphate   linen; (b) 2.5 to 20% sodium silicate; (c) 0 to 9% alkali metal carbonate; (d) 0.1 to 5% organic detergent material, water dispersible, stable to chlorine bleach;   (e) 5% to 5% stable foam inhibitor   chlorine bleach screw;   (f) a chlorine bleaching agent in one   portion capable of providing about 0.2 to 4% of active chlorine; (g) a thixotropic thickener in a proportion sufficient to impart a thixotropic index of about 2 to 10 to the composition; (h) 0 to 8% sodium hydroxide;   (i) a polyvalent metal salt of a dimer or trimer   of a C16 to C20 unsaturated fatty acid as a physical stability agent, in an effective proportion to   increase the apparent viscosity and increase the   physical bility of the composition; and (j) the additional water.   24. Composition according to Claim 23,   characterized in that the polyvalent polyvalent metal salt   take a chosen metal in any of the Groups   IIA, IIIA, IVA, VA, VIA, VIIA, IB, IIB, IIIB, IVB, VB,   VIB, VIIB and VIII of the Periodic Table of the Elements and is present in a proportion of about 0.01 to 0.5% in weight.   25. Composition according to claim 24, characterized in that the polyvalent metal salt is chosen from the salts of Mg, Ca, Ti, Zr, V, Nb, Fe, Co, Ni, Cd, Sn, Sb, Bi, Al and Zn.   26. Composition according to claim 23,   characterized in that the polyvalent polyvalent metal salt   take a chosen metal in any of the Groups   II, III or IV of the Periodic Table of the Elements.   27. Composition according to claim 26, characterized in that the polyvalent metal salt is   selected from aluminum, zinc, calcium and magnesium.   28. Composition according to claim 26, characterized in that the polyvalent metal salt is present in a proportion of approximately 0.05 to 0.2% by weight. weight.   29. Composition according to claim 23, characterized in that the proportion of clay thickener is in the range of about 0.1 to 2.5% by weight.   30. Process for improving stability   of a thixotropic aqueous composition in gel containing   a small, but effective, amount of clay as a thixotropic agent, characterized in that it comprises including in the composition a stabilizing effect amount of a polyvalent metal salt of a dimer or trimer of an acid unsaturated fatty acid C16 to C20, the metal salt being chosen from the salts   aluminum, zinc, calcium and magnesium.