US3468803A

US3468803A - Dishwashing compositions

Info

Publication number: US3468803A
Application number: US542449A
Authority: US
Inventors: Kenneth W Knapp; John S Thompson
Original assignee: FMC Corp
Current assignee: FMC Corp; Olin Corp
Priority date: 1966-04-14
Filing date: 1966-04-14
Publication date: 1969-09-23
Anticipated expiration: 1986-09-23

Description

(4) A sodium silicate having an Na O United States Patent US. Cl. 252-106 Claims ABSTRACT OF THE DISCLOSURE Germicidally active dishwashing compositions containing chlorinated trisodium phosphate, a low foaming nonionic surfactant and sodium silicate are rendered noncorrosive to silverware by incorporation of cyanuric acid and/or alkali metal and alkaline earth metal salts of cyanuric acid. 1

This invention relates to deter-gent compositions containing chlorinated trisodium phosphate for use in dishwashing machines, and particularly to such compositions which do not corrode silverware.

Dishwashing compositions have been developed which have the requisite dissolving rate, water softening ability, avoidance of excessive foaming and ability to clean effectively without corroding silverware and metal dishwasher parts.

Such compositions generally are not active against harmful bacteria and germs, however, and it is desirable to incorporate in them an ingredient which provides a germicidal effect. Chlorinated trisodium phosphate is an active chlorine compound which has the desired ability to attack harmful bacteria, and in addition it is compatible with typical dishwashing compositions having the above properties. However, it has the very serious disadvantage that when used in combination with the other components of such typical dishwashing compositions, it causes the overall composition to attack and corrode silverware.

Use of the otherwise desirable, germicidally active,

Ingredient (1) Clorinated trisodium phosphate- Amount From about to about 60%,

pgeferably about to about 4 From about 0.5 to about 3%,

preferably about 1 to about (3) Low foaming surfactant having From about 0 to about 4%,

the properties of defoaming food preferably about 1 to about soils and compatibility with chlo 3%. rinated trisodium phosphate.

From about 15 to about 45%,

to SiO; ratio of about 1:3.25 to 2:1 preferably about 15 to about and a water content of about 0 to 30%.

207. (5) A polyphosphate having an From about to about 55%,

(2) Cyanurie acid or salt or mixtures thereof.

Nit tO grlK O to P 0 ratio of about preferably about to 50%.

(6) An alkaline builder, usually From about 0 to 50%, prefersodium hydroxide or soda ash or ablyOto mixtures of these.

(7) An inert filler, usually sodium chloride or sodium sulfate, or mixtures of these components.

Essentially the rest, usually from about 10% to about In this specification and in the appended claims, all percentages and parts are given on a weight basis.

Additional ingredients commonly employed in dishwashing compositions may be incorporated with these essential constituents. For example, in the case of a tablet, the formulations contain a further component, namely about 0.1 to about 1%, and preferably about 0.5% of a tableting binder.

Solutions resulting from addition of the compositions to water have a pH of from about 10.5 to about 12.5 at 1% concentration. These preparations are normally used in dishwashing at a concentration of about 0.3 to 0.4%.

The first five constituents in the above table are necessary, and cooperate to give the unique combination of desirable properties possessed by the dishwashing compositions of our invention. In use in the aqueous medium to which the composition is added to effect cleaning of dishes in a dishwasher, the chlorinated trisodium phosphate provides active chlorine which is an excellent sanitizer and germicide and aids in the cleansing action of the composition. The presence of this chlorinated compound, however, in the absence of the cyanuric acid or cyanuric acid salt would attack and corrode silverware being washed with the composition. In the presence of our cyanuric acid or salt thereof, the compositions do not noticeably attack silverware.

The chlorinated trisodium phosphate which is employed in our compositions is readily available, and is normally supplied in crystal form. It is often assigned the empirical formula '(Na PO -11H O) NaOCl, and normally contains about 3.5 to 4% of available chlorine. Its particle size is not critical; the only limitations on the particle size of this and the other ingredients of our compositions are practical limitations, and generally these ingredients have particle sizes of about 20 to 270 US. Standard Series mesh. Particles above about 20 mesh in size sometimes have a tendency to segregate from granular compositions, and furthermore cause difficulty in dissolution and disintegration of the product in use. Part-icles having a particle size below about 270 mesh sometimes tend to cause dustiness in granular products and formation of non-uniform tablets when they are used in tablets.

The cyanuric acid or cyanuric acid salt as noted improves the composition by protecting against attack on silverware. This ingredient may be the acid itself, or it may be an alkali metal or alkaline earth metal salt of the cyanuric acid. Since only about 0.5 to 3% of the material is employed in the compositions, and the compositions are used in dishwashing at very high dilutions at which all of these salts dissolve, the factor of degree of solubility of the salt is not of substantial importance. It is nevertheless preferred to employ the relatively soluble cyanuric acid itself, or the likewise soluble sodium or potassium cyanurates. Mixtures of this cyanuric acid and its salts as well as of various such salts obviously are also useful in our compositions and reference to cyanuric acid or a salt thereof in this specification and in the appended claims encompasses such mixtures,

The nonionic surfactant component results in a composition high in food soil defoaming power, that is, a composition which has little or no tendency to foam by itself or in the presence of a foam-producing food soil. Use of such compositions is well known and is practiced generally in the trade. The nonionic surfactant employed must have a combiantion of three properties:

(1) it must be a low foaming material,

(2) it must be capable of defoaming proteinaceous food soils such as milk, egg whites, etc.,

(3) it must be compatible with chlorinated trisodium phosphate, that is, it must not decompose this chlorinated compound markedly in the formulation.

Nonionic surfactants which meet these requirements include the lower alkyl ethers of polyoxyethylated octylphenols such as those under the Triton CF trade name, for example Triton-CF-54 which is the butyl ether of polyoxyethylated octylphenol; water soluble benzyl ether of octylphenol condensed with ethylene oxide sold by Rohm and Haas Company under the Triton CF-10 designation; polyoxyalkylene glycols having a plurality of alternating hydrophobic and hydrophilic polyoxyalkylene chains, the hydrophilic chains consisting of linked oxyethylene radicals and the hydrophobic chains consisting of linked oxypropylene radicals, said product having three hydrophobic chains linked by two hydrophilic chains, the central hydrophobic chain constituting 30% to 34% by weight of the product, the terminal hydrophobic chains together constituting 31% to 39% by weight of the product, the linking hydrophilic chains together constituting 31% to 35% by weight of the product, the intrinsic viscosity of the product being from about 0.06 to 0.09 and the molecular weight of the product being from about 3000 to 5000, all as described in US. Patent 3,048,548; and the alkyl polyoxyalkylene ether alcohols based on straight chain biodegradable hydrophobic segments, for example Petrolite H-0307-S.

Other nonionic surfactants are suitable for use in the herein dishwashing preparations and it is not intended to exclude any surfactant possessing the above properties. Omission of the surfactant results in a formulation which lacks the ability to suppress the foam produced by food soils.

Sodium silicates of commerce having particle sizes of from 230 to 2000 microns are used in the production of granular preparations. Such particle size sodium silicates or fines can be used in the production of tablets. The incorporation of fines, i.e. material having a particle size of 74 microns or less, or such that substantially all of the material passes through a 200 mesh sieve (United States Standard Series), should not be used in the preparation of the granular products because such sodium silicate fines tend to produce an unstable product from the standpoint of loss of available chlorine on storage. Surprisingly, we have found that in the production of a tablet, the use of sodium silicate fines, i.e. having an average particle size of 74 microns or less, results in a product of markedly improved stability as compared with a similar tablet in which sodium silicate granules are used.

Sodium silicates useful in the herein preparations are those having an Na O to Si ratio of about 12325 to 2:1, and containing about 0 to 20% of water. Typical silicates falling within this definition are anhydrous sodium metasilicate, which is preferred for use herein; GD silicate which is a product having an Na O to Si0 ratio of 1:2 and typically available at a water content of 18.5%; and, G silicate which has an Na O to SiO ratio of 113.22 and frequently containing 18.5% of water.

The sodium silicate in the preparation serves as a detergent builder, i.e. enhances the cleansing action, and results in a preparation which when dissolved produces a solution having a pH which is more alkaline than would be the case if the sodium silicate were not employed. As is well known, the more alkaline the solution, the better the cleansing action, as a general rule. Also the sodium silicate acts as a corrosion inhibitor for metal parts of the dishwashing machine.

The polyphosphate functions as a water softener and a detergent builder. Polyphosphates of commerce, and having an Na O or K 0 to P 0 ratio of about 1:1 to 2:1 can be used. Typical polyphosphates of this kind are the preferred sodium tripolyphosphate, sodium hexametaphosphate and sodium pyrophosphate, as well as the corresponding potassium polyphosphates. The particle size of the polyphosphate is not critical. Any of the finely divided products readily available can be employed.

Inert fillers employed in our compositions may be sodium sulfate, sodium chloride, borax or the like materials ordinarily used as fillers in dishwashing compositions, so

long as such fillers are inert to our chlorinated trisodium phosphate. Alkaline detergency builders, for example soda ash (sodium carbonate) in any finely divided form, which aids in formation of an alkaline solution when the preparation is dissolved in water, or sodium hydroxide may also be used.

Any of the tableting binders of commerce which are inert in our compositions can be used in the formation of tablets These binders are added to give a strong tablet, which will not disintegrate in storage. Desirably the tableting binder used has lubricating properties so that its incoropration results in the diminished wear of the dyes of the tableting machine. A preferred binder is Sterotex which is a powdered vegetable fat. In a typical manner of preparing our compositions, the sodium silicate, the nonionic surfactant, the filler, the cyanuric acid or salt, the polyphosphate and the tableting binder, if used, are blended in the order mentioned in any suitable mixing apparatus. After the formation of a uniform blend of these components, the chlorinated trisodium phosphate is added to this blend and uniformly distributed throughout it. This blending procedure minimizes contact of the chlorinated trisodium phosphate with a nonionic surfactant during the blending, with consequent improved stability of the product.

An additional ingredient which sometimes is employed in these compositions is a mineral oil (white oil) which alleviates product dustiness during mixing and handling; a level of 0.1 to 0.5% of this ingredient is suitable.

In forming tablets the blended mixture prepared as described above is tableted in any available tableting machine under a tableting pressure of on the order of 1,000 to 15,000 lbs. Tablets of any desired size and shape can be provided. Disc-like tablets having for example a weight of about 12 grams each, a diameter of 30 mm. and thickness of 12 mm. are very useful. In this specification and the attached claims reference to compositions includes reference to tablets, which upon being dissolved in an aqueous dishwashing medium provide identical end use results with a granular composition.

The following examples are presented by way of illustration only and are not to be considered as limiting the scope of our invention in any way.

EXAMPLE 1 Component: Percent Chlorinated trisodium phosphate 32.5 Sodium cyanurate 1.4 Sodium tripolyphosphate 40 GD silicate 1 17 Triton CF-54 2 1.5 Sodium sulfate 7.6

Percent available chlorine 1.1

pH 0.35% aqueous solution 11.1

{GB Silicate 1s a sodium silicate havin an Na 0 to S10 ratio of 1 2 and a typical Water content o f 18.5% 2

EXAMPLE 3 Component: Percent Chlorinated trisodium phosphate 32.5 Potassium cyanurate 1.4 Sodium tripolyphosphate 40 GD silicate 17 Triton CF-54 1.5 Sodium sulfate 7.6

Percent available chlorine 1.1 pH 0.35 aqueous solution 11.1

COMPARATIVE EXAMPLE A Component: Percent Chlorinated trisodium phosphate 32.5 Sodium tripolyphosphate 40 GD silicate 17 Triton CF-54 1.5 Sodium sulfate 9 Percent available chlorine 1.1 pH 0.35 aqueous solution 11.1

The constituents of the compositions of the above examples were blended in the following order. The silicate was first introduced into the mixer followed by the surfactant, the cyanuric acid compound, the filler (sodium sulfate or sodium chloride) followed by the sodium tripolyphosphate and then the chlorinated trisodium phosphate.

EXAMPLE 4.TABLET The composition of this Example 4 was blended in the same fashion as was the composition of Example 1, with the exception that a tableting binder (Sterotex) was added just prior to the chlorinated trisodium phosphate. The blended mixture was pressed at 2,000 lbs. in a Carver laboratory press to form the tablets, each weighing 12 grams and having a diameter of 30 mm. and a thickness of 12 mm.

In order to compare the effect of these compositions on silverware, Rogers 1847 silverplate flatware pieces were immersed in 0.35 solutions of the above compositions and held at 130 F. for 24 hours. The granular compositions of our invention, namely compositions 1 through 3, and our tablets of Example 4 showed no adverse efiect on the silverplate samples. The comparative composition, namely the composition of Example A, on the other hand discolored the silverplate badly. This corrosion was evidenced by severe blackening of the silver.

The granular compositions of Example 1 to 3 and the tablets of Example 4 also were used to wash dishes in a home automatic dishwasher, and proved to be highly 6 effective in cleansing without damage to the dishes or silverware being washed.

Pursuant to the requirements of the patent statutes, the principle of this invention has been explained and exemplified in a manner so that it can be readily practiced by those skilled in the art, such exemplification including what is considered to represent the best embodiment of the invention. However, it should be clearly understood that, within the scope of the appended claims, the invention may be practiced by those skilled in the art and having the benefit of this disclosure, otherwise than as specifically described and exemplified herein.

What is claimed is:

1. A germicidally active dishwashing composition which is non-corrosive to silverware, containing as its essential constituents from 15 to 60% by weight of chlorinated trisodium phosphate, from 0.5 to 3 by weight of a cyanuric compound from the group consisting of cyanuric acid, alkali metal and alkaline earth metal salts of cyanuric acid and mixtures of these cyanuric compounds, from 0.5 to 4% by weight of a low-foaming nonionic surfactant capable of defoaming proteinaceous matter compatible with chlorinated trisodium phosphate, from 15 to 45% by weight of a sodium silicate having an Na 0 to SiO ratio of 1:325 to 2:1 and a water content of 0 to 20%, from 25 to 55% by weight of polyphosphate from the group consisting of sodium and potassium polyphosphate having an R 0 to P 0 ratio of 1:1 and 2:1 wherein R is sodium or potassium, and any balance of the com position comprising an inert filler.

2. The dishwashing composition of claim 1 in which the chlorinated trisodium phosphate is present in the amount of 20 to 40%, the cyanuric compound is present in the amount of l to 2%, the low-foaming nonionic surfactant is present in the amount of 1 to 3%, the sodium silicate is present in the amount of 15 to 30%, and the polyphosphate is present in the amount of 30 to 50%.

3. The composition of claim 1 in which the cyanuric acid compound is cyanuric acid.

4. The composition of claim 1 in which the cyanuric acid compound is sodium cyanurate.

5. The composition of claim 1 in which the filler is sodium sulfate or sodium chloride.

6. The composition of claim 1 in which there is present up to 50% of an alkaline builder.

7. The composition of claim 6 in which alkaline builder is soda ash, sodium hydroxide or a mixture of soda ash and sodium hydroxide.

8. The composition of claim 1 in which the polyphosphate is sodium polyphosphate.

9. The composition of claim 1 in granular form.

10. The composition of claim 1 which contains also 0.1 to 1% of a tableting binder, and in which the composition is in tablet form.

References Cited UNITED STATES PATENTS 2,988,471 5/ 1961 Fuchs et al. 212.5 X 3,314,891 4/ 1967 Schmolka et al. 252 3,255,117 6/ 1966 Knapp et a1. 252-99 LEON D. ROSDOL, Primary Examiner P. E. WILLIS, Assistant Examiner US. 01. X.R.