US 3755181 A
Borax forms 1-2-glycol borate esters that are excellant chelating agents in alkaline detergent formulae. These borate esters are used as a replacement for the conventional prior art sequestering phosphates in novel detergent compositions, in order to reduce the danger of eutrophication from the waste waters.
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United States Patent [191 Henricks 1 Aug. 28, 1973 DETERGENT COMPOSITION CONTAINING 1-2 GLYCOL BORATE ESTER  Inventor: John Arthur Henricks, 742 N. Oak
Park Ave., Oak Park, 111. 60302 221 Filed: Mar. 15, 1971 211 App]. No.: 124,492
 US. Cl 252/156, 44/76, 252/135, 252/175, 252/180, 252/181, 260/234 R  Int. Cl. ..G1ld 7/06,G11d 7/12  Field of Search 252/156, 135, 175, 252/180, 181; 260/234 R; 44/76 [56} References Cited UNITED STATES PATENTS 3,062,878 11/1962 Karabinos et a1 252/180 X 3,039,970 6/1962 Krueger et a1. 252/156 X 3,539,464 11/1970 Harper et a1 252/156 X 3,539,463 11/1970 Harper et a1 252/156 X Primary Examiner-Mayer Weinblatt  ABSTRACT 1 Claim, No Drawings DETERGENT COMPOSITION CONTAINING l-2 GLYCOL BORATEESTER This invention relates to alkaline cleaning compositions, and is addressed to the use of 1-2- dihydroxy glycol borate'esters as chelating agents for use therein.
It has been found that the widely used phosphate containing detergents are dangerous pollutants in waste water because they are nutrients that cause a proliferation of algae. As a result, the phosphates have been severely restricted by most pollution control agencies.
The action of polyphosphates in laundry cleaning is most valuable because they help to eliminate the tattle-tale gray deposits on fabrics that was a characteristic of early prior art detergents. It is believed that this major cleaning improvement was brought about by the property of the polyphosphates of sequestering heavy metals. This sequestration works both to prevent deposition of insoluble soaps formed with heavy metals and the fatty acids formed by the saponification .of oil and grease in the soil; and to prevent the precipitation'of dark metal hydroxides into the cloth. It will be recalled that the standard laundry test cloths are prepared with a soil containing oil and manganese dioxide. When a chelating agent ties up heavy metal ions, its eliminates the precipitation of soap curds and discoloring heavy metal hydroxides. The presence of chelatingagents in a detergent enhances both the detergency and the brightening action of these cleaning compositions.
l have found that the 1-2- glycol borate esters can be sucessfully used as replacements for the conventional phosphates in detergent compositions. This replacement not only maintains the high level of cleaning of the phosphated compositions at no increase in the chemical cost but it also eliminates the dangerous eutrophication of the waste water. Since the borates are slightly antiseptic, and since the glycols and sugars are readilly biodegradable; there is no eutrophication'danger in this novel replacement.
The l-2- glycol borate esters are unique in that they form their own chelate structure when the 1-2- glycol and the borate are merely dissolved in water. This unique property of the borates was first utilized for an accurate determination of boric acid. In 1893,R.T. Thompson used glycerine to make a titration of the very weak boric acid possible (Jour.Soc.Chem.lnd. Xll,pg.432, 1893 Later L.C. Jones (Amer..lour.- Science pg.l47, 1898) improved the Thompson method by the substitution of mannitol for glycerine in the boric acid analysis which is still the preferred method. The phenomena involved in one by which the l-2-glycol dihydroxy groups coordinate with with two of the three acid hydroxy groups of the boric acid to make the third boric acid hydroxy a strong enough monobasic acid to be titrated by a strong alkali base with a phenolphthalein indicator. Boeseken later studied this phenomena by measuring'the' increased conductivity imparted to the weak boric acid by coordination with various l-2-glycols (Ber. 46,pg'.26l9, 1913 Because of the unique in situ formation of these borate ester chelates, the compounder has a wide choice in his source of l-2-dihydroxy compounds, and a wide choice of proportions in which to mix them. While each borate anion requires two l-2-dihydroxy glycol groups for coordination any excess glycol imparts a helpfull solvent action and a coupling action to the detergent composition.
THere is a simpler method than the Boeseken electrical conductivity technique to determine the formation of ]-2-glycol borate'esters. This can be done by a sim ple solution pH measurement, for which even pH papers are adequate. For example, a 0.1 molar borax solution has a pH of about 9.5; but when 0.2 molar glucose is added to such a solution to form the I-Z-glycol borate ester, the pH falls to about 7.7 pH. Since glycol borate ester formation lowers the normal borax pH almost 2.0 units, a cheap source of alkali such as caustic soda or soda ash is usually compounded into these novel detergents as a source of added alkalinity for heavy duty cleaning. Table l which follows includes the pH shifts when divalent metal salts react with alkali builders, with borax, and with the l-2-glycols which esterify the borax.
Generally, we must furnish two dihydroxy linkages for every active boric acid radial. Using borax Na B- O-,l0 H O we find by titration that the salt acts like two boric acids, and it requires four l-2-glycol dihydroxys for each borax molecule. We were surprised to find that the glucose molecule offers two adjacent dihydroxy sites for borate-glycol ester formation. These are believed to be the same two dihydroxy sites that Emil Fischer, in 1895, showed would add on acetone to form the di-acetone glucose compound that he used to elucidate the ring structure of glucose.
With such a wide spectrum of l-2-diglycols that are now commercially available, the dihydroxy donor molecule is selected on the basis of both cost and biodegradability. Glucose and the equivalent saccharides are the preferred glycol source because of their low cost and high biodegradability. The ready biodegradability of the sugars could lead to an increased biological oxygen demand in the effluent were it not for the mild bacteriostatic action of the borax. it may even be, at times, advisable to mix the sugar borate esters with ethylene glycol borate esters to obtain more inhibitory activity in the borate ester chelating agents.
One problem in the use of polyhydroxy organic compounds lies in their extreme hydroscopicity that causes them to be the preffered humectants in industry. This moisture pick-up however, causes any detergent using them to cake up badly in the package so that it becomes difficult to pour the powder from the container in measured ammounts. Two methods can be used to obtain a free flowing detergent containing the polyhydroxy compounds that form borate ester chelating agents. The simplest method is to use anhydrous glucose and coat the grains with a film of starch, airfloated silica, fine chalk, or amorphous calcium silicate by tumbling the glucose with the coating powder. The coated glucose or other polyhydroxy powder is then used as a component of the detergent blend that is mixed in a commercial powder blender to form a homogeneous free flowing mixture.
Another technique to overcome the caking tendancy of the polyhydroxy organic compounds begins with thermally dehydrating the borax to the intumesced pyroborate, and grinding the pyroborate to a anhydrous powder. This fine dehydrated powder is then slurried into a hot liquid glycol, glycerine, or sorbitol; and the resultant slurry then sprayed from a soap powder drying tower. As an added precaution, the spraydried borate ester grains could then be coated in the same manner as the anhydrous glucose, and the coated ester then powder blended into the detergent formulation. Obviously, no such precautions need to be taken when using the l-2-glycol borate esters as chelants in a liquid detergent. When formulating a liquid detergent, certain syrupy or viscous high molecular weight l-Z-glycols can be utilized which would not be suitable in a powder, but which could have good coupling or emulsifying action. Certain glyceryl or sorbitol ethers and esters used commercially in urethane forms for example, could be used in a light duty liquid detergent, as could the sucrose acetates.
The numerous l-2-glycols that form borate esters can be evaluated in a simple manner. A 0.1 molar solution of calcium chloride is used as a prototype hard water component. The 0.] molar calcium chloride is treated with an equal volume of 0.2 molar sodium hydroxide solution to precipitate the calcium as hydroxide. An equal volume of 0.1 molar borax solution is then added to the solution of sodium hydroxide treated calcium chloride. The borax coagulates and precipitates the dipersed calcium hyroxide formed in the first reaction, appearantly as the calcium borate since the solution pH is above that of borax to indicate some sodium hydroxide regeneratiomThe chelation valve of the 1-2-glycol is then measured by dissolving the thus precipitated calcium salts by a 0.4 molar solution of the l-2- diglycol, with carefull stirring. In the case of the saccharides with two active l-2-dihydroxy sites, only 0.2 molar solutions are required. The evaluation of various common and available l-2-glycol sources is shown in the following table.
in mild alkali; and even some sacharinic acid in strong alkali. Although the literature reports the formation of borate esters with salycilic, tartaric, and lactic acids, these compounds are too expensive for wide commercial use.
Since bleaching agents like the perborates are widely used in laundry detergents; the oxidation products of the l-2-glycol selected for use is an important consideration. Here again, the sugars are preferred since their oxidation products like the sacharn'nic acids, gluconic acid, and even lactic acid form chelate compounds by coordination with the borate. The formation of active chelating oxidation products is an important consideration in the operating life of an industrial cleaner.
The compounding of commercial detergent compositions utilizing the l-2-glycol borate ester chelants is illustrated in the following examples. The examples for the Heavy Duty Household Detergent and the Light Duty Household Detergent were derived from examples in the excellant report by Dr.S.J.Silvis entitled The World of Synthetic Detergents Chemical Week Sept. 20th 1969, page 73 The table Typical Synthetic Detergent Formula on page 73 was used to obtain typical formulae which contained sodium tripoly phosphate. In both cases, the glycol borate ester was substituted for the tri-poly phosphate for the example.
Similarly, the three following industrial cleaner examples were derived by substituting the glycol borate esters for the phosphates in proven prior art cleaner formulations.
'IABLE T.-REACTIO N OF CALCIUM CHLORIDE WITII ALKALINE (1' LYCOL BORATE Initial Final pH pH Reaction 5. 7 5. 7 Clear solution. 13. 5 11.5 Cloudy precipitate. 9. 5 10. 3 Heavy precipitate. 10.3 0. 6 Ptecipitate redissolved.
Steps 1, 2, and 3 are repeated to form the calcium precipitate for the evaluation of the following l-Z-glycols The foregoing tests show that the l-2-glycols that form a borate ester in situ with borax by mere solution in water, are very active chelating agents particularly when there are excess hydroxy groups over those used for the coordinate compound. Thus those l-Z-glycols like ethylene or propylene glycol leave 10 to percent of the calcium precipitates undissolved, depending on the solution temperature, concentration, and what other ions are present; while the l-2-glycols with extra hydroxy groups like glycerine, glucose, sorbitol and the saccharides are superior solubilizers for precipitated calcium. Obviously, the sugars and hydrogenated sugars like sorbitol and mannitol make the best borate ester chelants. It was noted that invert sugar was a better solubilizer than plain sucrose, indicating that the glucose and fructose fragments reacted to form the borate more readily than the larger molecule. This characteristic may be advantageous in using these compounds because all sugars tend to rearrange their structure in alkaline media. Glucose, for example forms an equillibrium mixture of glucose, fructose, and mannose Example I Heavy Duty Household Detergent Wetting Agent mixture, principally alkyl benzene Sulfonates 21% l-2-glycol borate ester, (such as Borax 20% 8t coated glucose mixed glucose borate ester 22%) 2% Sodium metasilicate l2% Sodium carbonate l 1% Sodium sulfate 14% Total Example 11 Light Duty Household Detergent Wetting Agent mixture, principally lauryl sulfate ester 30 k l-2-glycol borate ester, such as 12% borax &
15% glucose spray dried from a tower 27 Sodium carbonate l5 Sodium sulfate 28 Total 100% This detergent was used to wash a load of white linens in a domestic automatic washer. The results were equal in both whiteness and brightness to an identical load of white linens washed in the same machine under identical conditions except that the control detergent contained 27 percent sodium tripoly phosphate in place of the 27 percent l-2-glycol borate ester shown above.
Example Ill Industrial Spray Cleaner Low foam non-ionic wetting agent 1.5 Octyl alcohol sulfate 05 Sodium metasilicate 34.0 Sodium carbonate 15.0 l-2-glycol borate ester, such as,- Borax 27% Coated Glucose 22% 49.0% Total 100 The above powder was made up at a concentration of 202. 2-oz./gal. in an industrial spray washer operated at 170 F. and used to clean cold-rolled steel stampings. The cleaning obtained in a two minute pressure spray cycle was excellent.
Example IV Agitated Industrial Soak Cleaner This immersion cleaner was made up to 8 to 10 oz./ gal. and used to clean cold rolled strip stock prior to forming it and welding it into tubing on a Yoder mill.
' The cleaning bath and the rotating cleaning brushes immersed therein were held at a temperature of about 150 F. The strip exited through wringer rolls to remove the cleaning solution; and was found to be clean and free of the soils picked up by the oily steel surface.
Example V Electrolytic Steel Cleaner Sod xylene sulfonate 1% Sodium hydroxide Sodium sulfate l-2-glycol glycol borate ester, such as,
Borax l8 Glucose I9 37 This electrocleaner is made up at a strength of from one to 2 pounds per gal., heated to about 200 F., and the steel work to be cleaned is made anode at about 100 amps.per sq.ft. It is noted that the steel so treated is made bright and clean and free of all smut deposits on the surface.
Another novel way to avoid the tattle tale gray discoloration caused by heavy metal soaps and heavy metal oxides lies in the use of a unique type of heterogeneous soap micelle, peptized to avoid precipitation into fabrics. This novel soap micelle is composed of identical hydrophobic tails"held together by hydrogen bonding;but having a mixture of hydrophilic heads" that hold the soap molecules into the micelle very firmly under adverse conditions.
I have found that a specific soap will not curd out when it is associated with at least equimolar similar tails that are not affected by poly-valent heavy metal salts. For example,if sodium laurate is mixed in a micelle with equimolar lauryl sulfate ester and polyoxyethylated lauryl alcohol having eight to 12 ethoxy groups; the mixed micelle will not precipitate soap. While these stabilized micelle detergents are particularly well suited for cleaning dermal tissues,they are also very effective in industrial use. This novel micelle stability is augmented by the use of the l-2-glycol borate esters,as the following example illustrates.
Example VI Stabilized Soap Micelle Detergent to OQWO 0% 3 8 8 3 3 5 The shorter chain fatty alcohol and fatty acid was used to obtain a higher salt tolerance, in this formula, The example above was found to be a fine laundry detergent for delicate white liners.
We believe that the foregoing examples illustrate the simplest use of the l-2-glycol borate esters in alkaline cleaning compositions. Attention is called to Example IV which contains 20 percent sodium tripoly phosphate,which is still a most valuable cleaner ingredient. The 5 percent phosphorous which this example contains is still well below the 8.7 percent phosphorous content that has been set for an upper limit.
We wish to acknowledge that a strong solution of sucrose will dissolve calcium hydroxide as a calcium saccharide complex and that this step is used to remove the caramel and the protein in sugar refining. We point out that this calcium saccharide complex is not the same as the 1-2-glycol borate ester complex;and that the solubilizing reactions shown in Table 1 cannot be accomplished without the borax.
We have also found that the l-2-glycol borate ester complexes are valuable chelating agents in electroplating baths; but we feel that this usage is sufficiently different from their use in cleaning to warrant a separate patent application.
Although several embodiments of the invention have been herein shown and described,it will be understood that in accordance with the provisions of the patent statutes,numerous modifications of these compositions can be resorted to without departing from the spirit of this invention.
Having thus described my invention, I claim 1. An alkaline detergent composition consisting essentially of water soluble surfactants and alkalinity agents selected from the group consisting of alkali metal hydroxides, carbonates, silicates and mixtures thereof and about 27 percent to about 49 percent of a 1-2 glycol borate ester sequestering agent formed in situ by reacting one mole of borax with two moles of a sugar selected from the group consisting of glucose,su-
crose and invert sugar.