The present invention relates to compositions of matter which are useful for water softening or as detergent builders.
Aluminosilicates which have high calcium and magnesium exchange rates and capacity have been added to water softening and detergent products to remove water hardness. Effective removal of calcium and magnesium ions from water when considered in the context of detergent products is important in that those ions can precipitate anionic surfactants rendering the former less effective in fabric cleaning. Moreover, if the calcium and magnesium ions are not removed from water used for washing, these ions will interact with soils on the fabrics thus interfering with soil removal.
U.S. Patent 3,985,669, issued October 12, 1976, Krummel et al, describes the formulation of a detergent composition containing aluminosilicates and alkali metal silicates. In Krummel et al the silicates are present at a very low level to avoid the interaction with the aluminosilicate. This product is formed by spray drying all of the components in the composition including the aluminosilicate and the alkali metal silicate.
It has been found that the incorporation of the aluminosilcate materials into detergent and water softening compositions described above presents great difficulties. For instance, if aluminosilcates are to be admixed into the composition as a dry material, a considerable quantity of dust can be generated by improper handling of the finely divided aluminosilicate. Moreover, the aluminosilicates per se are not free flowing. It is also noted that if the aluminosilicate materials with which the present invention is concerned are admixed dry with the remainder of a composition, that segregation of the fine aluminosilicate materials will occur during packing and transportation of the finished product. The segregation is extremely undesirable in that when the consumer uses the product the lack of uniformity may result in over-usage or under-usage.
The present invention is an improvement on U.S. Patent 4.096.081, Phenicie et al, issued June 20, 1978. This patent teaches agglomeration of the aluminosilicate particles using an organic agglomerating agent and an inorganic salt. This agglomerate can be admixed with conventional spray-dried detergent granules.
Throughout the specification and claims, percentages and ratios are by weight and temperatures are in degrees centigrade unless otherwise indicated.
A free-flowing particulate water softening composition comprising an intimate mixture of:
- (a) from 60% to 95% by weight of an aluminosilicate detergency builder, selected from the group consisting of:
- (i) an amorphous aluminosilicate;
- (ii) a hydrated crystalline zeolite selected from the group consisting of zeolite A, X, P and mixtures thereof, containing at least 10% of water and having a particle size in the range from 0.1 to 25 micrometers; and
- (iii) mixtures of the amorphous and the crystalline species; said aluminosilicates having a calcium ion-exchange capacity of at least 200 mg CaCO3/g; and a calcium ion-exchange rate of at least 0.034 g CaCO3/i/min/g;
- (b) from 1 % to 4% by weight of synthetic anionic detergent surfactant which is relatively hardness insensitive;
- (c) from 0,5% to 10% by weight of an inorganic salt and being essentially free of silicates; and
- (d) balance water.
The aluminosilicate detergency builder of this invention comprise both amorphous and crystalline aluminosilicates as is well known in the art. U.S. Patent 4.096.081 contains a description of such builders. Zeolites A, X, and P are preferred, with Zeolite A being most preferred.
An essential feature of the ion-exchange builder materials herein is that they be in a hydrated form, i.e., contain at least 10% by weight of water. Highly preferred Zeolite A aluminosilicates herein contain the theoretical maximum of from 18% to 22% (wt.) water in their crystal matrix. It has been found, for example, that less highly hydrated Zeolite A aluminosilicates, e.g., those with about 6% water, do not function effectively as ion exchange builders when employed in the context of a laundry detergent composition.
A second essential feature of the ion exchange builder materials herein is their particle size range. Of course, the amorphous aluminosilicates inherently have a small particle size (ca. 0.01-5 11m diameter). However, the crystalline aluminosilicates must have a small particle size in the range disclosed herein. Proper selection of small particle sizes results in fast, highly efficient builder materials. Moreover, the small particle size of the preferred aluminosilicates herein (<10 µm) presumably accounts for the fact that they are not noticeably deposited on fabrics from an aqueous laundering liquor. This nondeposition is, of course, desirable when the aluminosilicates are employed as detergent builders.
The amorphous aluminosilicate ion exchange builder/water softening materials herein can be prepared according to the following procedure:
- (a) Admix sodium aluminate (NaAlOz) and sodium hydroxide in water to form a mixture having the following (preferred) weight ratios of the components:
- (b) Add a sodium silicate solution (ca. 37% wt. solid; 3.2:1 SiO2/Na2O ratio) rapidly to the mixture of step (a). This rapid mixing step can be carried out using a vessel employed with an efficient agitator; alternatively, the two mixtures at the desired temperature can be metered into an inline mixer which can be part of a dominant bath system to provide a continuous process: The ratio of NaAI02 to sodium silicate (anhydrous basis) is 1.6:1.
- (c) Heat the mixture of step (b) rapidly to 75°C to 95°C (preferably 80°C-85°C) and maintain at this temperature for 10 minutes to 60 minutes (preferably 10 minutes-20 minutes).
- (d) Cool the slurry from step (c) to 50°C and filter. Recover the resulting filter cake and wash in water using a sufficient quantity of water to yield a wash water/solids (anhydrous basis) weight ratio of 2.0:1 (preferred). Repeat the filtration and washing operations.
The filter cake prepared by the foregoing process comprises a mixture of crystalline aluminosilicate and amorphous aluminosilicate in a 1:1 (wt.) ratio. The material from the filter cake exhibits a rapid and efficient uptake of both Ca++ and Mg++ ions. The filter cake is useful per se as an ion exchange material. For use in powdered or granular detergent compositions, it is preferred to dry the filter cake only the minimum amount to eliminate free moisture, using a drying temperature below 175°C to avoid excessive dehydration. Preferably, the drying is performed at 100°C to 105°C.
The amorphous aluminosilicate of this invention can, if desired, be separated from the amorphous-crystalline mixture prepared in the foregoing manner by simply suspending the filter cake mixture in water. When thus suspended, the crystalline portion of the mix settles out (over a period of 1-6 hours), whereas the amorphous material remains suspended in the aqueous medium. The amorphous material can be separated by decantation or other physical means. Of course, low speed centrifugation can be employed to more rapidly separate the amorphous component from the crystalline component of the mixtures herein.
Both the crystalline and amorphous aluminosilicate ion exchangers herein are further characterized by their calcium ion exchange capacity which is at least 200 mg of CaC03 hardness/gram of aluminosilicate, calculated on an anhydrous basis, and which preferably lies within the range of 300 to about 352 mg CaCO/g.
The ion exchange materials herein are further characterized by their calcium ion exchange rate which is at least 0.034 g CaCO3/I/min/g of aluminosilicate (anhydrous basis). Optimum aluminosilicates for builder purposes exhibit a calcium exchange rate of at least 0.068 g CaC03/I/min/g.
The amorphous aluminosilicate ion exchanges herein are further characterized by their magnesium exchange capacity, which is at least 42 mg of MgC03 hardness/gram of aluminosilicate, calculated on an anhydrous basis, and which generally lies within the range of 42 to 126 mg/g or greater.
The amorphous ion exchange materials herein are still further characterized by their magnesium ion exchange rate which is at least 0.004 g (Mg++)/I/min/g of aluminosilicate (anhydrous basis). Optimum aluminosilicates for builder purposes exhibit a magnesium exchange rate of at least 0.008 g (Mg++)/I/min/g.
The ion exchange properties of the aluminosilicates herein can conveniently be determined by means of a calcium ion electrode and a divalent ion electrode. In this technique the rate and capacity of Ca++ and Mg++ uptake from an aqueous solution containing a known quantity of Ca++ and Mg++ ions are determined as a function of the amount of aluminosilicate ion exchange material added to the solution. More specifically, the ion exchange rates of the amorphous and mixed amorphous-crystalline aluminosilicates herein are determined as follows. The aluminosilicate prepared in the foregoing manner is added in the sodium form to 150 ml of aqueous solution containing 0.080 g/I Ca++ and 0.041 g/I Mg++ (measured as CaC03) at a concentration of 0.06% (wt.), pH of 10.0, and with gentle stirring of the solution. The rate of calcium depletion is measured using the calcium electrode (commercially available; Orion@) and the rate of total calcium and magnesium depletion is determinea using the general divalent cation electrode. Magnesium ion removal is thereafter determined by the difference in readings. The rate of depletion is determined for each cation by taking measurements at appropriate time intervals. Total depletion from the solution is calculated after ten minutes, which corresponds to the normal wash time in an aqueous laundering process. Rate curves for calcium depletion, magnesium depletion and mixed calcium and magnesium depletion can be plotted as g/I v. time.
Calcium exchange capacity of the aluminosilicates herein can be determined by a simple titration method. In practice the aluminosilicate sample is equilibrated with a known excess of Ca++. After equilibration and uptake of the calcium ion, the excess calcium ion remaining in solution is determined by a standard titration with EDTA, using a standard Eriochrome@ Black T Indicator. Magnesium ion capacity is determined titrimetrically, in similar fashion.
As noted hereinabove, both the crystalline and amorphous aluminosilicates herein exhibit excellent rates of exchange and capacities for calcium ions. Moreover, the amorphous material herein additionally provides rapid and efficient uptake of magnesium ions. Accordingly, a mixture of crystalline and amorphous material can provide mixed Ca++/Mg++ hardness control.
Preferably, the compositions of this invention are essentially free of the organic agglomerating agents of U.S. Patent 4,096,081.
The surfactant agglomerating agents of this invention include the following.
Preferably the detergent component of the present invention is a water-soluble salt of: an alcohol polyethoxylate sulfate with an average degree of ethoxylation of 1 to 10 and an alkyl chain length of from 8 to 20; an alkyl benzene sulfonate with an average alkyl chain length between 9 and 15, preferably from 11 to 13, and most preferably 11.8 carbon atoms; a C6-GZO alpha-sulfocarboxylic acid or ester thereof having 1 to 14 carbon atoms in the alcohol radical; a C8―C18 secondary paraffin sulfonate; a C10―C18 olefin sulfonate or mixtures thereof; or other hardness insensitive anionic surfactant. Such preferred detergents are discussed below. Blends of surfactants which exhibit hardness resistance (insensitivity) can be used as well.
An especially preferred alkyl ether sulfate detergent component of the present invention is a mixture of alkyl ether sulfates, said mixture having an average (arithmetic mean) carbon chain length within the range of 12 to 16 carbon atoms, preferably from 14 to 15 carbon atoms, and an average (arithmetic mean) degree of ethoxylation of from 1 to 4 moles of ethylene oxide, preferably from 2 to 3 moles of ethylene oxide.
Specifically, such preferred mixtures comprise from 0 to 10% by weight of mixture of C12-13 compounds, from 50 to 100% by weight of mixture of C14-11 compounds, and from 0 to 45% by weight of mixture of C16-17 compounds, and from 0 to 10% by weight of a mixture of C18-19 compounds. Further, such preferred alkyl ether sulfate mixtures comprise from 0 to 30% by weight of mixture of compounds having a degree of ethoxylation of 0, from 45 to 95% by weight of mixture of compounds having a degree of ethoxylation from 1 to 4, from 5 to 25% by weight of mixture of compounds having a degree of ethoxylation from 5 to 8, and from 0 to 15% by weight of mixture of compounds having a degree of ethoxylation greater than 8. The sulfated condensation products of ethoxylated alcohols of 8 to 24 alkyl carbons and with from 1 to 30, preferably 1 to 4 moles of ethylene oxide may be used in place of the preferred alkyl ether sulfates discussed above.
Preferred water-soluble organic detergent compounds herein also include alkyl benzene sulfonates (preferably essentially linear, although "hard" ABS may be used) containing from 9 to 15 carbon atoms in the alkyl group. Examples of the above are sodium and potassium alkyl benzene sulfonates in which the alkyl group contains from 11 to 13 carbon atoms, in straight chain or branched chain configuration, e.g., those of the type described in U.S. Pat. Nos. 2,220,099 and 2,477,383. Especially valuable are straight chain alkyl benzene sulfonates in which the average of the alkyl groups is 11.8 carbon atoms, abbreviated as C11.2LAS.
Another useful detergent compound herein includes the water-soluble salts of esters of alpha- sulfonated fatty acids containing from 6 to 20 carbon atoms in the fatty acid group and their esters with alcohols containing from 1 to 14, preferably 1 to 2, carbon atoms.
Preferred "olefin sulfonate" detergent mixtures utilizable herein comprise olefin sulfonates containing from 10 to 18 carbon atoms. Such materials can be produced by sulfonation of olefins by means of uncomplexed sulfur trioxide followed by neutralization under conditions such that any sultones present are hydrolyzed to the corresponding hydroxy-alkane sulfonates. The alpha-olefin starting materials preferably have from 14 to 16 carbon atoms. Said preferred alpha-olefin sulfonates are described in U.S. Pat. No. 3,332,880.
The secondary paraffin sulfonates embraced in the present invention are essentially linear and contain from 8 to 18 carbon atoms, preferably from 12 to 16 and more preferably from 14 to 15 carbon atoms in the alkyl radical.
Other anionic detergent compounds herein include the sodium alkyl glyceryl ether sulfates, especially those ethers of higher alcohols derived from tallow and coconut oil; sodium coconut oil fatty acid monoglyceride sulfonates and sulfates; and sodium or potassium salts of alkyl phenol ethylene oxide ether sulfate containing 1 to 10 units of ethylene oxide per molecule and wherein the alkyl groups contain 8 to 12 carbon atoms.
Other useful detergents include water-soluble salts of 2-acyloxy-alkane-1-sulfonic acids containing from 2 to 9 carbon atoms in the acyl group and from 9 to 18 carbon atoms in the alkane moiety; beta-alkyloxy alkane sulfonates containing from about 1 to 3 carbon atoms in the alkyl group and from 8 to 18 carbon atoms in the alkane moiety; alkylmethylammoniopropane sulfonates and alkyl- methylammoniohydroxypropane sulfonates wherein the alkyl group in both types contains from 14 to 18 carbon atoms: and alkyl glycerol ether sulfates with from 10 to 18 carbon atoms in the alkyl radical.
A typical listing of the classes and species of detergent compounds useful herein appear in U.S. Pat. No. 3,852,211, to Ohren issued Dec. 3, 1974. The foregoing list of detergent compounds and mixtures which can be used in the instant compositions is representative of such. materials, but is not intended to be limiting.
The compositions comprise from 1 to 4%, preferably from 2% to 3% of hardness insensitive anionic surfactant. Higher levels of surfactant simply dilute the zeolite without any benefit and can give undesirable physical properties to the agglomerate.
The surfactant improves dispersion of the zeolite as shown hereinafter thus minimizing unacceptable deposits, e.g. on fabrics, and increasing the rate of ion exchange.
The inorganic salts are water soluble and form ions. They promote dispersion of the aluminosilicate as shown to rapidly control the water hardness. Examples of such inorganic salts include those having alkali metal cations such as sodium, or potassium, and having as anions thereof sulfates, chlorides, carbonates, bicarbonates, aluminates and phosphates, and mixtures thereof.
Preferred inorganic salts include sodium sulfate, sodium carbonate, sodium orthophosphate, sodium pyrophosphate, sodium tripolyphosphate, and sodium hexametaphosphate. Especially preferred are sodium sulfate and sodium carbonate. Alkali metal silicates should not be present because of their ability to polymerize the aluminosilicate leading to deposits upon washed fabrics.
When the aluminosilicate, the inorganic salt and the organic surfactant are to be incorporated into a detergent composition, additional surface active agent (detergent surfactant) will be included as a portion of the overall detergent composition since the level of surfactant herein is insufficient to form a complete detergent product.
Exemplary of detergent components which may be used in the present invention are those described in U.S. Patent 3,852,211 to Ohren, issued December 3, 1974.
The preparation of the agglomerate containing the aluminosilicate, the inorganic salt and the detergent surfactant is described as follows:
- (a) dispersing the detergent surfactant;
- (b) dispersing the inorganic salt into the detergent surfactant;
- (c) admixing into the dispersed detergent surfactant the aluminosilicate of the present invention, thereby forming an intimate mixture; and,
- (d) solidifying the resultant mass to form the particulate. Alternatively, the detergent surfactant can be sprayed onto a bed of the aluminosilicate and the inorganic salt. Water may be added to the mixture of the detergent surfactant, the inorganic salt, and the aluminosilicate to facilitate mixing. The excess water is then driven off by heating on forming the agglomerate.
In a preferred method, sulfuric acid is added to the synthesis liquor of the aluminosilicate to neutralize excess caustic (while staying above pH 9) and form Na2S04. The surfactant is then dispersed in the slurry and the product is spray or flash dried.
Another preferred method of preparing the agglomerate of the present invention is to spray the mixture of the aluminosilicate, the inorganic salt and the detergent surfactant to form granules of the size compatible with normal detergent particles. It is to be understood, however, that the product can take several forms, e.g. cakes, flakes, prills, or granules which are reduced by conventional methods to the appropriate size.
The preferred method of preparing the agglomerate of the present invention is by spray-drying or spray cooling the mass to form the agglomerate. It is essential when spray-drying is employed that the aluminosilicate should not be dehydrated beyond the point where its ion exchange capacity is adversely affected. Also, certain of the surfactants which are heat sensitive should not be heated to the extent at which they begin to decompose.
When a spray-drying operation is used to prepare the agglomerate the apparatus for conducting the drying operating may be a multilevel spray-drying tower such as that described in U.S. Patent 3,629,950 and 3,629,955 issued to Davis et al.
In preparing the agglomerate of the present invention the detergent surfactant will be present at from 0.5% to 4%, preferably from 1.5% to 2.5% by weight while the aluminosilicate will be present at from 60% to 95%, preferably from 70% to 80% by weight.
The inorganic salts which promote lessened friability are used at a level of from 0.5% to 10%, preferably from 2% to 4%. Larger amounts of the inorganic salts may be utilized in the particulate, however, the benefit reaches a maximum at 5% and additional amounts merely take up more formula room.
When the agglomerate of the present invention is utilized as a water softener for laundering purposes, it is simply added to the wash tub or washing machine, preferably before the fabrics and the detergent composition are introduced and after the water has been introduced into the container.
When the agglomerate of the present invention is used as part of a complete detergent product admixed with a separate granule containing additional detergent surfactant, the overall product is desirably added to the wash tub or the washing machine before the fabrics and after the water has been added.
The amount of the agglomerate utilized as a water softening pretreatment is simply an amount sufficient to remove most of the calcium and magnesium ions present in the wash water. As the product of the present invention normally has a density of from 0.45 gram per cc to 0.65 gram per cc, sufficient usage of the product will, under most United States conditions, be satisfied by the use of from 1/4 cup to 1 cup. Under continental European washing conditions where the water hardness is somewhat greater, the product will normally be used at a level of from 1/2 cup to 3 cups.
Laundry detergent products of the present invention are used under U.S. washing conditions at from 1/2 to 1-1/2 cups and from 1 cup to 3 cups under European washing conditions.
The agglomerate of this invention, when added to a spray-dried detergent granule containing a surfactant to give an agglomerate level of from 5% to 80%, preferably from 10% to 60% by weight of the total composition, provides a complete detergent composition with little or no apparent formation of insolubles. This is especially important when the spray-dried detergent granule contains large amounts of silicates. In order to avoid segregation, the agglomerate should have a size that is compatible with the detergent granule, e.g., not less than 100µm in diameter, preferably not less than 150 µm in diameter. The agglomerates of this invention do not break down unacceptably under ordinary handling and shipping.
Particle size can be adjusted by sieving and recycling or by adjusting spray drying pressure and nozzle size.
Preferably the agglomerates of this invention are completely free of the agglomerating compounds of U.S. Patent 4,096,081, and especially free of the polyethylene glycol of said patent.
The following are Examples of the present invention:
Detergent compositions were made with the intent of increasing the thoroughness of zeolite builder dispersion in wash water. The expected benefits of increased dispersion are (1) reduced incidence of insoluble aggregates on washed fabrics, and (2) increased rate of zeolite availability for complexation of water hardness.
The method used for evaluating degree of dispersion involved Nephelometer® Turbidity Unit (NTU) measurements of wash water concentrations (0.3 g active zeolite/I city water at about 0.154 g/I hardness). A water sample was grabbed after four minutes of normal wash agitation with the zeolite- containing composition present. A higher turbidity reading indicates greater exposed particle surface and thus more effective dispersion. A more sustained turbidity reading after 30 minutes of static observation indicates a slower settling rate and thus a smaller average zeolite aggregate size. Zeolite A, Arogen 2000 from Huber Co., was used in these experiments.
It is known that electrolytes alone aid in dispersion of aluminosilicates in an aqueous medium, and this is seen in comparing A and C. The addition of a binding and wetting agent, polyethylene glycol (PEG 8000), in D (ref. U.S. Patent 4,096,081) improves dispersibility to the level seen with a typical full detergent composition (non-phosphate), as in B. Addition of a relatively hardness-insensitive synthetic surfactant in E and G improves the dispersion, though removal of the PEG (F and H) now shows further benefit in fineness and stability of the zeolite dispersion.
Both of the surfactants in E-H are acceptably hardness insensitive. A tallow alkyl sulfate, for example, would be precipitated by free hardness and rendered ineffective as a zeolite dispersant. It is noted that the higher sustained dispersion at 30 minutes with samples E and F reflect the greater degree of hardness insensitivity of the alkyl polyethoxy sulfate vs. the alkylbenzene sulfonate of G and H.
In all cases, the zeolite was dried from an aqueous slurry of 50-60% total water to which the other ingredients had been added.
The slurry was heated to 60°C and mixed thoroughly. This mixture was then dried in a thin film in a 70°C oven until only 18-20% H20 remained. The water of hydration in the Zeolite A is generally not removed under these conditions. The dried cake was granulated arid screened through a 1.19 mm screen. The resultant density was 0.58 g/cc. The particle size was mostly greater than 1 50 IIm. Zeolite delivered to the wash water was controlled at 0.3 g/I and other components (except in B) were used as: sodium sulfate at 0.01 to 0.03 g/I, PEG 8000 at 0.01 to 0.015 g/I, and synthetic surfactants at 0.008 g/I.
27.6% of the following admix, formed by spray drying a slurry according to Example 1 H, heated to 79.4°C and pressure atomized into a pilot scale (3.05 m (10') diameter) spray-drying tower with 260°C inlet air, was mixed with the above base granule and the mixture was sprayed with .9% polyethyleneglycol (M.W. 8000) and 0.14% perfume. The admix density was 0.55-0.58 g/cc and the particle size was 90% greater than 150 µm diameter.
Composition of Example II was made using powdered zeolite (as received) admixed to the base granule composition. The resulting detergent product was excessively dusty and free flow was unacceptable due to bridging and surging. Segregation is a further potential problem with this approach.
The zeolite composition of Example II is metered into a fluidized bed along with other dry ingredients and nonionic surfactant, minors, and perfume are sprayed on.