US3520817A - Process for making fast hydrating tripolyphosphates and detergents containing said phosphates - Google Patents

Description

July 21, 1970 L. J. CALDWELL ET AL PRQCESS FOR MAKING FAST HYDRATING TRIPOIJYPHOSPHATES AND DETERGENTS CONTAINING SAID PHOSPHATES Filed April 21. 1966 FIG. 2

NEEDLE-L|KE CRYSTALS PLATE-LIKE CRYSTALS (ABOUT ZOOX MAGNIFICATION) (ABOUT ZOOX MAGNIFICATION) R 5 M S THA V W W E D V L NM [CG i. 0 MM mm LS M th i ATTORNEYS United States Patent PROCESS FOR MAKING FAST HYDRATING TRI- POLYPHOSPHATES AND DETERGENTS CON- TAININ G SAID PHOSPHATES Linda J. Caldwell, Pelham, N.Y., and Seymore Goldwasser, Teaneck, N.J., assignors to Lever Brothers Company, New York, N.Y., a corporation of Maine Filed Apr. 21, 1966, Ser. No. 544,244 Int. Cl. C11d 9/14; B01d 9/00; C01b 25/30 U.S. Cl. 252109 9 Claims ABSTRACT OF THE DISCLOSURE The disclosure is concerned with a slow hydrating phosphate, e.g., pentasodium tripolyphosphate, which is mixed, i.e., treated, with an acid phosphate, e.g., disodium dihydrogen pyrophosphate, to increase the rate of hydration of the phosphate and to promote the formation of desirable needle-like crystals. The disclosure is also concerned with a detergent composition containing a mixture of the aforementioned phosphates.

This invention relates to treated phosphates. More particularly, it is concerned with detergents containing the treated phosphates.

It is known to use a phosphate, such as sodium tripolyphosphate, in a detergent composition, such as a detergent tablet. In some instances, it is desirable to hydrate the phosphate before it is employed in the detergent composition. In the past, however, the sodium tripolyphosphate or the like may hydrate too slowly.

It has now been discovered in the present invention that the rate of hydration of a phosphate, e.g., sodium tripolyphosphate, may be increased by treating the phosphate with certain acid phosphates, such as disodium dihydrogen pyrophosphate. The treated phosphate may then be combined with a detergent, e.g., a nonionic detergent, and any optional ingredients to form the desired detergent composition, e.g., a detergent tablet.

During hydration of a phosphate, there is a growth of needle-like crystals therein. Apparently, the water in the hydrated phosphate causes growth in the longitudinal direction only to form the needle-like crystals. Needlelike crystals define a certain type of crystal formation. The needle-like crystals, which are indicated schematically in FIG. 1, are not the same as plate-like crystals, which also are indicated schematically in FIG. 2, The difference between needle-like crystals and plate-like crystals is well known in the art [Industrial Microscopy, L. C. Lindsley, William Byrd Press, Inc. (1929); Handbook of Chemical Microscopy, E. M. Chamot et al., vol. I (1928)].

The crystals described herein are further defined in accordance with the procedure for determining the crystallization in sodium tripolyphosphate. In this procedure, approximately 0.20 gram of sodium tripolyphosphate is placed on a 3 x 1" x 1 mm. microslide. Five to eight drops of water from a stirring rod are added to the sodium tripolyphosphate granules on the microslide. A 25 sq. mm. glass coverslide is placed immediately on top of the granules and it is tilted to one side in order to form a thin film of liquid and granules. The slide is observed at 3 minute intervals for 12 minutes by using a microscope adjusted to 100 magnifications with polarized light.

The phosphate, which is to be treated in this invention 3,520,817 Patented July 21, 1970 "ice with an acid phosphate, is defined herein as pentasodiu-m tripolyphosphate, pentapotassium tripolyphosphate and mixtures thereof. As further defined herein, a phosphate includes the substitution of other phosphates, such as an amount up to 50% of trisodium orthophosphate (Na P-O an amount up to 20% of tetrasodium pyrophosphate (Na P O- and an amount up to 20% of tetrapotassium pyrophosphtte (K P O and an amount up to 30% of pentasodium tripolyphosphate hexahydrate, for a portion of the pentasodium tripolyphosphate or pentapotassium tripolyphosphate.

With respect to sodium tripolyphosphate, i.e., pentasodium tripolyphosphate, it is suitable to use Form I sodium tripolyphosphate alone, Form II sodium tripolyphosphate alone or a combination of Form I and Form II sodium tripolyphosphates. For example, commercial Type I contains about 20% Form I and Form II. Form I and Form II sodium tripolyphosphates and their properties are well-known in the art (US. Pat. Nos. 3,056,652 and 2,897,155).

In order to increase the hydration rate of sodium tripolyphosphate or the like, it is treated with disodium dihydrogen pyrophosphate (NagHzPzoq), trisodium hydrogen pyrophosphate (Na3HP2O7), trisodium hydrogen pyrophosphate nonahydrate (Na HP O 9H O) and mixtures thereof. The phosphate may be treated with the acid phosphate by any acceptable method, such as by mixing as a dry powder or by spraying an aqueous solution on a bed of the phosphate. If the phosphate and acid phosphate are mixed in the powdered state, the mixture generally has about 0.4% to about 5% acid phosphate based on weight of untreated phosphate. If the phosphate is treated with a solution of acid phosphate, less acid phosphate may be employed.

The treated phosphate of the invention is especially useful in detergent compositions. As defined herein a detergent includes soaps and synthetic organic nonsoap detergents which are both well defined terms of art [Chemistry of Organic Compounds, Noller (1951), pages 186 '90; College Chemistry, Smith (1947), pages 431-2 and 455]. Furthermore, all classes of detergents, e.g., anionics, cationics, nonionics and ampholytics, are operable. This includes, among others, sodium soaps of C to C fatty acids, alkyl sulfates, sulfated ethylene oxide condensates of fatty alcohols, alkylbenzenesulfonates, alkyl taurines, acyl taurates, acyl isethionates, stearyl dimethyl benzyl ammonium chloride, 3 (N-2-acetamido ethyl)-2-heptadecyl imidazolinium acetate, tetradecyl ammonium chloride N- dodecyl-B-alanine and all other detergents disclosed in US. Pat. Nos. 2,396,278, 2,477,383, 2,674,619, 2,677,700, 2,897,155 and 3,081,267 which are incorporated herein by reference.

Water is also a required ingredient if the benefits of the invention are to be realized in a detergent composition. Furthermore, it is critical for the success of this invention that the aqueous medium, which has the treated phosphate therein, does not contain more dissolved caustic than is equivalent to about 23.5% NaOH. This percentage is based on the formula:

AXIOO A-l-B solved alkaline materials in the batch and B is the weight of Water per batch. Caustic is defined herein as an alkali material which is a source of Na O or K and which forms a solution in water with a concentration, based on equivalents of Na O, of less than aout 23.5% as NaOH. This definition, therefore, includes silicates, such as Na O-2.4 SiO If the aforementioned concentration is about 23.5% or more, it will actually prevent the formation of the desirable needle-like crystals. In view of this criticality, the amount of water used is at the least the amount necessary to provide the aforementioned required caustic concentration of less than 23.5%. The water content varies over a wide range but it may be as low as about 0.5% and as high as about 35% based on weight of detergent composition.

The detergent compositions of this invention may have other components optionally included therein. For example, a tablet may have one or more inorganic builder salts, such as sulfates, carbonates and silicates of an alkali metal. If a silicate is employed, however, the amount of silicate may be limited since it contributes equivalents of Na O. Other optional components include a small amount, e.g., up to about 1%, of fluorescent dyes or optical brighteners; soil-suspending agents, perfumes; water-dispersible colorants, pigments or dyes; and mixtures thereof.

As stated heretofore, the treated phosphates may be employed in any detergent composition. However, the preferred detergent compositions are the tablets and the spray dried particulate products such as powders, beads, flakes, chips and agglomerates. With respect to a detergent tablet, it generally has about 20% to 95%, preferably about 40% to 70%, phosphate based on the total weight of the tablet. It also has about 4% to 20%, preferably about 10% to 12%, detergent and about 0.5% to 23%, preferably 4% to 10%, water based on the total weight of the tablet. The preferred detergents are nonionic detergents, anionic detergents or mixtures thereof. Any suitable process may be employed for forming the detergent tablets including those described in U.S. Pat. No. 3,081,- 267. For example, an aqueous acid phosphate solution may be added to dry untreated phosphate and other ingredients may then be added until a uniform aqueous mixture is obtained. The agglomerated mixture therefrom is usually screened. The mixture is then compressed into tablets with any desired shape, such as a cylindrical shape. The compressed tablets may be treated subsequently by moistening the surface of the tablets with about 0.1% to 0.4% by weight of water. It is also possible to chill the compressed tablets, either with or without prior surface moistening, to accelerate the strengthening of the tablets. This chilling may be performed by exposing the tablets to substantially quiescent or moving cold air at a temperature not above about 45 F. for at least minutes.

The spray dried particulate detergent usually contains based on weight of total composition about to 60% (preferably 35% to 50%) phosphate, about 5% to 40% (preferably 10% to 20%) detergent and about 2% to 32% (preferably 7% to 15%) water. This detergent composition may be provided by any satisfactory method including those disclosed in U.S. Pat. Nos. 2,987,155, 2,961,410 and 3,189,551 which are incorporated herein by reference. For instance, in a pre-treatment method the phosphate and acid phosphate may be dry mixed and combined subsequently with the other ingredients to form a slurry. This slurry may be crutched at elevated temperatures. After thickening, the slurry may be spray dried, for example at an air inlet temperature from 400 F. to 435 F. and an air outlet temperature from 230 F. to 240 F., to form the desired particulate product. The terminology spray dried particulate product is defined in this invention to encompass free flowing particulate products obtained by any other heat drying process besides spray drying, e.g., drying on a heated roll.

The broad and preferred ranges of essential and optional ingredients for both tablet and spray dried detergent compositions are indicated in Table A.

TABLE A Tablet (percent Spray dried (percent) Ingredient Broad Preferred Broad Preferred Phosphate 40-70 10-60 35-50 Acid phosphate 0. 16-3. 5 0. 04-3. 0 0. 14-2. 5 Non-soap detergent 2 10-12 5-40 10-20 Sodium silicate 3 0-70 0-30 0-23 0-8 Na carboxymethyicellulose 2 0-1 0-0. 4 0-1 0-0. 4 Soap 4 0-10 0-2 0-5 0-0. 5 Fluorescent brightener 3 0-0. 7 0-0. 2 0-1. 0 0-0. 35 Fatty acid amide 0-5 0-3 0-5 0-3 N a toluencsulfonate 2 0-10 0-3 0-10 0-2 0-10 0-3 4-10 2-32 7-15 Balance to 100% tallow.

nlkanamide of 0 1-013 carbon chain: may be N-snbstituted by ethanol or isopropanol.

Thus, in accordance with this invention, a phosphate has been treated with certain acid phosphates to promote hydration and the formation of needle-like crystals therein. This treated phosphate is capable of being used without aging in detergent compositions, such as tablets and spray dried particulate products. 'One advantage in the preparation of tablets containing the treated phosphates is that the aqueous components can be added rapidly without lumping. Two advantages in the preparation of spraydried products containing the treated phosphates are that the crutched slurry does not objectionably thicken during the short time required to hydrate the phosphate and that the uncertainties due to variations in adsorbed water content of the phosphate are eliminated.

The following examples are submitted to illustrate but not to limit this invention. Unless otherwise indicated, all parts and percentages in the specification and claims are based upon weight.

EXAMPLE I Detergent tablets were prepared from the following formulation:

Ingredients: Pounds TPP 53.900

NagHgpaoq CMC 0.290 Fluorescent dye 1.080 Alkane 60 paste 35.000 N-silicate 13.200 Perfume 0.113 LIPA 3.000

Water Pentasodium tripolyphosphate, Type I.

Sodium carboxymethylcellulose.

Contains 15 pounds of detergent active consisting of about equal parts of C12 and C15 sodium alkylzenzenesulfonates with small amounts of other chain lengths and the balance of 20 pounds is mostly water with miscellaneous inert matter, mostly Na2SO4.

37.6% solidszsiozz Na.,0 ratio is 3.22.

8 Laurie isopropanolamide.

1 Grams.

g Contained in other listed ingredients and was 23.1% based on total weight of formulation.

The TPP was added to a rotating drum and the Na H P O was added subsequently thereto. The two powders were mixed thoroughly and 10 pounds of the mixture was removed therfrom. The CMC and fluorescent dyes were then added to the rotating drum containing the treated phosphate. Next, the Alkane '60 paste, N-silicate, perfume and LIPA were added to the rotating drum. Near the end of the mixing period the 10 pounds of previously removed TPP-N21 H P O mixture (treated phosphate) were incorporated in three separate portions. The liquid components were added thereto over a period of minutes, and the resulting mixture in agglomerated form was compressed into tablets.

After standing overnight at room temperature, a tablet having a thickness of 0.98 inch and weighing 1.75 grams has a fracture strength of 6 pounds and a rate of solubility of 75 seconds. The fracture strength was determined by a test which consisted of standing a tablet on edge on a spring scale and then pressing a lever down on the tablet until it fractured. The rate of solubility was determined by placing a tablet in a washing machine containing water at a temperature of 100 F. and measuring the time elapsed until the tablet had completely disintegrated, i.e., broken into small fragments, and dissolved. Furthermore, the rate of hydration of the phosphate was fast enough that the liquid ingredients could be added rapidly without lumping.

EXAMPLE II A similar formulation as described in Example I was prepared except that an acid phosphate was not included therein. This formulation, which is effectively a control for Example I, is as follows:

Ingredients: Pounds TPP 55.000 Alkylbenzenesulfonate 43.070 G-silicate b 6.063 CMC 0.290 Fluorescent dye c 1.080 Perfume 0.113 Sodium carbonate 2.000 Water.

One thousand pounds slow-hydrating pentasodium tripolyphosphate, Form II, may be mixed thoroughly in dry form with 5 pounds of N212H2P2O7. Nine hundred pounds of water may be pumped into a crutcher with the subsequent addition of 640 pounds sodium silicate solution of Example I, pounds sodium carboxymethylcellulose, 300 pounds Pluronic L-64 wherein b represents a molecular weight of 1501-1800 and a plus 0 is an integer such that the molecule contains 40-50% ethylene oxide], 30 pounds dried soap chips and 2 pounds fluorescent whitening agent.

The aforementioned powdered phosphate mixture (treated phosphate) may be added subsequently, and the slurry may be crutched for about 15 minutes at 140- 17 F. until it thickens. The slurry may then be spray dried without aging in a conventional tower with an air inlet temperature of about 435 F. and an air outlet temperature of about 240 F. to provide a solid, particulate detergent.

EXAMPLE IV The procedure of Example HI may be repeated except that 1000 pounds of water are used, that no soap chips are used and that 200 pounds Ucane 12 sulfonate (from mixed phenylalkane of average molecular weight 242 of which the alkyl portion is a straight chain having an average of 11.7 carbon atoms and in which the phenyl group is attached randomly along the alkyl group) and 200 pounds sodium alkyl sulfate derived from fatty alcohols synthesized from tallow are substituted for the Pluronic L-64. A spray dried particulate detergent composition is formed therefrom.

6 EXAMPLE v Dry pentasodium tripolyphosphate was treated with 1% of various dry acid phosphates. The dry mixture (0.20 g.) therefrom was placed on a microslide and several drops of a 20% NaOH solution were added. An observation was made after eight minutes to determine whether needle-like crystals were formed in each treated sample. The results are as follows:

Were needle-like crystals Sample N 0 Treated withformed? 1 Na2HzP207 YeS NasHPgOrQHgO YES 3 NazHP 4 No. NaH2PO4 No. NaaHzPsolo-LflHzo NO. 6 N34HP301u-H2O N0- This example shows a criticality in employing only certain acid phosphates to promote the formation of needlelike crystals in phosphates when phosphates and acid phosphates are mixed in a dry, powdered state.

Having set forth the general nature and specific embodiments of the present invention, the true scope is now particularly pointed out in the appended claims.

What is claimed is:

1. A process for increasing the rate of hydration of a phosphate selected from the group consisting of pentasodium tripolyphosphate, pentapotassium tripolyphosphate and mixtures thereof comprising mixing the phosphate with about 0.4% to 5% of an acid phosphate selected from the group consisting of disodium dihydrogen pyrophosphate, trisodium hydrogen pyrophosphate, trisodium hydrogen pyrophosphate nonahydrate and mixtures thereof to promote the formation of desirable needle-like crystals.

2. The process according to claim 1 in which the phosphate is substituted with up to 50% trisodium orthophosphate, up to 20% tetrasodium pyrophosphate, up to 20% tetrapotassium pyrophosphate or up to 30% pentasodium tripolyphosphate hexahydrate.

3. A process for preparing a detergent composition without aging comprising mixing a phosphate selected from the group consisting of pentasodium tripolyphosphate, pentapotassium tripolyphosphate and mixtures thereof with about 0.4% to 5% of an acid phosphate selected from the group consisting of disodium pyrophosphate, trisodium hydrogen pyrophosphate, trisodium hydrogen pyrophosphate nonahdrate and mixtures thereof; and adding the mixed phosphate to a detergent selected from the group consisting of soap and synthetic detergent and water whereby the rate of hydration of the phosphate is increased and the formation of needle-like crystals is promoted.

4. The process according to claim 3 in which the phosphate is mixed with a dry powder of acid phosphate.

5. The process according to claim 3 in which the phos phate is sprayed with a solution of acid phosphate.

6. The process according to claim 3 in which the addition product of mixed phosphate, detergent and water in agglomerated form is compressed subsequently to provide a detergent tablet.

7. The process according to claim 3 in which the addition product of mixed phosphate, detergent and water is crutched as a slurry and is spray dried subsequently to provide a particulate product.

8. A detergent composition which is a tablet prepared from a formation consisting essentially of a mixture 53.9 pounds pentasodium tripolyphosphate 1.1 pounds disodium dihydrogen pyrophosphate; 0.29 pound sodium carboxymethylcellulose; 1.08 grams fluorescent dye; 35 pounds of detergent comprising about 15 pounds of equal parts of C and C sodium alkylbenzenesulfonates and about 20 pounds water; 13.2 pounds of silicate solution with 37.6% solids and with a SiO :Na O ratio of 3.22; 0.113 pound perfume; and 3 pounds lauric isopropanolamide; said formulation having about 23.1% water; said phosphate being pre-mixed with said acid phosphate in powder form; said mixture being formed rapidly without lumping; said tablet having needle-like crystals therein.

9. A detergent composition which is a solid, particulate product prepared from a formulation consisting essentially of 1000 pounds pentasodium tripolyphosphate; 5 pounds disodium dihydrogen pyrophosphate; 900 pounds water; 640 pounds of silicate solution with 37.6% solids and with a SiO :Na O ratio of 3.22; 15 pounds sodium carboxymethylcellulose; 30 pounds dried soap chips; 2 pounds fluorescent whitening agent; and 300 pounds of HO(C H O),(C H O) (C H O) H in which (C H O) represents a molecular weight of 1501-1800 and a-l-c is an integer such that the molecule contains 40-50% ethylene oxide; said phosphate being pre-mixed with said acid phosphate in powder form; said particulate product being prepared by spray drying said formulation without aging; said particulate product having needle-like crystals therein.

References Cited UNITED STATES PATENTS DENNIS L. ALBRECHT, Assistant Examiner US. Cl. X.R.

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