Description:
This invention relates to a method of producing a detergent composition. More particularly, it relates to a process utilizing known detergent composition ingredients, such as, e.g., automatic dishwashing composition ingredients for producing agglomerates that require little aging or postpreparation grinding.
One commercial home automatic dishwashing composition is believed to be prepared by a process described in U.S. Pat No. 2,895,916. The composition contains a water-soluble alkaline condensed phosphate, a water-soluble alkali metal silicate, and chlorinated tri-sodium phosphate. The process contains the steps of adding to a substantially anhydrous alkaline condensed phosphate, a certain alkali metal silicate and water in an amount at least adequate to wet the said condensed phosphate sufficiently to induce agglomeration and insufficient to destroy the discrete particle characteristic of the condensed phosphate-silicate mixture, agitating the mixture while keeping the temperature from going above about 130° F., then adding chlorinated tri-sodium phosphate to said mixture, agitating the resultant mixture, aging the said resultant mixture to substantially complete hydration while intermittently agitating it and reducing the agglomerates formed to the desired size, the total amount of water added, exclusive of water introduced with the chlorinated tri-sodium phosphate, being from about 12 percent to about 25 percent by weight of the final detergent composition.
In other words, the process calls for a first step which comprises mixing together sodium tripolyphosphate, sodium silicate and water under specified conditions to induce agglomeration; and a second step which comprises separately adding to the partially agglomerated mixture the chlorinated tri-sodium phosphate. The resultant mixture is agitated and then aged to substantially complete hydration with intermittent agitation. The aging period is about 4 hours. The term aging as used herein means that period of time necessary to complete the hydration of ingredients.
Apparently, during this aging period, substantial completion of the hydration of the tripolyphosphate takes place. Thereafter, the resulting agglomerates are reduced to the desired size before packaging.
It should be noted that in an older prior art method of preparing a similar detergent composition described in the patent for comparative purposes, an aging period of an even greater period of time is stated.
U.S. Pat. No. 3,247,118, Lever Brothers, describes a process for preparing dishwashing compositions similar to those described in U.S. Pat No. 2,895,916 wherein the aging period is reduced to about 1 hour. However, the process utilizes an additional step of passing heated air over the agglomerated granules while they are admixed in a rotating drum.
It has been found, quite surprisingly, that the home automatic dishwashing compositions prepared according to the method hereafter described do not require an aging period before packaging, but only cooling to room temperature before packaging, nor do the agglomerates produced thereby require any reduction in size before packaging.
In addition, the automatic dishwashing composition prepared by the process of this invention is free-flowing, noncaking and nonfriable. It is chlorine stable and it can have a high moisture content if desired.
A principal object of the present invention is to overcome the aging and grinding steps in the preparation of home automatic dishwashing composition.
Another object is to prepare a controllable particle size free-flowing, noncaking home automatic dishwashing composition which is chlorine stable.
Still another object of this invention is to prepare a homogeneous, nonsegregating substantially dust-free agglomerate of home automatic dishwashing ingredients in either a batch or continuous operation.
Another object is to prepare a detergent composition which is noncaking in the dispenser of a home automatic dishwashing machine.
A further object is to provide a process for preparing detergent compositions wherein it is possible in one operation to mix particulate ingredients, including active chlorine containing compounds as hereinafter defined and then add liquid materials as hereinafter defined and run on a continuous basis to produce and package a home automatic dishwashing composition.
These and other objects are accomplished in accordance with the present invention in the following manner. Generally, in a continuous operation, detergent composition ingredients, e.g., home automatic dishwashing ingredients, in particulate form such as in powder or fine crystalline form are charged into a bed of material being agglomerated in a suitable agglomeration zone. A preferred agglomeration zone comprises an elongated cylindrical confined zone which is rotated about its longitudinal axis and which is adapted with suitable means for maintaining a falling curtain of the detergent ingredients communicating between an upper portion of the confined zone and a bed of the material maintained in the bottom portion thereof. The liquid material, defined hereinafter, of the home automatic dishwashing compounds is sprayed as discrete droplets through a suitable spray nozzle or nozzles. The droplets are then brought into contact with the particulate ingredients in the falling curtain, preferably of a constant density, thereby wetting the particles to form agglomerates, preferably without the liquid material being sprayed onto any part of the apparatus being used. The wetted particles fall to the bed of material maintained in the bottom portion of the agglomeration zone where they are subjected to shear which breaks the few large oversize agglomerates that happen to form into desirable uniform-sized particles. The rotating and tumbling action of the bed produces agglomerated particles of the home automatic dishwashing composition of the desired size. Particle size of the agglomerates can be varied by controlling the rate of rotation of the drum, the length of time of rotation, and the amount of liquid applied.
More specifically referring to the drawings, with particular initial reference to FIG. 1, the apparatus may generally comprise a frame 10 having an angularly adjustable bed 12, two-way acting power means 14 to selectively positioned bed 12 at any desired angle relative to the horizontal acylindrical drum 16, means 18 and 20 to rotatably support the drum on bed 12, and variable speed drive means 22, 24 and 26 to rotate the drum.
Drum 16 comprises: an outer cylindrical shell or wall 28; an annular end plate 32 defining a feed opening 34 through which the particulate ingredients 36 are loaded; an annular end plate 38 defining a discharge opening 40 through which the agglomerated detergent composition 44 is discharged through hopper 42; a spiral conveyor vane 52 to move the particulate ingredients and/or partially agglomerated particle 36 through the drum toward the feed opening 34; and a spiral conveyor vane 46 to move the particulate ingredients 36 and/or agglomerated particle 44 toward the discharge opening 40; a feedline 56 provided with a plurality of spaced spray nozzle 58 (FIG. 2); and a cylindrical bundle of parallel spaced cylindrical rods 60 which develop the falling curtain and are carried between conveyor vanes 46 and 52 and positioned between drum end plates 32 and 38. It will be appreciated that, except for feedline 56, the components of drum 16 rotate together as an integrated unit.
Other apparatus useful in the practice of this invention is described in pending application Ser. No. 858,213, filed May 2, 1969 to which reference is hereby made.
The ingredients that are useful in preparing automatic home dishwashing composition are well known to those skilled in the art. They have been described in numerous patents and articles, for example U.S. Pat Nos. 3,359,207; 3,247,118; 2,895,916; 2,756,214 and 2,689,225.
The preferred ingredients for the detergent composition, specifically the home automatic dishwashing composition, that can be made by the process of this invention are as follows: (A) alkaline condensed phosphate, (B) active chlorine containing compound, (C) sodium or potassium silicates, (D) surfactant and (E) water.
The alkaline condensed phosphates preferably are those having a Na2 O or K2 O to P2 05 of about 1:1 to 2:1. More preferably, they are the pyrophosphates and polyphosphates, the more desirable are those that rapidly hydrate. The most preferred alkaline condensed phosphate is sodium tripolyphosphate. About 20 to 80 parts by weight of the alkaline condensed phosphate per 100 parts is useful in the composition, preferably the amount is about 30 to 60 parts by weight. The alkaline condensed phosphates can be used in anhydrous form or in a hydrated or partly hydrated form, preferably the anhydrous form.
Another ingredient of the detergent compositions of this invention is an active chlorine-containing compound. The active chlorine-containing compound imparts germicidal, bleaching, water-sheeting and protein-removing action to the detergent compositions. Active chlorine-containing compounds which may be employed in accordance with this invention include chlorinated tri-sodium phosphate, trichlorocyanuric acid, the sodium salt of dichlorocyanuric acid, the potassium salt of dichlorocyanuric acid, sodium hypochlorite and 1,3-dichloro-5,5-dimethylhydantoin. Based on 100 parts of detergent composition, 0.5 to 35 parts of active chlorine-containing compound may be employed. If chlorinated tri-sodium phosphate is employed, then from 10 to 35 parts of the chlorine compound is preferred since the available chlorine in chlorinated tri-sodium phosphate is approximately 3.50 percent. Much higher amounts of chlorine are available in the chlorinated cyanuric acids and, therefore, when they are employed, from one-half to 10 parts of this chlorine compound is preferred. Generally, the amount of chlorine compound employed will depend upon the intended application of the detergent composition.
The sodium or potassium silicates preferably are those having a Na2 O or K2 O to SiO2 ratio of about 1:3.75 to 2:1. More preferred, are the sodium silicates having a Na2 O to SiO2 ratio of about 1:3.22 to 1:2.5. Preferably, about 3 to 30 parts by weight silicate (on an anhydrous basis) per 100 parts detergent should be used. A more preferred ratio is about 4 to 15. The silicate can be used in its anhydrous form or in its hydrated from or as a water solution of these forms or a combination thereof.
Water solutions of silicates are known as liquid silicates and normally are the sodium silicates having Na2 O: SiO2 ratios ranging from about 1:1.60 to about 1:3.75.
The surfactant preferably is a nonionic one that has little or no tendency to foam by itself or in the presence of a foam-producing food soil. It preferably is compatible with the chlorine-containing compound. Surfactants that are especially compatible with chlorine-containing compounds are described in U.S. Pat. Nos. 2,856,434; 3,281,475 and 3,310,496; French Pat No. 1,395,977 and Netherlands Pat. No. 65/05065. The nonionic surfactants are well known in the art and have been described in various publications, such as U.S. Pat. Nos. 3,390,092; 3,356,612 and 3,359,207, column 3, line 16 through column 5, line 33 which is incorporated herein by reference. Generally about 0.5 to 3 parts by weight surfactant, preferably nonionic type, per 100 parts of detergent composition is useful and such an amount is preferred. Minor amounts of an anionic surfactant can be used with the nonionic surfactant.
The amount of water that is used in preparing the detergent composition is critical and must be between about 5 to 50 parts by weight per 100 parts detergent composition, depending upon the amount of particulate anhydrous ingredients that are used. At least sufficient water should be present to permit complete hydration of the alkaline condensed phosphate and more preferable, all hydratable ingredients. The water that is used can be water per se or water containing a dissolved ingredient.
Other ingredients can optionally be included in the detergent formulation for various results. Such compounds include aluminum sulfate, sodium sulfate, soda ash, sodium aluminum phosphate, anhydrous tri-sodium phosphate, sodium aluminate, boric acid and borax.
The ingredients of the detergent composition are combined as follows:
According to one method, all the particulate ingredients are mixed to form a homogeneous mixture, if they are not already so mixed. These particulate ingredients are, (a) alkaline condensed phosphate, (b) active chlorine-containing compound, and optional particulate ingredients such as soda ash.
Next, the "liquid materials" are sprayed into a falling curtain of the particulate ingredients.
The "liquid materials" are (1) the surfactant and (2) either a solution of silicate or water. Optionally, water, a solution of a portion of the other particulate ingredients or a solution of optional ingredients can also be used as "liquid materials."
The various liquid materials can be sprayed in any order of addition, preferably the surfactant is added in an anhydrous state onto the particulate ingredients containing no free water. Free water does not include the water of hydration of the particulate ingredients.
According to one embodiment of this invention, the surfactant is sprayed onto a falling curtain of the particulate ingredients.
Next, an aqueous solution of the silicate is sprayed onto a falling curtain of the particulate ingredients and the surfactant. If the needed amount of water has not been added with the silicate, the remainder can be added by spraying in a similar manner to that of the surfactant and the aqueous solution of the silicate.
If it is desired to use a solid form of silicate, the solid silicate can be included with the aforedescribed particulate ingredients. In this event, water is sprayed onto the curtain of dry ingredients and surfactant in place of the aqueous solution of silicate.
Preferably when a cyanurate is the active chlorine-containing compound, it should be added in dry form onto the formed agglomerated particles.
Generally, the size of the agglomerates that can be produced in the practice of this invention is between about 10 and about 60 U.S. mesh size, preferably a mesh size between 12 and about 40 is produced. Normally, the particle size of the dry ingredient used in preparing the agglomerates is about 200 U.S. mesh size.
Having thus described the invention in general terms, reference is now made to the figure of the drawing which describes one preferred apparatus for carrying out the process of the present invention. The preferred apparatus is described herein and illustrated in the figure of the drawing.
The following examples will serve to illustrate the process of this invention. The amounts of the ingredients are expressed in pounds, unless otherwise indicated.
EXAMPLE I
A representative agglomeration is carried out batchwise in the agglomerator apparatus, similar to that shown in the drawings and described heretofor using the following recipe:
1. Particulate ingredients Sodium tripolyphosphate 30.0 Soda ash 7.0 Chlorinated trisodium phosphate 31.0 Sodium aluminate 0.5 2. Liquid nonionic surfactant amine polyglycol condensate type 0.6 Sodium salt of disulfonated dodecyl diphenyl oxide 0.5 3. Water 11.5 4. Liquid sodium silicate 19.0
First, the particulate ingredients are added and allowed to dry blend to a homogeneous mixture, usually for about 2 minutes. Next, a mixture of the liquid surfactants is sprayed onto a falling curtain of the mixed particulate ingredients from spray nozzles 58 at a pressure of about 30 to 60 p.s.i. at a temperature of 60-100° C. in about 1 to 2 minutes. Next, the water is sprayed at about 20-30 p.s.i. in a similar manner for that of the liquid surfactants. Finally, the liquid sodium silicate is sprayed at a temperature of 30-100° C. at a pressure of 40 to 80 p.s.i. for about 10 minutes.
The rotation is continued for about 20-30 minutes to cool the resulting agglomerates.
The agglomerated composition can be removed from the apparatus immediately after the silicate addition to be cooled in a rotary cooler for a minimum of 10-15 minutes if desired.
EXAMPLE II
The home automatic dishwashing composition which was prepared in example I, along with two of the available commercial home automatic dishwashing compositions, were evaluated as follows: Bulk density and frangibility data are obtained by a consolidated procedure. A bulk density determination is made on a 100 gm. sample. This sample is then screened utilizing "Ro-Tap" machine. The screen fractions are weighed, recombined and placed in a half-gallon jar with four, 1.5-inch diameter, hard rubber balls. The jar is turned on a jar roller for 30 minutes at 60 r.p.m. A second bulk density determination is made on the sample. The difference between initial and final values is reported as frangibility. The negative values seen in some of these samples can be attributed to water loss with little or no breakdown of the agglomerated particles. Dishwashing effectiveness is determined by washing plates soiled with standard milk-margarine mixture. A.G.E. Mobil Maid is used with tap water at 125° to 140° F. and approximately 5 p.p.m. hardness. Observation of haze, spots and streaks is made and a subjective ranking is applied by three observers. For simplicity, the numerical values have been converted to an "excellent to poor" grading.
Comparison has been made of the calculated available chlorine with the actual values observed. The stability of the available chlorine was evaluated by aging at 40° C. in sealed jars and at ambient room conditions in open jars.
The composition prepared in example I is given the designation sample No. 2, and the two commercial compositions are given the designation sample Nos. A and B. The evaluation test results for these compositions are reported in table I.
Also several other detergent composition agglomerations were prepared according to the procedure of example I and evaluated by the test procedures previously described, unless otherwise indicated.
The recipes and test results are reported in table I under sample Nos. 2 and 9. ##SPC1## ##SPC2## ##SPC3##
Sample No. A, a commercial compound, is believed to have been formulated with ingredients and amounts similar to that shown in sample No. 2. The data shows that sample No. 2 lost only 34 percent of its available chlorine after 30 days exposure to the air at room temperature compared to a 94 percent loss for commercial sample A. When tested at 40° C. in closed containers, the data shows that sample No. 2 lost 20 percent of its available chlorine as compared to a 45 percent loss for sample No. A.
Sample No. B, another commercial compound, is believed to have been formulated with ingredients and amounts similar to that shown in sample No. 5. The data shows that sample No. 5 lost only 2 percent of its available chlorine after 30 days exposure to the air at room temperature, compared to a 10 percent loss for commercial sample No. B.
The data for sample Nos. 3 and 4 show that the order of addition of the liquid materials is not critical.