US3562165A - Process for preparing a dry compacted detergent composition - Google Patents

Abstract

A SOAP-LIKE COMPACT DTERGENT, CONSISTING OF A MIXTURE OF DRY-COMPACTED POWDER COMPONENTS IS PRODUCED BY MIXING THE COMPONENTS IN THE DRY STATE, MILLING THE MIXTURE AND COMPACTING THE RESULTING POWDER IN DIES WITH A MINIMUM PRESSURE OF ABOUT 30 KG/.CM.2.

Description

OR 3562165 EX US. Cl. 252-99 4 Claims ABSTRACT OF THE DISCLOSURE A soap-like compact detergent, consisting of a mixture of dry-compacted powder components is produced by mixing the components in the dry state, milling the mixture and compacting the resulting powder in dies with a minimum pressure of about 30 kg./cm.

The present invention relates to a compact product based on detergent powder, said product having the shape and compactness of a common soap to be used in fact like a common soap, but which is obtained by a new process for this kind of product.

In fact, pieces of hard synthetic detergent presently on the market, are obtained by the conventional soap making process, consisting essentially of mixing the various components with water, drawing, refining the paste, drawing again, cutting and molding.

This process in the manufacture of hard detergents, as those previously cited, has several shortcomings of an operative, economic and qualitative character. In fact, the working cycle is necessarily very complicated and difiicult as the materials entering into the formula of said hard detergents have a nature quite different from those of a conventional soap obtained from fatty acids.

It is also very important to note that the quality of these products is not entirely satisfactory. The product shows in fact, when used, a non smooth and non soft surface. Under the solvent action of the water, when the product is used, there will develop a surface showing a certain sandy aspect or roughness which is very unpleasant and which, if the soap is used as a washing soap can amount to such a degree as to be harmful to the washed fabric, due to abrasive action. Furthermore said manufactured products are not very resistent to elevated room temperatures, tend to become soft and to exude moisture.

Another disadvantage of the conventional processes results from the limits to which the formulation is submitted, due to the presence of a high water content in said formula preventing the use of substances which are incompatible with one another in the presence of free water.

The working process to which the invention relates (defined for the sake of shortness as a dry process), ensures remarkable advantages from the operative, economical and qualitative standpoints.

In fact the simplicity of the technological process, its remarkable quickness and the very limited number of required equipment and machinery ensures high efficiencies and therefore low manufacturing costs. The investments in money for purchasing the equipment is far less than that required by the above mentioned conventional process. Also from the standpoint of quality, the dry process ensures remarkably higher results than those obtained by the conventional process; the roughness of the surfaces of the piece is entirely eliminated. During use a smooth and soft surface, almost like that of a normal soap is retained; the appearance of the piece ob- 3,562,165 Patented Feb. 9, 1971 tained by the dry process is more pleasant and finally the obtained volume, at a given weight, is greater.

The dry" process also shows a large flexibility of formulation due to the almost total absence of free water in the composition of the product. If the manufactured product is to be used as a washing soap, solid bleaching agents, such as sodium perborate and/or ammonia base compounds and/ or chlorine base compounds can be added to the formulation without affecting the compound itself.

The process to which the present invention relates will be described hereinafter:

The components of the formulation are dry mixed in a powder mixing apparatus of any kind. It is fundamentally important to the effect of the subsequent operations that the free humidity in the mixture of the powders be as low as possible, mainly in order not to affect the good fluency of the powders. The amount of total humidity can also be very high, but said water must be present as crystallization water of one or more components of the formula and not as free water.

The mixture will then be ground in a powder mill. The grain size of the powders after milling can range from an impalpable powder to a coarse powder, and said feature has a remarkable importance on the effects of the quality of the product. It has been experimentally found that the roughness of the piece when used depends on the fineness of the ground powder, the formula of the product and upon the pressure exerted when the components are compacted. In other words, certain possible components of the formula can cause a roughness in the use of the finished product if they are not ground to an impalpable powder, while other possible components of the formula can remain in a relatively coarse form, without thereby affecting the softness of the feel when the t piece is used. It is important to remark that the milling operation of the various ingredients can be carried out before the mixing operation, either individually for each component of the formula or for groups of components.

The mixed and ground powders in the desired proportions are then sent directly to a compacting operation without passing through any other intermediate working stage. It has been in fact found that detergent powders having determined compositions if-adequately compressed under pressures of at least 30 kg./ square cm., with particular contrivances in the equipments required for compacting, and provided that said powders are ground at a fineness adequate to the particular formulation which has to be compacted, give products which can be used like common soap, wearing out regularly without foliating or crushing, and being stable through the entire time of use without undergoing degradation even in the most unfavorable ambient conditions.

For the compacting operations it is necessary to have a machine equipped for this purpose, in order to solve the several problems deriving from the type of powder (which is very fine and rather sticky) and from the need of having a powder supply into the dies so as to ensure a constant dosage and therefore a constant weight of the piece, from the need of operating always under the same pressure on the powder in order to obtain a piece having uniform characteristics.

It is not essential that the compacting machine used in this process be of any particular kind. Either a die and punch reciprocating machine (for instance of the kind used for compressing thermosetting resins) or a rotary machine (for instance of the kind used for compacting medicinal products) or a compounded rotary-reciprocating machine can be successfully used. What is essential for the process is a group of technical contrivances and equipment as hereinafter described.

The supply of the powder to the die, when effected volumetrically, should be carried out 'by vibrating the powders in order to prevent the latter from having a variable apparent density depending on the aeration of said powders, the level of the powder in the feeding hopper, and for preventing bridges from being formed in the dosing device. The above has a particular importance due to the high amount of powder which must be fed into the die.

An example of a suitable kind of supply of the powders consist in a constant level hopper fed by a rotary valve controlled by an electric motor. The terminal portion of said hopper has a quadrangular shaped section and is connected by means of a flexible hose to guides on which glides a two compartment drawer having an equal volume and a quadrangular section approximately equal to that of the feeding hopper. Said compartments have hinged movable bottoms, the opening or closing movements of which are controlled by an electromagnet. When one of the compartments is being loaded in its position under the feeding hopper, its movable bottom is closed, while the other compartment is discharging in a stroke little hopper, wherefrom the powder directly falls into the die. The movement of the drawer which glides in the guide connected to the flexible hose is operated by an electromagnet.

As aforesaid, in order to ensure a constant specific gravity of the powders contained in the drawer each time, on the drawer itself a continually operating vibrator is mounted. Thus the powder in the dosing compartments of the drawer will always settle in the same way, thus having a constant apparent specific gravity and therefore a constant weight of powder will always be obtained in both dosing devices. If a product having a different weight is to be produced, the possibility exists of course of substituting dosing devices having a different volume for the drawer.

Under the drawer a stroke little hopper is mounted, the top cross sectional area is in immediate contact with the drawer and has such an area as to allow the discharge of the powder into the little hopper, whatever the position of the drawer. As aforesaid, the little hopper feeds directly the die into which the powder will be compressed.

Of course it is possible to use other feeding devices, of the volumetric or weight type.

Another essentially important point for the successful issue of the operations is the pre-compacting operation. It is necessary to expel from the powder the maximum possible amount of air before the final compacting, in order to avoid any included air from remaining in the piece when large amounts of powder are compressed at high speed, said air being very harmful since it will cause a great weakening of the product, rendering it brittle and friable instead of hard and compact. Further, without adequate pre-compacting it will be very difficult to obtain high manufacturing capacities as the punch of the press would have to effect too long a stroke and consequently the time required for this operation would be high.

The embodiment of this operation of course differs from one to another kind of press. In case of reciprocating presses, the pre-compression can very simply consist of a change of the stroke speed of the punches within the die; in case of rotary presses, in a gradual and relatively slow nearing of the upper punches to the lower punches; in case of compounded system press, the pre-compression can be obtained by one or both of the aforesaid systems.

Of course other mechanical systems may be used. What is really essential is a pre-compacting reducing in a relatively slow way the apparent volume of the powders by at least 25% and which expels such an amount of air when the powders are subsequently compressed (carried out at a more or less high speed), no shortcoming will result from air enclosed within the manufactured product.

In case of reciprocatory or compound presses, according to the selected formulation, it may be necessary to use more than one pre-compacting station. In other words, it might benecessary to compress the powders sequentially a certain number of times (2 to 6 times) in order to ensure a satisfactory expulsion of the air and an adequate gliding and settling of the powders themselves in the already partially compacted piece. The compacting must be carried out under relatively high pressures, in fact pressures of at least 30 kg./square cm. are necessary, in order to obtain a manufactured product having satisfactory features.

It is important to remark that the formulation has a fundamental importance in the selection of the pressure to which it is necessary to compact the powder.

As far as the mechanical part of the operations is concerned, the compacting operation is carried out in the die (which must be slightly conical in order to allow the expulsion of the finished product) into which the powder has been introduced and precompressed. Two punches (both movable or either movable) operate the actual compacting and give the shape to the manufactured product.

The pressure can be supplied by mechanical (eccentric presses, toggle presses, etc.) or by pneumatic or hydrostatic means (oleodynamic or hydrodynamic presses).

The manufactured piece can be expelled upward or downward of the die, and the various mechanical systems for embodying said operations are well known.

Another fundamental operation is that of cleaning the die and the punches. The powders which are submitted to the operations are rather sticky due to the nature of one or more components of the formulation to be compacted or due to possible relatively large amounts of free water.

Obviously various mechanical systems can be devised in order to exert this function, but practically the most efficient system consists in causing rotary brushes to pass, after each compacting cycle, on the punches or inside the die, said brushes removing any fouling which could be left.

Soon afterwards, the lubrification operation has to be carried out and this operation can be embodied, either by particular kinds of lubricant powders (for instance talcum, kaolin, starch, silicic acids etc.) which create a very thin film on the surface contacting the detergent powders, or by suitable lubricants (oils, silicone emulsions, water, kerosene, other petroleum derivatives, etc.).

Several devices suitable to carry out said operations exist and are well known in the art.

It is interesting to remark that the lubrication can be effected simultaneously with the brushing operation, coupling in the mechanical brushing devices the lubricating devices.

In order also to avoid difficulty in removing the pieces from the punches, it may be useful, according to the formulated compound, which must be compacted, to cool or to heat the punches or the die, or both.

As far as the formula is concerned, if the product is to be used as a washing soap, the composition of a compact detergent of the type described in the first part of the present invention is very similar to that of the common sprayed detergents. In said composition are included sodium aryl-alkyl sulphonates, having variable lengths of chain of the carbon atoms, complexed sodium phosphates such as sodium tii-poly-phosphate or pyro-phosphate, optical coloring agents, carboxymethyl cellulose, sodium carbonate, sodium sulphate, ammonium bicarbonate, waterglass, sodium metasilicate, starch etc.

Due to its compacting assisting action in this type of process, the presence of waterglass with a ratio Na O:SiO variable from 1.0:1.3 to l.0:1.5, is extremely important.

It is of course possible to obtain manufactured products without the use of this ingredient, but said products have a lower quality than those obtained with the waterglass having the characteristics as described above, due to a lower cohesion and compactness, due to a greater tendency to crush, to a lower mechanical strength of the product. The waterglass in the above Na O to SiO ratios acts in fact as a binding agent for the whole mass and therefore compacting pressures lower than those which would be necessary in the absence of such an ingredient.

The amount of waterglass (with the aforesaid characteristics) necessary to obtain a product of good quality, of course varies according to the formulation, from 0.5% to 35.0%.

As to the techniques to be used for adding the waterglass solution to the mixture of powders, avoiding the formation of a pasty mass, it is suflicient to add the solution on an anhydrous or partially hydrated ingredient, or a mixture of anhydrous and/or partially hydrated ingredients, such as for instance sodium tri-poly-phosphate, sodium pyrophosphate, the sodium orthophosphate, the sodium carbonate, etc. It is to be noted that (according to the kind of the components the formula has) it may be necessary to cool or to heat the mixture of the powders with the waterglass solution in order to promote and to accelerate the crystallization process of the free water and of the waterglass solution. On the other hand, it may be necessary to leave the mixture for a certain time in order to enable the hydration reaction to reach its completion. Once the hydration of the hydratable compounds is effected, and a dry powder is obtained, the other powders are normally added.

The required waterglass can otherwise already exist in the sodium aryl-alkyl-sulphonate (or other sulphonate or sulphate) previously mixed in paste form with the solution of waterglass having the aforesaid features, and then dried.

Even without waterglass having the aforesaid characteristics, it is possible to obtain manufactured products showing satisfactory qualities. It is however necessary to adopt remarkably higher compacting pressures.

As already pointed out, particular components with bleaching and cleaning properties can be used; without the risk of decomposition during the manufacturing process and during the storage of the pieces before their sale and use.

In connection with these materials, it is to be noted that the ammonium bicarbonate, when contacted with water, inhighly alkaline media, forms ammonia, which, as is known, has a bleaching power; that the sodium perborate, in contact with water, releases active oxygen, having a bleaching and cleaning power; that the chlorinated substances, such as calcium and lithium hypochlorite, the di-chloro and tri-chloro iso cyanuric acids, or also mixed or not, their alkaline and/or alkaline earth metal salts, when contacting water, release active chlorine having cleaning and bleaching power.

Said materials cannot be used in the normal sprayed detergents or in the compact detergents manufactured by the conventional processes, because the development of ammonia and/or of oxygen and/or of chlorine during the manufacturing process would occur due to the presence of water.

In the dry" process according to the present invention, said ingredients can be used without risk of decomposition during the manufacturing process or during the storage. The decomposition occurs, on the contrary, when the compact detergents are used, i.e. when the user contacts the compact detergent containing one or more of the aforesaid substances with the fabric to be washed and the water. The development of ammonia and/or of oxygen and/or of chlorine occurs in the most favorable conditions, both from the physical-chemical point of view as well as from the point of view of performance, as the developing of ammonia and/or of oxygen, and/or the chlorine are directly contacting, in high concentration, the fabric to be washed.

It is however to be noted that the aforesaid substances do not necessarily have to form part of the detergent composition, for the dry manufacture of the compact deterge'nt. It is quite possible to provide a formulation wherein the above mentioned substances do not exist at all, although all advantages deriving from the process remain valid.

Some examples of formulations are ported:

hereinafter re- EXAMPLE NO. 1

The following substances, in the amounts and in the order as indicated, are put in a common powder mixer:

10 parts of sodium tri-poly-phosphate 10 parts of sodium carbonate 10 parts of waterglass, in 30% solution The mixture is heated, cooled; then added with:

The mixer is started and operated for about minutes.

The mixture of the powders is discharged into the feeding hopper of a hammer-type mill. The mill is fitted with sieves suitable to obtain a maximum grain size of 100 mesh is started.

The powder thus milled is pounded into the feeding hopper of the dosing group of the compacting machine.

The dosing group is pre-set for dosages of 250 grams, with dosing allowable variations of :5 grams.

The compacting machine is started, feeding the lubricating devices of the dies and of the molds with a mixture, in equal parts of ventilated talcum and silica gel.

The dosed powder, poured into the lubricated dies, is de-aerated by compression and then definitely compacted in the actual compacting station under a 155 kg./sq. cm.

pressure.

The compacted piece will be expelled in the subsequent station and sent to a packaging station.

EXAMPLE NO. 2

The following substances, in the amount and in the order as hereinafter disclosed, are put in a common powder mixer:

parts of sodium tri-poly-phosphate 5 parts of sodium carbonate 5 parts of ammonium bicarbonate 14.7 parts of sodium sulphate 10 parts of sodium bentonite (white 350 gel) parts of sodium alkyl-benzene-sulphonate mixture with 10% waterglass 0.2 part of perfume 0.1 part of optical bleaching agent The mixer is started and then operated for about 25 minutes.

The mixture of powders is discharged into the feeding hopper of the hammer mill. The mill fitted with suitable sieves in order to obtain a grain size of 120 mesh is started.

parts of the mixture thus obtained and 10 parts of the mixture follows:

98 parts of potassium-di-chloro-iso-cyanurate 2 parts of silica gel are introduced into a common powder mixer and mixed for about 5 minutes.

The so mixed powder is transferred to the feeding powder of the dosing group of the compacting machine.

The dosing group is pre-set for dosages of 400 grams, with allowable variations of i8 grams.

The compacting machine is started, supplying the lubricating devices of the dies and of the molds with a mixture in equal parts of fluid vaseline oil and of fluid silicone.

The dosed powder, poured in the lubricated dies, will be deaerated by compression and then finally compacted in the actual compacting station under a 180 kg./sq. cm. pressure.

The compacted piece will be expelled in the subsequent station and sent to a packaging station.

If the product is to be used as a toilet soap, of course the composition of the possible formulations will be different, even if the manufacturing process remains identical to that described in the first part of the present invention.

In said compositions there will be ingredients well known in the techniques of toilet soap and cosmetic art, such as for instance sodium lauryl-sulphate, sulphates from animal or vegetable fats, alkyl-aryl-sulphonates, as detergents particularly suitable for the skin, fatting agents as for instance lanolin or vaseline, foaming agents, such as for instance the ethoxylated or non-ethoxylated fat amides, ingredients for imparting a particular plasticity to the finished piece such as for instance talcum or silica gel, waterglass having the features similar to those previously cited in connection with the manufactured product for washing purposes, and finally eccipients, coloring agents, and perfume.

A remarkable advantage of these kinds of soap is the possibility of obtaining a product which, when in solution, can have a neutral pH or an acid pH thus showing a beneficial effect on the skin which normally has an acid pH. This is possible as the above cited detergents (as generally almost all synthetic detergents) are stable in acid medium, as opposed to the behavior of common soap from fatty acids which is unstable in acid medium.

In order to obtain a neutral or acid pH, an organic acid can be added to the formulation, such as for instance citric acid and/or tartaric acid and/or oxalic acid; or it is possible to use a buffer system such as for instance a mixture of monosodic and bisodic phosphates, or buffer mixtures of other well known complexed phosphates. Of course also other buffer systems can be used, provided they are compatible with the other components of the formulation.

As to the use of the waterglass previously discussed, the same criteria apply as with the product for washing purposes.

Hereinafter will be disclosed an example of formulation of a compact detergent for use as a toilet soap.

EXAMPLE NO. 3

To a common powder mixer the following substances are charged in the amounts and in the order as hereinafter disclosed:

parts of a 30% solution of waterglass are added to a mixture of- 10 parts of anhydrous monosodic sodium phosphate parts of anhydrous sodium sulphate the mass is mixed until complete crystallization of the solution water of the waterglass is obtained.

Then are added:

parts of sodiumlaurylsulphate in 80% powder 8 parts of maize starch 5 parts of cocomonoethanolamide 5 parts of talcum 1 part of citric acid 1 part of perfume The dosed powder, poured into the lubricated dies, will be deaerated by compression and then finally compacted in the actual compacting station under a pressure of kg./sq. cm.

The compacted piece is expelled in the subsequent station and sent to a packaging station.

It is evident that in both cases of the washing soap and of the toilet-soap, other examples might be cited. Those skilled in the art may provide for changes and variations of the formulations for those substances covered hereby without departing from the principles and spirit of the invention.

By the above described process it is also possible to obtain manufactured products where particular ingredients are present having different colors from the color of the powder, in order to evidence the presence of said ingredient to the consumer.

It is for instance possible to obtain a manufactured product having any color in the mass of which are more or less uniformly distributed blue or green or yellow colored grains, or having any other color, said grains having an equal or different composition with respect of the remainder of the manufactured product.

These grains can be obtained by means of the well known dry or wet grain making processes and can have any detergent and/or bleaching and/or cleaning composition, previously mixed with a coloring agent.

Also other systems may be used, but regardless of how said colored grains are obtained, they must be mixed in a common mixer for powders, before compacting, with the ground detergent composition.

Having thus disclosed the invention, what is claimed is:

1. A process for preparing a dry, compacted detergent composition, said process comprising dry mixing the components of the detergent composition which are:

(a) from 0.5 to 35.0% of waterglass, wherein the ratio of Na O to Si0 is between 1.0:l.3 and 1.0:1.5; and

(b) at least one member of the group consisting of sodium tri-polyphosphate, sodium pyrophosphate, sodium orthophosphate, the sodium acid salts thereof, sodium carbonate, sodium sulphate, neutral sodium borate and acid sodium borate;

grinding the resulting mixture, deaerating the ground mixture to reduce the apparent volume of same by at least 25% and compacting same in a mold under a pressure of at least about 30 kg./sq. cm.

2. A process as claimed in claim 1 wherein the detergent composition further contains ammonium bicarbonate.

3. A process as claimed in claim 1 wherein the detergent composition further contains at least one member of the group consisting of sodium perborate and sodium percarbonate.

4. A process as claimed in claim 1 wherein the detergent composition further contains at least one member of the group consisting of dichloroisocyanuric acid, trichloroisocyanuric acid, alkaline earth metal salts thereof, lithium hypochlorite and calcium hypochlorite.

References Cited UNITED STATES PATENTS 2,607,738 8/1952 Hardy 252-102 2,801,978 8/1957 Perlman 252-137 2,979,464 4/1961 Pistor 252-99 3,247,122 4/1966 Schaafsan et a1. 252-174X 3,329,615 7/1967 Cooper et al 252-99 MAYER WEINBLA'IT, Primary Examiner US. Cl. X.R.