METHOD FOR THE PRODUCTION OF A SODIUM ION-FREE EFFERVESCENT TABLET, POWDER OR GRANULATE HAVING A HIGH X ION CONTENT, WHERE X CAN BE A VARIETY OF SUBSTANCES

Abstract

The process serves for preparing sodium ion-free X carbonate or hydrogencarbonate effervescent powder, such granules or such tablets. The active substances X, at least calcium carbonate, moistened with a small amount of alcohol and water, are mixed as powder with a small amount of lactobionic acid in a partial vacuum in a vacuum tank with continual pumping. As a result, the calcium salt (CaCO.sub.3) of the calcium in the surface layer of the powder particles reacts with the lactobionic acid, effervesces and releases a small amount of CO.sub.2. Consequently, the pressure in the vacuum tank rises and after the end of the effervescent reaction the internal pressure in the vacuum tank drops back to the starting value through the continual pumping. In so doing, the powder dries. After removal from the vacuum chamber an acid, preferably citric acid, as an effervescing agent is added, and subsequently the powder is electively pressed into tablets. The thus produced sodium ion-free calcium carbonate effervescent tablet hence contains at least calcium carbonate as well as citric acid as an effervescing agent, with the pressed particles having been initially effervesced in their surface layer by means of lactobionic acid.

Claims

1. A process for preparing a sodium ion-free X carbonate or hydrogencarbonate effervescent powder or such granules or such a tablet, wherein the active substances, corresponding at least to calcium carbonate, magnesium carbonate, magnesium hydrogencarbonate, potassium carbonate and potassium hydrogencarbonate or mixtures thereof, moistened with a small amount of alcohol and water, are mixed as powder with a small amount of lactobionic acid in a partial vacuum in a vacuum tank with continual pumping, by which the calcium salt of the calcium in the surface layer of the powder particles reacts with the lactobionic acid, effervesces, and releases a small amount of CO.sub.2, by which the pressure in the vacuum chamber rises, and after the end of the effervescent reaction the pressure in the partial vacuum drops back to the starting value through the continual pumping and in so doing the powder dries, and after removal from the vacuum chamber an acid as an effervescing agent for effervescing is added to said powder, and the latter is subsequently usable as effervescent powder or pressed into tablets.

2. The process for preparing a sodium ion-free X carbonate or hydrogencarbonate effervescent powder or such granules or such a tablet according to claim 1, characterized in that as X there is used calcium, magnesium or potassium or a mixture of said substances, and as an acid for effervescing there is used one or more of the following: citric acid, malic acid, succinic acid, fumaric acid, tartaric acid, ascorbic acid.

3. The process for preparing a sodium ion-free X carbonate or hydrogencarbonate effervescent powder or such granules or such a tablet according to claim 1, characterized in that there is moreover added potassium hydrogencarbonate which effervesces with the lactobionic acid and generates initial CO.sub.2, for starting and improving the water solubility of the calcium carbonate.

4. The process for preparing a sodium ion-free X carbonate or hydrogencarbonate effervescent powder or such granules or such a tablet according to claim 1, characterized in that the addition of lactobionic acid is effected several times in a partial vacuum, after which each time the pressure in the vacuum tank rises more slowly until the surface layer of the calcium carbonate is completely passivated, and then the vacuum-dried powder is removed from the vacuum tank and processed further.

5. A sodium ion-free X carbonate or hydrogencarbonate effervescent powder or such granules or such a tablet, prepared by the method according to claim 1, containing at least an X carbonate as well as an acid as an effervescing agent, and wherein the pressable powder particles or the particles pressed into an effervescent tablet are initially effervesced in their surface layer by means of lactobionic acid.

6. A sodium ion-free X carbonate or hydrogencarbonate effervescent powder or such granules or such a tablet, prepared by the method according to claim 1, wherein X in the carbonate is one of the following substances: calcium, magnesium or potassium or a mixture of said substances, and the acid as an effervescing agent for effervescing is one or more of the following: citric acid, malic acid, succinic acid, fumaric acid, tartaric acid, ascorbic acid, and wherein the pressable powder particles or the particles pressed into an effervescent tablet are initially effervesced in their surface layer by means of lactobionic acid.

7. A sodium ion-free X carbonate or hydrogencarbonate effervescent powder or such granules or such a tablet, prepared by the method according to claim 1, containing at least calcium carbonate and potassium hydrogencarbonate as well as citric acid as an effervescing agent, and wherein the pressable powder particles or the particles pressed into an effervescent tablet are initially effervesced in their surface layer by means of lactobionic acid.

8. The sodium ion-free X carbonate or hydrogencarbonate effervescent powder or granules or tablet according to claim 5, containing, along with optional further substances, at least calcium carbonate as well as calcium ion, and instead of sodium ion only lactobionic acid for solubilizing the calcium carbonate (CaCO.sub.3) powder surface, as well as citric acid for initial effervescing upon dissolution of the effervescent powder or effervescent tablet in water.

Description

[0017] The process according to the invention allows the preparation of effervescent tablets or effervescent granules that not only possess excellent storage stability but are also always constant in their quality since the reproducibility of the process is guaranteed at all times through the control of a number of reaction parameters. The process for preparing effervescent tablets or processable effervescent granules is effected through heat treatment at 30° C. to 100° C. from acid and hydrogencarbonate and/or carbonate together with the granulating liquid as the essential effervescent constituents. The powdery or grainy mixture is treated in a closed system in a partial vacuum, wherein the acid (a dosed amount of up to 7% by mass, based on the mass of the mixture, of lactobionic acid) is mixed with the necessary quantity of hydrogencarbonate and/or carbonate, and this mixture is thereupon mixed with a polar solvent such as water, alcohol, methanol, or mixtures thereof, and granulated. The vacuum treatment at a temperature of 30° C. to 100° C., preferably 40° C. to 80° C., leads to roughening of the surface layer of at least one of the reaction components or to conversion thereof to a dry state with faster solubility. A CO.sub.2 evolution arising therefrom due to the reaction that occurs causes the pressure in the vacuum tank to initially rise, up to a maximum of 1000 mbar (atmospheric pressure). From the pressure difference relative to the starting value of for example 10 mbar in the vacuum tank one can establish the volume and the mass of the released CO.sub.2. The heat treatment after the fast vacuum drying of the mixture in each case can be repeated until the distinct slowing-down of the reaction or decreased gas evolution indicates the end of the surface roughening.

[0018] The obtained aggregates are thereupon reduced to a desired particle size, furnished with the desired additives, where applicable, and then tableted into effervescent tablets by means of a tablet press.

[0019] The temperature at which the process according to the invention is carried out is not critical and best lies between 40 and 80° C. The negative pressure that is used should be as low as possible. Thus, the starting partial vacuum can have a pressure of for example 10 mbar. The polar solvent is preferably water, which is used in a quantity of 0.2 to 2% by mass, based on the weight of the mixture to be treated.

[0020] Carrying out the process according to the invention has shown that when using suitable concentrations of the reactants and suitable quantities of polar solvent only a portion of the reactants reacts, and that soon, after 10-20 minutes have passed, the reaction becomes distinctly slower. When the mixture that has been thus reacted and slowly stirred further is now abruptly dried, then this operation can be repeated under suitable conditions, it turning out upon repetition that the stated operation is slowed down because a large portion of the surface of the acid has already been passivated and made inert by alkali or alkaline earth salts. When the same reaction is now carried out a third time, then one can ascertain that almost no more reaction takes place, since the total surface is already passivated and the individual reactants are inherently buffered. There has thus arisen an inert mixture which no longer, or only very slowly, reacts even in contact with small quantities of polar solvents. It is obvious that the prepared mixtures in the dry state have very high stability even at higher temperatures, so that the entry of air moisture or a long storage at higher temperatures cannot bring about any further reactions.

[0021] Since according to the invention the released quantity of CO.sub.2 is ascertained, one can establish by way of simple stoichiometric calculations how much bicarbonate has been consumed or how much salt has been formed with the lactobionic acid. One is now readily able to determine, through suitable parameters such as for instance the stirring rate, the applied amount of moisture from e.g. water and alcohol, the grain size of the applied lactobionic acid, how much lactobionic acid reacts to acid salt on the surface thereof.

[0022] For example, if 40 kg of a reaction mixture is reacted in a closed 100 liter vessel, then the free space between mass and tank capacity will amount to about 50 liters depending on the bulk weight of the mass. If the vessel was evacuated before the reaction, then these 50 liters of free space will be practically gas-free. If a quantitatively determined amount of moisture is now made to flow into the mass with simultaneous stirring, then the corresponding carbon dioxide will fill the supernatant space of 50 liters. This filling of the space can be easily checked with a good manometer. Thus, if the initial partial vacuum was 10 mbar and the reaction has caused the pressure in the vacuum tank to rise to for example atmospheric pressure, then that means that about 50 liters of carbon dioxide have been produced.

[0023] It can now be calculated back how much lactobionic acid has in this case been consumed or how much lactobionate or how much citrate produced. Multiple repetition of the described vacuum treatment leads almost to a standstill of the reaction between the reactants, i.e. the lactobionic acid and the calcium salt of the calcium.

[0024] Even in the presence of polar solvents and despite the small quantities of reacted materials, hardly any reaction can be ascertained any more, so that after final drying of the product an exceptionally resistant but still reactive mass is obtained. The results are moreover strictly reproducible if the above-mentioned parameters are kept the same and guarantee the recovery of a product of unvarying quality.

[0025] As a theoretical explanation for the effect achieved by the process according to the invention it may be put forward that the contact areas of the reactants form buffer zones that are formed by different alkaline or alkaline earth salts of the corresponding acid. Said buffer zones will of course form depending on the surface of the individual crystals and on the reactivity.

[0026] Hereinafter an example with numbers will be given: In a 100 liter vacuum tank 29 kg of citric acid and 1 kg to 3 kg of lactobionic acid are provided and heated while stirring to 60° C. for 5 min, after which evacuation is briefly effected to 20 mbar in the vacuum tank for checking the residual moisture. After the vacuum is broken 10 kg of calcium carbonate is added, whereupon heating to 60° C. is again effected with further stirring. This mixture with the lactobionic acid then has a bulk weight per volume of approximately 1250 kg/m.sup.3, so that the space remaining in the vacuum tank amounts to about 50 liters. Then the tank is evacuated to 10 mbar, blocked off from the pump by means of a valve, and a quantity of 210 ml of water is introduced while stirring. Upon the now commencing reaction between the lactobionic acid and the hydrogencarbonate so as to form a passivating surface layer on the acid crystals and evolving CO.sub.2, the pressure in the vacuum tank rises from 10 mbar to 1000 mbar, which corresponds to a volume of released CO.sub.2 of 50 liters or, at a molar volume of the CO.sub.2 at 60° C. of 27.1 liters, to a mass of released CO.sub.2 of 81 grams.

[0027] From this it results that upon this first vacuum treatment a portion of the lactobionic acid reacted with the surface layer of the particles, that is, of the calcium salt of the calcium, and released CO.sub.2. The reaction time amounts to approx. 4 min. Now the treated product is dried and vacuum-treated, repeated under the same conditions and using 300 ml of water. In so doing, the pressure in the vacuum tank is made to rise to 1000 mbar again, corresponding to a volume of 50 liters or a mass of 81 grams of CO.sub.2. Due to the partial initial effervescence of the surface layer through the lactobionic acid achieved in the first treatment, the reaction time is substantially longer this time and amounts to about 10 to 30 minutes. The treated product is dried again and subjected to a third vacuum treatment, with only an insignificant pressure increase being measured because the lactobionic acid is used up, so that substantially no more CO.sub.2 generation takes place. The surface of the acid crystals is largely initially effervesced or has been passivated, that is, no further reaction takes place. The product is then dried and the obtained agglomerates can be reduced to the desired particle size and can be mixed with the desired additives such as flavoring materials, vitamins, sweeteners and the like. For later effervescing, an acid is added in the conventional way, preferably citric acid, but other acids such as malic acid, succinic acid, fumaric acid, tartaric acid or ascorbic acid, as well as mixtures of said acids, also work. These effervescent granules can be pressed into effervescent tablets by means of tablet presses in the known manner, where applicable.

[0028] The thus obtained product has excellent storage stability for long time periods even at tropical temperatures. The described pretreatment by means of lactobionic acid accelerates effervescing and makes it deep-acting because all the powder particles have been “initially effervesced”, that is, they offer a far greater surface for the later reaction with the admixed acid, for example citric acid, as soon as the effervescent tablet comes in contact with water.

[0029] When a thus prepared effervescent tablet is placed in water at ambient temperature, the water quickly penetrates into the surface layer of the powder particles and leads to an effervescent effect which effervesces the whole effervescent tablet quickly progressing toward the interior and dissolves it completely in water. After less than three minutes the effervescent tablet is completely dissolved and the solution is even clear.