Denture cleansing tablet.

Denture cleaning tablet

This invention relates to a cleaning tablet according to the preamble of the main claim for automatically cleaning dentures in aqueous solution.

Denture cleaning tablets, for example tablets of the type described in DE 2 133 710, are used in such a way that they are placed in water at the same time as the dentures to be cleaned and the cleaning tablet disintegrates, releasing more or less gas and releasing active substances .

Such cleaning tablets, such as DE patents 2 312 847, 2 548 469, 2 658 450 and 2 741 072, EP 0 010 412, 0 028 005 and 0 102 418, as well as EP applications 0 133 354, 0 149 308, 0 157 464 and 0 224 658 tablets contain, as their main constituents, oxygen-releasing substances for oxidation and disinfection (such as monopersulphates and / or perborates), inorganic softeners and lime binders (such as phosphates and / or polyphosphates), chelating agents such as EDTA, gaseous carriers such as carbonates and / or bicarbonates, citric acid 25, hydrophilic acid and aminosulfonic acid and their salts, such as disinfectants, disinfectants as well as lubricants, binders and / or disintegrants, surfactants, colorants and flavors. According to the composition, as the tablet dissolves in water, the pH values ​​fluctuate between acidic, neutral and basic values. They are usually fast-cleaning tablets, i.e. tablets with a cleaning time of 10 to 15 minutes. In some cases, however, they are slow-acting tablets with relatively long periods of use, in which case the complete cleaning effect on the dentures to be treated is only achieved after about 1-2 hours.

With regard to the cleaning of dentures, all the above-mentioned tablets suffer from a weakness typical of the composition and the method of use. The formation of perborate oxygen in the desired active form via the HOO ion only occurs satisfactorily at temperatures above 60 ° C. However, the user usually cleans the dentures in 10 to 15 minutes at a temperature of approximately 3040 ° C, so that in the case of known cleaning tablets, a considerable part of the desired oxidizing and disinfecting effect of the oxygen-releasing agents is not realized.

EP-A-0 253 772 describes a cleaning tablet of the above-mentioned type in which the phosphate combination forms a phosphorus compound which promotes or participates in the purification process while using a polymeric fluorocarbon as a binder. When such a hydrophobic fluorocarbon is used, the problem is not only that the dissolution of the cleaning tablet becomes difficult to dissolve due to the hydrophobic nature of the hydrocarbon, but also that the tablet floats in the cleaning liquid in an insulating manner and therefore slows down the cleaning process. The use of such a polymeric hydrophobic binder makes it clear why, in the case of the cleaning tablet according to EP 0 253 772, a high activator content is used, 5-15% by weight, which leads to a reduction in the proportion of actual cleaning active substances. As mentioned, known inorganic phosphates also use inorganic phosphates, which, like EDTA, act as a metal-binding agent, but which cannot be considered fully acceptable due to the potential environmental effects.

It is an object of the present invention to provide a so-called fast cleaning tablet of the above-mentioned type which, while guaranteeing the stability and activity of the tablet by means of a suitable stabilizer, eliminates the need for a hydrophobic, non-cleaning binder or environmentally suspicious inorganic polyphosphates (EDTA / NTA and NLS).

According to the invention, this problem is solved by the features set forth in the characterizing part of the main claim. Particularly preferred embodiments of the invention are the subject of the subclaims.

The invention is based on the surprising finding that it is possible to overcome the above-mentioned problems of known cleaning tablets by using organic phosphonic acid as a metal-binding agent and a peroxide stabilizer, thus avoiding the need for a hydrophobic polymeric binder. At the same time, it is a hydrolysis-resistant example of an alkali metal and heavy metal complexing agent and replaces environmentally problematic phosphates / polyphosphates and EDTA, which have been used as inorganic complexing agents in hitherto known denture cleaners. When the cleaning tablet dissolves, the inert polymer does not retain peroxide, but this is stabilized by the substance contained in the cleaning tablet, which has the effect of removing catalyst toxins or the like in the water during dissolution, so as to prevent negative effects on the activator. According to the invention, the activator content must be about 0.5 to 3.0% by weight, so that it is possible to increase the percentage of active substances in the cleaning tablet. This is also made possible by the fact that in the cleaning tablet according to the invention the amount of polyphosphate, which is usually 5-10 parts in the previous cleaning tablets, can be replaced by only one part of the phosphonates due to the high activity of the activator.

The fact that the peroxide and activator have full effect in the cleaning liquid, which does not contain external material, for example in the form of floating hydrophobic polymers, ensures that the full activity of the peroxide is maintained throughout the cleaning cycle, e.g. 15 minutes. According to a preferred embodiment of the invention, tetraacetylethylenediamine (TAED) is used as an activator, which makes it possible to significantly increase and stabilize the release of active oxygen in a form which is desirable for cleaning and antimicrobial activity, through the formation of highly active peracetic acid.

The hydrolysis-resistant organic phosphoric acids or their salts used according to the invention have a strong metal-binding effect and in particular an iron-binding effect and at the same time a dispersing / deflocculating effect. The advantageous equipping of the cleaning tablet with a toner system of the type according to the claims makes it possible to follow the series of cleaning events optically until the end of the main cleaning and also of the entire cleaning process. In this embodiment, a quantitative decrease in color intensity occurs during the cleaning process, followed by a qualitative color change before the color disappears.

The cleaning tablet according to the invention is characterized in that it does not contain environmentally questionable inorganic phosphates, polyphosphates or organic complexing agents based on aminocarboxylic acids (for example EDTA). The cleaning and antimicrobial effect is insensitive to temperature in the range of application, i.e. the tablet can be used with an optimal cleaning effect in the temperature range of 25 to 45 ° C.

As a result of the perborate activator used in the cleaning tablet of the present invention, a reaction mechanism is initiated in the aqueous solution, which can be represented in a simplified form as follows:

a) [ΒϊΟβΗΤΡ '· 2Na + ---) 2Na B0₂ + 2H₂O₂ perborate monohydrate hydrogen peroxide

b) H₂O₂ + 0H ~_< - »HaO + H00 o-

c) -XC = O + HOO'f = ± -XC-OOH

II ¹⁵ ch₃ ch₃

Acetyl group of the activator

<td></td><td> 0' |</td><td>0 II</td>

<td>d)</td><td>1 -XC-OOH 1 ch₃</td><td>i1 HjOj XH + | cH₃-C-OOH | + - OH peracetic acid</td>

<img file="FI89939B_D0001.tif" />

Acetic acid

Active oxygen

It is important that peracetic acid is formed as an intermediate, which then decomposes into acetic acid and oxygen. Thus, the release of activated oxygen from the perborate results in a significantly improved cleaning effect.

The antimicrobial effect of the cleaning tablet according to the invention, which is achieved by means of a perborate-peroxy-30 deactivator with peracetic acid as an intermediate, also exceeds expectations. It turns out that even in the case of high dilution rates and a short exposure time, sterility is achieved. The particular composition of the cleaning tablet may be varied according to the objectives set by those skilled in the art. In order to obtain bacterial-free cultures after 48 hours of incubation, in the case of peracetic acid, a concentration of 0.0020.005% by weight is sufficient to achieve an action time of 2-10 minutes for conventional test bacteria (Escherichia coli, Staphylococcus aureus. Streptococcus mutans. Pseudomonas aeruginosa, Proteus vulgaris, B ) to kill them. The same is true for hyphomycetes and blastomycetes (Trichophyton rubrum, Candida albicans). Even in the case of known resistant enteroviruses, the use of the cleaning tablet according to the invention requires a much lower concentration due to the presence of peracetic acid than the H₂O₂in the case of.

Most known denture cleaning formulations contain inorganic phosphates and polyphosphates as well as aminocarboxylic acid-based organic complexing agents such as EDTA and NTA for lime binding and dispersion, while the cleaning tablet of the invention does not require any such additives. This is advantageous because polyphosphates are sensitive to hydrolysis, i. they hydrolyze in aqueous solution, which involves the formation of orthophosphate and thus lose their dispersing effect, whereas EDTA has no dispersing effect from the beginning. It should also be borne in mind that inorganic phosphates and EDTA, for example, are not fully acceptable from an environmental point of view, as one of them causes problems by increasing the number of oxygen-consuming plants in water bodies and the other due to their difficult degradability.

85939

In the case of the cleaning tablet according to the invention, the above-mentioned environmentally problematic product groups are kept out of the entire composition. Highly effective lime and metal binding agents in the form of organic complexing agents based on phosphonic acid or its salts, used for the first time in the denture cleaning tablets of this invention, are hydrolysis resistant, have an anti-corrosion effect and enhance the cleaning process. because they, in synergistic cooperation with the perborate activator, stabilize the oxygen-releasing agent or oxygen release and at the same time have good dispersing and deflocculation properties.

Virtually all known, commercially available denture cleaning tablets require warm water and some even water at 50 ° C as a cleaning fluid. This is necessary for most conventional formulations to dissolve the active oxygen of the peroxide in a timely manner. However, other disadvantages have to be accepted, such as faster hydrolysis, reduced dispersion / deflocculation, reduced corrosion resistance, etc. The action of the peroxide activator stabilizer and the phosphonic acid-based hydrolysis-resistant organic complexing agent according to the invention, as well as the elimination of easily hydrolyzable inorganic polyphosphates, ensure that the cleaning tablet according to the invention does not suffer from the above-mentioned disadvantages. It is also fully effective from room temperature and does not require hot water, which has been necessary until now. Therefore, the user does not have to worry about achieving a cleaning and disinfecting effect or el when following the manufacturer's instructions for using a warm cleaning fluid.

To date, it has not been possible to monitor organoleptically with known cleaning tablets

39939 or visually the progress and end of the cleaning process. Even with the known bilayer tablets, only the pre-cleaning interval can be monitored, while the end of the main and final cleaning is not obvious to the user. The colors of the tablets used so far (e.g., blue or pink) appear long after the end of the washing process when using glassware, even if the goal is some other effect.

However, by using the color system proposed according to the invention, the problems hitherto encountered with respect to the optical monitoring of the cleaning process can be eliminated. In this case, a reduction-oxidation-sensitive dye having a relatively low oxidation potential is used in combination with a dye of a different color which is independent of the reduction-oxidation potential. The protons released as a result of the oxidation of the impurities and a certain release of protons from the other substances in the tablet lead to a quantitative decrease in the color intensity, followed by a qualitative color change before the color disappearance occurs. The temporal duration of the series of events depends on the degree of dirtiness of the dentures as well as partly on the temperature and pH of the water. In virtually all cases, it is possible to optically detect the end of the main cleaning step, whereby a color change occurs, and the end of the cleaning process, which is optimized to achieve the desired exposure time, whereby the color disappears completely. This can be done according to the invention with various suitable color systems and using the combination of the disodium salt of indigotine disulfonic acid and the disodium salt of quinophthalodisulfonic acid according to the invention a turquoise green color is obtained. The color intensity decreases during the cleaning process and then the color turns greenish yellow (main cleaning end point) before the color disappears (cleaning end point).

The composition of the cleaning tablet according to the invention may be in the following range:

Sodium perborate monohydrate Potassium monopersulphate Sodium hydrogen carbonate Sodium carbonate

Sodium sulfate

Citric acid or citrate salts and other similar organic acids or their salts Tetra-acetylethylenediamine and other peroxide activators having a similar effect

Organic phosphonic acid or its salts Polyethylene glycol 20,000 Polyvinylpyrrolidone

Silica (Aerosil 200/300) Sodium dodecylbenzenesulphonate, disodium salt of ricinyl monoethanolamide sulphosuccinate or similar surfactants Cured triglycerides

Fatty alcohol polyglycol ethers Preservatives / stabilizers Peppermint powder or other flavorings (eg eucalyptus) Color system (eg indigotina L-blue 2 and quinoline yellow L-yellow 3)

Weight-%

-30

-40

-30

-10

-10

- 20

0,3 - 3

0,5 -3

-4,5

0-3

0,5-1,5

0,2 - 1,5

0-2

0,5 - 2

0-2

1-2

0,05 - 0,35

The cleaning tablet according to the invention is described below with respect to a specific embodiment:

<td> 30</td><td>weight-%</td>

<td> 20</td><td>weight-%</td>

<td> 20</td><td>weight-%</td>

<td> 5</td><td>weight-%</td>

<td> 4</td><td>weight-%</td>

<td> 7</td><td>weight-%</td>

sodium perborate monohydrate potassium monopersulphate sodium hydrogen carbonate sodium carbonate sodium sulphate sodium salt of citric acid

1.5% by weight of tetraacetylethylenediamine

1.5% by weight of organic phosphonic acids or their salts 4% by weight of polyethylene glycol 20,000

1.5% by weight of polyvinylpyrrolidone

1.5% by weight of Aerosil 200/300

0.75% by weight of sodium dodecylbenzenesulfonate% by weight of fatty alcohol polyglycol ether

0.5% by weight of cured triglycerides by weight of preservative

0.5% by weight of peppermint powder

0.25% by weight as indigo L-blue 2 and quinoline yellow

L yellow 3

The above ingredients were compressed in powder or granular form using known methods to form a cleaning tablet. After dissolving the resulting cleaning tablet, the pH of the cleaning solution was 9.0 at 30 ° C. The progress of the cleaning process could be monitored optically by a corresponding color change and was complete after about 10 minutes.