LIQUID CLEANING AGENT CONCENTRATE, READY-TO-USE SOLUTION, USES THEREOF AND CLEANING METHOD

Abstract

Liquid cleaning agent concentrate comprising: a. at least one phosphonate, b. a first complexing agent selected from aminopolycarboxylic acids, hydroxycarboxylic acids, hydroxypolycarboxylic acids and their salts, and c. at least one enzyme, preferably proteolytic enzyme, a pH of the liquid cleaning agent concentrate being 9 or >9. The invention also relates to a ready-to-use solution; to uses thereof for cleaning and/or disinfecting objects and to cleaning methods.

Claims

1.-17. (canceled)

18. A liquid cleaning agent concentrate comprising: a. at least one phosphonate, b. a first chelating agent selected from (hydroxyethyl)ethylenediaminetriacetic acid, methylglycinediacetic acid and salts thereof, c. a second chelating agent selected from (hydroxyethyl)ethylenediaminetriacetic acid, ethylenediaminetetraacetic acid, glutamic acid-N,N-diacetic acid, iminodisuccinic acid, methylglycinediacetic acid and salts thereof, where the first and second chelating agents are different from one another, and d. at least one enzyme, preferably proteolytic enzyme, wherein a pH of the liquid cleaning agent concentrate is 9 or >9.

19. The liquid cleaning agent concentrate as claimed in claim 18, characterized in that the liquid cleaning agent concentrate has a pH of 9-12, preferably 10-12, more preferably 10-11.

20. The liquid cleaning agent concentrate as claimed in claim 18, characterized in that the at least one phosphonate is selected from salts of phosphonobutanetricarboxylic acid (PBTC), of aminotrismethylenephosphonic acid (ATMP), of 1-hydroxyethane-1,1-diphosphonic acid (HEDP), of diethylenetriamine penta(methylenephosphonic acid) (DTPMP) and mixtures thereof.

21. The liquid cleaning agent concentrate as claimed in claim 18, characterized in that the phosphonate is the sodium salt of phosphonobutane tricarboxylic acid, of aminotrismethylenephosphonic acid, or a mixture thereof.

22. The liquid cleaning agent concentrate as claimed in claim 18, characterized in that the first chelating agent is the sodium salt of (hydroxyethyl)ethylenediaminetriacetic acid or the sodium salt of methylglycinediacetic acid.

23. The liquid cleaning agent concentrate as claimed in claim 18, characterized in that the liquid cleaning agent concentrate comprises the sodium salt of phosphonobutanetricarboxylic acid, the sodium salt of aminotrimethylenephosphonic acid or a mixture thereof as the phosphonate, the sodium salt of (hydroxyethyl)ethylenediaminetriacetic acid as the first chelating agent, and preferably the sodium salt of methylglycine diacetic acid as the second chelating agent.

24. The liquid cleaning agent concentrate as claimed in claim 18, characterized in that the liquid cleaning agent also comprises further constituents selected from surfactants, hydrotropes, alkanolamines, alkali metal hydroxides, solvents, corrosion inhibitors, fragrances and dyes.

25. The liquid cleaning agent concentrate as claimed in claim 18, characterized in that at least one of the following constituents is present in the liquid cleaning agent concentrate in the following proportions by weight in each case: the phosphonate or phosphonate mixture in a proportion by weight of 1 to 13% by weight, preferably of 2 to 10% by weight, based on the total mass of the liquid cleaning agent concentrate; the first chelating agent in a proportion by weight of 0.5 to 10% by weight, preferably of 1 to 8% by weight, based on the total mass of the liquid cleaning agent concentrate; the second chelating agent in a proportion by weight of 0.5 to 10% by weight, preferably of 1 to 8% by weight, based on the total mass of the liquid cleaning agent concentrate; the enzyme or enzyme mixture in a proportion by weight of 0.05 to 4% by weight, preferably 0.1 to 2% by weight, based on the total mass of the liquid cleaning agent concentrate.

26. A ready-to-use application solution comprising 0.05 to 99.9/a of the liquid cleaning agent concentrate as claimed in claim 18, wherein a pH of the ready-to-use application solution is 9 or >9.

27. The ready-to-use application solution as claimed in claim 26, characterized in that the liquid cleaning agent concentrate has a pH of 9-12, preferably 10-12, more preferably 10-11.

28. The use of the liquid cleaning agent concentrate as claimed in claim 18 for cleaning and/or disinfecting objects, preferably for machine cleaning and/or disinfecting objects.

29. The use as claimed in claim 28, characterized in that the objects are medical and/or surgical instruments and/or apparatuses.

30. The use as claimed in claim 28, characterized in that the liquid cleaning agent concentrate or the ready-to-use application solution is dispensed cold, preferably at a temperature of 38° C. or less, more preferably of 18 to 35° C., even more preferably of 20 to 30° C., still more preferably of 22 to 27° C., even more preferably at about 25° C.

31. A method for cleaning medical and/or surgical instruments and/or apparatuses, characterized by the following steps: a) preparing a ready-to-use application solution as claimed in claim 26, b) cleaning of the medical and/or surgical instruments and/or apparatuses with the ready-to-use application solution.

32. The method as claimed in claim 31, characterized in that the ready-to-use application solution is prepared cold, preferably at a temperature of 38° C. or less, more preferably of 18 to 35° C., further preferably of 20 to 30° C., still more preferably of 22 to 27° C., even more preferably at about 25° C.

Description

[0077] The invention will now be described by way of example on the basis of certain advantageous embodiments with reference to the accompanying drawings. Shown are:

[0078] FIG. 1: Corrosion tests with GG25 gray cast iron chips in accordance with DIN 51360 Part 2 at different concentrations of the application solutions (i.e. la) 10% and 1b) 5%)

[0079] FIG. 2: Current density-potential curves of the anodic partial reactions on test specimens of stainless steel grade 1.4034, wherein the measurements with the preparation (I) according to the invention, the preparation (II) without phosphonate and salt solutions of different pH values are shown as comparisons

[0080] FIG. 3: Current density-potential curves of the anodic partial reactions on test specimens of stainless steel grade 1.4031, wherein the measurements with the preparation (I) according to the invention, the preparation (II) without phosphonate and salt solutions of different pH values are shown as comparisons

[0081] FIG. 4: Position of corrosion potentials, i.e. current density minima, (top) and graphical results of the Tafel analysis with test specimens of stainless steel grade 1.4034 (bottom).

[0082] FIG. 5: Results of the immersion cleaning tests with the preparation (I) according to the invention and the preparation (II) without phosphonate as comparison, with heparinized sheep's blood as soiling.

[0083] FIG. 6: Cleaning performance of ready-to-use application solutions comprising phosphonate and MGDA with respect to sheep's blood when a second chelating agent is varied, plotted in comparison with log(K) literature values for Ca.sup.2+ and Mg.sup.2+.

[0084] FIG. 7: Cleaning performance and corrosion behavior of ready-to-use application solutions comprising phosphonate and MGDA with respect to sheep's blood when a second chelating agent is varied, plotted in comparison with log(K) literature values for Ca.sup.2+ and Mg.sup.2+.

[0085] FIG. 8: Pressure and temperature curves for cold water dispensing of a liquid cleaning agent concentrate according to the invention at a concentration of 3 ml/l at 25° C.

[0086] FIG. 9: Pressure and temperature curves for cold water dispensing of the cleaning agents known from the prior art and standard on the market at the respective standard recommended concentration at 25° C.

[0087] 1. PHOSPHONATE

[0088] 1. Corrosion Tests with GG25 Gray Cast Iron Chips in Accordance with DIN 51360 Part 2

[0089] Four different phosphonates (i.e. the sodium salts of ATMP, HEDP, PBTC, DTPMP) and two other chelating agents (i.e. sodium glucoheptonate, HEDTA) were investigated for their corrosion inhibition effect in equimolar ratios in an otherwise constant liquid cleaning formulation, the pH being adjusted if appropriate. For the assessment, corrosion tests were carried out with GG25 gray cast iron chips in accordance with DIN 51360 Part 2 at different concentrations of the application solutions (i.e. 10% and 5%).

[0090] a. Equipment and materials [0091] Petri dishes Ø 100 mm (glass or plastic) [0092] filter paper Ø 70 mm 589 from Whatman, ash-free, medium-fast filtration [0093] gray cast iron GG 25 chips according to DIN 51360 T2 (Riegger Industriehandel, Article 03-39) [0094] demineralized water

[0095] b. Procedure

[0096] Using a spatula, 2.0 g±0.1 g of the chips were weighed onto the filter paper placed in the Petri dish. The chips were distributed as centrally as possible over an area of Ø 40-50 mm. The chips and the filter paper were wetted evenly with 2 ml of the 10% or 5% ready-to-use application solution and the Petri dish was sealed with the lid. The samples prepared in this way were stored for 2 hours±10 minutes at room temperature (20-25° C.) without direct sunlight or drafts. The chips were removed and discarded. The filter paper was rinsed under running demineralized water and swivelled in acetone for 5-10 seconds. The filter paper was dried at room temperature (20-25° C.). The degree of corrosion was determined immediately after drying. Each test was carried out in duplicate.

[0097] c. Evaluation

[0098] For the evaluation, instead of a visual assessment, the surface area of the corrosion that occurred was related to the total surface area of the filter paper used. The integrals of the surface areas were determined using ImageJ software.

[0099] d. Result

[0100] FIG. 1 shows the results of the corrosion tests with GG25 gray cast iron chips in accordance with DIN 51360 Part 2 at different concentrations of the application solutions (sample 1: Na-ATMP, sample 2: Na-HEDP, sample 3: Na-PBTC, sample 4: Na-glucoheptonate, sample 5: Na-DTPMP, sample 6: Na-HEDTA; sample ref: comparison without additive), where FIG. 1a) shows the tests with 10% ready-to-use application solutions and FIG. 1b) shows the tests with 5% ready-to-use application solutions. In both cases, the best results were obtained with the ready-to-use application solutions containing Na-ATMP (Sample 1) and Na-PBTC (Sample 3).

[0101] 2. Investigations of pH

[0102] It was shown that the phosphonate acts as corrosion inhibitor. A further effect of the phosphonate can be observed with a systematic variation of other components, for example the chelating agent, with an otherwise constant composition of the cleaning agent concentrate.

TABLE-US-00001 TABLE 1 pH when varying chelating agents in the presence or absence of phosphonate (PBTC) pH pH Chelating agent without phosphonate with phosphonate HEDTA 12.6 10.9 EDDS 11.0 10.6.sup.1 IDS 11.7 10.9 GLDA 12.4 10.9 Polyaspartate 11.6 10.8 EDTA 12.6 10.9 MGDA 12.3 10.9 — 10.8 .sup.1raw material used only ¾ deprotonated

[0103] The pH is shown to be stable when phosphonate is present. If this is missing, considerable fluctuations in the pH are observed when the ingredients are varied, i.e. when different chelating agents are added (see Table 1). The phosphonate therefore not only serves as corrosion inhibitor in the liquid cleaning concentrate and the ready-to-use application solution, but also acts as a buffer.

[0104] 2. Combination of Phosphonate and Chelating Agent

[0105] Electrochemical corrosion measurements and immersion cleaning tests with heparinized sheep's blood were carried out.

[0106] To this end, two preparations were prepared. Preparation (I) is a liquid cleaning agent concentrate according to the invention, which was prepared from the following constituents: [0107] 3.5% by weight endoprotease [0108] 10% by weight 50% PBTC [0109] 8.5% by weight 45% KOH [0110] 6.0% by weight 40% MGDA, 3Na [0111] 6.0% by weight 40% HEDTA [0112] 0.5% by weight fatty alcohol alkoxylate C12-C15 having 2EO/4PO [0113] 3.2% by weight 42% Na-octyl sulfate [0114] 16% by weight 99% triethanolamine [0115] to 100% by weight water

[0116] Preparation (II) is a comparison without phosphonate having an otherwise identical formulation, where the pH is adjusted to be identical to preparation (I). Based on the tests carried out, the synergistic effect of the phosphonate in combination with aminopolycarboxylates as chelating agents can be clearly demonstrated.

[0117] 1. Electrochemical Corrosion Measurements

[0118] a. Measurement Method

[0119] In each case, the open circuit potential (OCP) of the system was first determined. This took place over a period of 600 s in order to ensure sufficient equilibrium. The current density-potential curve was then recorded over a potential range of −0.1 to +1.5 V in relation to the measured OCP. For this purpose, a step size of 0.001 V at a scanning speed of 0.01 V/s was set.

[0120] b. Procedure

[0121] To carry out the electrochemical corrosion experiments, a measurement set-up was used consisting of an Autolab PGSTAT204 potentiostat and a corrosion measuring cell for flat samples (Metrohm AG) having a three-electrode arrangement and a silver/silver chloride reference electrode. Ground stainless steel sheets of grades 1.4034 and 1.4301 were used as test specimens.

[0122] Electrochemical corrosion tests were carried out on test specimens of the two stainless steel grades 1.4034 (chromium steel; less corrosion-resistant; cf. FIG. 2) and 1.4301 (chromium-nickel steel; more corrosion-resistant; cf. FIG. 3). For this purpose, a 10% application solution of preparations (I) and (II) was prepared in a 0.9% solution of sodium chloride (corresponding to physical saline solution) in order to obtain the required corrosive conditions and current density-potential curves were recorded. The pH was 10.5 for preparation (I) with phosphonate and 11.5 for preparation (II) without phosphonate. Despite the lower pH of the application solution from preparation (I), the measurements showed lower corrosion currents than in the case of the phosphonate-free variant at higher pH (see FIG. 2). In principle, it would have been expected that the corrosion resistance of steels also increases with increasing pH, so that improved resistance at a comparatively lower pH also indicates a clear inhibition effect.

[0123] In order to be able to rule out that the pH is responsible for the observed behavior, further tests were carried out with salt solutions in which the pH was adjusted to 10.5 or 11.5 with potassium hydroxide solution. This corresponds to the measured pH of the two application solutions, but without constituents of the cleaning solutions being able to influence the corrosion behavior. A test with sodium chloride solution without pH adjustment was also carried out as reference (pH=7.9). The associated current density-potential curves (see FIG. 2) clearly show that the corrosion current decreases with increasing pH. Thus, as expected, a lower current can be observed at pH=11.5 compared to pH=10.5 and pH=7.9.

[0124] Especially in the test series with the less corrosion-resistant steel 1.4034 (cf. FIG. 2), the effects of the pH alone, and the additional effect of the two formulations, can be perfectly differentiated. Thus, the corrosion potentials and corrosion rates of the individual measurements determined by Tafel analysis also clearly depict here the effects described. These can be found in Table 2 below and in FIG. 4.

[0125] In the case of the NaCl solutions, the increasing pH resulted in a decrease in the corrosion rate and in a shift in the corrosion potential in the direction of more positive potentials. The addition of the application solutions enhanced both effects in the same pH range, with the variant according to the invention with phosphonate showing the corrosion potentials shifted the most towards more positive values, although the pH here is lower than in the comparative variant without phosphonate, as described above.

TABLE-US-00002 TABLE 2 Corrosion potentials and corrosion rates from the Tafel analysis of the corrosion experiments carried out, where the experiments of preparations (I) and (II) were each carried out as duplicate determinations (A) and (B). Corrosion potential Corrosion rate Steel 1.4034 [V] [mm/year] 0.9% NaCl −0.332 0.046 pH = 7.9 0.9% NaCl −0.289 0.006 pH = 10.5 0.9% NaCl −0.287 0.004 pH = 11.5 Preparation II −0.269 0.001 (A) Preparation II −0.238 0.001 (B) Preparation I −0.227 0.001 (A) Preparation I −0.221 0.001 (B)

[0126] 2. Cleaning Tests in the Immersion Bath

[0127] a. Equipment and Materials [0128] stainless steel plate (slightly roughened, surface area 1 cm×9 cm) [0129] sheep's blood heparinized with 10 IU/ml of protamine sulfate or protamine chloride: ACILA GmbH [0130] marker points Ø 8 mm green [0131] demineralized water

[0132] b. Procedure

[0133] Preparation of test plates heparinized reactivated sheep's blood:

[0134] The heparinized sheep's blood and the protamine sulphate/protamine chloride were stored in a climate cabinet at 6° C. until the test. For the preparation of the test soiling, the sheep's blood and the protamine sulfate/protamine chloride should have reached a temperature of 20° C. The grease-free stainless steel plates were clamped on a rack and should be aligned horizontally as straight as possible.

[0135] 75 μl of protamine sulfate or protamine chloride were briefly mixed with 5 ml of heparinized sheep's blood on a magnetic stirrer in a 50 ml glass beaker. 100 μl of this solution were pipetted onto each plate and distributed evenly with an inoculation loop without contaminating the mounting holes and the lateral surfaces. Each batch was then incubated for 1 hour at room temperature in water vapor-saturated air (100% air humidity RH). The rack of plates can be immersed in the demineralized water, but the plates must be stored above the water level. To set 100% RH, the bottom of an 8.5 liter plastic can was filled with at least 1 liter of demineralized water. The demineralized water must completely cover the bottom of the horizontally placed tray. The tray was covered with a lid at least 2 hours before the start (conditioning of the atmosphere). After 1 hour, the wet test specimens with the coagulated blood soiling were removed from the plastic tray and dried at room temperature.

[0136] The quality of the dry test plates was checked. Plates with air bubbles on the soiling or showing irregularities were excluded. A green marker dot was glued to each of the other plates. The test plates were stored in test tubes with screw caps at room temperature until use in the immersion test.

[0137] Immersion Test Procedure: [0138] Concentration: 2.5 ml/l [0139] Water quality: Demineralized water [0140] Temperature: 45° C.±1° C. [0141] Holding time: 4 min [0142] Stirring speed: 350 rev/min (IKA RCT classic stirrer) [0143] Test plate: heparinized, reactivated sheep's blood

[0144] Immersion cleaning tests were carried out with both test preparations at a dosage of 2.5 ml/l in demineralized water and a temperature of 45° C. with a contact time of 4 minutes. Four individual experiments were carried out with each formulation variant, the residue was stained with a 0.1% amido black solution and the area was determined. The mean values of the quadruplicate determinations are plotted in FIG. 3.

[0145] c. Evaluation

[0146] The evaluation was carried out visually with the dried plates. In addition, the evaluation was also carried out using the integrals of the remaining blood residues in relation to the total area of the test specimen with the aid of ImageJ software.

[0147] d. Results

[0148] FIG. 5 shows the results of the immersion cleaning tests with preparation (I) according to the invention and preparation (II) without phosphonate, where heparinized sheep's blood was used as soiling.

[0149] As FIG. 5 shows, a somewhat better cleaning result in the removal of heparinized sheep's blood was achieved with preparation (I) according to the invention than with the comparative preparation (II), which contains no phosphonate and only aminopolycarboxylates as chelating agents. In addition, the pH of the application solution of preparation (I) according to the invention, at 10.5, was even somewhat lower than that of the application solution of preparation (II), for which a pH of 10.7 was determined.

[0150] The liquid cleaning concentrate according to the invention and the ready-to-use application solution thereof of preparation (I), compared to the cleaning concentrate and the application solution thereof of preparation (II) without phosphonate, exhibit improved corrosion protection with respect to stainless steel, better material compatibility, for example with aluminum, and improved cleaning performance with respect to blood, despite a lower pH, which usually has the opposite effect. In addition, a buffering effect to the desired pH was observed due to the presence of the phosphonate over a wide concentration range.

[0151] 3. Combination of Chelating Agents

[0152] The chelating agent MGDA was combined in each case with a second chelating agent (i.e. HEDTA, EDDS, IDS, GLDA, polyaspartate, EDTA), in addition to the phosphonate PBTC contained in a liquid cleaning concentrate according to the invention, and the corrosion-inhibiting properties and the cleaning performance with respect to sheep's blood were investigated for all the test preparations of this series.

[0153] 1. Corrosion Tests

[0154] The corrosion tests were carried out with GG25 gray cast iron chips in accordance with DIN 51360 Part 2 at a concentration of the application solutions of 2.5%. The tests were carried out and evaluated analogously to the corrosion tests on the phosphonates described above.

[0155] 2. Cleaning Tests in the Immersion Bath

[0156] a. Equipment and materials [0157] stainless steel plate (slightly roughened, surface area 1 cm×9 cm) [0158] sheep's blood heparinized with 10 IU/ml of protamine sulfate or protaminechloride: ACILA GmbH [0159] marker points Ø 8 mm green [0160] demineralized water

[0161] b. Procedure

[0162] The test specimens with heparinized, reactivated sheep's blood were prepared as previously described.

[0163] Immersion Test Procedure: [0164] Concentration: 2.0 ml/l [0165] Water quality: Demineralized water [0166] Temperature: 45° C.±1° C. [0167] Holding time: 4 min [0168] Stirring speed: 350 rev/min (IKA RCT classic stirrer) [0169] Test plate: heparinized, reactivated sheep's blood

[0170] Immersion cleaning tests were carried out with both test preparations at a dosage of 2.0 ml/l in demineralized water and a temperature of 45° C. with a contact time of 4 minutes. Four individual experiments were carried out with each formulation variant, the residue was stained with a 0.1% amido black solution and the area was determined.

[0171] c. Evaluation

[0172] The cleaning results were evaluated visually with the dried plates. In addition, the evaluation was also performed here by integrating the area relative to other individual tests.

[0173] 3. Results of the Corrosion and Cleaning Tests

[0174] Firstly, it was observed that the selection of the second chelating agent has an influence both on the cleaning performance and on the corrosion behavior of the liquid cleaning agent (cf. FIGS. 6 and 7). Secondly, a reciprocal relationship between corrosion behavior and cleaning performance was found (cf. FIG. 7). Thus, improved corrosion protection results in deterioration of the cleaning effect and vice versa. A further correlation can also be observed between the cleaning performance and the complex stabilities (log(K)) of the chelating agents with Ca.sup.2+ and Mg.sup.2+ ions (cf. FIG. 6). The use of chelating agents with higher log(K) values results in improved cleaning performance in the ready-to-use application solution, while this deteriorates accordingly when chelating agents with lower stability constants are used. This relationship can be seen particularly clearly when all three parameters are arranged in ascending order when plotted against the mean value of the log(K) values for Ca.sup.2+ and Mg.sup.2+ ions (cf. FIG. 7).

[0175] 4. Cold Water Dispensing

[0176] In the prior art, enzymatic, mildly alkaline, liquid cleaning agents, which preferably comprise surfactants, are usually metered in at a water temperature of about 40° C. for machine cleaning. This is necessary because the cleaning agents tend to foam too much at lower temperatures. The disadvantage of dispensing at a temperature of about 40° C., however, is that the run time of the cleaning programs is prolonged, since there is initially a certain time delay for heating up from the inlet temperature (usually ca. 18-22° C.) to a temperature of 40° C. before the cleaning agent can take effect.

[0177] The liquid cleaning agent concentrate and the ready-to-use application solution according to the invention, in contrast, make it possible to carry out cold dispensing directly after the water inlet, preferably at a temperature of 38° C. or less, even more preferably of 18 to 35° C., even more preferably of 20 to 30° C., still more preferably of 22 to 27° C., even further preferably at about 25° C., without the program being aborted due to excessive foam development. This is currently not possible with the cleaning agents known from the prior art.

[0178] FIG. 8 shows the correct and complete program sequence (pressure and temperature curves) from a cleaning and disinfection system (UniClean PL II from MMM). Here, the liquid cleaning agent concentrate according to the invention was dispensed at a concentration of 3 ml/l at 25° C.

[0179] This was carried out analogously for some of the commercially available cleaning agents known from the prior art at the respective recommended standard concentration at 25° C. (inter alia Dr. Weigert, neodisher MediClean forte, 6 ml/l, #681964; Ruhof, Endozyme AW plus, 3.5 ml/l Dr. Schumacher, thermoshield Xtreme, 3 ml/l, #460764; Borer, deconex Twin pH10+Twin Zyme, 3 ml/l+1.5 ml/l, #0370073+#0.397577; Prolystica, Prolystica 2× concentrate alkaline cleaner, 3 ml/l, #290186). For these cleaning agents, a program termination is observed, as is shown in FIG. 9.