WO2012025160A1

WO2012025160A1 - Liquid cleaner for automated instrument processing

Info

Publication number: WO2012025160A1
Application number: PCT/EP2010/062566
Authority: WO
Inventors: Laurence Geret; Carola Stingl; Silke Denzin
Original assignee: Ecolab Inc.
Priority date: 2010-08-27
Filing date: 2010-08-27
Publication date: 2012-03-01
Also published as: EP2609185B1; EP2609185A1

Abstract

The present invention relates to a liquid alkaline composition for cleaning metal surfaces, comprising at least one alkaline source, at least one disilicate corrosion inhibitor, at least a first sequestering agent, and at least one solvent, wherein the weight ratio of the disilicate to the sequestering agent is in the range from 0.1 : 1 to 1 : 1, and the weight ratio of the alkaline source to the sequestering agent is in the range from 0.01 : 1 to 1 : 1. The liquid alkaline composition provides an enhanced removal of blood and/or protein soils and prevents corrosion of metal surfaces.

Description

Liquid cleaner for automated instrument processing

Field of the Invention

The invention relates to a liquid alkaline cleaning compositions and methods for automated cleaning processing of surfaces with effective cleaning compositions. In particular, the invention relates to liquid alkaline cleaning compositions useful in the cleaning of articles or surfaces, including metal articles or metal surfaces, such as surgical, medical, and dental instruments.

Background of the Invention

Many commercial and domestic articles include surface metal layers. Such articles are known to those skilled in a variety of occupations or domestic activities, particularly those working in industrial plants, hospitals, maintenance and repair services, manufacturing facilities, kitchens, restaurants and the like. Surgical, medical, and dental instruments after use are typically contaminated with blood and other body matter and potentially with infectious microorganisms. Before being reused in a future procedure these instruments must be washed and disinfected where indicated.

Aqueous alkali cleaners are known as effective cleaning agents. However, many such alkali cleaners have disadvantages when used for automated cleaning processing due to the formation of foam, thus requires the content of additional foam inhibiting agents, which make the composition more complex. The formation of foam lowers the cleaning properties, due to the loss of mechanical agitation. Further, pumping of foam dramatically reduce the liquid flow rates, thus causes dosing and transport problems in the sump, liquid conduits, as well as in the dispensing drawer. Thus, foam is not acceptable in an automated washer.

Many articles having a surface that requires cleaning contain an alkaline sensitive metal, such as, aluminum or aluminum containing alloys. Exemplary equipment having a surface containing an alkaline sensitive metals include surgical, medical, and dental instruments, sinks, cookware, utensils, machine parts, vehicles, tanker trucks, vehicle wheels, work surfaces, tanks, immersion vessels, spray washers, and ultrasonic baths. Aqueous alkali cleaners are known as effective cleaning agents. However, many alkali cleaners have disadvantages when used on alkaline sensitive metals, such as, aluminum. A problem with using aqueous alkali systems to clean aluminum surfaces is the potential to corrode and/or discolor.

Further, blood-containing soils are of significant economic importance to several industries including healthcare and meat processing plants in particular. Dried blood on instruments is hazardous to the employees of the hospital and to the next surgical patient upon which the instruments are used. The danger of handling instruments contaminated with blood is obvious in this age of hepatitis and HIV. Cleaning dried blood is much more difficult than cleaning other soils. Blood-containing soils are particularly tenacious and difficult to remove for at least three reasons.

First, red blood cell surfaces are hydrophobic and therefore difficult to wet with aqueous use solutions of detergents.

A second reason for the tenacity of blood-containing soils resides with hemoglobin that has limited water solubility and also contains iron. Iron is particularly difficult to remove from surfaces whether it is an automobile with iron-containing soil adhered to the surface, or a dental instrument with blood on the surface.

A third reason for difficulty in removal of blood-containing soils lies in the fact that blood-containing soils contain fibrin. Fibrin is a protein involved in the clotting of blood. It is a fibrillar protein that is polymerized to form a 'mesh' that forms a haemostatic plug or clot (in conjunction with platelets) over a wound site. This 'mesh' formation is a result of intermolecular cross-linking of cysteine in the protein. While it is desirable and necessary for clot formation, it also acts to make blood-containing stains all the more tenacious.

The fibrin jams itself into microscopic irregularities in the surface of instrumentation and fabric. This is a physical attachment to the surface through mechanical means, not just chemical means as with traditional adhesives. The action is similar to the roots of plants growing into cracks in rocks, anchoring themselves to the surface.

The approach to removal of blood soils to date has primarily relied upon the use of high levels of caustic. However, there are drawbacks to using high amounts of caustic to clean delicate metal instrumentation. The foremost reason to avoid high amounts of caustic is that the cleaning composition may erode the metal thereby ruining the instruments instead of cleaning them. Another drawback is the exposure of the caustic to human skin. That is, the person engaged in the cleaning duty is exposed to the high alkalinity detergent that is at least irritating to human skin and eyes.

It is still a need in prior art to provide a liquid alkaline composition for automated cleaning processing of hard and/or soft surfaces that is metal-safe. Further, it is a need to provide a liquid alkaline composition for automated cleaning processing of metal surface layers to remove blood, protein soils and other matter are allowed to dry, that provides an improved cleaning effect and shows practical no foam formation during the automated processing and prevents corrosion of metal surfaces that are exposed to the liquid alkaline solutions.

Summary of the Invention

The object of the present invention is to provide a liquid alkaline composition for automated cleaning processing of hard and/or soft surfaces, comprising:

at least one alkaline source,

at least one disilicate corrosion inhibitor,

at least a first sequestering agent, and

at least one solvent, wherein

the weight ratio of the disilicate to the sequestering agent is in the range from 0.1 : 1 to 1 : 1, and the weight ratio of the alkaline source to the sequestering agent is in the range from 0.01 : 1 to 1 : 1.

The liquid alkaline composition of the invention is a concentrated solution. The concentrated solution can be further diluted by admixing a solvent, preferably water. This diluted liquid alkaline composition obtained from the liquid alkaline composition of the invention is referred to as "ready-to-use" solution.

The ratio of components is the weight ratio, if not otherwise indicated in the specification.

The formation of foam lowers in particular the cleaning properties, due to the loss of mechanical agitation. Further, pumping of foam dramatically reduce the liquid flow rates, thus causes dosing and transport problems in the sump, liquid conduits, as well as in the dispensing drawer. Thus, foam is not acceptable in an automated washer. It has surprisingly found that the liquid alkaline cleaning composition of the invention is remarkable sensitive to metal surfaces; it provides an improved cleaning effect and shows practical no foam formation during the automated cleaning processing.

The "phrase" alkaline sensitive metal" identifies those metals that exhibit corrosion and/or discoloration when exposed to an alkaline solution. An alkaline solution is a solution having a pH that is > 8. Exemplary alkaline sensitive metals include soft metals such as aluminum, nickel, tin, zinc, copper, brass, bronze, and mixtures thereof. Aluminum and aluminum alloys are common alkaline sensitive metals that can be cleaned by the cleaning compositions of the invention.

Disilicate is a silicate compound that has two silicon atoms in the molecule. A solvent, preferably water, can be added add. 100 wt.-% to the composition of the invention. The water content of the composition according to the invention is simply determined by subtracting the amounts of all the usual components from 100 wt. %.

The weight amount (wt.-%) is calculated on the total weight amount of the liquid alkaline composition, if not otherwise stated. The total weight amount of all components of the liquid alkaline composition does not exceed 100 wt.-%.

It should be understood that the liquid alkaline composition of the invention can be free of surfactant/s, such as nonionic tensides, anionic tensides, cationic tensides and amphoteric tensides.

It should be understood that the liquid alkaline composition of the invention can be free of a hydrotrope component.

It should be understood that the liquid alkaline composition of the invention can be free of a phosphate.

It should be understood that the liquid alkaline composition of the invention can be free of a mono silicate.

It should be understood that the liquid alkaline composition of the invention can be free of at least one additive, preferably all additives, selected from the group of

antimicrobials, fungicides, fragrances, dyes, antistatic agents, UV absorbers, reducing agents and/or buffering compounds.

The combination of an alkaline source in combination with a tenside leads to a foam formation, thus not very suitable for use in an automated cleaning processing. However, surfactants, such as nonionic tensides, anionic tensides, cationic tensides and amphoteric tensides are known to have an improved cleaning effect.

Surprisingly, it has been found that the use of a sequestering agent instead of a surfactant provides an excellent cleaning effect on metal surfaces. Further, replacing the surfactant by a sequestering agent provides no or practical no foam formation when used for automated cleaning processing.

Moreover, it has been found that the use of disilicates in the composition of the invention compared to monosilcates avoids deposit as well as deposit corrosion inside a cleaning chamber of an automated cleaning apparatus and on the surface of articles processed therein. The deposit can be a colored residue that remains preferably on surfaces inside the cleaning chamber. The use of disilicates in the liquid alkaline composition of the invention overcomes this drawback. In particular, if the liquid alkaline composition of the invention is free of a surfactant. The specific weight ratio of the disilicate to the sequestering agent according to the present invention provides a good cleaning effect, no or practical no deposit of colored residue is observed even after a number of cleaning processes in combination with no or practical no foaming as required for an automated processing of metal surfaces. In order to provide a good cleaning action and no or practical no deposit of colored residue the weight ratio of disilicate to sequestering agent can be in the range from 0.20 : 1 to 0.8 : 1, preferably

0.25 : 1 to 0.75 : 1, further preferred 0.30 : 1 to 0.70 : 1, also preferred 0.35 : 1 to 0.65 : 1, more preferred 0.40 : 1 to 0.60 : 1, furthermore preferred 0.45 : 1 to 0.55 : 1, and most preferred 0.50 : 1 to 0.53 : 1.

At the time of dissolution with water, a spontaneous foam formation in the dispensing draw of an apparatus for cleaning processing as well as in the cleaning chamber is observed, if surfactants are used. Further, nonionic tensides known to be of low foaming degrade under alkaline conditions and an increased foam formation is observed.

However, if the weight ratio of the surfactant, such as nonionic tenside, anionic tenside, cationic tenside and/or amphoteric tenside, is selected low to reduce foam formation, the cleaning action is insufficient.

According to the present invention, at least one sequestering agent having a good cleaning activity and no or practical no tendency of foam formation can be used. The weight ratio of alkaline source to sequestering agent can be adjusted in the range from 0.1 : 1 to 0.4 :

1, preferably 0.15 : 1 to 0.35 : 1, further preferred 0.20 : 1 to 0.30 : 1, and also preferred 0.23 : 1 to 0.26 : 1. None significant foam formation is observed at a weight ratio of alkaline source to sequestering agent in the range from 0.1 : 1 to 1 : 1, if used as liquid solution, preferably as an aqueous solution, in the dispensing draw of an apparatus for cleaning processing as well as in the cleaning chamber .

Due to none or marginal foam formation the automated pumping flow rate of water- dissolved composition according to the present invention is not affected.

Further, the cleaning and disinfection action of the liquid alkaline composition of the present invention used in an automated washing process is surprisingly good, even if no surfactants are used. Especially, body fluids, such as blood, lipids and synovial fluids from joints adhere to the items metal surface used during a procedure. As these fluids dry, the adhesion gets stronger and the fluids get harder to dissolve using ordinary cleaning methods. Blood in particular becomes much more difficult to remove once it has dried. Eventually, the adhesion of the soils becomes too strong for normal detergents to break and the instruments remain soiled after cleaning. A problem with using aqueous alkali systems to clean metal surfaces, such as aluminum surfaces, especially eloxadized aluminum, is the potential to corrode and/or discolor. The liquid alkaline composition of the present invention is surprisingly extremely mild and reduces this effect to a minimum. According to an embodiment of the invention an additional second corrosion inhibitor can be used to further prevent corrosion of metal surfaces that are exposed to liquid, preferably aqueous, alkaline solutions.

It should be understood that the second corrosion inhibitor is optional and can be omitted.

A preferred embodiment of the liquid alkaline composition according to the invention can comprise:

- at least one alkaline source,

- at least a first disilicate corrosion inhibitor,

- at least a second corrosion inhibitor,

- at least a first sequestering agent, and

- at least one solvent, wherein the weight ratio of the disilicate to the sequestering agent is in the range from 0.1 : 1 to 1 : 1, and the weight ratio of the alkaline source to the

sequestering agent is in the range from 0.01 : 1 to 1 : 1.

The soil removal or cleaning action of an aqueous solution of the liquid alkaline composition according to the present invention can be achieved by adding at least one sequestering agent to the liquid alkaline composition, preferably at least one sequestering agent that exhibits soil removal properties. However, according to one embodiment of the invention a second sequestering agent can be added. It has been surprisingly found that the addition of sodium gluconate as second sequestering agent may increase the cleaning effect of the liquid alkaline composition of the invention. Thus, most preferred, as the second sequestering agent is sodium gluconate.

- at least one alkaline source,

- at least a first disilicate corrosion inhibitor,

- at least a first sequestering agent,

- sodium gluconate as a second sequestering agent, and - at least one solvent, wherein the weight ratio of the disilicate to the sequestering agent is in the range from 0.1 : 1 to 1 : 1, and the weight ratio of the alkaline source to the sequestering agent is in the range from 0.01 : 1 to 1 : 1.

Another preferred embodiment of the liquid alkaline composition according to the invention can comprise:

- at least one alkaline source,

- at least a first disilicate corrosion inhibitor,

- at least a second corrosion inhibitor,

- at least a first sequestering agent,

- sodium gluconate as a second sequestering agent, and

- at least one solvent, wherein the weight ratio of the disilicate to the sequestering agent is in the range from 0.1 : 1 to 1 : 1, and the weight ratio of the alkaline source to the sequestering agent is in the range from 0.01 : 1 to 1 : 1.

In order to improve the cleaning effect and to minor the potential of the liquid alkaline composition to corrode and/or discolor metal surfaces due to the cleaning process a water conditioner can be added.

- at least one alkaline source,

- at least one disilicate corrosion inhibitor,

- at least a first sequestering agent,

- sodium gluconate as a second sequestering agent,

- at least one water conditioner, and

- at least one alkaline source,

- at least a first disilicate corrosion inhibitor,

- at least a second corrosion inhibitor,

- at least a first sequestering agent,

- sodium gluconate as a second sequestering agent, - at least one water conditioner, and

A liquid alkaline composition of the present invention that provides an increased cleaning effect and is in addition remarkable mild to eloxadized aluminum, may comprises a defined weight ratio of sodium gluconate to the water conditioner in the range from 1 : 1 to 20 : 1, further preferred 5 : 1 to 15 : 1, also preferred 8 : 1 to 12 : 1 and most preferred 9 : 1 to 10 : 1.

at least one alkaline source,

at least one disilicate corrosion inhibitor,

at least a first sequestering agent,

sodium gluconate as a second sequestering agent,

at least one water conditioner, and

at least one solvent, wherein

the weight ratio of the sodium gluconate to the water conditioner is in the range from 1 : 1 to 20 : 1, further preferred 5 : 1 to 15 : 1, also preferred 8 : 1 to 12 : 1 and more preferred 9 : 1 to 10 : 1.

A liquid alkaline composition according to the present invention that is extremely mild, that means that corrosion is reduced to a minimum, having an improved cleaning effect with respect to metal surfaces to be processed therewith and has no tendency with respect to foam formation at processing can be a liquid alkaline composition that comprises:

> 0.1 wt.-% to < 6 wt.-%, preferably > 0.5 wt.-% to < 5 wt.-%, further preferred > 1 wt.- % to < 4 wt.-%, also preferred > 1.5 wt.-% to < 3 wt.-%,and more preferred > 2 wt.-% to

< 2.5 wt.-%, of at least one alkaline source;

> 1 wt.-% to < 10 wt.-%, preferably > 1.5 wt.-% to < 8 wt.-%, further preferred > 2 wt.- % to < 6 wt.-%, also preferred > 3 wt.-% to < 4 wt.-%, and more preferred > 3.5 wt.-% to

< 3.75 wt.-%, of at least one disilicate;

> 5 wt.-% to < 10 wt.-%, preferably > 6 wt.-% to < 9 wt.-%, further preferred > 7 wt.-% to < 8 wt.-%, and more preferred > 7.4 wt.-% to < 7.6 wt.-%, of at least one first sequestering agent; > 0 wt.-% to < 40 wt.-%, preferably > 5 wt.-% to < 35 wt.-%, further preferred > 10 wt.- % to < 30 wt.-%, also preferred > 15 wt.-% to < 27 wt.-%, and more preferred > 20 wt.-% to < 25 wt.-%, sodium gluconate as a second sequestering agent;

> 0 wt.-% to < 10 wt.-%, preferably > 1 wt.-% to < 5 wt.-%, further preferred > 1.5 wt.- % to < 3 wt.-%, and more preferred > 2 wt.-% to < 2.5 wt.-%, of at least one water conditioner;

- > 0 wt.-% to < 1 wt.-%, preferably > 0.05 wt.-% to < 0.8 wt.-%, further preferred > 0.1 wt.-% to < 0.5 wt.-%, and more preferred > 0.2 wt.-% to < 0.3 wt.-%, of at least one corrosion inhibitor;

and solvent is added add. 100 wt.-%; wherein the weight % of the components are based on the total weight of the composition.

According to the invention, a liquid alkaline composition can be preferred comprising a first corrosion inhibitor, namely a disilicate and a second corrosion inhibitor that is a triazole derivate. The combination of said first and second corrosion inhibitor can improve the performance of the liquid alkaline composition of the present invention as already mentioned before. A preferred composition that contains said first and second corrosion inhibitor can be a liquid alkaline composition that comprises:

< 2.5 wt.-%, of at least one alkaline source;

< 3.75 wt.-%, of at least one disilicate;

- > 0 wt.-% to < 1 wt.-%, preferably > 0.05 wt.-% to < 0.8 wt.-%, further preferred > 0.1 wt.-% to < 0.5 wt.-%, and more preferred > 0.2 wt.-% to < 0.3 wt.-%, of at least one heterocyclic compound, preferably a triazole derivate;

> 5 wt.-% to < 10 wt.-%, preferably > 6 wt.-% to < 9 wt.-%, further preferred > 7 wt.-% to < 8 wt.-%, and more preferred > 7.4 wt.-% to < 7.6 wt.-%, of at least one first sequestering agent;

> 0 wt.-% to < 40 wt.-%, preferably > 5 wt.-% to < 35 wt.-%, further preferred > 10 wt.- % to < 30 wt.-%, also preferred > 15 wt.-% to < 27 wt.-%, and more preferred > 20 wt.-% to < 25 wt.-%, sodium gluconate as a second sequestering agent; - > 0 wt.-% to < 10 wt.-%, preferably > 1 wt.-% to < 5 wt.-%, further preferred > 1.5 wt.-% to < 3 wt.-%, and more preferred > 2 wt.-% to < 2.5 wt.-%, of at least one water conditioner; and

solvent is added add. 100 wt.-%; wherein the weight % of the components are based on the total weight of the composition.

Alkaline Source

The source of alkalinity can be any source of alkalinity that is compatible with the other components of the cleaning composition and that will provide the use solution, i.e. solution as well as the ready-to-use solution with the desired pH. Exemplary sources of alkalinity include alkali metal hydroxides, alkali metal salts, phosphates, amines, and mixtures thereof.

Exemplary alkali metal hydroxides include sodium hydroxide, potassium hydroxide, and lithium hydroxide.

Exemplary alkali metal salts include sodium carbonate, trisodium phosphate, potassium carbonate, and mixtures thereof.

Exemplary phosphates include sodium pyrophosphate, potassium pyrophosphate, and mixtures thereof.

Exemplary amines include alkanolamine selected from the group comprising triethanolamine, monoethanolamine, diethanolamine, and mixtures thereof.

The source of alkalinity, preferably an alkali metal hydroxide, may be added to the composition in a variety of forms, dissolved in an aqueous solution or a combination thereof. Alkali metal hydroxides are commercially available as pellets or beads having a mix of particle sizes ranging from 12-100 U. S. mesh, or as an aqueous solution, as for example, as a 45 wt. %, 50 wt. % and a 73 wt. % solution.

Corrosion Inhibitor

Mono silicates, comprising sodium mono silicate, have a tendency to begin

precipitating from aqueous solution at a pH below 11, thus reducing its effectiveness to prevent corrosion of the contacted surfaces when used in liquid, preferably aqueous, alkaline cleaning solutions having a lower pH. Additionally, when mono silicates are allowed to dry on the surface to be cleaned, films or spots are often formed, which are visible and which are themselves very difficult to remove. The presence of these mono silicate-containing deposits can affect the texture of the cleaned surface, the appearance of the surface, and on cooking or storage surfaces, can affect the taste of the materials that come into contact with the cleaned surfaces. Therefore, it can be preferred that the liquid alkaline composition of the present invention is free of mono silicates.

However, it has been found that a first corrosion inhibitor, namely a disilicate(s) corrosion inhibitor can be used in the liquid alkaline composition according to the present invention. The disilicate(s) corrosion inhibitor can be an alkali disilicate, particularly preferably crystalline or amorphous alkali disilicates in quantities of > 0.05 wt.-% to < 10 wt- %, preferably > 0.1 wt.-% to < 8 wt.-%, further preferred > 1 wt.-% to < 6 wt.-%, also preferred > 2 wt.-% to < 5 wt.-%, especially preferred > 3 wt.-% to < 4.5 wt.-%, and more preferred of > 3.75 wt.-% to < 4 wt.-%; based on the weight of the liquid alkaline

composition.

Suitable disilicates can have the formula NaMSi_x022x+i .yH20 and are marketed for example by Clariant GmbH (Germany) under the trade names Na-SKS. Crystalline, layered silicates of the above formula, in which x stands for 2, are particularly suitable for the purposes of the present invention. Na-SKS-5 (alpha -Na2Si205), Na-SKS-7 (beta -Na2Si205, Natrosilit), Na-SKS-9 (NaHSi205.H20), Na-SKS-10 (NaHSi205.3H20, Kanemit), Na-SKS- 11 (t-Na2Si205) and Na-SKS- 13 (NaHSi205) are most notably suitable, particularly Na- SKS-6 (delta -Na2Si205). In the context of the present application, silicates can comprise a content by weight of crystalline layered silicates of formula NaMSix02x+l .yH20 of 0.1 to 20 wt. %, preferably 0.2 to 15 wt. % and particularly 0.4 to 10 wt. %, each based on the total weight of the corrosion inhibitor agent.

Particularly preferred are especially those that can have a total silicate content > 1 and < 7 wt.- %, advantageously below 6 wt.- %, preferably below 5 wt.- %, particularly preferably below 4 wt.- %, quite particularly preferably below 3 wt. -% and especially below 2.5 wt.- %, wherein this silicate, based on the total weight of the comprised silicate, is advantageously at least 70 wt.- %, preferably at least 80 wt.- % and especially at least 90 wt.- % of a silicate of the general formula NaMSix02x+l .yH20. It should be understood that a silicate(s) corrosion inhibitor that have a total silicate content of < 2 and/or > 2 is optional and can be omitted.

In order to improve its effectiveness to prevent corrosion of the contacted surfaces when used in liquid, preferably aqueous, alkaline cleaning solutions an additional second corrosion inhibitor can be used. The second corrosion inhibitor can be a heterocyclic compound, preferably a triazole derivate. The triazole derivate can be selected from the group comprising benzotriazole, 1,2,3-benzotriazole and mixtures thereof. An aqueous alkaline composition having a high pH are often more corrosive than an aqueous composition having a light acidic pH. In order to minimize the potential to corrode and/or discolor the metal surface, the pH of the aqueous alkaline solutions of the liquid alkaline composition can be adjusted to a lower pH in the range of > 11 pH to < 13 pH and preferably to pH of 12.

However, other corrosion inhibitors can be suitable added to the liquid alkaline composition of this invention include magnesium and/or zinc ions and Ca (N0₂) ₂. Preferably, the metal ions are provided in water-soluble form.

Examples of useful water-soluble forms of magnesium and zinc ions are the water- soluble salts thereof including the chlorides, nitrates and sulfates of the respective metals. If any of the alkalinity providing agents are the alkali metal carbonates, bicarbonates or mixtures of such agents, magnesium oxide can be used to provide the Mg ion. The magnesium oxide is water soluble and is a preferred source of Mg ions.

In order to maintain the dispersibility of the magnesium and/or zinc corrosion inhibitors in aqueous solution, and in the presence of agents which would otherwise cause precipitation of the zinc or magnesium ions, e. g. , carbonates, phosphates, etc. , it might be advantageous to include a carboxylated polymer to the solution.

The useful carboxylated polymer corrosion inhibitors may be generically categorized as water-soluble carboxylic acid polymers such as polyacrylic and polymethacrylic acids or vinyl addition polymers, in addition to the acid-substituted polymers used in the present invention.

Of the vinyl addition polymer corrosion inhibitors contemplated, maleic anhydride copolymers as with vinyl acetate, styrene, ethylene, isobutylene, acrylic acid and vinyl ethers are examples.

The polymers tend to be water-soluble or at least colloidally dispersible in water. The molecular weight of these polymers may vary over a broad range although it is preferred to use polymers having average molecular weights ranging between 1,000 up to 1,000, 000. These polymers have a molecular weight of 100,000 or less and between 1,000 and 10,000.

The polymers or copolymers (either the acid- substituted polymers or other added polymers) may be prepared by either addition or hydro lytic techniques. Thus, maleic anhydride copolymers are prepared by the addition polymerization of maleic anhydride and another comonomer such as styrene. The low molecular weight acrylic acid polymer corrosion inhibitors may be prepared by addition polymerization of acrylic acid or its salts either with itself or other vinyl comonomers.

Alternatively, such polymers may be prepared by the alkaline hydrolysis of low molecular weight acrylonitrile homopolymers or copolymers.

It should be understood that other corrosion inhibitors, with the exception of the first corrosion inhibitor namely disilicate and the second corrosion namely a heterocyclic compound, preferably a triazole derivate, can be omitted.

Water conditioner

The liquid alkaline composition according to the present invention can comprise at least one water conditioner. The amount of water conditioner can be > 0 wt.-% to < 10 wt.-%, preferably > 1 wt.-% to < 5 wt.-%, further preferred > 1.5 wt.-% to < 4 wt.-%, and more preferred > 2 wt.-% to < 3 wt.-%, based on the weight of the liquid alkaline composition.

The water conditioner can be selected from the group comprising salts of

phosphonocarboxylic acids, phosphonates, salts of 1 -hydro xyethylidene -1,1,-diphosphonic acid (HEDP), salts of acid substituted polymers, and mixtures thereof, preferably salts of acid substituted polymers of monomers of acrylate, methacrylate, salts of polyitaconic acid, salts of polymaleic acid, and mixtures thereof. In particular preferred are salts of polyacrylic acid.

Sequestering Agent

The liquid alkaline composition according to the present invention can comprise at least one sequestering agent. The amount of sequestering agent can be > 5 wt.-% to < 10 wt.- %, preferably > 6 wt.-% to < 9 wt.-%, further preferred > 7 wt.-% to < 8 wt.-%, and more preferred > 7.4 wt.-% to < 7.6 wt.-%, based on the weight of the liquid alkaline composition.

The first sequestering agent can be selected from the group of pentasodium salt of diethylenetriamine pentaacetic acid, sodium glucoheptonate, salts of ethylene diamine tetraacetic acid, sodium salt of ethylene diamine tetraacetic acid, salts of hydro xyethyl ethylene diamine triacetic acid, sodium salt of hydro xyethyl ethylene diamine triacetic acid, salts of nitrilotriacetic acid, sodium salt of nitrilotriacetic acid, diethanolglycine sodium salt, ethanoldiglycine disodium salt, salts of hydro xymonocarboxylic acid compounds, sodium salt of hydroxydicarboxylic acid compounds, salts of amine containing carboxylic acids, salts of N,N-bis(carboxylatomethyl)-L-glutamate and mixtures thereof, preferably the first sequestering agent is selected from the group of salts of N,N-bis(carboxylatomethyl)-L- glutamate (GLDA), salts of nitrilotriacetic acid (NT A), salts of ethylene diamine tetraacetic acid and mixtures thereof. Most preferred can be sodium salts of the before mentioned first sequestering agents.

Sodium gluconate can be used as second sequestering agent.

In particular preferred is at least one sequestering agent that exhibits soil removal properties when used at a pH of at least 10.0. The sequestering agent is provided for tying up metals in the soil to assist in cleaning and detergency. The sequestering agent can be provided as part of the liquid alkaline composition. Exemplary sequestering agents that exhibit soil removal properties at a pH of greater than 10.0 that can be used according to the invention include sodium gluconate, pentasodium salt of diethylenetriamine pentaacetic acid (available under the name Versenex 80), sodium glucoheptonate, ethylene diamine tetraacetic acid (EDTA), salts of ethylene diamine tetraacetic acid, hydroxyethyl ethylene diamine triacetic acid (HEDTA), salts of hydroxyethyl ethylene diamine triacetic acid, nitrilotriacetic acid (NT A), salts of nitrilotriacetic acid, diethanolglycine sodium salt (DEG), ethanoldiglycine disodium salt (EDG), tetrasodium N,N-bis(carboxylatomethyl)-L-glutamate (GLDA), and mixtures thereof. Exemplary salts of ethylene diamine tetraacetic acid include disodium salts, tetrasodium salts, diammonium salts, and trisodium salts. An exemplary salt of hydroxyethyl ethylene diamine triacetic acid is the trisodium salt.

It should be understood that the sequestering agent can include mixtures of different sequestering agents.

Solvents

Suitable solvents include, but are not limited to, water, alcohols, glycols, glycol ethers, esters, and the like, or combinations thereof. Suitable alcohols include, but are not limited to, ethanol, propanol, isopropanol (propan-2-ol), 2-butoxy ethanol (butyl glycol), 1-decanol, benzyl alcohol, glycerin, monoethanolamine (MEA), and the like, or mixtures thereof.

Suitable glycols include, but are not limited to, ethylene glycol (monoethylene glycol or MEG), diethylene glycol (propylene glycol or butoxy diglycol or DEG), triethylene glycol (TEG), tetraethylene glycol (TETRA EG), glycerin, propylene glycol, dipropylene glycol, hexylene glycol, and the like, or combinations thereof.

Liquid Alkaline Ready-To-Use Composition

Another object of the present invention is directed to a liquid ready-to-use alkaline composition. The liquid ready-to-use alkaline composition can be obtained from the liquid alkaline composition of the invention by adding additional solvent, preferably water, thereto. It can be preferred that the ready-to-use solution is directly prepared at the place of use. For example, the liquid alkaline composition of the invention is filled into a storage tank of the cleaning apparatus. At the time of use, at least a portion of the liquid alkaline composition of the invention is piped to the place of use, such as the cleaning chamber or cleaning drum, wherein the liquid alkaline composition of the invention is further diluted with a solvent, preferably water, before or at the time, it arrives the place of use. For example, the liquid alkaline composition of the invention can be diluted with additional solvent, such as water, to obtain the ready-to-use solution, in a dispensing draw or dispensing tank of a cleaning apparatus. However, the liquid alkaline composition of the invention can be used without being diluted to a ready-to-use solution.

Using a concentrated solution, such as the liquid alkaline composition of the invention, which is further diluted at the time of use has the advantage, that the concentrated solution is less bulky compared to the more diluted ready-to-use solution. Thus, total weight, transport volume as well as storage volume of the liquid alkaline composition of the invention is reduced thus facilitates the handling for the user.

The cleaning compositions according to the invention can take the form of a single concentrate or multiple concentrates that can be diluted and combined to provide a ready-to- use solution, and as a ready-to-use solution that can be used to clean articles having a metal surface, such as surgical, medical, and dental instruments, including endoscopes.

The liquid alkaline composition of the invention can be in the form of a concentrate that can be diluted with a solvent, such as alcohol and/or water, to provide a ready-to-use solution that can be used for cleaning applied to articles having a metal surface, such as surgical, medical, and dental instruments.

In addition, the ready-to-use solution can be provided as a relatively dilute solution that can be, without the addition of water, to provide an organic ready-to use solution, for example an alcohol based ready-to use solution, that can be for cleaning applied to articles having a metal surface, such as surgical, medical, and dental instruments.

As already mentioned before, it is advantageous to provide the liquid alkaline composition of the invention as a concentrate and then to dilute the concentrate at the situs of use in order to decrease transportation costs associated with transporting large amounts of solvent, such as water.

The liquid alkaline composition of the invention and/or the ready-to-use solution obtained there from can be used in an automated washing process for cleaning and disinfection metal surfaces, in particular metal surfaces of surgical, medical, and dental instruments including endoscopes, from body fluids, such as blood, lipids, contrast agent and synovial fluids from joints adhere to the metal surface used during a procedure.

Aqueous Solution

The source of alkalinity and addition of solvent, such as water, are provided so that the aqueous solution of the liquid alkaline composition according to the present invention

(concentrated solution) may have a pH in the range of > 11 pH to < 13 pH, preferably a pH in the range of > 11.5 pH to < 12.5 pH and more preferred a pH of 12 pH.

The source of alkalinity and addition of solvent, such as water, are provided so that the ready-to-use solution of the liquid alkaline composition according to the present invention may have a pH in the range of >10 pH to 12 pH and preferably a pH in the range of > 11 pH to < 11.5 pH.

In order to obtain to provide the ready-to-use aqueous solution, additional solvent, preferably water, can be added to further dilute the liquid alkaline composition of the invention. Thus, the aqueous solution of the liquid alkaline composition according to the present invention can be further diluted with a solvent to the desired concentration of the ready-to-use solution, wherein the weight ratio for the dilution, i.e. added solvent (weight) : liquid alkaline composition (weight), can be in the range of from 800 : 1 to 1 : 1, preferably 700 : 1 to 10 : 1, further preferred 600 : 1 to 20 : 1, also preferred 550 : 1 to 30 : 1, more preferred 500 : 1 to 40 : 1, in particular preferred 450 : 1 to 40 : 1, especially preferred 400 : 1 to 50 : 1, and most preferred 350 : 1 to 60 : 1. However, the weight ratio for the dilution, i.e. added solvent (weight) : liquid alkaline composition (weight), can be 340 : 1 to 70 : 1, 335 : 1 to 80 : 1, 330 : 1 to 90 : 1 , 325 : 1 to 100 : 1, 320 : 1 to 110 : 1, 320 : 1 to 120 : 1, 310 : 1 to 130 : 1, 300 : 1 to 140 : 1, 290 : 1 to 140 : 1, 250 : 1 to 150 : 1.

However, it can be preferred that the ready-to-use solution is a > 0.1 wt.-% to < 1 wt.- %, preferably > 0.2 wt.-% to < 0.9 wt.-%, further preferred > 0.3 wt.-% to < 0.8 wt.-%, also preferred > 0.4 wt.-% to < 0.7 wt.-%, > 0.5 wt.-% to < 0.6 wt.-%, diluted solution of the liquid alkaline composition of the invention.

According to one embodiment of the invention, the ready-to-use liquid alkaline composition may comprises:

> 0.0003 wt.-% to < 0.2 wt.-%, preferably > 0.0005 wt.-% to < 0.1 wt.-%, further preferred > 0.0007 wt.-% to < 0.08 wt.-%, also preferred > 0.0009 wt.-% to < 0.07 wt.-%, also preferred > 0.001 wt.-% to < 0.075 wt.-%, in particular preferred > 0.003 wt.-% to < 0.07 wt.-%, especially preferred > 0.005 wt.-% to < 0.06 wt.-%, and more preferred > 0.003 wt.-% to < 0.06 wt.-%,of at least one alkaline source;

> 0.003 wt.-% to < 0.03 wt.-%, preferably > 0.0045 wt.-% to < 0.024 wt.-%, further preferred > 0.006 wt.-% to < 0.018 wt.-%, also preferred > 0.009 wt.-% to < 0.012 wt.-%, and more preferred > 0.01 wt.-% to < 0.01 wt.-%, of at least one disilicate;

> 0.015 wt.-% to < 0.03 wt.-%, preferably > 0.018 wt.-% to < 0.027 wt.-%, further preferred > 0.021 wt.-% to < 0.024 wt.-%, and more preferred > 0.022 wt.-% to < 0.023 wt.-%, of at least one first sequestering agent;

> 0 wt.-% to < 0.12 wt.-%, preferably > 0.015 wt.-% to < 0.10 wt.-%, further preferred > 0.03 wt.-% to < 0.09 wt.-%, also preferred > 0.045 wt.-% to < 0.08 wt.-%, and more preferred > 0.06 wt.-% to < 0.075 wt.-%, sodium gluconate as a second sequestering agent;

> 0 wt.-% to < 0.03 wt.-%, preferably > 0.003 wt.-% to < 0.015 wt.-%, further preferred

> 0.0045 wt.-% to < 0.009 wt.-%, and more preferred > 0.006 wt.-% to < 0.0075 wt.-%, of at least one water conditioner;

- > 0 wt.-% to < 0.003 wt.-%, preferably > 0.00015 wt.-% to < 0.002 wt.-%, further

preferred > 0.0003 wt.-% to < 0.0015 wt.-%, and more preferred > 0.0006 wt.-% to < 0.001 wt.-%, of at least one corrosion inhibitor;

According to a preferred embodiment of the invention, the ready-to-use solution may comprises:

> 0.0003 wt.-% to < 0.1 wt.-%, preferably > 0.0005 wt.-% to < 0.09 wt.-%, further preferred > 0.0007 wt.-% to < 0.08 wt.-%, also preferred > 0.0009 wt.-% to < 0.07 wt.-%, also preferred > 0.001 wt.-% to < 0.075 wt.-%, in particular preferred > 0.003 wt.-% to < 0.07 wt.-%, especially preferred > 0.005 wt.-% to < 0.06 wt.-%, and more preferred > 0.003 wt.-% to < 0.06 wt.-%,of at least one alkaline source, preferably sodium hydroxide;

- > 0.015 wt.-% to < 0.03 wt.-%, preferably > 0.018 wt.-% to < 0.027 wt.-%, further

preferred > 0.021 wt.-% to < 0.024 wt.-%, and more preferred > 0.022 wt.-% to < 0.023 wt.-%, of at least one first sequestering agent; > 0 wt.-% to < 0.12 wt.-%, preferably > 0.015 wt.-% to < 0.10 wt.-%, further preferred > 0.03 wt.-% to < 0.09 wt.-%, also preferred > 0.045 wt.-% to < 0.08 wt.-%, and more preferred > 0.06 wt.-% to < 0.075 wt.-%, sodium gluconate as a second sequestering agent;

preferred > 0.0003 wt.-% to < 0.0015 wt.-%, and more preferred > 0.0006 wt.-% to < 0.001 wt.-%, of at least one heterocyclic compound, preferably a triazole derivate; and solvent is added add. 100 wt.-%; wherein the weight % of the components are based on the total weight of the composition.

Manufacture of Liquid alkaline composition

There are a number of processes known in prior art to provide a liquid product. For example, all components of the liquid alkaline composition of the invention as well as the ready-to-use solution can be mixed together or added portionwise or one after the other.

Cleaning Device

Another object of the invention is directed to a cleaning device. The cleaning device is used to clean and to disinfect metal and/or plastic articles, preferably articles having a metal and/or plastic surface, such as surgical, medical, and dental instruments.

The cleaning device may include at least a first tank to receive the liquid alkaline composition of the invention; optional at least a second component tank to receive the ready- to-use solution of said liquid alkaline composition of the invention, a water feed, and at least one solution line.

The first component tank is provided for containing the liquid alkaline composition of the invention. The first component tank can be provided for mixing water to the liquid alkaline composition to provide the ready-to-use solution. The liquid alkaline composition can be mixed with a solution, preferably water.

The optional second component tank can be provided for receiving the liquid alkaline composition of the invention for mixing with a solvent, preferably water, to provide the alkaline ready-to-use solution.

According to a preferred embodiment the cleaning device can comprise: (a) at least a first container comprising an alkaline liquid alkaline composition according to claims 1 to 12 having a pH of > 11 to < 13, preferably a pH of > 11,5 to < 12,5 and more preferred a pH of 12;

(b) a solution line for conveying solution from a container to an applicator and/or to the place of use.

The ready-to-use solution or the liquid alkaline composition of the invention can be in any form including liquid, gel and slurry.

The cleaning solutions, i.e. ready-to-use solution and/or the liquid alkaline

composition of the invention, are suitable to treat any metal surface contaminated with a wide variety of contaminants.

Exemplary contaminants include body fluids, such as blood, lipids and synovial fluids and chemical residues.

The aqueous cleaning solutions of this invention, i.e. the aqueous alkaline ready-to-use solution and/or the liquid alkaline composition of the invention, may be used at any temperature, including an elevated temperature of from about 30° C to 70° C, preferably 45° C to 60° C and more preferred 55° C. After contact with the cleaning solution, the solution is removed from the metal surface.

The contact time of the liquid alkaline composition of the invention or preferably the ready-to-use solution in an automated process with the metal substrates will vary depending upon the degree of contamination but broadly will range between a few seconds or > 1 minute to < 30 minutes, with > 3 minutes to < 15 minutes being more typical and most preferred is > 5 minutes to < 10 minutes.

The following examples are presented to help to illustrate the invention and should not be construed as limiting the invention.

Example

The following examples El, CI and C2 were carried out to illustrate the improved cleaning effect, especially the enhanced removal of blood and/or protein soils of the liquid alkaline composition of the invention.

The following examples El, CI and C2 were carried out to illustrate the enhanced metal-surface-safeness with respect to corrosion of the liquid alkaline composition of the invention.

The following examples E2 to E13 were carried out to illustrate the none foaming characteristic of the liquid alkaline composition of the invention. Cleaning Efficiency Test Method

This test method provides a basis to assess the cleaning efficiency of instruments whose metal surface is contaminated with blood soils.

Equipment

600 ml beakers for each test condition

Transparent plastic sticks

Acetone

Pillar

Single use pipette

Spattle

Stainless steel test plates of 40 mm x 50 mm x 1mm (V2A)

(The stainless steel test plates are cleaned with acetone before use)

Clean paper toweling

Stop watch

Drying oven

Analytical balance capable of weighing to the 0.0001 place Blood sample

9.5 ml of heparinized sheep blood was added with a single use pipette into a test tube.

Subsequent 0.335 ml HPLC-water was added and the resulting composition was mixed.

Before use, 0.135 ml protamine sulfate was added thereto and mixed. Thereafter 0.2 g blood soil were immediately placed with a single use pipette on the stainless steel test plates (V2A) and the blood soil is equally arranged all over the upper surface of the stainless steel test plates (V2A) by means of a spattle. However, an area of 3 mm along the outer edges of said metal test plate surface is spared, i.e. not contaminated with blood soil. Subsequently the blood soil covered stainless steel test plates (V2A) were dried in a drying oven at 45° C for 1 hour and allowed to cool at room temperature for 20 minutes. Thereafter the blood covered metal plates were scaled and the weight of each blood soil contaminated stainless steel test plates (V2A) were recorded.

Test method The liquid cleaning composition El according to the invention and comparative compositions CI to C2 (see table 1) were diluted with deionized water to a 0.3 wt.-% ready-to-use solution. In each 600 ml beaker 400 ml of the ready-to-use solutions El, CI and C2 were added respectively. Subsequently, in each 600 ml beaker said blood soil contaminated stainless steel test plate (material = V2A) was completely submerged in the liquid cleaning solution, upright placed and arrange on the bottom of the beaker in a pillar so that the contaminated area is completely exposed to the liquid cleaning composition. Further, a transparent plastic stick secured the top of the metal plate. The blood soil contaminated stainless steel test plate (V2A) were allow to stay each at a determined time and temperature as given in table 2. Thereafter the so treated blood soil contaminated stainless steel test plate (V2A) were completely dipped 5 x times for 7 seconds into a 1000 ml beaker with deionized water and placed on clean paper allowed to dry for 30 minutes. Subsequently, the so treated blood soil covered stainless steel test plates (V2A) were dried in a drying oven at 45° C for 1 hour and allowed to cool at room temperature for 20 minutes. Thereafter, said treated blood soil contaminated stainless steel test plates (V2A) were scaled to determined the blood removal effectiveness, see table 2.

Table 1

Liquid cleaning composition El of the invention and comparative compositions CI to C2

= Britesil C 205

^*2 = 1,2,3 benzotriazole

^*3 = Tetrasodium N,N-bis(carboxylatomethyl)-L-glutamate (GLDA)

*⁴ = Sodium gluconate = alkyl polyglycosides based on natural fatty alcohol C₈-C₁₄, such as Glucopon 650 EC available by Cognis.

Table 2

Ready-to-use solutions

Material Compatibility Test

This test method provides a basis to assess the enhanced metal-surface-safeness of the liquid alkaline cleaning composition of the invention with respect to corrosion.

Corrosion testing equipment

350 ml wide-necked screw cap flasks for each test condition

Acetone

Aluminum test plates of 100 mm x 50 mm x 1.5 mm

(The aluminum test plates are cleaned with acetone before use)

Clean paper toweling

Stop watch

Drying oven

Analytical balance capable of weighing to the 0.0001 place. Test method

The cleaning compositions El and C2 of table 1 were diluted with deionized water to a 0.8 wt.-% ready-to-use solution. The weights of two aluminum test plates of 100 mm x 50 mm x 1.5 mm were recorded and then placed in the center area of the bottom of a 350 ml wide- necked screw cap flask each. The aluminum test plates were completely submerged.

Subsequently, each wide-necked screw cap flask was filed to the top with said 0.8 wt.-% ready-to-use solution El and C2 having a temperature of 23° C. The wide-necked screw cap flasks were closed with the cap and allow staying for 7 days at a temperature of 23° C.

Thereafter, the aluminum test plates were removed, rinsed with deionized water, placed on a clean paper towel and allowed to dry at a temperature of 23° C. The aluminum test plates were then weighted and the weight was taken to the fourth place. Subsequently the aluminum test plates were returned in there wide-necked screw cap flasks for another 7 days. Thereafter, the aluminum test plates were removed, rinsed with deionized water, placed on a clean paper towel and allowed to dry at a temperature of 23° C. The aluminum test plates were then weighted and the weight was taken to the fourth place. Subsequently the aluminum test plates were returned again in there wide-necked screw cap flasks for another 7 days. The weight loss was calculated. Three test were run for each experiment and the average weight loss was determined.

Table 3

Corrosion test results of the ready-to-use solutions

Foam Formation Test

This test method provides a basis to assess the foam formation properties of the liquid alkaline cleaning composition of the invention. Foam testing equipment

250 ml long-necked glass cylinder

Rubber stopper to close the long-necked glass cylinder

Test method

The cleaning compositions E2 to E13 of table 4 were diluted with deionized water to a 1.0 wt.-%, ready-to-use solution, to a 0.8 wt.-% ready-to-use solution, to a 0.5 wt.-% ready-to-use solution, and to a 0.3 wt.-% ready-to-use solution. Each long-necked glass cylinder was filed with 100 ml of the ready-to-use solution of 23° C respectively. The long-necked glass cylinder was then turned up and down 20 x times in 20 seconds. Thereafter the glass cylinder was placed and the foam depth of each cylinder was scaled in ml to determine the foam formation.

For none of said tested ready-to-use solutions a foam formation could be observed. Thus, the liquid alkaline cleaning solution of the invention is a non-foaming composition.

Table 4

Liquid cleaning composition E2 to E13 of the invention

Sodium hydroxide 2 2 2 2 2 2

1,2,3 benzotriazole 0.2 0.2 0.2 0.2 0.2 0.2

GLDA *3 10

NT A* 6 10

EDTA*7 10

HEDTA*8 10

DEG*9 10

EDG* 10 10

Sodium gluconate 20 20 20 20 20 20

Deionized Water Add. Add. Add. Add. Add. Add.

100 100 100 100 100 100

= Sodium salt of nitrilotriacetic acid (NTA)

= Sodium salt of ethylene diamine tetraacetic acid (EDTA)

*⁸ = Sodium salt of hydroxyethyl ethylene diamine triacetic acid (HEDTA)

*⁹ = Sodium salt of diethanolglycine sodium salt (DEG)

*¹⁰ = Sodium salt of ethanoldiglycine disodium salt (EDG)

Metal surfaces and/or plastic surfaces in need of cleaning are found in several locations. Exemplary locations include surgical instruments, medical instruments, and dental instruments, sinks, cookware, utensils, machine parts, vehicles, tanker trucks, vehicle wheels, work surfaces, tanks, immersion vessels, spray washers, and ultrasonic baths.

The cleaning compositions of the present invention can be used for removing residues including blood, greases, cutting fluids, drawing fluids, machine oils, antirust oils such as cosmoline, carbonaceous soils, sebaceous soils, particulate matter, waxes, paraffins, used motor oil, fuels, etc..

Metal surfaces that can be cleaned include iron-based metals such as iron, iron alloys, e. g. steel, tin, aluminum, copper, tungsten, titanium, molybdenum, etc., for example. The structure of the metal surface to be cleaned can vary widely. Thus, the metal surface can be as a metal part of complex configuration, sheeting, coils, rolls, bars, rods, plates, disks, etc.

More preferred is the use of the liquid alkaline cleaning solution of the invention, in particular the ready-to-use-solution to clean metal and/or plastic articles, especially metal instruments, plastic instruments, instruments with a plastic surface and/or instruments with a metal surface.

Most preferred is the use of the liquid alkaline cleaning solution of the invention, in particular the ready-to-use-solution, to clean in an automated instrument processing metal and/or plastic articles, especially metal instruments, plastic instruments, instruments with a plastic surface and/or instruments with a metal surface.

It should be noted that, as used in this specification and the appended claims, the singular forms "a", "an" and "the" include plural referents unless the content clearly dictates otherwise.

Thus, for example, reference to a composition containing "a compound" includes a mixture of two or more compounds. It should also be noted that the term "or" is generally employed in its sense including "and/or" unless the content clearly dictates otherwise. All publications and patent applications in this specification are indicative of the level of ordinary skill in the art to which this invention pertains. The invention has been described to various specific and preferred embodiments and techniques. However, it should be understood that many variations and modifications may be made while remaining within the spirit and scope of the invention.

Claims

What is claimed is:

1. A liquid alkaline composition for cleaning metal surfaces, comprising

at least one alkaline source,

at least one disilicate corrosion inhibitor,

at least a first sequestering agent, and

at least one solvent, wherein

2. The liquid alkaline composition according to claim 1, comprising

at least one alkaline source,

at least one disilicate corrosion inhibitor,

at least a first sequestering agent,

sodium gluconate as a second sequestering agent,

at least one water conditioner, and

at least one solvent, wherein

the weight ratio of the sodium gluconate to the water conditioner is in the range from 1 : 1 to 20 : 1, further preferred 5 : 1 to 15 : 1, also preferred 8 : 1 to 12 : 1.

3. The liquid alkaline composition according to claim 1 or 2, wherein the weight ratio of the disilicate to the sequestering agent is in the range from 0.20 : 1 to 0.8 : 1, preferably 0.25 : 1 to 0.75 : 1, further preferred 0.30 : 1 to 0.70 : 1, also preferred 0.35 : 1 to 0.65 : 1, more preferred 0.40 : 1 to 0.60 : 1, furthermore preferred 0.45 : 1 to 0.55 : 1, and most preferred 0.50 : 1 to 0.53 : 1 and/or the weight ratio of the alkaline source to the sequestering agent is in the range from 0.1 : 1 to 0.4 : 1, preferably 0.15 : 1 to 0.35 : 1, further preferred 0.20 : 1 to 0.30 : 1, and also preferred 0.23 : 1 to 0.26 : 1.

4. The liquid alkaline composition according to claims 1 to 3, comprising:

> 0.1 wt.-% to < 6 wt.-%, preferably > 0.5 wt.-% to < 5 wt.-%, further preferred > 1 w - % to < 4 wt.-%, also preferred > 1.5 wt.-% to < 3 wt.-%,and more preferred > 2 wt.-% to < 2.5 wt.-%, of at least one alkaline source; > 1 wt.-% to < 10 wt.-%, preferably > 1.5 wt.-% to < 8 wt.-%, further preferred > 2 wt.- % to < 6 wt.-%, also preferred > 3 wt.-% to < 4 wt.-%, and more preferred > 3.5 wt.-% to < 3.75 wt.-%, of at least one disilicate;

- > 5 wt.-% to < 10 wt.-%, preferably > 6 wt.-% to < 9 wt.-%, further preferred > 7 wt.-% to < 8 wt.-%, and more preferred > 7.4 wt.-% to < 7.6 wt.-%, of at least one first sequestering agent;

> 0 wt.-% to < 40 wt.-%, preferably > 5 wt.-% to < 35 wt.-%, further preferred > 10 wt.- % to < 30 wt.-%, also preferred > 15 wt.-% to < 27 wt.-%, and more preferred > 20 wt.-% to < 25 wt.-%, sodium gluconate as a second sequestering agent;

- > 0 wt.-% to < 1 wt.-%, preferably > 0.05 wt.-% to < 0.8 wt.-%, further preferred > 0.1 wt.-% to < 0.5 wt.-%, and more preferred > 0.2 wt.-% to < 0.3 wt.-%, of at least one corrosion inhibitor, preferably a heterocyclic compound, more preferred a triazole derivate; and

5. The liquid alkaline composition according to claims 1 to 4, wherein the composition comprises at least one alkaline source selected from the group of sodium hydroxide, sodium carbonate, potassium hydroxide, and lithium hydroxide.

6. The liquid alkaline composition according to claims 1 to 5, wherein the disilicate is an alkali disilicate, preferably a crystalline and/or amorphous alkali disilicates.

7. The liquid alkaline composition according to claims 1 to 5, wherein the first sequestering agent is selected from the group of pentasodium salt of diethylenetriamine pentaacetic acid, sodium glucoheptonate, salts of ethylene diamine tetraacetic acid, salts of hydroxyethyl ethylene diamine triacetic acid, salts of nitrilotriacetic acid,

diethanolglycine sodium salt, ethanoldiglycine disodium salt, salts of

hydro xymonocarboxylic acid compounds, salts of hydro xydicarboxylic acid compounds, salts of amine containing carboxylic acids, salts of N,N-bis(carboxylatomethyl)-L- glutamate and mixtures thereof, preferably the first sequestering agent is selected from the group of salts of N,N-bis(carboxylatomethyl)-L-glutamate (GLDA), salts of nitrilotriacetic acid (NT A), salts of ethylene diamine tetraacetic acid and mixtures thereof.

8. The liquid alkaline composition according to claims 1 to 5, wherein the water conditioner is selected from the group of salts of phosphonocarboxylic acids, phosphonates, salts of

1 -hydro xyethylidene -1,1,-diphosphonic acid (HEDP), salts of acid substituted polymers, salts of acid substituted polymers of monomers of acrylate, methacrylate, salts of polyitaconic acid, salts of polymaleic acid, and mixtures thereof , most preferred is 1- hydro xyethylidene -1,1,-diphosphonic acid (HEDP).

9. The liquid alkaline composition according to claims 1 to 8, wherein the corrosion

inhibitor is selected from the group comprising a heterocyclic compound, preferably a triazole derivate, more preferred a benzotriazole, 1,2,3-benzotriazole and mixtures thereof.

10. The liquid alkaline composition according to claims 1 to 9, wherein the solvent is

selected from the group comprising water, alcohols, glycols, glycol ethers, esters, preferably ethanol, propanol, propan-2-ol, 2-butoxy ethanol, 1-decanol, benzyl alcohol, glycerin, monoethanolamine and mixtures thereof, most preferred is water.

11. The solution of claims 1 to 10, wherein the solution is a concentrated solution or a ready- to-use solution.

12. The ready-to-use liquid alkaline composition according to claim 11, comprising:

> 0.003 wt.-% to < 0.03 wt.-%, preferably > 0.0045 wt.-% to < 0.024 wt.-%, further preferred > 0.006 wt.-% to < 0.018 wt.-%, also preferred > 0.009 wt.-% to < 0.012 wt.-%, and more preferred > 0.01 wt.-% to < 0.01 wt.-%, of at least one disilicate; > 0.015 wt.-% to < 0.03 wt.-%, preferably > 0.018 wt.-% to < 0.027 wt.-%, further preferred > 0.021 wt.-% to < 0.024 wt.-%, and more preferred > 0.022 wt.-% to < 0.023 wt.-%, of at least one first sequestering agent;

preferred > 0.0003 wt.-% to < 0.0015 wt.-%, and more preferred > 0.0006 wt.-% to < 0.001 wt.-%, of at least one corrosion inhibitor; and

13. Use of the solution of claims 1 to 13 to clean metal and/or plastic articles, preferably metal instruments, plastic instruments, instruments with a plastic surface and/or instruments with a metal surface.

14. Use of the solution of claim 13 to clean in an automated instrument processing metal and/or plastic articles, metal surfaces and/or plastic surfaces, preferably metal instruments, plastic instruments, instruments with a plastic surface and/or instruments with a metal surface.

15. A cleaning device comprising:

(a) at least a first container comprising an alkaline liquid alkaline composition according to claims 1 to 12 having a pH of > 11 to < 13, preferably a pH of > 11,5 to < 12,5 and more preferred a pH of 12;