EP3022280B1

EP3022280B1 - Mild alkaline solid instrument cleaner

Info

Publication number: EP3022280B1
Application number: EP13739990.3A
Authority: EP
Inventors: Carola Stingl; Beana HÜSKEN; Sebastian NIEBUR; Laurence Geret
Original assignee: Ecolab USA Inc
Current assignee: Ecolab USA Inc
Priority date: 2013-07-19
Filing date: 2013-07-19
Publication date: 2019-01-02
Anticipated expiration: 2033-07-19
Also published as: EP3022280A1; WO2015007347A1; PL3022280T3

Description

Field of the Invention

The invention relates to a mild alkaline solid cleaning composition, suitable for cleaning medical instruments, and methods for automated cleaning processing of surfaces with effective cleaning compositions. In particular, the invention relates to mild alkaline solid cleaning compositions useful in the cleaning of articles or surfaces, including plastic articles, plastic surfaces, metal articles, 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 and restaurants. 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.
WO 2012/045365 A1 refers to a solid of alkaline concentrated cleaning composition, a solution thereof and methods for automated cleaning processing of surfaces with effective cleaning compositions. The solid alkaline composition for cleaning metal surfaces, comprising at least one alkaline source, at least one polyethylene glycol and at least one corrosion inhibitor, wherein the ratio of alkaline source to polyethylene glycol is in the range from about 30 : 1 to about 2 : 1.
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.
One particular disadvantage of known commercial concentrated liquid products such as surface cleaners, detergent bleach, automatic instrument and cleaning formulations and the like comprising caustic alkali are hazardous, causes chemical "burns" if splashed onto the skin and causes corrosion of sensitive metal surfaces that come into contact with aqueous alkaline solutions. Further, the known commercial instrument processing liquid concentrated caustic alkali solutions have the disadvantage of transportation and storage because they are bulky. Although said commercial liquid products have an excellent disinfection effects the danger for humans and environment is still considerable, since the commercial products are liquid.
It is still a need in prior art to provide a mild alkaline solid cleaning composition for automated cleaning processing of hard and/or soft surfaces. In particular, it is a need to provide a mild alkaline solid cleaning composition for automated cleaning processing of metal surface layers to remove blood or other matter are allowed to dry, which is not bulky, avoids the disadvantages of transport and storage of liquids, provides a rapid dissolution in water, and develops after dissolution based on a low active concentration a good cleaning effect. Further, it shows no foam formation during the automated processing and prevents corrosion of metal surfaces that are exposed to aqueous alkaline solutions.

Summary of the Invention

The object of the present invention is to provide a mild alkaline solid cleaning composition, suitable for automated cleaning processing of hard and/or soft surfaces, such as metal and/or plastic surfaces in accordance with claim 1, comprising:

≥ 10 wt.% ≤ 35 wt.% of at least one alkaline source,
≥ 0.1 wt.% ≤ 1 wt.% of at least one polyethylene glycol, and
≥ 20 wt.% ≤ 40 wt.% of at least one corrosion inhibitor; wherein the weight-% ratio of the alkaline source to the polyethylene glycol is > 30 : 1; and wherein the weight-% of the components are based on the total weight of the mild alkaline solid cleaning composition.

The weight -% ratio of the alkaline source to the polyethylene glycol can be > 30 : 1 to > 3000 : 1, preferably > 31 : 1 to > 300 : 1, further preferred > 32 : 1 to > 100 : 1, and also preferred > 32.5 : 1 to > 35 : 1.
It has surprisingly found, that the mild alkaline solid cleaning composition of the invention, is suitable for automated cleaning processing of hard and/or soft surfaces, such as metal and/or plastic surfaces, in particular metal instruments. The mild alkaline solid cleaning composition comprises a very low content of polyethylene glycol and an increased amount of at least one corrosion inhibitor that makes it extremely sensitive to metal articles, metal surfaces, plastic articles and/or plastic surfaces. For example, the mild alkaline solid cleaning composition according to the invention may provide good cleaning performances even though the weight-% ratio of alkaline source to polyethylene glycol can be for example in the range from > 30 : 1 to ≤ 3000 : 1, based on the total weight of the mild alkaline solid cleaning composition.
The weight-% ratio of alkaline source to polyethylene glycol can be in the range from > 30 : 1 to ≤ 3000 : 1, preferably ≥ 31 : 1 to ≤ 300 : 1, further preferred ≥ 32 : 1 to ≤ 150 : 1, ≥ 32 : 1 to ≤ 100 : 1, ≥ 32 : 1 to ≤ 50 : 1, and also preferred ≥ 32.5 : 1 to ≤ 35 : 1, wherein the weight-% of the components are based on the total weight of the mild alkaline solid cleaning composition.
The term "alkaline sensitive metal" identifies those metals that exhibit corrosion and/or discoloration when exposed to an aqueous alkaline solution.
An aqueous alkaline solution is an aqueous solution having a pH that is greater than 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 mild alkaline solid cleaning compositions.
References herein to a "solid" composition are to those, which are solid at 15° C and up to 60° C. Preferably, the mild alkaline solid cleaning composition of the present invention may be at 15° C and up to 60° C form stable and/or rigid.
A solvent, preferably water, can be added add. 100 wt.-% to the mild alkaline solid cleaning composition of the invention. The solvent content, such as the water content, of the mild alkaline solid cleaning composition according to the invention is simply determined by subtracting the amounts of all the usual components from 100 wt. %.
The weight-% (wt.-%) of the components are calculated based on the total weight amount of the mild alkaline solid cleaning composition, if not otherwise stated.
The ratio of components of the mild alkaline solid cleaning composition is parts by weight, if not otherwise stated.
The total amount of all components of the mild alkaline solid cleaning composition does not exceed 100 wt.-%.
It should be understood that the addition of other surfactants to the solid as well as to a liquid mild alkaline cleaning composition, obtained by solving the mild alkaline solid cleaning composition, for automated cleaning processing of hard and/or soft surfaces is optional and can be omitted.
Preferably, the mild alkaline solid cleaning compositions are free of other surfactants, except polyethylene glycol.
It should be understood that the mild alkaline solid cleaning compositions can be free of a hydrotrope component.
It should be understood that the mild alkaline solid cleaning compositions can be free of a zeolite, except sodium disilicate.
It should be understood that the mild alkaline solid cleaning compositions 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 polyethylene glycol leads to an increased foam formation, thus not suitable for use in an automated cleaning processing. However, it has been surprisingly found, that at a specific ratio of the alkaline source to the polyethylene glycol provides a low foaming composition suitable for automated cleaning processing of hard and/or soft surfaces, such as metal articles, metal surfaces, plastic articles and/or plastic surfaces.
At the time of dissolution with the solvent, such as water, a spontaneous and intensive foam formation in the dispensing draw of an apparatus for cleaning processing as well as in the cleaning chamber is observed, if the ratio or concentration of polyethylene glycol in the mild alkaline solid cleaning composition of the present invention is selected to high. However, reducing the amount of polyethylene glycol to a very low content leads to an improper cleaning result. It has been surprisingly found that the insufficient cleaning characteristics due to the very low content of polyethylene glycol can be compensated and improved by increasing the amount of corrosion inhibitor.
Whiteout being bonded to a specific theory, it is assumed by the inventor that the increased amount of corrosion inhibitor has a synergetic cleaning effect that allows to reduce the polyethylene glycol content. The decrease content of polyethylene glycol reduces unwanted foam generation including the formation of micro bubbles to an absolute minimum, which improves disinfection of the surfaces to be cleaned.
The specific ratio of the at least one corrosion inhibitor to polyethylene glycol according to the present invention provides a good cleaning effect in combination with no visible foaming as required for an automated processing of metal articles, metal surfaces, plastic articles and/or plastic surfaces.
No foam formation is observed for the compositions according to the present invention, especially 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 a mild alkaline solid cleaning composition of the present invention used in an automated washing process is surprisingly good, although the concentration of the polyethylene glycol in the mild alkaline solid cleaning composition of the present invention is extremely low due to the addition of an increased amount of at least one corrosion inhibitor.
An aqueous alkaline composition having a high pH are often more corrosive than an aqueous composition having a light acidic pH. The concentrated liquid composition of the invention can have a pH in the range of ≥ 12.5 pH to ≤ 13.5 pH.
In order to minimize the potential to corrode and/or discolor the metal surface, the pH of the ready-to-use aqueous alkaline solutions, that is used for soil removal or cleaning action in direct contact with the surface of the article to be cleaned, can be adjusted to a lower pH in the range of ≥ 9.5 pH to ≤ 11 pH.
The soil removal or cleaning action of an aqueous solution of the mild alkaline solid cleaning composition according to the present invention can be improved by adding at least one sequestering agent to the mild alkaline solid cleaning composition, preferably at least one sequestering agent that exhibits soil removal properties.

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. concentrated liquid composition as well as the ready-to-use liquid mild alkaline cleaning 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, including for example in the form of solid beads, 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 45 wt. %, 50 wt. % and 73 wt. % solution.
According to the invention, the mild alkaline solid cleaning composition comprises ≥ 10 wt.-% to ≤ 35 wt.-%, preferably ≥ 13 wt.-% to ≤ 24 wt.-%, and more preferred ≥ 15 wt.-% to ≤ 20 wt.-%, of at least one alkaline source, preferably sodium hydroxide; wherein the weight-% of the components are based on the total weight of the mild alkaline solid cleaning composition.

Polyethylene Glycol

A suitable polyethylene glycol for use in the present invention can have an average mol weight (MW) in the range of ≥ 4000 to ≤ 12000, preferably ≥ 6000 to ≤ 10000 and more preferred of ≥ 7000 to ≤ 8000. Polyethylene glycol that can be used are marketed for example by BASF under the tradename PLURIOL®.
According to the invention, the mild alkaline solid cleaning composition comprises ≥ 0.1 wt.-% to ≤ 1 wt.-%, preferably ≥ 0.2 wt.-% to ≤ 0.8 wt.-%, further preferred ≥ 0.3 wt.-% to ≤ 0.7 wt.-%, and more preferred ≥ 0.4 wt.-% to ≤ 0.6 wt.-%, and most preferred 0.5 wt.-%, of at least one polyethylene glycol, preferably a polyethylene glycol with an average mol weight in the range of 4.000 to 12.000, and more preferred a polyethylene glycol having an average mol weight of 8,000; wherein the weight-% of the components are based on the total weight of the mild alkaline solid cleaning composition.

Corrosion Inhibitor

According to the present invention, at least one corrosion inhibitor, preferably at least two corrosion inhibitors, in large amounts, are used to compensate the extreme low polyethylene glycol content of the composition in order to reach an excellent cleaning performance as well as to prevent the corrosion of an article to be cleaned.
Preferably a silicate(s) corrosion inhibitor and more preferred a disilicate corrosion inhibitor can be used in the solid composition according to the present invention. The silicate(s) and/or disilicate corrosion inhibitor can be an alkali silicate and/or alkali disilicate.
Other inhibitors that can be used can be selected from the group comprising calcium acetate, calcium chloride, calcium gluconate, calcium phosphate, calcium borate, calcium carbonate, calcium citrate, calcium lactate, calcium sulfate, calcium tartrate, benzotriazole, 1,2,3-benzotriazole and mixtures thereof.
More preferred, the corrosion inhibitor is a heterocyclic compound, a triazole derivate, such as a benzotriazole or 1,2,3-benzotriazole and mixtures thereof.
Exemplary silicates include sodium metasilicates, sesquisilicates, orthosilicates, potassium silicates, and mixtures thereof. However, most preferred can be sodium silicate.
The silicates may comprise at least one crystalline layer-forming silicate of the general formula NaMSixO2x+1.yH2O, wherein M represents sodium or hydrogen, x is a number from 1.9 to 22, preferably 1.9 to 4 and y stands for a number from 0 to 33.
The crystalline layer-forming silicates of the formula NaMSixO22x+1.yH2O are marketed for example by Clariant GmbH (Germany) under the trade names Na-SKS, eg. Na-SKS-1 (Na2Si22O45.xH2O, Kenyait), Na-SKS-2 (Na2Si14O29.xH2O, Magadiit), Na-SKS-3 (Na2Si8O17.xH2O) or Na-SKS-4 (Na2Si4O9.xH2O, Makatit).
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 -Na2Si2O5), Na-SKS-7 (beta -Na2Si2O5, Natrosilit), Na-SKS-9 (NaHSi2O5.H2O), Na-SKS-10 (NaHSi2O5.3H2O, Kanemit), Na-SKS-11 (t-Na2Si2O5) and Na-SKS-13 (NaHSi2O5) are most notably suitable, particularly Na-SKS-6 (delta -Na2Si2O5).
In the context of the present application, silicates can comprise a content by weight of crystalline layered silicates of formula NaMSixO2x+1.yH2O 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 have a total silicate content > 0 and below 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 NaMSixO2x+1.yH2O.
However, other corrosion inhibitors can be suitable added to the mild alkaline solid cleaning composition of this invention include magnesium and/or zinc ions and Ca(NO₂)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, 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 hydrolytic 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.
According to the invention, the mild alkaline solid cleaning composition comprises ≥ 15 wt.-% to ≤ 40 wt.-%, preferably ≥ 18 wt.-% to ≤ 35 wt.-%, further preferred ≥ 20 wt.-% to ≤ 28 wt.-%, and more preferred ≥ 23 wt.-% to ≤ 25 wt.-%, of at least one corrosion inhibitor, preferably sodium disilicate, and more preferred at least two corrosion inhibitors, preferably a benzotriazol and sodium disilicate and most preferred 1,2,3-benzotriazole and sodium disilicate; wherein the weight-% of the components are based on the total weight of the mild alkaline solid cleaning composition.

Threshold Inhibitor/Crystal Modifier

The mild alkaline solid cleaning composition according to the present invention can comprise at least one threshold inhibitor/crystal modifier.
The threshold inhibitor/crystal modifier can be selected from the group comprising salts of phosphonocarboxylic acids, phosphonates, salts of 1-hydroxyethylidene -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.
The amount of threshold inhibitor/crystal modifier can be ≥ 0.5 wt.-% to ≤ 15 wt.-%, preferably ≥ 1 wt.-% to ≤ 10 wt.-%, and more preferred ≥ 3 wt.-% to ≤ 5 wt.-% of at least one threshold inhibitor/crystal modifier, preferably the threshold inhibitor/crystal modifier is a salt of a polyacrylic acid; wherein the weight-% of the components are based on the total weight of the mild alkaline solid cleaning composition.

Sequestering Agent

The mild alkaline solid cleaning composition according to the present invention can comprise at least one sequestering agent.
The sequestering agent can be selected from the group of sodium gluconate, pentasodium salt of diethylenetriamine pentaacetic acid, sodium glucoheptonate, salts of ethylene diamine tetraacetic acid, salts of ethylene diamine tetraacetic acid, salts of hydroxyethyl ethylene diamine triacetic acid, salts of hydroxyethyl ethylene diamine triacetic acid, salts of nitrilotriacetic acid, salts of nitrilotriacetic acid, diethanolglycine sodium salt, ethanoldiglycine disodium salt, salts of hydroxymonocarboxylic acid compounds, salts of hydroxydicarboxylic acid compounds, salts of amine containing carboxylic acids, tetrasodium N,N-bis(carboxylatomethyl)-L-glutamate (GDLA) and mixtures thereof.
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 mild alkaline solid cleaning 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 (NTA), salts of nitrilotriacetic acid, diethanolglycine sodium salt (DEG), ethanoldiglycine disodium salt (EDG), tetrasodium N,N-bis(carboxylatomethyl)-L-glutamate (GLDA), methyl glycine diacetic acid (MGDA)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.
The amount of sequestering agent can be ≥ 5 wt.-% to ≤ 40 wt.-%, preferably ≥ 15 wt.-% to ≤ 30 wt.-%, and more preferred ≥ 20 wt.-% to ≤ 25 wt.-% of at least one sequestering agent, preferably the sequestering agent is a salt of an amine containing carboxylic acid, and more preferred terasodium N,N-bis(carboxylatomethyl)-L-glutamate (GLDA); wherein the weight-% of the components are based on the total weight of the mild alkaline solid cleaning composition.

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, isopropanol (propan-2-ol), 2-butoxy ethanol (butyl glycol), 1-decanol, benzyl alcohol, glycerin, monoethanolamine (MEA), and the like, or combinations 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. Preferably the composition comprises at least two solvents and more preferred the composition comprises water and hexylene glycol.
The amount of an additional solvent that is not water, preferably hexylene glycol, can be ≥ 0.1 wt.-% to ≤ 5 wt.-%, preferably ≥ 0.4 wt.-% to ≤ 1 wt.-%, and more preferred ≥ 0.6 wt.-% to ≤ 0.8 wt.-%; wherein the weight-% of the components are based on the total weight of the mild alkaline solid cleaning composition.
Water can be added add 100 wt.-%; wherein the weight-% of the components are based on the total weight of the mild alkaline solid cleaning composition.

Mild alkaline solid cleaning composition

According to one embodiment of the invention, the mild alkaline solid cleaning composition may comprise:

≥ 10 wt.-% to ≤ 35 wt.-%, preferably ≥ 13 wt.-% to ≤ 24 wt.-%, and more preferred ≥ 15 wt.-% to ≤ 20 wt.-%, of at least one alkaline source, preferably sodium hydroxide;
≥ 0.1 wt.-% to ≤ 1 wt.-%, preferably ≥ 0.2 wt.-% to ≤ 0.8 wt.-%, further preferred ≥ 0.3 wt.-% to ≤ 0.7 wt.-%, and more preferred ≥ 0.4 wt.-% to ≤ 0.6 wt.-%, and most preferred 0.5 wt.-%, of at least one polyethylene glycol, preferably a polyethylene glycol with an average mol weight in the range of 4.000 to 12.000, and more preferred a polyethylene glycol having an average mol weight of 8,000; and
≥ 15 wt.-% to ≤ 40 wt.-%, preferably ≥ 18 wt.-% to ≤ 35 wt.-%, further preferred ≥ 20 wt.-% to ≤ 28 wt.-%, and more preferred ≥ 23 wt.-% to ≤ 25 wt.-%, of at least one corrosion inhibitor, preferably sodium disilicate, and more preferred at least two corrosion inhibitors, preferably a benzotriazol and sodium disilicate;
a solvent, preferably water, is added add. 100 wt.-%; wherein

According to another embodiment of the invention, the mild alkaline solid cleaning composition may comprise:

≥ 10 wt.-% to ≤ 35 wt.-%, preferably ≥ 13 wt.-% to ≤ 24 wt.-%, and more preferred ≥ 15 wt.-% to ≤ 20 wt.-%, of at least one alkaline source, preferably sodium hydroxide;
≥ 0.1 wt.-% to ≤ 1 wt.-%, preferably ≥ 0.2 wt.-% to ≤ 0.8 wt.-%, further preferred ≥ 0.3 wt.-% to ≤ 0.7 wt.-%, and more preferred ≥ 0.4 wt.-% to ≤ 0.6 wt.-%, and most preferred 0.5 wt.-%, of at least one polyethylene glycol, preferably a polyethylene glycol with an average mol weight in the range of 4.000 to 12.000, and more preferred a polyethylene glycol having an average mol weight of 8,000 ; and
≥ 15 wt.-% to ≤ 40 wt.-%, preferably ≥ 18 wt.-% to ≤ 35 wt.-%, further preferred ≥ 20 wt.-% to ≤ 28 wt.-%, and more preferred ≥ 23 wt.-% to ≤ 25 wt.-%, of at least one corrosion inhibitor, preferably sodium disilicate, and more preferred at least two corrosion inhibitors, preferably a benzotriazol and sodium disilicate;
≥ 0.5 wt.-% to ≤ 15 wt.-%, preferably ≥ 1 wt.-% to ≤ 10 wt.-%, and more preferred ≥ 3 wt.-% to ≤ 5 wt.-% of at least one threshold inhibitor/crystal modifier, preferably the threshold inhibitor/crystal modifier is a salt of a polyacrylic acid;
≥ 5 wt.-% to ≤ 40 wt.-%, preferably ≥ 15 wt.-% to ≤ 30 wt.-%, and more preferred ≥ 20 wt.-% to ≤ 25 wt.-% of at least one sequestering agent, preferably the sequestering agent is a salt of an amine containing carboxylic acid, and more preferred terasodium N,N-bis(carboxylatomethyl)-L-glutamate (GLDA);
a solvent, preferably water, is added add. 100 wt.-%; wherein

Liquid mild alkaline cleaning composition

Another object of the present invention is directed to a liquid mild alkaline cleaning composition obtained from the mild alkaline solid cleaning composition of the invention. 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 liquid mild alkaline cleaning solution. The ready-to-use liquid mild alkaline cleaning solution can be directly used to clean articles and need not to be diluted.
The ready-to-use liquid composition according to the invention may be used to clean articles having a metal surface, such as surgical, medical, and dental instruments, including endoscopes.
The solution can be in the form of a concentrate that can be diluted with a solvent, such as water, to provide a ready-to-use liquid mild alkaline cleaning solution that can be used for cleaning applied to articles having a metal surface, such as surgical, medical, and dental instruments.
In addition, the solutions 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.
It is advantageous to provide the solution 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 concentrate liquid composition and/or the ready-to-use liquid mild alkaline cleaning solution can be used in an automated washing process for cleaning and disinfection metal and plastic 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.

Concentrated mild alkaline liquid composition

The source of alkalinity and addition of the solvent, preferably water, are provided so that the concentrated, preferably aqueous, liquid composition of the mild alkaline solid cleaning composition according to the present invention may have a pH in the range of 12 pH to 14 pH, preferably a pH in the range of 12.5 pH to 13.5 pH and more preferred a pH of 13 pH.
The ratio of the solvent, preferably water, to solid, to provide a concentrated liquid composition, preferably an aqueous solution, of the mild alkaline solid cleaning composition can be in the range of from 200 : 1 to 10 : 1, preferably 100 : 1 to 12 : 1, further preferred 50 : 1 to 15 : 1, also preferred 40 : 1 to 17 : 1 and in particular preferred 30 : 1 to 20 : 1.
According to one embodiment of the invention, the alkaline concentrated liquid composition can comprise:

≥ 0.07 wt.-% to ≤ 3.5 wt.-%, preferably ≥ 0.3 wt.-% to ≤ 1.6 wt.-%, and more preferred ≥ 0.5 wt.-% to ≤ 1 wt.-%, of at least one alkaline source, preferably sodium hydroxide;
≥ 0.0005 wt.-% to ≤ 0.1 wt.-%, preferably ≥ 0.002 wt.-% to ≤ 0.07 wt.-%, further preferred ≥ 0.006 wt.-% to ≤ 0.05 wt.-%, and more preferred ≥ 0.01 wt.-% to ≤ 0.35 wt.-%, and most preferred 0.02 wt.-%, of at least one polyethylene glycol, preferably a polyethylene glycol with an average mol weight in the range of 4.000 to 12.000, and more preferred a polyethylene glycol having an average mol weight of 8,000; and
≥ 0.075 wt.-% to ≤ 4 wt.-%, preferably ≥ 0.36 wt.-% to ≤ 2.5 wt.-%, further preferred ≥ 0.5 wt.-% to ≤ 1.5 wt.-%, and more preferred ≥ 0.7 wt.-% to ≤ 1.25 wt.-%, of at least one corrosion inhibitor, preferably sodium disilicate, and more preferred at least two corrosion inhibitors, preferably a benzotriazol and sodium disilicate;
a solvent, preferably water, is added add. 100 wt.-%;

According to another embodiment of the invention, the mild alkaline solid cleaning composition can comprise:

≥ 0.07 wt.-% to ≤ 3.5 wt.-%, preferably ≥ 0.3 wt.-% to ≤ 1.6 wt.-%, and more preferred ≥ 0.5 wt.-% to ≤ 1 wt.-%, of at least one alkaline source, preferably sodium hydroxide;
≥ 0.0005 wt.-% to ≤ 0.1 wt.-%, preferably ≥ 0.002 wt.-% to ≤ 0.07 wt.-%, further preferred ≥ 0.006 wt.-% to ≤ 0.05 wt.-%, and more preferred ≥ 0.01 wt.-% to ≤ 0.35 wt.-%, and most preferred 0.02 wt.-%, of at least one polyethylene glycol, preferably a polyethylene glycol with an average mol weight in the range of 4.000 to 12.000, and more preferred a polyethylene glycol having an average mol weight of 8,000; and
≥ 0.075 wt.-% to ≤ 4 wt.-%, preferably ≥ 0.36 wt.-% to ≤ 2.5 wt.-%, further preferred ≥ 0.5 wt.-% to ≤ 1.5 wt.-%, and more preferred ≥ 0.7 wt.-% to ≤ 1.25 wt.-%, of at least one corrosion inhibitor, preferably sodium disilicate, and more preferred at least two corrosion inhibitors, preferably a benzotriazol and sodium disilicate;
≥ 0.0025 wt.-% to ≤ 1.5 wt.-%, preferably ≥ 0.02 wt.-% to ≤ 0.7 wt.-%, and more preferred ≥ 0.1 wt.-% to ≤ 0.25 wt.-% of at least one threshold inhibitor/crystal modifier, preferably the threshold inhibitor/crystal modifier is a salt of a polyacrylic acid;
≥ 0.025 wt.-% to ≤ 4 wt.-%, preferably ≥ 0.3 wt.-% to ≤ 2 wt.-%, and more preferred ≥ 0.6 wt.-% to ≤ 1.25 wt.-% of at least one sequestering agent, preferably the sequestering agent is a salt of an amine containing carboxylic acid, and more preferred terasodium N,N-bis(carboxylatomethyl)-L-glutamate (GLDA);
a solvent, preferably water, is added add. 100 wt.-%; wherein

Readv-to-use liquid mild alkaline cleaning solution

The source of alkalinity and addition of solvent, preferably water, are provided so that the aqueous ready-to-use liquid mild alkaline cleaning solution according to the present invention may have a pH in the range of ≥ 9.5 pH to ≤ 11.5 pH and preferably a pH in the range of ≥ 10.0 pH to ≤ 11 pH.
The ratio of the solvent, preferably water, to solid, to provide a ready-to-use liquid mild alkaline cleaning solution, preferably an aqueous solution, of the mild alkaline solid cleaning composition can be in the range of from 60,000 : 1 to 100 : 1, preferably 30,000 : 1 to 300 : 1, further preferred 10,000 : 1 to 500 : 1, also preferred 5,000 : 1 to 750 : 1 and in particular preferred 2,500 : 1 to 1,000 : 1.
According to one embodiment of the invention, the ready-to-use liquid mild alkaline cleaning solution can comprise:

≥ 0.0002 wt.-% to ≤ 0.035 wt.-%, preferably ≥ 0.0009 wt.-% to ≤ 0.016 wt.-%, and more preferred ≥ 0.0015 wt.-% to ≤ 0.01 wt.-%, of at least one alkaline source, preferably sodium hydroxide;
≥ 0.0000015 wt.-% to ≤ 0.001 wt.-%, preferably ≥ 0.000006 wt.-% to ≤ 0.0007 wt.-%, further preferred ≥ 0.00002 wt.-% to ≤ 0.0005 wt.-%, and more preferred ≥ 0.00003 wt.-% to ≤ 0.0035 wt.-%, and most preferred 0.0002 wt.-%, of at least one polyethylene glycol, preferably a polyethylene glycol with an average mol weight in the range of 4.000 to 12.000, and more preferred a polyethylene glycol having an average mol weight of 8,000; and
≥ 0.0002 wt.-% to ≤ 0.04 wt.-%, preferably ≥ 0.001 wt.-% to ≤ 0.025 wt.-%, further preferred ≥ 0.0015 wt.-% to ≤ 0.015 wt.-%, and more preferred ≥ 0.002 wt.-% to ≤ 0.01 wt.-%, of at least one corrosion inhibitor, preferably sodium disilicate, and more preferred at least two corrosion inhibitors, preferably a benzotriazol and sodium disilicate;
a solvent, preferably water, is added add. 100 wt.-%; wherein

According to another embodiment of the invention, the ready-to-use liquid mild alkaline cleaning solution can comprise:

≥ 0.0002 wt.-% to ≤ 0.035 wt.-%, preferably ≥ 0.0009 wt.-% to ≤ 0.016 wt.-%, and more preferred ≥ 0.0015 wt.-% to ≤ 0.01 wt.-%, of at least one alkaline source, preferably sodium hydroxide;
≥ 0.000001 wt.-% to ≤ 0.001 wt.-%, preferably ≥ 0.000006 wt.-% to ≤ 0.0007 wt.-%, further preferred ≥ 0.00002 wt.-% to ≤ 0.0005 wt.-%, and more preferred ≥ 0.00003 wt.-% to ≤ 0.0035 wt.-%, and most preferred 0.0002 wt.-%, of at least one polyethylene glycol, preferably a polyethylene glycol with an average mol weight in the range of 4.000 to 12.000, and more preferred a polyethylene glycol having an average mol weight of 8,000; and
≥ 0.0002 wt.-% to ≤ 0.04 wt.-%, preferably ≥ 0.001 wt.-% to ≤ 0.025 wt.-%, further preferred ≥ 0.0015 wt.-% to ≤ 0.015 wt.-%, and more preferred ≥ 0.002 wt.-% to ≤ 0.01 wt.-%, of at least one corrosion inhibitor, preferably sodium disilicate, and more preferred at least two corrosion inhibitors, preferably a benzotriazol and sodium disilicate;
≥ 0.000007 wt.-% to ≤ 0.015 wt.-%, preferably ≥ 0.00006 wt.-% to ≤ 0.007 wt.-%, and more preferred ≥ 0.0003 wt.-% to ≤ 0.0025 wt.-% of at least one threshold inhibitor/crystal modifier, preferably the threshold inhibitor/crystal modifier is a salt of a polyacrylic acid;
≥ 0.0007 wt.-% to ≤ 0.04 wt.-%, preferably ≥ 0.001 wt.-% to ≤ 0.02 wt.-%, and more preferred ≥ 0.002 wt.-% to ≤ 0.01 wt.-% of at least one sequestering agent, preferably the sequestering agent is a salt of an amine containing carboxylic acid, and more preferred terasodium N,N-bis(carboxylatomethyl)-L-glutamate (GLDA);
a solvent, preferably water, is added add. 100 wt.-%; wherein

Manufacture of the mild alkaline solid cleaning composition

There are a number of processes known in prior art to provide a solidified product. For example, all components of the mild alkaline solid cleaning composition can be mixed together or added portionwise or one after the other. A cast process then solidifies the heated slurry, e.g. the solidification can erupt after cooling down a NaOH melt by crystallization.

Cleaning Apparatus

A cleaning apparatus is used to clean and to disinfect articles having a metal surface, such as surgical, medical, and dental instruments.
The cleaning apparatus includes at least a first tank to receive the mild alkaline solid cleaning composition of the invention; at least a second component tank to receive water diluted concentrated composition or a ready-to-use liquid mild alkaline cleaning solution of said mild alkaline solid cleaning composition of the invention, a water feed, and a use solution line; and optional a third component tank to receive a day portion of the concentrated composition or a ready-to-use liquid mild alkaline cleaning solution of the invention.
The first component tank is provided for containing the mild alkaline solid cleaning composition of the invention. The first component tank can be provided for mixing water to the mild alkaline solid cleaning composition to provide a concentrated liquid composition. The mild alkaline solid cleaning composition can be mixed with water in a circulation method to obtain a defined alkaline aqueous concentrated liquid composition.
The second component tank is provided for receiving the aqueous concentrated liquid composition or for mixing water to the alkaline aqueous concentrated liquid composition to provide a ready-to-use liquid mild alkaline cleaning solution.
The optional third component tank is provided for receiving a day portion of the aqueous concentrated liquid composition or for mixing water to the alkaline aqueous concentrated liquid composition to provide a day portion of a ready-to-use liquid mild alkaline cleaning solution.
The water feed is provided for conveying water to the first tank, second tank (makeup tank) and/or third tank (day tank) for dissolving the mild alkaline solid cleaning composition (first tank) and/or for providing an aqueous concentrated alkaline liquid composition or a ready-to-use liquid mild alkaline cleaning solution (second tank) and/or for providing an aqueous ready-to-use liquid mild alkaline cleaning solution (third tank). It can be preferred that the aqueous concentrated alkaline liquid composition is transferred to the day tank, by the time the defined concentration, pH, volume and/or temperature is reached.
However, the makeup tank (second tank) and more preferred the third tank (day tank) can be used to receive and stock the alkaline aqueous concentrated liquid composition or the ready-to-use liquid mild alkaline cleaning solution. Most preferred is to provide the ready-to-use liquid mild alkaline cleaning solution at the place of use, for example in an applicator, by adding sufficient water. The aqueous concentrated alkaline liquid composition can be conveyed from the second tank or a day tank (optional third tank) to a dispenser and the dispenser sprays out the ready-to-use liquid mild alkaline cleaning solution at the place of operation in a defined concentration.
The solution line is provided for conveying solution from the second container to a use solution applicator.
In more detail, the mild alkaline solid cleaning composition of the invention can be used in combination with a healthcare solid dispenser. This dispenser sprays out the mild alkaline solid cleaning composition of the invention having the form of a capsule in a circulation method to a defined concentration. This alkaline aqueous concentrated liquid composition is collected in a makeup tank and transferred to a day tank as soon as the concentration and referring conductivity has reached the defined level. From there the pumps of the washer disinfectors dose the cleaning alkaline aqueous concentrated liquid composition in the cleaning cycle of the reprocessing step. The solid can be diluted to a 5% alkaline aqueous concentrated liquid composition in the dispenser.
The ready-to-use liquid mild alkaline cleaning solution or the concentrated liquid composition can be in any form including liquid, gel, paste and slurry.
The cleaning solutions, i.e. ready-to-use liquid mild alkaline cleaning solution and/or the concentrated liquid composition, 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 liquid mild alkaline cleaning solution and/or the concentrated aqueous alkaline liquid composition, may be used at any temperature, including an elevated temperature of from 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 or plastic surface.
The contact time of the aqueous cleaning solution in an automated process, i.e. ready-to-use liquid mild alkaline cleaning solution and/or the concentrated liquid composition, 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 cleaning apparatus may comprise:

(a) a first container comprising an alkaline solid composition according to claims 1 to 10;
(b) a second container comprising a concentrated liquid composition of the solid composition according to claim 12 or 14 having a pH of ≥ 12.5 to ≤ 13.5, preferably a pH of 13;
(c) optional a third container comprising a day solution of the concentrated liquid composition or a ready to use solution having a pH of ≥ 9.5 to ≤ 11.0;
(c) a water feed for conveying water to the first container for forming said solution from water;
(d) a solution line for conveying solution from the first container to the second container;
(e) optional a third container that is connected with the second container with a solution line for conveying solution from the second container to the third container; and
(f) a use solution line for conveying the use solution from the second container and/or third container to a use solution applicator and/or to the place of use.

The following examples are presented to help illustrate the invention and should not be construed as limiting the invention.
When processing solids in the cast process there are different ways to ensure a solidification of the product. The solidification can erupt after cooling down a NaOH melt by crystallization, e.g. with silicates and polyethylene glycol. Foaming of this formula was observed to an extent that was not acceptable in the field of automated reprocessing. If the cleaner generates too much foam in the washer, the cleaning efficiency goes down due to lack of mechanical agitation in the washer.
It was observed that polyethylene glycol in combination with NaOH and heat lead to a high foaming composition. The formation of foam lowers in particular the cleaning properties, due to the loss of mechanical agitation. Further, pumping of foam dramatically reduces 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. Cleaning efficacy tests have shown that that the results without polyethylene glycol in the formula were not as good as with polyethylene glycol in the formula.
To achieve a good level of cleaning efficacy it was successfully tried to add a small amount of polyethylene glycol to the NAOH based formulation. With this addition of a minor amount of polyethylene glycol (PEG) the composition of the invention has a surprising cleaning efficacy due to none foam formation, if mixed with water, as sump solution or in the dispensing drawer.
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.
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 and/or plastic surface can be as a metal and/or plastic part of complex configuration, sheeting, coils, rolls, bars, rods, plates, disks.
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.

Example

The following examples were carried out to illustrate the reduced foam formation of the cleaning compositions according to the invention.

The following alkaline concentrates were provided in a solid form:
All components of table 1 and 2 are mixed together. Then the slurry is mixed and heated to temperature of 80° C for 30 minutes. Thereafter, the mixed slurry is casted and allows cooling to room temperature, whereby a casted alkaline solid is formed.

Table 1

Solid alkaline concentrate of the invention
Components	E1	E2	E3	E4	E5	E6	E7
	Wt.-%	Wt.-%	wt.-%	wt.-%	wt.-%	wt.-%	wt.-%
Polyethylene glycol (PEG 8000)	0.1	0.2	0.4	0.5	0.6	0.7	0.8
Hexylene glycol	---	---	---	0.6	0.6	0.6	0.6
Polyacrylic acid	---	---	2	3	3.5	---	---
NaOH	15	20	15	16	18	20	20
1,2,3-Benzotriazole	---	---	4	5.5	6	6.5	---
Disilicate	40	35	30	25	24	23	20
N,N-bis(carboxylatomethyl)-L-glutamate (GLDA)	---	---	15	20	25	25	20
Water	Add. 100	Add. 100	Add. 100	Add. 100	Add. 100	Add. 100	Add. 100

Examples E5 to E7 are outside of the claimed scope.

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

An aqueous ready-to-use liquid mild alkaline cleaning solution is formed, wherein 1.0 g of examples E1 to E7 are dissolved in 100 ml of deionized water each.
100 ml of said aqueous ready-to-use liquid mild alkaline cleaning solution of examples E1 to E7 are added to a graduated 250 ml long-necked glass cylinder.
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. This test was carried out at a temperature of the cleaning solution at ambient temperature, 20° C and 55° C. The foam height are given in ml.
The table 2 shows the result of the foam formation caused by the aqueous ready-to-use liquid mild alkaline cleaning solution of examples E1 to E7 obtained by the foam formation test. Table 2

Foam Formation Test-Results

Exampels ml

E1 0

E2 0

E3 0

E4 0

E5 0

E6 0

E7 0

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 E1 to E7 and comparative compositions V1 to V14 were diluted with deionized water to a 0.8 wt.-% ready-to-use liquid mild alkaline cleaning solution. The weights of 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 liquid mild alkaline cleaning solution E1 to E7 and V1 to V14 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 tests were run for each experiment and the average weight loss was determined. The average weight loss for each aluminum test plates after treatment with said ready-to-use liquid mild alkaline cleaning solution obtained from E1 to E7 were ≤ 0.30 wt.-% and for V1 to V14 ≥ 1 wt.-%.

Table 3

Comparative composition V1 to V14
Components	V1	V2	V3	V4	V5	V6	V7
	Wt.-%	wt.-%	wt.-%	wt.-%	wt.-%	wt.-%	wt.-%
Polyethylene glycol (PEG 8000)	2	3	5	6	9	10	12
Hexylene glycol	---	---	---	0.6	0.6	0.6	0.6
Polyacrylic acid	6	6	5	5	5	5	4
NaOH	37	35	33	30	28	25	25
1,2,3-Benzotriazole	6	5	4				7
Disilicate				4	5	3
N,N-bis(carboxylatomethyl)-L-glutamate (GLDA)					25	22	22
Water	Add. 100	Add. 100	Add. 100	Add. 100	Add. 100	Add. 100	Add. 100
Components	V8	V9	V10	V11	V12	V13	V14
	Wt.-%	Wt.-%	Wt.-%	Wt.-%	Wt.-%	Wt.-%	Wt.-%
Polyethylene glycol (PEG 4000)	2	4	6	---	---	---	---
Polyethylene glycol (PEG 10000)	---	---	---	2	6	8	10
Hexylene glycol					0.6	0.5	0.4
Polyacrylic acid	6	6	5	6	5	5	5
NaOH	37	33	30	28	26	26	25
1,2,3-Benzotriazole	6	6	5
Disilcate				6	5	4	4
N,Nbis(carboxylatomethyl)-L-glutamate (GLDA)	28					24	24
Water	Add. 100	Add. 100	Add. 100	Add. 100	Add. 100	Add. 100	Add. 100

An aqueous ready-to-use liquid mild alkaline cleaning solution is formed, wherein 1.0 g of examples E1 to E7 and V1 to V14 are dissolved in 100 ml of deionized water each.
The cleaning performance of the compositions E1 to E7 compared to V1 to V14 was tested in an automatic metal instrument cleaning apparatus Miele G 7836 CD, Program DES-VAR-TD, 55 °C, 10 minutes.
It was surprisingly found, that the cleaning performance of E1 to E7 are the same of V1 to V14. However, E1 to E7 shows no foam formation at all contrary to V1 to V14.
Further, the average weight loss for aluminum test plates after treatment with said ready-to-use liquid mild alkaline cleaning solution obtained from E1 to E7 compared to V1 to V14 is improved.
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.

Claims

A mild alkaline solid cleaning composition comprising:
- ≥ 10 wt.-% to ≤ 35 wt.-% of at least one alkaline source,

- ≥ 0.1 wt.-% to ≤ 1 wt.-% of at least one polyethylene glycol, and

- ≥ 15 wt.-% to ≤ 40 wt.-% of at least one corrosion inhibitor;
wherein the weight-% ratio of the alkaline source to the polyethylene glycol is > 30 : 1; and wherein the weight-% of the components are based on the total weight of the mild alkaline solid cleaning composition.
The mild alkaline solid cleaning composition according to claim 1, wherein the composition comprises at least two corrosion inhibitors, preferably ≥ 16 wt.-% of an sodium disilicate and ≥ 4 wt.-% of an benzotriazole; wherein the weight-% of the components are based on the total weight of the mild alkaline solid cleaning composition.
The mild alkaline solid cleaning composition according to claims 1 or 2, comprising:
- ≥ 10 wt.-% to ≤ 35 wt.-%, preferably ≥ 13 wt.-% to ≤ 24 wt.-%, and more preferred ≥ 15 wt.-% to ≤ 20 wt.-%, of at least one alkaline source, preferably sodium hydroxide;

- ≥ 0.1 wt.-% to ≤ 1 wt.-%, preferably ≥ 0.2 wt.-% to ≤ 0.8 wt.-%, further preferred ≥ 0.3 wt.-% to ≤ 0.7 wt.-%, and more preferred ≥ 0.4 wt.-% to ≤ 0.6 wt.-%, and most preferred 0.5 wt.-%, of at least one polyethylene glycol, preferably a polyethylene glycol with an average mol weight in the range of 4.000 to 12.000, and more preferred a polyethylene glycol having an average mol weight of 8,000; and

- ≥ 15 wt.-% to ≤ 40 wt.-%, preferably ≥ 18 wt.-% to ≤ 35 wt.-%, further preferred ≥ 20 wt.-% to ≤ 28 wt.-%, and more preferred ≥ 23 wt.-% to ≤ 25 wt.-%, of at least one corrosion inhibitor, preferably sodium disilicate, and more preferred at least two corrosion inhibitors, preferably a benzotriazol and sodium disilicate;

- a solvent, preferably water, is added add. 100 wt.-%; wherein
the weight-% of the components are based on the total weight of the of the mild alkaline solid cleaning composition.
The mild alkaline solid cleaning composition according to claims 1 to 3, wherein the composition comprises at least one alkaline source selected from the group of sodium hydroxide, sodium carbonate, potassium hydroxide, and lithium hydroxide.
The mild alkaline solid cleaning composition according to claims 1 to 4, wherein the composition comprises at least one, preferably two, corrosion inhibitors selected from the group comprising silicate, sodium silicate, sodium disilicate, calcium acetate, calcium chloride, calcium gluconate, calcium phosphate, calcium borate, calcium carbonate, calcium citrate, calcium lactate, calcium sulfate, calcium tartrate, benzotriazole, 1,2,3-benzotriazole, and mixtures thereof.
The mild alkaline solid cleaning composition according to claims 1 to 5, wherein the composition comprises at least one threshold inhibitor/crystal modifier selected from the group comprising salts of phosphonocarboxylic acids, phosphonates, salts of 1-hydroxyethylidene -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.
The mild alkaline solid cleaning composition according to claims 1 to 6, wherein the composition comprises at least one sequestering agent composition selected from the group of sodium gluconate, pentasodium salt of diethylenetriamine pentaacetic acid, sodium glucoheptonate, salts of ethylene diamine tetraacetic acid, salts of ethylene diamine tetraacetic acid, salts of hydroxyethyl ethylene diamine triacetic acid, salts of hydroxyethyl ethylene diamine triacetic acid, salts of nitrilotriacetic acid, salts of nitrilotriacetic acid, diethanolglycine sodium salt, ethanoldiglycine disodium salt, salts of hydroxymonocarboxylic acid compounds, salts of hydroxydicarboxylic acid compounds, salts of amine containing carboxylic acids, terasodium N,N-bis(carboxylatomethyl)-L-glutamate (GLDA) and mixtures thereof.
The mild alkaline solid cleaning composition according to claims 1 to 7, wherein the composition comprises at least one solvent selected from the group comprising water, alcohols, ethanol, isopropanol, 2-butoxy ethanol, 1-decanol, benzyl alcohol, glycerin, monoethanolamine, glycols, ethylene glycol, diethylene glycol, propylene glycol, butoxy diglycol, triethylene glycol, tetraethylene glycol, glycerin, propylene glycol, dipropylene glycol, hexylene glycol, glycol ethers, esters, or combinations thereof. Suitable alcohols include, but are not limited to, ethanol, isopropanol, 2-butoxy ethanol, 1-decanol, benzyl alcohol, glycerin, monoethanolamine, or combinations thereof; preferably the composition comprises at least two solvents and more preferred the composition comprises water and hexylene glycol.
The mild alkaline solid cleaning composition according to claims 1 to 8, comprising:
- ≥ 10 wt.-% to ≤ 35 wt.-%, preferably ≥ 13 wt.-% to ≤ 24 wt.-%, and more preferred ≥ 15 wt.-% to ≤ 20 wt.-%, of at least one alkaline source, preferably sodium hydroxide;

- ≥ 0.1 wt.-% to ≤ 1 wt.-%, preferably ≥ 0.2 wt.-% to ≤ 0.8 wt.-%, further preferred ≥ 0.3 wt.-% to ≤ 0.7 wt.-%, and more preferred ≥ 0.4 wt.-% to ≤ 0.6 wt.-%, and most preferred 0.5 wt.-%, of at least one polyethylene glycol, preferably a polyethylene glycol with an average mol weight in the range of 4.000 to 12.000, and more preferred a polyethylene glycol having an average mol weight of 8,000 ; and

- ≥ 15 wt.-% to ≤ 40 wt.-%, preferably ≥ 18 wt.-% to ≤ 35 wt.-%, further preferred ≥ 20 wt.-% to ≤ 28 wt.-%, and more preferred ≥ 23 wt.-% to ≤ 25 wt.-%, of at least one corrosion inhibitor, preferably sodium disilicate, and more preferred at least two corrosion inhibitors, preferably a benzotriazol and sodium disilicate;

- ≥ 0.5 wt.-% to ≤ 15 wt.-%, preferably ≥ 1 wt.-% to ≤ 10 wt.-%, and more preferred ≥ 3 wt.-% to ≤ 5 wt.-% of at least one threshold inhibitor/crystal modifier, preferably the threshold inhibitor/crystal modifier is a salt of a polyacrylic acid;

- ≥ 5 wt.-% to ≤ 40 wt.-%, preferably ≥ 15 wt.-% to ≤ 30 wt.-%, and more preferred ≥ 20 wt.-% to ≤ 25 wt.-% of at least one sequestering agent, preferably the sequestering agent is a salt of an amine containing carboxylic acid, and more preferred terasodium N,N-bis(carboxylatomethyl)-L-glutamate (GLDA);

- a solvent, preferably water, is added add. 100 wt.-%; wherein
the weight-% of the components are based on the total weight of the of the mild alkaline solid cleaning composition.
A solution of the mild alkaline solid cleaning composition according to claims 1 to 9.
The solution of claim 10, wherein the solution is a concentrated liquid composition or a ready-to-use liquid mild alkaline cleaning solution.
The solution of claim 10 or 11, wherein the ratio of the solvent, preferably water, to solid, to provide a concentrated liquid composition, preferably an aqueous solution, of the mild alkaline solid cleaning composition is in the range of from 200 : 1 to 10 : 1, preferably 100 : 1 to 12 : 1, further preferred 50 : 1 to 15 : 1, also preferred 40 : 1 to 17 : 1 and in particular preferred 30 : 1 to 20 : 1; or
the ratio of the solvent, preferably water, to solid, to provide a ready-to-use liquid mild alkaline cleaning solution, preferably an aqueous solution, of the mild alkaline solid cleaning composition is in the range of from 60,000 : 1 to 100 : 1, preferably 30,000 : 1 to 300 : 1, further preferred 10,000 : 1 to 500 : 1, also preferred 5,000 : 1 to 750 : 1 and in particular preferred 2,500 : 1 to 1,000 : 1.
Use of the solution of claims 10 to 12 to clean hard and soft surfaces, preferably metal and/or plastic articles, metal surfaces and/or plastic surfaces, more preferred metal instruments, plastic instruments, instruments with a plastic surface and/or instruments with a metal surface.
Use of the solution of claim 13 to clean hard and soft surfaces, preferably metal and/or plastic articles, metal surfaces and/or plastic surfaces, further preferred metal instruments, plastic instruments, instruments with a plastic surface, instruments with a metal surface and/or surgical instruments, in an automated processing.