Field of the Invention

The present invention relates to cleaning compositions, in particular to compositions that works as a hard water scale remover, rust remover and a rust inhibitor. The cleaning composition of the present invention is particularly useful in the healthcare industry.

Background of the Invention

Medical equipments and surgical instruments are often in contact with organic contaminants such as disinfectants, human secretions or blood stains. Since these instruments are designed for reuse, they need to be carefully cleaned, disinfected and sterilized to prevent decontamination. Many hospitals are witnessing a shift in trend from manual to automatic washing to clean surgical instruments. The surgical instruments that have signs of rust when received from an operation theatre are usually cleaned by soaking in a rust remover for a period of time before being processed in the auto washers. Automatic washing usually happens in a washer/disinfector or an ultrasonic washer at higher temperatures. However, the water used in a washer/disinfector contains considerably high levels of hardness. This results in scale deposits on the internal walls of the washer which eventually gets transported to the clean instruments during the washing/drying cycle defeating the whole purpose of cleaning. Consequently, the need to de-scale these equipments operating at high temperatures is continuously increasing as this seems to be real burning issue globally. Further many hospitals use rust removers for removing the rust which arise due to inadequate cleaning and drying of surgical instruments after use or sterilization with solutions that eat into the surface.

A wide variety of cleaning formulations are known in the art for the removal of hard water scale and rust deposit from the surface of substrates. In particular, acidic cleaning compositions are known to remove the hard water scale deposit. While acidic cleaners with sulfamic acid such as those disclosed in EP 0778338, WO 9219557 are known, most acid based cleaners have a tendency to corrode due to which rust inhibitors are generally added to the formulations to overcome the problem of corrosion. Rust removing agents are compositions of hydrochloric acid and surfactants and as such they are highly corrosive to metals (e.g. US Patent No. 5,215,676). Further most of these compositions comprise rust inhibitors added to it due to which they suffer from the problem of re-rusting and severe corrosion to metal surfaces after use, thus resulting in secondary rusting and corrosion of metals.

Accordingly, it is an object of the present invention to provide a cleaning composition which will alleviate the above said drawbacks.

Summary of the Invention

The present invention relates to a cleaning composition which acts as a hard water scale remover, rust remover as well as a rust inhibitor.

In a primary aspect the present invention relates to a cleaning composition comprising a balanced combination of one or more organic acids, an inorganic acid, a penetrant, and a surfactant. A balanced combination of one or more organic acids corresponds to essentially a sulfamic acid as a primary organic acid along with a second organic acid.

In a preferred embodiment, the composition comprises based on the total mass of the composition:
0.5 to 2% of sulfamic acid;
5 to 30% of a second organic acid;
1 to 5% of an inorganic acid
5 to 30% of a penetrant
0.05 to 5% of a surfactant and
28% to 88% of water

Yet another embodiment of the present invention relates to a process of treating hard and corroded surfaces wherein a cleaning composition of the present invention is applied in its neat form (undiluted/concentrated solution) or in diluted form, on to said surfaces, then left to act onto said surfaces and then removed by rinsing with water.

The composition can be formulated using conventional mixing methods. Preferable compositions have no off-odor, no irritant odor given off, and no acid mist occurring.

The present invention possesses the following advantages in that the cleaning composition functions as a hard water scale remover, rust remover as well as a rust inhibitor and can be used immediately after the enzyme cleaning cycle and before the high temperature disinfecting/drying cycle in the auto washer of the medical equipments. This would enable to maintain the washing equipment and cleaned equipment free of scale deposits at any point of time. Further such formulations usually might have the tendency to corrode. However the composition of the present invention exhibited a superior property of almost 99% corrosion inhibition without any added corrosion inhibitors. Thus the cleaned instrument using the composition of the present invention was free of rust deposits and was less prone to rust reformation.

However this invention does not exclude the presence of corrosion inhibitor in the cleaning composition. Accordingly in an alternate embodiment this invention also relates to a cleaning composition comprising sulfamic acid, a second organic acid, an inorganic acid, a penetrant, a surfactant and a corrosion inhibitor. The corrosion inhibitor may comprise thiourea, hexamine, methionine or mixtures thereof. The corrosion inhibitor may be present in an amount of 1-10% by weight.

Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating embodiments of the invention, are given by way of illustration only, because various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.

Detailed description of the invention

For the purposes of the following detailed description, it is to be understood that the invention may assume various alternative variations and step sequences, except where expressly specified to the contrary. Moreover, other than in any operating examples, or where otherwise indicated, all numbers expressing, for example, quantities of ingredients used in the specification are to be understood as being modified in all instances by the term "about". It is noted that, unless otherwise stated, all percentages given in this specification and appended claims refer to percentages by weight of the total composition.

Thus, before describing the present invention in detail, it is to be understood that this invention is not limited to particularly exemplified systems or process parameters that may of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments of the invention only, and is not intended to limit the scope of the invention in any manner.

The use of examples anywhere in this specification including examples of any terms discussed herein is illustrative only, and in no way limits the scope and meaning of the invention or of any exemplified term. Likewise, the invention is not limited to various embodiments given in this specification.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. In the case of conflict, the present document, including definitions will control.

It must 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 an "organic acid" may include two or more such organic acids.

The terms "preferred" and "preferably" refer to embodiments of the invention that may afford certain benefits, under certain circumstances. However, other embodiments may also be preferred, under the same or other circumstances. Furthermore, the recitation of one or more preferred embodiments does not imply that other embodiments are not useful, and is not intended to exclude other embodiments from the scope of the invention.

As used herein, the terms "comprising" "including," "having," "containing," "involving," and the like are to be understood to be open-ended, i.e., to mean including but not limited to.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the invention pertains.

In a primary aspect the present invention relates to a cleaning composition comprising sulfamic acid, a second organic acid, an inorganic acid, a penetrant and a surfactant. In another aspect the composition comprises water.

Sulfamic acid is also known as amidosulfonic acid, amidosulfuric acid, aminosulfonic acid, and sulfamidic acid, and has the chemical formula H3NSO3. The compositions of the present invention comprise sulfamic acid which may be added in the composition in its acid form or as alkali metal salts thereof. For example, sulfamic acid may be added as sulfamate. In an embodiment the sulfamic acid may be present in an amount of 0.5 to 2% by weight, preferably in an amount of 0.5 to 1.5% % by weight and more preferably in an amount of 1 to 1.5%

A second organic acid in the composition of the present invention is meant herein to any strong, medium and/or weak organic acids known to those skilled in art with the exception of sulfamic acid. The second organic acids are preferably anionic compounds which are capable of complexing with multivalent metal ions, serving the purpose of accelerating rust removal and lengthening the lifetime of the rust removing agent. Examples of organic acids include but are not limited to citric acid, oxalic acid, aminosulfonic acid, lactic acid, malic acid, tartaric acid, glycolic acid, acetic acid, propionic acid, benzoic acid, nonylbenzoic acid etc., more preferably citric acid and aminosulfonic acid, and most preferably citric acid. In an embodiment the second organic acid may be present in an amount of 5 to 30% by weight, preferably in an amount of 10 to 20 % by weight and more preferably in an amount of 10 to 15%by weight.

The inorganic acid in the composition of the present invention is meant herein to any strong medium and/or weak inorganic acids known to those skilled in the art. Indeed, such acids can be used in their acidic form or in the form of salts, anhydrous or hydrate forms or mixtures. Preferably, the inorganic acids suitable for use in the present invention are medium strong acids, including but not limited to ortho - acid, metaphosphoric acid, boric acid or mixtures thereof. Such inorganic acids are very reactive with metal ions and prone to form chelates with metals dissolved out, serving the purpose of masking. Also, these inorganic acids are poorly volatile and will not generate acid mist, therefore they will not contaminate the surroundings and do harm to the users. More preferable inorganic acids are ortho phosphoric acid or metaphosphoric acid. Phosphate or metaphosphate ions have a good ability to complex ferrous and ferric ions, forming a dense passivation film on the surfaces of stainless steel substrates and preventing further corrosion of the stainless steel metal. In an embodiment the inorganic acid may be present in an amount of 1 to 5% by weight, preferably in an amount of 1 to 3 % by weight and more preferably in an amount of 1 to 2% by weight.

Penetrants can be organic or inorganic penetrants. They can help the bulk rust removing agent to rapidly penetrate a rust film. During this process, the penetrant loosens the adherence of the rust film to the underlying steel surface thereby promoting penetration and wetting and enhancing the rust removing effect. Examples of penetrant would include glycol ether, ethylene glycol monoalkyl ether, ethylene glycol monoaryl ether, diethylene glcyol monoalkyl ether, dialkyl ethers, and esters. Preferred penetrants include but not limited to dipropylene glycol mono methyl ether, 2-butoxy ethanol, ethylene glycol mono methyl ether, ethylene glycol mono ethyl ether, ethylene glycol monopropyl ether, ethylene glycol mono isopropyl ether, ethylene glycol monobutyl ether, ethylene glycol monophenyl ether, ethylene glycol monobenzyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol mono-n-butyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether,ethylene glycol dibutyl ether, ethylene glycol methyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate. The more preferred penetrants are dipropylene glycol mono methyl ether, 2-butoxy ethanol wherein dipropylene glycol mono methyl ether is the most preferred. In an embodiment the penetrant may be present in an amount of 5 to 30% by weight, preferably in an amount of 5 to 20% by weight and more preferably in an amount of 5 to 10% by weight.

Surfactants are contained in the compositions of the present invention which contribute to hard water scale removal. The presence of a surfactant improves the wettability of the surfaces being treated with the cleaning compositions of the present invention. The surfactants used in the present invention are non-ionic in nature. Preferred surfactants are a mixture of alkyl polyglucosides. These are new generation environmental friendly surfactants that are manufactured from renewable resources and are biodegradable. Preferred surfactant are mixture of alkyl polyglucosides namely D-glucopyranoside, Cio-16 alkyl, oligomer and D-glucose, decyl, octyl ethers, oligomer. Some examples of alkyl polyglucosides are alkyl a (+b)-D-mono and oligoglycopylranosides, Cs-i6 alkyl glucoside alkyl glycosides, alkyl polyglycosides (APG), caprylyl glucoside such as octyl glucoside, octyl-beta-D-glucopyranoside, coco-glucoside, decyl glucoside, Cs-i6 fatty alcohol glycoside, Cs-16 fatty alcohol polyglycoside, C12-16 fatty alcohol polyglycoside, D-glucopyranose, oligomeric, C10-16 alkyl glycosides, lauryl glucoside. In an embodiment the surfactant may be present in an amount of 0.05 to 5% by weight, preferably in an amount of 0.05 to 3 % by weight and more preferably in an amount of 0.05 to 1% by weight.

In an alternate embodiment this invention also relates to a cleaning composition comprising sulfamic acid, a second organic acid, an inorganic acid, a penetrant, a surfactant and a corrosion inhibitor. A corrosion inhibitor is a chemical compound that, when added to a liquid or gas, decreases the corrosion rate of a material, typically a metal or an alloy. The corrosion inhibitor which could be used in this invention may be selected from thiourea, hexamine and methionine or mixtures thereof. This may be present in an amount of by weight. In an embodiment the corrosion inhibitor may be present in an amount of 1-10% by weight, preferably in an amount of 1 to 5% by weight and more preferably in an amount of 1 to 2% by weight.

In an embodiment of the present invention the cleaning compositions are in the form of aqueous formulations. Such formulations may comprise from 28% to 88% by weight of the total composition of water, preferably from 50% to 83% and more preferably from 70% to 80%.

The following examples merely illustrate certain aspects of the invention and is to enable those skilled in the art to more clearly understand and to practice the present invention. They should not be considered as limiting the scope of the invention, but merely as being illustrative and representative thereof.

Example 1:
In a preferred embodiment of the present invention, the cleaning composition comprises the following components in % (w/w) based on the total mass of the composition as shown in table 1: Table 1

Ingredients Weight percentage
1. Sulfamic acid 0.5-2
2. Ortho Phosphoric acid 1-5
3. Citric acid monohydrate 10-30
4. C8 -C16 Alkyl polyglucoside 0.05 - 5
5. Dipropylene glycol mono methyl ether 5-30
6 Water 28-88

The composition of the present invention was tested for the following properties:

1. Ability to clean hard water scale deposits
2. Ability to remove rust (corrosion removal)
3. Ability to inhibit rust reformation (measured as corrosion reformation) Example 1 to 15

The composition of Example 1 was prepared according to the present invention and compositions of comparative examples 2 to 15 were prepared with corrosion inhibitors added to the composition as listed below in table 2 and the activities of the compositions of examples 1 and comparative examples 2 to 15 with respect to the different parameters were determined which are shown in table 3.

Table 2

Table 3

Performance Parameter Examples

As evidenced from the above table, the cleaning composition of the present invention exhibited superior activity in terms of the above mentioned properties. The overall performance of the cleaning composition of the present invention is excellent performance parameters even without any added rust inhibitors as compared to those formulations which contain rust inhibitors.

Example 16
Table 4 shows an optional aspect of the invention wherein the composition comprises a corrosion inhibitor.

Table 4

Ingredients Weight percentage
1. Sulfamic acid 0.5-2
2. Ortho Phosphoric acid 1-5
3. Citric acid monohydrate 10-30
4. C8 -C16 Alkyl polyglucoside 0.05 - 5
5. Dipropylene glycol mono methyl ether 5-30
6. Thiourea 1-10

We Claim:

1. A cleaning composition comprising sulfamic acid, a second organic acid, an inorganic acid, a penetrant, a surfactant.

2. The cleaning composition as claimed in claim 1 wherein the second organic acid is selected from citric acid, oxalic acid, aminosulfonic acid, lactic acid, malic acid, tartaric acid, glycolic acid, acetic acid, propionic acid, benzoic acid, nonylbenzoic acid or mixtures thereof

3. The cleaning composition as claimed in claims 1 and 2 wherein the second organic acid is citric acid.

4. The cleaning composition as claimed in claims 1 to 3 wherein the inorganic acid is selected from ortho phosphoric acid, metaphosphoric acid, boric acid or mixtures thereof.

5. The cleaning composition as claimed in claims 1 to 4 wherein the inorganic acid is orthophosphoic acid.

6. The cleaning composition as claimed in claims 1 to 5 wherein the penetrant is selected from glycol ether, ethylene glycol monoalkyl ether, ethylene glycol monoaryl ether, diethylene glcyol monoalkyl ether, dialkyl ethers and esters.

7. The cleaning composition as claimed in claims 1 to 6 wherein the penetrant is glycol ether.

8. The cleaning composition as claimed in claims 1 to 7 wherein the penetrant is dipropylene glycol monomethyl ether.

9. The cleaning composition as claimed in claims 1 to 8 wherein the surfactant is a non-ionic surfactant.

10. The cleaning composition as claimed in claims 1 to 9 wherein the surfactant is C8 -C16 alkyl polyglucoside.

11. The cleaning composition as claimed in claims 1 to 10 wherein a corrosion inhibitor is optionally present.

12. The cleaning composition as claimed in claims 1 to 11 wherein the corrosion inhibitor comprises thiourea, hexamine, methionine or mixtures thereof.

13. The cleaning composition as claimed in claims 1 to 12 wherein the corrosion inhibitor is thiourea.

14. The cleaning composition as claimed in claims 1 to 13 wherein the sulfamic acid is present in an amount of 0.5 to 2% by weight based on the total mass of the composition.

15. The cleaning composition as claimed in claims 1 to 14 wherein the sulfamic acid may be present in an amount of 0.5 to 1.5% % by weight and more preferably in an amount of 1 to 1.5%.

16. The cleaning composition as claimed in claims 1 to 15 wherein the second organic acid is present in an amount of 5 to 30% by weight based on the total mass of the composition.

17. The cleaning composition as claimed in claims 1 to 16 wherein the second organic acid is present in an amount of 10 to 20 % by weight and more preferably in an amount of 10 to 15% by weight.

18. The cleaning composition as claimed in claims 1 to 17 wherein the inorganic acid is present in an amount of 1 to 5% based on the total mass of the composition.

19. The cleaning composition as claimed in claims 1 to 18 wherein the inorganic acid is present in an amount of 1 to 3 % by weight and more preferably in an amount of 1 to 2% by weight.

20. The cleaning composition as claimed in claims 1 to 19wherein the penetrant is present in an amount of 5 to 30% based on the total mass of the composition.

21. The cleaning composition as claimed in claims 1 to 20 wherein the penetrant is present in an amount of 5 to 20% by weight and more preferably in an amount of 5 to 10% by weight.

22. The cleaning composition as claimed in claims 1 to 21 wherein the surfactant is present in an amount of 0.05 to 5% based on the total mass of the composition.

23. The cleaning composition as claimed in claims 1 to 22 wherein the surfactant is present in an amount of 0.05 to 3 % by weight and more preferably in an amount of 0.05 to 1% by weight.

24. The cleaning composition as claimed in claims 1 to 23 wherein the corrosion inhibitor is present in an amount of 1-10% based on the total mass of the composition.

25. The cleaning composition as claimed in claims 1 to 24 wherein the corrosion inhibitor is present in an amount of 1 to 5% by weight and more preferably in an amount of 1 to 2% by weight.

26. The cleaning composition as claimed in claims 1 to 25 wherein it is in the form of aqueous formulation comprising from 28% to 88% by weight of the total composition of water.

27. The cleaning composition as claimed in claims 1 to 26 wherein it comprise water in an amount of 50% to 83% and more preferably from 70% to 80% by weight.

28. A cleaning composition comprising based on the total mass of the composition comprising 0.5 to 1.5% of sulfamic acid, 1 to 3% of ortho phosphoric acid, 10 to 20% of citric acid, 5 to 10% of dipropylene glycol monomethyl ether, 0.05 to 1% of C8 -C16 alkyl polyglucoside.

29. A process of treating hard and corroded surfaces comprising the step of applying a cleaning composition as claimed in claims 1 to 28 on to said surfaces which is then left to act onto said surfaces followed removing the composition by rinsing.