EP0119336B1

EP0119336B1 - Two-pack cleaning preparation, cleaning formulation prepared therefrom and method of cleaning building material therewith

Info

Publication number: EP0119336B1
Application number: EP19830301486
Authority: EP
Inventors: Jeffrey John King
Original assignee: Ceil Clean Corp Inc
Current assignee: Ceil Clean Corp Inc
Priority date: 1981-03-16
Filing date: 1983-03-17
Publication date: 1987-08-12
Also published as: JPS57153099A; CA1171751A; EP0119336A1; AU559448B2; AU8298982A

Description

The present invention is concerned with cleaning of building materials, and preparations and formulations useful therefor.
The building materials which may be cleaned according to the invention include porous cellulosic materials, such as acoustic ceiling tile, wood fibre matrices, blown acoustic mineral matrices comprising perlite combined with white Portland cement, cement and lime, fabrics, painted acoustic surfaces, vinyl and plastics materials, cork, mineral fibres and mineral wool, plastics coated metals, metals, and the like.
Cleaning solutions that are presently employed to clean such building materials generally contain a solution of chlorine bleach or other solutions that contain releasable chlorine as the active ingredient. A cleaning solution would be desirable that could function in a manner similar to chlorine but without the latter's dangerous side effects.
Ammonium persulphate and similar inorganic persulphates that are water soluble are known oxidizing agents, and these persulphate solutions are relatively stable when used alone. However, when used in conjunction with many common cleaner ingredients, the persulphate unfortunately decomposes fairly rapidly, following solution make-up, losing its strength over a short period of time.
It would also be preferable to be able to store an oxidizer in the solid dry form rather than in solution as this would increase the oxidizer storage life considerably, and would save storage and transport costs.
According to the invention, cleaning compositions and a method for cleaning porous building materials are provided using one or more water soluble persulphates as the active oxidizing ingredient. The latter is much safer to use than chlorine and is equivalent in cleaning effectiveness compared to solutions containing chlorine bleach or releasable chlorine.
The invention accordingly comprises a two-pack cleaning preparation which comprises, separately, a water-soluble inorganic persulphate and a stable aqueous solution, or concentrate therefor, containing a cleaning detergent which is unreactive with said persulphate, a soil suspender, a water-miscible organic liquid solvent, a pH adjusting agent, a hydrotrope which is such that said aqueous solution remains in the form of a single phase and, optionally, a chelating agent.
The invention further comprises a cleaning formulation which comprises an aqueous solution as just defined having dissolved therein from 2 to 10% by weight of a water-soluble inorganic persulphate, the persulphate remaining active in the formulation for 5 to 10 days after mixing. The storage life depends to some extent on the purity of the water and the storage temperature.
The invention further comprises a method of cleaning building material, which comprises applying a cleaning formulation as just defined thereto (for example, by spraying), optionally after physical removal of dirt therefrom.
Typical inorganic persulphates for use according to the invention include ammonium persulphate (NH₄)₂S₂0₈, potassium persulphate KSO_S, K_ZS₂0₈, and sodium persulphate NaSO_s, Na₂S₂0₈. Ammonium persulphate is preferred due to its relatively low cost and high and rapid water solubility. From 2.0% to 10% of ammonium persulphate is employed, preferably from 5.0% to 7.0%. All percentages herein refer to parts by weight of the final cleaning solution used for application onto the building material.
Initially, the cleaning formulation is made up in two portions, one portion containing the persulphate, the other portion containing various dirt dissolving compounds, a caustic pH adjusting agent, and stabilizing compounds, is quite stable and relatively free of particulate matter such as precipitates, crystallization and colloidal materials. The dirt dissolving portion of the formulation thus has a relatively long term storage life, and this property enables it to be readily formulated at a factory as a concentrate, shipped and then stored. The final cleaning formulation is produced by mixing appropriate amounts of persulphate and dirt dissolving concentrate with water.
The stability of the cleaning formulation according to the invention is quite surprising since a technical bulletin published by FMC Corporation concerning ammonium persulphate advises that the dry persulphate should not contact solvents, oils, greases and oxidizable organic compounds; the FMC bulletin also states that a solution of ammonium persulphate should not contact strong caustic solutions. Notwithstanding the FMC bulletin, the cleaning formulation of this invention, containing persulphate, can be stabilized in the presence of a variety of organic compounds including solvents, emulsifiers, surfactants, and also caustic solution, and be utilized to safely remove greases, dirt, stains, and so forth.
Since many impurities may be contained in tap water that could catalyse the decomposition of ammonium persulphate, or otherwise reduce its effectiveness, these compounds should be either eliminated or neutralized. Such compounds include bacteria in concentrations that would render the water non-potable, ions such as Ca+2 and Mg⁺² that will react with the cleaner to precipitate alkali or other solution components, or Cu+2 ions which are potent catalysts for the decomposition of persulphates. Generally, if a solution in potable tap water is employed, the problem of bacterial reaction with the persulphate will be minimized.
The use of a chelating agent, such as a nitriloacetic acid derivative, will reduce the effect of hard water ions; usually, a concentration of about 0.03%-0.3%, and preferably about 0.05%-0.1 % will be effective. A preferred chelating agent is hydroxyethyl ethylene diamine triacetic acid tri-sodium salt (such as that marketed by the Dow Chemical Co. as "Versenol 120" (Versenol 120 is a Registered Trade Mark), or by Hampshire Chemical Division of W. R. Grace Co. as "Hampol 120" (Hampol 120 is a Registered Trade Mark)). The Versenol 120 or Hampol 120 appears to aid in the removal of tobacco residue stains more effectively than the more commonly used "Versene 100" (Versene 100 is a Registered Trade Mark) marketed by Dow Chemical Co. which is ethylene diamine tetra acetic acid tetra sodium salt.
A hydrotrope is employed in the dirt dissolving solution to maintain this solution as a single phase and also to stabilize the cleaning formulation formed by combining the oxidizing agent and the dirt dissolving solution. Preferred hydrotropes include Na or K xylene sulphonates, phosphate ester surfactants, or mixtures thereof. The hydrotrope is generally used in the cleaning solution in a concentration range of about 0.5%-3.0% and preferably about 0.8%-1.3%.
Cleaning compounds such as surfactants or emulsifiers are used to emulsify dirt particles which remain on the building material after initial physical cleaning (such as by vacuuming or brushing). The surfactant or emulsifier should be non-reactive with the persulphate, it is preferably one or more of ethoxylated alkyl phenols including octyl or nonyl phenols, ethoxylated fatty acid esters, ethoxylated alcohols, fatty acid sulphates, ether sulphates, and mixtures thereof. When an emulsifier is employed in conjunction with a surfactant, a suitable type that may be used is polyethyleneglycol 400 sesquioleate, sold by Emery Industries, Inc. as "Emerest 2647" (Emerest 2647 is a Registered Trade Mark). A concentration range of about 0.5%-4.0% of the surfactant and/or emulsifier in the cleaning solution is preferred, and more preferably about 0.5%-1.5% is used.
An inorganic soil suspender is used to produce a suspension of solids that are removed from the building material; this minimizes formation of a thick residue that tends to be impervious to an oxidizer because of its thickness. Preferred soil suspenders include tetrapotassium pyrophosphate, sodium tripolyphosphate, Na or K hexametaphosphate and Na and K silicates. Typical soil suspender concentrations are from about 0.1%―4.0%, and preferred concentrations are from about 0.2%-0.5%.
A water miscible organic solvent is used to dissolve organic components in the dirt. Typical solvents include isopropyl alcohol, acetone, ethyl alcohol, ethyl and butyl monoesters of ethylene glycols, methyl ethyl ketone, etc. The solvent and detergent are coupled by the hydrotrope, the latter also coupling the aqueous phase with the non-aqueous phase of the dirt dissolving solution. About 1.0%-6.0%, more preferably about 1.5%-3.5% of the solvent is preferably employed in the cleaning solution.
A base such as NaOH or KOH is generally added to the dirt dissolving and stabilizing solution in a sufficient amount so that the pH of the cleaning solution is about 8-9; this optimizes the activity of ammonium persulphate, and prevents the odour of ammonia. When using ammonium persulphate, a typical concentrate solution pH when formulated at the factory is about 13-14; usually, the KOH concentration in the cleaning solution may vary from about 1 %-6%, but this range can vary widely, depending on the choice of ingredients. If the ammonia odour is not objectionable, or if a persulphate other than ammonium persulphate is used, the pH may be increased to about 9-11. This will increase the persulphate activity somewhat, but will shorten the useful life of the cleaning solution, and will slightly increase the potential skin hazard to the user.
The building material (such as porous acoustic tiles) is initially brushed and/or vacuumed. The cleaning solution is prepared from the concentrate and dry persulphate, and then applied to the physically cleaned tiles, preferably by spraying. With the exception of metal fittings that may catalyze the decomposition of the persulphate, such as mild steel, copper, copper alloys, nickel, etc., the same spraying equipment may be used as that conventionally used for chlorine, thus obviating the need for new equipment. The detergent and solvent action of the cleaning solution will loosen the dirt from the tile surface and then redistribute the dirt over the tile in an even manner. This facilitates a uniform oxidation of the dirt, tobacco and cooking residues, etc., by the persulphate and conversion of these materials to a neutral colour. The tiles are then simply allowed to dry.
When applying the aqueous cleaning formulation containing persulphate, it is preferred to avoid direct contact with the spray, and use of common painter's spray or dust goggles and face mask, and possibly rubber gloves is accordingly recommended. However, unlike chlorine, the spray of this invention does not pose a problem to persons outside the work area because it is not disseminated as a hazardous gas, with the exception of minor amounts of solvent.
If the water used is of very good quality and low hardness, the amount of chelating agent used may be reduced below the lower concentration of 0.03% specified earlier. Furthermore, the amount of phosphate ester or similar surfactant used as the hydrotrope may be increased above the upper concentration of 3.0% specified earlier and can thereby function partly or completely in place of the preferred polyoxyethylene-9-octyl (or -nonyl) phenol surfactant. If the material to be cleaned is extremely dirty, a cleaning formulation having a persulphate concentration approaching the upper limit of 10% or having a pH in the range 9 to 11, as referred to earlier, may be used, or a second application of the formulation may be made. If desired, an optical brightener may be included in the cleaning formulation to enhance the brightness of the cleaned surface.

Claims

1. A two-pack cleaning preparation which comprises, separately, a water-soluble inorganic persulphate and a stable aqueous solution, or concentrate therefor, containing a cleaning detergent which is unreactive with said persulphate, a soil suspender, a water-miscible organic liquid solvent, a pH adjusting agent, a hydrotrope which is such that said aqueous solution remains in the form of a single phase and, optionally, a chelating agent.

2. A preparation according to claim 1, in which the cleaning detergent is an ethoxylated alkyl phenol, an ethoxylated alcohol, an ethoxylated fatty acid ester, a fatty acid sulphate, an ether sulphate, or a mixture thereof.

3. A preparation according to claim 1 or 2, in which the soil suspender is tetrapotassium pyrophosphate, sodium tripolyphosphate, sodium or potassium hexametaphosphate or a sodium or potassium silicate, and/or in which said organic-liquid solvent is isopropanol, ethanol, acetone, methyl ethyl ketone or ethylene glycol monobutyl ether.

4. A preparation according to any of claims 1 to 3, in which said pH adjusting agent is NaOH and/or KOH.

5. A preparation according to any of claims 1 to 4, in which said hydrotrope is sodium or potassium xylene sulphonate, a phosphate ester surfactant, or a mixture thereof.

6. A preparation according to claim 5, in which the chelating agent is hydroxyethyl ethylene diamine triacetic acid trisodium salt, the cleaning detergent is polyoxyethylene octyl- or nonyl-phenol or polyethylene glycol sesquioleate, the soil suspender is tetrapotassium pyrophosphate, the organic liquid solvent is isopropanol and the pH adjusting agent is KOH.

7. A preparation according to any of claims 1 to 6, in which said aqueous solution has the following composition (in parts by weight):

8. A cleaning formulation which comprises an aqueous solution as defined in any of claims 1 to 7, having dissolved therein from 2 to 10% by weight of a water-soluble inorganic persulphate.

9. A cleaning formulation according to claim 8, in which the water-soluble inorganic persulphate is ammonium persulphate, potassium persulphate, or sodium persulphate.

10. A method of cleaning building material, which comprises applying a cleaning formulation according to claim 8 or 9 thereto, optionally after physical removal of a portion of dirt therefrom, and allowing the solvent and water to evaporate.