GB1604562A

GB1604562A - Process for keeping clean internal and external surfaces in danger of contamination

Info

Publication number: GB1604562A
Application number: GB22604/78A
Authority: GB
Original assignee: UNILEASE
Current assignee: UNILEASE
Priority date: 1977-05-25
Filing date: 1978-05-25
Publication date: 1981-12-09
Also published as: FR2391784A1; SE7805937L; ATA362278A; DE2723493B2; DE2723493A1; BE867438A; CH621071A5; SE438322B; NL7805662A; DK230078A; AT373794B; LU79698A1; FR2391784B1

Abstract

To keep clean internal or external surfaces at risk of fouling, a protective layer is applied to the surfaces to be treated and after fouling has taken place, the dirt is removed. For this purpose, a film former composition is used in the form of a solution or dispersion which contains a film former which, after drying, forms a protective layer which is soluble in water, sparingly soluble in water, sparingly soluble in water but swellable, insoluble in water or insoluble in water but swellable. This film former composition is applied to the surface to be treated and allowed to dry. The surface obtained in this manner, furnished with a protective coating, after fouling has occurred, is treated with a film former composition or with water or an aqueous medium for cleaning, at least part of the protective coating being left. Virtually all types of surfaces can be treated in this manner, in particular glass, ceramics, metal, plastics, wood, carpets and fabrics, and it is irrelevant whether these are internal or external surfaces.

Description

(54) A PROCESS FOR KEEPING CLEAN INTERNAL AND EXTERNAL SURFACES IN DANGER OF CONTAMINATION (71) We, UNILEASE S.A. a body corporate organised under the laws of Luxembourg of Boulevard de la Petrusse, 92 Luxembourg, Luxembourg do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to a process for keeping clean internal and external surfaces in danger of contamination.

Various proposals have been made for providing surfaces in danger of contamination with a protective layer for protection against contamination, which protective layer is completely removed together with the dirt after contamination has occurred, before being renewed.

Thus, it is known from U.S. Patent No. 2,986,471, to coat cars with a protective layer based on sodium carboxy-methyl cellulose for protection against the remains of insects and to wash off the protective layer together with the remains of insects once contamination has occurred. According to Australian Patent No. 70178/74, external surfaces are coated for protection against contamination with a protective layer which is insoluble in neutral and slightly acidic aqueous solutions but is at least partially soluble in alkaline solutions, which protective layer is removed together with the dirt, after contamination and prior to renewal, by means of treatment with an alkaline aqueous cleaning solution.

These previously known cleaning processes have the disadvantage that the surfaces to be protected from contamination have to be exposed alternately to the action of the film-forming composition and the action of the aqueous or aqueous alkaline cleaning solutions used to remove the protective layer, so that, in particular, relatively sensitive surfaces, for example lacquered surfaces can be damaged with time. In addition, this combination of removing the protective layer and applying a film-forming agent demands a relatively high outlay in labour.

We have now found that these disadvantages can be avoided if the protective layer applied to the surface to be protected is not completely removed after contamination so that the invention is not based on cleaning but on keeping clean the surfaces to be protected.

The present invention provides a process for keeping clean internal and external surfaces in danger of contamination, a protective layer being applied to the surfaces to be treated, optionally after fundamental cleaning, and the dirt being removed after contamination has occurred, wherein a film-forming composition in the form of a solution or dispersion containing a film-forming agent which forms after drying a protective layer which is soluble in water, sparingly soluble in water, sparingly soluble but capable of swelling in water, insoluble in water or insoluble but capable of swelling in water, which protective layer may contain or absorb moisture, is applied to the surface to be treated and left to dry, and the surface thus obtained and provided with a protective layer is treated after contamination has occurred with a film-forming composition for cleaning purposes, only the surface of the protective layer being removed during said cleaning.

The film-forming composition is applied to the surface to be treated, preferably in the form of an aqueous solution or dispersion which optionally contains organic solvents in the medium. Alternatively, the composition may be used in the form of a solution or dispersion in an organic solvent. A few examples of this composition include: aliphatic or aromatic hydrocarbons, ketones, esters, alcohols, pyrrolidones and/or ethers. When selecting the solvent or dispersant, attention should be paid to compatability both with the film-forming agent and with the surface to be treated. The type of composition preferred depends upon the properties of solubility or dispersion of the film-forming agent used. The use of film-forming compositions with organic solvents is preferred when forming water-insoluble protective layers.

Film-forming compositions which form a moisture-containing and/or moisture-absorbing film after application are preferred.

By subjecting the surface provided with a protective layer to a cleaning treatment with the film-forming composition, after contamination, partial removal of the protective layer together with the dirt (the dirt adheres substantially to the film-forming agent applicator) and new application of a film-forming composition are performed simultaneously with initial dissolving of the protective layer surface, that is to say in one operation.

In so doing, the original, that is to say the already present, protective layer is bonded to the newly applied film-forming composition and a uniform protective layer is formed.

As an intermediate measure before cleaning the contaminated protective layer with a film-forming composition, it is possible to clean the free surface of the protective layer with a neutral, alkaline or acidic aqueous medium which can contain the surface-active agent and/or organic solvents. Such a cleaning treatment is recommended if contamination is very marked or if the film-forming composition used for cleaning is to be economised.

An advantage which may be achieved by means of the process according to the invention is, in addition to that already mentioned of the saving produced by having only one operation that the surface in danger of contamination is permanently coated with a protective layer which has the function of providing a separating layer between the surface and dirt. The protection and maintainance of cleanliness of the surface to be treated is ensured better by this permanent protective layer than by the previously known processes.

The process according to the invention may be applied in practice to substantially all types of surfaces. Some examples include glass, ceramics, metals, plastics material, concrete, wood, carpets and fabrics.

The selection of film-forming agent depends upon whether the surface to be protected is an internal or an external surface.

Thus, in the protection of internal surfaces, for example tiled walls, floors, floor coverings and windows, preference is given to film-forming agents which form a water-soluble protective layer after drying. However, in the protection of external surfaces, for example, outer surfaces of windows, facades of houses, means of transport, preference is given to the film-forming agents which form, after drying out, a protective layer which is sparingly soluble to insoluble and/or capable of swelling in water, that is to say substantially insensitive to climatic factors.

The selection of film-forming agents is also based on the desired degree of susceptibility to water of the protective layer obtained, once the film-forming agent has dried out. Since the film-forming agent's properties of solubility and ability to swell are known, a skilled man has to seek out from the film-forming agents available only those which are best suited to the purpose intended: application on external or internal surfaces.

A few examples of 'suitable film-forming agents include: cellulose ethers, alginates, polyacrylates, polyvinylalcohol, polyvinylpyrrolidone, dextrins, silicates, gum arabic, tragacanth, dimethylhydantoin-formaldehyde-condensates, urea formaldehyde condensates and their derivatives, sulphite waste liquors, oxylignin, polymethylvinyl ether-maleic acid anhydride, shellac, polyesters, phenol resins, polyamides, copolymers of vinyl acetate, ketone resins, silicone resins, melamine resins, rubber resins, oxidising resins, alone or in a mixture.

The proportions in which the film-forming agents are used in the film-forming composition can vary within wide ranges. They depend upon the type of the film-forming agent or agents used and preferably amount to approximately 0.5 to approximately 80% by weight, based on the composition.

The proPerties of the protective layer obtained once the film-forming agent has dried out can be adjusted by means of additives to the respective purpose. Examples of such properties are such as water-solubility, ability to swell in water, moisture content - which can also be controlled by means of the hygroscopicity - water-repellant properties, elasticity, plasticity, transparency and/or adhesion.

A few examples of additives which may be contained in the film-forming composition include : to improve the plasticity or adhesion of the protective layer: alcohols, glycols, glycolether, pyrrolidone; to change the flow properties of the film-forming composition as well as the ability to swell and the speed of drying of the protective layer: surface-active agents and solvents; to increase the water-resistance of a protective layer based, in particular, upon cellulose ethers, alginates, dextrin: aldehydes, aldehyde-separating materials, maleic acid anhydride, melamine resins, formic acid, pyrrolidone, chromium salts, zinc salts; to increase the water-resistance of a protective layer based on phenol resin: oleic acid, naphthenic acid, tatty acids, phosphoric acid ester, dicarboxylic acid anhydride; to improve the transparency of the protective layer: glycols, surface-active agents.

The selection of the film-forming composition to be used for cleaning the protective layer as well as the aqueous media suitable for intermediate cleaning also depend upon the selection of film-forming agent or its degree of water-solubility or ability to swell in water.

Although essentially the same film-forming composition may be used for cleaning the protective layer as for forming the protective layer, the process according to the invention also provides the opportunity of subsequently modifying, for example, the properties of solubility of the protective layer by changing the film-forming composition. A condition ior this is that the film-forming composition used for cleaning the protective layer is compatible with the protective layer to be cleaned.

This variation in the process can be of particular importance in keeping clean external surfaces, in particular ficades of houses, metallic window frames and hoardings. External surfaces of this type, which are usually not completely resistant to the waste gases and particles of dirt, fat or oil contained in the air in large towns, can - optionally after fundamental cleaning - initially be safely protected from the atmospheric incluences, including the dirt contained in the air, by treatment with a film-forming agent which dries out to a water-insoluble protective layer which is optionally capable of swelling.This water-insoluble protective layer can then be modified in water-solubility by means of a surface cleaning treatment with a film-forming composition which begins to dissolve the protective layer and forms a film which adheres well to it, in such a way that it provides access for intermediate cleaning treatments with aqueous acidic or alkaline media, without the basic protective layer having to be removed completely.

Intermediate cleaning treatments can be substantially reduced if the free outer surface of the protective layer is made water-soluble or can form water-soluble salts in a slightly acidic environment, for example, in the air of large towns which contains waste gases, since self-cleaning is performed to a certain extent by rain. It is then only necessary to give the surface a cleaning treatment with the film-forming composition for the base layer or with the film-forming composition for the surface layer at relatively long intervals, as required.

An example of film-forming compositions, which form a watcr-soluble protective layer in a slightly acidic environment after drying out, contains phenol resins.

The selection of the aqueous media used for the intermediate cleaning of the protective layer also depends upon the choice of film-forming agent. If the protective layer is soluble or dispersible in water, as should be the case in particular with protective layers applied on internal surfaces, intermediate cleaning is beneficially carried out with water, to which, for example, conventional detergents may be added, if necessary.If the protective layer is sparingly soluble to insolube in water, intermediate cleaning - adapted to the specific solubility properties of the protective layer to be cleaned superficially with initial dissolution-is performed with an aqueous medium optionally containing the conventional detergents, surface-active agents and organic solvents, which is made alkaline in the usual way, for example with alkalis, ammonia, amines or which is made acidic in the usual way.

With protective layers which are capable of swelling in water, the ability to swell may be accelerated by mechanical treatment using brushes with a supply of water. As already mentioned above, the process according to the invention may be applied with success to the cleaning both of external surfaces and of internal surfaces.

External surfaces include all surfaces which are exposed to the weather and the dirt and noxious substances contained in the air, the cleaning of which is desired. A few examples include: facades of houses, for example of metal, eloxated aluminium, metal window frames, external faces of windows, of shop-windows, hoardings; external surfaces of means of transport such as railway, tram, of motor vehicles such as private cars, lorries, buses, aeroplanes, ships; traffic signs, and animal cages.

Internal surfaces include all surfaces located in interiors and exposed to contamination. A few examples include: internal surfaces of windows, interiors which are cleaned, including stair well, internal surfaces of shop-windows, of railway carriages, of the medical and paramedical and health fields, of wet areas such as swimming baths, and stalls for keeping animals.

Surfaces located in interiors, which may also be kept clean according to the invention include: upholstery; floor coverings of any type, for example, carpets, carpet tiles; drapery and curtains made of synthetic materials, wool and/or cotton.

The protective layers obtained with the invention are clear or opaque and matt to highly lustrous, depending upon the film-forming material used. Additional proPerties may be imparted to them by using film-forming compositions containing suitable additives.

A few examples include: dyestuffs, pigments, ultra-violet absorbents, complex-forming agents, chelates, sequestering agents, hydrophobic agents, such as silicones, cation-active compounds, phosphoric acid ester, disinfectants such as hydroxy benzoic acid and/or its derivatives, in particular its ammonium or amine salts, such as the alkanolamine, morpholine salts, iodine compounds, or iodine-separating compounds, quaternary com- pounds, organo-metallic compounds, aldehydes or aldehyde-separating compounds, microbiocides as well as agents which alter the hygroscopicity of the protective layer, alone or in a mixture.

The proportions in which the additives are added to the film-forming composition may vary within a wide range. They depend upon the type and the degree of the action desired by the addition. They amount to approximately 0.01 to approximately 15, preferably approximately 0.05 to approximately 16, in particular approximately 0.05 to approximately 7% by weight based on the film-forming composition.

It has also been found that by means of additives to the film-forming composition, it is also possible to impart to the protective layer, obtained after drying out, activities against the dirt considered at any time, more particularly both against the dirt which has settled on the surface after coating and against dirt which originates from the uncoated surface if the film-forming composition is applied to a contaminated surface.

The proportions in which these additives are used can vary within a wide range. They depend upon the additive and the desired effect. They usually amount to approximately 0.5 to approximately 25, preferably approximately 0.5 to approximately 2 , in particular approximately 0.5 to approximately 15% by weight, based on the film-forming composition.

If the dirt under consideration is, for example, raised earth, metal oxides, that is dirt which mainly effects means of transport, in particular rail vehicles, and is sensitive to acid, or if the dirt comprises calcium deposits which are also sensitive to acid and are found in factories producing food-stuffs, then it has proven beneficial to have additives of an acidic nature to the film-forming compositions. A few examples include: acidic phosphoric acid ester, optionally halogenated acetic acid, citric acid, formic acid, glycolic acid, gluconic acid, oxalic acid, boric acid, phosphonic acid, phosphoric acid, phosphorous acid, hypohosphorous acid and benzoic acid.

Additives of this type contained in protective layers have been found to act on the dirt, for example on rail vehicles such as railway engines and railway carriages when the vehicle is in use, thus between cleaning treatments, so that when the contaminated protected layer is cleaned with the film-forming composition, acid-sensitive dirt, such as metal oxides (rust), is removed more easily and more completely using substantially less acid than is the case in the previously known cleaning methods.

In the previously known methods, for example, the rail vehicles are washed with hydrochloric acid, phosphoric acid and/or oxalic acid between being used twice, in order to clean the exterior.

This acid wash does however have the following disadvantages: hydrochloric acid cannot be used for engines and carriages with refined steel or aluminium facings, for reasons of corrosion. Corrosion, for example by under-rusting, also has to be taken into consideration in the other spheres, for example in the case of window frames. Phosphoric acid has only a slight cleaning action, tends to form aluminium and calcium phosphates which lead to efflorescence both on the carriage wall and on the bogies, and has to be used in high concentrations even for slight contamination. The use of oxalic acid is hazardous in the protection of labour. Furthermore, all three acids have to be neutralised in a clarifying plant, their salts, the chlorides, phosphates and oxalates remaining in the waste water.In addition, the surface-active agents contained in the purifiers lead to re-emulsification of the oil contained in the dirty water.

Apart from this, fats and the protein originating from gnats as well as lubricating fats and lubncating oils from acidic purifiers can be removed only with difficulties.

Alkaline cleaning agents are more suitable for this purpose but do however lead to marked corrosion phenomena on window frames, in particular those made of aluminium or aluminium alloys, and to changes in the paint, even two component paints. In addition, they cannot be used for removing the metal oxides which are produced in substantial quantities on rail vehicles. The alkaline cleaning agents also have to be neutralised in the clarifiers and this is associated with undesirable salt formation. Furthermore, protective masks have to be used in part when working with alkaline, in particular ammoniacontaining, cleaning agents.

The combination of acid cleaner with alkali cleaner which is necessary for complete cleaning in the previously known methods, demands not only high labour costs, but leads with time to damage to the material to be cleaned as well as to deterioration of concrete surfaces, pipework, containers and clarifying plant. Furthermore, the cleaning of metal oxides, in particular rust, achieved in this way is not satisfactory.

The process according to the invention differs from these previously known cleaning methods in simpler process control - for removing the acid-sensitive dirt such as, for example, rust. Only one cleaning treatment with film-forming composition or with an aqueous medium is necessary, providing the protective layer is thick enough not to be completely removed. The method according to the invention also differs in a substantially smaller loading of waste water and in substantially safer protection of the surfaces exposed to contamination, which surfaces are substantially permanently protected by the measure of subjecting only the surface of the protective layer to a cleaning treatment.

In addition, the action of the additives on the dirt can be adapted to respective conditions by combining the above-mentioned additives. It has thus proven advantageous to combine one of the sparingly evaporating acids, for example acidic phosphoric acid ester, with the readily evaporating formic acid. The very active formic acid exerts - until it has evaporated an initial action on the acid-sensitive dirt, converts, for example, a proportion of the metal oxides into soluble formiates and thus simplifies the attack and the action, for example of the acidic phosphoric acid esters which evaporate more slowly. Rapidly evaporating acids which form soluble salts with metal oxides may also be used instead of the formic acid.

The protective layer should contain moisture which can either originate from production or be taken from the air later on, so that the additives can develop their whole effect on the dirt.

If the process according to the invention is to be used for keeping clean surfaces which are exposed mainly to contamination by basically reacting substances such as for example fats, proteins and lubricants, then it has proven beneficial to add to the film-forming compositions additives which act on fats, proteins and lubricants. A few examples for such additives which are usually basic include: alkalihydroxides, alkanolamines, phosphates, silicates and/or gluconates, carboxylic acid salts, carboxylic acid amides.

These additions are preferably added to film-forming compositions which are intended for cleaning surfaces which have been contaminated by fat such as for example kitches, engine compartments and bogies.

Film-forming compositions which can contain these additives may be used particularly advantageously for keeping clean reflective, highly lustrous or transparent surfaces, for example window panes. If, for example, the window panes are provided with a protective layer after a fundamental cleaning treatment, a surface cleaning treatment of the protective layer with the film-forming composition or - if the protective layer is still sufficiently thick with water, is sufficient cleaning for the window panes in order to obtain clear panes. The inconvenient task of rubbing the panes dry is eliminated.This is eliminated in that, during the cleaning treatment with the film-forming solution or even with water, the dirt on the surface in the form of, for example, particles of dust, remains suspended in the article used for applying the cleaning fluid, for example washing cloth, brush or sponge, and the dirt remaining on the protective layer in the form of fats and oil as well as finger pnnts - if it does not also adhere to the applicator - is taken up into the protective layer which has begun to dissolve or is softened by the cleaning treatment with the film-forming composition or water, and becomes invisible when the protective layer dries out.

The process according to the invention may also be applied successfully to the keeping clean of toilets and humid rooms such as baths. In actual fact, film-forming compositions which upon drying form a protective layer which is sparingly soluble to insoluble in water but capable of swelling in water are also used in the case of interior surfaces. If disinfectant and/or microbiocides are added to the film-forming composition, it is possible, for example, in this way to counteract the foot fungus frequently encountered in baths: Trichophyton mentagrophytes, since, upon contact with wet feet, the protective layer swells at least so that the disinfectant can become effective. The disinfectants and/or microbiocides suitable for this purpose should have a vapour pressure which is as low as possible under the prevailing conditions in order to act for as long as possible.Other example of additives for humid rooms are: complex-forming agents, chelates and sequestering agents which counteract the hardness of water.

Similarly, when applying the process according to the invention in the health, medical and paramedical fields, for example in intensive care units, operating theatres, the permanent sterility needed for these environments may be obtained by using film-forming compositions which contain microbiocides and/or disinfectants.

If the process according to the invention is to be applied for keeping clean metallic surfaces, for example those made of iron and aluminium, which apart from the usual contamination from outside, are subjected to self-oxidation promoted by the noxious substances in the air, film-forming compositions are beneficially used which contain as additives nitric acid, nitrous acid or salts of these acids.

When using film-forming compositions which contain cellulose ether or cation-active resins, for example phenol resins, as film-forming agents, and react acidly or are adjusted acidly, for keeping clean aluminium or iron surfaces, effective corrosion protection may be obtained with the application of the protective layer, even without further additions.

A few examples of preferred mixtures for keeping clean or for cleaning according to the invention are: A) A film-forming composition for use in keeping internal surfaces clean containing about 0.5 to about 15% by weight of water-soluble cellulose ether about 0.5 to about 7% by weight of amine salt of polymethylvinyl-ether maleic acid anhydnde about 0.5 to about 5% by weight of glycols about 0.05 to about 2% by weight of surface-active agents about 0.5 to about 20% by weight of isopropyl alcohol about 0.00 to about 5% by weight of disinfectant and remainder water.

B) A film-forming composition for use in keeping internal surfaces clean containing about 0.5 to about 10% by weight of water-soluble urea formaldehyde condensate and/or polyacrylates about 0.5 to about 5% by weight of giycol about 0.05 to about 2% by weight of surface-active agents about 0.5 to about 20% by weight of isopropylalcohol about 0.00 to about 5% by weight of disinfectant and remainder water.

C) A film-forming composition for use in keeping external surfaces clean, in particular of means of transportation containing about 1 to about 10% by weight of cellulose ethers which are sparingly soluble to insoluble and/or capable of swelling in water, about 0.5 to about 10% by weight of polymethylvinyl ether maleic acid anhydride about 1 to about 20% by weight of formic acid about 1 to about 10% by weight of acidic phosphoric acid ester and/or halogenated acetic acid about 1 to about 10% by weight of glycols about 0.05 to about 5% by weight of surface-active agents about 0.05 to about 5% by weight of acetone about 0.5 to about 5% by weight of sulphite waste liquors remainder water.

D) A film-forming composition for use in keeping external surfaces clean, in particular of means of transportation, which are exposed to contamination by oil and/or fat and dirt containing about 1 to about 40% by weight of potassium and/or sodium silicates which are sparingly soluble to insoluble and/or capable of swelling in water or about 0.5 to about 10% by weight of polyacrylates and about 0.5 to about 15% by weight of complex-forming agents about 0.5 to about 10% by weight of sulphite waste liquors or oxylignins about 0.05 to about 15% by weight of surface-active agents about 0.00 to about 4% by weight of dyestuffs and remainder water.

The invention will be described in more detail by the following examples.

Example I (Suitable for keeping external surfaces clean, in particular of rail vehicles) 5% by weight hydroxyethylcellulose 10% by weight formic acid 1% by weight phosphoric acid ester 1% by weight glycols (monoethylene glycol) 0.5% by weight surface-active agents 2% by weight acetone 2% by weight sulphite waste liquors 0.5% by weight salt of polymethylvinylether-maleic acid anhydride and remainder water.

The cleaning treatment is carried out with film-forming compositions or - if the protective layer is still sufficiently thick - with water and aqueous acid or aqueous alkaline solutions, optionally in conjunction with a mechanical treatment, for example by means of brushes.

Example 2 (Suitable for keeping internal surfaces of windows clean, in particular of rail vehicles).

5% by weight of hydroxyethylcellulose 1% by weight of glycols (monoethylene glycol) 0.5% by weight surface-active agents (sugar ester, Type BG 10) 2% by weight of isopropylalcohol 0.5% by weight of salt of polymethylvinylethermaleic-anhydride 0.1% by weight of morpholine salt of hydroxybenzoic acid remainder water.

Example 3 (Suitable for keeping internal surfaces of windows clean, in particular, of rail vehicles) 5% by weight of urea (formaldehyde condensate) 1 % by weight of glycol (triethylene glycol) 0.5 % by weight of surface-active agents (succinates) 2% by weight of isopropylalcohol remainder water.

The cleaning treatment of the protective layers obtained according to Examples 2 and 3 is carried out with film-forming composition or, if the protective layer is still sufficiently thick, with water, in conjunction with a mechanical treatment by means of a sponge.

Example 4 (Suitable for keeping clean parts of rail vehciles contaminated by oil and/or fat and solid particles of dirt) 10% by weight of potassium and/or sodium silicates 2% by weight of complex-forming agents (Trilon registered trade mark) A,B,D; cf.

Rompp Chemielexikon, 6th edition, column 6646) 3% by weight of sulphite waste liquor 3% by weight of surface-active agents (Type BG 10) 0.1% by weight of Monflor (trade mark) 31, a fluorine surface-active agent; (cf. Rompp Chemielexikon, 7th edition, page 2212) remainder water.

The cleaning treatment is carried out with a film-forming composition or, if the protective layer is still sufficiently thick, with pressurised water at about 3 atmospheres and at about 60"C.

WHAT WE CLAIM IS: 1. A process for keeping clean internal or external surfaces in danger of contamination, wherein a film-forming composition in the form of a solution or dispersion containing a film-forming agent which forms on drying a protective layer which is soluble in water, sparingly soluble in water, sparingly soluble but capable of swelling in water, insoluble in water or insoluble but capable of swelling in water, is applied to the surface to be treated and left to dry, and the surface thus obtained, provided with the protective layer, is treated with a film-forming composition for cleaning purposes after contamination, only the surface of the protective layer being removed during said cleaning.

2. A process as claimed in claim 1, wherein the surface to be treated is given a fundamental cleaning treatment prior to the first application of the protective layer.

3. A process as claimed in claim 1 or 2, wherein either or both of the film-forming compositions in the form of an aqueous solution or dispersion.

4. A process according to claim 1 or 2, wherein a film-forming composition whose liquid medium consists of organic solvent or dispersant is used.

5. A process according to any of claims 1 to 3, wherein a film-forming composition with a film-forming agent which forms on drying a moisture-containing and/or moistureabsorbing protective layer is used.

6. A process according to any preceding claim, wherein as an intermediate measure, the free side of the protective layer is cleaned with a neutral, alkaline or acidic aqueous medium which may contain surface-active agents and/or organic solvents, before subsequent application of a film-forming composition.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. The cleaning treatment is carried out with film-forming compositions or - if the protective layer is still sufficiently thick - with water and aqueous acid or aqueous alkaline solutions, optionally in conjunction with a mechanical treatment, for example by means of brushes. Example 2 (Suitable for keeping internal surfaces of windows clean, in particular of rail vehicles). 5% by weight of hydroxyethylcellulose 1% by weight of glycols (monoethylene glycol) 0.5% by weight surface-active agents (sugar ester, Type BG 10) 2% by weight of isopropylalcohol 0.5% by weight of salt of polymethylvinylethermaleic-anhydride 0.1% by weight of morpholine salt of hydroxybenzoic acid remainder water. Example 3 (Suitable for keeping internal surfaces of windows clean, in particular, of rail vehicles) 5% by weight of urea (formaldehyde condensate) 1 % by weight of glycol (triethylene glycol) 0.5 % by weight of surface-active agents (succinates) 2% by weight of isopropylalcohol remainder water. The cleaning treatment of the protective layers obtained according to Examples 2 and 3 is carried out with film-forming composition or, if the protective layer is still sufficiently thick, with water, in conjunction with a mechanical treatment by means of a sponge. Example 4 (Suitable for keeping clean parts of rail vehciles contaminated by oil and/or fat and solid particles of dirt) 10% by weight of potassium and/or sodium silicates 2% by weight of complex-forming agents (Trilon registered trade mark) A,B,D; cf. Rompp Chemielexikon, 6th edition, column 6646) 3% by weight of sulphite waste liquor 3% by weight of surface-active agents (Type BG 10) 0.1% by weight of Monflor (trade mark) 31, a fluorine surface-active agent; (cf. Rompp Chemielexikon, 7th edition, page 2212) remainder water. The cleaning treatment is carried out with a film-forming composition or, if the protective layer is still sufficiently thick, with pressurised water at about 3 atmospheres and at about 60"C. WHAT WE CLAIM IS:

1. A process for keeping clean internal or external surfaces in danger of contamination, wherein a film-forming composition in the form of a solution or dispersion containing a film-forming agent which forms on drying a protective layer which is soluble in water, sparingly soluble in water, sparingly soluble but capable of swelling in water, insoluble in water or insoluble but capable of swelling in water, is applied to the surface to be treated and left to dry, and the surface thus obtained, provided with the protective layer, is treated with a film-forming composition for cleaning purposes after contamination, only the surface of the protective layer being removed during said cleaning.

7. A process according to any of claims 1 to 3 or 5, wherein, in order to keep internal

surfaces clean, a film-forming composition with a film-forming agent which dries to form a water-soluble protective layer is used and the protective layer thus obtained is cleaned with the film-forming composition used for forming the protective layer or with water or with an aqueous medium.

8. A process according to any of claims 1 to 4, wherein, in order to keep external surfaces clean, a film-forming composition with a film-forming agent which dries to form a protective layer which is sparingly soluble but capable of swelling in water is used and the protective layer thus obtained is cleaned with the film-forming composition used for forming the protective layer or with an aqueous medium.

9. A process according to claim 8, wherein the protective layer is cleaned mechanically.

10. A process according to any of claims 1 to 3, wherein, in order to keep external surfaces clean, a film-forming composition with a film-forming agent which dries to form a protective layer which is insoluble in water is used and the protective layer thus obtained is cleaned with the film-forming composition used for forming the protective layer or with a film-forming composition containing a film-forming agent which dries to form a protective layer which is soluble or sparingly soluble in water, which may be removed partialIy or wholly with aqueous, acidic or alkaline medium.

11. A process according to claim 10, wherein the protective layer which is soluble or sparingly soluble in water is also caPable of swelling in water.

12. A process according to any of claims 1 to 5, and 7 to 11, wherein a film-forming composition is used which contains as film-forming agent cellulose ethers, alginates, poly-acrylates, polyvinyl alcohol, polyvinylpyrrolidone, dextrins, silicates, gum arabic, tragacanth, dimethylhydantoin-formaldehyde condensates, urea-formaldehyde condensates, urea-formaldehyde condensates and their derivatives, sulphite waste liquors, oxylignin, polymethylvinyl ether-maleic acid anhydride, shellac, polyester, phenol resins, polyamides, copolymers of vinyl acetate, ketone resins, silicone resins, melamine resins, rubber resins, oxidising resins, alone or in a mixture.

13. A process according to any of claims 1 to 5 and 7 to 12, wherein the film-forming composition used contains as additives, dyestuffs, pigments, ultra-violet absorbents, complex-forming agents, chelates, hydrophobic agents, disinfectants, microbiocides, acidic additives active against acid-sensitive dirt, basically acting additives which are effective against fats and proteins, or water-fixing materials, alone or in a mixture.

14. A process according to claim 13, wherein the basically acting additives which are effective against fats and proteins, comprise any of the following: alkali hydroxides, alkanol amines, amides, phosphates, silicates and giuconates.

15. A process according to claim 13, wherein the acidic additives active against acid-sensitive dirt, comprise any of the following: acidic phosphoric acid esters, halogenated acetic acids, citric acid, formic acid, glycolic acid, gluconic acid, oxalic acid, boric acid and phosphonic acid.

16. A process according to claim 13, wherein the water-fixing materials comprise any of the following: aldehydes, aldehyde-separating materials chromium salts and zinc salts.

17. A process according to any of claims 1 to 3 and 6, wherein, in order to keep clean the internal or external surfaces of metals such as aluminium or iron, an acidly reacting film-forming composition is used which contains cellulose ether or a cation-active resin, as film-forming agent.

18. A process according to claim 17, wherein the action-active resin is phenol resin.

19. A process as claimed in claim 1 for keeping internal surfaces clean wherein either or both of the film-forming compositions comprises approximately 0.5 to approximately 15 % by weight of water-soluble cellulose ether approximately 0.5 to approximately 7 %by weight of amine salt of polymethylvinyl-ether maleic acid anhydride approximately 0.5 to approximately 5 % by weight of glycols approximately 0.05 to approximately 2 % by weight of surface-active agents approximately 0.5 to approximately 20 % by weight of isopropyl alcohol approximately 0.00 to approximately 5% by weight of disinfectant, and remainder water.

20. A process as claimed in claim 1 for keeping internal surfaces clean wherein either or both of the film-forming compositions comprises approximately 0.5 to approximately 10% by weight of water-soluble urea formaldehyde condensate and/or polyacrylates 0.5 to approximately 5% by weight of glycol 0.05 to approximately 2 % by weight of surface-active agents 0.5 to approximately 20% by weight of isopropylalcohol 0.00 to approximately 5 % by weight of disinfectant and remainder water.

21. A process as claimed in claim 1 for keeping external surfaces clean wherein either or both of the film-forming compositions comprises approximately 1 to approximately 10% by weight of cellulose ethers which are sparingly soluble to insoluble and/or capable of swelling in water, approximately 0.5 to approximately 10% by weight of polymethylvinyl ether maleic acid anhydride approximately 1 to approximately 20% by weight of formic acid approximately 1 to approximately 10% by weight of acidic phosphoric acid ester and/or halogenated acetic acid approximately 1 to approximately 10% by weight of glycols approximately 0.05 to approximately 5% by weight of surface-active agents approximately 0.05 to approximately 5% by weight of acetone approximately 0.5 to approximately 5% by weight of sulphite waste liquors, and remainder water.

22. A process as claimed in claim 1 for keeping external surfaces clean, which are exposed to contamination by oil and/or fat and dirt, wherein either or both of the film-forming compositions comprises approximately 1 to approximately 40% by weight of potassium and/or sodium silicates which are sparingly soluble to insoluble and/or capable of swelling in water or approximately 0.5 to approximately 10% by weight of polyacrylates and approximately 0.5 to approximately 15% by weight of complex-forming agents approximately 0.5 to approximately 10% by weight of sulphite waste liquors or oxylignins approximately 0.05 to approximately 15% by weight of surface-active agents approximately 0.00 to approximately 4% by weight of dyestuffs and remainder water.

23. A process according to claim 21 or 22, when used for cleaning the external surfaces of means of transportation.

24. A process for keeping internal or external surfaces clean as claimed in claim 1 substantially as herein described with reference to any of the Examples.