Field of the invention
The present invention relates to a micro emulsion for use as a water repellant on various cementitious substrate. Background of the invention
The deterioration of concrete structures has been one of the social issues of concern in recent years, and due to this, there have been developed a variety of water repellents to prevent the infiltration of external water, which is a main cause of the deterioration of concrete. These presently developed water repellents include water repellant on various cementitious substrates,even in alkaline and acidic conditions and is neutral in nature. The solvent-base water repellents involve problems in that they are liable to ignite and that they have high toxicity and really have a detrimental influence on a working environment and natural environment There is therefore an increasing demand for water repellents having extraordinary efficacy on different substrates and which is thermodynamically stable.
Prior-art
JP-A-62-197369 teaches a water-repellent emulsion obtained by emulsifying alkylalkoxysilane as a water-repellent substance in water in the presence of a nonionic emulsifier as a dispersant.
U.S. Pat. No. 4,476,282 and U.S. Pat. No. 4,529,758 disclose an aqueous emulsion of an organic polysiloxane oil and a water-base dispersion of a silicon resin respectively.
Since, however, alkylalkoxysilane is highly hydrolyzable and requires a large amount of an emulsifier to be stable in water, there is a problem in that the water repellency decreases due to a large amount of the emulsifier which are incorporated to obtain an aqueous-dispersion water repellent having high dispersion stability.

Further, there is another problem in that the above aqueous emulsion of an organic
polysiloxane oil and the above water-base dispersion of a silicon resin are still poor m
water repellency and barrier properties against water absorption.
Object of the invention
It is an object of the present invention to provide a water-repellent emulsion composition
having improved water repellency and improved barrier properties against water
absorption, and a process for the production thereof
Summary of the invention
A micro emulsion for use as a water repellant on various cementitious substrate comprising a reaction mixture of solution A added to the solution B drop by drop over a period of 2 hours, wherein the solution A comprises surfactant mixed in de-ionised water by stirring in a homogeniser at a speed of 13500 rpm and mono carboxylic acid added to it maintainmg the pH between 7 and 7.5 and the solution B is made of silane, added with silicone oil dimethyl siloxane or any other siloxane. Statement of the invention
Accordmg to an embodiment of the invention a process for preparing micro emulsion for use as a water repellant on various cementitious substrate comprises the following steps,
a) Taking a clean and dry 100 litre stainless steel drum fixed with a homogeniser with a speed of 13,500 rpm,
b) Making a solution of 0.180 to 5.40 kg anionic, cationic and non-ionic surfactant into 10.5 to 55.6 kg of de-ionised water,
c) Adding a solution of 30 to 300 grams of mono carboxylic acid,
d) Adding into the reaction vessel the aqueous solution of acid, drop by drop for a period of 30 minutes to obtain a flexible plastic type ester maintaining the pH between 7 and 7.5,
e) Stirring the solution for 1 hour 30 minutes enabling the formation of polymeric type fibrous material which after further stirring goes back in the form of solution,
f) Making a solution B by adding 12.8 to 13.8 kg of silane in the de-ionised water,

g) Adding 6.08 to 20.08 kg silicone oil dimethyl siloxane or any other poly
siloxane and thoroughly mixing the solution, h) Adding the solution B into the solution A in the original reaction vessel drop-wise over a period of 2 hours, i) Agitating the reaction mixture for a period of 2 hours to maintain the pH 7 to
7.5, j) Adding 25-40 kg of de-ionized water and stirring for 1 hour to obtain a milky
white emulsion, k) Passing the milky white emulsion through a nozzle rotating circularly,
attached with a compressor pump and spray drying the liquid at ambient
temperature, 1) Allowing the liquid of the emulsion to age in a tightly closed container for 2
to 3 days to obtain the fmal product.
According to another embodiment of the invention a process for preparing micro emulsion for use as a water repellant on various cementitious substrate, wherein the surfactant is alkalamine, ethoxylates, sodium secondary, alkaline sulphonate and ethoxylated sorbitan fatty acid esters.
According to another embodiment of the invention a process for preparing micro emulsion for use as a water repellant on various cementitious substrate, wherein the most preferred surfactant is ehoxylates.
According to another embodiment of the invention a process for preparing micro emulsion for use as a water repellant on various cementitious substrate, wherein the said mono carboxylic acid is acidic acid.
According to another embodiment of the invention a process for preparing micro emulsion for use as a water repellant on various cementitious substrate, wherein the said silane is octyl tri ethoxy silane or Iso Butyle Tri Ethoxy Silane or any other silane.

According to another embodiment of the invention a process for preparing micro emulsion for use as a water repellant on various cementitious substrate, wherein in the preparation of micro emulsion nano-technology is used to achieve 2-4 nano-meter.
According to another embodiment of the invention a micro emulsion for use as a water repellant on various cementitious substrate comprising a reaction mixture of solution A added to the solution B drop by drop over a period of 2 hours, wherein the solution A comprises surfactant mixed in de-ionised water by stirring in a homogeniser at a speed of 13500 rpm and mono carboxylic acid added to it maintaining the pH between 7 and 7.5 and the solution B is made of silane,added with silicone oil dimethyl siloxane or any other siloxane.
According to another embodiment of the invention a micro emulsion for use as a water repellant on various cementitious substrate, wherein the surfactant is 0.180 to 5.40 kg.
According to another embodiment of the invention a micro emulsion for use as a water repellant on various cementitious substrate, wherein the de-ionised water is 10.5 to 55.6 kg.
According to another embodiment of the invention a micro emulsion for use as a water repellant on various cementitious substrate, wherein the mono carboxylic acid is 30 to 500 grams.
According to another embodiment of the invention a micro emulsion for use as a water repellant on various cementitious substrate, wherein the silane is 12.8 to 48.8 kg.
According to another embodiment of the invention a micro emulsion for use as a water repellant on various cementitious substrate, wherein the silicone oil dimethyl siloxane is 6.08 to 48.8 kg.

According to another embodiment of the invention the said emulsion, whenever used as a water repellant coating by spraying the solution of the emulsion with distilled water on the substrate by means of a hand pump.
Detailed deacription of the invention
Protekta Micro Emulsion is a novel Ethoxylate-Acrylate Silane Siloxane emulsion produced by the applicant and is effective as a water repellant on various cementitious substrates, even in alkaline and acidic conditions, and is neutral in nature. It is thermodynamically stable and its efficacy on different substrates is extraordinary.
With labour costs going up and aesthetics playing a significant role, the multi-million dollar building industry is today looking at waterproofing as a mechanism to maintain and preserve the look of new buildings. Protekta Micro Emulsion would be a particular boon for the exteriors of buildings.
Various methods to make silicone emulsions as masonry water repellents have been reported in the literature. Most of the other emulsions available in the market are based on silane-siloxane but our product is produced by using esters of ethoxylate surfactants and thus becomes a novel micro emulsion.
Apart from consideration of the physical emulsion stability and impregnation performance, particular attention must also be paid to two important factors: hydrolysis of silicone components in the emulsion and wetting effect induced by the surfactant. The wetting effect due to the emulsion is very difficult to avoid, as the surfactant is the major part in making a physically stable emulsion. This wetting effect has not been seriously considered by previous workers who developed silicone emulsions. Therefore, wetting effects are able to be observed in the substrates treated with many masonry water repellents which are commercial silicone emulsions.

The design of the surfactant is probably the most important part of the silane-siloxane emulsion. Applicant studied a large number of surfactants and found a few belonging to the ethoxylate alkylamine exthoxylate series as most preferred. In our process the Micro Emulsion is thermodynamically stable and can be stored and used. Another important factor is that our Micro Emulsion is not based only on silane-siioxane but first an alkyl ester is produced and therefore what we get is a specially substituted acrylic silane siloxane, poly siloxane and surfactant. In the preparation of Micro Emulsion, we have to take care to arrest the evaporation of silane and the higher depth of impregnation of the smaller particle size of the product. For this we have used very successfully nanotechology. Through the usage of nanotechology we were able to achieve 2-4 nanometer.
Protekta Micro Emulsion is water-based and can be sprayed or brushed on external brick walls, stones, exteriors or on any other concrete surfaces. The nano size of this emulsion is of great significance. It penetrates and creates a hydrophobic zone in capillaries and pores, which does not allow water to enter but allows vapour to go out. This is a very strong repellent and the repellency can be noticed after 2 to 7 days. It gets permanently bonded to the substrate and cannot be washed out.
Many waterproofing products are available in the market but importance should be given to the essential requirements of waterproofing materials, namely:
Resistance to water absorption
Prevention of entry of water-soluble salts, particularly chloride salts
Penetration of waterproofing treatment to a measurable depth
Non-staining of treated surface areas
Long-term stability in an alkaline environment
Low risk to health and environment
UV stability (20+ years)

The only way to achieve these results is to have a very effective waterproofing and it may not be out of place to mention that it is very important to select the right type of waterproofing product.
Environmental Impact on Structures
The ingress of damaging materials to structures may occur in the gaseous state or in the liquid state. This makes the design of a durable protection system the more difificult. Gaseous damaging materials include CO2, SO2, SO3 and nitrogen oxides. On entering the building material as a gas they may dissolve in water present in pores and capillaries forming a dilute acid solution.
As one begins to understand the mechanics of water infiltration one begins to understand the importance of keeping a building watertight. Water infiltration causes major problems to a structure. Water damages a building first cosmetically then structurally. What is important to realize is that by the time a stain shows up on the interior of your building, most likely irreversible damage has been caused to the exterior.
To prevent all possible water intrusion causes, a building must be enveloped from top to bottom with waterproof materials. These waterproof systems must then interact integrally to prevent water infiltration. Should any one of these systems fail or not act integrally with all other envelope systems, leakage will occur.
Water soaked roof insulation will never dry out. Trapped moisture in insulation can also decay a roof deck and will cause roofs to fail prematurely. Water entering walls will rust steel relieving angles and carrymg beams, which support the structure. Moisture penetrating reinforced concrete structures carry chloride ions, which will rust reinforcing bars causing them to expand in size resulting in spalling concrete.
Corrosion is a major problem for most concrete structures, occurring in the steel bars used to reinforce the concrete. There is no controversy about the fact that we want safer

and durable buildings and we have to guard the reinforcement from cancer. In fact, the expense incurred in North America as a result of corrosion-induced repair runs into billions of dollars, without taking into consideration the environmental toll of repeated construction and repair. Corrosion inhibitors are one of the most cost effective solutions to this problem, but little independent information is available on their effectiveness in actual use.
Generally, steel is chemically passive in concrete because of concrete's alkalinity. On the other hand, steel is not immune to corrosion. That is, the rate of corrosion can be so low that normally we neglect it for all practical purposes. But if the pollutants entering into the slab reduce the pH from 14 to, say, 8 corrosion starts. The passivity around the reinforcement is its only protection. The corrosion process requires water, oxygen from air, and a catalyst such as salt. Steel will not corrode in dry reinforced concrete even if salt is present. Nor will it in wet concrete even in the presence of chloride ions which are in salt solutions, if oxygen is essentially unavailable, for instance, at great depths under the ocean surface.
Deterioration of concrete occurs through a number of mechanisms. These include
• Corrosion of reinforcement due to
- Carbonation
- Chloride Ion
- Dissolved gases like S02, N02, C02, etc.

• Sulphate attack on concrete
• Efflorescence
• Alkali Aggregate Reaction
• Shrinkage
Toxic gases and environmental pollutants such as these enter into the building along with water, which finds ingress points. Concrete is supposed to be watertight but it is not so.

It is porous, develops cracks, honeycombs, voids and so many other entries through coping, or through other parts of the building.
It is possible to impregnate concrete with water repellent to protect against water penetration by capillary action. As shown in Figure 1, the major difference between impregnation and surface coating is that unpregnation only allows the impregnate to penetrate into the concrete to line the capillary wall surface to form a water repellent impregnated zone, whilst surface coating completely seals the capillaries by forming a thick film on the surface. Impregnation and lining of the capillaries can significantly reduce the water absorption by the masonry through capillary depression.
The invention will be described with reference to the accompanying drawings wherein
Figure 1 shows the Diagrams of impregnation and coating of masonry: (A) unpregnated
masonry surface with water repellent lined on capillary surfaces, and (B) coated masonry
surface with sealed capillaries.
Figure 2 shows Effects of various additives in the oil phase of OMMS emulsions on the
depth of impregnation (Emulsion contained 50% oil phase and 2.3% Teric 16M2-7 and
was diluted to 5% before impregnation)
Figure 3 shows Relationship between interfacial tension at the oil/water interface and
acid addition to the alkylamine ethoxylate surfactant. (The dotted line is extrapolated as
the surfactant is insoluble in aqueous phase in that range)
Figure 4. shows Water absorption of: (A) Cement mortar, (B) Indian fired bricks, and
(C) Mud bricks treated with ME, PMS and solvent-based siloxane (OMMS-Sn in Isopar
G) impregnant
Products marketed as penetrants or sealants or impregnants including silicates, siliconates, silanes, siloxanes, etc. These penetrant sealants can be further divided into hydrophobic products or water-repellants and pore blockers. Silanes, siloxanes and siliconates fall within the hydrophobic category. They lower the substrate's surface tension, thereby imparting water-repellency.

Numerous studies have been conducted on these impregnants and the effectiveness and toxicity of these products have been evaluated. Silanes and siloxanes can be either solvent- or water-based but if solvent-based, they are not only expensive but also toxic and pollute the environment. Silanes and siloxanes both release volatile organic compounds (VOCs). In the case of solvent-based, VOCs are released both due to the solvent evaporation and when the alcoxy groups hydrolyze in the substrate. Due to faster evaporation of silanes they are volatile and their application may not be recommended because the products can evaporate very quickly without penetrating the concrete surface.
Performance of the impregnant can be measured by the hydrophobicity it imparts to the substrate and its ability to inhibit acids like chlorides, or water or carbon dioxide. The depth of penetration is another important factor and it is important that one uses non¬toxic, non-hazardous and effective products. In the recent past it has been found that Micro Emulsion and Silane Cream are not only effective but give very good penetration and are neutral in nature. An emulsion is defined according to Becher as a heterogeneous system, consisting of at least one immiscible liquid intimately dispersed in another in the form of droplets, whose diameter, in general, exceeds 0.1 \im}^ Such systems possess a minimal stability, which may be increased by such additives as surface-active agents, finely divided solids, and other materials.
Most building materials are very porous, wetting easily and absorbing water through the pores. They have surface hydroxyl groups that attract water because of their similarity with the structure of water and their hydrophilic nature. The size of the water molecule is 0.18 T^m (nanometer 10'' meter i.e. 0.00018 microns) while the size of the pores in most building materials ranges from 5 to 200 Tim. The size of most pollutants like acids, chlorides and sulphates would range between 1 and 2 T^m. Even with dense concrete and stones the pore size is much larger than water allowing easy entry with the hydrophilic nature of the building material.

As we have said earlier, an emission is a thermodynamically unstable system and there is a tendency for the interfacial energy between the oil and water phases to reduce the interface, causing the droplets to flow together resulting in droplet coalescence and eventually a breaking of the emulsion. Consequently in order to obtain a stable oil/water emulsion, external energy (such as shear mixing or other homogenization mixing) must be provided to the oil/water system to break the oil phase into small oil droplets. In addition, surface active materials such as surfactants have to be added to the emulsifying system to either reduce the interfacial energy between oil and water phases to achieve the smallest droplets, or to form a rigid barrier in the oil/water interface. This slows down the coalescence of the emulsion droplets, or imparts an electric charge to the interface, resulting in the formation of an electric double layer that lessens the frequency and effectiveness of close droplet approach and contact leading to droplet growth.
The general procedure adopted by us is to use surfactants that behave both as cationic and anionic since most of the surfactants belong to ethoxylate series and they were taken in water and acidified imder condition that after few hours it becomes ester. The ester was stirred with high-speed homogenizer.
This may be explained as the result of reduced viscosity of the oil phase in the emulsion. A silicone emulsion is believed to break after application to the concrete substrate surface'^ leaving the silicone oil on the substrate surface to further penetrate into the capillaries. Particularly, if the emulsion is stabilized with acidified alkyl amine ethoxylate surfactant, the emulsion is assumed to rapidly break after application because the surfactant will be abstracted from the oil/water interface by adsorption onto the negatively charged concrete surface according to Wates and James.
Another factor which may affect the depth of impregnation of the silicone emulsion is the so-called aquaplane effect. This effect was termed by Roth.*'* Roth found that octyl/methyl methoxysilane dissolved in hydrocarbon solvent can impart a higher depth of impregnation to the substrate if the substrate is pre-wetted with water. This effect is assumed to be due to a sliding or aquaplaning of the organic phase along a wet capillary

wall of the substrate. In the case of impregnating substrates with emulsion, the same aquaplane effect may apply. The emulsion may break into the organic and water after application to the substrate.'^'^^ The water may then wet the substrate capillaries first with subsequent penetration of the organic phase. From the test results shown in Fig. 2, the effect of increased depth of impregnation with the addition of particular organic solvents may also be attributed to the aquaplane effect. Addition of the silanes into the siloxane may be regarded as adding a solvent and therefore a higher depth of impregnation is then observed because silanes also have low viscosity.
It is important to maintain the pH of the surfactant between 7 and 7.5. The particle size of the emulsion decreases sharply with acid addition and then slowly decreases to a minimum at a HAc/16M2 ratio of 0.1/1. The particle size then increases slightly with the further increase in acid addition. In a comparison with interfacial tension change shown in Figure 3„ the result of the particle size change is consistent with that of interfacial tension change. In addition, the particle size distribution is also affected by the acid addition to the surfactant. After careful study of beading and water-absorption it was foimd that 4-6% emulsion in proper solvent, preferably food grade de-ionized water, gives excellent beading and penetration of up to 5 mm, depending on the substrate.
Experiments: Example -1
Take a clean and dry 100 litre SS. drum fixed with homogeniser with a speed of 13,500 rpm.
Make a Solution - A, by taking 10.5 to 55.6 kg of de-ionised water. Add 0.180 to 5.40 kg of anionic, cationic, non-ionic surfactant type alkalamine, ethoxylates,, sodium secondary, alkaline sulphonate, ethoxylated sorbitan fatty acid esters, preferably ethoxylates. Stir for 15 minutes.
Add a solution of 30 to 300 gms of mono carboxylic acid, preferably acidic acid.

This aqueous solution of acid was added drop by drop into the reaction vessel over a period of 30 minutes. As the acid content increases and the pH changes, a flexible plastic type ester is formed. It is important that the final pH should be between 7 and 7.5.
This solution is further stirred for 1 54 hours and one would notice some polymeric type fibrous material which after stirring starts going back into the solution.
In a separate vessel make solution -B by taking 12.8 - 38.8 kg of octyl tri ethoxy silane or Iso Butyle Tri Ethoxy Silane or any other silane. Add 6.08 - 28.08 kg silicone oil dimethyl siloxane or any other poly siloxane is added and the solution is thoroughly mixed.
This Solution B is added into the origmal solution reaction vessel drop-wise over a period of 2 hours.
The reaction mixture is now left for vigorous agitation for a period of 1 hour. During the stirring period the pH is checked and maintained at 7 to 7.5.
At the end of the stirring 25 - 40 kg de-ionized water is added and stirred for 1 hour.
The above milky white emulsion which is neutral at pH 7 is passed through a nozzle of 0.02 mm continuously circulated through the system. The system is run by compressor pump and is akin to spray dryer except that here liquid is passed at ambient temperature.
Leave the emulsion m a tightly closed can and after ageing of 2 to 3 days, it can be dispatched.
Make 5% solution of the above emulsion in distilled water and sprayed on the substrate by using low pressure hand pump. It gives excellent results: Reduction of water absorption by the substrate, by 90-95%.

Example - 2
Take a clean and dry 100 litre SS. drum fixed with homogeniser with a speed of 13,500 rpm.
Make a Solution - A by taking 12.5 to 42.6 kg of de-ionised water. Add 0.340 to 3.40 kg of anionic, cationic, non-ionic surfactant type alkalamine, ethoxylates,, sodium secondary, alkalme sulphonate, ethoxylated sorbitan fatty acid esters, preferably ethoxylates. Stir for 15 minutes.
Add a solution of 50 to 500 gms of mono carboxylic acid, preferably acetic acid. This aqueous solution of acid was added drop by drop into the reaction vessel over a period of 30 minutes. As the acid content increases and the pH changes, a flexible plastic type ester is formed. It is important that the final pH should be between 7 and 7,5.
This solution is further stirred for 114 hours and one would notice some polymeric type fibrous material which after stirring starts going back mto the solution.
In a separate vessel make solution - B by taking 18.8 - 48.8 kg of n-propyl tri ethoxy silane or any other silane. Add 10.6 - 48.88 kg silicone oil (dimethyl siloxane) or any other polysiloxane is added and the solution is thoroughly mixed.
This Solution B is added into the original solution reaction vessel drop-wise over a period of 2 hours.
The reaction mixture is now left for vigorous agitation for a period of 1 hour. During the stirring period the pH is checked and made 7 to 7.5.
At the end of the stirring 10 - 50 kg de-ionized water is added and stirred for 1 hour.

The above milky white emulsion which is neutral at pH 7 is passed through a nozzle of 0.02 mm continuously circulated through the system. The system is run by compressor pump and is akin to spray dryer except that here liquid is passed at ambient temperature.
Leave the emulsion in a tightly closed can and after ageing of 4 to 6 days, it can be dispatched.
Make 10% solution of the above emulsion in distilled water and sprayed on the substrate by using low pressure hand pump. It gives excellent results: Reduction of water absorption by the substrate, by 90-95%.
Beading effect: The beading efTect of various substrates treated with Micro Emulsion / Potassium Methyl Siliconate (ME / PMS) impregnant is shown in Table 1. The beading effect of the substrates treated with 5% ME solution is the same as those treated with 5% solvent-based siloxane impregnant. In addition, the beading effect of the substrates shows no difference between the substrates treated with ME and the ones with Potassium Methyl Siliconate (PMS) in non-alkaline substrates but ME shows better beading effect than PMS in cement mortar substrates.


Water absorption: Water absorption tests were conducted for 24 weeks (168 days) in order to examine the long-term water repellent performance of ME impregnant. Water absorption of cement mortar substrates is plotted in Figure 4(A). The test results indicate that the water absorption value of the substrate treated with 5% ME is equivalent to that of 5% solvent-based siloxane treated substrate. However, substrate treated with 2% PMS failed the water absorption test within a few days of the test. The test results imply that ME impregnant is satisfactory to render alkaline substrates water repellent while PMS is not suitable for alkalme substrates.
Figure 4(B) and 4(C) show the water absorption test results of Indian fired bricks and mud bricks respectively, treated with various impregnants. The results show that 5% ME can significantly reduce water absorption values of both substrates. It was found that the water repellent effect of ME impregnant in terms of water absorption is similar to that of PMS impregnant. Therefore, it may not be necessary to use ME impregnant to treat neutral substrates such as fired bricks and mud bricks. It was also observed that both ME and PMS impart less water repellency to the neutral substrates than that of solvent-based siloxane impregnant particularly to the mud bricks. Therefore, siliconate impregnants are less effective in rendering substrates such as mud bricks water repellent.
USES
• Excellent product for exteriors or expensive tiles/stones/marbles etc.
• Reduces water absorption by about 95%.
• Gets permanently bonded to substrate and cannot be washed out.
• Does not leave an oily residue on the substrate
• Easy to use.
• Water-based, non-hazardous, stable at high pH
• Non-flammable, non-toxic and non-corrosive
• Cost effective
• UV & alkali stable and durable emulsion

TECHNICAL DATA
Appearance : Milky white liquid
Specific gravity : 0.95
PH value : 6.5-7
Solubility in water : Miscible
Flash Point : > 100°

CONCLUSION
Protekta Micro Emulsion is a water based thermodynamically stable emulsion, a solvent-free aqueous silicone ester emulsion. It is designed to be used for reducing water absorption capacity of building materials and renders the substrate water repellent. This water repellent zone reduces not only the absorption of water but also efflorescence and other water borne staining materials.
Protekta Micro Emulsion is water based and can be sprayed or brushed on external brick walls, exteriors or on any concrete surfaces. It penetrates 4-6 mm and creates a hydrophobic zone in capillaries and pores which does not allow water to enter but allows vapour to go out. This is a very strong repellent and the repellency can be noticed after 24 hours.
The product is designed to penetrate into the capillaries of cement, concrete and other masonry surfaces including natural stone, marble, limestone, clay bricks, terracotta tiles, etc.

References:
1. DePasquale, R.J. and Wilson, M.E., US Patent, 4 648 904,1987
2. Suzuki, T., US Patent, 5 226 954,1993
3. Koemer, G., Nickel, F., Rott, H. and Schmidt, G., US Patent, 4 476 282,1984
4. Grape, W., Schlak, O., Montigny, A.D. and Kober, H., US Patent, 4 940 743,1990
5. Gobel, T., Michel, R., Alff, H. and Karl, J., Gennany Patent, 41 22 263,1993
6. Schamberg, E., Koemer, G., Fritsch, H., Grasse, M. and Sucker, R., US Patent, 5 091 002,
1992
7. Raleigh, W.J., US Patent, 4 175 159,1979
8. Heaton, T.F., US Patent, 5 037 873,1991
9. Kaijou, A., European Patent, 550 915,1992
10. Adamson, A.W., 'Physical Chemistry of Surfaces', 3'^ Edn, pp. 9-10 (John Wiley & Sons,
New York 1976)
11. Becher, P., 'Emulsions: Theory and Practice', 2"** Edn, (Robert E. Krieger Publishing
Company, Huntington 1977)
12. Mayer, H., KOnig-Lumer, I., Kolleritsch, C, Wochinger, C. and Dickmann, C,
Bautenschutz
+ Bamanierung, 1991,14(3), 27
13. Wates, J.M. and James, A.D., 'First World Congress on Emulsions', 1-40 (89) (Paris,
France
1993)
14. Roth, M., Bautenschutz + Bausanierung, 1987,10(1), 9

We claim;
1. A process for preparing micro emulsion for use as a water repellant on various
cementitious substrate comprising the following steps, m) Taking a clean and dry 100 litre stainless steel drum fixed with a homogeniser
with a speed of 13,500 rpm, n) Making a solution of 0.180 to 5.40 kg anionic, cationic and non-ionic
surfactant into 10.5 to 55.6 kg of de-ionised water, o) Adding a solution of 30 to 300 grams of mono carboxylic acid, p) Adding into the reaction vessel the aqueous solution of acid, drop by drop for
a period of 30 minutes to obtain a flexible plastic type ester maintaining the
pH between 7 and 7.5, q) Stirring the solution for 1 hour 30 minutes enabling the formation of
polymeric type fibrous material which after further stirring goes back in the
form of solution, r) Making a solution B by adding 12.8 to 13.8 kg of silane in the de-ionised
water, s) Adding 6.08 to 20.08 kg silicone oil dimethyl siloxane or any other poly
siloxane and thoroughly mixing the solution, t) Adding the solution B into the solution A in the original reaction vessel drop-wise over a period of 2 hours, u) Agitating the reaction mixture for a period of 2 hours to maintain the pH 7 to
7.5, v) Adding 25-40 kg of de-ionized water and stirring for 1 hour to obtain a milky
white emulsion, w) Passing the milky white emulsion through a nozzle rotating circularly,
attached with a compressor pump and spray drying the liquid at ambient
temperature, x) Allowing the liquid of the emulsion to age in a tightly closed container for 2
to 3 days to obtain the final product.

2. A process for preparing micro emulsion for use as a water repellant on
various cementitious substrate, wherein the surfactant is alkalamine,
ethoxylates, sodium secondary, alkaline sulphonate and ethoxylated sorbitan fatty acid esters.
3. A process for preparing micro emulsion for use as a water repellant on various cementitious substrate, wherein the most preferred surfactant is ehoxylates.
4. A process for preparing micro emulsion for use as a water repellant on various cementitious substrate, wherein the said mono carboxylic acid is acidic acid.
5. A process for preparing micro emulsion for use as a water repellant on various cementitious substrate, wherein the said silane is octyl tri ethoxy silane or Iso Butyle Tri Ethoxy Silane or any other silane.
6. A process for preparing micro emulsion for use as a water repellant on various cementitious substrate, wherein in the preparation of micro emulsion nano-technology is used to achieve 2-4 nano-meter.
7. A micro emulsion for use as a water repellant on various cementitious substrate comprising a reaction mixture of solution A added to the solution B drop by drop over a period of 2 hours, wherein the solution A comprises surfactant mixed in de-ionised water by stirring in a homogeniser at a speed of 13500 rpm and mono carboxylic acid added to it maintaining the pH between 7 and 7.5 and the solution B is made of silane,added with silicone oil dimethyl siloxane or any other siloxane.
8. A micro emulsion for use as a water repellant on various cementitious substrate, wherein the surfactant is 0.180 to 5.40 kg.

9. A micro emulsion for use as a water repeliant on various cementitious
substrate, wherein the de-ionised water is 10.5 to 55.6 kg.
10. A micro emulsion for use as a water repeliant on various cementitious
substrate, wherein the mono carboxylic acid is 30 to 500 grams.
11. A micro emulsion for use as a water repeliant on various cementitious
substrate, wherein the silane is 12.8 to 48.8 kg.
12. A micro emulsion for use as a water repeliant on various cementitious substrate, wherein the silicone oil dimethyl siloxane is 6.08 to 48.8 kg.
13. The emulsion as claimed in any of the preceding claims, whenever used as a water repeliant coating by spraying the solution of the emulsion with distilled water on the substrate by means of a hand pump.
14. A process for preparing micro emulsion for use as a water repeliant on various cementitious substrate substantially as hereinbefore described with reference to the accompanying examples.
15. A micro emulsion for use as a water repeliant on various cementitious
substrate substantially as hereinbefore described with reference to the
accompanying examples.