GB1570966A - Waterproofing compositions - Google Patents

Description

(54) WATERPROOFING COMPOSITION (71) We ,NL INDUSTRIES, INC., a Company organized under the laws of the State of New Jersey, United States of America, of 1221 Avenue of the Americas,New York, New York 10020, United States of America, 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: The present invention relates to coating compositions in particular to compositions for improving the resistance of masonry, concrete, mortar and similar materials and structures made therefrom to seepage of water.

Many waterproofing paints and coating compositions have been developed for waterproofing concrete and masonry walls such as cement and cinderblock structures used in foundations for homes. Typical paint formulations as are available on the market consist of a combination of vehicle and pigment and other solid materials. The vehicle portion of the paint may, for example, comprise vinyl toluene resins, chlorinated paraffin aliphatic solvents, such as mineral spirits and various additives in minute amounts. The so-called pigment portion of the paint will generally be portland cement and some amount of pigment such as titanium dioxide plus other extenders and fillers. The waterproofing characteristic of these prior art paint formulations is developed for the most part by the reaction between the cement contained in the paint and water as will be present in the block to be waterproofed.After the cement portion has been cured for some period of time, the porosity is significantly reduced and thus the water leakage through the cementitious composition is materially reduced. An undesirable characteristic of such paint formulations, however, is the fact that until the cement is actually cured or set up, the paint is quite porous, and seepage of water occurs through the paint surface. An average basement having a seven to eight foot ceiling is generally nine or more feet underground and, thus, considerable hydrostatic pressure is developed from surface water or other sources, such as underground streams. Such hydrostatic pressure is typically in the range of 4 to 6 Ibs per square inch (psi). The seepage of water through the treated surface is undesirable for a number of reasons.For example, if sufficient hydrostatic pressure is present the continued seepage of water may well wash away at least a portion of the waterproofing composition applied to the masonry surface. It will also affect the general appearance of the paint compositions, thus destroying the asthetic quality of the coating. In addition, salts as may be contained in the seepage water are quite likely to be deposited on the surface of the coating. Further the seepage moisture may cause damage to furniture and other housing articles as are normally present in basements. We have developed a coating composition that can effectively block the seepage of water through a masonry wall even under hydrostatic pressure.

The present invention accordingly provides a masonry coating composition having improved water-proofing characteristics comprising a non-aqueous vehicle portion and a pigment-extender portion including a hydraulic cement, and from 2 to 15 % by weight of the total composition of a smectite-type clay characterized by swelling in water and from 0.5 to 5% by weight of the total weight of the composition of a water-soluble polymer.

The waterproofing composition of the instant invention is typically prepared by incorporating a water soluble polymer and smectite type colloidal clay in waterproof paints as heretofore described. Both of these components have the characteristic of swelling on contact with water. Thus, they fill most of the pores and prevent water from passing through the film.

The clay employed according to the present invention is a colloidal clay of the smectite type as for example, hectorite, saponite montmorillonite and bentonite. Among clays generally, a special group of clay types exists, which are characterized by swelling behaviour in water. This group is in contrast to the clays used for thousands of years for ceramic purposes, in which swelling is a disadvantage since it leads to excessive shrinkage in the production of ceramic articles. This swelling group is characterized by a flat crystal habit in which the equilibrium distance between the individual flat crystallites is dependent upon the water content as well as other influences such as the electrolyte content of the water in contact with the clay.The term "Smectite" has been revived in recent years to embrace the so-called montmorillonite group of clays which includes such well known members as montmorillonite, saponite and hectorite. A discussion and further details on Smectites may be found in the book "Rock Forming Minerals", Volume 3, Sheet Silicates, by WA Deer et al, London 1962, pages 226-245. More recently these smectite clays have been produced synthetically and such synthetic products are also useful in this invention.

The water soluble polymer portion may be high molecular weight polyethylene oxide, such as that material sold by Union Carbide Corporation under the trade mark POLYOX.

Other polymeric materials which can be employed, although generally with a somewhat lesser degree of efficiency, are hydroxy ethyl cellulose (HEC), methylcellulose and hydroxy propyl methyl cellulose, the latter sold under the trademark METHOCEL by The Dow Chemical Company.

A particularly preferred combination of smectite clay and water soluble polymer is bentonite and polyethylene oxide.

In the preparation of a coating composition according to this invention, the smectite clay and the water soluble polymer are added to the other components in amounts as hereinafter described.

The smectite clay such as bentonite is added in amounts of from 2 to 15 percent by weight of the paint composition. Higher amounts of clay may result in absorption of part of the solvent system and thus cause thickening of the paint as may be stored in containers prior to application on the masonry surface.

If the polymer is used in amounts of less than 6 pounds per hundred gallons of paint (approximately 0.5% by weight) it tends to lose its effectiveness in the system. Use of more than about 5 weight percent of the polymer is not only expensive but the paint begins to get gummy, thus making application more difficult.A typical formulation according to the present invention will have the following composition: Weight Weight Component Percent Function Vehicle Portion Vinyl toluene - butadiene copolymer 6.10 Vehicle, binder Aliphatic hydrocarbon 28.15 Solvent Chlorinated paraffin 0.78 Plasticizer, part of vehicle Substituted triglyceride 1.56 Wetting agent Pigment-Extender Portion Titanium dioxide 1.87 White hiding pigment Portland cement 25.80 Upon hydration forms a water barrier Sand 15.64 Extender pigment Talc 7.04 Extender pigment Mica 7.04 Extender pigment Smectite clay 5.08 Swells on contact with water filling most pores and pre venting water from passing through film High molecular weight 0.94 Water soluble polymer that polyethylene oxide swells and deforms, blocks pores It should be recognised that excepting for the smectite clay and the high molecular weight polyethylene oxide the individual components are those generally used in waterproofing paint compositions, and they may vary in proportions employed within the skill of those knowledgeable in this field. The smectite clay and polymer are preferably added to the other ingredients so as to form a waterproofing paint composition as may be packaged in suitable containers directly. However, it is contemplated and within the scope of this invention to prepare a mixture of the clay and polymer and to use such a rnixture as an additive to those masonry paints as are currently being marketed.

The presence of the smectite clay and polymer in the paint composition will permit water to get into the paint film and thus react with and hydrate the cement; however the instant swelling characteristics of the clay and polymer when in contact with water prevents undesirable seepage of water through the paint film as applied to the masonry surface.

The PVC or Pigment Volume Concentration is always of consideration when preparing a paint composition. Generally it has been found that the best results are obtained if the PVC of the instant paints is maintained in the range of about 50-90. A PVC value in the range of 65-75 has been found particularly suitable for the waterproofing compositions of this invention. The PVC should be high enough to allow porosity so that the water can contact the polymer, clay and cement.

Example In order to show the benefit obtained by incorporating the combination of smectite clay and water soluble polymer to masonry paints, a series of three paint formulations was prepared. The first formulation (Sample A) was typical of the prior art paint compositions.

The second (Sample B) was modified to include the addition of smectite clay. The third (Sample C) illustrative of this invention contained both colloidal clay and a water soluble polymer. All three samples were prepared by techniques as usual to the industry, i.e. by mixing together the vehicle fractions and then blending in the pigment and filler materials with agitation until a satisfactory paint blend resulted. The paints so formed were then tested to determine their capability to provide protection to a masonry structure by preventing seepage of water therethrough after application of the paint to the surface of the masonry structure. Specifically three cinder blocks of substantially the same configuration size, weight, and porosity were coated on the outer surface at the same film thickness with each of the paints (Samples A, B and C).After permitting the paint film to dry the blocks were then placed in a test apparatus, the blocks forming an outside wall of the apparatus and the apparatus being designed to receive and hold water under pressure. The test apparatus was then filled with water and subjected to a pressure of 4 to 6 pounds per square inch (psi) for 4 hours. As previously mentioned this pressure corresponds to that hydrostatic pressure as would be present in the lower portion of a typical home basement due to surface water and the like. the painted surfaces were than observed to determine the water seepage through the surface of the blocks. The results are shown in the Table.

TABLE Sample A Sample B Sample C Composition Wt. % Wt. % Wt. % Vinyl Toluene - Butadiene Copolymer 6.10 6.10 6.10 Aliphatic hydrocarbon 28.15 28.15 28.15 Chlorinated paraffin 0.78 0.78 0.78 Substituted Triglyceride 1.56 1.56 1.56 Titanium Dioxide 1.87 1.87 1.87 Portland Cement 25.80 25.80 25.80 Talc 7.04 7.04 7.04 Mica 7.04 7.04 7.04 Sand 21.66 16.58 15.64 Bentonite --- 5.08 5.08 Polyethylene Oxide --- --- 0.94 Water Seepage - - - Substantial Less than No seepage Sample A observed but still not accept able The comparative results clearly show the superiority of the present invention. Further the results show that use of the combination of smectite clay and water soluble polymer to be better than the use of colloidal clay alone. This is probably due to the characteristic of the polymer to swell and fill even the most minute pores of the paint film when in contact with water.

WHAT WE CLAIM IS: 1. A masonry coating composition having improved water-proofing characteristics comprising a non-aqueous vehicle portion and a pigment-extender portion including a hydraulic cement, and from 2 to 15% by weight of the total composition of a smectite-type clay characterized by swelling in water and from 0.5 to 5% by weight of the total weight of the composition of a water-soluble polymer.

2. A coating composition as claimed in claim 1 wherein the smectite clay is bentonite, hectorite, montmorillonite or saponite.

3. A coating composition as claimed in either claim 1 or claim 2 wherein the polymer is polyethylene oxide, hydroxy propyl methylcellulose, hydroxy ethyl cellulose or methylcellulose.

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

Claims (6)

**WARNING** start of CLMS field may overlap end of DESC **. with agitation until a satisfactory paint blend resulted. The paints so formed were then tested to determine their capability to provide protection to a masonry structure by preventing seepage of water therethrough after application of the paint to the surface of the masonry structure. Specifically three cinder blocks of substantially the same configuration size, weight, and porosity were coated on the outer surface at the same film thickness with each of the paints (Samples A, B and C). After permitting the paint film to dry the blocks were then placed in a test apparatus, the blocks forming an outside wall of the apparatus and the apparatus being designed to receive and hold water under pressure.The test apparatus was then filled with water and subjected to a pressure of 4 to 6 pounds per square inch (psi) for 4 hours. As previously mentioned this pressure corresponds to that hydrostatic pressure as would be present in the lower portion of a typical home basement due to surface water and the like. the painted surfaces were than observed to determine the water seepage through the surface of the blocks. The results are shown in the Table. TABLE Sample A Sample B Sample C Composition Wt. % Wt. % Wt. % Vinyl Toluene - Butadiene Copolymer 6.10 6.10 6.10 Aliphatic hydrocarbon 28.15 28.15 28.15 Chlorinated paraffin 0.78 0.78 0.78 Substituted Triglyceride 1.56 1.56 1.56 Titanium Dioxide 1.87 1.87 1.87 Portland Cement 25.80 25.80 25.80 Talc 7.04 7.04 7.04 Mica 7.04 7.04 7.04 Sand 21.66 16.58 15.64 Bentonite --- 5.08 5.08 Polyethylene Oxide --- --- 0.94 Water Seepage - - - Substantial Less than No seepage Sample A observed but still not accept able The comparative results clearly show the superiority of the present invention. Further the results show that use of the combination of smectite clay and water soluble polymer to be better than the use of colloidal clay alone. This is probably due to the characteristic of the polymer to swell and fill even the most minute pores of the paint film when in contact with water. WHAT WE CLAIM IS:

1. A masonry coating composition having improved water-proofing characteristics comprising a non-aqueous vehicle portion and a pigment-extender portion including a hydraulic cement, and from 2 to 15% by weight of the total composition of a smectite-type clay characterized by swelling in water and from 0.5 to 5% by weight of the total weight of the composition of a water-soluble polymer.

2. A coating composition as claimed in claim 1 wherein the smectite clay is bentonite, hectorite, montmorillonite or saponite.

3. A coating composition as claimed in either claim 1 or claim 2 wherein the polymer is polyethylene oxide, hydroxy propyl methylcellulose, hydroxy ethyl cellulose or methylcellulose.

4. A coating composition as claimed in claim 1 wherein the smectite clay is bentonite and the polymer is polyethylene oxide.

5. A coating composition as claimed in any one of claims 1 to 4 having a pigment vehicle concentration of from 50 to 90.

6. A coating composition as claimed in any one of claims 1 to 5 and substantially as hereinbefore described.