NO770948L - IMPREGNANT. - Google Patents

Description

I mp re gn e ring mi d the 1

The present application relates to a unique coating composition which effectively blocks the penetration of water through brick walls due to hydrostatic pressure. The coating composition is prepared by incorporating a water-insoluble polymer and a colloidal clay of smectic structure together with conventional ingredients commonly present in a wall paint or coating. The polymer and clay swell immediately on contact with water and thus block all pores in the coating and prevent water from penetrating through it.

A number of waterproof paints and coatings have been developed to impregnate concrete and brick walls, such as cement-

and lightweight concrete block structures, which are used as foundations for residential buildings. Typical paint formulations that are marketed consist of a combination of a carrier and pigment as well as other solids. The bearing axle in the paint can e.g. include vinyl toluene resins, chlorinated aliphatic paraffin solvents such as e.g. white spirit, and various additives in small quantities. The so-called pigment part in the paint is generally portland cement and a smaller part pigment, such as e.g. titanium dioxide, plus other extenders and filler materials. The impregnation properties of these previously known paint formulations are developed for the most part by reaction between the cement, which is contained in the paint, and water which will be present in the block or wall, which is to be impregnated. After the cement part has hardened for some time, the porosity is significantly reduced and thus the water penetration through the cementitious compound is significantly reduced

reduced. However, an undesirable characteristic of such paint formulations is that until the cement is fully hardened or used, the paint is relatively porous and penetration of water occurs through the paint surface.

An average basement with a ceiling height of 2 - 2.5 m generally extends 2.75 m or more below the ground and is thus exposed to significant hydrostatic pressure from surface water and other sources, such as e.g. groundwater. Such a hydrostatic pressure will be of the order of magnitude 0.2Q - 0.42 kg/cm. Penetration of water through the treated surface is undesirable for a number of reasons. E.g. if sufficient hydrostatic pressure is present, the continuous water penetration will wash away, at least a part, of the impregnating compound applied to the wall surface. It will also affect the general appearance of the paint and thereby spoil the aesthetic quality of the coating.

In addition, there is a high probability that salts that may be contained in the water, which penetrate through, are deposited on the surface of the coating. In addition, the penetrating moisture can cause damage to furniture and other household items that are normally found in the basement.

A unique coating compound has now been developed which will effectively block the penetration of water through masonry walls under hydrostatic pressure.

The present application includes a coating composition for concrete and masonry walls and is characterized by a wood carrier part and a pigment-extender part and contains smectitizers and a water-soluble polymer. The application also includes an additive for wall paint compositions consisting of a mixture of smectitizers and a water-soluble polymer as a means of improving the waterproofing of the wall paints.

As described later in more detail, the impregnating agent according to the present invention is produced by incorporating a water-insoluble polymer and a smectitizer in waterproof paints as described earlier. Both of these additives have the unique property that they swell on contact with water. Thereby, they fill most of the pores in the paint film and prevent water from penetrating.

The clay used according to the present invention is a colloidal clay with a smectic structure such as e.g. hectorite^ saponite, montmorillonite or bentonite. Among clays in general, there is a special group of clays that are characterized by swelling in water. This group differs from the clays that have been used for thousands of years for ceramic purposes, where the swelling is a disadvantage because it leads to excessive shrinkage in the production of ceramic articles. This swelling group is characterized by the flat crystal structure where the equilibrium distance between the individual flat crystallites depends on the water content as well as other influencing properties, such as e.g. the electrolyte content of the water in contact with the clay. The term "smectite" has been used in recent years to include the so-called montmorillonite group

of clays including such known clays as montmorillonite, saponite and hectorite. A discussion and further details as smectite can be found in the book "Rock Forming Minerals"; volume 3»Sheet Silicates, by W.A. Deer et al, London 1962, pages 226 - 245• In the later tdd, these smectitizers are produced synthetically and such synthetic products are also usable according to the present invention.

The water-insoluble polymer part can be a polyethylene oxide with a high molecular weight, such as e.g. products sold by Union Carbide Corporation under the trade name POLYOX. Other polymeric materials that can be used, albeit generally with a lower degree of effectiveness, are hydroxyethyl cellulose (HEC), methyl cellulose and hydroxypropyl methyl cellulose. The latter is sold under the trade name METHOCEL by The Dow Chemical Company.

When preparing the coating compound according to

In the present invention, the smectitizer and the water-soluble polymer are added to the other components in amounts as described below. It is typical to add the smectitizer, such as e.g. bentonite, in amounts from approx. 2 to approx. 15 tbsp

of the paint compound. Large amounts of clay may result in absorption of part of the dissolution system and thereby cause thickening of the paint during storage in containers for application to the masonry surface.

If the polymer is used in amounts less than 720 g/lOO" 1 paint (about 0.5 tbsp) it seems to lose its effectiveness in the system. Using more than about 5 tbsp of the polymer is not only expensive, but the paint also starts to become rubbery which makes application more difficult. A typical formulation according to the present invention will have the following composition:

It should be noted that, apart from the smectitizer and the high-molecular polyethylene oxide, the individual components are those that are usually used in waterproof paint compounds, and they can be varied in the conditions used, as known to those skilled in the art. The smectitizer and the polymer are preferably added to the other ingredients to form a waterproof paint compound that can be filled directly into suitable containers. However, this invention also includes making

a mixture of clay and polymer and use such a mixture as an additive to the wall paints that are marketed at any time, as a means of making them waterproof.

The presence of the smectitizer and polymer in the paint compound will allow water to penetrate the paint film and thus react with and hydrate the cement. However, the instant swelling ability of the clay and polymer, when they come into contact with water, will prevent unwanted penetration of water through the paint film applied to the wall.

The pigment volume concentration (PVC) must always be taken into account when producing paints. It has generally been found that the best result is achieved if the PVC of the present paint is kept within the range of approx. 50 - 90. A PVC value i

the range 60-75 has been found particularly suitable for impregnating agents according to the present invention. The pigment volume concentration must be high enough to provide porosity so that water can come into contact with the polymer, clay and cement.

Example

To demonstrate the benefits achieved by incorporating the combination of smectitizers and water-soluble polymer into masonry paints, a series of 3 paint formulations was produced. The first formulation (sample A) was typical of previously known paints. The second (sample B) was modified and additionally contained smectitizers. The third (sample C) which is illustrative of the present invention contained both colloidal clay and a water-insoluble polymer. All 3

prbvér was produced by techniques that are commonly used in industry, i.e.* by mixing together the carrier part and then

mix in the pigment and filler materials while stirring until a satisfactory paint mixture is obtained. The paints thus prepared were then tested to determine their ability to provide protection for a masonry structure by preventing the penetration of water therethrough after application of the paint to the surface of the masonry structure. More specifically, 3 lightweight concrete blocks of practically the same shape, size, weight and porosity were coated on an outer surface with each of the three paints (samples A, B and C) with the same film thickness. After the paint had had time to dry, the blocks were placed in the test apparatus where the blocks formed an outer wall in the apparatus and where the apparatus was designed to receive and hold water under pressure. The test apparatus was then filled with water and subjected to a pressure of 0.28 to 0.1+2 kg/cm for 2+ hours. As previously mentioned, this corresponds to pressure

the hydrostatic pressure you will get in the lower part of a typical residential basement due to surface water and the like. The painted surfaces were then measured to determine the water penetration through the surface of the blocks. The result is shown in the table.

The comparable results clearly demonstrate the superiority of the present invention. Furthermore, the result1 shows that the use of a combination of smectitizers and water-soluble polymer is better than the use of colloidal clay alone. This is probably caused by the polymer's ability to swell and fill even the smallest pores in the paint film when it comes into contact with water.

Claims (1)

1. A mortar composition with improved impregnation properties characterized by a carrier part and a pigment extender part and containing smectitizers and a water-soluble polymer. 2. Paint composition according to claim 1, characterized in that the smectitizer is bentonite, hectorite, montmorillonite or saponite. 3* Paint composition according to claim 1 or claim 2, characterized in that the polymer is polyethylene oxide, hydroxypropylmethylcellulose, hydroxyethylcellulose. or methylcellulose. k. Paint composition according to claims 1-3, characterized in that the smectitizer is bentonite and the polymer is polyethylene oxide. 5. Paint composition according to claim 1-1+" characterized in that the smectitizer is present in 2 - 15 by weight of the total paint composition. 6. Paint composition according to claims 1-5" characterized in that the polymer is present in 0.5 - 5 wt? of the total paint composition. 7o An additive for improving the waterproofing of masonry paint compositions characterized by a mixture of smectitizers and a water-soluble polymer. 8. An additive to improve water tightness according to claim 7" characterized by a mixture of bentonite and polyethylene oxide.