TECHNICAL FIELD

Present invention relates to rheological additives for solutions or emulsions. This invention particularly relates to sepiolite based anti-settling additives.

As it is known in the art, water borne solutions or emulsions such as water borne painting or coating compositions comprise pigments and other fine industrial mineral powders such as calcite, barite, bentonite, kaolen and so on, which tend to settle especially during prolonged storage periods. For this reason there is always a need for some pigment suspension or anti-settling additives for use in said painting and coating compositions to prevent settling and sedimentation. Such additives provide rheological properties to compositions, in other words, the additives keep elements of the compositions, to which they are added, in floated, suspended and dispersed position for long period of times.

Accordingly, some rheological additives are used for above explained purpose such as clay-based materials or relevant chemical agents. Clay-based additives are relatively inexpensive but suffer from ineffectiveness in providing rheological properties to the solutions or emulsions compared to chemical agents. On the other hand, chemical agents are more expensive and not environment friendly. Related to this, in the light of recent developments, such chemical additives may not be allowed in the future as a consequence environmental concerns.

Bentonite, hectorite, attpulgite or sepiolite, which are in powder form, can be used as clay-based additives. The sepiolite clays, however, provide excellent anti-sag capabilities to the solutions or emulsions compared to other above mentioned clay- based materials. Furthermore, conventional thixatropes such as bentonites and other common organo clays usually drastically increase product viscosity. Related to this, the sepiolite clays have been used in many solutions or emulsions including anti-sag coating for concrete, water soluble paint coatings, paints for high water resistance, synthetic resin emulsion coatings, water base paints, water-soluble paint compositions, water or solvent based coatings and so on to prevent settling. For instance, EP 0170299 B1 discloses a rheological grade sepiolite and processes for its manufacture. However, even though speiolite material has advantages over other clay-based materials, it reduce the gloss of the composition to which it is added, which is undesired in the art, and is not as effective as chemical additives.

As cited above, calcite powder is widely used in painting or coating compositions. Manufacturers obtain the calcite powder from some suppliers and process the powder and one of above mentioned anti settling additives to prevent settling of the calcite powder and other element of the painting or coating composition. Such way increases the production time and labor costs.

For this reason, it is desirable to have an anti settling product which is inexpensive and as effective as chemical additives and also which can be used as ingredient of a composition while acting as anti-settling additive, resulting in considerable expedition in production of paint or coating compositions.

BRIEF DESCRIPTION OF THE INVENTION

Present invention relates to a ready-to-use floating calcite powder with sepiolite which eliminates all above mentioned drawbacks.

Accordingly, one object of the present invention is to provide an anti-settling additive which is inexpensive, environment friendly, easy-to-produce and easy-to- use and even more effective comparing to other clay based anti-settling additives.

Another object of the present invention is to provide an anti-settling additive which does not reduce the gloss of the composition to which it is added.

Another object of the invention is to provide an anti-settling additive which will expedite production of painting or coating compositions.

Another object of the present invention is to enable companies to make the most of their sepiolite stocks.

To realize above mentioned objects, anti-settling additive of the present invention comprises %90-99 calcite powder and %1-10 white dolomitic sepiolit powder. Said speiolite is found in Eski§ehir - Turkey. DETAILED DESCRIPTION OF THE INVENTION

As it is known in the art, among clay-based materials, several types of sepiolite minerals is used in giving rheologic properties to emulsions or solutions as a clay- based anti-settling additive. One type of the sepiolite is found in Eski§ehir, a city in Turkey, more particularly in Sivrihisar region thereof. This sepiolite is known as meerschaum which is partly valuable and thus has been used in the manufacture of many types of ornamental stuffs for many years. Comparing to other sepiolite types such as those found and processed in Spain, the white dolomitic sepiolite is far more softer, elastic and more importantly in white color which is a desired and rare property of present sepiolite types.

However, white dolomitic sepiolite has not been tried in industrial area in contrary to other sepiolite types so far especially due to higher cost thereof. However, in recent years, rich sepiolite mines were found in Sivrihisar region of Eski§ehir and the Applicant acquired all of the mines and used this sepiolite type in the production of a novel sepiolite based cat litter, which is patented. However, in the interim, Applicant surprisingly found that this type of sepiolite has effective capability of providing rheologic properties to the solutions or emulsions such as water borne paints in addition its above mentioned properties such as softness and being in white color compared to other types of sepiolites.

In the light of the observation, in one preferred embodiment of the invention, said white dolomitic sepiolite material in the proportion of %1-10 and calcite powder in the proportion of %90-99 are ground together and a ready-to-use floating calcite powder is obtained. Alternatively, said calcite and sepiolite may be ground separately "and then obtained calcite powders and sepiolite powders are mixed, preferably by a mixer, in a non-aqueous medium.

Thanks to capability of white dolomitic sepiolite, said floating calcite powder is very effective in floating, dispersing and suspending pigments and all other fine industrial mineral powders in solutions or emulsions such as paint compositions. During relevant experiments, the product is mixed with water and it has been observed that the calcite powder does not settle for long period of times, even for months. It has also been observed that the floating caltice powder gives thixotropic properties at desired viscosity level to the compositions to which it is applied. Paint manufacturers can use the product in the manufacture of paints without having to obtain and process the calcite powder and anti-settling agent separately, whereby the manufacture process is expedited, resulting in considerable time and labor cost saving in respect of manufacturers of paints or similar products. Additionally, as for manufacturers of the floating calcite product, it is very easy and inexpensive to produce since white dolomitic sepiolite is softer than other sepiolite types and thus easy to process, namely grind.

Moreover, said sepiolite is white in color and thus the floating calcite powder also in white color. Therefore, when the calcite powder is used as anti-settling additives it does not reduce gloss of painting compositions to which it is added, which is desirable in the relevant art.

Additionally, in respect of sepiolite material suppliers, the present invention would enable them to make the most of their excessive sepiolite stocks by converting the stocks to ready-to-use floating calcite powder by a simple grinding process.

In one alternative embodiment of the present invention, other types of sepiolite materials can be used instead of white dolomitic sepiolite when obtaining the ready-to-use floating calcite powder.

In another alternative embodiment of the present invention, said calcite and white dolomitic sepiolite or other types of sepiolite can be processed to obtain an anti- settling additive in gel form.

Although the present invention has been shown and described in terms of a preferred embodiment, it will be appreciated that changes and modifications will be evident to those skilled in the art from knowledge of the teachings of the present invention. Such changes and modifications, which do not depart from the spirit, scope and teachings herein, are deemed to fall within the purview of the invention as set forth in the appended claims.