Maintenance-free stone tile, coating agent therefor, and method for producing the tile

An inorganic glassy coating agent for a maintenance-free stone tile, comprising a main ingredient which comprises:

• a polyorganosiloxane comprising at least one kind of an alkoxysilane or a mixture of at least two kinds of a tetrafunctional alkoxysilane and a trifunctional alkoxysilane,
• a silane coupling agent that has an epoxy functional group;
• and
• colloidal silica superfine particles having an average particle size of 5 to 20 μm;
• wherein provided that the proportion of the main ingredient being regarded as 100% by weight,
• the polyorganosiloxane is from 30 to 50% by weight;
• the silane coupling agent is from 5 to 20% by weight;
• the colloidal silica superfine particles are from 20 to 40% by weight;
• and
• phosphoric acid and/or such a substance is in the range from 0.1 to 5.0% by weight or
• a titanium based catalyst and/or an aluminum based catalyst is in the range from 0.1 to 20.0% by weight,
• added as a catalyst for heightening reaction hardenability.

A method for producing a maintenance-free stone tile, comprising:

• a step of adjusting a viscosity of a glassy coating agent for a stone tile to 3 cSt to 6 cSt (mm2/s), and then coating a floor surface of a stone that is obtained by roughening a surface of the stone beforehand by diamond grinding,
• a step of hardening the coating agent at ambient temperature in one hour to one day after the coating treatment to have a pencil hardness corresponding to 12H or more when the pencil hardness is measured on the basis of correlative data between a pencil hardness test and an abrasion resistance test;
• and
• a subsequent step of grinding the outer surface of the resultant coating layer with a diamond grindstone, whereby the resultant outer surface has a surface roughness Rmax of 0.8 s or less and a mirror surface glossiness of 80 or more,
• wherein the glassy coating agent for a stone tile comprises a main ingredient which comprises:
• a polyorganosiloxane comprising at least one kind of an alkoxysilane or a mixture of at least two kinds of a tetrafunctional alkoxysilane and a trifunctional alkoxysilane,
• a silane coupling agent that has an epoxy functional group;
• and
• colloidal silica superfine particles having an average particle size of 5 to 20 μm;
• wherein provided that the proportion of the main ingredient being regarded as 100% by weight,
• the polyorganosiloxane is from 30 to 50% by weight;
• the silane coupling agent is from 5 to 20% by weight;
• the colloidal silica superfine particles are from 20 to 40% by weight;
• and
• phosphoric acid is in the range from 0.1 to 5.0% by weight or
• a titanium based catalyst and/or an aluminum based catalyst is in the range from 0.1 to 20.0% by weight,
• added as a catalyst for heightening reaction hardenability.