Silicate paints applications

On account of their properties, silicate paints are used as weather-resistant and wash-resistant coatings on mineral substrates in both exterior and interior applications. Substrates include lime, lime cement, cement renders (mortar groups I, II, and III), concrete, sandy limestone, as well as old silicate or mineral coatings. Old lime coats should be removed completely, and gypsum substrates should be treated only... 

Paints are complex formulations of polymeric binders with additives including anti-corrosion pigments, colors, plasticizers, ultraviolet absorbers, flame-retardant chemicals, etc. Almost all binders are organic materials such as resins based on epoxy, polyurethanes, alkyds, esters, chlorinated rubber and acrylics. The common inorganic binder is the silicate used in inorganic zinc silicate primer for steel. Specific formulations are available for application to aluminum and for galvanized steel substrates. 

Kuhlmanjt remarks that the contact of lime with silicata of potassa, always determines the decomposition of this salt and its transformation into silicate of lime, which retains the coloring matter, and even carbonic acid, as lately supposed by M. Fuchs but when the colors aro applied ou bodies which do not react on the soluble silicate—such as wood, iron, glass, et cetera —it becomes necessary to seek for conditions of insolubility in the reaction of the coloring matter on this silicate. On wood the difficulty may be removed by the application, before the silicious painting, of a sufficiently thick covering of chalk, which may bo applied with zinc, or fixed with a very little silicate. 

In general, polycarbonate resins have fair chemical resistance to aqueous solutions of acids or bases, as well as to fats and oils. Chemical attack by amines or ammonium hydroxide occurs, however, and aliphatic and aromatic hydrocarbons promote crazing of stressed molded samples. For these reasons, care must be exercised in the choice of solvents for painting and coating operations. For sheet applications, polycarbonate is commonly coated with a silicone—silicate hardcoat which provides abrasion resistance as well as increased solvent resistance. Coated films are also available. 

Water-based inorganic zinc primer 65 100-125 15 min 8 h Self-curing alkali silicate primer under most paint systems, good from — 90°C to 400°C, withstands rain 60 min after application, fair flexibility, good abrasion resistance when cured... 

Since the alcohol is regenerated and the net result is the same as though the original silicon halide had been hydrolyzed directly, it is obvious that the esters may be regarded as hydrolytic intermediates which allow the over-all process of hydrolysis to be controlled and directed. The commercial value of the esters therefore lies in their ability to deposit silica in a desired form and at a well-defined rate. Besides their use as stone preservatives, esters like ethyl silicate are used as sources of pure ion-free silica and as additives to organic paints and lacquers to provide a harder, more resistant film. A disperse sol of silica in n-propanol (possibly derived from propyl silicate) is available commercially for related applications. 

Talcs (RI 1.55) are hydrated magnesium silicates. It is extremely soft and is characterized by its slippery feel. Talc is used in paint to assist the dispersion of titanium dioxide and to improve the application properties of the paint film. 

Potassium-silicate water glass is manufactured for special purposes (e.g. binder for acid-resistant cements, fresco paintings, etc.). The application of soluble silicates in industry is dealt with in the monograph by Vail (1952). 

MAJOR PRODUCT APPLICATIONS high temperature synthesis of wollastonite, synthesis of calcium hydro silicates, sealants, stucco, primers, road marking formulations, resin casting, adhesives, mortars, coatings, paint, lacquers, special papers, construction elements, pin insulators, machine tools, hning for chemical pumps... 

Talc is the magnesium silicate structural analog to pyrophyllite. Its properties are nearly identical to pyrophyllite, except that Al3+ cations have been replaced by Mg2+ cations [25], Talc occurs in secondary deposits and is formed by the weathering of magnesium silicate minerals such as olivine and pyroxene [2], In bulk form, talc is also called soapstone and steatite. A typical composition for talc is given in Table 7 [22], Historically, talc has been used extensively in electrical insulator applications, in paints, and as talcum powder [2],... 

Pigment Effects. These effects are achieved in practice only with precipitated silicates. This effect is of special significance in emulsion or latex paints and in paper coatings. These applications play a more minor role in the United States than they do in Europe and Asia. Part of the titanium dioxide content in the paint and paper-coating applications is substituted with precipitated silicates without causing a deterioration in the brightness or opacity. The amount of silicate added must not exceed... 

The concept of fire-retardancy is remarkably old. The Greek historian, Herodotus, in 484-431 BC recorded that the Egyptians imparted fire-resistance to wood by soaking it in a solution of alum (potassium aluminum sulfate) [Browne, 1958]. The Romans added vinegar to the alum for the same purpose. Vitruvius in the first century BC described the natural fire-retardant properties of the larch tree and some military applications of fire retardant materials such as plaster of clay reinforced with hair [Vitruvius, I960]. In 1638, Circa recorded that Italian theaters were painted with a mixture of clay and gypsum (potassium aluminum silicate and hydrated calcium sulfate) to protect them from fire. Wild was issued a British patent in 1735 for his process of treating wood with a mixture of alum, ferrous sulfate and borax (sodium tetraborate decahydrate). And Gay-Lussac in 1821 showed that a solution of ammonium phosphate, ammonium chloride and borax acts as a fire-retardant for wood. 

The form of magnesium silicate hydroxide with which most people are familiar is talc, the main ingredient in talcum powder. Talcum powder is used directly as a skin treatment, especially for babies, primarily as a moisture absorbent and for soothing the skin. It is also used in a number of cosmetic products, including blushes, eye shadows, make-up foundations, and face powders. Talc is also used widely as an additive to give products a smoother texture. Some products in which it is found include paints, rubber products, roofing materials, ceramics and insecticides. Other applications of talc include ... 

On application, the paint layer hardens within a short time due to evaporation of the solvent, progressive hydrolysis of ester groups after uptake of atmospheric moisture, reaction of silanol groups with the zinc and substrate, and condensation of silanol groups to form sparingly soluble, cross-linked silica gel [2.186]. Conditions are generally chosen such that the film is hard enough to allow transportation after 4 h and a topcoat after 24 h. Alkyl silicate zinc dust paints are particularly suitable... 

Historical Development. The importance and advantages of ethyl silicate zinc dust paints were recognized and intensively investigated in the late 1940s [2.187], [2.188]. The fundamental work of Lopata and Keithler [2.189] on the partial acid hydrolysis of tetraethyl orthosilicate and the use of the product as a zinc dust paint binder was followed by attempts to improve the application properties and quality of the coatings (e.g., by adding polyfvinyl butyral) [2.190], alkyl titanates [2.191], borate esters [2.192], or trialkyl phosphates [2.19. ]. 

Continuous efforts have therefore been made to develop binders for one-pack paints which must be completely compatible with active pigments such as zinc dust. Mixtures of ethyl silicate and zinc can be stored for unlimited periods in the absence of water. If the hydrolysis and condensation reactions caused by atmospheric moisture can be sufficiently accelerated during application of the coating, a one-pack system can be produced. 

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