Impregnating resins, silicone

Silicone resins. Methyl silicone resins which can be diluted with organic solvents have been used for impregnating the facades of buildings since the mid-1950s. Surfaces impregnated with silicone resins show... 

This comprises composite materials on mica, glass fibre and asbestos bases, impregnated or glued together with silicone resins or silicone elastomer. These materials must not contain any organic fibrous materials such as paper or cloth backing, which is covered under class B and even F insulation systems. 

Silicone resins find use as insulating varnishes, impregnating and encapsulating agents and in industrial paints. 

Reactive adhesives Reactive adhesives are either low molecular weight polymers or monomers that solidify by polymerization and/or cross-linking reactions after application. Cyanoacrylates, phenolics, silicon rubbers, and epoxies are examples of this type of adhesive. Plywood is formed from impregnation of thin sheets of wood with resin, with the impregnation occurring after the resin is placed between the wooden sheets. 

Ethyl silicate (tetraethoxysilane) is often used without modification as a water-repellent material for concrete and masonry in general. All, or nearly all. the ethoxyl groups are hydrolyzed by the moisture of the air to form cross-linked watcr-rcpcllcnt polymers. The material is applied in desirable thickness, dissolved in some volatile solvent which soon evaporates. Silicone resins which arc partially condensed before application, or even fully condensed, can also be used here. In the latter case, hardness is achieved on evaporation of the solvent. Certain silicone resins arc useful as hydrophobic agents for the impregnation of paper and fabrics. 

Figure 6.15 Depth of penetration the upper block was impregnated with a silicone resin the block on the lower left-hand side was impregnated with silane the block on the lower right-hand side was impregnated with siloxane. Courtesy of HULS...

Silicone resins can be used for impregnating strongly absorbent, poorly absorbent, light and dark substrates. Unlike the siliconates, silicone resins can be applied as often as desired to already impregnated surfaces since they do not repel organic solvents. 

Keywords silicone resin network, masonry protection, building material, natural stone impregnation, silicone coating of mineral substrates, structure-effect principle of trifunctional silicones... 

The Silicone Resin Network in Paints and Impregnated Building Materials... 

Fig. 6. Comparative SE images of an untreated Lower Triassic red sandstone and a red sandstone (both Wfistenzeller Buntsandstein) impregnated with a silicone microemulsion concentrate (SMK). a, b Untreated Mica layer surfaces (white arrows) and clay mineral fibers (illite, black arrow) without signs of polymeric encapsulation, c - f Impregnated with SMK d A detailed view fiom Fig. 6c clay mineral-mica intergrowlfas reveal structured silicone films on the prism plane of the cl mineral, e Clay mineral intergrowth with quartz, coated with a veil of silicone resin (white arrow) plan view of crystallogra]diic prism plane (110) or (010) (black arrow) plan view of sheet plane (001). f Detailed view from Fig. 6e day mineral perfectly encapsulated by structured silicone resin network.

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