Coatings moisture-impermeable

Nowadays, amorphous silicon dioxide may be used as corrosion-resistant coatings in various types of cans and as moisture-impermeable films, as well as for rheology control in materials such as paints, silicone rubbers, polyester compounds, dental formulations, emulsions, cosmetics, and excipients in pharmaceuticals. 

Uses Butyl mbber in sealants, coatings, elec, encapsulating compds., and conformal coatings incl. moisture-impermeable coatings, marine and constmetion sealants, elec, encapsulants tackifier for pressure-sensi-... 

Recently more and more attention has been paid to atmosphere-resistant and moisture-impermeable coating materials [205], for example, in apparatus construction (instrument making), enamels constituting copolymers of vinylchloride with vinyracetate in agriculture,alkyd-styrene enamels and for the painting of light motor vehicles [206], polyacrylate enamels. 

Air-bubble entrapment may occur in the case of a gravity-appHed continuous coating over an impermeable substrate. Bubbles may also be caused by moisture vaporization from the substrate. Remelting of the coating may minimize the bubble defects. Curtain coating equipment of this design is capable of operation at substrate speeds up to 500 m /min. 

Many seeds become dormant as a means of survival and are able to germinate after many years in the soil. Factors that influence seed germination and seed dormancy include temperature, moisture, oxygen, light, inhibitors (e.g., allelopathic effects), hardness or impermeability of seed coats, mechanically resistant seed coats, immature embryos, and after-ripening requirements (e.g., cool temperatures for several months). Weed seeds may survive and germinate due to several of these characteristics (Pareja et al, 1985). 

Tablets manufactured with OraSolv technology should contain an effervescence couple along with microparticles of drug within a rupturable coat. The tablets manufactured are compressed at a low hardness that promotes fast disintegration. The dosage forms need to be packaged in foil-foil aluminum blisters with a dome shape that impact physical protection and impermeability to moisture. This constitutes the PakSolv Techonology. ...

This is the newest coating process to emerge and has been applied to PET and PP films. The coating shows high hardness, transparency and impermeability, reducing moisture permeation by 40-60x and oxygen by up to lOOx. In the process of manufacture acetylene is ionised in a vacuum chamber, releasing carbon onto a film. 

Egress or loss may relate to any substance (liquid, solid or gas) which exerts a vapour pressure under normal storage conditions, which usually lie between (-20°C) deep freeze conditions and somewhere around +55 to 60°C. However, moisture loss (and gain) is critical to many products, hence requires special consideration. As mentioned previously, whether loss is solely via the closure and/or pack depends on the materials employed for each. In order to separate the loss from each it may be necessary to carry out controlled experiments where either the container or the closure is covered or coated with an impermeable material (wax dipped or foil covered and sealed) so that permeation from one can be quantified. 

Hydrophobic treatment. In principle, reduction in the moisture content of concrete can also reduce the corrosion rate in chloride-contaminated concrete, and thus hydrophobic treatment may be used to control the corrosion rate. Nevertheless, there is insufficient knowledge about the critical moisture content in the case of chloride-induced corrosion. The greater the content of chlorides and their hygroscopicity, the lower the moisture content must be. The hterature is conflicting in some cases hydrophobic treatments seem to slow down chloride-induced corrosion, in other cases they clearly do not [8]. However, since no precise data are available in this instance, an evaluation must be made of the advisabihty of applying hydrophobic treatments and impermeable coatings that prevent concrete from coming into direct contact with water (but allow aqueous vapour to pass so that the concrete will dry out), on a case-by-case basis. 

Conformal coatings protect many different types of products with a nearly impermeable barrier against moisture, dust, and harmful gases. In many applications they also act as dampers against shock and vibration. 

Cost, ease of handling, ease of application, shelf and pot life, strength and durabiUty of the cured coating, impermeability to moisture and dust, and other factors must be considered. 

Permeability Copolyester TPE films and coatings are permeable to moisture and gases (O2 and CO2) but are non-porous and thus impermeable to water, blood, and bacteria.[ ... 

Barrier property to moisture and gas is another key demand for PU coatings. It is reported that impermeable nanoclays can effectively reduce the permeability of polymers by up to hundred times. The mechanism of permeabrhty has been widely discussed from experimental and theoretical aspects. Nielsen [44] proposed a permeability model for a regular arrangement of platelets based on the assumption, that is, rectangular platelets are uniformly dispersed and perpendicularly... 

The simplest way of hindering the corrosion processes at a metal surface is to seal it off by an impermeable and adherent barrier coating, which denies access to moisture and oxygen. The barrier coatings used on iron and steel need to be strongly resistant to the corrosive influence of their environ-... 

PflMW layer provides most of the corrosion protection in the multilayer coating system. It contains inhibitive and reactive pigments, and ideally must be impermeable to moisture intrusion, adhere strongly to the Pre-Treatment, ideally through a gradient in composition to the substrate. 

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