Silicone adhesion

One of the important breakthroughs in the silicone PSA industry has been the development of new release liners based on fluorosilicones [116]. These new materials significantly improve the release characteristics of the silicone PSAs, something that has been difficult to achieve because of the high adhesion silicone PSAs show to low energy substrates, including silicone rubbers and liners. 

The backing material and release liner can be fabricated from a variety of materials including polyvinylchloride, polyethylene, polypropylene, ethylene-vinyl acetate and aluminium foil. The most important property of these materials is that they are impervious to both drug and formulation excipients. The most useful backing materials conform with the skin and provide a balanced resistance to transepidermal water loss, which will allow some hydration of the stratum corneum, yet maintain a healthy subpatch environment. The release liners are usually films or coated papers and must separate easily from the adhesive layer without lifting off any of the pressure-sensitive adhesive. Silicone release coatings are used with acrylate and rubber-based adhesive systems, and fluorocarbon coatings with silicone adhesives. 

Pressure-Sensitive Adhesives. Silicone PSAs are used primarily in specialty tape applications that require the superior properties of silicones, including resistance to harsh chemical environments and temperature extremes (398,399). Silicone PSAs are also used in applications requiring long service life, electrical insulation, and protection from moisture. Another distinctive advantage of silicone PSAs is their ability to wet low surface energy tape substrates such as PTFE. 

Our product lines feature high-quality concrete admixtures, specialty mortars, sealants and adhesives, silicones, damping and reinforcing materials, structural strengthening systems, industrial flooring, roofing and waterproofing systems. 

Hydroxyethylethylene urea Lithopone Olefin/acrylate copolymer PPG-2 isoceteth-20 acetate Styrene/allyl alcohol copolymer gloss aid, adhesives Silicone glycol copolymer gloss aid, agric. 

PEG-3 dimethacrylate Trimethylolpropane propoxylate triacrylate photoresist adhesion, silicon nitride Phenyltriethoxysilane photoresists... 

Keywords adhesion, silicone, corona, surface, contact angle, XPS, AFM, PP, PET... 

The use of adhesives/sealants in both the industrial and consumer spheres has increased dramatically in the past 20 years. In the industrial segment, both reactive and nonreactive systems are used in a wide variety of applications. The increasing use of reactive systems has, however, tended to overshadow that of the nonreactive systems. Most prominent amongst the reactive systems favored in industrial applications are anaerobic sealants (methacrylate ester based), instant adhesives (alkyl cyanoacrylate ester based), acrylic (toughened) adhesives, epoxy resin adhesives, polyurethane/isocyanate-based adhesives, silicone adhesives/sealants, and phenolic resin adhesives. 

These polymers have unusual properties and are used both to promote and to prevent adhesion. Silicones have good heat stability, chemical inertness, and surface-active properties. Applications of silicone adhesive fall into four types... 

A second aspect is that some adhesives/sealants cure by the diffusion of water vapour. This causes a sequence of chemical reactions, which leads to chain extension and possibly cross-linking by step copolymerization. Examples are some silicone and isocyanate materials, where the depth of cure is often proportional to the square root of RH, and to the square root of time" (Moisture cure of adhesives, Silicone adhesion). 

Water in the atmosphere is pure and free, and in a temperate country like the United Kingdom, the amount present, as expressed by the relative Humidity, remains fairly constant for most of the time. Cyanoacrylates, silicones and isocyanates are among the materials that may be available as one-part, moistnre-cnred adhesives. (Cyanoacrylate adhesives. Silicone adhesion). 

Information on particular types of adhesive may be found in articles cited above and in the following entries Hot melt adhesives. Selection of adhesives. Silicone adhesives addition cure. Silicone adhesives condensation cure. Toughened adhesives. 

Silicones are widely used in industry, for example, as adhesives, sealants and release agents see Silicone properties and Silicone adhesion. Silicone adhesives may cure by condensation or addition reactions. The former is considered here and the latter in Silicone adhesives addition cure (see also Step polymerization). 

Frances, R.S. and Edelman, R., Ultraviolet radiation-curable acrylic polymer pressure sensitive adhesives, Japanese Patent JP 200004-4887, 2000 Frances, J.M., Delchet, L., Amaut, C., Gambut, L., Pressure-sensitive adhesive silicone compositions. World Patent 0310257, CA-2003-97495 2003. 

The bonding is achieved by different methods. The hard component can contain undercuts where the rubber is anchored during its vulcanisation, a primer on the hard component or even using self-adhesive silicone rubber will give sufficient anchorage. 

Section 11.5. will explain the three alternatives for bonding, where mechanical anchorage (undercuts) or self-adhesive silicone rubber allow for two colour injection moulding. 

In such cases the processor basically has the choice between undercuts, primers or primerless self-adhesive silicone rubber. 

Self-adhesive silicone rubbers do not require a primer and, therefore, the plastic substrate can be injection moulded on the same machine as the silicone rubber. 

However, at the same time it is possible to achieve sufficient bonding to steel without having problems with the self-adhesive silicone sticking to the mould, as is the case with conventional bonding agents for rubber to metal components. 

Table 11.4 Self-adhesive silicone rabbet ELASTOSIL LR 3070/40 Test results of peeling test according to DIN 53531 [11] ...

Transdermal drug-delivery systems offer several important adventages over more traditional approaches, in addition to the benefits of avoiding the hepatic first-pass effect. Transdermal drug delivery systems (TDDS) are usually in the form of patches incorporating pressure sensitive adhesives. There are two basic designs for transdermal patches matrix or reservoir type. Matrix-type patches include monolithic adhesive and polymer matrices, whereas reservoir-type patches include liquid and solid-state reservoirs [71-73]. For various types of transdermal delivery systems, medical grade adhesive silicones are used as [73,74] ... 

As a drug in adhesive system the drug matrix is formed by dispersing the active pharmaceutical ingredient in an adhesive silicone and then spreading it onto an impervious backing layer. On top of the former, layers of unmedicated adhesive silicone are applied. 

Silicone Being soft and having good adhesion, silicone is useful over a wide temperature range. 

Siiicone Adhesives silicone rubber 23 3 8 No effect Lexan GE Plastics... 

Frances JM, Delchet L, Arnaut C, et al. Pressure-sensitive adhesive silicone compositions. World patent WO 0310257, CA] 2003 2003-97495. 

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