Primers: silicone sealants

Although silicone sealants adhere to many unprimed substrates, primers may be required to achieve long-term adhesion to some substrates. Primers may also be required to minimise the risk of migratory staining from the sealant into the adjacent substrate. 

Compound, caulking, conductive Compound, polyurethane Compound, heat sink, silicone Compound, sealing, poly sulfide rubber Compound, plastic polyurethane Primer, silicone rubber sealant Primer, polyurethane Primer, silicone... 

Epoxy adhesives such as Huntman s Araldite AW 134 with HY 994 hardener (cured for 15 min at 120°C) and Araldite AV 1566 GB (cured for 1 h at 230°C) give the best results with this engineering resin. Other adhesives that can be used are cyanoacrylate (Loctite 414 with AC primer), anaerobics (Loctite 638 with N primer), and silicone sealant (Loctite Superflex). The highest lap-shear strength was obtained with Araldite AW 134. This adhesive has balanced properties, good resistance to mechanical shock, thermal resistance to 100°C, and reasonable stability in the presence of aliphatic and aromatic solvents. Some solvents, particularly chlorinated hydrocarbons, will cause deterioration of the bond [30]. 

Polyethersulfone may be solvent cemented. Conventional adhesives recommended by the manufacmrers include epoxies (Huntman s Araldite AV 138 with HV 998 hardener and Araldite AW 134B with HY 994 hardener), Hysol 9340 two-part epoxy paste, and Silcoset 153 RTV silicone sealant supplied by ACC Silicones Europe with primer OP and Silcoset RTV2 with Superflex primer supplied by F. Ball and Company [32]. The highest lap-shear strength was obtained with the Araldite AW 134B [30]. 

Chem. Descrip. Tetraethyl orthosilicate CAS 78-10-4 EINECS/ELINCS 201-083-8 Uses Binder in precision investment castings as sec. backup casting coating mfg. of electronics, computer components silicon dioxide source in films deposited on silicon substrates catalyst intermediate component in zinc-based primer coatings for corrosion-resist, paints crosslinking agent in mfg. of sealants raw material in sol-gel systems scratch resist, hard coat on glass and plastic lens... 

Uses Adhesion promoter aiding bond between fillers and reinforcements (e.g., fiberglass, particulates, metals) and various polymers (phenolic, urea-melamine, epoxies, polyamide, PU) used in glass fiber sizes and finishes, wool insulation resin binders, primers, foundry sand binders, adhesives, sealants, and abrasive grinding wheel binders low VOC emissions Manuf./Distrib. Aldrich http //www.sigma-aldrich.com, Gelest http //www.gelest.com Trade Name Synonyms Silquest Y-11542 [Crompton/Silanes Spec. Silicones]... 

For highway sealants (119), the desired properties are adhesion (without primer), weatherability (adequate retention of properties for more than 10 years), resilience, temperature stability, hardness range for hot or cold (firm enough to resist incompressibles, puncture and tear resistant), good uncured consistency, solvent resistance, repairability, and abrasion resistance. Silicones, especially those of low-modulus, offer nearly all the properties desired as a good highway sealant. 

Liquid silicone rubbers (LSRs) are two-part grades which can be coinjection-molded with thermoplastics to make door locks and flaps for vents.1 LSRs can be biocompatible and have low compression set, low durometer hardness, and excellent adhesion. One-part silicones are cured by ambient moisture. They are used for adhesives and sealants with plastic, metal, glass, ceramic, and silicone mbber substrates. A solventless, clear silicone/PC has been developed which requires no mixing, and can be applied without a primer. ... 

MS Polymers. A relatively new class of adhesives are the two-component MS polymer adhesives, known as moisture-cross-linkable sealants up to know. Due to their excellent elastic properties they are used for elastic bonding. Chemically they are based on silanealkoxy-modified prepolymers such as polyfpropylene glycol). The end groups of these so-called MS polymers are sdanealkoxyl groups which are hydrolyzed by water and then cross-link. In comparison to silicone adhesives, they adhere to all kinds of surfaces without any primer and are paintable in the freshly cured state. 

Sealant, ablative, silicone base, room temperature curing and primer Sealant, silicone rubber, room temperature vulcanizing Sealing compound, high tear strength Sealant, electrically conductive... 

Abstract In this chapter, classification of adhesive and sealant materials is presented. For this purpose, various categories are considered depending on the polymer base (i.e., natural or synthetic), functionality in the polymer backbone (i.e., thermoplastic or thermoset), physical forms (i.e., one or multiple components, films), chemical families (i.e., epoxy, silicon), functional types (i.e., structural, hot melt, pressure sensitive, water-base, ultraviolet/ electron beam cured, conductive, etc.), and methods of application. The classification covers high-temperature adhesives, sealants, conductive adhesives, nanocomposite adhesives, primers, solvent-activated adhesives, water-activated adhesives, and hybrid adhesives. 

An example of a silicone primer for use with polysulfide sealants is Chemlok AP-131 (LORD Corporation). ... 

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