GENIOSIL® STP-E35 is a polyether-based silane-terminated polymer suitable as a binder in moisture curing formulations. It is a clear liquid with a slight but characteristic odor and differs to conventional silylated polymers due to its high reactivity. This is a direct consequence of the trimethoxysilyl group attached to the organic backbone. It hydrolyzes in the presence of moisture to finally form a stable siloxane network initiated by heavy metal or strong amine catalysis. Formulations are characterized by the following advantages:
- simple compounding with conventional auxiliaries
- plasticizer free if desirable
- good mechanics
- very good elastic recovery and high elasticity
- rapid curing
- broad adhesion profile
GENIOSIL® STP-E35 dissolves readily in standard organic solvents. It is virtually insoluble in aqueous media, and reacts slowly releasing methanol and forming a resinous deposit. Due to its reactive terminal groups GENIOSIL® STP-E35 forms a skin following air exposure after several days. However, its reactivity with water or atmospheric humidity must be taken into account during storage and processing, since the material will slowly start to condense. GENIOSIL® STP-E35 can be formulated by conventional methods and mixing processes. The formulation composition depends on the required property profile. GENIOSIL® STP-E35 can be formulated with a variety of fillers at high addition levels. The range starts with oxides, such as aluminum trihydroxide, quartz powders or pyrogenic silicas, and extends to coated and uncoated chalks. Water scavengers can be added to stabilize the formulations against premature curing as this is moisture-curing technology. Therefore exclusion of moisture during compounding and storage is necessary. GENIOSIL® XL 10 or GENIOSIL® XL 70 are particularly suitable scavengers. Any type of plasticizer can be used to further lower the viscosity as well as to impact elongation values. It has been observed, that polypropylene glycol types give better mechanical performance whereas aromatic plasticizers like trimellitates or phthalates yield good adhesion values. Antioxidants, UV- and light-stabilizers are mandatory to ensure durable sealants and adhesives. The amount and type of stabilizer depends on application needs. Curing of GENIOSIL® STP-E35 requires a catalyst which can be organo-metallic or a strong base compound. Here dioctyl tin or titanium compounds have proven their suitability in the presence of an aminosilane such as GENIOSIL® GF 96. In particular, GENIOSIL® GF 95 can attain improved water resistance, which is further increased by the addition of epoxy silanes. Surface Treatment Always apply the formulation to clean and dry surfaces.