GENIOSIL® XM 25
GENIOSIL® XM 25 reflects new silane terminated polymers suitable as reactive diluent in moisture-curing formulations. The technology embrace the typical Wacker portfolio. GENIOSIL® XM 25 belongs to gamma chemistry.
GENIOSIL® XM 25 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
- modification to achieve lower Modulus
- very good elastic recovery and high elasticity
- rapid curing
- broad adhesion profile
GENIOSIL® XM 25 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® XM 25 forms a skin following exposure to air 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® XM 25 can be formulated by conventional methods and mixing processes. The formulation composition depends on the required property profile. GENIOSIL® XM 25 can be formulated with a variety of fillers at high addition ratios. The range starts with oxides, such as aluminum hydroxide, quartz powders or pyrogenic silica, 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® XM 25 requires a catalyst that can either be organo-metallic or a strong base. Here dioctyl tin or titanium compounds have proven their suitability especially in the presence of an aminosilane such as GENIOSIL® GF 96. In particular, GENIOSIL® GF 95 can attain improved water resistance, which is increased by the addition of epoxy silanes. Surface Treatment Always apply the formulation to clean and dry surfaces.
GENIOSIL® XM 25 is used as a reactive plasticizer in elastic sealant & adhesives, potting compounds and coatings, that does not migrate out of cured formulations. The adhesion profile of formulated sealants and adhesives was seen to enhance when including this polymer. Additionally it can be used to reduce modulus and is thus suitable for low modulus formulations. Curing takes places at ambient temperature in the presence of both moisture and catalyst. Depending on the formulation, either prepared as one-part or two-part systems, it will give good adhesion to a wide variety of substrates even without pretreatment. The low glass transition temperature allows stable mechanical properties over a wide temperature range.