| GENIOSIL® XB 502 is a silane-terminated binder based on alpha-silane technology for the formulation of high-strength adhesives. Alphasilane-terminated polyethers are an important group of moisture-curing binders that can crosslink without a tin catalyst. GENIOSIL® XB 502 is a transparent low-viscosity binder. The resultant adhesives display hardnesses in the high Shore D range when cured. This new polymer therefore represents an extension of elastic binders such as GENIOSIL® STP-E10 and can be mixed with this product group in any proportions in order to tailor the properties to the respective application.
Catalysts: Curing of GENIOSIL® XB 502 requires a catalyst that does not necessarily have to be organo-metallic. However dioctyl tin (e.g. TibKat 223) may be used if required. Catalysis can also be accelerated with titanium systems (Tyzor®TnBT or Tyzor® PITA-SM), as well as inorganic (phosphoric) or organic (tartaric) acids. Manufacturer recommends using an amine catalyst, and adjusting the skin-formation time by varying the amount of aminosilane used. GENIOSIL® GF 9 and GENIOSIL® GF 95 have proven particularly advantageous here. GENIOSIL® GF 95 can achieve improved water resistance, which is increased by the addition of epoxy silanes.
Plasticizers: A plasticizer can be used with the new binder, but impairs its mechanical properties. For example, GENIOSIL® XB 502 can be readily mixed with polyethers, phthalates, trimelletates and phosphoric acid ester. Another way of elastifying a GENIOSIL® XB 502- Based formulation is to use silane-modified polymers of the hybrid series GENIOSIL® STP-E. Tailored elastic adhesives can be developed while retaining the high strength properties.
Fillers: GENIOSIL® XB 502 can be formulated with a variety of fillers, in amounts of up to 70%. The range starts with oxidic materials, such as aluminum trihydroxide (e.g. Martinal® OL 104), quartz flours (e.g. Millisil® W10) or pyrogenic silicas (HDK® H13L), and extends to coated (Omyabond® 520, Hakuneka®CCR-S10) and uncoated chalks (Omyacarb® 5 GU). Based on a model formulation of 1:1 filler to GENIOSIL® XB 502 plus 1.5% GENIOSIL® GF 9 as the catalyst, tensile lap-shear strength values from 9 to 15 N/mm² with beech/beech test specimens were determined.
Stabilizers: Because of its polymer backbone, GENIOSIL® XB 502 is already stable to heat and light. However, manufacturer recommends using the conventional stabilizers employed in STP-E technology to guarantee long-time stability of the adhesive. Experiments have shown that a sterically hindered amine (e.g. Tinuvin 123) and an oxalanilide (e.g. Hostavin 3206) provide adequate stabilization. Special features: Properties of the binder GENIOSIL® XB 502: - low viscosity
- easy handling and dosing
- tin-free catalysis
- non-labeling
Properties of the formulated adhesive:- high mechanical strength with ast strength build up
- hardnesses in the Shore D range
- good adhesion to metals, glass and ceramics
- non-bubbling
- isocyanate,- tin- and solvent-free
- good heat-stability
- low yellowing tendency
- formulation of water resistant products possible (D1 - D4)
Application: Adhesives can be formulated having high tensile lap shear strength (= 15 N/mm²) on a wide variety of substrates. With certain substrates, it may be advisable to modify the elasticity of the binder. Based on the model formulation and filler (1 : 1), with 2.5% GENIOSIL® GF 9 as catalyst, the tensile lap-shear strength of beech/beech and aluminum/aluminum test specimens was determined. While GENIOSIL® XB 502 is ideal for bonding wood, metals can be very readily bonded when GENIOSIL® XB 502 is mixed with GENIOSIL® STP-E10 in a ratio of 3 : 1.Further state-of-the art bonding: - wood
- stone
- metal
- ceramics
- bonding of different substrates (e.g. wood/metal, metal/concrete)
Information provided by Wacker Chemie AG. |
