Polyacetal binder

This technique applies to particular binders that exhibit specific degradation (catalytic) mechanisms in certain atmospheres. BASF (Germany) has developed an injection formulation containing polyacetal binders, which are eliminated at 110°C in acid atmosphere (98% nitrogen + 2% nitric acid). This atmosphere leads to the sublimation of a part of the polyacetal binder and the crystallization of the remaining part. However, sublimation vapors reqnire a reliable reprocessing before their evacuation into the air and the debinding furnaces must have an anticorrosion treatment in order to resist nitric acid fumes. 

Among the more than several uses for polyethers in ordn application is as a binder for extrusion-cast expls (Ref 3), and in a caseless proplht charge where the charge is used as an ammo element (Ref 5). Also, some development work on the use of Polyacetal resins (polyformaldehyde) as a fuel has been done by Singhal T ien y[Pg.816]

Various polymer binders and their blends are employed (PE, PA, CFD, polyacetal, thermoelastoplasts, and so on) for the inhibited antifrictional materials of INHAM trade mark. In addition, oil-soluble inhibitors of donator types (KP, KSK, MNI, etc.), acceptor types (MSDA, BMP, SIM, etc.) and their synergetic blends with complex effects (AKOR, NG and others) are used as their Cl. The inhibitors are impregnated into the INHAM materials in the form of a solution in PI (mineral or silicone oils) and may contain various fillers and modifiers depending on the purpose. 

The rate of depolymerizing polyacetal to formaldehyde is the subject of much research, because the rate of depolymerizing is a critical factor in MIM costs, and there is not that much proven information on it. Removal of binder is determined by various factors, namely, binder removal temperature, about 120°C (248°F) catalyst linear or random degradation of polyacetal resin fineness of powder mold part shape and size and catalytic debinding furnace. The catalytic furnace developed for debinding... 

Polyacetals have a low ceiling temperature, and are readily depolymerized by unzipping at low temperature (0.4-0.8% min at 222°C for POM). Owing to this low thermal stability, polyacetals can be used only if end-capped with stable groups (acetate or ether). This inherent thermal instability is exploited in an industrial method known as metal injection molding , which allows fine metal powder mixed with a polymer binder to be processed by injection molding, in much the same way as thermoplastic materials [31]. In a procedure based on POM, the binder is removed by thermal devolatilization according to Eq. (62)... 

Binder High pressure Polyethylene, polypropylene, polystyrene, polyvinyl alcohol, polyethylene glycol, ethyl vinyl acetate, polyacetal, paraffins, microcrystalline waxes... 

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