Polyurethane Casting resin

Baygal, Baymidur Bayer Polyurethane casting resins... 

Chem. Descrip. Aluminum trihydrate CAS 21645-51-2 EINECS/ELINCS 244-492-7 Uses Flame retardant, filler for polyester, acrylic, and epoxy resins, polyurethanes (casting resins), powd. coatings Propertes Povird. = 4 pm median particle size bulk dens. = 530 kg/m oil absorp. = 21 cmVIOO g conduct. <140 p cm < 0.35% moisture Martinal ON-906 (Martinswerk GmbH Lonza]... 

Baygal/Baymidur Polyurethane casting resins, PU Bayer AG/Miles... 

FIGURE 1.274 Casting process of a low-viscosity polyurethane casting resin in the casting chamber... 

Vacuum casting is a shaping technique for producing plastic parts using for example stereolithography models as the masters. The master is used as a pattern to cast a mold in silicone, and this mold is used for replication. The material used for replication is a polyurethane casting resin. Resins with a number of different property profiles are available. 

P.O.34 is rarely used in polyolefins. In such media, it only withstands exposure to 200°C, and its opaque colorations show insufficient lightfastness. P.O.34 tends to bloom, especially in extrusion products made of low molecular weight LDPE types. The pigment is, however, recommended for a variety of other media. These range from aromatic polyurethane foams to cast resins of unsaturated polyester, in which the pigment slightly delays the hardening process. 

P.R.164 was also found in cast resin composed of methacrylate and unsaturated polyester. The pigment does not affect the hardening process of such media, which may be carried out, for instance, by using peroxides. An important field of application was in the coloration of various polyurethanes, for which the pigment was also sold in the form of a pigment preparation. 

P.R.144 is also suited to use in other plastics, such as polystyrene, polyurethane, elastomers, or cast resins, including those made from unsaturated polyester. 

P.Y.110 lends color to polystyrene and styrene containing plastics. It is a suitable candidate for unsaturated polyester and other cast resins, as well as for polyurethane. P.Y.110 is used to an appreciable extent in polypropylene spin dyeing, it is very lightfast in this medium. It is utilized in polyacrylonitrile spin dyeing and sometimes also in polyamide. Its fastness properties, however, especially its lightfastness, do not meet special application conditions (Sec. 1.8.3.8). 

The surface of the model is covered with a uniform layer of clay or plasticine. The thickness of the spacing layer determines the thickness of the final mold. The next step is to build up a rigid layer on top of the spacer. This support is either poured (plaster or casting resin) or built up in layers by spreading the material (polyester, polyurethane or epoxy resin reinforced with fiberglass matting). Once the support has set, it is separated from the spacer, which is then discarded. The support, which must contain air-escape and feeding holes, is now fitted over the model. The silicone rubber is poured into the hollow space between the support and the model and allowed to cure. The... 

Casting resins such as unsaturated polyester resins, polyurethane resins and foams, epoxy resins and, within limits, acrylic resins... 

Formacast Epoxy/polyurethane casting blends Formulated Resins... 

FIGURE 2.2 Monomers can form different shapes of polymer, (a) Randomly coiled linear thermoplastics, e.g. PMMA. (b) Shghdy branched thermoplastics, e.g. PVAC. (c) Highly branched thermoplastics, e.g. polyurethane foam pre-polymer, (d) Cross-hnked polymers with trifunctional junctions, perhaps formed by reaction of (c), e.g. epoxy resin, (e) Cross-linked polymer with tetra-functional junctions, e.g. polyester casting resin. Source Brydson (1982). 

Polyurethane Casting with Synthetic Resin Molds... 

An important development of polymerisation casting is that of reaction injection moulding. Developed primarily for polyurethanes (and discussed further in Chapter 27), the process has also found some use with polyamides and with epoxide resins. 

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