Thermoplast foam-casting

Uses Used in mfg. of thermoplastic and cast elastomers, textile coatings, paints, stmctural foam, adhesives and binders, automotive parts, flexible foams for bedding/upholstery, rigid insulation foams, carpet backing... 

The diverse range of properties which results is variously applied as elastomers, foams, casting compounds, adhesives, sealants, surface and fabric coatings, thermoplastic moulding compounds, to name a selection. 

The Hquid monomers are suitable for bulk polymerization processes. The reaction can be conducted in a mold (casting, reaction injection mol ding), continuously on a conveyor (block and panel foam production), or in an extmder (thermoplastic polyurethane elastomers and engineering thermoplastics). Also, spraying of the monomers onto the surface of suitable substrates provides insulation barriers or cross-linked coatings. 

The market is dominated by flexible foam applications (43% in the United States) and rigid and semi-rigid foam (29%). Cast elastomers (4%) and RIM elastomers (3%) have only specialised outlets. The remaining sizeable 21% of the market cover such diverse uses as thermoplastic rubbers, surface coatings, adhesives, sealants and synthetic leathers. 

Based on the numbers in Figures 1 and 2, by 1985 RIM and RRIM will require approximately 50 M lbs. of monomeric MDI, which is about one-third of the monomeric MDI supply in 1985 (Table IX based on 20-25% of 85% nameplate capacity, excluding ARCO capacity, = 137-171 M lbs. monomeric MDI). This will leave about 100 M lbs. of monomeric MDI for cast elastomers, thermoplastic polyurethanes, shoe soles, semi-rigid foams, and some adhesives and sealants, a monomeric MDI supply which should be more than sufficient for these applications. As RRIM grows, a need for capacity expansion can be seen in the late 1980 s. No effects on the market will be seen from PUR-SMC until after 1985, and at the present time meaningful projections are impossible. 

Castor oil is used in many PU applications such as coatings, cast elastomers, thermoplastic elastomers, rigid foams, semi-rigid foams, sealants, adhesives, flexible foams and so on [29,36,41-43,47, 48]. 

Uses Soft segment or extender in formation of elastomers such as thermoplastic urethanes, polyether esters, polyether amides, coatings, adhesives and sealants, casting resins, and urethane foams Features Resist, to microbial attack, low temp, flexibility and elasticity Properties APHA 50 max. liq. sol. in most org. solvs. and water m.w. 250 sp.gr. 0.991 (40 C) acid no. 0.05 hyd. no. 408.2-498.4 flash pt. 180C 0.03% water... 

Mold release agents are used in a variety of applications, including fiber-reinforced plastics, castings, polyurethane foams and elastomers, injection-molded thermoplastics, vacuum-formed sheets, and extruded profiles. Because each application has its own plastic, mold material, cycle time, temperature, and final product use, there is no universal... 

Foams are versatile both in their applications and in the way in which the materials are made. These include the production of various shapes by casting, extruding, injection molding, thermoforming, and reaction injection molding. Foam versatihty also includes the fact that any plastic material, thermoplastic or thermoset, may be produced in cellular form. 

Solid polyurethane elastomers (as distinct from flexible foams) may be divided into three categories, namely cast, millable and thermoplastic elastomers. 

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). 

Polyurethanes can have the physical structure of a solid casting, a flexible elastomer or soft or rigid foams. It can be either a thermoplastic or more usually it is a thermoset material. The isocyanates in polyurethanes often result in health and safety implications during cure or processing and so must be carefully controlled. 

---