One-shot elastomer

Uses Polyol for adhesives, thermoplastic coatings, thermoplastic urethanes and hot melts, castable and one-shot elastomers, RIM applies. Features Suitable for applies, where reactivity is important Properties APHA 25 color m.w. 2000 sp.gr. 1.058 dens. 8.81 Ib/gal vise. 363 cp acid no. 0.03 hyd. no. 56 pH 6.0. 

Uses Polyol for adhesives, coatings, thermoplastic urethanes and hot melts, castable and one-shot elastomers, potting compds. 

In this chapter, the dramatic effect that monol content or polyol functionality has on processability and properties of polyurethane cast elastomers is discussed. This effect is shown for elastomers prepared by both the prepolymer and one-shot processes. Further improvements in elastomer processability and formulating latitude can be achieved by incorporating oxyethylene moieties into the polyol backbone. For one-shot elastomer processes, ultra-low monol PPG polyols capped with ethylene oxide have been commercialised. 

One-Shot Elastomer System Based on EO-Capped, Ultra-Low Monol PPG Polyols... 

Effect of Primary Hydroxyl Concentration on One-Shot Elastomer Processability... 

The reactivity of PPG polyols can be increased by reacting with EO, which ring opens to form a primary hydroxyl group. A 100% primary hydroxyl content cannot be achieved using this approach since EO has a tendency to form chains instead of distributing evenly to each secondary hydroxyl group however, it is well known that a 100% primary content is not required to achieve one-shot processability. The effect of the primary hydroxyl content on the processability of a one-shot elastomer system is discussed next. 

The hardness build of 80 Shore A, one-shot elastomers based on polyols with primary contents of 80, 87 and 100 percent are shown in Figure 9.6. As expected, the elastomer... 

Figure 9.6 Hardness buildup of 80 Shore A one-shot elastomers (carbodiimide-modified MDI/polyol/BDO)...

Effect of Monol Content on One-Shot Elastomer Processability and Properties... 

The effect of monol content on the processability and properties of one-shot elastomers is shown in Table 9.9. We prepared 80 Shore A elastomers based on carbodiimide-modified MDI and BDO using a 4000-MW, EO-capped, ultra-low monol diol containing 3% monol content and a conventional EO-capped diol containing 15% monol. These polyols had comparable primary hydroxyl concentrations of 87 and 89%, respectively. 

Table 9.11 One-shot elastomers based on ultra-low monol, EO-capped, ...

The 2250-MW (50 OH ) EO-capped, ultra-low monol diol was designed to enhance processability at higher Shore hardnesses. The processability and properties of one-shot elastomers based on this polyol are shown in Table 9.12. One-shot elastomers with excellent processability and properties can be formulated from an 80 Shore A up to about a 55 Shore D. Thus, a broad range of Shore hardnesses (40A to 55D) can be achieved using EO-capped, ultra-low monol polyols. 

Laboratory Casting of One-Shot Elastomers Based on Carbodiimide-Modified MDI, Polyol, and BDO... 

One-shot elastomers were prepared by mixing and reacting three components carbodiimide-modified MDI (CD-MDI), high primary-hydroxyl-content polyol and BDO. The polyol was preheated to 60 °C and degassed under vacuum (130 to 665 Pa). The... 

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