Polymer-Filler Coupling Additives

A method for preparing and covalently bonding either 4-(2-oxazolyl)-phenyl- or methyl-A-phenylnitrone to natural rubber in automotive tires is described. The effect has been a 40% overall reduction in tire hysteresis and superior performance over existing polyamine formulations. 

A solution of 4-formyl-benzoylchloride (1 eq) in 300 ml of CCI3H was added drop wise at — 10°C to a solution of 2-aminoethanol (2 eq), dissolved in 200 ml of CCI3H, and then stirred at 25°C for 2 hours. The mixture was filtered, dried, and concentrated, and 17.4 g of product were isolated as a yellow liquid. 

The Step 1 product (17.4 g) was treated dropwise with 50 ml of 18 M H2SO4 and then heated to 100°C for 60 minutes. The mixture was added dropwise with stirring to 500 ml 20% sodium hydroxide and 500 ml of CCI3H while the solution temperature was kept below 15°C. The organic phase was separated and dried, and 6.3 g of product were isolated. 

A mixture of the Step 2 product (1 eq) and A-phenyl-hydroxyamine (1 eq) was refluxed in 100 ml of ethanol for 30 minutes and then concentrated to 50 ml. The concentrate was treated with 50 ml of water and cooled in a refrigerator to 5°C overnight. White crystals were obtained these were isolated by filtration, dried, and 6.7 g of product were isolated. 

Model Reaction Reactivity of 4-(2-Oxazolyl)-Phenyl-A-Phenylnitrone with Cyclododecene 

---

Y. Fukushima, R.W. Koch, W.L. Hergenrother, and S. Araki, Polymer-filler coupling additives, US Patent 7186845, assigned to Bridgestone Corporation (Tokyo, JP), March 6,2007. 

The term compatibiliser refers to an additive used to improve the miscibility and properties of a polymer blend. It is sometimes more specifically used to mean an additive used to promote adhesion between a polymer and an inorganic smface such as a mineral, or glass fibres. In this report, the coupling agents used to promote adhesion between polymer and inorganic additives are discussed imder the heading of Fillers, and this section concentrates almost entirely on the compatibilisers used to promote the compatibility of two organic polymers. 

The adhesion of filler and polymer can be enhanced by the use of coupling additives. In many industries it is often desirable to produce polymeric compounds in which fillers are well dispersed. For example, in the rubber industry it can be desirable to produce elastomeric compounds exhibiting reduced hysteresis when compounded with other ingredients, such as reinforcing fillers, and then vulcanized (4). 

Various investigations have considered the effects of titanate treatments on melt rheology of filled thermoplastics [17,41]. Figure 10, for example, shows that with polypropylene filled with 50% by weight of calcium carbonate, the inclusion of isopropyl triisostearoyl titanate dispersion aid decreases melt viscosity but increases first normal stress difference. This suggests that the shear flow of the polymer is promoted by the presence of titanate treatment, and is consistent with the view that these additives provide ineffective coupling between filler particles and polymer matrix [42]. 

---