Nyrim

Nyrim Nylon Block Copolymers, NY-01-01, Monsanto Co., St. Louis, Mo. 

This process, commonly used with thermosets, is sometimes used for specific thermoplastics such as monomers or pre-polymers of PMMA or polyamide (Nyrim). For the latter, a mix is made just before casting with ... 

Nylon block copolymers were previously synthesized from the anionic polymerization of caprolactam in the presence of polyurethane prepolymers. (11) The prepolymers, prepared from the reaction of diisocyanates with polyether glycols, contained Isocyanate end groups which initiated caprolactam polymerization. Sodium caprolactam was used to catalyze the reaction. This copolymer system is the basis for some current areas of nylon 6 RIM research. (12) NYRIM nylon block copolymers are formed from stoichiometric mixtures of polymeric polyols and caprolactam using poly acyllactam initiation which was described previously. The reactions are as follows ... 

The alkaline catalyst systems used for caprolactam polymerization are suitable for both the prepolymer and copolymerization reactions. The preferred catalyst Is caprolactam magnesium bromide, prepared by reaction of Grignard reagent with caprolactam. With NYRIM copolymers, a two-package system Is used—reactive prepolymer and catalyst concentrate. These are dissolved in caprolactam to make up the two reactive streams. 

This longer time is also a result of the very low heat of reaction of caprolactam, only 3-4 Kcai/mole versus 18-20 kcal/mole for urethanes. A typical reaction exotherm is shown in Figure 11 for NYRIM 2000 nylon block copolymer. 

Figure 10. Viscosity of urethane and NYRIM raw material streams.

Figure 11. In-mold reactant temperature during cure of a part made from NYRIM 2000.

NBC (Nyrim) is more expensive than RIM polyurethane but it may be heated to 200°C without softening. NBC moldings are produced by the reaction injection molding (RIM) of polypropylene glycol and caprolactam in the presence of a catalyst. The tendency for this copolymer to swell in the presence of water is reduced by reinforcing with glass fibers. 

Monomeric and oligomeric forms of caprolactam modified with a compatible elastomer (such as butadiene) and usually glass-fibre-reinforced, can be conveniently processed using reaction injection moulding equipment to produce block copolymers of PA 6, (e.g. Dutch State Mines Nyrim ). Applications include panels for the underside of snowmobiles. 

Essentially, the process shows dose similarities to polyurethane and polyurea RIM. Therefore, the machinery developed for these latter polymers and well known in the industrial practice can be readily adapted to NyRIM. The specific requirements of the RIM process applied to CL anionic polymerization have been summarized by Macosko in terms of unit operations. The initiators typically used are sodium c-caprolactamate or magnesium bromide c-caprolactamate. 

Both systems have similar extent of side reactions in other words, they are not decreased substantially by CLMgBr [20]. However, the result of a polymerization in the presence of 20% a,co-dibenzamidopoly(propylene oxide) (the model of Nyrim block-copolymer preparations see the last two Unes in Table 7.2) was surprising with, in the case of CLMgBr, the polyether present unexpectedly suppressing the side reactions. Thus, the data provided by others [25] represent a classical... 

The Nyrim technology was the first successfiil process to produce block copolymers, namely, poly(E-caprolactam)-blodk-polyether [53]. The OH end-groups of the prepolymer are transformed to the growth centers through an alcoholysis of bis(acyllactams) (Scheme 7.3). 

Scheme 7.3 Preparation of block copolymers of lactams the Nyrim process.

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