B-stage resin

Bryamycin Bryostatin 1 BSA-SILICA B-stage B-stage resins B. subtilis 66333 BTEPE [37853-59-1]... 

Polymerization is usually carried out by heating in an open aluminum mold in an air-circulating oven. The crystalline monomer melts and, over a period of days, forms a dark green "B-staged" resin, which eventually solidifies into a rubber and finally a glass. 

Many epoxy adhesives are capable of being B-staged. A B-staged resin is one in which a limited reaction between the resin and hardener has taken place so that the product is in a semicured but solid state. In the B-staged state, the polymeric adhesive is still fusible and soluble. On additional heat curing, the adhesive will progress from the B stage to a completely cured state. This will usually be accompanied by moderate flow. 

A B-stage resin is one in which a limited reaction between resin and curing agent is allowed to take place. The reaction is arrested while the product is still fusible and soluble,... 

See B-stage resin C-stage resin novolak phenol-formaldehyde resin. 

B-Stage resin. (resitol). A thermosetting phe-nolformaldehyde-type resin that has been thermally reactive beyond the A stage so that the product has only partial solubility in common solvents (alcohols, ketones) and is not fully fusible even at 150-180C. The B stage resin has limited commercial use. 

Heat reactivation—The use of heat to effect adhesive activity, e.g., hot-melt adhesive completion of the curing process of a B-staged resin. 

Liquid B-stage resin is held in a closed cavity and heated to cross-link it to a rigid solid product This is done in a variety of ways. 

Transfer, or plunger molding, is a process in which high-flow B-stage resins, such as epoxies, are liquefied under heat and pressure in a transfer pot, after which the resultant liquid resin is transferred under pressure into mold cavities. The transferred resin is then heated to form cured, final parts that are then removed from the mold. Although compression and transfer molding are used principally with thermosetting compounds, the processes are occasionally used with thermoplastic material, often thermoplastic composites. 

All the monomers (I, n, IRC, and IVC, see Table 1) were converted to prepolymers before the polymerization process. A typical prepolymer synthesis is as follows In a small reaction vial 2 g of phthalonitrile monomer (IC) was heated above the melting point in air. To the melt was added (0.06 g) 3 wt % of diamine curing agent 4,4 -oxydianiline(ODA) and stirred well for about 3 min. Once the sample became homogeneous, it was quenched to room temperature. The obtained amorphous sohd (B-stage resin) was ground well and used for polymerization (Laskoski et al., 2005). 

Similarities to epoxy resin include no volatile polymerization byproducts stable B-stage resins possible low shrinkage, high adhesion and void free structures. High purity makes cyanate esters very attractive for use in electronic applications. The performance of bisphenol A dicyanate resins in printed wiring board laminates was described by Weirauch et al(4). Mobay Chemical (and Bayer) introduced products of this type for PWB applications in the United States in 1976-78. These "Triazine A resins were not commercially successful and were withdrawn from the market about 1979. 

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