Bisphenol A dicyanate

A mjmber of blends were prepared from a bisbenzocyclobutene monomer (BCB) and various bisdienophiles (Kerimid 353 dicyanates such as bisphenol A dicyanate, tetramethylbisphenol F dicyanate and thiodiphenol dicyanate and bisphenyl-acetylenes ... 

The phase separation behavior during curing of polyetherimide (PEI) modified diglycidyl ether of bisphenol A (DGEBA) epoxy and PEI modified bisphenol A dicyanate (BPACY) were studied using SEM, light scattering, and dynamic mechanical analyzer. 

Diglycidyl ether of bisphenol-A (DGEBA), epoxy resin (YD 128, Kuk Do Chem., Mn = 378), and bisphenol-A dicyanate (BPACY, Arocy B-10, Ciba-Geigy) were used as the thermoset resin. 4,4 -diaminodiphenyl sulfone (DDS, Aldrich Chem. Co.) was used as a curing agent for epoxy. Polyetherimide (PEI, Ultem 1000, General Electric Co., M = 18,000) and 2-methyl imidazole (2MZ, Aldrich Chem. Co.) were used as the thermoplastic modifier and catalyst. 

BPA/DC— Bisphenol A dicyanate 2,2-bis(4-cyanatophenyl)propane BMI — bismaleimide bis(4-maleimidophenyl)methane... 

Aromatic cyanates are synthesized by the condensation of phenols with C1CN and a tertiary amine [1], The most important dicyanate is 2,2-bis(4-cyanatopbenyl) propane or Bisphenol A dicyanate [2] (Scheme 1). 

Difunctional cyanate ester monomers were discovered 30 years ago by Ernst Grigat, an organic chemist now retired from Bayer of Levetkusen, Germany, who was also the first to succeed in making organic cyanate esters at all. Bayer licensed dicyanate/polycyanurate technology to Mitsubishi Gas Chemical Co., Tokyo, and to the then Celanese Corp., New York City. Mitsubishi improved the resin by copolymerization of bisphenol A dicyanate with the bis-(maleimide) of 4,4 -methylenedianiline. 

Some examples of what may be considered as actual thermosetithermoset blends are the epoxy and bismaleimide thermosets modified with aromatic dicyanate esters such as bisphenol A dicyanate. Aromatic cyanates crosslink by cyclotrimerization to form a network of triazine ethers. 

Similar hybrid thermosets consisting of bismaleimide resins mixed with bisphenol A dicyanate ester have been commercially available (BT resin, Mitsubishi gas chemical). The presence of cross-linked triazine ether network in the matrix of bismaleimide crosslinked network is believed to improve the toughness, reduce the moisture sensitivity and improve the dielectric properties of the bismaleimide thermoset without a sacrifice in heat resistance. 

Cyanate/Cyanurate. When aryl cyanate esters are heated to 150 to 250°C, they cyclotrimerize to cyanuric acid esters (Fig. 3.62). They can be catalyzed by organo-metallic and active hydrogen compounds. When the monomer is a dicyanate such as bisphenol A dicyanate (Fig. 3.63), the result is a highly cross-linked heterocyclic polymer (Table 3.57). Using a novolac polycyanate has produced Tg and useful life over 300°C. 

Hwang et al. (1997) have investigated mixtures of polysulfone with bisphenol A dicyanate, the stmcture of which is shown in Fig. 16.7. 

Thus, several properties of the common bisphenol A-diglycidyl ether-based epoxy thermosets can be improved by cocuring with a commercial bisphenol A-dicyanate ester, and the blend is more cost-effective than the cyanate ester alone. Such epoxy/cyanate ester thermoset blends exhibit improvements in processability, toughness, hot-wet performance, and low dielectric properties. 

The predominant curing pathway for cyanate ester is via cyclotrimerization using metal coordination catalysts. Three types of metal coordination catalysts are used metal naphthenates, metal acetylacetonates (AcAc), and metal octoates. Of these, Cu AcAc and Mn octoate are the most popular. Nonylphenol is also required as a cocatalyst. Reaction 5 shows the cyclotrimerization reaction of bisphenol A dicyanate to form the triazine network structure ... 

Aryl cyanate esters such as bisphenol A dicyanate can be processed much like epoxy resins for many applications. This may be implied by comparing the monomer structure of bisphenol A diglycidyl ether to bisphenol A dicyanate. 

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. 

Mitsubishi Gas Chemical (7) has developed a family of products which are stated to be a coreactive blend of triazine resin (terminology used to describe bisphenol A dicyanate and its prepolymers) and a bismaleimide resin. Properties of these resins are described in patents (8) and product literature (7). End uses suggested include electronic encapsulation, printed wiring board and structural composites. 

Polycyanurate network was modified with hydroxyl-terminated polyester, poly(butylene glycol adipate), PBGA, by polycyclotrimerization of bisphenol A dicyanate in the immediate presence of PBGA [18]. The modified networks with PBGA content from 5 to 20 wt. % were characterized by a combination of FTIR, DSC, TMA, TGA, impact testing and sol-gel analysis. It has been established that almost the whole PBGA was chemically incorporated into the PCN structure. It is supposed that the chemistry of such incorporation is the same as that shown in Figure 2. 

Fainleib A, Grigoryeva 0, Hourston D. Synthesis of inhomogeneous modified polycyanurates by reactive blending of bisphenol A dicyanate ester and polyoxypropylene glycol. Macromol. Symp., 164, 429-442 (2001). 

Bershtein VA, Egorova LM, Ryzhov VP, Yakushev PN, Fainleib AM, Shantalii TA and Pissis P (2001) Structure and segmental dynamics heterogeneity in hybrid polycyanurate-polyurethane networks, JMacromol Sci Phys, B 40 105-131. Srichatrapimuk V.W.and Cooper S.L.,. J. Macromol. Sci.-Phys., B15, 267 (1978). Bellamy LJ. The Infra-Red Spectra of Complex Molecules. Wiley, New York, 1954. Vilensky V A, Fainleib A M, Goncharenko L A and Danilenko I Yu (2002) Influenee of inclusion polymer and components thermodynamic affinity on bisphenol A dicyanate ester polycyclotrimerization. Reports of the National Academy of Sciences of Ukrainem-. A2- A%. 

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