Bis-maleimide resin

In the narrow sense, bis-maleimide resin means the thermosetting resin eom-posed of the bis-maleimide of methylene dianiline (BMI, bis(4-maleimidophenyl)-methane) and methylene dianiline (MDA, bis(4-aminophenyl)methane) (Fig. 1). Beeause of the addition meehanism, the resin is eured without elimination, whieh is a eharacteristic of this resin. Bis-maleimide resin is used as a thermally stable matrix up to 204°C (400 F) whieh typical epoxy resins may not normally be used. However, in spite of having an imide structure, bis-maleimides are classified as being moderately thermally stable resins. The aliphatic structure of the resin is not stable for long periods above 232°C (450°F.) If a highly aromatic thermally stable thermosetting resin is necessary, acetylene end-capped aromatic imide-based oligomers should be used. 

Bis-maleimide resins composed of BMI and diamines have been reported in the early 1960s in the patent literature. Since that time, a number of patents have appeared describing improvements in their properties and uses [3]. Although many bis-maleimide resins are commercially developed, relatively few reports of their use as adhesives are to be found in scientific journals [4-10]. Improvements of maleimide resins are mirrored in the improvements of thermosetting polyimides. For example, the method of in situ polymerization of monomer reactants (PMR method) was developed [6]. 

To improve upon their inherent brittleness, bis-maleimide resins are often mixed with other eompounds and materials. Glass fabrie and earbon fiber fabrie are immersed in uncured maleimide resin and plied are layed up, followed by... 

The most common thermosetting PI resins are bis(maleimide) resins. A wide variety of these resins is known. Commercially available bismale-imide thermoset compositions are well known for their high modulus, and excellent resistance to thermal degradation. 

BMI also reacts with dienes to form Diels-Alder adducts [12]. When BMI reacts with a a,(n-biscyclopentadienyl compound or other bis-diene resin, the bis-maleimide chain is extended by the Diels-Alder reaction. Bis-maleimide, chain extended with bis-diene, is not used in adhesives. However, as the Diels-Alder reaction is reversible, there may be a possibility of recyclability of the cured resin by depolymerization of the backbone (Fig. 6). 

One can vary the chemical composition of the bis-maleimide system by replacing tbe MDA with other diamines. The nature of the resin is not that different from that using MDA because the resins are so highly crosslinked. Based upon availability, ease of use and cost, BMI and MDA are most often used. However, one commercial maleimide resin, Techocbemie s Compimide H795 has an original structure. As shown in Fig. 8, it is composed of BMI and / -aminobenzoyl hydrazide [10]. 

Bis(maleimides) have been nsefnl in many applications, including the electronic indns-tries, as materials for printed circnit boards and insulators, and in the aerospace industries in matrix resins for strnctnral composites. Alternative polyimide systems have been investigated which are formed via the free-radical polymerization of the maleimide ring. 

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. 

Alkyd resins Amino resins Epoxy resins Phenolic resins Poly(bis maleimide)... 

Thermo set polymers Alkyd resins Amino resins Epoxy resins Phenolic resins Poly(bis maleimide) Polyesters, unsaturated Thermoset resin Tohprene TOR Torelina Torlon TP 301 TPX... 

Epoxy and filled epoxy Silicones and filled silicones Bis-maleimide triazine (BT) resin BT-Epoxy E-glass laminate Epoxy-E-glass laminate Polyimide-E-glass laminate Poly(tetrafluoroethylene)-E-glass laminate Polyimide-E-glass laminate Polyester film Polyimide film... 

Cyanate Ester Blends. The second most stable resin system is the triazine or cyanate ester family. In its pure form, the cyanate ester resin is brittle and is difficult to drill without cracking. Low peel strengths are typically associated with its use. In addition, cyanate ester is an expensive resin system. As a result, cyanate ester resin is often blended with epoxy and a small amount of polyimide. This blend, called BT (after its two ingredients, bis-maleimide and triazine), can be coated on conventional glass cloth to produce a laminate. 

A variety of specialty resins with increased Tg is available, albeit at higher prices. Modified FR-4 materials with higher functionality offer the best combination of improved Tg at a reasonable price. Further improvements in Tg and other characteristics can be obtained with bis-maleimide triazine (BT), GETEK, cyanate ester, and polyimide, but at greater price penalties. 

The resins used were isophthalic polyester phenolic epoxy bis-maleimide and several thermoplastics - PES, PEEK (ICI) and PPS (Phillips Petroleum). 

Another original approach is exemplified by Ciba-Geigy s XU292. BMI is mixed with o,o -diallylbisphenol A (DAP, 2,2-bis(3-allyl-4-hydroxyphenyl)pro-pane Fig. 9) followed by heating to 110-125°C to obtain a liquid pre-polymer. The pre-polymer could be cured in the same way as common maleimide and epoxy resins are done [ 16,17]. 

The maleimide group can undergo a variety of chemical reactions. The reactivity of the double bond is a consequence of the electron withdrawing nature of the two adjacent carbonyl groups which create a very electron-deficient double bond, and therefore is susceptible to homo- and copolymerizations. Such polymerizations may be induced by free radicals or anions. Nucleophiles such as primary and secondary amines, phenates, thiophenates, carboxylates, etc. may react via the classical Michael addition mechanism. The maleimide group furthermore is a very reactive dienophile and can therefore be employed in a variety of Diels Alder reactions. Bisdienes such as divinylbenzene, bis(vinylbenzyl) compounds, bis(propenylphenoxy) compounds and bis(benzocyclobutenes) are very attractive Diels Alder comonomers and therefore some are used as constituents for BMI resin formulations. An important chemical reaction of the maleimide group is the ENE reaction with allylphenyl compounds. The most attractive comonomer of this family is DABA particularly when tough bismaleimide resins are desired. 

Amino and functional aromatic phosphates, phosphonates, and phosphine oxides have also been used as reactive components to impart flame retardancy to cured epoxy resins. Phosphine oxides are particularly hydrolytically stable and several studies have been reported, for example, of the curing of epoxy resins with bis(aminophenyl) alkyl and aryl phosphine oxides65-67 (Structure 5.19). The relative performances of epoxies cured with aromatic diamine hardeners containing phosphine oxide, phosphinate, phosphonate, or phosphate units have recently been assessed.68 Aromatic phosphine oxides have been functionalized also with maleimide and hydroxyl groups for use as epoxy resin hardeners.69,70... 

A binder for copper clad laminates contains the prepolymer from BPA/DC and A -(3,5-dimethyl-4-vinylphenyl)maleimide in methylethylketone, an epoxynovolak resin, Zn acetate and tert.butyl peroxide [100], In a similar composition, a prepolymer obtained from epoxide resin, BMI and bis(4-aminophenyl)methane was mixed with BPA/DC, Zn acetate and tert.butyl peroxide in solution [101]. 

A new type of bismaleimide resin containing a P-heterocyclic unit was prepared by the reaction of a bis(epoxide) and two units of A-(4-carboxylphenyl)maleimide to make available a new flame retardant (Scheme 51). ... 

Tg measurements have been performed on many other polymers and copolymers including phenol bark resins [71], PS [72-74], p-nitrobenzene substituted polymethacrylates [75], PC [76], polyimines [77], polyurethanes (PU) [78], Novolac resins [71], polyisoprene, polybutadiene, polychloroprene, nitrile rubber, ethylene-propylene-diene terpolymer and butyl rubber [79], bisphenol-A epoxy diacrylate-trimethylolpropane triacrylate [80], mono and dipolyphosphazenes [81], polyethylene glycol-polylactic acid entrapment polymers [82], polyether nitrile copolymers [83], polyacrylate-polyoxyethylene grafts [84], Novolak type thermosets [71], polyester carbonates [85], polyethylene naphthalene, 2,6, dicarboxylate [86], PET-polyethylene 2,6-naphthalone carboxylate blends [87], a-phenyl substituted aromatic-aliphatic polyamides [88], sodium acrylate-methyl methacrylate multiblock copolymers [89], telechelic sulfonate polyester ionomers [90], aromatic polyamides [91], polyimides [91], 4,4"-bis(4-oxyphenoxy)benzophenone diglycidyl ether - 3,4 epoxycyclohexyl methyl 3,4 epoxy cyclohexane carboxylate blends [92], PET [93], polyhydroxybutyrate [94], polyetherimides [95], macrocyclic aromatic disulfide oligomers [96], acrylics [97], PU urea elastomers [97], glass reinforced epoxy resin composites [98], PVOH [99], polymethyl methacrylate-N-phenyl maleimide, styrene copolymers [100], chiral... 

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