The novel monobenzoxazines having two propargyl groups were synthesized from various dihydroxyaromatics compound. In a dynamic viscoelasticity test, the glass transition temperatures (T_g) of the cured resin exceeded 350 ° C. In a thermogravimetry test excellent thermal decomposition resistance was observed. The cured resin therefor exhibits excellent physical and chemical properties required by next generation power devices. High levels of chemical and physical heat resistance were confirmed. In addition, this cured product maintained high modulus of elasticity over a wide temperature range. The reasons for the excellent properties of the novel benzoxazine having a propargyl group were considered by examining the relationship between the structure of various dihydroxyaromatics as raw materials and the calculation result of activation energy of bond cleavage of the model structure of each cured product.

Printed wired board is one of the representative application of epoxy resin. In order to reduce fire risk, the printed wired board has been required flame retardancy, and it is achieved using tetrabromobisphenol A as a flame retardant.However, due to the increasing awareness of environmental problems in recent years, the use of halogen-containing flame retardants have been avoided, and halogen-free flame retardants are required. In our previous report, we reported that amidophosphate can be used as a curing agent for epoxy resin, and it is expected that the amidophosphate is useful as a flame retardant. In this report, we investigated the application of the amidophosphate to a flame retardant of epoxy resin. The use of the amidophosphate only could not achive the target flame retardancy. However, the use of the amidophosphate with a commercially available flame retardant achieved very high flame retardancy and high T_g of cured product. We investigated the flame retardant mechanism and found that the amidophosphate contributes to the heat insulating effect by the formation of a char layer, and that the combined commercially available flame retardant contributes to combustion inhibiting effect by the radical trap. It was suggested that the high flame retardancy was achieved by these effects.

Cresol formaldehyde novolac resins (Cre/Form) are used as photo-resist materials because they can be applied minutely onto hard silicon wafers, which are used in the process of making integrated semiconductor circuits. Resins with high hardness cannot be applied minutely onto flexible bases, such as polyimide films. To develop flexible novolac resins for photo-resists, bisphenol A (BisA), which has a bulky isopropylidene group, was incorporated into the molecular backbone chain of novolac resins as a phenolic (PhOH) component. The resulting resins were much more flexible than cresol (Cre) novolac resin. In this study, BisA/BMMB and (BisA/PY)/BMMB novolac resins, where 4,4'-bis(methoxymethyl)biphenyl (BMMB) is as a comonomer and pyrogallol (PY) is added to the PhOH component, were synthesized and investigated. The chain length of BMMB was elongated through a polycondensation reaction confirmed by TOF-MASS measurements. By increasing the BMMB component in the feed, it was observed that the dissolving ratio for alkaline aq. solution (DR) decreased with increasing M_w. The maximum M_w of the BisA/BMMB and (BisA/PY)/BMMB novolac resins were 2000 and 7200, respectively. To prepare cast films, resins meeting the condition of DR below 500Å/s were chosen. Cast films of thickness 5 μm onto the polyimides, were prepared by spin-coating, heat-setting and then exposing to developer solution. The flexibility of the obtained resins were evaluated by observation of the bent parts with microscope. The order of flexibility of the obtained novolac resins was PY/BMMB > (BisA/PY)/BMMB >> BisA/BMMB. The lithographic performance of the novolac resins, coated with a thickness of 1.5 μm onto the silicon wafers was examined. The residual membrane thickness of PY/BMMB novolac resin, which showed the highest flexibility, was 81%. Therefore, (BisA/PY)/BMMB novolac resin showed excellent performance compared to Cre novolac resin, in terms of flexibility and fine drawing ability, in this study. The residual membrane thickness of (BisA/PY)/BMMB novolac resin was high (≒100%) and the resist pattern could draw up to 4 μm clearly.

Following to a previous work, this article takes up several types of phenolic resins which include renewable resources-based type, and functionalized types having heat resistance and low dielectric contant. There are three typical renewable resources actually used as raw material for phenolic resin; one is terpene, another is CNSL (cashew nut shell liquid), and the other is lignin. Phenolic resin, as a curing agent of epoxy resin, has been constantly improved to be imparted with the functions which reflect the technological trends of the time. At the present, better dielectric properties are most needed in the electric and electronic fields. Taking an example of the property improvement, introduction of active ester group to phenolic resin is found to provide superior dielectric properties after curing with epoxy resin. The CAS registration number and the chemical structure of each phenolic resin and its derivatives, are summarized in tabular form similar to the previous review article.