Polymethacrylates (5) containing pendant spiro ortho ester group were prepared by the reaction of ε-caprolactone and the corresponding polyfunctional epoxides (4) with different compositions, which were obtained by radical (co) polymerization of methyl methacrylate and/or glycidyl methacrylate varying the feed ratio. 5 with quantitative introduction of SOE moiety to the polymer side chain were obtained in the presence of BF₃OEt₂ in ca. 50% yield. These polymers were treated with BF₃OEt₂ in refluxing dichloromethane to afford the crosslinked polymers (6) by the double ring-opening of SOE moiety in high yields. To evaluate the volume change during the crosslinking of 5, crosslinking of 4 was also carried out in the same condition to obtain the solvent-insoluble polymers (8) quantitatively. From the determination of densities of 6 and 8, nearly zero volume change (-0.9-+0.5%) were observed during the crosslinking of 6.

View full abstract

Recently, many kinds of epoxy resins containing unique skeleton have been developing and applying in IC molding compound industries. In this work, we developed a epoxy resin containing dicyclopentadiene (DCPD) skeleton. This epoxy resin could present high Tg, low moisture absorption, low dielectric constant and dielectric dissipation factor to its cured resin. So the effects of DCPD skeleton for the properties were studied.
In order to understand the effects of it, cured resins were preparetedat four different amount of DCPD skeleton content. Checking the relationship between DCPD skeleton content and various properties, many interesting results were obtained. As content of DCPD skeleton became higher, Tg of cured resins increased instead of almost same values of cross-linking density, dielectric constant and dielectric dissipation factor decreased. The increase of Tg was caused by larege stiffness and steric hinderance of DCPD skeleton. And electronic properties were known to be depended on molar volume and molar polarization according to Clausius-Mossotti equation. So we investigated they were caused by both of low content of OH group in cured resins with large molecular weight of DCPD skeleton and large bulkiness of it. And low moisture absorption could be explained by both of low content of OH group and low free volume with low cross-linking density.

View full abstract

Mechanical property and water resistance of a UV-cured novel urethane acrylate oligomer (UA), having poly (aliphatic carbonate) unit, were compared with a general polyether type UA. The cured novel UA had excellent flexibility, because of homogenious interaction between urethane and carbonate units, and demonstrated better mechanical and water resistant properties than those of the general UA.

View full abstract

Polyurethanes, obtained from polyisocyanates and compounds having active hydrogen atoms such as polyols, polyamines, etc., are used for manufacturing flexible cellular plastic, elastomers, paints, adhesives, etc. Nowadays, a massive effort is continued for grading up the performance of these polyurethane products through the improvements of the material properties and molding techniques. The environmental protection, on the other hand, has been a task to be globally grappled. With facing to the limitation in using solvent (solvent regulation), the manufacturers of urethane paints are expectantly waiting for the development of new materials. Isocyanates is the key materials to which our attention is to be paind. This article describes the trend in development and new materials expected to come to market.

View full abstract

Thermal shock resistance has been required for epoxide resin, as electrical insulating materials. The thermal shock behavior is a complex phenomena because it is affected by the strength, modulus, thermal conductivity, coefficient of thermal expansion, etc. of the resin. This review describes the thermal shock test of brittle materials. Then the thermal shock test quenching notched disk type specimen which we proposed as simple and easy test method and evaluation method based on fracture mechanics was explained. The improvement in thermal shock resistance by inorganic filler and problem in particle filled resin was also mentioned.

View full abstract

The amine-based hardeners are very important for epoxy resins. Recently, Norbornane diamine (NBDA) attracts many attentions as a new cycloaliphaticdiamine with a norbornane structure in it. Usally, as a hardener, other diamines cannot satisfy both reactivity and weather ability of cured resin simultaneously. And so, suitable diamines are necessary for each purpose. But, NBDA can satisfy these conflict properties simultaneously. For this reason, we can use NBDA in various curing conditions and to get various cured epoxy resin properties.

View full abstract