摘要:
Epoxy-terminated polyoxazolidone having from about 5 to about 30 weight percent of the isocyanate content are described. These polyoxazolidone are prepared by a process in which various process parameters are controlled in a targeted manner to give a product having from about 50 to about 100 percent of isocyanate groups converted to oxazolidone rings and from about 0 to about 50 percent of the isocyanate groups converted to isocyanurate rings. These epoxy terminated polyoxazolidones exhibit high glass transition temperatures and high resistance to chemicals when cured. They are useful for the preparation of electrical laminates, particularly laminates used in the preparation of electrical circuit boards.
摘要:
Epoxy resins containing both terminal hydroxyl groups and epoxy or epoxy-derived groups are prepared by advancing a polyepoxide with a polyol and terminating the reaction at a point such that the epoxy resin reaction product contains both epoxy and terminal hydroxyl groups. The controlled conversion resins have improved cure rates. The epoxy groups can be further reacted to form epoxy-derived groups to improve the cure rate even further. The epoxy resins exhibit lower melt and solution viscosities than those exhibited by conventional epoxy resins having the same epoxy equivalent weight, as well as curing quickly when used. The resins are usefully employed at high solids levels in can coating formulations and other epoxy formulations wherein the resin is applied from an organic liquid solution or aqueous dispersion.
摘要:
A method of preparing epoxy parts wherein the interval of low viscosity of an amine-hardened epoxy system can be extended without sacrifice of cure time. Suitable catalysts for the epoxy-amine hardener reaction are generated in situ. As an advantage, more epoxy articles may be prepared with a given mold capacity having improved wet-out of fiber reinforcement attributed to a larger interval of low viscosity.
摘要:
Epoxy resins of increased functionality are prepared by branching the epoxy resin in the presence of a lithium or cesium compound as a branching catalyst until the desired functionality is obtained and thereafter terminating the branching reaction. Since the lithium and cesium compounds are not deactivated by the aliphatic chloride typically found in an epoxy resin, the branching reaction can effectively be conducted even at low concentrations of the lithium or cesium compound. Termination of the branching reaction is conducted by cooling the branching reaction mixture or by the addition of a deactivating agent which stops or effectively reduces the rate of the branching reaction. Due to the low conecntration at which the branching catlayst can be employed, the resulting branched epoxy resins can be prepared without visible turbidity.
摘要:
Epoxy resins of increased functionality are prepared by branching the epoxy resin in the presence of a lithium or cesium compound as a branching catalyst until the desired functionality is obtained and thereafter terminating the branching reaction. Since the lithium and cesium compounds are not deactivated by the aliphatic chloride typically found in an epoxy resin, the branching reaction can effectively be conducted even at low concentrations of the lithium or cesium compound. Termination of the branching reaction is conducted by cooling the branching reaction mixture or by the addition of a deactivating agent which stops or effectively reduces the rate of the branching reaction. Due to the low concentration at which the branching catalyst can be employed, the resulting branched epoxy resins can be prepared without visible turbidity.
摘要:
A flame retardant epoxy resin composition containing not more than 10% by wgt. of halogen, comprising an epoxy resin, stated concentrations of phosphoric acid ester, nitrogen—containing cross-linking agent having an amine functionality of at least 2 and a catalyst capable of promoting the reaction of the phosphoric acid ester with the epoxy resin and promoting the curing of the epoxy resin with the cross-linker, and optionally a Lewis acid in a stated amount.