Provided is a curative part usable in a two-part curable composition. The curative part includes a liquid amine; a heterogeneous dispersant; and core-shell rubber particles having an elastomeric core and a (meth)acrylic shell. The core-shell rubber particles and the heterogeneous dispersant can be collectively shear-dispersed in the liquid amine such that the core-shell rubber particles are substantially non-aggregated and the curative part is phase-stable over a period of at least 3 months at ambient temperature. Advantageously, large amounts of core-shell rubber particles can thus be incorporated into a cured resin matrix, which can afford significantly enhanced impact performance.

A curable epoxy composition includes an epoxy resin composition; a hardener composition comprising an aromatic dianhydride curing agent of the formula

##STR00001##

wherein T is O, S, SO.sub.2, SO, C.sub.yH.sub.2y wherein y is an integer from 1 to 5 or a halogenated derivative thereof, or OZO wherein Z is an aromatic C.sub.6-24 monocyclic or polycyclic moiety optionally substituted with 1 to 6 C.sub.1-8 alkyl groups, 1 to 8 halogen atoms, or a combination thereof, and the aromatic dianhydride has a melting point of 220 C. or less; and at least one additional anhydride curing agent different from the aromatic dianhydride curing agent; and 0.1 to 5 wt % of a heterocyclic accelerator, wherein the heterocyclic accelerator comprises a substituted or unsubstituted C.sub.3-6 heterocycle comprising 1 to 4 ring heteroatoms, wherein each heteroatom is nitrogen, oxygen, phosphorus, silicon, or sulfur.

Epoxy curing agents are disclosed having an epoxy curing agent comprising at least one room temperature ionic liquid salt, the room temperature ionic liquid salt being a reaction product of (a) at least one polyalkylene polyamine compound represented by formula (I):

##STR00001##

wherein x, y, and z are integers of 2 and 3, m and n and integers of 1-3; and (b) an organic acid having pKa (the negative of the logarithm of the acid dissociation constant) less than 6. The liquid salt is a stable liquid at a temperature greater than 15 C. Curable epoxy-based compositions including the curing agent and articles formed by the curable epoxy-based compositions are also disclosed.

A resin composition contains an epoxy resin, and a curing agent including a first acid anhydride and a second acid anhydride. An unsaturated bond concentration in the second acid anhydride is not higher than 0.7%. The unsaturated bond concentration is represented by following formula (1). The ratio of the number of acid anhydride equivalents of the first acid anhydride to the number of epoxy equivalents of the epoxy resin is between 0.05 and 0.5 (inclusive). The ratio of the total number of acid anhydride equivalents of the first acid anhydride and the second acid anhydride to the number of epoxy equivalents is between 0.5 and 1.1 (inclusive).
Unsaturated bond concentration={(number of unsaturated bonds per molecule)/(molecular weight)}/(number of acid anhydride groups per molecule)100(1)

The present invention relates to a halogen-free epoxy resin composition, a prepreg, a laminate and a printed circuit board containing the same. The halogen-free epoxy resin composition comprises an epoxy resin and a curing agent. Taking the total equivalent amount of the epoxy groups in the epoxy resin as 1, the active groups in the curing agent which react with the epoxy groups have an equivalent amount of 0.5-0.95. By controlling the equivalent ratio of the epoxy groups in the epoxy resin to the active groups in the curing agent to be 0.5-0.95, the present invention ensures the Df value stability of prepregs under different curing temperature conditions while maintaining a low dielectric constant and a low dielectric loss. The prepregs and laminates prepared from the resin composition have comprehensive performances, such as low dielectric constant, low dielectric loss, excellent flame retardancy, heat resistance, cohesiveness, low water absorption and moisture resistance, and are suitable for use in halogen-free multilayer circuit boards.

A hardener composition is prepared by blending a low intrinsic viscosity hydroxyl-diterminated poly(phenylene ether), and an anhydride having structure (1) where q, R.sup.a, and X are defined herein. The hardener composition exhibits glass transition temperature of 46 to +110 C., which is characteristic of the blend and distinct from the glass transition temperatures of the individual components. Also described are a method of forming the hardener composition, a curable epoxy composition incorporating the hardener composition, a cured composition formed from the curable epoxy composition, and an article that includes the cured composition.

##STR00001##

The present invention provides an epoxy resin composition that can produce a cured product maintaining good dielectric characteristics (low dielectric constant and low dielectric loss tangent), and having high adhesion strength to metal; and also provides a process for producing the same, a cured product obtained by curing the epoxy resin composition, and use thereof. The present invention includes an epoxy resin composition comprising an epoxy resin, an acid anhydride-based curing agent, and a curing accelerator, the epoxy resin being represented by the formula (1):

##STR00001##

wherein X is a divalent group obtained by removing two hydrogen atoms from a hydrocarbon ring, or a divalent group represented by the formula (2):

##STR00002##

wherein Y is a bond, a C.sub.1-6 alkylene group, etc.;

R.sup.1 is the same or different, and is a C.sub.1-18 alkyl group, etc.,

R.sup.2 is the same or different, and is a C.sub.1-18 alkylene group, etc.,

R.sup.3 is the same or different, and is a C.sub.1-18 alkyl group, etc., and

n is the same or different, and is an integer of 0 to 3.

The present invention also includes a process for producing the same, a cured product of the epoxy resin composition, and use thereof.

A resin composition contains a preliminary reaction product obtained through mixing an epoxy resin and a monofunctional acid anhydride as a first curing agent in an equivalence ratio of the epoxy resin to the monofunctional acid anhydride in a range of 1:0.1 to 1:0.6, and reacting the epoxy resin and the monofunctional acid anhydride such that a percentage of ring opening of the monofunctional acid anhydride is 80% or more, and a second curing agent being a different compound from the monofunctional acid anhydride.

A silicone-modified epoxy resin which yields a cured product having low gas permeability and excellent strength; a composition of the silicone-modified epoxy resin; and an epoxy resin cured product obtainable by curing the composition, are provided. An epoxy resin represented by the following Formula (1): ##STR00001## wherein R.sup.1 represents a hydrocarbon group having 1 to 6 carbon atoms; X represents an organic group having a norbornane epoxy structure, or a hydrocarbon group having 1 to 6 carbon atoms; n represents an integer from 1 to 3; plural R.sup.1s and plural Xs present in the formula may be respectively identical or different; and two or more of plural Xs represent an organic group having a norbornane epoxy structure.

The purpose of the present invention is to provide a silicone-modified epoxy resin which produces a cured product having excellent low gas permeability and strength; a composition of the resin; and an epoxy resin cured product obtainable by curing the composition. Disclosed is an epoxy resin represented by the following Formula (1): ##STR00001## wherein R.sup.1 independently represents a monovalent aromatic hydrocarbon group having 6 to 12 carbon atoms; R.sup.2 independently represents a monovalent aliphatic hydrocarbon group having 1 to 12 carbon atoms; R.sup.3 independently represents a monovalent aliphatic hydrocarbon group having 1 to 12 carbon atoms or a monovalent aromatic hydrocarbon group having 6 to 12 carbon atoms; R.sup.4 represents an oxygen atom or a divalent hydrocarbon group having an aliphatic cyclic structure; R.sup.5 represents silicone chain having a norbornane epoxy structure at either end; and X represents an organic group having a norbornane epoxy group.