A prepreg includes; sizing agent-coated carbon fibers coated with a sizing agent; and a thermosetting resin composition impregnated into the sizing agent-coated carbon fibers. The sizing agent includes an aliphatic epoxy compound (A) and an aromatic compound (B) at least containing an aromatic epoxy compound (B1). The thermosetting resin composition includes a thermosetting resin (D) and a latent hardener (E), and optionally includes an additive (F) other than the thermosetting resin (D) and the latent hardener (E). The (a)/(b) ratio is within a predetermined range where (a) is the height of a component at a binding energy assigned to CHx, C—C, and C═C and (b) is the height of a component at a binding energy assigned to C—O in a C.sub.1s core spectrum of the surfaces of the sizing agent-coated carbon fibers analyzed by X-ray photoelectron spectroscopy.

The present invention relates to sizing compositions, glass fibers at least partially coated with sizing compositions, and glass fiber reinforced composite materials. In one embodiment, a sizing composition comprises at least one maleic anhydride copolymer, at least one coupling agent, and a reaction product of an alkoxylated amine and a polycarboxylic acid, which is further reacted with an epoxy compound.

The present invention relates to sizing compositions, glass fibers at least partially coated with sizing compositions, and glass fiber reinforced composite materials. In one embodiment, a sizing composition comprises at least one maleic anhydride copolymer, at least one coupling agent, and a reaction product of an alkoxylated amine and a polycarboxylic acid, which is further reacted with an epoxy compound.

Various embodiments directed towards methods of applying sizing to fibers are disclosed herein. In some embodiments, solvent can be used to dissolve a sizing material into a solution, which can then be used to coat the fibers. In some embodiments, a water bath is used to coagulate a sizing on the fiber surface and to remove the remove solvent after coating the fibers, so that water vapor can be created during a subsequent drying step as opposed to solvent vapors. In some embodiments, strong acids or strong bases can be used as the solvent.

Various embodiments directed towards methods of applying sizing to fibers are disclosed herein. In some embodiments, solvent can be used to dissolve a sizing material into a solution, which can then be used to coat the fibers. In some embodiments, a water bath is used to coagulate a sizing on the fiber surface and to remove the remove solvent after coating the fibers, so that water vapor can be created during a subsequent drying step as opposed to solvent vapors. In some embodiments, strong acids or strong bases can be used as the solvent.

An environment-friendly impregnation solution includes in percentage by weight: 1-15% of blocked isocyanate, 0.5-10% of special amino resin, 10-50% of rubber latex, 1-5% of auxiliaries, and the balance of water, wherein the sum of the weight percentage of each component is 100%. A method for preparing the environment-friendly impregnation solution includes adding blocked isocyanate and auxiliary A into water and stirring uniformly to obtain Composition 1; adding auxiliary B into Composition 1 and stirring uniformly to obtain Composition 2; adding special amino resin into Composition 2 and stirring uniformly, then subjecting the same to grinding to obtain Composition 3; adding rubber latex into Composition 3 and stirring uniformly to obtain the environment-friendly impregnation solution, followed by packaging. The impregnation solution of the invention does not contain toxic and harmful substances such as formaldehyde and resorcinol, and the preparation method thereof is simple.

A 3D printed core-shell filament comprises an elongated core radially surrounded by an outer shell with a barrier layer in between, where the elongated core comprises a ductile polymer and the outer shell comprises a stiff polymer having a Young's modulus higher than that of the ductile polymer. A lightweight lattice structure may comprise a plurality of the 3D printed core-shell filaments deposited in layers.

To provide an opened carbon fibre bundle having a good fibre-opening state and excellent resin impregnation properties. An opened carbon fibre bundle comprising a carbon fibre bundle comprising a plurality of carbon fibres and coated particles arranged between the carbon fibres, wherein the coated particles comprise core particles and a synthetic resin coating that covers at least a part of the surface of the core particles, and the core particles are integrally bonded to the carbon fibre surface via the synthetic resin coating.

Provided is a fiber sizing agent including a vinyl ester resin (A), an epoxy compound (B), and an aqueous medium. The vinyl ester resin (A) has an alkoxy polyoxyalkylene structure and a urethane linkage. The fiber sizing agent exhibits excellent binding ability for various fibers, such as glass fibers and carbon fibers. Molded articles produced from a molding material including the fiber sizing agent have various excellent physical properties, and examples of the physical properties include flexural strength, compressive strength, and interlaminar shear strength. Accordingly, the molded articles can be used, for example, in automotive parts, aircraft parts, windmill parts, industrial parts, and the like.

Provided is a fiber sizing agent including a vinyl ester resin (A), an epoxy compound (B), and an aqueous medium. The vinyl ester resin (A) has an alkoxy polyoxyalkylene structure and a urethane linkage. The fiber sizing agent exhibits excellent binding ability for various fibers, such as glass fibers and carbon fibers. Molded articles produced from a molding material including the fiber sizing agent have various excellent physical properties, and examples of the physical properties include flexural strength, compressive strength, and interlaminar shear strength. Accordingly, the molded articles can be used, for example, in automotive parts, aircraft parts, windmill parts, industrial parts, and the like.