Provided is an improvement in a method for manufacturing a slit carbon fiber bundle. The method for manufacturing a slit carbon fiber bundle of the present invention is a method including a step of forming a resin film on one surface of a flat carbon fiber bundle to obtain a single-sided coated carbon fiber bundle, and a step of partially slitting the single-sided coated carbon fiber bundle using a slitter roll to obtain a slit carbon fiber bundle, which has been split into sub-bundles, wherein in the step of slitting, the single-sided coated carbon fiber bundle contacts a circumferential surface of the slitter roll on a surface where the resin film has been formed.

Provided is an improvement in a method for manufacturing a slit carbon fiber bundle. The method for manufacturing a slit carbon fiber bundle of the present invention is a method including a step of forming a resin film on one surface of a flat carbon fiber bundle to obtain a single-sided coated carbon fiber bundle, and a step of partially slitting the single-sided coated carbon fiber bundle using a slitter roll to obtain a slit carbon fiber bundle, which has been split into sub-bundles, wherein in the step of slitting, the single-sided coated carbon fiber bundle contacts a circumferential surface of the slitter roll on a surface where the resin film has been formed.

A sizing agent for carbon fibers includes 2 to 30 parts by weight of a resin main agent (A) having at least one epoxy compound, 2 to 30 parts by weight of a resin main agent (B) having at least one acrylate compound, 0.5 to 15 parts by weight of a surfactant (C), 0.01 to 0.5 parts by weight of a hindered phenol agent (D), and a balance of a solvent, in which a particle diameter of the sizing agent is in a range from 0.01 to 0.5 μm.

A sizing agent for carbon fibers includes 2 to 30 parts by weight of a resin main agent (A) having at least one epoxy compound, 2 to 30 parts by weight of a resin main agent (B) having at least one acrylate compound, 0.5 to 15 parts by weight of a surfactant (C), 0.01 to 0.5 parts by weight of a hindered phenol agent (D), and a balance of a solvent, in which a particle diameter of the sizing agent is in a range from 0.01 to 0.5 μm.

Provided is a method for splitting a carbon fiber tow, which comprises heating a carbon fiber tow sized with a first sizing material to soften the first sizing material and form a spread carbon fiber tow; passing the spread carbon fiber tow through at least one splitter and corresponding cutter to obtain multiple carbon fiber strands spaced apart; and sizing the carbon fiber strands with a second sizing material. With the method, multiple small carbon fiber tows having better tensile strength and/or modulus than the commercially available small carbon fiber tow products can be obtained. Products made of the small carbon fiber tows obtained by the present invention are lighter but stronger, and the production cost is relatively reduced. The present invention also achieves the purpose of energy saving and carbon reduction.

Provided is a method for splitting a carbon fiber tow, which comprises heating a carbon fiber tow sized with a first sizing material to soften the first sizing material and form a spread carbon fiber tow; passing the spread carbon fiber tow through at least one splitter and corresponding cutter to obtain multiple carbon fiber strands spaced apart; and sizing the carbon fiber strands with a second sizing material. With the method, multiple small carbon fiber tows having better tensile strength and/or modulus than the commercially available small carbon fiber tow products can be obtained. Products made of the small carbon fiber tows obtained by the present invention are lighter but stronger, and the production cost is relatively reduced. The present invention also achieves the purpose of energy saving and carbon reduction.

In one aspect, the present disclosure provides a nozzle for 3-D printing. The nozzle may include a first nozzle tip defining a first outlet, where the first nozzle tip includes a first channel extending therethrough. The nozzle may further include a second nozzle tip defining a second outlet, where the second nozzle tip includes a second channel extending therethrough, and where the first channel surrounds the second outlet. The second nozzle tip may be retracted longitudinally with respect to the first nozzle tip such that the second outlet of the second nozzle tip is located in the first channel.

A reinforcing material is disclosed that includes coated glass flakes and coated glass strands. When the total amount of a glycidyl group-including resin and aminosilane contained in the coatings of the coated glass flakes corresponds to 100% by mass, the amount of the resin is 30% to 95% by mass. When the total amount of a glycidyl group-including resin, aminosilane, and a urethane resin contained in the coatings of the coated glass strands corresponds to 100% by mass, the amount of the glycidyl group-including resin is 10% to 90% by mass, the amount of the aminosilane is 0.1% to 40% by mass, and the amount of the urethane resin is 1% to 50% by mass. Both the coated glass flakes and the coated glass strands have an ignition loss of 0.1% to 2.0% by mass measured pursuant to JIS R3420 (2013).

A chopped carbon fiber bundle comprising carbon fibers and a sizing agent, the sizing agent including a compound having a maleimide group, the compound having a maleimide group being liquid at 25° C. A method for producing a chopped carbon fiber bundle, the method comprising a step of applying an aqueous dispersion of a secondary sizing agent including a compound having a maleimide group to a long-length carbon fiber bundle including a primary sizing agent deposited thereon, in order to prepare a long-length carbon fiber bundle further including the aqueous dispersion of the secondary sizing agent, and a step of cutting the long-length carbon fiber bundle including the aqueous dispersion of the secondary sizing agent. A chopped carbon fiber bundle that has improved. heat resistance and. feedabli and that is capable of beng produced with high productivity is provided.

The present invention is directed to a reinforced building block made of autoclaved aerated concrete (AAC) comprising rebars formed essentially from A) at least one fibrous carrier and B) and a hardened composition formed from B1) at least one epoxy compound and B2) at least one diamine and/or polyamine in a stoichiometric ratio of the epoxy compound B1) to the diamine and/or polyamine component B2) of 0.8:1 to 2:1, as matrix material, and C) optionally further auxiliaries and additives and to methods of production thereof