An aramid paper suitable for use in electronic applications which has a density of 0.20-0.65 g/cm3 and a grammage of 30-280 g/m2, which paper comprises 10-40 wt. % of aramid shortcut with a linear density of 2.6 dtex or lower and a length of 0.5-25 mm and 10-90 wt. % of aramid fibrid, wherein the aramid shortcut comprises at least 70 wt. % para-aramid shortcut and the aramid fibrid including at least 70 wt. % para-aramid fibrid. It has been found that the use of a paper with the above properties in electronic applications ensures a low CTE in combination with good homogeneity and a good dimensional stability resulting from good resin adhesion and penetration. Use of the aramid paper in a composite sheet including at least one layer of aramid paper and a resin, or in a substrate board for electronic applications.

Disclosed is a method for producing roll-type gas diffusion layer. The method includes steps of preparing a carbon paper by using carbon fiber chops having a low modulus of 10 to 100 Gpa; impregnating the prepared carbon paper with a phenol resin or the like, and then carbonizing the same at 1,800 to 2,400 C.; forming a microporous polytetrafluoroethylene resin layer on one of both sides of the carbonized carbon paper, thus to prepare a sheet-like gas diffusion layer; and then, winding the prepared sheet-like gas diffusion layer on a roll.

A friction paper including filler, para-aramid pulp, and resin, characterised in that the para-aramid pulp includes 0.1 to 10 wt. % of polyvinyl pyrrolidone (PVP), the paper having a grammage in the range of 100 to 800 g/m2. It has been found that the use of a PVP-containing para-aramid pulp leads to improved friction performance as compared to the use of para-aramid pulp not containing PVP. Effects obtained include improved friction properties, improved strength properties, and improved filler retention.

A friction paper including filler, para-aramid pulp, and resin, characterised in that the para-aramid pulp includes 0.1 to 10 wt. % of polyvinyl pyrrolidone (PVP), the paper having a grammage in the range of 100 to 800 g/m2. It has been found that the use of a PVP-containing para-aramid pulp leads to improved friction performance as compared to the use of para-aramid pulp not containing PVP. Effects obtained include improved friction properties, improved strength properties, and improved filler retention.

A method for manufacturing a carbon fiber sheet, the method including a carbon fiber forming step of heating a resin sheet to a carbonization temperature at a heating rate of 15,000 C./sec or higher, thereby forming a carbon fiber from the resin sheet. In the carbon fiber forming step, the resin sheet is preferably irradiated with an energy ray having an output density of 130 W/mm.sup.2 or higher and an amount of irradiation energy of 0.05 J/mm.sup.2 or more.

A porous base material and a porous electrode having both gas permeability suitable for a gas diffusion layer for a fuel cell vehicle and mechanical strength capable of withstanding continuous processing in a roll-to-roll manner, and a porous electrode which is suitable for an electrode for a redox flow cell and has excellent diffusibility of an electrolyte are required. Provided is a porous base material containing a carbon fiber (A) having an average fiber diameter of 10 to 20 m, an average fiber length of 2 to 30 mm, a tensile modulus of elasticity of 200 to 600 GPa, and a tensile strength of 3,000 to 7,000 MPa and a carbon binder (D), in which the carbon fiber (A) is bound with the carbon binder (D).

A porous base material and a porous electrode having both gas permeability suitable for a gas diffusion layer for a fuel cell vehicle and mechanical strength capable of withstanding continuous processing in a roll-to-roll manner, and a porous electrode which is suitable for an electrode for a redox flow cell and has excellent diffusibility of an electrolyte are required. Provided is a porous base material containing a carbon fiber (A) having an average fiber diameter of 10 to 20 m, an average fiber length of 2 to 30 mm, a tensile modulus of elasticity of 200 to 600 GPa, and a tensile strength of 3,000 to 7,000 MPa and a carbon binder (D), in which the carbon fiber (A) is bound with the carbon binder (D).

A method for manufacturing a printing paper for decorative boards is provided. The method includes the processes of: applying a resin-containing liquid comprising at least one of a resin and a resin precursor to a base paper for decorative boards; forming a print layer on or in the base paper which is not dried after the resin-containing liquid is applied thereto; and solidifying a liquid contained in the base paper having the print layer.

Provided is a flame-retardant sheet-forming body containing a matrix resin, a flame-retardant fiber, and a metal hydroxide. The content of the metal hydroxide in the flame-retardant sheet-forming body is 1 to 20% by weight with respect to the total weight of the flame-retardant sheet-forming body. In addition, the flame-retardant fiber in the flame-retardant sheet-forming body is preferably at least one of an aramid fiber, a pitch-based carbon fiber, and a BPO fiber.

A preparation method of tea residue fiber raw materials includes steps of (1) sun-drying tea residues, crushing the sun dried tea residues, and treating them with concentrated hydrochloric acid and a strong base in succession; (2) extracting water from the treated tea residues to obtain tea polyphenols and pulp respectively, cooking the pulp, and then pressing and dehydrating it to obtain coarse pulp; (3) sequentially grinding and sieving the pulp, and beating it; and (4) adding -cyclodextrin, carboxymethylcellulose sodium, and reinforced starch after the beating, adjusting the pH to 7-8, diluting, adding the tea polyphenols obtained in the second step, stirring uniformly, pressing and dehydrating, and drying to obtain the tea residue fiber raw material.