The thermal conductivity of the electrical paper insulation could be increased if the paper material is either enriched or fully substituted by a material with higher thermal conductivity. Diamond as enrichment material will be the right choice because besides the high thermal conductivity, it also acts as an excellent electrical insulator and has good mechanical properties. The thermal conductivity of the diamond is k.sub.diamond=2200 [W/mK], that is even more than 7000 times higher than the paper material. Diamond enriched insulation papers have not existed before this invention. In the proposed structure the diamond particles are held in place also by the fibrous substance of the paper itself, without the need of a holding matrix material by default, as shown in FIG. 1. The diamond particles mixed in the paper can also penetrate the paper across creating a thermal bridge between the insulated parts while maintaining strong electrical insulation.

The thermal conductivity of the electrical paper insulation could be increased if the paper material is either enriched or fully substituted by a material with higher thermal conductivity. Diamond as enrichment material will be the right choice because besides the high thermal conductivity, it also acts as an excellent electrical insulator and has good mechanical properties. The thermal conductivity of the diamond is k.sub.diamond=2200 [W/mK], that is even more than 7000 times higher than the paper material. Diamond enriched insulation papers have not existed before this invention. In the proposed structure the diamond particles are held in place also by the fibrous substance of the paper itself, without the need of a holding matrix material by default, as shown in FIG. 1. The diamond particles mixed in the paper can also penetrate the paper across creating a thermal bridge between the insulated parts while maintaining strong electrical insulation.

A flame-blocking nonwoven fabric has excellent processability and high flame-blocking properties. The flame-blocking nonwoven fabric has a density of 200 kg/m.sup.3 or more and includes non-melting fibers A whose high-temperature shrinkage rate is 3% or less and whose Young's modulus multiplied by the cross-sectional area of the fibers is 2.0 N or less, and thermoplastic fibers B whose LOI value is 25 or more as determined according to JIS K 7201-2 (2007).

A flame-blocking nonwoven fabric has excellent processability and high flame-blocking properties. The flame-blocking nonwoven fabric has a density of 200 kg/m.sup.3 or more and includes non-melting fibers A whose high-temperature shrinkage rate is 3% or less and whose Young's modulus multiplied by the cross-sectional area of the fibers is 2.0 N or less, and thermoplastic fibers B whose LOI value is 25 or more as determined according to JIS K 7201-2 (2007).

The present invention provides a preparation method of aramid fiber far-infrared emitting paper. In the present invention, para-aramid chopped fiber and para-aramid pulp fiber are used as paper base functional materials with excellent characteristics of high specific strength and high specific stiffness. In addition, the para-aramid chopped fiber and the para-aramid pulp fiber can form a paper material with pores and porous channels, and carbon nanotubes are embedded into the structural pores and porous channels of the paper material. Therefore, the aramid fiber far-infrared emitting paper has better molding quality and composite performance. Results of embodiments indicate that: A far-infrared wavelength emitted by the aramid fiber far-infrared emitting paper provided in the present invention is 4 μm to 20 μm, a main frequency band thereof is approximately 10 μm, and far-infrared conversion efficiency is up to 99%; and the aramid fiber far-infrared emitting paper has tensile strength of 0.12 KN/mm.sup.2 to 0.18 KN/mm.sup.2, and can be bent and folded.

The present invention provides a preparation method of aramid fiber far-infrared emitting paper. In the present invention, para-aramid chopped fiber and para-aramid pulp fiber are used as paper base functional materials with excellent characteristics of high specific strength and high specific stiffness. In addition, the para-aramid chopped fiber and the para-aramid pulp fiber can form a paper material with pores and porous channels, and carbon nanotubes are embedded into the structural pores and porous channels of the paper material. Therefore, the aramid fiber far-infrared emitting paper has better molding quality and composite performance. Results of embodiments indicate that: A far-infrared wavelength emitted by the aramid fiber far-infrared emitting paper provided in the present invention is 4 μm to 20 μm, a main frequency band thereof is approximately 10 μm, and far-infrared conversion efficiency is up to 99%; and the aramid fiber far-infrared emitting paper has tensile strength of 0.12 KN/mm.sup.2 to 0.18 KN/mm.sup.2, and can be bent and folded.

A method of producing a fibrous web, according to which method a fibrous web is formed of foamed fibre dispersion, by using foam forming. According to the present invention, the foamed fibre dispersion comprises recycled textile fibres and possibly natural fibres or synthetic fibres, or a mixture thereof, in which case, of the fibres in the fibre layer, at least 30% % by weight, in particular at least 50% by weight, is sourced from recycled textile fibres. The present invention generates a product with which it is possible to replace, for example, plastic in bag and package applications. The present product is also suitable, for example, for various textile and furniture applications.

A method of producing a fibrous web, according to which method a fibrous web is formed of foamed fibre dispersion, by using foam forming. According to the present invention, the foamed fibre dispersion comprises recycled textile fibres and possibly natural fibres or synthetic fibres, or a mixture thereof, in which case, of the fibres in the fibre layer, at least 30% % by weight, in particular at least 50% by weight, is sourced from recycled textile fibres. The present invention generates a product with which it is possible to replace, for example, plastic in bag and package applications. The present product is also suitable, for example, for various textile and furniture applications.

A paper suitable for use as a separator paper in electrochemical cells and an electrochemical cell comprising same, the paper comprising as the sole fibrous components 95 to 100 weight percent fibrils and 0 to 5 weight percent aramid fibrids and having a thickness of 10 to 40 micrometers and a tensile strength of at least 15 megapascals or greater, the fibrils comprising a polymer blend of 80 to 96 weight percent polyparaphenylene terephthalamide and 4 to 20 weight percent of polyvinylpyrrolidone; the fibrils having a diameter of 10 to 2000 nanometers, a length of 0.2 to 3 millimeters, a surface area of 3 to 40 square meters/gram, and a Canadian Standard Freeness of 0 to 10 milliliters.

A paper suitable for use as a separator paper in electrochemical cells and an electrochemical cell comprising same, the paper comprising as the sole fibrous components 95 to 100 weight percent fibrils and 0 to 5 weight percent aramid fibrids and having a thickness of 10 to 40 micrometers and a tensile strength of at least 15 megapascals or greater, the fibrils comprising a polymer blend of 80 to 96 weight percent polyparaphenylene terephthalamide and 4 to 20 weight percent of polyvinylpyrrolidone; the fibrils having a diameter of 10 to 2000 nanometers, a length of 0.2 to 3 millimeters, a surface area of 3 to 40 square meters/gram, and a Canadian Standard Freeness of 0 to 10 milliliters.