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.

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.

The invention relates to an insulation element (1) with low electrical conductivity for the electrical insulation of an electrotechnical component in the high voltage range. The insulation element (1) comprises artificial fibres (2) and electrically conductive particles (3) having an electrically non-conductive core (5) and an electrically conductive or semi-conductive cladding (6) surrounding the core (5). Moreover, the insulation element (1) comprises a cationic polymer (4).

The invention relates to an insulation element (1) with low electrical conductivity for the electrical insulation of an electrotechnical component in the high voltage range. The insulation element (1) comprises artificial fibres (2) and electrically conductive particles (3) having an electrically non-conductive core (5) and an electrically conductive or semi-conductive cladding (6) surrounding the core (5). Moreover, the insulation element (1) comprises a cationic polymer (4).

The disclosure relates to a curable mixture, in particular for use in impregnation of paper bushings, comprising (a) a resin composition comprising a bisphenol-A-diglycidylether; a polyglycidylether different from BADGE and/or a cycloaliphatic epoxy resin; a N-glycidyl component; a nano-size or dissolvable toughener; and a silane component, and b) a hardener composition comprising methyltetrahydrophthalic anhydride (MTHPA) and at least one curing accelerator as well as paper bushings impregnated with such mixture and uses of such mixture.

The disclosure relates to a curable mixture, in particular for use in impregnation of paper bushings, comprising (a) a resin composition comprising a bisphenol-A-diglycidylether; a polyglycidylether different from BADGE and/or a cycloaliphatic epoxy resin; a N-glycidyl component; a nano-size or dissolvable toughener; and a silane component, and b) a hardener composition comprising methyltetrahydrophthalic anhydride (MTHPA) and at least one curing accelerator as well as paper bushings impregnated with such mixture and uses of such mixture.

An aramid-based paper comprising at least 90 wt. % of aramid material, the aramid material including at least one of aramid shortcut and aramid fibrid, the paper including at most 40 wt. % aramid pulp, calculated on the total amount of aramid material, wherein the paper includes 0.1-10 wt. % of polyamido-amine epichlorohydrin (PAE). It has been found that the incorporation of 0.1-10 wt. % of polyamido-amine epichlorohydrin (PAE) into an aramid-based paper including at least 90 wt. % of aramid material calculated on the weight of the paper not including the PAE, the aramid material including at least one of aramid shortcut and aramid fibrid, the paper including at most 40 wt. % aramid pulp, leads to a surprising improvement of the z-strength and the tear strength of the paper.

An electrical device including a cellulose based electrically insulating composite material in the form of a paper or pressboard, the composite material having cellulose fibres; and an electrically insulating thermoplastic polymer material; wherein the polymer material is arranged around and between the cellulose fibres, and binds the fibres to each other.

An electrical device including a cellulose based electrically insulating composite material in the form of a paper or pressboard, the composite material having cellulose fibres; and an electrically insulating thermoplastic polymer material; wherein the polymer material is arranged around and between the cellulose fibres, and binds the fibres to each other.