A method for producing a wet-running friction paper includes providing a fiber portion with a fiber, providing a filler portion with a filler, providing a binder portion with a phenol-resin-based binder, dissolving the binder portion to form a phenolate, and processing the fiber portion, the filler portion and the phenolate in a paper production process to form the wet-running friction paper.

A method of preparing an aramid paper coated with aramid nanofibers includes the following steps: (1) mixing a meta-aramid fibrid slurry and a chopped meta-aramid fiber slurry, filtering, pressing and drying to obtain a meta-aramid paper; (2) mixing potassium hydroxide, deionized water, dimethyl sulfoxide, and para-aramid nanofibers in a container, and stirring to obtain a para-aramid nanofiber coating solution; and (3) applying the para-aramid nanofiber coating solution to a first side of the meta-aramid paper, washing with deionized water, and drying; applying the para-aramid nanofiber coating solution to a second side of the meta-aramid paper, washing with deionized water, and drying; and hot pressing to obtain the aramid paper coated with aramid nanofibers.

A method of preparing an aramid paper coated with aramid nanofibers includes the following steps: (1) mixing a meta-aramid fibrid slurry and a chopped meta-aramid fiber slurry, filtering, pressing and drying to obtain a meta-aramid paper; (2) mixing potassium hydroxide, deionized water, dimethyl sulfoxide, and para-aramid nanofibers in a container, and stirring to obtain a para-aramid nanofiber coating solution; and (3) applying the para-aramid nanofiber coating solution to a first side of the meta-aramid paper, washing with deionized water, and drying; applying the para-aramid nanofiber coating solution to a second side of the meta-aramid paper, washing with deionized water, and drying; and hot pressing to obtain the aramid paper coated with aramid nanofibers.

A sheet comprises a nonwoven filamentary substrate and an inorganic refractory layer in contact with at least one surface of the substrate wherein (i) the substrate comprises from 40 to 80 weight percent of uniformly distributed mica and from 20 to 60 weight percent aramid material, the aramid material being in the form of aramid floc or pulp, a combination thereof and polymeric binder and (ii) the refractory layer comprises from 85 to 99 weight percent of platelets and from 1 to 15 weight percent of an adhesion promoter. The sheet is an electrically insulating flame and thermal barrier.

A sheet comprises a nonwoven filamentary substrate and an inorganic refractory layer in contact with at least one surface of the substrate wherein (i) the substrate comprises from 40 to 80 weight percent of uniformly distributed mica and from 20 to 60 weight percent aramid material, the aramid material being in the form of aramid floc or pulp, a combination thereof and polymeric binder and (ii) the refractory layer comprises from 85 to 99 weight percent of platelets and from 1 to 15 weight percent of an adhesion promoter. The sheet is an electrically insulating flame and thermal barrier.

The present invention provides aramid compound paper with a pinning effect and a preparation method for the aramid compound paper. The preparation method for the aramid compound paper includes the following steps: preparing aramid paper from polyphenylene sulfide meltblown superfine fibers and aramid chopped fibers with wet papermaking; then placing polyphenylene sulfide meltblown superfine fiber non-woven fabrics on two sides of aramid base paper as face layers respectively; embedding the polyphenylene sulfide superfine fibers on the face layers into pores of the aramid paper at a middle layer by using a hot-pressing technology to be fusion-joined to the polyphenylene sulfide super-short fibers which are uniformly dispersed in the aramid base paper, so as to form the pinning effect; and meanwhile, melting and then solidifying the polyphenylene sulfide superfine fibers between the aramid chopped fibers to form a continuous network, and firmly bonding the aramid chopped fibers.

The present invention provides aramid compound paper with a pinning effect and a preparation method for the aramid compound paper. The preparation method for the aramid compound paper includes the following steps: preparing aramid paper from polyphenylene sulfide meltblown superfine fibers and aramid chopped fibers with wet papermaking; then placing polyphenylene sulfide meltblown superfine fiber non-woven fabrics on two sides of aramid base paper as face layers respectively; embedding the polyphenylene sulfide superfine fibers on the face layers into pores of the aramid paper at a middle layer by using a hot-pressing technology to be fusion-joined to the polyphenylene sulfide super-short fibers which are uniformly dispersed in the aramid base paper, so as to form the pinning effect; and meanwhile, melting and then solidifying the polyphenylene sulfide superfine fibers between the aramid chopped fibers to form a continuous network, and firmly bonding the aramid chopped fibers.

A nanofiber nonwoven product is disclosed which comprises a polyamide with a relative viscosity from 2 to 330, spun into nanofibers with an average diameter of less than 1000 nanometers (1 micron). In general, the inventive products are prepared by: (a) providing a polyamide composition, wherein the polyamide has a relative viscosity from 2 to 330; (b) melt spinning the polyamide composition into a plurality of nanofibers having an average fiber diameter of less than 1 micron, followed by (c) forming the nanofibers into the product.

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.

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.