E.i. Dupont De Nemours and Company

Dupont Safety & Construction, Inc.

Gary Lee Hendren

Mikhail R Levit

Subhotosh Khan

Vlodek Gabara

Lee J Hesler

Hamid M Ghorashi

Richard L Provost

Danny R Ratliff

Leland A Taylor

Kim L Fried

This invention relates to papers made with fibrids containing a polymer or copolymer derived from a monomer selected from the group consisting of 4,4'diaminodiphenyl sulfone, 3,3&#x2032;diaminodiphenyl sulfone, and mixtures thereof. Such papers have high thermal stability and accept ink more readily than papers made solely with aramid fibrids.

Papers containing fibrids derived from diamino diphenyl sulfone

This invention relates to a honeycomb having cells of paper, comprising by weight 3 to 30 parts by weight aliphatic polyamide binder, and 70 to 97 parts of a poly(paraphenylene terephthalamide) fiber having a modulus of 600 grams per denier (550 grams per dtex) or greater, based on the aliphatic polyamide binder and PPD-T fiber in the paper. In another embodiment, the honeycomb is made from paper comprising by weight 30 to 50 parts aliphatic polyamide binder, and 50 to 70 parts of a poly(paraphenylene terephthalamide) fiber having a modulus of 600 grams per denier (550 grams per dtex) or greater, based on the aliphatic polyamide binder and PPD-T fiber in the paper. Both papers have an average specific tensile index of 60 (lbs/in)/opsy (310 Nm/g) or greater. Articles made from the honeycombs include a panel or an aerodynamic structure.

Honeycomb containing poly(paraphenylene terephthalamide) paper with aliphatic polyamide binder and articles made therefrom

This invention relates to an improved flame retardant honeycomb comprising high modulus fiber and a flame retardant thermoplastic binder having a melt point of from 120&#xb0; C. to 350&#xb0; C. and a limiting oxygen index of 26 or greater, methods for making the honeycomb, and articles comprising the honeycomb. In a preferred embodiment the paper in the honeycomb has a flame classification of UL-94 V-0.

Honeycomb from paper having flame retardant thermoplastic binder

This invention relates to papers made with floc containing a polymer or copolymer derived from a monomer selected from the group consisting of 4,4'diaminodiphenyl sulfone, 3,3&#x2032;diaminodiphenyl sulfone, and mixtures thereof. Such papers have higher elongation-at-break and work-to-break (toughness) properties and exhibit less shrinkage at high temperatures than papers made with solely with poly (metaphenylene isophthalamide) floc.

Papers containing floc derived from diamino diphenyl sulfone

A honeycomb containing a thermoplastic material, high modulus fiber and thermoset resin has process steps of fracturing the thermoset resin, bending, molding or forming the honeycomb in a mold or over a form, heating to allow flow of thermoplastic material and cooling of the honeycomb to retain the shape of the mold or form.

Processes for making shaped honeycomb and honeycombs made thereby

This invention relates to an improved high performance honeycomb, methods for making the same, and articles including aerodynamic structures comprising the honeycomb, the honeycomb made with a paper that allows rapid impregnation of the honeycomb by structural resins while retarding excessive impregnation of node-line adhesives during manufacture. The honeycomb comprises a paper having a thickness of from 25 to 75 microns and a Gurley porosity of 2 seconds or greater and comprising high modulus fiber and thermoplastic binder having a melt point of from 180&#xb0; C. to 300&#xb0; C., wherein at least 30 percent by weight of the total amount of thermoplastic material is in the form of discrete film-like particles in the paper, the particles having a film thickness of about 0.1 to 5 micrometers and a minimum dimension perpendicular to that thickness of at least 30 micrometers.

Honeycomb from controlled porosity paper

This invention relates to a honeycomb including articles such as a panel or aerodynamic structure comprising matrix resin and paper, the paper comprising 50 to 80 parts by weight fibrous material having a modulus of 600 grams per denier (550 grams per dtex) or greater, 0 to 50 parts by weight powdered inorganic material, and 20 parts by weight or greater thermoplastic fiber, the improvement comprising the thermoplastic fiber is a binder for the paper and has a melting temperature above the curing temperature of the matrix resin; a glass transition temperature of greater than 100&#xb0; C., and the weight average molecular weight of the thermoplastic polymer in the thermoplastic fibers changes 20% or less after being maintained for 10 minutes at the melting temperature.

Honeycomb from paper having a high melt point thermoplastic fiber

This invention relates to a honeycomb comprising cells having edges forming a face of the honeycomb, the face defined by a plurality of points and having an area of curvature wherein at least two of the points are located in different tangential planes, the walls of the cells comprising 5 to 50 parts by weight thermoplastic material having a melting point of from 120&#xb0; C. to 350&#xb0; C., and 50 to 95 parts by weight of a high modulus fiber having a modulus of 600 grams per denier (550 grams per dtex) or greater, based on the total amount of thermoplastic material and high modulus fiber in the walls; wherein less than 25 percent of the honeycomb cells in the area of curvature have a re-entrant angle of greater than 180 degrees. This invention also relates to articles including panels and/or aerodynamic structures comprising the honeycomb.

Shaped honeycomb

A laminate for honeycomb structures comprised of two outside layers having good surface adhesion and a tough core layer, said core constituting from 50 to 70% by weight of the laminate and containing from about 60 to 80% by weight of poly(m-phenylene isophthalamide) fibrids and each outside layer constituting from 15 to 25% by weight of the laminate and containing about 60 to 70% by weight of floc.

Tough layered papers with improved surface adhesion

A high strength fibrid-floc sheet is made of a floc which can be carbon, aramid or glass. The fibrids are made from the following units: ##STR1## where n is 4 or 5; X is from 0.03 to 0.30 and Ar is a radical selected from 3,4'-oxydiphenylene, 4,4'-oxydiphenylene, 4,4'-sulfonyldiphenylene, 1,3-phenylene, 1-methyl-2,4-phenylene, and mixtures of such radicals with each other or mixtures of such radicals with up to 50 mol percent of 1,4-phenylene radicals based on the mixtures of radicals.

High strength papers from floc and fibrids

Flash expansion of moist multi-layered boards wherein each layer comprises aramid floc bonded by aramid fibrid results in high strength, low density aramid boards.

Low-density, high strength aramid boards

High temperature resistant pressboard having a density of 0.70 to 0.90 g/cc, a calculated void volume of 31 to 49, percent by volume of said pressboard and a smoothness of 80 to 250 microinches MD range and 90 to 260 microinches is disclosed. The pressboard is prepared by wet laying an aqueous dispersion of polyaramid fibrids and floc to form a waterleaf building up layers to form a wet lap which is dried and then pressed at 270.degree. C. to 520.degree. C. rising a press with a predetermined minimum opening to form the desired smooth low density pressboard.

Pressboard and process for its production

A process for making a wet-laid, elongate, nonwoven flexible sheet having an additive distributed in a predetermined cross-directional pattern includes providing two synthetic fibrous stocks containing the additive in a concentration higher in one stock than in the other stock. The stocks are supplied to a paper machine having a headbox for depositing the stocks on a wire to form a wet sheet with the stocks being introduced into the headbox from a plurality of cross-directional positions equally spaced-apart along the headbox with a generally equal amount of solids being introduced at each position and with the stock with the higher concentration being introduced in higher quantity than the other stock at least at one cross-directional position so that the additive is distributed in the predetermined cross-directional pattern.

Cross-directional distribution of additives in synthetic papers

A process for making a high heat resistant oil-impregnatable insulating board, having a dielectric constant less than 2.7, made from bleached polytetrafluoroethylene floc and aromatic polyamide fibrids and the resulting insulating board are disclosed.

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Richmond, VA, United States of America

Gary Lee Hendren