Damage tolerant composites containing infusible particles

Claim 2

An epoxy resin composition comprising a polyepoxide component, a reactive oligomer, a curing agent and infusible particulate, said resin composition exhibiting phase separation upon cure into crosslinked glassy phases and made by a process comprising combining : 100 parts by weight of a polyepoxide component comprising a polyepoxide compound having a glass transition below 50°C and having at least about two epoxide groups per molecule; 'between about 10 and 200 parts by weight of a reactive oligomer component comprising a crosslinkable oligomer having at least about two crosslinkable groups per molecule and a molecular weight (number average) between about 2000 and 10,000; between about 5 and 100 parts by weight of a curing agent for orosslinking said epoxy composition and having a molecular weight below about 1000; and between about I and 16% by weight of said epoxy resin composition of solid, infusible particles having a median size between 10 and 75 microns.

Claim 3

The epoxy resin composition in accordance with Claim I, wherein said infusible particles comprise a a rubber polymer used at a level between about I and 16% by weight of said epoxy resin composition, an amount of said polymer being contained within said infusible particles that are dispersed throughout said resin composition and a lower modulus than the matrix of said epoxy resin composition that is cured in absence of said infusible particles.

Claim 4

The epoxy resin composition in accordance with claim 2, wherein said particles are made using a crosslinkable rubber polymer.

Claim 5

The epoxy resin composition in accordance with claim 3, wherein said crosslinkable rubber polymer is carboxy-functional.

Claim 6

The epoxy resin composition in accordance with claim 4, wherein said reactive oligomer is selected from an amine functional polyarylene polyether sulfone or ketone, an amine functional polyarylene polythioether sulfone or ketone and combinations thereof.

Claim 7

The epoxy resin composition in accordance with claim 5, wherein said curing agent comprises an amine functional sulfone.

Claim 8

The epoxy composition in accordance with claim I, wherein said oligomer comprises an amine functional polyarylene polyether sulfone having a molecular weight between about 2,500 and 7,500.

Claim 9

The epoxy resin composition in accordance with claim 7, wherein said polyepoxide component comprises a combination of di and trifunctional polyepoxide compounds.

Claim 10

In a prepreg useful in making damage tolerant structural composites, said prepreg comprising one or more high strength filament tows or bundles that is impregnated with a thermosettable epoxy resin composition that phase separates into crosslinked glassy phases upon cure, the improvement wherein said impregnation provides a portion of said epoxy resin composition contained within said tows or bundles and a portion of said epoxy resin composition atop a surface of said tows or bundles as a resin surface of said prepreg, said thermosettable epoxy resin comprising infusible particles having a median size between 10 microns and 75 microns, said infusible particles distributed in said thermosettable resin such that the number of said particles having a dimension greater than 10 microns is greater in that part of said resin composition closer to said surface than contained within said tows or bundles.

Claim 11

In a prepreg useful in making damage tolerant structural composites, said prepreg comprising one or more high strength filament tows or bundles that is impregnated with a thermosettable epoxy resin composition that phase separates into crosslinked glassy phases upon cure, the improvement wherein said impregnation provides a portion of said epoxy resin composition contained within said tows or bundles and a portion of said epoxy resin composition atop a surface of said tows or bundles as a resin surface of said prepreg, said thermosettable epoxy resin comprising infusible particles having a median size between 10 microns and 75 microns, said infusible particles distributed in said thermosettable resin such that the number of said particles having a dimension greater than 10 microns is greater in that part of said resin composition closer to said surface than contained within said tows or bundles.

Claim 12

The prepreg in accordance with claim 9, wherein said infusible particles comprise a crosslinked rubber polymer.

Claim 13

II. The prepreg in accordance with claim 10, wherein said high strength fiber tows comprise tows of carbon fiber.

Claim 14

The prepreg in accordance with claim II, wherein said thermosetting resin comprises a polyether sulfone having a molecular weight between about 2,000 and 10,000.

Claim 15

The prepreg in accordance with claim 12, wherein there are particles comprising a rubber polymer having a median size less than about 10 microns that are carried within said tows or bundles.

Claim 16

The prepreg in accordance with claim 9, wherein said tows or bundles extend in two or more directions in said prepreg.

Claim 17

The prepreg in accordance with claim 9, wherein said tows or bundles extend in a single direction and form a sheet.

Claim 18

The prepreg in accordance with claim 15, wherein a single tow or bundle of said high strength filaments form said prepreg.

Claim 19

A multi-layer damage tolerant, structural composite containing high strength filaments and a tough, crosslinked epoxy resin matrix that is phase separated into glassy phases, an amount of said crosslinked epoxy resin matrix, between about I and 16% by weight thereof, being discretely dispersed infusible particles, said composite comprising: a first ply layer having a first group of said filaments and a first matrix portion of said matrix which continue together throughout said composite, said first matrix portion having a portion of said particles dispersed therein that respectively contain an amount of said polymer and have a median particle size less than 10 microns; a second ply layer having a second group of said filaments and a second matrix portion of said matrix which continue together throughout said composite, said second matrix portion having a portion of said particles dispersed therein that respectively contain an amount of said polymer and have a median particle size less than 10 microns; a boundary layer between said first and second ply layers and continues throughout said composite, said boundary layer consisting essentially of a third matrix portion of said matrix which is substantially free of said high strength filaments and integral with said first and second portions of said matrix, said third matrix portion having more of said particles dispersed therein that respectively contain an amount of said polymer and have a dimension greater than 10 microns than either of said first or second matrix portions.

Claim 20

A multi-layer damage tolerant, structural composite containing high strength filaments and a tough, crosslinked epoxy resin matrix that is phase separated into glassy phases, an amount of said crosslinked epoxy resin matrix, between about I and 16% by weight thereof, being discretely dispersed infusible particles, said composite comprising: a first ply layer having a first group of said filaments and a first matrix portion of said matrix which continue together throughout said composite, said first matrix portion having a portion of said particles dispersed therein that respectively contain an amount of said polymer and have a median particle size less than 10 microns; a second ply layer having a second group of said filaments and a second matrix portion of said matrix which continue together throughout said composite, said second matrix portion having a portion of said particles dispersed therein that respectively contain an amount of said polymer and have a median particle size less than 10 microns; a boundary layer between said first and second ply layers and continues throughout said composite, said boundary layer consisting essentially of a third matrix portion of said matrix which is substantially free of said high strength filaments and integral with said first and second portions of said matrix, said third matrix portion having more of said particles dispersed therein that respectively contain an amount of said polymer and have a dimension greater than 10 microns than either of said first or second matrix portions.

Claim 21

The structural. composite in accordance with claim 17, wherein said infusible particles comprise a rubber polymer.

Claim 22

The structural composite in accordance with claim 18, wherein said infusible particles have a lower modulus than said crosslinked glassy phases.

Claim 25

The method in accordance with claim 20, wherein said reactive oligomer comprises an amine functional polyarylene polyether sulfone.

Claim 28

The method in accordance with claim 22, which further comprises admixing an amine hardner with said composition, said amine hardner having a molecular weight belov p about 1,000.

Claim 31

A method in accordance with claim 24, wherein said epoxy resin composition comprises a reactive polyarylene polyether sulfone having a molecular weight between 2,000 and 10,000 (number average).