# US 9,517,608 B2 · Particle toughening for improving fracture toughness

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- Number: US 9,517,608 B2
- Document ID: US9517608B2
- Status: Granted
- Kind: B2
- Application number: 14/079,918
- Filed: 2013-11-14
- Published: 2014-06-19
- Granted: 2016-12-13
- Earliest claimed: 2012-12-19
- Assignees: Cytec Industries Inc.
- Applicants: Cytec Industries Inc
- Inventors: Emiliano Frulloni; Vincent Aerts; Samuel Hill
- Web page: https://patentgrep.com/patent/US9517608B2

## CPC

- B32B 5/28: impregnated with or embedded in a plastic substance {(not used)}
- B32B 37/10: characterised by the pressing technique, e.g. using action of vacuum or fluid pressure
- B32B 37/14: characterised by the properties of the layers
- C08J 5/243: {using carbon fibres}
- C08J 5/249: {characterised by the additives used in the prepolymer mixture}
- B32B 2250/03: 3 layers
- B32B 2262/106: Carbon fibres, e.g. graphite fibres
- B32B 2264/00: Composition or properties of particles which form a particulate layer or are present as additives
- B32B 2264/12: Mixture of at least two particles made of different materials
- B32B 2305/30: Fillers, e.g. particles, powders, beads, flakes, spheres, chips
- B32B 2305/72: Cured, e.g. vulcanised, cross-linked
- B32B 2307/56: Damping, energy absorption
- B32B 2363/00: Epoxy resins
- C08J 2300/22: Thermoplastic resins
- C08J 2363/00: Characterised by the use of epoxy resins; Derivatives of epoxy resins
- Y10T 156/10: Methods of surface bonding and/or assembly therefor
- Y10T 428/249952: At least one thermosetting synthetic polymeric material layer
- B32B: LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- C08J: WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H (working, e.g. shaping, of plastics B29)
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

A curable prepreg ply formed by applying two outer resin films to the top and bottom surfaces, respectively, of a layer of resin-impregnated reinforcement fibers. The outer resin films contains insoluble toughening particles, and partially soluble or swellable toughening particles, but the resin matrix which impregnates the reinforcement fibers does not contain the same toughening particles. The insoluble toughening particles are insoluble in the resin matrix of the resin films upon curing of the prepreg ply. The partially soluble or swellable toughening particles are partially soluble or swellable in the resin matrix of the resin films upon curing of the prepreg ply, but remain as discreet particles after curing.

## Claims

### Claim 1

A curable prepreg ply comprising:
a layer of resin-impregnated reinforcement fibers having a top surface and a bottom surface;
two resin films applied to the top surface and the bottom surface of said layer, respectively,
wherein said layer of resin-impregnated reinforcement fibers comprises reinforcement fibers impregnated with a first curable resin matrix, and said resin films comprises a second curable resin matrix,
said second curable resin matrix comprises at least one thermoset resin, and a mixture of two different types of particles: (i) insoluble toughening particles, and (ii) partially soluble toughening particles, and
said first curable resin matrix comprises at least one thermoset resin, but is void of said insoluble toughening particles and said partially soluble or swellable toughening particles, and
wherein said insoluble toughening particles are insoluble in the second resin matrix upon curing of the prepreg ply, and said partially soluble toughening particles are thermoplastic particles that decrease in volume by more than 5% upon curing of the prepreg ply, but remain as discreet particles after curing.

### Claim 2 (depends on 1)

The curable prepreg ply of claim 1, wherein the ratio of insoluble toughening particles (i) to partially soluble toughening particles (ii) in the second resin matrix is ranging from 20:80 to 80:20.

### Claim 3 (depends on 1)

The curable prepreg ply of claim 1, wherein the second resin matrix comprises at least one epoxy resin, and said insoluble toughening particles are thermoplastic particles that are insoluble in the epoxy resin upon curing of the epoxy resin.

### Claim 4 (depends on 1)

The curable prepreg ply of claim 1, wherein the insoluble and partially soluble toughening particles have particle sizes in the range of 5 μm-70 μm.

### Claim 5 (depends on 1)

The curable prepreg ply of claim 1, wherein each of the first and second resin matrices comprises a plurality of multifunctional epoxy resins which are common to both matrices.

### Claim 6 (depends on 1)

A composite structure comprising a plurality of prepreg plies laid up in a stacking arrangement to form a laminate structure having toughening particles in the interlaminar regions, which are formed between adjacent layers of reinforcement fibers, wherein each prepreg ply is as recited in claim 1.