# US 2021/0276280 A1 · High strength thermoplastic composites

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- Number: US 2021/0276280 A1
- Document ID: US20210276280A1
- Status: Published application
- Kind: A1
- Application number: 16/474,292
- Filed: 2018-02-23
- Published: 2021-09-09
- Earliest claimed: 2017-02-28
- Assignees: E. I. Du Pont de Nemours and Company
- Applicants: E I Du Pont De Nemours and Company
- Inventors: Bryan Benedict Sauer; Zachary R. Dillworth; Mark Gary Weinberg; Jacob G. Dickinson
- Web page: https://patentgrep.com/patent/US20210276280A1

## CPC

- B29C 70/20: oriented in a single direction, e.g. roofing or other parallel fibres {(B29C70/083, B29C70/226 take precedence)}
- C08J 5/043: {with glass fibres}
- B32B 5/022: {Non-woven fabric}
- B32B 5/024: {Woven fabric}
- B32B 5/12: characterised by the relative arrangement of fibres or filaments of {different layers, e.g. the fibres or filaments being parallel or perpendicular to each other}
- B32B 5/26: another layer {next to it} also being fibrous or filamentary {(relative arrangement of fibres or filaments of different layers B32B5/12)}
- B32B 27/12: next to a fibrous or filamentary layer
- B32B 27/286: {comprising polysulphones; polysulfides}
- B32B 27/32: comprising polyolefins {(comprising vinyl (co)polymers or acrylic (co)polymers B32B27/30)}
- B32B 27/34: comprising polyamides
- B32B 27/36: comprising polyesters
- B29K 2101/12: Thermoplastic materials
- B29K 2307/04: Carbon
- B32B 2260/023: Two or more layers
- B32B 2260/046: Synthetic resin
- B32B 2262/0269: Aromatic polyamide fibres
- B32B 2262/10: Inorganic fibres
- B32B 2262/101: Glass fibres
- B32B 2262/106: Carbon fibres, e.g. graphite fibres
- B32B 2307/546: Flexural strength; Flexion stiffness
- B32B 2307/72: Density
- B32B 2307/732: Dimensional properties
- C08J 2300/22: Thermoplastic resins
- B29C: SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING (making preforms B29B11/00; making laminated products by combining previously unconnected layers which become one product whose layers will remain together B32B37/00 - B32B41/00)
- 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)
- B32B: LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B29K: INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR {MOULDS, } REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS

## Abstract

Voided carbon fiber tapes comprising from 18K to 125K carbon fibers, a thermoplastic resin having a viscosity of about 10 to about 150 Pa·s, at least 3 void areas, a fiber fraction ranging from about 35 to 70 percent, a void volume ranging from about 2 to about 50 percent, and at least 10 percent wetted carbon fibers may be used to prepare consolidated thermoplastic composites which exhibit flexural strengths greater than or equal to 75 percent of the theoretical flexural strength.

## Claims

### Claim 1

A voided tape comprising:
a) from 18K to 125K carbon fibers,
b) a thermoplastic resin having a viscosity of about 10 to about 150 Pa·s when measured using a capillary viscometer at a temperature 30° C. above the thermoplastic resin melting point and at a shear rate of 300 s−1,
c) at least 3 void areas,
d) a fiber fraction ranging from about 35 to 70 percent,
e) a void volume ranging from about 2 to about 50 percent when measured by a buoyancy method, and
f) at least 10 percent wetted carbon fibers;
wherein:
the voided tape width ranges from about (0.00019 mm×the number of carbon fibers in (a)) to about (0.0016 mm×the number of carbon fibers in (a)),
the voided tape width:height ratio ranges from about 10 to 1000.

### Claim 2 (depends on 1)

The voided tape of claim 1 comprising 24K to 125K carbon fibers.

### Claim 3 (depends on 1)

The voided tape of claim 1 comprising a single carbon fiber tow.

### Claim 4 (depends on 1)

The voided tape of claim 1 comprising 48K to 60K carbon fibers.

### Claim 5 (depends on 1)

The voided tape of claim 1 wherein the void volume ranges from about 10 to 35 percent.

### Claim 6 (depends on 1)

The voided tape of claim 1 wherein the width ranges from about (0.0003 mm×the number of carbon fibers in (a)) to about (0.0010 mm×the number of carbon fibers in (a)).

### Claim 7 (depends on 1)

The voided tape of claim 1 wherein the width:height ratio ranges from about 30 to 130.

### Claim 8 (depends on 1)

The voided tape of claim 1 comprising at least 4 void areas.

### Claim 9 (depends on 1)

The voided tape of claim 1 comprising 30% to 97% wetted fibers.

### Claim 10 (depends on 1)

A thermoplastic composite preform comprising:
a) at least one carbon fiber fabric layer in the form of woven, RFF, non-woven, uni-directional, or cross-ply structures or a combination of these prepared from the voided tape of claim 1, and
b) from about 60 to 100 percent fabric fill factor.

### Claim 11 (depends on 10)

The thermoplastic composite preform of claim 10 wherein the at least one carbon fiber fabric layer is in the form of woven or RFF fabric structures.

### Claim 12 (depends on 10)

The thermoplastic composite preform of claim 10 comprising bi-axial carbon fiber fabric symmetry.

### Claim 13 (depends on 10)

The thermoplastic composite preform of claim 10 comprising multi-axial carbon fiber fabric structures.

### Claim 14 (depends on 11)

The thermoplastic composite preform of claim 11 wherein the fabric fill factor ranges from about 60 to 96 percent.

### Claim 15 (depends on 10)

A consolidated thermoplastic composite prepared from the thermoplastic composite preform of claim 10, wherein said consolidated thermoplastic composite exhibits a flexural strength greater than or equal to 75 percent of the theoretical flexural strength when measured according to ASTM D7264, and wherein said consolidated thermoplastic composite has an average lamellae layer thickness ranging from about 100 to 200 μm.

### Claim 16 (depends on 15)

The consolidated thermoplastic composite of claim 15, wherein the flexural strength is greater than or equal to 80 percent of the theoretical flexural strength.

### Claim 17 (depends on 15)

The consolidated thermoplastic composite of claim 15, wherein the flexural strength is at least 950 MPa in orthogonal directions when measured according to ASTM D7264.

### Claim 18 (depends on 14)

A consolidated thermoplastic composite prepared from the thermoplastic composite preform of claim 14, wherein said consolidated thermoplastic composite exhibits a flexural strength greater than or equal to 75 percent of the theoretical flexural strength when measured according to ASTM D7264, and wherein said consolidated thermoplastic composite has an average lamellae layer thickness ranging from about 100 to 200 μm.

### Claim 19 (depends on 14)

A consolidated thermoplastic composite prepared from the thermoplastic composite preform of claim 14 by stamp pressing with unconstrained edges wherein the consolidated thermoplastic composite has less than 11 percent squeeze-out.

### Claim 20 (depends on 1)

A process comprising the steps of:
a) heating a thermoplastic composite preform comprising the voided tape of claim 1 to a temperature from about 30 to 80° C. above the melting point of the thermoplastic resin and a pressure ranging from about 100 psi to about 500 psi to form a shaped thermoplastic composite preform,
b) maintaining the temperature and pressure on the shaped thermoplastic composite preform for a time sufficient to impregnate the carbon fibers of the shaped thermoplastic composite preform,
c) cooling the thermoplastic composite preform under pressure to a temperature of about 20° C. to 120° C. to provide a consolidated thermoplastic composite having a flexural strength which is at least 75 percent of the theoretical flexural strength measured according to ASTM D7264.

### Claim 21 (depends on 20)

The process of claim 20 wherein the pressure in step (a) ranges from about 150 psi to about 360 psi.

### Claim 22 (depends on 20)

The process of claim 20 wherein the temperature and pressure in step (b) are maintained for a time from about 30 to about 300 seconds.

### Claim 23 (depends on 20)

The process of claim 20 wherein step (c) occurs in 30 seconds or less.

### Claim 24 (depends on 1)

A process comprising the steps of:
a) stamp-pressing with unconstrained edges a thermoplastic composite preform having a fabric fill factor of 60 to 96 percent prepared from the voided tape of claim 1 at a temperature from about 30 to 80° C. above the melting point of the thermoplastic resin of the preform and a pressure ranging from about 100 psi to about 500 psi,
b) maintaining the temperature and pressure on the thermoplastic composite preform for a time period sufficient to impregnate the carbon fibers of the thermoplastic composite preform,
c) cooling the thermoplastic composite preform under pressure to a temperature of about 20° C. to 120° C. to provide a consolidated thermoplastic composite having less than 11 percent squeeze-out.