Thermoplastic Prepreg Containing Continuous and Long Fibers

• US 20130136890A1
• Filed: 06/22/2011
• Published: 05/30/2013
• Est. Priority Date: 06/22/2010
• Status: Active Grant

• Current Assignee: Ticona LLC (Celanese Corporation)
• Original Assignee: Ticona LLC (Celanese Corporation)
• Inventors: Johnson, Aaron H., Maliszewski, Jeremy J., Tibor, Timothy L.
• Granted Patent: US 9,096,000 B2
• Time in Patent Office: Days
• US Class Current: 428/113
• CPC Class Codes: B29B 11/10 Extrusion moulding
• CPC Class Codes: B29B 11/16 comprising fillers or reinforcement non-woven fabrics per se D04H1/00, D04H3/00
• CPC Class Codes: B29B 15/122 with a matrix in liquid form, e.g. as melt, solution or latex
• CPC Class Codes: B29C 48/0011 combined with compression moulding
• CPC Class Codes: B29C 48/0018 combined with shaping by orienting, stretching or shrinking, e.g. film blowing B29C48/0017 takes precedence
• CPC Class Codes: B29C 48/04 Particle-shaped making granules B29B9/00
• CPC Class Codes: B29C 48/05 Filamentary, e.g. strands
• CPC Class Codes: B29C 48/06 Rod-shaped
• CPC Class Codes: B29C 48/07 Flat, e.g. panels
• CPC Class Codes: B29C 48/08 flexible, e.g. films
• CPC Class Codes: B29C 48/154 Coating solid articles, i.e. non-hollow articles
• CPC Class Codes: B29C 48/156 Coating two or more articles simultaneously
• CPC Class Codes: B29C 48/157 Coating linked inserts, e.g. chains
• CPC Class Codes: B29C 48/21 the layers being joined at their surfaces
• CPC Class Codes: B29C 48/345 Extrusion nozzles comprising two or more adjacently arranged ports, for simultaneously extruding multiple strands, e.g. for pelletising
• CPC Class Codes: B29C 48/397 using a single screw
• CPC Class Codes: B29C 48/695 Flow dividers, e.g. breaker plates
• CPC Class Codes: B29C 48/705 in the die zone, e.g. to create flow homogeneity
• CPC Class Codes: B29C 48/71 for layer multiplication extrusion of multi-component articles B29C48/16
• CPC Class Codes: B29C 48/905 using wet calibration, i.e. in a quenching tank
• CPC Class Codes: B29C 48/908 : characterised by calibrator surface, e.g. structure or holes for lubrication, cooling or venting
• CPC Class Codes: B29C 48/916 : using vacuum
• CPC Class Codes: B29C 48/919 : using a bath, e.g. extruding into an open bath to coagulate or cool the material
• CPC Class Codes: B29C 70/08 : comprising combinations of different forms of fibrous reinforcements incorporated in matrix material, forming one or more layers, and with or without non-reinforced layers
• CPC Class Codes: B29C 70/081 : Combinations of fibres of continuous or substantial length and short fibres
• CPC Class Codes: B29C 70/523 : and impregnating the reinforcement in the die
• CPC Class Codes: B29K 2101/12 : Thermoplastic materials
• CPC Class Codes: B29K 2105/08 : of continuous length, e.g. cords, rovings, mats, fabrics, strands or yarns
• CPC Class Codes: B29K 2105/0872 : Prepregs
• CPC Class Codes: B29K 2105/0881 : unidirectional
• CPC Class Codes: B29K 2105/105 : uni directionally
• CPC Class Codes: B29K 2105/107 : transversally, i.e. perpendicular to the 2D reinforcement direction
• CPC Class Codes: 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
• CPC Class Codes: Y10T 428/24124 : Fibers
• CPC Class Codes: Y10T 428/249942 : Fibers are aligned substantially parallel
• CPC Class Codes: Y10T 428/249945 : Carbon or carbonaceous fiber
• CPC Class Codes: Y10T 428/249946 : Glass fiber

Abstract

A prepreg that contains a plurality of unidirectionally aligned continuous fibers embedded within a thermoplastic polymer matrix is provided. In addition to continuous fibers, the prepreg also contains a plurality of long fibers that are combined with the continuous fibers so that they are randomly distributed within the thermoplastic matrix. As a result, at least a portion of the long fibers become oriented at an angle (e.g., perpendicular) relative to the direction of the continuous fibers. Through such orientation, the long fibers can substantially increase the mechanical properties of the prepreg in the transverse direction (e.g., strength) and thus achieve a more isotropic material. Although unique isotropic prepregs are one aspect of the present invention, it should be understood that this is not a requirement. In fact, one notable feature of the present invention is the ability to tailor the mechanical properties of the prepreg for an intended application by selectively controlling certain process parameters, such as the type of long fibers employed, the type of continuous fibers employed, the concentration of the long fibers, the concentration of the continuous fibers, the thermoplastic resin(s) employed, etc.

Claims

1. A thermoplastic prepreg comprising:

a plurality of continuous fibers that are substantially oriented in a longitudinal direction, the continuous fibers constituting from about 10 wt. % to about 80 wt. % of the prepreg;

a plurality of randomly distributed long fibers, at least a portion of which are oriented at an angle relative to the longitudinal direction, the long fibers constituting from about 2 wt. % to about 35 wt. % of the prepreg; and

a resinous matrix that contains one or more thermoplastic polymers and within which the continuous fibers and long fibers are embedded, wherein the thermoplastic polymers constitute from about 10 wt. % to about 80 wt. % of the prepreg;

wherein the ratio of the maximum tensile stress of the prepreg in the longitudinal direction to the maximum tensile stress of the prepreg in the transverse direction is from about 1 to about 40.

2. The thermoplastic prepreg of claim 1, wherein the ratio of the maximum tensile stress of the prepreg in the longitudinal direction to the maximum tensile stress of the prepreg in the transverse direction is from about 2 to about 30.

3. The thermoplastic prepreg of claim 1, wherein the prepreg exhibits a maximum tensile stress of from about 250 to about 3000 Megapascals in the longitudinal direction.

4. The thermoplastic prepreg of claim 1, wherein the prepreg exhibits a maximum tensile stress of from about 0.5 to about 50 Megapascals in the transverse direction.

5. The thermoplastic prepreg of claim 1, wherein the continuous fibers constitute from about 20 to about 70 wt. % of the prepreg.

6. The thermoplastic prepreg of claim 1, wherein the long fibers constitute from about 5 to about 30 wt. % of the prepreg.

7. The thermoplastic prepreg of claim 1, wherein the continuous fibers, the long fibers, or both, include glass fibers, carbon fibers, or a combination of glass and carbon fibers.

8. The thermoplastic prepreg of claim 1, wherein the thermoplastic polymers include a polyolefin, polyether ketone, polyetherimide, polyarylene ketone, liquid crystal polymer, polyarylene sulfide, fluoropolymer, polyacetal, polyurethane, polycarbonate, styrenic polymer, polyester, polyamide, or a combination thereof.

9. The thermoplastic prepreg of claim 1, wherein the prepreg has a void faction of about 2% or less.

10. The thermoplastic prepreg of claim 1, wherein the long fibers are intermingled with the continuous fibers.

11. The thermoplastic prepreg of claim 1, wherein the long fibers are present within a first layer of the prepreg and the continuous fibers are present within a second layer of the prepreg.

12. The thermoplastic prepreg of claim 11, wherein at least a portion of the long fibers extend into the second layer.

13. A lineal profile comprising the prepreg of claim 1.

14. The lineal profile of claim 13, wherein the profile further comprises a capping layer that defines a surface of the profile.

15. A molded part that comprises the prepreg of claim 1.

16. A method for forming a thermoplastic prepreg, the method comprising:

supplying continuous fibers and long fibers to an extrusion device;

supplying a thermoplastic feedstock to the extrusion device, wherein the feedstock comprises at least one thermoplastic polymer; and

extruding the continuous fibers, long fibers, and the thermoplastic polymer within an impregnation die to form an extrudate in which the continuous fibers are intermixed with the long fibers and embedded with a matrix of the thermoplastic polymer.

17. The method of claim 16, wherein the feedstock comprises the long fibers.

18. The method of claim 16, further comprising pulling the extrudate through a nip defined between rollers to consolidate the extrudate into the form of a sheet.

19. The method of claim 16, wherein the continuous fibers constitute from about 10 to about 80 wt. % of the prepreg and the long fibers constitute from about 2 to about 35 wt. % of the prepreg.

20. The method of claim 16, wherein the continuous fibers, the long fibers, or both, include glass fibers, carbon fibers, or a combination of glass and carbon fibers.

21. The method of claim 16, wherein the thermoplastic polymer includes a polyolefin, polyether ketone, polyetherimide, polyarylene ketone, liquid crystal polymer, polyarylene sulfide, fluoropolymer, polyacetal, polyurethane, polycarbonate, styrenic polymer, polyester, polyamide, or a combination thereof.

22. The method of claim 16, wherein a manifold assembly supplies the thermoplastic feedstock to the extrusion device, the manifold assembly comprising branched runners through which the thermoplastic feedstock flows.

23. A method for forming a thermoplastic prepreg, the method comprising:

supplying continuous fibers to an extrusion device;

supplying a thermoplastic feedstock to the extrusion device, wherein the feedstock comprises at least one thermoplastic polymer; and

extruding the continuous fibers and the feedstock within an impregnation die to form an extrudate in which the continuous fibers are embedded with a matrix of the thermoplastic polymer;

thereafter, applying long fibers to the extrudate to form a composite.

24. The method of claim 23, further comprising pulling the composite through a nip defined between rollers to consolidate the composite into the form of a sheet.

25. The method of claim 23, wherein the continuous fibers constitute from about 10 to about 80 wt. % of the prepreg and the long fibers constitute from about 2 to about 35 wt. % of the prepreg.

26. The method of claim 23, wherein the continuous fibers, the long fibers, or both, include glass fibers, carbon fibers, or a combination of glass and carbon fibers.

27. The method of claim 23, wherein the thermoplastic polymer includes a polyolefin, polyether ketone, polyetherimide, polyarylene ketone, liquid crystal polymer, polyarylene sulfide, fluoropolymer, polyacetal, polyurethane, polycarbonate, styrenic polymer, polyester, polyamide, or a combination thereof.

28. The method of claim 23, wherein a manifold assembly supplies the thermoplastic feedstock to the extrusion device, the manifold assembly comprising branched runners through which the thermoplastic feedstock flows.