THERMOPLASTIC COMPOSITE AND ITS MANUFACTURING

Abstract

The present invention provides a roll-to-roll continuous manufacturing process for producing a thermoplastic composite laminate comprising extruding a thermoplastic resin into a film article, surface treating a fiber material with a special sizing and laminating at least one layer of thermoplastic film and at least one layer of the surfaced treated fiber material into a composite sheet at a temperature above the melting or softening point of the thermoplastic film and under pressure applied by nipping rolls or nipping belts.

Claims

1.-14. (canceled)

15. A roll-to-roll continuous manufacturing process for producing a thermoplastic composite laminate comprising: extruding a thermoplastic resin into a film article; surface treating a fiber material with a polymer sizing; and laminating at least one layer of thermoplastic film and at least one layer of the surfaced treated fiber material into a composite sheet at a temperature above the melting or softening point of the thermoplastic film and under pressure applied by nipping rolls or nipping belts, whereby the fiber material are unidirectional fibers, woven cloth, fiber fleece or combinations thereof

16. The process according to claim 15 further including adding a silane coupling agent to the thermoplastic film.

17. The process according to claim 15 further including adding a silane coupling agent to the polymer sizing.

18. The process according to claim 15, wherein the extruding is by one selected from the group consisting of a blown film process and a flat-die process.

19. The process according to claim 15, wherein the thermoplastic resin is selected from the group consisting of thermoplastic polyurethane, polyethylene terephthalate glycol-modified copolyester, polycarbonate, polycarbonate copolymer, poly(methyl methacrylate), polycarbonate/acrylonitrile butadiene styrene blend and polystyrene.

20. The process according to claim 19, wherein the thermoplastic resin is polyurethane.

21. The process according to claim 20, wherein the polyurethane has soft segments in its backbone structure and a hardness between 50-80 Shore D.

22. The process according to claim 20, wherein the polyurethane has no soft segments in its backbone structure and has a hardness above 80 Shore D.

23. The process according to claim 15, wherein the polymer sizing is selected from the group consisting of polyurethane, epoxy, phenolic and polyacrylate based dispersion in water or an organic solvent.

24. The process according to claim 15, wherein the polymer sizing is a dispersion of polyurethane in water.

25. The process according to claim 15, wherein the fibers are selected from the group consisting of glass, rock, ceramic, carbon, graphite, polyamide, aramid, wool cotton, copper and aluminum and combinations thereof.

26. A thermoplastic composite laminate made according to the process of claim 15.

27. An article made of the thermoplastic laminate according to claim 26.

28. A method comprising utilizing the article according to claim 27 as structural reinforcement part in automotive, bicycle, boat or air- or space craft sector as housing parts for machines, whereby the fibers material are unidirectional fibers, woven cloth, fiber fleece or combinations thereof.

Description

[0066] The present invention will now be described for purposes of illustration and not limitation in conjunction with the figures and examples, wherein:

[0067] FIG. 1 shows a typical cyclic process flow of TPU and unidirectional fiber on a press.

[0068] FIG. 2 shows a microscopic cross-sectional image of carbon fibers with a TPU-matrixwith approximately 41 vol.-% of fibers.

[0069] Thermoplastic composites processing with films.

[0070] At least one layer of thermoplastic film and one layer of fiber material which may be a woven cloth or unidirectional fibers or fleece are unwound from their individual rolls and guided to meet in a laminator comprising of heated nip rolls and nipping belts. Under pressure and heat applied by the nipping rolls and belts, the thermoplastic film layers turn into a melt and are squeezed to fill into all voids inside the fiber material as the laminating layers moving forward continuously inside the laminator. Upon exiting the laminator, the laminate is cooled to below melting or glass transition temperature of the thermoplastic film by passing through cooling rolls and consolidates into a rigid composite sheet or tape. The resultant composite sheet or tape is wound up into a roll for further forming and molding uses.

[0071] The present invention is further illustrated, but is not to be limited, by the following examples in which the following materials were used:

EXAMPLE 1

[0072] TPU-film, a Dureflex X2311 aromatic thermoplastic polyurethane film with a shore D value of 83, and UD-fibers were laminated in an own built thermo bonding machine by Cetex Institute wherein the fibers were arranged to a tape with uniform thickness and width between 150 mm and 250 mm. The lamination was used to fix the fibers, it was not intended to fully impregnate the fibers by the TPU film matrix. After laminating the tape was wound on a roll for further processing. For the production of impregnated composite sheets (organic sheets), a rectangular tool made of steel enclosed on all sides with a defined height was used to be fitted with the UD-tapes. The tool was closed with a steel plate. In a press manufactured by the company Dr. Collin Type P300 P/M the heating of the UD tapes, as well as the pressing of the single layers was performed. After cooling, the fully impregnated composite sheet was removed. A thermoforming to a geometric part can be done later. A typical cyclic process flow on a press is shown in FIG. 1.

TABLE-US-00001 TABLE 1 Parameters for the cyclic press flow as shown in FIG. 1 for a sheet of 289 cm.sup.2 Step 1 2 3 4 Time/sec 1 260 180 480 T top/ C. 140 210 210 70 T bottom/ C. 140 210 210 70 Temperature 0 30 0 30 Raise/K/min Machine 0 35 47 47 Pressure/bar Tool Pressure/ 0 149 200 200 N/cm.sup.2 Presssure Raise/ 0 0 0 0 bar/sec

[0073] The sheets can then be water-jet cut and cut straps can be formed as well as samples for tensile stress, compression stress, impact resistance or bending tests. The samples are examined in a degree of 0, 45 and 90 with respect to the UD fibers. Furthermore, the sheets can be thermoformined or high-pressure formed.

[0074] Following properties were determined for the UD fiber reinforced TPU prepared according to Example 1 and listed in Table 2:

TABLE-US-00002 TABLE 2 Properties of the fibers prepared according to example 1 Carbon Carbon Glass fibers - fibers - fibers - TPU (41 TPU (50 TPU (41 vol.-%) vol.-%) von.-%) Tensile strength/MPa 1.120 1.468 15 Flexural modulus of 89 122 25 elasticity/GPa Bending strength/MPa 320 1.226 17 Bending elongation/% 0.6 1.0 0.8 Impact resistance/ 98 80 125 kJ/m.sup.2 Shear strength/MPa 27 66 16

[0075] A Zwick Z100 material testing machine with a macro displacement transducer was used to determine the flexural modulus, the bending strength and elongation according to DIN EN ISO 14125 and a Zwick Pendulum Z 25J was used to determine the impact resistance according to DIN EN ISO 179.

[0076] TPU films with a higher amount of Carbon fibers show significant higher mechanical strength than TPU films with lower amount of Carbon fiber volume. It is also notable that the strength of TPU-Carbon fiber sheet is clearly superior compared to Glass fiber sheet with the same TPU-matrix.

TABLE-US-00003 TABLE 3 Properties of reinforced TPU films compared to reinforced polyamide (PA6) films Carbon fibers - Carbon fibers - TPU (50 vol.-%) PA 6 (50 vol.-%) Tensile strength/MPa 1.468 1.094 Flexural modulus of 122 108 elasticity/GPa Flexural strength/MPa 1.226 1.026 Flexural strain/% 1.0 0.9

[0077] Surprisingly reinforced TPU films (inventive films) show better mechanical properties than reinforced polyamide (PA 6) films if they are comparable strengthened (Table 3). The inventive films are easier and faster to be processed and handled.

[0078] Instead of a composite plate, the individual UD tapes can be formed also in a geometric three-dimensional structure to a structural component.

[0079] After the first trials with the TPU film in thermoplastic composites area, the following effects were observed: [0080] very good impregnation behavior of glass fibers and carbon fibers to the TPU matrix [0081] almost every single filament with TPU matrix enclosed (see also the microscopic cross-sectional images of the composite laminates, FIG. 2) [0082] good processing behavior [0083] very suitable for the production of composites.

[0084] Surprisingly, it turned out that very good optical surfaces can be produced with the TPU film and the surface of the tool is very well mapped. Matrix resin buildup on the tool is very easy to remove without expensive mechanical cleaning. The use of mold release agents is not required.

[0085] The thermoplastic/fiber composite sheets made by the instant process may preferably be used to make parts by thermoforming in short molding cycles and they are recyclable. These parts possess good chemical resistance, mechanical properties and are paintable or printable without priming or other surface preparations.

[0086] Various aspects of the subject matter described herein are set out in the following numbered clauses in any combination thereof:

[0087] 1. A roll-to-roll continuous manufacturing process for producing a thermoplastic composite laminate comprising: extruding a thermoplastic resin into a film article; surface treating a fiber material with a polymer sizing; and laminating at least one layer of thermoplastic film and at least one layer of the surfaced treated fiber material into a composite sheet at a temperature above the melting or softening point of the thermoplastic film and under pressure applied by nipping rolls or nipping belts, whereby the fiber material are unidirectional fibers, woven cloth, fiber fleece or combinations thereof.

[0088] 2. The process according to claim 1 fiirther including adding a silane coupling agent to the thermoplastic film.

[0089] 3. The process according to Claims 1 or 2 further including adding a silane coupling agent to the polymer sizing.

[0090] 4. The process according to any of Claims 1 to 3, wherein the extruding is by one selected from the group consisting of a blown film process and a flat-die process.

[0091] 5. The process according to any of claims 1 to 4, wherein the thermoplastic resin is selected from the group consisting of thermoplastic polyurethane, polyethylene terephthalate glycol-modified copolyester, polycarbonate, poly(methyl methacrylate), polycarbonatelacrylonitrile butadiene styrene blend and polystyrene.

[0092] 6. The process according to claim 5, wherein the thermoplastic resin is polyurethane.

[0093] 7. The process according to claim 6, wherein the polyurethane has soft segments in its backbone structure and hardness between 50-80 Shore D.

[0094] 8. The process according to claim 6, wherein the polyurethane has no soft segments in its backbone structure and has a hardness above 80 Shore D.

[0095] 9. The process according to any of Claims 1 to 8, wherein the polymer sizing is selected from the group consisting of polyurethane, epoxy, phenolic and polyacrylate based dispersion in water or an organic solvent.

[0096] 10. The process according to any of Claims 1 to 9, wherein the polymer sizing is a dispersion of polyurethane in water.

[0097] 11. The process according to any of Claims 1 to 10, wherein the fibers are selected ftom the group consisting of glass, rock, ceramic, carbon, graphite, polyamide, aramid, wool cotton, copper and aluminum and combinations thereof.

[0098] 12. A thermoplastic composite laminate made according to the process of any of Claims 1 to 11.

[0099] 13. An article made of the thermoplastic laminate according to claim 12.

[0100] 14. Use of an article according to claim 14 as structural reinforcement part in automotive, bicycle, boat or air-or space craft sector as housing parts for machines, whereby the fibers material are unidirectional fibers, woven cloths, fiber fleece or combinations thereof.

[0101] The foregoing examples of the present invention are offered for the purpose of illustration and not limitation. It will be apparent to those skilled in the art that the embodiments described herein may be modified or revised in various ways without departing from the spirit and scope of the invention, The scope of the invention is to be measured by the appended claims.