Composite articles reinforced with highly oriented microfibers

• US 20040012118A1
• Filed: 07/14/2003
• Published: 01/22/2004
• Est. Priority Date: 02/05/1999
• Status: Active Grant

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Hobbs, Terry R., Perez, Mario A., Siedle, Allen R., Swan, Michael D.
• Granted Patent: US 7,014,803 B2
• Time in Patent Office: Days
• US Class Current: 264/257
• CPC Class Codes: B32B 2255/02 on fibrous or filamentary layer
• CPC Class Codes: B32B 2255/26 Polymeric coating
• CPC Class Codes: B32B 2260/021 Fibrous or filamentary layer
• CPC Class Codes: B32B 2262/0253 Polyolefin fibres
• CPC Class Codes: B32B 2305/20 in the form of a non-woven mat
• CPC Class Codes: B32B 2307/412 Transparent
• CPC Class Codes: B32B 2310/0445 using gas or flames B32B2310/0427 takes precedence
• CPC Class Codes: B32B 2310/14 Corona, ionisation, electrical discharge, plasma treatment
• CPC Class Codes: B32B 2323/10 Polypropylene
• CPC Class Codes: B32B 2367/00 Polyesters, e.g. PET, i.e. polyethylene terephthalate
• CPC Class Codes: B32B 27/32 comprising polyolefins comprising vinyl (co)polymers or acrylic (co)polymers B32B27/30
• CPC Class Codes: B32B 27/36 comprising polyesters
• CPC Class Codes: B32B 38/0008 Electrical discharge treatment, e.g. corona, plasma treatment; wave energy or particle radiation heat treatment B32B38/0036
• CPC Class Codes: B32B 5/022 Non-woven fabric
• CPC Class Codes: B32B 5/26 another layer next to it also being fibrous or filamentary relative arrangement of fibres or filaments of different layers B32B5/12
• CPC Class Codes: D01D 5/423 by fibrillation of films or filaments
• CPC Class Codes: Y10T 428/24355 Continuous and nonuniform or irregular surface on layer or component [e.g., roofing, etc.]
• CPC Class Codes: Y10T 428/24994 Fiber embedded in or on the surface of a polymeric matrix
• CPC Class Codes: Y10T 428/2904 Staple length fiber
• CPC Class Codes: Y10T 428/2913 Rod, strand, filament or fiber
• CPC Class Codes: Y10T 428/2924 : Composite
• CPC Class Codes: Y10T 428/2929 : Bicomponent, conjugate, composite or collateral fibers or filaments [i.e., coextruded sheath-core or side-by-side type]
• CPC Class Codes: Y10T 428/2973 : Particular cross section
• CPC Class Codes: Y10T 428/2976 : Longitudinally varying
• CPC Class Codes: Y10T 442/613 : Microcellular strand or fiber material

Abstract

A composite formed of a polymer matrix phase having a reinforcement phase including polymeric microfibers. The microfibers are preferably formed of a highly oriented polymer, having a high modulus value and a large surface area. The large surface area can serve to tightly bind the microfibers to the polymer matrix phase. The microfibers can be provided as a fully- or partially-microfibrillated film, as a non-woven web of entangled microfibers, or as a pulp having free fibers. The microfibers can be embedded in, or impregnated with, a polymer or polymer precursor. Some composite articles are formed from thermoset resins cured about a highly oriented polypropylene microfiber reinforcement phase, providing a strong, tough, moisture resistant article. One composite includes a matrix and reinforcement formed of the same material type and having substantially equal refractive indices, allowing the composite to be optically clear.

Claims

1. A method for making a composite article, the method comprising the steps of:

providing a polymerizable monomer or resin;

providing a microfibrillated article;

contacting the microfibrillated article with the monomer; and

polymerizing the monomer(s) or resin into the matrix polymer.

2. A method for making a composite article as in claim 1, wherein the microfibers of the microfibrillated article have a surface area of at least about 3 square meter per gram.

3. A method for making a composite article as in claim 1, wherein the microfibers have a draw ratio of 10:

1.

4. A method for making a composite article as in claim 1, wherein the microfibers have a tensile strength of at least about 275 MPa.

5. A method for making a composite article as in claim 1, wherein the microfibers have a surface coating thereon.

6. A method for making a composite article as in claim 5, wherein the surface coating includes a coupling agent.

7. A method for making a composite article as in claim 1, wherein the microfibers have a surface treatment thereon.

8. A method for making a composite article as in claim 1, wherein the microfibers are formed of polypropylene.

9. A method for making a composite article as in claim 1, wherein the monomer is selected from the group of phenolic resins, epoxy resins, vinyl ether resins, vinyl ester resins, urethane resins, cashew nut shell resins, napthalinic phenolic resins, epoxy modified phenolic resins, silicone resins, polyimide resins, urea formaldehyde resins, methylene dianiline resins, methyl pyrrolidinone resins, acrylate and methacrylate resins, isocyanate resins, unsaturated polyester resins, and mixtures thereof.

10. A method for making a composite article as in claim 1, wherein the microfibrillated article comprises a non-woven web of entangled microfibers.

11. A method for making a composite article as in claim 1, wherein the microfibrillated article further comprises engineering fibers.

12. The method of claim 11 wherein said engineering fibers are selected from the group consisting of E-glass, S-glass, boron, ceramic, carbon, graphite, aramid, polybenzoxazole, ultrahigh molecular weight polyethylene (UHMWPE), and liquid crystalline thermotropic fibers.

13. A method for making a composite article as in claim 1, wherein the monomer is a precursor to a thermoset polymer.

14. A method for making a composite article as in claim 1, wherein the monomer is a precursor to an elastomeric polymer.

15. A method for making a composite article comprising the step of laminating at least one microfiber layer to at least one polymer matrix layer.

16. The method of claim 15 wherein said polymer layer is a thermoplastic polymer layer.

17. The method of claim 16 wherein said microfiber layer further comprises engineering fibers.

18. A method for making a composite article, the method comprising the steps of:

providing a thermoplastic polymer;

providing a microfibrillated article;

contacting the microfibrillated article with the thermoplastic polymer with heat and/or pressure.

19. The method of 18 wherein the thermoplastic polymer is injection molded.

20. The method of 18 wherein the microfibrillated article is extrusion coated with thermoplastic polymer.

21. The method of 18 wherein the microfibrillated article and thermoplastic polymer are laminated together.