3-D printed fluoropolymer structures

Patent metadata

Field	Value
Publication number	US-11248071-B2
Application number	US-202016856254-A
Country	US
Kind code	B2
Filing date	Apr 23, 2020
Priority date	Apr 1, 2016
Publication date	Feb 15, 2022
Grant date	Feb 15, 2022

Abstract

The invention relates to fluoropolymer filament for use in 3-D printing, and 3-D printed fluoropolymer articles having low warpage, excellent chemical resistance, excellent water resistance, flame resistance, and good mechanical integrity. Additionally, the articles of the invention have good shelf life without the need for special packaging. In particular, the invention relates to filament, 3-D printed polyvinylidene fluoride (PVDF) articles, and in particular material extrusion 3-D printing. The articles may be formed from PVDF homopolymers, copolymers, such as KYNAR® resins from Arkema, as well as polymer blends with appropriately defined low shear melt viscosity. The PVDF may optionally be a filled PVDF formulation. The physical properties of the 3-D printed articles can be maximized and warpage minimized by optimizing processing parameters.

First claim

What is claimed is:

1. A process for forming a 3-dimensional fluoropolymer article, comprising the steps of:
a) presetting the software of a 3D printer to a set volume flow and line spacing for the printing of said article;
b) feeding at least one fluoropolymer composition in the form of filament, pellets or powder into the 3D printer;

wherein the 3D printer heats the fluoropolymer composition to form a melt;
c) depositing the melt through one or more nozzles at the set location, line spacing and flow rate set by the software, to form an article,

wherein said fluoropolymer composition comprises a fluoropolymer comprising either a homopolymer of vinylidene fluoride, or a copolymer comprising at least 65 weight percent of vinylidene fluoride monomer units, and one or more comonomers, wherein said fluoropolymer has a low shear rate viscosity at 232° C. and 4 sec −1 of less than 13,000 Pa-s, as measured by capillary rheomometry and a high shear rate viscosity of 30 to 2000 Pa-s at 232° C. and 100 sec −1 , as measured by capillary rheomometry at the temperature given in the ASTM Melt Flow Testing for that fluoropolymer.

2. The process of claim 1 , wherein said fluoropolymer composition is in the form of a filament or pellets.

3. The process of claim 2 , wherein said filament is a coextruded, multiphase filament having at least one polyvinylidene fluoride homopolymer or copolymer phase, and at least one phase of another polymer, copolymer or blend, and wherein the total of all polyvinylidene fluoride homopolymer and copolymer phases makes up greater than 50 weight percent of said filament.

4. The process of claim 2 , wherein said filament contains less than 5 volume percent of void space.

5. The process of claim 1 , wherein said fluoropolymer composition further comprises from 0.01 to 50 weight percent filler based on the weight of the fluoropolymer and filler.

6. The process of claim 5 , wherein said filler is selected from the group consisting of carbon fiber, milled carbon fiber, carbon powder, carbon nanotubes, glass beads, glass fibers, nano-silica, Aramid fiber, polyaryl ether ketone fibers, BaSO 4 , talc, CaCO 3 , graphene, impact modifiers, nano-fibers, and hollow spheres, and mixtures thereof.

7. The process of claim 1 , wherein said fluoropolymer composition comprises a blend of said fluoropolymer and up to 49 weight percent of one or more other compatible polymers.

8. The process of claim 7 , wherein said other compatible polymer is selected from the group consisting of a different fluoropolymer, a polymethyl methacrylate homopolymer or copolymer, a block copolymer with one or more compatible blocks and at least one incompatible block, and combinations thereof.

9. The process of claim 7 , wherein blend comprises at least two chemically different fluoropolymers, and/or fluoropolymers of differing weight average molecular weights wherein said weight average viscosity of the blend is less than 13000 Pa-s.

10. The process of claim 1 , wherein the one or more comonomers of the copolymer are selected from the group consisting of tetrafluoroethylene (TFE), trifluoroethylene (TrFE), chlorotrifluoroethylene (CTFE), dichlorodifluoroethylene, hexafluoropropene (HFP), vinyl fluoride (VF), hexafluoroisobutylene (HFIB), perfluorobutylethylene (PFBE), 1,2,3,3,3-pentafluoropropene, 3,3,3-trifluoro-1-propene, 2-trifluoromethyl-3,3,3-trifluoropropene, 2,3,3,3-tetrafluoropropene, 1-chloro-3,3,3-trifluoropropene, fluorinated vinyl ether, fluorinated dioxoles, partially- or per-fluorinated alpha olefins of C 4 and higher, partially- or per-fluorinated cyclic alkenes of C 3 and higher, and combinations thereof.

11. The process of claim 10 , wherein the fluorinated vinyl ether is selected from the group consisting of perfluoromethyl ether (PMVE), perfluoroethylvinyl ether (PEVE), perfluoropropylvinyl ether (PPVE), perfluorobutylvinyl ether (PBVE) and combinations thereof.

12. The process of claim 1 , wherein said fluoropolymer has a low shear rate viscosity at 232° C. and 4 sec −1 of less than 10,000 Pa-s.

13. The process of claim 1 , wherein said flow rate and/or line spacing represents an overflow of from 105 to 150 volume percent.

14. The process of claim 1 , further comprising the step of cross-linking, by radiation, after step c).

15. The process of claim 14 , wherein two or more fluoropolymers compositions with different stress modulus are deposited.

16. The process of claim 1 , wherein two or more nozzles are depositing the same or different fluoropolymer compositions.

17. A three-dimensionally printed fluoropolymer article, formed by the process of claim 1 .

Assignees

• Arkema Inc

Inventors

• Liu David Shin-Ren
• O'Brien Gregory S
• Seiler David A
• Aubart Mark
• Henry James J
• Roland Thomas

Classifications

• B29C64/112 Primary

  using individual droplets, e.g. from jetting heads · CPC title

• C08L61/00

  Compositions of condensation polymers of aldehydes or ketones (with polyalcohols C08L59/00; with polynitriles C08L77/00); Compositions of derivatives of such polymers · CPC title

• C08K7/04

  inorganic · CPC title

• C08K3/40

  Glass · CPC title

• B32B7/02

  Physical, chemical or physicochemical properties · CPC title