US 20170009383A1 (19) United States (12) Patent Application Publication (10) Pub. No.: US 2017/0009383 A1 Shiels et al. (43) Pub. Date: Jan. 12, 2017 (54) PHOSPHONATED PB FIBER Publication Classification (51) Int. Cl. (71) Applicant: PBI Performance Products, Inc., DOIF 6/74 (2006.01) Charlotte, NC (US) C08G 73/18 (2006.01) (72) Inventors: Brian P. Shiels, Charlotte, NC (US); (52) U.S. Cl. Gregory S. Copeland, Tega Cay, SC CPC ................. D0IF 6/74 (2013.01); C08G 73/18 (US): Feng Qin, Charlotte, NC (US) (2013.01) (57) ABSTRACT (73) Assignee: PBI Performance Products, Inc. A fiber is made with a polybenzimidazole (PBI) polymer with a phosphoric acid pick-up (APU) in the range of 1-25% (21) Appl. No.: 15/193,206 (PBI-p fiber). The PBI-p fiber may have a LOI-50% and/or an initial thermal decomposition temperature in air of 555° (22) Filed: Jun. 27, 2016 C. A method of making a phosphonated polybenzimidazole fiber comprises the steps of spinning an untreated PBI resin Related U.S. Application Data into a PBI fiber; treating the PBI fiber with phosphoric acid, (60) Provisional application No. 62/188,812, filed on Jul. and thereby obtaining a PBI fiber with 1-25 wt.% phos 6, 2015. phoric acid APU. Patent Application Publication Jan. 12, 2017 US 2017/0009383 A1 C).,L9"|69 |?un61– (~~~~|- US 2017/0009383 A1 Jan. 12, 2017 PHOSPHONATED PB FIBER PBI-p fiber has a phosphoric acid APU in the range of 4-20 wt.%. In still another embodiment, the PBI-p fiber has a RELATED APPLICATION phosphoric acid APU in the range of 8-24 wt.%. In still 0001. This application claims the benefit of co-pending another embodiment, the PBI-p has a phosphoric acid pick U.S. provisional patent application No. 62/188,812 filed Jul. up in the range of 12-20 wt.%. In yet another embodiment, 6, 2015, incorporated herein by reference. the PBI-p fiber has a phosphoric acid APU of about 17 wt. %. In still another embodiment, the PBI-p fiber may have an FIELD OF THE INVENTION APU in the range of lower end-upper end, where the lower 0002 The instant invention is directed to a polybenzimi end of the weight range may be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10. dazole fiber. and 11, and the upper end of the weight range may be: 25, 0003 BACKGROUND 24, 23, 22, 21, 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, and 10. 0004. In the article. History and Development of Poly 0011 PBI-p fibers may have any LOI (Limiting Oxygen benzimidazole by E.J. Powers and G. A. Serad (presented on Index ASTM D2863). PBI-p fibers may have a LOI of Apr. 15-18, 1986 and published in High Performance Poly about 47+% 47%). PBI-p fibers may have a LOI of 50+% mers. Their Origin and Development), it is disclosed that a (>50%). PBI-p fibers may have a LOI of 55+% 55%). In one polybenzimidazole (PBI) polymer with 27 wt.% phosphoric embodiment, PBI-p fibers may have a LOI of 60+% (60%). acid (HPO) absorbed (or pick-up) may have utility as a PBI-p fiber may have a LOI of >60% at >1% or 4% APU very thermo-oxidatively stable fiber, pages 19-20 and Table phosphoric acid. PBI-p fiber may have a LOI in a range of XIII. Powers & Serad teach that the phosphonated PBI is about 60-75% at >1% or 4% APU phosphoric acid. PBI-p made by soaking PBI films in 2% aqueous phosphoric acid, fiber may have a LOI of >60% at about 4-25% APU page 20. phosphoric acid. PBI-p fiber may have a LOI in a range of 0005 Polybenzimidazole fibers, that have been commer about 60-75% at 4-25% APU phosphoric acid. PBI-p fiber cially offered up until this time, are sulfonated. This sul may have a LOI in a range of about 60-75% at lower fonated PBI fiber has met with great commercial success in, end-upper limit % APU phosphoric acid, where the lower for example, fire fighters turnout gear, because it has a LOI end of the weight range may be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10. (limiting oxygen index, ASTM D2863) of around 41. and 11, and the upper limit is chosen from 25, 24, 23, 22, 21, 0006. In an effort to explore for and open up new appli 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, and 10. PBI-p fiber may cations and uses for PBI and articles made from PBI, the have a LOI of about 62.3% at about 7% APU phosphoric inventors have discovered new and more commercially acid. PBI-p fiber may have a LOI of about 65.5% at about advantageous phosphonated PBI fibers. 12% APU phosphoric acid. PBI-p fiber may have a LOI of about 63.5% at about 17% APU phosphoric acid. Accord SUMMARY OF THE INVENTION ingly, one may obtain a thermo-oxidatively stable fiber 0007. A fiber is made with a polybenzimidazole (PBI) without a 27 wt.% phosphoric acid pick-up. This is impor polymer with a phosphoric acid pick-up (APU) in the range tant because of the negative implications associated with of 1-25% (PBI-p fiber). The PBI-p fiber may have a phosphates in the environment. The LOI of PBI-s fibers is in LOI-50% and/or an onset thermal degradation temperature the range of 41-44%. >555° C. determined by Thermo-Gravimetric Analysis 0012. In Thermal Gravimetric Analysis (TGA), changes (TGA) in air at a 20° C./min heating rate. A method of of sample weight are measured as a function of increasing making a phosphonated polybenzimidazole fiber comprises temperature. A sharp weight loss at high temperature often the steps of spinning an untreated PBI resin into a PBI fiber; indicates decomposition of the sample. PBI-p fibers may treating the PBI fiber with phosphoric acid, and thereby have any temperature of onset of thermal decomposition in obtaining a PBI fiber with 1-25 wt.% phosphoric acid APU. air, as determined by thermo-gravimetric analysis (TGA). TGA tests (using a TA Instrument Model TGA Q500) are DESCRIPTION OF THE DRAWING conducted for a PBI-s sample and a PBI-p sample in air at a 20°C/min heating rate to up to 1000°C. The results are 0008 For the purpose of illustrating the invention, there shown in FIG. 1. In the tests, PBI-s fiber sample has an is shown in the drawing a form that is presently preferred; initial thermal decomposition temperature of 55.1° C. and it being understood, however, that this invention is not PBI-p fiber sample has an initial thermal decomposition limited to the precise arrangements and instrumentalities temperature of >555° C. under the same testing conditions. shown. For TGA tests in air at a 20° C./min heating rate, PBI-p fiber 0009 FIG. 1 is a TGA graph comparing the initial (or may have an initial thermal decomposition temperature in a onset) thermal degradation temperatures of various PBI range of about 555-625° C. at > 1 wt.% APU phosphoric fibers in air at a 20° C./min heating rate. acid. PBI-p fiber may have an initial thermal decomposition temperature of >565° C. at about 4-25% APU phosphoric DESCRIPTION OF THE INVENTION acid. PBI-p fiber may have an initial thermal decomposition 0010 Polybenzimidazole (FBI) fibers, phosphonated in temperature in a range of about 565-625° C. at 4-25% APU the range of 1-25 wt.% phosphoric acid (or 1-25 wt.% acid phosphoric acid. PBI-p fiber may have an initial thermal pick up (or APU) of phosphoric acid), have thermo-oxida decomposition temperature in a range of about 565-625°C. tive stability equal to or better than commercially available at lower end-upper limit'/6 APU phosphoric acid, where the sulfonated PBI fibers (the range includes all sub-ranges lower end of the weight range may be 1, 2, 3, 4, 5, 6, 7, 8, included therein). Thereinafter, phosphonated PBI fiber will 9, 10, and 11, and the upper limit is chosen from 25, 24, 23, be referred to as PBI-p fiber, and sulfonated PBI fiber will 22, 21, 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, and 10. The be referred to as PBI-s fiber. In another embodiment, the following is actual test data: PBI-p fiber has an initial US 2017/0009383 A1 Jan. 12, 2017 thermal decomposition temperature of about 567° C. at polymer. Poly-2,2'-(m-phenylene)-5,5'-bibenzimidazole is about 7% APU phosphoric acid; PBI-p fiber has an initial preferred. thermal decomposition temperature of about 577° C. at about 12% APU phosphoric acid; and PBI-p fiber has an 0016. In general, PBI-p fiber may be made by: spinning initial thermal decomposition temperature of about 592 C. PBI resin (without any acid treatment, i.e., untreated), and at about 17% APU phosphoric acid. treating the fibers with phosphoric acid. 0013 PBI-p fiber may have any denier. PBI-p fiber may 0017 Spinning may be by any conventional spinning have a denier no greater than 6 denier per filament (dpf). technique. One such technique is solution spinning where a PBI-p fiber may have a denier in the range of 0.1-5 dpf. In dope (FBI dissolved in a suitable solvent) is spun through a one embodiment, the fiber denier is in the range of 1-3 dpf.