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 Publication Classification (51) Int. Cl. (71) Applicant: PBI 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 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

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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 may have any LOI (Limiting Oxygen 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. spinneret, and Subsequently taken-up after Solvent removal. 0014 Polybenzimidazoles (PBI) resins are a known class 0018 Treating may include the steps of applying the of compounds. See, for example, U.S. Pat. Nos. Re26065; phosphoric acid to the untreated fiber, and, after a suitable 3.433,772; 4,717,764; and 7,696,302, each of which is residence time, removal and/or drying of the treated fiber. incorporated herein by reference. Polybenzimidazole (PBI) Applying the phosphoric acid may be conducted by any resin may be any known PBI resin. PBI resins also refers to conventional method. Conventional methods include, but blends of PBI resins with other polymers, co-polymers of are not limited to, dipping (e.g., via a bath), spraying, PBI, and combinations thereof. The PBI resin component brushing, roller coating, and the like. In one embodiment, may be the entire (100%) resin component or a major (i.e., the treating may be conducted in a bath of phosphoric acid. at least 50 wt %) component. In general, PBI resins may be In one embodiment, the residence time (time that fiber is the product of the melt polymerization of a tetraamine (e.g., immersed in the acid bath) may be in the range of 15-360 aromatic and heteroaromatic tetra-amino compounds) and a seconds. In another embodiment, the residence time may be second monomer being selected from the group consisting in the range of 20-180 seconds. In yet another embodiment, of free dicarboxylic acids, alkyl and/or aromatic esters of the residence time may be in the range of 20-70 seconds. The dicarboxylic acids, alkyl and/or aromatic esters of aromatic bath may be at any temperature. In one embodiment, the or heterocyclic dicarboxylic acid, and/or alkyl and/or aro bath has a temperature in the range of 15-60°C. In another matic anhydrides of aromatic or heterocyclic dicarboxylic embodiment, the bath has a temperature in the range of acid. Further details about PBI polymerization may be 20-50° C. In yet another embodiment, the temperature may obtained from U.S. Pat. Nos. Re 26065; 4,506,068; 4.814, be range of 25-40° C. In yet another embodiment, the 530; and US Publication Nos. 2007/015 1926 and 2014/ temperature may be in the range of 30-40° C. The phos 0357831 (organic aldehyde adduct route), each of which is phoric acid used in the treatment step may be any concen incorporated herein by reference. PBI resins and fibers are tration of phosphoric acid. In one embodiment, the phos commercially available from PBI Performance Products, phoric acid (aqueous) has a concentration in the range of 10-85 wt.%. In another embodiment, the phosphoric acid Inc. of Charlotte, N.C. (aqueous) has a concentration in the range of 20-60 wt.%. 00.15 Examples of PBI polymers include, but are not In still another embodiment, the phosphoric acid (aqueous) limited to: poly-2,2'-(m-phenylene)-5,5'-bibenzimidazole; has a concentration in the range of 40-60 wt.%. In yet poly-2,2'-(biphenylene-2"2")-5,5'-bibenzimidazole; poly-2, another embodiment, the phosphoric acid (aqueous) has a 2'-(biphenylene-4"4")-5,5'-bibenzimidazole; poly-2,2'-(1", concentration of about 50 wt.%. While applying the phos 1",3"trimethylindanylene)-3"5"-p-phenylene-5,5'-bibenz phoric acid, the fiber may under tension. In one embodiment, ; 2,2'-(m-phenylene)-5,5'-bibenzimidazole/2.2- the tension may range from 1.0-25.0 dN (as measured by a (1", 1",3'-trimethylindanylene)- 5",3"-(p-phenylene)-5,5'- conventional tensiometer on a Subtow). In another embodi bibenzimidazole copolymer: 2,2'-(m-phenylene)-5,5- ment the tension may be in the range of 2-12 dN. In still bibenzimidazole-2,2'-biphenylene-2".2"-5.5'- another embodiment, the tension may be in the range of 2-8 bibenzimidazole copolymer; poly-2,2'-(furylene-2".5")-5,5'- dN. In yet another embodiment, the tension may be in the bibenzimidazole; poly-2,2'-(naphthalene-1".6")-5.5'- range of 2.5-7.5 dN. Removal of excess acid and/or drying bibenzimidazole; poly-2,2'-(naphthalene-2",6")-5.5'- may be conducted in any manner. Removal and/or drying bibenzimidazole; poly-2,2'-amylene-5,5'-bibenzimidazole; may include an optional rinse to remove residual acid. poly-2,2'-octamethylene-5,5'-bibenzimidazole; poly-2,2'- 0019 PBI-p fibers may be used in any application. Such (m-phenylene)-diimidazobenzene; poly-2,2'-cyclohexenyl applications include, but are not limited to: applica 5,5'-bibenzimidazole; poly-2,2'-(m-phenylene)-5.5'-dicben tions, mechanical applications, and additives for plastics. In Zimidazole)ether; poly-2,2'-(m-phenylene)-5,5'-di the textile applications, the fibers (either staple of filament) (benzimidazole)sulfide: poly-2,2'-(m-phenylene)-5,5'-di may be combined with other fiber to spin yarns. The yarns (benzimidazole)sulfone; poly-2,2'-(m-phenylene)-5,5'-di may be woven or knitted into fabrics. The fabrics may be cut (benzimidazole)methane; poly-2.2"-(m-phenylene)-5.5"-di and sewn into garments. These textile processes are con (benzimidazole)propane-2.2; and poly-ethylene-1,2-2.2"- ventional. The PBI-p fibers may also be converted to non (m-phenylene)-5.5"-dibenzirnidazole)ethylene-1,2 where wovens by any conventional technique. The mechanical the double bonds of the ethylene groups are intact in the final applications include, for example, gaskets and seals. US 2017/0009383 A1 Jan. 12, 2017

EXAMPLES 0022. The present invention may be embodied in other forms without departing from the spirit and the essential 0020 Extruded polybenzimidazole fiber was washed in attributes thereof, and, accordingly, reference should be hot water to remove spinning solvent and then space drawn made to the appended claims, rather than to the foregoing in a heated oven to improve its tensile properties. The fiber specification, as indicated the scope of the invention. was then treated with 50% (wt) aqueous phosphoric acid by We claim: submerging the fibers in a bath for 48 - 52 seconds from 1. A fiber comprises a polybenzimidazole (PBI) polymer entry to exit of the unit (the fiber was immersed in the liquid with a phosphoric acid pick-up (APU) in the range of for about 25 seconds). The bath temperature was held at 35° 1-25%. C. The fiber was then squeezed to dry it and washed with 2. The fiber of claim 1 wherein the phosphoric acid APU water at room temperature. The washed fiber was then dried is in the range of 4-20%. in an air non-contact oven operating at 350° C. The dry fiber 3. The fiber of claim 1 wherein the phosphoric acid APU was then heat treated in a nitrogen blanketed oven operating is in the range of 12-20%. at 565° C. to fix the acid within the polymer structure. 4. The fiber of claim 1 wherein the phosphoric acid APU Subsequent textile treatment processes resulted in the phos is in the range of 8-24%. phonated fiber being produced as a two inch cut staple fiber. 5. The fiber of claim 1 wherein the phosphoric acid APU is 17%. The 1.5 denier per filament (dpf) cut staple fiber had a 6. The fiber of claim 1 wherein the LOI (Limiting Oxygen tenacity of 2.00 g/dN, an elongation at break of 10.88%, and Index) is about 47%. an acid pick-up of 17-20 wt %. * Acid pick-up values were 7. The fiber of claim 1 wherein the initial thermal decom determined by mass balance, and verified by elemental position temperature in air is about 555° C. analysis. Mass balance—Acid Content was derived using a 8. The fiber of claim 1 having a denier no greater than 6 mass balance evaluating the weight gain of the fiber. The dpf. moisture is removed from the sample and the remaining 9. The fiber of claim 1 is a staple or a filament. mass is divided by the dry PBI from the creel. The balance 10. A yarn comprises the fiber of claim 1. is then checked with a second balance around the acid 11. A fabric comprises the yarn of claim 10. concentrations in the bath, waste-water, and consumption. 12. The fabric of claim 11 is a woven fabric or a knitted Elemental analysis—Acid Content was derived using fabric. elemental analysis by Inductively Coupled Plasma Optical 13. A garment comprises the fabric of claim 11. Emission Spectrometry (ICP-OES). The ICP-OES method 14. A nonwoven comprises the fiber of claim 1. determines the percent of a particular element present in a 15. A method of making a phosphonated polybenzimida sample. In the case of the example fiber, ICP-OES deter Zole fiber comprises the steps of: mined the presence of 5.51% Phosphorous. However, phos spinning an untreated PBI resin into a PBI fiber; phorous is present on the example fiber as Phosphate (PO). treating the PBI fiber with phosphoric acid, and Phosphorous is present in Phosphate at approximately 32%. thereby obtaining a PBI fiber with 1-25 wt.% phosphoric Therefore, the presence of 5.51% Phosphorous tells us that acid. Phosphate (acid) pick-up is approximately 17%. 16. The method of claim 15 wherein the phosphoric acid 0021 Preliminary laboratory phosphoric acid treatment is a 10-85 wt.% phosphoric acid (aqueous). of extruded PBI fiber is further illustrated with the data 17. The method of claim 15 wherein the phosphoric acid presented in Table below. is a 40-60 wt.% phosphoric acid (aqueous). TABLE 1. Time in Time in Time in oven Time in oven Wt after Drying Acid Pickup Estimated Orig. % acid Temp acid H2O 1st drying 2nd drying 2nd Condition (APU) Dry Wt g Fiber wt. g. used C. Sec Sec Sec Sec drying g (in oven) C. wt % Note 1 O.60 0.7 30% OOl 60 5 3OO 100 O.68 8O 14.3% 2 O.63 O.74 SO% OOl 60 5 3OO 100 O.76 8O 20.8% 3 O.60 O.71 85% OOl 60 5 3OO 100 O.67 8O 11.0% 4 O.70 O.82 30% OOl 60 5 3OO 100 O.78 8O 11.9% 5 O.65 0.77 SO% OOl 60 5 3OO 100 0.79 8O 20.7% 6 O.70 O.82 85% OOl 60 5 3OO 100 O.83 8O 19.1% 7 O.71 O.83 30% OOl 60 O 3OO 100 1.14 8O 61.6% 8 O.62 0.73 SO% OOl 60 O 3OO 100 1.29 8O 107.9% 9 0.67 0.79 85% OOl 60 O 3OO 100 1.88 8O 180.0% 10 O.76 O.89 30% 50 60 5 3OO 100 1 8O 32.2% 11 O.65 O.76 SO% 50 60 5 3OO 100 1.02 8O 57.9% 12 O.71 O.84 30% 40 60 5 3OO 100 O.84 8O 17.6% 13 O.70 O.82 SO% 40 60 5 3OO 100 1 8O 43.5% 14 O.34 0.4 SO% 60 60 5 900 100 O.S2 05 52.9% with tension 15 O.34 0.4 SO% 60 60 5 900 100 O.S1 05 SO.0% 16 O.36 O42 SO% 45 60 5 18OO O O.S1 05 42.9% 17 O.34 0.4 SO% 45 60 5 18OO O O.S3 05 55.9% 18 O.38 O.45 SO% 45 60 5 18OO O O48 05 25.5% with tension 19 0.37 0.44 SO% 45 60 5 18OO O O46 05 23.0% with tension US 2017/0009383 A1 Jan. 12, 2017

18. The method of claim 15 wherein the phosphoric acid is a 50 wt.% phosphoric acid (aqueous). 19. The method of claim 15 wherein the treating is conducted at a temperature in the range of 15-50° C. 20. The method of claim 15 further comprising tensioning the fiber during applying the acid. k k k k k