Temperature-resistant polymer composition and methods for its production

Abstract

A temperature-resistant polymer composition comprising: a. poly-2,5-benzimidazole having an inherent viscosity (IV) between 1.0 dL / g and 2.5 dL / g; and b. at least one binder having a glass transition temperature lower than that of the poly-2,5-benzimidazole and having an inherent viscosity in the range of 0.2 dL / g and 1.5 dL / g, which is subjected to compression at a temperature in the range of 400 °C to 600 °C and a pressure in the range of 689,475.72 Pa (1000 psi) to 689,475.29 Pa (10000 psi), wherein the composition is characterized by: i. a glass transition temperature in the range of 150 to 480 °C; and ii. a ratio of poly-2,5-benzimidazole to binder in a range between 95:5 and 5:95.

Description

FIELD OF THE DISCLOSURE:The present disclosure relates to a high temperature resistant thermosetting material. The present disclosure also relates to a method of manufacturing articles from a high temperature resistant thermoset material.BACKGROUND:ABPBI or poly-2,5-benzimidazole (PBI) is a thermosetting polymer represented by the empirical formula: -(C 7 H 4 N 2)n-. It is a solid, odorless, brown or black substance having a specific gravity ranging from 1.28 to 1.33 and is insoluble in water and organic solvents and has no freezing or melting point. The polymer is not melt processable to 500°C due to its high glass transition temperature (Tg) and lack of melting temperatures (Tm) to 500°C. Therefore, the polymer is extremely high temperature stable, but obviously also difficult to process. ABPBI is also highly chemical resistant (it is even non-flammable) and can even be formed as a fiber with excellent textile and tactile performance. Although it has excellent properties which debriminate applications in various fields such as fire fights and aerospace authorities, it has not been fully studied as a preliminary stage because of the difficulty of processing.DE69026128 relates to a sintered shaped body made from a homogeneous mixture of 5 to 75 wt.% polybenzimidazole and 95 to 25 wt.% polyether ketone. The PBI polymers suitable for the preparation of the sintered articles used in DE69026128 are poly-2,2'-(m-phenylene)-5,5'-bibenzimidazole (PBI) prepared by a two monomer reaction using 3,3'-diaminobenzidine and diphenyl ester of isophthalic acid.Moreover, Zheng et al. (Journal of Power Sources, 2012, volume 208, pp. 176-179) relate to mixing membranes. The mixed membranes are based on poly(2,5-benzimidazole) (ABPBI) and sulfonated poly(ether ether ketone) (SPEEK) with different sulfonation degrees (SD). These mixed membranes exhibited increased conductivity compared to the original ABPBI membrane. After doping with H 3 PO 4 a maximum conductivity of 1.09×10 -1 S cm -1 for ABPBI with 16% SD SPEEK membranes is achieved at 100° C., which is six times higher than the maximum conductivity of 1.8×10 -2 S cm -1 for the ABPI membrane at 120° C.Heretofore, it has been applied only as a solution casting membrane and has been estimated as a phosphoric acid-impregnated proton exchange fuel cell membrane. Therefore, the need for an effective solution by which such a unique and useful polymer becomes processable is apparent.DEFINITIONS:As used in the present disclosure, the following terms and formulations are intended to have the meaning defined below, except to the extent that the context in which they are used indicates otherwise.The term "thermally stable" indicates the resistance of an article or material to change in dimensions or structure due to heat.TARGETING:Some of the objects of the disclosure made possible by at least one embodiment are described below:It is an object of the present disclosure to provide a temperature resistant thermosetting polymer.An object of the present disclosure is to improve the industrial applicability of the temperature-resistant thermosetting polymer.Another object of the present disclosure is to overcome the inherent barriers in terms of physical properties to render the temperature resistant thermoset polymer processable.Another object of the present disclosure is to solve the problem of difficulty in the processability of the temperature-resistant thermosetting polymer.Another object of the present disclosure is to provide a method for making an easily processable temperature resistant thermosetting polymer.Still another object of the present disclosure is to provide a preliminary stage for the manufacture of general technical goods that are resistant to heat and chemicals.Other objects and advantages of the present disclosure will become more apparent from the following description, which is not intended to limit the scope of the present disclosure.SUMMARY:In one aspect of the present disclosure, a temperature resistant polymer composition is provided comprising: a. poly-2,5-benzimidazole having an inherent viscosity (I.V.) between 1.0 dL / g and 2.5 dL / g; and b. at least one binder having a glass transition temperature lower than the glass transition temperature of the poly-2,5-benzimidazole and an inherent viscosity in the range between 0.2 dL / g and 1.5 dL / g subjected to compression at a temperature in the range between 400°C and 600°C and a pressure in the range between 6894775.72 Pa (1000 psi) and 6894757.29 Pa (10000 psi), the composition characterized by: i. a glass transition temperature in the range between 150 and 480°C; and ii. a ratio of the poly-2,5-benzimidazole to the binder in a range between 95:5 and 5:95.In one embodiment of the present disclosure, the ratio of the poly-2,5-benzimidazole to the binder is in a range between 95:5 and 50:50.Normally, the binder is selected from the group consisting of polyether ketone (PEK), polyaryletherketone (PAEK), polyetheretherketone (PEEK), polyetherketoneketone (PEKK), polyphenylene sulfide (PPS), polyetherimide (PEI), polyethersulfone (PES), and polyphenylsulfone (PPSU). Preferably, the binder is selected from the group consisting of polyetheretherketone (PEEK), polyetherketone (PEK), and polyethersulfone (PES).In another aspect of the present disclosure, there is provided a method of making a temperature resistant polymer composition consisting of 2,5-benzimidazole and at least one binder, the method comprising the steps of:mixing the poly-2,5-benzimidazole with the at least one binder to obtain a dry powder mixture; andcasting the mixture by heating to a temperature in the range between 400°C and 600°C for a time in the range between 0.5 hours and 4 hours and at a pressure in the range between 689475, 72 Pa (1000 psi) and 6894757, 29 Pa (10000 psi) in a die, followed by cooling to obtain a temperature resistant polymer composition in the form of a molded article selected from the group consisting of discs, chips, plates, tubes and rods,wherein the composition is characterized in that the glass transition temperature is in a range between 150 and 480° C.Normally, the binder is at least one compound having a glass transition temperature lower than the glass transition temperature of the poly-2,5-benzimidazole.Normally, the binder is selected from the group consisting of polyether ketone (PEK), polyaryletherketone (PAEK), polyetheretherketone (PEEK), polyetherketoneketone (PEKK), polyphenylene sulfide (PPS), polyetherimide (PEI), polyethersulfone (PES), and polyphenylsulfone (PPSU).Normally, the inherent viscosity (I.V.) of the poly-2,5-benzimidazole is in a range between 1.0 dL / g and 2.5 dL / g.Normally, the inherent viscosity of the binder is in a range between 0.2 dL / g and 1.5 dL / g.In one embodiment of the present disclosure, the ratio of the poly-2,5-benzimidazole to the binder is in a range between 95:5 and 95:5.DETAILED DESCRIPTION:The embodiments herein, as well as various features and advantageous details thereof, are discussed with reference to the non-limiting embodiments in the following description. Descriptions of well-known components and processing methods are omitted so as not to obscure the embodiments herein with unnecessary detail. The examples used herein are intended to enable understanding of the manner in which the embodiments included herein may be practiced and to enable those of ordinary skill in the art to practice the embodiments included herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments included herein.The foregoing description of the specific embodiments will fully uncover the general character of the embodiments herein such that others may readily modify and / or adapt the specific embodiments by applying current knowledge without departing from the preamble. Therefore, these adaptations and modifications are to be understood as belonging to the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the formulations or terminology used herein are for the purpose of description and not of limitation. Thus, while the embodiments herein have been described with reference to the preferred embodiments, those skilled in the art will appreciate that the embodiments herein may be practiced with modification within the spirit and scope of the embodiments described herein.ABPBI is a thermoset polymer that is not melt processable to 500°C due to its very high glass transition temperature (Tg) of 485°C and lack of melting temperature (Tm) to 500°C. It is therefore evident that this polymer is difficult to process, but is extremely stable at high temperatures.The present disclosure solves this problem of difficult processability of the polymer. The present inventors have found that the thermoplastic ABPBI polymer can be rendered processable by blending with a binder. The binder mixed with ABPBI lowers the softening temperature of the ABPBI polymer. Due to the reduced softening temperature, the processing of the ABPBI can be realized. This mixture can be easily processed to produce articles such as gaskets, seals, thrust bearings which would be extremely useful for high temperature, high hardness, chemical and flame retardant applications in the oil and gas industry.According to one aspect of the present disclosure, there is provided a temperature resistant polymer composition comprising poly-2,5-benzimidazole (ABPBI) and at least one binder subjected to compression at a temperature in the range between 400° C. and 600° C. and a pressure in the range between 689475, 72 Pa (1000 psi) and 6894757, 29 Pa (10000 psi). The polymer composition is characterized by a glass transition temperature in the range between 150°C and 480°C.The binder and the amount of binder used in the polymer composition is selected so as to be capable of lowering the softening temperature of the poly-2,5-benzimidazole (ABPBI) to the extent that the ABPBI becomes processable.Furthermore, during the experiments, it was observed that in order to make the ABPBI processable, the glass transition temperature of the binder should be lower than the glass transition temperature of the ABPBI. Still further, the ability of the binder to bond to the ABPBI plays a key role in the extent of lowering the glass transition / softening temperature of the ABPBI.These binders include, but are not limited to, polyether ketone (PEK), polyaryletherketone (PAEK), polyetheretherketone (PEEK), polyetherketoneketone (PEKK), polyphenylene sulfide (PPS), polyetherimide (PEI), polyethersulfone (PES), and polyphenylsulfone (PPSU). The amount of binder is also dependent on the end use of the final material / article. Depending on the use on the one hand and the processing of the ABPBI on the other hand, the ratio of the ABPBI to the binder can therefore vary from 95:5 to 5:95. According to one of the exemplary embodiments of the present disclosure, the ratio of the poly-2,5-benzimidazole to the binder is in a range between 95:5 and 50:50.Furthermore, the intrinsic viscosity (I.V.) and the binder in combination with the amount of the individual constituents of the polymer composition have an effect on the chemical and physical properties of the polymer composition resulting therefrom.In an exemplary embodiment, the composition made from a mixture of ABPBI having an intrinsic viscosity of 1.2 dL / g and polyetherketone having an intrinsic viscosity of 1.0 dL / g in the ratio of 95:5 has different properties compared to a composition made from a mixture of ABPBI having an intrinsic viscosity of 1.8 dL / g and polyetherketone having an intrinsic viscosity of 1.0 dL / g in the ratio of 90:10.Therefore, in order to obtain a polymer composition having predetermined properties, the intrinsic viscosity of the ABPBI may be varied in the range of 1.0 dL / g to 2.5 dL / g, whereas the intrinsic viscosity of the binder may vary in a range of 0.2 dL / g to 1.5 dL / g.According to another aspect of the present disclosure, there is provided a method for preparing a temperature-resistant polymer composition consisting of poly-2,5-benzimidazole (ABPBI) and at least one binder. The polymer composition prepared by the process of the present disclosure has a glass transition temperature that is in the range of 150° C. to 480° C.In the first step, ABPBI having an intrinsic viscosity in the range of 1.0 dL / g to 2.5 dL / g and a fine powder of the binder are mixed in a high-speed mixer to obtain a dry mixture. The binder used for the mixture with ABPBI has a glass transition temperature lower than the glass transition temperature of poly-2,5-benzimidazole and an intrinsic viscosity of 0.2 dL / g to 1.5 dL / g. The binders used include, among others, PEK or PAEK, PEEK, PEKK, PPS, PEI, PES and PPSU, singly or in mixtures. To obtain optimum results, the ratio of ABPBI to binder was maintained between 95:5 and 50:50.In the second step, the mixture was placed in a mold and heated by a ceramic heater belt in a compression molding machine to a temperature in the range between 400°C and 600°C for a period between 0.5 hours and 4 hours and at a pressure in the range between 689475.72 Pa (1000) psi and 6894757.29 Pa (10000 psi).Finally, the mold was cooled in the printing press to obtain a polymer composition. The temperature-resistant polymer composition thus obtained may take any form including discs, chips, plates, tubes, rods and the like.The present disclosure will be further described in light of the following non-limiting examples, which are for illustrative purposes only and are not to be construed as limiting the scope of the disclosure.Example 1:100 g of ABPBI polymer I.V. (inherent viscosity 1.8 dL / g) fine powder having a particle size of <100 microns was placed in a round die having an inner diameter of 110 mm (electrically heated by external heating tapes). The mold was then loaded onto a 50 ton press press (LABTECH LPS-50) and the powder was pressed for 3 hours at 500°C and a pressure of 13789514,58 Pa (2000 psi) in a press mold. It was then cooled to 120°C before the disc was removed from the mould. A 5-6 mm thick round disc having a diameter of 110 mm was ejected for further testing. The disc was found to be very hard and dark green in color. However, cracks were present on the entire surface. Otherwise, the surface was smooth and glossy, but when cut by a circular saw, it was seen that the inner part was not fused or melted at all and maintained a powdery grainy appearance. In addition, the disk split into small pieces during cutting. The edges could even be easily peeled off by hand pressure at the deep cracks.Example 2:Experiment 1 was repeated with ABPBI powder with an I.V. of 1.2 dL / g. A similar disc could be produced which was also hard, dark green in color and difficult to remove from the mold. However, it had more cracks than the specimen of Example 1 and was more prone to chip when cut with a saw. The inner surface was granular, indicating no fusion or melt had occurred.Example 3: Example 3:Fine powder of ABPBI (I.V. 1.2 dL / g) was dry blended in a high speed mixer with fine powder of PEK (I.V. 1.0, G-PAEK) at a ratio of 95:05 for 5 minutes. The mixture was poured into a cylindrical casting mold having an inner diameter of 110 mm and heated by ceramic heating belts. The mold was then loaded onto a 50 ton press (LABTECH LPS-50), the powder was pressed for 1 hour at 500°C and a pressure of 13789514,58 Pa (2000 psi) in the press. Then, after cooling, the molded disk was removed and tested for storage modulus by dynamic mechanical analysis, Taber abrasion test, (weight loss), and hardness after the specimen was cut into the required shape. It was observed that the ABPBI disk thus produced did not split upon cutting, and it was found that the inner surface was completely fused. No larger cracks or chips were observed on the surface of the disc.Example 4: Example 4:Example 3 was repeated with compression molding for a compression time of 2 hours. The cooled disc could be removed from the mould without breakage and cut by a circular saw without fragments. It has been found that the inner surface is smooth and fused under these conditions.Example 5: Example 5:Example 3 was repeated with compression molding for a compression time of 3 hours. The cooled disc could be removed from the mould without breakage and cut by a circular saw without fragments. It has been found that the inner surface is smooth and fused under these conditions.Examples 6, 7 and 8:Examples 3, 4 and 5 were repeated using ABPBI having an I.V. of 1.8 dL / g mixed with PEK having an I.V. of 1.0 dL / g in the ratio of 90:10. The molded disks were lathe machined to produce the specimens. It was observed that the ABPBI molded disks were very hard and somewhat difficult to machine. The machining tool was also worn out when the disk was cut. The inner surface was found to be completely fused and molten. The solidified polymer had no granular and powdery appearance.Example 9:Example 3 was repeated at temperatures of 400°C (Example 7), 450°C (Example 8) and 500°C (Example 9), except that a mixture of 90% ABPBI and 10% PEK was used. The sheets thus prepared were well fused, hard and cut into specimens.Example 10:Example 3 was performed with 5% PEEK as binder of ABPBI instead of PEK. The molding was done at 450°C and the disc was cooled to 120°C and ejected. Ejection was easy and the color of the disc was lighter than the color of all other compositions containing PEK and PEKK.Example 11:Example 3 was performed with PEEK as binder instead of PEK. 5% PEKK powder was mixed with 95% ABPBI powder having an I.V. of 1.8 dL / g and compression molded at 450° C. and a pressing time of 1 hour. The part was easily ejected and had a dark brown color. It did not show any cracks and did not break during the processing.Example 12:Example 3 was carried out with PES (polyethersulfone) as binder instead of PEK. 5% PES powder was mixed with 95% ABPBI powder having an I.V. of 1.8 dL / g and compression molded at 450° C. for 1 hour. The disc could be ejected and showed no signs of cracking.Example 13:5 % PEK having an intrinsic viscosity of 0.7 dL / g (G-PAEK 1400P) was used as a binder instead of 5% PEK having an intrinsic viscosity of 1.0 dL / g as described in Example 3. The product could be ejected well and had good Taber abrasion resistance.Examples 14 to 23:A dry mixture of ABPBI:PEK (1.0 dL / g I.V.) was prepared in the ratio of 95:5 and compression molded at 450°C for 1 hour at 13789514,58 Pa (2000 psi) (Example 14).Additional compositions of ABPBI: PEK were also prepared as below and prepared at 450°C for 1 hour at a pressure of 13789514,58 Pa (2000 psi).ABPBI: PEK (90:10) - Example 15ABPBI: PEK (80:20) - Example 16ABPBI: PEK (70:30) - Example 17ABPBI: PEK (60:40) - Example 18ABPBI: PEK (50:50) - Example 19ABPBI: PEK (40:60) - Example 20ABPBI: PEK (30:70) - Example 21ABPBI: PEK (20:80) - Example 22ABPBI: PEK (10:90) - Example 23In all the above cases, strong whole disks could be ejected without cracks or chips, and they could be cut into the test pieces required for various tests.Example 24:A composition of 60% PEK with an I.V. of 1.0 dL / g and 40% ABPBI with an I.V. of 1.8 dL / g was compression molded at 500°C for 1 hour at a pressure of 13789514,58 Pa (2000 psi). The disc could be ejected well. The surface was very smooth and there were no cracks or chips on one of the edges or surfaces. For some samples, Taber abrasion resistance was examined, and the values are shown in Table 1.(Friction roller used: CS-17, load: 1 kg, Abrasion cycle number: 1000 cycles)Table 1: Comparative Taber Rub Test Study for up to 5000 cycles for the ABPBI disks prepared by the method of the present disclosure: Table 1: Comparative Taber Rub Test Study for up to 5000 cycles for the ABPBI disks prepared by the method of the present disclosure:3193752657541835485570514133145611013.123.236.544.1541123.738.460.287.8107.81213.524.5031.041.752.91315.131.337.453.769.11418.629.345.660.475.61523.344.557.575.194.11623.344.557.575.194.11716.230.644.355.665.81811.219.229.337.444.31912.125.234.640.449.22019.733.441.848.456.62110.319.628.840.149.82214.726.941.152.4662319.538.74976.688.7241012273040In general, ABPBI alone exhibited more attrition compared to ABPBI associated with PEK. The higher the PEK content, the lower the abrasion and the greater the abrasion resistance. ABPBI functions as a polymeric particulate filler in the matrix, which is bound by the presence of PEK. The higher the PEK content, the better the bond and the lower the abrasion loss normally. It is important that the addition of a binder is necessary for the production of compression-molded ABPBI. PEEK and PES as binders also ensure lower abrasion losses. Thus, a binder with a higher flow rate and lower melting point may provide better wetting of the matrix and thus better bonding.PEK with a lower I.V. (0.7 dL / g) resulted in lower abrasion loss compared to PEK with a higher I.V. (1.0 dL / g) due to better binding. Table 2: Dynamic Mechanical Analysis (DMA) of ABPBI and PEK samples Table 2: Dynamic Mechanical Analysis (DMA) of ABPBI and PEK samplesABPBI / PEK - (95 / 5)Example 330152709211713891186464ABPBI / PEK - (40 / 60)Example 1217011497333164-175PEK (unfilled)122085777--170ABPBI485From the dynamic mechanical analysis and the results shown in Table 2, it is seen that the glass transition temperatures (Tg) of PEK and ABPBI are 170°C and 485°C, respectively, whereas the Tg of the composition containing ABPBI and PEK in the ratio of 95:5 is 464°C and the Tg of the composition containing ABPBI and PEK in the ratio of 40:60 is 175°C.Therefore, it is found that the glass transition temperature of ABPBI is lowered by the inclusion of a binder such as PEK, PEEK, PEKK, PES and PAEK, thereby rendering the resulting polymer composition processable. In other words, the ABPBI shapes so produced maintain a high level of storage modulus or stiffness until 400°C, indicating their usefulness at higher temperatures.Technical Development and Economic ImportanceThe method of processing a high temperature resistant thermoset material, ABPBI, according to the present disclosure has several technical advancements including, but not limited to, the realization of:Use of simple but effective techniques for overcoming the inherent physical barriers of high temperature resistant thermoset materials.A cost-effective solution for processing high-temperature-resistant thermosetting materials.A relatively simple and inexpensive process to obtain a precursor that can possibly replace the currently used, comparatively expensive counterparts such as metals and the like.Throughout the specification, the terms "include" or variations thereof such as "includes" or "including" are to be understood to imply the inclusion of the stated element, integer or step, or group of elements, integers or steps, but do not exclude another element, integer or step or group of elements, integers or steps.The use of the phrase "at least" or "at least one" indicates the use of one or more elements or ingredients or amounts, as used in the embodiment of the disclosure, to achieve one or more of the desired goals or results. Any explanation of documents, acts, materials, devices, articles, or the like included in this specification is provided solely for the purpose of providing the context of the disclosure. It is not to be taken as an admission that any or all of these contents form part of the prior art or general knowledge in the field relevant to the disclosure, since they already existed before the priority date of this patent application.The numerical values recited for the various physical parameters, dimensions, or amounts are only approximate values, it is contemplated that values higher / lower than the numerical values assigned to the parameters, dimensions, or amounts fall within the scope of the disclosure, unless there are any statements to the contrary in the specification.While considerable emphasis has been placed herein on the individual features of this disclosure, it will be understood that various modifications may be made and that many changes may be made in the preferred embodiments without departing from the principles of the disclosure. These and other modifications, within the meaning of the disclosure or the preferred embodiments, will become apparent to persons skilled in the art from the disclosure presented here, it being expressly understood that the above description is to be interpreted solely as illustrative of the disclosure and not as restrictive.

Claims

A temperature resistant polymer composition comprising: a. poly-2,5-benzimidazole having an inherent viscosity (I.V.) between 1.0 dL / g and 2.5 dL / g; and b. at least one binder having a glass transition temperature lower than the glass transition temperature of the poly-2,5-benzimidazole and an inherent viscosity in the range between 0.2 dL / g and 1.5 dL / g subjected to compression at a temperature in the range between 400°C and 600°C and a pressure in the range between 689475, 72 Pa (1000 psi) and 6894757.29 Pa (10000 psi), the composition being characterized by: i. a glass transition temperature in the range between 150 and 480°C; and ii. a ratio of the poly-2,5-benzimidazole to the binder in a range between 95:5 and 5:95.The polymer composition of claim 1, wherein the binder is selected from the group consisting of polyether ketone (PEK), polyaryletherketone (PAEK), polyetheretherketone (PEEK), polyetherketoneketone (PEKK), polyphenylene sulfide (PPS), polyetherimide (PEI), polyethersulfone (PES), and polyphenylsulfone (PPSU).The polymer composition of claim 2, wherein the binder is selected from the group consisting of polyetheretherketone (PEEK) and polyethersulfone (PES).A process for the preparation of a temperature resistant polymer composition consisting of 2,5-benzimidazole and at least one binder according to claim 1, said process comprising the steps of: - mixing poly-2,5-benzimidazole and at least one binder to obtain a mixture; and - casting said mixture by heating to a temperature in the range between 400°C and 600°C for a time in the range between 0.5 hours and 4 hours and at a pressure in the range between 689475, 72 Pa (1000 psi) and 689475, 29 Pa (10000 psi), followed by cooling to obtain a temperature resistant polymer composition in the form of a shaped article selected from the group consisting of discs, chips, plates, tubes and bars, said composition being characterized in that, wherein the glass transition temperature is in a range between 150 and 480° C., wherein the binder is at least one compound having a glass transition temperature lower than the glass transition temperature of the poly-2,5-benzimidazole, wherein the inherent viscosity (I.V.) of the poly-2,5-benzimidazole is in a range between 1.0 dL / g and 2.5 dL / g, wherein the inherent viscosity of the binder is in a range between 0.2 dL / g and 1.5 dL / g, wherein the ratio of the poly-2,5-benzimidazole to the binder is in a range between 95:5 and 5:95.The method of claim 4, wherein the binder is selected from the group consisting of polyether ketone (PEK), polyaryletherketone (PAEK), polyetheretherketone (PEEK), polyetherketoneketone (PEKK), polyphenylene sulfide (PPS), polyetherimide (PEI), polyethersulfone (PES), and polyphenylsulfone (PPSU).