Polyimide: Composition, method of production, and components produced therefrom

Abstract

A polyimide composition comprising particles of a polyimide polymer derived from (i) ODA, (ii) PMDA, (iii) PPD, and (iv) BPDA monomers, wherein, if the polyimide composition consists of particles of the polyimide polymer, the polyimide composition has an apparent density of 0.25 g / cubic centimeter or less.

Description

[Technical Field]

[0001] Cross-reference of related applications none.

[0002] The present invention generally relates to polyimide compositions, components manufactured from polyimide compositions, and methods for manufacturing polyimide compositions and components. [Background technology]

[0003] Components manufactured from polyimide compositions are well known. For example, components have been manufactured from polyimide compositions derived from 4,4'-oxydianaline (ODA) and pyromellitic dianhydride (PMDA), and separately from p-phenylenediamine (PPD), m-phenylenediamine (MPD), and biphenyltetracarboxylic dianhydride (BPDA). However, with the increasing demand for higher performance and more demanding applications, the limitations of polyimides derived from these polyimides have become apparent. For example, improved toughness is desired from components derived from these polyimide compositions in some applications. Increased toughness can be equivalent to an improved product life in use. The higher toughness of the polymer also provides design engineers with greater flexibility in designing components that can withstand more demanding operating conditions than might be achievable with brittle polymers.

[0004] One such application where improved toughness is desired in polyimide parts is in clutches for primary and secondary transmissions. Polyimide can be formed into rollers that can be used in clutches (clutch rollers). As engines continue to become more powerful, clutch rollers manufactured from existing polyimide materials are subjected to greater stress, and these more demanding conditions are causing some polyimide parts to fail sooner than desired, resulting in costly repairs. [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] Therefore, there is a need for a novel polyimide composition and a method for producing the polyimide composition that provides improved toughness when molded into parts such as clutch rollers. [Means for solving the problem]

[0006] The present invention relates to a polyimide composition comprising particles of a polyimide polymer derived from (i) ODA, (ii) PMDA, (iii) PPD, and (iv) BPDA monomers, wherein, in the case where the polyimide composition consists of particles of the polyimide polymer, the polyimide composition has an apparent density of 0.25 g / cubic centimeter or less.

[0007] The present invention comprises the steps of: (i) combining ODA, (ii) PMDA, (iii) PPD, (iv) BPDA, and (v) a solvent for a sufficient time and under conditions to form a reaction product mixture containing polyamide and a solvent; heating the reaction product mixture at a temperature of 110°C or higher for a sufficient time to form solid polyimide particles and remove water; filtering and washing the formed solid polyimide particles to form washed solid polyimide particles; and drying the washed solid polyimide particles to 0.25 g / cm³. 3 The present invention relates to a step of forming a polyimide composition comprising dried polyimide particles having an apparent density of less than a certain density, and a method for producing a polyimide composition comprising such a composition.

[0008] The present invention further relates to a component formed from a polyimide composition comprising particles of polyimide polymers derived from (i) ODA, (ii) PMDA, (iii) PPD, and (iv) BPDA monomers, wherein, in the case where the polyimide composition consists of particles of polyimide polymers, the polyimide composition has an apparent density of 0.25 g / cubic centimeter or less.

[0009] The present invention provides polyimide compositions that can be formed into parts having increased toughness and density, and that provide improved lifespan in applications involving the ability to withstand greater stress during typical use. The present invention further provides polyimide compositions having improved friction resistance or lubricity. [Brief explanation of the drawing]

[0010] [Figure 1] This represents friction and abrasion test materials machined to specific shapes and sizes for testing in a Falex apparatus. [Figure 2] The graph shows the tensile strength of sintered parts plotted against %BPDA and %PPD in the tested polymers. Outlined symbols represent polymer compositions formed by blending BPDA-PPD homopolymers and PMDA-ODA homopolymers in various proportions. Filled symbols represent various copolyimide compositions of the present invention. The tensile strength of the copolymers is significantly higher than that of blended polymers having the same monomer composition. [Figure 3] The graph shows the % elongation at break of the sintered part plotted against %BPDA and %PPD in the polymer being tested. Out-of-focus symbols represent polymer compositions formed by blending BPDA-PPD homopolymers and PMDA-ODA homopolymers in various proportions. Filled-in symbols represent various copolyimide compositions of the present invention. The elongation of the copolymer is significantly higher than that of blended polymers having the same monomer composition. [Figure 4] This graph shows the polymer toughness of sintered parts plotted against %BPDA and %PPD in the polymer being tested. Outlined symbols represent polymer compositions formed by blending BPDA-PPD homopolymers and PMDA-ODA homopolymers in various proportions. Filled symbols represent various copolyimide compositions of the present invention. The toughness of the copolymers is significantly higher than that of blended polymers having the same monomer composition. [Modes for carrying out the invention]

[0011] As used herein, "BPDA" means biphenyltetracarboxylic dianhydride, "PMDA" means pyromellitic dianhydride, "PPD" means p-phenylenediamine, and "ODA" means 4,4'-oxydianiline.

[0012] As used herein in connection with polyimides, "homopolymer" means a polymer having the same repeating unit throughout the polymer backbone, formed from the reaction of a dianhydride and a diamine. A polyimide composition comprising particles of a polyimide derived from (i) ODA, (ii) PMDA, (iii) PPD, and (iv) BPDA monomers, wherein when the polyimide composition consists of particles of a polyimide polymer, the polyimide composition has an apparent density of 0.25 g / cubic centimeter or less.

[0013] ODA, PMDA, PPD, and BPDA are as defined above.

[0014] A polyimide is a polymer containing repeating units having imide functional groups. Those skilled in the art will know what polyimides and imide functional groups are. Particles of polyimide are derived from (i) ODA, (ii) PMDA, (iii) PPD, and (iv) BPDA monomers, for example, as described below for methods of making polyimide compositions. Those skilled in the art will know methods of deriving particles of polyimide based on the methods described below. The size, shape, and morphology of the particles of polyimide can vary depending on the ratio of the monomers used and the conditions used in the process. One measure of the size, shape, and morphology of the particles of polyimide is the apparent density. The particles of polyimide are less than 0.25 g / cm 3 or less, or 0.10 g / cm 3 ~0.25 g 3 or, or 0.15 g / cm 3 ~0.25 g / cm 3 or, or 0.10 - 0.20 g / cm 3has an apparent density. The apparent density is measured as described in the Examples and relates to particles of polyimide without the addition of a filler or any other additive. For example, the apparent density of particles of polyimide can be measured using a volumeter using the test method described in ASTM-D1895-17, entitled "Standard Test Methods for Apparent Density, Bulk Factor, and Pourability of Plastic Materials." The addition of a filler can change the apparent density such that the apparent density of the polyimide composition is changed. Thus, when a filler is included in the polyimide composition, the apparent density refers to particles of polyimide derived from the same monomer ratio, using the same process and conditions but without the addition of a filler. The apparent density is a measure of the particle morphology, which is thought to affect the ability of the polyimide particles to form strong parts with sufficient specific gravity.

[0015] As used herein, "when a polyimide composition consists of particles of a polyimide polymer" means that the polyimide composition contains only particles of the polyimide polymer and does not contain any other added materials, excluding residual materials such as unreacted reactants and / or impurities. The particles of the polyimide and / or polyimide composition may contain additional materials such as a filler. However, when the polyimide composition contains a filler, the particles and / or polyimide composition have an apparent density of 0.25 g / cubic centimeter or less if they are produced without a filler using the same monomers, monomer ratios, conditions, and process used to produce the polyimide composition with the filler.

[0016] In one embodiment, a component made from a polyimide composition has greater toughness than a component made from a mixture of polymers A) and B), in which case polymer A) is derived only from ODA and PMDA monomers, polymer B) is derived only from PPD and BPDA monomers, and the molar ratio of ODA, PMDA, PPD, and BPDA in the component made from the polyimide composition is the same as in the mixture of homopolymers A) and B).

[0017] As used herein, “part” has the meaning typically known in the art. In one embodiment, the part is a clutch roller. Examples of parts, but not limited to, include seal rings, spherical washers, compressor seals, ball bearing cages, planetary gear set washers for electric vehicles, transmission washers for replacing metal thrust needle bearings, main or lower bearings in scroll compressors used in heating and air conditioning applications, valve seats or poppets in high-pressure gas valves, friction or wear parts in wind turbines, and variable stator vanes (VSVs) or variable pre-stator vanes (VIGVs) in jet engine compressors. Parts may be used in the aerospace, transportation, and industrial fields. The polyimide compositions of the present invention may be used as sealing devices in electrochemical batteries such as lithium batteries. Films may be manufactured by methods known in the art. Those skilled in the art will know how to mold polyimide compositions to form parts.

[0018] The toughness of a material and / or component is defined by its ability to absorb energy and deform plastically without breaking. This is also defined as the amount of energy per unit volume that the material can absorb before it ruptures. Another definition is the resistance that the material gives to breaking when stress is applied. Toughness is determined by calculating the area under a stress-strain curve where stress is on the y-axis and strain is on the x-axis. Those skilled in the art will know how to determine the stress and strain of a component made from a polyimide composition. For the purposes of this invention, toughness was determined and recorded for a tensile dogbone-shaped test specimen under tensile stress. The tensile stress-strain curve of the dogbone-shaped polyimide was obtained using an Instron testing machine. Toughness was obtained by numerically integrating the area under the stress-strain curve and recorded in Ksi units.

[0019] A method for producing a polyimide composition, (i) a step of combining ODA, (ii) PMDA, (iii) PPD, (iv) BPDA, and (v) a solvent for a sufficient time and under conditions to form a reaction product containing polyamide and solvent, A step of removing water and heating the reaction product to a temperature and time sufficient to form polyimide particles, A process of filtering and washing the polyimide particles, A step of drying washed polyimide particles to form a polyimide composition, wherein the polyimide composition comprises polyimide particles, A method for producing a polyimide composition having an apparent density of 0.25 g / cubic centimeter or less, where the polyimide composition consists of particles of a polyimide polymer.

[0020] (i) ODA, (ii) PMDA, (iii) PPD, (iv) BPDA, and (v) the solvent are combined for a sufficient amount of time and under conditions to form a reaction product comprising the polyamide and the solvent. As used herein, “polyamide” includes polyamic acids. Methods known in the art can be used to combine the monomers.

[0021] The temperature at which monomers (i) to (iv) and the solvent are combined is a temperature sufficient to cause the reaction, or from room temperature to high temperature, or at room temperature, or from room temperature to 120°C, or from high temperature to 90°C, or between 50 and 80°C.

[0022] The polyamide reaction product is subjected to sufficient conditions, or heated, or heated at temperatures of 70°C to 190°C, 110°C to 170°C, or 110°C to 150°C to convert the polyamide to insoluble polyimide and remove water. Heating can be carried out under high pressure in a high-pressure vessel such as a Parr reactor. Those skilled in the art will know the method of converting polyamide to polyimide by heating in a solvent.

[0023] The combining and heating processes may be carried out in the same or different containers, or in separate containers.

[0024] The polyimide particles are filtered and washed. The polyimide is filtered using methods known in the art. For example, the polyimide and solvent may be passed through a Buchner funnel to recover the polyimide. Those skilled in the art will know how to filter polyimide. The polyimide is washed with a solvent and dried. Those skilled in the art will know how to wash and dry polyimide. The polyimide slurry is dried at a temperature of 100°C to 230°C, or 140°C to 190°C, or about 180°C to convert it into a polyimide resin in the form of powder (or particles). Filtration and washing are typically carried out in a container separate from the combining and reaction steps.

[0025] If the polyimide composition consists of particles of polyimide polymer, the polyimide composition has an apparent density of 0.25 g / cubic centimeter or less, as described above in this specification.

[0026] A method for producing a polyimide composition may further include a step of combining a filler with the reaction product before or during the heating step. The filler is described further herein. The filler can alter the apparent density of the polyimide particles. Apparent density relates to unfilled polyimide compositions and unfilled particles.

[0027] Polyimides can be derived from (i) ODA, (ii) PMDA, (iii) PPD, and (iv) BPDA monomers using, for example, a solution imidation process according to one embodiment. Diamines (PPD and ODA) are generally first dissolved in a solvent to form a diamine component. Generally, after dissolving the diamine component in the solvent to the required concentration, dianhydrides (BPDA and PMDA) are added to the reaction solution in substantially equimolar amounts to form a polyamic acid (PAA) polymer solution. In one embodiment, the polyimide polymer may have a slight molar excess of either the dianhydride component or the diamine component, or a 0.5-1.0% molar excess of the diamine component, which has been found to yield good results. In another embodiment, equimolar diamine and dianhydride close stoichiometry are used. The resulting PAA polymer solution is transferred to a heated solution of solvent over time. The transferred PAA polymer solution is continuously heated and stirred to complete the reaction of the soluble PAA and obtain an insoluble polyimide slurry. The resulting polyimide slurry is washed with a solvent and dried at 100°C to 230°C, or 110°C to 190°C, or 110°C to 150°C to convert the polyimide slurry into a polyimide resin in the form of a powder or particles with a high surface area. The optimal temperature results in higher process efficiency and better physical properties, such as the apparent density of the particles or parts produced from the polyimide particles.

[0028] The solvent can be any organic solvent, but is not limited to those listed above, that does not react to the extent that its functional groups are recognizable to either the reactants (anhydride or diamine). The solvent can have a pH of about 8 to about 10, which can be measured by mixing the solvent with a small amount of water and then measuring it with pH paper or a probe. Examples of such solvents include pyridine. Other solvents that do not necessarily have a pH of 8 to 10 may be used, and the pH of the solvent may be altered by adding additives such as β-picoline. Examples of solvents that can be used, but are not limited to these, include dimethylacetamide (DMAC), n-methyl-2-pyrrolidone (NMP), dimethyl sulfoxide (DMSO), and β-picoline, and mixtures thereof. Among the solvents disclosed in U.S. Patent No. 3,179,614 by Edwards of Galland, pyridine (K=1.4×10) is a preferred solvent for these reactants in the polymerization reaction, as it functions as a catalyst. A basic catalyst is required for the dianhydride and diamine to react to form the PAA polymer solution. Since pyridine is a basic compound, it functions as both a catalyst and a solvent.

[0029] The amount of solvent is important for obtaining a product with ideal particle size, low apparent density, and high surface area. In particular, the solvent must be present in such an amount that the concentration of the PAA polymer solution is about 1 to 15% by weight of solids, preferably about 5 to about 12% by weight of solids. Those skilled in the art will be familiar with the process of producing polyimide compositions and the method of selecting an appropriate amount of solvent.

[0030] In one embodiment, a component made from a polyimide composition has greater toughness than a component made from a mixture of polymers A) and B), in which case polymer A) is derived from ODA and PMDA monomers, polymer B) is derived from PPD and BPDA monomers, or B) is derived from PPD, MPD, and BPDA, and the molar ratio of ODA, PMDA, PPD, and BPDA in the polyimide is the same as that in a mixture of polymers A) and B).

[0031] Polymer A) is derived from ODA and PMDA monomers, in which case the molar ratio of ODA and PMDA in polymer A) is the same as that in polyimide compositions derived from ODA, PMDA, PPD, and BPDA used to manufacture parts. Polymer B) is derived from PPD and BPDA monomers, or B) is derived from PPD, MPD, and BPDA, in which the molar ratio of PPD and BPDA monomers is the same as that in polyimide compositions derived from ODA, PMDA, PPD, and BPDA used to manufacture parts.

[0032] Examples of polymer A include polymers manufactured with an ODA to PMDA molar ratio of approximately 45:55 to 55:45, or approximately 50:50. Examples of polymer B include polymers manufactured with a PPD to BPDA molar ratio of approximately 45:55 to 55:45, or approximately 50:50.

[0033] Polymers A) and B) are produced according to the methods for producing polyimide compositions described and illustrated herein. To produce parts from polymers A) and B), a physical mixture of polymer A) and B) particles is produced by mixing them using a typical mixing apparatus for producing polyimide particles. The physical mixture is then formed into parts by molding the mixture under conditions sufficient to form parts, or at high pressure and ambient temperature as described below for the polyimide composition, or at ambient temperature at a pressure of about 20,000 to 100,000 psi (345 to 690 MPa), or preferably 50,000 to 100,000 psi.

[0034] A polyimide composition comprising a polyimide derived from (i) ODA, (ii) PMDA, (iii) PPD, and (iv) BPDA monomers, wherein a component manufactured from the polyimide composition has a specific gravity greater than that of a mixture of polymer A) and polymer B), polymer A) is derived from ODA and PMD monomers, polymer B) is derived from PPD and BPDA monomers, and the molar ratios of ODA, PMDA, PPD, and BPDA in the polyimide are the same as in the mixture of polymer A) and polymer B).

[0035] The monomers ODA, PMDA, PPD, BPDA, polymers A) and B), and the molar fraction of ODA of ODA, PMDA, PPD, and BPDA are as described above.

[0036] The specific gravity is as known in the art. A person skilled in the art will understand the method of measuring and calculating the specific gravity of a component. In one embodiment, the specific gravity is 3 from 0.138 g / cm 3 to 1.54 g / cm 3 and greater.

[0037] The specific gravity refers to the specific gravity of a component manufactured from the polyimide composition without adding other additives such as fillers. Fillers and other additives can change the specific gravity. However, the specific gravity of a component manufactured from the filled polyimide composition will be greater than the specific gravity of a component manufactured from a mixture of polymers A and B. When a filler is included in the polyimide composition, the specific gravity of the component refers to the specific gravity of a component formed from a polyimide composition having the same monomer ratio, using the same process and conditions but without the addition of a filler.

[0038] The specific gravity mya measured according to methods known in the art. A person skilled in the art will understand the method of measuring the specific gravity. The specific gravity of a component is calculated herein by the following formula:

Number

[0039] A polyimide composition comprising a polyimide derived from (i) ODA, (ii) PMDA, (iii) PPD, and (iv) BPDA monomers, wherein the total molar fraction of BPDA and PMDA is about 1, the total molar fraction of PPD and ODA is about 1, and the relationship between the molar fraction of BPDA based on dianhydride and the molar fraction of PPD based on diamine is PPD - 0.2 < BPDA, 0.05 < BPDA < 0.95, and 0.05 < PPD < 0.95.

[0040] In one embodiment, the total molar fraction of BPDA and PMDA is about 1, the total molar fraction of PPD and ODA in the polyamide is about 1, and the relationship between the molar fraction of BPDA based on dianhydride and the molar fraction of PPD based on diamine is, optionally, PPD - 0.2 < BPDA, 0.05 < BPDA < 0.95, and 0.05 < PPD < 0.95. The molar fraction of BPDA is based on total dianhydride, and the molar fraction of PPD is based on total diamine.

[0041] In one embodiment, the molar % of BPDA relative to other monomers combined to produce the polyimide particles is greater than or equal to (mol% of PPD + 0.2) (≧(mol% of PPD + 0.2)). This molar % of BPDA will produce parts with sufficient toughness.

[0042] Those skilled in the art know how to calculate the molar % and molar fractions of monomers that fall within the described ranges and will modify the manufacturing methods described above to produce polyimides having the described monomer fractions and molar %.

[0043] In one embodiment, the parts produced from the polyimide composition have a toughness greater than 0.80 Ksi, or greater than 0.85 Ksi, or between 0.80 Ksi and 5 Ksi, or between 0.80 Ksi and 1.5 Ksi, or between 0.85 Ksi and 1.0 Ksi.

[0044] Toughness refers to the toughness of a part manufactured from polyimide particles without the addition of fillers or other additives. Fillers and other additives can affect toughness. Therefore, when fillers are included in a polyimide composition, as used herein, the toughness of a part refers to the toughness of a part formed from a polyimide composition derived from the same monomer ratio and using the same process and conditions but without the addition of fillers.

[0045] The method for manufacturing parts from ODA, PMDA, PPD, BPDA, and polyimide compositions, and for determining the toughness of the parts, is as described above. Those skilled in the art will know the method for determining the toughness of parts derived from the monomers listed above.

[0046] (i) Derived from ODA, (ii) PMDA, (iii) PPD, and (iv) BPDA monomers, the following repeating units [ka]

[0047] A polyimide composition containing one or more of the following:

[0048] The surface area of ​​the polyimide in the polyimide composition of the present invention is typically at least 20 m². 2 The value is / g. The surface area is at least about 75m² to achieve acceptable physical properties and ease of processing. 2 It is preferable that it be / g.

[0049] The average molecular weight (Mw) of polyimides measured by GPC is greater than 50,000 g / mol, preferably greater than 100,000 g / mol, or greater than 150,000 g / mol. Those skilled in the art will know methods for determining and controlling the molecular weight during the preparation of polyimides.

[0050] In one embodiment, the polyimide composition further comprises fillers. Examples of fillers, but not limited to these, include carbonaceous fillers such as graphite and carbon fibers, and inorganic fillers such as kaolinite clay, molybdenum sulfide, tungsten sulfide, and boron nitride, for improving wear and friction properties while maintaining the excellent mechanical properties and oxidative stability of the polyimide, as well as polymeric fillers such as tetrafluoroethylene polymers and copolymers. In addition to improving wear and friction properties, fillers may also be added to affect other properties of the polymer, such as increasing the hardness or stiffness of the polymer and polymer-derived parts, but not limited to these. Fillers may be present in amounts ranging from 0.1% to 80% by weight. The specific filler or filler selected, and the amount used, naturally depend on the desired effect in the final composition, as will be apparent to those skilled in the art. Typically, these fillers are incorporated into a heated solvent before the transfer of the PAA polymer solution, resulting in the precipitation of the polyimide in the presence of the incorporated fillers. The form of the filler depends on its function in the final product. For example, the filler can be in the form of fine particles or fibers.

[0051] After adding the filler, the apparent density is 0.25 g / cm³. 3 It's extremely possible.

[0052] A component comprising the polyimide composition described above, with a toughness of 0.80 Ksi or higher and a density of 1.38 g / cm². 3 A specific gravity of the above, or a toughness of 0.80 Ksi or higher, and 1.4 g / cm². 3 The component has the above specific gravity. Its toughness and specific gravity are as described above.

[0053] Polyimide compositions can be molded into a wide variety of configurations under high pressure to form parts, or parts can be formed by cold compact molding, which is then heated to temperatures above 400°C, or parts can be manufactured by hot pressing the polyimide composition to which high pressure and temperature are applied simultaneously. It has been found that molding the polyimide composition at ambient temperature under pressures of approximately 50,000 to 100,000 psi (345 to 690 MPa) is particularly advantageous. Lower pressures can be used, but this may increase the porosity of the final part and impair the strength of the part. Those skilled in the art will know the polyimide compositions of the present invention and methods for manufacturing molded parts from polyimide compositions produced by the methods of the present invention.

[0054] Parts manufactured from the polyimide composition of the present invention, further comprising fillers, exhibit at least 50%, 75%, or 100% lower wear compared to parts manufactured from mixtures of polymers A and B described above, having the same monomer composition and fillers as the polyimide composition. Wear is determined by the procedure described in the Examples section.

[0055] The present invention may include the following embodiments: 1. A polyimide composition comprising (i) a polyimide derived from ODA, (ii) PMDA, (iii) PPD, and (iv) BPDA monomers, having an apparent density of 0.25 g / cubic centimeter or less. 2. The parts manufactured from the polyimide composition have a toughness of more than 0.80 Ksi and a density of 1.4 g / cm². 3 A polyimide composition according to embodiment 1 having the following specific gravity. 3. A polyimide composition comprising a polyimide derived from (i) ODA, (ii) PMDA, (iii) PPD, and (iv) BPDA monomers, wherein the polyimide has a specific gravity greater than that of a mixture of polymer A) and polymer B), polymer A) is derived from ODA and PMD monomers, polymer B) is derived from PPD and BPDA copolymers, and the molar fractions of ODA, PMDA, PPD, and BPDA in the polyimide are the same as those in the mixture of polymer A) and polymer B). 4. A part manufactured from the polyimide composition has a specific gravity greater than 1.4 g / cm 3 The polyimide composition according to aspect 3. 5. A polyimide composition comprising a polyimide derived from (i) ODA, (ii) PMDA, (iii) PPD, and (iv) BPDA monomers, wherein the sum of the molar fractions of BPDA and PMDA is about 1, the sum of the molar fractions of PPD and ODA is about 1, and the relationship between the molar fraction of BPDA and the molar fraction of PPD is PPD - 0.2 < BPDA, 0.05 < BPDA < 0.95, and 0.05 < PPD < 0.95. 6. A polyimide composition comprising a polyimide derived from (i) ODA, (ii) PMDA, (iii) PPD, and (iv) BPDA monomers and containing one or more of the following repeating units [Chemical formula]

[0056] 7. A polyimide composition comprising a polyimide derived from (i) ODA, (ii) PMDA, (iii) PPD, and (iv) BPDA monomers, wherein a part manufactured from the polyimide composition has a toughness greater than 0.80 Ksi. 8. A polyimide composition comprising a polyimide derived from (i) ODA, (ii) PMDA, (iii) PPD, and (iv) BPDA monomers, wherein a part manufactured from the polyimide composition has a specific gravity greater than 1.4 g / cm 3 The polyimide composition. ​9. A polyimide composition according to any one of the above embodiments, further comprising a filler. 10. A polyimide composition according to any one of the above embodiments, wherein the molar ratio of diamine monomer to anhydride monomer is about 1. 11. A component comprising the polyimide composition described in any one of embodiments 1 to 10. 12. The part is molded, as described in embodiment 11. 13. The part is a clutch roller, as described in embodiment 10 or 11. 14. A method for producing a polyimide composition, comprising the steps of: combining (i) ODA, (ii) PMDA, (iii) PPD, (iv) BPDA, and (v) a solvent for a sufficient time and under conditions to form a reaction product mixture containing polyamide and a solvent; heating the reaction mixture at a temperature of 110°C or higher for a sufficient time to form polyimide particles and remove water; filtering and washing the solid polyimide particles; and drying the solid polyimide particles to form a polyimide composition containing the solid polyimide particles, wherein the heating temperature of the reaction mixture is 0.25 g / cm³ 3 A method selected to obtain solid polyimide particles having an apparent density of less than a certain value. 15. The method according to embodiment 14, further comprising the step of combining dried polyimide with a filler. 16. The method according to embodiment 14 or 15, further comprising the step of sintering and molding a dried polyamide or dried polyimide and a filler to form a component. 17. The method according to embodiment 16, wherein the part has a toughness greater than 0.80 Ksi. 18. The method according to one embodiment of 16 or 17, wherein the part has a higher specific gravity than a part made from a mixture of polymer A) and polymer B), polymer A) is derived from ODA and PMD monomers, polymer B) is derived from PPD and BPDA, and the molar composition of ODA, PMDA, PPD, and BPDA in the polyimide is the same as in the mixture of polymer A) and polymer B). 19. The component has a weight of 1.4 g / cm³. 3 The method according to any one of embodiments 16 to 18, having a specific gravity of the above. 20. The method according to any one of aspects 14 to 19, wherein the relationship between the molar fraction of BPDA and the molar fraction of PPD is PPD - 0.2 < BPDA < PPD + 0.2, 0.05 < BPDA < 0.95, and 0.05 < PPD < 0.95. 21. A component manufactured according to the method of any one of aspects 16 to 20. 22. The component according to aspect 21, wherein the component is a clutch roller, a seal ring, a spherical washer, a compressor seal, a lip seal, a valve seat, a ball bearing cage, and an operating disk. 23. The component according to aspect 21, wherein the component manufactured from the polyimide composition further containing a filler has at least 50% lower wear compared to the component manufactured from the homopolymers A and B having the same monomer composition and filler.

[0057] The polyimide composition of the present invention forms components having increased toughness and specific gravity. The polyimide composition can be used to manufacture components for applications such as clutch rollers used in power sports vehicles.

Examples

[0058] The following examples are included to demonstrate preferred embodiments of the present invention, but they should not be considered as limiting the present invention as detailed in the appended claims. Those skilled in the art will understand that the techniques disclosed in the following examples represent techniques found by the inventors to function well in the implementation of the present invention and, therefore, may be considered as preferred embodiments for its implementation. However, those skilled in the art should understand that, considering the present disclosure, many modifications can be made to the disclosed specific embodiments without departing from the spirit and scope of the present invention and still obtain the same or similar results. Unless otherwise specified, all percentages are in units of weight %. The following table explains the abbreviations used in the examples.

[0059]

Table 1

[0060] In Examples 1-24 and Comparative Examples 1-2 and 7-13 below, the copolyimide compositions were prepared using a solution imidation process in which a mixture of p-phenylenediamine (PPD) and a diamine derived from 4,4'-oxydianaline (ODA) was reacted in the amounts shown in the Examples with a mixture of dianhydrides derived from 3,3',4,4'-biphenyltetracarboxylic acid dianhydride (BPDA) and pyromellitic acid dianhydride (PMDA). The procedure used was substantially similar to the procedure outlined by Gall in U.S. Patent No. 3,179,631, Endrey in U.S. Patent No. 3,249,588, and Delcolibus in U.S. Patent No. 5,886,129, all of which are incorporated herein by reference for their descriptions relating to the preparation of copolyimide compositions. These are available from U.S. Patent No. 3,179,631, U.S. Patent No. 3,249,588, and Delcolibus in U.S. Patents. Japanese Patent Nos. 5, 886, and 129 (all of which are incorporated herein by reference with respect to their descriptions relating to the preparation of copolyimide compositions) describe the present invention. To illustrate the present invention, both polymerization and imidation were carried out using pyridine as the solvent.

[0061] Polymerization to form polyamic acid (PAA) was carried out in a 500 ml Chemglass round-bottom glass-jacketed reaction vessel with a bottom take-off for draining the completed polyamic acid solution. The reaction vessel was stirred by a Cole-Palmer Servo Dyne Model 50008 overhead stirrer with a boat-type impeller. The temperature inside the reaction vessel was controlled by circulating heat transfer fluid from a Huber Ministat cc3 recirculating heater-condenser. A silicone-based heat transfer fluid stable up to 150°C was used in the circulator.

[0062] A typical theoretical batch size for polymerization involved approximately 60 g of polymer in pyridine anhydride. Unless otherwise specified, polymerization was carried out at a concentration of 10% by weight or solids content in pyridine solvent. The solids content concentration is reported based on the weight of the polyamic acid (PAA) polymer, not the final imidized polymer. In preparation for carrying out polymerization, the target copolymer composition (defined by the mole fraction of monomers), polymer concentration, and % monomer imbalance were fixed. Monomer imbalance is defined by the following formula:

number

[0063] For all exemplary examples presented herein, polymerization was carried out in a diamine-rich environment with monomer imbalance of approximately 0.75%.

[0064] The molecular weight of polyamic acid (PAA) solutions was measured using an Agilent GPC instrument, which included an Agilent 1290 UHPLC stack, binary delivery pump, autosampler, separation column compartment, and UV detector. The GPC was fitted with two stationary phases: two Agilent PLgel 5μm MIXED-C 300mm × 7.5mm columns and one PLgel 5μm guard column 50mm × 7.5mm. The instrument was controlled by Chemstation OpenLabs software with a Cirrus GPC add-on. The columns were calibrated using Agilent-sold polystyrene polymer standard material (Easi Cal PS-1).

[0065] The mobile phase for GPC was prepared by pre-mixing 98.436% dimethylacetamide (DMAc), 0.357% o-phosphate, 0.942% tetrahydrofuran (THF) (unstabilized), and 0.265% lithium bromide (LiBr). All percentages are by weight. The sample injection volume was fixed at 2 μl. The mobile phase flow rate was set to 0.5 ml / min. Elution was isocratic. The GPC pause time was 55 minutes. A UV detector set to detect at 268 nm was used for GPC.

[0066] The imidation of polyamic acid was carried out in a 1000 ml Parr high-pressure reactor equipped with an anchor-type impeller. The PAA solution was transferred to the high-pressure Parr vessel using a Teledyne ISCO 500D pump. After heating the PAA solution in the ISCO pump to 70°C, it was transferred to the high-pressure reactor. The Parr vessel could be heated to 200°C using an electric resistance heater. The imidation temperature in the Parr reactor during PAA transfer and imidation varied in the range of 110°C to 175°C.

[0067] After imidization, small slurry samples were collected for particle size distribution analysis. A Malvern Panalytical Mastersizer 3000 laser scattering instrument was used to determine the PSD of the wet polyimide slurry. Laser scattering measurements were performed in deionized water. All measurements were performed at room temperature, and no ultrasonic energy was used during the measurements.

[0068] The remaining polyimide slurry was transferred to a Buchner funnel for filtration and washing of the copolyimide particles. The filtration rate was controlled to manage the discharge of the pyridine solvent and prevent premature cracking of the filter cake. Just before all the pyridine had been discharged from the filter cake, four volumes of clean acetone were added to the filter cake for replacement washing. After all the solvent had been discharged from the filter cake, the moistened filter cake was left in a ventilated hood to air dry for about an hour, and then transferred to a 175°C vacuum oven to dry overnight.

[0069] The apparent density of the pulverized copolyimide powder was measured using a volumetric instrument with the test method described in ASTM-D1895-17, titled "Standard Test Methods for Apparent Density, Bulk Factor, and Pourability of Plastic Materials."

[0070] The specific surface area of ​​the dried copolyimide powder sample was measured using the BET method described by S. Brunauer, PHEmmett, and E. Teller in the Journal of the American Chemical Society, Volume 60, 309 (1938). Before testing, the sample was degassed at 120°C for 12 hours at less than 100 μmHg. Nitrogen adsorption / desorption measurements were performed at 77.3 K using a Micromeritics ASAP Model 2420 porosimeter. Surface area measurements were analyzed using the BET method with a five-point adsorption isotherm collected over a range of 0.05 to 0.20 P / P0.

[0071] To perform tensile testing, copolyimide powder resin was compression molded to form green tensile test specimens at an applied pressure of 100,000 psi. The morphology and dimensions of the tensile test specimens are described in the ASTM E8 test method titled "Standard Tension Test Specimen for Powdered Metal Products - Flat Unmachined Tensile Test Bar". The molded green test specimens were sintered in a nitrogen atmosphere using a series of temperature lamps that slowly heated the parts from room temperature to 405°C over 70 hours, then held at 405°C for 30 minutes, and finally slowly cooled to room temperature. The long sintering cycle (70 hours) is not a prerequisite for demonstrating the high toughness properties of the copolyimide resin. Shorter sintering cycles can also be used, provided that no blisters or voids are formed in the parts during faster sintering cycles. Longer sintering times can also be used depending on the dimensions of the parts being sintered.

[0072] The mechanical properties of the copolymer resin were obtained by testing tensile specimens in an Instron testing machine at 30 kN at room temperature. The tensile specimens were subjected to a strain rate of 5 mm / min. Tensile measurements were performed on at least five specimens; however, the reported tensile properties are the average of the tests performed on at least five specimens. The toughness of the specimens was estimated by calculating the area on the stress-strain curve using numerical integration, and the average across five specimens is reported.

[0073] Furthermore, the copolymer resin powder sample was compression-molded to form green cylindrical pellets with a diameter of 8 mm and a height of 8 mm, which were then sintered at 405°C using a 70-hour sintering cycle. The compression properties of the cylindrical parts were measured using a 29-kip MTS test machine test frame equipped with a 100 KN load cell and a laser extensometer to measure the deformation of the parts under stress. The compression speed for all tests was 0.005 seconds. -1 The compression strain rate was fixed at 2.4 mm / min, which corresponds to the compression strain rate. As with the tensile properties, the compression properties are reported as the average obtained after testing performed on five cylindrical samples.

[0074] The specific gravity of the parts was measured by immersion in water. The parts were weighed in air, and then weighed again after being completely immersed in a 0.05% by weight soap solution. The soap solution was necessary to ensure that no small air bubbles adhered to the test specimen. The specific gravity of the parts was calculated using the following formula.

number

[0075] Glass transition temperature of copolyimide polymers (T gThe temperature was obtained by testing rectangular sintered specimens using a dynamic mechanical analyzer (TA Instruments Q800 DMA). The specimens were fixed with a dual cantilever and deformed at the center with a strain amplitude of 0.25% and a frequency of 1 Hz. The temperature sweep for the test was from 40°C to 425°C at a rate of 2°C / min. The temperature corresponding to the peak of the tan δ curve is reported as Tg.

[0076] The friction and abrasion tests of the unfilled and filled copolymers of the present invention were performed using a Falex block-on-ring tester manufactured by Falex Corporation, Sugar Grove, IL. ASTM test methods D2714-94 and G77-17 describe the calibration and operation of the Falex block-on-ring tester and its use in evaluating the friction and abrasion properties of materials. In its simplest form, the machine consists of a rotating metal ring (also called the counter surface) and a stationary test block that is loaded against the rotating ring. The test block is machined from a test specimen disc whose abrasion and friction properties need to be evaluated. Once machined, the test block fits to the outer surface of the counter surface metal ring. During testing, 0.1608 inches 2The inner curved surface of the test specimen, having a certain area, is always in contact with the outer surface of the ring, and the pressure on the block remains constant throughout the test. The machined test block represents a 1 / 4 inch (6.35 mm) thick bushing segment and is mounted to the sample holder via a hemispherical ball, allowing the machined test block to be aligned with the ring, as shown in Figure 1. The load on the block is applied by a weight via a lever arm with a 30x magnification. Thus, a 1 pound weight is amplified to a 30 pound force on the block. The metal rings used in all tests were standard "Alpha" rings machined from SAE4620 steel with surface roughness Rc58-63 and 6-12 rms. A new ring is used in each block-on-ring test. The sample holder is connected to a load cell that measures the frictional force between the block and the ring and provides output in pounds of force.

[0077] The test specimens were prepared by compression molding polyimide powder to form circular discs with a diameter of 1 inch and a thickness of approximately 6 mm. All sample discs were molded at 80,000 psi. Each green disc was sintered using the same temperature and sintering cycle as previously used for the tensile test specimens. After sintering, each disc was machined to form curved blocks as shown in Figure 1. After machining to the desired shape, the test blocks were washed with a solvent to remove contaminants from the sample surface and then dried in a vacuum oven at 150°C. Each test block was weighed to the nearest 0.1 mg. Similarly, the steel rings used in the test were washed with a solvent to remove the rust-preventive coating from the surface, dried, and then weighed before being mounted in the Falex apparatus.

[0078] Friction and wear tests of the Falex apparatus are performed in two different modes. In the constant pressure-velocity (PV) test mode, a fixed load is applied to the test block, and the ring rotates at the same preset constant speed for the entire duration of the test. For the purpose of testing the copolymer of the present invention, the duration of the constant PV test was 24 hours. In the pressure-velocity (PV) limit test, the load and / or speed are increased at 20-minute intervals based on the set program shown in Table 2 until a significant increase in temperature and / or frictional force is obtained. The stopping point of the PV limit test becomes clear when the temperature and frictional force increase exponentially, at which point the apparatus shuts down and the test ends. The PV conditions immediately before the end of the test define the PV limit of the material being tested.

[0079] [Table 2]

[0080] In both test modes, the procedure for preparing the test specimen is the same. After weighing and measuring the thickness of the test specimen (block), the test block is mounted in the apparatus using a self-aligning specimen holder. Next, the counter surface ring is placed on the machine shaft. Based on the pressure value (P) required during the test, a known weight is placed in the machine weight bale. Next, the desired speed (V) is set to achieve the desired PV conditions. A constant PV test is performed for a total of 24 hours with a 1.5-hour "break-in" to achieve a perfect fit between the block and the ring. During the test, the Falex apparatus periodically monitors and reports the coefficient of friction between the surface of the test block and the ring counter surface. After the completion of the constant PV test, the test block is completely dried at 150°C for 24 hours, and its weight is measured with an accuracy of 0.1 mg. The weight loss of the block is used to calculate the wear loss based on weight. Next, the new thickness of the block is measured to determine an alternative measure of wear based on dimensional change. Wear based on weight loss is K wIt is reported as follows: Using the wear base during block thickness reduction, the wear rate (inches / hour) and thickness change based on the wear coefficient - K t Calculate.

[0081] Example 1 A polyimide obtained from 40 mol% BPDA, 40 mol% PPD, 60 mol% PMDA, and 60 mol% ODA, wherein the mol% of the dianhydride components is stated based on the total dianhydride standard, and the mol% of the diamines is stated based on the total diamine standard.

[0082] Anhydrous pyridine was obtained by drying the solvent through molecular sieves. Before starting the experiment, both anhydrous compounds were stored in a vacuum oven at 150°C for at least 12 hours. 7.025 g of PPD and 19.512 g of ODA were weighed and set aside. Similarly, 18.97 g of pre-dried BPDA and 21.095 g of pre-dried PMDA were weighed and set aside.

[0083] 562 g of anhydrous pyridine dried on molecular sieves was added to a 500 cc Chemglass® jacketed reactor. The reactor jacket temperature was set to 45°C and the stirrer speed to 125 rpm. When the solvent temperature reached 35°C, both diamines were added to the reactor. The reactor temperature was then raised to 50°C. Once all the diamines were visibly dissolved in the pyridine heel, the two dianhydrides were added simultaneously to the reactor, and all remaining dianhydrides in the weighing pan were washed away using 62.4 g of anhydrous pyridine that had been set aside for this purpose. After the addition of the dianhydrides was complete, the jacket temperature was raised to 70°C. The stirrer speed was also increased to 250 rpm at this point.

[0084] The heat generated from the reaction between the diamine and the dianhydride caused the reactor temperature to rise rapidly to a maximum of 70°C, and then finally stabilize. Polymerization was continued for a total of 1 hour. At the end of the polymerization time, the stirrer was slowed down and the formed viscous PAA solution was discharged through the bottom take-off valve. A small amount of polymer solution was set aside for molecular weight measurement. The number-average molecular weight (M) of the PAA sample was determined. n ) and weight-average molecular weight (M w The measured values ​​were 100,546 and 226,557 Daltons, respectively.

[0085] The imidization process was carried out in fed-batch mode. At the start of the imidization process, approximately 100 ml of pyridine was initially added to the Parr vessel as the heel and heated to 114°C. The anchor impeller was also started and set to the predetermined value. The stirrer's RPM was set to 200. Next, 597.2 g of the polyamic acid solution discharged from the polymerization vessel was transferred to the barrel of the ISCO pump. The exact weight of the PAA solution transferred to the pump was recorded. Based on this value, the exact pyridine heel required during the imidization process was calculated to be 166.7 g. Based on this calculation, 66.7 g of makeup pyridine was injected into the Parr reactor to obtain an exact pyridine heel size of 166.7 g. The ISCO pump was sealed and connected to the Parr reactor using stainless steel tubing and compression fittings. The PAA solution was transferred to the Parr reactor at a constant rate so that the entire solution transfer was completed over 90 minutes. At the end of the transfer, the internal temperature of the reactor was raised to 145°C over 75 minutes. After reaching 145°C, the contents of the container were held at that temperature for 30 minutes, and then the reactor was cooled to room temperature.

[0086] The D50 of the polyimide particles in the slurry was measured to be 68.1 μm.

[0087] The remaining polyimide slurry was filtered, the resulting filter cake was washed with acetone, and then dried under vacuum at 175°C. The dried polyimide polymer was ground in a lab Wiley mill while being separated through a 30-mesh screen.

[0088] The dried polymer was pulverized and its apparent density (AD) and specific surface area (SA) were characterized. The AD and SA of the copolyimide polymer were 0.159 and 112.4 m², respectively. 2 It was / g.

[0089] Copolymer resin was compression-molded into tensile test specimens and cylindrical pellets, and its compression properties were measured. The green parts were sintered at 405°C. The specific gravity of the sintered parts was 1.420. The Tg of the tan δ curve was 371.4°C.

[0090] The average tensile strength and elongation % measured for five tensile test specimens were 18388 psi and 14.7%, respectively. The average toughness of the copolyimide resin, 2.27 Ksi, was obtained using a stress-strain curve. The average compressive strength was measured at 750 MPa, and the average fracture deformation was 62.5%.

[0091] Examples 2-8 A polyimide composition with higher specific gravity, lower apparent density, and higher toughness containing BPDA, PMDA, PPD, and ODA. In these examples, the mol% of BPDA on a total anhydride basis was maintained to be the same as the mol% of PPD on a total diamine basis.

[0092] The copolyimide resin compositions exemplified in Examples 2-8 were synthesized using the same process outlined in Example 1. Table 3 shows the polymer composition, the amount of each monomer used, and the solvent used during polymerization in Examples 2-8. Table 4 shows the conditions for the imidization step for the synthesis of the copolyimide polymer of the present invention, and the properties of the polymer powder obtained after drying. Table 5 shows the properties of the polymer parts after sintering.

[0093] [Table 3]

[0094] [Table 4]

[0095] [Table 5]

[0096] Comparative Examples 1-2 Homopolymers derived from BPDA, PPD, PMDA, and ODA, respectively, exhibiting inferior toughness compared to the polyimides of the present invention illustrated by Examples 1-8.

[0097] The polymerization and imidation reactions of BPDA and PPD were carried out in a manner very similar to that described in Example 1, except that the homopolymerization of BPDA-PPD and subsequent imidation were carried out in a pyridine to NMP ratio of 10:1 (by weight). Since the polyamic acid homopolymer of BPDA and PPD is immiscible in pyridine, a change of solvent was necessary because a small amount of NMP is required to ensure that the polyamic acid remains in the solution. Before starting polymerization, 18.776 g of PPD was dissolved in 624 g of the pyridine-NMP mixture and then reacted with 50.574 g of BPDA at 50°C. After polymerization was complete, 576 g of the resulting polyamic acid (PAA) homopolymer solution was slowly transferred to 247 g of a 10:1 mixture of pyridine and NMP according to the transfer procedure of Example 1. The solvent temperature was maintained at 114°C during the PAA transfer. During this imidization process, after the imidized polymer precipitated, the reactor temperature was increased to 145°C to maximize polymer precipitation and further enhance the degree of imidization of the precipitated polymer. The D50 particle distribution was measured to be 76.6 mm. The polyimide solvent slurry was cooled to 60°C and then filtered. The filtered cake was washed with acetone and then dried in a vacuum oven at 180°C, as described in Example 1. The dried polymer was ground through a 30-mesh screen before further use. The AD of the powder was measured to be 0.170 g / cc. The polymer powder was compression molded to form test parts for tensile testing. The toughness of the homopolymer under tension was obtained from the stress-strain curve. The properties of the finished parts of the BPDA-PPD homopolymer are shown in Table 6. The BPDA-PPD homopolymer exhibits very low elongation and very low toughness.

[0098] [Table 6]

[0099] The imidized homopolymer of PMDA and ODA was obtained by polymerizing 30.537 g of PMDA with 28.132 g of ODA in 362 g of pure pyridine solvent. The PAA homopolymer formed in solution was imidized by slowly transferring 290 g of it to 86 g of pyridine at 114°C, and then the entire solution was heated to 145°C to precipitate, forming the PMDA-ODA polyimide homopolymer. The homopolymer was filtered, washed, and vacuum-dried as described in Example 1. The dried polymer was pulverized. The AD was measured to be 0.177 g / cc. The polymer powder was compression-molded to form test parts for both tensile tests. The toughness of the homopolymer under tension was obtained from the stress-strain curve. The properties of the finished parts of the PMDA-ODA homopolymer are shown in Table 7. The PMDA-ODA homopolymer exhibits higher elongation and toughness than the BPDA-PPD homopolymer, but still exhibits much lower toughness than the copolymers shown in Examples 1-8. [Table 7]

[0100] Comparative Examples 3-6 Polyimide blends are prepared by blending BPDA and PPD polymers with PMDA and ODA polymers in various weight ratios, in order to compare the properties of the blended polymer composition with those of a polyimide composition containing similar amounts of BPDA, PMDA, PPD, and ODA in the polymer backbone. The blended polymers in these examples exhibit inferior strength, elongation, and toughness compared to copolyimide compositions having the same monomer composition.

[0101] The imidized homopolymer of BPDA-PPD was synthesized in exactly the same manner as described in Comparative Example 1. After the imidization step was completed, the polymer slurry in the pyridine-NMP mixture was set aside for further processing in the subsequent examples.

[0102] The imidized homopolymers of PMDA and ODA are manufactured by EIDupont & Nemours company, and the finished parts and shapes produced from these polymers are sold under the trademark name Vespel® SP-01. SP-01 polyimide slurry samples were recovered from the Vespel® manufacturing plant and further processed in the subsequent examples. The D50 of the SP-01 slurry was measured to be 27.0 μm.

[0103] Comparative Example 3 A BPDA-PPD homopolymer slurry containing 10 g of solid BPDA-PPD homopolymer in pyridine and a PMDA-ODA homopolymer slurry containing 40 g of PMDA-ODA in pyridine were weighed into round-bottom flasks and vigorously mixed for 15 minutes using an overhead agitator assembly. The blended polymer slurries were filtered, and the wet cake was washed with excess acetone. The acetone-containing cake was dried in a vacuum oven at 180°C for 16 hours, and the dried polymer was ground through a 30-mesh screen. Since the resulting polymer blend was obtained by mixing two homopolymer components in slurry form, it is reasonable to assume that the individual particles constituting the two homopolymer slurries are homogeneously dispersed, resulting in a well-mixed polymer system. In the resulting polymer blend, the molar percentage of BPDA on a total anhydrous basis should be 20%, and the molar percentage of PPD on a total diamine basis should be 20%. The blended polymer powder was compressed into tensile test specimens in the same manner as described in Example 1, sintered, and tested for its properties.

[0104] Comparative Example 4 A BPDA-PPD homopolymer slurry containing 20 g of solid BPDA-PPD homopolymer and a PMDA-ODA homopolymer slurry containing 30 g of PMDA-ODA homopolymer were blended together, and the resulting slurry was processed to form dried powder and test parts as described in Comparative Example 3.

[0105] Comparative Example 5 A BPDA-PPD homopolymer slurry containing 30 g of solid BPDA-PPD homopolymer and a PMDA-ODA homopolymer slurry containing 20 g of PMDA-ODA were blended together. The resulting slurry was processed to form a dried powder and test parts as described in Comparative Example 3.

[0106] Comparative Example 6 A BPDA-PPD homopolymer slurry containing 40 g of solid BPDA-PPD homopolymer and a PMDA-ODA homopolymer slurry containing 10 g of PMDA-ODA were blended together. The resulting slurry was processed to form dried powder and test parts as described in Comparative Example 3.

[0107] Table 8 shows the final properties of the blended polymer compositions of Comparative Examples 3-6.

[0108] [Table 8]

[0109] The results of Comparative Examples 3-6 are graphically compared with the results of Examples 1-8 in Figures 2, 3, and 4, where the tensile strength, elongation at break %, and tensile toughness of the copolyimide of the present invention are plotted against the BPDA and PPD content in the polymer and compared with those of blended polyimides. These examples and the resulting figures demonstrate that the copolyimide of the present invention exhibits significantly superior performance compared to blended homopolymers having the same BPDA, PPD, PMDA, and ODA content.

[0110] Examples 9-17 Copolyimide compositions with further higher specific gravity, lower apparent density, and higher toughness, containing BPDA, PMDA, PPD, and ODA. In Examples 1-8 of the present invention, the mol% of BPDA on a total anhydride basis and the mol% of PPD on a total diamine basis were maintained to be equal. In Examples 9-17, the mol% of BPDA was not equal to the mol% of PPD, but the tensile properties and toughness were still similar to those observed in Examples 1-8, thus demonstrating that the content of BPDA and PPD in the copolymer does not need to be the same to produce a high-toughness copolymer composition.

[0111] The copolyimide resin compositions exemplified in Examples 9-17 were synthesized using the same process outlined in Example 1, except for the temperature range of 110°C to 150°C during the PAA transfer imidation. Table 9 shows the polymer compositions of Examples 9-17, the amounts of each monomer used, and the solvents used during polymerization. Table 10 shows the conditions for the imidation step for the synthesis of the copolyimide polymers of the present invention, and the properties of the polymer powder obtained after drying. Table 11 shows the properties of the polymer components after sintering.

[0112] [Table 9]

[0113] [Table 10]

[0114] [Table 11]

[0115] Comparative Examples 7-13 These examples demonstrate that when the molar percentage of BPDA based on the total dianhydride content in the copolymer composition differs significantly from the molar percentage of PPD based on the total diamine content, the copolyimide exhibits high AD, low specific gravity, and low toughness in the final sintered parts.

[0116] The copolyimide resin compositions exemplified in Comparative Examples 7-13 were also synthesized using the same process outlined in Example 1. Table 12 shows the polymer composition, the amount of each monomer, and the solvent used in the polymerization and imidization steps for the synthesis of the copolyimide polymer of the present invention. Table 13 shows the conditions for the imidization step for the synthesis of the copolyimide polymer of the present invention and the properties of the polymer powder obtained after drying. Table 14 shows the properties of the polymer parts after sintering.

[0117] [Table 12]

[0118] [Table 13]

[0119] [Table 14]

[0120] All comparative examples presented herein exhibit significantly inferior properties compared to the copolymers of the present invention demonstrated in Examples 1-17. These comparative examples either exhibit insufficient tensile properties and toughness, or the polymer attributes fail to allow for the creation of suitable parts for testing. The polymer powders formed in Comparative Examples 9-13 are dense, as seen by their high AD. High-density powders result in parts with low specific gravity, low tensile strength, low elongation, and low polymer toughness. Comparative Example 9 uses only three monomers (BPDA, PMDA, and ODA) in its composition. These examples demonstrate that all four monomers—BPDA, PMDA, PPD, and ODA—are necessary to form polymers with low powder density and high toughness. The copolymers of Comparative Examples 10 and 11 are synthesized from all four monomers, and while they exhibit sufficiently low apparent density (less than 0.25 Ksi), they still exhibit low strength, low elongation, and very low toughness. In both of these inferior-performing copolymer compositions, the molar percentage of PPD is significantly greater than the molar percentage of BPDA. Therefore, the examples demonstrate that for a copolymer composition with higher toughness, the molar percentage of BPDA needs to be (molar percentage of PPD + 0.2) or higher.

[0121] Example 18 A copolyimide composition containing 9% by weight of graphite as a filler, 60 mol% of BPDA, 60 mol% of PPD, 40 mol% of PMDA, and 40 mol% of ODA.

[0122] The polyamic acid of the copolyimide in this example was synthesized in the laboratory using a process very similar to that described in Example 1. 10.54 g of PPD and 13.01 g of ODA were dissolved in 600 g of pyridine anhydride at 35°C. The diamine solution was heated to 50°C, at which point 28.46 g of BPDA and 14.06 g of PMDA were simultaneously added to the reactor to initiate the polymerization reaction. An additional 19.1 g of pyridine was used to wash away all remaining dianhydride in the weighing pan into the polymerization reactor.

[0123] After a reaction time of 1 hour, the polymer Mn and M w These were measured to be 90,000 Daltons and 186,000 Daltons, respectively.

[0124] 168.8 g of anhydrous pyridine was added to a clean high-pressure Parr reactor. 5.96 g of natural graphite, grade 200-09, sold by Southern Graphite, was added to this solvent and dispersed using an anchor stirrer running at 200 rpm. The reactor was purged with nitrogen and the graphite-pyridine slurry was heated to 114°C. Almost simultaneously, 548.1 g of the PAA solution synthesized above was transferred to an ISCO syringe pump and heated to 70°C. Once the temperature of the PAA solution in the pump stabilized, the transfer of the PAA solution to the Parr reactor was started. The temperature of the imidation reaction was kept constant at 114°C throughout the entire PAA transfer. All of the PAA in the ISCO pump was transferred in 90 minutes. At the end of the transfer, the PAA supply line from the pump was purged into the imidation reactor with 29.1 g of pyridine. Similar to Example 1, at the end of the PAA transfer, the contents of the imidizing agent were heated to 145°C over 75 minutes, and then the reactor was maintained at 145°C for a further 30 minutes. After this holding time, the imidization process was considered complete, and the contents of the reactor were cooled to room temperature.

[0125] The D50, which represents the particle size distribution in the reaction slurry, was measured to be 57.9 mm. The graphite-containing copolyimide slurry was filtered, the filtered cake was washed with acetone, and then dried overnight in a heated vacuum oven to obtain a copolyimide resin containing 9% by weight of graphite.

[0126] The polymer powder was compressed at room temperature to form a green tensile test specimen, which was then sintered at 405°C as described in Example 1. The tensile properties of the sintered specimen were measured in the same manner as described in Example 1.

[0127] Table 15 shows the tensile strength, elongation at break %, and measured toughness of the graphite-containing copolyimide. It is well known to those skilled in the art that the addition of solid fillers to any polymer reduces its toughness. However, even though the copolyimide in this example contains 9% graphite filler and its toughness is lower than that of the unfilled composition taught in Example 4, the filled copolymer still exhibits higher toughness than the unfilled homopolymers of BPDA-PPD and PMDA-ODA.

[0128] [Table 15]

[0129] Example 19 A copolyimide containing polyamic acid with 60 mol% BPDA, 60 mol% PPD, 40 mol% PMDA, and 40 mol% ODA was synthesized as described in Example 17. The imidation step was also very similar to that described in Example 17, except that 0.5 g of Polyfil DL Kaolinite (supplied by KaMin, LLC) was added together with 5.3 g of natural graphite to 169.9 g of anhydrous pyridine heel in a high-pressure Parr reactor. For this reaction, 548.2 g of copolyimide PAA solution was transferred to the imidation reactor over 90 minutes. The final composition of the filler in the copolyimide resin was 1 wt% kaolinite and 9 wt% graphite.

[0130] Tensile test specimens were prepared from the filled copolyimide resin and tested as described in Example 1. The tensile strength, elongation %, and toughness of the filled copolyimide resin are shown in Table 16.

[0131] In this case as well, the filled copolymer of this example exhibits higher toughness than the unfilled homopolymers of BPDA-PPD and PMDA-ODA.

[0132] [Table 16]

[0133] Example 20 A copolyimide composition containing 60 mol% BPDA, 60 mol% PPD, 40 mol% PMDA, and 40 mol% ODA, with 10% by weight of graphite as a filler.

[0134] A copolyimide polyamic acid containing 60 mol% BPDA, 60 mol% PPD, 40 mol% PMDA, and 40 mol% ODA was polymerized in the same manner as described in Example 1. 7.03 g of PPD and 19.51 g of ODA were reacted with 18.97 g of BPDA and 21.09 g of PMDA in 624.1 g of pyridine anhydride.

[0135] The imidation process in the presence of natural graphite was carried out in the same manner as described in Example 17. 5.9 g of natural graphite was dispersed in 168.5 g of anhydrous pyridine heal. 552.6 g of copolyimide polyamic acid was added to the imidation reaction, followed by the addition of 29 g of clean pyridine. After the imidation reaction was complete, the slurry was filtered, the cake was washed with acetone, and then dried. Tensile test specimens were prepared from the filled resin and then tested for tensile properties.

[0136] The filled copolyimide resin had a tensile strength of 17,480 psi and an elongation at break of 12.76%.

[0137] Examples 21-25 This embodiment demonstrates the low friction and low wear performance of a copolymer filled with graphite and kaolinite according to the present invention.

[0138] Copolyimide compositions having varying amounts of BPDA, PPD, PMDA, and ODA were polymerized using the same process as described in Example 1. The copolymer polyamic acid solutions thus prepared were converted into graphite and kaolinite-filled polyimide powders and components using the process described in Example 18. Two different types of graphite were used in these examples: the first was natural graphite 200-09 sold by Southwestern Graphite, and the second was synthetic graphite Asbury 4767 sold by Asbury Carbons.

[0139] The compositions of the fabricated copolymers are shown in Table 17, and the tensile properties of these polymers are shown in Table 18.

[0140] [Table 17]

[0141] [Table 18]

[0142] The copolymer powders of Examples 21-25 were compression-molded at 80,000 psi to form 1-inch diameter discs with a thickness of 6-6.5 mm. Three discs were formed from each composition. The green discs were sintered using the same sintering cycle and temperature as used for all tensile test specimens in the previous examples. After sintering, the discs were machined to form test blocks that fit snugly into the steel rings of the Falex testing machine. The machined blocks were mounted in the sample holder of the Falex testing machine and then tested under various PV conditions as described in the previous section. Multiple tests were performed for each composition. The first test was conducted for 24 hours at a constant PV of 100,000 psi ft / min, the second test was conducted at a PV of 300,000 psi ft / min, and the third test was terminated under continuously increasing PV conditions (PV limit test) until the sample failed or the temperature increased exponentially due to frictional heating. At the end of a set PV test, dimensional wear, weight-based wear coefficient, friction coefficient, and steady-state ambient temperature due to frictional heat dissipation were recorded. The friction and wear performance of the filled copolymer at 100,000 psi ft / min is shown in Table 19, and the friction and wear performance under higher PV conditions of 300,000 psi ft / min is shown in Table 20. The PV limit conditions under which the PV limit test ends due to an exponential rise in temperature caused by frictional heating are also shown in Table 18.

[0143] [Table 19]

[0144] [Table 20]

[0145] Comparative Examples 14-15 EIDupont & Nemours Company manufactures PMDA-ODA graphite-filled homopolymer under the trademark name Vespel® SP-21. The average tensile strength and elongation % of this polymer grade are 10,500 psi and 7.5%, respectively.

[0146] Dupont also manufactures graphite-filled polymers derived from BPDA and PPD, marketed under the trademark name Vespel® SCP-50094. The average tensile strength and elongation percentage for this grade are 20,000 psi and 4.0%, respectively.

[0147] Multiple circular discs, each 1 inch in diameter and 6 mm thick, were formed by compression molding of SP-21 and SCP-50094 polymer powders at 80,000 psi. These discs were machined to form friction and abrasion test blocks for a Falex block-on-ring tester. Both grades of polymer were tested for friction and abrasion at 100,000 psi ft / min, 300,000 psi ft / min, and PV limit tests.

[0148] Table 21 shows the friction and abrasion performance of both SP-21 and SCP-50094 at 100,000 psi ft / min, and Table 22 shows the friction and abrasion performance of both polymers at 300,000 psi ft / min, where the PV limit is reached. The filled copolymers of the present invention, as exemplified by Examples 21-25, exceed the performance of both SP-21s in terms of tensile properties and friction and abrasion performance.

[0149] [Table 21]

[0150] [Table 22]

Claims

1. A polyimide composition comprising (i) particles of polyimide polymer derived from ODA, (ii) PMDA, (iii) PPD, and (iv) BPDA monomers, If the polyimide composition consists of the particles of the polyimide polymer, the polyimide composition has an apparent density of 0.25 g / cubic centimeter or less.

2. The parts manufactured from the polyimide composition comprising the particles of the polyimide polymer have a toughness of 0.80 Ksi or higher and a density of 1.38 g / cm². 3 A specific gravity of the above, or a toughness of 0.80 Ksi or higher, and 1.4 g / cm². 3 The polyimide composition according to claim 1, having the above specific gravity.

3. The polyimide composition according to claim 1, wherein the sum of the mole fractions of BPDA and PMDA in the particles of the polyimide polymer is about 1, the sum of the mole fractions of PPD and ODA in the particles of the polyimide polymer is about 1, and the relationship between the mole fraction of BPDA and the mole fraction of PPD in the particles of the polyimide polymer is in the range of PPD-0.2 < BPDA < PPD+0.

2.

4. The following repeating units 【Chemistry 1】 The polyimide composition according to claim 1, comprising a polyimide containing one or more of the following.

5. The polyimide composition according to claim 1, wherein the polyimide composition comprises a filler, the filler is present in an amount of up to 75% (by weight / weight) of the polyimide composition by weight.

6. The polyimide composition according to claim 5, wherein the filler is graphite or clay.

7. A component comprising the polyimide composition according to any one of claims 1 to 6.

8. The part according to claim 7, wherein the polyimide composition is molded to form the part.

9. The component according to claim 7 or 8, wherein the component is a clutch roller, a seal ring, a spherical washer, a compressor seal, a lip seal, a valve seat, a ball bearing cage, and an operating disc.

10. A method for producing a polyimide composition, (i) a step of combining ODA, (ii) PMDA, (iii) PPD, (iv) BPDA, and (v) a solvent for a sufficient time and under conditions to form a reaction product comprising a polyamide and a solvent, A step of heating the reaction product for a temperature and time sufficient to remove water and form polyimide particles, A process of filtering and washing the polyimide particles, A step of drying washed polyimide particles to form the polyimide composition, wherein the polyimide composition comprises the polyimide particles, Includes, A method for producing a polyimide composition, wherein the polyimide composition comprises particles of a polyimide polymer, and the polyimide composition has an apparent density of 0.25 g / cubic centimeter or less.

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