Non-halogenated flame retardant polyamide composition

Abstract

Disclosed is a non-halogenated flame retardant polyamide composition comprising a polyamide, a non-halogenated flame retardant, a PA-6 homopolymer, and at least one heat stabilizer, including a copper-containing heat stabilizer, an amine-containing heat stabilizer, or a phenol-containing heat stabilizer. The polyamide has a ratio of carboxylic acid end groups to amine end groups of greater than 1.8: 1. The polyamide composition may include less than 900 ppm of bromine. A product formed from the composition is also disclosed.

Description

This application is an international application filed by Ascend Functional Materials Operations Co., Ltd. on April 1, 2020 with the number PCT / US2020 / 026202 and the title of the invention is “ Non-halogenated flame retardant polyamide composition " is a divisional application of the international application. The date on which the international application PCT / US2020 / 026202 entered the Chinese national phase is September 28, 2021, and the national application number is 202080025633.1. CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of and priority to U.S. Provisional Application No. 62 / 827,653, filed April 1, 2019, which is incorporated herein by reference in its entirety. Technical Field

[0002] The present disclosure relates to non-halogenated flame retardant polyamide compositions and molded products made therefrom. More particularly, the present disclosure relates to non-halogenated flame retardant polyamide compositions comprising a synergistic combination of a polyamide having low reactivity, a heat stabilizer, and optional additives, resulting in a polyamide composition having excellent heat aging resistance. Background Art

[0003] Polyamide resin compositions are known to have beneficial physical properties, such as a high melting point, a high recrystallization temperature, faster injection molding cycle times, high flowability, toughness, elasticity, chemical resistance, inherent UL94 V2 flame retardancy, and wear resistance. These properties generally make them ideal for high-performance automotive and electrical / electronic applications. However, when plastic parts are exposed to high temperatures for extended periods, such as in automotive or electrical / electronic applications, mechanical properties generally tend to degrade due to thermal oxidation of the polymer. This phenomenon is commonly referred to as heat aging.

[0004] Polyamide resins with good heat aging resistance are clearly useful in high-temperature applications. Examples of these applications are in the electrical / electronics industry, where the trend toward integrated electronic components has led to an increasing demand for plastic materials with significantly greater heat resistance and flame retardancy. Specific applications include connectors, circuit breakers, circuit boards, and junction boxes. These devices often need to operate continuously in harsh environments under extreme temperatures and voltages.

[0005] In an effort to improve the heat aging properties of polymers, it is common practice to add heat stabilizers to thermoplastic compositions containing polyester or polyamide resins. However, the heat aging properties of existing technologies are insufficient for more demanding applications involving exposure to higher temperatures, such as automotive and electrical / electronic applications. Furthermore, while adding heat stabilizers to polyamide resins can improve heat aging, heat stabilizers often introduce additional halogen compounds into the composition. Consequently, thermoplastic compositions using such heat stabilizers may not be rated as "halogen-free."

[0006] Therefore, there is a need for polyamide molding compositions that provide improved heat aging stability and durability while maintaining non-halogen grades. Summary of the Invention SUMMARY OF THE INVENTION

[0007] In some embodiments, the present disclosure relates to a flame-retardant polyamide composition comprising: a polyamide having a ratio of carboxylic acid end groups to amine end groups greater than 1.8:1; a non-halogenated flame retardant; less than 0.29 wt% of a first copper-containing heat stabilizer comprising a copper halide and an organohalo-phosphorus compound, based on the total weight of the polyamide composition; wherein the polyamide composition comprises less than 900 ppm of bromine, and wherein the polyamide composition retains 50% of its initial tensile strength after greater than 800 hours of heat aging at a temperature of 195°C and measured at 23°C. In some embodiments, the polyamide composition further comprises a PA-6 homopolymer. In some embodiments, the PA-6 homopolymer is present in an amount of up to 20 wt%, based on the total weight of the polyamide composition. In some embodiments, the polyamide composition comprises less than 900 ppm of chlorine. In some embodiments, the polyamide composition comprises less than 1500 ppm of a combination of chlorine and bromine. In some embodiments, the polyamide composition further comprises a second copper-containing heat stabilizer comprising free copper; and a copper complexing agent comprising a phosphorus-containing additive. In some embodiments, the copper complexing agent complexes the free copper of the second copper-containing heat stabilizer. In some embodiments, the phosphorus-containing additive includes a phosphine-containing compound, a phosphate-containing compound, a polyphosphate-containing compound, a bromine-containing phosphate, a bromine-containing polyphosphate, a bromine-containing phosphite, a chlorine-containing phosphate, a chlorine-containing polyphosphonate, a chlorine-containing phosphite, triphenylphosphine, triphenyl phosphite, or a combination thereof. In some embodiments, the second copper-containing heat stabilizer includes copper halide, copper acetate, copper propionate, copper benzoate, copper adipate, copper terephthalate, copper isophthalate, copper salicylate, copper nicotinate, copper stearate, a copper complex salt, or a combination thereof. In some embodiments, the second copper-containing heat stabilizer is present in an amount less than 3% by weight based on the total weight of the polyamide composition. In some embodiments, the polyamide composition further includes an amine-containing heat stabilizer, a phenol-containing heat stabilizer, or a combination thereof. In some embodiments, the polyamide composition includes less than 5% by weight of elemental phosphorus, based on the total weight of the polyamide composition. In some embodiments, the polyamide composition comprises 0.1 wt% to 20 wt% PA6, wherein the polyamide composition has a tensile elongation of at least 1.0%, and wherein the polyamide composition has a tensile strength retention of at least 75% when heat aged at a temperature of 155°C for 1000 hours and measured at 23°C. In some embodiments, the polyamide composition further comprises one or more additives including a flow modifier, glass fiber, filler, synergist, lubricant / release agent, antioxidant, or a combination thereof. In some embodiments, the polyamide composition comprises 40 wt% to 70 wt% polyamide; 5 wt% to 25 wt% of the non-halogen flame retardant; 0.1 wt% to 3 wt% of a second copper-containing heat stabilizer; 0.1 wt% to 15 wt% of a copper complexing agent; and 0 wt% to 10 wt% of a lubricant / release agent.In some embodiments, the non-halogenated flame retardant comprises an organophosphorus flame retardant. In some embodiments, the polyamide composition comprises 40% to 70% by weight of polyamide; 5% to 25% by weight of the non-halogenated flame retardant; 0% to 30% by weight of glass fiber; 0% to 3% by weight of carbon black; and 0% to 5% by weight of zinc stearate and / or zinc borate.

[0008] In some embodiments, the present disclosure is directed to a flame retardant polyamide composition comprising: a polyamide having a ratio of carboxylic acid end groups to amine end groups greater than 1.8:1; a non-halogenated flame retardant; a PA-6 homopolymer; less than 0.29 wt % of a first copper-containing thermal stabilizer comprising a copper halide and an organohalo-phosphorus compound, based on the total weight of the polyamide composition; and wherein the polyamide composition comprises less than 900 ppm bromine.

[0009] In some embodiments, the present disclosure relates to a flame retardant polyamide composition comprising: a polyamide having a ratio of carboxylic acid end groups to amine end groups greater than 1.8:1; a non-halogenated flame retardant; a PA-6 homopolymer; and an amine-containing heat stabilizer, wherein the polyamide composition is heat aged at a temperature of 215°C and retains 50% of its initial tensile strength after heat aging for greater than 450 hours when measured at 23°C, in some embodiments, the PA-6 homopolymer is present in an amount of up to 20% by weight based on the total weight of the polyamide composition, and wherein the polyamide composition has a tensile elongation of at least 3.0%. In some embodiments, the amine-containing heat stabilizer comprises a hindered amine heat stabilizer. In some embodiments, the composition further comprises one or more additives comprising a flow modifier, glass fiber, filler, synergist, lubricant / release agent, antioxidant, or a combination thereof. In some embodiments, the non-halogenated flame retardant comprises an organophosphorus flame retardant.

[0010] In some embodiments, the present disclosure relates to a flame retardant polyamide composition comprising: a polyamide having a ratio of carboxylic acid end groups to amine end groups greater than 1.8:1; a non-halogenated flame retardant; a PA-6 homopolymer; and a phenolic heat stabilizer. In some embodiments, the PA-6 homopolymer is present in an amount of up to 20 weight percent based on the total weight of the polyamide composition, wherein the polyamide composition is heat aged at a temperature of 215° C. and retains 50% of its initial tensile strength after heat aging for greater than 450 hours when measured at 23° C., and wherein the polyamide composition has a tensile elongation of at least 2.5%. In some embodiments, the phenolic heat stabilizer includes N,N'-hexane-1,6-diylbis[3-(3,5-di-tert-butyl-4-hydroxyphenylpropionamide)]; pentaerythritol-tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]; N,N'-hexamethylenebis(3,5-di-tert-butyl-4-hydroxy-cinnamic acid); triethylene glycol-bis[3-(3-tert-butyl-5-methyl-4-hydroxyphenyl)propionate]; 3,9-bis{2- [3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionyloxy]-1,1-dimethylethyl}-2,4,8,10-tetraoxaspiro[5,5]undecane; 3,5-di-tert-butyl-4-hydroxybenzylphosphonate-diethyl ester; 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene; and 1,3,5-tris(4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl)isocyanurate, or a combination thereof. In some embodiments, the polyamide composition further comprises one or more additives comprising a flow modifier, glass fiber, filler, synergist, lubricant / release agent, antioxidant, or a combination thereof. In some embodiments, the non-halogenated flame retardant comprises an organophosphorus flame retardant.

[0011] In some embodiments, the present disclosure relates to a molded flame retardant polyamide product according to any of the polyamide compositions described herein. DETAILED DESCRIPTION Detailed Description of the Invention summary

[0012] Conventional polyamide compositions typically include heat stabilizer packages in an attempt to improve high temperature heat aging performance. Although the art is replete with examples of heat stabilized compositions, most, if not all, of these compositions fail to achieve the very high heat aging performance required for extended high temperature applications such as automotive or electrical / electronic applications.

[0013] The present disclosure relates to non-halogenated flame retardant polyamide compositions and molded products produced therefrom that exhibit improvements in high heat aging performance. The disclosed polyamide compositions utilize a unique combination of a polyamide having a high ratio of carboxylic acid end groups to amine end groups (e.g., greater than 1.8:1), a specific heat stabilizer, and optional additives (e.g., PA-6 homopolymer). Typically, known polyamides containing high carboxyl end groups do not provide high thermal performance. These heat stabilizers, used in combination with polyamides having a high ratio of carboxyl end groups to amine end groups, surprisingly and unexpectedly provide good heat aging performance while maintaining a non-halogen grade. Surprisingly, the polyamide compositions described herein have a synergistic effect with other components (e.g., heat stabilizers, additives, etc.), which allows the compositions to achieve good heat aging performance despite having high carboxyl end groups.

[0014] Some conventional copper-containing heat stabilizers can improve heat aging stability, but due to the halogen component content, they can adversely affect the non-halogen grade of the polyamide composition. For example, some copper-containing heat stabilizers contain large amounts of halogen compounds, such as organohalo-phosphorus (organobromo-phosphorus) compounds, which help improve heat aging performance but disadvantageously result in exceeding halogen content limits. In addition, some copper-containing heat stabilizers have been found to introduce large amounts of free copper into the polyamide composition. This free copper adversely affects the surface appearance of molded products and promotes contact corrosion. As used herein, "free copper" refers to unbound elemental copper or copper ions.

[0015] The present inventors have now discovered that the use of specific copper-containing heat stabilizers (in specific amounts), optionally in combination with specific additives, produces a synergistic heat stabilizer package that provides excellent heat aging performance and a non-halogen rating while also minimizing or eliminating the amount of free copper introduced into the polyamide composition. For example, in some embodiments, the amount of copper-containing heat stabilizer is limited to meet the non-halogen rating while still providing excellent heat aging performance to the polyamide composition without adding free copper to the polyamide composition. The present inventors have also discovered that the addition of specific copper complexing agents, such as phosphorus-containing compounds, complexes any free copper that may be present in the polyamide composition. In other cases, the use of additional copper-containing heat stabilizers containing complexed copper can also reduce the amount of free copper in the polyamide composition, which in turn reduces contact corrosion in the final polyamide composition. In addition, the copper-containing heat stabilizers provide polyamide compositions with a high relative temperature index (RTI).

[0016] The present inventors have also discovered that using PA-6 homopolymer in combination with a heat stabilizer (in specific amounts), and optionally with specific additives, in a polyamide composition results in a synergistic heat stabilizer package that provides excellent heat aging performance and a non-halogen rating. For example, in some embodiments, a polyamide composition can include a PA-6 homopolymer in combination with at least one of a copper-containing heat stabilizer, an amine-containing heat stabilizer, or a phenol-containing heat stabilizer. The PA-6 homopolymer and these heat stabilizers exhibit a synergistic effect, providing a high RTI while also meeting a non-halogen rating.

[0017] Additionally, the present inventors have discovered that by using specific polyamides with specific properties, particularly a controlled ratio of carboxyl to amine end groups, compositions with synergistic characteristics are formed. Without being bound by theory, it is hypothesized that the use of polyamides with reduced reactivity, increased inert acetic acid end groups, and / or increased carboxylic acid end groups results in improved thermal stability and other desirable properties. As an additional benefit, the molecular weight of the composition is controlled from initial formation to final compounding and molding.

[0018] In addition, the present inventors have found that the disclosed compositions produce products with reduced plating out and corrosion of metal parts. These improvements advantageously result in products with improved durability and performance. In some embodiments, the compositions are prepared and then compounded and molded into final molded products.

[0019] In some embodiments, the polyamide composition comprises a polyamide, a non-halogenated flame retardant, a (first) copper-containing thermal stabilizer, and optionally one or more additives. The polyamide may have a ratio of carboxylic acid end groups to amine end groups greater than 1.8:1 ("high CEG polyamide"). The polyamide composition may comprise (less than 0.29 wt%) a first copper-containing thermal stabilizer, which may comprise a copper halide and an organohalo-phosphorus (organobromo-phosphorus) compound (bound copper thermal stabilizer).

[0020] In some embodiments, the polyamide composition comprises a polyamide, a non-halogenated flame retardant, a PA-6 homopolymer, a first copper-containing thermal stabilizer, and optionally one or more additives. The polyamide may be as disclosed herein. The polyamide composition may include (less than 0.29 wt %) a first copper-containing thermal stabilizer, which may comprise a copper halide and an organobromine-phosphorus compound.

[0021] In some embodiments, the polyamide composition comprises a polyamide, a non-halogenated flame retardant, a PA-6 homopolymer, an amine-containing heat stabilizer, and optionally one or more additives. The polyamide can be as disclosed herein. The polyamide composition can include from about 0.1 wt % to about 2 wt % of the amine-containing heat stabilizer.

[0022] In some embodiments, the polyamide composition comprises a polyamide, a non-halogenated flame retardant, a PA-6 homopolymer, a phenolic heat stabilizer, and optionally one or more additives. The polyamide can be as disclosed herein. The polyamide composition can include from about 0.1 wt % to about 2 wt % of the phenolic heat stabilizer.

[0023] In some cases, when the composition further comprises a second copper-containing heat stabilizer (free copper heat stabilizer) containing free copper, the polyamide may further comprise a copper complexing agent. The copper complexing agent may comprise a phosphorus-containing compound that complexes the free copper present in the polyamide composition from the second copper-containing heat stabilizer. In some cases, the free copper of the second copper-containing heat stabilizer may be complexed by the copper complexing agent before the second copper-containing heat stabilizer is added to the polyamide composition. In other words, the second copper-containing heat stabilizer may be supplied to the polyamide composition together with the complexed copper. It has been found that the compositions described herein are thermally stable and have a reduced molecular weight gain during compounding and molding. Copper-containing heat stabilizer

[0024] Polyamide composition can include one or more heat stabilizers. In some embodiments, one or more heat stabilizers include (first) copper-containing heat stabilizer. In some embodiments, the first copper-containing heat stabilizer includes copper, halogen (or copper halide-compound including copper and halogen) and optional organic halogen-phosphorus (organic bromine-phosphorus) compound. In some aspects, the first copper-containing heat stabilizer includes a mixture including copper halide, phosphate or phosphine or its complex. In some aspects, the first copper-containing heat stabilizer includes a complex including cupric iodide, bis(triphenylphosphine) and tris(tribromoneopentyl) phosphate. Suitable first copper-containing heat stabilizer includes those described in German Patent DE19847626, which is incorporated herein by reference in its entirety.

[0025] When these combinations of copper halides and organohalo-phosphorus (organobromo-phosphorus) compounds are added to the polyamides described herein, the resulting polyamide compositions exhibit excellent thermal stability while also maintaining excellent electrical properties, making the polyamide compositions of the present invention ideally suited for use in the electrical / electronics industry. As an additional benefit, this combination of copper halide and organophosphorus compound does not discolor the polyamide composition.

[0026] Suitable commercially available (first) copper-containing heat stabilizers include H3386 (available from Brüggemann Chemical).

[0027] As described above, a polyamide composition comprising a first copper-containing heat stabilizer including a halogen compound, such as an organic bromine-phosphorus compound, may have a potential to have a halogen content exceeding non-halogen grades. To avoid exceeding the halogen content limit, the polyamide composition may include a specific amount of the first copper-containing heat stabilizer.

[0028] In some embodiments, the polyamide composition includes the first copper-containing heat stabilizer in an amount of 0.01 wt% to 0.29 wt%, e.g., 0.05 wt% to 0.28 wt%, 0.08 wt% to 0.275 wt%, 0.1 wt% to 0.27 wt%, 0.12 wt% to 0.26 wt%, 0.14 wt% to 0.25 wt%, 0.15 wt% to 0.24 wt%, 0.16 wt% to 0.23 wt%, or 0.17 wt% to 0.22 wt%, based on the total weight of the polyamide composition. In terms of upper limits, the polyamide composition comprises the first copper-containing heat stabilizer in an amount of less than 0.29 wt %, e.g., less than 0.28 wt %, less than 0.27 wt %, less than 0.26 wt %, less than 0.25 wt %, less than 0.24 wt %, less than 0.23 wt %, less than 0.22 wt %, less than 0.21 wt %, or less than 0.20 wt %, based on the total weight of the polyamide composition. In terms of lower limits, the polyamide composition comprises the first copper-containing heat stabilizer in an amount of greater than 0.01 wt %, e.g., greater than 0.02 wt %, greater than 0.04 wt %, greater than 0.05 wt %, greater than 0.06 wt %, greater than 0.08 wt %, greater than 0.1 wt %, greater than 0.12 wt %, greater than 0.14 wt %, or greater than 0.15 wt %, based on the total weight of the polyamide composition. These specific amounts of the first copper-containing heat stabilizer have been found to provide good heat aging performance while also meeting a non-halogen rating.

[0029] In some embodiments, the first copper thermal stabilizer may comprise a copper-based compound in which copper is bound to another compound (e.g., free copper). In some embodiments, the first copper thermal stabilizer comprises a copper halide and an organophosphorus compound, such as a copper halide complexed with an organophosphorus compound. For example, the organophosphorus compound may include an organic phosphite, such as triphenyl phosphite, tris-(2,6-dimethylphenyl) phosphite, tris-(mixed mono- and di-nonylphenyl) phosphite, etc.; triphenylphosphine, phosphonates such as dimethylphenylphosphonate, etc., phosphates such as trimethyl phosphate, or a combination comprising at least one of the foregoing thermal stabilizers. In some aspects, the first thermal stabilizer is a copper halide complexed with triphenylphosphine or triphenyl phosphite. In some aspects, the first copper thermal stabilizer is a copper iodide complexed with triphenylphosphine or triphenyl phosphite.

[0030] In some aspects, the first copper-containing thermal stabilizer comprises a copper halide and an organophosphorus compound. The organophosphorus compound can be triphenylphosphine or triphenyl phosphite. The organophosphorus compound and the copper halide can form a complex, such as copper halide (I) / bis (triphenylphosphine), copper halide (I) / bis (triphenyl phosphite), copper iodide (I) / bis (triphenylphosphite), and / or copper iodide (I) / bis (triphenyl phosphite).

[0031] In some aspects, the first copper-containing thermal stabilizer comprises a copper halide and a chlorine-containing organophosphorus compound. The chlorine-containing organophosphorus compound can be a chlorine-containing phosphate and / or a chlorine-containing polyphosphonate. The chlorine-containing organophosphorus compound and the copper halide can form a complex, such as copper (I) halide / bis (chlorine-containing phosphate), copper (I) halide / bis (chlorine-containing polyphosphonate), copper (I) iodide / bis (chlorine-containing phosphate) and / or copper (I) iodide / bis (chlorine-containing polyphosphonate).

[0032] In some embodiments, the polyamide composition may include a second thermal stabilizer. In some embodiments, the second thermal stabilizer is a (second) copper-containing thermal stabilizer. The second copper-containing thermal stabilizer can be added to the polyamide composition to supplement the first copper-containing thermal stabilizer and / or maintain a non-halogen rating. For example, in some embodiments, when the content of the first copper-containing thermal stabilizer is limited to meet the non-halogen rating, the second copper-containing thermal stabilizer can be added to provide good heat aging performance to the polyamide composition.

[0033] In some aspects, the second copper thermal stabilizer can comprise a metal halide and an alkali metal salt. In some aspects, the metal halide can comprise copper in combination with a halogen (e.g., iodide or bromine). In some aspects, the metal halide can comprise potassium in combination with a halogen (e.g., iodide or bromine). In some aspects, the second copper thermal stabilizer can comprise one or more of CuI, CuBr, KI, or KBr.

[0034] In some embodiments, the amount of the second copper-containing thermal stabilizer present in the polyamide composition is from 0.01 wt % to 3 wt %, e.g., from 0.05 wt % to 2.8 wt %, from 0.1 wt % to 2.6 wt %, from 0.2 wt % to 2.4 wt %, from 0.4 wt % to 2.2 wt %, from 0.6 wt % to 2.1 wt %, from 0.8 wt % to 2 wt %, from 1 wt % to 1.8 wt %, or from 1.2 wt % to 1.6 wt %, based on the total weight of the polyamide composition. In terms of upper limits, the amount of the second copper-containing thermal stabilizer present in the polyamide composition is less than 3 wt %, e.g., less than 2.9 wt %, less than 2.8 wt %, less than 2.6 wt %, less than 2.2 wt %, less than 2.1 wt %, less than 2 wt %, less than 1.8 wt %, less than 1.6 wt %, or less than 1.5 wt %, based on the total weight of the polyamide composition. In terms of lower limits, the amount of the second copper-containing heat stabilizer present in the polyamide composition is greater than 0.01 wt%, e.g., greater than 0.05 wt%, greater than 0.1 wt%, greater than 0.2 wt%, greater than 0.4 wt%, greater than 0.6 wt%, greater than 0.8 wt%, greater than 1 wt%, greater than 1.2 wt%, or greater than 1.4 wt%, based on the total weight of the polyamide composition.

[0035] In some embodiments, the second copper-containing thermal stabilizer contains (small amounts of) free copper, such as elemental copper or copper ions, which may infiltrate the polyamide composition. As used herein, "free copper" refers to unbound elemental copper or copper ions. It has been found that free copper may precipitate from the polyamide composition and cause discoloration, thereby affecting the surface appearance of the molded article. In addition, free copper present in the polyamide composition may adversely affect other properties of the polyamide composition, including, but not limited to, for example, heat aging resistance, dimensional accuracy, and chemical resistance of the molded article. Reduction or elimination of free copper in the stabilizer or polyamide composition often surprisingly provides improvements in these properties.

[0036] In some embodiments, the amount of free copper, such as elemental copper or copper ions, present in the polyamide composition is from 100 ppm to 200 ppm, e.g., from 105 ppm to 290 ppm, from 110 ppm to 290 ppm, from 115 ppm to 185 ppm, from 120 ppm to 180 ppm, from 125 ppm to 175 ppm, from 130 ppm to 170 ppm, from 135 ppm to 165, from 140 ppm to 160 ppm, or from 145 ppm to 155 ppm. In terms of upper limits, the amount of free copper present in the polyamide composition is less than 200 ppm, e.g., less than 195 ppm, less than 190 ppm, less than 185 ppm, less than 180 ppm, less than 175 ppm, less than 170 ppm, or less than 165 ppm. In terms of lower limits, the amount of free copper present in the polyamide composition is greater than 100 ppm, e.g., greater than 105 ppm, greater than 110 ppm, greater than 115 ppm, greater than 120 ppm, greater than 125 ppm, greater than 130 ppm, greater than 135 ppm, or greater than 140 ppm.

[0037] The above-mentioned amount of free copper found in the polyamide composition, for example, less than 200ppm, can suppress the coloring caused by precipitation. The surface appearance of the molded product can be further improved. In addition, reducing the amount of free copper suppresses the deterioration of the hydrogen bond of the amide group caused by the excessive coordination bond of the polyamide resin and copper, suppresses the wear resistance, fatigue resistance, and heat aging resistance of the molded product, and improves chemical resistance. The content of free copper present in the polyamide resin composition can be within the above-mentioned desired range by appropriately adjusting the amount of the copper compound. In addition, the copper that is complexed or otherwise in a form that reduces and / or prevents copper migration, for example non-migrating copper, reduces the contact corrosion of copper from the final product.

[0038] In some embodiments, a copper complexing agent, such as a phosphorus-containing compound, is added to the polyamide composition to complex the free copper of the second copper-containing thermal stabilizer. In other words, the copper complexing agent complexes the free copper in the polyamide composition to reduce the amount of free copper ions in the polyamide composition. In some embodiments, the second copper-containing thermal stabilizer may comprise complexed copper. In some aspects, the second copper-containing thermal stabilizer may comprise copper complexed with phosphorus. In some aspects, the second copper-containing thermal stabilizer is supplied to the polyamide composition together with the complexed copper so that no free copper is introduced into the polyamide composition.

[0039] In some embodiments, the second copper-containing thermal stabilizer does not include any halogen-containing compounds. In some aspects, the second copper-containing thermal stabilizer does not include any bromine-containing compounds. In some aspects, the second copper-containing thermal stabilizer does not include any chlorine-containing compounds.

[0040] In some embodiments, the total amount of halogen provided by the heat stabilizer in the polyamide composition is less than 1500ppm, to achieve non-halogen grade. For example, the total amount of the halogen compound contributed by the first heat stabilizer and the second heat stabilizer is less than 1500ppm. In some embodiments, the total amount of bromine contributed by the heat stabilizer in the polyamide composition is less than 900ppm bromine. In some embodiments, the total amount of bromine contributed by the heat stabilizer in the polyamide composition is 100 to 900ppm, for example, 150 to 880ppm, 200 to 860ppm, 250 to 840ppm, 300 to 820ppm, 350 to 800ppm or 400 to 780ppm. With regard to the upper limit, the total amount of bromine contributed by the heat stabilizer in the polyamide composition is less than 900ppm, for example, less than 880ppm, less than 860ppm, less than 840ppm, less than 820ppm, less than 800ppm, less than 780ppm, less than 760ppm or less than 740ppm. In terms of lower limits, the total amount of bromine in the polyamide composition contributed by the thermal stabilizer is greater than 100 ppm, e.g., greater than 150 ppm, greater than 200 ppm, greater than 250 ppm, greater than 300 ppm, greater than 350 ppm, greater than 400 ppm, greater than 450 ppm, or greater than 500 ppm.

[0041] In some embodiments, the total amount of chlorine contributed by the thermal stabilizer in the polyamide composition is less than 900 ppm. In some embodiments, the total amount of chlorine contributed by the thermal stabilizer in the polyamide composition is 100 to 900 ppm, for example, 150 to 880 ppm, 200 to 860 ppm, 250 to 840 ppm, 300 to 820 ppm, 350 to 800 ppm, or 400 to 780 ppm. In terms of upper limits, the total amount of chlorine contributed by the thermal stabilizer in the polyamide composition is less than 900 ppm, for example, less than 880 ppm, less than 860 ppm, less than 840 ppm, less than 820 ppm, less than 800 ppm, less than 780 ppm, less than 760 ppm, or less than 740 ppm. In terms of lower limits, the total amount of chlorine contributed by the thermal stabilizer in the polyamide composition is greater than 100 ppm, for example, greater than 150 ppm, greater than 200 ppm, greater than 250 ppm, greater than 300 ppm, greater than 350 ppm, greater than 400 ppm, greater than 450 ppm, or greater than 500 ppm.

[0042] In some embodiments, the total amount of bromine and chlorine contributed by the thermal stabilizer in the polyamide composition is less than 1500 ppm bromine. In some embodiments, the total amount of bromine and chlorine contributed by the thermal stabilizer in the polyamide composition is 100 to 1500 ppm, for example, 150 to 1400 ppm, 200 to 1300 ppm, 250 to 1200 ppm, 300 to 1100 ppm, 400 to 1000 ppm, 500 to 950 ppm, or 600 to 900 ppm. In terms of upper limits, the total amount of bromine and chlorine contributed by the thermal stabilizer in the polyamide composition is less than 1500 ppm, for example, less than 1450 ppm, less than 1400 ppm, less than 1350 ppm, less than 1300 ppm, less than 1250 ppm, less than 1200 ppm, less than 1150 ppm, or less than 1100 ppm. In terms of lower limits, the total amount of bromine and chlorine contributed by the thermal stabilizer in the polyamide composition is greater than 100 ppm, e.g., greater than 150 ppm, greater than 200 ppm, greater than 250 ppm, greater than 300 ppm, greater than 350 ppm, greater than 400 ppm, greater than 450 ppm, or greater than 500 ppm.

[0043] In an exemplary embodiment, the total maximum halogen (elemental fluorine, chlorine, and bromine) content of the polyamide composition is 1500 ppm or less, as determined using UL Halogen Test 746H. Amine-containing heat stabilizers

[0044] In some embodiments, the polyamide composition may include an amine-containing heat stabilizer. In some embodiments, the amine-containing heat stabilizer includes an aromatic amine, a hindered amine, or a combination thereof. In some embodiments, the amine-containing heat stabilizer includes bis(4-(1-methyl-1-phenylethyl)phenyl)amine, 2-ethyl-2'-ethoxyoxalanilide, dimethylglyoxime, 2,2'-bipyridine, 1,10-phenanthroline, o-phenylenediamine, 1,2-diaminocyclohexane, 1,4-diaminobutane, urea, 8-hydroxyquinoline, substituted urea, and a combination thereof.

[0045] Suitable commercially available amine-containing heat stabilizers include NYLOSTAB S-EED from Clariant, NAUGARD 445 from Addivant, OKABEST FLEX, OKABEST ULTRA-FLEX, OKABEST S-FLEX 2, OKABEST S-FLEX 3, OKAFLEX U, and OKAFLEX EM from OKA-Tec, or combinations thereof.

[0046] In some embodiments, the polyamide composition comprises an amine-containing heat stabilizer in an amount of 0.1 to 2 wt%, such as 0.2 to 1.8 wt%, 0.3 to 1.7 wt%, 0.4 to 1.6 wt%, 0.5 to 1.5 wt%, 0.6 to 1.4 wt%, 0.7 to 1.3 wt%, 0.8 to 1.2 wt%, or 0.9 to 1.1 wt%, based on the total weight of the polyamide composition. In terms of upper limits, the polyamide composition comprises an amine-containing heat stabilizer in an amount of less than 2 wt%, such as less than 1.9 wt%, less than 1.8 wt%, less than 1.6 wt%, less than 1.4 wt%, less than 1.2 wt%, or less than 1.1 wt%. In terms of lower limits, the polyamide composition comprises an amine-containing heat stabilizer in an amount greater than 0.1 wt%, e.g., greater than 0.2 wt%, greater than 0.3 wt%, greater than 0.4 wt%, greater than 0.5 wt%, greater than 0.6 wt%, greater than 0.7 wt%, greater than 0.8 wt%, or greater than 0.9 wt%, based on the total weight of the polyamide composition. These specific amounts of amine-containing heat stabilizer have been found to provide good heat aging properties while also meeting non-halogen ratings. Phenolic heat stabilizer

[0047] In some embodiments, the polyamide composition may include a phenolic heat stabilizer. In some embodiments, the phenolic heat stabilizer includes N,N'-hexane-1,6-diylbis[3-(3,5-di-tert-butyl-4-hydroxyphenylpropionamide)]; pentaerythritol-tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]; N,N'-hexamethylenebis(3,5-di-tert-butyl-4-hydroxyhydrocinnamic acid); triethylene glycol-bis[3-(3-tert-butyl-5-methyl-4-hydroxyphenyl)propionate]; 3,9-bis{2-[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionyloxy]-1,1-dimethylethyl}-2,4,8,10-tetraoxaspiro[5,5]undecane ; 3,5-di-tert-butyl-4-hydroxybenzylphosphonate-diethyl ester; 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene; bis(2,4-dicumylphenyl)pentaerythritol diphosphite plus 1% triisopropanolamine, tetrakis(methylene(3,5-di-(tert-butyl)-4-hydroxyhydrocinnamate))methane, N,N'-hexamethylenebis(3,5-di-(tert-butyl)hydroxyhydrocinnamic acid), bis(2,4-dicumylphenyl)pentaerythritol diphosphite plus stabilizer; and 1,3,5-tris(4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl)isocyanurate, or a combination thereof.

[0048] Suitable commercially available phenolic heat stabilizers include IRGANOX 1010, IRGANOX 1098, and IRGANOX 1076 from CIBA Specialty Chemicals, IRGAFOS 168 from CIBA Specialty Chemicals, DOVERPHOS S-9228T from Dover Chemical Corporation, or combinations thereof.

[0049] In some embodiments, the polyamide composition comprises a phenolic heat stabilizer in an amount of 0.1 to 2 wt %, such as 0.2 to 1.8 wt %, 0.3 to 1.7 wt %, 0.4 to 1.6 wt %, 0.5 to 1.5 wt %, 0.6 to 1.4 wt %, 0.7 to 1.3 wt %, 0.8 to 1.2 wt %, or 0.9 to 1.1 wt %, based on the total weight of the polyamide composition. In terms of upper limits, the polyamide composition comprises a phenolic heat stabilizer in an amount of less than 2 wt %, such as less than 1.9 wt %, less than 1.8 wt %, less than 1.6 wt %, less than 1.4 wt %, less than 1.2 wt %, or less than 1.1 wt %. In terms of lower limits, the polyamide composition comprises a phenolic heat stabilizer in an amount greater than 0.1 wt%, e.g., greater than 0.1 wt%, greater than 0.2 wt%, greater than 0.3 wt%, greater than 0.4 wt%, greater than 0.5 wt%, greater than 0.6 wt%, greater than 0.7 wt%, greater than 0.8 wt%, or greater than 0.9 wt%, based on the total weight of the polyamide composition. These specific amounts of phenolic heat stabilizer have been found to provide good heat aging properties while also meeting the non-halogen rating. Contains phosphorous acid Salt Heat stabilizer

[0050] In some embodiments, the polyamide composition may include a phosphite-containing heat stabilizer. In some embodiments, the phosphite-containing heat stabilizer may include an alkaline phosphite. In some embodiments, the phosphite-containing heat stabilizer may include manganese phosphite, sodium phosphite, sodium hydrogen phosphite, potassium phosphite, aluminum phosphite, calcium phosphite, magnesium phosphite, or a combination thereof. In some embodiments, the phosphite-containing heat stabilizer may include an alkali metal-aluminum phosphite. Suitable commercially available phosphite-containing heat stabilizers include H10 (available from Brüggemann Chemical).

[0051] In some embodiments, the polyamide composition comprises a phosphite-containing heat stabilizer in an amount of 1 to 5 wt %, for example, 1.5 to 4.8 wt %, 1.8 to 4.6 wt %, 2 to 4.4 wt %, 2.5 to 4.2 wt % or 3 to 4 wt %, based on the total weight of the polyamide composition. With regard to an upper limit, the polyamide composition comprises a phosphite-containing heat stabilizer in an amount of less than 5 wt %, for example, less than 4.8 wt %, less than 4.6 wt %, less than 4.4 wt %, less than 4.2 wt % or less than 4 wt %. With regard to a lower limit, the polyamide composition comprises a phosphite-containing heat stabilizer in an amount greater than 1 wt %, for example, greater than 1.5 wt %, greater than 1.8 wt %, greater than 2 wt %, greater than 2.4 wt %, greater than 2.6 wt %, greater than 2.8 wt % or greater than 3 wt %, based on the total weight of the polyamide composition. Copper complexing agent

[0052] The copper complexing agent used in the compositions described herein can vary widely. In some embodiments, a copper complexing agent can be added to the polyamide composition to stabilize free copper. For example, as described above, the copper complexing agent can be a phosphorus-containing compound that complexes free copper in the polyamide composition to reduce the amount of free copper. In some cases, any free copper present in the heat stabilizer can be complexed by the copper complexing agent before the heat stabilizer is added to the polyamide composition.

[0053] In some aspects, the copper complexing agent is a phosphate, such as a polyphosphate. Exemplary copper complexing agents include phosphinates, aluminum diethylphosphinate, and melamine polyphosphate. Other examples include condensation products of melamine and / or reaction products of melamine with polyphosphoric acid and / or reaction products of melamine condensation products with polyphosphoric acid, or mixtures thereof; or include melem, melam, cyanuramide, dimelamine pyrophosphate, melamine polyphosphate, melem polyphosphate, melam polyphosphate, cyanuramide polyphosphate, and / or mixed polysalts thereof; or include a compound of formula (NH4) y H 3-y PO4 and / or (NH4 PO3) z Nitrogen-containing phosphates wherein y is 1 to 3 and z is 1 to 10000. Other examples include mixed alkali aluminum phosphites and mixtures thereof with alkali metal salts.

[0054] In some aspects, the copper complexing agent can be a chlorine-containing phosphate, a chlorine-containing polyphosphonate, or a chlorine-containing organophosphorus.

[0055] In some aspects, the copper complexing agent can be a phosphorus-free complexing agent. Exemplary additional copper complexing agents include those produced by Dow A phosphorus-free, non-corrosive silicone powder sold as 43-821. Additional copper complexing agents include zinc borate, calcium hypophosphite, and aluminum hydrogen phosphite in combination with aluminum salts.

[0056] In some embodiments, the composition comprises a copper-complexing agent, for example, a copper-chelating agent of an amount of 0.1 to 10 wt %, 0.5 to 10 wt %, 1.5 to 2.5 wt %, 2.5 to 3.5 wt %, 3.5 to 4.5 wt % or 4.5 wt % respectively. In some embodiments, the composition comprises a copper-complexing agent, for example, a copper-chelating agent of an amount of 0.1 to 10 wt %, 0.5 ...% or 0.5 to 10 wt % respectively. Non-halogenated flame retardants

[0057] Typically, non-halogenated flame retardants are used because of the desire to avoid the potential adverse environmental effects of halogenated flame retardants.

[0058] Exemplary non-halogenated flame retardants include flame retardants containing phosphorus or melamine. Melamine flame retardants are known in the art and include melamine phosphate and melamine cyanurate. Phosphate esters are particularly suitable. These compounds include, for example, alkyl and aryl esters of phosphoric acid, such as trimethyl phosphate, triethyl phosphate, tributyl phosphate, trioctyl phosphate, tributoxyethyl phosphate, triphenyl phosphate, tricresyl phosphate, cresyl diphenyl phosphate, octyl diphenyl phosphate, tris(2-ethylhexyl) phosphate, diisopropylphenyl phosphate, tri(xylyl) phosphate, tri(isopropylphenyl) phosphate, trinaphthyl phosphate, bisphenol A diphenyl phosphate and resorcinol diphenyl phosphate. Commonly used triaryl phosphates include, for example, triphenyl phosphate (TPP), cresyl diphenyl phosphate and tricresyl phosphate. Inorganic phosphate flame retardants can also be used, such as ammonium polyphosphate (which is used as an intumescent flame retardant).

[0059] Phosphinate flame retardants, including Those sold as OP1230 and OP1400 may be used in the compositions described herein.Phosphine flame retardants may be desirable due to their anti-corrosion properties.

[0060] In terms of lower limits, the non-halogenated flame retardant is present in an amount of at least 5 wt %, e.g., at least 7.5 wt %, at least 10 wt %, or at least 12.5 wt %, based on the total weight of the composition. In terms of upper limits, the non-halogenated flame retardant is present in an amount of less than 25 wt %, e.g., less than 22.5 wt %, less than 20 wt %, or less than 17.5 wt %. In terms of ranges, the non-halogenated flame retardant is present in an amount of 5 to 25 wt %, e.g., 7.5 to 22.5 wt %, 10 to 20 wt %, or 12.5 to 17.5 wt %.

[0061] In some embodiments, non-halogenated flame retardants can function as both flame retardants and complexing agents. For example, for a heat stabilizer added to a polyamide composition along with an unbound component (e.g., copper), a small amount of non-halogenated flame retardant can complex a portion of the heat stabilizer. polyamide

[0062] Polyamides can vary widely, and additional discussion and examples of suitable polyamides are provided herein. As mentioned above, in some embodiments, the polyamide has a high carboxyl end group content. It is believed that high CEG polyamides work well with the above-mentioned thermal stabilizers because the use of polyamides with reduced reactivity, such as by lower amine end groups, increased inert acetic acid end groups and / or increased carboxylic acid end groups, has led to improved thermal stability and other desirable properties. As an additional benefit, the molecular weight of the composition from initial formation to final compounding and molding is controlled.

[0063] Surprisingly and unexpectedly, it has been discovered that by controlling the ratio of carboxylic acid end groups to amine end groups in the polyamide resin, the increase in weight average molecular weight, number average molecular weight, z-average molecular weight, polydispersity index, and intrinsic viscosity from the polyamide resin to the final product through the compounding process is minimized. These improvements also provide synergistic improvements in mechanical properties, especially at high temperatures.

[0064] In some aspects, the ratio of carboxylic acid end groups to amine end groups in the polyamide resin is greater than 1.8: 1, e.g., greater than 1.9: 1, greater than 2: 1, greater than 2.1: 1, greater than 2.2: 1, greater than 2.3: 1, or greater than 2.4: 1. In terms of upper limits, the ratio of carboxylic acid end groups to amine end groups in the polyamide resin is 3: 1 or less, e.g., 2.975: 1 or less, 2.95: 1 or less, 2.925: 1 or less, 2.9: 1 or less, 2.875: 1 or less, 2.85: 1 or less, 2.825: 1 or less, 2.8: 1 or less, 2.775: 1 or less, 2.75: 1, 2.725: 1 or less, or 2.7: 1 or less. In terms of ranges, the ratio of carboxylic acid end groups to amine end groups in the polyamide resin can be from 1.81:1 to 3:1, e.g., from 1.9:1 to 3:1, from 2:1 to 3:1, from 2.1:1 to 2.975:1, from 2:1 to 2.95:1, from 2.2:1 to 2.925:1, from 2.3:1 to 2.9:1, or from 2.4:1 to 2.7:1, including all ranges and values ​​therebetween.

[0065] In some aspects, the carboxylic acid end groups are present in an amount of less than 175 μeq / gram of polyamide, e.g., less than 170 μeq / gram, less than 160 μeq / gram, or less than 150 μeq / gram. As a lower limit, the carboxylic acid end groups are present in an amount of at least 80 μeq / gram, e.g., at least 85 μeq / gram, at least 90 μeq / gram, or at least 95 μeq / gram. As a range, the carboxylic acid end groups can be present in an amount of 80 to 175 μeq / gram, e.g., 85 to 160 μeq / gram, 90 to 140 μeq / gram, or 95 to 120 μeq / gram.

[0066] In some aspects, the amine end groups are present in an amount of less than 50 μeq / gram of polyamide, e.g., less than 47 μeq / gram, less than 45 μeq / gram, or less than 43 μeq / gram. In terms of lower limits, the amine end groups are present in an amount of at least 5 μeq / gram, e.g., at least 10 μeq / gram, at least 15 μeq / gram, or at least 20 μeq / gram. In terms of ranges, the amine end groups may be present in an amount of 5 to 50 μeq / gram, e.g., 10 to 47 μeq / gram, 15 to 45 μeq / gram, or 20 to 43 μeq / gram.

[0067] As used herein, delta end groups (DEG or DEGs) is defined as the amount of amine end groups (-NH2) minus the amount of carboxylic acid end groups (-COOH). DEG calculation methods are well known.

[0068] As described above, the base polyamide composition uses specific ranges and / or limits of DEG levels. In some embodiments, the base polyamide composition has a DEG level in the range of -31 μeq / gram to -90 μeq / gram, e.g., -35 μeq / gram to -85 μeq / gram, -35 μeq / gram to -80 μeq / gram, -40 μeq / gram to -75 μeq / gram, -50 μeq / gram to -75 μeq / gram, -40 μeq / gram to -70 μeq / gram, -42 μeq / gram to -68 μeq / gram, -45 μeq / gram to -60 μeq / gram, -45 μeq / gram to -65 μeq / gram, -47 μeq / gram to -63 μeq / gram, -48 μeq / gram to -58 μeq / gram, -50 μeq / gram to -60 μeq / gram, or -52 μeq / gram to -57 μeq / gram. In terms of lower limits, the DEG level of the base polyamide composition may be greater than -85 μeq / gram, such as greater than -80 μeq / gram, greater than -75 μeq / gram, greater than -70 μeq / gram, greater than -68 μeq / gram, greater than -65 μeq / gram, greater than -63 μeq / gram, greater than -60 μeq / gram, greater than -58 μeq / gram, greater than -55 μeq / gram, greater than -53 μeq / gram, or greater than -50 μeq / gram. In terms of upper limits, the DEG level of the base polyamide composition may be less than -30 μeq / gram, such as less than -35 μeq / gram, less than -40 μeq / gram, less than -42 μeq / gram, less than -45 μeq / gram, less than -48 μeq / gram, less than -50 μeq / gram, or less than -52 μeq / gram. It has also been discovered that these specific DEG levels provide an unexpected combination of advantageous synergistic properties in the final product after compounding as described herein.

[0069] To achieve desired properties, polyamide end groups can be controlled. Nylon 6,6, for example, contains amino and acid end groups. Acid end groups include inert acetic acid end groups and reactive carboxylic acid end groups. Unbalanced polyamide PA-6,6 can be achieved in various ways known to those skilled in the art, such as during polymerization by stoichiometrically unbalancing the diamine compound and diacid, or by adding compounds during extrusion to achieve an unbalanced final amine in polyamide 6,6.

[0070] In some cases, the end group level (and resulting DEG level) can be obtained / achieved / controlled by controlling the amount of excess hexamethylenediamine (HMD) in the polymerization reaction mixture. HMD is believed to be more volatile than the (di)carboxylic acids (e.g., adipic acid) used in the reaction. HMD and the carboxylic acid act as a balancing formula (based on the theoretical number of end groups), and the balance between the two (and therefore the DEG) can be adjusted to obtain the desired properties in the polyamide composition.

[0071] In some cases, the end group level (and resulting DEG level) can be obtained / achieved / controlled by introducing (mono)acids and / or (mono)amines, e.g. by "capping" some of the terminal structures to achieve a desired DEG level, e.g. a desired end group balance.

[0072] In some cases, it has been found that the use of monofunctional endcapping provides surprising benefits in controlling, for example, slowing the polymerization rate in an SSP process. Without being bound by theory, it is believed that the endcapping (1) limits the amount of reactive ends; and (2) limits the degree of polymerization to a finite number. In some cases, the more endcapping is used, the lower the (maximum) molecular weight can be (at 100% conversion). Both the former and the latter can be achieved by creating a high DEG system. Monofunctional addition will increase DEG levels.

[0073] In one embodiment, the (mono)acid and / or (mono)amine is added at a level of 1 to 40 μeq / gram, for example, 1 μeq / gram to 35 μeq / gram, 3 μeq / gram to 35 μeq / gram, 3 μeq / gram to 30 μeq / gram, 5 μeq / gram to 30 μeq / gram, 5 μeq / gram to 25 μeq / gram, 7 μeq / gram to 25 μeq / gram, 7 μeq / gram to 20 μeq / gram, 10 μeq / gram to 20 μeq / gram, or 10 μeq / gram to 15 μeq / gram. In terms of upper limits, the (mono)acid and / or (mono)amine may be introduced at a level of less than 40 μeq / gram, for example, less than 35 μeq / gram, less than 30 μeq / gram, less than 25 μeq / gram, less than 20 μeq / gram, or less than 15 μeq / gram. In terms of lower limits, the (mono)acid and / or (mono)amine may be incorporated at levels greater than 1 μeq / gram, eg, greater than 3 μeq / gram, greater than 5 μeq / gram, greater than 7 μeq / gram, or greater than 10 μeq / gram.

[0074] Exemplary (mono) acids include, but are not limited to, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, octanoic acid, palmitic acid, myristic acid, decanoic acid, undecanoic acid, dodecanoic acid, oleic acid, or stearic acid, or any combination thereof. Exemplary (mono) amines include, but are not limited to, benzylamine, ethylamine, propylamine, butylamine, pentylamine, hexylamine, 2-ethyl-1-hexylamine, heptylamine, octylamine, nonylamine, decylamine, undecylamine, dodecylamine, pentylamine, tert-butylamine, tetradecylamine, hexadecylamine, or octadecylamine, or any combination thereof.

[0075] After the polyamide is dissolved, the amount of amino end groups and / or acid is determined potentiometrically. A method is described, for example, in the "Encyclopedia of Industrial Chemical Analysis," Volume 17, Page 293, 1973. The amount of amino end groups (GTA) and / or acid (BMS) can be determined by potentiometric titration after the polyamide is completely dissolved in trifluoroethanol and an excess of a strong base is added. The alkaline substance is then titrated with an aqueous solution of a strong acid. The amount of chain limiter is calculated from the ratio between the molar amount of chain limiter added and the mass of the product polymer. The amount of chain limiter can also be determined by hydrolyzing the polyamide and subsequently analyzing by liquid chromatography.

[0076] In some embodiments, the polyamide includes nylon 66, and copolymers, blends, and alloys of nylon 66 and nylon 6. Other embodiments include nylon derivatives, copolymers, terpolymers, blends and alloys containing or made from nylon 66 or nylon 6, copolymers or terpolymers having the above repeating units, including but not limited to: N6T / 66, N612, N6 / 66, N6I / 66, N11 and N12, where "N" represents nylon. Another preferred embodiment includes high temperature nylon ("HTN") and blends, derivatives, copolymers or terpolymers containing them. In addition, another preferred embodiment includes long chain aliphatic polyamides prepared with long chain diacids and blends, derivatives or copolymers containing them.

[0077] As used herein, polyamide compositions and similar terms refer to compositions containing polyamides, including copolymers, terpolymers, polymer blends, alloys, and derivatives of polyamides. Additionally, as used herein, "polyamide" refers to a polymer having a bond of an amino group of one molecule and a carboxylic acid group of another molecule as a component. In some aspects, polyamide is the component present in the largest amount. For example, a polyamide containing 40% by weight nylon 6, 30% by weight polyethylene, and 30% by weight polypropylene is referred to herein as a polyamide because the nylon 6 component is present in the largest amount. Additionally, a polyamide containing 20% ​​by weight nylon 6, 20% by weight nylon 66, 30% by weight polyethylene, and 30% by weight polypropylene is also referred to herein as a polyamide because the nylon 6 and nylon 66 components are the components present in the largest amount.

[0078] Exemplary polyamides and polyamide compositions are described in Kirk-Othmer, Encyclopedia of Chemical Technology, Vol. 18, pp. 328-371 (Wiley 1982), the disclosure of which is incorporated herein by reference.

[0079] In simple terms, polyamides are generally considered to be compounds containing repeating amide groups as part of the main polymer chain. Linear polyamides are of particular interest and can be formed by the condensation of difunctional monomers. Polyamides are commonly referred to as nylons. Although they are generally considered condensation polymers, polyamides are also formed by addition polymerization. This preparation method is particularly important for certain polymers, such as nylon 6, in which the monomer is a cyclic lactam. Specific polymers and copolymers and their preparation methods are described in the following patents: U.S. Patents 4,760,129; 5,504,185; 5,543,495; 5,698,658; 6,011,134; 6,136,947; 6,169,162; 7,138,482; 7,381,788; and 8,759,475.

[0080] Using polyamides, particularly nylon, in commercial applications offers many advantages. Nylons are generally chemically and temperature resistant, resulting in superior performance compared to other particles. They are also known to have improved strength, elongation, and abrasion resistance compared to other polymers. Nylons are also very versatile, allowing them to be used in a variety of applications.

[0081] One class of polyamides that is particularly preferred for some applications includes high temperature nylons (HTN's), as described in Glasscock et al., High Performance Polyamides Fulfill Demanding Requirements for Automotive Thermal Management Components (DuPont), http: / / www2.dupont.com / Automotive / en_US / assets / downloads / knowledge%20center / HTN-whitepaper-R8.pdf, available online on June 10, 2016. Such polyamides generally include one or more structures as shown below:

[0082] Non-limiting examples of polymers included in the polyamide include polyamide, polypropylene and copolymers, polyethylene and copolymers, polyesters, polystyrene, polyurethanes, and combinations thereof.

[0083] The nylon nanofiber products described herein, including copolymers and terpolymers, may have a melting point between 223° C. and 390° C., such as 223 to 380° C., or 225 to 350° C. Additionally, depending on any additional polymeric materials added, the melting point may be greater than that of conventional nylon 6,6.

[0084] Other polymeric materials that can be used in the compositions of the present disclosure include addition polymers and condensation polymer materials, such as polyolefins, polyacetals, polyamides (as previously discussed), polyesters, cellulose ethers and esters, polyalkylene sulfides, polyarylene oxides, polysulfones, modified polysulfone polymers, and mixtures thereof. Preferred materials within these broad categories include polyamides, polyethylene, polybutylene terephthalate (PBT), polypropylene, poly(vinyl chloride), polymethyl methacrylate (and other acrylic resins), polystyrene and its copolymers (including ABA-type block copolymers), poly(vinylidene fluoride), poly(vinylidene chloride), polyvinyl alcohol in various degrees of hydrolysis (87% to 99.5%) in cross-linked and non-cross-linked forms. Addition polymers tend to be glassy (Tg greater than room temperature). This is the case for polyvinyl chloride and polymethyl methacrylate, polystyrene polymer compositions or alloys, or for low crystallinity in the case of polyvinylidene fluoride and polyvinyl alcohol materials. The nylon copolymers embodied herein can be made by combining various diamine compounds, various diacid compounds, and various cyclic lactam structures in a reaction mixture, and then forming a nylon having monomeric materials randomly positioned within the polyamide structure. For example, nylon 66-6,10 material is a nylon made from hexamethylenediamine and a blend of C6 and C10 diacids. Nylon 6-66-6,10 is a nylon made by copolymerizing epsilon aminocaproic acid, hexamethylenediamine, and a blend of C6 and C10 diacid materials.

[0085] In some respects, polyethylene can be used in the compositions of the present disclosure. The polyethylene that can be used for the method for this embodiment of the present disclosure preferably can have a melt index of about 5 grams / 10 minutes to about 200 grams / 10 minutes, for example, about 17 grams / 10 minutes to about 150 grams / 10 minutes. Polyethylene preferably should have a density of about 0.85 grams / milliliter to about 1.1 grams / milliliter, for example, about 0.93 grams / milliliter to about 0.95 grams / milliliter. Most preferably, the melt index of polyethylene is about 150 and the density is about 0.93.

[0086] The blend or copolymer of polyethylene and nylon can be formed in any suitable manner. Typically, the nylon compound is nylon 66; however, other polyamides in the nylon family can be used. Mixtures of nylons can also be used. In one embodiment, polyethylene is blended with a mixture of nylon 6 and nylon 66. Polyethylene and nylon polymers are typically supplied in the form of pellets, chips, flakes, etc. The desired amount of polyethylene pellets or chips can be blended with nylon pellets or chips in a suitable mixing device (such as a rotating drum), and the resulting blend can be introduced into the feed hopper of a conventional extruder or meltblown line.

[0087] Furthermore, different species from the broad class of polymers can be blended. For example, high molecular weight styrene materials can be blended with low molecular weight high-impact polystyrene. Nylon-6 materials can be blended with nylon copolymers (e.g., nylon-6, 66, and 6,10 copolymers). Furthermore, polyvinyl alcohols with a low degree of hydrolysis (e.g., 87% hydrolyzed polyvinyl alcohol) can be blended with fully or superhydrolyzed polyvinyl alcohols with a degree of hydrolysis of 98 to 99.9% and higher. All of these blended materials can be crosslinked using an appropriate crosslinking mechanism. Nylons can be crosslinked using crosslinkers that react with nitrogen atoms in amide bonds. Polyvinyl alcohol materials can be crosslinked using hydroxyl-reactive materials (e.g., monoaldehydes such as formaldehyde, urea, melamine-formaldehyde resins and their analogs, boric acid and other inorganic compounds, dialdehydes, diacids, urethanes, epoxy resins, and other known crosslinking agents). Cross-linking technology is a well-known and well-understood phenomenon in which cross-linking agents react and form covalent bonds between polymer chains to significantly improve molecular weight, chemical resistance, overall strength, and resistance to mechanical degradation.

[0088] A preferred embodiment is a polyamide comprising a first polymer and a second, but different, polymer (different in polymer type, molecular weight, or physical properties) conditioned or treated at elevated temperatures. The polymer blend can be reacted and formed into a single chemical species or can be physically combined into a blended composition through an annealing process. Annealing means physical changes such as crystallinity, stress relaxation, or orientation. Preferred materials are chemically reacted into a single polymer species so that differential scanning calorimetry (DSC) analysis reveals a single polymeric material to produce improved stability when exposed to high temperatures, high humidity, and difficult operating conditions. Preferred materials for the blended polymer system include nylon 6; nylon 66; nylon 6,10; nylon (6-66-6,10) copolymer, and other linear, generally aliphatic nylon compositions.

[0089] Suitable polyamides may include, for example, 20% nylon 6, 60% nylon 66, and 20% by weight polyester. The polyamide may include a combination of miscible polymers or a combination of immiscible polymers. In some aspects, the composition is free of aromatic polyamide.

[0090] In some aspects, the polyamide can include nylon 6. In terms of lower limits, the polyamide can include nylon 6 in an amount of at least 0.1 wt%, e.g., at least 1 wt%, at least 5 wt%, at least 10 wt%, at least 15 wt%, or at least 20 wt%. In terms of upper limits, the polyamide can include nylon 6 in an amount of 99.9 wt% or less, 99 wt% or less, 95 wt% or less, 90 wt% or less, 85 wt% or less, or 80 wt% or less. In terms of ranges, the polyamide can include nylon 6 in an amount of 0.1 to 99.9 wt%, e.g., 1 to 99 wt%, 5 to 95 wt%, 10 to 90 wt%, 15 to 85 wt%, or 20 to 80 wt%.

[0091] In some aspects, the polyamide can include nylon 66. In terms of lower limits, the polyamide can include nylon 66 in an amount of at least 0.1 wt%, e.g., at least 1 wt%, at least 5 wt%, at least 10 wt%, at least 15 wt%, or at least 20 wt%. In terms of upper limits, the polyamide can include nylon 66 in an amount of 99.9 wt% or less, 99 wt% or less, 95 wt% or less, 90 wt% or less, 85 wt% or less, or 80 wt% or less. In terms of ranges, the polyamide can include nylon 66 in an amount of 0.1 to 99.9 wt%, e.g., 1 to 99 wt%, 5 to 95 wt%, 10 to 90 wt%, 15 to 85 wt%, or 20 to 80 wt%.

[0092] In some aspects, the polyamide is primarily nylon 66, such as at least 50 wt%, at least 60 wt%, at least 70 wt%, at least 80 wt%, at least 90 wt%, at least 95 wt%, or 100 wt% nylon 66.

[0093] In some aspects, the polyamide can include nylon 6I. In terms of lower limits, the polyamide can include nylon 6I in an amount of at least 0.1 wt%, e.g., at least 0.5 wt%, at least 1 wt%, at least 5 wt%, at least 7.5 wt%, or at least 10 wt%. In terms of upper limits, the polyamide can include nylon 6I in an amount of 50 wt% or less, 40 wt% or less, 35 wt% or less, 30 wt% or less, 25 wt% or less, or 20 wt% or less. In terms of ranges, the polyamide can include nylon 6I in an amount of 0.1 to 50 wt%, e.g., 0.5 to 40 wt%, 1 to 35 wt%, 5 to 30 wt%, 7.5 to 25 wt%, or 10 to 20 wt%.

[0094] In some aspects, the polyamide can include nylon 6T. In terms of lower limits, the polyamide can include nylon 6T in an amount of at least 0.1 wt%, e.g., at least 1 wt%, at least 5 wt%, at least 10 wt%, at least 15 wt%, or at least 20 wt%. In terms of upper limits, the polyamide can include nylon 6T in an amount of 50 wt% or less, 47.5 wt% or less, 45 wt% or less, 42.5 wt% or less, 40 wt% or less, or 37.5 wt% or less. In terms of ranges, the polyamide can include nylon 6T in an amount of 0.1 to 50 wt%, e.g., 1 to 47.5 wt%, 5 to 45 wt%, 10 to 42.5 wt%, 15 to 40 wt%, or 20 to 37.5 wt%.

[0095] Block copolymers can also be used in the methods of the present disclosure. For such copolymers, the choice of solvent swelling agent is important. The solvent is selected so that both blocks are soluble in the solvent. An example is an ABA (styrene-EP-styrene) or AB (styrene-EP) polymer in dichloromethane solvent. If one component is insoluble in the solvent, it will form a gel. An example of such a block copolymer is Styrene-b-butadiene and styrene-b-hydrogenated butadiene (ethylene propylene), Type e-caprolactam-b-ethylene oxide, Polyester-b-ethylene oxide and polyurethanes of ethylene oxide and isocyanate.

[0096] Addition polymers such as polyvinylidene fluoride, syndiotactic polystyrene, copolymers of vinylidene fluoride and hexafluoropropylene, polyvinyl alcohol, polyvinyl acetate, amorphous addition polymers such as poly(acrylonitrile) and its copolymers with acrylic acid and methacrylates, polystyrene, poly(vinyl chloride) and its various copolymers, poly(methyl methacrylate) and its various copolymers are known to be relatively easy to solution spin because they are soluble at low pressures and temperatures. It is contemplated that these can be melt-spun as a method of making nanofibers according to the present disclosure.

[0097] There are substantial advantages to forming polymer compositions comprising two or more polymeric materials in a polymer admixture, alloy format, or in a cross-linked chemically bonded structure. Without being bound by theory, it is believed that such polymer compositions improve physical properties by altering polymer attributes, such as improving polymer chain flexibility or chain mobility, overall molecular weight, and by forming a network of polymeric materials to provide reinforcement.

[0098] In one embodiment of this concept, two related polymer materials can be blended for beneficial properties. For example, a high molecular weight polyvinyl chloride can be blended with a low molecular weight polyvinyl chloride. Similarly, a high molecular weight nylon material can be blended with a low molecular weight nylon material.

[0099] The polyamide can have a relative viscosity (RV) of at least 20, e.g., at least 25, at least 30, or at least 35. In terms of upper limits, the polyamide can have an RV of less than 70, e.g., less than 60, less than 55, or less than 50. In terms of ranges, the polyamide can have an RV of 20 to 70, e.g., 25 to 60, 30 to 55, or 35 to 50.

[0100] In terms of lower limits, the composition can include at least 40% by weight, such as at least 42.5% by weight, at least 45% by weight, at least 47.5% by weight, at least 50% by weight, or at least 55% by weight of the polyamide. In terms of upper limits, the composition can include 70% by weight or less, 68% by weight or less, 66% by weight or less, 64% by weight or less, 62% by weight or less, or 60% by weight or less of the polyamide. In terms of ranges, the composition can include 40 to 70% by weight, such as 42.5 to 68% by weight, 45 to 66% by weight, 47.5 to 64% by weight, 50 to 62% by weight, or 55 to 60% by weight of the polyamide. Composition components

[0101] In some embodiments, the non-halogenated flame retardant polyamide composition comprises a polyamide in combination with a non-halogenated flame retardant, a copper-containing heat stabilizer, and optionally one or more additives.

[0102] In some embodiments, the non-halogenated flame retardant polyamide composition comprises a polyamide in combination with a non-halogenated flame retardant, a copper-containing heat stabilizer, a PA-6 homopolymer, and optionally one or more additives.

[0103] In some embodiments, the non-halogenated flame retardant polyamide composition comprises a polyamide in combination with a non-halogenated flame retardant, an amine-containing heat stabilizer, a PA-6 homopolymer, and optionally one or more additives.

[0104] In some embodiments, the non-halogenated flame retardant polyamide composition comprises a polyamide in combination with a non-halogenated flame retardant, a phenolic heat stabilizer, a PA-6 homopolymer, and optionally one or more additives.

[0105] The composition can be formed by mixing the above components and then extruding them through an extruder.It has been found that the compositions described herein are thermally stable and have reduced molecular weight gain during compounding and molding.

[0106] As described herein, a major advantage of the compositions described herein is that during the compounding and molding of the compositions, the expected increase in molecular weight is controlled and limited. In some aspects, the initial weight average molecular weight of the polyamide is at least 10,000, such as at least 12,500, at least 15,000, or at least 17,500. In terms of upper limits, the weight average molecular weight of the initial polyamide is 40,000 or less, such as 37,500 or less, 35,000 or less, or 32,500 or less. In terms of ranges, the weight average molecular weight of the initial polyamide is 10,000 to 40,000, such as 12,500 to 37,500, 15,000 to 35,000, or 17,500 to 32,500. In some aspects, the initial number average molecular weight of the polyamide is at least 10,000, such as at least 12,500, at least 15,000, or at least 17,500. In terms of upper limits, the number average molecular weight of the initial polyamide is 40,000 or less, e.g., 37,500 or less, 35,000 or less, or 32,500 or less. In terms of ranges, the number average molecular weight of the initial polyamide is from 10,000 to 40,000, e.g., from 12,500 to 37,500, from 15,000 to 35,000, or from 17,500 to 32,500. In some aspects, the initial Z-average molecular weight of the polyamide is at least 30,000, e.g., at least 35,000, at least 40,000, or at least 45,000. In terms of upper limits, the Z-average molecular weight of the initial polyamide is 70,000 or less, e.g., 65,000 or less, 60,000 or less, or 55,000 or less. In terms of ranges, the Z-average molecular weight of the initial polyamide is from 30,000 to 70,000, e.g., from 35,000 to 65,000, from 40,000 to 60,000, or from 45,000 to 55,000. The polydispersity index of the initial polyamide may be at least 1.2, e.g., at least 1.3, at least 1.4, at least 1.5, or at least 1.6. In terms of upper limits, the polydispersity index of the initial polyamide may be less than 2, e.g., less than 1.95, less than 1.9, less than 1.85, or less than 1.8. In terms of ranges, the polydispersity index of the initial polyamide may be from 1.2 to 2, e.g., from 1.3 to 1.95, from 1.3 to 1.9, from 1.4 to 1.85, from 1.5 to 1.8, or from 1.6 to 1.8. The intrinsic viscosity (in dl / g) of the initial polyamide may be at least 2, e.g., at least 2.1, at least 2.2, at least 2.3, or at least 2.4. In terms of upper limits, the intrinsic viscosity (in dl / g) of the initial polyamide can be less than 3, e.g., less than 2.9, less than 2.8, less than 2.7, or less than 2.6. In terms of ranges, the intrinsic viscosity (in dl / g) of the initial polyamide can be from 2 to 3, e.g., from 2.1 to 2.9, from 2.2 to 2.8, from 2.3 to 2.7, or from 2.4 to 2.6.

[0107] After compounding and extrusion or injection molding, the weight average molecular weight of the final product can be at least 20,000, such as at least 25,000, at least 30,000 or at least 35,000. In terms of upper limit, the weight average molecular weight of the final product is 100,000 or less, such as 97,500 or less, 95,000 or less or 92,500 or less. In terms of scope, the weight average molecular weight of the final product is 20,000 to 100,000, such as 25,000 to 97,500, 30,000 to 95,000 or 35,000 to 92,500. In some aspects, the number average molecular weight of the final product is at least 10,000, such as at least 12,500, at least 15,000 or at least 17,500. In terms of upper limit, the number average molecular weight of the final product is 40,000 or less, such as 37,500 or less, 35,000 or less or 32,500 or less. In terms of scope, the number average molecular weight of the final product is 10,000 to 40,000, such as 12,500 to 37,500, 15,000 to 35,000 or 17,500 to 32,500. In some aspects, the Z average molecular weight of the final product is at least 30,000, such as at least 35,000, at least 40,000 or at least 45,000. In terms of upper limit, the Z average molecular weight of the final product is 550,000 or less, such as 500,000 or less, 400,000 or less or 300,000 or less. In terms of ranges, the Z-average molecular weight of the final product is from 30,000 to 550,000, e.g., from 35,000 to 500,000, from 40,000 to 400,000, or from 45,000 to 300,000. The polydispersity index of the final product may be at least 1.8, e.g., at least 1.9, at least 2, or at least 2.1. In terms of upper limits, the polydispersity index of the final product may be less than 4, e.g., less than 3.85, less than 3.5, or less than 3. In terms of ranges, the polydispersity index of the final product may be from 1.8 to 4, e.g., from 1.9 to 3.85, from 2 to 3.5, or from 2.1 to 3. The intrinsic viscosity (in dl / g) of the final product may be at least 2, e.g., at least 2.1, at least 2.2, at least 2.3, or at least 2.4. In terms of upper limits, the intrinsic viscosity (in dl / g) of the final product can be less than 4, e.g., less than 3.9, less than 3.8, less than 3.7, or less than 3.6. In terms of ranges, the intrinsic viscosity (in dl / g) of the starting polyamide can be from 2 to 4, e.g., from 2.1 to 3.9, from 2.2 to 3.8, from 2.3 to 3.7, or from 2.4 to 3.6.

[0108] In terms of increase, the percent increase in weight average molecular weight from the initial polyamide to the final product can be at least 1%, such as at least 5%, at least 10%, or at least 20%. In terms of upper limits, the percent increase in weight average molecular weight from the initial polyamide to the final product can be less than 300%, such as less than 250%, less than 200%, or less than 100%. In terms of ranges, the percent increase in weight average molecular weight from the initial polyamide to the final product can be from 1% to 300%, such as from 5% to 250%, from 10% to 200%, or from 20% to 100%. In terms of increase, the percent increase in number average molecular weight from the initial polyamide to the final product can be at least 1%, such as at least 5%, at least 10%, or at least 15%. In terms of upper limits, the percent increase in number average molecular weight from the initial polyamide to the final product can be less than 100%, such as less than 50%, less than 25%, or less than 20%. In terms of ranges, the percent increase in weight average molecular weight from the initial polyamide to the final product can be from 1% to 100%, e.g., from 5% to 50%, from 10% to 25%, or from 15% to 20%. In terms of increases, the percent increase in Z-average molecular weight from the initial polyamide to the final product can be at least 1%, e.g., at least 5%, at least 10%, or at least 20%. In terms of upper limits, the percent increase in Z-average molecular weight from the initial polyamide to the final product can be less than 300%, e.g., less than 250%, less than 200%, or less than 100%. In terms of ranges, the percent increase in Z-average molecular weight from the initial polyamide to the final product can be from 1% to 300%, e.g., from 5% to 250%, from 10% to 200%, or from 20% to 100%. In terms of increases, the percent increase in polydispersity index from the initial polyamide to the final product can be at least 1%, e.g., at least 5%, at least 10%, or at least 20%. In terms of upper limits, the percent increase in polydispersity from the initial polyamide to the final product can be less than 200%, e.g., less than 100%, less than 50%, or less than 25%. In terms of ranges, the percent increase in polydispersity from the initial polyamide to the final product can be from 1% to 200%, e.g., from 5% to 100%, from 10% to 50%, or from 20% to 25%. In terms of increase, the percent increase in weight average molecular weight from the initial polyamide to the final product can be at least 1%, e.g., at least 5%, at least 10%, or at least 20%. In terms of upper limits, the percent increase in intrinsic viscosity from the initial polyamide to the final product can be less than 100%, e.g., less than 75%, less than 50%, or less than 25%. In terms of ranges, the percent increase in intrinsic viscosity from the initial polyamide to the final product can be from 1% to 100%, e.g., from 5% to 75%, from 10% to 50%, or from 20% to 25%.

[0109] In some embodiments, the non-halogenated flame retardant polyamide composition comprises a polyamide in combination with a non-halogenated flame retardant and a copper-containing heat stabilizer. The polyamide may include nylon 66, which may be present in an amount of 40 to 70 weight %, based on the total weight of the composition. The ratio of the carboxylic acid to the amine end groups of nylon 66 may be at least 1.8, such as 1.9-3. The flame retardant may be non-halogenated and may be present in an amount of 5 to 25 weight %, based on the total weight of the composition. The copper-containing heat stabilizer may include a copper halide and an organic halogenated-phosphorus compound, and based on the total weight of the polyamide composition, the amount of the copper-containing heat stabilizer may be less than 0.29 weight %. In some embodiments, the polyamide composition may include a second copper-containing heat stabilizer, and may be present in an amount of 0.01 to 3 weight %. In some embodiments, the polyamide composition may include a copper complexing agent, which may include a phosphorus-containing compound, and based on the total weight of the composition, its amount may be 0.1 to 10 weight %.

[0110] In some embodiments, the non-halogenated flame retardant polyamide composition comprises a polyamide in combination with a non-halogenated flame retardant, a PA-6 homopolymer and a copper-containing heat stabilizer. The polyamide may include nylon 66, which may be present in an amount of 40 to 70 weight %, based on the total weight of the composition. The ratio of the carboxylic acid to amine end groups of nylon 66 may be at least 1.8, such as 1.9-3. The flame retardant may be non-halogenated and may be present in an amount of 5-25 weight %, based on the total weight of the composition. The copper-containing heat stabilizer may include a copper halide and an organic halogenated-phosphorus compound, and may be present in an amount of less than 0.29 weight %, based on the total weight of the polyamide composition. The PA-6 homopolymer may be present in an amount of up to 20 weight %, based on the total weight of the composition. In some embodiments, the polyamide composition may include a second copper-containing heat stabilizer containing complexed copper, and may be present in an amount of 0.01 weight % to 3 weight %.

[0111] In some embodiments, the non-halogenated flame retardant polyamide composition comprises a polyamide in combination with a non-halogenated flame retardant, a PA-6 homopolymer, and an amine-containing heat stabilizer. The polyamide may include nylon 66, which may be present in an amount of 40 to 70 weight percent, based on the total weight of the composition. The ratio of carboxylic acid to amine end groups of nylon 66 may be at least 1.8, for example, 1.9-3. The flame retardant may be non-halogenated and may be present in an amount of 5 to 25 weight percent, based on the total weight of the composition. The PA-6 homopolymer may be present in an amount of up to 20 weight percent, based on the total weight of the composition. The amine-containing heat stabilizer may be present in an amount of 0.1 to 2 weight percent, based on the total weight of the composition.

[0112] In some embodiments, the non-halogenated flame retardant polyamide composition comprises a polyamide in combination with a non-halogenated flame retardant, a PA-6 homopolymer, and a phenolic heat stabilizer. The polyamide may include nylon 66, which may be present in an amount of 40 to 70 weight percent, based on the total weight of the composition. The ratio of carboxylic acid to amine end groups of nylon 66 may be at least 1.8, such as 1.9-3. The flame retardant may be non-halogenated and may be present in an amount of 5 to 25 weight percent, based on the total weight of the composition. The PA-6 homopolymer may be present in an amount of up to 20 weight percent, based on the total weight of the composition. The phenolic heat stabilizer may be present in an amount of 0.1 to 2 weight percent, based on the total weight of the composition. additive

[0113] In some aspects, the composition may also include various additives, such as fillers, reinforcing agents, stabilizers, additional heat stabilizers, colorants, etc., provided that the additives do not adversely affect the desired properties of the thermoplastic composition. Mixtures of additives may be used. These additives may be mixed at a suitable time during the mixing of the components for forming the polymer composition. Examples of other suitable additives include flow modifiers, glass fibers, stabilizers, additional heat stabilizers, fillers, and combinations thereof.

[0114] Typically, the additive can be present in an amount of at least 0.1 wt %, such as at least 0.5 wt %, at least 1 wt %, at least 5 wt % or at least 10 wt %. In terms of upper limits, the additive can be present in an amount of 55 wt % or less, 52.5 wt % or less, 50 wt % or less, 47.5 wt % or less or 45 wt % or less. In terms of ranges, the additive can be present in an amount of 0.1 to 55 wt %, such as 0.5 to 52.5 wt %, 1 to 50 wt %, 5 to 47.5 wt % or 10 to 45 wt %.

[0115] In some respects, composition can comprise glass fiber.Glass fiber can exist with the amount of at least 5 % by weight, for example at least 10 % by weight, at least 12.5 % by weight, at least 15 % by weight, at least 20 % by weight or at least 25 % by weight.With regard to the upper limit, glass fiber can exist with the amount of 45 % by weight or less, 42.5 % by weight or less, 40 % by weight or less, 37.5 % by weight or less or 35 % by weight or less.With regard to scope, glass fiber can exist with the amount of 5 to 45 % by weight, for example 10 to 42.5 % by weight, 12.5 to 40 % by weight, 15 to 37.5 % by weight, 20 to 35 % by weight or 25 to 35 % by weight.

[0116] In some embodiments, the composition may include an additive comprising a PA-6 homopolymer. The present inventors have discovered that using a PA-6 homopolymer (in specific amounts) in combination with the aforementioned heat stabilizers and a polyamide having a high ratio of carboxyl end groups to amine end groups results in a synergistic polyamide composition that provides excellent heat aging properties and a non-halogen grade. For example, in some embodiments, this combination of components provides the polyamide composition with excellent heat aging properties.

[0117] In some aspects, the composition can include a PA-6 homopolymer. The PA-6 homopolymer can be present in an amount of 0 to 20 wt %, such as 0.1 to 19 wt %, 0.5 to 18 wt %, 1 to 17 wt %, 2 to 16 wt %, 3 to 15 wt %, 4 to 14 wt %, 6 to 13 wt %, 7 to 12 wt %, or 8 to 11 wt %. In terms of upper limits, the PA-6 homopolymer can be present in an amount of 20 wt % or less, 19 wt % or less, 18 wt % or less, 16 wt % or less, 14 wt % or less, or 12 wt % or less. In terms of lower limits, the PA-6 homopolymer can be present in an amount greater than 0 wt %, such as greater than 0.1 wt %, greater than 0.5 wt %, greater than 1 wt %, greater than 2 wt %, greater than 4 wt %, greater than 6 wt %, or greater than 8 wt %.

[0118] Additional fillers or reinforcing agents include any materials known for these uses. For example, suitable fillers and reinforcing agents include silicate and silica powders such as aluminum silicate (mullite), synthetic calcium silicate, zirconium silicate, fused silica, crystalline silica graphite, natural silica sand, etc.; boron powders such as boron nitride powder, boron silicate powder, etc.; oxides such as TiO2, aluminum oxide, magnesium oxide, etc.; calcium sulfate (as its anhydrate, dihydrate or trihydrate); single crystal fibers or "whiskers" such as silicon carbide, aluminum oxide, boron carbide, iron, nickel, copper, etc.; fibers (including continuous fibers and chopped fibers) such as carbon fibers, glass fibers such as E-glass, etc.; sulfides such as molybdenum sulfide, zinc sulfide, etc.; barium compounds such as barium titanate, barium ferrite, barium sulfate, barite, etc.; metals and metal oxides such as particulate or fibrous aluminum, bronze, zinc, copper and nickel, etc.; plate-like fillers such as glass flakes, plate-like silicon carbide, aluminum diboride, aluminum flakes , steel flakes, etc.; fibrous fillers, such as short inorganic fibers, such as those derived from a blend comprising at least one of aluminum silicate, aluminum oxide, magnesium oxide, and calcium sulfate hemihydrate, etc.; natural fillers and reinforcing materials, such as wood flour obtained by pulverizing wood, fibrous products such as cellulose, cotton, sisal, jute, starch, cork flour, lignin, peanut shells, corn, rice hulls, etc.; reinforcing organic fibrous fillers formed from organic polymers capable of forming fibers such as poly(ether ketone), polyimide, polybenzoxazole, poly(phenylene sulfide), aromatic polyamide, aromatic polyimide, polyetherimide, etc.; and additional fillers and reinforcing agents, such as mica, feldspar, soot, magnesium aluminosilicate (fillite), quartz, quartzite, pearlite, tripoli, diatomaceous earth, carbon black, etc., or a combination comprising at least one of the above fillers or reinforcing agents. In some aspects, the composition does not contain aromatic polyamide.

[0119] Filler and reinforcing agent can be coated with metal material layer to promote conductivity, or with silane surface treatment to improve bonding and dispersion with polymer matrix resin.In addition, reinforcing filler can be provided in the form of monofilament or multifilament fiber, and can be used alone or in combination with other types of fibers, by for example co-braiding or core / skin type, side-by-side type or matrix-fibril type structure, or by other methods known to those skilled in the art of fiber manufacturing field.Suitable co-braiding structure includes for example glass fiber-carbon fiber, carbon fiber-aromatic polyimide (aramid (aramid)) fiber and aromatic polyimide fiber-glass fiber etc.Fiber filler can be for example with roving, woven fiber reinforcement material, such as 0-90 degree fabric etc.;Non-woven fiber reinforcement material, such as continuous strand mat (continuous strand mat), chopped strand mat, voile, paper and felt (felts) etc.;Or three-dimensional reinforcing material, such as braided form supply.In some aspects, said composition does not contain layered silicate.In addition, in some aspects, said composition does not contain ammonium polyphosphate and zinc polyphosphate. In other aspects, the composition is free of melamine cyanurate and zinc borate.

[0120] Antioxidants or "stabilizers" (e.g., hindered phenols and / or secondary aromatic amines) and, optionally, secondary antioxidants (e.g., phosphates and / or thioesters) may also be included as additives. Suitable antioxidant additives include, for example, organic phosphites, such as tris(nonylphenyl) phosphite, tris(2,4-di-tert-butylphenyl) phosphite, bis(2,4-di-tert-butylphenyl) pentaerythritol diphosphite, distearyl pentaerythritol diphosphite, and the like; alkylated monophenols or polyphenols; alkylated reaction products of polyphenols with dienes, such as tetrakis[methylene(3,5-di-tert-butyl-4-hydroxyhydrocinnamate)]methane; butylated reaction products of p-cresol or dicyclopentadiene; alkylated hydroquinones; hydroxylated thiodiphenyl ethers; alkylene-bisphenols; benzyl compounds; β-(3,5-di-tert-butyl-4-hydroxyhydrocinnamate)]methane; -hydroxyphenyl)-propionic acid esters with monohydric or polyhydric alcohols; esters of β-(5-tert-butyl-4-hydroxy-3-methylphenyl)-propionic acid with monohydric or polyhydric alcohols; esters of sulfanyl or thioaryl compounds, such as distearyl thiopropionate, dilauryl thiopropionate, ditridecyl thiodipropionate, octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, pentaerythritol-tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, etc.; amides of β-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionic acid, etc., or a combination comprising at least one of the above antioxidants. In some embodiments, antioxidants and heat stabilizers are used in combination to avoid adverse chemical effects during processing and to provide them with subsequent long-term resistance to external influences such as heat, UV light, climate, and oxygen (air).

[0121] Light stabilizers and / or ultraviolet (UV) absorbing additives may also be used. Suitable light stabilizer additives include, for example, benzotriazoles such as 2-(2-hydroxy-5-methylphenyl)benzotriazole, 2-(2-hydroxy-5-tert-octylphenyl)benzotriazole, and 2-hydroxy-4-n-octyloxybenzophenone, or a combination comprising at least one of the foregoing light stabilizers.

[0122] Suitable UV absorbing additives include, for example, hydroxybenzophenones; hydroxybenzotriazoles; hydroxybenzotriazines; cyanoacrylates; N,N'-oxanilides; benzoxazinones; 2-(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl)-phenol (CYASORB TM 5411); 2-Hydroxy-4-n-octyloxybenzophenone (CYASORB TM 531); 2-[4,6-bis(2,4-dimethylphenyl)-1,3,5-triazin-2-yl]-5-(octyloxy)-phenol (CYASORB TM1164); 2,2'-(1,4-phenylene)bis(4H-3,1-benzoxazin-4-one)(CYASORB TM UV-3638); 1,3-bis[(2-cyano-3,3-diphenylacryloyl)oxy]-2,2-bis[[(2-cyano-3,3-diphenylacryloyl)oxy]methyl]propane (UVINUL TM 3030); 2,2'-(1,4-phenylene)bis(4H-3,1-benzoxazin-4-one); 1,3-bis[(2-cyano-3,3-diphenylacryloyl)oxy]-2,2-bis[[(2-cyano-3,3-diphenylacryloyl)oxy]methyl]propane; nanoscale inorganic materials, such as titanium oxide, cerium oxide, and zinc oxide, all having a particle size of less than about 100 nanometers; and the like, or a combination comprising at least one of the foregoing ultraviolet absorbers, based on 100 parts by weight of the polymer component of the polymer composition.

[0123] In some aspects, filler includes zinc borate and zinc stearate. When included, filler can be present in an amount of at least 0.01 wt %, for example, at least 0.05 wt %, at least 0.075 wt % or at least 0.1 wt %. With regard to the upper limit, filler can be present in an amount of 5 wt % or less, 4.75 wt % or less, 4.5 wt % or less or 4.25 wt % or less. With regard to scope, filler can be present in an amount of 0.01 to 5 wt %, for example, 0.05 to 4.75 wt %, 0.1 to 4.5 wt % or 0.1 to 4.5 wt %. In some embodiments, polyamide composition can include one or more of zinc borate and zinc stearate.

[0124] In some embodiments, the polyamide composition may include zinc borate in an amount of at least 0.01 wt%, e.g., at least 0.05 wt%, at least 0.075 wt%, or at least 0.1 wt%. In terms of upper limits, the zinc borate may be present in an amount of 3 wt% or less, 2.75 wt% or less, 2.5 wt% or less, or 2 wt% or less. In terms of ranges, the zinc borate may be present in an amount of 0.01 to 3 wt%, e.g., 0.05 to 2.5 wt%, 0.1 to 2 wt%, or 0.5 to 1.5 wt%.

[0125] In some embodiments, the polyamide composition may include zinc borate in an amount of at least 0.001 wt%, e.g., at least 0.005 wt%, at least 0.01 wt%, or at least 0.05 wt%. In terms of upper limits, the zinc borate may be present in an amount of 2 wt% or less, 1.5 wt% or less, 1 wt% or less, or 0.5 wt% or less. In terms of ranges, the zinc borate may be present in an amount of 0.001 to 2 wt%, e.g., 0.005 to 1.5 wt%, 0.01 to 1 wt%, or 0.05 to 0.5 wt%.

[0126] Plasticizers, lubricants, and / or mold release additives may also be used. There is a significant overlap between these types of materials, including, for example, phthalates such as dioctyl-4,5-epoxy-hexahydrophthalate; tris-(octyloxycarbonylethyl) isocyanurate; tristearin; poly-α-olefins; epoxidized soybean oil; silicones, including silicone oils; esters such as fatty acid esters such as alkyl stearates, for example, methyl stearate; stearyl stearate, pentaerythritol tetrastearate, and the like; mixtures of methyl stearate and hydrophilic and hydrophobic nonionic surfactants (including polyethylene glycol polymers, polypropylene glycol polymers, and copolymers thereof), for example, methyl stearate and polyethylene-polypropylene glycol copolymers in a suitable solvent; waxes such as beeswax, montan wax, paraffin wax, and the like.

[0127] Colorants such as pigments and / or dye additives may also be present. Suitable pigments include, for example, inorganic pigments such as metal oxides and mixed metal oxides, such as zinc oxide, titanium dioxide, iron oxides, and the like; sulfides, such as zinc sulfide, and the like; aluminates; sodium sulfo-silicates; sulfates), chromates, etc.; carbon black; zinc ferrite; ultramarine blue; Pigment Brown 24; Pigment Red 101; Pigment Yellow 119; organic pigments, such as azos, diazos, quinacridones, perylenes, naphthalenetetracarboxylic acids, flavanthrones, isoindolinones, tetrachloroisoindolones, anthraquinones, tribenzo[cd,jk]pyrene-5,10-dione (anthanthrones), dioxazines, phthalocyanines and azo lakes; Pigment Blue 60, Pigment Red 122, Pigment Red 149, Pigment Red 177, Pigment Red 179, Pigment Red 202, Pigment Violet 29, Pigment Blue 15, Pigment Green 7, Pigment Yellow 147 and Pigment Yellow 150, or a combination comprising at least one of the foregoing pigments.

[0128] When present, these additional additives may be present in an amount of at least 0.01 wt %, e.g., at least 0.05 wt %, at least 0.075 wt %, or at least 0.1 wt %. In terms of upper limits, the additional additives may be present in an amount of 4 wt % or less, 3 wt % or less, 2.75 wt % or less, or 2.5 wt % or less. In terms of ranges, the additional additives may be present in an amount of 0.01 to 4 wt %, e.g., 0.05 to 3 wt %, 0.1 to 2.75 wt %, or 0 to 2.5 wt %. Performance characteristics

[0129] The non-halogenated flame-retardant polyamide compositions described herein exhibit surprising performance results. For example, the polyamide compositions exhibit excellent tensile strength over a wide temperature range, for example, from 190°C to 230°C. These performance parameters are exemplary, and the examples support other performance parameters contemplated by the present disclosure. For example, other performance characteristics obtained at other heat aging temperatures and durations are contemplated and can be used to characterize the disclosed polyamide compositions. It is contemplated that molded flame-retardant polyamide products produced from the polyamide compositions described herein may exhibit the properties described below.

[0130] In some embodiments, the polyamide composition retains 50% of its initial tensile strength after heat aging for greater than 800 hours, e.g., greater than 825 hours, greater than 850 hours, greater than 875 hours, greater than 900 hours, greater than 925 hours, greater than 950 hours, greater than 975 hours, or greater than 1000 hours, when heat aged at a temperature of about 195° C. and measured at 23° C. In terms of upper limits, the polyamide composition retains 50% of its initial tensile strength after heat aging for less than 1500 hours, e.g., less than 1475 hours, less than 1450 hours, less than 1425 hours, less than 1400 hours, or less than 1375 hours. In terms of ranges, the polyamide composition retains 50% of its initial tensile strength after heat aging for 800 hours to 1500 hours, e.g., 825 hours to 1450 hours, 875 hours to 1400 hours, 900 hours to 1375 hours, 950 hours to 1350 hours, 1000 hours to 1375 hours, or 1100 hours to 1400 hours.

[0131] In some embodiments, the polyamide composition retains 50% of its initial tensile strength after heat aging for greater than 600 hours, e.g., greater than 610 hours, greater than 625 hours, greater than 650 hours, greater than 675 hours, greater than 700 hours, greater than 725 hours, or greater than 750 hours, when heat aged at a temperature of about 205°C and measured at 23°C. In terms of upper limits, the polyamide composition retains 50% of its initial tensile strength after heat aging for less than 1200 hours, e.g., less than 1150 hours, less than 1100 hours, less than 1050 hours, or less than 1025 hours. In terms of ranges, the polyamide composition retains 50% of its initial tensile strength after heat aging for 600 hours to 1200 hours, e.g., 610 hours to 1150 hours, 625 hours to 1125 hours, 650 hours to 1100 hours, 670 hours to 1050 hours, 700 hours to 1000 hours, or 725 hours to 975 hours.

[0132] In some embodiments, the polyamide composition retains 50% of its initial tensile strength after heat aging for greater than 450 hours, e.g., greater than 460 hours, greater than 475 hours, greater than 500 hours, greater than 510 hours, greater than 525 hours, greater than 550 hours, greater than 575 hours, or greater than 600 hours, when heat aged at a temperature of about 215°C and measured at 23°C. In terms of upper limits, the polyamide composition retains 50% of its initial tensile strength after heat aging for less than 1000 hours, e.g., less than 975 hours, less than 950 hours, less than 925 hours, less than 900 hours, or less than 875 hours. In terms of ranges, the polyamide composition retains 50% of its initial tensile strength after heat aging for 450 to 1000 hours, e.g., 475 to 975 hours, 500 to 950 hours, 525 to 900 hours, 550 to 880 hours, 575 to 850 hours, or 600 to 825 hours.

[0133] This heat aging performance in the range of 190°C to 230°C (as shown in this section) illustrates the unexpected performance of the disclosed polyamide compositions. This also applies to performance characteristics such as tensile strength retention. Other temperature ranges, such as 190°C to 220°C or 210°C to 230°C, are also supported by the examples and are contemplated, but all of these specific performance characteristics are not specifically listed (for the sake of brevity and simplicity).

[0134] In some embodiments, the polyamide composition exhibits a tensile strength retention of at least 75%, e.g., at least 76%, at least 78%, at least 80%, or at least 82%, when heat aged at a temperature of about 155° C. for 1000 hours and measured at 23° C. In terms of upper limits, the tensile strength retention may be less than 99%, less than 98%, less than 95%, less than 92%, less than 90%, less than 88%, less than 86%, or less than 84%. In terms of ranges, the tensile strength retention may be in the range of 75% to 98%, e.g., 76% to 96%, 78% to 95%, 80% to 92%, or 82% to 90%.

[0135] In some embodiments, the polyamide composition exhibits a tensile strength retention of at least 60%, e.g., at least 62%, at least 64%, at least 66%, or at least 68%, when heat aged at a temperature of about 165° C. for 1000 hours and measured at 23° C. In terms of upper limits, the tensile strength retention may be less than 90%, less than 88%, less than 86%, or less than 84%. In terms of ranges, the tensile strength retention may be in the range of 60% to 90%, e.g., 62% to 88%, 65% to 85%, 68% to 82%, or 70% to 80%.

[0136] In some embodiments, the polyamide composition exhibits a tensile strength retention of at least 50%, e.g., at least 52%, at least 54%, at least 56%, or at least 60%, when heat aged at a temperature of about 175° C. for 1000 hours and measured at 23° C. In terms of upper limits, the tensile strength retention may be less than 80%, less than 78%, less than 76%, less than 74%, or less than 72%. In terms of ranges, the tensile strength retention may be in the range of 50% to 80%, e.g., 52% to 78%, 54% to 75%, 56% to 72%, 58% to 70%, or 60% to 68%.

[0137] Tensile strength isn't the only mechanical property that polyamides exhibit after exposure to high temperatures. Heat-induced damage to polyamides manifests itself in many ways. It has been discovered that heat-stabilized polyamide compositions also exhibit improved resilience to other forms of damage. That is, polyamide compositions exhibit other desirable mechanical properties after exposure to high temperatures.

[0138] In some embodiments, the polyamide composition exhibits a tensile elongation of at least 1.0%, e.g., at least 1.2%, at least 1.4%, at least 1.6%, at least 1.8%, or at least 2%, when measured at room temperature. In terms of upper limits, the tensile elongation may be less than 5%, less than 4.8%, less than 4.6%, less than 4.4%, less than 4.2%, or less than 4.0%. In terms of ranges, the tensile elongation may be in the range of 1.0% to 5.0%, e.g., 1.5% to 4.5%, 2% to 4%, or 2.5% to 3.5%.

[0139] Typically, tensile strength and tensile elongation measurements can be performed under ISO 527-1 (2018 or 2019), and heat aging measurements can be performed under ISO 188 (2018 or 2019).

[0140] The tensile strength retention rate can be measured by measuring the tensile strength before and after treatment and calculating the ratio of the measured values.

[0141] Furthermore, the heat stabilizer package has been shown to delay damage to the polyamide even when exposed to higher temperatures. The tensile strength of the heat-stabilized polyamide composition remains surprisingly high when the tensile strength is measured at higher temperatures. Typically, the tensile strength of polyamide compositions is much lower when measured at higher temperatures. While the trends disclosed herein for the heat-stabilized polyamide compositions still hold true, the actual tensile strength remains surprisingly high, even when measured at certain temperatures. Method of forming the final molded product

[0142] As described herein, the composition can be compounded and then extruded or injection molded to form the final product. In some aspects, by using a polyamide resin having a carboxylic acid to amine end group ratio greater than 1.8:1, pressure peaks are avoided during extrusion. Other benefits during extrusion, including controlled molecular weight gain, are described herein. application

[0143] The compositions of the present invention are useful in a variety of applications due to their thermal stability, flowability, processability, and recyclability. The products can be used in electrical and electronic applications including connectors, relays, junction boxes, motors, wall plates, lighting, circuit breakers, switches, and sensors, among other applications.

[0144] Therefore, this product is used for air or liquid filtration in the following areas: transportation; industrial; commercial and residential. Example

[0145] The unique properties of the compositions of the present disclosure provide functionality and benefits not found in conventional products, such as existing non-halogenated flame retardant compositions and injection molded articles produced therefrom.

[0146] Examples 1-7 were prepared by mixing the components in the amounts shown in Table 1 and compounding in a twin-screw extruder. The composition was melted, the additives were added to the melt, and the resulting mixture was extruded and pelletized. In the compositions of Examples 1-7 listed below, the PA-6,6 polyamide had a high carboxyl end group content (a high ratio of carboxyl end groups to amine end groups, e.g., 1.8:1 or greater) as described herein. The non-halogenated flame retardant additive was OP1400 (available from Clariant), the glass fiber used was PPG HP 3610 (available from PPG, NL), and the amine-antioxidant used was 4,4'-bis(α,α-dimethyl-benzyl)diphenylamine ( 445, available from Uniroyal Chemical), the sterically hindered phenol antioxidant used ("hindered phenol") was 1098 (available from BASF), the copper-complexing agent stabilizer used was H3386 (available from Bruggemann Chemical). The compositions of Comparative Examples A and B comprise polyamides having a low carboxyl end group content (a low ratio of carboxyl end groups to amine end groups, e.g., less than 1.8:1) and do not utilize at least one of PA6, a copper complexing agent stabilizer, a hindered phenol antioxidant, or an amine antioxidant. All weight percentages (wt%) are based on the total weight of the polyamide composition.

[0147] Examples 1-7 and Comparative Examples A and B were heat aged and tested for tensile strength, tensile strength retention, and tensile elongation. The samples were heat aged at the temperatures listed in Table 2, and the heat aging time (hours) from the original tensile strength to 50% tensile strength was measured. Tensile strength measurements were performed under ISO 527-1 (2018 or 2019), and heat aging measurements were performed under ISO 188 (2018 or 2019). The results are summarized in Tables 2-4.

[0148] As shown in Table 2, Examples 1-7 generally show significant improvements in heat aging performance within the temperature range of 195-215°C. Moreover, the improvements in heat aging performance are even more pronounced as the heat aging temperature increases. The tensile strength within this temperature range and these extended heat aging times are important and significant because they represent conditions under which polyamide compositions are typically used, such as in automotive under-the-hood applications.

[0149] Most of the average values ​​and ranges for the working examples are higher than those for the comparative examples, especially at higher heat aging times. For example, for tensile strength measured at 195°C, the heat aging times to 50% tensile strength (from the original tensile strength) for the working examples range from 975 to 1375 hours (excluding Example 3), while the range for the comparative examples is significantly smaller, at 825 to 875 hours. The comparison of Examples 2, 4, 5, and 7 at temperatures of 205°C and 215°C is even more pronounced. The heat aging times to 50% tensile strength for working examples 2, 4, 5, and 7 range from 530 to 1375 hours, while the range for the comparative examples is significantly smaller, at 380 to 600 hours. This again demonstrates the improvement in performance at higher temperature differences and higher heat aging times.

[0150] The samples were heat aged for 1000 hours at the temperatures listed in Table 3 and tested for tensile strength retention. The tensile strength retention was measured by measuring the tensile strength before and after treatment and calculating the ratio of the measured values. The tensile strength retention results are summarized in Table 3.

[0151] Examples 1-7 provide improved polyamide compounds that exhibit significantly improved tensile strength retention at higher temperatures, e.g., above 155°C or between 155°C and 175°C, as is the case in many polyamide structures used in automotive applications, such as those involving engine heat. Examples 1, 2, 5, and 7 exhibited tensile strength retention of 77% to 96% after heat aging for 1000 hours at 155°C, while Comparative Examples A and B exhibited tensile strength retention of 77% or less. Specifically, Example 5 exhibited a tensile strength retention of 83% after heat aging for 1000 hours at 155°C, a tensile strength retention of 76% after heat aging for 1000 hours at 165°C, and a tensile strength retention of 72% after heat aging for 1000 hours at 175°C. Example 5 exhibited the highest tensile strength retention at a heat aging temperature of 175°C.

[0152] Specifically, Examples 2 and 5, which include PA6 homopolymers, exhibit high tensile strength retention within a temperature range of 155° C. to 175° C. The polyamide compositions comprising PA6 homopolymers exhibit improved thermal stability (e.g., tensile strength retention). In addition, polyamide compositions comprising amine antioxidants (Examples 3-5) and hindered phenol antioxidants (Examples 6 and 7) also exhibit enhanced thermal stability within the aforementioned temperature range.

[0153] The results of tensile elongation are summarized in Table 4. The measurement of tensile elongation was performed under ISO 527-1 (2018 or 2019), and the measurement of heat aging was performed under ISO 188 (2018 or 2019).

[0154] As shown in Table 4, Examples 1-7 generally demonstrate improvements in tensile elongation at high heat aging temperatures. For example, Examples 2 and 4 each have a tensile elongation of 3.2%, while Comparative Example A has a tensile elongation of 2.5%. Similarly, polyamide compositions including PA6 homopolymer generally exhibit improved elongation at break.

[0155] As shown in the table, Examples 1-7, using the above-described polyamides and additives, generally demonstrate unexpected synergistic results for all measured performance characteristics (e.g., tensile strength, tensile retention, and tensile elongation). Importantly, the disclosed polyamide compositions show significant improvements in the temperature range of 195° C. to 215° C. The tensile strength / retention in this temperature range and these extended heat aging times are important and significant because they represent conditions under which polyamide compositions are typically used, such as in automotive under-the-hood applications.

[0156] Separate comparisons also support the synergistic effect of the disclosed formulations. As an example, a comparison of Example 2 with Comparative Examples A and B demonstrates the surprising synergistic effect of the disclosed stabilizer package and polyamide. Comparative Example A uses a polyamide with a low carboxyl end group content (a low ratio of carboxyl end groups to amine end groups, e.g., less than 1.8:1) and does not include PA6, a copper complexing agent stabilizer, a sterically hindered phenolic antioxidant, or an amine antioxidant, while Example 2 uses a high CEG polyamide and a copper complexing agent heat stabilizer. At 215°C, the heat aging times to 50% tensile strength for Comparative Examples A and B were 500 hours and 300 hours, respectively. Surprisingly, the heat aging time to 50% tensile strength for Example 5 under the same testing conditions was 800 hours. In addition, the tensile elongation of Example 2 was at least 12% greater than that of Comparative Examples A and B. The magnitude of these improvements was unexpected.

[0157] By incorporating the heat stabilizer packages and polyamides disclosed herein, the inventors have discovered that the performance of polyamide compositions can be improved, for example, at higher temperatures, and that damage typically suffered by polyamide compositions at higher temperatures, such as thermo-oxidative damage, is mitigated. Thus, these heat stabilizer packages allow for improved use and functionality of polyamide compositions in higher temperature environments, such as in automotive applications. In contrast, polyamide compositions known in the art become much more brittle after exposure to such high temperatures, whereas the compositions disclosed herein are able to maintain higher strength and elongation. Implementation Plan

[0158] Embodiment 1: A flame retardant polyamide composition comprising: a polyamide having a ratio of carboxylic acid end groups to amine end groups greater than 1.8:1; a non-halogenated flame retardant; and less than 0.29 wt% of a copper-containing heat stabilizer, based on the total weight of the polyamide composition, the copper-containing heat stabilizer comprising a copper halide and an organic halo-phosphorus compound; wherein the polyamide composition comprises less than 900 ppm of bromine.

[0159] Embodiment 2: The embodiment according to embodiment 1, wherein the polyamide composition further comprises a PA-6 homopolymer.

[0160] Embodiment 3: The embodiment according to embodiment 1 or 2, wherein the PA-6 homopolymer is present in an amount of up to 20% by weight, based on the total weight of the polyamide composition.

[0161] Embodiment 4: The embodiment according to embodiments 1-3, wherein the polyamide composition comprises less than 900 ppm of chlorine.

[0162] Embodiment 5: The embodiment according to embodiments 1-4, wherein the polyamide composition comprises less than 1500 ppm of chlorine and bromine combined.

[0163] Embodiment 6: The embodiment according to embodiments 1-5, wherein the polyamide composition further comprises a second copper-containing heat stabilizer containing free copper; and a copper complexing agent comprising a phosphorus-containing additive.

[0164] Embodiment 7: The embodiment according to embodiments 1-6, wherein the phosphorus-containing additive complexes the free copper of the second copper-containing thermal stabilizer.

[0165] Embodiment 8: An embodiment according to embodiments 1-7, wherein the phosphorus-containing additive comprises a phosphine-containing compound, a phosphate-containing compound, a polyphosphate-containing compound, a bromine-containing phosphate, a bromine-containing polyphosphate, a bromine-containing phosphite, a chlorine-containing phosphate, a chlorine-containing polyphosphonate, a chlorine-containing phosphite, triphenylphosphine, triphenyl phosphite, or a combination thereof.

[0166] Embodiment 9: The embodiment according to embodiments 1-8, wherein the second copper-containing heat stabilizer comprises copper halide, copper acetate, copper propionate, copper benzoate, copper adipate, copper terephthalate, copper isophthalate, copper salicylate, copper nicotinate, copper stearate, copper complex salts, or combinations thereof.

[0167] Embodiment 10: The embodiment according to embodiments 1-9, wherein the second copper-containing thermal stabilizer is present in an amount less than 3 weight percent based on the total weight of the polyamide composition.

[0168] Embodiment 11: The embodiment according to embodiments 1-10, wherein the polyamide composition further comprises an amine-containing heat stabilizer, a phenol-containing heat stabilizer, or a combination thereof.

[0169] Embodiment 12: The embodiment according to embodiments 1-11, wherein the polyamide composition comprises less than 5 wt% elemental phosphorus, based on the total weight of the polyamide composition.

[0170] Embodiment 13: The embodiment according to embodiments 1-12, wherein the polyamide composition further comprises one or more additives comprising a flow improver, glass fiber, filler, synergist, lubricant / release agent, antioxidant, or a combination thereof.

[0171] Embodiment 14: The embodiment according to embodiments 1-13, wherein the polyamide composition comprises 40% to 70% by weight of polyamide; 5% to 25% by weight of a non-halogen flame retardant; 0.1% to 3% by weight of a second copper-containing thermal stabilizer; 0.1% to 15% by weight of a copper complexing agent; and 0% to 10% by weight of a lubricant / release agent.

[0172] Embodiment 15: The embodiment according to embodiments 1-14, wherein the non-halogenated flame retardant comprises an organophosphorus flame retardant.

[0173] Embodiment 16: A flame retardant polyamide composition comprising: a polyamide having a ratio of carboxylic acid end groups to amine end groups greater than 1.8:1; a non-halogenated flame retardant; a PA-6 homopolymer; less than 0.29 wt% of a first copper-containing thermal stabilizer, based on the total weight of the polyamide composition, the first copper-containing thermal stabilizer comprising a copper halide and an organic halo-phosphorus compound; and wherein the polyamide composition comprises less than 900 ppm of bromine.

[0174] Embodiment 17: A flame retardant polyamide composition comprising: a polyamide having a ratio of carboxylic acid end groups to amine end groups greater than 1.8:1; a non-halogenated flame retardant; a PA-6 homopolymer; and an amine-containing heat stabilizer.

[0175] Embodiment 18: The embodiment of embodiment 17, wherein the PA-6 homopolymer is present in an amount of up to 20 wt %, based on the total weight of the polyamide composition.

[0176] Embodiment 19: The embodiment of embodiment 17 or 18, wherein the amine-containing heat stabilizer comprises a hindered amine heat stabilizer.

[0177] Embodiment 20: The embodiment of embodiments 17-19, wherein the composition further comprises one or more additives comprising a flow improver, glass fiber, filler, synergist, lubricant / release agent, antioxidant, or a combination thereof.

[0178] Embodiment 21: The embodiment of embodiments 17-20, wherein the non-halogenated flame retardant comprises an organophosphorus flame retardant.

[0179] Embodiment 22: A flame retardant polyamide composition comprising: a polyamide having a ratio of carboxylic acid end groups to amine end groups greater than 1.8:1; a non-halogenated flame retardant; a PA-6 homopolymer; and a phenolic heat stabilizer.

[0180] Embodiment 23: The embodiment of embodiment 22, wherein the PA-6 homopolymer is present in an amount of up to 20 wt %, based on the total weight of the polyamide composition.

[0181] Embodiment 24: The embodiment of embodiment 22 or 23, wherein the phenolic heat stabilizer comprises N,N'-hexane-1,6-diylbis[3-(3,5-di-tert-butyl-4-hydroxyphenylpropionamide)]; pentaerythritol-tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]; N,N'-hexamethylenebis(3,5-di-tert-butyl-4-hydroxyhydrocinnamic acid); triethylene glycol-bis[3-(3-tert-butyl-5-methyl-4-hydroxyphenyl)propionate] ; 3,9-bis{2-[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionyloxy]-1,1-dimethylethyl}-2,4,8,10-tetraoxaspiro[5,5]undecane; 3,5-di-tert-butyl-4-hydroxybenzylphosphonate-diethyl ester; 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene; and 1,3,5-tris(4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl)isocyanurate, or a combination thereof.

[0182] Embodiment 25: The embodiment of embodiments 22-24, wherein the polyamide composition further comprises one or more additives comprising a flow improver, glass fiber, filler, synergist, lubricant / release agent, antioxidant, or a combination thereof.

[0183] Embodiment 26: The embodiment of embodiments 22-25, wherein the non-halogenated flame retardant comprises an organophosphorus flame retardant.

[0184] Embodiment 27: The embodiment of embodiments 1-26, wherein a molded flame retardant polyamide product is prepared from any of the polyamide compositions described herein.

[0185] Although the present disclosure has been described in detail, it will be readily apparent to those skilled in the art that modifications within the spirit and scope of the present disclosure may be made. Such modifications are also considered to be a part of the present disclosure. Based on the above discussion, the relevant knowledge in this area, and the references discussed in connection with "background technology" above (their disclosures are all incorporated herein by reference), further description is considered unnecessary. In addition, it should be understood from the above discussion that aspects of the present disclosure and a part of the various embodiments may be combined or interchanged in whole or in part. In addition, it will be appreciated by those skilled in the art that the above description is merely illustrative and is not intended to limit the present disclosure. Finally, all patents, disclosures, and applications mentioned herein are incorporated herein by reference in their entirety.

Claims

1. A flame retardant polyamide composition comprising: Polyamides having a ratio of carboxylic acid end groups to amine end groups greater than 1.8:1; Non-halogenated flame retardants; less than 0.29 wt. % of a first copper-containing thermal stabilizer, based on the total weight of the polyamide composition, the first copper-containing thermal stabilizer comprising a copper halide and an organohalo-phosphorus compound; wherein the polyamide composition contains less than 900 ppm bromine, and wherein the polyamide composition retains 50% of its initial tensile strength after heat aging for greater than 800 hours when heat aged at a temperature of 195°C and measured at 23°C. 2 . The flame retardant polyamide composition according to claim 1 , further comprising a PA-6 homopolymer.

3. The flame retardant polyamide composition according to claim 2, wherein the PA-6 homopolymer is present in an amount of up to 20 wt%, based on the total weight of the polyamide composition.

4. The flame retardant polyamide composition of claim 1, wherein the polyamide composition comprises less than 900 ppm of chlorine.

5. The flame retardant polyamide composition of any one of claims 1 to 4, wherein the polyamide composition comprises less than 1500 ppm of chlorine and bromine combined.

6. The flame retardant polyamide composition according to any one of claims 1 to 5, further comprising: a second copper-containing heat stabilizer comprising free copper; and Copper complexing agent containing phosphorus-containing additives.

7. The flame retardant polyamide composition according to claim 6, wherein the copper complexing agent complexes with free copper of the second copper-containing heat stabilizer.

8. The flame retardant polyamide composition according to any one of claims 6 or 7, wherein the phosphorus-containing additive comprises a phosphine-containing compound, a phosphate-containing compound, a polyphosphate-containing compound, a bromine-containing phosphate, a bromine-containing polyphosphate, a bromine-containing phosphite, a chlorine-containing phosphate, a chlorine-containing polyphosphonate, a chlorine-containing phosphite, triphenylphosphine, triphenyl phosphite, or a combination thereof.

9. The flame retardant polyamide composition according to any one of claims 6 to 8, wherein the second copper-containing heat stabilizer comprises copper halide, copper acetate, copper propionate, copper benzoate, copper adipate, copper terephthalate, copper isophthalate, copper salicylate, copper nicotinate, copper stearate, a copper complex salt, or a combination thereof.

10. The flame retardant polyamide composition according to any one of claims 6 to 9, wherein the second copper-containing heat stabilizer is present in an amount of less than 3 wt%, based on the total weight of the polyamide composition.

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