WO2025210480A1 - Thermally resistant fiber - Google Patents

Abstract

A thermally resistant melt-spun fiber includes a partially aromatic polyamide comprising PA-MXD6, PA-PXD6, PA-MXD6/PXD6, or a combination thereof. The fiber also includes an at least partially aliphatic polyamide. The partially aromatic polyamide is at least 50 wt% of a total amount of polyamides in the fiber.

Description

THERMALLY RESISTANT FIBER

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims the benefit of priority to U.S. Provisional Patent Application Serial No. 63/572,372 filed April 1, 2024, the disclosure of which is incorporated herein in its entirety by reference.

BACKGROUND

[0002] Protective garments formed from flame resistant (FR) or heat resistant fabrics are commonly used to protect the wearer from hazardous conditions they might encounter. Such garments include those designed to be worn by firefighters, military, law enforcement, first responders, emergency personnel, electrical workers, welders, and workers in industries such as petroleum drilling and refining, power generation, transportation, construction, metal refining, and manufacturing. Flame resistant fabrics minimize the risk of injury from exposure to flame, flash fire or arc flash events by resisting ignition, not sustaining a flame, not dripping or sticking to the skin of the wearer, and having limited thermal shrinkage and thermal conductivity. In addition, the fabric should not rupture during flame exposure to prevent direct flame impingement on the skin of the wearer. Flame resistance is also required for a variety of non-apparel applications such as carpets, upholstery, drapery, furnishings, wall coverings, seat covers in transportation (e.g., automobiles, trains, planes, buses, cruise ships), awnings, ballistic plate carriers/vests, tenting, and firefighting gear.

[0003] Different strategies can be employed to obtain flame resistance in fabrics. These include using one or more inherently flame resistant fibers (i.e., fibers made from materials that are permanently fire resistant and where the fire resistance is not altered by wearing, laundering, or abrasion), applying a chemical flame retardant treatment or coating to the fabric, or combining the two approaches where inherently flame resistant fibers are combined with non-flame resistant fibers and the fabric optionally treated with a flame retardant chemical to enhance the resistance to heat and flame. Using these strategies, numerous flame resistant fabrics have been developed for protective apparel as well as other end-uses and applications. For apparel applications, as well as many others (e.g. airplane seat covers), rigorous testing is required to ensure that fabrics and the garments made therefrom comply with industry standards (e.g. NFPA 2112 and ISO 11612).

[0004] Textiles that comply with flame resistant standards often incorporate expensive fibers (e.g., meta-aramids like DuPont Nomex®) and/or fibers with limited tensile strength (e.g., modacrylics like Kaneka Protex®). In addition, while some fibers may exhibit high tensile strength and resistance to tearing (e.g., para-aramids like DuPont Kevlar®), they also have limited extension and increase the rigidity and stiffness of a fabric. As a result, garments composed of such fabrics can be uncomfortable to wear, with limited flexibility, and a rough or scratchy hand that can irritate the skin, particularly in warm climates where the wearer is more likely to perspire. Many FR fabrics have lower strength and abrasion resistance than comparable non-FR fabrics which results in shorter garment life. Furthermore, inherently flame resistant fibers can be more difficult to dye and exhibit reduced colorfastness compared to conventional apparel fibers composed of polyester (e.g., polyethylene terephthalate) or nylon (e.g., nylon-6, 6 or polyamide-6,6) which also shortens the useful life of a garment.

[0005] A common strategy to improve the comfort or durability of a fabric or improve other fabric characteristics which are not as desirable when inherently FR fibers are used or when flame retardant chemistries are applied to fabrics (e.g., colorfastness) is to include non-FR fibers in the composition. However, only limited amounts of such materials can be used without impacting the performance of fabrics in flame resistance testing and/or burn injury prediction testing. For example, nylon-6, 6 fibers have high strength and abrasion resistance, combined with levels of moisture regain and elongation that make fabrics comfortable against the skin. Furthermore, nylon-6, 6 fibers can easily be dyed with good colorfastness in high temperature industrial laundering, although they will melt and burn when exposed to flame. Therefore, flame resistant apparel fabrics which comply with standards like NFPA 2112, NFPA 70E or ISO 11612 typically incorporate a maximum of a 20% content of nylon-6, 6 since flame resistance must take priority over other desirable characteristics like strength, durability, and comfort.

[0006] A polyamide-based fiber (filament or staple) with superior thermal resistance compared to commodity aliphatic polyamides like nylon-6 (PA6) and nylon-6, 6 (PA66) and which has similar strength, abrasion resistance, dyeability and colorfastness to a commercially available PA66 apparel fiber could be incorporated into a flame resistant fabric at significantly higher loadings. This can result in a more comfortable and durable fabric that will still provide the multi-hazard protection typically required of flame resistant garments. Injuries from a variety of risks can be mitigated with this type of flame-resistant fabric by ensuring it meets the requirements of the relevant standard or standards. These standards include, but are not limited to, those targeted at protecting individuals exposed to: flash fire (e.g., NFPA 2112, ISO 11612), electric arc (e.g., NFPA 70E, EN 61482-2), welding hazards (e.g., ISO 11611), static electricity (e.g., ISO 1149), chemical splash (e.g., ISO 13034), molten metal splash (e.g., ISO 9150), structural firefighting hazards (e.g., NFPA 1971) and wildlands firefighting hazards (e.g., NFPA 1977).

[0007] Enhanced comfort of a fabric can be influenced by several factors including, but not limited to, increased air permeability, lighter weight, increased stretch, improved moisture management (i.e., the ability of a fabric to move moisture away from the skin and evaporate from the fabric), improved thermal management, softer hand, smoother fabric, and increased drape (i.e., reduced stiffness). Likewise, there are numerous aspects of fabric durability that influence the wear life of a garment comprising the fabric, including, but not limited to, the fabric abrasion resistance, tear strength, tensile strength, pilling resistance, colorfastness (e.g., colorfastness to laundering, UV exposure, perspiration, rubbing or bleaching), dimensional stability, as well as stain and soil resistance and release.

[0008] Partially aromatic polyamide-based fiber has superior thermal resistance and can therefore be incorporated into a flame-resistant fabric in greater proportions than a comparable fiber including only an aliphatic nylon such as PA6 or PA66. However, the achievable tensile strength and abrasion resistance of a purely PA-MXD6 is lower than comparable fiber including only an aliphatic nylon. There is a need for fiber that is thermally resistant, has high strength, and has high abrasion resistance.

SUMMARY OF THE INVENTION

[0009] Various aspects of the present invention provide a thermally resistant melt- spun fiber that includes a partially aromatic polyamide including PA-MXD6, PA-PXD6, PA- MXD6/PXD6, or a combination thereof. The fiber also includes an at least partially aliphatic polyamide. The partially aromatic polyamide is at least 50 wt% of a total amount of polyamides in the fiber.

[0010] Various aspects of the present invention provide a thermally resistant melt- spun fiber including a partially aromatic polyamide that is PA-MXD6 and that has a relative viscosity (RV) of 2.4 to 2.9 as measured according to ISO 307 in 96% sulfuric acid. The fiber also includes an at least partially aliphatic polyamide that is PA66 and that has an RV of 65 to 95 as measured according to ASTM D789 as an 8.4 w/w% solution in 90% formic acid. The partially aromatic polyamide is 55 wt% to 90 wt% of a total weight of polyamides in the fiber, the at least partially aliphatic polyamide is 45 wt% to 10 wt% of the total weight of polyamides in the fiber, and the partially aromatic polyamide and the at least partially aliphatic polyamide are together 90 wt% to 100 wt% of the fiber. [0011] Various aspects of the present invention provide a thermally resistant melt- spun fiber that includes a partially aromatic polyamide that is PA-MXD6, that has an RV of 2.4 to 2.9 as measured according to ISO 307 in 96% sulfuric acid, and that is 55 wt% to 90 wt% of the fiber. The fiber also includes an at least partially aliphatic polyamide that is PA66, that is 45 wt% to 10 wt% of the fiber, and that has an RV of 65 to 95 as measured according to ASTM D789 as an 8.4 w/w% solution in 90% formic acid.

[0012] Various aspects of the present invention provide a yarn that includes a thermally resistant fiber or that is comprised solely of the thermally resistant fiber. The fiber includes a partially aromatic polyamide including PA-MXD6, PA-PXD6, PA-MXD6/PXD6, or a combination thereof. The fiber also includes an at least partially aliphatic polyamide. The partially aromatic polyamide is at least 50 wt% of a total amount of polyamides in the fiber.

[0013] Various aspects of the present invention provide a fabric. The fabric includes a yarn that includes a thermally resistant fiber. The fiber includes a partially aromatic polyamide including PA-MXD6, PA-PXD6, PA-MXD6/PXD6, or a combination thereof. The fiber also includes an at least partially aliphatic polyamide. The partially aromatic polyamide is at least 50 wt% of a total amount of polyamides in the fiber.

[0014] Various aspects of the present invention provide a method of forming a thermally resistant fiber. The method includes melt blending a partially aromatic polyamide and an at least partially aliphatic polyamide to form a blend. The method also includes meltspinning the blend to form the thermally resistant fiber. The fiber includes the partially aromatic polyamide and the at least partially aliphatic polyamide, wherein the partially aromatic polyamide is at least 50 wt% of a total amount of polyamides in the fiber.

[0015] Various aspects of the present invention have various advantages over other thermally resistant fibers, and/or yarns and fabrics including the same. For example, in various aspects, the thermally resistant fiber of the present invention has a high tensile strength which imparts strength and durability to a fabric and therefore extends the life cycle of garments made from that fabric. The thermally resistant fiber can have a level of physical properties such as tenacity, toughness, and abrasion resistance that cannot be achieved with a fiber formed from the partially aromatic polyamide alone, such as PA-MXD6 alone.

[0016] The thermally resistant fiber can have increased char formation, a decreased propensity for dripping during combustion, and decreased total heat release during combustion as compared to a fiber formed from only the at least partially aliphatic polyamide (e.g., PA66), wherein total heat release can be measured by pyrolysis combustion flow calorimetry according to ASTM D7309. In various aspects, the thermally resistant fiber of the present invention brings various advantages when blended with other fibers and/or yarns to form flame resistant fabrics. In various aspects, fabrics formed from the thermally resistant fiber of the present invention can have a level and combination of performance in flame resistant testing (e.g., vertical flammability and instrumented manikin testing, according to ASTM D6413 or ISO 15025 and ASTM F1930 or ISO 13506 respectively), thermally resistant properties, and physical properties (e.g., strength, durability, and the like) that could not be achieved by blending 100% partially aromatic polyamide staple fibers (e.g., PA-MXD6) and 100% at least partially aliphatic polyamide staple fibers (e.g., PA66) in a yarn to form a fabric.

[0017] In various aspects, in addition to improvements in physical properties, the addition of the at least partially aliphatic polyamide to the partially aromatic polyamide provides an improvement in spinning properties of the fiber, such as by enabling initiation of fiber drawing at lower temperatures. Optional addition of catalyst and antioxidant to the polymer melt blend can also improve physical properties of the fiber such as tenacity.

[0018] In various aspects, instead of a linear weighted average impact of addition of the at least partially aliphatic polyamide to the partially aromatic polyamide on char yield and total heat release, the fiber of the present invention has a disproportionately negative impact of the at least partially aliphatic polyamide content on char yield and total heat release. As such, various embodiments of the fiber of the present invention have a combination of good thermally resistant performance (e.g., high char formation and low heat release) and good physical properties (e.g., tenacity and abrasion resistance) that could not have been predicted based on a linear weighted average. In various aspects, using an at least partially aliphatic polyamide with a higher viscosity (e.g., PA66 with viscosity greater than or equal to 50 RV or greater than or equal to 65 RV) can be used to further tune the properties of the fiber and can lead to an even greater fiber tenacity.

[0019] In various aspects, the fiber of the present invention, by providing an improvement in strength, abrasion resistance, and processability, while maintaining a significant portion of the improvements in heat release and char formation, can be incorporated into a fabric to provide similar flame-retardancy benefits to use of a pure partially aromatic polyamide fiber (e.g., PA-MXD6) but without negatively affecting the level of protectivity of the fabric (e.g., protection against bum injury from flash fire or electric arc flash exposure). While aliphatic polyamide fibers such as PA66 or PA6 are typically limited below 20% of an overall fabric in order for the fabric to be self- extinguishing and meet flame resistance protection requirements, various aspects of the fiber of the present invention can be incorporated into fabrics at a higher percentage, such as 30% to 50%, while still enabling the fabric to be self-extinguishing and meet flame-retardancy protection requirements, such as according to NFPA 2112, NFPA 70E and ISO 11612, ISO 14116, ISO 61482-1-1, ISO 61482-1-2, and ISO 13506 standards.

[0020] In various aspects, the improved thermal resistance of the fiber of the present invention is inherent to the polymer composition and therefore cannot be washed out or abraded off fiber as in the case of additives with limited water solubility or topical/surface treatments applied to fiber, yarn, or fabric. In various aspects, the fiber of the present invention can be comfortable against the skin, can be dyed/printed with conventional technology for dyeing/printing polyamide apparel fibers, and can be suitable for laundering in hot water or with industrial laundry since flame-retardancy performance is inherent to the fiber. In various aspects, the fiber of the present invention can have moisture regain such that it is comfortable to wear (similar to a conventional aliphatic nylon like N6 or N66) but is still faster drying than a cellulosic fiber.

DETAILED DESCRIPTION OF THE INVENTION

[0021] Reference will now be made in detail to certain aspects of the disclosed subject matter. While the disclosed subject matter will be described in conjunction with the enumerated claims, it will be understood that the exemplified subject matter is not intended to limit the claims to the disclosed subject matter.

[0022] Throughout this document, values expressed in a range format should be interpreted in a flexible manner to include not only the numerical values explicitly recited as the limits of the range, but also to include all the individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range is explicitly recited. For example, a range of “about 0.1% to about 5%” or “about 0.1% to 5%” should be interpreted to include not just about 0.1% to about 5%, but also the individual values (e.g., 1%, 2%, 3%, and 4%) and the sub-ranges (e.g., 0.1% to 0.5%, 1.1% to 2.2%, 3.3% to 4.4%) within the indicated range. The statement “about X to Y” has the same meaning as “about X to about Y,” unless indicated otherwise. Likewise, the statement “about X, Y, or about Z” has the same meaning as “about X, about Y, or about Z,” unless indicated otherwise.

[0023] In this document, the terms “a,” “an,” or “the” are used to include one or more than one unless the context clearly dictates otherwise. The term “or” is used to refer to a nonexclusive “or” unless otherwise indicated. The statement “at least one of A and B” or “at least one of A or B” has the same meaning as “A, B, or A and B.” In addition, it is to be understood that the phraseology or terminology employed herein, and not otherwise defined, is for the purpose of description only and not of limitation. Any use of section headings is intended to aid reading of the document and is not to be interpreted as limiting; information that is relevant to a section heading may occur within or outside of that particular section. [0024] In the methods described herein, the acts can be carried out in a specific order as recited herein. Alternatively, in any aspect(s) disclosed herein, specific acts may be carried out in any order without departing from the principles of the invention, except when a temporal or operational sequence is explicitly recited. Furthermore, specified acts can be carried out concurrently unless explicit claim language recites that they be carried out separately or the plain meaning of the claims would require it. For example, a claimed act of doing X and a claimed act of doing Y can be conducted simultaneously within a single operation, and the resulting process will fall within the literal scope of the claimed process. [0025] The term “about” as used herein can allow for a degree of variability in a value or range, for example, within 10%, within 5%, or within 1% of a stated value or of a stated limit of a range, and includes the exact stated value or range.

[0026] The term “substantially” as used herein refers to a majority of, or mostly, as in at least about 50%, 60%, 70%, 80%, 90%, 95%, 96%, 97%, 98%, 99%, 99.5%, 99.9%, 99.99%, or at least about 99.999% or more, or 100%. The term “substantially free of’ as used herein can mean having none or having a trivial amount of, such that the amount of material present does not affect the material properties of the composition including the material, such that about 0 wt% to about 5 wt% of the composition is the material, or about 0 wt% to about 1 wt%, or about 5 wt% or less, or less than, equal to, or greater than about 4.5 wt%, 4, 3.5, 3, 2.5, 2, 1.5, 1, 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, 0.1, 0.01, or about 0.001 wt% or less, or about 0 wt%.

[0027] As used herein, the term “polymer” refers to a molecule having at least one repeating unit and can include copolymers.

[0028] As used herein, the terms “polyamide” and “nylon” are inter-changeable and define a type of a thermoplastic polymer. Examples of polyamides or nylons include PA66, PA6, PA10, PAI 1, PA12, PA46, PA56, PA610, PA1010, PA1012, PA6/66, PA66/D6, PA66/6T, PA66/6I, PA66/DI, PA66/6T/6I, PA-MXD6, PA-PXD6, PA-MXD6/PXD6, and others.

[0029] As used herein, the term “thermally resistant” refers to the property of resistance to burning such as measured via char formation (wherein more char formation means more thermally resistant), propensity for dripping during combustion (wherein less dripping means more thermally resistant), and heat release during combustion (wherein less heat release means more thermally resistant).

[0030] As used herein, the term “flame resistant” or “fire resistant” refers to the property of self-extingui shing a flame in pure form. After the flame or heat source is removed, the material does not continue to burn until completely consumed.

[0031] As used herein, the term “FR” indicates flame resistant or fire resistant.

[0032] As used herein, the terms “flame-retardant” or “fire-retardant” refers to the property of an additive or treatment to increase thermal resistance or flame resistance of a material.

Thermally resistant fiber,

[0033] Various aspects of the present invention provide a thermally resistant fiber. The fiber includes a thermally resistant melt-spun fiber that includes a partially aromatic polyamide including PA-MXD6, PA-PXD6, PA-MXD6/PXD6, or a combination thereof. The fiber also includes an at least partially aliphatic polyamide. The partially aromatic polyamide is at least 50 wt% of a total amount of polyamides in the fiber. The fiber is spun from a melt blended composition that includes the partially aromatic polyamide and the at least partially aliphatic polyamide. The melt blended composition can have the same composition as the thermally resistant melt-spun fiber. The fiber can be thermally resistant or flame resistant.

[0034] The partially aromatic polyamide can include polymers or monomers selected from the group consisting of aromatic diamine monomers, aliphatic diamine monomers, aromatic diacid monomers, aliphatic diacid monomers, and combinations thereof. The partially aromatic polyamide can also include copolymers or mixtures of multiple partially aromatic amides. The partially aromatic polyamide can include PA-MXD6 (i.e., produced by polycondensation of m-xylenediamine and adipic acid), PA-PXD6 (i.e., produced by polycondensation of p-xylenediamine and adipic acid), PA-MXD6/PXD6 (i.e., produced by polycondensation of m-xylenediamine, p-xylenediamine, and adipic acid), or a combination thereof. The partially aromatic polyamide can include PA-MXD6. The partially aromatic polyamide can have any suitable relative viscosity (RV). For example, the partially aromatic polyamide can have an RV of 1.5 to 4 as measured according to ISO 307 in 96% sulfuric acid, or 2 to 3.5, or 2.4 to 2.9, 2.45 to 2.85, or less than or equal to 4 and greater than or equal to 1.5 and less than, equal to, or greater than 2, 2.1, 2.2, 2.3, 2.4, 2.5, 2.55, 2.6, 2.65, 2.7, 2.75, 2.8, 2.9, 3, 3.1, 3.2, 3.3, 3.4, or 3.5. The partially aromatic polyamide can be at least 50 wt% of the fiber, such as 51 wt% to 99.5 wt% of the fiber, 55 wt% to 90 wt%, 60 wt% to 80 wt%, or less than or equal to 99.5 wt% and greater than or equal to 50 wt% and less than, equal to, or greater than 52, 54, 56, 58, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 82, 84, 86, 88, 90, 92, 94, 96, or 98 wt%.

[0035] The fiber can have a weight ratio of the partially aromatic polyamide to the at least partially aliphatic polyamide of at least 50:50, such as 50:50 to 95.5:0.5, or 51 :49 to 95.5:0.5, or 55:45 to 90:10, or 60:40 to 80:20, or less than or equal to 95.5:0.5 and greater than or equal to 50:50 and less than, equal to, or greater than 52:48, 54:46, 56:44, 58:42, 60:40, 61 :39, 62:38, 63:37, 64:36, 65:35, 66:34, 67:33, 68:32, 69:31, 70:30, 71 :29, 72:28, 73:27, 74:26, 75:25, 76:24, 77:23, 78:22, 79:21, 80:20, 82: 18, 84: 16, 86: 14, 88: 12, 90: 10, 92:8, 94:6, 96:4, or 98:2.

[0036] The partially aromatic polyamide and the at least partially aliphatic polyamide together, and/or the total amount of polyamides in the fiber, can by 80 wt% to 100 wt% of the fiber, or 90 wt% to 100 wt%, or 95 wt% to 100 wt%, or less than or equal to 100 wt% and greater than or equal to 80 wt% and less than, equal to, or greater than 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 99.5, 99.9, or 99.99 wt% of the fiber.

[0037] The at least partially aliphatic polyamide can include an aliphatic polyamide, an aliphatic/aromatic polyamide copolymer, or a combination thereof. The at least partially aliphatic polyamide can include PA66, PA6, PA10, PAI 1, PA12, PA46, PA56, PA610, PA1010, PA1012, PA6/66, PA66/D6, PA66/6T, PA66/6I, PA66/DI, PA66/6T/6I, or a combination thereof, wherein “T” is formed from terephthalic acid (TP A), “D” is formed from 2-methyl-l,5-pentanediamine (MPMD), and “I” is formed from isophthalic acid (IP A). The at least partially aliphatic polyamide can include a polyamide formed from a combination of monomers such as two or more of hexamethylene diamine (HMD), adipic acid (AA), TP A, IP A, MPMD, caprolactam, and the like. The at least partially aliphatic polyamide can include PA66 (i.e., nylon 6,6, or N66, formed from polycondensation of adipic acid and hexamethylenediamine). The at least partially aliphatic polyamide can have an RV of 40 to 150 as measured according to ASTM D789 as an 8.4 w/w% solution in 90% formic acid, or 50 to 120, or 65 to 95, or greater than or equal to 75, or less than or equal to 150 and greater than or equal to 40 and less than, equal to, or greater than 42, 44, 46, 48, 50, 52, 54, 56, 58, 60, 62, 64, 66, 68, 70, 72, 74, 76, 78, 80, 82, 84, 86, 88, 90, 95, 100, 105, 110, 115, 120, 125, 130, 135, 140, or 145. The at least partially aliphatic polyamide can be less than 50 wt% of the fiber, such as 0.5 wt% to 49.9 wt% of the fiber, or 10 wt% to 45 wt%, or 20 wt% to 40 wt%, or less than 50 wt% and greater than or equal to 0.5 wt% and less than, equal to, or greater than 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 42, 44, 46, or 48 wt% of the fiber.

[0038] In various aspects, the fiber further includes a flame-retardant additive. The flame-retardant additive can be any suitable flame-retardant additive. For example, the flame-retardant additive can include a halogen-containing flame-retardant additive, phosphorus-containing flame-retardant additive, inorganic flame-retardant additive, nitrogencontaining flame-retardant additive, non-halogenated flame retardant, polymeric halogenated flame retardant, or a combination thereof. The flame-retardant additive can include a nonhalogenated flame retardant, a polymeric halogenated flame retardant, or a combination thereof, and can optionally include one or more synergists. The flame-retardant additive can be 0.01 wt% to 25 wt% of the fiber, 0.01 wt% to 20 wt%, 0.01 wt% to 15 wt%, or 0.1 wt% to 5 wt%, or less than or equal to 25 wt% and greater than or equal to 0.01 wt% and less than, equal to, or greater than 0.05, 0.1, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, or 44 wt%. In other aspects, the fiber is substantially free of flameretardant additive; for example, flame-retardant additive can be less than 0.01 wt% of the fiber, or 0 wt% to 0.01 wt% of the fiber, or 0 wt% to 0.001 wt% of the fiber.

[0039] The fiber can optionally include one or more additives, such as an antioxidant, a delustrant, a pigment, a draw assist, other fiber additives, or a combination thereof.

[0040] The fiber can have improved physical properties compared to the same fiber having the combination of the partially aromatic polyamide and the at least partially aliphatic polyamide replaced with the at least partially aliphatic polyamide. For example, the fiber can have increased char formation as compared the same fiber having the combination of the partially aromatic polyamide and the at least partially aliphatic polyamide replaced with the at least partially aliphatic polyamide, as measured according to ASTM D7309-22. The fiber can have decreased total heat release as compared the same fiber having the combination of the partially aromatic polyamide and the at least partially aliphatic polyamide replaced with the at least partially aliphatic polyamide, as measured according to ASTM D7309-22.

[0041] The fiber can have improved physical properties compared to the same fiber having the combination of the partially aromatic polyamide and the at least partially aliphatic polyamide replaced with the partially aromatic polyamide. For example, the fiber can have increased tenacity as compared to the same fiber having the combination of the partially aromatic polyamide and the at least partially aliphatic polyamide replaced with the partially aromatic polyamide, as measured according to ASTM DI 907. The fiber can have increased abrasion resistance as compared to the same fiber having the combination of the partially aromatic polyamide and the at least partially aliphatic polyamide replaced with the partially aromatic polyamide, as measured according to ASTM D3885.

[0042] The fiber can have a shrinkage of 2% to 20% as measured according to ASTM D4974 (for filament) or ASTM D2102 (for staple), such as 2% to 16%, or 3% to 10%, or 4% to 7%, or less than or equal to 20% and greater than or equal to 2% and less than, equal to, or greater than 3%, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10, 10.5, 11, 11.5, 12, 12.5, 13, 13.5, 14, 14.5, 15, 15.5, 16, 16.5, 17, 17.5, 18, 18.5, 19, or 19.5%.

[0043] The fiber can have an elongation of 10% to 50% as measured according to ASTM D2256, such as 15% to 35%, or less than or equal to 50% and greater than or equal to 10% and less than, equal to, or greater than 11%, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 28, 30, 32, 34, 36, 38, 40, 42, 44, 46, or 48%.

[0044] The fiber can have a tenacity of 4 g/den to 12 g/den as measured according to ASTM D1907, or 5 g/den to 10 g/den, or less than or equal to 12 g/den and greater than or equal to 4 g/den and less than, equal to, or greater than 4.5 g/den, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10, 10.5, 11, or 11.5 g/den.

[0045] The fiber can be a staple fiber, a continuous filament fiber, or a combination thereof. The fiber can be flat or textured. Texturing can be performed via air jet texturing, draw texturing, pin texturing, or a combination thereof. The fiber cross-section can have any suitable shape, such as round, circular, triangular, star, square, oval, bi-lobal, tri-lobal, or flat.

Yarn,

[0046] Various aspects of the present invention provide a yarn that includes the thermally resistant melt-spun fiber described herein. The thermally resistant melt-spun fiber includes a partially aromatic polyamide including PA-MXD6, PA-PXD6, PA-MXD6/PXD6, or a combination thereof. The fiber also includes an at least partially aliphatic polyamide. The partially aromatic polyamide is at least 50 wt% of a total amount of polyamides in the fiber. The yarn can be thermally resistant or flame resistant.

[0047] In various aspects, the yarn is substantially free of fibers other than the thermally resistant melt-spun fiber described herein. In other aspects, the yam can include one or more additional fibers. The additional fiber can be a FR fiber (i.e., a fiber that is flame resistant or a fiber that is inherently flame resistant), a thermally resistant fiber, a non-FR fiber, or a fiber that is not thermally resistant. The one or more additional fibers can be one or more non-FR fibers or fibers that are not thermally resistant, such as a fiber including polyurethane, polyethylene, polypropylene, wool, cellulosic fibers (e.g., cotton, hemp, linen, jute, ramie, sisal), regenerated cellulosic fibers (e.g., viscose, modal, lyocell), cellulose acetate (e.g., Eastman Naia™), cupro or cupra fibers, ultra high molecular weight polyethylene (UHMWPE), anti-static fiber, bicomponent polyester, polyester (e.g., PET, PTT, PBT), other nylon fibers (e.g., PA66 or PA6), or a combination thereof. In some aspects, the additional fiber is a FR fiber (i.e., a fiber that is flame resistant) or a thermally resistant fiber, such as a fiber including FR polyester (e.g., Indorama Trevira® CS), FR nylon, FR viscose, FR rayon (e.g., Lenzing™ FR), FR lyocell, FR cellulose acetate, metaaramid (e.g., DuPont Nomex®, Teijin Teijinconex®), para-aramid (e.g., DuPont Kevlar®, Teijin Twaron®), modacrylic (e.g., Kaneka Protex®, Aksa Armora), phenol-formaldehyde resin (e.g., Novoloid), melamine, poly(p-phenylene benzobisoxazole) (PBO), polybenzimidazole (PBI), polysulphonamide (PSA), oxidized acrylic, partially oxidized acrylic, cross-linked acrylic, polyoxadiazole, aromatic polyester, aromatic copolyimide (e.g. Teijin Technora®), polybenzimidazole (PBI), polyoxadiazole (POD) (e.g., Svetlogorsk Khimvolokno Arselon and Arselon-S), polybenzoxazole (PBO) (e.g., Toyobo Zylon®), polyamide-imide (e.g., Kermel®), polyimide (e.g., Evonik P84®), novoloid phenolic, crosslinked acrylonitrile (e.g., PyroTex®, Grupo ADI Tecstar®), oxidized or partially oxidized polyacrylonitrile (PAN) (e.g., TECGEN®), polyarylate (e.g., Kuraray Vectran™), polysulfonamide (PPS), poly{2,6-diimidazo[4,5-b:40; 50-e]-pyridinylene-l,4-(2,5- dihydroxy)phenylene} (PIPD), poly etherimide (PEI), polyethylene naphthalate (PEN), vinalon, vinylon, polytetrafluoroethylene (PTFE), expanded PTFE, or a combination thereof. [0048] In woven or knit fabrics, yarns can be continuous filament or multi-filament, stretch-broken, or spun from staple fibers or a combination of filament and staple fibers. Staple fibers may be an intimate blend in which the components are uniformly blended throughout the yarn. Yams can include a single yarn or two or more individual yams of any type (e.g., staple, filament, and the like) that are combined by twisting, plying, cabling, wrapping, intermingling, interlacing, covering, or core-spinning. Furthermore, other types of yarns including ceramic, metal, glass, carbon and/or other types of inorganic yarns may be incorporated to form composite yarns. Fabric.

[0049] Various aspects of the present invention provide a fabric that includes the yarn described herein. The yam includes a thermally resistant fiber including a partially aromatic polyamide including PA-MXD6, PA-PXD6, PA-MXD6/PXD6, or a combination thereof. The fiber also includes an at least partially aliphatic polyamide. The partially aromatic polyamide is at least 50 wt% of a total amount of polyamides in the fiber. The fabric can be thermally resistant or flame resistant.

[0050] The fabric can be any suitable type of fabric. The fabric can be woven, knit, non-woven (e.g., spun bond or melt bond), or a combination thereof. The fabric can optionally be coated or laminated for specific end-use applications. Non-woven fabrics include those made from carded webs, melt blown processes, spun bond processes and those combined by hydroentangling.

[0051] The yarn can be a primary yarn. The fabric can further include at least one additional yarn which is compositionally different from the primary yarn. The additional yarn differs from the primary yarn in at least one of a variety of aspects such as different fiber compositions, different amounts of the same fibers, different fiber cross-sections, different additives, different combinations of filament yams, different combinations of filament and staple yarns, different additives (e.g., flame-retardant additives, pigments, anti-oxidants, processing aids, catalysts, or additives to control the infrared signature of the fiber and fabric), different yam sizes, different yarn spinning methods (e.g., ring spinning or vortex spinning) and different colors. The additional yarn or yarns can also be formed of a single fiber type. The additional yarn can include exclusively a partially aromatic polyamide-based fiber like an PA-MXD6-based fiber either in continuous filament or staple spun yarn form, or including a mixture of staple and filament fiber (e.g., twisted or core-spun). The additional yarn can be a FR yarn (i.e., a yarn that is flame resistant), a thermally resistant yam, a non-FR yarn, or a yarn that is not thermally resistant. The thermally resistant fiber can form any suitable proportion of the total fibers in the fabric. For example, the fiber can be 1 wt% to 100 wt% of the total amount of fibers in the fabric, or 1 wt% to 60 wt%, or 30 wt% to 50 wt%, or less than or equal to 100 wt% and greater than or equal to 1 wt% and less than, equal to, or greater than 2 wt%, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30, 32, 34, 36, 38, 40, 42, 44, 46, 48, 50, 52, 54, 56, 58, 60, 62, 64, 66, 68, 70, 72, 74, 76, 78, 80, 82, 84, 86, 88, 90, 92, 94, 96, or 98 wt%.

[0052] Elastomeric fibers can optionally be incorporated into yarns or can be 100% of an additional yarn. These impart stretch to a fabric and improve wearer comfort, and include, but are not limited to, polyether-polyurea type fibers commonly known as spandex or elastane (e.g., Lycra® spandex), bicomponent polyester-based fibers known as elastomultiester fibers (e.g., Lycra® T400®), and partially cross-linked polyethylene-based fibers known as elastolefins (e.g., XLANCE®). Stretch yarns may be formed by corespinning where the elastic core is surrounded by a flame resistant or thermally resistant sheath.

[0053] Multiple different yarns can be used in a woven, knit, or non-woven fabric and the fabric constructed so that the two sides of the fabric (i.e., the “back” side facing the wearer and the “face” side facing away from the wearer) have different properties. Different yarns can be used to construct one direction of a fabric (e.g., multiple different warp yams or multiple different weft yams in a woven fabric). The different yams can be incorporated into the fabric in a regular pattern (e.g., alternating weft picks or ripstop yarns at set intervals) or a random arrangement.

[0054] Fabrics can be constructed with the primary yarn and one or more additional yarns in woven fabrics using any available weaving technique in any weave pattern, including, but not limited to, twill weaves, plain or oxford weaves, rip-stop weaves, satin or sateen weaves, dobby weaves, double-beam or double-cloth weaves or jacquard weaves. [0055] In some aspects, the fabric is substantially free of flame-retardant additives added to the fabric. In other aspects, the fabric can include a topical flame-retardant treatment, such as including tetrakis (hydroxymethyl) phosphonium salts (THPx) including the branded Proban® treatment or alternative treatments including the branded Pyrovatex® treatments. A fabric including a yarn including the thermally resistant fiber of the present invention either in continuous filament or staple spun yam form, or including a mixture of staple and filament fiber (e.g., twisted or core-spun) can be treated with a flame retardant chemistry to yield a flame resistant fabric meeting the requirements of flame-retardant protective apparel, including outerwear and garment reinforcements, and/or other flameretardant textile applications.

[0056] The fabric can be self-extingui shing and provide protection according to NFPA 2112, NFPA 70E and ISO 11612, ISO 14116, ISO 61482-1-1, ISO 61482-1-2, and ISO 13506 standards.

[0057] The fabric can be incorporated into any form of apparel garment or nonapparel textile application. Apparel garments may be single or multi-layer and may be worn against the skin or layered over other garments. The fabric including the inventive fiber can be used in flame resistant protective apparel applications such as undergarments, baselayers, uniforms, outerwear, footwear, accessories (e.g., headwear, turnout gear, gloves, and the like) or any part thereof (e.g. inner linings, reinforcements, and the like). The fabric can be pliable or rigid. The fabric can incorporate elastic fibers or be substantially free of elastic fibers.

Method of forming a thermally resistant fiber.

[0058] Various aspects of the present invention provide a method of forming the thermally resistant melt-spun fiber described herein. The method can include melt blending the partially aromatic polyamide and the at least partially aliphatic polyamide, to form a blend. The method can also include melt-spinning the blend to form the fiber. The fiber includes a partially aromatic polyamide including PA-MXD6, PA-PXD6, PA-MXD6/PXD6, or a combination thereof. The fiber also includes an at least partially aliphatic polyamide. The partially aromatic polyamide is at least 50 wt% of a total amount of polyamides in the fiber.

[0059] The melt-spinning can include using a total draw ratio of 3 to 6, or 3.5 to 4.7, or 3.75 to 4.7, or 4 to 4.7, or greater than 3.75, or less than or equal to 6 and greater than or equal to 3 and less than, equal to, or greater than 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.75, 3.8, 3.9, 4, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, 5, 5.1, 5.2, 5.3, 5.4, 5.5, 5.6, 5.7, 5.8, or 5.9.

[0060] In various aspects, the blend is free of catalysts, such as catalysts that increase molecular weight of the polyamides during melt blending. In other aspects, the blend includes a catalyst. The catalyst can be added to the blend, the catalyst can be used during the polymerization of the at least partially aliphatic polyamide and/or the partially aromatic polyamide such that these polymers include the catalyst, or both. The catalyst can be a catalyst that increases molecular weight of the partially aromatic polyamide and/or the at least partially aliphatic polyamide during the melt blending. The catalyst can include a phosphorus-based catalyst, such as phosphinic acid, phosphoric acid, phenyl phosphinic acid, phenyl phosphonic acid, a salt formed from these acids (e.g. sodium hypophosphite, sodium phosphate, and the like), or a combination thereof. The use of a catalyst can increase the tenacity of the fiber. Examples

[0061] Various aspects of the present invention can be better understood by reference to the following Examples which are offered by way of illustration. The present invention is not limited to the Examples given herein.

[0062] Materials: PA-MXD6 was MX Nylon, Grade S6011 from MGC Advanced Polymers (Colonial Heights, VA) or Mitsubishi Gas Chemical Company (Niigata, Japan), having an RV of 2.45-2.85 as measured according to ISO 307 in 96% sulfuric acid. PA66 was from INVISTA (Canada) Company (Kingston, ON). PA6 was BASF Ultramid® B24 N 02.

[0063] Unless otherwise indicated, relative viscosity (RV) was measured according to ASTM D789 as an 8.4 w/w% solution in 90% formic acid. Breaking strength and elongation at break measurements are conducted on continuous multi-filament fibers according to ASTM D2256 (Configuration A: Straight Specimen). Fiber tenacity is determined by dividing the breaking strength by the fiber linear density (measured according to ASTM DI 907). Flame resistance performance testing was performed according to ASTM D6413. Knit fabric specimens were prepared from 50 wt% continuous multi-filament PA-MXD6- based nylon fibers twisted with 50 wt% spun yam including only Lenzing™ FR (made by Lenzing AG, Lenzing, Austria) viscose fiber purchased commercially. Mass loss was calculated as the difference in mass of the 3” x 12” specimen before and after exposure to flame. Shrinkage was measured on continuous multi -filament fibers according to ASTM D4974. Abrasion resistance was measured using the apparatus described in ASTM D3885 on the same number of yarns arranged parallel to each other at uniform intervals and secured on adhesive strip prior to mounting in the test apparatus as is typically done with a strip of fabric. Pyrolysis Combustion Flow Calorimetry (PCFC) was performed according to ASTM D7309-22 on undrawn material extruded from a fiber melt-spinning system prior to the application of lubricant.

Blend Ratio.

[0064] Analysis of polymer by pyrolysis combustion flow calorimetry (PCFC) shows (Table 1) that increasing the content of PA66 blended with PA-MXD6 results in a reduction of the amount of char formed, an increase in the fire growth capacity (FGC) and an increase in the total heat released during combustion (Total HR). Therefore, the polymer blend selection must balance the improved thermal resistance provided by PA-MXD6 with the improved fiber mechanical properties provided by PA66. The PA66 used in Tables 1-4 had an RV of 75.

[0065] Table 1. Characterization of fibers by PCFC (ASTM D7309-22). [0066] Flammability performance of fibers with different melt blend ratios of PA-

MXD6 and PA66 combined in a 50:50 ratio with Lenzing™ FR viscose (Table 2) shows that levels below approximately 40% PA66 in a melt-blend with PA-MXD6 do not significantly impact FR performance.

[0067] Table 2. Knit sock flammability (ASTM D6413).

[0068] Physical properties of fibers spun with different melt blend ratios of PA-

MXD6 and PA66 (Table 3) show an increase in tenacity with the inclusion of PA66 in a melt blend with PA-MXD6.

[0069] Table 3. Physical properties of melt-spun fibers at total draw ratio of 3.9. [0070] Fibers spun with different melt blend ratios of PA-MXD6 and PA66 (Table 4) show that with increasing PA66 content, lower feed roll temperatures are required to initiate draw.

[0071] Table 4. Minimum feed roll temperature required to initiate draw.

N66 RV

[0072] Blending PA-MXD6 with PA66 in a 70:30 ratio provides a balance of thermal resistance enabling inclusion of up to 50% of this PA-MXD6-based fiber with other FR fibers resulting in a self-extinguishing fabric which can be used in protective apparel applications. Increasing the molecular weight of the PA66 used in the melt blend above the level typically used for spinning apparel fibers results in a fiber which has an increased tenacity and abrasion resistance and can still be processed with conventional melt-spinning techniques. [0073] Melt blending PA-MXD6 with PA66 of >=65 RV which may or may not include the presence of a catalyst to further increase molecular weight of the mixture during processing (Table 5 and Table 6) is shown to enable spinning at higher draw ratios resulting in fiber of improved tensile strength and durability. When used, the catalyst was used during formation of the PA-MXD6 and/or the PA66, such that the catalyst was present in the melt blend of the PA-MXD6 and the PA66. The catalyst can be a phosphorus-based catalyst.

[0074] Table 5A. Physical properties of 70/30 PA-MXD6/PA66 fiber with differing RV of PA66.

[0075] Table 5B. Physical properties of 70/30 PA-MXD6/PA66 fiber with differing RV of PA66. [0076] Table 5c. Physical properties of 70/30 PA-MXD6/PA66 fiber with differing RV of PA66.

[0077] Table 6. Flex abrasion testing of filament yams of differing polymer compositions.

N66 vs. N6

[0078] A blend of PA-MXD6 with PA6 with the same melt viscosity is shown (Table

7) to result in fibers of very high shrinkage and with lower tenacity than with PA66. [0079] Table 7. Physical properties of PA-MXD6 based fibers with N66 and N6 at a

30% level. [0080] The terms and expressions that have been employed are used as terms of description and not of limitation, and there is no intention in the use of such terms and expressions of excluding any equivalents of the features shown and described or portions thereof, but it is recognized that various modifications are possible within the scope of the aspects of the present invention. Thus, it should be understood that although the present invention has been specifically disclosed by specific aspects and optional features, modification and variation of the concepts herein disclosed may be resorted to by those of ordinary skill in the art, and that such modifications and variations are considered to be within the scope of aspects of the present invention.

Exemplary Aspects.

[0081] The following exemplary aspects are provided, the numbering of which is not to be construed as designating levels of importance:

[0082] Aspect 1 provides a thermally resistant melt-spun fiber comprising: a partially aromatic polyamide comprising PA-MXD6, PA-PXD6, PA-MXD6/PXD6, or a combination thereof; and an at least partially aliphatic polyamide; wherein the partially aromatic polyamide is at least 50 wt% of a total amount of polyamides in the fiber.

[0083] Aspect 2 provides the fiber of Aspect 1, wherein the fiber is a thermally resistant fiber spun from a melt blended composition comprising the partially aromatic polyamide and the at least partially aliphatic polyamide.

[0084] Aspect 3 provides the fiber of any one of Aspects 1-2, wherein the partially aromatic polyamide comprises PA-MXD6.

[0085] Aspect 4 provides the fiber of any one of Aspects 1-3, wherein the partially aromatic polyamide has an RV of 1.5 to 4 as measured according to ISO 307 in 96% sulfuric acid.

[0086] Aspect 5 provides the fiber of any one of Aspects 1-4, wherein the partially aromatic polyamide has an RV of 2.4 to 2.9 as measured according to ISO 307 in 96% sulfuric acid.

[0087] Aspect 6 provides the fiber of any one of Aspects 1-5, wherein the partially aromatic polyamide is 51 wt% to 99.5 wt% of the fiber.

[0088] Aspect 7 provides the fiber of any one of Aspects 1-6, wherein the partially aromatic polyamide is 55 wt% to 90 wt% of the fiber. [0089] Aspect 8 provides the fiber of any one of Aspects 1-7, wherein the partially aromatic polyamide is 60 wt% to 80 wt% of the fiber.

[0090] Aspect 9 provides the fiber of any one of Aspects 1-8, wherein the fiber has a weight ratio of the partially aromatic polyamide to the at least partially aliphatic polyamide of greater than 50:50 to 95.5:0.5.

[0091] Aspect 10 provides the fiber of any one of Aspects 1-9, wherein the fiber has a weight ratio of the partially aromatic polyamide to the at least partially aliphatic polyamide of 51 :49 to 95.5:0.5.

[0092] Aspect 11 provides the fiber of any one of Aspects 1-10, wherein the fiber has a weight ratio of the partially aromatic polyamide to the at least partially aliphatic polyamide of 55:45 to 90: 10.

[0093] Aspect 12 provides the fiber of any one of Aspects 1-11, wherein the fiber has a weight ratio of the partially aromatic polyamide to the at least partially aliphatic polyamide of 60:40 to 80:20.

[0094] Aspect 13 provides the fiber of any one of Aspects 1-12, wherein the partially aromatic polyamide and the at least partially aliphatic polyamide together are 80 wt% to 100 wt% of the fiber.

[0095] Aspect 14 provides the fiber of any one of Aspects 1-13, wherein the partially aromatic polyamide and the at least partially aliphatic polyamide together are together 100 wt% of the fiber.

[0096] Aspect 15 provides the fiber of any one of Aspects 1-14, wherein the at least partially aliphatic polyamide comprises an aliphatic polyamide, an aliphatic/aromatic polyamide copolymer, or a combination thereof.

[0097] Aspect 16 provides the fiber of any one of Aspects 1-15, wherein the at least partially aliphatic polyamide comprises PA66, PA6, PA10, PAI 1, PA12, PA46, PA56, PA610, PA1010, PA1012, PA6/66, PA66/D6, PA66/6T, PA66/6I, PA66/DI, PA66/6T/6I, or a combination thereof.

[0098] Aspect 17 provides the fiber of any one of Aspects 1-16, wherein the at least partially aliphatic polyamide comprises PA66.

[0099] Aspect 18 provides the fiber of any one of Aspects 1-17, wherein the at least partially aliphatic polyamide has an RV of 40 to 150 as measured according to ASTM D789 as an 8.4 w/w% solution in 90% formic acid. [0100] Aspect 19 provides the fiber of any one of Aspects 1-18, wherein the at least partially aliphatic polyamide has an RV of 65 to 95 as measured according to ASTM D789 as an 8.4 w/w% solution in 90% formic acid

[0101] Aspect 20 provides the fiber of any one of Aspects 1-19, wherein the at least partially aliphatic polyamide is less than 50 wt% of the fiber.

[0102] Aspect 21 provides the fiber of any one of Aspects 1-20, wherein the at least partially aliphatic polyamide is 0.5 wt% to 49.9 wt% of the fiber.

[0103] Aspect 22 provides the fiber of any one of Aspects 1-21, wherein the at least partially aliphatic polyamide is 10 wt% to 45 wt% of the fiber.

[0104] Aspect 23 provides the fiber of any one of Aspects 1-22, wherein the at least partially aliphatic polyamide is 20 wt% to 40 wt% of the fiber.

[0105] Aspect 24 provides the fiber of any one of Aspects 1-23, wherein the fiber further comprises a flame-retardant additive.

[0106] Aspect 25 provides the fiber of Aspect 24, wherein the flame-retardant additive comprises a non-halogenated flame retardant, a polymeric halogenated flame retardant, or a combination thereof.

[0107] Aspect 26 provides the fiber of any one of Aspects 24-25, wherein the flameretardant additive is 0.01 wt% to 25 wt% of the fiber.

[0108] Aspect 27 provides the fiber of any one of Aspects 24-26, wherein the flameretardant additive is 0.1 wt% to 5 wt% of the fiber.

[0109] Aspect 28 provides the fiber of any one of Aspects 1-24, wherein the fiber is substantially free of flame-retardant additive.

[0110] Aspect 29 provides the fiber of any one of Aspects 1-28, wherein flameretardant additive is 0 wt% to 0.01 wt% of the fiber.

[0111] Aspect 30 provides the fiber of any one of Aspects 1-29, wherein the fiber has increased char formation as compared the same fiber having the combination of the partially aromatic polyamide and the at least partially aliphatic polyamide replaced with the at least partially aliphatic polyamide, as measured according to ASTM D7309-22.

[0112] Aspect 31 provides the fiber of any one of Aspects 1-30, wherein the fiber has decreased total heat release as compared the same fiber having the combination of the partially aromatic polyamide and the at least partially aliphatic polyamide replaced with the at least partially aliphatic polyamide, as measured according to ASTM D7309-22.

[0113] Aspect 32 provides the fiber of any one of Aspects 1-31, wherein the fiber has increased tenacity as compared to the same fiber having the combination of the partially aromatic polyamide and the at least partially aliphatic polyamide replaced with the partially aromatic polyamide, as measured according to ASTM DI 907.

[0114] Aspect 33 provides the fiber of any one of Aspects 1-32, wherein the fiber has increased abrasion resistance as compared to the same fiber having the combination of the partially aromatic polyamide and the at least partially aliphatic polyamide replaced with the partially aromatic polyamide, as measured according to ASTM D3885.

[0115] Aspect 34 provides the fiber of any one of Aspects 1-33, wherein the fiber has a shrinkage of 2% to 20% as measured according to ASTM D4974 (for filament) or ASTM D2102 (for staple).

[0116] Aspect 35 provides the fiber of any one of Aspects 1-34, wherein the fiber has a shrinkage of 3% to 10% as measured according to ASTM D4974 (for filament) or ASTM D2102 (for staple).

[0117] Aspect 36 provides the fiber of any one of Aspects 1-35, wherein the fiber has an elongation of 10% to 50% as measured according to ASTM D2256.

[0118] Aspect 37 provides the fiber of any one of Aspects 1-36, wherein the fiber has an elongation of 15% to 35% as measured according to ASTM D2256.

[0119] Aspect 38 provides the fiber of any one of Aspects 1-37, wherein the fiber has a tenacity of 4 g/den to 12 g/den as measured according to ASTM D1907.

[0120] Aspect 39 provides the fiber of any one of Aspects 1-38, wherein the fiber has a tenacity of 5 g/den to 10 g/den as measured according to ASTM D1907.

[0121] Aspect 40 provides a thermally resistant melt-spun fiber comprising: a partially aromatic polyamide that is PA-MXD6 and that has an RV of 2.4 to 2.9 as measured according to ISO 307 in 96% sulfuric acid; and an at least partially aliphatic polyamide that is PA66 and that has an RV of 65 to 95 as measured according to ASTM D789 as an 8.4 w/w% solution in 90% formic acid; wherein the partially aromatic polyamide is 55 wt% to 90 wt% of a total weight of polyamides in the fiber, the at least partially aliphatic polyamide is 45 wt% to 10 wt% of the total weight of polyamides in the fiber, and the partially aromatic polyamide and the at least partially aliphatic polyamide are together 90 wt% to 100 wt% of the fiber.

[0122] Aspect 41 provides a thermally resistant melt-spun fiber comprising: a partially aromatic polyamide that is PA-MXD6, that has an RV of 2.4 to 2.9 as measured according to ISO 307 in 96% sulfuric acid, and that is 55 wt% to 90 wt% of the fiber; and an at least partially aliphatic polyamide that is PA66, that is 45 wt% to 10 wt% of the fiber, and that has an RV of 65 to 95 as measured according to ASTM D789 as an 8.4 w/w% solution in 90% formic acid.

[0123] Aspect 42 provides a yam comprising the fiber of any one of Aspects 1-41.

[0124] Aspect 43 provides the yam of Aspect 42, wherein the fiber is a staple fiber, a filament fiber, or a combination thereof.

[0125] Aspect 44 provides the yam of any one of Aspects 42-43, further comprising an additional fiber.

[0126] Aspect 45 provides the yam of Aspect 44, wherein the additional fiber comprises polyurethane, polyethylene, UHMWPE, polypropylene, cellulosic fiber, regenerated cellulosic fiber, cellulose acetate, cupro, cupra, anti-static fiber, polyester, nylon, bicomponent polyester, or a combination thereof.

[0127] Aspect 46 provides the yam of any one of Aspects 44-45, wherein the additional fiber is a non-flame-resistant fiber and/or a non-thermally-resistant fiber.

[0128] Aspect 47 provides the yam of Aspect 44, wherein the additional fiber is a flame resistant fiber and/or a thermally resistant fiber.

[0129] Aspect 48 provides the yam of Aspect 47, wherein the flame resistant fiber and/or thermally resistant fiber comprises a fiber comprising FR polyester (e.g., Indorama Trevira® CS), FR nylon, FR viscose, FR rayon (e.g., Lenzing™ FR), FR lyocell, FR cellulose acetate, meta-aramid (e.g., DuPont Nomex®, Teijin Teijinconex®), para-aramid (e.g., DuPont Kevlar®, Teijin Twaron®), modacrylic (e.g., Kaneka Protex®, Aksa Armora), phenol-formaldehyde resin (e.g., Novoloid), melamine, poly(p-phenylene benzobisoxazole) (PBO), polybenzimidazole (PBI), polysulphonamide (PSA), oxidized acrylic, partially oxidized acrylic, cross-linked acrylic, polyoxadiazole, aromatic polyester, aromatic copolyimide (e.g. Teijin Technora®), polybenzimidazole (PBI), polyoxadiazole (POD) (e.g., Svetlogorsk Khimvolokno Arselon and Arselon-S), polybenzoxazole (PBO) (e.g., Toyobo Zylon®), polyamide-imide (e.g., Kermel®), polyimide (e.g., Evonik P84®), novoloid phenolic, cross-linked acrylonitrile (e.g., PyroTex®, Grupo ADI Tecstar®), oxidized or partially oxidized polyacrylonitrile (PAN) (e.g., TECGEN®), polyarylate (e.g., Kuraray Vectran™), polysulfonamide (PPS), poly{2,6-diimidazo[4,5-b:40; 50-e]-pyridinylene-l,4- (2,5-dihydroxy)phenylene} (PIPD), polyetherimide (PEI), polyethylene naphthalate (PEN), vinalon, vinylon, polytetrafluoroethylene (PTFE), expanded PTFE, or a combination thereof. [0130] Aspect 49 provides a fabric comprising the yarn of any one of Aspects 42-48. [0131] Aspect 50 provides the fabric of Aspect 49, wherein the fabric is woven, knit, non-woven, or a combination thereof.

[0132] Aspect 51 provides the fabric of any one of Aspects 49-50, wherein the fabric comprises a topical flame-retardant treatment.

[0133] Aspect 52 provides the fabric of any one of Aspects 49-51, wherein the fiber is 1 wt% to 100 wt% of a total amount of fibers in the fabric.

[0134] Aspect 53 provides the fabric of any one of Aspects 49-52, wherein the fiber is 30 wt% to 50 wt% of a total amount of fibers in the fabric.

[0135] Aspect 54 provides the fabric of any one of Aspects 49-53, wherein the fabric is self-extingui shing and provides protection according to NFPA 2112, NFPA 70E and ISO 11612, ISO 14116, ISO 61482-1-1, ISO 61482-1-2, and ISO 13506 standards.

[0136] Aspect 55 provides the fabric of any one of Aspects 49-54, wherein the yam is a primary yarn, wherein the fabric further comprises at least one additional yarn which is compositionally different from the primary yarn.

[0137] Aspect 56 provides the fabric of Aspect 55, wherein the additional yam is a flame resistant yarn and/or a thermally resistant yarn.

[0138] Aspect 57 provides the fabric of Aspect 55, wherein the additional yam is a non-flame-resistant yarn and/or a non-thermally-resistant yarn.

[0139] Aspect 58 provides a method of forming the fiber of any one of Aspects 1-41, the method comprising: melt blending the partially aromatic polyamide and the at least partially aliphatic polyamide, to form a blend; and melt-spinning the blend to form the fiber.

[0140] Aspect 59 provides the method of Aspect 58, wherein the melt-spinning comprises a total draw ratio of 3 to 6.

[0141] Aspect 60 provides the method of any one of Aspects 58-59, wherein the meltspinning comprises a total draw ratio of 3.5 to 4.7.

[0142] Aspect 61 provides the method of any one of Aspects 58-60, wherein the meltspinning comprises a total draw ratio of greater than 3.75.

[0143] Aspect 62 provides the method of any one of Aspects 58-61, wherein the blend further comprises a phosphorus-based catalyst.

[0144] Aspect 63 provides the method of Aspect 62, wherein the catalyst comprises phosphinic acid, phosphoric acid, phenyl phosphinic acid, phenyl phosphonic acid, a salt formed from these acids, or a combination thereof. [0145] Aspect 64 provides the method of any one of Aspects 62-63, wherein the catalyst increases molecular weight of the partially aromatic polyamide and/or the at least partially aliphatic polyamide during the melt blending.

[0146] Aspect 65 provides the fiber, yarn, fabric, or method of any one or any combination of Aspects 1-64 optionally configured such that all elements or options recited are available to use or select from.

Claims

CLAIMS What is claimed is:

1. A thermally resistant melt-spun fiber comprising: a partially aromatic polyamide comprising PA-MXD6, PA-PXD6, PA-MXD6/PXD6, or a combination thereof; and an at least partially aliphatic polyamide; wherein the partially aromatic polyamide is at least 50 wt% of a total amount of polyamides in the fiber.

2. The fiber of claim 1, wherein the partially aromatic polyamide comprises PA-MXD6.

3. The fiber of claim 1, wherein the partially aromatic polyamide has an RV of 2.4 to 2.9 as measured according to ISO 307 in 96% sulfuric acid.

4. The fiber of claim 1, wherein the fiber has a weight ratio of the partially aromatic polyamide to the at least partially aliphatic polyamide of 51 :49 to 95.5:0.5.

5. The fiber of claim 1, wherein the fiber has a weight ratio of the partially aromatic polyamide to the at least partially aliphatic polyamide of 60:40 to 80:20.

6. The fiber of claim 1, wherein the partially aromatic polyamide and the at least partially aliphatic polyamide together are 80 wt% to 100 wt% of the fiber.

7. The fiber of claim 1, wherein the partially aromatic polyamide and the at least partially aliphatic polyamide together are together 100 wt% of the fiber.

8. The fiber of claim 1, wherein the at least partially aliphatic polyamide comprises PA66, PA6, PA10, PAI 1, PA12, PA46, PA56, PA610, PA1010, PA1012, PA6/66, PA66/D6, PA66/6T, PA66/6I, PA66/DI, PA66/6T/6I, or a combination thereof.

9. The fiber of claim 1, wherein the at least partially aliphatic polyamide comprises PA66.

10. The fiber of claim 1, wherein the at least partially aliphatic polyamide comprises PA6.

11. The fiber of claim 1, wherein the at least partially aliphatic polyamide has an RV of 65 to 95 as measured according to ASTM D789 as an 8.4 w/w% solution in 90% formic acid

12. The fiber of claim 1, wherein the fiber further comprises a flame-retardant additive.

13. The fiber of claim 1, wherein the fiber is substantially free of flame-retardant additive, wherein flame-retardant additive is 0 wt% to 0.01 wt% of the fiber.

14. A thermally resistant melt-spun fiber comprising: a partially aromatic polyamide that is PA-MXD6 and that has an RV of 2.4 to 2.9 as measured according to ISO 307 in 96% sulfuric acid; and an at least partially aliphatic polyamide that is PA66 and that has an RV of 65 to 95 as measured according to ASTM D789 as an 8.4 w/w% solution in 90% formic acid; wherein the partially aromatic polyamide is 55 wt% to 90 wt% of a total weight of polyamides in the fiber, the at least partially aliphatic polyamide is 45 wt% to 10 wt% of the total weight of polyamides in the fiber, and the partially aromatic polyamide and the at least partially aliphatic polyamide are together 90 wt% to 100 wt% of the fiber.

15. A thermally resistant melt-spun fiber comprising: a partially aromatic polyamide that is PA-MXD6, that has an RV of 2.4 to 2.9 as measured according to ISO 307 in 96% sulfuric acid, and that is 55 wt% to 90 wt% of the fiber; and an at least partially aliphatic polyamide that is PA66, that is 45 wt% to 10 wt% of the fiber, and that has an RV of 65 to 95 as measured according to ASTM D789 as an 8.4 w/w% solution in 90% formic acid.

16. A yarn comprising the fiber of claim 1.

17. A fabric comprising the yarn of claim 16.

18. The fabric of claim 17, wherein the fabric comprises a topical flame-retardant treatment.

19. A method of forming the fiber of claim 1, the method comprising: melt blending the partially aromatic polyamide and the at least partially aliphatic polyamide, to form a blend; and melt-spinning the blend to form the fiber.

20. The method of claim 19, wherein the blend further comprises a phosphorus-based catalyst.