Patent Description:
Furthermore, and especially challenging as the total amount of all non-polyamide components in the resin system increases, acceptable melt processing properties at both the compounding and molding stages is required. In addition to desired flame-retardant properties, mechanical properties, and processing properties, there may also be other desired properties, such as and without limitation, electrical properties (e.g., dielectric strength, volume and surface resistivity, and comparative tracking resistance), surface gloss, color, thermal stability, UV stability, corrosivity, resistance to migration, chemical resistance, toxicity, as well as non-technical requirements such as cost efficiency. To achieve these other desired properties, other functional additives can be incorporated into the flame-retardant composition, whose presence may also influence the flame-retardant properties, mechanical properties, and processing properties.

One challenge to one skilled in the art is to discover means to achieve these diverse requirements when the interplay between the components in the resin system may counter each other's effects in achieving these requirements. So even with the variety of flame-retardant additives and functional additives commercially available, it is not a predictable pathway for a person having ordinary skill in the art to find a combination of ingredients in unfilled or filled resins which, together, can achieve a desired flame-retardant property (for instance a V-<NUM> rating in a <NUM> thick flammability bar in the Underwriters' Laboratories Test No. UL <NUM> testing) in combination with mechanical, processing, and other needed properties.

The present invention provides a flame-retardant polyamide composition that includes nylon <NUM> that is <NUM> wt% to <NUM> wt% of the composition. The nylon <NUM> has an RV of ≥<NUM> to ≤<NUM> as measured in an <NUM> wt% solution in <NUM>% formic acid. The composition also includes one or more flame-retardant additives. The flame-retardant additives are preferably <NUM> wt% to <NUM> wt% of the composition. The composition is substantially free of poly(arylene ether) and non-polyamide copolymers thereof, and has a flame retardancy rating at <NUM> of V-<NUM>, V-<NUM>, or V-<NUM> as measured by Underwriters' Laboratories Test No. UL <NUM>, wherein the one or more flame-retardant additives are halogen-containing flame-retardant additives, halogen-containing flame-retardant additives with synergists, phosphorus-containing flame-retardant additives, inorganic flame-retardant additives, nitrogen-containing flame-retardant additives, nitrogen-containing flame-retardant additives with synergists, or a combination thereof, wherein the nitrogen-containing flame-retardant additives are selected from melamine cyanurate, melamine polyphosphate, melamine pyrophosphate, or mixtures thereof.

In various aspects, the present invention provides a flame-retardant polyamide composition including nylon <NUM> that is <NUM> wt% to <NUM> wt% of the composition The nylon <NUM> has an RV of ≥<NUM> to ≤<NUM>. The composition also includes one or more flame-retardant additives that are <NUM> wt% to <NUM> wt% of the composition, the one or more flame-retardant additives chosen from melamine cyanurate, aluminum diethylphosphinate, melamine polyphosphate, bromopolystyrene, antimony trioxide, dehydrated zinc borate, and a combination thereof. The composition is substantially free of glass fibers, and the composition has a flame retardancy rating at <NUM> of V-<NUM>, V-<NUM>, or V-<NUM> as measured by Underwriters' Laboratories Test No. UL <NUM>. The composition can have a flame retardancy rating at <NUM> of V-<NUM> as measured by Underwriters' Laboratories Test No. UL <NUM>.

In various aspects, the present invention provides a flame-retardant polyamide composition including nylon <NUM> that is <NUM> wt. % to <NUM> wt% of the composition. The nylon <NUM> has an RV of ≥<NUM> to ≤<NUM>. The composition also includes one or more flame-retardant additives that are <NUM> wt% to <NUM> wt% of the composition, the one or more flame-retardant additives chosen from melamine cyanurate, aluminum diethylphosphinate, melamine polyphosphate, bromopolystyrene, antimony trioxide, dehydrated zinc borate, and a combination thereof. The composition also includes a glass fiber reinforcing filler that is about <NUM> wt% to about <NUM> wt% of the composition. The composition has a flame retardancy rating at <NUM> of V-<NUM>, V-<NUM>, or V-<NUM> as measured by Underwriters' Laboratories Test No. UL <NUM>. The composition can have a flame retardancy rating at <NUM> of V-<NUM> as measured by Underwriters' Laboratories Test No. UL <NUM>.

In various aspects, the present invention provides a method of making the flame-retardant polyamide composition, such as any embodiment of the flame-retardant polyamide composition described herein. The method includes combining the polyamide with the one or more flame-retardant additives to form the flame-retardant polyamide composition.

In various aspects, the flame-retardant composition including the polyamide and the flame-retardant additive can have certain advantages over other polyamide compositions, at least some of which are unexpected. For example, in some aspects, the flame-retardant polyamide composition can have a combination of high strength and good processability with good flame-retardant properties. In various aspects, it is possible to incorporate one or more flame-retardant additives to produce a flame-retardant polyamide composition with surprising ease of processability both during manufacture and subsequent melt processing by using a polyamide having a relative viscosity (RV) from ≥ <NUM> to ≤ <NUM> using production assets for which manufacture or subsequent processing would fail if used for polyamides outside of this RV range due to resultant poor processability.

In some aspects, the one or more flame-retardant additives can have a greater flame-retarding effect in the flame-retardant polyamide composition of the present invention as compared to other polyamide compositions including the same or greater concentration of the one of more flame-retardant additives. In some aspects, a particular concentration of the one or more flame-retardant additives in the flame-retardant polyamide composition of the present invention results in a greater flame-retardant effect, as measured by the UL <NUM> test rating, when used with a polyamide having an RV from ≥ <NUM> to ≤ <NUM>, as compared to an otherwise identical polyamide composition including the same or greater concentration of the one or flame-retardant additives but including a polyamide having an RV that is < <NUM> or > <NUM>.

Typically, lowering the concentration of one or more fire-retardant additives in a polyamide composition results in a decrease in the fire-retardancy of the polyamide composition. However, in some aspects, a lower concentration of the one or more flame-retardant additives in the flame-retardant polyamide composition of the present invention can be used to accomplish the same or better flame-retardant property as an otherwise identical polyamide composition including the same or greater concentration of the one or flame- retardant additives but including a polyamide having an RV that is < <NUM> or > <NUM>.

In the methods described herein, the acts can 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. 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.

The term "substantially free of' can mean having a trivial amount of, such that a composition is about <NUM> wt% to about <NUM> wt% of the material, or about <NUM> wt% to about <NUM> wt%, or about <NUM> wt% or less, or less than, equal to, or greater than about <NUM> wt%, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or about <NUM> wt% or less, or about <NUM> wt%.

The polymers described herein can terminate in any suitable way. In some aspects, the polymers can terminate with an end group that is independently chosen from a suitable polymerization initiator, -H, -OH, a substituted or unsubstituted (C<NUM>-C<NUM>)hydrocarbyl (e.g., (C<NUM>-C<NUM>)alkyl or (C<NUM>-C<NUM>)aryl) interrupted with <NUM>, <NUM>, <NUM>, or <NUM> groups independently selected from -O-, substituted or unsubstituted -NH-, and -S-, a poly(substituted or unsubstituted (C<NUM>-C<NUM>)hydrocarbyloxy), and a poly(substituted or unsubstituted (Ci-C<NUM>)hydrocarbylamino).

Various aspects of the present invention provide a flame-retardant polyamide composition. The composition includes a polyamide that is <NUM> wt % to <NUM> wt% of the composition. The polyamide has a relative viscosity (RV) of ≥<NUM> to ≤<NUM>. The composition also includes one or more flame-retardant additives. The composition can be substantially homogeneous, such that the polyamide, one or more flame-retardant additives, and any other components such as fillers, are evenly distributed with regard to one another in the composition. The composition can have good flame-retardant properties. For example, the composition can have a flame retardancy rating at <NUM> of V-<NUM> or better (e.g., V-<NUM> or V-<NUM>), or of V-<NUM>, as measured by Underwriters' Laboratories Test No. UL <NUM>, as described herein. In some aspects, the RV range of the polyamide can increase the effectiveness of the one or more flame-retardant additives. For example, another composition that includes a polyamide having a different RV (e.g., an RV of <<NUM> or ><NUM> instead of an RV of ≥<NUM> to ≤<NUM>) but is otherwise identical can have less flame-retardancy as measured by Underwriters' Laboratories Test No. UL <NUM>. In various aspects, another composition that includes a polyamide having a different RV (e.g., an RV of <<NUM> or ><NUM> instead of an RV of ≥<NUM> to ≤<NUM>) but is otherwise identical can require a greater concentration of the one or more flame-retardant additives to achieve the same flame-retardancy as measured by Underwriters' Laboratories Test No. UL <NUM>.

An aspect of this disclosure is that by using a polyamide having a relative viscosity (RV) from ≥ <NUM> to ≤ <NUM> in combination with the one or more flame-retardant additives, it is possible to either (i) improve on the flame-retardant properties, or classification (e.g., UL <NUM> test rating), of the flame-retardant polyamide system as compared to using a polyamide having an RV outside of this range; or (ii) if the flame-retardant classification is at its highest level or is already at a desired level then it is possible to reduce the amount of the one or more flame-retardant additives.

Another aspect of this disclosure is that it is possible to incorporate one or more flame-retardant additives to produce a flame-retardant polyamide resin that is processable both during manufacture and subsequent melt processing by using a polyamide having a relative viscosity (RV) from ≥ <NUM> to ≤ <NUM> using production assets that, if used using polyamide outside of this range, manufacture and/or subsequent processing would fail.

In addition to the good flame-retardant properties in combination with efficient use of the one or more flame-retardant additives, and the good processability, the flame-retardant polyamide composition can also have good mechanical properties. In some aspects, the composition can have a tensile strength at break of <NUM> MPa to <NUM> MPa as measured by the method of ISO <NUM>, or <NUM> MPa to <NUM> MPa, or <NUM> MPa or less, or less than, equal to, or greater than <NUM> MPa, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> MPa, or <NUM> MPa or more. In some aspects, the composition can have a tensile modulus of <NUM>,<NUM> MPa to <NUM>,<NUM> MPa as measured by the method of ISO <NUM>, or <NUM>,<NUM> MPa to <NUM>,<NUM> MPa, or <NUM>,<NUM> MPa or less, or less than, equal to, or greater than <NUM>,<NUM> MPa, <NUM>,<NUM>, <NUM>,<NUM>, <NUM>,<NUM>, <NUM>,<NUM>, <NUM>,<NUM>, <NUM>,<NUM>, <NUM>,<NUM>, <NUM>,<NUM>, <NUM>,<NUM>, <NUM>,<NUM>, <NUM>,<NUM>, <NUM>,<NUM>, or <NUM>,<NUM> MPa or more.

The flame-retardant polyamide composition can be in any suitable physical form. The flame-retardant polyamide composition can be a in the form of a flame-retardant fiber.

The polyamide is <NUM> wt % to <NUM> wt% of the composition. For example, the polyamide can be about <NUM> wt% to about <NUM> wt%, or about <NUM> wt% to about <NUM> wt%, or about <NUM> wt% or less, or less than, equal to, or greater than about <NUM> wt%, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or about <NUM> wt% or more. A composition that is free of glass fibers or free of other structural fillers can have a higher proportion of the polyamide therein, such as about <NUM> wt% to about <NUM> wt% of the composition, or about <NUM> wt% to about <NUM> wt%, or about <NUM> wt% or less, or less than, equal to, or greater than about <NUM> wt%, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or about <NUM> wt% or more. A composition that includes a structural filler such as glass fibers can have a lower proportion of the polyamide therein, such as about <NUM> wt% to about <NUM> wt% of the composition, or about <NUM> wt% to about <NUM> wt% of the composition, or about <NUM> wt% or less, or less than, equal to, or greater than about <NUM> wt%, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or about <NUM> wt% or more.

Polyamides and copolyamides are derived from diamines and dicarboxylic acids and/or from aminocarboxylic acids or the corresponding lactams. In various aspects, the composition can be free of polyamide copolymers formed from flame-retardant monomers, such as phosphorus-containing monomers, such as <NUM>,<NUM>-dihydro-<NUM>-oxa-<NUM>-phosphaphenanthrene-<NUM>-oxide (DOPO). In various aspects, the polyamide can be free of melamine cyanurate polyamide composites formed from adipic acid-melamine salts and cyanuric acid-hexane diamine salts, or formed by polymerization of the polyamide in the presence of melamine cyanurate.

For example, the polyamide can be formed from monomers chosen from tetramethylenediamine, hexamethylenediamine, <NUM>-methylpentamethylenediamine (D), diaminodecane, diaminododecane, <NUM>,<NUM>,<NUM>-trimethylhexamethylenediamine, <NUM>,<NUM>,<NUM>-trimethylhexamethylenediamine, adipic acid, azelaic acid, sebacic acid, dodecanedioic acid, iso- and/or terephthalic acid, ε-caprolactam, undecanlactam, laurolactam, and mixtures thereof. Monomers may also include those which may contribute to the flame-retardant behavior of the whole system, such as a phosphorus-containing monomer, for example, bis(<NUM>-carboxyethyl)phenylphosphineoxide.

The polyamide can be formed from monomers including hexamethylenediamine and adipic acid. The polyamide is nylon <NUM>. The polyamide is nylon <NUM> and the composition can optionally be substantially free of all other polyamides (e.g., nylon <NUM> can be the only polyamide used to form the composition).

Polyamides can be manufactured by polymerization of dicarboxylic acids and diacid derivatives and diamines. In some cases, polyamides may be produced via polymerization of aminocarboxylic acids, aminonitriles, or lactams. The dicarboxylic acid component is suitably at least one dicarboxylic acid of the molecular formula HO<NUM>C-R<NUM>-CO<NUM>H; wherein R<NUM> represents a divalent aliphatic, cycloaliphatic or aromatic radical or a covalent bond. R<NUM> suitably includes from <NUM> to <NUM> carbon atoms, for example, <NUM> to <NUM> carbon atoms or <NUM> to <NUM> carbon atoms. R<NUM> may be a linear or branched (e.g., linear) alkylene radical including <NUM> to <NUM> carbon atoms, or <NUM> to <NUM> carbon atoms, for example <NUM>, <NUM>, <NUM> or <NUM> carbon atoms, an unsubstituted phenylene radical, or an unsubstituted cyclohexylene radical. Optionally, R<NUM> may contain one or more ether groups. For example, R<NUM> is an alkylene radical, for example a linear alkylene radical, including <NUM> to <NUM> carbon atoms, or <NUM> to <NUM> carbon atoms, for example, <NUM>, <NUM>, <NUM>, or <NUM> carbon atoms.

Specific examples of suitable dicarboxylic acids can include hexane-<NUM>,<NUM>-dioic acid (adipic acid), octane-<NUM>,<NUM>-dioic acid (suberic acid), decane-<NUM>,<NUM>-dioic acid (sebacic acid), dodecane-<NUM>,<NUM>-dioic acid, <NUM>,<NUM>-cyclohexanedicarboxylic acid, <NUM>,<NUM>-cyclohexanedicarboxylic acid, <NUM>,<NUM>-cyclohexanedicarboxylic acid, <NUM>,<NUM>-cyclohexanediacetic acid, <NUM>,<NUM>-cyclohexanediacetic acid, benzene-<NUM>,<NUM>-dicarboxylic acid (phthalic acid), benzene-<NUM>,<NUM>-dicarboxylic acid (isophthalic acid), benzene-<NUM>,<NUM>-dicarboxylic acid (terephthalic acid), <NUM>,<NUM>'-oxybis(benzoic acid), and <NUM>,<NUM>-naphthalene dicarboxylic acid. A suitable dicarboxylic acid is hexane-<NUM>,<NUM>-dioic acid (adipic acid).

The diamine component can be at least one diamine of the formula H<NUM>N-R<NUM>-NH<NUM>, wherein R<NUM> represents a divalent aliphatic, cycloaliphatic or aromatic radical. R<NUM> can include from <NUM> to <NUM> carbon atoms, for example, <NUM> to <NUM> carbon atoms, or <NUM> to <NUM> carbon atoms. R<NUM> may be a linear or branched (e.g., linear) alkylene radical including <NUM> to <NUM> carbon atoms, or <NUM> to <NUM> carbon atoms, for example, <NUM>, <NUM>, or <NUM> carbon atoms, an unsubstituted phenylene radical, or an unsubstituted cyclohexylene radical. Optionally, R<NUM> may contain one or more ether groups. For example, R<NUM> can be an alkylene radical, for example, a linear alkylene radical, including <NUM> to <NUM> carbon atoms, or <NUM> to <NUM> carbon atoms, for example, <NUM>, <NUM>, <NUM>, or <NUM> carbon atoms.

Specific examples of suitable diamines include tetramethylene diamine, pentamethylene diamine, hexamethylene diamine, octamethylene diamine, decamethylene diamine, dodecamethylene diamine, <NUM>-methylpentamethylene diamine, <NUM>-methylpentamethylene diamine, <NUM>-methylhexamethylene diamine, <NUM>-methylhexamethylene diamine, <NUM>,<NUM>-dimethylhexamethylene diamine, <NUM>,<NUM>,<NUM>-trimethylhexamethylene diamine, <NUM>,<NUM>,<NUM>-trimethylhexamethylene diamine, <NUM>,<NUM>-dimethyloctamethylene diamine, <NUM>,<NUM>,<NUM>,<NUM>-tetramethyloctamethylene diamine, <NUM>,<NUM>-cyclohexanediamine, <NUM>,<NUM>-cyclohexanediamine, <NUM>,<NUM>-cyclohexanediamine, <NUM>,<NUM>'-diaminodicyclohexylmethane, benzene-<NUM>,<NUM>-diamine, benzene-<NUM>,<NUM>-diamine and benzene-<NUM>,<NUM>-diamine. A suitable diamine is hexamethylene diamine.

The aromatic diacid is suitably at least one diacid of the formula HO-C(O)-R<NUM>-C(O)-OH, wherein the variable R<NUM> is substituted or unsubstituted aryl, such as phenyl. In one aspect, the aromatic diacid is terephthalic acid.

The polyamide resin can further include a catalyst. In one aspect, the catalyst can be present in the polyamide resin in an amount ranging from <NUM> ppm to <NUM>,<NUM> ppm by weight. In another aspect, the catalyst can be present in an amount ranging from <NUM> ppm to <NUM> ppm by weight. The catalyst can include, without limitation, phosphorus and oxyphosphorus compounds, such as phosphoric acid, phosphorous acid, hypophosphorous acid, hypophosphoric acid, arylphosphonic acids, arylphosphinic acids, salts thereof, or mixtures thereof. In one aspect, the catalyst can be sodium hypophosphite (SHP), manganese hypophosphite, sodium phenylphosphinate, sodium phenylphosphonate, potassium phenylphosphinate, potassium phenylphosphonate, hexamethylenediammonium bis-phenylphosphinate, potassium tolylphosphinate, or mixtures thereof. In one aspect, the catalyst can be sodium hypophosphite (SHP).

In various aspects, the flame-retardant polyamide composition can be substantially free of poly(arylene ether), non-polyamide copolymers thereof, or a combination thereof. For example, the composition can be substantially free of poly(phenylene ether), non-polyamide copolymers thereof such as polysiloxane block copolymers of poly(phenylene ether), or a combination thereof. In various aspects, the polyamide composition can be substantially free of styrenic copolymers, polyolefins, non-polyamide polyesters, derivatives thereof, or a combination thereof. The composition can be substantially free of styrene-ethylene-butadiene-styrene (SEBS), non-polyamide polymers, derivatives thereof, or a combination thereof. The composition can be substantially free of maleated styrene-hydrogenated butadiene-styrene. Any one or more of poly(arylene ether), non-polyamide copolymers thereof, styrenic copolymers, polyolefins, non-polyamide polyesters, non-polyamide polymers, and derivatives thereof, can form a trivial amount of the composition, such as about <NUM> wt% to about <NUM> wt% of the composition, or about <NUM> wt% to about <NUM> wt%, or about <NUM> wt% or less, or less than, equal to, or greater than about <NUM> wt%, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or about <NUM> wt% or less, or about <NUM> wt% of the composition.

The polyamide in the flame-retardant polyamide composition can have a particular relative viscosity range. Relative viscosity is the ratio of the viscosity of the solution to the viscosity of the solvent used. For polyamides, RV is measured as an <NUM> wt% solution in <NUM>% formic acid, at room temperature and pressure, unless otherwise indicated. The polyamide can have any suitable RV (as measured in <NUM> wt% solution in <NUM>% formic acid), such as ≥<NUM> to <<NUM>, ≥<NUM> to <<NUM>, ≥<NUM> to ≤<NUM>, or <NUM> to <NUM>, <NUM> to <NUM>, <NUM> to <NUM>, <NUM> to <NUM>, <NUM> to <NUM>, <NUM> to <NUM>, <NUM> to <NUM>, ≥<NUM> to <<NUM>, ≥<NUM> to ≤<NUM>, ≥<NUM> to <<NUM>, ≥<NUM> to <<NUM>, ≥<NUM> to <<NUM>, or about <NUM> or less, or less than, equal to, or greater than <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or about <NUM> or more. For the flame-retardant polyamide composition herein, the RV refers to the RV of the polyamide when tested alone and without any of the other components of the composition such as the one or more flame-retardant additives and without any processing additives or fillers such as glass fibers. Other methods of determining the RV, such as a <NUM> wt% solution in concentrated sulfuric acid, may be used and an appropriate correlation of RVs between the method used and the <NUM> wt% in <NUM>% formic acid method, as used herein, can be determined.

An alternative method of determining the RV is to measure the Viscosity Number (VN, sometime referred to as Viscosity Index) of the polyamide according to ISO <NUM> and use the conversion relationships for N66 within the ISO standard to convert the VN to RV. In the case of N66, by way of non-limiting example, a VN (as determined as a <NUM> wt% solution in <NUM>% sulfuric acid) of <NUM> corresponds to an RV of <NUM> (as measured as a <NUM> wt% solution in <NUM>% formic acid). The ISO <NUM>:<NUM> at page <NUM> gives an equation for the interconversion as VN = -<NUM> + <NUM> * ln(RV), which means RV = exp((VN+<NUM>)/<NUM>). Using this equation, for N66, an RV of <NUM> would correspond to a VN of about <NUM>/g, and an RV of <NUM> would correspond to a VN of <NUM>/g, with RV measured as a <NUM> wt% solution in <NUM>% formic acid and with VN measured as a <NUM> wt% solution in <NUM>% sulfuric acid. Strictly this relationship is for N66, but for the purposes herein may be applied approximately to other polyamides, it being useful to do so when the polyamide has poor solubility characteristics in <NUM>% formic acid but may be dissolved as a <NUM> wt% solution in <NUM>% sulfuric acid for solution viscosity determinations. Similarly, as reported in ISO <NUM>:<NUM> at page <NUM>, VN as determined as a <NUM> wt% solution in <NUM>% sulfuric acid can be converted to RV as measured as a <NUM>% solution in <NUM>% sulfuric acid as VN = <NUM>*RV - <NUM>, which means RV = (VN+<NUM>)/<NUM>. Similarly, as reported in ISO <NUM>:<NUM> at pages <NUM>-<NUM>, VN as determined as a <NUM> wt% solution in <NUM>% sulfuric acid can be converted to RV as measured as a <NUM>% solution in <NUM>% sulfuric acid as VN = <NUM>*RV - <NUM> or VN = <NUM>*RV - <NUM>, which means RV = (VN+<NUM>)/<NUM> or RV = (VN+<NUM>)/<NUM>. As reported in ISO <NUM>:<NUM> at page <NUM>, for PA66, ln y = <NUM> + <NUM>*ln x, wherein y is the viscosity number in <NUM>% sulfuric acid, and x is the viscosity number in <NUM>% formic acid. If additives are present that interfere with viscosity measurement in a particular solvent, viscosity measurements cannot accurately be converted from one solvent to another.

The flame-retardant polyamide composition can include one flame-retardant additive, or more than one flame-retardant additive, wherein the type and amount of the flame-retardant additive are sufficient to impart a desired amount of flame-retardant effect to the polyamide composition as described herein.

The one or more flame-retardant additives can be any suitable proportion of the composition. For example, the one or more flame-retardant additives can be about <NUM> wt% to about <NUM> wt% of the composition, about <NUM> wt% to about <NUM> wt%, about <NUM> wt% or less, or less than, equal to, or greater than about <NUM> wt%, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or about <NUM> wt% or more of the composition. In some aspects, in a composition that is substantially free of reinforcing fillers or free of glass fibers a lower amount of flame retardant can be used, such as about <NUM> wt% to about <NUM> wt%, about <NUM> wt% to <NUM> wt%, or about <NUM> wt% or less, or less than, equal to, or greater than about <NUM> wt%, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or about <NUM> wt% or more. In some aspects, in a composition that includes reinforcing fillers such as glass fibers a greater amount of flame retardant can be used, such as about <NUM> wt% to <NUM> wt% of the composition, or <NUM> wt% to <NUM> wt%, or about <NUM> wt% or less, or less than, equal to, or greater than about <NUM> wt%, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or about <NUM> wt% or more.

The one or more flame-retardant additives are halogen-containing flame-retardant additives, halogen-containing flame-retardant additives with synergists, phosphorus-containing flame-retardant additives, inorganic flame-retardant additives, nitrogen-containing flame-retardant additives, nitrogen-containing flame-retardant additives with synergists, or a combination thereof, wherein the nitrogen-containing flame-retardant additives are selected from melamine cyanurate, melamine polyphosphate, melamine pyrophosphate, or mixtures thereof. A particular flame-retardant additive can be added neat, or can be available as or formed into a blend with a polyamide (e.g., a masterbatch) prior to combining with the polyamide in the flame-retardant composition. In some aspects, the one or more flame retardants can be chosen from Melapur™ MC25, Mastertek® <NUM>, Exolit® OP <NUM>, Exolit® OP <NUM>, vPreniphor™ EPFR-MPP300, SAYTEX® HP <NUM>, Campine PA <NUM>, Firebrake® <NUM>, or a combination thereof. The one or more flame retardants can be chosen from melamine cyanurate, aluminum diethylphosphinate, melamine polyphosphate, bromopolystyrene, antimony trioxide, dehydrated zinc borate, and a combination thereof.

Broad classes of flame-retardant additives can include, for example: halogen-containing flame-retardant additives, halogen-containing flame-retardant additives with synergists, phosphorus-containing flame-retardant additives, inorganic flame-retardant additives, nitrogen-containing flame-retardant additives, nitrogen-containing flame-retardant additives with synergists; these may be used alone or in combination. <NPL> speaks to the general topic of flame-retardant additives in polyamides and in Table <NUM> p <NUM> exemplifies typical flame-retardant additives and the levels of various flame-retardant additives used in polyamides. <NPL> speaks to the general topic and in Table <NUM> p. <NUM> exemplifies flame-retardant additives and the levels of flame-retardant additives used in polyamides. <NPL>speaks to the topic of flame-retardant additives and exemplifies flame-retardant additives and the levels of flame-retardant additives used in polyamides throughout. Manufacturers and providers of flame-retardant additives will often supply guidance on effective formulations, for instance, ICL Industrial Products Ltd produces such a <NPL>.

Halogen-containing flame-retardant additives can include: brominated polystyrene; poly(dibromostyrene); poly(pentabromobenzylacrylate); brominated polyacrylate; brominated epoxy polymer; epoxy polymers derived from tetrabromobisphenol A and epichlorohydrin; ethylene-<NUM>,<NUM>-bis(pentabromophenyl); Dechlorane plus; chlorinated polyethylene; or mixtures thereof.

Synergists, such as for use with halogen-containing flame-retardant additives, can include antimony (III) oxide, antimony (V) oxide, sodium antimonate; iron (II) oxide, iron (II/III) oxide, iron (III) oxide, zinc borate, zinc phosphate, zinc stannate, or mixtures thereof.

Phosphorus-containing flame-retardant additives can include red phosphorus, ammonium polyphosphate, melamine polyphosphate, melamine pyrophosphate, metal dialkylphosphinates (such as aluminum methylethylphosphinate, and aluminum diethylphosphinate), aluminum hypophosphite, or mixtures thereof.

Inorganic flame-retardant additives can include magnesium hydroxide, alumina monohydrate, alumina trihydrate, aluminum hydroxide, or mixtures thereof.

Nitrogen-containing flame-retardant additives can include melamine cyanurate, melamine polyphosphate, melamine pyrophosphate, or mixtures thereof.

Nitrogen-containing flame-retardant additives with synergists can include nitrogen-containing flame-retardant additives together with a synergist, such as but not limited to, Novolac resins (e.g., phenol-formaldehyde resins with a formaldehyde to phenol molar ratio of less than one).

Small amounts of polytetrafluoroethylene can be incorporated into the composition or into the flame-retardant additives, such as to retard dripping.

The literature of flame-retardant additives also speaks to the different mechanisms by which the flame-retardant additive imparts its flame-retardant properties to the polyamide. The flame-retardant additive can be active in the condensed phase, the gas phase, or both. In the condensed phase the flame-retardant additive may act as a heat sink or may participate in the formation of char (e.g., an intumescent system) limiting heat and mass transportation, or provide conduction of heat away by evaporation or mass dilution. In the gas phase, flame-retardant additives may act by interrupting the combustion chemistry by providing volatile species that form radicals in the gas phase which quench the radical chain reactions that would otherwise initiate or propagate the fire. In various aspects, the flame-retardant polyamide composition may aid or enhance the effectiveness of these flame-retarding mechanisms.

There are a variety of tests and standards that may be used to rate the flame-retardant nature of a polymeric resin system, such as Underwriters' Laboratories Test No. UL <NUM>, or another rating system. "UL <NUM> Standard for Tests for Flammability of Plastic Materials for Parts in Devices and Appliances" gives details of the UL <NUM> testing method and criteria for rating. The test method ASTM D635 is the Standard Test Method for Rate of Burning and/or Extent and Time of Burning of Plastics in a Horizontal Position. The test method ASTM D3801 is the Standard Test Method for Measuring the Comparative Burning Characteristics of Solid Plastics in a Vertical Position. These test methods can be used to generate vertical and horizontal burning UL <NUM> test ratings. Vertical burning test ratings (e.g.: V-<NUM>, V-<NUM>, V-<NUM>) are more stringent and difficult to achieve than horizontal burning ratings (HB-<NUM>, HB-<NUM>, HB-<NUM>). As seen in Table <NUM>, the V-<NUM> rating is distinguished from the V-<NUM> and V-<NUM> ratings, which are less acceptable if one is seeking the best flame retardance rating. For certain uses, V-<NUM> is acceptable. A specimen must meet all the criteria conditions for a particular rating to achieve that rating. A specimen that fails to reach all the criteria conditions within any of V-<NUM>, V-<NUM>, or V-<NUM> ratings is rated V-NOT.

The UL <NUM> Flammability test performance rating may be assessed at various thicknesses, for instance and without limitation, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>. By achieving a UL <NUM> V-<NUM> rating at a particular thickness, such as <NUM>, it is known that a plastic article having any larger thickness will also achieve a UL <NUM> V-<NUM> rating. Obtaining a V-<NUM> rating is more difficult to achieve in thinner test specimens, such as for <NUM> or <NUM> thicknesses, than thicker ones, such as <NUM> or <NUM> thickness.

Other tests and instruments exist to rate flammability, such as: the Limiting Oxygen Index (LOI) test (ASTM <NUM>); the cone calorimetry instrument (which measures amount and rate of heat release during combustion, ASTM E <NUM> and ISO <NUM>-<NUM> standards are both based upon this instrument); Glow Wire Flammability (IEC <NUM>-<NUM>-<NUM>); or Glow Wire Ignition (IEC <NUM>-<NUM>-<NUM>).

Other tests which exist to rate flame retardancy include, and are not limited to, those where a determination is made of the rate of smoke generation, smoke obscuration, or the toxicity of smoke and combustion gases.

Other tests exist to rate flame retardancy which are application-specific, such as apparel fabrics, upholstery fabrics, airbag fabrics, carpets, or rugs.

The flame-retardant polyamide composition can include one or more reinforcing fillers. The reinforcing fillers can be any suitable one or more fillers that provide a desired mechanical property. For example, the one or more reinforcing fillers can be carbon (e.g., carbon fibers), glass (e.g., glass fibers), fibrous materials, Kevlar, cellulose, graphene, silicates, nanotubes, diamonds, or a combination thereof. The reinforcing filler can be glass fibers.

Standard industrial glass filler fibers are useful in accordance with the disclosed composition and process. For information on incorporating glass fibers into nylon <NUM>, see<NPL>. The one or more glass fibers can be about <NUM> wt% to about <NUM> wt% of the flame-retardant polyamide composition, or about <NUM> wt% to about <NUM> wt%, or about <NUM> wt% to about <NUM> wt%, ≥<NUM> wt% to ≤<NUM> wt%, ≥<NUM> wt% to <<NUM> wt%, ≥<NUM> wt% to ≤<NUM> wt%, ≥<NUM> wt% to ≤<NUM>, or about <NUM> wt% or less, or less than, equal to, or greater than about <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> wt%, or about <NUM> wt% or more, for example <NUM> wt% glass fibers, based on the weight of the finished polyamide composition including all additives and fillers (including the glass fibers).

The composition can include one type of glass fibers or multiple types of glass fibers. The glass fibers may have cross-sectional shapes other than round, for example, oval, rectangular, multilobal, or H- or I-shaped. The one or more glass fibers can form any suitable proportion of the composition, such as ≥<NUM> wt% to ≤<NUM> wt%, ≥<NUM> wt% to ≤<NUM> wt%, ≥<NUM> wt% to ≤<NUM> wt%, ≥<NUM> wt% to ≤<NUM> wt%, or about <NUM> wt%. The glass fibers can be any suitable glass fibers, such as glass fibers including soda-lime glass, fused silica glass, borosilicate glass, lead-oxide glass, aluminosilicate glass, oxide glass, glass with high zirconia content, or a combination thereof. Glass fibers can have any suitable dimensions. The glass fibers can have a length of about <NUM> to about <NUM>, about <NUM> to about <NUM>, about <NUM> to about <NUM>, about <NUM> to about <NUM>, or about <NUM> or less, or less than, equal to, or greater than about <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or about <NUM> or more. Glass fibers can have a diameter (e.g., largest cross-sectional dimension) of about <NUM> microns to about <NUM> in diameter, about <NUM> to about <NUM> in diameter, or about <NUM> microns or less, or less than, equal to, or greater than about <NUM> micron, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> microns, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or about <NUM> or more.

The flame-retardant polyamide composition of the present disclosure can include any one or more suitable additives. For example, the other additives can include fillers such as talc, mica, clay, silica, alumina, carbon black, natural fiber, wood flour, wood fibers, non-wood plant fibers, sawdust, wood shavings, newsprint, paper, flax, hemp, wheat straw, rice hulls, kenaf, jute, sisal, peanut shells, soy hulls, or combinations thereof. The composition can include one or more catalysts, acid generators, solvents, compatibilizers, crosslinkers, anti-blocking agents, coupling agents, fillers, heat stabilizers, light stabilizers, antioxidants, impact modifiers, tackifiers, flame retardants, plasticizers, blowing agents, colorants, dyes, fragrances, foaming additives, processing aids, lubricants, adhesion promoters, biocides, antimicrobial additives, or combinations thereof. Non-limiting examples of optional additives include anti-fogging agents, anti-static agents, anti-oxidants, bonding, blowing and foaming agents, dispersants, extenders, smoke suppressants, impact modifiers, initiators, nucleants, pigments, colorants and dyes, optical brighteners, plasticizers, processing aids, release agents, silanes, titanates and zirconates, slip agents, anti-blocking agents, stabilizers, stearates, ultraviolet light absorbers, waxes, catalyst deactivators, or combinations thereof.

The flame-retardant polyamide composition can include one or more processability additives, such as to improve the processability of the polyamide (e.g., to decrease the viscosity of the polyamide composition during processing). The one or more processability additives can form any suitable proportion of the composition, such as about <NUM> wt% to about <NUM> wt% of the composition, about <NUM> wt% to about <NUM> wt%, or about <NUM> wt% or less, or less than, equal to, or greater than about <NUM> wt%, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or about <NUM> wt% or more. One example of a suitable processability additive is Irganox® B1171, a commercial polymer additive product of BASF, which is a blend of hindered phenolic antioxidant (<NPL>) and a phosphite (<NPL>), for processing and long-term thermal stabilization.

The flame-retardant polyamide composition of the present disclosure can include conventional plastics-additives in an amount that is sufficient to obtain a desired processing or performance property for the polyamide composition. The amount should not be wasteful of the additive nor detrimental to the processing or performance of the polyamide composition. Those skilled in the art of thermoplastics compounding, without undue experimentation but with reference to such treatises as <NPL>), can select from many different types of additives for inclusion into the polyamide compositions of the present disclosure.

Even with the variety of functional additives commercially available, it is not a predictable pathway for a person having ordinary skill in the art to find a particular combination of ingredients which, together, can achieve a V-<NUM> rating in a UL <NUM> Flammability test.

Without undue experimentation but with such references as "<NPL>"; "<NPL>"; "<NPL>"; "<NPL>"; and "<NPL> (see, elsevier. com website), one can make articles of any conceivable shape and appearance using polyamide compositions of the present disclosure.

Various aspects of the present invention provide a method of making an embodiment of the flame-retardant polyamide composition described herein. The method can be any suitable method that provides the flame-retardant polyamide composition. For example, the method can include combining the polyamide that is about <NUM> wt% to about <NUM> wt% of the composition, the polyamide having a relative viscosity (RV) of ≥<NUM> to <<NUM>, with the one or more flame-retardant additives, to form the flame-retardant polyamide composition.

In various aspects, the polyamide resin, such as nylon <NUM>, may be melt-kneaded with the pre-determined amount of glass fibers and other additives using industrial compounding or extrusion equipment. For example, the polyamide resin may be supplied to the feed port of the compounding machine and glass fibers may be introduced either at the feed port, at the side feeder port, or some combination of the two. Compounding conditions may be properly set in terms of the desired temperature range, extrusion pressure, extrusion time, screw speed, etc. to obtain homogenized melt at the discharge port. The compounded glass fiber-reinforced polymer strands immediately after compounding may follow pelletization in the suitable pelletizer with water cooling. The obtained pellets may be useful for further industrial processes, such as injection molding, for making parts and other articles of interest.

In various aspects, the method includes compounding the polyamide with the flame-retardant additive or another additive. In some examples, the method can include using a twin-screw extruder, such as a Coperion ZSK <NUM> MEGAlab including two conveying screws, having <NUM>-mm diameter with a <NUM>/D (i.e., LID ratio of <NUM>), co-rotating and turning at a suitable speed, such as <NUM> RPM. The barrel can be heated along its length in zones at temperatures, typically <NUM>-<NUM> may be used for Nylon <NUM> to melt the polymer. The processing section of the Coperion twin screw compounder ZSK <NUM> MEGAlab can be set up to suit various process needs and to allow a wide variety of processes, such as compounding processes. Polymer, fillers and additives, as desired, can be continuously fed into the first barrel section of the twin screw using a metering feeder. The materials can be conveyed along the screw and get melted and mixed by kneading elements in the plastification section of the barrel. The polyamide composition can then travel along to a side port where, if desired, fillers, such as but not limited to glass fibers, may be added. The polyamide composition can then pass onto degassing zones, and from there to a pressure build zone where it can then exit the die via a hole (e.g., <NUM>-mm diameter) as a lace. The cast lace can feed into a water bath to cool and to enable it to be cut into chips via a pelletizer.

The method can include forming molded shapes. The method can include using an injection molding machine (e.g., Demag Sumitomo Sytec <NUM>/<NUM>) which can include a feed throat, such as a single rotating screw in a temperature zoned barrel, where zones may typically range from <NUM> to <NUM> to melt a Nylon <NUM>-based resin, and where the screw may move within the barrel to inject a volume of molten resin into a mold, where the mold is typically at <NUM>-<NUM> for a Nylon <NUM> based resin. The mold can yield solid parts or specimens, which can include those suitable for testing, such as flammability bars of desired dimensions.

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

The term "RV", used herein in the Examples, refers to relative viscosity of a polymer sample as measured (unless otherwise indicated) in an <NUM> wt. % solution in <NUM>% formic acid.

As used herein, the glass fibers were standard short glass fibers, for example, commercially available product, chopped strand for PA, from Chongqing Polycomp International Corp. cppicfiber. com), which was E-glass chopped strand grade 301HP having <NUM>-mm chopped length and <NUM>-µm filament diameter. In the present disclosure, the term "glass fiber" is abbreviated as "GF" which is understood to be a standard nomenclature in the polymer and compounding industry. The amount of GF in the polymer sample is represented as wt. % of the total, unless stated otherwise. Parts of a composition are given in parts by weight, unless otherwise indicated.

As used herein, Melapur™ MC25 is a commercially available halogen-free flame-retardant additive from BASF. The active flame-retardant additive, melamine cyanurate (<NPL>), has <NUM>% of particles less than <NUM>.

As used herein, Irganox® B1171, a commercial polymer additive product of BASF, is a blend of hindered phenolic antioxidant (<NPL>) and a phosphite (<NPL>) for processing and long-term thermal stabilization.

As used herein, Mastertek® <NUM> is a <NUM> wt% masterbatch of melamine cyanurate (<NPL>) in Nylon <NUM> (or N6) available from Campine NV.

As used herein, Exolit® OP <NUM> is a commercially available non-halogenated flame-retardant additive based on organic phosphinates (aluminum diethylphosphinate; <NPL>) and a synergist (zinc borate; <NPL>) from Clariant. As used herein, Exolit® OP <NUM> is a commercially available flame-retardant additive that is aluminum diethylphosphinate (<NPL>) and is produced by Clariant.

As used herein, Preniphor™ EPFR-MPP300 is a commercially available, halogen-free, melamine polyphosphate (<NPL>) flame-retardant additive from Presafer (Quingyuan) Phosphor Chemical Co.

As used herein, SAYTEX® HP <NUM> (<NPL>) is a commercially available class of bromine-based flame-retardant additives from Albemarle.

As used herein, Campine PA <NUM> is a <NUM> wt% masterbatch of antimony trioxide (<NPL>) in Nylon <NUM> (N6). It is a commercially available product from Campine NV.

As used herein, Firebrake® <NUM> is a commercially available, dehydrated zinc borate (<NPL>)-based flame-retardant from Borax Europe Ltd.

Compounds were made on a Berstorff ZE <NUM> AX 40D-UTX twin screw extruder with <NUM> screws. Typical setpoint conditions were: Feed zone <NUM><NUM>; Zone <NUM><NUM>; Zone <NUM><NUM>; Zone <NUM><NUM>; Zone <NUM><NUM>; Zone <NUM><NUM>; Zone <NUM><NUM>; Zone <NUM><NUM>; Die <NUM>; Vacuum <NUM> mbar; throughput <NUM>/hr. Further conditions are given in tables of experimental results.

Injection molding of tensile and impact bars were conducted on an Arburg 420A-<NUM>-<NUM>, screw size <NUM>. Further conditions are given in tables of experimental results.

Injection molding of flammability bars were conducted on an Arburg 370C-<NUM>-<NUM>, screw size <NUM>. Further conditions are given in tables of experimental results. Tensile Properties were determined as per DIN EN ISO <NUM>/<NUM>. Impact Properties were determined as per ISO <NUM>:<NUM>. Flammability Properties were determined as per UL <NUM> V.

Using the general procedures described herein, the following flame-retardant polyamide compositions were made from <NUM>, <NUM>, and <NUM> RV N66 feedstock polyamides. For each of these specimens, the compositions contained <NUM> parts feedstock polyamide, <NUM> parts Melapur™ MC25 flame-retardant additive, and <NUM> parts Irganox® B1171 polymer additive.

Each specimen was molded into the appropriate flammability or mechanical tests bars and the flammability rating and mechanical properties determined.

Comparing Examples <NUM> and <NUM> with Example <NUM> demonstrates the advantages of improved ease of processing using the <NUM> RV feedstock polymer as evidenced by the reduced % maximum torque and reduced Nozzle Pressure at the same screw speed of <NUM> RPM.

Comparing Examples <NUM> and <NUM> with Example <NUM> demonstrates the advantages of improved ease of processing using the <NUM> RV feedstock polymer as evidenced by the reduced filling pressures, and reduced cycle times.

Comparing Examples <NUM> and <NUM> with Example <NUM> demonstrates the comparable flammability performances.

Comparing Examples <NUM> and <NUM> with Example <NUM> demonstrates that though some of the mechanical properties are reduced they are still acceptable, and that some properties are improved.

Overall, comparing Examples <NUM>-<NUM> to Example <NUM> demonstrates the improved ease of processing from using the <NUM> RV feedstock polymer whilst maintaining flammability properties together with useful mechanical properties. Should flammability properties not meet the desired performance, the improved ease of processing widens the processing window to one skilled in the art to allow them to add further flame-retardant additives to meet the balance of acceptable processing, flammability, and mechanical performance desired.

Comparing Examples <NUM>, 5a and 5b with Example <NUM> demonstrates the advantages of improved ease of processing using the <NUM> RV feedstock polymer as evidenced by the reduced % maximum torque and reduced nozzle pressure. Example <NUM> was run at two screw speeds in Example 5a and Example 5b) and pellet bridging problems were countered at the higher speed.

Comparing Examples <NUM>, 5a, and 5b with Example <NUM> demonstrates the advantages of improved ease of processing using the <NUM> RV feedstock polymer as evidenced by the reduced filling pressures, and/or the generally reduced cycle times.

Comparing Examples <NUM>, 5a, and 5b with Example <NUM> demonstrates the comparable flammability performances.

Comparing Examples <NUM> and 5b with Example <NUM> demonstrates that though some of the mechanical properties are reduced they are still acceptable, and that some properties are improved.

Overall, comparing Examples <NUM>, 5a, 5b, and <NUM> demonstrates the improved ease of processing from using the <NUM> RV feedstock polymer at both compounding and molding whilst maintaining flammability properties together with useful mechanical properties, indeed some properties are improved. Should flammability properties not meet the desired performance, the improved ease of processing widens the processing window to one skilled in the art to allow them to add further flame-retardant additives to meet the balance of acceptable processing, flammability and mechanical performance required.

Using the general procedures described herein, the following flame-retardant polyamide compositions were made from <NUM>, <NUM>, and <NUM> RV N66 feedstock polyamides. The test compositions contained <NUM> parts of <NUM> RV N66 polyamide, <NUM> parts of Mastertek® <NUM> flame-retardant additive masterbatch, and <NUM> parts Irganox® B1171 polymer additive.

Each specimen was molded into the appropriate flammability or mechanical tests bars and the flammability rating and mechanical properties were determined.

Comparing Examples <NUM> and <NUM> with Example <NUM> demonstrates the advantages of improved ease of processing using the <NUM> RV feedstock polymer as evidenced by the reduced % maximum torque and reduced nozzle pressure.

Comparing Examples <NUM> and <NUM> with Example <NUM> demonstrates the advantages of improved ease of processing using the <NUM> RV feedstock polymer as evidenced by the reduced filling pressures, and/or the generally reduced cycle times.

Comparing Examples <NUM> and <NUM> with Example <NUM> demonstrates the comparable flammability performances. Improvement was observed with the <NUM> RV feedstock resin formulation as evidenced by the V-<NUM> rating as compared to the V-<NUM> ratings of the higher viscosity feedstock resin formulations.

Overall, comparing Examples <NUM>, and <NUM> to Example <NUM> demonstrates the improved ease of processing from using the <NUM> RV feedstock polymer at both compounding and molding whilst maintaining flammability properties together with useful mechanical properties, indeed some properties are improved. Should flammability properties not meet the desired performance, the improved ease of processing widens the processing window to one skilled in the art to allow them to add further flame-retardant additives to meet the balance of acceptable processing, flammability and mechanical performance required.

Using the general procedures described herein, the following flame-retardant polyamide compositions were made from <NUM>, <NUM>, and <NUM> RV N66 feedstock polyamides. The test compositions contained <NUM> parts of <NUM> RV N66 polyamide, <NUM> parts of glass fiber, <NUM> parts of Exolit® OP <NUM> flame-retardant additive, and <NUM> parts Irganox® B1171 polymer additive.

Comparing Examples <NUM> and <NUM> with Example <NUM> demonstrates the advantages of improved ease of processing using the <NUM> RV feedstock polymer as evidenced by the reduced Filling Pressures, and/or generally reduced cycle times.

Overall, comparing Examples <NUM>, <NUM>, and <NUM> demonstrates the improved ease of processing from using the <NUM> RV feedstock polymer at both compounding and molding whilst maintaining flammability properties together with useful mechanical properties, indeed some properties are improved. Should flammability properties not meet the desired performance, the improved ease of processing widens the processing window to one skilled in the art to allow them to add further flame-retardant additives to meet the balance of acceptable processing, flammability and mechanical performance required.

Using the general procedures described herein, the following flame-retardant polyamide compositions were made from <NUM>, <NUM>, and <NUM> RV N66 feedstock polyamides. The test compositions contained <NUM> parts of <NUM> RV N66 polyamide, <NUM> parts of glass fiber, <NUM> parts of Exolit® OP <NUM> flame-retardant additive, <NUM> parts Prenifor™ EPFR-MPP300 flame-retardant additive, and <NUM> parts Irganox® B1171 polymer additive.

Comparing Examples <NUM> and <NUM> with Example <NUM> demonstrates the advantages of improved ease of processing using the <NUM> RV feedstock polymer as evidenced by the reduced % maximum torque and reduced Nozzle Pressure.

Comparing Examples <NUM> and <NUM> with Example <NUM> demonstrates the advantages of improved ease of processing using the <NUM> RV feedstock polymer as evidenced by the generally reduced Filling Pressures and/or cycle times.

Comparing Examples <NUM> and <NUM> with Example <NUM> demonstrates the comparable Flammability performances. Indeed, in some instances an improvement in the flammability rating.

Overall, comparing Examples <NUM>, <NUM>, and <NUM> demonstrates the improved ease of processing from using the <NUM> RV feedstock polymer at both compounding and molding whilst maintaining flammability properties together with useful mechanical properties, indeed some properties are improved. Should flammability properties not meet the desired performance, the improved ease of processing widens the processing window to one skilled in the art to allow them to add further flame-retardant additives to meet the balance of acceptable processing, flammability, and mechanical performance required.

Using the general procedures described herein, the following flame-retardant polyamide compositions were made from <NUM>, <NUM>, and <NUM> RV N66 feedstock polyamides. The test compositions contained <NUM> parts of <NUM> RV N66 polyamide, <NUM> parts of glass fiber, <NUM> parts of SAYTEX® HP <NUM> bromine-based flame-retardant additive, <NUM> parts of Campine PA <NUM> antinomy-based flame-retardant additive, <NUM> parts of Firebrake® <NUM> zinc borate-based fire retardant additive, and <NUM> parts of Irganox® B1171 polymer additive.

Comparing Examples <NUM> and <NUM> with Examples <NUM> and <NUM> demonstrates the advantages of improved ease of processing using the <NUM> RV and <NUM> RV feedstock polymers as evidenced by the reduced % maximum torque and reduced nozzle pressure.

Comparing Examples <NUM> and <NUM> with Examples <NUM> and <NUM> demonstrates the advantages of improved ease of processing using the <NUM> RV and <NUM> RV feedstock polymers as evidenced by the generally reduced filling pressures and/or cycle times.

Comparing Examples <NUM> and <NUM> with Examples <NUM> and <NUM> demonstrates the comparable flammability performances.

Comparing Examples <NUM> and <NUM> with Examples <NUM> and <NUM> demonstrates that though some of the mechanical properties are reduced they are still acceptable, and that some properties are improved.

Overall, comparing Examples <NUM> and <NUM> to Examples <NUM> and <NUM> demonstrates the improved ease of processing from using the <NUM> RV or <NUM> RV feedstock polymers at both compounding and molding whilst maintaining useful mechanical properties and while improving some properties. Should flammability properties not meet the desired performance, the improved ease of processing widens the processing window to one skilled in the art to allow them to add further flame-retardant additives to meet the balance of acceptable processing, flammability, and mechanical performance required.

Using the general procedures described herein, the following flame-retardant polyamide compositions were made from <NUM>, <NUM>, and <NUM> RV N66 feedstock polyamides. The test compositions contained <NUM> parts of <NUM> RV N66 polyamide, <NUM> parts of glass fiber, <NUM> parts of Exolit® OP <NUM> flame-retardant additive, <NUM> parts of Prenifor™ EPFR-MPP300 flame-retardant additive, and <NUM> parts of Irganox® B1171 polymer additive.

Comparing Examples <NUM> and <NUM> with Example <NUM> demonstrates the advantages of improved ease of processing using the <NUM> RV feedstock polymer as evidenced by the reduced % maximum torque and reduced nozzle Pressure.

Comparing Examples <NUM> and <NUM> with Example <NUM> demonstrates the advantages of improved ease of processing using the <NUM> RV feedstock polymer as evidenced by the generally reduced filling pressures and/or cycle times.

Comparing Examples <NUM> and <NUM> with Example <NUM> demonstrates the comparable Flammability performances.

Comparing Examples <NUM> and <NUM> with Example <NUM> demonstrates that the mechanical properties are still acceptable, and that some properties are improved.

Overall, comparing Examples <NUM> and <NUM> to Example <NUM> demonstrates the improved ease of processing from using the <NUM> RV feedstock polymer at both compounding and molding whilst maintaining useful mechanical properties, while some properties are improved. Should flammability properties not meet the desired performance, the improved ease of processing widens the processing window to one skilled in the art to allow them to add further flame-retardant additives to meet the balance of acceptable processing, flammability and mechanical performance required.

In this Example, fibers are melt-spun using N66 polyamide having various RVs and including various amounts of Exolit® OP <NUM> flame-retardant additive in a range of <NUM>-<NUM> wt%, along with <NUM> wt% Irganox® B1171 polymer additive. No glass fibers were present in the compositions. For the filled N66 resin prepared, the RVs tested are <NUM> RV, <NUM> RV, <NUM> RV, and <NUM> RV. The fibers are drawn to obtain round cross-section continuous filament that was <NUM> denier per filament (dpf).

Breaking strength measurements are conducted on continuous multi-filament fibers according to ASTM D885 - Standard Test Methods for Tire Cords, Tire Cord Fabrics, and Industrial Filament Yarns Made from Manufactured Organic-Base Fibers. The flame resistance performance testing was performed using ASTM D6413 - Standard Test Method for Flame Resistance of Textiles (Vertical Test). Woven fabric specimens are prepared from <NUM>" staple spun yarns containing <NUM> wt. % nylon-<NUM>,<NUM>-based fiber (RV values in Table <NUM>) and <NUM> wt. % flame-retardant rayon (commercially available from Lenzing FR; Lenzing Group, Lenzing, Austria). The tested woven fabric specimens have <NUM> oz/yd<NUM> twill weave.

Table <NUM> lists the fiber mechanical strength (or breaking strength) along with the flame resistance data for drawn fibers from the N66 polyamide resins having varying RVs and flame-retardant additive levels.

In these Examples, fibers were melt-spun using N66 polyamide having various RVs and including various amounts of Exolit® OP <NUM> flame-retardant additive in a range of <NUM>-<NUM> wt%. No glass fibers were present in the compositions. For the filled N66 resin prepared, the RVs tested were <NUM> RV, <NUM> RV, and <NUM> RV. The fibers were drawn to obtain round cross-section continuous filament that was <NUM> denier per filament (dpf).

Breaking strength measurements were conducted on continuous multi-filament fibers according to ASTM D885 - Standard Test Methods for Tire Cords, Tire Cord Fabrics, and Industrial Filament Yarns Made from Manufactured Organic-Base Fibers.

Table <NUM> lists the fiber mechanical strength (or breaking strength) along with the pack pressure data for drawn fibers from the N66 polyamide resins having varying RVs and flame-retardant additive levels.

Claim 1:
A flame-retardant polyamide composition comprising:
apolyamide that is <NUM> wt%to <NUM> wt% of the composition, the polyamide having a relative viscosity (RV) of ≥<NUM> to ≤<NUM> as measured as an <NUM> wt% solution in <NUM>% formic acid, wherein the polyamide is nylon <NUM>; and
one or more flame-retardant additives;
wherein the flame-retardant polyamide composition is substantially free of poly(arylene ether) and non-polyamide copolymers thereof, and the composition has aflame retardancy rating at <NUM> of V-<NUM>, V-<NUM>, or V-<NUM> as measured by Underwriters' Laboratories Test No. UL <NUM>, wherein the one or more flame-retardant additives are halogen-containing flame-retardant additives, halogen-containing flame-retardant additives with synergists, phosphorus-containing flame-retardant additives, inorganic flame-retardant additives, nitrogen-containing flame-retardant additives, nitrogen-containing flame-retardant additives with synergists, or a combination thereof, wherein the nitrogen-containing flame-retardant additives are selected from melamine cyanurate, melamine polyphosphate, melamine pyrophosphate, or mixtures thereof.