EP4649108A1 - Flame retardant composition and methods thereof - Google Patents

Abstract

A flame retardant composition for wire insulation and jacket includes a polymer comprising a cross-linked polyolefin, and a halogen-free fire retardant composition comprising a first fire retardant selected from the group consisting of aluminum dialkyl phosphinates (ADPs), and/or a second fire retardant selected from the group consisting of melamine cyanurate (MC), melamine phosphate (MP), and melamine polyphosphate (MPP) and a functional filler selected from the group consisting of clays, talc and combinations thereof. The composition can easily be processed to make wire and cable insulation exhibiting a balance of properties needed by the UL44 standard including the horizontal flame rating of FT-2, the burning particles, the long-term insulation resistance (LTIR), in addition to good mechanical property.

Description

FLAME RETARDANT COMPOSITION AND METHODS THEREOF

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to and the benefit of U.S. Provisional Application No. 63/437,773, filed on January 9, 2023, which is incorporated herein by reference in its entirety.

FIELD

[0002] The present technology is generally related to halogen-free flame retardant compositions and methods of making and using those compositions.

BACKGROUND

[0003] Fire is a major concern to the wire and cable industry; the burning cables will lead to substantial damage in different ways. This serious concern is reflected in the stringent fire safety requirements needed by the wire and cable codes and standards.

[0004] Given the serious fire risk posed by the wire and cable, there is a need to impart flame retardancy to these materials. The most common method to reduce the flammability of polymeric materials is by incorporating flame-retardant additives.

[0005] In North America, the current trend is to use halogenated flame retardant compositions based upon halogens such as bromine coupled with antimony synergist to obtain a suitable flame rating. However, due to environmental concern regarding the use of halogenated materials, there is a need to look for alternative halogen-free flame- retardant system.

[0006] An alternate approach is to use non-halogen flame retardant compositions based upon hydrated fillers such as aluminum trihydrate and magnesium hydroxide. However, a high loading of these hydrated fillers must be used in the flame retardant composition to obtain a suitable flame rating. This high loading compromises other properties of the materials such as, for example, mechanical properties.

[0007] Therefore, there is a need for a flame retardant composition that avoids these problems. SUMMARY

[0008] In one aspect, a flame retardant composition for wire insulation comprises a polymer comprising a cross-linked polyolefin, and a halogen-free fire retardant composition comprising a first fire retardant selected from the group consisting of aluminum dialkyl phosphinates (ADPs), and/or a second fire retardant selected from the group consisting of melamine cyanurate (MC), melamine phosphate (MP), and melamine polyphosphate (MPP) and a functional filler selected from the group consisting of clays, talc, and combinations thereof. The flame retardant composition exhibits a horizontal flame rating of FT-2 as determined pursuant to UL44, Section 5.14 and/or UL2556, Section 9.1. A structural representation of MC is shown here:

[0009] In an embodiment, the first fire retardant comprises aluminum diethyl phosphinate (DEPAL). A structural representation of DEPAL is shown here:

[0010] In an embodiment, the first fire retardant is present at greater than 0 wt.% to about 8 wt.%. In an embodiment, the first fire retardant comprises aluminum diethyl phosphinate (DEPAL) at greater than 0 wt.% to about 5 wt.%.

[0011] In an embodiment, the functional filler comprises kaolin clay and talc. [0012] In an embodiment, the functional filler is present at greater than 0 wt.% to about 6 wt.%. In an embodiment, the functional filler comprises kaolin clay at greater than 0 wt.% to about 6 wt.% and talc at greater than 0 wt.% to about 6 wt.%. In an embodiment, the functional filler is kaolin clay at about 2 wt.% and talc at about 2 wt.%.

[0013] In an embodiment, the polymer comprises a cross-linked polyethylene. In an embodiment, the polymer comprises a silane-cross-linked polyethylene.

[0014] In an embodiment, the polymer is present in an amount to make up the balance of the composition.

[0015] In an embodiment, the first fire retardant comprises aluminum diethyl phosphinate (DEPAL) from about 3 wt.% to about 8 wt.%, the functional filler comprises kaolin clay from about 0 wt.% to about 6 wt.% and talc from about 0 wt.% to about 6 wt.%, and the polymer comprises a cross-linked polyethylene at greater than 82 wt.%.

[0016] In an embodiment, the second flame retardant comprises melamine cyanurate (MC).

[0017] In an embodiment, the second fire retardant comprises melamine cyanurate (MC) from about 2 wt.% to about 6 wt.%.

[0018] In an embodiment, the first fire retardant comprises aluminum diethyl phosphinate (DEPAL) from about 3 wt.% to about 8 wt.%, the second fire retardant comprises melamine cyanurate (MC) from about 2 wt.% to about 6 wt.%, and the polymer is a cross-linked polyethylene in an amount to make up the balance of the composition.

[0019] In an embodiment, the first fire retardant comprises aluminum diethyl phosphinate (DEPAL) from about 3 wt.% to about 8 wt.%, the second fire retardant comprises melamine cyanurate (MC) from about 2 wt.% to about 6 wt.%, and the functional filler comprises kaolin clay at greater than 0 wt.% to about 6 wt.% and talc at greater than 0 wt.% to about 6 wt.%; and the polymer comprises a cross-linked polyethylene at greater than 82 wt.%.

[0020] In an embodiment, the flame retardant composition further comprises an additive selected from the group consisting of anti-oxidants, processing aids, UV stabilizers, and combinations thereof. [0021] In another aspect, a wire insulation comprises a first fire retardant selected from the group consisting of aluminum dialkyl phosphinates (ADPs), a second fire retardant selected from the group consisting of melamine cyanurate (MC), melamine phosphate (MP) and melamine polyphosphate (MPP) and/or a functional filler selected from the group consisting of clays, talc, and combinations thereof, and a polymer selected from the group consisting of cross-linked polyolefins and cross-linked thermoplastic polyolefins.

[0022] In an embodiment, the first fire retardant comprises aluminum diethyl phosphinate (DEPAL) from about 3 wt.% to about 8 wt.%, and the functional filler comprises kaolin clay at greater than 0 wt.% to about 6 wt.% and talc at greater than 0 wt.% to about 6 wt.%.

[0023] In an embodiment, the first fire retardant comprises aluminum diethyl phosphinate (DEPAL) from about 3 wt.% to about 8 wt.%, and the second fire retardant comprises melamine cyanurate (MC) from about 2 wt.% to about 6 wt.%.

[0024] In an embodiment, the first fire retardant comprises aluminum diethyl phosphinate (DEPAL) from about 3 wt.% to about 8 wt.%, the second fire retardant comprises melamine cyanurate (MC) from about 2 wt.% to about 6 wt.%, and the functional filler comprises kaolin clay at greater than 0 wt.% to about 6 wt.% and talc at greater than 0 wt.% to about 6 wt.%.

[0025] In yet another aspect, a method of making a fire retardant composition for wire insulation comprises a-i) adding a first fire retardant selected from the group consisting of aluminum dialkyl phosphinates (ADPs) and a-ii) a second fire retardant selected from the group consisting of melamine cyanurate (MC), melamine phosphate (MP) and melamine polyphosphate (MPP) and/or a functional filler selected from the group consisting of clays, talc, and combinations thereof to an un-grafted polymer selected from the group consisting of un-grafted polyolefins, un-grafted thermoplastic polyolefins, and combinations thereof to form a first mixture.

[0026] In an embodiment, step a) further comprises adding additives selected from the group consisting of anti-oxidants, colorants, processing aids, UV stabilizers, and combinations thereof to the first mixture. [0027] In an embodiment, the method further comprises b) compounding a silane- grafted polymer selected from the group consisting of silane-grafted polyolefins, silane- grafted thermoplastic polyolefins, and combinations thereof with the first mixture by initiating the crosslinking reaction using a catalyst to promote the crosslinking reaction to form the fire retardant composition.

[0028] In an embodiment, step b) comprises b-i) compounding the silane-grafted polymer selected from the group consisting of silane-grafted polyolefins, silane-grafted thermoplastic polyolefins, and combinations thereof with the first mixture; and b-ii) followed by initiating the crosslinking reaction using the catalyst to promote the crosslinking reaction to form the fire retardant composition.

[0029] In an embodiment, step b) further comprises using an extrusion compounding technique to compound the silane-grafted polymer.

[0030] In still another aspect, a method of making wire insulation comprises extruding the fire retardant composition as disclosed herein to form the wire insulation.

[0031] In still yet another aspect, an article of manufacture comprises a wire at least partially enclosed by wire insulation. The wire insulation comprises a cross-linked polyolefin and a halogen-free fire retardant composition. The halogen-free fire retardant composition comprises a first fire retardant, a second fire retardant, and a function filler. The first fire retardant comprises an aluminum dialkyl phosphinate (ADPs). The second fire retardant comprises melamine cyanurate (MC), melamine phosphate (MP), or melamine polyphosphate (MPP). The functional filler comprises a clay or talc. The wire insulation exhibits a horizontal flame rating of FT-2 as determined pursuant to UL44, Section 5.14 and/or UL2556, Section 9.1.

[0032] In an embodiment, the first fire retardant comprises aluminum diethyl phosphinate (DEPAL) from about 3 wt.% to about 8 wt.%. in an embodiment, the functional filler comprises kaolin clay at greater than 0 wt.% to about 6 wt.% and talc at greater than 0 wt.% to about 6 wt.%.

[0033] In an embodiment, the first fire retardant comprises aluminum diethyl phosphinate (DEPAL) from about 3 wt.% to about 8 wt.%. In an embodiment, the second fire retardant comprises melamine cyanurate (MC) from about 2 wt.% to about 6 wt.%. [0034] In an embodiment, the first fire retardant comprises aluminum diethyl phosphinate (DEPAL) from about 3 wt.% to about 8 wt.%. In an embodiment, the second fire retardant comprises melamine cyanurate (MC) from about 2 wt.% to about 6 wt.%. In an embodiment, the functional filler comprises kaolin clay at greater than 0 wt.% to about 6 wt.% and talc at greater than 0 wt.% to about 6 wt.%.

[0035] These and other objects, features and advantages will become apparent as reference is made to the following detailed description, preferred embodiments, and examples, given for the purpose of disclosure, and taken in conjunction with the accompanying drawings and appended claims.

DETAILED DESCRIPTION

[0036] Various embodiments are described hereinafter. It should be noted that the specific embodiments are not intended as an exhaustive description or as a limitation to the broader aspects discussed herein. One aspect described in conjunction with a particular embodiment is not necessarily limited to that embodiment and can be practiced with any other embodiment s).

[0037] As utilized herein with respect to numerical ranges, the terms “approximately,” “about,” “substantially,” and similar terms will be understood by persons of ordinary skill in the art and will vary to some extent depending upon the context in which it is used. If there are uses of the terms that are not clear to persons of ordinary skill in the art, given the context in which it is used, the terms will be plus or minus 10% of the disclosed values. When “approximately,” “about,” “substantially,” and similar terms are applied to a structural feature (e.g., to describe its shape, size, orientation, direction, etc.), these terms are meant to cover minor variations in structure that may result from, for example, the manufacturing or assembly process and are intended to have a broad meaning in harmony with the common and accepted usage by those of ordinary skill in the art to which the subject matter of this disclosure pertains. Accordingly, these terms should be interpreted as indicating that insubstantial or inconsequential modifications or alterations of the subject matter described and claimed are considered to be within the scope of the disclosure as recited in the appended claims. [0038] The use of the terms “a” and “an” and “the” and similar referents in the context of describing the elements (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to better illuminate the embodiments and does not pose a limitation on the scope of the claims unless otherwise stated. No language in the specification should be construed as indicating any non-claimed element as essential.

[0039] Flame retardant compositions for wire insulation are disclosed herein. The flame retardant compositions include a polymer comprising a cross-linked polyolefin and a halogen-free fire retardant composition. The halogen-free fire retardant composition comprises a first fire retardant that includes an aluminum dialkyl phosphinates (ADPs), optionally a second fire retardant that includes melamine cyanurate (MC), melamine phosphate (MP), melamine polyphosphate (MPP), or a mixture of any two or more thereof, and a functional filler that may include a clay, talc, or a combination of any two or more thereof. The flame retardant compositions exhibit a horizontal flame rating of FT-2 as determined pursuant to UL44, Section 5.14 and/or UL2556, Section 9.1. By “halogen-free” it is intended that no halogen is intentionally added to the composition, but some halogen may be carried into the composition from chemical reactant sources and the like. Halogen- free is meant to indicate less than 0.1 wt% halogen (i.e., F, Cl, Br, or I) is included in the composition. In some embodiments, halogen-free means 0 wt% halogen is included.

[0040] Methods for making and using the novel flame retardant composition are also disclosed.

Flame Retardant Composition

[0041] In one aspect, a flame retardant composition for wire insulation includes a polymer composition that includes a cross-linked polyolefin, and a halogen-free fire retardant composition. The halogen-free fire retardant composition includes a first fire retardant that is an aluminum dialkyl phosphinate, and, optionally, a second fire retardant that includes melamine cyanurate (MC), melamine phosphate (MP), melamine polyphosphate (MPP), or a mixture of any two or more thereof, and a functional filler that may include a clay, talc, and combinations of any two or more thereof. See e.g., Table 1.

[0042] The flame retardant compositions exhibit a horizontal flame rating (i.e., FT- 2) as determined pursuant to UL44, Section 5.14 and/or UL2556, Section 9.1 (i.e., passes a horizontal flame test).

[0043] Pursuant to UL 44, Section 5.14.1,

A finished wire or cable of any construction shall not convey flame along its length or to combustible materials in its vicinity when a specimen is subjected to the test, FT2/FH/Horizontal flame, in UL 2556, CSA C22.s No. 2556, or NMX-J-192-ANCE. The total length of char on the specimen shall not exceed 100 mm (4 in), and the dripping particles emitted from the specimen during or after the application of flame shall not ignite the cotton on the floor of the enclosure, on the base of the burner, or on the wedge. Flameless charring of the cotton shall be ignored. . . .

[0044] See also UL 2556, Section 9.1. Pursuant to UL 44, Section 5.14.2,

XL insulation shall be such that when a specimen of single-conductor wire or cable without a covering or jacket is subjected to the test, Burning particles (dropping), in UL 2556, CSA C22.2 No. 2556, or NMX-J-556-ANCE, burning particles from the specimen shall not cause the newsprint to ignite (flame). The specimen shall be tested after allowing at least 3 weeks after manufacture. Earlier testing by the manufacturer is optional.

See also UL 2556, Section 9.2.

Table 1.

First Flame Retardant

[0045] In an embodiment, the first fire retardant may be an aluminum dialkyl phosphinate (ADPs), or a mixture of any two or more thereof. In an embodiment, the first fire retardant may be any suitable aluminum dialkyl phosphinate. Suitable aluminum dialkyl phosphinates include, but are not limited to, aluminum diethyl phosphinate (DEPAL). In one embodiment, the first fire retardant comprises aluminum diethyl phosphinate (DEPAL).

[0046] The first fire retardant may be present from greater than 0 wt.% to about 8 wt.%, and any range or value there between. This may include where the first fire retardant may be present at greater than 0 wt.% to about 5 wt.%, at about 3 wt.% to about 8 wt.%, at about 7 wt.%, or at about 4 wt.%.

Second Flame Retardant

[0047] The second fire retardant may be a melamine cyanurate (MC), melamine phosphate (MP), melamine polyphosphate (MPP), or a mixture of any two or more thereof. In some embodiments, the second fire retardant may be melamine cyanurate (MC). In other embodiments, the second fire retardant may be melamine phosphate (MP). In further embodiments, the second fire retardant may be melamine polyphosphate (MPP).

[0048] The second fire retardant may be present from 0 wt.% to about 6 wt.%, and any range or value there between. This may include where the second flame retardant may be present from greater than 0 wt.% to about 6 wt.%. This may include where the second flame retardant may be present from about 2 wt.% to about 6 wt.%, or about 3 wt.%.

Functional Filler

[0049] The functional filler may be a clay, talc, and or mixture of any two or more thereof. In some embodiments, the clay may be selected from any suitable clay. Suitable clays may include, but are not limited to, ball clay, china clay, and/or kaolin clay. In some embodiment, the functional filler may be a mixture of kaolin clay and talc. In other embodiment, the functional filler may be kaolin clay. In further embodiments, the functional filler may be talc.

[0050] The functional filler may be present from about 0 wt.% to about 6 wt.%, and any range or value there between. This may include from about 0 wt.% to about 4 wt.%, about 2 wt. % to about 6 wt.%, or at about 4 wt.%. This may also include from greater than 0 wt.% to about 4 wt.%.

Optional Additives

[0051] The flame retardant compositions may also include other additives such as anti-oxidants, colorants, processing aids, UV stabilizers, and combinations of any two or more thereof.

[0052] In some embodiments, the anti-oxidant may be any suitable anti-oxidant(s) to inhibit oxidation of the polymer from atmospheric oxygen and/or to inhibit degradation of the polymer from thermo-mechanical or thermo-oxidative conditions. Illustrative antioxidants include, but are not limited to, phenolic antioxidants such as Irganox® 1035

(2-[2-[3-(3,5-dite/T-butyl-4-hydroxyphenyl)propanoyloxy]ethylsulfanyl]ethyl 3-(3,5-di/c77- butyl-4-hydroxyphenyl)propanoate), Irganox® MD1024 (3-(3,5-dite/7-butyl-4- hydroxyphenyl)-A'-[3-(3,5-diter/-butyl-4-hydroxyphenyl)propanoyl]propanehydrazide), and Ethanox™ 330 (l,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl) benzene; phosphite antioxidants such as Irgafos® 168 (tris(2,4-di-tert-butylphenyl)phosphite); and thiosynergist antioxidants such as Songnox® DSTDP (distearyl thiodipropionate). [0053] In some embodiments, the colorant, may be any suitable colorant(s) to provide a color to the polymer. Illustrative colorant materials include, but are not limited to, iron oxides such as Red 101 and carbon black, such as Black 7

[0054] In some embodiments, the processing aid may be any suitable processing aid(s) to improve the processability and processing characteristics of the polymer. For example, a suitable processing aid includes, but is not limited to, lubricants, and combinations thereof. In an embodiment, the lubricant may be a high molecular weight silicone, an ultra-high molecular weight silicone, and combinations thereof. Illustrative processing aids include, but are not limited to, zinc stearate, calcium stearate, and fluoroelastomers, such as Dynamar™ FX5920A.

[0055] In some embodiments, the UV stabilizer may be any suitable UV stabilizer to inhibit degradation of the polymer from UV radiation. For example, a suitable UV stabilizer includes, but is not limited to, a UV protector, a light stabilizer, and combinations thereof. Illustrative UV stabilizers include, but are not limited to, materials such as benzophenones such as Cyasorb® UV 531 ([2-hydroxy-4- (octyloxy)phenyl]phenylmethanone), benzotriazoles such as Tinuvin® 326 (2-(2 '-Hydroxy - 3'-tert-butyl-5'-methylphenyl)-5-chlorobenzortriazole), and hindered amine light stabilizers (HALS) such as Chimassorb® 944 (poly-{6-[(l,l,3,3-tetramethylbutyl)amino-l,3,5- triazine-2, 4-diyl][(2, 2,6, 6-tetramethyl-4-piperidyl)imino]-l,6-hexanediyl[(2, 2,6,6- tetramethyl-4-piperidyl)imino)}).

Polymers

[0056] The polymer may be a cross-linked polyolefin, a silane-cross-linked polyolefin, or a combination of any two or more thereof. Illustrative cross-linked polyolefins include, but are not limited to, cross-linked polyethylene (LLDPE, LDPE, HDPE or blends thereof), cross-linked polypropylene, cross-linked polybutylene, crosslinked polypentene, cross-linked polyhexene, cross-linked polyheptene, cross-linked polyoctene, and combinations of any two or more thereof.

[0057] In some embodiments, the polymer includes a silane-cross-linked polyethylene. Illustrative silane-cross-linked polyolefins includes, but is not limited to, silane cross-linked polyethylene (LLDPE, LDPE, HDPE or blends thereof), silane-cross- linked polypropylene, silane-cross-linked polybutylene, silane-cross-linked polypentene, silane-cross-linked polyhexene, silane-cross-linked polyheptene, silane-cross-linked polyoctene, and combinations thereof.

[0058] Method of Making Composition

[0059] In another aspect, a method of making a fire retardant composition for wire insulation is provided. The methods include adding a first fire retardant, optionally a second fire retardant, and a functional filler to an un-grafted polymer in a mixing vessel. An anti-oxidant, colorant, processing aid, UV stabilizer, or mixture of any two or more thereof, may also be added. The components mixed/added to the un-grafted polymer form a first mixture.

[0060] The method may further include compounding a silane-grafted polymer selected from the group consisting of silane-grafted polyolefins, silane-grafted thermoplastic polyolefins, and combinations of any two or more thereof with the first mixture by initiating the crosslinking reaction using a catalyst to promote the crosslinking reaction to form the fire retardant composition. Illustrative catalysts used to promote the crosslinking reaction include, but are not limited to, tin catalysts such as dibutyltindilaurate (DBTDL) and dioctyltindilaurate (DOTDL).

[0061] The method may further include compounding the silane-grafted polymer through an extrusion compounder. This may be conducted at a melt temperature from about 195 °C to about 220 °C, as determined pursuant to ISO 11357.

[0062] In various embodiments, the un-grafted polymer may be an un-grafted polyolefin. Illustrative un-grafted polyolefins include, but are not limited to, un-grafted polyethylene, un-grafted polypropylene, un-grafted polybutylene, un-grafted polypentene, un-grafted polyhexene, un-grafted polyheptene, un-grafted polyoctene, and a combination of any two or more thereof.

[0063] In some embodiments, the un-grafted polymer may be an un-grafted thermoplastic polyolefin. Illustrative un-grafted thermoplastic polyolefins include, but are not limited to, un-grafted thermoplastic polyethylene, un-grafted thermoplastic polypropylene, un-grafted thermoplastic polybutylene, un-grafted thermoplastic polypentene, un-grafted thermoplastic polyhexene, un-grafted thermoplastic polyheptene, un-grafted thermoplastic polyoctene, and a combination of any two or more thereof.

[0064] In an embodiment, the silane-grafted polymer may be selected from the group consisting of silane-grafted polyolefins, silane-grafted thermoplastic polyolefins, and a combination of any two or more thereof.

[0065] The silane-grafted polymer may be a silane-grafted polyolefin. Illustrative silane-grafted polyolefins include, but are not limited to, silane-grafted polyethylene (LLDPE, LDPE, HDPE or blends thereof), silane-grafted polypropylene, silane-grafted polybutylene, silane-grafted polypentene, silane-grafted polyhexene, silane-grafted polyheptene, silane-grafted polyoctene, and combinations thereof.

[0066] In an embodiment, the silane-grafted polymer may be a silane-grafted thermoplastic polyolefin. Illustrative silane-grafted thermoplastic polyolefins include, but are not limited to, silane-grafted thermoplastic polyethylene (LLDPE, LDPE, HDPE or blends thereof), silane-grafted thermoplastic polypropylene, silane-grafted thermoplastic polybutylene, silane-grafted thermoplastic polypentene, silane-grafted thermoplastic polyhexene, silane-grafted thermoplastic polyheptene, silane-grafted thermoplastic polyoctene, and a combination of any two or more thereof.

[0067] Method of Making Wire Insulation

[0068] In still another aspect, a method of making wire insulation comprising extruding the flame retardant composition as disclosed herein using the crosshead extrusion process to form the wire insulation.

[0069] Article of Manufacture

[0070] In still yet another aspect, an article of manufacture comprises a wire at least partially enclosed by wire insulation that includes a cross-linked polyolefin and a halogen- free fire retardant composition as disclosed herein. The halogen-free fire retardant composition includes a first fire retardant, a second fire retardant, and a function filler.

[0071] In an embodiment, the first fire retardant comprises aluminum diethyl phosphinate (DEPAL) from about 3 wt.% to about 8 wt.%. In an embodiment, the functional filler comprises kaolin clay at greater than 0 wt.% to about 6 wt.% and talc at greater than 0 wt.% to about 6 wt.%.

[0072] In an embodiment, the first fire retardant comprises aluminum diethyl phosphinate (DEPAL) from about 3 wt.% to about 8 wt.%. In an embodiment, the second fire retardant comprises melamine cyanurate (MC) from about 2 wt.% to about 6 wt.%.

[0073] In an embodiment, the first fire retardant comprises aluminum diethyl phosphinate (DEPAL) from about 3 wt.% to about 8 wt.%. In an embodiment, the second fire retardant comprises melamine cyanurate (MC) from about 2 wt.% to about 6 wt.%. In an embodiment, the functional filler comprises kaolin clay at greater than 0 wt.% to about 6 wt.% and talc at greater than 0 wt.% to about 6 wt.%.

[0074] The present invention, thus generally described, will be understood more readily by reference to the following examples, which are provided by way of illustration and are not intended to be limiting of the present invention.

EXAMPLES

[0075] Example 1. A flame retardant composition for wire insulation may includes a silane-cross-linked polyethylene at about 89 wt.%, aluminum diethyl phosphinate at about 7 wt.%, kaolin clay at about 2 wt.%, and talc at about 2 wt.%. See e.g., Table 2.

Table 2:

[0076] The flame retardant composition of Example 1 has a horizontal flame rating as determined pursuant to UL44, Section 5.14 and/or UL2556, Section 9.1 (i.e., passes the horizontal flame test). It is pass/fail criteria based upon the char length, the total length of char on the specimen shall not exceed 100 mm (4 in).

[0077] Example 2. The flame retardant composition for wire insulation may include a silane-cross-linked polyethylene at about 93 wt.%, aluminum diethyl phosphinate at about 4 wt.%, and melamine cyanurate at about 3 wt.%. See e.g., Table 3.

Table 3:

[0078] The flame retardant composition of Example 2 has a horizontal flame rating as determined pursuant to UL44, Section 5.14 and/or UL2556, Section 9.1 (i.e., passes the horizontal flame test). It is pass/fail criteria based upon the char length, the total length of char on the specimen shall not exceed 100 mm (4 in).

[0079] Example 3. The flame retardant composition for wire insulation includes a silane-cross-linked polyethylene at about 89 wt.%, aluminum diethyl phosphinate at about 4 wt.%, melamine cyanurate at about 3 wt.%, kaolin clay at about 2 wt.%, and talc at about 2 wt.%. See e.g., Table 4.

Table 4:

[0080] The flame retardant composition of Example 3 has a horizontal flame rating as determined pursuant to UL44, Section 5.14 and/or UL2556, Section 9.1 (i.e., passes the horizontal flame test). It is pass/fail criteria based upon the char length, the total length of char on the specimen shall not exceed 100 mm (4 in).

[0081] The following methods were used to prepare the compositions:

[0082] Method A. The compositions were prepared using laboratory scale twin screw extruder. The melt compounding process is achieved by feeding the resin pellets with the halogen free flame retardants additives. Functional fillers such as talc, kaolin clay, the catalyst, the antioxidants and the light stabilizes will also be added.

[0083] The main feeder along with the side feeder can be used to feed the ingredient materials to the extruder, the liquid materials such as the catalyst and the siloxanes will be injected downstream during the extrusion process. The extruded FR composition material is pelletized.

[0084] This FR composition will be combined with the silane grafted resin in a second extrusion pass to make the wire coating insulation. The wire samples will be cured in heated water bath to make the crosslinked structure.

[0085] Method B. In another compounding process, the polyethylene resin can be grafted with silane along with adding and compounding the FR ingredients and the other additives in a first extrusion pass. The second extrusion pass includes combining the filled graft made in the first step with the catalyst masterbatch to make the wire insulation. The wire samples will be cured in heated water bath to make the crosslinked structure.

[0086] Additional Examples and data. The following example compositions were prepared and tested as indicated in the following Tables.

Table 5. Examples 4-10.

* The additives are primary antioxidants (~ 0.2%), secondary antioxidants (-0.3%) and processing aids (-0.1%).

Table 6. Component Identification Table for the Flame retardant compositions. Table 7. Properties of Examples 4-10 from Table 5.

* All testing are based upon UL44 and UL2556 standards.

The following ASTM or UL methods were used for the indicated parameter testing: density: ASTM D792, FT-2 flame test: UL 44, section 5.14.1, burning particles: UL 44, Section 5.14.2, tensile strength & Elongation: ASTM D412, crush resistance: UL44, section 5.18, deformation: UL44, section 5.12, and long term insulation resistance in water (90 °C): UL44, section 5.4

Table 8. Examples 11-15.

* The additives are primary antioxidants (~ 0.2%), secondary antioxidants (-0.3%) and processing aids (-0.1%).

** Monomeric silianes sold under tradenames such as Dynasylan 9116, and oligomeric siloxanes such as Dynasylan 6490, 6498 and 6598 were used.

Table 9. Properties of Examples 11-15.

* All testing are based upon UL44 and UL2556 standards.

[0087] Discussion of the data: The above data are illustrative examples of the halogen-free flame retardant crosslinked polyethylene compositions that can be applied as wire insulation and jacket materials. The flame retardant package provided here is based upon the synergy of the phosphorus/nitrogen flame retardant system. The data shows that using this inventive composition with the first flame retardant (DEPAL) alone or in combination with the second flame retardant (MC), it will pass the flame testing according to UL44 standard (both FT-2 and the Burning particles), the composition has also a good mechanical properties.

[0088] Using phosphorus-based flame retardants makes it difficult to pass the longterm insulation resistance in water (LTIR) according to UL44 and UL2556. However, the data above shows that the natural version of the composition has the potential to pass the LTIR (as shown in example 6) by using the monomeric siloxane.

[0089] It was found out that adding the reactive siloxane oligomers, in some instances, results in passing tests, as shown in example 12.

[0090] Para. 1. A flame retardant composition for wire insulation comprising: a polymer comprising a cross-linked polyolefin; and a halogen-free fire retardant composition comprising: a first fire retardant comprising an aluminum dialkyl phosphinate; optionally, a second fire retardant comprising melamine cyanurate, melamine phosphate, melamine polyphosphate, or a mixture of any two or more thereof; and a functional filler comprising a clay, talc, or a combination of any two or more thereof; wherein the flame retardant composition exhibits a horizontal flame rating of FT-2 as determined pursuant to UL44, Section 5.14 and/or UL2556, Section 9.1.

[0091] Para. 2. The flame retardant composition of Para. 1, wherein the first fire retardant comprises aluminum diethyl phosphinate. [0092] Para. 3. The flame retardant composition of Para. 1 or 2, wherein the first fire retardant is present at greater than 0 wt.% to about 8 wt.%.

[0093] Para. 4. The flame retardant composition of Para. 1, 2, or 3, wherein the first fire retardant comprises aluminum diethyl phosphinate at greater than 0 wt.% to about 5 wt.%.

[0094] Para. 5. The flame retardant composition of any one of Paras. 1-4, wherein the functional filler comprises kaolin clay and talc.

[0095] Para. 6. The flame retardant composition of any one of Paras. 1-5, wherein the functional filler is present at greater than 0 wt.% to about 6 wt.%.

[0096] Para. 7. The flame retardant composition of any one of Paras. 1-6, wherein the functional filler comprises kaolin clay at greater than 0 wt.% to about 6 wt.% and talc at greater than 0 wt.% to about 6 wt.%.

[0097] Para. 8. The flame retardant composition of any one of Paras. 1-7, wherein the functional filler is kaolin clay at about 2 wt.% and talc at about 2 wt.%.

[0098] Para. 9. The flame retardant composition of any one of Paras. 1-8, wherein the polymer comprises a cross-linked polyethylene.

[0099] Para. 10. The flame retardant composition of any one of Paras. 1-9, wherein the polymer comprises a silane-cross-linked polyethylene.

[00100] Para. 11. The flame retardant composition of any one of Paras. 1-10, wherein the polymer is present in an amount to make up the balance of the composition.

[00101] Para. 12. The flame retardant composition of any one of Paras. 1-11, wherein: the first fire retardant comprises aluminum diethyl phosphinate from about 3 wt.% to about 8 wt.%; the functional filler comprises kaolin clay from about 0 wt.% to about 6 wt.% and talc from about 0 wt.% to about 6 wt.%; and the polymer comprises a cross-linked polyethylene at greater than 82 wt.%.

[00102] Para. 13. The flame retardant composition of any one of Paras. 1-12, wherein the second flame retardant comprises melamine cyanurate. [00103] Para. 14. The flame retardant composition of Para. 13, wherein the second fire retardant comprises melamine cyanurate from about 2 wt.% to about 6 wt.%.

[00104] Para. 15. The flame retardant composition of any one of Paras. 1-12, wherein: the first fire retardant comprises aluminum diethyl phosphinate from about 3 wt.% to about 8 wt.%; the second fire retardant comprises melamine cyanurate from about 2 wt.% to about 6 wt.%; and the polymer is a cross-linked polyethylene in an amount to make up a balance of the composition.

[00105] Para. 16. The flame retardant composition of any one of Paras. 1-12, wherein: the first fire retardant comprises aluminum diethyl phosphinate from about 3 wt.% to about 8 wt.%; the second fire retardant comprises melamine cyanurate from about 2 wt.% to about 6 wt.%; and the functional filler comprises kaolin clay at greater than 0 wt.% to about 6 wt.% and talc at greater than 0 wt.% to about 6 wt.%; and the polymer comprises a cross-linked polyethylene at greater than 82 wt.%.

[00106] Para. 17 The flame retardant composition of any one of Paras. 1-16 further comprising an anti-oxidant, processing aid, UV stabilizer, or a combination of any two or more thereof.

[00107] Para. 18. A wire insulation comprising: a first fire retardant comprising an aluminum dialkyl phosphinate; a second fire retardant comprising melamine cyanurate, melamine phosphate and melamine polyphosphate, or a mixture of any two or more thereof; and a functional filler comprising a clay, talc, or a combination of any two or more thereof; and a polymer comprising a cross-linked polyolefin, a cross-linked thermoplastic polyolefin, or a mixture of any two or more thereof.

[00108] Para. 19. The wire insulation of Para. 18, wherein: the first fire retardant comprises aluminum diethyl phosphinate from about 3 wt.% to about 8 wt.%; and the functional filler comprises kaolin clay at greater than 0 wt.% to about 6 wt.% and talc at greater than 0 wt.% to about 6 wt.%.

[00109] Para. 20. The wire insulation of Para. 18, wherein: the first fire retardant comprises aluminum diethyl phosphinate from about 3 wt.% to about 8 wt.%; and the second fire retardant comprises melamine cyanurate from about 2 wt.% to about 6 wt.%. [00110] Para. 21. The wire insulation of Para. 18, wherein: the first fire retardant comprises aluminum diethyl phosphinate from about 3 wt.% to about 8 wt.%; the second fire retardant comprises melamine cyanurate from about 2 wt.% to about 6 wt.%; and the functional filler comprises kaolin clay at greater than 0 wt.% to about 6 wt.% and talc at greater than 0 wt.% to about 6 wt.%.

[00111] Para. 22. A method of making a fire retardant composition for wire insulation, the method comprising combining a first fire retardant, a second fire retardant, and an un-grafted polymer to form a first mixture; wherein: the first fire retardant comprises aluminum dialkyl phosphinates; the second fire retardant comprises melamine cyanurate, melamine phosphate, melamine polyphosphate, or a mixture of any two or more thereof; and a functional filler comprising a clay, talc, or a combination of any two or more thereof; and the un-grafted polymer comprises an un-grafted polyolefin, un-grafted thermoplastic polyolefin, or a combination of any two or more thereof.

[00112] Para. 23. The method of Para. 22 further comprising adding additives or a mixture of any two or more additives to the first mixture, wherein the additives comprise an anti-oxidant, colorant, processing aid, UV stabilizer, or a mixture of any two or more thereof.

[00113] Para. 24. The method of Para. 23 further comprising compounding a silane- grafted polymer comprising silane-grafted polyolefins, silane-grafted thermoplastic polyolefins, or a combination of any two or more thereof with the first mixture by initiating a crosslinking reaction using a catalyst to promote the crosslinking reaction to form the fire retardant composition.

[00114] Para. 25. The method of Para. 24, wherein the compounding comprises compounding the silane-grafted polymer with the first mixture and initiating a crosslinking reaction using the catalyst to promote the crosslinking reaction to form the fire retardant composition.

[00115] Para. 26. The method of Para. 24 further comprising using an extrusion compounding technique to compound the silane-grafted polymer.

[00116] Para. 27. A method of making wire insulation comprising extruding the fire retardant composition of Para. 1 using a twin screw extruder to form the wire insulation. [00117] Para. 28. An article of manufacture comprising: a wire at least partially enclosed by wire insulation; wherein: the wire insulation comprises a cross-linked polyolefin and a halogen-free fire retardant composition; the halogen-free fire retardant composition comprises a first fire retardant, a second fire retardant, and a functional filler: the first fire retardant comprises an aluminum dialkyl phosphinate; the second fire retardant comprises melamine cyanurate, melamine phosphate, melamine polyphosphate, or mixture of any two or more thereof; and the functional filler comprises a clay or talc; and the wire insulation exhibits a horizontal flame rating of FT-2 as determined pursuant to UL44, Section 5.14 and/or UL2556, Section 9.1.

[00118] Para. 29. The article of manufacture of Para. 28, wherein: the first fire retardant comprises aluminum diethyl phosphinate from about 3 wt.% to about 8 wt.%; and the functional filler comprises kaolin clay at greater than 0 wt.% to about 6 wt.% and talc at greater than 0 wt.% to about 6 wt.%.

[00119] Para. 30. The article of manufacture of Para. 28, wherein: the first fire retardant comprises aluminum diethyl phosphinate from about 3 wt.% to about 8 wt.%; and the second fire retardant comprises melamine cyanurate from about 2 wt.% to about 6 wt.%.

[00120] Para. 31. The article of manufacture of Para. 28, wherein: the first fire retardant comprises aluminum diethyl phosphinate from about 3 wt.% to about 8 wt.%; the second fire retardant comprises melamine cyanurate from about 2 wt.% to about 6 wt.%; and the functional filler comprises kaolin clay at greater than 0 wt.% to about 6 wt.% and talc at greater than 0 wt.% to about 6 wt.%.

[00121] While certain embodiments have been illustrated and described, it should be understood that changes and modifications can be made therein in accordance with ordinary skill in the art without departing from the technology in its broader aspects as defined in the following claims.

[00122] The embodiments, illustratively described herein may suitably be practiced in the absence of any element or elements, limitation or limitations, not specifically disclosed herein. Thus, for example, the terms “comprising,” “including,” “containing,” etc. shall be read expansively and without limitation. Additionally, the terms and expressions employed herein have been 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 claimed technology.

Additionally, the phrase “consisting essentially of’ will be understood to include those elements specifically recited and those additional elements that do not materially affect the basic and novel characteristics of the claimed technology. The phrase “consisting of’ excludes any element not specified.

[00123] The present disclosure is not to be limited in terms of the particular embodiments described in this application. Many modifications and variations can be made without departing from its spirit and scope, as will be apparent to those skilled in the art. Functionally equivalent methods and compositions within the scope of the disclosure, in addition to those enumerated herein, will be apparent to those skilled in the art from the foregoing descriptions. Such modifications and variations are intended to fall within the scope of the appended claims. The present disclosure is to be limited only by the terms of the appended claims, along with the full scope of equivalents to which such claims are entitled. It is to be understood that this disclosure is not limited to particular methods, reagents, compounds, compositions, or biological systems, which can of course vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting.

[00124] In addition, where features or aspects of the disclosure are described in terms of Markush groups, those skilled in the art will recognize that the disclosure is also thereby described in terms of any individual member or subgroup of members of the Markush group.

[00125] As will be understood by one skilled in the art, for any and all purposes, particularly in terms of providing a written description, all ranges disclosed herein also encompass any and all possible subranges, and combinations of subranges thereof. Any listed range can be easily recognized as sufficiently describing and enabling the same range being broken down into at least equal halves, thirds, quarters, fifths, tenths, etc. As a nonlimiting example, each range discussed herein can be readily broken down into a lower third, middle third and upper third, etc. As will also be understood by one skilled in the art all language such as “up to,” “at least,” “greater than,” “less than,” and the like, include the number recited and refer to ranges which can be subsequently broken down into subranges as discussed above. Finally, as will be understood by one skilled in the art, a range includes each individual member.

[00126] All publications, patent applications, issued patents, and other documents referred to in this specification are herein incorporated by reference as if each individual publication, patent application, issued patent, or other document was specifically and individually indicated to be incorporated by reference in its entirety. Definitions that are contained in text incorporated by reference are excluded to the extent that they contradict definitions in this disclosure.

[00127] Other embodiments are set forth in the following claims.

Claims

WHAT IS CLAIMED IS:

1. A flame retardant composition for wire insulation comprising: a polymer comprising a cross-linked polyolefin; and a halogen-free fire retardant composition comprising: a first fire retardant comprising an aluminum dialkyl phosphinate; optionally, a second fire retardant comprising melamine cyanurate, melamine phosphate, melamine polyphosphate, or a mixture of any two or more thereof; and a functional filler comprising a clay, talc, or a combination of any two or more thereof; wherein the flame retardant composition exhibits a horizontal flame rating of FT-2 as determined pursuant to UL44, Section 5.14 and/or UL2556, Section 9.1.

2. The flame retardant composition of claim 1, wherein the first fire retardant comprises aluminum diethyl phosphinate.

3. The flame retardant composition of claim 1 or 2, wherein the first fire retardant is present at greater than 0 wt.% to about 8 wt.%.

4. The flame retardant composition of claim 1, 2, or 3, wherein the first fire retardant comprises aluminum diethyl phosphinate at greater than 0 wt.% to about 5 wt.%.

5. The flame retardant composition of any one of claims 1-4, wherein the functional filler comprises kaolin clay and talc.

6. The flame retardant composition of any one of claims 1-5, wherein the functional filler is present at greater than 0 wt.% to about 6 wt.%.

7. The flame retardant composition of any one of claims 1-6, wherein the functional filler comprises kaolin clay at greater than 0 wt.% to about 6 wt.% and talc at greater than 0 wt.% to about 6 wt.%.

8. The flame retardant composition of any one of claims 1-7, wherein the functional filler is kaolin clay at about 2 wt.% and talc at about 2 wt.%.

9. The flame retardant composition of any one of claims 1-8, wherein the polymer comprises a cross-linked polyethylene.

10. The flame retardant composition of any one of claims 1-9, wherein the polymer comprises a silane-cross-linked polyethylene.

11. The flame retardant composition of any one of claims 1-10, wherein the polymer is present in an amount to make up the balance of the composition.

12. The flame retardant composition of any one of claims 1-11, wherein: the first fire retardant comprises aluminum diethyl phosphinate from about 3 wt.% to about 8 wt.%; the functional filler comprises kaolin clay from about 0 wt.% to about 6 wt.% and talc from about 0 wt.% to about 6 wt.%; and the polymer comprises a cross-linked polyethylene at greater than 82 wt.%.

13. The flame retardant composition of any one of claims 1-12, wherein the second flame retardant comprises melamine cyanurate.

14. The flame retardant composition of claim 13, wherein the second fire retardant comprises melamine cyanurate from about 2 wt.% to about 6 wt.%.

15. The flame retardant composition of any one of claims 1-12, wherein: the first fire retardant comprises aluminum diethyl phosphinate from about 3 wt.% to about 8 wt.%; the second fire retardant comprises melamine cyanurate from about 2 wt.% to about

6 wt.%; and the polymer is a cross-linked polyethylene in an amount to make up a balance of the composition.

16. The flame retardant composition of any one of claims 1-12, wherein: the first fire retardant comprises aluminum diethyl phosphinate from about 3 wt.% to about 8 wt.%; the second fire retardant comprises melamine cyanurate from about 2 wt.% to about

6 wt.%; and the functional filler comprises kaolin clay at greater than 0 wt.% to about 6 wt.% and talc at greater than 0 wt.% to about 6 wt.%; and the polymer comprises a cross-linked polyethylene at greater than 82 wt.%.

17 The flame retardant composition of any one of claims 1-16 further comprising an antioxidant, processing aid, UV stabilizer, or a combination of any two or more thereof.

18. A wire insulation comprising: a first fire retardant comprising an aluminum dialkyl phosphinate; a second fire retardant comprising melamine cyanurate, melamine phosphate and melamine polyphosphate, or a mixture of any two or more thereof; and a functional filler comprising a clay, talc, or a combination of any two or more thereof; and a polymer comprising a cross-linked polyolefin, a cross-linked thermoplastic polyolefin, or a mixture of any two or more thereof.

19. The wire insulation of claim 18, wherein: the first fire retardant comprises aluminum diethyl phosphinate from about 3 wt.% to about 8 wt.%; and the functional filler comprises kaolin clay at greater than 0 wt.% to about 6 wt.% and talc at greater than 0 wt.% to about 6 wt.%.

20. The wire insulation of claim 18, wherein: the first fire retardant comprises aluminum diethyl phosphinate from about 3 wt.% to about 8 wt.%; and the second fire retardant comprises melamine cyanurate from about 2 wt.% to about 6 wt.%.

21. The wire insulation of claim 18, wherein: the first fire retardant comprises aluminum diethyl phosphinate from about 3 wt.% to about 8 wt.%; the second fire retardant comprises melamine cyanurate from about 2 wt.% to about 6 wt.%; and the functional filler comprises kaolin clay at greater than 0 wt.% to about 6 wt.% and talc at greater than 0 wt.% to about 6 wt.%.

22. A method of making a fire retardant composition for wire insulation, the method comprising combining a first fire retardant, a second fire retardant, and an un-grafted polymer to form a first mixture; wherein: the first fire retardant comprises aluminum dialkyl phosphinates; the second fire retardant comprises melamine cyanurate, melamine phosphate, melamine polyphosphate, or a mixture of any two or more thereof; and a functional filler comprising a clay, talc, or a combination of any two or more thereof; and the un-grafted polymer comprises an un-grafted polyolefin, un-grafted thermoplastic polyolefin, or a combination of any two or more thereof.

23. The method of claim 22 further comprising adding additives or a mixture of any two or more additives to the first mixture, wherein the additives comprise an anti-oxidant, colorant, processing aid, UV stabilizer, or a mixture of any two or more thereof.

24. The method of claim 23 further comprising compounding a silane-grafted polymer comprising silane-grafted polyolefins, silane-grafted thermoplastic polyolefins, or a combination of any two or more thereof with the first mixture by initiating a crosslinking reaction using a catalyst to promote the crosslinking reaction to form the fire retardant composition.

25. The method of claim 24, wherein the compounding comprises compounding the silane- grafted polymer with the first mixture and initiating a crosslinking reaction using the catalyst to promote the crosslinking reaction to form the fire retardant composition.

26. The method of claim 24 further comprising using an extrusion compounding technique to compound the silane-grafted polymer.

27. A method of making wire insulation comprising extruding the fire retardant composition of claim 1 using a twin screw extruder to form the wire insulation.

28. An article of manufacture comprising: a wire at least partially enclosed by wire insulation; wherein: the wire insulation comprises a cross-linked polyolefin and a halogen-free fire retardant composition; the halogen-free fire retardant composition comprises a first fire retardant, a second fire retardant, and a functional filler: the first fire retardant comprises an aluminum dialkyl phosphinate; the second fire retardant comprises melamine cyanurate, melamine phosphate, melamine polyphosphate, or mixture of any two or more thereof; and the functional filler comprises a clay or talc; and the wire insulation exhibits a horizontal flame rating of FT-2 as determined pursuant to UL44, Section 5.14 and/or UL2556, Section 9.1.

29. The article of manufacture of claim 28, wherein: the first fire retardant comprises aluminum diethyl phosphinate from about 3 wt.% to about 8 wt.%; and the functional filler comprises kaolin clay at greater than 0 wt.% to about 6 wt.% and talc at greater than 0 wt.% to about 6 wt.%.

30. The article of manufacture of claim 28, wherein: the first fire retardant comprises aluminum diethyl phosphinate from about 3 wt.% to about 8 wt.%; and the second fire retardant comprises melamine cyanurate from about 2 wt.% to about 6 wt.%.

31. The article of manufacture of claim 28, wherein: the first fire retardant comprises aluminum diethyl phosphinate from about 3 wt.% to about 8 wt.%; the second fire retardant comprises melamine cyanurate from about 2 wt.% to about

6 wt.%; and the functional filler comprises kaolin clay at greater than 0 wt.% to about 6 wt.% and talc at greater than 0 wt.% to about 6 wt.%.