CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This patent application claims the benefit of U.S. Provisional Patent Application 62/200,932, entitled "Oil and Mud Resistant Sheathing Composition," filed on August 4, 2015, the entire contents of which are hereby incorporated by reference, for any and all purposes.

BACKGROUND

[0002] Cables for use in marine structures such as oil well drilling ships, oil well drilling structures or drillships are required to have more excellent oil resistances compared to cables for more general use. In addition to this requirement, cables for such applications often are also required to maintain their flexibility even at low temperatures, e.g. down to - 40 °C. It has generally proved to be very difficult for a cable sheath material having flexibility at a such low temperatures as well as to satisfy both the oil resistance requirement of IEC 60092-359 and the oil resistance requirement of the NEK 606.

For this reason, cable sheathing materials exhibiting stronger oil resistances are in demand for cables for use in oil well drilling ships or drilling structures.

[0003] In recent years, the use of a halogen such as bromine or chlorine has been partially limited in many countries. This is because halogen-containing compounds have been reported to generate environmental hormones, which can result in a toxicity to the human body and a variety of adverse human health consequences. In addition, halogens can cause chemical reactions through interaction with water and heat, resulting in the generation of highly toxic products. When a fire breaks out in, for example, in ships provided with halogen-containing cables, the risk of human casualties can be increased due to the generation of such harmful gases.

[0004] In view of the trend toward environment-friendly products, there is a continuing desire to provide cable or electric wire which does not include a halogen-containing sheathing material. Since halogen based flame retardants are known to have adverse effects, for example emission of substances harmful to the human body upon combustion. In addition, there is a continuing need to develop a cable or an electric wire sheathing materials which maintains flexibility at very low temperatures and at the same time satisfies a high oil resistance for use in oil well drilling ships or drilling structures, while also exhibiting excellent flame retardancy.

SUMMARY

[0005] The present application relates generally to the field of materials which can be used as sheathing materials in wire and cable applications. The sheathing materials are desirably moisture curable, halogen-free polymer compositions, which includes a crosslinkable thermoplastic polymer and flame retardant material. The flame retardant material typically includes a metal hydroxide flame retardant, such as a magnesium, calcium, zinc and/or aluminum hydroxide. The crosslinkable thermoplastic polymer commonly includes a thermoplastic polyester elastomer, which may be blended with one or more other thermoplastic polymers, such as an ethylene/vinyl acetate copolymer. The polymer component of the sheathing material may also include an aromatic

polycarbodiimide, such as a polycarbodiimide based on aromatic diisocyanate chemistry, e.g., substituted phenyl diisocyanate chemistry. The crosslinkable thermoplastic polymer is desirably curable by exposure to moisture, e.g., by the inclusion of moisture curable silane functionality in the thermoplastic polymer. This may be accomplished by grafting silane functional groups onto a thermoplastic polymer. For example, crosslinkable thermoplastic polymer may include thermoplastic polyester elastomer and/or ethylene/vinyl acetate copolymer, which has been grafted with silane functional groups, e.g., through free radical initiated reaction with a vinyl alkoxysilane, such as a vinyltrialkoxysilane.

[0006] The present application provides a moisture curable, halogen-free polymer wire sheathing composition. The wire sheathing composition includes a crosslinkable thermoplastic polymer component, which includes silane-grafted polymer blend, and metal hydroxide flame retardant. The silane-grafted polymer blend is typically formed by silane- grafting a polymer blend which includes thermoplastic polyester elastomer and

ethylene/vinyl acetate copolymer. The thermoplastic polyester elastomer may be a thermoplastic elastomer ether ester, such a block copolymer, which includes a polyalkylene terephthalate segment and a long-chain polyalkylene ether segment, e.g., a polybutylene terephthalate segment, and a long-chain polyether glycol, such as a polyethyleneglycol segment. The polymer blend may also include an aromatic polycarbodiimide, such as an aromatic polycarbodiimide based on 2,6-diisopropyl phenyl isocyanate (DIPPI) and/or 2,4,6-triisopropyl phenyl diisocyanate (TRIDI) chemistry. The metal hydroxide flame retardant may include magnesium, calcium, zinc or aluminum hydroxide(s) or a mixture thereof.

DETAILED DESCRIPTION

[0007] The present application provides moisture curable, halogen-free polymer wire sheathing compositions, which typically exhibit excellent oil and mud resistance. The moisture curable, halogen-free sheathing materials may be used in wire and cable applications. The sheathing material includes a crosslinkable thermoplastic polymer and flame retardant material. The flame retardant material may include a metal hydroxide flame retardant, such as a magnesium, calcium, zinc and/or aluminum hydroxide. The

crosslinkable thermoplastic polymer includes a thermoplastic polyester elastomer, which may be blended with one or more other thermoplastic polymers. The polymer component of the sheathing material may also include an aromatic polycarbodiimide. The crosslinkable thermoplastic polymer is typically curable by exposure to moisture and may include moisture curable silane functionality in the thermoplastic polymer, e.g., silane functionality that has been grafted onto the thermoplastic polymer(s).

[0008] The halogen-free polymer wire sheathing composition typically includes about 10 to about 200 parts by weight of the metal hydroxide flame retardant per 100 parts by weight of the crosslinkable thermoplastic polymer. For example, the wire sheathing composition may include about 80 to about 150 parts by weight magnesium dihydroxide per 100 parts by weight of the crosslinkable thermoplastic polymer. The crosslinkable thermoplastic polymer typically includes a silane-grafted polymer blend, which may be formed by reacting a mixture which includes the thermoplastic polyester elastomer, the ethylene/vinyl acetate copolymer, vinylalkoxysilane and a free radical initiator. The mixture may also include an aromatic polycarbodiimide (PCD).

[0009] The thermoplastic polyester elastomer may include a thermoplastic elastomer ether ester, such as a thermoplastic polyester ether elastomer with polyalkylene terephthalate and long-chain polyether glycol segments. One example of a suitable thermoplastic polyester ether elastomer is a block copolymer, which includes a polybutylene terephthalate segment and a long-chain polyether glycol.

[0010] The ethylene/vinyl acetate (EVA) copolymer is typically a random ethylene /vinyl acetate copolymer. The ethylene/vinyl acetate copolymer may have a vinyl acetate content of about 25-30%, more commonly about 27-29%. Such ethylene/vinyl acetate copolymers may suitably have a melt flow index (MFI as determined pursuant to ISO 11357) of about 0.1 - 1 g/10 min (@ 230 C) and a density of about 0.94-0.96. Such EVA copolymers may suitably have a Shore A hardness (as determined pursuant to ISO 868) of about 70-80 and/or a melting temperature of about 135-145 °C (as determined pursuant to ISO 11357).

[0011] The aromatic polycarbodiimide (PCD) may be introduced into the mixture to be silane grafted as a polymer blend with the thermoplastic polyester elastomer. For example, the aromatic polycarbodiimide may be a polycarbodiimide based on substituted phenyl diisocyanate chemistry. A suitable example, is an aromatic polycarbodiimide based on 2,6- diisopropyl phenyl isocyanate (DIPPI) and/or 2,4,6-triisopropyl phenyl diisocyanate (TRIDI) chemistry. The polymer blend may include about 10-25 wt.% of the

polycarbodiimide (PCD) as a blend in the thermoplastic polyester elastomer, e.g., as blend with a thermoplastic polyester ether elastomer, which may be a block copolymer including a polybutylene terephthalate segment and a long-chain polyether glycol.

[0012] The flame retardant material may be metal hydroxide flame retardant, such as a magnesium, calcium, zinc and/or aluminum hydroxide. The flame retardant material typically includes magnesium hydroxide and/or aluminum hydroxide, which commonly has an average particle size no more than about 3 microns. For example, the flame retardant material may include magnesium hydroxide, such as a precipitated magnesium dihydroxide (MDH) having average particle size of no more than about 2 microns. The magnesium dihydroxide may be in the form of hexagonal platelets having average particle size of about 0.8-2 microns.

[0013] The present crosslinkable polymer composites may suitably contain a number of optional ingredients. For example, the composites may include anti-oxidant(s), a UV protector/light stabilizer, colorant, and optional processing aids such as an UHMW silicone, which may be dispersed in a thermoplastic polyolefin, and/or chalk. [0014] The tables below provide illustrative formulations that can be used to produce the present wire sheathing materials. The silane grafted polyester blends may be formed by combining a thermoplastic polyester ether elastomer, such as a polyester ether having polybutylene terephthalate and long-chain polyether glycol segments, with a

polycarbodiimide (available as a blend in the polyester ether) and a random ethylene/vinyl acetate copolymer (EVA) in the amounts shown in the tables below for formulations Al and A2. The mixture may also include other additives, such as antioxidant, chalk (CaC0 ₃ ). Vinyl silane, e.g., vinyl trimethoxysilane, and organic peroxide (such as l, l-di(tert- butylperoxy)-3,3,5-trimethylcyclohexane) are included in the amounts shown. The mixture may suitably be compounded in an extruder at a temperature of about 140 to 200°C to provide the silane grafted polymer blend.

[0015] The silane-grafted polymer blend may be compounded with metal hydroxide flame retardant (e.g., magnesium hydroxide and/or aluminum hydroxide) and other conventional additives and then extruded to form a halogen free, flame-retardant, crosslinkable polymer composite. This may suitably be carried out by extrusion compounding the silane-grafted polymer blend metal hydroxide flame retardant and other conventional additives in an extruder at a temperature of about 135 to 200°C. The crosslinkable polymer composite is typically UV stabilized and is curable by exposure to moist conditions. In use, the crosslinkable polymer composite is typically mixed with a crosslinking catalyst

masterbatch, e.g., in a ratio of about 95:5 to 99: 1 (commonly about 97:3). The moisture cured product is commonly able to satisfy the requirements of the NEK 606 and/or IEC 60092-359 standards. The product typically shows good flexibility and confers tough sheathing protection. It is particular notable that the moisture cured product may exhibit oil and mud resistance, such required by specification NEK 606, in combination with one or more of the other specifications typically required for such sheathing materials.

[0016] The tables below provide illustrations of suitable formulations for producing the present crosslinkable halogen-free, flame retardant filled polymer composites. The components for listed for Silane Grafted Polyester Blend Formulation Al can be melt processed, e.g., via extrusion, to provide Silane Grafted Polymer Blend Al . This may then be combined in the amount shown with the other ingredients listed for Flame Retardant Filled Polymer Composite Formulation HFFR-1 in a melt processing step, e.g., via extrusion, to provide a crosslinkable polymer composite. The components for listed for Silane Grafted Polyester Blend Formulation A2 can be melt processed, e.g., via extrusion, to provide Silane Grafted Polymer Blend A2. This may then be combined in the amount shown with the other ingredients listed for Flame Retardant Filled Polymer Composite Formulation FIFFR-2 in a melt processing step, e.g., via extrusion, to provide a crosslinkable polymer composite.

Silane Grafted Polyester Blend Formulation Al

Flame Retardant Filled Polymer Composite Formulation HFFR-1

Silane Grafted Polyester Blend Formulation A2

EXAMPLES

[0017] The following examples more specifically the present cleaning compositions according to various embodiments described above. These examples should in no way be construed as limiting the scope of the present technology.

[0018] Production of a halogen free flame-retardant, silane crosslinkable, UV stabilized, flexible polymer composite, curable by exposure to moist conditions can be carried out by combining the components for listed below for the 1 st Pass - Silane Grafted Polyester/EVA Blend Formula. This can be done via a melt processing operation, e.g., via extrusion compounding at about 140 to 200°C, to provide the 1 ^st Pass Silane Grafted Polymer Blend. This may then be combined in the amount shown with the other ingredients listed for the 2 ^nc Pass - Flame Retardant Filled Polymer Composite in a melt processing step, e.g., via extrusion compounding at about 135 to 200° C, to provide a crosslinkable polymer composite.

Silane Grafting of polyester/EVA blend

1 ^st Pass - Silane Grafted Polyester/EVA Blend Formula

Production of FiFFR Polymer Composite

2" Pass - Flame Retardant Filled Polymer Composite

ILLUSTRATIVE EMBODIMENTS

[0019] 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.

[0020] In one embodiment, the moisture curable, halogen-free polymer composite includes a crosslinkable thermoplastic polymer and metal hydroxide flame retardant selected from magnesium, calcium, zinc and aluminum hydroxide or mixtures thereof. The crosslinkable thermoplastic polymer includes a silane-grafted polymer blend, where the polymer blend includes thermoplastic polyester elastomer and ethylene/vinyl acetate copolymer and may also include an aromatic polycarbodiimide. The thermoplastic polyester elastomer typically includes a thermoplastic elastomer ether ester, such as a block copolymer, which includes a polybutylene terephthalate segment and a long-chain polyether glycol. The ethylene/vinyl acetate copolymer typically has a vinyl acetate content of about 20-35% and, commonly, about 25-30%. The metal hydroxide flame retardant generally includes magnesium dihydroxide (Mg(OH)2). The magnesium dihydroxide may be a precipitated magnesium dihydroxide with a median particle size of about 0.1 to 3 microns (often - 0.8 - 2 microns) and may be in the form of hexagonal platelets. The composition may also include one or more of chalk, antioxidant, ultrahigh molecular weight silicone processing additive and UV protector/light stabilizer additive.

[0021] In another embodiment, the moisture curable, halogen-free polymer composition includes 100 parts by weight of a crosslinkable thermoplastic polymer and about 10 to about 200 parts by weight metal hydroxide selected from magnesium, calcium, zinc or aluminum hydroxides or mixtures thereof. The crosslinkable thermoplastic polymer typically includes silane-grafted thermoplastic polyester elastomer and/or silane-grafted ethylene/vinyl acetate copolymer. The crosslinkable thermoplastic polymer may also include an aromatic polycarbodiimide, such as an aromatic polycarbodiimide based on 2,6-diisopropyl phenyl isocyanate (DIPPI) and/or 2,4,6-triisopropyl phenyl diisocyanate (TRIDI) chemistry. The composition may also include chalk and/or antioxidant.

[0022] In another embodiment, the moisture curable, halogen-free polymer composition includes a crosslinkable thermoplastic polymer, which includes silane-grafted thermoplastic polyester elastomer, silane-grafted ethylene/vinyl acetate copolymer and aromatic polycarbodiimide; and metal hydroxide flame retardant, which comprises magnesium dihydroxide. The magnesium dihydroxide may be precipitated magnesium dihydroxide with a median particle size of about 0.1 to 2 microns, where the precipitated magnesium dihydroxide is in the form of hexagonal platelets. The composition may also include one or more of chalk, antioxidant, ultrahigh molecular weight silicone processing additive and UV protector/light stabilizer additive.

[0023] In another embodiment, the moisture curable, halogen-free polymer composition includes 100 parts by weight of a crosslinkable thermoplastic polymer comprising silane- grafted polymer blend, which includes an ether ester block copolymer including a polybutylene terephthalate segment and a long-chain polyether glycol, ethylene/vinyl acetate copolymer and aromatic polycarbodiimide; and about 80 to about 150 parts by weight precipitated magnesium dihydroxide with a median particle size of about 0.1 to 2 microns. The composition may also include one or more of chalk, antioxidant, ultrahigh molecular weight silicone processing additive and UV protector/light stabilizer additive.

[0024] A silane grafted polymer blend may be formed by combining a polyester ether having polybutylene terephthalate segment and a long-chain polyether glycol, with a polycarbodiimide (available as a blend in the polyester ether) and a random ethylene/vinyl acetate copolymer (EVA) in the amounts shown in the table above for 1 ^st pass ingredients. The mixture also includes antioxidant, chalk (CaC03), vinyl trimethoxysilane and organic peroxide (such as l,l-di(tert-butylperoxy)-3,3,5-trimethylcyclohexane) in the amounts shown. The mixture is typically passed through an extruder at a temperature of aboutl40 to 200 °C to provide the silane grafted polymer blend.

[0025] This silane grafted polymer blend may be compounded with metal hydroxide flame retardant and other conventional additives and then extruded to form a halogen free, flame-retardant, crosslinkable polymer composite. The crosslinkable polymer composite is typically UV stabilised and is curable by exposure to moist conditions, typically at a somewhat elevated temperature. In use, the crosslinkable polymer composite is typically mixed with a crosslinking catalyst masterbatch, e.g., in a ratio of about 95:5 to 98:2. The moisture cured product is commonly able to satisfy the requirements of the NEK 606 and/or IEC 60092-359 SHF2 standards. The product typically shows good flexibility and confers tough sheathing protection. It is particular notable that the moisture cured product may exhibit excellent oil and mud resistance, such required by specification NEK 606, in combination with all the other specifications typically required for such sheathing materials.

[0026] Sheathing materials formed from curing the crosslinkable, halogen-free, flame retardant polymer composite materials described herein commonly meet one or more of the following specifications:

- the composition has a variation in tensile strength after accelerated aging in

mineral oil (IRM 903) for 7 days at 100 °C of no more than about ±30% (as determined pursuant to IEC 60092-360 & NEK606:2009).

- the composition has a variation in elongation after accelerated aging in mineral oil (IRM 903) for 7 days at 100 °C of no more than about ±30% (as determined pursuant to IEC 60092-360 & NEK606:2009).

- the composition has a mass increase after accelerated aging in mineral oil (IRM 903) for 7 days at 100 °C of no more than about 30% (as determined pursuant to IEC 60092-360 & NEK606:2009).

the composition has a volume swell increase after in mineral oil (IRM 903) for 7 days at 100 °C of no more than about 30% (as determined pursuant to IEC 60092-360 & NEK606:2009).

- the composition has a hot elongation after for 15 minutes at 200 °C (20N load) of no more than about 175% (as determined pursuant to IEC 60092-360 & NEK606:2009).

- the composition has a permanent elongation after treatment for 15 minutes at 200 °C and subsequent cooling of no more than about 25% (as determined pursuant to IEC 60092-360 & NEK606:2009).

- the composition has an elongation before aging at least about 120% (as

determined pursuant to IEC 60092-360 & NEK606:2009).

- the composition has a tensile strength before aging at least about 9N/mm ² (as determined pursuant to IEC 60092-360 & NEK606:2009).

- the composition has a variation in tensile strength after accelerated aging in SHF Mud oil (EDC 95-11) for 56 days at 70 °C of no more than about ±25% (as determined pursuant to IEC 60092-360 & NEK606:2009).

- the composition has a variation in elongation after accelerated aging in SHF Mud oil (EDC 95-11) for 56 days at 70 °C of no more than about ±25% (as determined pursuant to IEC 60092-360 & NEK606:2009). - the composition has a mass increase after accelerated aging in SHF Mud oil (EDC 95-11) for 56 days at 70 oC of no more than about ±15% (as determined pursuant to IEC 60092-360 & EK606:2009).

- the composition has a volume swell increase after accelerated aging in SHF Mud oil (EDC 95-11) for 56 days at 70 oC of no more than about ±20% (as determined pursuant to IEC 60092-360 & EK606:2009).

- the composition has a variation in tensile strength after accelerated aging in air oven for 7 days at 120 °C of no more than about ±30% (as determined pursuant to IEC 60092-360 & EK606:2009).

- the composition has a variation in elongation at break after accelerated ageing in air oven for 7 days at 120 °C of no more than about ±30% (as determined pursuant to IEC 60092-360 & EK606:2009).

- the composition exhibits no cracking after exposure to 250-300 ppm ozone at 25 °C for 24 hours as determined pursuant to to IEC 60092-360 & EK606:2009.

[0027] 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," 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.

[0028] As used herein, "about" 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 term which are not clear to persons of ordinary skill in the art, given the context in which it is used, "about" will mean up to plus or minus 10% of the particular term.

[0029] 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.

[0030] 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.