1. A composition comprising

A. A first interpolymer or oligomer comprising ethylene monomer residues and residues of a first comonomer having one or more functional groups selected from the group consisting of carboxylic acids;

B. a second interpolymer or oligomer comprising ethylene monomer residues and residues of a second comonomer having epoxy functionality; and

C. a peroxide free radical initiator.

2. The composition of claim 1, comprising:

5 to 94.995 wt% of the first interpolymer or oligomer;

5 to 94.995 wt% of the second interpolymer or oligomer; and

0.005 to 1.2 weight percent of the peroxide free radical initiator;

the wt% is based on the total weight of the composition.

3. The composition of claim 2, comprising from 0.18 wt% to 0.40 wt% of the peroxide free radical initiator, the wt% based on the total weight of the composition.

4. The composition of claim 1, further comprising a catalyst.

5. The composition of claim 4, comprising 0.005 to 1.2 wt% of the catalyst.

6. The composition of claim 4, wherein the molar ratio of catalyst to epoxide is in the range of 1:240 to 2: 15.

7. The composition of claim 1, wherein:

the first interpolymer has an anhydride content of from 0.1 wt% to 10 wt%; and is

The second interpolymer has an epoxide content of 0.1 wt% to 10 wt%.

8. The composition of claim 1, wherein the epoxide to anhydride molar ratio is in the range of 12:1 to 1: 12.

9. The composition of claim 1, wherein:

the first comonomer comprises acrylic acid, methacrylic acid, or maleic anhydride, or a combination thereof; and is

The second comonomer comprises glycidyl acrylate, glycidyl methacrylate, or allyl glycidyl ether, or a combination thereof.

10. The composition of claim 1, wherein the first interpolymer comprises residues of the first comonomer from 1 wt% to 10 wt%, and

the second interpolymer comprises from 1 to 10 weight percent of residues of the second comonomer.

Background

Medium voltage ("MV"), high voltage ("HV") and extra high voltage ("EHV") cables typically contain an oxide crosslinked polyethylene material as an insulating layer. Existing processes for cable manufacture involve extruding Low Density Polyethylene (LDPE) imbibed with peroxide as an insulating layer onto a suitable conductor at a temperature where peroxide reaction is minimal to maintain good processability (average temperature of about 140 ℃). Subsequently, the cable core was conveyed through a vulcanization unit at an elevated temperature of about 200 ℃ on average, causing crosslinking of the LDPE insulation within a few minutes. After cooling, the cable core is wound onto a spool for subsequent processing.

Although crosslinking provides a valuable improvement in the thermo-mechanical properties of the material, peroxide generation for crosslinking requires the removal (e.g., by degassing) of byproducts from the material after formation in the insulating layer but before placing the jacket layer over the insulating layer. In the case of dicumyl peroxide, these by-products include methane, acetophenone, alpha methyl styrene, and cumyl alcohol. Although work has been conducted to explore insulating materials that do not require outgassing, no available solution has been found to date.

Techniques have been described for crosslinking polyethylene via a catalyst-assisted epoxy-anhydride reaction that can reduce volatile byproducts in the crosslinked material by more than 70%. However, achieving a suitable balance of cure rate at the disclosed 175 ℃ to 260 ℃ cure temperature and scorch delay at 140 ℃ is problematic, either with a significantly slower cure rate or significantly more prone to scorch than existing peroxide-initiated systems.

Thus, there remains a need for crosslinkable materials suitable for use in wire and cable applications that can be produced at acceptable cure rates during the vulcanization stage without compromising processability during the extrusion stage and that require little or no degassing after crosslinking of the material.

Disclosure of Invention

In various embodiments, the present disclosure provides compositions comprising:

A. a first interpolymer or oligomer comprising ethylene monomer residues and residues of a first comonomer having one or more functional groups selected from the group consisting of carboxylic acid and carboxylic acid anhydride;

B. a second interpolymer or oligomer comprising ethylene monomer residues and residues of a second comonomer having epoxy functionality; and

C. a peroxide free radical initiator.

In an embodiment, the composition comprises a catalyst.

In another aspect, the present invention provides a crosslinked composition formed from a composition as disclosed herein. In an embodiment, the crosslinking composition has a volatile content of less than 1.0 wt%.

In another aspect, the present disclosure provides an article comprising at least one component formed from a composition as disclosed herein. In one embodiment, the article is an insulated cable comprising a conductor and an insulation comprising an at least partially crosslinked polymeric network comprising a composition as disclosed herein.

In yet another aspect, the present invention provides a process for preparing a crosslinked insulation by crosslinking at least a portion of a crosslinkable material comprising a composition as disclosed herein and a catalyst at a temperature of 175 ℃ to 260 ℃ to provide a crosslinked insulation.

The compositions, articles, and/or methods may comprise a combination of two or more embodiments described herein.

Drawings

Figure 1 is a graph of TGA measurements reporting the by-product (volatiles) content of samples CS3, TS5, and TS6) in study 2.

Detailed Description

Various embodiments of the present invention are directed to hybrid compositions comprising blends of epoxy and anhydride grafted polymers designed to cure by peroxide and epoxy/anhydride initiated crosslinking reactions. An amount of peroxide is added to the epoxy and anhydride grafted polymer blend to accelerate the cure rate while reducing volatile byproducts by more than 70% compared to the levels found in prior art compositions cured with peroxide alone.

In an embodiment, the interpolymer blend (including the peroxide initiator and crosslinking catalyst) cures to a gel content of greater than (>)60 wt% in less than 1.13 minutes when subjected to crosslinking conditions at 200 ℃, as determined by the method described in astm d 2765.

The compositions and methods are useful in a variety of commercial applications, including (but not limited to) insulation and jacketing applications for wire and cable.

Ethylene-based interpolymers

In various embodiments, the composition comprises at least two types of ethylene-based interpolymers. Each of the first and second interpolymers comprises ethylene monomer residues. The first interpolymer comprises residues of a first comonomer having one or more functional groups selected from the group consisting of carboxylic acids and carboxylic acid anhydrides. The second interpolymer comprises residues of a second comonomer having epoxy functionality.

In an embodiment, the ethylene monomer of the interpolymer comprises at least 50 weight percent ("wt%") of the total alpha-olefin content of the interpolymer. In embodiments, the ethylene monomer can comprise at least 60 wt%, at least 70 wt%, at least 80 wt%, at least 90 wt%, at least 95 wt%, at least 99 wt%, or up to 100 wt% of the total alpha-olefin monomer content of the interpolymer. In embodiments, ethylene monomer can comprise substantially all of the total alpha-olefin monomer content of the interpolymer.

In an embodiment, the first interpolymer has an anhydride content of from 0.1 wt% to 10 wt%; and the second interpolymer has an epoxide content of from 0.1 wt% to 10 wt%. In the examples, the epoxide to anhydride molar ratio is in the range of 12:1 to 1: 12. In an embodiment, each of the first and second interpolymers has a number average molecular weight from 1,000 to 500,000.

In addition, the first and second interpolymers may optionally further comprise additional comonomer residues. Examples of such optional comonomers include alpha-olefins (alpha-olefins), dienes, vinyl silanes, unsaturated esters (e.g., ethyl acrylate), and acetates (e.g., vinyl acetate). In embodiments, the first and/or second interpolymer comprises residues of one or more alpha-olefin comonomers. In embodiments, the alpha-olefin comonomer can be any C₃-C₂₀Alpha-olefin monomer, C₃-C₁₂Alpha-olefin monomers or C₃-C₅An alpha-olefin monomer. Examples of such alpha-olefin monomers include, but are not limited to, propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, and the like. The alpha-olefins may also contain cyclic structures such as cyclohexane or cyclopentane, yielding alpha-olefins such as 3-cyclohexyl-1-propene (allylcyclohexane) and vinylcyclohexane. In an embodiment, the alpha-olefin comonomer may be selected from the group consisting of propylene, 1-butene, and mixtures thereof. Such optional monomer residues may be present in an amount in the range of 1 wt% to 40 wt% or 5 wt% to 20 wt%.

First interpolymer

In addition to ethylene monomer residues, the first interpolymer comprises residues of a first comonomer having one or more functional groups selected from the group consisting of carboxylic acid and carboxylic acid anhydride. In addition, the first comonomer may have at least one site of unsaturation to allow the first comonomer to polymerize. Illustrative examples of comonomers having carboxylic acid functionality include acrylic acid and methacrylic acid and the like and higher homologs thereof. Examples of comonomers having carboxylic anhydride functionality are maleic anhydride and the like. In an embodiment, the first comonomer is selected from the group consisting of acrylic acid, maleic anhydride and mixtures thereof. In some embodiments, the first comonomer is acrylic acid. In some embodiments, the first comonomer is maleic anhydride.

In embodiments, the first interpolymer can comprise at least 0.5 wt%, at least 1 wt%, or at least 2 wt% of the first comonomer, based on the total weight of the first interpolymer. In embodiments, the first interpolymer can comprise the first comonomer in an amount in the range of from 0.5 wt% to 10 wt%, from 1 wt% to 5 wt%, or from 2 wt% to 4 wt%. The amount of the first comonomer can be confirmed via analytical methods known in the art such as, but not limited to, fourier transform infrared spectroscopy, nuclear magnetic resonance, and differential scanning calorimetry. In embodiments, ethylene monomer residues comprise the remainder of all (i.e., 100 wt%) or substantially all of the first interpolymer.

In embodiments, the first interpolymer has a melt index ("I") in the range of from 1 to 50dg/min, or in the range of from 2 to 7dg/min₂") as determined according to ASTM D-1238(190 ℃/2.16 kg). In embodiments, the first interpolymer has a melt flow rate in the range of from 0.85 to 0.97g/cm³Or in the range of 0.86 to 0.93g/cm³Density within the range of (a), as determined according to ASTM D-792. In embodiments, the first interpolymer has a polydispersity index (i.e., weight average molecular weight/number average molecular weight, "Mw/Mn," or molecular weight distribution ("MWD")) in the range of 1.5 to 20 or in the range of 3 to 15, as determined by gel permeation chromatography.

An example of a commercially available interpolymer suitable for use as the first interpolymer is Lotader^TM3210 which is an anhydride functionalized polyethylene (poly (ethylene-co-butyl acrylate-co-maleic anhydride random terpolymer) available from Arkema, Inc.

Second interpolymer

In addition to ethylene monomer residues, the second interpolymer comprises residues of a second comonomer having epoxy functionality. In an embodiment, the second comonomer comprises at least one epoxy functional group. In addition, the second comonomer may have at least one site of unsaturation to allow the second comonomer to polymerize. Illustrative examples of comonomers having epoxy functionality include glycidyl esters of carboxylic acids, such as esters of acrylic or methacrylic acid and the like, and higher homologs thereof. In embodiments, an unsaturated glycidyl ether can be used as at least a portion of the second comonomer. Exemplary comonomers having epoxy functionality include glycidyl acrylate, glycidyl methacrylate, and allyl glycidyl ether. In some embodiments, the second comonomer is glycidyl methacrylate.

In embodiments, the second interpolymer comprises at least 0.5 wt%, at least 3 wt%, or at least 7 wt% of the second comonomer, based on total second interpolymer weight. In embodiments, the second interpolymer can comprise the second comonomer in an amount in the range of from 0.5 wt% to 20 wt%, from 3 wt% to 10 wt%, or from 7 wt% to 9 wt%. In various embodiments, ethylene monomer residues comprise all or substantially all of the remainder of the second interpolymer. In embodiments, ethylene monomer residues comprise the remainder of all (i.e., 100 wt%) or substantially all of the second interpolymer.

In embodiments, the second interpolymer has a melt index ("I") in the range of from 1 to 50dg/min, or in the range of from 2 to 7dg/min₂") as determined according to ASTM D-1238(190 ℃/2.16 kg). In an embodiment, the second interpolymer has a melt flow rate in the range of from 0.85 to 0.97g/cm³Or in the range of 0.86 to 0.93g/cm³Density within the range of (a), as determined according to ASTM D-792. In embodiments, the second interpolymer has a polydispersity index in the range of from 1.5 to 20 or in the range of from 3 to 15, as determined by gel permeation chromatography.

An example of a commercially available interpolymer suitable for use as the second interpolymer is Lotader^TMAX 8840, which is an epoxy-functionalized polyethylene (poly (ethylene-co-glycidyl methacrylate) random copolymer) available from arkema.

Any method known or hereafter discovered for making interpolymers can be used to make the first and second interpolymers having the corresponding compositions described herein. In embodiments, the interpolymers may be prepared using methods known for preparing high pressure low density polyethylene ("HP LDPE"). One conventional high pressure process is described in Introduction to Polymer Chemistry, Stille, Wiley and Sons, New York, 1962, pages 149-151. High pressure processes are generally free radical initiated polymerizations carried out in a tubular reactor or a stirred autoclave. In such cases, the first and second comonomer residues are incorporated during polymerization of the first and second interpolymers, respectively. In other embodiments, the first and second comonomer residues may be incorporated by a grafting process. For example, an ethylene polymer, such as LDPE, can be melt mixed with one or more of the described first and/or second comonomers (e.g., maleic anhydride, acrylic acid, allyl glycidyl ether, glycidyl methacrylate, etc.) in the presence of a peroxide or other free radical initiator to form an interpolymer comprising the first and second comonomers.

In the examples, the interpolymers were prepared using free radical initiated low density polyethylene based polymerization. In addition to feeding ethylene and various comonomers as described herein, other components may be fed to the reactor to initiate and support the free radical reaction in forming the interpolymer, as known and used in the art such as reaction initiators, catalysts, and chain transfer agents.

Free radical initiators

In various embodiments, the blend of the first and second interpolymers is cured by a free radical and epoxy/anhydride initiated crosslinking reaction.

In embodiments, the first and second interpolymers are combined with a peroxide free radical initiator ("peroxide initiator").

Examples of peroxide initiators include, but are not limited to, dicumyl peroxide, 2, 5-bis (t-butylperoxy) -2, 5-dimethylhexane, bis (t-butyldioxyisopropyl) benzene, di-t-butyl peroxide, t-butyl perbenzoate, benzoyl peroxide, cumene hydroperoxide, t-butyl peroctoate, methyl ethyl ketone peroxide, 2, 5-dimethyl-2, 5-di (t-butylperoxy) hexane, 2, 5-dimethyl-2, 5-di (t-butylperoxy) -3-hexyne, dodecyl peroxide, t-butyl peracetate, and the like. In embodiments, the peroxide initiator is selected from the group consisting of: dicumyl peroxide, 2, 5-bis (t-butylperoxy) -2, 5-dimethylhexane and bis (t-butyldioxyisopropyl) benzene. In an embodiment, the free radical initiator is dicumyl peroxide.

In embodiments, the concentration of peroxide initiator is 0.005 wt% or greater, or greater than (>)0.05 wt%, or >0.1 wt%, or >0.16 wt%, or >0.25 wt%, or >0.5 wt%, or >1 wt%, or up to 1.2 wt%, or up to 0.4 wt%, based on the total weight of the composition. In embodiments, the peroxide initiator is present in a concentration of 0.005 wt% to 1.2 wt%, or ≧ 0.05 wt% to <1.2 wt%, or 0.1 wt% to 0.4 wt%, based on the total weight of the composition. In embodiments, the peroxide initiator is present at a concentration of >0.16 wt% to 1.2 wt% based on the total weight of the composition.

Crosslinking catalyst

In various embodiments, the interpolymer blend may be crosslinked to form an at least partially crosslinked polymeric network. In such embodiments, the blend of the first and second interpolymers and the peroxide initiator may be combined with a crosslinking catalyst to aid in crosslinking.

Crosslinking catalysts suitable for use in the present invention include catalysts commonly used to cure epoxy resins, including, but not limited to, amines, imidazoles, substituted imidazoles, imidazolium, substituted imidazolium, phosphines, phosphonium, ammonium compounds, and the like. Examples of such crosslinking catalysts include tertiary amines such as triethylamine, tripropylamine, tributylamine, and benzyldimethylamine; substituted imidazoles such as 1-methylimidazole, 2-methylimidazole and 4-methyl-2-phenylimidazole (MPI); substituted imidazolium, such as 3-ethyl-1-methylimidazolium chloride, 1, 3-dimethylimidazolium chloride; phosphonium compounds such as ethyltriphenylphosphonium; ammonium compounds such as benzyltrimethylammonium chloride, and the like, and mixtures thereof. In one embodiment, the crosslinking catalyst is 4-methyl-2-phenylimidazole (MPI).

Depending on the catalyst and the reaction conditions, the catalyst may optionally be co-reacted to a formulation.

In embodiments, the concentration of the crosslinking catalyst may range from 0.005 wt%, or 0.01 wt%, or 0.1 wt% up to 2 wt%, or 1.5 wt%, or 1.2 wt%, or 1 wt%, based on the total weight of the composition. In embodiments, the crosslinking catalyst is present in an amount of 0.005 wt% to 2 wt%, or 0.01 wt% to 1.5 wt%, or 0.1 wt% to 1 wt%, based on the total weight of the composition. In an embodiment, the catalyst is present in an amount of 0.005 wt% to 1.2 wt%, based on the total weight of the composition.

In the examples, the ratio of catalyst to epoxide is in the range of 1:240 to 2: 15.

Additive agent

In embodiments, the interpolymer blend composition may optionally include one or more compatible additives including, but not limited to, processing aids, fillers, antioxidants, coupling agents, uv absorbers or stabilizers, antistatic agents, nucleating agents, slip agents, plasticizers, lubricants, viscosity control agents, tackifiers, anti-blocking agents, surfactants, extender oils, acid scavengers, flame retardants, and metal deactivators, adjuvants, and colorants or pigments. Such additives may be used in desired amounts to achieve their desired effects. The additives other than the filler are generally used in an amount ranging from 0.01 wt% or less to 10 wt% or more based on the total weight of the composition. Fillers are generally added in larger amounts, but such amounts can range as low as 0.01 wt% or less to 65 wt% or more based on the total weight of the composition.

Illustrative examples of fillers include, but are not limited to, clays, precipitated silicas and silicates, fumed silica, talc, titanium dioxide, calcium carbonate, ground minerals, alumina trihydrate, magnesium hydroxide, and carbon blacks wherein the typical arithmetic mean particle size is greater than 15 nanometers (nm).

Exemplary antioxidants include: hindered phenols (e.g., tetrakis [ methylene (3, 5-di-tert-butyl-4-hydroxyhydrocinnamate) ] methane); phosphites and phosphonites (e.g., tris (2, 4-di-tert-butylphenyl) phosphate); thio compounds (e.g., dilauryl thiodipropionate); various silicones; and various amines (e.g., polymeric 2,2, 4-trimethyl-1, 2-dihydroquinoline). The antioxidant may be used in an amount of 0.1 wt% to 5 wt%, based on the total weight of the composition. In forming wire and cable compositions, antioxidants are typically added to the system prior to processing into a finished article (i.e., prior to extrusion and crosslinking).

Examples of suitable flame retardants include, but are not limited to, magnesium hydroxide, Alumina Trihydrate (ATH), calcium phosphate, titanium oxide, zinc oxide, magnesium carbonate, barium sulfate, barium borate, kaolinite, silica, and the like. In an embodiment, the composition comprises 20 vol% to 60 vol% of the one or more flame retardants, based on the total volume of the composition.

Mixing and blending

Embodiments of the present invention relate to blends of first and second interpolymers and a peroxide free radical initiator ("interpolymer blends"). The compositions can be prepared by conventional or hereinafter discovered melt compounding techniques that provide mixtures of the components as described herein, using equipment such as, but not limited to, mixers for melt blending the components, and equipment for continuous mixing procedures (including single and twin screw extruders, static mixers), as well as other machines and methods designed to provide blends of the components.

In embodiments, the blend of the first and second interpolymers can be prepared by melt compounding the first and second interpolymers and a peroxide initiator at an elevated temperature to form the interpolymer blend. In embodiments, the melting temperature is greater than room temperature (i.e., 22 ℃), but less than about 150 ℃, or 120 ℃, or 110 ℃. In an embodiment, the interpolymer blend further comprises a catalyst. Thereafter, the interpolymer blend may be extruded through a fine screen (e.g., a 500 mesh screen) via melt filtration and optionally pelletized. In other embodiments, the peroxide initiator can be combined with one or both of the interpolymers via compounding or soaking prior to combining the two interpolymers.

In embodiments, the first and second interpolymers may be combined in any concentration ratio suitable to achieve the desired result. In embodiments, the first interpolymer (comprising residues of a first comonomer having carboxylic acid and/or carboxylic anhydride functional groups) can be present in the blend at a concentration of greater than 50 wt.%, greater than 60 wt.%, greater than 70 wt.%, or greater than 75 wt.%, based on the combined weight of the first and second interpolymers, with the remainder being a second interpolymer (comprising residues of a second comonomer having epoxy functional groups) at a concentration of less than 50 wt.%, less than 40 wt.%, less than 30 w.%, or less than 25 wt.%, respectively.

In an embodiment, the first interpolymer may be present in the blend in an amount in the range of from 60 wt% to 95 wt%, or from 65 wt% to 95 wt%, or from 75 wt% to 90 wt%, based on the combined weight of the first and second interpolymer weights, with the remainder being the second interpolymer in an amount in the range of from 40 wt% to 5 wt%, or from 35 wt% to 5 wt%, or from 25 wt% to 10 wt%, respectively. In other embodiments, the first and second interpolymers can each be in the range of from 5 wt% to 95 wt% for a total of up to 100% of the polymeric components of the composition combined.

In embodiments, the concentration of the first interpolymer in the composition can be in the range of from 5 wt%, or 10 wt%, or 20 wt%, or 30 wt%, or 40 wt%, or 50 wt%, or 55 wt%, or 60 wt% up to 95 wt%, or less than (<)95 wt%, or 94.995 wt%, or 94.99 wt%, or 90 wt%, or 85 wt%, or 80 wt%, or 75 wt%, or 70 wt%, based on the total weight of the composition. In an embodiment, the first interpolymer is present in an amount from 5 wt% to 95 wt%, or from 5 wt% to <95 wt%, or from 5 wt% to 94.995 wt%, or from 5 wt% to 94.99 wt%, or from 10 wt% to 90 wt%, or from 20 wt% to 85 wt%, or from 30 wt% to 80 wt%, or from 40 wt% to 75 wt%, or from 50 wt% to 70 wt%, based on the total weight of the composition.

In embodiments, the concentration of the second interpolymer in the composition can be in the range of from 5 wt%, or 10 wt%, or 20 wt%, or 30 wt%, or 40 wt%, or 50 wt%, or 55 wt%, or 60 wt% up to 95 wt%, or less than (<)95 wt%, or 94.995 wt%, or 94.99 wt%, or 90 wt%, or 85 wt%, or 80 wt%, or 75 wt%, or 70 wt%, based on the total weight of the composition. In an embodiment, the first interpolymer is present in an amount from 5 wt% to 95 wt%, or from 5 wt% to <95 wt%, or from 5 wt% to 94.995 wt%, or from 5 wt% to 94.99 wt%, or from 10 wt% to 90 wt%, or from 20 wt% to 85 wt%, or from 30 wt% to 80 wt%, or from 40 wt% to 75 wt%, or from 50 wt% to 70 wt%, based on the total weight of the composition.

In an embodiment, the composition comprises from 5 wt% to 95 wt%, or from 5 wt% to less than (<)95 wt%, or from 5 wt% to 94.995 wt%, or from 5 wt% to 94.99 wt% of the first interpolymer (or oligomer); from 5 wt% to 95 wt%, or from 5 wt% to less than (<)95 wt%, or from 5 wt% to 94.995 wt%, or from 5 wt% to 94.99 wt% of a second interpolymer (or oligomer); and 0.005 wt% to 1.2 wt%, or greater than (>)0.16 wt% to 1.2 wt%, or 0.18 wt% to 4.0 wt% of a peroxide free radical initiator, the wt% based on the total weight of the composition.

In embodiments, at least 50 volume percent ("vol%") of the interpolymer blend may be a homogeneous blend. As used herein, the term "homogeneous blend" refers to a composition that does not have distinct interpolymer domains with an average diameter greater than 3 micrometers (μm). In embodiments, the homogeneous blend of the first and second interpolymers do not have distinct domains of the interpolymer greater than 2 μm or greater than 1 μm. The domains of the interpolymers can be evaluated by microscopic techniques such as FTIR microscopy, atomic force microscopy, scanning electron microscopy, transmission electron microscopy and other methods known to those skilled in the art. In embodiments, at least 60 vol%, at least 70 vol%, at least 80 vol%, at least 90 vol%, essentially all, or all (i.e., 100 vol%) of the interpolymer blend is a homogeneous blend.

In embodiments, when the first and second interpolymers and peroxide initiator are incorporated into a blend in the absence of a crosslinking catalyst and stored at room temperature (i.e., 22 ℃), the blend may exhibit little, if any, initial crosslinking. In the examples, the time (denoted as "T") for achieving a homogeneous blend of the first and second interpolymers and the peroxide initiator is determined by_b"), the blend can be at a temperature less than or equal to the blending temperature and above T_bFor a maximum of sixty minutes (denoted as "T_b+60 ") exhibits a gel content of less than 50%, 30% or 10%. Gel content may be determined according to astm d 2765.

In an embodiment, crosslinking of the first and second interpolymers may be performed in a cure zone having a temperature of at least 175 ℃ up to a maximum of about 260 ℃. Further, the interpolymer may be cured for a time in the range of from 2 minutes to about 30 minutes. In various embodiments, the curing zone may be hot nitrogen gas or hot steam tubes.

In an embodiment, the degree of crosslinking of the material can be determined via analysis on a moving die rheometer or a dynamic mechanical analyzer at 200 ℃, and the degree of scorch retardation at 140 ℃. The degree of crosslinking can be determined by the method described in ISO 6502. When analyzed, an increase in torque ("MH-ML"), as indicated by the difference between the maximum torque ("MH") and the minimum torque ("ML"), indicates a higher degree of crosslinking. In various embodiments, the crosslinked interpolymer has a maximum MH-ML at 200 ℃ of at least 0.4 inch-pounds (0.045 newton meters ("Nm")), at least 0.6 inch-pounds (0.068Nm), at least 0.8 inch-pounds (0.090Nm), at least 1 inch-pounds (0.113Nm), at least 1.2 inch-pounds (0.136Nm), at least 2 inch-pounds (0.226Nm), at least 3 inch-pounds (0.339Nm), or at least 4 inch-pounds (0.452Nm), up to 15 inch-pounds.

In an embodiment, the degree of crosslinking of a material can be measured by dissolving the composition in a solvent (e.g., xylene or decalin) for a specified duration and calculating the% gel or% non-extractable component, as determined according to ASTM D2765. In general, the% gel generally increases with increasing level of crosslinking. In embodiments, the composition is crosslinked to an extent so as to provide a cured article having a% gel content of at least 30 wt%, or at least 50 wt%, at least 70 wt%, or at least 90 wt%, and up to 100 wt%, based on the total weight of the composition.

Without being bound by theory, incorporation of the functional groups of the first and second comonomers into the interpolymer has advantages in terms of low volatiles after crosslinking (even if the crosslinking reaction is not 100% complete) and little or no degassing is required after crosslinking. Further, including a peroxide initiator and a crosslinking catalyst in an amount of at least 0.05 wt%, based on the total weight of the composition, provides faster curing of the interpolymer composition that does not include a peroxide initiator.

In an embodiment, the interpolymer blend comprising a peroxide initiator and a crosslinking catalyst cures to a gel content of >50 wt% in less than 2.00 minutes or less than 1.50 minutes or less than 1.13 minutes when subjected to crosslinking conditions at 200 ℃, as determined by the method described in ISO 6502.

In various embodiments, the at least partially crosslinked interpolymer blend has a volatile content of less than 1.5 wt%, less than 1.0 wt%, less than 0.5 wt%, less than 0.1 wt%, or less than 0.01 wt%, based on the total weight of the composition.

In the examples, the volatile content is measured by thermo-gravimetric analysis ("TGA") of the weight loss of the crosslinked sample in a nitrogen atmosphere. For example, a change in sample mass may follow heating the crosslinked sample from 30 ℃ to 200 ℃ at 10 ℃/min and then holding at 200 ℃ for 60 minutes. The amount of weight loss indicates the volatile content of the crosslinked material.

Illustrative examples of volatiles include water, methane, acetophenone, cumyl alcohol, and alpha-methylstyrene, among others. In an embodiment, the at least partially crosslinked interpolymer blend has a combined concentration of water, methane, acetophenone, cumyl alcohol, and alpha-methylstyrene of less than 1.5 wt%, less than 1.0 wt%, less than 0.5 wt%, less than 0.1 wt%, or less than 0.01 wt%. Such volatile concentrations can be achieved without degassing the disclosed at least partially crosslinked interpolymer blends.

Article of manufacture

The compositions of the present invention may be used to prepare a variety of articles or components or portions thereof. In embodiments, the composition including the crosslinking agent can be fabricated into an article and the temperature increased to allow crosslinking of the composition.

The compositions of the present invention may be processed into articles by any of a variety of conventional techniques and equipment. Illustrative methods include, but are not limited to, injection molding, extrusion molding, thermoforming, compression molding, rotational molding, slush molding, overmolding, insert molding, blow molding, calendering, and other processing techniques known to those skilled in the art. Films, including multilayer films, can be produced by cast or input processes, including blown film processes.

Articles include, but are not limited to, sheets, moldings, and extruded parts. Additional articles include automotive parts, weather stripping, belts, hoses, jacketing and insulation ((e.g., insulated cable) including flame retardant versions of wire and cable, cable accessories, seals, tire components, computer parts, building materials, and other applications.

In various embodiments, the interpolymer blends may be used to prepare polymeric coatings (e.g., insulation and/or jackets) for wires and/or cables. Compounding of the cable polymeric coating material (e.g., insulation) can be accomplished by standard equipment known to those skilled in the art. Examples of compounding equipment are internal batch mixers, such as Banbury^TMOr Boling^TMAn internal mixer. Alternatively, a continuous single or twin screw mixer, such as a Farrel, may be used^TMContinuous mixer, Werner and Pfleiderer^TMTwin screw mixers or Buss^TMKneading a continuous extruder.

In various embodiments, an insulated cable comprising a conductor and an insulating material comprising an at least partially crosslinked polymeric network can be prepared using the interpolymer blends described above. In one embodiment, the conductor may be at least partially surrounded with at least a portion of the cross-linkable material, and at least a portion of the cross-linkable material may be cross-linkable to provide the cross-linked insulating material. Different types of extruders (e.g., single or twin screw types) can be used to prepare cables containing an insulation layer comprising the interpolymer blend. A description of a conventional extruder can be found in USP 4,857,600. Examples of co-extrusion and extruders can thus be found in USP 5,575,965. In one embodiment, the crosslinkable material and the conductor can be coextruded to produce an extruded intermediate cable.

After extrusion, the extruded intermediate cable may be passed into a heated curing zone downstream of the extrusion die to help crosslink the interpolymer blend or terpolymer in the presence of the crosslinking catalyst described above. In an embodiment, the crosslinkable material can be crosslinked by passing the extrudable intermediate cable through a curing zone having a temperature of at least 175 ℃. In an embodiment, the heated cure zone may be maintained at a temperature in the range of 175 ℃ to 260 ℃. The heating zone may be heated by pressurized steam or inductively heated by pressurized nitrogen.

After extrusion and crosslinking, the cable may be jacketed using known cable manufacturing processes. In various embodiments, the cable is not subjected to any degassing process prior to such jacketing. Alternatively, the jacket may be extruded simultaneously with the conductor and insulation, which heretofore was not possible simultaneously with the crosslinkable insulation due to the outgassing requirements of the insulation.

The ac cable prepared according to the present disclosure may be a low voltage, medium voltage, high voltage or ultra high voltage cable. Further, the dc cables prepared according to the present disclosure include high voltage or ultra high voltage cables.

Definition of

Unless stated to the contrary, implied from the context, or customary in the art, all parts and percentages are by weight and all test methods are current as of the filing date of this disclosure.

For purposes of united states patent practice, the contents of any referenced patent, patent application, or publication are incorporated by reference in their entirety (or the equivalent us version thereof is so incorporated by reference), especially with respect to the definition in the art (to the extent not inconsistent with any definitions specifically provided in this disclosure) and the disclosure of common general knowledge.

The numerical ranges disclosed herein include all values from the lower value to the upper value (inclusive). For ranges containing exact values (e.g., 1 or 2 or 3 to 5 or 6 or 7), any subrange between any two exact values is included (e.g., 1 to 2; 2 to 6; 5 to 7; 3 to 7; 5 to 6, etc.).

"and/or" when used in a list of two or more items means that any of the listed items can be employed alone or in combination with any two or more of the listed items. For example, if the composition is described as containing components A, B and/or C, the composition may contain only a; only contains B; only contains C; a combination comprising A and B; a combination comprising A and C; a combination comprising B and C; or a combination comprising A, B and C.

"cable" and "power cable" mean at least one electrical wire or optical fiber within at least one polymeric coating material (e.g., an insulating sheath or a protective outer sheath). A cable is typically two or more wires or optical fibers bound together, typically in a common insulating and/or protective sheath. The individual wires or fibers within the polymeric coating material may be bare, covered or insulated. Combination cables may contain both electrical wires and optical fibers. The cable may be designed for low, medium and/or high voltage applications. Typical cable designs are described in U.S. Pat. nos. 5,246,783, 6,496,629, and 6,714,707.

As used herein, "composition" and similar terms mean a mixture or blend of two or more components.

The use of "including," "comprising," "having," and derivatives thereof herein is not intended to exclude the presence of any additional component, step, or procedure, whether or not the same is specifically disclosed. In order to avoid any doubt, all compositions claimed through use of the term "comprising" may include any additional additive, adjuvant, or compound (whether polymeric or otherwise), unless stated to the contrary. In contrast, the term "consisting essentially of … …" excludes from any subsequently listed range any other components, steps or procedures other than those that are not essential to operability. The term "consisting of … …" excludes any component, step, or procedure not specifically recited or listed.

As used herein, "conductor" and similar terms mean one or more wires or fibers for conducting heat, light, and/or electricity. The conductor may be a single wire/fiber or a multiple wire/fiber and may be in strand form or in tubular form. Non-limiting examples of suitable conductors include metals such as silver, gold, copper, carbon, and aluminum. The conductor may also be an optical fiber made of glass or plastic.

As used herein, "crosslinking," "vulcanization," and similar terms refer to a composition or component of a composition that is subjected or exposed to a treatment that induces crosslinking to provide an insoluble composition or component having a gel content of 50 wt% to 100 wt%. The degree of crosslinking can be measured according to ASTM 2765-84 by dissolving the composition or component in a solvent (e.g., xylene or decalin) that dissolves the composition or component prior to crosslinking for a specified duration and calculating the% gel or% non-extractable component. The% gel content generally increases with increasing level of crosslinking.

As used herein, "ethylene-based polymer," "ethylene-based interpolymer," and similar terms refer to a polymer comprising, in polymerized form, a majority weight percent (wt%) (i.e., >50 wt%) ethylene (based on the weight of the polymer) and at least one comonomer.

As used herein, the term "homogeneous blend" refers to a composition that does not have distinct interpolymer domains with an average diameter greater than 3 micrometers (μm).

"interpolymer" means a polymer prepared by polymerizing at least two different monomers. This generic term includes copolymers, which are commonly used to refer to polymers prepared from two different monomers, and polymers prepared from more than two different monomers, such as terpolymers (at least three different monomers), tetrapolymers (at least four different monomers), and the like. Interpolymers further include polymers prepared by grafting unsaturated comonomers to the polymer. For example, an ethylene polymer (such as LDPE) can be melt mixed with an unsaturated comonomer (such as maleic anhydride, acrylic acid, allyl glycidyl ether, or glycidyl methacrylate) in the presence of a peroxide or other free radical initiator to form an interpolymer.

As used herein, the term "polymer" and similar terms refer to polymeric compounds prepared by polymerizing monomers of the same or different types. Thus, the generic term polymer encompasses the term homopolymer (used to refer to polymers prepared from only one type of monomer, and it is understood that trace amounts of impurities may be incorporated into the polymer structure) and the term interpolymer as defined below. Trace impurities (e.g., catalyst residues) can be incorporated into and/or within the polymer.

As used herein, "residue" and similar terms when referring to a monomer means a portion of the monomer molecule present in the polymer molecule as a result of polymerization with or grafting to another monomer or comonomer molecule to produce the polymer molecule.

As used herein, "substantially all" and similar terms exclude any non-specified components having a concentration of greater than one part per million by weight ("ppmw"), parts per million.

As used herein, "wire" and similar terms mean a single strand of electrically conductive metal, such as copper or aluminum, or a single strand of optical fiber.

Test method

Density.As provided herein, in g/cm³Polymer density in units is determined according to ASTM International ("ASTM") method D792.

Gel content.The gel content (insoluble fraction) was determined according to ASTM D2765 by extraction in boiling decalin at 180 ℃ for 5 hours.

Melt index.Melt index (I) provided herein₂) Measured according to ASTM method D-1238. Unless otherwise indicated, melt index (I)₂) Measured at 190 ℃/2.16kg and reported in grams eluted per 10 minutes or decigrams eluted per minute (dg).

Polydispersity index (PDI) or Molecular Weight Distribution (MWD)."polydispersity index" (PDI) or "molecular weight distribution" (MWD) is the weight average molecular weight/number average molecular weight (M)_w/M_n) As determined by gel permeation chromatography. Molecular weight (M)_w) Expressed as g/mol.

Examples of the invention

Material

In the examples detailed below, the following materials were employed:

table 1: material

Study 1

The following study was conducted to evaluate the curing of samples using a conventional peroxide-initiated crosslinking reaction versus the curing of samples using a hybrid curing system via a peroxide and epoxy/anhydride initiated crosslinking reaction according to the present invention.

Sample preparation

Using DSMsA twin screw micro-compounder prepared polymer blends according to the formulation provided in table 2 below. The micro-blender was started at a set point of 220 ℃ with a rotor speed of 30 rpm. A pre-weighed amount of component "A" anhydride functionalized PE terpolymer (LOTADER)^TM3210) In N₂Added to the rotating mixing rotor of the micro-compounder under purge. After heating at 220 ℃ for 30 minutes, the component "A" terpolymer material was cooled to 115 ℃. Subsequently, an epoxy-functionalized PE copolymer (LOTADER) is added as component "B^TMAX 8840) copolymer and blended with the component "a" terpolymer at 30rpm for 3 minutes. Component "C" MPI catalyst was then added and the composite blended for 5 minutes at 30 rpm. Component "D" peroxide concentrate blend (HFDB 4201) was then added and the composite blended for 5 minutes at 30 rpm. The DSM compound was stopped and a sample was collected. Samples of the polymer blend were formed into 2mm and 0.1mm thick polymer films using a Carver press. The forming temperature was 115 ℃ and the applied forming pressure was 20,000 psi. The integral forming process time is less than 3 min.

Table 2 summarizes the formulations of four test samples according to the invention (TS1, TS2, TS3, TS4) and two comparative samples (CS1, CS 2).

TABLE 2

Comparative sample CS1 was cured by an epoxy/anhydride crosslinking reaction alone. In contrast, inventive samples TS1 through TS4 were cured by peroxide and epoxy/anhydride initiated crosslinking reactions using a hybrid cure system.

Curing-scorching balance.The cure-scorch balance is determined by dividing the cure level by the scorch level. In general, for a given level of scorch, a higher level of cure is desired, and thus a high cure-scorch balance is desired.

The cure level and the scorch level are in pascals (Pa) as determined by storage modulus via Dynamic Mechanical Analysis (DMA). The degree of crosslinking ("cure level") of the sample was determined via DMA analysis on a TA instrument (TA Instruments) AR-G2 rheometer at 1.1 minutes and 200 ℃, with 200 ℃ being the typical temperature in a CV tube, and the 1.1 minute being the typical time period required for the crosslinking reaction of the insulation to reach 90% cure (T90) using conventional peroxide initiation in the rheometer at 200 ℃. According to the analysis, an increase in storage modulus as indicated by the difference between the maximum storage modulus and the minimum storage modulus indicates a higher degree of crosslinking.

The degree of scorch ("scorch level") was determined on an AR-G2 rheometer at 40 minutes and 140 ℃, said 140 ℃ being the typical temperature for cable extrusion, and said 40 minutes being the typical time period for scorch using a conventional peroxide-initiated crosslinking reaction of insulation in the rheometer at 140 ℃.

The results in table 2 show that the use of hybrid peroxide and epoxy/anhydride initiated crosslinking systems in TS1 to TS4 produced a disproportionate increase in final cure (i.e., 90% cure) compared to the scorch level, and thus a much higher balance between scorch and final cure (i.e., cure-scorch balance) than the comparative sample CS1 of the epoxy/anhydride initiated crosslinking system alone.

Peroxide levels.Comparative sample CS2 and test samples TS1 through TS4 were cured by a peroxide and epoxy/anhydride initiated crosslinking reaction using the hybrid cure system according to the present invention, wherein a peroxide initiator was used in the test samples (i.e., 0.1 based on the total weight of the composition6 wt% to 0.36 wt% peroxide).

The results further show that when low amounts of peroxide are used as part of the hybrid peroxide and epoxy/anhydride initiated cure system (i.e., 0.16 wt% peroxide based on the total weight of the composition), insufficient cure is obtained, as indicated by the very low cure level of comparative sample CS 2.

Study 2

The following study was conducted to evaluate the volatile (by-product) content of samples cured using a conventional peroxide-initiated crosslinking reaction (CS3) versus samples cured using a hybrid curing system according to the present invention via a peroxide and epoxy/anhydride initiated crosslinking reaction.

Sample preparation

Using DSMsA twin screw micro-compounder prepared polymer blends as shown in table 3 below. The micro-blender was started at a set point of 200 ℃ with a rotor speed of 30 rpm. A pre-weighed amount of component "A" anhydride functionalized PE terpolymer (LOTADER)^TM3210) In N²Added to the rotating mixing rotor of the micro-compounder under purge. After heating for 30 minutes, the terpolymer of component "A" (LOTADER)^TM3210) Cooling to 120 ℃. Subsequently, component "B" epoxy-functionalized PE copolymer (LOTADER)^TMAX 8840), component "C" MPI catalyst (for sample TS5), and component "D" peroxide concentrate to component "A" terpolymer (LOTADER)^TM3210) A material. The polymer blend was compounded at 120 ℃ for 5 minutes. Samples of the blend were then extruded through a micro-compounder and stored under anhydrous conditions.

Compression moulding to prepare sheets for DMA analysis

A portion of each of the polymer blend samples was compression molded into 2mm x 0.1mm thick polymer films using a Carver laboratory press and cured. The forming temperature was 115 ℃ and the applied forming pressure was 20,000 psi. The overall forming process time is typically less than 3 min.

Table 3 summarizes the formulations of test samples TS5 and TS6 cured using the hybrid curing system according to the present invention and a comparative sample CS3 cured by peroxide-initiated crosslinking reaction alone.

TABLE 3

Thermogravimetric analysis (TGA) of volatile by-product content

To evaluate the volatile (by-product) content of the crosslinked samples (CS3, TS5, TS6), the total weight loss of the samples was determined by thermogravimetric analysis (TGA) using a temperature ramp of 10 ℃/min to 200 ℃ and holding at a temperature of 200 ℃ for 60 minutes. The results are shown in figure 1.

The TGA data show that samples TS5 and TS6 cured using a cure system containing peroxide and epoxy/anhydride initiated crosslinking reactions according to the present invention have only 0.25 wt% volatile by-product content. This is a 84.38% reduction in volatile byproducts as compared to sample CS3, which was crosslinked by a conventional peroxide-initiated crosslinking reaction and had a volatile byproduct content of 1.60 wt%.

It is specifically intended that the present invention not be limited to the embodiments and illustrations contained herein, but include modified forms of those embodiments including portions of the embodiments and combinations of elements of different embodiments as come within the scope of the following claims.

In summary, the present application includes, but is not limited to, the following:

1. a composition comprising

A. A first interpolymer or oligomer comprising ethylene monomer residues and residues of a first comonomer having one or more functional groups selected from the group consisting of carboxylic acid and carboxylic acid anhydride;

B. a second interpolymer or oligomer comprising ethylene monomer residues and residues of a second comonomer having epoxy functionality; and

C. a peroxide free radical initiator.

2. The composition of item 1, comprising:

5 to 94.995 wt% of the first interpolymer or oligomer;

5 to 94.995 wt% of the second interpolymer or oligomer; and

0.005 to 1.2 weight percent of the peroxide free radical initiator;

the wt% is based on the total weight of the composition.

3. The composition of item 2, comprising from 0.18 wt% to 0.40 wt% of the peroxide free radical initiator, the wt% based on the total weight of the composition.

4. The composition of item 1, further comprising a catalyst.

5. The composition of item 4, comprising 0.005 to 1.2 wt% of the catalyst.

6. The composition of item 4, wherein the molar ratio of catalyst to epoxide is in the range of 1:240 to 2: 15.

7. The composition of item 1, wherein:

the first interpolymer has an anhydride content of from 0.1 wt% to 10 wt%; and is

The second interpolymer has an epoxide content of 0.1 wt% to 10 wt%.

8. The composition of item 1, wherein the epoxide to anhydride molar ratio is in the range of 12:1 to 1: 12.

9. The composition of item 1, wherein:

the first comonomer comprises acrylic acid, methacrylic acid, or maleic anhydride, or a combination thereof; and is

The second comonomer comprises glycidyl acrylate, glycidyl methacrylate, or allyl glycidyl ether, or a combination thereof.

10. The composition of item 1, wherein the first interpolymer comprises residues of the first comonomer from 1 to 10 wt%, and

the second interpolymer comprises from 1 to 10 weight percent of residues of the second comonomer.

11. A crosslinked composition formed from the composition of any one of the preceding claims.

12. The crosslinked composition of item 11, having a volatiles content of less than 1.0 wt.%.

13. An article comprising at least one component formed from the composition according to any one of the preceding claims.

14. A method for preparing a crosslinked insulating material, the method comprising:

crosslinking at least a portion of a crosslinkable material comprising the composition according to any one of items 1 to 10 and a catalyst at a temperature of 175 ℃ to 260 ℃ to provide a crosslinked insulating material.

15. The method of item 14, wherein the composition has a gel content of >50 wt% in less than 1.5 minutes at a cure temperature of 200 ℃, as measured according to ISO 6502.