WO2009020554A2

WO2009020554A2 - Compositions for compounding and extrusion of foamed fluoropolymers

Info

Publication number: WO2009020554A2
Application number: PCT/US2008/009285
Authority: WO
Inventors: Charles A. Glew
Original assignee: Glew Charles A
Priority date: 2007-08-03
Filing date: 2008-08-01
Publication date: 2009-02-12
Also published as: WO2009020554A3

Abstract

The disclosure provides a composition or set of compositions and method for producing cellular or foamed or blown perfluoropolymers or fluoropolymers and other thermoplastics to create a lower cost communications cable, conductor separator, conductor support-separator, jacketing, tape, wire insulation and in some cases a conduit tube as individual components or combined configurations that exhibit improved electrical, flammability and optical properties. Specifically, the foamable or blown perfluoropolymer cellular insulation composition comprises a composition comprising; talc and the selected perfluoropolymer or perfluorpolymers. A single compounded pellet or product resulting in cellular or foamable products has also been realized by providing the melt combination of only talc and a perfluoropolymer.

Description

Compositions for Compounding and Extrusion of Foamed Fluoropolymers

This Non-Provisional Application claims benefit under 35 U.S.C. 119(e) of Provisional Application No. 60/963,322, filed August 3, 2007 and titled: "Compositions for Compounding and Extrusion of Foamed Fluoropolymers for Wire and Cable Applications".

FIELD OF INVENTION

Wire and cable applications, especially those using copper conductors, utilize the insulative properties of specific polymers over the conductors as insulation and over the entire cable core of insulated conductors as jackets. Cable fillers of varying shapes and size are used as well for their insulative properties and more specifically in communications designs to minimize pair-to-pair crosstalk within a cable as will as mitigating crosstalk between adjacent cables which is commonly referred to as "alien crosstalk." Jackets and cable fillers provide mechanical and physical properties as well as an ever evolving requirement for enhanced fire performance i.e. (reduced flame spread, ignitability, and smoke evolution.) These mechanical, physical and fire retardancy performance requirements apply to fiber optic cables as well. Cable design demands a balance of these performance requirements and the attributes of processing a cellular that improves both insulation values e.g. (lower crosstalk in communications cables) while lowering material content and therefore the amount of combustible materials used in a cable. These added performance characteristics through cellular (or microcellular) foaming can additionally lower cost of the overall cable design.

BACKGROUND OF INVENTION

Communication cables have evolved continuously over the years as we have evolved from a voice -based telecommunication network environment to the new structured cabling designs for high-speed data transmission which are commonly referred to as Local Area Networks or LAN's. Technical requirements, standards and guidelines of the Telecommunication Industry Association and Electronic Industry Association (TIA/EIA) and International Standard Organization (ISO) have been developed and published to support high-speed data communication of voice, internet and video. In addition, these requirements continue to evolve with more and more stringent electrical performance needs such that cellular foam insulation and fillers play an increasing role in the cable designs. The primary communications cable designs incorporate twisted copper pairs together to form a balanced transmission line, coaxial cables, and fiber optic cables. All of these cables may be run in a network of a building (LAN's) as separate functional cables or in hybrid or combination cable design.

Furthermore, TIA/EIA has defined standards that are published and recognized as well as industry drafts of soon-to-be published standards for commercial building telecommunication networks. Table 1, which follows, provides those published and pending, or soon-to-be adopted and published Technical Service Bulletin "TSB" standards.

Table 1 - TIA/EIA Standards

Each of the standards of Table 1 illustrates continued widened bandwidth enabling greater data transmission. The broadening of communication cable bandwidth enhances the electrical characteristics or data bit rate based on the evolving needs of software, hardware and video transmission. The terminology within the standards for testing can be defined as electrical performance within the cable as measured by impedance, near end and far end crosstalk (NEXT & FEXT), attenuation to crosstalk ratio (ACR), ELFEXT, ELNEXT, Power Sum, etc., and the electrical performance that may be transferred to the adjacent cable a.k.a. (alien cross talk) which are measured within similar performance parameters while incorporating a power sum alien cross talk requirement. Electromagnetic noise that can occur in a cable that runs alongside one or more cables carrying data signals can create alien crosstalk. The term "alien" arises from the fact that this form of Crosstalk occurs between different cables in a group or bundle, rather than between individual wires or circuits within a single cable. Alien Crosstalk can be particularly troublesome because of its effect on adjacent 4 pair cables which degrades the performance of a communications system by reducing the signal-to-noise ratio. Traditionally, alien crosstalk has been minimized or eliminated by aluminum Mylar^R shields and/or braid in shielded cable designs i.e. (Category 7 or ISO Class F shielded designs) to prevent electromagnetic fields from ingress or egress from the cable or cables. The use of foamed or blown constructions for symmetrical and asymmetrical airspace designs further improve electrical performance characteristics in that the overall modulus and elasticity of the resulting foamed compounds are reduced leading to final conformations that more closely approach optimal geometries. Specifically, the ability to form inner structures of cables such that these inner structures have little or no plastic memory once the cabling process is completed, ensures that the nested pairs remain in the desired geometric configuration and that the use of foamed fillers, insulations and jackets using air as an insulator act to mitigate alien crosstalk in Unshielded Twisted Pair (UTP) designs i.e. (Category 6 or ISO Class E and Category 6 Augmented or ISO Class E_A).

These Electrical Performance Standards especially for UTP cables (Category 5e, 6, 6 A and 7) necessitate improved insulative performance wherein foamed perfluoropolymers optimize their inherently excellent insulative values i.e. (dielectric constant and dissipation factor.) Foamed perfluoropolymers offer lower cost and lower material content while improving fire retardancy performance by lowering the amount of combustible material in a cable and the overall fire load of Local Area Network cables within a building.

A brief review of the Fire Performance Requirements both in North America and Globally follows:

In 1975, the National Fire Protection Agency (NFPA) recognized the potential flame and smoke hazards created by burning cables in plenum areas, and adopted within the United States, the National Electric Code (NEC), and a standard for flame retardant and smoke suppressant cables. This standard, commonly referred to as "the Plenum Cable Standard", was later adopted for North America Communications Cabling by Canada and Mexico. The standard permits the use of power-limited type cables that includes communication cables without conduit, so long as the cable exhibits low smoke and flame retardant characteristics. The test method for measuring these characteristics is commonly referred to as the Steiner Tunnel Test. The Steiner Tunnel Test has been adapted for the burning of cables according to the following test protocols: NFPA 262, Underwriters Laboratories (U.L.) 910, or Canadian Standards Association (CSA) FT-6. The test conditions for each of the U.L. 910 Steiner Tunnel Test, CSA FT-6, and NFPA 262 are as follows: a 300,000 BTU/hour flame is applied for 20 minutes to a calculated number of cable lengths based on their diameter that fills a horizontal tray approximately 25 feet long with an enclosed tunnel. This test simulates the horizontal areas (ceilings) in buildings wherein these cables are run.

The criteria for passing the Steiner Tunnel Test UL 910/NFPA 262 are as follows:

A. Flame spread — a maximum flame spread of less that 5.0 feet.

B. Smoke generation:

1. A maximum optical density of smoke less than 0.5.

2. An average optical density of smoke less than 0.15.

The premise of the standard is based on the concerns that flame and smoke could travel along the extent of a building plenum area if the electrical conductors and cable were involved and were not flame and smoke resistant. The National Fire Protection Association ("NFPA") developed the standard to reduce the amount of flammable material incorporated into insulated electrical conductors and jacketed cables. Reducing the amount of flammable material would, according to the NFPA, diminish the potential of the insulating and jacket materials from spreading flames and evolving smoke to adjacent plenum areas and potentially to more distant and widespread areas within a building. The cellular foam fluoropolymer products of this disclosure can typically reduce the quantity of combustible materials by 30 to 60% based on the extent of the foaming process within insulations, fillers and jacket materials.

The products of the present disclosure have also been developed to support the possible adoption of a new NFPA standard referenced as NFPA 255 entitled "Limited Combustible Cables" with less than 50 as a maximum smoke index and NFPA 259 entitled "Heat of Combustion" which includes the use of an oxygen bomb calorimeter that allows for materials with less than 3500 BTU/lb. for incorporation into cabling systems and buildings wherein survivability of the communication network from fires is required i.e. (military installation such as the Pentagon in Washington D.C.). For these applications requiring survivability from flame spread and smoke generation, the cellular products of the present disclosure will be an effective method for reducing material content and the fuel load of cables in such critical environments.

Table 2 provides a hierarchy of fire performance standards for North America and Europe. Table 2 - Flammability Test Methods and Level of Severity for Wire and Cable

SUMMARY OF THE INVENTION

In the present disclosure the term blowing agent(s) and foaming agent(s) are synonymous and may be used interchangeably and are associated with chemical reactions. The term nucleating agent(s) are used in materials that provide sites for the formation of cells resulting blowing agents or the use of gas injection

The present disclosure provides for the use of talc or talc derivatives which are natural or synthetic hydrated magnesium silicate.

The present disclosure refers to talc as natural or synthetic hydrated magnesium silicate. It has been discovered that talc acts independently as a chemical blowing agent in combination with the perfiuoropolymers and fluoropolymers of the present invention without the need for additional blowing agents or the need for any nucleating agent. In certain cases, the talc is used to produce the fluorinated polymeric foamable pellets from which foamed products may be obtained, where the pellets contain talc that acts as a chemical blowing agent and in some cases as a nucleating agent when the pellets are heated and extruded.

The embodiments within this disclosure reference talc as a chemical blowing agent as well as a nucleating agent except where otherwise noted. The use of talc in combination with the use of a chemical blowing agent or gas injection is also included in the scope the present disclosure.

This disclosure provides a composition, method and system for producing foamed or blown cellular insulation articles utilizing fluorinated polymers (either perfluoropolymers or fluoropolymers) to create a lower cost communications cable, conductor separator, conductor support-separator, jacketing, tape, tube, cross web, wrap, wire insulation and as well as a conduit tube for individual components or several combined configurations that exhibit improved electrical, flammability and optical properties.

The foamed perfluoropolymers disclosed yield the inherent benefits of reducing the amount of combustible materials within a cable as well as enhancing electrical properties while reducing costs. The blown, foamed or cellular perfluoropolymers or fluoropolymer insulation, jacket, or filler material using a nucleating/foaming agent of talc the chemical composition of which includes MgSiOH; 3MgO+4SiO₂+H₂O; MgOH+H₂O+SiOH or any derivatives thereof) that synergistically reacts with the perfluoropolymers at their elevated or higher extrusion operating temperatures with or without a chemical blowing agent or gas blowing agent. The nucleating/foaming agent of talc creates a foam ideally suited for the requirement of Category 6 and 6A UTP insulation, jacket, or fillers i.e. (crosswebs, circular profiles, tubes and tapes) and is a highly cost effective replacement for the traditionally used Boron Nitride (nucleating agent) vs which costs approximately $60.00 per Ib. versus the cost per Ib. of talc (a chemical blowing agent and it may also act as a nucleating agent) of approximately $1.00 per Ib.

The cost reduction benefit due to the change from Boron Nitride to talc is further enhanced by the fact that insulation, jacketing and filler extrusion may be performed by a relatively simplistic and robust chemical reaction that uses varying extrusion temperatures to foam at various desired percentages based on varying talc loadings. Noteworthy, under specific extrusion conditions which are described in further detail, talc itself "foams". Traditional foaming of perfluoropolymers has been via a gas injection extrusion process and the use of nucleated perfluoropolymers with Boron Nitride. The cost benefits of chemical foaming visa-vis gas foaming of perfluoropolymers enable standard high temperature extruders to run foam perfluoropolymers without the need to port the barrel with a highly sophisticated gas valve, as well as the design and use of a specialized decompression screw. The use of talc also works effectively with traditional gas injection extrusion processes.

An added benefit of using talc is that it neutralizes the acidity of hydrogen fluoride (HF) which may evolve during extrusion. HF is highly acidic and causes corrosion in extrusion barrels, screws and extrusion head, tools and dies. Traditional metals or non-Hasteloy or Inconel surfaces cannot be used to extrude perfluoropolymers under normal process conditions and the use of talc significantly reduces the acidity of the HF, thus mitigating corrosive wear on standard extrusion equipment.

The introduction of talc has the benefit of being an acid (HF) scavenger when compounded into pellets prior to extrusion and acts as both a nucleating as well as a foaming agent. Furthermore, when enhanced with the addition of a pelletized perfluoropolymer with MgCO₃ and CaCO₃ and AClyn^® wax (a registered trademarked wax provided by Honeywell) perfluoropolymer foaming levels are further enhanced. This foaming agent of magnesium carbonate and calcium carbonate may be added as a separate pellet in a tumble blended mix or compounded together in a single homogenous pellet of talc (MgSiOH) and MgCO₃/CaCO₃/ AClyn wax. The single homogenous pellet can then be extruded for insulations, jackets, or fillers in a very simplistic chemically foamed extrusion process for perfluoropolymers. The foaming rate from 20% to 50% can be raised or lowered based on the percentage of each constituent used as well as by adjustments in extrusion temperatures.

The perfluoropolymers that are characterized here are the melt processable materials for which this disclosure is focused:

1. FEP (Fluorinated Ethylene Propylene)

2. PFA (Perfluoroalkoxy)

3. MFA (Polytetrafluoroethylene-Perfluoromethylvinylether) It should be emphasized that the use of talc may be independent of the use of MgCCVCaCO₃/ AClyn wax or talc may be used in any combination with MgCCVCaCO₃/ AClyn wax to produce the desired foamed compositions.

The perfluoropolymers described are fluoropolymer resins that can be used and include copolymers of TFE with one or more copolymerizable monomers chosen from perfluoroolefins having 3-8 carbon atoms and perfluoro (alkyl vinyl ethers) (PAVE) in which the linear or branched alkyl group contains 1-5 carbon atoms. Preferred perfluoropolymers include copolymers of TFE with at least one hexafluoropropylene (HFP) unit and one PAVE (unit). Preferred comonomers include PAVE in which the alkyl group contains 1-3 carbon atoms, especially 2-3 carbon atoms, i.e. perfluoro (ethyl vinyl ether) (PEVE) and perfluoro (propyl vinyl ether) (PPVE). Additional fluoropolymers that can be used include copolymers of ethylene with TFE, optionally including minor amounts of one or more modifying comonomer such as perfluorobutyl ethylene. Representative fluoropolymers are described, for example, in ASTM Standard Specifications D-2116, D-3159, and D-3307. Such fluoropolymers are non-functional fluoropolymers if they have essentially no functional groups, but are functionalized fluoropolymers if functional groups are added, e.g., by grafting. Alternatively or additionally, preferred fluoropolymers are non-elastomeric, as opposed to elastomeric.

Functionalized fluoropolymers include fluoropolymers such as those described in the foregoing paragraph and additionally containing copolymerized units derived from functional monomers. If the concentration of functional monomer is high enough in a TFE copolymer, however, no other comonomer may be needed. Usually, but not necessarily, the functional groups introduced by such monomers are at the ends of pendant side groups. Functional monomers that introduce pendant side groups having such functionality can have the general formula CYZ wherein Y is H or F and Z contains a functional group. Preferably, each Y is F and ~Z is --Rf —X, wherein Rf is a fluorinated diradical and X is a functional group that may contain CH2 groups. Preferably, Rf is a linear or branched perfluoroalkoxy having 2-20 carbon atoms, so that the functional comonomer is a fluorinated vinyl ether. Examples of such fluorovinylethers include CF₂ CF[OCF₂ CF(CF₃)Jm ~O-(CF₂)n CH₂ OH as disclosed in U.S. Pat. No. 4,982,009 and the alcoholic ester CF₂ -CF[OCF₂ CF(CF₃)Jm -O~(CF₂)n ~ (CH₂)P --O--COR as disclosed in U.S. Pat. No. 5,310,838. Additional fluorovinylethers include CF₂CF[OCF₂ CF(CF₃)Jm O(CF₂)n COOH and its carboxylic ester CF₂CF[OCF₂ CF(CF₃)]m O(CF₂)n COOR disclosed in U.S. Pat. No. 4,138,426. In these formulae, m=0-3, n=l-4, p=l-2 and R is methyl or ethyl. Preferred fluorovinylethers include CF₂CF-O-CF₂ CF₂ -SO₂ F; CF₂ CF[OCF₂ CF(CF₃)] O(CF₂)₂ -Y wherein -Y is -SO₂ F, -CN, or -COOH; and CF₂-CF[OCF₂ CF(CF₃)]O(CF₂)₂ -CH₂ -Z wherein -Z is -OH, -OCN, -0-(CO)-NH₂, or -OP(O)(OH)₂. These fluorovinylethers are preferred because of their ability to incorporate into the polymer backbone and their ability to incorporate functionality into the resultant copolymer.

One embodiment is the use of talc at 7% by weight combined with 93% neat resin.

One embodiment is that foaming will occur with the use of talc at 10% by weight with 90% neat resin.

Pellets of the compounds described above can be created at 600-610 Deg F and under certain conditions as low as 570 F within the extruder barrel.

One embodiment of the present application includes a first composition comprising a foaming agent comprising perfluoropolymer plus talc or other talc derivative (which may include Mg₃Si₄Oi₀(OH)₂; 3MgO+4SiO₂+H₂O; MgOH+H₂O+SiOH which is blended, melted and extruded into a pelletized form for extrusion that allows for blowing or foaming with or without gas injection and with or without another chemical foaming agent.

A specific embodiment includes mixtures of a foaming agent comprising perfluoropolymer pellets (85%) and talc (15%) which is compounded together via heating to a selected melting point and extruded into a pelletized form, tumble blended in pelletized form for subsequent extrusion such that the pellets are placed in an extruder, heated to a selected melting point allowing for manufacture of blown or foamed insulative components.

An additional composition may be used exclusively as a foaming agent with nucleating capabilities in a tumbled blend of 30% foaming agent and 70% perfluoropolymer pellets.

An additional embodiment includes the composition comprising a singular perfluoropolymer or a mixture of different perfluoropolymers or recycled perfluoropolymers wherein the recycled perfluoropolymers comprise from 1-100% of the perfluoropolymers. In another embodiment of the composition, additional nucleating agent may be used in combination with the talc in an amount from 1% to 10% by weight.

In another embodiment the composition comprises talc in an amount from 2% - 20% by weight.

Another embodiment includes the talc of the composition, during blowing or foaming, reacting synergistically with another composition to form smaller, more uniform cell structures in the foamed or blown other composition.

Additionally an embodiment is where the composition comprises 100% non-recycled talc powder combined with 100% non-recycled perfiuoropolymer wherein the ratio of talc to perfiuoropolymer is 0.5% - 20% by weight.

In another embodiment the talc and/or the perfiuoropolymer may be recycled or virgin.

Another embodiment includes the extruded fourth composition comprising a foamed or blown cell structure wherein the cell structures are consistent and as small as 0.0005 inches to 0.003 inches with an average size of 0.0008 inches.

In another embodiment the composition comprises talc in an amount from 0.5% - 20% by weight wherein the talc and/or perfiuoropolymer may be recycled materials.

Another added benefit of using talc is that it neutralizes the acidity of hydrogen fluoride (HF) which may evolve during extrusion. HF is highly acidic and causes corrosion in extrusion barrels, screws and extrusion head, tools and dies. Traditional metals or non-Hasteloy or Inconel surfaces cannot be used to extrude perfluoropolymers under normal process conditions and the use of talc significantly reduces the acidity of the HF, thus mitigating corrosive wear on standard extrusion equipment.

In another embodiment the composition comprises inorganic or organic salt(s) and a perfiuoropolymer. In another embodiment the cellular insulation is 100% recyclable.

Another embodiment is that the composition may comprise either inorganic or organic additives or both that includes inorganic salts, metallic oxides, silica and silicon oxides as well as substituted and unsubstituted fullerenes.

Also in an embodiment the composition is capable of meeting specific fiammability and smoke generation requirements as defined by UL 910, UL 2424, NAPA 262, 259, 255, and EN 50266-2-x, class B test specifications.

Another embodiment includes the use of a twin-screw extruder for melting, blending and pelletizing the composition. In more detail, the compounding process utilizes a two-step system to insure the foaming components are thoroughly distributed and dispersed in the base polymer of the final compound. The first step requires a masterbatch blend be made of the foaming agents. The foaming agents are in a fine powder form and a high intensity blender, (i.e. Henschel type) is used to prepare the powder blend according to the specified formulation. A certain amount of resin, also in powder form, can be used in the first blending step as a mechanism to predisperse the foaming agents and aid in the second extrusion compounding step. The second stage of the compound preparation process utilizes a twin screw extrusion compounding system to incorporate the foaming agent masterbatch blend with the base resin. The design of the compounding screw is such that there is sufficient heat and mechanical energy to fully thermally melt the base polymer and incorporate the masterbatch blend with proper distribution and dispersion during mixing for homogeneity, but yet mild enough to keep the processing temperature of the compound below that in which foaming may be prematurely initiated. The final compound can be strand extruded and pelletized or alternatively an underwater pelletizing technique may be used (in other words air or water cooling is acceptable).

Another embodiment is a method and system for heating the talc powder and a selected pelletized perfluoropolymer or fluoropolymer creating a melt blendable composition, extruding the molten composition, cooling the molten composition and forming the solid composition into a pelletized nucleating and foaming agent. Another embodiment includes a communications cable, conductor separator, conductor support-separator, jacketing, tape, wrap, wire insulation and in some cases a conduit tube individually comprising the same blown or foamed composition or may utilize the composition that includes selected perfluoropolymers or fluoropolymers.

Another embodiment of the disclosure includes the use of a foamed core and/or the use of a hollow center of the core, which in both cases significantly reduces the material required along the length of the finished cable. The effect of foaming and/or producing a support- separator with a hollow center portion should result in improved flammability of the overall cable by reducing the amount of material available as fuel for the UL 910 test, improved electrical properties for the individual non-optical conductors, and reduction of weight of the overall cable.

A method and system wherein the blown and/or foamed perfluoropolymer composition, cable, support-separator, conduit tube, insulation, jacketing, wrapping and/or taping line speeds are at or about 75 to 1500 ft/min.

Additional benefits of the embodiments include reduction of the overall material mass required for conventional spacers, insulation and jacketing which contributes to flame and smoke reduction.

Another embodiment of the disclosure includes the using this foam process, with either chemical or gas foaming, and placing the foam skin with both being the same materials e.g. (Perfluoropolymers) in a coextrusion or a second extrusion of a thermoplastic non- fluoropolymer as a skin or encapsulated by a layer of foam or solid perfluoropolymer skin as an insulation, cable filler or jacket.

In an embodiment of the present disclosure it has been found that talc, generally known as a nucleating agent in foamed plastics, exhibits blowing agent properties without the presence of a blowing agent.

Another embodiment combines talc, as a blowing agent, with resin(s) in the absence of any additional chemical blowing agent wherein the talc comprises 2-50% by weight of the resin and wherein the resulting composition is extruded into an extrudate product. In another embodiment the talc is combined with a resin as a masterbatch in a percentage of up to 15% talc by weight to resin and extruded as a pellet.

In another embodiment the talc is combined with a recycled resin as a masterbatch in a percentage of up to 20% talc by weight to recycled resin and extruded as a pellet.

In another embodiment the resin(s) may be perfluoropolymers as a subset of fiuoropolymers FEP, MFA, PFA perfluoropolymers or semicrsytalline fluoroploymers ECTFE, etfe pvdf, etc as pure resin, recycled resin, as a single resin or in combination with other resins.

In yet another embodiment the extrudate is a pellet, cross web, insulation, jacketing, wire insulation.

In another embodiment the extrudate is at a sufficiently low temperature so that the resin(s) are thermally constrained from foaming and subsequently extruded into pellet, jackets, separators, insulation, etc.

In another embodiment the pellets are extruded at a sufficiently high temperature so that the resin is receptive to the talc blowing agent wherein the product is a foamed article.

In another embodiment the pellets may optionally include and a color concentrate.

Another object of the disclosure is a foamed insulation comprising said composition.

Still an object of the invention is a process for manufacturing the composition.

Still another object of the disclosure is a process for manufacturing foamed insulation from the composition.

Other objects of the disclosure include recycled or waste materials to form these compositions (pelletized or otherwise), which can be processed and tumble blended with or without virgin or bare perfluoropolymer or fiuoropolymers to obtain acceptable foamable compositions after heating and extrusion. Additionally it is known that foamed or blown articles or foamed composition produced with a gas blowing agent can be used in combination with talc leading to an increase in the percentage of cellular structure within a foamed or foamable composition when the combination of talc and either a chemical or gas blowing agent is used. This works with the use of pellets that incorporate talc and where these pellets have been formed when talc and fiuorinated. polymers form pelletized extrudate. The pelletized extrudate (pellets) are then subsequently heated via extrusion, molding, etc. to form the foamed, blown or cellular articles of matter. These pellets are known as "foamable" pellets or foamable perfluoropolymer compositions that may incorporate fluoropolymers.

Additionally the pellets are suitable for foaming or blowing such that when the pellets are combined with additional one or more selected perfluoropolymers or selected fluoropolymer in an amount of 7 weight % to 70 weight % of the pellets to form an extrudate that is a foamed cellular insulation article.

Another embodiment is a method for manufacturing foamed or blown perfluoropolymer cellular insulation compositions wherein a second composition is a blowing or foaming agent comprising 20 weight percent of the first composition and 80 weight percent of the selected one or more perfluoropolymers heated to an appropriate melting point with homogeneously blending, extruding, cooling and forming into pellets using chemical or gas injection methods.

Another embodiment is an extrusion process wherein extrusion of a composition capable of forming cellular foam is extruded in an extruder wherein the extruder is specifically designed to minimize mechanical shear and increased heating mitigating premature foaming during the process of melting, blending, extruding and pelletizing said composition as well as mitigating corrosion of the extruder barrel due to passivation of acid and acidic gases provided by the use of talc with the perflouropolymers and fiourbpolymers during the extrusion process.

An additional embodiment is the perfluoropolymer compositions having been added into an extruded melt of a base perfluoropolymer resin, in sequential steps, sufficient talc to accomplish a loading of talc in a range of 0.5 to 20% in combination with perfluoropolymer resin forming compound pellets, wherein the compositions may be used for subsequent heat extrusion or molding processes and provide cellular or foamed or blown perfluoropolymer end products.

In another embodiment the compounded pellets comprise 7.5 weight % talc and 92.5 weight % perfluoropolymer resin.

The perfluoropolymer compositions may be extruded or molded into desired shapes and geometries without pelletizing, wherein the talc is acting as a chemical blowing agent and may also act as a nucleating agent, a foaming agent or both during extrusion or molding.

The foamed cellular insulation article reduces the quantity of combustible materials by 30 to 60 percent based on the extent of the foaming process, wherein the foamed cellular insulation article is achieved with or without a chemical blowing agent or gas blowing agent.

Another embodiment is a method of making a communications cable having flame retardant properties comprising the steps of; mixing the pellet(s) at a temperature of at most 600°F to ensure reaching the melting point of the polymer and melt processing such composition at a predetermined temperature exceeding 525°F to ensure reaching the required temperature of the blowing agent, extruding a metered amount of a melted composition around an advancing electrical conductor and allowing the composition to foam and expand to produce an insulated conductor with a chemically blown perfluoropolymer insulation.

The pellets comprise 7.5 weight percent of said talc and 92.5 weight percent of the perfluoropolymer or fluoropolymer.

The pellets comprise from 2 to 30 weight percent of said talc and 98 to 70 weight percent of the perfluoropolymer or fluoropolymer.

The talc or talc derivative is a chemical composition of a magnesium hydrosilicate represented by the formula; 3MgOSiO₂H₂O, wherein SiO₂ is 63.5 % wt, MgO is 31.90 % wt and H₂O is 4.75 % wt and optionally includes other minerals including magnesite, chlorite, calcite, magnetite, carbonate, and dolomite. The pellets are chemically foamed or blown via an extrusion process, a molding process or any known process requiring heat and/or pressure to achieve a commercially viable cellular product(s).

The cellular product(s) include FEP, PFA and MFA, TFE, ECTFE or PVDF the resulting foamed extrudate of which comply with fire and smoke and sheathing requirements for LAN cable.

Cellular material formed by heating pellets having a perfluoropolymer and a blowing agent consisting primarily of talc, to a temperature above the melting temperature of the perfluoropolymer, and above the required temperature of the talc.

The cellular material is formed by heating the pellets during an extrusion process.

The disclosure includes and defines a cable utilizing the compositions described above.

DETAILED DESCRIPTION OF THE INVENTION

For the purpose of the present invention, the expressions "fluoropolymer" is intended to denote any polymer comprising recurring units (R), with more than 25 wt % of recurring units (R) being derived from at least one ethylenically unsaturated monomer comprising at least one fluorine atom (hereinafter, fluorinated monomer).

The fluoropolymer comprises preferably more than 30 wt %, more preferably more than 40 % wt of recurring units derived from the fluorinated monomer.

The fluorinated monomer can further comprise one or more other halogen atoms (Cl, Br, I). When the fluorinated monomer is free of a hydrogen atom, it is designated as per(halo)fluoromonomer. When the fluorinated monomer comprises at least one hydrogen atom, it is designated as hydrogen-containing fluorinated monomer.

Non limitative examples of fluorinated monomers are notably tetrafluoroethylene (TFE), vinylidene fluoride (VdF), chlorotrifluoroethylene (CTFE), and mixtures thereof. Optionally, the fluoropolymer may comprise recurring units derived one first monomer, said monomer being a fluorinated monomer as above described, and at least one other monomer [comonomer (CM), hereinafter].

Hereinafter, the term comonomer (CM) should be intended to encompass both one comonomer and two or more comonomers.

The comonomer (CM) can notably be either hydrogenated (i.e. free of fluorine atom) [comonomer (HCM), hereinafter] or fluorinated (i.e. containing at least one fluorine atom) [comonomer (FCM), hereinafter].

Examples of suitable hydrogenated comonomers (HCM) are notably ethylene, propylene, vinyl monomers such as vinyl acetate, acrylic monomers, like methyl methacrylate, acrylic acid, methacrylic acid and hydroxyethyl acrylate, as well as styrene monomers, like styrene and p-methylstyrene.

In a embodiment of the invention, the polymer is a hydrogen-containing fluoropolymer. By "hydrogen-containing fluoropolymer" it is meant a fluoropolymer as above defined comprising recurring units derived from at least one hydrogen-containing monomer. A hydrogen-containing monomer may be the same monomer as the fluorinated monomer or can be a different monomer.

Thus, this definition encompasses notably copolymers of one or more per(halo)fluoromonomers (for instance tetrafluoroethylene, chlorotrifluoroethylene, hexafluoropropylene, perfluoroalkylvinylethers, etc.) with one or more hydrogenated comonomer(s) (for instance ethylene, propylene, vinylethers, acrylic monomers, etc.), and/or homopolymers of hydrogen-containing fluorinated monomers (for instance vinylidene fluoride, trifluoroethylene, vinyl fluoride, etc.) and their copolymers with fluorinated and/or hydrogenated comonomers.

The hydrogen-containing fluoropolymer are preferably chosen among:

TFE and/or CTFE copolymers with ethylene, propylene or isobutylene (preferably ethylene), with a molar ratio per(halo)fluoromonomer(s)/hydrogenated comonomer(s) of from 30:70 to

70:30, optionally containing one or more comonomers in amounts of from 0.1 to 30 % by moles, based on the total amount of TFE and/or CTFE and hydrogenated comonomer(s) (see for instance U.S. Pat. No. 3,624,250 and U.S. Pat. No. 4,513,129);

Vinylidene fluoride (VdF) polymers, optionally comprising reduced amounts, generally comprised between 0.1 and 15 % by moles, of one or more fluorinated comonomer(s) (see for instance U.S. Pat. No. 4,524,194 and U.S. Pat. No. 4,739,024), and optionally further comprising one or more hydrogenated comonomer(s); and mixtures thereof.

As used here, a blowing agent comprising "primarily talc" achieves at least most of its blowing function from talc. In certain exemplary embodiments wherein the blowing agent comprises primarily talc, the blowing agent is at least 30 weight percent talc. That is, in such embodiments talc is at least 30 weight percent of all materials operative as a blowing agent in the composition in the intended extrusion or other forming operation. In certain exemplary embodiments the blowing agent is at least 10 weight percent talc. In certain exemplary embodiments the blowing agent is at least 20 weight percent talc. In certain exemplary embodiments the blowing agent consists essentially of talc. In certain exemplary embodiments talc is used in combination with other blowing agents, including, e.g., boron nitride and/or other known blowing agents as well as derivatives of talc.

Working Compounding Example 1

A composition including talc (MgSiOH; 3MgO+4SiO2+H2O; MgOH+H2O+SiOH) or other talc/talc derivatives such as Mg3Si4O10(OH)₂ is sequentially added into the feeder section with base perfluoropolymer resin in a ratio of 15%-20% talc and 80%-85% perfiuoropolymer resin. The extrusion of the base resin perfluoropolymer is pelletized into a single pellet. The temperature profile for zones 1 through 6 would be as follows: 520, 530, 540, 560, 580 and 600 degrees Fahrenheit. The process temperatures of this single compound pellet with 7.5% talc and 92.5% perfluoropolymer resin is kept to a minimum to ensure no premature foaming occurs during pellet formation. The pellets are then extruded on a 30 to 1 ratio high temperature extruder with temperature zones of 525, 535, 550, 580, 640 and 660 degrees Fahrenheit for the subsequent extrusion into profiles, insulations and jackets.

Working Insulation Extrusion Example 2: A foamed perfluoropolymer insulation was extruded over 24 gage wire by using a cross head with a tip and die. The extruder was a high temperature 1 1/2 inch, 30:1 ratio device. The screw design was a 4:1 high compression screw. The line speeds were in a range from 400 fVmin. to 1500 ft/min. The screw rpm were from 12 rpm to 35 rpm with pressure ranging from 1500 psi to 2000 psi. The melt temperature was 678 F. The extruder was loaded with pellets containing 10% talc and 90% FEP. This resulted in an insulation extrudate that was 41% foamed with an average foamed cell size of 0.0007 inches.

Working Profile Extrusion Example 3

A cross web cable support-separator was manufactured with a l l/2 inch high temperature extruder using the following materials and conditions;

Use of a cross web die with a high compression screw, a line speed of 148 ft./min. at a pressure of 1700 psi with a 48 RPM screw speed and a melt temperature of 649 F. The extruder was loaded with a pellet master batch, the pellet comprising 15% talc and 85% FEP. The pellet master batch was blended in a 50:50 ratio with 100% FEP. Therefore, the final blend ratio was 50% master batch pellets and 50% FEP. This resulted in a cross web extrudate that was 40% foamed with an average foamed cell size of 0.0006 inches.

Working Profile Extrusion Example 4

A Double Helix cable support-separator was manufactured using a l l/2 inch extruder with the following materials and conditions;

A web cable support-separator was manufactured using a profile extrusion die with a high compression screw, a line speed of 75 ft./min. at a pressure of 1850 psi with a 40 RPM screw speed and a melt temperature of 646 F. The extruder was loaded with master batch pellets containing 15% talc and 85% FEP. This master batch was blended with 100% FEP. The final blend ratio was 70% master batch pellets and 30% FEP. This resulted in a web extrudate that was 33% foamed with an average foamed cell size of 0.0007 inches.

Working Insuation Extrusion Example 5

A foamed perfluoropolymer insulation was extruded over 24 gage wire by using a cross head with a tip and die. The extruder was a high temperature 1 1/2 inch, 30:1 ratio device. The screw design was a 4: 1 high compression screw. The line speeds were in a range from 300 ft/min. to 900 ft/min.. The screw rpm were from 12 rpm to 30 rpm with pressure ranging from 1500 psi to 2000 psi. The melt temperature was 680 F. The extruder was loaded with pellets containing 10% talc and 90% FEP. This resulted in an insulation extrudate that was 35% foamed with an average foamed cell size of 0.0007 inches.

Other desired embodiments, results, and novel features of the present invention will become more apparent from the following drawings, detailed description of the drawings, and the accompanying claims.

DETAILED DESCRIPTIONS

The following description will further help to explain the inventive features of the system, method and composition of the present disclosure.

The composition is comprised of magnesium silicate hydroxide, commonly known as talc and perfiuoropolymer. The ratio of talc is at or about 15 percent with the perfluoropolymer at or about 85 percent by weight, however the talc may range in concentration from 0.2 to 20 percent. The perfluoropolymer component of the composition may be MFA, FEP, or PFA, as a selected, uniform, pure fluoropolymers or perfluoropolymer or as a mixture of one or more different fluoropolymers or perfluoropolymers or 100 percent recycled and/or blended with non-recycled perfluoropolymers in any ratio from 1 to 99 percent. The composition is then placed in an extruder specifically designed to minimize heat transfer such that foaming or nucleation is not prematurely initiated and such that the composition may be melted, blended, extruded and pelletized. Additionally, an organic or inorganic salt may be added to the pellet composition.

The composition may also comprise inorganic and/or organic additives that include inorganic salts, metallic oxides, silica and silicon oxides as well as substituted and unsubstituted fullerenes.

The pellet composition may then be blended with virgin or recycled fluorinated polymers, perfluoropolymers or fluoropolymers, extruded at a temperature higher than the foaming or nucleation temperature so that foaming and nucleation occur in the fluorinated polymers. It will, of course, be appreciated that the system, method and compositions that have been described have been given simply by the way of illustration, and the disclosure is not limited to the precise embodiments described herein; various changes and modifications may be effected by one skilled in the art without departing from the scope or spirit of the invention as defined in the inventive claims.

Claims

What is claimed is:

1. A foamable perfluoropolymer composition comprising; blending talc and additional selected one or more perfluoropolymers, extruding the mixture of said talc and said perfluoropolymers into an extrudate wherein said extrudate forms pellet(s).

2. The foamable perfluoropolymer composition of claim 1, wherein said selected one or more perfluoropolymers are MFA, FEP, or PFA.

3. The foamable perfluoropolymer composition of claim 1, wherein said composition is comprised of recycled perfluoropolymer materials and wherein the recycled percentage used is between 1 and 100 percent.

4. The foamable perfluoropolymer composition of claim 1 , wherein said composition is only talc and said one or more selected perfluoropolymers or one or more fiuoropolymers.

5. The foamable perfluoropolymer composition of claim 1, wherein said composition is a foaming agent comprised of 15 percent of said talc and 85 percent of said one or more selected perfluoropolymers heated to a selected melting point, homogeneously blended, extruded, cooled and formed into said pellets.

6. The foamable perfluoropolymer composition of claim 1, wherein said talc is included in said composition in a range of 0.2 to 20 weight percent.

7. The foamable perfluoropolymer composition of claim 1, wherein said composition is comprised of organic or inorganic salt(s) and said selected one or more perfluoropolymers.

8. The foamable perfluoropolymer composition of claim 1, wherein said talc and said selected one or more perfluoropolymers or one or more selected fiuoropolymers may be recycled or virgin and which are extruded and formed into said pellets.

9. The foamable perfluoropolymer composition of claim 1, wherein said pellets are suitable for foaming or blowing such that when said pellets are combined with additional one or more selected perfluoropolymers or said one or more selected fluoropolymer in an amount of 7 weight % to 70 weight % of said pellets to form an extrudate a foamed cellular insulation article I acheived.

10. The foamable perfluoropolymer composition of claim 9, wherein said foamed cellular insulation comprises cellular cells that are in the range of 0.0005 inches to 0.003 inches with an average cell size of 0.0008 inches.

11. The foamable perfluoropolymer composition of claim 1, wherein said foamed cellular insulation is 100 percent recyclable.

12. The foamable perfluoropolymer composition of claim 1, wherein said composition includes inorganic and/or organic salt(s), metallic oxides, silica, and silica oxides, as well as substituted and/or unsubstituted fullerenes.

13. The foamable perfluoropolymer composition of claim 1, wherein said composition is capable of meeting specific flammability and smoke generation requirements as defined by UL 910, UL 2424, NAPA 262, 259, 255, and EN 50266-2-x, class B test specifications.

14. The foamable perfluoropolymer composition of claim 9, wherein said cellular insulation articles are communications cables, conductor separators, cable support- separators, wire insulation, jacketing, wraps or tapes and conduit tubes.

15. A method for manufacturing foamable perfluoropolymer compositions comprising; blending talc and a selected one or more perfluoropolymers, extruding the mixture of said talc and said perfluoropolymer into an extrudate wherein said extrudate forms pellet(s).

16. The method for manufacturing foamable perfluoropolymer compositions of claim 15, wherein selecting said one or more selected perfluoropolymers is a fluoropolymer.

17. The method for manufacturing foamable perfluoropolymer compositions of claim 15, wherein selecting said one or more selected perfiuoropolymers are MFA, FEP, or PFA.

18. The method for manufacturing foamable perfluoropolymer compositions of claim 15, wherein blending of said compositions is comprised of recycled perfluoropolymer materials wherein the recycled percentage used is between 1 and 100 weight percent.

19. The method for manufacturing foamable perfluoropolymer compositions of claim 15, wherein preparing said compositions includes said talc and said one or more selected perfiuoropolymers or said one or more selected fluoropolymers.

20. The method for manufacturing foamable perfluoropolymer cellular insulation compositions, wherein one composition includes up to 20 weight percent of a blowing or foaming agent and a second composition comprising up to 80 weight percent of one or more selected perfiuoropolymers heated to an appropriate melting point with homogeneously blending, extruding, and cooling forms pellets using chemical or gas injection methods.

21. The method for manufacturing foamable perfluoropolymer compositions of claim 20, wherein providing talc as said blowing or foaming agent is in a range of 0.2 to 20 weight percent is desirable.

22. The method for manufacturing foamable perfluoropolymer compositions of claim 20, wherein included in said compositions are organic or inorganic salt(s) and said selected one or more perfiuoropolymers.

23. The method for manufacturing foamable perfluoropolymer compositions of claim 20, wherein providing said talc and said selected one or more perfiuoropolymers are recycled talc or perfiuoropolymers or not recycled talc or perfiuororpolymers.

24. A method for manufacturing foamable perfluoropolymer compositions of claim 15, wherein said pellets provided are suitable for foaming or blowing such that when said pellets are combined with additional said selected one or more perfiuoropolymers or said one or more selected fluoropolymers using 7 weight % to 70 weight % of said pellets, an extrudate that is a foamed cellular insulation article is porvided.

25. The method for manufacturing foamable perfluoropolymer compositions of claim 24, wherein foaming said cellular insulation comprises cellular cells that are in the range of 0.0005 inches to 0.003 inches with an average size of 0.0008 inches.

26. The method for manufacturing foamable perfluoropolymer compositions of claim 24, wherein recovery of said cellular insulation provides for 100 percent recyclability.

27. The method for manufacturing foamable perfluoropolymer compositions of claim 15, wherein said composition includes inorganic and/or organic salt(s), metallic oxides, silica, silica oxides, as well as substituted and/or unsubstituted fullerenes.

28. The method for manufacturing foamable perfluoropolymer compositions of claim 15, wherein said composition meets specific flammability and smoke generation requirements as defined by UL 910, UL 2424, NAPA 262, 259, 255, and EN 50266- 2-x, class B test specifications.

29. The method for manufacturing foamable perfluoropolymer compositions of claim 24, wherein producing articles of said cellular insulation are communications cables, conductor separators, cable support-separators, wire insulation, jacketing, wraps or tapes and conduit tubes.

30. An insulation including insulation forming a separator comprising; an inner core of a non-fluoropolymer or perfluoropolymer and an outer layer covering said core comprising a foamed or foamed skinned perfluoropolymer wherein a cellular foaming extrusion process is performed using a single or dual head extruder and wherein said cellular foam is formed by chemical means, gas injection means or both chemical and gas injection means.

31. An extrusion process wherein extrusion of a composition capable of forming cellular foam is extruded in an extruder wherein said extruder is specifically designed to minimize mechanical shear and increase heating thereby mitigating premature foaming during the process of melting, blending, extruding, and pelletizing said composition as well as mitigating corrosion of the extruder barrel due to passivation of acid and acidic gases provided by the use of talc with the perflouropolymers and flouropolymers during said extrusion process.

32. Perfluoropolymer compositions comprising; adding into an extruded melt of a base perfluoropolymer resin, in sequential steps, sufficient talc to accomplish a loading of talc in a range of 0.5 to 20% in combination with perfluoropolymer resin forming compound pellets, wherein said compositions may be used for subsequent heat extrusion or molding processes and provide cellular or foamed or blown perfluoropolymer end products.

33. The perfluoropolymers of claim 32, wherein said compound pellets comprise 7.5 weight % talc and 92.5 weight % perfluoropolymer resin.

34. The perfluoropolymer compositions of claim 32, wherein said compositions may be extruded or molded into desired shapes and geometries without pelletizing, wherein said talc is acting as a chemical blowing agent and may also act as a nucleating agent, a foaming agent or both a nucleating and foaming agent during extrusion or molding.

35. The perfluoropolymer compositions of claim 1, wherein said talc neutralizes the acidity of hydrogen fluoride (HF) and provides for lubricating and mitigating corrosion in extrusion barrels, screws, extrusion heads, tools and dies.

36. The perfluoropolymer compositions of claim 35, wherein the use of said talc significantly reduces the acidity of said HF during extrusion of said perfluoroploymer compositions.

37. The foamable perfluoropolymer composition of claim 1, wherein said foamed cellular insulation article reduces the quantity of combustible materials by 30 to 60 percent based on the extent of the foaming process, wherein said foamed cellular insulation article is achieved with or without a chemical blowing agent or gas blowing agent.

38. The foamed cellular article of claim 37, wherein said gas blowing agent can be used in combination with said talc leading to an increase in the percentage of cellular structure within said foamed cellular insulation article when the combination of talc and either a chemical blowing agent or gas blowing agent is used.

39. A method of making a communications cable having flame retardant properties comprising the steps of; mixing the pellet(s) of claim 1 at a temperature of at most 600°F to ensure reaching the melting point of the polymer and melt processing such composition at a predetermined temperature exceeding 525°F to ensure reaching the required temperature for the blowing agent, extruding a metered amount of a melted composition around an advancing electrical conductor and allowing the composition to foam and expand to produce an insulated conductor with a chemically blown perfluoropolymer insulation.

40. Pellets comprising perfluoropolymer or fluoropolymer and a blowing agent consisting essentially of talc or a talc derivative, wherein said talc or talc derivative is a natural or synthetic hydrated magnesium silicate.

41. The pellets of claim 40, wherein said pellets comprise 15 weight percent of said talc and 85 weight percent of said perfluoropolymer or fluoropolymer.

42. The pellets of claim 40, wherein said pellets comprise 7.5 weight percent of said talc and 92.5 weight percent of said perfluoropolymer or fluoropolymer.

43. The pellets of claim 40, wherein said pellets comprise from 2 to 30 weight percent of said talc and 98 to 70 weight percent of said perfluoropolymer or fluoropolymer.

44. The pellets of claim 40, wherein said talc or talc derivative is a chemical composition of a magnesium hydrosilicate represented by the formula; 3MgOSiO₂H₂O, wherein SiO₂ is 63.5 % wt, MgO is 31.90 % wt and H₂O is 4.75 % wt and optionally includes other minerals including magnesite, chlorite, calcite, magnetite, carbonate, and dolomite.

45. The pellets of claim 40, wherein said pellets are chemically foamed or blown via an extrusion process, a molding process or any known process requiring heat and/or pressure to achieve a commercially viable cellular product(s).

46. The pellets of claim 45, wherein said cellular product(s) include one or more of FEP, PFA MFA, PVDF, ECTFE and PTFE, the resulting foamed extrudate of which comply with fire and smoke and sheathing requirements for LAN cable.

47. The pellets of claim 46, wherein said pellets optionally include a color concentrate.

48. Cellular material formed by heating pellets comprising perfluoropolymer and a blowing agent consisting primarily of talc, to a temperature above the melting temperature of the perfluoropolymer, and above the required temperature of the talc.

49. The cellular material of claim 48, formed by heating said pellets during an extrusion process.