CA2509691A1 - Pre-molding heat treatment of dynamic vulcanizates of fluorocarbon elastomers - Google Patents

Abstract

Methods for making processable rubber compositions containing fluorocarbon elastomers cured by polyol or phenol curative agents include an optional heat treating step before thermoplastic processing. In one aspect, a dynamic vulcanizate of a fluorocarbon elastomer containing an excess of un-reacted polyol curative agent is subject to a pre-molding heat treatment at a temperature of 150°C or above, but preferably below the thermoplastic processing temperature, for a time sufficient to drive off or decompose at least part of the un-reacted or excess polyol curative agent. After part or all of the curative agent is driven off or decomposed by the heat treatment, the heat treated material may be thereafter processed by thermoplastic techniques to form shaped articles. Advantageously, articles produced by thermoplastic processing of the heat treated dynamic vulcanizates are characterized by a low permeability to gases and vapors.

Description

Attorney Rocket No. 03-0047 (8470-000013) PRE-T~IOLDING BEAT TREATMENT OF DYNAMIC VULCANIZATES OF
FLUOROCAREON ELASTOMERS
Ilrt?RODUCTION
[000'(] The present invention xelates to processable fluorocarbon elastomer compositions and articles made from the coixlpositions.

[0002] Lured fluorocarbon elastomer compositions have a desirable combunation of stability and fluid resistance that makes them useful for applications in challenging environments. For example, they can be used as the basis for elastomeric seal materials where resistance to organic fluids is required. As such they find application in automotive applications as seals, gaskets, hoses and the like.

[0003] 'To protect the environment and improve aix quality, suppliers of seal and hose materials strive constantly to provide improved matexiah. Fuel hoses made from cured fluorocarbon elastomers must be impermeable to gasoline and other fuels during opexation to prevent release of the fuel vapors into the environrrl.ent. In addition, they must maintain a high degree of flexibility and structural integrity whet exposed to various chemical compounds associated with the fuel system. T'he cured elastomer material itself is amorphous and xelatively low density, wztlZ interconnected voids in its stricture. As a result, the material is relatively permeable to gases and vapors and so is not suitable as a hose material by itself. To overcome this drawback, composite hoses are provided containing at least one impermeable layer along with a cured fluorocarbon layer.

(0004] Dynamic vulcanizates of tluoroearbon rubbers in a thermoplastic matrix are prepared by curing a fluorocarbon elastomer in the pzesence of a curative and I

At<omey Docket ~Io. 03-0047 (8470-000013) a thermoplastic material to make a structure characterised as small particles of cured elastomer in a continuous thermoplastic phase. In a variety of applications, polyol or phenol curative agents are preferred.

[0005] The presence of unreacted excess curative agent in the dynamic w]canixates leads to difficulties during the molding or other thermoplastic operations oarried out after the curing of the fJ.uorocarbon rubber irt the vulcanization process. The high tenoperatures required to process the compositions lead to volatilization and degradation of un-reacted phenol. curative during subsequent molding or extrusion processes. The resulting off gsssin~ of volatile components leads to porous structures in articles prepared frora the vulcanizates, which are unsuitable as l.ow permeability fuel hoses and the like.

[0006] The drawback is not seen in conventional fluorocarbon rubbers cured by phenols, because there the cured composition is not further processed into shaped articles, and because any matezial that volatilizes or off gasses during a high temperature "post cure" treatment does not cause a porous structure or other Iack of structural integrity. This is because the rubber matrix, unlike the thermoplastic matrix of the dynamic vulcanizate, is amorphous and crosslinked and so not subject to damage from the escaping volatile component.

[0007] It would be desirable to make cured elastomer compositions having the advantageous properties of phenol cured fluorocarbons, yet have suitable gas and vapor permeability properties to be used in hoses and the like.

Attorney TJocket No. 03-0047 (8470-000013) SUMMARY
[0008 Methods are provided for forming shaped articles from processable rubber compositions. The processable rubber compositions contain dyxlaroie wleanizates of fluorocarbon elastomers in a continuous phase thermoplastic material.
Shaped articles such. as hoses, gaskets and the like are provided that have favorable elastoraeric charactexistics. In addition, they are characterized by a low permeability to gsses and vapors. A pre-molding heat treatment step is applied, whereby processable rubber compositions resulting from the dynamic wlcaniaation of a fluorocarbon rubber in the thermoplastic are subject to an elevated temperature before they are melted and processed into the shaped articles by conventional. thermoplastic techniques.
[0009] 'Ihe methods are particularly suited to processable rubber compositions containing fluorocarbon elastomers cured by polyol or phenol curative agents. Tn one aspect, a dynamic wlcanizate of a fluorocarbon elastomer containing an excess of un-reacted polyol curative anent is subject to a pre-molding heat treatment at a temperature of 150°C or above, but preferably below the thermoplastic processing temperature, for a time sufficient to drive off ox decorrlpose at least part of the un-reacted or excess polyol curative agent. After part or all of the curative agent is driven off or decomposed by the heat treatment, the heat treated material may be thereafter processed by thermoplastic techniques to form shaped articles. Advantageously, articles produced by thermoplastic processing of the heat treated dynamic vulcanizates are characterized by a loiv permeability to gases and vapors, for exarzrpla fuel vapors.
(0010) Dynarz~ic vulcanization is carried out by combining an elastomer composition and a non-cuzixlg thermoplastic polymer in the presence of a polyol or.

~tttorncy' Docket',~1o. 03-0047 (8470-000013) phenol curative agent. The curative agent also contains an accelerator. The combixlation.
is melt blended, after tvhich the melt blend is heated while applying shear for a time and at a temperature sufficient to at least partially clue the fluorocarbon elastomer. In a preferred embodiment, the resulting dynsznic vulcanizate is cooled and converted to a particulate form, for example by extruding a strand and chopping it into pellets, or casting the material and grinding it. Thereafter, the particulate dynamic vulcarzizate is heat treated by exposing it to a temperature, preferably I50°C or greater, for a time sufficient to renoove at Ieast some of the excess un-reacted polyol or phenol curative remaining in the dynamic vulcanizate affier the heating and shearing step described above.
r~.fter the heat treatment step, the heat treated d~~namzc vulcanizate is heated above its processing temperature and processed according to thermoplastic techniques to make shaped articles of the invention.
[0011] Recognizing the need to eliminate or minimize the amount of excess or un-reacted phenol or polyol curative agent in dynamic vulcanizates of this kind, the invention encompasses methods for dynam.ical.ly wlcanizing fluorocarbon elastomers by techniques that result in pracessable rubber compositions having lesser amounts of un-reacted polyol curing agents. To the extent that dynamic wlcanizates may be prepared containing a minimum of excess curing agent, the heat treating step may be carried out for a shorter period of time. In the Iimit that the dynamic vulcanizates era well cured with a minimum of excess curing agent, the separate heat treating step may be done away with. In this embodiment, sufficient heat treatment is provided by the dynamic wlcariization step itself, and by the heating of the dynamic vulcanizate after cooling to provide further processing by thermoplastic techniques. In these embodiments, Attorney nodet No. 03-OOa7 (8470-000013) fluorocazbon elastomer compositions are used that contain a fluorocarbon.
elastomer, a phenol curative agent, and an accelerator, wherein the curative agent is present at a stoichiometric amount such that a8er cure the dynamic wlcanizate contains less than about 0.5 phr un.-reacted phenol curing agent and wherein the phenol and the accelerator are finely dispersed in th.e elastomer composition to provide sufficient reaction kinetics to complete the initial cure of the fluorocarbon in less than 1 S minutes at 13U°C, and to develop full cure density within two hours of pre-molding heat treatment at 200°C or less.
[0012) Further areas of applicability of the present invention wi.h become apparent from the detailed description pro~~ided hereinafter. It should be understood that the detailed description and specific examples are intended for purposes of iJ.lustration only and are not intended to tizrxit the scope of the invention.
BRIEF DESCRIPTION' OF THE DRAW1NGS
[0013] The present invention ~~iJl become more fully understood from the detailed description and the accompanying drawings, wherein:
[0014) Figure J. is a graphical representation of the development of soma physical properties during pre-molding heat treatment accordizrg to the invention.
DESCRIPTION
[0015) The following description of the preferred embodiments) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses.

Attorney Docket tvTo. U3-007 (&470-OOOOI3j [0016] The headings (such as "Introduction" and "Summary,") used herein are intended only for general organization of topics within the disclosure of the invention, and are not intended to limit th.e disclosure of the invention or any aspect thereof. In particular, subject matter disclosed in the ''Introduction" may include aspects of technology within the scope of the invention, and may not constitute a recitation of prior art. Subject matter disclosed in flue "Summary" i.s not an exhaustive or complete disclosure of the entire scope of the invention or any embodiments thereof.
[0017] The citation of references herein does not constitute an admission drat those references are prior art or have any relevance to the patentability of the invention disclosed herein. All references cited in the Description section of this specification are hereby incorporated by reference in their entirety.
[0018] The description and . specific examples, v~hile indicating embodiments of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. Moreover, recitation of m.u).tiple embodiments having stated features is not intended to exclude other embodiments having additional features, or other embodiments incorporating different combinations of the stated features. Specific Examples are provided for illustrative purposes of how to make, use and practice the compositions and methods of this invention and, unless explicitly stated otherwise, are not intended to be a representation that given embodiments of this invention have, or have not, been made or tested.
[0019] As used herein, the words "preferred" and "preferably" refer to embodiments of the invention that afford certain benefits, under certain circumstances.
However, other embodiments ma5~ also be preferred, under flee same or other attorney pocket No. 03-o0a7 (840-000013) circurr~stances. Furthermore, the recitation of one or more preferred embodiments does not imply that other embodiments are not useful, and is not intended to exclude other embodiments from the scope of the invention.
[0020] As used herein, the word "include," and its variants, is intended to be non-limiting, such that recitation of items in a list is not to the exclusion of other like items that may also be useful in the materials, compositions; devices, and methods of this invention.
[0021] Tloe terrrxs "elastomeric material", "elastomer", and the like refex to chemical compositions that possess, or can be modified (i.e. cured or crosslinked) to possess elastomeric properties. According to context, the. terms refer to an uncured or partially cured material, in which elastorneric properties are not fully developed, or to a cured rubber-life material, with fully developed elastomez-ic properties. At Borne points in the specification, the terms are used wiih adjectives such as "cored", "
partially cured", or "uncuxed" for clarity.
[0022] In one embodiment, the inventt.on provides a method for processing a rubber composition comprising cured fluozocarbon elastomer, thermoplastic polymer material, and excess un-reacted polyol curative agent into shaped articles. The rubber composition is prepared by a process of dynamically vulcanizing a fluorocarbon elastomer in the presence of a th.ermopIastic material and a palyol curative agent. The method for processing the rubber composition comprises heat treating the rubber composition at about 150°C or greater, but preferably below the thernaopla_stie processing temperature, for a time sufficient to drive off or decompose at least part of the un-reacted polyol curative agent, anal thereafter processin.? the heat treated rubber composition by Attorney Docket No. 03-0047 (8070-OO0U13) conventional thermoplastic techniques to form the shaped article. Shaped articles that can be made by the method include lom permeability extruded hoses, low permeation shaft seals, and the like. Processing the heat treated rubber composition by thermoplastic techniques generally involves heating the rubber composition above its thermoplastic processizzg temperature for further use in extrusion, injection molding, and other thermoplastic processes.
[0023] Methods for m.aki»g a shaped article comprising a cured fluorocarbon elastomer in a thermoplastic matrix involve a number of steps.
First, an elastomer composition is combined W tll a non-curing thermoplastic polymer material.
The elastomer compositio» comprises a fluorocarbon elastomer, a~~d optionally further comprises a polyol curative agent and an accelerator. The combination is then melt blended. Zf not alresdy contained in the elastomer conaposiiion, the curative agent and acceleraiat, as well as an acid acceptor and other additives are added to the melt blend.
The melt blend comprising fluorocarbon elastomer, polyol curative agent, accelerator, and thermoplastic polymer material is heated ulhile applying sb.ear for a time and at a temperature sufficient to at least partially cure the fluorocarbon elastomer.
The resulting dynamic vulcanizate is then cooled and converted into a particulate form. In a further step, the particulate dymamic vulcanixate is heat treated by exposing it to a temperature of about 150°C or greater far a time sufficient to remove at least some of the excess polyol curative agent remaining in the dynamic vutcani2ate after cure or partial cure. After at )east some of the excess polyol curative has been removed by the preceding heat treatment step, the heat treated dynamic vulcanizate is heated above its processing Attorney Docket No. 0~-0047 (,8470-000013) temperature and processed according to thermoplastic techniques to make the shaped article.
[0024] In v arious erbbodiments, the heat treatment step is canied out at a temperature of above 150°C but below its thermoplastic processing temperature. For simplicity, the heat treatment will be refetxed to as a pre-molding heat treatment, although it is to be understood that the heat treatment can in fact precede other therrmoplastie techniques that are to be carried out on the dynamic vulcanizate. In addition to molding, such techniques can include extrusion and thermoforming.
In a preferred embodiment, the pre-molding heat treatment is carzied out at about 230°C for a time exceeding one hoax, preferably heater than five hours. In various embodiments, the beat treatment is carried out for a period of about 16 to 24 hours. When the dynamically cured vuIcanizate contains a lesser amount of excess polyol curative agent, the pre-molding )teat treatment may be carried out for shorter periods of time at temperatures toward the lower end of the preferred range. For example, heat treatment may be carried out at 200°C or less for a time of 2 hours or less. 1n an exemplary embodinnent, heat treatment is carried out at about 1 SO°C.
X0025] In another embodiment, the invention provides a method of preparing a thermally processable rubber composition and for making shaped articles from the composition, which method may be carried out without a separate pre-molding heat treatment step as described abo~~e, or alternatively with a relatively short heat treatment of two hours or less at a relatively low temperature of 200°C
or less.. Irz this embodiment, a cure-incorporated elastomer composition and a non-curing thermoplastic polymeric material are f rst melt blended. The rx~elt blend is heated whi.]e applying shear Attonaey Docket No. 03-0047 (8470-000013) for a time and at a temperature suff. acient to cure the elastomer to a constant torque reading, and thereafter the melt blend is cooled to give a processable rubber composition.
The elastomer composition contains a fluorocarbon elastomer, a phenol or polyol curative agent, and an accelerator, wherein the curative scent is present at a stoichionzetric amount such that after cure the dynamic vulcaniaate contains less than about 1 phr un-reacted phenol curative agent In various embodiments, the dynamic wlcanizate has 0.5 phr or less, 0.2 phr or less, and preferably 0.1 phr or less of unreacted polyol curing agent after cure, where phx represents one part per hundred parts of elastomer. In a preferred embodiment, the phenol or polyol curative agent and the accelerator are finely dispersed in the elastomer composition, and the elastomer composition itself hss suitable low viscosity to enhance mixing during dynamic vulcanization. In a preferred embodiment, the accelerator also has a suitably low viscosity. The combination of the fine dispersion of the phenol and accelerator in the elastomer together with the low mixing vi.scosi.ties of components of the elastoraer eornposition provides sufficient reaction kinetics to complete the cure of the fluorocarbon elastomer to a constant torque reading during the dynamic vulcanisation step in 15 minutes or less at 180°C, and to provide development of a final cure density in 2 hours or less of pre-molding heat treatment at a temperature of 200°C or less. The final cure density is marked by achieving a constant value of at least one of compression set, tensile strength, and elongation at break. It has been found that if the methods of the invention axe carried out under these conditions, a separate pre-molding heat treatment step may be omitted, or the beat treatment can be carried out for a short period of time of about 2 hours or less at 230°C or less, preferably about 200°C or less, to obtain shaped articles W th acceptable properties such as compression set and Actomey Docket No. 03-0047 (8470-000013]
vapor permeability. Comxn.ercially available cure-incorporated elastomer compositions especially suited for this embodiment include Tecnoflan FOR SOHS and Tecnoflon FOR
80XiS, produced by Solway.
[0026] In a preferred embodiment, low permeabilit3~ hoses such as those suitable as fuel hoses are pzepared from the processable rubber. compositions of the invention. A d3namic wlcanizate of a fluorocarbon elastomer in a thermoplastic matrix.
is optionally heat treated to remove excess polyol curing agent. Then the beat treated dynamic vulcanizate is made into a low permeability hose, for example by extrusion or co-extrusion. In a preferred embodiment, the pracessable rubber composition.
of the invention forms a gas impermeable inside layer of. the hose, while a less expensive material, such as El'AM, butyl rubber, isoprene rubber, butylene rubber, butadiene rubber, AEM, ACM, nylon, thermoplastic elastomers, and the like forms the outside layer. Multilayer hoses can be prepaxed by extrusion of the processable rubber composition together with the less expensive material through a multilayer co-extrusion die. Alterbati~~ely, a tube or hose of the processable rubber composition can be fixst ek'truded and then fed into a rubber extruder to provide an extrusion coating comprising a thick layer of conventional rubber. Advantageously, the processable rubber compositi.oix fotnzing the inner layer of the hose provides chemical resistance anal low gas pexm.eability, while the outer rubber layer provides flexibility, toughness, and structural integrity. A cost advantage is also obtained by use of a relatively less expensive material to provide the outer layer.
[0027] In another embodiment, the invention provides a low gas permeability hose comprising an extruded dynamic wtlcanizate, ~vhexein the vulcanizate Attorney Docket No. 03-004 (8470-040013) comprises particles of cured fluorocarbon elastomer in a continuous phase of a thermoplastic polymeric matexial, and the hose has a vapor permeation rate of less than about 8 grams per square meter per day, preferably less than 7 grams per square meter per day, preferably less than or equal to about 5 gxams per square meter per day, and more preferably less than or equal about 3 grams per square meter per day, as measured according to standard test method ASTNI D-8I4 using fuel C. 'l he hoses of the invention optionally further comprise an extrusion layer on the extruded dynamic vulcanizate that forms an outer layer of the hose. The extrusion layer comprises a non-fluorocarbon rubber, a thermoplastic nnaterial, or a thermoplastic elastomer.
[0028) If desired, an adhesive layer may be provided to aid in bonding of the processable rubber composition with the outer layer of the hose. In an alternative embodiment where the outer layer is made of a thermoplastic material such as nylon or a thermoplastic elastomer, specialized adhesives may be used. In a non-limiting example, a functionalized ethylene/ trifluoroethylene copolymer such as Tefzel9, sold by T?upont, is used to bond to nylons. To bond the processable rubber composition to other rubbers, the extruded dynamic vulcanizate can be surface treated by corona or plasma treatment before the extrusion coating is applied. Alternatively, the surface of the extruded dynat~aic vulcanizate can be chemically etched according to known procedures such as treatzrzent with SLr011o bases like sodium amine or sodium naphthalene. The etched surface is then neutralized before the extrusion coating is applied.
[0029) Fluorocarbon elastomers are curable compositions based on fluorine-containing polymers. Various types of fluoroelastomers may be used.
One classification of fluoroelastomers is given. in ASTbI-D 1418, "Standard practice for Attorney Docket No. 03-0047 (8470-000013) rubber and rubber lances-nomenclature". The designation FKI~i is given for fluoro-robbers that utilize vinylidene fluoride as a co-monomer. Several varieties of FKM
fluoroelastomer.s are commexciaLly available. A first variety may be chemically described as a copolymer of hexafluoropropylene and vinylidene fluoride. These FKM
elastomers tend to have an advantageous combination of overall properties.
Some commercial embodiments are available with about 66% by weight fluorine.
Another type of FKI'4 elastomer may be chemicalJ.y described as a terpolymer of tecrafluoroethylene, hexafluoropropylene, and vinylidene fluoride. Such elastomers tend to have high heat resistance and good resistance to aromatic solvents. They are commercially available with, for ey;ample 68-69.5°~o by weight fluorine. Another FKM elastomer is chemically described as a terpolymer of tetrafluoroethylene, a fluorinated vin~rl ether, and vinylidene fluoride. Such elastomers tend to have improved low temperature performance.
They are available with. 62-68% by weight fluorine. A fourth type of FKiVi elastomer is described as a terpolymer of tetrafluoroethylene, propylene, and vinylidene fluoride.
Such FKM elastomers tend to have improved bsse resistance. Some commercial embodiments contain about 67% weight fluorine. A fifth type of FKM elastomer may be described as a pentapolymez of tetrafluoroethylene, hexafluoropropyl.ene, ethylene, a fluorinated vinyl ether and vinyl.idene fluoride. Such elastomers typically have unpro~:ed base resistance and have improved low temperature performance.
[0030] Another category of fluorocarbon elastvmers is designated as FFKM. These elastomers nxay be designated as perfluoroelastomers because the polymer' are completely fluorinated aid contain no carbon hydrogen bond. As a group, the FFKM fluoroelastom~rs tend to have superior fluid resistance. They were originally Attorney Docket No. 03-004 7 (8aTp-000013) introduced by DuPont under the lCalrez~ trade name. Additional suppliers include Daikin and Ausirrtont.
j0031] A third category of fluorocarbon elastomer is designated as FTPIvI.
typical of this category are the copolymers of propylene and tetrafluoroethylene. The category is characterized by a hj.~. resistance to basic materials such as amines.
[003Z] F_refexred fluorocarbon elastomers include cornnoercially available copolymers of one or more fluorine containing monomers, chiefly vinylidene fluoride NDF), hexafluotopropylene (HFP), tetra,fluoroethylene (TFE), and perfluvrovinyl ethers (PFVE). Preferred PFVE include those with a Cl-8 perfluoroalkyl group, pre.~erably perfluoroalkyl groups with. 1 to 6 carbons, and particularly perfluoromethyl vinyl ether and perfluoropropyl vinyl ether. In addition, the copolymers may also contain repeating unzts derived from olefins such as ethylene (Et) and propylene (Pr). Preferred copolymer fluorocarbon elastomers include ~'DF'/HFP, VDl~IHFP/TFE, TFE/Pr, and TFEIPrIVDF. The ela.Stomer designation gives the monomers from which the eIastomer gums are synthesized. In various embodiments, the e)astomer gums have viscosities that give a Mooney viscosity in the range generally of 15-I60 (M)rl + 10, large rotor at 121 °C), which can be selected for a combination of flow and physical properties.
Elastomer suppliers include Dyneon (3M), Asahi Glass Fluoropolymers, Solvay/Ausimont, Dupont, and Daikin.
(0033) In a preferred embodiment, the elastoraerie material comprises repeating units derived from 10-90 mole% tetrafluoroethylene, 10-90 mole% C2-4 olefin, and up to 30 mole°,% of one or snore additional fluorine-contai.ni.ng monomers.
Preferably, the repeating units are derived from 25-90 mole%
tetrafluoroetbylene and 10-Attorney Docket No. 03-0047 (&470-000013) 7~ mole% C2-4 olefin. In another preferred embodiment, the repeating units are derived from ~5-65 mole ~/o tetralluoroethylene and 20-55 mole °fo C2-4 ole;fn.
[003~4j In various embodiments, the molar ratio of tetrafluoroetbylene units to CZ_a olefin repeating units is from 60:40 to 40:60. In another embodiment, the elastomeric material comprises alternating units of Cz_~ olefins and tetrafluoroethylene.
In such pol~Jme.rs the molar ratio of tetrafluoroethylene to Cz~ olefin is approximately 50:50.
[0035] In another embodiment, the elastomeric materials are provided as block copolymers having an. A-B-A structure, wherein A represents a block of poly-tetrafluoroethylene and B represents a block of polyol.efin.
[0036] A preferred C2_~ olefin is propylene. lrl.astomeric materials based on copolymers of tetrafluoroethylene and propylene are commercially available, for example from Asahi under the Aflas~ trade name.
[0037 A, prefen:ed additional monomer in the vulcanised elastomeric matexial is vinylidene di.fluoride. Other .fl.uorine-containing monomers that may be used in the elastomeric materials of the invention include without limitation, perfluoroalkyl zrinyl compounds, perfluoroaikyl vinylidene compounds, and perfluoroalkoxy vinyl compounds. Hexafluoropropylene (HFP) is an example of per~luoroalkyl vinyl monomer. Pezfluoromethyl vinyl ether is an example of a preferred perfluoroalkoxy vinyl monomer. For example, rubbers based on copolymers of tetrafluoroethylene, ethylene, and perfluoromethyl vinyl ether are commercially available from nupont under the Viton~ ETf trade name.

Attorney Docket No. 03-0047 (8470-000013) [0038] In another embodiment, the elastomerie materials are curable fluorocarbon elastomers containing repeating units derived from fluoromonomers vinylidene fluoride (VDF) and hexafluoropropylene (HFP). In some embodiments, the elastomers further contain repeating units derivad from tetrafluoroethylene.
[0039j Chemically, in this embodiment the elastotberic material is made of copolymers of VDF and HFP, or of terpolymers of VDF, I-IFP, and tetrafjuoroethylene (TFE), with optional cure site monomers. In preferred embodiments, they contain about 66 to about 70% by weight fluorine. The elastomers are commercially available, and are axempl~ed by the Viton~ A, Viton~ B, and Viton~ F series of elastomers from DuPont Dow Elastomers. Grades ace com.mercialIy available containing the gum poly~x~ers alone, or as curative-containing pre-compounds.
[0040] In another embodiment, the elastomers can be described chemically as copol3nners of TFE and PFVE, optionally as a terpolymer with VDF. The elastomer may further contai~a xepeating units derived from cure site monomers.
[0041] Fluorocarbon elastomeric materials used to make the processable rubber compositions of the invention may typically be prepared by free radical emulsion polymerization of a monomer mixture containing the desired molar ratios of starting monomers. Initiators are tvpically organic or inorganic peroxide compounds, and the emulsifying agent i.s typically a fluorinated acid soap. The molecular weight of the polymer fornned may be controlled by the relative amounts of initiators used compared to the monomer level and the choice of transfer agent if any. Typical transfer agents include carbon tetrachloride, methanol, and acetone. The emulsion. polymerization may be 1 f, Attorney Dockat No. 03-007 (3470-000413) conducted under batch or continuous conditions. Such fluoroelastumers are connmereially available as noted above.
[0042] In some embodiments, the thermoplastic material co~npxises at least one fluorine containing thermoplastic polymer, or fluoroplastic.
Thermoplastic fluorine-containing polymers may be selected from a wide range of polymers and commercial products. The polymers are melt processable - they soften and flow when heated, and can be readily processed in thertn~oplastic techniques such as injection molding, extrusion, compression molding, and blow molding. The materials are readily recyclable by melting and re-processing.
[0043] The thezmoplastic polymers may be fully fluorinated or partially fluorinated. Fully fluorinated thermoplastic polymers include copolymers of tetrafluoroetttylene and perfluoroalkyl vinyl ethers. The perfluoroallcyl soup is preferably of 1 to 6 carbon atoms. Examples of copolymers are PFA (copolymer of TFB
and perfluoropropyl vinyl ether) and MFA (copolymer of TFE and perfluoromethyl vinyl ether). Other examples of fully fluorinated thermoplastic polymers include copolymers of TFE ~rith perfluoro olefins of 3 to A carbon atoms. Non-limiting examples include FEP (copolymer of TFE and hexafluoropropy~lene).
(0044) Partially fluorinated therrr~oplastie polymers ipclude E-TF'E
(copolyzrler of ethylene and TFE), E-CTFE (copolymer of ethylene and chlorotrifluoroethylene), and PVDF (polyvinylidene fluoride). A number of thermoplastic copolymers of vinylidene fluoride are also suitable thermoplastic polymers for use in the invention. These include, without limitation, copolymers with perfluorooleflns such as hexafluorvpzopylene, and copolyxlers with Attorney Docket No. 03-004 7 (8474-000013) chlorotrifluoroethylene. Thermoplastic terpolynners may also be used. these include thermoplastic terpolymers v~ TFE, H)rP, and vinylidene fluoride. Commercial embodiments are available which contain 59 to 76% by weight fluorine. Art example is Dyneon THV, which exhibits a melting point of frotz~. about 120°C to about 200°C, depending on the composition. In one embodiment, partially Fluorinated fluoroplastics are preferred that are characterized by a melting point of fxorn about 105°C to about 160°C. Use of. these rather low melting fluoroplastics permits the use of. peroxide curing agents at a lotv terz~peratuxe inhere undesirable volatilization of the peroxides is minimized.
[0045] Non-fluorine containing thermoplastic polymers may also be used.
bi one aspect, a thermoplastic material is one th.e melt viscosity of which can be measured, such as by ASTh-1 D-1238 or D-2116, at a tempexature above its melting point [0046] The thermoplastic material of the invention may be selected to provide enhanced properties of the rubber/thermoplastie combination at elevated temperatures, preferably above 100°C and snore pzeferably at about 150°C and higher.
Such thexmoplastics include those that maintain physical properties, such as at least one of tensile strength, nnoduius, and elongation at break to an acceptable degree at the elevated temperature. In a preferred embodiment, the thermoplastics possess physical properties at the elevated temperatures that are superior (i.e, higher tensile strength, higher modulus, and/or higher elongation at break) to those of the cured fluorocarbon elastomer (rubber) at a comparable temperature.
[0047] The thermoplastic polymeric msterial used in the invention may be a thermoplastic elastomer. Thernnoplastic etastomers have some physical properties of ,~ttorri2y Docket No, O,i-007 (8470-000013) rubber, such as softness, flexibility and resilience, but may be processed like thermoplastics. A transition from a melt to a solid rubber-like composition occurs fairly rapidly upon cooling. This is in contrast to conventional elastomers, which harden slowly upon heating. Thert~aoplastic elastomers may be processed on conventional plastic equipment such as injection molders and extruders. Scrap may generally be readily recycled.
[0048] Thermoplastic e~astomers have a mufti-phase structure, wherein the phases are generally intimately mixed. Tn many cases, the phases are held together by graft or block copolymerization. At least one phase is made of a material that is hard at room temperature but fluid upon heating. Another phase is a softer material that is rubber like at zoom temperature.
r0049~ Sortie therr~loplastic elastomers have an A-)3-A block copolymer srntcture, where A represents bard segments and B is a soft segment. Because most polymeric material tend to be incompatible with one another, the hard anal soft segments of therm,oplastie elastomers tend to associate with one another to form hand and soft phases. For example, the hard segments tend to fornz spherical regions or domains dispersed in a contizxuous elastomer phase. At room temperature, the domains are hard and act as physical crosslinks tying together elastomeric chains in a 3-D
network. The domains tend to lose strength when the material is heated or dissolved in a solvent [0050] Other thermoplastic elastomers hate a repeating structure represented by (A-B j", where A represents the hard se~nents and B the soft segments as described above, and n indicates a number of repeating units.

Anomey Docket No. 03-0047 (8470-000013) [0057] Many thermoplastic elastomers are known. Non.-limiting examples of A-B-A type thermoplastic elastomers include polystyrene/polysiloxaneJpolystyrene, polystyrene/polyethylene-co-butylenelpolystyrene, polystyrene/polybutadiene polystyrene, polystyrene/ polyisoprene/polystyrene, poly-a-methyl styrene/polybutadiene/poly-a-methyl styrene; poly-a-methyl styrene/polyisoprene/
poly-a-methyl styrene, and polyethylenelpolyethylene-cc-butylene/polyethylene.
[0052] Non-linnitin5 examples of thermoplastic elastomers having a (?~-B)n repeating structure include polyamide/poly~ether, polysulfone/
polydimethylsiIoxane, polyurethane/polyester, polyurethanelpolyether, polyester/polyether, polycarbonate/
polydimethylsiloxane, and polycarbonate/polyether. Among th.e most common commercially available thermoplastic elastomers are those that contain polystyrene as the hard segnent_ Triblock elastomers are available with polystyrene as the hard segment and either polybutadiene, polyisoprerJe, or polyethylene-co-butylene as the sofr segment.
Similarly, styrene butadiene repeating cv-polymers are commercially available, as well as polystyrene/polyisoprene repeating polymers.
[0053] A thermoplastic elastomer may have alternating blocks of polyamdde and polyetlaer. Such materials are commercially available, ~or example from Atofina under the Pebax~ trade name. The polyamide blocks may be derivzd from a eopolymet of a diacid component and a diamixie component, or may be prepared by bomopolymerizaiion of a cyclic lactam. The polyeth.er block is generally derived from homo- or copolymers of cyclic ethers such as ethylene oxide, prop3~lene oxide, and tetrahydrofuran.

<~ttorney Docket No. 03-007 ($470-000013]
[005] The thezmoplastic polymeric material may also be selected from among solid, generally high molecular weight, plastic materials. Preferably, the materials are crystalline or semi-crystalline polymers, and more preferably have a crystallinity of at least 25 percent as measured by differential scanning calorimetry. Amorphous polymem with a suitably high glass transition temperature are also acceptable as the thermoplastic polymeric material. The therznupiastic slso preferably bas a melt temperature or glass transition temperature ix~ th.e range from about 80'C to about 350'C, but the melt temperature should generally be lovyer than the decomposition temperature of the thermoplastic vulcaniaate.
(0053] Non-limiting examples of thermoplastic polymers include polyolefxns, polyesters, nylons, polycarbonates, styrene-acrylonitrile copolymers, polyethylene tereplathalate, polybutyIene terephthalate, polyanudes, polystt~rene, polystyrene derivatives, polyphenylene oxide, polyoxymethylene, and fluorine-containing thermoplastics.
(0056) Polyolefms are formed by polymerizing a-olefins such as, but not limited to, ethylene, propylzne, 1-butene, 1-hexene, l-octene, 2-methyl-1-propene, 3-m.etlryl-1-pentene, 4-methyl-1-pentene, 5-n~etbyl-1-lzexene, and mixtures thereof.
Copolymers of etbyler~e and propylene or ethylene or propylene with another a-olefin such as 1-butene, 1-hexene, 1-octene, 2-methyl-1-propene, 3-methyl-1.-pentene, methyl-1-pentene, 5-methyl-1-hexene or mixtures thereof are also contemplated.
These hon~:opolymers and copolymers, and blends of therx~, may be incorporated as the tb.ermopl.astic polymeric material of the invention.

Attorney Docket No. 03-0047 (8470-0000(3) [0057] Polyester thermoplastics contain repeating ester l.inlang units in the polymer backbone. In one embodiment, they contain repeating units derived from low molecular weight diols and low molecular weight aromatic diacids. Non-limiting examples include the commercially available grades of polyethylene tetephthalate and polybutylene tereplathalate. Alternatively, the polyesters may be based on aliphatic diols and aliphatic diucids. Exemplary here the copolymers of ethylene glycol or butanediol with adipic acid. In another embodiment, the thermoplastic polyesters are polylactones, prepared by polymerizing a monomer containiz~ both hydroxyl and carboxyl functionality. Polycaprolactone is a non-limiting example of this class of thertnoplastic polyester.
[0058] 1'olyamide thermoplastics contain repeating amide linkages in the polytrxer backbone. In one embodiment, the pol.yamides contain repeating units derived (torn diamine and diacid monomers such as the welt knov~~. nylon 66, a polymer of hexamethylene diamine and adipic acid. Other nylons have stntctures resulting from varying the size of the diatnine and diacid components. Non-limiting examples include nylon 610, nylon 612, nylon 4b, and nylon 6/66 copolymer. In another embodiment, the polyamides have a structure resulting from polynteri2ing a monomer with both amine and cazboxyl functionality. Non-l.itniting examples include nylon 6 (,polycaprolactam), nylon 11, and nylon 12.
[0059] Other polyamides made from diamine and diacid components include the high. temperature aromatic polyamides containing repeating units derived from diamines and aromatic diacids such as terephtbalie acid. Commercially available examples of these include PA6T (a copolymer of hexanediamine and terephthalic acid), Attorney Docket No. 03-0047 (8470-OOOOl3) and PA9T (a copolymer of nonanediarn.ine and terephthalic acid j, sold by Kuraray under the Genestar tradcname. For some applications, the melting point of some aromatic polyamuides may be higher than optimum for thermoplastic processing. In such cases, the melting poi~.t may be lovs~ered by preparing appropriate copolymers. In a non-limiting example, in the case of PA6T, which has a melting temperature of about 370°C, it is possible to in effect l.o~t~er the melting point to below a moldable temperature of 320°C
by including an effective amount of a non-aromatic diacid such as adipic acid when making the polSZner.
[0060] In another preferred embodiment, an aromatic pol.yan~.ide is used based on a copoltzner of an aromatic diacid such as terephthalic acid and a diamine containing greater than 6 carbon atoms, preferably containing 9 carbon atoms or noore.
The upper limit of the length of the carbon chain of the diamine is limited from a practical standpoint by the availability of suitable monomers for the polymer synthesis.
As a rule, suitable diatxtines include those having from 7 to 20 carbon atoms, preferably in the range of 9 to IS carbons, and more preferably in the range from 9 to 12 carbons.
Pxeferred embodiments include C9, C10, and Cl l diamine based aromatic polyamides. It is believed that such aromatic polyamides exhibit an irxcrease level of solvent resistance based on the oleophilic nature of the carbon chain having greater than 6 carbons. If desired to reduce the melting point below a preferred molding temperature (typically 320°C or Iowerj, the aromatic pol.yamide based on diamines of greater than 6 carbons may contain an effective amount of a non-azomatie diacid, as discussed above with the aromatic pol.yamide based on a 6 carbon diamine. Such effective amount of diacid Attorney Docket No. 03-0047 (&470-040013) should be enough to tourer the nnelting point into a desired molding temperature range, ctrithout unacceptably affecting the desired solvent resistance properties.
j0061] Other non-limiting examples of high temperature thert~oplastics include polyphenylene sulfide, liquid crystal polymers, and high temperature pol.yimides.
Liquid wystal polymers are based chemically on linear polymers containing repeating linear arotxtatic rings. Because of the aromatic structure, the materials form domains in the nezaatic melt state with a characteristic spacing detectable by ?t-ray diffraction methods. Examples of materials include copolymers of bydroxybenzoic acid, or copolymers of ethylene glycol and linear aromatic diesters such as terephthalic acid or naphthalene dicarboxylic acid.
(0062] High temperature thermoplastic polyimides include the polymeric reaction products of aromatic dianhydrides and aromatic diamines. They are commercially available from a number of souxces. Exemplary is a copolymer of 1,4-benzenediamine and 1,2,4,5-benzenetetracarboxylic acid dianhydride.
[0063] The curative agents and curative systems for the fluorocarbon elastomers used in the present invention are generally selected from the group of polyol and opium salt combinations. The polyol curative agents include phenol curative agents, while the opium salts are used as accelerators in the curing systems.
j0064] Suitable onJUm salts are described, for example, in U.S. Pat. Nos.
4,233,421; 4,912,171; and 5,262,490, each of v~hich is iocoyorated by reference.
Examples include triphenylbenzyl phosphonium chloride, tribut5~l. alkyl phosphonium chloride, tributyl benzyl ammonium chloride, tetrabutyl ammonium bromide, and triarylsulfonium chloride.

a~oraEy Do~k~t :~o. o~-ooa~
(~Sd~O-400013) [0065] Another class of useful opium salts i.s represented by the following formula:
[0066] Formula I:
R, f+l R2 Q Z [X] "~'~
3 n [0067] wl~erei0 [0068] Q is nitrogen or phosphorus;
[0069] Z is a hydrogen aiom or [0070] is a substituted or un.substituted, cyclic or acyclic alkyl group having from 4 to about 20 carbon atoms that is teralinated wiih a group of the formula --C00A where A is a hydrogen atom or a N~+ cation or Z is a group of the formula [0071] --CY2 COOR' where ~' is a hydrogen or balogetl atom, or is a substituted or unsubstituted alkyl or aryl gxoup having from 1 to about 6 carbon atoms that may optionally contain one or more quaternary heteroatonrls and where R' is a hydrogen. atom, a NH.~+ canon, an alkyl gxoup, or is an acyclic anhydride, e.g., a group of the formula --COR where R is an alkyl group or is a group that itself contains organo-opium (i.e., giving a his-organo-opium); preferably R' is hydrogen; Z may also be a substituted or unsubstituted, cyclic or acyelie alkyl group having from 4 to about 20 carbon atoms that is terminated with a coup of the formula --CODA where A 15 3 hydrogen atom or is a NH4+ cation;
[0072j R1., R2, and R3 are each, independently, a hydrogen atom ox an alkyl, aryl, alkenyl, or any combination Thereof, each Rl, Rz, and R3 can be substituted Arorney Docket No. 03-0047 (8470-000013) t~~ith chlorine, fluorine, bromine, cyano, --OR", or --COOR" where R" is a CI
to C20 alkyl, aryl, aralkyl, or alkenyh and any pair of the Rl, RZ, and R.3 groups can be connected with each other and with Q to forn.7 a heterocyclic ring; one or more of the Rl, R?, and R3 groups may also be a group of the forraula Z where Z is as defZned above;
[0073] X is an organic or inorganic anion (for example, without limitation, halide, sulfate, acetate, phosphate, phosphonate, hydroxide, alkoxide, phenoxide, or bisphenoxide); and [00741 n i.s a number equal to the valence of the anion. X.
[0075] The polyol crosslinkino agents may be any of those polyhydxoxy compounds known in the art to function as a crosslinking agent or co-curative for fluoroelastomers, such as those polyhydroxy compounds disclosed in U.S. Pat.
Nos, 4,259,463 (Moggi et al.), U.S. Pat. No. 3,876,654 (Pattison), U.S. Pat. No.
4,233,421 (Worm), and U.S. Defensive Publication TI07,301 (Nersasian). Preferred pol.yols include aromatic polyhydroxy compounds, aliphatic polyhydroxy compounds, and pbebol resins.
[0076] Representative aromatic polyhydroxy compounds include any one of the following: di-, tri-, and tetrahydroxybenzenes, -naphthalenes, and -anthracenes, arid bisphenols of the Formula [007'1] Formula 2:
~E..~ n OH)n _' (A) x [0078] wherein A is a difunetional aliphatic, cycloaliphatic, or aromatic radical of 1 to 13 carbon atorn.s, or a thio, oxy, carbonyl, or sulfonyl radical, A is ?6 Attorn.zy Docket No. 03-ood7 (8470-UUUUI3j optionally substituted with at least one chlorine or fluorine atom, x is 0 or 1, each n is independently 1 or 2, and any aromatic ring of the polyhydroxy compound is optionally substituted with at least one atom of chlorine, fluorine, or bromine atom, ox carboxyl or an, acyl radical (e.g., --COR, where R is H or a C1 to C8 alkyl, aryl or cycloallyl group) or alkyl radical with, for example, 1 to 8 carbon atoms. It will be understood from the above bisphenol formula III that the --OIL groups can be attached in any position (other than number one) in either ring. Blends of two or nnore such compounds can also be used.
preferred bisphenol compomid is Bisphenol AF, which is 2,2-bis(4-hydrox5~phenyl)hexafluoropropane. Uther non-limiting examples include 4,4'-dihydroxydipbenyl sulfone (Bisphenol S) and 2,z-bis(4-hydroxyphenyl) propane (Bisphenol A). Aromatic polyhydroxy compound, such as hydroquiraone may also be used as curative agents. Further non-limiting examples include catechol, resorcinol, 2-methyl resorcinol, 5-methyl resorcinol, 2-methyl hydroquinone, 2,5-diznethyl hydroquinone, and 2-t-butyl hydroquinone, 1,5-dihydroxynaphthalene and 9,10-dihydroxyanthracene.
[0079] Aliphatic polyhydroxy compounds may also be used as a polyol curative. )examples include fJuoroaliphatic diols, e.g. 1,1,6,6-tetrahydrooctafluorohexanedioi, and others Such as those described in U.S.
Pat. No.
4.358,559 (Holcomb et al.) and references cited therein. Derivatives of polyhydroxy compounds can also be used such as those described in U.S. Pat. No. 4,446,270 (Guenthner et al.) and include, for example, 2-(4-allylox~~phenyl)-2-(4-hydroxypb.et~yl)propane. l~4ixtures of two or. more of the polyhydroxy compounds cats be used.

Attorney Docket No. 03-0047 (8470-000013) [0080] Phenol resins capable of crosslinkina a rubber polymer can be employed as the polyol curative agent.. Reference to phenol resin may include mixtures of these resins. U.S. Pat, Nos. 2,972,600 and 3,287,440 are incorporated herein in this regard. These pbenolic resins can be used to obtain the desired level of cure without the use of other curatives or curing agents.
(0081 Phenol resin curatives can be made by the condensation of alkyl substituted phenols or unsu.bstituted phenols with aldehydes, preferably formaldehydes, in an alkaline medium or by condensation of bi-functional phenol dialcohols.
The alkyl substituents of the alkyl subsrituted phenols typically contain 1 to about 10 carbon atoms.
Dimethylolphenols or phenolic resins, substituted in para-positions with atl,,yl groups containing 1 to about 10 carbon atoms, are preferred. Useful coTx~mercially available phenol resins include alkylphenol-formaldehyde resin, and bromomethylated alJ~~lphenol-folxnaldehyde resins.
(0082] In one embodiment- phenol resin curative agents may be represented by the general formula:
OH OH
OH--CHa ~~.-ON
v ~ v n (0083] whera Q is a divalent radical selected from the group consrstTng of -CH2--- and --CH2 --0--CH2 --; m is zero or a positive integer from 1 to 20 and R' is hydrogen or an organic radical. Preferably, Q is the divalent radical --CH2 --0--CH2 --, m is iero or a positive integer from 1 to 10, and R' is hydrogen or an organic radical Attorney Docket No. 03-0047 (8470-000010 having Iess than 20 carbon atoms. In another embodiment, preferably m is zero or a positive integer from I to 5 and R' is an. organic radical having between 4 and 12 carbon.
atoms. Other preferred phenol resins are also defined izt U.S. Pat. No.
5,952,425, which is incorporated herein by reference.
[0084] The cured fluorocarbon elastomer compositions of the invention are prepared by a process of dynamic vulcanization. Dy~namt.c vulcanization is a vul-canization or curing process for a rubber (here a fluorocarbon elastom.er) contained in a thermoplastic composition, ~ul~erein the curable rubber is vulcanized under conditions of suffciently high shear at a temperature above the melting point of the tbertnoplastic component. In this way, the rubber is simultaneously crosslinked and dispersed within the- thermoplastic matrix. Dynamic wlcanization may be carried out by appllring mechanical energy to mix the elastomeric and thermoplastic components at elevated temperaturz in the presence of a curative in conventional mixing equipment, such as roll mills, bLoriyama mixers, Banbury mixers, Brabender mixers, continuous mixers, mixing extruders such as single axed twin-screw extruders, and the like. An advantageous characteristic of dynamically cured compositions is that, not withstanding that the elastomeric component is fu115~ cured, the composition can be processed and reprocessed by conventional. plastic processing techniques such. as extrusion, injection molding, and compression molding. Scrap or flashing can also be salvaged and reprocessed with thermoplastic techniques.
[0085] The vulcanized elastomeric material that results from the process of dynamic ~rulcanization is generally present as small particles within a continuous thermoplastic pol.ytner matzix. A co-continuous morphology is also possible depending Attorne)~ Docket No. 03-0047 (8470-000013) on the amount of etastomeric material relative to thermoplastic material, the cure system, the mechanism of cure and the amount and degree of mixing.
[0086] After dynamic wlcanization, a homogeneous mixiure is obtained wherein the cured fluozoelastomer is in the form of dispersed particles having an average particle smaller than. about 50 micrometers, preferably of an average particle size smaller than about 2~ micrometers. The particle size may be determined from maps prepared by atomic force microscopy on cryogenically rnicrotomed cross-sections of shaped articles formed from the processable rubber composition.
[0087] Typically, the particles hate an average size of l0 micrometers or less, more preferably 5 micrometers or less as measured with the atomic force microscopy technique. In some embodiments, the panicles have an average size of 1 micrometer or less. In otb.er embodiments, even when the average particle size is higher, there will be a significant number of cured el.aston3er particles with a diameter of less than 1 micron dispersed in the thermoplastic mstrix.
[0088] 1n a preferred embodiment, plasticizers, extender oils, synthetic processing oils, or a combination thereof may be used in the compositions of the irxvention. The type of processing oil selected will typically be consistent with that ordinarily used in. conjunction with the specific zubber or rubbers present in the composition. The extender oils may include, but are not limited to, aromatic, naphthenic, and paraffinie extender oils. Preferred synthetic processing oils include polyliaear a-olefins. The extender oils may also include organic esters, alkyl ethers, or combinations thereof. a,s disclosed inn U.S. Pat. No. 5,397,832, it has been found that the addition of certain Iotv to medium molecular weight organic esters and alkyl ether esters to the 3~

Attorney Docket No. 03-0047 (8470-000013) compositions of the i~verltion lowers the Tg of the thermoplastic and rubber components, and of. the overall composition, and improves the low temperatures properties, particularly flexxbilit~~ and strength;. These organic esters and alkyl ether esters generally have a molecular weight that is generally less than about I0,000. Particularly suitable esters include monomeric and oligomeric materials having an average molecular weight below about 2000, and preferably below about b00. In one embodiment, the esters may be either aliphatic mono- or diesters or alternatively oligomeric aliphatic esters or alkyl ether esters.
[0089] In addition to the elastomeric material, th.e thermoplastic palymerie material, and curative, the processable rubber compositions of this invention may include other additives such as stabilizers processing aids, curing accelerators, filers, pigments, adhesives, tackil:xers; and coaxes. The propezties of the compositions and articles of the invention may be modified, either before or aftez vulcanization, by the addition of ingredients that are conventional in the compounding of rubber, thermoplastics, and blends thereof.
[0090] A wide variety of processing aids may be used, i.ncl.uding plasticizers and mold release agents. Non-limiting examples of processing aids include Caran,uba wax, phthalate ester plasticizers such as dioctylphthalate (DOP) and di.buty~lphtha)ate silicate (DBS), fatty acid salts such zinc stearate and sodium stearate, polyethylene «,~ax, and keramide. In some embodiments, hi.glx temperature processing aids are preferred. Such include, without limitation, linear fatty alcohols such as blends of C10-C28 alcohols, organosilicones, and functionalized perfluoropolyet).iers. In some .i 1.

Attorney Docket No. 03-0047 (8470-OOOUI3) embodiments, the compositions contain about 1 to about 15°,% by weight processizlg aids, preferably about 5 to about 10% by weight.
[0091] Acid acceptor compounds are commonly used to speed up or stabilize the cure of the fluorocarbon elastomers. Preferred acid acceptor compounds include oxides and hydroxides of divalent metals. Non-limiting examples include Ca(OH~2, h~fg0, CaO, and ZrtO.
[0092] Non-limiting examples of fillers include both. organic and inorganic fillers such as, barium sulfate, zinc sulfide, carbon black, silica;
titanium dioxide, clay, talc, fiber glass, fumed silica and discontinuous fibers such as mineral fibers, wood cellulose fibers, carbon fzber, boron. fiber, and aramid fiber (Kevlar). Some non-limiting examples of processing additives include stearic acid anal lauric acid. The addition of carbon black, extender oil, or both, preferably prior to dynamic vulcanization, is particularly preferred. Non-limiting examples of carbon black fillers include SAIr black, HAF black, SRP black and Austin black. Carbon black improves the tensile strength, and an extender oi.l can improve processabiJity, the resistance to oil swell, beat stability, hysteresis, cost, and permanent set. In. a preferred embodiment, fillers such as carbon block may make up to about ~0% by weight of the total weight of the compositions of the invention. Preferably, the compositions comprise 1 to 40 ~~'eight o/o of filler. In other embodiments, the filler makes up 10 to 25 weight % of. the composition9.
j0093] 'fhe size of the particles referred to above may be equated to the diameter of spherical pazticles, or to the diameter of a sphere of equivalent volume. It is to be understood that not all particles will be spherical. Some particles will be fairly Attorney Docket Tio. 03~0047 (8470-00001.0 isotropic so that a size approximating a sphere diameter may be readily determined.
Other particles may be anisotropic in that one or two dimensions may be longer than another dimension. In such cases, the preferred particle sixes referred to above correspond to the shortest of the dimensions of the panicles.
[0094] In some embodiments, the clued e.lastomeric material is in. the form of particles forming a dispersed, discrete, or non-continuous phase wherein the particles are separated from one another by the continuous phase made up of the thermoplastic matrix. Such structures are expected to be more favored at relatively lower loadings of cured elattomer, i.e. where the thermoplastic material tglces up a relatively higher volume of the com.position.s. Tn other embodiments, the cured material may be in the form of a co-continuous phase with the thermoplastic material. Such structures are believed to be favored at relatively higher volume of the cured elastomer. At intermediate elastomer loadinps, the structure of th.e tu~o-phase compositions may take on az~ intermediate state in that some of. th.e cured elastomer rnay be in the form of discrete particles and some may be in the form of a co-continuous phase.
[0095j The homogenous nature of the compositions, the small particle size indicative of a large surface area of contact between the phases, and the ability of the compositions to be formed into shaped articles having sufficient hardness, tensile strength, modules, elor.~atian at break, or compression set to be useful in it~.dustrial applications, indicate a relatively high dea~.ree of compatibility between doe elastomer and chermoplastio phases.
[0096] The progress of the wLcanization may be followed by monitoring mixing torque or mixing energy requirements during mixing. The mixing torque or ., Attorney Docket No. 03-004?
(8470-000013) mixing energy curare generally goes thxough a n~axixmun after which mixing can be continued somewhat Longer to improve the fabricability of the blend. If desired, one can add additions( ingredients, such as the stabilizer package, a~.er the dynamic vulcanization is complete. The stabilizer package is preferably added to the thermoplastic vulcanizate after ~ul.canization has been essentially completed, i.e., the curative bas been essentially consumed, [0097] The processable rubber compositions of the invention may be manufactured in a batch process or a continuous process.
[0098] In a batch process, predetermined charges of elastomeric material, thermoplastic, and curative agents are added to a mixing apparatus. Iu a typical batch procedure, the elastomenic material and thermoplastic are first mixed, blended, masticated or otberw~ise physically combined until a desired particle size of elastomeric material is provided in a continuous phase of thermoplastic material. When the structure of the elastomeric material is as desired, a curative agent may be added while continuing to apply mechanical energy to mix the elastomeric material and thermoplastic.
Curing is effected by heating or continuing to heat the mixing combination of thermoplastic and eiastamerie material in the presence of the curative agent. When cure is complete, the processabJ.e rubber composition naay be remo~c~ed from the reaction vessel (mixing chamber) for further processing.
[0099] It is preferred to mix the elastomeric material and thermoplastic at a temperature where the thermoplastic material softens and flo~~s. If such a temperature is below that at which the curative agent is activated, the curative agent may be a part of the mixture durin~z the initial particle dispersion step of the batch process.
In some Attorney Docket'-Jo. 03-0047 (S4?0-0000).3]
embodiments, a curative is combined with the elastomeric material and thermoplastic at a temperature below the curing temperatuze. When the desired dispersion is achieved, the temperature may be increased to effect cure. In one embodinnent, commercially available elastorxxeric materials are used that contain a curative pre-formulated into the elastomer.
However, if the curative agent is activated at the temperature of initial mixing; it is preferred to leave out the curative until the desired particle size distribution. of. the elastomeric material in the them~oplastic matrix is achieved. In another embodiment, curative is added after the elastomeric material and thermoplastic are mixed.
In a preferred embodiment, the curative agent is added to a mixture of elastomaric particles in the thermoplastic while the entire mixture continues to be mechanically stirred, agitated or otherwise mined.
[0100] Continuous processes may also be used to prepare the processsble rubber compositions of the invention. In a preferred embodiment, a twin screw extruder apparatus, either co-rotation or counter-rotation screw type, is provided with ports for material addition and reaction chsznbexs made up of modular components of the twin screw apparatus. In a i~~pical continuous procedure, the thermoplastic and elastomeric materials are combined by inserting them into the screw extruder together fxonn a first hopper using a feeder (loss-in-weight or volumetric feeder). Temperature and screw parameters may be adjusted to provide a proper temperature and shear to effect the desired mixing and panic-le size distzibution of an uncured elastomeric component in a thermoplastic material matrix. The duration of mixing may be controlled by providing a l.ongez or shorter length of extrusion apparatus or by controlling the speed of screw rotation for the mixture of elastomerze material and thermoplastic material to go through Attorney Docket No. 03-0047 (8470-000013) during the mixing phase. The degree of mixln.g may also be controlled by the m.ixixxg screw element configuration in the screw shaft, such as intensive, medium or mild screw designs. Then, at a downstream port, by using side feeder (loss-in-weight or volumetzic feeder), the curative agent may be added continuously to the mi?tture of thermoplastic and elastomeric materials as it eontirtues to travel down the twin screw extrusion pathway.
Do~mstream of the curative additive port, the mixing parameters and transit lime may be varied as described above. By adjusting the shear rate, temperature, duration of mixing, mixing screw element configuration, as well as the time of adding the curati4e agent, processable rubber compositions of the invention may be made in a continuous process.
As in the batch process, the elastomeric material may be commercially formulated to contain a curative agent, generally a phenol or phenol. resin curative.
(0101) The compositions and articles of the invention will contain a sufficient annount of ~~uleanized elastomerie material ("rubber") to form a rubbery composition of matter, that is, they v~ill exhibit a desirable combination of ~lexability, softness, and compression set. Preferably, the compositions should comprise at least about 25 parts by weight rubber, preferably at least about 35 parts by weight rubber, more preferably at least about 40 parts by weight rubber, even more preferably at least about 45 parts by weight rubber, and still more preferably at least about SO parts by weight rubber per 100 parts by weight of the rubber and thermoplastic polymer corxabined.
The amount of cured rubber within the thermoplastic vulcanizate is generally from about S
to about 95 percent by weight, preferably from about 35 to about 95 percent by weight, more preferably from about 40 to about 90 weight percent, and more preferably from about 50 Attorney Aockot No. 03-0047 (8470-OOOOt3) to about 80 percent by weight of the total weight of the robber and the thermoplastic polymer combined.
[Oi 02] The amount of thermoplastic material withzn the processable rubber compositions of the invention is generally from about 5 to about 95 percent by weight, preferably from about 10 to about 65 percent by weight and more preferably from about 20 to about 50 percent by weight of the total weight of the rubber and the fluoroplastic blend combined.
[0103] Advantageously, the shaped articles of the invention are rubber-Like materials that, unlike conventional rubbers, can be processed and recycled like thermoplastic materials. These materials are rubber like to the ek-tent that they will retract to less than I.~ times their original length within one minute after being stretched at room temperature to tW ce its original length and held for one mijztute before release, as defined in ASTM D1566. Also, these materials satisfy the tensile set requixements set forth in ASTM D~12, and they also satisfy the elastic requirements for connpression set per ASTl4i D395.
[0104] In one embodiment, the dynamic wlcanizate after cure, preferably to a constant tarque reading, contains excess amounts of polyol or phenol curative agent.
It has been discovered that when d~~namic vulcanixates containing excess polyol curative agent are processed at high temperatures such as at melt processing temperatures for thermoplastic techniques, shaped articles resulting from the process are characterized by a l~a,I~ degree of porosity. It is believed that the porosity is caused by the off gassing of volatile curing agent and decompositi.ozt products during the high temperature melt processing. Such off gassing and decomposition present a problem for dynamically Attorney taocket No. 03-0047 (3470-000013) cured vulcanizates having a continuous matrix of a thermoplastic material.
Unlike cured rubber compositions, the thermoplastic matrix is subject to the formation of pores and voids by the action of the volatilizing decomposition products. Such processes lead to t>le formation of shaped articles having undesirable gasJvapor permeability characteristics. For applications such as hoses for fuel systems, the undesirable permeabilit3~ properties render them. unsuitable for their purpose.
[0105) To overcome the problem, the dynamic vulcanizate containing excess curative agent can be put through a heat treatment step to at J.east partially drive off or decompose tile excess curative agent. As discussed above, the heat treatment is referred to herein as a pre-molding heat treatment, even though it is understood the treatment can precede other thermoplastic techniques such. as extrusion, blowing, or thermoforming. As a result, shaped articles made by thermoplastic techniques from the processable rubbez compositions are characterized by a lower degree of vapor permeability and are suitable fur applications such as fuel hoses.
[0906] In various embodiments, the pre-molding heat treatment step is carried out an a dynamic wlcanizate in particulate form. The pazticles of the dynamic s~ulcaniaate may be prepared by a number of methods. Tn one errlbodirnent, the dynamic vulcanizate is exttided through strand dies, cooled in a water bath, and cut into pellets for Jater pre-molding heat treatment, In various embodiments, the molten dynamic vulcanizate is removed from the reaction chamber and ground or milled into particles of suitable size for subsequent pre-molding heat treatment.
[0107] The pre-molding Cleat treatment may be cao-ied out immediately upon Cooling and pelletizt»; Of the dynamic wlcanizate, or the pellets may be stored for 4ttoxney Docket No. 03-0047 (8470-000013) a short period or an extended period of time before the subsequent heat treatment and thermoplastic processing into shaped articles. Whenever the pre-molding heat treatment is to be cazried out, it is preferred to heat the particulate dynamic ~sntlcanizate at a sufficient temperature so that volatile curative agent will be driven off and/or the curative agent decomposed and the decomposition products driven off during the heat treatment.
In a preferred embodiment, the heat treatment is carried out at a temperature of about 150°C or greater. In various embodiments, it is preferred to carry out the pre-molding heat treatment at a temperature below which the dynamic vul.canizate bei.rlg heat treated ~evill soften and flow. Fer this reason, it is preferred to carry out the heat treatment at temperatures below the melt processing temperature of the pellets.
(0108] Zn one aspect, the nature of the thermoplastic continuous phase determines and limits the temperature at which the pre-molding heat treatment may be carried out. In preferred embodiments, the pre-molding beat treatlxlent is carried out at temperatures as high as 230°C or above. For these embodiments, it is preferred to use dynamic vulcanizates containing a thermoplastic continuous phase with. a n~.elting or a softening point above 230°C. Non-lirniiing examples of such suitable thermoplastics include fully fluorinated therrxloplastrcs, as well as their blends with partially fluorinated thermoplastics. Typical melting points of fully fluorinated plastics include FPA at about 305°C and FEP at about 290°C. It has also been found that blends of the fully fluorinated thermoplastics and a partially fluorinated thermoplastic may be used as long as an overall melting temperature of the tlxermoplastic blend and the dvnarnic vul.canizate remain above about230°C.

Attorney Docket No. 03-0047 (8470-000013) [0109] Pre-molding heat treatment is carried out generally under ambient pressure conditions, but at elevated temperatures, preferably from about 150°C to about 230°C. It is preferred to heat treat the particles at a temperature below 4vhich the particles would soften, f]wu, or coalesce. It is also preferred to tumble or gently agitate the particles during floe beat treatment. In various embodiments, for example, where the fluorocarbon elastomer contains finely dispersed curative and accelerator and cures rapidly during dynamic wlcaniaation, heat treating is carried out at 200°C or less for 5 hours or less, preferably for 2 hours or less. In some embodiments, heat treatrrtent is carried out for about one hour. In an exemplary embodiment, heat txeating is carried out at about 150°C for I hour.
(0110] The pre-molding heat treatment is carried out for a time until at least some of the excess polyol or phenol curative agent is driven off or decomposed.
The course of the heat treatment can be followed by observing visible smoke and other indications of volatile products being driven off. If desired, the course of the reaction can also be followed gravimetrically. Thus in various embodiments, the heat treatment is carried on for a time until visible srz~oke and the like are no longer observed, or for a time until a constant weight of the pellets is reached.
[0111] The pre-molding heat treatment is carried out in order to drive off excess curative agents, which would othertvise cause problems in subsequent thermoplastic processing due to volatization and pore formation in the thermoplastic matrix of the shaped article. As a result of using the method, it is possible to make shaped articles such as hoses and gaskets that have an acceptable level of gas and vapor ~0 Attorney Docket No. 03-0047 (8470-000013) permeability. However, another advantage observed is the development o~ some favorable properties during and as a result of the pre-rnoldi3~ heat treatment step.
[011Z] As noted above, the dynamic ~nzlcanizate is heated under shear for a time and at a temperaturz sufficient to at least partially cure the fluorocarbon elastomer.
In some embodiments, the dynamic wlcanization i.s carried on for a time sufficient to completely cure the elastom.er, as indicated by a constant torque on the mi.xixzg apparatus.
Even. when the dynamic vulcanisation process results in a complete cure of the fluorocarbon elastomer as tested by constant torque however, the pre-molding heat treatment step can be observed to further develop desirable characteristics, such as compression set. For erample, as shoum in Figure 1, the compression set of a shaped article (such as a gasket or seal) formed from heat treated dynamic vulc9nizates decreases to a constant amount with increasing pre-molding heat treatxrzent time.
[0113] The duration of pre-molding heat txeattxzent needed to fully develop the property depends on the nature of the fluorocarbon elastomer and the curative agent, as well as the stoichiometri.c excess of curative agent used, the fineness of dispersion of the curative and accelerator in the elastomer, the effectiveness of the accelerator, the viscosity of the elastomer, and other parameters. Figure 1 shows rivo curves indicating the development of compression. set against time of pre-molding heat treatment. An experiment can be carried out wherein the cooled dynamic vuleanizate is subjected to heat treatment for a variable amount of time. After a tiz~ne of heat treatment, the heat treated dynamic vulcanizate may be processed by thermoplastic techniques into shaped articles and the compression set messured. As shown in Figure l, a."fast curing"
composition can develop its final compression set value within about l hour of pre-Attorney Docket No. 03-0047 (8470-000013) molding heat treatment, while a "slow curing'- dynamic vulcanizate may develop a steady state compression set after several hours of heat treatment. As shown in Figure 1, the slow curing composition develops a steady compression set after about 16 hours of pre-molding heat treatment 23U°C. Thus, in addition to reducing the porosity of the shaped articles, tb.e method provides a means for pzoducu~g shaped articles having unproved characteristics such as compression set. Figures analogous to Figure 1 czn also be prepared for other physical properties that reflect development of cure density, such as tensile strength and elongation at break.
(0114] The invention has been described above with regard to preferred embodiments. Further non-limiting disclosure of the invention i.s giilen in the Examples that follow.
E,XA.MPLI:S
(0115j The following materials are used ixa the Examples:
[0116] Fluorel FE 5840 is a hid fluorine (70% P) cure incorporated fl. uoroelastomer from Dvneon.
[0917] Dyneon BRE 7231X is a base resistant cure incorporated t?uoroelastor~er from Dyneon. It is based on a terpolymcr of TFE, propylene, and vinylidene fluoride.
[0118] FTalar SOOLC is a thermoplastic copolymer of ethylene and chlorotrifluoroethylene from Solvay.
[0119] Rhenofzt CF is a calcium hydroxide fxom Rhein Chemie.
[0120] Elastomag 170 is a magnesium hydroxide powder from Rohm and Haas.

?~ttorney Docket No. U3-0047 (8470-000013 j [0121] Struktol WS-2$0 is a processing aid from Struktol.
[0122] Austin Black is a carbon black filler.
[0123] Tecnoflon FPA-1 is a high tennperature processing aid from Solvay.
[0'124] MT Black is a carbon black filler.
[0125] Tecnoflon FOR SOHS and FOR 80I-IS are no (low) post cure bisphenol curable fluorocarbon elastomers frorx~ Solvay, with bisphenol curing agent formulated into the resin..
[0126] Dyxtaznic vulcanizates are made by a batch procedure according to tb.e recipes given in Examples 1-3. 1'he elastomer and plastic materials are mixed together in a Brabender mixer at 50 rpm and 190°C. The acid acceptor and other materials are then added to start the cure. T4ixin.g continues for about 10 minutes at 50 rpm and 190°C until a steady state mixing torque is achieved. After cure of the fluorocarbon elastomer is complete, as indicated by constant torque reading on the mixer, the vulcanizate is cooled to room temperature and ground into particulate form.
~3 attorney Docket No. 03-0047 (8470-000013) Example 1 Tngredient E~
la Phr Fluorel FE584070.0 Dyneon BRE ' 30.0 alar SOOLC 25.0 Rhenofit CF 6.0 Elastamag 170 3.0 Struktol WS-2801.0 Austin Black 10.00 '1'ecnoflon 1.00 FI'A-I ~

Examyle 2 Ingredient Ez Ex 1b Ex Ex Ex 2e 2a hr 2c 2d phr hr phr hr Tecnoflon FOR 100.0 100.0 100.0 100.0 100.0 50I;CS

Halar SOOLC 25.0 X0.0 100.0 1.50.0z00.0 ~

ldlastomag 3.0 3,0 3.0 3.0 3.0 x70 (Mg0) ~

i~'IT Btaek 10.0 10.0 10.0 1Ø0 10.0 (N990) ;

Struktol WS-?801.0 1.0 1.0 1.0 1.0 'I'ecnoflon 1.00 1.00 1.00 1.00 FPA-1 ~ t.00 ~4 Attorney Docket No. 03-0047 18470-000013) Example 3 Ingredient Ex Ex 3b E~x Ex Ex 3e 3a hr 3c 3d hr hr hr hr Tecnoflon FOR 100.0 y 100.0100.0 100.0 100.0 f~atar SOULC 25.0 50.0 100.0 150.0 200.0 Elastomag 170 3.0 3.0 3.0 3.0 3.0 (Mg0) &ZT Btacl: 10.00 10.00 10.00 10.00 10.00 (N990) Shruktol WS-?801.00 1.00 2.00 1.00 I.00 Tecnofton 1''PA-1'--i.01.0 1.0 1.0 I.0 ~ ~ ~ ~ ~

Exam a 4 [0127] A fuel hose is extruded from the d3mamic vulcanizate of Example I. Hoses are produced by extruding through a thin wall (,about 0.4 mm) or a thick wall (about 2 mm) extrusion die. The barrel and extrusion die are set at 230'C to 2~0°C. .A
larje amount of gas is generated during the extrusion process. A ventilation hale is requixed at the dowxlstxeam section of the extruder barrel to release the gases given off.
Extrusion of tile fuel hose is not possible without ventilation. When the extrusion is carried out with a gas ventilation hole, the extruded hose exhibits porous holes that are connected to each other to provide a pathway for gases. As a result of the interconnected porous structure, the hose performs poorly in an air leak test.
~xar~z~le S - Pre-MQIdin~ Heat Treatment [0128] The dynamic wlcanizzte of Example 1 is beat txeated in particulate form. The particles of the dynamic vulcanizate of Example 1 are exposed to a temperature o~ 230°C fox about 16 flours, with occasional agitation.
Thereafter the heat treated particles axe extruded into hoses as in Example ~. In contrast to the result in Attorney Dockec No. 03-00=t7 (5470-OOOOl3) Example 4, in this example; ,,vi.th pre-molding heat treatment, no gas i.s observed given off during the extrusion process. Further, no ventilation hole is required. Zn contrast to the results of Example 4, the extruded hose exhibits acceptable fuel vapor permeability properties.
Example 6 [0129] The dynamic wlcanizates of Examples 2 and 3 are exuvded into hoses as in Example 4, with either no pre-molding heat treatment (untreated), or with pre-txtolding heat treatment at 250°C for one hour (treated], where "pre-molding" heal treatment refers to heat treatment performed after dvnamio vulcanization but before extrusion. A hose extruded from the dynamic vulcanizate of Example ?
(untreated) gives a vapor permeation rate (vapor permeability) of 8 grams per square meter per day during exposure to fuel C at 40°C for 30 days according to ASTM 1J-814. A hose extruded from the dynatnic vulcanizate of Example 3 (untreated) exhibits a petrneation rate of 7. Hoses extruded from heat treated samples of Examples 2 and 3 give a lowered vapor permeation rate of 3. Vapor permeation rate is measured according to ASTM D-814 using fuel C.
Example 7 [0130] A hose is extruded from the dynamic vulcanizate of Example 1.
The particles of dynamic vulcanizate are either untreated (no pre-molding heat treatment]
or treated (heated at 230°C for J 6 hours prior to extrusion). The vapor permeation rate of the hose extruded from untreated dynamic vu)cani.zate is 50 grams per square meter per day, while that of the treated hose is 3.

Claims (45)

1. A method for making a shaped article comprising a cured fluorocarbon elastomer in a thermoplastic matrix, the method comprising:
heating a melt blend comprising fluorocarbon elastomer, polyol curative agent, accelerator and thermoplastic polymer material while applying shear for a time and at a temperature sufficient to cure the fluorocarbon elastomer, as determined by a constant mixing torque;
cooling the resulting dynamic vulcanizate and converting it to a particulate form;
heat treating the particulate dynamic vulcanizate by exposing it to a temperature of 150°C or greater for a time sufficient to remove at least some of the excess phenol curative remaining in the dynamic vulcanizate after cure;
thereafter heating the heat treated dynamic vulcanizate above its processing temperature; and processing the vulcanizate by thermoplastic techniques to make the shaped article.

2. A method according to claim 1, comprising melting the elastomer and thermoplastic together, then adding curative agent and accelerator to form the melt blend.

3. A method according to claim 1, comprising forming the melt blend by melt blending a cure incorporated elastomer composition and a non-curing thermoplastic, wherein the cure incorporated elastomer composition comprises the fluorocarbon elastomer, polyol curative agent, and accelerator.

4. A method according to claim 1, wherein the thermoplastic polymeric material comprises a fluoroplastic.

5. A method according to claim 4, wherein the thermoplastic polymeric material comprises a fully fluorinated fluoroplastic.

6. A method according to claim 4, wherein the thermoplastic polymeric material comprises a partially fluorinated fluoroplastic.

7. A method according to claim 1, comprising heat treating at 150°C or higher for at least one hour.

8. A method according to claim 7, comprising heat treating at 200°C or less for 2 hours or less.

9. A method according to claim 7, comprising heat treating at about 150°C
for about 1 hour.

10. A method according to claim 1, comprising heat treating at 230°C or higher.

11. A method according to claim 7, comprising heating for 5 hours or greater.

12. A method according to claim 1, wherein the processing temperature is greater than or equal to 230°C.

13. A method according to claim 1, wherein the processing temperature is greater than 290°C.

14. A method according to claim 1, wherein the curative agent comprises bispbenol A.

15. A method for processing a rubber composition comprising cured fluorocarbon elastomer, thermoplastic polymer material, and excess unreacted phenol curative agent into a shaped article, wherein the rubber composition is prepared by dynamically vulcanizing a fluorocarbon elastomer in the presence of a thermoplastic material and a phenol curative, the method comprising:
heat treating the rubber composition at 200°C or less for a time sufficient to drive off or decompose at least part of the phenol curative agent; and thereafter processing the beat treated dynamic vulcanizate by thermoplastic techniques to form the shaped article.

16. A method according to claim 15, comprising heat treating for less than 5 hours,

17. A method according to claim 15, comprising heat treating for one hour or less.

18. A method according to claim 15, comprising heat treating at 150° C
or less.

19. A method according to claim 15, comprising extruding the heat treated dynamic vulcanizate into a hose.

20. A method according to claim 18, comprising extruding the heat treated dynamic vulcanizate into a hose.

21. A method according to claim 15, wherein the thermoplastic polymeric material comprises a fluoroplastic.

22. A method according to claim 21, wherein the thermoplastic polymeric material comprises a fully fluorinated fluoroplastic.

23. A method according to claim 21, wherein the thermoplastic polymeric material comprises a partially fluorinated fluoroplastic.

24. A method for preparing a thermally processable rubber composition, comprising melt blending a cure incorporated elastomer composition and a non-curing thermoplastic polymeric material;
heating the melt blend while applying shear for a time and at a temperature sufficient to cure the elastomer to a constant torque reading; and cooling the melt blend to give the processable rubber composition, wherein the elastomer composition comprises a fluorocarbon elastomer, a phenol curative agent, and an accelerator, wherein the curative agent is present at a stoichiometric amount such that after cure the dynamic vulcanizate contains less than or equal about 0.5 phr unreacted phenol curative agent.

25. A method according to claim 24, wherein the phenol and accelerator are finely dispersed in the elastomer composition to provide sufficient reaction kinetics to complete the initial cure of the fluorocarbon to a constant torque reading in 15 minutes or less at 180 °C and to develop a final cure density in 2 hours or less of pre-molding heat treatment at a temperature of 200°C or less.

26. A method according to claim 24, wherein the fluorocarbon elastomer has a Mooney viscosity less than 100.

27. A method according to claim 26, wherein the Mooney viscosity of the fluorocarbon elastomer is about 40-80.

28. A method according to claim 26, wherein the fluorocarbon elastomer comprises a copolymer of HFP and VdF.

29. A method according to claim 25, wherein the elastomer composition comprises Tecnoflon FOR 50HS or Tecnoflon FOR 80HS.

30. A method for making polymeric shaped articles, comprising processing a processable rubber composition by thermoplastic techniques, wherein the processable rubber composition is made by a process according to claim 24.

31. A method according to claim 30, comprising extruding the processable rubber composition.

32. A method according to claim 30, comprising injection molding the processable rubber composition.

33. A method according to claim 25, wherein the final cure density is marked by achieving a constant value of at least one of compression set, tensile strength, and elongation at break.

34. A method according to claim 25, wherein a final cure density is reached in about 1 hour at about 150°C.

35. A low gas permeability hose, comprising an extruded dynamic vulcanizate, wherein the vulcanizate comprises particles of cured fluorocarbon elastomer in a continuous phase of a thermoplastic polymeric material, and the hose has a permeability characterized by a vapor permeation rate of less than 8 grams per square meter per day, measured according to ASTM D-814 using fuel C.

36. A hose according to claim 35, wherein the thermoplastic polymeric material comprises a fluoroplastic polymer material.

37. A hose according to claim 35, wherein the cured fluorocarbon elastomer particles comprised a polyol cured copolymer of tetrafluoroethylene, propylene, and vinylidene fluoride.

38. A hose according to claim 35, wherein the cured fluorocarbon elastomer particles comprised a polyol cured copolymer of tetrafluoroethylene, hexafluoropropylene, and vinylidene fluoride.

39. A hose according to claim 35, wherein the cured fluorocarbon elastomer particles comprised a polyol cured copolymer of hexafluoropropylene and vinylidene fluoride.

40. A hose according to claim 35, wherein the vapor permeation rate is less than 5 grams ger square meter per day.

41. A hose according to claim 35, wherein the hose has a vapor permeation rate of less than or equal to about 3 grams per square meter per day.

42. A hose according to claim 35, further comprising an extrusion layer on the extruded dynamic vulcanizate, wherein the extrusion layer comprises a non-fluorocarbon rubber and forms an outer layer of the hose.

43. A hose according to claim 42, wherein the non-fluorocarbon rubber is selected from the group consisting of EPDM rubber, butyl rubber, isoprene rubber, butadiene rubber, ABM, ACM, and silicone rubber.

44. A hose according to claim 35, further comprising an extrusion layer on the extruded dynamic vulcanizate, wherein the extrusion layer forms an outer layer of the hose and comprises a thermoplastic material or a thermoplastic elastomer.

45. A hose according to claim 44, wherein the extrusion layer comprises a nylon.