| Title of Invention | ARTICLES CONTAINING SILICONE COMPOSITIONS AND METHODS OF MAKING SUCH ARTICLES |
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| Abstract | The disclosure is directed to a method of making a silicone composition includes mixing a silicone formulation in a mixing device and adding an in situ adhesion promoter to the mixing device. The disclosure is further directed to articles made from the above-mentioned silicone composition. |
| Full Text | ARTTCLFS CONTAINING SILICONE COMPOSITIONS AND METHODS OF MAKING SUCH ARTICLES TECHNICAL FIELD This disclosuie, in general, relates to a method for making a silicone composition and articles including the silicone composition, nACKGROUND ART Curable silicone compositions are used in a variety of applications that rani-es from the automotive industry to medical devices. Typical commercial formulations of liquid silicone rubber (LSR) compositions include a nuiiti-component mixture of a vinyl-containing polydiorganosiloxane, a hydmgen-containing polydiorganosiloxane. catalyst, and filler, Often, the commercial formulation is a two-part formulation that is mixed together prior to use. Once the commercial foraiiilation is mixed, the silicone composition is subsequently molded or exhiided and vulcanized. In many cases, the silicone composition is coupled to a variety of substrates such as polymeric, metallic, or glass substrates, tor instance, silicone compositions are used as a coating or a laminate over a variety of polymeric substrates. Typically, a primer is used between the silicone composition and the substrate. Alternatively, the backbone of the silicone composition may be formulated to provide the silicone composition with adhesive properties to various substrates, such that a primer is optional. Often, such silicone compositions are refen-ed to as self-bonding silicone compositions. While self-bonding silicone compositions desirably improve bonding to panicular stibstrates. such compositions are generally orders of magnitude more expensive than other silicone formulations. In addition, manufactures of products that use such self-bonding silicone compositions are limited in their ability lo customize such formulations to better suit a particular product or process. As a result, manufacturers are otten left to choose between desired bonding propeitics or desired mechanical properties, without an option to acquire both. As such, an improved silicone formulations and method of manufacturing silicone-including aiticles would be desirable. DISCLOSURE OF INVENTION In a particular embodiment, a method of making a silicone composition includes mixing a silicone fonnnlation in a mixing device and adding an in sim adhesion promoter to the mixing device. In another embodiment, an article includes silicone formulation comprising a polyalkylsiloxane and an in situ adhesion promoter. The in situ adhesion promoter includes a Ci-g alkyl ester of maleic acid, fumaric acid, or any combination thereof and optionally, an organosilsesquioxane. In another exemplary cmbcKliment. an article includes a firsl layer comprising a polymeric material, a glass, or a metal and a second layer adjacent the first layer. The second layer includes a silicone fonnulation and an in situ adhesion promoter. The in situ adhesion prornoter is a Ci-a alkyl ester of maleic acid, fumaric acid, or any combination thereof and optionally, an organosilsesquioxane. In another excmplai-y embodiment, an article includes a silicone composition comprising a polyalkylsiloxane and a vinyl-containing silsesquioxane. The vinyl-containing silsesquioxane contains RSiOa;:units wherein R is an alkyl group, an alkoxy group, a phenyl gimip, or any combination thereof. hi a further exemplai^ embodiment, an article includes a first layer comprising a potymeiic material, a glass, or a metal and a second layer adjacent the first layer. The second layer includes a silicone formulalion and a vinyJ-containing silsesquioxane containing RSi03/21'i'^its wherein R is an alkyl group, an alkoxy group, a phenyl group, or combination thereof. BRIEF DESCWPTION OF THE DRAWINGS The present disclosure may be better understood, and its numerous features and advantages made apparent lo those skilled in the art by referencing the accompanying drawings. FIGs. I and 2 include illustrations of e.Tjemplarymbes. FIG. 3 includes graphical illustrations of data representing the perfonnance of exemplary tubes. DESCRIPTION OF TliF, EMBOniMENT(S) In a particular embodiment, a silicone composition includes a silicone formulation and an in situ adhesion promoter, stich as a silsesquioxane. The incorporation of the in situ adhesion promoter into the silicone formulation provides a silicone composition that adheres to substrates wiih desirable peel sti'ength. In particular, desirable adhesion may be achieved without a primer, Tlie silicone composition is typically prepared by homogeneously mixing tlie in sini adhesion promoter with the silicone fonnulation using any suitable mixing method. "In situ" as used herein refers to mixing the adhesion promoter and the silicone formulation prior to vulcanization of the silicone rubber. Tn an exemplary embodiment, the silicone formulation may include a non-polar silicone polymer. The silicone polymer may, for example, include poiyalkytsiloxanes, such as silicone polymers formed of a precursor, stich as dimelhylsiloxane, diethyl si loxane, dipropylsiloxane, methylethylsiloxane. methylpropylsiloxane. or combinations thereof. In a particular embodiment, the polyalkylsiloxane includes a polydialkylsiloxane, such as polydimethylsiloxane (PDMS). In a particular embodiment, the polyalkylsiloxane is a silicone hydride-containing polydimethylsiloxane. In a further embodiment, the polyalkylsiloxane is a vinyl-containing polydimethylsiloxane. In yet another embodiment., ihc silicone polymer is a combination of a hydride-eon laining polydiraethylailoxime and a vinyl-conlaining polydimethylsiloxane, In an example, the silicone polymer is non-polar and is free of halidc functional groups, such as chlorine and fluorine, and of phenyl functional groups. Alternatively, the silicone polymer may include halide functional groups or phenyl functional groups. For example, the silicone polymer may include fluorosilicone or phcnylsilicone. Typically^ the silicone polymer is elastomeric. For example, the diuometer (Shore A) of the silicone polymer may be less than about 75, such as about 1 to 70, abotit 20 to about 50, about 30 to about 50, about 40 to about 50, or aboul I to about 5, Jn particular, the silicone compositions including the in situ adhesion promoter and the process for fonmilating sxich a composition may advantageously produce low durometer silicone elastomers having desirable nieehanieal properties. For example, a silicone elastomer having a Shore A durometer not greater than 30, such as not gieatcr than 25, and having desirable mechanical properties may be formed. The silicone fomiutation may ftirther include a catalyst and other optional additives. Exemplai-y additives may include, individually or in combination, fiilei's, inhibitors, colorants, and pigments. In an embodiment, the silicone fomiulation is a platinum catalyzed silicone formulation. Ahernatively, the silicone fonnulation may be a peroxide catalyzed silicone formulation. In another example, the silicone foi'mulation may be a combination of a platiniun catalyzed and peroxide catalyzed silicone fonnulation, The silicone fomiulation may be a room temperature vulcanizable (RTV) formulation or a gel. In an example, the silicone formulation may be a liquid silicone nibber (LSR) or a high consistency gum mbber (HCR). In an embodiment, the silicone formulation may include silicone foams, for example, an HCR silicone foam, such as platinum cured HCR silicone foam. Jn a particular embodiment, the silicone formulation is a phtimim catalyzed LSR. In a ftirther embodiment, the silicone formulation is an LSR formed from a two-part reactive system. The silicone formulation may be a conventional, commercially prepared silicone polymer. The commercially prepared silicone polymer typically includes the non-polar silicone polymer, a catalyst, a filler, and optional additives, "Conventionfil" as used herein refers to a commercially prepared silicone polymer that is free of any self-bonding moiety or additive. Particular embodiments of conventional, commercially prepared LSR include Wactcer Elastosil® LR 3003/50 by Wacker Silicone of Adrian, MI and Rhodia Silhione® LSR 4340 by Rhodia Silicones of Ventura, CA. In another example, the silicone polymer is an HCR, such as Wacker Elastosil® R4000/50 available from Wacker Silicone,. In an exemplary embodiment, a conventional, commercially prepared silicone polymer is available as a two-part reactive system. Part 1 typically includes a vinyl-containing polydiatkylsiloxane, a filler, and catalyst. Part 2 typically includes a hydride-containing polydialkylsiloxane and optionally, a vinyl-containing polydialkylsiloxane and other additives, A reaction inhibitor may be included in Part 1 or Part 2. Mixing Part 1 and Part 2 by any suitable mixing method produces the silicone formulation. In an embodiment, the in silu adhesion promoter, such as silsesquioxane, is added to the mixed two-part system or dizring the process of mixing the two-part syiilem. As stated earlier, the in silu adhesion promoter is added to the conventional, commei-cially prepared silicone polymer prior to vtilcanizalion. In an exemplary embodiment, the two-parl system and the in sit^l adliesion promoter are mixed in a mixing device. In an example, the mixing device is a mixer in an injection molder. In another example, the mixing device is a mixer, such as a dough mixer, Ross mixer, two-roll mill, or Drabender mixer. In conlrabt Ui adding the in situ adhesion promoter during or after mixing and prior lo vulcanizalion, typical self-bonding silicone compositions that are commercially available incorporate an additive during an earlier stage of preparing the silicone rubber. Typically, the additive is incoiporated into the precursor while preparing the polyalkylsiloxane, and often, modifies the polyalkylsiloxane chain. hi an embodiment, the in situ adhesion promoter may include vinyl siloxanc or silsesquioxane. Jn an example, the silsesquioxane includes an organosilsesquioxane or a vinyl-containing silsesquioxane. For example, the vinyl-containhig silscsquioxanc may include RSiOj/^ units, wherein R is a vinyl group, an aJkyl group, an alkoxy group, a phenyl gi'oup, or any combination tliereof. Typically, the silsesquioxane has a vinyl content of at least about 30.0% by weight. In an embodiment, the alkyl or alkoxy gi'oup includes a Ci.6 hydi-ocarbon group, such as a methyl, ethyl, or propyl group. The in situ adhesion promoter may inchide R2Si02/: units, R3SiOi/2 units and Si04/2 units, wherein R is an alkyl radical, alkoxy radical, phenyl radical, or any combination thereof. In an embodiment, the vinyl-containing .silsesquioxane may include pre-hydrolyzed silsesquioxane prepolymers, monomers, or ohgomers. In addition, the silsesquioxane may have desirable processing properties, such as viscosity. In particular, the viscosity may provide for improved processing in situ, such as during silicone fomiulation mixing or extrusion. For example, the viscosity of tlie silsesquioxane may be about! .0 ceniistokes (cSt) to about K.O cSl, such as about 2,0 cSt to about 4.0 cSl, or about 3.0 cSt to about 7.0 cSt. In an example, the viscosity of the silsesquioxane may he up to about 100.0 cSt, or even greater than about lOO.O cSt. Typically, the addition nf the vinyl-containing silsesqtiioxane in situ adhesion promoter to the silicone composition is detectable using nuclear magnetic resonance (NMR). The ^^Si NMR spectra of the sihcone formulation has two groups of distinguished peaks at about -65 ppm to about -67 ppm and about -72 ppm to about -75ppm, which coiTesponds to ViSi02/2 (OH) units and ViSiO?^units, respect ively. In an embodiment, the in situ adhesion promoter may include an ester of unsaturated aUphatic carboxylic acids. Exemplary esters of unsaturated aliphatic carboxylic acids include Ci.s alkyl esters of maleic acid and CLB alkyl esters of fumaric acid. In an embodiment, the alkyl group is methyl or ethyl. In an example, ihe maleic acid is an ester having the general formula; ? R'O C C=C C OR' wherein R' is a Ci.s allcyl gi'oup. In an embodiment, R' is methyl or ethyl. In a particular enil>odiment. the in silu adhesion promoter is dimethyl maleate, diethyl maleaie, or any combination thereof. Jn an embodiment, one or mord of the abt>ve-meniioned in siUi adhesion promoters may be added to the silicone formulation, For instance, the in situ adhesion promoter may include a mixture of the silsesquioxane and the ester of unsaturated aliphatic carboxylic acid. In an embodiment, the silsesiquioxane is an organosilsesquioxane wherein the organo gi'Oiip is a CMS alkyl. In an embodiment, the in situ adhesion promoler is a mixture of the organosilsesqiiioxane and diethyl maleate. In another embodiment, the in situ adhesion promoter is a. mixture of the organosilsesquioxane and dimethyl maleate. In a particular embodiment, the mixture of the organosilsesquioxane and the ester of unsaturate aliphatic carboxylic acid is a weight ratio of about 1,5 : 1.0 to about 1.0; 1.0. Generally, the in situ adhesion promoter is present in an effective amount to provide an adhesive fomuilation which bonds to substi'ates. In an embodiment, an "effective amount" is about 0.1 weight % to about5,0 weight %, such as about 0.1 wl% to about 3.0 wt%, such as about 1.0 wt%to about 3.0 wt%. or about 0.2 wt% to about I.O wt% of the total weight of the silicone polymer. The silicone composition containing the in situ adhesion promoter may exhibit improved adhesion to substrates. Typical subslrates include polymeric materials such as thennoplastics and therniosets. An exemplary polymeric material may include polyatnide. polyaramide, polyimide, polyolefin, polyvinylchloride, aci7lic polymer, diene monomer polymer, polycarbonate (PC), polyetheretherketone (PEEK.), poly ether imide (Ultem), polyphenylsulfone (Radel), tluoropolymer, polyester, polypropylene, polystyrene, polyurethane, themioplastic blends, or any combination thereof. Further polymeric materials may include silicones, phenolics, epoxys, glass-filled nylon, or any combination thereof. In a paniculai- embodiment, the substrate includes PC, PEEK., fluoropolymer, or any combination thereof. The silicone composition and the substrate can be used to form any usefiil article. To form a useftil article, the polymeric substrate may be processed. Processing of the polymeyic substrate, particularly the thcraioplastic substrates, may include casting, extiiiding or skiving, In an example, the substrate is a fluoropolymer. An exemplary fluoropolymer may be formed of a homttpolymer, copolymer, lerpolymcr, or polymer blend fomied from a monomer, such as tetrafluoroethylene, hexafluoropropylene. chlorotrifluoroethylene, trifltioroethylene, vinylidene fluoride, vinyl fluoride, perfluoropropyl vinyl ether, periluoromelhyl vinyl ether, or any combination thereof. For exaniple, the fluoropolymer is polytetrafluoroethylene (PTFE). In an embodiment, the polytetrafluoroetbylene (PTFE) may be paste extruded, skived, expanded, biaxially stretched, or an oriented polymeric film. In an exemplary embodiment, the fluoropolymer is a heat-shrinicable poly tetrafluoroethylene (PTFE). The heal-slirinkablc PTFE of the disclosure has a stretch ratio not greater than about 4:1, such between about 1.5:1 and about 2.5;l. In an exemplary embodiment, the hcat-shrinkable PTFE is not stretched to a node and fibrilc stnicturc, In contrast, expanded PTFE is generally biaxially expanded at ratios of about 4:1 to form node and tibrile stnicturcs. Rence, the heat-shririkablc PTFE of tlie disclosttrc maintains chemical resistance as well as achieves tlcxibility. Further exemplary fluoropoiymers include a fluorinated ethylene propylene copolymer (FEP), a copolymer of tetrafluoroethylene and perfluoropropyl vinyl ether (PFA), a copolymer of tetrafluoroethylene and perfluoromethyl vinyl ether (MFA), a copolymer of ethylene and letranuorc>ethylene(ETFE), a copolymer of ethylene andchlorotrinuoroethylene(ECTFF,), polychlorotrifltioroethylene (PCTFE), poly vinylidene fluoride (PVDF), a terpolymer including tetrafluoroethylene, hexafluoropropylene, and vinylidenefluoride (THV), or any blend or any alloy thereof For example, the fluoropolymer may incltide FEP. In a further example, the fluoropolymer may include PVDF. In an exemplary embodiment, the fluoropolymer may be a polymer crosshnkable through radiation, such as e-beam, An exemplary crosslinkable fluoropolymer may include ETFE, THV, PVDF, or any combination thereof A THV resin is available fram Dyneon 3M Corporation Minneapolis, Minn, An ECTFR polymer is available from Ausimont Corporation (Italy) under the trade name Halar. Other fluoropolymers used herein may be obtained fi'om Daikin (Japan) and DuPont (USA). In particular, FEP fluoropolymers are commercially available from Daikin, such as NP-12X. Other substrates include glass and metals. An exemplaiy glass may include boroaluminosilicate. silicate, aluminosilicate, or any combination thereof. An exemplary metal may include stainless steel, steel, titanium, aluminum, capper, or any combination thereof. In general, the silicone foraiLtlation including the in situ adhesion promoter exhibits desirable adhesion to a substrate without fiuther treatment of the substrate surface. Alternatively, the substrate may he treated to tijilher enhance adhesion. In an embodiment, the adhesion between the substrate and the silicone composition may be improved through the use of a variety of commercially available surface treatment of the substrate. An exemplary surface treatment may include chemical etch, physical-mechanical etch, plasma etch, corona treatment, chemical vapor deposition, or any combination thereof In an embodiment, the chemical elch includes sodium ammonia and sodium naphthalene. An exemplary physical-mechanical elch may include sandblasting and air abrasion. In anoUier embodiment, plasma etching includes reactive plasmas such as hydi'ogen, oxygen, acetylene, methane, and mixtures thei-eof with nitrogen, argon, and helium. Corona irealmeiil may include the reactive hydi-ocarhon vapors such as acetone. In an embodiment, the chemical vapor deposition includes the use of aeiylates, vinylidene chloride, and acetone. Onee the article is fomied, the article may be subjected to a post-cure U^eatment, such as a ihennal treatment or radiative curing. Thermal treatment typically occurs at a temperature of about 125^0 to aboiu 200*^0. In an embodiment, the tliennal treatment is at a temperature of about ISO'^C to about 180°C. Typically, the thermal treatment occm'S fora time period of about 5 minutes to about 10 hours, such as about 10 minutes to about 30 minutes, or ahematively about 1 hour to about 4 hours, In an embodiment, radiation crosslinking or radiative curing may be performed once the article is fomied. The ludiation may be effective to crosslink the silicone composition. The uitralayer crosslinidtig of polymer moiecutes within the silicone composition provides a ctired composition and imparts structural strength to the silicone composition of the aiticle. In addition, radiation may effect a bond between the silicone composition and the substrate, stich as through inlerlayer crosslinking, In a particular embodiment, the combination of interlayer crosslinking bonds between the substrate and the silicone composition present an integrated composite that is highly resistant to dclamination, has a high quality of adhesion resistant and protective surface, incoiporates a minimum amount of adhesion resistant material, and yet, is physically substantial for convenient handling and deployment of the article. In a particular embodiment, the radiation may be ultraviolet electio magnetic radiation having a wavelength between 110 nm and AIM) nm, such as about 170 nm to about 220 nm. In an example, crossUnking may be effected using at least about 120 J/cm" radiation. In an exemplary embodiment, the silicone composition advantageously exhibits desirable peel strength when applied to a substrate. In particular, the peel strength may be significandy high or the layered strticttire may exhibit cohesive failure during testing. "Cohesive failui"e" as used herein indicates that the silicone composition or the substrate mptures before the bond between the silicone composition and the subsU'ate fails. In an embodiment, the article has a peel strength of at least about 0.9 pounds per inch (ppi), or even enough to lead to cohesive failure, when tested in standard "180""-Peel configuration at room temperature prior to any post-cure, or may have a peel strength of at least about 10.0 ppi after post-cure treatment when adhered to a polymeric substrate. For example, before post-cure treatment, the silicone composition may exhibit a peel strength of at least about 0.6 ppi. such as at least about 1,2 ppi, such as at least about 4.0 ppi, such as at least about 10.0 ppi, such as at least abotit 14.0 ppi. or even at least about 20.0 ppi when adhered to polycarbonate. After treatment, the silicone composition may exhibit a peel strength of al least about 10.0 ppi, such as at least about 16.0 ppi, such as at least about 20.0 ppi. such as at least about 29.0 ppi, such as at least about 35,0 ppi. such as at least about 50.0 ppi, or even cohesively fail during the lest when adhered to polycarbonate. In another example, the peel strength of the article may be at least about 1.6 ppi, such as at least abotit 2.0 ppi, such as at least about 5.0 ppi. such as at least about 7.0 ppi, such as at least about 11.0 ppi, such as al least about 13.0 ppi. such as at least about 20.0 ppi, or even enough to lead to cohesively fail during testing when the substrate is polyetheretherkelone and prior to any post-cure. Wlien the substrate is polye the retherke tone, the article may have a peel strength ofal least about 2.9 ppi, such as atlenst about 8.0 ppi, such as at least about 12.0 ppi, such as al least about 20.0 ppi, such as at least about 25.0 ppi, stich as at least about 55.0 ppi, such as at least about 64.0 ppi, or even enough to lead to cohesively fail during testing after post-cure treatment. When the substrate is polyester, the article may have a peel strength of al least about 0.8 ppi, such as at least about 2.6 ppi, such as at least about 9,0 ppi, such as al least about 15.0 ppi, such as about 22.0 ppi or even cohesively fail prior to any post-cure. After treatment, the silicone composition may exhibit a peel stiength of at least about 50.0 ppi, such as at least about 65.0 ppi, such as at least about 80.0 ppi, or even cohesively fail during the test when adhered to polyester. When the substrate is polyetherimide, the article may have a peel strength of at least about 1.8 ppi, such as at least about 3.0, such as at least about 8.5 ppi, such as at least about 20.0 ppi, or even cohesively fail prior to any post-cure. After treatment, the silicone composition may exhibit a peel strength of at least about 17.0 ppi, suchasatleast about 40.0 ppi, such as at least about 63.5 ppi. or even cohesively fail when adhered to polyetherimide. When the substrate is polypheny Is ulfone, the article may have a peel strengQi of at least about 3,2 ppi, such as at least about 26.0 ppi, or even cohesively fail prior to any post-cure. ARer treatment, the silicone composition may exhibit a peel sti-ength of at least about 51.0 ppi, such as at least about 75.0 ppi, or even cohesively fail when adhered to polyphenylsulfbne. In addition to desirable peel strength, the silicone compositions have advantageous physical properties, such as improved elongation-at-break, tensile strength, or teai- strength. Elongation-at-hreak and tensile strength are dctennincd using an Instron instrument in accordance with ASTM D-412 testing methods. For example, the silicone composition may exhibit an elongation-at-break of at least about 350%, such as at least about 500%, at least about 550%, at least about 600%, at least about 650%, or even at least about 700%. In an embodiment, the tensile strength of the silicone composition is greater than about 400 psi, and in particular. Is at least about 1100 psi, such as at least about 1200 psi, such as at least about 1250 psi, or even at least about 1500 psi. Paiticular embodiments exhibit a desirable combination of elongation and tensile strength, such as exhibiting a tensile strength of at least about 800 psi and an elongation of at least about 500%. Further, the silicone composition may have a tear strength greater than about 100 ppi, such as at least about 150 ppi, such as at least about 225 ppi, such as at least about 250 ppi, or even al least about 300 ppi, The silicone formulation can be used to form articles such as monolayer articles, multilayer articles, or can be ]aminated. coated, or formed on a substrate. In an example, the silicone formulation may be used to fonn a multilayer film or tape. The silicone fomiulation may be used as a film or tape to provide a barrier layer or a chemical resistant layer. Alternatively, the silicone fonnulation may be used to form an irregularly shaped article. Further, the silicone fomiuladon may be used to form fabrics, reinforcements, or foams. Fabrics and reinforcement articles may include glass mats, fiberglass, and polymeric braids such as polyamide or polyester braids. In an embodiment, the article includes a silicone formulation of liquid silicone rubber (LSR) or high consistency rubber (HCR). The article may include processing of the liquid silicone rubber or high consistency gum rubber. For example, processing ofLhe liqtiid silicone rubber may include any suilable method such as co(npresj;ion molding, overmoldtng, liquid inJGClion molding;, co-processing of the LSR with a thermoplastic material, coating, or processing as a thin film, In another example, processing of the higli consistency rubber may include any suitable method such as extrusion, jacketing, braiding, processing as a lilm, compression molding, and overmoldtng. Applications for the silicone formulations arc numerous. The silicone formulation may be used as laminates, tie layera, insulators, medical devices, silicone adhesives, coated fabrics, and tubing and hoses. For instance, the silicone fonnulation may be used as a laminate to produce articles such as, for example, multilayer films, barrier and chemical resislaiit films, anaJjIical septa, and bearings. An ejcemplaiy multilayer film includes a PTFE layer, a silicone fonnulation layer, and a metal layer. Another exemplaiy multilayer film includes a PTFE layer, a silicone foiTniilation layer, and a thcnnoplastic layer. The silicone fomiulation may be used as an insulator. The silicone formulation may be used to produce articles such as, for example, wires and cables, electrical and thennal insulators, insulators for high temperature applications, and insulators to control heal transfer. In an example, the silicone fomiulation is used with a nielal as the substi'ate. Further, the silicone formulation may be used in medical devices. The silicone fonnulation may be used to produce articles such as two-component medical devices. Exemplary medical devices include surgical tools or any suitable application for operator comfort. Tn an example, the medical device may include a thermoplastic and the silicone formulation. In another example, tlie medical device may include a metal and the silicone formulation. In another example, the silicone formulation may be used as a silicone adhesive, Parlictilariy, ihe silicone formulation may be used as a bonding agent for cured silicone nibber. In an example, the silicone formulation may be used to bond a silicone to another silicone. In another example, the silicone forauilalion may be used Lo bond another material to a silicone, such as a lie layer to bond a thermoplastic to a silicone. The silicone formulation may also be used to bond surface modified lluoropolymer to metal, such as sodium naphthalene etched PTFE to steel. The silicone formtilation may be used for coated fabrics. The silicone formulation may be used to produce coated articles such as temperature resist ai-ticles, non-stick bakeware, heat-resistant gloves. or protective coatings for glass. In an example, the silicone formulaiion is used to coat fiberglass, In yet anoliier embodiment, the silicone fomiuiation may be used to produce tubing and hoses. The silicone formulation can be used as tubing or hosing to produce chemically resistant pump tubing. reinforced hosing, chemically resistant hosing, braided hosing, and low penneabiiity hosing and tubing, In a particular embodiment, the aiiicle may be a monolayer tube or multilayer tube. For example, the multi-layer tube may include a liner and a cover. The liner may include a low surface energy polymer, for example, a fluoropolymer. The cover may inchide the silicone composition and directly contacts the liner. In an exemplary embodiment, (he muUi-Uyer tube also may include an intermediate layer sandwiched between the liner and the cover. The intermediate layer may include, for example, an adhesive layer. As illustrated in FIG. L, the silicone fonuulation is used to produce a multi-layer mbe 100. The multi-layer tube 100 is an elongated annular stnicUirc with a hollow central bore. The multi-layer tube 100 incltidcs a cover 102 and a liner 104. The cover 102 is directly in contact with and may be directly bonded to a liner 104 along an outer surface 108 of the liner 104. For example, the cover 102 may directly bond to the liner 104 without intervening adhesive layers. In an exemplary embodiment, the multi-layer tube 100 includes two layers, such as the cover 102 and the liner 104, In an exemplary embodiment, the Jiner 104 is a fliioropolymer. Alternatively, a multi-layer tube 200 may include Iwo or more layers, such as three layers. For Gx-drnp)e, FIG, 2 illustrates a third layer 206 sandwiched between Jiner 204 and cover 202. In an exemplary embodiment, third layer 206 is directly in contact with and may be directly bonded to the outer surface 208 of the liner 204. In such an example, the third layer 206 may directly contact and may be bonded to cover 202 along an outer surface 210 of third layer 206, In an embodiment, the third layer 206 may be an adhesive layer Returning to FIG, i, tlie multi-layer tube 100 may be formed through a method wherein the elastomeric cover 102 is extruded over the liner 104. The liner 104 includes an inner smface 112 that defines a central lumen of the tube. In an exemplary embodiment, the liner 104 may be a paste-extruded fluoropolymer. Paste extrusion is a process that inchides extniding a paste of a lubricant and a PTFE powder. Typically, the PTFE powder is a fine powder fihrillated by application of shearing forces. This paste is extruded at low temperature (not exceeding 75'^C). In an embodiment, the pasts is extnided in the form of a tube. Once the paste is extruded, the PTFE may be stretched to a ratio of less than about 4:1 to form heat shrinkable PTFE. In an embodiment, the multi-layer tube 100 may be produced without the use of a mandrel during the laminating process, and the heat-shrink PTFE linei- is produced without mandi'cl wrapping. Prior 10 exhTJsion of the cover 102, adhesion between the liner 104 and the cover 102 may be improved thi'ough the use of a surface treatment of the outer surface 108 of die liner 104. In an embodiment, radiation ci'osslinking may be perfonued once the multi-layer tube 100 is tbrmed. hi general, the cover 102 has greater thickness than the liner 104. The total tube thickness of the multi-layer Uibe 100 may be at least about 3 mils to about 50 mils, such as about 3 mils to about 20 mils, or about 3 mils to about 10 mils. In an embodiment, the liner 104 has a thickness of about 1 rail to about 20 mils, such as about 3 mils to about 10 mils, or about 1 mil to about 2 mils. Once formed and cured, particular embodiments of the above-disclosed multi-layer tube advantageously exhibit desired properties such as increased lifetime and flow stability. For example, the multi-layer tube may have a pump life of greater than about 250 hours, such as greater than about 350 hours. In an embodiment, a mnlti-layer Uibe including a liner iomied of a hcai-shrinkable fluoropolymer is parlicularly advantageous, pmviding improved lileLime. In a ruriher embodiment, a liner Ibnned of a sodium-napthalene etched heat-shrinkable fluoropolymer is panicularly advantageous, reducing delamination of the liner and the coating, In an exemplary embodiment, ihe multi-layer tube may have less than about 30% loss in the dclivei7 rate when tested for flow stability, in particular, the loss in the delivery rate may be less than about 60%, such as less than about 40%, or such as less than about 30%, when tested at 600 rpm on a standai'd pump head. EXAMPLE 1 Five formulations are prepared for a performance study. Specifically, three vinyl-containing silsesquinxanes are added to two commercial LSR formulations. The vinyl-containing silsesqtiioxanes are commercially available from Gelest. Technical data of the vinyl-containing silsesquioxanes is illustrated in Table 1. The silicon LSRs are Wacker product 3003/50 and Rhodia product 4340. Formulation data is illustrated in Table 2. The low viscosity vinyl-containing silsesquioxanes are incorporated easily into the LSRs during the two part mixing step, rising a dough mixer. The additive loading level was between 0.5 to 2% by weight of LSR (phr, part per hundred pan of nibber). Table 1. Properties of Silsesquioxane In-Situ Adhesion Promoter Allcoxy group Density (g/cm^) Visco.sity (cSt) VFF-005 Ethoxy 1.02 4-7 VMM-010 Methoxy 1,10 8-12 VPB-005 Ethoxy 1.02 3-7 Table 2. Example Formiilaiions Matrix Additive % of additive (phr) FoiTnulation 1 Wacker 3003/50 VEE-005 0.75 Formiilalion 2 Wacker 3003/50 VMM-010 0.75 Formulation 3 Rhodia 4340 VEE-005 0,75 Fomiulation 4 Wacker 3003/40 VPE-005 1,5 Formulation 5 Wacker 3003/50 VPE-005 1.5 Th^: mechanical properties of the five fonmilalions are evaluated. The test slabs arc compression molded at \1TC for 5 mimitcs and post-ctu'ed at 177°C for 4 hours. Tensile propeities, such as tensile strength and elongation-at-break, are evaluated on an Instron using ASTM D-412. Tear tests are performed on an InsU-on according to ASTM D-624 and haixlness measurements are cairied out on a Shore A duroraeler, following the procediu-e of ASTM D-2240. Compression set measiuements are carried out according to ASTM 0-395, The results are summarized in Table 3. Table 3. Properties of Silicone FoiTnulations Tensile strength (psi) Elongation 200% modulus (psi) Tear strength (ppi) Durometei' (shore A) Com p. Set (%) Formulation 1 1212 850 255 251 39 37 Formulation 2 210 355 128 32 23 40 Formulation 3 251 509 115 34 18 69 Formutiition 4 402 674 113 63 23 44 FoiTnulation 5 1104 6% 288 226 40 19 EXAMPLE 2 The adhesion properties of Formulations 1 to 5 on thei-mal plastic substrates are evaluated. The thermal plastic substrates include the following: two commercial polycarbonate substrates, GE Lexan and Bayer Sheffield, a polyetheretherketone (PEEK) substi-ate, a polyester substrate, and a polyethcrimide substrate (GE UUcm), Self-bonding films having a thickness of about 0.5mm to abotit 1.5mm arc compression molded onto the substrates and the molding conditions are identical to physical test slabs described in Example 1. A mylar film is also molded onto the back of the silicone rtibber in the same step to prevent elongation during the peel test. The peel test uses an Instron 4465 testing machine. Both silicone layer and the substrate are clamped into the Instron grip. The grip then transvcrses in the vertical direction at the rate of two in/min. which pulls the silicone 180° away from llie substrate. The 180°peeltestresults arestimmari7fidinTables4and5. Table 4 illustrates the peel strength prior to treatment, and Table 5 incltides peel strength after post cure at 177°C for 4 hovirs. Comparison data for base rubber Wacker 3003/50 on selected substrates is also included. Tabic 4. Peel Strength Prior to Treatment Peel strength (ppi) Polycarbonate PEEK Polyester Ultcm Lex an Sheffield 3003/50 0.2 0.1 0.4 0.4 0.1 Foimulation I 27.3 4.3 tl.6 22.3 8.5 Formulation 2 C.F. C.F, C.F, C.F. / Fonmilation 3 C.F, C.F, C.F, C.F. / Foniiulation 4 C.F. 0.9 7.4 C.F. / Formulation 5 34.7 3.8 3,9 48.1 / Table 5. Peel Strength after Po.st-Ciire Treatment Peel strength (PPO Polycarbonate PEhK Polyester Ultem Lexan Sheffield 3003/50 1.4 1.7 1.2 1.1 0.9 FoiTTiulalion I 57.7 24.4 68.5 76.4 17.7 Formulation 2 C.F. C.F, C.F. C.F, / Formulation 3 C.F. C.F. C.F. C.F. / Formulation 4 C.F. C.F. 8.2 C.F. / Formulation 5 92.9 40.6 30.4 65.5 / Before and after post-cure treatment. Formulations 1 -5 bond with greater peel strength than Wacker 3003/50 on all five substrates. In particular, cohesive failure is observed in Formulations 2, 3, and 4, Hence, the adhesion force is greater than the strength of the silicone rubber. Typically, the peel strength is greater than 20 ppi when cohesive failure occurs. EXAMPLE 3 The adhesion properties of Fomiulaiions 1 and 5 on themiai set polyiners are evaluated. The thermal set polymeric substrates include the following; extrusion grade HCR mbber(Waclcer 4105/40), aciylics (Plexi glass) and phenolic resin (Garolite), Self-bonding LSR films having a thickness of about 0.5mm to about 1,5mm are compression molded onto the substrates and the molding conditions are identical to physical test slabs described in Example 1. The peel test results are summai-ized in Tables 6 and 7. Table 6 illustrates the peel strength prior la treatment, and Table 7 includes peel strength after post cure at 177°C for 4 hours. Table 6, Peel Strength Prior to Treatment Peel strength (PPO IICR rubber Phenolic resin Acrylics Formulation 1 C.F, C.F. CF Formulation 5 C.F. C.F. / Table 7. Peel Strength after Post-Cui'e Treatment Peel strength (Ppi) IICR rubber Phenolic resin Acrylics Fonnulation ! C.F. C.F. 0,3 Forraulation 5 C.F. CF, / Formulation t exhibits cohesive failiu-e prior to post-cure IrL^almenl on all Lliree substratcb. Foi-mulation 5 exhibits cohesive failin'e prior lo post-cure treatment on both HCR rubber and phenolic resin. Cohesive failure occurs when the adhesion force is greater than the strength of the silicone rubber. Typically, the peel strength is greater than 20 ppi when cohesive failure occurs. Post-cure, both Formulations 1 and 5 exhibit cohesive failure on HCR rubber and phenolic EXAMPLE 4 The adliesion properties of Formulations 1 and 5 on glass me evaluated The glass substrate is borosilicate. Self-bonding LSR films having a thickness of about 0.5mm to about 1.5mm are compression molded onto the subsn-ates and the molding conditions are identical to physical test slabs described in lixample 1. The peel test results are summari/i^d in Tables S and 9, Table 8 illustrates the peel strength prior to treatment, and Table 9 includes pcci strength aficr post ciu-e at 177°C for 4 ho^irs. Table S. Peel Sti-ength Prior to Treatment Peel strength (PPi) Borosilicale glass Fonnulation 1 C.F, Fimnulation 5 C.F, Table 9. Pee! Strength after Post-Cure Treatment Peel strength (PPO Borosilicatc glass Formulation 1 C.F. Formulation 5 C,F. On borosilicate glass, both Formulation 1 and 5 exhibit excellent peel strength with cohesive failure prior to post-cure treatment and after post-cure treatment. Cohesive failure occurs when the adhesion force is greater than the strength of the silicone mbber. Typically, the peel strength is greater than 20 ppi when cohesive failure occurs. EXAMPLE 5 The adhesion properties of Formulations 1 and 5 on metal are evaluated. The metal substrates include the following: steel, stainless steel, akiminum, copper, and titanium. Self-bonding LSR films having a thickness of about 1.0mm to about 1.5min are compression molded onto the substrates and the molding conditions are identical to physical test slabs described in Example 1. The peel test results are summari/Ajd in Tables 10 and 11. Table 10 illustrates the peel strength prior to treatment, and Table 11 includes peel strength after post cure at 177°C for 4 hours. Comparison data for Wacker 3003/50 on selected substrates is also included. Table 10. Peel Stvcnglh Prioi to Treatment Peel strength (ppO Steel Stainless sLeel ahiminiim copper titanium 3003/50 0.4 0,2 0.4 0.2 0.1 Fomiulation 1 59.8 56.7. 20.9 19.7 31.3 Fomiulation 5 61.2 63.8 21.0 23.4 29.7 Table U. Peel Strength after Post-Ctire Treatment Peel strength (PPi) Steel Stainless steel aluminum copper titanium 3003/50 0.7 0.4 0,7 0.9 0.6 Formulation 1 79.2 74,8 58,3 39,8 47.9 FonTiuiation 5 82.6 72.7 65.2 42,5 52.4 On metal substrates, both Formulation 1 and 5 exhibit excellent peel strength with greater peel strength compared to conventional Wacker 3003/50 prior to post-cure treatment and ader post-cure ireaimenl. Cohesive l^ilure is observed. Hence, the adhesion force is greater than the strength of the silicone mbber. The peel strength is typically greater than 20ppi when cohesive failure occurs. EXAMPLE 6 The adhesion properties of Formulations 1 and 5 on sodium naphthalene etched PTFh are evaluated. Self-bonding LSR films having a thickness of about 1.8mm is compression molded onto the substrates and the molding conditions are identical to physical test slabs described in Example 1. The peel test results are summarized in Tables 12 and 13, Table 12 illustrates the peel strength prior to treatment, and Table 13 includes peel strength after post ctire at 177°C for 4 hoiu-s. Comparison data for base rubber Wacker 3003/50 substrates is also included in the same table. Table 12. Peel Strength Prior to Treatment Peel strength (ppi) Na Naphth etched PTFE Formulation 1 21.9 Foi-mulation 5 24.6 3003/50 1,7 Table 13. Peel Strength alter Posl-Curc Treatment Peel strength (ppi) Na Naphth etched PTFE Formulation 1 40.8 Formulation 5 43.2 3003/50 3.8 On sodium naphthalene etched PTFE. both Formulation 1 and 5 exhibit excellent peel strength with greater peel strength and cohesive failure compared to conventional Wacker 3003/50 prior to post-cure treatment and after post-cure treatment, Cohesive failure occurs when the adhesion force is greater than the strength of the siHcone rubber. Typically, the peel strength is greater than 20 ppi when cohesive failure occtirs. EXAMPLE 7 This example illustrates the use of self-bonding LSR as coating onto a range of substrate materials. The metal stibstrates include the following: fiberglass mat, colloidal silica (Ludox®) treated PTFE and stainless steel. A 0.2mm thin film of Formulation 1 was coated onto the substrate using a slab mold. Vulcanization occttrs in tlie slab mold at 177'C for 0.5 minutes and the specimens are further post-ctire for 4 hours at 177'C. The adhesion properties of the silicone film on these substrates are measured by the ISO'^C peel test as described above and the results ai'e summarized in Table 14. Table 14. Peel Strength after Post-Cure Treatment Peel strength (PPi) Fiberglass mat Ludox silica treated FTFE Stainless steel Foramlation 1 22.8 23.8 25.0 On all three substrates. Formulation 1 has excellent peel strength. EXAMPLE 8 Self-bonding LSR can also be used as an adhesive to bond a fully cured silicone rubber slab onto a given substrate. A 0.2mm tie layer of self-bonding LSR is molded between the silicone rubber slab and the substrate. The substrates arc stainless steel and GE Lexan polycarbonate. Vulcanization occurs in the slab mold at 177'C for 0.5 minutes. Adhesion properties of Formulation 1 are evaluated and the results are summarized in Table 15. The silicone rubber slab used in the test is made from Wacker 4105/40 (HCR). Table 15. Peel Strength after Post-Cure Treatment Peel strength (ppi) Stainless steel Lexan Formulation I 10.7 47,7 Formulation 1 as a tie layer shows good peel strength on both substrates. EXAMPLE 9 Thiee formulations are prepared for a performance study. Specifically, two vinyl-containing silsesquioxanes arc added to two commercial HCR formulations. The vinyl-conlaining silsesquioxanes are commercially available from Oclcst. Technical data of the vinyl-containing silsesquioxanes is illustrated in Table 16. The silicon HCRs are Wacker product R4000/50 for molding applications, and R4105/40 for extrusion applications. Formulation data is illustrated in Table 17. The low viscosity vinyl-containing silsesquioxanes are incorporated into the HCRs during the two part mixing step, using a roll mill. The additive loading level was between 0.5 to 2% by weight of HCR (phr, part per hundred part of rubber). Table 16, Properties of Silscsquioxane in-situ adhesion promoter Alkoxy group Density (g/cm"^) Viscosity (oSt) VEE-005 Eiboxy 1.02 4-7 VPE-005 Ethoxy 1.02 3-7 Table 17. Example Formulations Matrix Additive % of additive (phr) Fonnulation 6 Wackcr R4000/50 VEE-005 0.75 Fonnulation 7 WackerR4105/40 VEE-005 0.75 Formulation 8 WackerR4105/40 VPE-005 1.5 The mechanical properties of the three formulations are evaluated. The test slabs are compression molded at 177'^C for 5 minutes and posi-cured at 177°C for 4 hours. Tensile properties, such as tensile strength and elongation-at-break, are evaluated on an Insti'on using ASTM D-412. Tear tests are performed on an Instron according to ASTM D-624 and hardness measurements are canied out on a Shore A duroraeter, following the procedui"e of ASTM D-2240. Compression set measurements are carried out according to ASTM D-395. The resuhs are summarized in Table 18. Table 18. Properties of Silicone Foraiulations Tensile strength (psi) Elongation 200% modulus (psi) Tear strength (PPO Durometer (shore A) Formulation 6 1276 702 375 222 55 Formulation 7 1288 675 280 144 48 Formulation 8 1301 698 292 172 51 EXAMPLE 10 The adhesion properties of Formulations 6 and 7 on thermal plastic substrates ai« evaluated. The thennal plastic substiates include the following: a polycarbonate substrate (GE Lexan), a polyetheretherketone (PEEK) substrate, a polyester substrate, and a polyetherimide substrate (Ultem). Self-bonding HCR films having a thickness of about 0.5mm to about 1.5mm are compression molded onto the substrates and the molding conditions are identical to physical test slabs described in Example 9. A mylar film is also molded onto the back of the silicone rubber in the same step to prevent elongation during the peel rest. The 180'C peel test as dcsciibcd above is performed and results are summarized in Tables 19 and 20. Table 19 illusu*aies the peel strength prior to Ireatment, and Table 20 includes peel strength after post cure at 177'C for 4 hours. Comparison data for base nibber Waclcer R400/50 is also included. Table 19- Peel Strength Prior to Treatment Peel strength (ppi) Lexan PREK Polyester Ultem Formulation 6 0.6 2.4 0.8 / Formulation 7 4.4 2.6 1,8 3.3 Formulation 8 / / 2.2 / R4000y50 0.3 0.3 0.1 1.2 Table 20. Peel Strength after Post-Cure Treatment Peel strength (ppi) Lexan PEEK Polyester Ultem Formulation 6 78.8 3.7 76.4 / FoiTnulation 7 64.3 2.9 71.2 n.5 Formulation 8 / / C.F, / R4000y50 0.4 0.6 1.2 0.9 Before and after post-cure Ireatment, Fomiulations 6-8 bond with gi-eater peel strength than Wacker R4000/50 on all four stibstrates. Tn particular, cohesive failui-e is observed in Formulations 6, 7, and 8 after post-cure on polyester. Further, Formulations 6 and 7 exhibit cohesive failure on Lexan after post-cure. Hence, the adhesion force is greater than the strength of the silicone rubber. Typically, the peel strength is greater than 20 ppi when cohesive failure occurs. EXAMPLE 11 The adhesion propeities of Foimulations 6 and 7 on thennal set are evaluated. The thermal set substrates include the following: extnision grade HCR rubber (Wacker 4105/40) and phenoHc resin (Garoliie). The peel lesl results are sumniHrizcd in Tables 21 snd 22. Table 21 ilhistrates the peel su-ength prior to treatment, and Table 22 includes peel strength after post cure at 177°C for 4 hours Tabic 21. Peel Sti-cugth Prior to Treatment Peel strength (ppi) HCR rubber Phenolic resin FoiTnulation 6 C.F. C.F. Formulation 7 C.F. C.F. Table 22. Peel Strength after Post-Cure Treatment Peel strength (ppi) HCR rubber Phenolic resin Formulation 6 C.F. C.F. Formulation 7 C.F. C.F. On IICR rubber and phenolic resin, both Fomiulation 6 and 7 exhibit excellent peel sti'ength with cohesive failure prior to post-cure treatment and after post-ctire treatment. Cohesive failtire occurs when the adhesion force is greater than the strength of the silicone rubber. Typically, the peel sti'ength is greater than 20 ppi when cohesive faiUire occurs. EXAMPLES The adhesion properties of Formulation 6 on glass are evaluated. The glass substrate is borosilicate. The peel test results are summarized in Tables 23 and 24. Table 23 illusU-ates the peel strength prior to treatment, and Table 24 includes peel strength after post cure at 177^C for 4 liours. Table 23, Peel Strength Prior to Treatment Peel strength (ppi) Borosilicate glass Formulation 6 C.F. Table 24. Peel Strength after Post-Cure Treatment Peel strength (ppi) Borosilicate glass Formulation 6 C.F. On borosilicate glass, both Formulation 6 exhibits excellent peel strength with cohesive failure prior lo posi-ciu'e ireatmenl and after posl-ciue treatment. Cohesive failure occurs when the adliesion force is greater than the sti'ength of the silicone rubber, Typically, the peel strength is greater than 20 ppi when cohesive failure occurs, FXAMPLE 13 The adhesion properties of Formulations 6 and 7 on metal are evaluated. The metal substrates include the following: steel, stainless steel, and aluminum. Self-bonding HCR films having a thickness of 1.0mm to about 1.5mm are compression molded onto the substrates and the molding conditions are identical to physical test slabs described in Example 9. The peel test results are summarized in Tables 25 and 26, Table 25 illustrates the peel sti-ength prior to treatment, and Table 26 inchides peel strength after post cure at 1ITC for 4 hours. Comparison data for Wacker R4000/50 on selected substrates is also included. Table 25. Peel Sti-ength Prior to Treatment Peel strength (ppi) Steel Stainless steel aluminum R4000/50 0.6 0.5 0.5 Formulation 6 52.9 49.7 59.6 Fomuilation 7 61.2 53.8 51.3 Table 26. Peel Strength a(\er Post-Cure Treatment Peel strength (ppi) Steel Stainless steel aluminiun R4000/50 1,2 0.5 0.9 Formulation 6 63.8 58,6 67.8 Formulation 7 69.2 62.2 71.4 On metal substrates, both Formulation 6 and 7 exhibit excellent peel strength with greater peel strength compared lo Wacker R4000/50 prior to post-cure treatment and afler post-cure treatment, Cohesive failure occurs before and after post-cure treatment for Formulations 6 and 7 on steel and aluminian. Cohesive failure occurs when the adhesion force is greater than the strength of the silicone rubber. Typically, the peel strength is greater than 20 ppi when cohesive failure occtu-s. EXAMPLE 14 The adhesion properties of Formulations 6 and 7 on sodium naphthalene etched PTFE are evaluated. Self-bonding HCR films having a thickness of about 1.8mm are compression molded onto the PTFE substrates and the molding conditions are identical to physical test slabs described in Example 9, The peel test results are summarized in Tables 27 and 28. Table 27 illustrates the peel strength prior to treatment, and Table 28 includes peel strength after post cure at 177°C for 4 hotu-s. Comparison data for base mbber Wacker 3003/50 substrates is also included in the same table. Table 27. Peel Strength Prior to Treatment Peel strength (ppi) Na Naphth etched PTFE R4105/40 6.7 Formulation 6 25.6 Fomiulation 7 27,4 Table 28, Peel Strength after Post-Cure Treatment Peel strength (PPO Na Naphth etched PTFE R4105/40 2,7 Formulation 6 46,4 Fonnulalion 7 49.1 On sodium naphthalene etched PTFE, both Fomuilations 6 and 7 exhibit excellent peel strength with greater peel strength and cohesive failure compared to Wacker 4105/40 prior to post-cure treatment and after post-cure treatment. Cohesive failure occurs when the adhesion force is greater than the strength of the silicone rubber. Typically, the peel strength is gi-eater than 20 ppi when cohesive failure occurs, EXAMPLE 15 This example illustrates the use of self-bonding HCR as a laminate onto a fiberglass mat. The adhesion property of Formulation 7 on the fiberglass mat is evaluated. A laminate with LOmm thickness is molded onto the fiberglass mat using a slab mold. Vulcanization occurs in the slab mold at \1TC for 0,5 minutes, A 20.6 ppi peel strength is measured on the post cured specimens (4hr at 177T). EXAMPLE 16 Sell^honding HCR can be used as a tie layer to bond ditterent substrate materials together. Typical examples include PTFE/SB HCR/slainless steel and PTFE/SB HCR/aluminum. Tlie self-bonding liCR (SB HCR) is Fonnulatiou 7. Typical thickness of the tic layer is about 0.2mm. The laminate is formed by compression molding at 177°C for 5 minutes. The peel strengths between the PTFE and metals arc summarized in Tables 29 and 30. Table 29 is the peel suength prior to treatment. Table 30 is the peel strength after post cure at 177°C for 4 hours. Table 29. Peel Strength Prior to Treatment Peel .strength (ppi) PTFE/SB HCR/stainless steel PTFE/SB HCR/aluminum Formulation 7 CF CF Table 30. Peel Strength after Post-Cure Treatment Peel strength (ppi) PTFE/SB HCR/stainless steel PTFE/SB HCR/aluminum Fomuilatlon 7 CF CF Cohesive failure is observed. Hence, the adhesion force is greater than the strength of the silicone rubber. The peel strength is typically greater than 20ppi when cohesive failiu'e occurs. EXAMPLE 17 Six multi-layer tubes are used for a performance study. SpeciGcally, various silicone formulations are tested as covers over a sodium-naphthalene etched heat-shrinkable PTFE liner (2:1 H/S ratio; obtained from Teleflex). The silicone rubber covers are obtained from Wacker (product 3003/50). GE (product LIMS 8040) and Shin Etsu (product 2090-40). Formulation I (Wacker 3003/50 + Gelest VEE-005) and Formulation 5 (Wacker 3003/50 + Gelest VPE-005) described above are also used as covers. Further, the first silicone tube is a tube made from Wacker product 3003/50 without a liner. Life of the silicone mbber tubing is tested on either a standard pump head or Easy-Load 11 head at 600 rpm and zero backpressure. FIG. 3 illustrates the affects of the three different liners on Lhe life of silicone rubber tubing. Both the formtilations containing the silsesquioxancs oulpcrfomi lhe commercially available GE self-bonding LSR as well as the conventional LSRs, The multi-layer tube using Gelest VPE-005 has a life of greater [hiin about 275 hours. The multi-layer lube using Gelest VEE-005 has a life of gi-CHler than about 350 hours and outperfoi-ms the commercially available Shin-Etsu self-bonding LSR. EXAMPLE 18 This example illustrates tlie prepaiation of self-bonding silicone foam, 300g of Momentive Sanitech 50 base is inixed witli 3g of Momentive CA6. 3g of Azo Nobel Expancel and 2.25g of VEH-005 by a two-roll mill. The mix is molded into 2.0mm slabs at SSCF for 2minutes. The mix is also molded onto a stainless steel substrate, a polyester substrate, and an aluminum substrate under the same conditions. The slabs are post cured at 350°F for 2hr and the peel test results are summarized in Table 31. Table 31. Peel strength for self-bonding silicone foam. Substrate Peel Strength (ppi) Aluminum 2g.4 Polyester 25.9 Stainless Steel 32.1 The density of the silicone foam is 0.52g/cm' and the thermal conductivity of the silicone foam is0.16W/mK, On all three substrates, the scH-bonding silicone loam has excellent peel strength. EXAMPLE 19 Five formulations are prepared for a perfonnance study. Specifically, three in-situ adhesion promoters are added to a commercial LSR formulation. The adhesion promoters are dimethyl maleate (DMM), diethyl maleate (DEM) and dimethyl flimarate (DMF). which are all commercially available from Sigma Aldrich. The silicon LSR base rubber is Wacker Elastosil LR3003/50. Formulation data i; illu.strated in Table 31. The in-situ adhesion promoters are incorporated easily into the LSR during the two part mixing step, using a dotigh mixer; or a static mixer in the commercial LIMS mixing system. The additive loading level is between 0.3 to 1% by weight of LSR (phr, part per hiuidred part of rubber). Organosilsesquioxanes (Dynasylan 6498 and Dynasylan 6598, available from Degussa) are also used in two of the examples, to facilitate the dispersion of the adhesion promoter into the LSR matrix. Table 31. Example Formulations Additive (phi;) Carrier (phr) Fomuilation 9 DMM (0.5) Foraiulation 10 DEM (0.7) Formulation 11 DMF(0.7) Fonnulation 12 DMM (0.35) Dynasylan6498 (0.35) Fommlatioii 13 DEM (0.5) Dynasylan6598 (0.6) The mechanical properties of two formulations (Fomiulations 12 and 13) are evaluated. The tesL slabs are compression molded at 177'C for 5 minutes and post-cured at 177°C for 4 hours. Tensile properties, such as tensile strength and elongation-at-break, are evaluated on an Instron using ASTM D-412. Tear tests are performed on an Inslron according lo ASTM D-624 and hardness measurements are carried out on a Shore A durometer, following the procedure of ASTM D-2240. The results arc summarized in Table 32, Table 32. Properties of Silicone Formulations Tensile strength (psi) Elongation (%) 200% modulus (psi) Tear strength (PPO Durometer (shore A) FoiTTiulalion 12 1384 756 311 229 42 Fomiulation 13 1259 628 307 223 42 EXAMPLE 20 The adhesion properties of Fomiulations 9 to 13 on thermal plastic substrates are evaluated. The thermal plastic substrates include the following: a polycarbonate substrate (GE Lexan), a polyetheretherketone (PEEK) substrate, a polyester substrate, polyetherimide (Ultem), and polyphenylsultbne (Radel). Self-bonding films having a thickness of about 0.5mm to abotit 1.5mm are compression molded onto the substrates and the molding conditions are identical to physical test slabs described in Example 18, A mylar film is also molded onto the back of the silicone rubber in the same step to prevent elongation during the peel test. The peel test uses an Instron 4465 testing machine. Both the silicone layer and the substrate are clamped into the Insh-on grip. The grip then transverses in the vertical direction at the rale of two inches/minute, which puUs the silicone 180° away from the substrate. The 180° peel test results arc summarized in Tables 33 and 34. Table 33 illustrates the peel strength prior to treatment, and Table 34 includes the peel strength after post cure at 1 ITC for 4 hours. Comparison data for base rubber Wacker 3003/50 on selected substrates is also included. Table 33. Peel Sti'ength Prior to Treatment Peel strength (ppi) Polycai'bonate (Lexan) PEEK Polyester Ultem Radel Formulation 9 22.4 N/A N/A N/A N/A Fonnulaiion 10 17.8 N/A N/A N/A N/A Formulation 11 20.9 WA N/A N/A N/A Formulation 12 M.O 5.0 9.3 N/A N/A Formulation 13 24.1 23.7 15.4 21.9 26.0 3003/50 0.2 0.4 0.4 0.3 0.4 Table 34. Peel Strength after Post-Cure Treatment Peel strength (ppi) Polycarbonate (Lexan) PEEK Polyester Ultem Radel Foitnulation 9 53.4 N/A N/A N/A N/A FoiTnulation 10 49.7 N/A N/A N/A N/A Fminulation 11 38.7 N/A N/A N/A N/A Formulation 12 64.9 28.9 66.4 N/A N/A Formulation 13 57.3 55.6 57,0 63.S 51.9 3003/50 1.4 1.2 l.l 0.9 1.4 Before and after post-cure treatment, Formulations 9-13 bond with greater peel strength than Wacker 3003/50 on polycarbonate. In particular, cohesive failure is observed in Formulations 12 and 13 on the suiface of polycarbonate, PERK, Ultem. Radel, and polyester after post-cure treatment. Hence, the adhesion force is greater than the strength of the silicone rubber. Typically, the peel -slrengLh is greater than 20 ppi when cohesive failure occurs. The adliesion properties of Formulations 12 and 13 on glass-filled nylon substrates are evaluated. Formulation 12 and 13 are injection molded onto freshly made substrate using a two-shot press. The thickness of the silicone nibber films is 4.0mm and the geometry of the adliesion test specimen is defined by ASTM429. The adhesion test is carried by a 90° Peel according to ASTM429 and the results are summarized in Table 35. The post cure condition is 177*^0 for 4 hours. Table 35. Peel strength of two-shot molded silicone/Nylon parts. Peel stiengtli (ppi) Prior to Treatment After Post-Cm'e Treatment Formulation 12 37,4 41.8 Formulation 13 21.6 49.2 EXAMPLn21 The adhesion properties of Formulations 12 and 13 on metal are evaluated. Tlie metal substrates include the following: copper, stainless steel, and aluminum. Self-bonding LSR fUms having a thickness of about 1.5mm to about 1.8mm are compression molded onto the substrates and the molding conditions are identical to physical test slabs described in Example 18. Tlie peel test results are summarized in Tables 36 and 37. Table 36 illustrates the peel strength prior to treatment and Table 37 includes peel strength after post cure at 177°C for 4 hours. Comparison data for Waeker 3003/50 on selected substrates is also included. Table 36. Peel Su'engih Prior LO TreaLmeiil Peel strength (ppi) Stainless steel Aluminum Copper 3003/50 0.2 0.4 0.1 Formulation 12 20.9 18.3 21.4 Fonmilalion 13 23.4 22.5 24.7 Table 37. Peel Strength after Post-Cure Treatment Peel strength (ppi) Stainless steel Aluminum Copper 3003/50 0.4 0.7 0.6 Formulation 12 23.2 71.6 54.8 Formulation 13 58.4 60.1 49.2 On metal substrates, both FoiTnulations 12 and 13 exhibit excellent peel strength with greater peel strength compared to conventional Wacker 3003/50 prior to post-cure treatment and after post-cure Irealment. Cohesive failure is observed. Hence, the adhesion force is gi'cater than the strength of the silicone nibber. The peel strength is typically greater than 20.0 ppi when cohesive failure occurs. EXAMPLE 22 The adliesion properties of Formulations 12 and 13 on sodium naphthalene etched PTFF- arc evaluated. Self-bonding LSR films having a thickness of about 1.8mm is compression molded onto the substrates and the molding conditions are identical to physical test slabs described in Example 18. The peel test restilts are stimraaiized in Tables 38 and 39. Table 38 illustrates the peel strength prior to treatment and Table 39 includes peel strength at\er post cure at 177°C for 4 houi-s, Comparison data for base rubber Wacker 3003/50 substrates is also included in the same table. Table 38. Peel Sti-ength Prior to Treatment Peel strength (ppi) Na Naphth etched PTFE I'onnulation 12 27,8 Fonnulation 13 29.7 3003/50 1.7 Table 39. Peel Su-cngth after Post-Cure Treatment Peel strength (ppi) NaNaphth etched PTFE Formulation 12 33.9 Formulation 13 42.4 3003/50 3.S On sodium naphthalene etched PTFE, both Formulations 12 and 13 exhibit excellent peel strength with greater peel strength and cohesive failure compared to conventional Wackcr 3003/50 prior to post-cure treatment and after post-cure treatment. Cohesive failure occurs when the adhesion force is greater than the strength of the PTFE film, Typically, the peel strength is greater than 20,0 ppi when cohesive failure occurs. EXAMPLE 23 Tliree formulations are prepared for a performance study. Specifically, dietliyl maleate is added to one commercial platinum cured HCR fomiulation and two peroxide cured HCR formulation.s. Diethyl maleate is commercially available from Sigma Aldrich. The platinum cured silicon IICR is Momentive product, Santitech 65. The peroxide cured silicone HCRs are Bayer HV3 622 and Momentive SE6350. FoiTnulation data is illustrated in Table 40. The low viscosity diethyl maleate is incorporated into the OCRs during the two pan mixing .step, using a two-roll mill. Tlie additive loading level is between 0.5 to 1% hy weight of HCR (phr. part per hundred part of nibber). Table 40. Example Formulations Base Rubber Catalyst % of additive (phr) Fonuulation 14 Momentive Santitech 65 Platinum (Momentive CA6) 0.70 Formulation 15 Bayer HV3 622 Dichlorobenzonyl peroxide 0.70 Formulation 16 Momentive SH 6350 Dichlorobenzonyl peroxide 0.83 The mechanical properties of the three formulations are evaluated and the restilts are summarized in Table 41. The test slabs are compression molded at 210*C for 2 minutes and post-cured at 177°C for 4 hours. Tensile properties, such as tensile strength and elongation-at-break, are evaluated on an Instron using ASTM D-412. Tear tests are peiformed on an Instron according to ASTM D-624 and hardness measurements are carried out on a Shore A diiroraeler, following the procediu-e of ASTM D-2240. Table 41. Properties of Silicone Fonnnlations Tensile strength (psi) Elongation 200% modulus (psi) Tear strength (PPO Duro meter (shore A) Formulation 14 1355 650 544 287 65 Formulation 15 1533 731 235 220 53 FoiTnulation 16 1576 690 294 296 54 EXAMPLE 24 The adhesion properties of Formulations 14 on thermal plastic substrates ai'e evaluated, The thermal plastic substrates include the following: a polycai'bonate subsu-ate (GE Lexan), a polyetheretherketone (PEEK) stibstrate, a polyetherimide (Ultem) substrate, a polyphenylsulfone (Radel) subshate, and a polyester substrate. Self-bonding IICR films having a thickness of about 0.5mm to about 1.5nim are compression molded onto the suhsU'ates and the molding conditions are identical lo physical test slabs described in Example 22. A mylar film is also molded onto the back of the silicone rubber in the same step to prevent elongation during the peel test. The 180° peel lest as described above is performed and results are summarized in Tables 42 and 43. Table 42 illustrates the pee! Blrenglh prior lo ti-eatmenl. and Table 43 includes peel strength al\er post cure at 177*'C for 4 hours. Comparison data for conventional HCR Wacker R4000/50 is also included. Table 42. Peel Strength Prior to Treatment Peel strength (ppi) Lexan PEEK Polyester Ultem Radcl Formulation 14 1.2 1.6 2.6 L8 3.2 R4000/50 0.3 0.3 O.I 0.2 0.4 Table 43. Peel Strength after Post-Cure Treatment Peel strength (ppi) Lexan PEEK Polyester Ultem Radel Fonnulation 14 29.2 64.2 83.8 40.4 76.1 R40O0/5O 0.4 0.6 1.2 0.8 0.9 Formulations 14 bond with gieater peel strength than Wacker R400O/5O on all five substrates after post-cure treatment. In pailicular, cohesive failure is observed for all five substrates. Hence, the adhesion roi"ce is greater than the strength of the silicone rubber. Typically, the peel strength is gi'eater than 20.0 ppi when cohesive failure occurs. EXAMPLE 25 The adhesion properties of Formulations 14 and 15 on metal aie evaluated. The metal substrates include stainless steel and aluminum. Self-bonding HCR films having a thickness of 1.0mm lo about 1.8mm are compression molded onto the substrates and the molding conditions are identical to physical test slab.s described in Example 22. The peel test results are summarized in Tables 44 and 45. Table 44 illustrates the peel strengthpriortotreatment and Table 45 includes peel strength after post cure at 177T for 4 hours. Compai'ison data for Wacker R4000/50 on selected substrates is also included. Table 44. Peel Strength Prior to Treatment Peel strength (ppi) Stainless steel Aluminum R4000/50 0.5 0.5 Formulation 14 45,0 36,8 Foraiulation 15 6,9 15,6 Table 45. Peel Strength after Post-Cure Treatment Peel strength (ppi) Stainle.ss steel Aluminum R4000/50 0.5 0.9 Formulation 14 74.8 54.3 Foi-mulation 15 15.4 30.6 On metal substraLes, both Formulations 14 and 15 exhibit excellent peel strength with greater peel strength compared to Wucker R4000/50 prior Lo posl-ciire treatment and after post-cure treatment, Cohesive failm-e occiii-s before and after post-cure treatment for Fonmilations 14 and 15 on steel and aluminum. Cohesive falhtre occurs when the adhesion force is greater than the strength of the silicone rubber. Typically, the peel strength is greater than 20.0 ppi when cohesive failure occurs. KKAMPLE 26 The adhesion properties of Formulations 14 to 16 on sodium naphthalene etched PTFE, sodiimi ammonium etched PTFE, and colloidal silica (Ludox®) treated PTFE are evaluated. Self-bonding HCR films having a thickness of about 1.8mm are compression molded onto the etched PTFF substrates and the molding conditions are identical to physical test slabs described in Example 22. The peel test restilts are summarized in Tables 46 and 47. Table 46 ilhistj-ates the peel strength prior to treatment, and Table 47 includes peel strength after post cure at 177°C for 4 hours. Comparison data for conventional HCR rubber Wacker 3003/50 substrates is also included in the same table. Table 46. Peel Strength Prior to Treatment Peel strength (ppi) NaNaphth etched PTFE Na Nils etched PTFE LtidoxtK-treated PTFE R4105/40 6.7 1.7 2,1 Formulation 14 20.5 29.2 10.0 Formulation 15 23.5 28.9 9.3 Fonnulation 16 22.9 27.6 N/A Table 47. Peel Strength after Post-Cure Treatment Peel strength (ppi) NaNaphth etched PTFE Na NHj etched PTFE Ludox® treated PTFE R4105/40 2.7 2.3 2.3 Formulation 14 43.8 27.2 N/A Formulation 15 15.6 18.7 N/A Formulation 16 29.7 28.2 N/A On soditim naphthalene etched PTFE, both Formulations 14 and 15 exhibit excellent peel strength with greater peel strength and cohesive failure compared to Wacker 4105/40 prior to post-cure treatment and after post-cure treatment. Both Formulations 14 and 15 give good peel strength on sodium ammonium etched PTFE and reasonable peel strength on Ludox® treated PTFE. Cohesive failure occurs when the adhesion force is greater than the strength of the PTFE film. Typically, the peel strength is greater than 20,0 ppi when cohesive failure occurs. The above-disclosed subject matter is to be considered illustrative, and not restrictive, and the appended claims are intended to cover all such moditications, enhancetnenls, and other embodiments, which fall within the true scope of the present invention. Thus, to the maximum extent allowed by law^ the scope of the present invention is to be detemiined by the broadest permissible interpretation of the following claims and their equivalents, and shall not be restricted or limited by the foregoing detailed desciiption. 1. A method of mailing a silicone composition comprising: mixing a silicone formulation in a mixing device; and adding an in situ adhesion promoter to the mixing device. 2. The method of claim 1, further comprising the step of vulcanizing said silicone composition. 3. The method of any one of claims 1-2, wherein the in situ adhesion promoter is a silsesquioxane, an ester of unsaturated aliphatic carboxylic acid, or mixture thereof 4. The method of claim 3, wherein the ester of unsaturated aliphatic cai'boxylic acid is a C\.g alkyl ester of maleic acid, fumaric acid, or any combination thereof. 5. The method of claim 3, wherein the silsesquioxane contains vinyl groups. 6. The method of claim 5, wherein the vinyl-containing silsesquioxane contains RSi03/2 units wherein R is an alkyl, an alkoxy, or a phenyl group, or any combination thereof. 7. The method of claim 6, wherein the silsesquioxane has a vinyl content of at least about 30.0% by weight. 8. The method of claim 3, wherein adding the in situ adhesion promoter includes adding a silsesquioxane having a viscosity of about 1.0 centistokes to about 8.0 centistokes. 9. The method of any one of claims 1-8, wherein the in situ adhesion promoter is added in an amount of about 0.1 wt% to about 5.0 wt% of the total weight of the silicone formulation. 10. The method of any one of claims 1-9, further comprising heating the silicone composition to a temperature of about US^C to about 200°C. 11. The method of claim 10, wherein heating includes heating for a time of about 5 minutes to about 10 hours. 12. An article comprising: a silicone formulation comprising a polyalkylsiloxane; an in sitii adhesion promoter comprising a Ci-s allcyl ester of maleic acid, flimartc acid, or any combination thereof; and optionally, an organosilsesquioxane. 13. An article comprising; a first layer comprising a polymeric material, a glass, or a metal; and a second layer adjacent the first layer, the second layer comprising: a silicone formulation; and an in situ adhesion promoter comprising a Ci.g alkyl ester of maleic acid, ftimaric acid, or any combination thereof and optionally, an organosilsesquioxane. 14. An article comprising: a silicone formulation comprising a polyalkylsiloxane; and a vinyl-containing silsesquioxane containing RSi03/2 units wherein R is an alkyl group, an alkoxy group, a phenyl group, or any combination thereof. 15. An article comprising: a first layer comprising a polymeric material, a glass, or a metal; and a second layer adjacent the first layer, the second layer comprising: a silicone formulation; and a vinyl-containing silsesquioxane containing RSi03/2 units wherein R is an alkyl group, an alkoxy group, a phenyl group, or any combination thereof |
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| Patent Number | 272545 | ||||||||||||
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| Indian Patent Application Number | 5211/CHENP/2009 | ||||||||||||
| PG Journal Number | 15/2016 | ||||||||||||
| Publication Date | 08-Apr-2016 | ||||||||||||
| Grant Date | 07-Apr-2016 | ||||||||||||
| Date of Filing | 04-Sep-2009 | ||||||||||||
| Name of Patentee | SAINT-GOBAIN PERFORMANCE PLASTICS CORPORATION | ||||||||||||
| Applicant Address | 1199 CHILLICOTHE ROAD, AURORA, OHIO 44202 | ||||||||||||
Inventors:
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| PCT International Classification Number | C08L83/04 | ||||||||||||
| PCT International Application Number | PCT/US08/56305 | ||||||||||||
| PCT International Filing date | 2008-03-07 | ||||||||||||
PCT Conventions:
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