Patent Description:
Aryl-functionalized polysiloxanes, such as phenyl-functionalized polysiloxanes and substituted phenyl-functionalized polysiloxanes, tend to be thermally unstable, having a propensity to undergo thermally induced aryl scission at elevated temperatures. The propensity for thermally induced aryl scission is greater when the aryl-functionalized polysiloxane contains silanol functionality. Such thermally induced aryl scission is undesirable and is a challenge for many applications of aryl-functionalized polysiloxanes.

Aryl-functionalized polysiloxanes are useful as coatings, encapsulants and adhesives in applications that can experience temperatures of <NUM> degrees Celsius (°C) or more, <NUM> or more, <NUM> or more and even <NUM> or more. At these temperatures, aryl scission can undesirably produce aromatic byproducts such as benzene and/or cause the aryl-functionalized polysiloxane to yellow and/or become hard and brittle in an air environment.

Often, aryl-functionalized polysiloxanes used as elastomers, coatings, encapsulants and adhesives are applied as an aryl-functionalized polysiloxane and cured to form a crosslinked aryl-functionalized polysiloxane. Aryl scission is a concern before, during and after curing of such aryl-functionalized polysiloxanes. Curing can occur via crosslinking by condensation reactions of aryl-functionalized polysiloxanes that are silanol functionalized. Curing can also occur via crosslinking by hydrosilation reactions through an unsaturated carbon-carbon bond whether the aryl-functionalized polysiloxane contains a silanol functionality or not. The presence of silanol tends to increases the propensity for thermally induced aryl scission.

It would advance the art of aryl-functionalized polysiloxane technology to find a way to inhibit thermally induced aryl scission of aryl-functionalized polysiloxane. It would be especially desirable to identify a way to inhibit thermally induced aryl scission for aryl-functionalized polysiloxanes that are silanol functionalized. It would be even more desirable if, at the same time, there was a way to inhibit aryl scission of aryl-functionalized polysiloxane, with or without silanol functionality, at temperatures of <NUM> or more, <NUM> or more, especially <NUM> or more and even <NUM> or more.

<CIT> discloses the addition of various quaternary ammonium salts with counter-ions, including acetate and benzoate, to aryl-functional polysiloxanes having OH groups, to form a tack-free coating after heating at <NUM>.

As part of the discovery of the present invention, it was surprisingly and unexpectedly discovered that an additional problem is that thermally induced aryl scission of aryl-functionalized polysiloxanes occurs more readily when an aryl-functionalized polysiloxane is in the presence of inorganic particulates. That is, the extent of aryl scission that occurs in an aryl-functionalized polysiloxane increases when the aryl-functionalized polysiloxane is in the presence of inorganic particulates such as calcium carbonate, talc, silica and clay particles.

The present invention as defined in the claims provides a solution to the problem of inhibiting thermally induced aryl scission of aryl-functionalized polysiloxanes, such as phenyl-functionalized polysiloxanes and substituted phenyl-functionalized polysiloxanes. Moreover, the present invention provides a solution to the problem of inhibiting thermally induced aryl scission of aryl-functionalized polysiloxanes that are silanol functionalized. At the same time, the present invention provides a solution to the problem of aryl scission of such aryl-functionalized polysiloxanes at temperatures of <NUM> or more, <NUM> or more, especially <NUM> or more and even <NUM> or more. Even more, in addition to solving the aforementioned problems, the present invention solves the problem of inhibiting aryl scission of aryl-functionalized polysiloxanes in the presence of inorganic particulates such as calcium carbonate, talc, silica and clay particles.

The present invention is a result of surprisingly and unexpectedly discovering that certain, but not all, quaternary ammonium compounds inhibit thermally induced aryl scission of aryl-functionalized polysiloxane when mixed with the aryl-functionalized polysiloxane, even when the polysiloxane is silanol functionalized, and even when it is in the presence of inorganic particulates, including metal catalysts. The quaternary ammonium compounds, in the broadest scope, can have any cationic nitrogen component. However, the anion of the quaternary ammonium compound must be selected from a group consisting of halides (such as chloride and bromide), salicylate (<NUM>-hydroxybenzoate), octanoate (CH<NUM>(CH<NUM>)<NUM>COO-), dihydrogen citrate (C<NUM>H<NUM>O<NUM>-,
<CHM>
), maleate (-O<NUM>CCHCHCO<NUM>-), hydrogenglutaric acid anion (HO<NUM>C(CH<NUM>)<NUM>)CO<NUM>-), and bistartaric acid anion (HOOC(CHOH)<NUM>COO-). When such a quaternary ammonium compound is mixed with aryl-functionalized polysiloxane, aryl scission is dramatically reduced, even at temperatures of <NUM> or higher, <NUM> or higher, <NUM> or higher and even at temperatures of <NUM> or higher, even when the aryl-functionalized polysiloxane has silanol functionality and even when in the presence of inorganic particulates.

In a first aspect, the present invention is a composition as defined in claim <NUM>, embodiments of which are defined in the dependent claims. In a second aspect, the present invention is a process comprising heating the composition of the first aspect to a temperature of <NUM> or higher, <NUM> or higher, <NUM> or higher, or even <NUM> or higher. Optionally, the process comprises applying the composition to a substrate and then heating to a temperature of <NUM> degrees Celsius or higher.

The present invention is useful for inhibiting thermally induced aryl scission in aryl-functionalized silicone-base polymers whether cured, non-cured or as they are curing, thereby enhancing the thermal stability of aryl-functionalized coatings, encapsulants and adhesives.

Test methods refer to the most recent test method as of the priority date of this document if a date is not indicated with the test method number. References to test methods contain both a reference to the testing society and the test method number. The following test method abbreviations and identifiers apply herein: ASTM refers to American Society for Testing and Materials; EN refers to European Norm; DIN refers to Deutsches Institut für Normung; and ISO refers to International Organization for Standardization.

"Multiple" means two or more. "And/or" means "and, or as an alternative". All ranges include endpoints unless otherwise indicated. Molecular weight refers to weight-average molecular weight unless otherwise stated. Determine molecular weight by gel permeation chromatography using polystyrene standards.

The present invention is a composition as defined in the claims. The composition can be in any form as long as it contains the requisite components. For example, the composition can be a volume of liquid, a coating, an encapsulant, and elastomer, and/or a film. The composition can be a composition useful for curing by condensation and/or hydrosilation. Additionally, or alternatively, the composition can comprise a polysiloxane that has been cured by condensation and/or hydrosilation. The composition can at least partially and even entirely cover an article. For example, the composition can be an encapsulant around a light emitting diode or a film over another material. The composition is also useful as an adhesive between two components.

The composition comprises an aryl-functionalized polysiloxane wherein the aryl-functionalized polysiloxane is silanol functionalized, and contains <NUM> mole-percent or more, preferably <NUM> mole-percent or more, and more preferably <NUM> mole-percent or more T units based on total moles of siloxane units. An aryl-functionalized polysiloxanes contains an aryl functionality attached to a silicone atom. The aryl functionality can be, for example, phenyl or a substituted phenyl group. Substituted phenyl groups are phenyl groups where one or more than one of the hydrogens of the phenyl group is substituted with something other than hydrogen. The aryl-functionalized polysiloxane can comprise M, D, T, and Q siloxane units. "M" units correspond to units having the following structure: R<NUM>R<NUM>R<NUM>SiO<NUM>/<NUM>; "D" units correspond to units having the following structure: R<NUM>R<NUM>SiO<NUM>/<NUM>; "T" units correspond to units having the following structure: R<NUM>SiO<NUM>/<NUM>; and "Q" units correspond to units having the following structure: SiO<NUM>/<NUM>; where R<NUM>, R<NUM>, R<NUM>, R<NUM> and R<NUM> are independently in each occurrence selected from hydrogen, alkyl groups, aryl groups, hydroxyl, halogen or any other pendant group provided there is at least one R group that is an aryl group (that is, an aryl functionality). Preferably, the aryl-functionalized polysiloxane comprises <NUM> mole-percent or more, preferably <NUM> mole-percent or more, and more preferably <NUM> mole-percent or more aryl substituted siloxane units relative to total moles of siloxane units. Determine mole-percent aryl substituted siloxane units by Silicon-<NUM> nuclear magnetic resonance spectroscopy (<NUM>Si NMR). The aryl-functionalized polysiloxane contains <NUM> mole-percent or more, preferably <NUM> mole-percent or more, and more preferably <NUM> mole-percent or more T units based on total moles of siloxane units. Determine the mole-percent T units by <NUM>Si NMR. Preferably, the aryl-functionalized polysiloxane contains <NUM> mole-percent or more aryl-functionalized T units (T units where the R group is an aryl). Determine mole-percent aryl-functionalized T units by <NUM>Si NMR.

The aryl-functionalized polysiloxane has silanol functionality. Aryl-functionalized polysiloxane containing silanol functionality contain M, D and/or T siloxane units as described above where one or more than one of the R groups of a siloxane unit is a hydroxyl (-OH). Aryl scission is generally more prevalent in aryl-functionalized polysiloxane containing silanol functionality. Yet, surprisingly, compositions of the present invention demonstrate dramatically reduced aryl scission in even aryl-functionalized polysiloxanes with silanol functionality. The aryl-functionalize polysiloxane of the present invention can comprise one weight-percent (wt%) or more, two wt% or more, three wt% or more, four wt% or more, five wt% or more, six wt% or more, seven wt% or more, eight wt% or more, nine wt% or more and even <NUM> wt% or more while at the same time can comprise <NUM> wt% or less, nine wt% or less, eight wt% or less, seven wt% or less, six wt% or less, five wt% or less and even four wt% or less hydroxyl groups relative to aryl-functionalized polysiloxane. Determine wt% hydroxyl groups relative to aryl-functionalized polysiloxane as an average value by <NUM>Si NMR.

Prepare aryl-functionalized polysiloxanes by standard methods known in the art. For example, polysiloxanes for use in the present invention can be made using the general procedures taught in <CIT>, <CIT> and/or <CIT>.

The aryl-polysiloxane of the composition of the present invention can be cured (that is, crosslinked) or non-cured (non-crosslinked). Curing of aryl-polysiloxanes can occur by hydrosilation if the aryl-functionalized polysiloxane comprising silanol functionality. Curing of aryl-functionalized polysiloxanes can also, or alternatively, occur by hydrosilation regardless of whether the aryl-functionalized polysiloxane has silanol functionality provided it comprises unsaturated carbon-carbon bonds. These curing reactions are described further below.

The composition comprises a specific quaternary ammonium compound. It has been surprisingly and unexpectedly discovered that select quaternary ammonium compounds inhibit aryl scission of aryl-functionalized polysiloxanes. The quaternary ammonium compound has a quaternary ammonium cation component and an anion component. In the broadest scope of the invention, the cation can be any quaternary ammonium cation. Quaternary ammonium compounds with a N,N,N-trimethyl ethanolammonium cation (also known as "choline") are particularly effective at inhibiting aryl scission. The anion of the quaternary ammonium compound is selected from a group consisting of halides, salicylate (<NUM>-hydroxybenzoate), octanoate (CH<NUM>(CH<NUM>)<NUM>COO-), dihydrogen citrate, maleate, hydrogenglutaric acid anion (HO<NUM>C(CH<NUM>)<NUM>)CO<NUM>-), and bistartaric acid anion. The halide is desirably selected from chloride and bromide. The composition can comprise a single type of quaternary ammonium compound or multiple different types of the quaternary ammonium compounds.

The concentration of quaternary ammonium compounds in the composition is generally <NUM> wt% or more, preferably <NUM> wt% or more, more preferably <NUM> wt% or more, still more preferably <NUM> wt% or more, even more preferably <NUM> wt% or more and can be <NUM> wt% or more, <NUM> wt% or more, <NUM> wt% or more, <NUM> wt% or more, and can be <NUM> wt% or more and even <NUM> wt% or more while at the same time is generally <NUM> wt% or less, typically <NUM> wt% or less and can be <NUM> wt% or less, <NUM> wt% or less, <NUM> wt% or less, <NUM> wt% or less, <NUM> wt% or less, <NUM> wt% or less, <NUM> wt% or less, <NUM> wt% or less, <NUM> wt% or less and even <NUM> wt% or less where wt% is the weight percent of total quaternary ammonium compound relative to aryl-containing polysiloxane weight.

The composition can further comprise an inorganic particulates. Inorganic particulates are particulates of inorganic material. It was discovered that when inorganic particulates are present in a composition of aryl-functionalized polysiloxane the extent of aryl scission that occurs upon heating the composition is greater than when the inorganic particulates are absent. Hence, inorganic particulates tend to facilitate aryl scission of aryl-functionalized polysiloxane. Nonetheless, it has further been surprisingly and unexpectedly discovered that the specific quaternary ammonium compound of the present invention inhibits aryl scission of aryl-functionalized polysiloxane even in the presence of inorganic particulates. Any inorganic particulate is expected to facilitate aryl scission.

Inorganic particulates include any one or combination of more than one particulate of the following materials: minerals of sulfides, sulfosalts, oxides, hydroxides, halides, carbonates, nitrates, borates, sulfates, phosphates, silicates, mica, talc, calcium carbonate, magnesium carbonate, zinc carbonate, magnesium chloride, zinc stearate, zinc oxide, titanium dioxide, zirconium dioxide, wollastonite (calcium silicate), glass, aluminum hydroxide, aluminum silicate, antimony trioxide, barium ferrite, barytes (barium sulfate), calcium sulfate, silica, clay, Frankin fiber, iron silicate, litharge, lithopone, pyrophyllite, gypsum, perlite, phyllosilicates, vermiculite, barite, and inorganic phosphor. Inorganic particulates include one or more than one inorganic filler selected from a group consisting of calcium carbonate, talc, silica and clay (such kaolin clay).

Inorganic phosphor is commonly included inorganic particulate when the composition is used in producing light-emitting semiconductor components. Inorganic phosphor fillers include cerium (Ce)-doped yttrium aluminum garnet (YAG) phosphors, cerium-doped garnet phosphors containing at least one element selected from yttrium (Y), lutetium (Le), scandium (Sc), lanthanum (La), gadolinium (Gd) and samarium (Sm) and at least one element selected from aluminum (Al), gallium (Ga) and Indium (In). Inorganic phosphor can also be other garnets doped with rare earths such as Y<NUM>Ga<NUM>O<NUM>:Ce<NUM>+, Y(Al,Ga)<NUM>O<NUM>:Ce<NUM>+ and Y(Al,Ga)<NUM>O<NUM>:Tb<NUM>+, as well as alkaline earth metal sulfides doped with rare earths, such as SrS:Ce<NUM>+, Na, SrS:Ce<NUM>+, Cl, Srs:CeCl<NUM>, CaS:Ce<NUM>+ and SrSe:Ce<NUM>+. The thiogallates doped with rare earths, for example, CaGa<NUM>S<NUM>:Ce<NUM>+ and SrGa<NUM>S<NUM>:Ce<NUM>+, and aluminates doped with rare earths, such as, for example, YAlO<NUM>:Ce<NUM>+, YGaO<NUM>:Ce<NUM>+, Y(Al,Ga)O<NUM>Ce<NUM>+, and orthosilicates M<NUM>SiO<NUM>:Ce<NUM>+ (M:Sc, Y, Sc) doped with rare earths, such as, for example, Y<NUM>SiO<NUM>:Ce<NUM>, and all of the yttrium compounds, scandium compounds or lanthanum compounds.

Organometallic catalysts can also be included in the composition and are a form of inorganic particulate. Organometallic catalysts can facilitate reactions such as hydrosilation of the aryl-functionalized polysiloxane. Organometallic catalysts include organometallic compounds containing a metal selected from a group consisting of platinum, titanium, zirconium, tin, zinc, bismuth, cobalt, iron, vanadium and cadmium.

Inorganic particulates can be present in the composition at a concentration of zero wt% or more, <NUM> wt% or more, <NUM> wt% or more, <NUM> wt% or more, <NUM> wt% or more, <NUM> wt% or more, <NUM> wt% or more, <NUM> wt% or more, <NUM> wt% or more, <NUM> wt% or more, <NUM> wt% or more, and even <NUM> wt% or more, <NUM> wt% or more, <NUM> wt% or more, <NUM> wt% or more and even <NUM> wt% or more while at the same time are generally present at a concentration of <NUM> wt% or less, <NUM> wt% or less, <NUM> wt% or less, <NUM> wt% or less, <NUM> wt% or less, <NUM> wt% or less, <NUM> wt% or less, <NUM> wt% or less <NUM> wt% or less, or even <NUM> wt% or less relative to the weight of aryl-functionalized polysiloxane.

A desirable feature of the composition of the present invention is that it unexpectedly and surprisingly experiences less aryl scission than the same composition without the quaternary ammonium compound, or with a different quaternary ammonium compound. In particular, this unexpected and surprising result is true at temperatures of <NUM> and higher, <NUM> or higher, <NUM> or higher, and even at temperatures of <NUM> or higher. Hence, the present invention also includes a process comprising heating the composition of the present invention to a temperature of <NUM> or higher, <NUM> or higher, <NUM> or higher, and even <NUM>° or higher. The process can further include applying the composition of the present invention to a substrate (for example, coating or encapsulating or adhering a substrate with the composition) and heating to <NUM> or higher, <NUM> or higher, <NUM> or higher, and even <NUM> or higher before, during and/or after applying the composition to the substrate. Beneficially, the process results in less aryl scission of the aryl-functionalized polysiloxane than an identical process using a composition that does not contain the quaternary ammonium compound specified for the composition of the present invention. The reduction in aryl scission is often one or more, two or more and even three or more orders of magnitude relative to an identical formulation without the quaternary ammonium compound specified for the present invention.

The composition of the present invention can be used, for example, as an adhesive, a coating, an encapsulant, an elastomer or a gel. The process of the present invention can include applying the composition to a substrate. The process can further include inducing crosslinking of the aryl-functionalized polysiloxane before, during and/or after applying the composition to a substrate. For example, the process of the present invention can be one or more process selected from condensation and hydroxylation.

Crosslinking of aryl-functionalized polysiloxanes in compositions of the present invention can be accomplished by condensation reactions when the aryl-functionalized polysiloxane also includes silanol functionality. Generally, the concentration of silanol hydroxyl must exceed one wt% of the aryl-functionalized polysiloxane to achieve condensation or the hydroxyls will not be exposed on the surface of the polymer sufficiently to effectively participate in condensation. The composition can experience temperatures of <NUM> or higher, <NUM> or higher, <NUM> or higher, even <NUM> or higher before, during or after condensation so preventing aryl scission is important during condensation reactions of aryl-functionalized polysiloxanes.

Crosslinking of aryl-functionalized polysiloxanes in composition of the present invention can be accomplished by hydrosilation reactions with aryl-functionalized polysiloxanes without silanol functionality or with silanol functionality. Hydrosilation is an organometallic catalyzed reaction between hydrogen-silicon (hydrido, Si-H) groups and unsaturated carbon-carbon bonds. Hence, the composition of the present invention can comprise (or be free of, if not used in hydrosilation reactions) compounds having one or more than one unsaturated carbon-carbon bond. Unsaturated carbon-carbon bonds include carbon-carbon double bonds and carbon-carbon triple bonds. Compositions of the present invention used in hydrosilation reactions comprise both organometallic catalyst and components having one or more than one unsaturated carbon-carbon bond. The organometallic catalysis is as described previously above. Preferably, the organometallic catalyst is a platinum catalyst. The composition can experience temperatures of <NUM> or higher, <NUM> or higher, <NUM> or higher, even <NUM> or higher before, during or after hydrosilation so preventing aryl scission is important during hydrosilation reactions of aryl-functionalized polysiloxanes.

Applications of compositions of the present invention can require exposure to temperatures of <NUM> or higher, <NUM> or higher, <NUM> or higher, even <NUM> or higher and even <NUM> or higher. As already noted, the compositions can experience these temperatures during condensation or hydrosilation reactions. Even after such crosslinking reactions are done, or even if they do not occur, applications can require exposure to such temperatures. For example, compositions of the present invention are useful as a coating or encapsulant or elastomeric device over light emitting diodes (LEDs) and in such applications the composition can experience such temperatures. The compositions of the present invention are especially well suited for such applications because aryl scission is reduced at these temperatures for compositions of the present invention.

The following Examples (Exs) and Comparative Examples (Comp Exs) constitute compositions prepared and then tested for extent of aryl scission. Test results reveal that compositions of the present invention demonstrate significantly less aryl scission of aryl-functionalized polysiloxane than compositions outside the scope of the present invention.

The polysiloxanes used in the present examples can be prepared to the specified properties by known methods such as those taught in <CIT>, <CIT> and/or <CIT>.

The compositions of the Examples and Comparative Examples contain phenyl-functionalized polysiloxanes that, upon aryl scission, generate benzene. Determine the thermal stability of a sample composition from the Examples and Comparative Examples to aryl scission by evaluating extent of benzene generation with gas chromatography with flame ionization detection (GC-FID) while holding the composition at <NUM> for <NUM> minutes. Submit <NUM> to <NUM> grams (g) of a sample composition into a closed <NUM> milliliter headspace of a gas chromatography apparatus (GC, Agilent HP <NUM> FID Gas Chromatograph System, Hewlett Packard). Heat the sample to <NUM> for <NUM> minutes for analysis by gas chromatography with flame ionization detection (GC-FID) to check for the presence of benzene. The level of benzene in the headspace above the sample was determined by calibrating the GC using a full evaporation technique. The benzene generation in weight parts per million weight parts of sample (ppm) was calculated by the amount tested by GC-FID-headspace divided by the sample weight. A higher benzene generation from this test indicated a poorer thermal stability to aryl scission (that is, more extensive aryl scission). Similar analysis can be done for other aryl-functionalized polysiloxanes other than aryl-functionalized polysiloxanes by a similar method by quantifying the amount of aryl material generated in like manner as the amount of benzene was quantified for phenyl-functionalized polysiloxanes.

Aryl-functionalized polysiloxanes with silanol are commonly used in condensation reactions. The following examples illustrate that a quaternary ammonium compound within the scope of the present invention reduces aryl scission in such polysiloxanes, which is desirable for thermal stability of polysiloxanes in condensation reactions and reaction products.

Prepared sample compositions by combining components of the composition in a dental cup and mixing using a rotary mixer (SPEEDMIXER™ DAC <NUM> FVZ (FlackTek Inc. ) for one minute at a spinning speed of <NUM>,<NUM> revolutions per minute. Form approximately <NUM> of the resulting paste into a film by pressing between two lamination films and then dry at <NUM> for <NUM> minutes in a venting oven to remove the solvent to produce a sample composition.

Prepare Comp Ex A by combining <NUM> of Resin A1 and <NUM> of ethanol. Resin A1 is a polysiloxane characterized by the following formula: TPh<NUM>T<NUM>D<NUM> with <NUM> wt% -OH groups based on resin weight and having weight-average molecular weight of <NUM>,<NUM> grams per mole as determined by gel permeation chromatography using a polystyrene standard (for example RSN-<NUM> flake resin available from Dow Performance Silicones). Herein, "TPh" refers to a "PhSiO<NUM>/<NUM>" unit, "T" refers to "CH<NUM>SiO<NUM>/<NUM>" unit, and D refers to a "(CH<NUM>)<NUM>SiO<NUM>/<NUM>" unit. Enough units are hydroxyl substituted to provide the specified amount of hydroxyl. Subscripts refer to the molar ratio of the different units in the polysiloxane resin.

Characterization results reveal <NUM> ppm benzene production in the Aryl Scission characterization. Aryl Scission characterization results are included in Table <NUM> for comparative purposes.

Prepare and characterize Comp Ex B in like manner as Comp Ex A except combine <NUM> of calcium carbonate (catalog number <NUM> from Sigma-Aldrich) and <NUM> of Talc (3MgO*4SiO<NUM>*H<NUM>O; powder with mesh of approximately <NUM>; catalog number <NUM> from Sigma-Aldrich) with the <NUM> of Resin A1 and <NUM> of ethanol.

Characterization results reveal <NUM> ppm benzene production in the Aryl Scission characterization. Results reveal that the inorganic particulates dramatically increased the extent of aryl scission by over two orders of magnitude. Characterization results are included in Table <NUM> for comparative purposes.

Prepare and characterize Comp Exs C-F in like manner as Comp Ex B except include in the composition inorganic particulates as noted in the Table <NUM> "Description". Characterization results are in Table <NUM>. Comments indicate change in aryl scission relative to Comp Ex B.

Prepare and characterize Comp Exs C-F in like manner as Comp Ex B except include in the composition quaternary ammonium compounds as noted in the Table <NUM> "Description". Characterization results are in Table <NUM>. Comments indicate change in aryl scission relative to Comp Ex B (Comp Ex B indicate change relative to Comp Ex A). A reduction of 10x corresponds to an order of magnitude reduction and a reduction of 100x corresponds to two order of magnitude reduction.

Prepare and characterize Exs <NUM>-<NUM> in like manner as Comp Ex B except include in the composition quaternary ammonium compounds as noted in the Table <NUM> "Description". Characterization results are in Table <NUM> with Aryl Scission reporting ppm benzene and Change in phenyl scission indicating the extent of aryl scission reduction from the Comp Ex B reference. An aryl reduction of 10x corresponds to an order of magnitude reduction, 100x corresponds to two orders of magnitude reduction and 1000x corresponds to three orders of magnitude reduction.

Results of Table <NUM> reveal an extensive reduction of aryl scission when specific quaternary ammonium compounds are present, in contrast to an absence of quaternary ammonium compounds (Comp Ex B) or even the presence of "out of scope" quaternary compounds (Comp Exs G-I). *NC means not claimed.

The following pairs of Exs and Comp Exs illustrate the ability of quaternary ammonium compounds within the scope of the present invention to inhibit aryl scission for different aryl-functionalized polysiloxanes with silanol functionality.

Comp Ex A and Ex <NUM>. Prepare Ex <NUM> in like manner as Comp Ex A except include <NUM> choline salicylate. Aryl Scission characterization reveals <NUM> ppm benzene for Comp Ex A and <NUM> ppm benzene for Ex <NUM>.

Comp Ex J and Ex <NUM>. Prepare Comp Ex J in like manner as Comp Ex A except use Resin A2 as the polysiloxane, where Resin A2 has the following formula: D<NUM>DPh2<NUM>T<NUM>TPh<NUM> with one wt% -OH by weight of resin and weight-average molecular weight of <NUM>,<NUM> grams per mole (for example, Dowsil™ RSN-<NUM> flake resin from Dow Performance Silicones). "DPh2" corresponds to (Ph)<NUM>SiO<NUM>/<NUM> units. Prepare Ex <NUM> in like manner as Comp Ex J except include <NUM> choline salicylate. Aryl Scission characterization reveals <NUM> ppm benzene for Comp Ex J and <NUM> ppm benzene for Ex <NUM>.

Comp Ex K and Ex <NUM>. Prepare Comp Ex K in like manner as Comp Ex A except use Resin A3 as the polysiloxane, where Resin A3 has the following formula: D<NUM>DPh2<NUM>T<NUM>TPh<NUM> with <NUM> wt% -OH by weight of resin and weight-average molecular weight of <NUM>,<NUM> grams per mole (for example, Dowsil™ RSN-<NUM> flake resin from Dow Performance Silicones). Prepare Ex <NUM> in like manner as Comp Ex K except include <NUM> choline salicylate. Aryl Scission characterization reveals <NUM> ppm benzene for Comp Ex K and <NUM> ppm benzene for Ex <NUM>.

Comp Ex L and Ex <NUM>. Prepare Comp Ex L in like manner as Comp Ex A except use Resin A4 as the polysiloxane (see synthesis, below) and <NUM> of toluene as the solvent instead of <NUM> of ethanol and include <NUM> diazabicyclo[<NUM>. <NUM>]undec-<NUM>-ene from Aldrich. Prepare Ex <NUM> in like manner as Comp Ex L except include <NUM> choline salicylate. Aryl Scission characterization reveals <NUM> ppm benzene for Comp Ex L and <NUM> ppm benzene for Ex <NUM>.

Synthesis for Resin A4: Add to a <NUM>-liter <NUM>-nick round bottom flask <NUM> of TPh resin having a weight-average molecular weight of <NUM>,<NUM> per mole and a -OH content of <NUM> weight-percent of the resin weight (for example, Dowsil™ RSN-<NUM> Flake) and <NUM> of toluene. Equip the flask with a thermometer, Teflon stir paddle and a Dean Stark apparatus attached to a water-cooled condenser. Apply a nitrogen blanket. Prefill the Dean Stark apparatus with toluene. Use and oil bath to heat the flask contents. Heat the reaction flask contents to reflux for <NUM> minutes, then cool to <NUM> and quickly add a solution of diacetoxy terminated PhMe siloxane. Prepare the diacetoxy terminated PhMe siloxane by adding a <NUM>/<NUM> w/w MTA/ETA (<NUM>, <NUM> moles Si) mixture to a solution of α,ω-silanol terminated poly(methylphenylsiloxane) with a degree of polymerization (DP) of <NUM> (<NUM>, <NUM> moles Si) dissolved in toluene (<NUM>). Mix the solution for <NUM> hours at <NUM> under a nitrogen atmosphere. After adding diacetoxy terminated PhMe siloxane, heat the mixture to reflux for <NUM> hours. Add <NUM> <NUM>/<NUM> wt% MTA/ETA (<NUM>, <NUM> moles Si) at <NUM>. Heat the reaction mixture at reflux for one hour. Cool to <NUM> and add <NUM> milliliters deionized water. Increase the temperature to reflux and remove the water by azeotropic distillation. Cool the reaction mixture again to <NUM> and add another <NUM> milliliters of deionized water. Heat to reflux and remove water again by azeotropic distillation. Remove <NUM> toluene to increase solids content. Cool to <NUM> and filter through a <NUM> micrometer filter to obtain Resin A4. Resin A4 has the following composition: DPh<NUM>TPh<NUM> with a weight-average molecular weight of <NUM>,<NUM> grams per mole and an -OH content of <NUM> weight-percent (wt%) relative to resin weight.

Comp Ex M and Ex <NUM>. Prepare Comp Ex M in like manner as Comp Ex L except use <NUM> aluminum acetylacetonate instead of <NUM> diazabicyclo [<NUM>. <NUM>]undec-<NUM>-ene from Aldrich. Prepare Ex <NUM> in like manner as Comp Ex M except include <NUM> choline salicylate. Aryl Scission characterization reveals <NUM> ppm benzene for Comp Ex M and <NUM> ppm benzene for Ex <NUM>.

The following pairs of Exs and Comp Exs illustrate the ability of quaternary ammonium compounds within the scope of the present invention to inhibit aryl scission in the presence of inorganic particulates covering different character relative to calcium carbonate and talc.

Comp Ex N and Ex <NUM>. Prepare Comp Ex N in like manner as Comp Ex A except further include <NUM> precipitated amorphous silica (for example, Zeosil 1165MP from Solvay). Prepare Ex <NUM> in like manner as Comp Ex N except further include <NUM> choline salicylate. Aryl Scission characterization reveals <NUM> ppm benzene for Comp Ex N and <NUM> ppm benzene for Ex <NUM>.

Comp Ex O and Ex <NUM>. Prepare Comp Ex O in like manner as Comp Ex N except use kaolin claim (such as Polyplate HTM from Kamin) instead of precipitated amorphous silica. Prepare Ex <NUM> in like manner as Comp Ex O except further include <NUM> choline salicylate. Aryl Scission characterization reveals <NUM> ppm benzene for Comp Ex O and <NUM> ppm benzene for Ex <NUM>.

The following groups of Comp Exs and Exs illustrate the reduction of aryl scission also occurs in the presence of different crosslinkers, with and without kaolin clay inorganic particulate.

Comp Exs P and Q and Exs <NUM> and <NUM>. Prepare Comp Ex P in like manner as Comp Ex A except use <NUM> of <NUM>-butanoone instead of ethanol and include <NUM> ethyltriacetoxyilane. Prepare Ex <NUM> in like manner as Comp Ex P except include <NUM> choline salicylate. Prepare Comp Ex Q and Ex <NUM> in like manner as Comp Ex P and Ex <NUM>, respectively, except include <NUM> kaolin clay (Polyplate HMT). Aryl Scission characterization reveals <NUM> ppm benzene for Comp Ex P and <NUM> ppm benzene for Ex <NUM>; and <NUM>,<NUM> ppm for Comp Ex Q and <NUM> ppm for Ex <NUM>.

Comp Exs R and S and Exs <NUM> and <NUM>. Prepare Comp Exs R and S and Exs <NUM> and <NUM> in like manner as Comp Exs P and Q and Exs <NUM> and <NUM>, respectively, except use <NUM> of methyltrimethoxysilane instead of <NUM> ethyltriacetoxysilane. Aryl Scission characterization reveals <NUM> ppm benzene for Comp Ex R and <NUM> ppm benzene for Ex <NUM>; and <NUM> ppm for Comp Ex S and <NUM> ppm for Ex <NUM>.

Comp Exs T and U and Exs <NUM> and <NUM>. Prepare Comp Exs T and U and Exs <NUM> and <NUM> in like manner as Comp Exs P and Q and Exs <NUM> and <NUM>, respectively, except use <NUM> of vinyltriisopropenoxysilane instead of <NUM> ethyltriacetoxysilane. Also, use <NUM> choline salicylate in Ex <NUM> and <NUM> choline salicylate in Ex <NUM>. Aryl Scission characterization reveals <NUM> ppm benzene for Comp Ex T and <NUM> ppm benzene for Ex <NUM>; and <NUM> ppm for Comp Ex U and <NUM> ppm for Ex <NUM>.

Claim 1:
A composition comprising an aryl-functionalized polysiloxane and quaternary ammonium compound, where the polysiloxane comprises silanol functionality and <NUM> mole-percent or more T siloxane units based on total moles of siloxane units and where the quaternary ammonium compound has an anion selected from a group consisting of: halides, salicylate, octanoate, dihydrogen citrate, maleate, hydrogenglutaric acid anion, and bistartaric acid anion.