Polysiloxanes and formulations incorporating the polysiloxanes therein

Abstract

A polysiloxane comprising alkyl groups with 5 or 6 carbon atoms, alkyl groups with at least 8 carbon atoms, and / or arylalkyl groups with at least 8 carbon atoms. A process of preparing the polysiloxane by reacting polymethylhydridosiloxane with a C5 or C6 alkene and at least one of a C8-18 alkene or a C8-20 arylalkene in the presence of catalyst and solvent. The polysiloxane may be formulated into a grease comprising 50 to 95% by weight of the polysiloxane and 5 to 50% by weight of a filler. The grease composition may be suitable for use in dielectric applications, particularly with silicone-based components under strain or elongation.

Description

POLYSILOXANES AND FORMULATIONS INCORPORATINGTHE POLYSILOXANES THEREINFIELD OF INVENTION

[0001] Poly siloxanes, in particular polysiloxanes with alkyl and / or arylalkyl pendant groups, their methods of preparation, and their use in formulating dielectric greases compatible with silicone elastomers.BACKGROUND

[0002] Silicone elastomers are used in a wide range of industries, including energy, electronics, automotive and aerospace, medical, apparel, food and beverage, and construction. Silicone elastomers typically exhibit low dielectric constants, stability over wide temperature ranges, water repellency, and chemical inertness, making them ideally suited for a variety of applications. In many of these applications there is a need to lubricate and / or seal the interfaces between the silicone elastomer and other surfaces. In such instances, it is often desirable to apply a grease at the interfaces that exhibits similar low dielectric properties, temperature tolerance, water repellency and inertness.

[0003] One of the challenges in formulating greases for use with silicone elastomers is minimizing the diffusion of the grease into the silicone elastomer, which reduces availability of the grease as lubricant and / or sealant and, in some instances, may degrade the mechanical properties of the elastomer. Silicones have some of the greatest free volumes amongst polymers. This free volume is even greater under strain or elongation, which can occur during use of silicone elastomers in certain applications. Further, silicone elastomers often comprise fillers (e.g., silica, alumina, carbon black) to enhance the mechanical properties and / or impart electrical conductivity to the elastomers. Interactions between the filler and grease can present additional challenges to inhibiting diffusion of the grease into a silicone elastomer.

[0004] A variety of greases having a wide range of chemical compositions currently exist in the marketplace. A grease compatibility chart is often used to match the composition of a grease with the composition of a surface to which it is applied. In the case of silicone elastomers, polyglycol-based greases and perfluoropolyether(PFPE)-based greases are suitable matches for use with silicone elastomers. However, polyglycol-based greases tend to be hydrophilic and may be a less favorable option in applications where water and / or moisture are detrimental. Further, the current regulatory environment is moving industry away from the use of fluorinated organic compounds.

[0005] Polysiloxanes exhibit some of the same physical properties of silicone elastomers (e.g., high thermal stability, low chemical reactivity, and low dielectric constants) suggesting suitability for applications involving silicone elastomers. However, silicone -based greases, in particular those greases based on dimethyl-, phenyl, and halogenated- greases with a Viscosity Index of 200-650, are identifiedas good compatibility matches for many types of polymeric substrates, but are less favorable for substrates made of silicone elastomer.

[0006] Therefore, despite the versatility of polysiloxanes and their wide range of applications, there is a demand for polysiloxanes with improved properties and performance, particularly for use as greases and sealants.SUMMARY

[0007] Polysiloxanes can be modified by ataching different pendent groups to the silicon atoms in the polymer chain. These pendent groups can influence the properties of the polysiloxane, such as its solubility, flexibility, and compatibility with other materials. For example, alkyl pendent groups, which are chains of carbon atoms, can make the polysiloxane less likely to diffuse into silicone elastomers by creating steric hindrance and increasing the kinetic and thermodynamic energy barriers to diffusion. On the other hand, if the alkyl substituents become too large, the silicone is no longer a liquid at desired use temperatures. Many alkyl-substituted silicone greases marketed for compatibility with silicone elastomers function at zero elastomer elongation, but fail under non-zero elongation due to increasing diffusion of the grease into the elastomer under increased elongation.

[0008] The present disclosure relates to polysiloxanes and compositions containing the polysiloxanes that may be used as lubricants and / or sealants with silicone elastomers, especially in applications where the silicone elastomer is subject to elongation.

[0009] Accordingly, in one aspect, the present disclosure provides a polysiloxane comprising a polymer of Formula I:Formula I whereinR1 is a alkyl group having 1 to 6 carbon atoms,R2 is an alkyl group having 5 or 6 carbon atoms,R3 is an alkyl group having at least 8 carbon atoms,R4 is an arylalkyl group having at least 8 carbon atoms,R5 is selected from hydrogen or hydroxyl, w, x, y, and z are integers, and x and / or y is > 0; andwherein the ratio of w / (w+x+y+z) ranges from 0.01 to 0.30, ratio of x / (w+x+y+z) ranges from 0 to 0.80, ratio of y / (w+x+y+z) ranges from 0 to 0.65, and ratio of z / (w+x+y+z) ranges from 0.1 to 0.25.

[0010] In another aspect, the present disclosure provides a process of preparing polysiloxane, the process comprising reacting polymethylhydridosiloxane, a C5 or Cg alkene, and at least one of an alkene having at least 8 carbon atoms or an arylalkene having at least 8 carbon atoms, in the presence of a catalyst and a solvent. In some embodiments, the alkene having at least 8 carbon atoms is a Cx-C’ix alkene and the arylalkene having at least 8 carbon atoms is a C8-C20 arylalkene.

[0011] In another aspect, the present disclosure provides a composition comprising a) 50 to 95% by weight of the polysiloxane, and b) 5 to 50% by weight of a filler.

[0012] In another aspect, the present disclosure provides an article comprising the composition in contact with a silicone elastomer.

[0013] The above summary of the present disclosure is not intended to describe each disclosed embodiment or every implementation of the present disclosure. The description that follows more particularly exemplifies illustrative embodiments.DETAILED DESCRIPTION

[0014] Those skilled in the art will be aware that the present disclosure is subject to variations and modifications other than those specifically described. It is to be understood that the present disclosure includes all such variations and modifications. The disclosure also includes all such steps, features, compositions, and compounds referred to or indicated in this specification, individually or collectively, and any and all combinations of any or more of such steps or features.

[0015] As used herein, the term “at least one” is used to mean one or more and thus includes individual components as well as mixture s / combinations.

[0016] As used herein, the term “alkyl” broadly refers to monovalent linear chain and branched alkyl groups, as well as cyclic alkyl groups.

[0017] As used herein, the term “alkene” broadly refers to a linear or branched hydrocarbon comprising at least one carbon-carbon double bond.

[0018] As used herein, the term “aryl” broadly refers to a monovalent group that is aromatic and carbocyclic. The aryl has at least one aromatic ring but may include additional rings (saturated and / or unsaturated).

[0019] As used herein, the term “arylalkyl” broadly refers to a monovalent group where an aryl group is attached to an alkyl group. For example, the arylalkyl group can be phenylalkyl such as phenylmethyl, phenylethyl, phenylpropyl, and so on.

[0020] As used herein, the term “arylalkene” broadly refers to a linear or branched hydrocarbon comprising at least one carbon-carbon double bond and at least one aromatic ring.

[0021] As used herein, the terms, such as “a”, “an”, and “the” are not intended to refer to only a singular entity, but include the general class of which a specific example may be used for illustration. The terms “a”, “an”, and “the” are used interchangeably with the term “at least one”.

[0022] As used herein, the term “or” is generally employed in its usual sense including “and / or” unless the content clearly dictates otherwise.

[0023] As used herein, the term “and / or” means one or all of the listed elements or a combination of any two or more of the listed elements.

[0024] As used herein, the term “comprises” and variations thereof do not have a limiting meaning where these terms appear in the description and claims. Such terms will be understood to imply the inclusion of a stated step or element or group of steps or elements but not the exclusion of any other step or element or group of steps or elements. By “consisting of’ is meant including, and limited to, whatever follows the phrase “consisting of.” Thus, the phrase “consisting of’ indicates that the listed elements are required or mandatory, and that no other elements may be present. By “consisting essentially of’ is meant including any elements listed after the phrase, and limited to other elements that do not interfere with or contribute to the activity or action specified in the disclosure for the listed elements. Thus, the phrase “consisting essentially of’ indicates that the listed elements are required or mandatory, but that other elements are optional and may or may not be present depending upon whether or not they materially affect the activity or action of the listed elements.

[0025] As used herein, the term “including” is used to mean “including but not limited to”; “including” and “including but not limited to” are used interchangeably.

[0026] Also herein, all numbers are assumed to be modified by the term “about”. As used herein in connection with a measured quantity, the term “about” refers to that variation in the measured quantity as would be expected by the skilled artisan making the measurement and exercising a level of care commensurate with the objective of the measurement and the precision of the measuring equipment used. Also herein, the recitations of numerical ranges by endpoints include all numbers subsumed within that range as well as the endpoints (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, 5, etc.).

[0027] The present disclosure provides a polysiloxane of Formula I.Formula I

[0028] In this Formula I, Rl is an alkyl group having 1 to 6 carbon atoms. In some embodiments, Rl may be a methyl group or an ethyl group, more particularly a methyl group. R2 is an alkyl group having 5 or 6 carbon atoms. In some embodiments, R2 is a hexyl group, more particularly a 1 -hexyl group. R3 is an alkyl group having at least 8 carbon atoms. In some embodiments, R3 is an alkyl group having 8 to 18 carbon atoms, more particularly 9 to 13 carbon atoms. In some embodiments, R3 may be an octyl, a decyl and / or a dodecyl group, more particularly a 1 -octyl, a 1 -decyl or a 1 -dodecyl group. In some embodiments, R3 is a 1 -dodecyl group. R4 is an arylalkyl group having at least 8 carbon atoms, more particularly at least 9 carbon atoms. In some embodiments, R4 is an arylalkyl group having 8 to 20 carbon atoms, more particularly 9 to 20 carbon atoms. In some embodiments, R4 is a 2-phenylpropyl group or a 3 -phenylpropyl group. R5 is hydrogen and / or hydroxyl group. In some embodiments, R5 is hydrogen. In other embodiments, for example, at least some of the hydrogen in R5 has been hydrolyzed to a hydroxyl group.

[0029] In some embodiments, Rl, R2, R3, R4 and R5 are each a single group (e.g., all Rls in the polysiloxane are methyl groups, all R2s are a 1 -hexyl group, all R3s are a 1 -octyl group, all R4s are a 2 -phenylpropyl group, and all R5s are hydrogen). In other embodiments, one or more of Rl, R2, R3, R4 and R5 comprise two or more different groups (e.g., some R2s in the polysiloxane are a 1-pentyl group and some R2s are a 1 -hexyl group).

[0030] In some embodiments, Rl is a methyl group and R2 is an 1 -hexyl group. In the same or different embodiments, R3 is a 1 -dodecyl group. In the same and / or different embodiments, R4 is a 2- phenylpropyl group or a 3 -phenylpropyl group. In some embodiments, none of R2, R3, R4 and R5 are a phenyl group or a methyl group.

[0031] The selection of Rl, R2, R3, R4 and R5 can be adjusted depending upon the desired application of the polysiloxane. For example, the alkyl groups R2 and R3, having 5 or 6 carbon atoms and at least 8 carbon atoms, respectively, contribute to the hydrophobic nature of the polysiloxane. This hydrophobicity is beneficial in electrical and electronics grease applications, as it helps to repel water, prevents moisture from affecting the electrical performance, and maintains a desirably low dielectric constant. The arylalkyl group of R4, having at least 8 carbon atoms, can also contribute to the hydrophobicity of the poly siloxane.

[0032] The integers w, x, y, and z in Formula I represent the number of repeating units with R2, R3, R4, and R5 groups, respectively. The ratio of w / (w+x+y+z) ranges from 0.01 to 0.30; the ratio of x / (w+x+y+z) ranges from 0 to 0.80; the ratio of y / (w+x+y+z) ranges from 0 to 0.65; the ratio of z / (w+x+y+z) ranges from 0.1 to 0.25; and, x and / or y is > 0. In some embodiments, the sum of the ratios x / (w+x+y+z) and y / (w+x+y+z) is at least 0.46. In some embodiments, the sum of the ratios x / (w+x+y+z) and y / (w+x+y+z) ranges from 0.46 to 0.80.

[0033] The ratios of w, x, y and z can also be tailored for the desired application of the polysiloxane. For instance, in some embodiments, the ratio of w / (w+x+y+z) may be 0.01. This means that 1% of the total number of units in the polysiloxane have R2 groups, which are alkyl groups having 5 or 6 carbon atoms. This can contribute to the overall hydrophobicity and flexibility of the polysiloxane. In some embodiments, the ratio of w / (w+x+y+z) is at least 0.01, at least 0.06, at least 0.08, at least 0.09, at least 0.12, or at least 0. 19. In some embodiments, the ratio of w / (w+x+y+z) is no greater than 0.29, no greater than 0.19, no greater than 0. 12, no greater than 0.09, no greater than 0.08, or no greater than 0.06. In some embodiments, the ratio w / (w+x+y+z) is 0.01 to 0.29, more particularly 0.08 to 0.29.

[0034] In some embodiments, the ratio of x / (w+x+y+z) may be 0.80. This means that 80% of the total number of units in the polysiloxane have R3 groups, which are alkyl groups having at least 8 carbon atoms, more particularly having 8 to 18 carbon atoms, and even more particularly 9 to 13 carbon atoms. The presence of these larger alkyl groups can enhance the hydrophobicity and decrease the dielectric constant of the polysiloxane, making it more suitable for use in greases for electrical and electronics applications. In some embodiments, the ratio of x / (w+x+y+z) is 0, at least 0.08, at least 0.36, at least 0.42, at least 0.46, at least 0.51, at least 0.74, or at least 0.76. In some embodiments, the ratio of x / (w+x+y+z) is no greater than 0.80, no greater than 0.79, no greater than 0.76, no greater than 0.74, no greater than 0.51, no greater than 0.46, no greater than 0.42, no greater than 0.36, or no greater than 0.08. In some embodiments, the ratio of x / (w+x+y+z) is 0 to 0.80, more particularly 0 to 0.79, or even more particularly 0 to 0.74.

[0035] In other cases, the ratio of y / (w+x+y+z) may be 0.65. This means that 65% of the total number of units in the poly siloxane have R4 groups, which are arylalkyl groups having at least 8 carbon atoms, more particularly having 8 to 20 carbon atoms. The inclusion of these larger arylalkyl groups can further increase the hydrophobicity of the polysiloxane and minimize its diffusion into silicone elastomers, particularly silicone elastomers under elongation. In some embodiments, the ratio of y / (w+x+y+z) is 0, at least 0.25, at least 0.28, at least 0.39, at least 0.61, or at least 0.63. In some embodiments, the ratio of y / (w+x+y+z) is no greater than 0.65, no greater than 0.63, no greater than 0.61, no greater than 0.39, no greater than 0.28, or no greaterthan 0.25. In some embodiments, the ratio y / (w+x+y+z) is 0 to 0.65, more particularly 0 to 0.63.

[0036] In yet other cases, the ratio of z / (w+x+y+z) may be 0.10. This means that 10% of the total number of units in the polysiloxane have R5 groups, which is hydrogen or hydroxyl. In some embodiments, the ratio of z / (w+x+y+z) is at least 0.10, at least 0.16, at least 0.17, at least 0.18, or at least 0.24. In some embodiments, the ratio z / (w+x+y+z) is no greater than 0.25, no greater than 0.24, no greater than 0.18, no greater than 0.17, or no greater than 0.16. In some embodiments, the ratio z / (w+x+y+z) is 0.10 to 0.25, more particularly 0.16 to 0.25.

[0037] In some embodiments, the sum of the ratios x / (w+x+y+z) and y / (w+x+y+z) is 0.46. This indicates that 46% of the total number of units in the polysiloxane have R2 and / or R3 groups. In some embodiments, the sum of the ratios x / (w+x+y+z) and y / (w+x+y+z) is at least 0.46, at least 0.63, at least 0.65, at least 0.69, at least 0.70, at least 0.74, at least 0.75, at least 0.76, at least 0.79, or at least 0.80. In some embodiments, the sum of the ratios x / (w+x+y+z) and y / (w+x+y+z) is no greater than 0.80, no greater than 0.79, no greater than 0.76, no greater than 0.75, no greater than 0.74, no greater than 0.70, no greater than 0.69, no greater than 0.65, or no greater than 0.63. In some embodiments, the sum of the ratios x / (w+x+y+z) and y / (w+x+y+z) is 0.46 to 0.80, more particularly 0.46 to 0.79, or even more particularly 0.46 to 0.79. This high proportion of larger alkyl and / or arylalkyl groups can contribute to the overall hydrophobicity and low diffusivity of the polysiloxane, making it particularly suitable for use in dielectric greases that are in contact with silicone elastomers under strain or elongation.

[0038] The repeating units of the polysiloxane of Formula 1 (i.e., w, x, y and z) are typically randomly arranged. However, in some instances, the units may be arranged in blocks.

[0039] A process for preparing the polysiloxanes disclosed herein comprises reacting polymethylhydridosiloxane, a C5 or Cg alkene (i.e., an alkene having 5 or 6 carbon atoms), and at least one of an alkene having at least 8 carbon atoms or an arylalkene having at least 8 carbon atoms, in the presence of a catalyst and a solvent. In some embodiments, the alkene having at least 8 carbon atoms is a Cg-Cig alkene and the arylalkene having at least 8 carbon atoms is a C8-C20 arylalkene. In some embodiments, the alkene having at least 8 carbon atoms is 1 -decene or 1 -dodecene. In the same or other embodiments, the arylalkene having at least 8 carbon atoms is alpha-methyl styrene (2 -phenylpropene) or allylbenzene. In some embodiments, the C5 or Cg alkene is 1 -hexene, and the at least one of an alkene having at least 8 carbon atoms or an arylalkene having at least 8 carbon atoms is 1 -dodecene. In some additional embodiments, the C5 or Cg alkene is 1 -hexene, and the at least one of an alkene having at least 8 carbon atoms or an arylalkene having at least 8 carbon atoms is 1 -dodecene and alphamethylstyrene.

[0040] The process of preparing the polysiloxane may be carried out at a temperature in the range of 30 to 200 °C. The reaction temperature may be at least 30 °C, at least 35 °C, at least 40 °C, at least 45 °C, at least 50 °C, at least 55 °C, at least 60 °C, at least 65 °C, at least 70 °C, at least 75 °C, at least 80 °C, at least 85 °C, at least 90 °C, at least 95 °C, at least 100 °C, at least 105 °C, at least 110 °C, at least115 °C, at least 120 °C, at least 125 °C, at least 130 °C, at least 135 °C, at least 140 °C, at least 145 °C, at least 150 °C, at least 155 °C, at least 160 °C, at least 165 °C, at least 170 °C, at least 175 °C, at least 180 °C, at least 185 °C, at least 190 °C, or at least 195 °C. In some embodiments, the reaction temperature may be no greater than 200 °C, no greater than 195 °C, no greater than 190 °C, no greater than 185 °C, no greater than 180 °C, no greater than 175 °C, no greater than 170 °C, no greater than 165 °C, no greater than 160 °C, no greater than 155 °C, no greater than 150 °C, no greater than 145 °C, no greater than 140 °C, no greater than 135 °C, no greater than 130 °C, no greater than 125 °C, no greater than 120 °C, no greater than 115 °C, no greater than 110 °C, no greater than 105 °C, no greater than 100 °C, no greater than 95 °C, no greater than 90 °C, no greater than 85 °C, no greater than 80 °C, no greater than 75 °C, no greater than 70 °C, no greater than 65 °C, no greater than 60 °C, no greater than 55 °C, no greater than 50 °C, no greater than 45 °C, no greater than 40 °C, or no greater than 35 °C. In some cases, the reaction is carried out at 60 °C and / or at 40 °C. The choice of reaction temperature can influence the reaction rate and the properties of the resulting polysiloxane. For instance, a higher reaction temperature may increase the reaction rate and yield a polysiloxane with different properties compared to a polysiloxane prepared at a lower reaction temperature. In some cases, the reaction temperature may be specifically chosen based on the reactants and catalyst used, as well as the desired properties of the resulting polysiloxane.

[0041] In some embodiments, the polymethylhydridosiloxane has a weight average molecular weight ranging from 1000 to 5000 g / mol, more particularly ranging from 1300 to 2500 g / mol, and even more particularly from 1400 to 2400 g / mol. In some embodiments, the polymethylhydridosiloxane has a weight average molecular weight ranging from 1400 to 1800 g / mol. In other embodiments, the polymethylhydridosiloxane has a weight average molecular weight ranging from 2100 to 2400 g / mol. In some embodiments, the polymethylhydridosiloxane is trialkylsilyl-terminated, more particularly trimethylsilyl-terminated.

[0042] Exemplary catalysts include platinum divinyltetramethyldisiloxane complex, platinum cyclovinylmethylsiloxane complex, platinum carbonyl cyclovinylmethylsiloxane complex, platinum octanal complex, trisdibutylsulfide rhodium trichloride, or combinations thereof. In some embodiments, the catalyst is a platinum divinyltetramethyldisiloxane complex. The choice of catalyst can influence the structure and properties of the resulting polysiloxane. For instance, the platinum divinyltetramethyldisiloxane complex can facilitate the reaction between the hydridosilane-functional polysiloxane and the alkene, leading to the formation of the desired polysiloxane.

[0043] Suitable solvents may include xylene, toluene, benzene, chloroform, dichloromethane, tetrahydrofuran, or combinations thereof. The choice of solvent can affect the reaction conditions and the solubility of the reactants and products. For example, xylene, toluene, benzene, chloroform, dichloromethane, and tetrahydrofuran are all suitable solvents that can dissolve the reactants and facilitate the reaction.

[0044] After the reaction, the solvent may be removed in vacuo to yield the polysiloxane as a viscous liquid. This step can help to purify the polysiloxane and remove any unreacted materials or byproducts. The resulting polysiloxane can then be used in the formulation of greases, as further described below.

[0045] The grease composition may comprise 50 to 95% by weight of the polysiloxanes disclosed herein, and 5 to 50% by weight of a filler. In some embodiments, the polysiloxanes comprise at least 50%, at least 55%, at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, or at least 90% by weight with respect to total weight of the grease composition. In some embodiments, the polysiloxanes comprise no greater than 95%, no greater than 90%, no greater than 85%, no greater than 80%, no greater than 75%, no greater than 70%, no greater than 65%, no greater than 60%, or no greater than 55% by weight with respect to the total weight of the grease composition. The polysiloxane in the grease composition may provide the desired hydrophobic and low dielectric properties and the weight percentage can be adjusted to meet specific application and performance requirements of the grease.

[0046] In some embodiments, the filler may constitute 5 to 50% by weight of the grease composition. In some embodiments, the filler is at least 5%, at least 10%, at least 15%, at least 20%, at least 25%, at least 30%, at least 35%, at least 40%, or at least 45% by weight with respect to total weight of the grease composition. In some embodiments, the filler is no greater than 50%, no greater than 45%, no greater than 40%, no greater than 35%, no greater than 30%, no greater than 25%, no greater than 20%, no greater than 15%, or no greater than 10% by weight with respect to the total weight of the grease composition. The filler may contribute to the overall consistency and stability of the grease, and the weight percentage of the filler can be adjusted to meet specific application and performance requirements of the grease.

[0047] The filler in the grease composition may be selected from a variety of materials, depending on the desired properties of the grease. Exemplary fillers include silica, aluminosilicate clay, alumina, mica, lithium stearate, calcium stearate, carbon black, fluoropolymer, polyurea, or combinations thereof.

[0048] In some embodiments, the filler is silica, more particularly hydrophobic fumed silica. Silica is a commonly used filler in grease compositions due to its excellent thermal stability and ability to enhance the viscosity of the grease. In other embodiments, the filler is aluminosilicate clay. Aluminosilicate clay can provide good thermal stability and can also enhance the thixotropic properties of the grease, making it more resistant to flow under low shear stress.

[0049] In yet other embodiments, the filler is alumina. Alumina is a high temperature-resistant material that can enhance the thermal stability of the grease. In some embodiments, the filler is mica. Mica is a naturally occurring mineral that can enhance the lubricity and thermal stability of the grease. In otherembodiments, the filler is lithium stearate or calcium stearate. These materials are commonly used as thickeners in grease compositions and can enhance the consistency and stability of the grease.

[0050] In further embodiments, the filler is carbon black. Carbon black is a material that can enhance the electrical conductivity of the grease, making it suitable for use in electrical applications. In some embodiments, the filler may be a fluoropolymer. Fluoropolymers are materials with excellent chemical resistance and low friction properties, making them suitable for use in harsh environments. In other embodiments, the filler is polyurea. Polyurea is a material that can enhance the water resistance and mechanical stability of the grease.

[0051] It is to be appreciated that the specific type of filler used in the grease composition can be selected based on the application and performance requirements of the grease. By varying the type of filler, the properties of the grease can be tailored to suit specific applications.

[0052] In some embodiments, a grease composition is formulated from the polysiloxane and hydrophobic fumed silica. The formulation process involves combining the polysiloxane and hydrophobic fumed silica in a speed mixer. In some embodiments, the grease composition is formulated from 14 parts by weight of the poly siloxane and 1.5 parts by weight of hydrophobic fumed silica. The polysiloxane and hydrophobic fumed silica are combined in a speed mixer, which is operated at a rotational speed of 3500 revolutions per minute (rpm) for a duration of 1 minute. This formulation process ensures a homogeneous mixture of the polysiloxane and hydrophobic fumed silica, resulting in a grease composition with desirable properties for use in dielectric applications.

[0053] The hydrophobic fumed silica in the grease composition serves as a fdler, contributing to the overall consistency and stability of the grease. The hydrophobic nature of the fumed silica enhances the water-repellent properties of the grease, making it suitable for use in high voltage applications where moisture resistance is paramount. Furthermore, the fumed silica can enhance the thixotropic properties of the grease, making it more resistant to flow under low shear stress, which is beneficial in applications where the grease is subjected to mechanical stress or vibration.

[0054] The present disclosure also provides articles comprising compositions described herein in contact with an elastomer. In some embodiments, the elastomer is a silicone rubber or a carbon-black- filled silicone rubber. The elastomer may form components (e.g., O-rings, gaskets, valves, tubes, film, etc.) in, for example, medical devices, safety & breathing apparatus, cooling & cryogenic systems, automotive and aerospace technologies, electrical cables and accessories, electronic devices and electronics packaging, food production and processing equipment, pharmaceutical production equipment, industrial and manufacturing equipment, and oil, gas and mining equipment. In some embodiments, the article may be part of an electrical or electronics construction.

[0055] Compatibility of the grease composition with the elastomer can be evaluated by measuring the percent mass uptake of the grease by the elastomer under strain or elongation. The percent mass uptakeis calculated based on the initial (dry) mass of the elastomer and the mass of the elastomer after immersion in the grease composition for the specified duration and temperature. A lower percent mass uptake indicates a lower diffusivity of the grease composition into the elastomer, which is a desirable property for greases used with silicone-based components under strain or elongation.

[0056] The elastomers in the articles disclosed herein may exhibit a mass uptake of less than 3.0% by weight when in contact with the grease composition for a time period greater than 14 days at a temperature greater than or equal to 80 °C and at an elongation under strain in a range of 50% to about 150% of their original length. In one embodiment, the article comprises a grease composition in contact with a silicone elastomer that may or may not comprise carbon black. In some embodiments, the silicone elastomer exhibits a mass uptake of less than 3.0% by weight when in contact with the grease composition for 10 days at a temperature of 80 °C and at an elongation under strain of about 100% of its original length. In some embodiments, the silicone elastomer exhibits a mass uptake of less than 0.5% by weight when in contact with the grease composition for 10 days at a temperature of 80 °C and at an elongation under strain of about 100% of its original length.

[0057] Although specific embodiments have been illustrated, it will be appreciated by those of ordinary skill in the art that a wide variety of alternate and / or equivalent implementations may be substituted for the specific embodiments shown and described without departing from the scope of the present invention. This application is intended to cover any adaptations or variations of the exemplified embodiments discussed herein.EXAMPLES

[0058] Objects and advantages of this disclosure are further illustrated by the following examples, but the particular materials and amounts thereof recited in these examples, as well as other conditions and details, should not be construed to unduly limit this disclosure.

[0059] Unless otherwise noted, all parts, percentages, ratios, etc. in the examples and the rest of the specification are expressed by weight. Abbreviations for materials used in this section, as well as descriptions of the materials, are provided in Table 1.Table 1. Materials Used in the ExamplesPreparatory Examples

[0060] Generally, polysiloxanes (Pl -Pl 1) were prepared by the reaction of polymethylhydridosiloxane with an alkene and / or arylalkene in presence of a catalyst and a solvent. The catalyst was platinum divinyltetramethyldisiloxane, supplied as a xylene solution. The solvent was toluene.Polysiloxane Pl

[0061] PMHS 1 (12.83 g, 0.214 mol SiH, Mw 1400-1800 g / mol) was added to a solution of 1-decene (22.51 g, 0. 160 mol), Pt catalyst (1 drop), and toluene (100 mL). The toluene was previously dried over 4A molecular sieves. The reaction mixture was stirred at 60 °C for 3 days, cooled to 40 °C, and 1- hexene (4.50 g, 0.053 mol) was added. The mixture was stirred for a further 3 days at 40 °C and toluene was removed in vacuo to give the product as a viscous liquid.Polysiloxane P2

[0062] PMHS 1 (9.80 g, 0.163 mol SiH, Mw 1400-1800 g / mol) was added to a solution of 1-dodecene (27.43 g, 0. 163 mol), Pt catalyst (1 drop), and toluene (150 mL). The toluene was previously dried over 4 A molecular sieves. The reaction mixture was stirred at 60 °C for 3 days, cooled to 40 °C, and 1- hexene (3.45 g, 0.041 mol) was added. The mixture was stirred for a further 3 days at 40 °C and toluene was removed in vacuo to give the product as a viscous liquid.Polysiloxane P3

[0063] PMHS 1 (9.80 g, 0.163 mol SiH, Mw 1400-1800 g / mol) was added to a solution of 1-dodecene (16.50 g, 0.065 mol), alpha-methylstyrene (7.68 g, 0.098 mol), Pt catalyst (1 drop), and toluene (150 mL) . The toluene was previously dried over 4 A molecular sieves. The reaction mixture was stirred at 60 °C for 3 days, cooled to 40 °C, and 1-hexene (3.45 g, 0.041 mol) was added. The mixture was stirred for a further 3 days at 40 °C and toluene was removed in vacuo to give the product as a viscous liquid.Polysiloxane P4

[0064] PMHS 2 (15.0 g, 0.25 mol SiH, Mw 2100-2400 g / mol) was added to a solution of 1-dodecene (19.36 g, 0.115 mol), alpha-methylstyrene (8.86 g, 0.075 mol), Pt catalyst (1 drop), and toluene (150 mL). The toluene was previously dried over 4 A molecular sieves. The reaction mixture was stirred at60 °C for 3 days, cooled to 40 °C, and 1-hexene (5.05 g, 0.06 mol) was added. The mixture was stirred for a further 3 days at 40 °C and toluene was removed in vacuo to give the product as a viscous liquid.Polysiloxane P5

[0065] PMHS 1 (15.0 g, 0.25 mol SiH, Mw 1400-1800 g / mol) was added to a solution of 1-dodecene (15.15 g, 0.09 mol), alpha-methylstyrene (13.0 g, 0.11 mol), Pt catalyst (1 drop), and toluene (150 mL). The toluene was previously dried over 4 A molecular sieves. The reaction mixture was stirred at 60 °C for 3 days, cooled to 40 °C, and 1-hexene (4.21g, 0.05 mol) was added. The mixture was stirred for a further 3 days at 40 °C and toluene was removed in vacuo to give the product as a viscous liquid.Polysiloxane P6

[0066] PMHS 1 (15.0 g, 0.25 mol SiH, Mw 1400-1800 g / mol) was added to a solution of 1-dodecene (3.37 g, 0.02 mol), alpha-methylstyrene (21.27 g, 0.18 mol), Pt catalyst (1 drop), and toluene (150 mL). The toluene was previously dried over 4 A molecular sieves. The reaction mixture was stirred at 60 °C for 3 days, cooled to 40 °C, and 1-hexene (4.21 g, 0.05 mol) was added. The mixture was stirred for a further 3 days at 40 °C and toluene was removed in vacuo to give the product as a viscous liquid.Polysiloxane P7

[0067] PMHS 1 (14.67 g, 0.245 mol SiH, Mw 1400-1800 g / mol) was added to a solution of alphamethylstyrene (20.74 g, 0.176 mol), Pt catalyst (1 drop), and toluene (150 mL). The toluene was previously dried over 4 A molecular sieves. The reaction mixture was stirred at 60 °C for 3 days, cooled to 40 °C, and 1-hexene (5.7 6g, 0.0684 mol) was added. The mixture was stirred for a further 3 days at 40 °C and toluene was removed in vacuo to give the product as a viscous liquid.Polysiloxane P8

[0068] PMHS 1 (15.00 g, 0.250 mol SiH, Mw 1400-1800 g / mol) was added to a solution of 1-dodecene (25.04 g, 0. 125 mol), Pt catalyst (1 drop), and toluene (150 mL). The toluene was previously dried over 4 A molecular sieves. The reaction mixture was stirred at 60 °C for 4 days, cooled to 50 °C, and 1- hexene (12.62 g, 0.150 mol) was added. The mixture was stirred for a further 3 days at 50 °C and toluene and excess alkene were removed in vacuo to give the product as a viscous liquid.Polysiloxane P9

[0069] PMHS 1 (8.51 g, 0.142 mol SiH, Mw 1400-1800 g / mol) was added to a solution of 1-octene (15.91 g, 0. 142 mol), Pt catalyst (1 drop), and toluene (100 mL). The toluene was previously dried over 4 A molecular sieves. The reaction mixture was stirred at 60 °C for 6 days, cooled to 50 °C, and 1- hexene (5.00 g, 0.059 mol) was added. The mixture was stirred for a further 2 days at 50 °C and toluene and excess alkene were removed in vacuo to give the product as a viscous liquid.Polysiloxane PIO

[0070] PMHS 1 (9.80 g, 0.163 mol SiH, Mw 1400-1800 g / mol) was added to a solution of allylcyclopentane (17.96 g, 0.163 mol), Pt catalyst (1 drop), and toluene (150 mL). The toluene was previously dried over 4 A molecular sieves. The reaction mixture was stirred at 60°C for 2 days, cooled to 50 °C, and 1-hexene (5.00 g, 0.059 mol) was added. The mixture was stirred for a further 2 days at 50 °C and toluene and excess alkene were removed in vacuo to give the product as a viscous liquid.Polysiloxane Pll

[0071] PMHS 1 (9.80 g, 0.163 mol SiH, Mw 1400-1800 g / mol) was added to a solution of allylbenzene (19.26 g, 0. 163 mol), Pt catalyst (1 drop), and toluene (150 mL). The toluene was previously dried over 4 A molecular sieves. The reaction mixture was stirred at 60 °C for 2 days, cooled to 50 °C, and 1- hexene (5.00 g, 0.059 mol) was added. The mixture was stirred for a further 2 days at 50 °C and toluene and excess alkene were removed in vacuo to give the product as a viscous liquid.Comparative Polysiloxane CPI

[0072] PMHS 1 (15.0 g, 0.25 mol SiH, Mw 1400-1800 g / mol) was added to a solution of 1-hexene (24.2 g, 0.29 mol), Pt catalyst (1 drop), and toluene (150 mL). The toluene was previously dried over 4 A molecular sieves. The reaction mixture was stirred at 40 °C for 5 days and toluene was removed in vacuo to give the product as a viscous liquid.Comparative Polysiloxane CP2

[0073] PMHS 2 (15.0 g, 0.25 mol SiH, Mw 2100-2400 g / mol) was added to a solution of 1-hexene (24.2 g, 0.29 mol), Pt catalyst (1 drop), and toluene (150 mL). The toluene was previously dried over 4 A molecular sieves. The reaction mixture was stirred at 40 °C for 5 days and toluene was removed in vacuo to give the product as a viscous liquid.Comparative Polysiloxane CP3

[0074] PMHS 1 (9.80 g, 0.163 mol SiH, Mw 1400-1800 g / mol) was added to a solution of 1-heptene (16.00 g, 0. 163 mol), Pt catalyst (1 drop), and toluene (100 mL). The toluene was previously dried over 4 A molecular sieves. The reaction mixture was stirred at 60 °C for 3 days, cooled to 50 °C, and 1- hexene (5.00 g, 0.059 mol) was added. The mixture was stirred for a further 2 days at 50 °C and toluene and excess alkene were removed in vacuo to give the product as a viscous liquid.Nuclear Magnetic Resonance (NMR)

[0075] NMR analysis of the polysiloxanes prepared above were carried out using solutions of the polysiloxanes in deuterated chloroform. NMR analysis was conducted using a Bruker AVANCE III 500 MHz NMR spectrometer equipped with a CPBBO gradient cryoprobe, a Bruker B-ACS 60autosampler, and Broker Topspin 3.04 software. Spectra were analyzed using Advanced Chemistry Development software (Toronto, Canada). For poly siloxanes, integration was used to determine the hydrosilylation reaction yield and percent substitution via loss of the starting material SiH peak at 4.7 ppm and by the appearance of product SiC F peaks at 0.5 ppm. In samples where polysiloxanes carried two or more different pendent groups, their levels were also determined by integration, for example by comparing integrals of product alkyl pendants (terminal CH3 at 0.8 ppm) and phenylpropyl pendants (PhCH at 2.9 ppm). Results are shown in Tables 2 and 3.Grease Compositions Gl-Gll

[0076] Grease compositions Gl-Gl l were each made by combining 14 parts by weight of the polysiloxanes indicated in Table 4 (Column 2) with 1.5 parts by weight hydrophobic fumed silica in a speed mixer at 3500 rpm for 1 minute.Comparative Grease Compositions CG1-CG10

[0077] Comparative grease compositions CG1-CG4 and CG6-CG8 were each made by combining 14 parts by weight of the polysiloxanes indicated in Table 4 (Column 2) with 1.5 parts by weight hydrophobic fumed silica in a speed mixer at 3500 rpm for 1 minute. Comparative grease composition CG5 was the polysiloxane indicated in Table 4 (Column 2) used “as is” (i.e., not combined with hydrophobic fumed silica).Mass Uptake Test Method

[0078] The performance of each grease composition was evaluated by measuring mass uptake by an elastomer (ELAS 1 or ELAS 2) immersed in the grease composition for a prolonged period of time. ELAS 1 is a mineral-filled silicone rubber insulator. ELAS 2 is a semi-conductive carbon-black filled silicone rubber.

[0079] Elastomers were molded into tubes have the following dimensions: an inner diameter of 1.91 cm (0.75 inches); a wall thickness of 0.305 cm (0.120 inches); and a length of 20.3 cm (8 inches). The molded tubes were post-cured in an oven at 200 °C for 2 hours prior to cutting into the corresponding test specimens. Ring test specimens were cut from molded tubes using a lathe to cut the rings at 8 mm in length.

[0080] Ring specimens of the elastomers were slid onto stainless steel mandrels or a jig to provide an elongation of 100%. The rings were then coated with a generous amount of the grease composition and placed in an air-convection oven at 80 °C for 10 days. At the end of 10 days, the rings were slid off the mandrels and excess grease was cleaned off their surface using paper towels. The percent mass uptake was calculated based on the initial (dry) mass of the given specimen. The average of 2 or 3 replicate specimens for each elastomer and grease composition are reported in Table 4.Table 2. Compositions of PolysiloxanesTable 3. Mole Ratios of Repeating Polysiloxane Subunits w, x, y and z*CP3 contains primarily 1 -heptyl side groups, which do not fall under w, x, y or z.Table 4. Mass Uptake of Grease by Elastomers

[0081] Thus, the present disclosure provides, among other things polysiloxanes with alkyl and / or arylalkyl pendant groups, their methods of preparation, and their use in formulating greases compatible with silicone elastomers. Various features and advantages of the present disclosure are set forth in the following claims.

Claims

What is claimed is:

1. A polysiloxane comprising a polymer of Formula I:Formula I whereinR1 is an alkyl group having 1 to 6 carbon atoms,R2 is an alkyl group having 5 or 6 carbon atoms,R3 is an alkyl group having at least 8 carbon atoms,R4 is an arylalkyl group having at least 8 carbon atoms,R5 is selected from hydrogen or hydroxyl, w, x, y, and z are integers, and x and / or y is > 0; and wherein the ratio of w / (w+x+y+z) ranges from 0.01 to 0.30, ratio of x / (w+x+y+z) ranges from 0 to 0.80, ratio of y / (w+x+y+z) ranges from 0 to 0.65, and ratio of z / (w+x+y+z) ranges from 0.1 to 0.25.

2. The polysiloxane of claim 1, wherein R3 is an alkyl group having 8 to 18 carbon atoms.

3. The polysiloxane of claim 1 or claim 2, wherein R4 is an arylalkyl group having 8 to 20 carbon atoms.

4. The polysiloxane of any one of claims 1 to 3, wherein R1 is a methyl group and R2 is a 1 -hexyl group.

5. The polysiloxane of any one of claims 1 to 4, wherein R3 is a 1 -dodecyl group.

6. The polysiloxane of any one of claims 1 to 5, wherein R4 is at least one of a 2- phenylpropyl group or a 3 -phenylpropyl group.

7. The polysiloxane of any one of claims 1 to 6, wherein the sum of the ratios x / (w+x+y+z) and y / (w+x+y+z) is at least 0.46.

8. The polysiloxane of any one of claims 1 to 7, wherein sum of the ratios x / (w+x+y+z) and y / (w+x+y+z) ranges from 0.46 to 0.80.

9. A process for preparing the polysiloxane of any one of claims 1 to 8, the process comprising reacting polymethylhydridosiloxane, a C5 or G, alkene, and at least one of an alkene having at least 8 carbon atoms or an arylalkene having at least 8 carbon atoms, in the presence of a catalyst and a solvent.

10. The process of claim 9, wherein the alkene having at least 8 carbon atoms is a Cg-Cis alkene and the arylalkene having at least 8 carbon atoms is a C8-C20 arylalkene.

11. The process of claim 9 or claim 10, wherein the reacting is carried out at a temperature in a range of 30 to 200 °C.

12. The process of any one of claims 9 to 11, wherein the catalyst is selected from platinum divinyltetramethyldisiloxane complex, platinum cyclovinylmethylsiloxane complex, platinum carbonyl cyclovinylmethylsiloxane complex, platinum octanal complex, trisdibutylsulfide rhodium trichloride, or combinations thereof; and solvent is selected from xylene, toluene, benzene, chloroform, dichloromethane, tetrahydrofuran, or combinations thereof.

13. The process of any one of claims 9 to 12, further comprising removing the solvent in vacuo to yield the polysiloxane as a viscous liquid.

14. A composition comprising: a) 50 to 95% by weight of the polysiloxane in any one of claims 1 to 8; and b) 5 to 50% by weight of a filler.

15. The composition of claim 14, wherein the filler is selected from silica, aluminosilicate clay, alumina, mica, lithium stearate, calcium stearate, carbon black, fluoropolymer, polyurea, or combinations thereof.

16. An article comprising the composition of claim 14 or claim 15 in contact with a silicone elastomer.

17. The article of claim 16, wherein the silicone elastomer further comprises carbon black.

18. The article of claim 16 or claim 17, wherein the silicone elastomer exhibits mass uptake of less than 3.0% by weight when in contact with the grease composition for 10 days at a temperature of 80 °C and at an elongation under strain of 100% of its original length, as provided in the Mass Uptake Test Method provided herein.

19. The article of claim 16 or claim 17, wherein the silicone elastomer exhibits mass uptake of less than 0.5% by weight when in contact with the grease composition for 10 days at a temperature of 80 °C and at an elongation under strain of 100% of its original length, as provided in the Mass Uptake Test Method provided herein.

Images