Quick Recovery Silicone Gel

Abstract

A sealant, including a silicone gel, composition, and method of making, is provided for use in sealing telecommunications closures. The silicone gel can rapidly seal and reseal, for example, within five minutes of closure.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application was filed as a PCT international patent application on November 23, 2020, and claims the benefit of U.S. Patent Application No. 62 / 942,594, filed December 2, 2019, and U.S. Patent Application No. 63 / 013,992, filed April 22, 2020, the disclosures of which are incorporated herein by reference in their entireties. [Background technology]

[0002] Telecommunications systems typically employ networks of telecommunications cables capable of transmitting large amounts of data and voice signals over relatively long distances. The telecommunications cables may include fiber optic cables, electrical cables, or a combination of electrical and fiber optic cables. A typical telecommunications network also includes multiple telecommunications enclosures and interconnection systems integrated throughout the network of telecommunications cables. The telecommunications enclosures and interconnection systems are typically sealed to prevent the ingress of moisture or other contaminants. Silicone gel is a thermosetting gel that exhibits desirable physical properties for use as a sealant in closures or interconnection systems.

[0003] For example, U.S. Patent Nos. 8,642,891 and 9,556,336, by Berghmans et al., disclose silicone dry gels suitable for use in closure or interconnect systems. The silicone dry gels were developed without silicone oil to avoid excessive oil bleed-out. The silicone dry gels may be prepared from vinyl-terminated polydimethylsiloxane (PDMS), a hydride-containing crosslinker, and a hydride-containing chain extender, and the dry silicone gels have hardnesses ranging from 100 g to 300 g. A target hardness is required for the gel to function from a sealing perspective.

[0004] One problem with silicone dry gel is that it exhibits a long relaxation time and a wide distribution of relaxation times. Silicone dry gel exhibits a relatively slow response when the gel is formed into a gel block and placed into a closure system. This means that the closure does not seal immediately after closure. It is common for closures using silicone dry gel to take up to 15 minutes or more to seal to 20 kPa, and in some cases (depending on the cable size, combination, and configuration), it can take up to two hours to seal the closure. It is desirable to provide a silicone gel for use in closures that can seal and reseal as quickly as possible, preferably within five minutes of closure. Summary of the Invention

[0005] A sealant, including a silicone gel, composition, and method of making, is provided for use in sealing telecommunications closures and interconnection systems. The silicone gel can rapidly seal and reseal, for example, within five minutes of closure.

[0006] A method for making a silicone gel is provided, comprising: providing a first component set comprising (1) a base polymer having vinyl-silicone groups, (2) an addition cure catalyst, and optionally (3) a non-reactive silicone oil; providing a second component set comprising (1) a crosslinker, (2) an additional base polymer having vinyl-silicone groups, and optionally (3) a non-reactive silicone oil; mixing the first and second component sets together to form a silicone gel composition; and molding and curing the silicone gel composition to form the silicone gel. The second component set can further comprise a chain extender.

[0007] The silicone gel composition comprises 10-60 wt%, 20-55 wt%, or 30-50 wt% of a non-reactive silicone oil. The first and / or second component sets comprise a non-reactive silicone oil.

[0008] The non-reactive silicone oil may be a trimethylsiloxy-terminated or silanol-terminated polydialkylsiloxane. The non-reactive silicone oil may have a viscosity of 10 to 30,000 cSt (10 to 30,000 mmHg). 2 / s), 20 to 5,000cSt (20 to 5,000mm 2 / s), 50 to 1,000cSt (50 to 1,000mm 2 / s), or 50 to 350 cSt (50 to 350 mm 2 / s).

[0009] The base polymer and the additional base polymer may each be a vinyl-terminated polydimethylsiloxane. The base polymer and the additional base polymer may each have the following characteristics: (a) a molecular weight of 6,000 g / mol to 170,000 g / mol; (b) a 100 mm 2 / s~165,000mm 2 / s, and (c) a vinyl content of 0.01 equivalents / kg to 0.1 equivalents / kg. The silicone gel composition may comprise the base polymer and the additional base polymer in an amount of 40 to 90 weight percent, 45 to 80 weight percent, or 50 to 65 weight percent.

[0010] The crosslinker may have >2 or <10 Si-H hydride moieties per molecule. The crosslinker may have 3 or 4 Si-H hydride moieties per molecule. The crosslinker may be selected from the group consisting of tetrakis(dimethylsiloxy)silane, methyltris(dimethylsiloxy)silane, phenyltris(dimethylsiloxy)silane, and combinations thereof.

[0011] The chain extender may have two Si-H hydride moieties per molecule. In the silicone gel composition, the mole fraction of hydride (MFHC) present as a crosslinker may be from about 0.2 to about 0.5, or from about 0.3 to about 0.4. In the silicone gel composition, the hydride-to-vinyl ratio may be from about 0.8 to 1.0.

[0012] The chain extender may be a hydride containing polydimethylsiloxane, a hydride terminated polydimethylsiloxane, a hydride terminated polyphenylmethylsiloxane, a hydride terminated polydiphenylsiloxane, a functionalized hydride terminated silicone, and combinations thereof.

[0013] The catalyst may be selected from the group consisting of platinum and rhodium chloride complexes complexed with divinyltetramethyldisiloxane.

[0014] The weight percentage ratio of the first set of ingredients to the second set of ingredients may be approximately 47.5:52.5 to 52.5:47.5, 49:51 to 51:49, or about 50:50.

[0015] The weight ratio of the first set of ingredients to the second set of ingredients may be approximately 1.10:1.0 to 1.0:1.10, 1.05:1.0 to 1.0:1.05, or about 1:1.

[0016] The extended silicone gels of the present disclosure after being compressed at 70°C for at least 56 days exhibit a compression set of <12%, <10%, <5%, or <4%, or 0-12%, 0-5%, or 0-4%, after a 24 hour recovery period at room temperature.

[0017] The extensible silicone gels of the present disclosure, after being compressed at 70°C for at least 56 days, exhibit a compression set of <20%, <15%, or <12%, or 0-20%, 2-20%, or 4-12%, after a 5 minute recovery time at room temperature.

[0018] The silicone gel has the following properties: (a) a hardness of 50g to 200g or 60g to 150g, (b) a stress relaxation of 40% to 60% when the gel undergoes a deformation of 50% of its original size, (c) a compression set of 2% to 20% after subjecting the gel to a 50% strain for 1000 hours at 70°C, (d) a compression set recovery of 12% or less after 5 minutes, (e) an oil bleed-out of 15% or less after being placed under a compression of 1.2 atmospheres at 70°C for 21 days, and (f) a H of 80g to 120g. 60s hardness, (g) a residual indentation hardness in the range of 20 g to 150 g; (h) a compression set of less than 10% after a recovery time of 30 minutes, 20 minutes, or 10 minutes; and (i) an elongation at break of at least 500%. (j) 0.5 cm 3 It may exhibit one or more of the following: resistance to extrusion with a measured volume of less than 20% or 15% oil bleed-out after 21 days at 120 kPa.

[0019] A silicone gel is provided that is prepared from a silicone gel composition that includes a base polymer having vinyl-silicone groups, a catalyst, a crosslinker, and a non-reactive silicone oil, and the silicone gel composition may further include a chain extender.

[0020] The non-reactive silicone oil may be a trimethylsiloxy-terminated or silanol-terminated polydialkylsiloxane. The non-reactive silicone oil may be a trimethylsiloxy-terminated polydimethylsiloxane. The non-reactive silicone oil may have a viscosity of about 10 to 30,000 cSt (10 to 30,000 mmHg). 2 / sec), 20~5,000cSt(20~5,000mm 2 / sec), 50~1,000cSt(50~1,000mm 2 / sec), or 50 to 350cSt (50 to 350mm 2The silicone gel composition may have a viscosity of about 10-60 wt %, 20-55 wt %, or 30-50 wt % of a non-reactive silicone oil. The base polymer and the additional base polymer may each be a vinyl-terminated polydimethylsiloxane. The base polymer and the additional base polymer may each have the following characteristics: (a) a molecular weight of 6,000 g / mol to 170,000 g / mol; (b) a viscosity of 100 mm 2 / s~165,000mm 2 / s, and (c) a vinyl content of 0.01 equivalents / kg to 0.1 equivalents / kg.

[0021] A closure or interconnect system comprising the silicone gel provided herein is provided, which is capable of sealing and resealing to a pressure of 20 kPa within 5 minutes of being opened or closed.

[0022] A sealant is provided for use in enclosures to seal cable entry / exit locations, the sealant having a residual indentation hardness in the range of 20g to 150g, a compression set of less than 10% after a recovery time of 30 minutes, 20 minutes, or 10 minutes, an elongation to failure of at least 500%, and a compressibility of at least 0.5cm. 3 The sealant material includes a sealant material having a resistance to extrusion with a measured volume of less than 20% or 15% oil bleed-out after 21 days at 120 kPa. The sealant material may be a thermosetting material. The sealant may be a silicone gel prepared from a silicone gel composition including a base polymer having vinyl-silicone groups, a catalyst, a crosslinker, a chain extender, and a non-reactive silicone oil. [Brief explanation of the drawings]

[0023] [Figure 1]Figure 1 shows a graph of compression set versus recovery time for silicone gels of the present disclosure having three different hardness values: 80g (A), 100g (B), or 120g (C). Each of the three gels exhibits a rapid recovery of compression set of 10% or less within 5 minutes and 5% or less within 30 minutes. Closures made using prior art silicone dry gel formulations failed this test, typically requiring up to 2 hours to reseal to a pressure of 20 kPa after opening and closing. [Figure 2] Figure 1 shows oil bleed graphs for silicone oil gels with 40% by volume of 50 cSt (A), 350 cSt (B), 1000 cSt (C), and 5000 cSt (D) non-reactive PDMS silicone extending oil at 70°C and 120 kPa for at least 37 days. Silicone Gels A, B, and C each exhibited 15% or less by weight oil bleed out up to 21 days and 20% or less by weight oil bleed out up to 35 days. [Figure 3] 1 shows a graph of a theoretically expressed stoichiometric curve comparing the mole fraction of hydride content (MFHC) in the crosslinker and the hardness of the silicone gel as a function of the hydride / vinyl ratio (H / V). [Figure 4] Photographs of an extrusion resistance test apparatus are shown in which extensible silicone gels containing 40% 50 cSt silicone oil with a target hardness of 80 g or 120 g exhibited gel bubbles of approximately 7 mm diameter (approximately 5-6 mm protruding from the device) or approximately 4 mm diameter (approximately 2-3 mm protruding from the device) at 70°C for 1 week (168 hours) and under 25 psi pressure, respectively. DETAILED DESCRIPTION OF THE INVENTION

[0024] Compositions and methods are provided for preparing silicone gels suitable for use as sealants in closures and interconnection systems. The silicone gels seal and reseal quickly (within minutes) after closure. In contrast to prior art silicone dry gels, the silicone gels of the present disclosure exhibit rapid recovery of compression set of 10% or less within 5 minutes and 5% or less within 30 minutes.

[0025] In certain implementations, sealant materials for use in applications of the type disclosed herein include hydrosilation-cured vinyl-terminated polydimethylsiloxane (PDMS) gels. Additional information regarding such gels can be found in U.S. Pat. No. 8,642,891, the disclosure of which is incorporated herein by reference in its entirety. In one example, the gel can be made by reacting a crosslinker, a chain extender, and vinyl-terminated polydimethylsiloxane (PDMS). In other implementations, sealant materials for use in applications of the type disclosed herein include hydrosilation-cured vinyl-terminated polydimethylsiloxane (PDMS) gels. In other implementations, sealant materials for use in applications of the type disclosed herein include moisture (and / or UV)-cured PDMS gels (various terminations, including silanols, are possible). In other implementations, sealant materials for use in applications of the type disclosed herein include moisture (and / or UV)-cured, silylated polyether (commonly referred to as "MS polymer") gels. In certain implementations, the gel material comprises a polyether or polyester-based polyurethane gel. In other implementations, the sealant material for use in the types of applications disclosed herein comprises a chemically crosslinked polyacrylate (acrylic or methacrylic), such as n-butyl acrylate or ethyl-hexyl acrylate with triethylene glycol dimethacrylate. In other implementations, the sealant material for use in the types of applications disclosed herein comprises an ionically or chemically crosslinked rubber gel. In other implementations, the sealant material for use in the types of applications disclosed herein comprises a chemically crosslinked styrene-butadiene-styrene (SBS) family thermoplastic elastomer (TPE) gel (crosslinking of only the polystyrene phase). In other implementations, the sealant material for use in the types of applications disclosed herein comprises a physically crosslinked triblock polyacrylate gel (e.g., Kurarity®).In other implementations, sealant materials for use in applications of the type disclosed herein include physically crosslinked triblock olefin gels (e.g., injections). In other implementations, sealant materials for use in applications of the type disclosed herein include hybrids and / or multiple combinations of the above chemistries.

[0026] A silicone gel composition is provided for preparing a silicone gel for use in a hermetic closure or interconnect system.

[0027] As used herein, terms such as "typically" are not intended to limit the scope of the claims or to imply that a particular feature is critical, essential, or even essential to the structure or function of the claimed invention. Rather, these terms are merely intended to highlight alternative or additional features that may or may not be utilized in a particular embodiment of the invention.

[0028] As used herein, the terms "comprise," "include," "having," "have," "contain," and variations thereof are intended to be open-ended transitional phrases, terms, or words that do not preclude the possibility of additional acts or structures.

[0029] Any concentration range, percentage range, or ratio range recited herein should be understood to include any integer and fraction thereof within that range, e.g., tenths and hundredths of integers, etc., unless otherwise indicated. Also, any numerical range recited herein with respect to any physical characteristic should be understood to include any integer within the recited range, unless otherwise indicated.

[0030] As used above and elsewhere in this specification, the terms "a" and "an" refer to "one or more" of the listed components. For example, "a" polymer refers to one polymer or a mixture containing two or more polymers.

[0031] As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0032] As used herein, the term "about" means within 10% of a given value, 10% more than a given amount, or 10% less than a given amount, or both.

[0033] As used herein, the term "composition" refers to one or more of a compound, a mixture, a blend, an alloy, a polymer, and / or a copolymer.

[0034] Unless otherwise specified, the term "room temperature" is defined as 15-25°C.

[0035] The term "centiStokes" (mm 2 / s, cSt) can be used as a measure of kinematic viscosity. Viscosity is a measure of the resistance to flow of a fluid. Kinematic viscosity differs from viscosity in that it is a measure of the volumetric flow rate of a liquid, defined as Stokes (St). Stokes is the flow rate per cm 2 / s or 10 -4 m 2 / s. Centistokes, cSt = 0.01 St = 1 mm 2 / s. The kinematic viscosity of a liquid (in Stokes) can be converted to viscosity (in poise) by multiplying by the density of the fluid. Unless otherwise specified, viscosity values ​​reported herein (in cSt or mm 2 / s) is the value of kinematic viscosity measured at 25°C. Dynamic viscosity and density can be measured by ASTM D7042 test method. Kinematic viscosity values ​​reported herein can be ±10% for fluids ≤ 100,000 cSt and ±15% for fluids > 100,000 cSt.

[0036] The term "centipoise" (10 -3 N s / m 2 , cSt) can be used as a measure of absolute viscosity. A perfect or ideal fluid has no resistance to shear and zero consistency. Consistency is the resistance of a real fluid to deformation. Viscosity measures area times force per unit time. The unit of viscosity is poise (p) = 1 g / (cm)(s), which is a measure of the mass flow rate of a liquid. 1 poise is equivalent to 0.1 Pa.s in SI units. The conversion from absolute (dynamic) viscosity to kinematic viscosity depends on the fluid density. Values ​​from 1 to 200,000 cSt can be analogous to cP for fluids with densities like water, or cP for fluids with a specific gravity of 1.

[0037] As provided herein, ranges are intended to include at least the numbers defining the boundaries of the range.

[0038] Unless otherwise specified, % values ​​refer to % by weight.

[0039] Furthermore, as used herein, it will be understood that the terms "comprises" and / or "comprising" specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. Unless otherwise defined, all terms, including technical and scientific terms, used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. In the event of conflicting terms, the present specification will control. All patents, patent applications, and publications referenced herein are incorporated by reference in their entirety.

[0040] As used herein, the term "silicone gel" refers to a chemically crosslinked polymer with an Si-O backbone. In contrast to carbon-based polymers, the crosslinked silicone polymer in silicone dry gel is based on an Si-O backbone. The properties of silicon and oxygen give the crosslinked polymer its excellent properties. For example, silicon forms a stable tetrahedral structure, and the silicon-oxygen bond is relatively strong, resulting in a silicone gel with high heat resistance. Furthermore, crosslinked Si-O polymers have relatively high chain flexibility and a low rotational energy barrier.

[0041] As used herein, the term "silicone oil gel" may refer to a silicone gel having a chemically crosslinked polymer with an Si-O backbone and containing an amount of added non-reactive diluent liquid, such as silicone oil or mineral oil.

[0042] As used herein, the term "silicone dry gel" may refer to a chemically crosslinked polymer having a Si-O backbone and containing relatively little or no added diluent liquid, such as silicone oil or mineral oil.

[0043] Closure systems are used to protect internal components from degradation caused by the external environment. For example, internal components such as fiber optic cables and copper cables are often encapsulated in closure systems. Other closure systems are commercially available for use with communications and energy transmission cables. Closure systems typically include internal components such as fiber organizers, cable seals and termination devices, drop cable seals that accommodate multiple drops with drop cable termination devices, and universal splice holders that accommodate multiple splices. These internal components can be affected by environmental factors such as changing humidity levels, heat and cold, and exposure to other chemicals. Closure systems are preferably protected from damage with some type of sealant.

[0044] Sealants are often used in closure systems for thermal insulation and protection against water, corrosion, and environmental degradation, as well as thermal management. Suitable sealant or closure systems can include thermoplastic gels or thermosetting gels. Thermosetting gels, such as silicone gels or polyurethane gels, can be used in closure systems. Thermosetting gels can be produced by chemical crosslinking.

[0045] The silicone gel of the present disclosure can be prepared according to several different polymerization reactions by further adding non-reactive silicone oil. The polymerization reaction can be a hydrosilylation reaction, also called a hydrosilation reaction. The hydrosilylation reaction can utilize a platinum catalyst, while other embodiments utilize radicals. In further embodiments, the silicone gel is prepared by a dehydrogenation coupling reaction. In other embodiments, the silicone gel is prepared by a condensation cure RTV reaction.

[0046] Silicone gels can be made by reacting at least a crosslinker, a chain extender, and a base polymer (e.g., vinyl-terminated polydimethylsiloxane) in the presence of a non-reactive silicone oil. A catalyst may be included to speed the reaction. In additional embodiments, an inhibitor may be used to slow the reaction rate. Exemplary components of silicone gels, their resulting properties, and their end uses are described in more detail below.

[0047] Silicone gels may be made by addition cure or platinum cure reaction mechanisms. In some embodiments, the mechanism employs the use of a catalyst. The use of a catalyst reduces the activation energy of the reaction, allowing faster cure times to be achieved at lower temperatures. A summary of the platinum cure reaction mechanism is shown below in (I). [ka]

[0048] To enable the reaction in (I), two functional groups must react with each other. In certain embodiments, the two functionalities are (1) an Si-H group and (2) an Si-vinyl group. These two functionalities can be provided by (1) the base polymer, (2) the crosslinker, and (3) the chain extender.

[0049] Base Polymer The Si-vinyl groups may be provided by a base polymer such as vinyl-terminated polydimethylsiloxane (also referred to as V-PDMS), shown below in (II): In this example, the base polymer compound contains a vinyl group at each end of the compound. [ka]

[0050] The molecular weight of the base polymer can be controlled via anionic ring-opening polymerization of cyclic siloxanes in the presence of alkali metal hydroxides of volatile bases (e.g., tetramethylammonium silanolate). End-capping of PDMS with vinyl groups may be required, so these groups are added to the polymerization mixture. V-PDMS can be used with chain extenders to determine the molecular weight between different crosslink sites.

[0051] Vinyl-containing base polymers, such as V-PDMS, can have varying viscosities that affect the resulting silicone gel. Generally, higher molecular weight V-PDMS can produce uncured gels with higher viscosities. In certain embodiments, lower molecular weight V-PDMS can improve processability.

[0052] The V-PDMS used in the silicone gel has a viscosity of approximately 100 to 165,000 cSt (100 to 165,000 mm 2 / s), approximately 1000 to 100,000 cSt (1000 to 100,000 mm 2 / s), approximately 1000cSt to 60,000cSt (1000 to 60,000mm 2 / s), approximately 3000cSt to 7000cSt (3000 to 7000mm 2 / s), or approximately 4500cSt to 5500cSt (4500 to 5500mm 2 / s).

[0053] The vinyl-terminated polydimethylsiloxane may have an average molecular weight of about 6,000 g / mol to about 170,000 g / mol, about 28,000 g / mol to about 72,000 g / mol, and the vinyl-terminated polydimethylsiloxane may have an average molecular weight of approximately 49,500 g / mol.

[0054] The base polymer may contain approximately 1-10 moles of vinyl per 500,000 g / mol of V-PDMS. In one embodiment, the base polymer contains approximately 2 moles of vinyl per mole of V-PDMS. In yet other embodiments, the vinyl content of the V-PDMS is approximately 0.01-0.1 equivalents / kg, or approximately 0.036-0.07 equivalents / kg, or approximately 0.04-0.05 equivalents / kg.

[0055] The base polymer may be a vinyl-containing polydialkylsiloxane, polyalkylarylsiloxane, or polydiallylsiloxane, including vinyl polymers and copolymers. For example, the vinyl-containing base polymer may contain any of the following monomers: dimethyl, diethyl, vinylmethyl, diphenyl, phenylmethyl, trifluoropropylmethyl, nonafluorohexamethyl, dimethoxy, and diethoxy. In addition to divinyl-terminated base polymers, alpha-vinyl, omega-hydride-terminated polymers can be used as a substantial portion of the gel polymer.

[0056] The amount of base polymer in the silicone gel composition can be 40 to 90% by weight, 45 to 80% by weight, or 50 to 65% by weight.

[0057] Crosslinking agent The Si-H end groups for the reaction in (I) may be provided by a crosslinker and / or a chain extender. The crosslinker can form connections between vinyl-terminated polydimethylsiloxane chains. In certain embodiments, the crosslinker contains electronegative substituents such as alkylsiloxy or chlorine. In some embodiments, the crosslinker can have three or more Si-H groups, which can form connection points between three or four different vinyl-terminated polydimethylsiloxane chains, respectively. The crosslinker may have four Si-H groups. For example, the crosslinker may be tetrakis(dimethylsiloxy)silane or 1,3-diphenyltetrakis(dimethylsiloxy)disiloxane, shown below in (IIIa). In other embodiments, the crosslinker may contain three Si-H hydride groups, for example, the crosslinker may be methyltris(dimethylsiloxy)silane or phenyltris(dimethylsiloxy)silane, shown below in (IIIb). Other crosslinkers can also be used. Although more highly functional crosslinkers can be used, these crosslinkers form less defined polymer structures. [ka]

[0058] Preferred crosslinkers include Gelest SIT 7278 tetrakisdimethylsiloxysilane and Gelest SIP 6826, phenyltrisdimethylsiloxysilane, although other hydride-based crosslinkers may also be used. For example, the crosslinker may include phenyltris(dimethylsiloxy)silane (e.g., CAS 18027-45-7) to improve the tear resistance of the silicone gel.

[0059] Alternative multifunctional vinyl crosslinkers can be used to reduce the steepness of the hardness ratio curve. The advantage of multifunctional vinyl crosslinkers is that they can be placed on both the A and B sides because they do not react with the hydride on the B side without a platinum catalyst. The ability to place a portion of the multifunctional vinyl compound on the B and / or A side allows the A to B ratio to remain close to 1.00-1.00 at various hardness values, effectively flattening the hardness-to-B curve. Alternative crosslinkers can consist of any multifunctional vinyl compound, such as a bis(divinyl)-terminated polydimethylsiloxane, such as Gelest DMS-VD11.

[0060] Chain extender In addition to the crosslinker, Si-H end groups may be provided by, for example, a chain extender, where both ends of the chain extender compound are terminated with Si-H groups. Any difunctional Si-H molecule with good solubility in the base vinyl may be suitable as a chain extender. For example, the chain extender may be a hydride-terminated PDMS. Practically speaking, below a certain molecular weight, dihydrides may become too volatile. Chain extenders of about 400-500 g / mol, or even about 450 g / mol or higher, may be used. Higher molecular weight dihydrides may also be used. For example, dihydrides of similar molecular weight up to the upper end of the base polymer MW range can be used, with some adjustments made to account for the resulting difference in molecular weight between crosslinks. For the purpose of increasing the molecular weight between crosslinks, a chain extender (dihydride-functional molecule, F=2) may be used when a low-viscosity, low-molecular-weight base polymer is used. When a high-molecular-weight base polymer (e.g., >80 kJ / mol) is used, a chain extender may not be necessary.

[0061] In certain embodiments, the chain extender contains reactive groups that are compatible with and willing to react with vinyl groups in the base polymer. Similar to crosslinkers, these groups are Si-H groups capable of reacting in a hydrosilylation reaction. Chain extenders typically contain two functional groups, but chain extenders may contain three or more functional groups so that the chain extender functions as a branching agent. The functional groups may be the same as or different from each other. The functional groups may also be the same as or different from the functional groups of the first and / or second components.

[0062] The chain extender may be any chain extender known in the art. In one embodiment, the chain extender is a hydride-containing polydimethylsiloxane. In another embodiment, the chain extender may be a hydride-terminated polydimethylsiloxane, as shown in (IV) below. [ka]

[0063] The chain extender may be a hydride-terminated polyphenylmethylsiloxane. In another embodiment, the chain extender is a hydride-terminated polydiphenylsiloxane. In yet another embodiment, the chain extender is a dihydride-containing siloxane. For example, the chain extender may be a hydride-terminated PDMS having an average molecular weight of about 400 to about 62,700 g / mol, or about 400 to 500 g / mol, about 600 to 700 g / mol, about 1000 to 1100 g / mol, about 4000 to 5000 g / mol, about 17,200 g / mol, about 28,000 g / mol, or about 62,700 g / mol. The chain extender may have a high or low molecular weight. The chain extender may also be branched or unbranched. In another embodiment, the chain extender is a high molecular weight polydimethylsiloxane. In another embodiment, the chain extender is a low molecular weight polydimethylsiloxane with a MW of 400-500 g / mol.

[0064] Considering the full range of vinyl-based polymers, the total dihydride content (based on the reference molecule) can be as high as 15-20%, and this is for a 100 cSt vinyl-based polymer. For vinyl-based polymers above about 40 kJ / cSt, the dihydride (chain extender) content can be very low, approaching 0%. In some embodiments, the silicone gel composition can be used with even 0% chain extender.

[0065] Optionally, an alkoxy-functionalized siloxane can be included. Suitable alkoxy-functionalized siloxanes include polydiethoxysiloxane, tetraethoxysilane, tetramethoxysilane, and polydimethoxysiloxane (DMS). In other embodiments, the chain extender may be fluorosilicone, phenylsilicone, or branched diethylsilicone.

[0066] In certain embodiments, the V-PDMS base polymer can be made shorter by utilizing a chain extender molecule, since the H-PDMS chain extender extends the V-PDMS base polymer chain in situ between two crosslinker compounds. Using this mechanism, shorter V-PDMS chain lengths can be applied, resulting in lower viscosities and compounds that are easier to work with. Therefore, unlike peroxide-activated curing reaction mechanisms, lower viscosity base polymer compounds can be used. For example, peroxide-activated curing mechanisms require a viscosity of approximately 2,000,000 cSt (2,000,000 mm). 2 / s), whereas the platinum hardening mechanism uses polymer chains with a viscosity of about 5,000 cSt (5,000 mm 2 This allows the use of a base polymer chain (V-PDMS) with a viscosity of 0.05 kJ / s.

[0067] MFHC ratio and H / V ratio The amount of crosslinker and chain extender providing the hydride component can vary. In certain embodiments, the amount of hydride in the gel may be defined in terms of the mole fraction of hydride present as a crosslinker (MFHC). For example, an MFHC value of 0.3 or 30% means that 30% of the hydride present in the system is part of the crosslinker, with the remaining 70% provided by the chain extender. In certain embodiments, the MFHC ratio may be altered to adjust the firmness of the gel (i.e., increasing the MFHC can increase the firmness). In certain embodiments, the MFHC value may be greater than 0.2, 0.3, 0.4, or 0.5. In some embodiments, the MFHC value is between 0.2 and 0.5. In other embodiments, the MFHC value is between 0.3 and 0.4.

[0068] The overall amount of hydride components in the gel can also vary. The ratio of hydride to vinyl components (e.g., provided by the base polymer) can be defined as "H / V." In other words, H / V is the total moles of hydride (e.g., contributions from crosslinkers and chain extenders) divided by the number of moles of vinyl from the base polymer (e.g., V-PDMS) present. In certain embodiments, silicone gels can have H / V ratios of 0.5-1.0, 0.6-1.0, 0.7-1.0, 0.8-1.0, or 0.9-1.0. When the H / V ratio is greater than 1, this means that there are more hydride groups than vinyl groups in the system. Theoretically, silicone gels have a maximum hardness when the H / V ratio is 1 (this is the theoretical point at which all groups have reacted with each other). However, in practice, this is not always the case, and the maximum value lies near H / V equal to 1.

[0069] The target hardness of the gel can be adjusted by adjusting the stoichiometry of the combination of components A (PDMS vinyl groups) and B (hydride groups from the crosslinker and extender chains). Figure 3 shows a theoretical representation of the relationship between silicone gel hardness and the H / V ratio. In certain embodiments, the region of interest (ROI) of the silicone gel contains slightly fewer hydride groups than vinyl groups (i.e., an H / V value less than, but close to, 1). This is because gels with an H / V value greater than 1 may undergo undesirable post-cure after the gel has cured. With the help of the stoichiometric curve shown in Figure 3, the relationship between the amount of hydride groups and the amount of vinyl can be calculated to obtain a specific hardness. This value can be used to obtain the various amounts of reagents needed to create a gel with the desired hardness. By adding non-reactive silicone oil, the amount of crosslinker and / or chain extender can be increased slightly from the calculated hydride-to-vinyl ratio to achieve the target hardness.

[0070] The reaction scheme is illustrated in (V) below, where the crosslinker compound is represented by a "+", the chain extender compound is represented by an "=", and the base polymer V-PDMS compound is represented by a "-". In certain embodiments, the chain extender must always connect two different base polymer compounds, or connect to one base polymer and terminate the chain at the opposite end. [ka]

[0071] In certain embodiments, an addition cure catalyst is used to assist the reaction of the base polymer, crosslinker, and chain extender. Carrying out the reaction without a catalyst is typically a very energy-intensive process. Temperatures of 300°C or higher may be required to avoid the resulting gel having poor and inconsistent mechanical properties.

[0072] The catalyst may comprise a Group VIII metal. In another embodiment, the catalyst comprises platinum. Platinum catalysts can be prepared according to methods disclosed in the art, for example, Lewis, Platinum Metals Rev., 1997, 41, (2), 66-75, and U.S. Pat. No. 6,030,919, which are incorporated herein by reference. In another embodiment, the catalyst is a homogeneous catalyst. In another embodiment, the catalyst is a heterogeneous catalyst. Examples of heterogeneous catalysts include platinum coated on carbon or alumina.

[0073] The catalyst may be "Karstedt's catalyst," which is a platinum catalyst made of Pt complexed with divinyltetramethyldisiloxane, shown below in (VI). [ka]

[0074] The advantage of this catalyst is the fact that no heterogeneous reaction occurs, but the catalyst forms a colloid. The advantage of these catalysts is the fact that only small amounts (ppm level) are needed, which reduces the cost of the polymerization process.

[0075] The catalyst may be a rhodium chloride complex, such as tris(triphenylphosphine)rhodium chloride ("Wilkinson's catalyst"). Rhodium-based catalysts may require higher concentrations and higher reaction temperatures for most success. However, poisoning occurs along with the reaction, and thus rhodium-based catalysts may be less susceptible to poisoning than platinum catalysts.

[0076] The catalyst may be a carbonyl derivative of iron, cobalt, or nickel. For example, the catalyst may be dicobalt octacarbonyl CO2(CO)8. High temperatures (e.g., >60°C) should be avoided to prevent decomposition and deactivation of the catalyst. Here, compared to Pt catalysts, 10 -6 For M or ppm levels of Pt, 10 -3M is required. Also, the reaction is about five times slower.

[0077] The catalytic reaction mechanism may be a Lewis mechanism. First, oxygen coordinates to the catalyst in the presence of a crosslinker or chain extender. This step is called the induction period. This yields hydrogen and platinum colloid. Next, the chain extender or crosslinker precedes attack of the vinyl group, forming an electrophilic complex. The vinyl group (V-PDMS) then acts as a nucleophile. Combining the vinyl group of the V-PDMS chain with the crosslinker or chain extender attached to the Pt-catalyst yields the silicone product. The hydride transfers to the second carbon of the vinyl group. The Pt colloid is then available for the second reaction. Because oxygen is not consumed in this reaction and OO is not destroyed in the reaction sequence, oxygen can be viewed as a cocatalyst.

[0078] Catalysts must be separated from compounds that are toxic or potentially harmful to the catalyst's performance. For example, amines, thiols, and phosphates can all poison catalysts, such as platinum-containing catalysts. Amines, thiols, and phosphates can form very stable complexes with the catalyst, slowing or completely stopping the reaction.

[0079] inhibitors In certain embodiments, inhibitors are added to silicone gel formulations to slow the curing process, which allows more time to work with the polymer mixture during processing, dispensing, and molding.

[0080] The inhibitor can bind to the catalyst and form a stable complex. By doing so, the Pt catalyst is deactivated. When the complex is activated by adding energy (raising the temperature), the inhibitor will lose its bond to the Pt catalyst. The Pt catalyst then returns to its activated form and can initiate the polymerization reaction. The inhibitor can help manipulate the gel before it fully cures, extending its pot life. In certain embodiments, the pot life can be approximately 1 hour at room temperature and 6-8 hours at 3°C.

[0081] In certain embodiments, the inhibitor contains two electron-rich groups (alcohol and allylic functions) that form an acetylenic alcohol. These groups can interact with the catalyst and shield it from other reactive groups. The inhibitor for the Pt-catalyst may be 3,5-dimethyl-1-hexyn-3-ol, shown below in (VII). [ka]

[0082] Silicone gel compositions may contain additional common ingredients. For example, the compositions may include additives such as flame retardants, colorants, adhesion promoters, stabilizers, fillers, dispersants, flow improvers, plasticizers, slip agents, toughening agents, and combinations thereof. In certain embodiments, the additional additives may include at least one material selected from the group consisting of ethyl polysilicate (Dynasylan 40), diphenylsiloxane-dimethylsiloxane copolymer (PDM1922), 1,2-bis(3,5-di-tert-butyl-4-hydroxyhydrocinnamoly)hydrazine (Songnox 1024), Kingnox 76, DHT-4A, Kingsorb, pigments, and mixtures thereof. In some embodiments, the additives comprise 0.1 to 25% by weight of the total composition, 0.1 to 5% by weight of the total composition, 0.1 to 2% by weight of the total composition, or 0.1 to 1% by weight of the total composition.

[0083] To improve tear strength, silicone gels may be optionally reinforced by incorporating silica (SiO2) reinforcing materials into their structure. The silica reinforcing materials may be fumed silica, precipitated silica, or structurally modified silica reinforcing materials. Silica reinforcing materials may be used in silicone gels in amounts ranging from 0 to 30 wt%, 1 to 25 wt%, or 5 to 20 wt%. For example, hydrophobic fumed silica may be used to improve physical properties. Hydrophilic fumed silica may be used to modify the viscosity of the components to create shear-thinning behavior. Typical amounts of fumed silica may be about 0 to 30 wt%, 10 to 25 wt%, or 2 to 20 wt%. For example, structurally modified silica (e.g., silane-modified fumed silica, e.g., Aerosil® 8200) may be used to improve tear strength, for example, in amounts ranging from 0 to 30 wt%, 5 to 25 wt%, or 10 to 20 wt%.

[0084] In some embodiments, the compositions disclosed herein and according to the methods disclosed herein include a flame retardant. In particular embodiments, the flame retardant is zinc oxide. In some embodiments, the flame retardant comprises 0.1-25% by weight of the total composition, 0.1-5% by weight of the total composition, 0.1-2% by weight of the total composition, or 0.1-1% by weight of the total composition. In one embodiment, the flame retardant comprises 20% by weight of the total gel composition.

[0085] Non-reactive silicone oil The silicone gel composition may contain a non-reactive silicone oil fluid in the first and / or second component set. The non-reactive silicone oil may be an inert polydimethylsiloxane (PDMS). For example, the non-reactive silicone oil may be trimethylsiloxy-terminated PDMS or silanol-terminated PDMS (Si-OH). Other inert silicone fluids include diphenylsiloxane-dimethylsiloxane copolymer, phenylmethylsiloxane-dimethylsiloxane copolymer, phenylmethylsiloxane homopolymer, phenylmethylsiloxane-diphenylsiloxane copolymer, alkylsilicone, arylalkylsilicone, and fluorosilicone fluid. In some embodiments, the non-reactive silicone oil is trimethylsiloxy-terminated PDMS, as shown in (VIII). The non-reactive silicone oil may have a kinematic viscosity at 25°C ranging from 10 cSt to 30,000 cSt, 20 to 5,000 cSt, 50 to 1,000 cSt, or 50 to 350 cSt. The non-reactive silicone oil may be a trimethylsiloxy-terminated PDMS having a kinematic viscosity of about 50, about 100, about 200, or about 350 cSt at 25°C. [ka]

[0086] The silicone gels of the present disclosure can be prepared by incorporating 10-60%, 20-55%, or 30-50%, 35-45%, or about 40% by volume of non-reactive silicone oil fluid. The non-reactive silicone oil fluid level may distinguish the silicone gels of the present disclosure from certain prior art gels that contain approximately 65% ​​or more fluid by volume, which are much less firm and not as strong.

[0087] In some embodiments, the compositions disclosed herein and made by the disclosed methods contain at least one stabilizer, including antioxidants, acid scavengers, light and UV absorbers / stabilizers, heat stabilizers, metal deactivators, free radical scavengers, carbon black, and antifungal agents.

[0088] Preparation of silicone gel Silicone gels can be prepared by mixing a first component set together, a second component set together, and then mixing the two component sets together. A non-reactive silicone oil fluid is added to at least one of the first and / or second component sets (sides A and / or B). The first component set can include blending a base polymer (e.g., V-PDMS) with a silicone oil along with a catalyst. The second component set can include blending a crosslinker and a chain extender. The second component set can also include blending an additional base polymer, optionally a non-reactive silicone oil, and in some embodiments, an inhibitor. In some embodiments, the first and / or second component sets can also include blending at least one of the additives discussed above.

[0089] The first component set can include a base polymer, a catalyst, and optionally a non-reactive silicone oil. The amount of catalyst present in the first component set can be 0.01-1 wt%, 0.03-0.1 wt%, or approximately 0.06 wt%. The amount of base polymer in the first component set can be 40-99 wt%, 40-90 wt%, 45-80 wt%, or 50-65 wt%. When present in the first component set, the amount of non-reactive silicone oil can be 10-60 wt%, 20-55 wt%, or 30-50 wt%.

[0090] For the second component set, the starting amount of crosslinker can be 0-20 wt%, 0.001-10 wt%, 0.005-5 wt%, 0.01-1 wt%, 0.02-0.5 wt%, 0.05-0.3 wt%, or 0.075-0.125 wt%. The amount of chain extender in the second component set can be 0-15 wt%, 0.1-10 wt%, 0.5-5 wt%, 1-3 wt%, or 1.5-2.5 wt%. The amount of optional inhibitor in the second component set can be 0-1.5 wt%, 0.01-1 wt%, or 0.03-0.5 wt%. The amount of base polymer in the second component set can be 40-99 wt%, 40-90 wt%, 45-80 wt%, or 50-65 wt%. When present in the second set of ingredients, the amount of non-reactive silicone oil can be 10 to 60 wt %, 20 to 55 wt %, or 30 to 50 wt %.

[0091] The amount of the crosslinker and chain extender combination in the overall silicone gel composition can be 0.01-20 wt%, 0.05-15 wt%, 0.08-10 wt%, 0.1-5 wt%, 0.5-3 wt%, or approximately 1.25 wt%. The amount of base polymer in the overall silicone gel composition can be 40-90 wt%, 45-80 wt%, or 50-65 wt%. The amount of non-reactive silicone oil in the overall silicone gel composition can be 10-60 wt%, 20-55 wt%, or 30-50 wt%.

[0092] The non-reactive silicone oil can be added to the first and second component sets equally, unevenly on both sides, or only on one side. In one embodiment, the oil is added equally on both sides.

[0093] Hardeners, or curing agents, are polyhydride-functional molecules or blends of polyhydride-functional molecules, any of which may or may not contain inhibitors (this is simply a processing concern). Polyhydride molecules (F>2 with Si-H functionality) are used to effect crosslinking and create elasticity and hardness. Generally, polyhydride crosslinkers are used with F<10, most preferably F=4 or 3. The amount of curing agent required varies based on vinyl content, oil content, and other factors. Chain extenders (dihydride-functional molecules, F=2) may be used when low-viscosity, low-molecular-weight base polymers are used, in part to increase the molecular weight between crosslinks. When using high-molecular-weight (e.g., >80 kG / mol) base polymers, chain extenders may not be strictly required. Inhibitors may be used when longer working times are required for processing the A+B mixture.

[0094] Silicone gels can be prepared by blending a first component set with a second component set. In one embodiment, the weight ratio of the blend of the first component set to the second component set is approximately 1:1. In another embodiment, the weight ratio of the blend is approximately 47.5:52.5 to 52.5:47.5. Small adjustments to the ratio can result in significant differences in the overall hardness of the silicone gel. For example, in certain embodiments, when the ratio between the first component set and the second component set is 52.5:47.5 (the second component set includes V-PDMS, a crosslinker, a chain extender, and an inhibitor), the hardness can be lower than the hardness of the same composition at a 1:1 blend ratio. Furthermore, in certain embodiments, when the ratio between the first component set and the second component set is 47.5:52.5, the hardness can be greater than the hardness of the same composition at a 1:1 blend ratio. In one example, the hardness may be approximately 72 g for a 52.5:47.5 ratio, 140 g for a 1:1 ratio, and about 210 g for a 47.5:52.5 ratio. In other words, a 2.5% variation can affect the hardness of the gel by as much as 70 g. Therefore, it is preferred that weighing procedures during the preparation of the gel composition be performed with high precision.

[0095] Silicone Gel Uses and Properties The silicone gels described herein can be used in many end uses due to their improved properties, such as improved behavior under mechanical stress (e.g., vibration and impact), or the ability to seal uneven or complex structures (due to their ability to flow and conform to the area of ​​the structure), and reduced compression set recovery time (the ability to seal quickly upon closure). In certain embodiments, the silicone gels can be used in interconnect, cover, or closure systems. In particular, the silicone gels can be used in fiber optic closures, electrical sealants, or electrical closures. In some embodiments, the silicone gels are used as gel wraps, clamshells, or gel caps. In further embodiments, the silicone gels are used inside a residence. In other embodiments, the silicone gels can be used outside a residence. The use of silicone gels in closures or interconnect systems can potentially reduce the number of components, frame size, or cost over other sealing mechanisms.

[0096] The silicone gel can be used as a flame retardant sealant. In one embodiment, the silicone gel includes a flame retardant additive (e.g., zinc oxide) to function as a flame retardant sealant.

[0097] The silicone gel may be used in a closure system. In certain embodiments, the closure system includes a housing, a cable, and a silicone gel. In some embodiments, the cable may be a low smoke zero halogen (LSZH) cable.

[0098] Exemplary sealant materials may be defined by properties such as hardness, compression set, extrusion resistance, elongation at break, and oil bleed-out properties. Examples of ranges of values ​​for each property, as well as test procedures for measuring these values ​​for sample materials, are described below.

[0099] Indentation hardness The sealant material can be tested for indentation hardness using a texture analyzer that includes a load cell and a probe assembly. The load cell may be motor-driven. The load cell may be bidirectional. The probe assembly includes a stainless steel ball probe. The ball probe measures approximately 6.35 mm (0.25 inches). The load cell has a minimum resolution of 0.20 g and an FSR accuracy of ±0.5%. The load cell has a trigger point of approximately 4 g (gram force). One example of a texture analyzer suitable for hardness testing is the Brookfield CT3 Model 1500 from Brookfield Engineering Laboratories, Inc., Middleboro, Massachusetts.

[0100] During testing, the material to be tested is placed in a cup below the probe assembly. The cup is formed from aluminum. The cup is filled with 51 grams of the material to be tested. The material filling the cup is free of air bubbles. The cup has a frusto-conical interior shape with a large inner diameter of 50 millimeters at the open top end, a small inner diameter of 45 millimeters at the closed bottom end, and a depth of 30 millimeters extending between the top and bottom ends.

[0101] The load cell drives the probe assembly vertically into the material sample to a depth of 4 mm at a rate of 2 mm / sec. The load cell holds the probe assembly at the 4 mm depth for 1 hour.

[0102] Indentation hardness is measured as the peak and residual forces (in grams) applied to the probe assembly by the load cell. Peak hardness is measured immediately when the probe assembly is at a preset depth from the trigger point. Residual hardness is measured at a preset depth after a preset time has elapsed. For example, residual hardness can be measured after 1 hour (3600 seconds). In certain embodiments, the mean and standard deviation are calculated for the peak and residual force measurements. In one example, a sealing material suitable for use in gel sealing applications described herein has a residual indentation hardness in the range of 20 g (gram force) to 150 g or 50 g to 130 g after 1 hour.

[0103] Compression set The sealant material can be tested for compression set under a constant deflection in air. In certain examples, the material is tested using ASTM D395, Method B.

[0104] The material to be tested is formed into a cylindrical specimen having a diameter of about 20 mm and a height of about 20 mm.

[0105] The test is performed using an oven (e.g., air-circulating) and a compression fixture. The compression fixture includes compression plates, spacers, and components for compressing the plates. The compression plates are vertically oriented so that the compression fixture has an upper and lower compression plate. The compression plates and spacers are formed from steel. The plates have dimensions of 150 mm long x 150 mm wide x 12.5 mm high. The spacers have dimensions of 25 mm wide x 10 mm high. Each spacer has an 8 mm central hole. The components for compressing the plates include bolts and nuts. The bolts are 10 mm long.

[0106] During testing, a sample (e.g., a cylindrical sample) is placed in a compression fixture between upper and lower compression plates so that the height of the sample extends along the axis between the upper and lower plates. Nuts and bolts are tightened to move the compression plates together and compress the sample. Spacers are placed between the compression plates to limit the compression of the sample. In certain embodiments, the compression plates are moved relative to one another (e.g., the upper plate is moved toward the lower plate, the lower plate is moved toward the upper plate, or both plates are moved toward each other) until the compression plates are separated by the height of the spacers. For example, a sample may be compressed to a height of approximately 10 mm using 10 mm high steel spacers.

[0107] The compressed sample is placed in an oven at a preset temperature for a preset period of time. In certain embodiments, a compression fixture and sample are placed in the oven. The compression fixture holds the sample in a compressed state while in the oven. The compressed sample remains in the oven for a preset period of time, such as 22 hours, while the oven maintains an internal temperature of 70°C. The preset period for compression of the sample can be, for example, 22 hours, 7 days, 14 days, 21 days, or 56 days.

[0108] The heated sample and compression fixture are removed from the oven after a preset period of time. The compression fixture is allowed to cool to room temperature before opening. The upper compression plate is removed from the sample, and the sample is allowed to recover. For example, the upper compression plate can be removed from the sample by loosening or removing nuts and bolts.

[0109] The height of the sample can be measured after a preset recovery time, such as 5 minutes, 20 minutes, 30 minutes, 60 minutes, 3 hours, 24 hours, 48 ​​hours, or 100 hours. The percent compression set is calculated by the following formula:

number

[0110] In one example, a sealing material suitable for use in the gel sealing applications described herein is provided. In some embodiments, the sealing material has a compression set of less than 10% after 20 minutes of recovery, or less than 10% after 10 minutes of recovery, or less than 5% after 60 minutes of recovery, or less than 5% after 30 minutes of recovery.

[0111] In some embodiments, sealing materials are provided that exhibit a compression set in the range of 0-20%, 2-20%, 2-10%, or 12% or less, 10% or less, 5% or less, or 4% or less after a 24 hour recovery period.

[0112] In some embodiments, sealing materials are provided that exhibit a compression set in the range of 0-20%, 2-20%, 2-10%, or 12% or less, 10% or less, 5% or less, or 4% or less after a 24-hour recovery period for the sample after 22 hours, 7 days, 14 days, 21 days, or 56 days of sample compression time.

[0113] In some embodiments, sealing materials are provided that exhibit a compression set in the range of 0-10%, 0-5%, 0-4%, or 5% or less, or 4% or less after a 22 hour sample compression time and a 24 hour sample recovery time.

[0114] In some embodiments, sealing materials are provided that exhibit a compression set in the range of 0-10%, 0-5%, 0-4%, or 5% or less, or 4% or less after a 7-day sample compression time and a 24-hour sample recovery time.

[0115] Extrusion Resistance Sealant materials can be tested for extrusion resistance using an extrusion fixture, a pneumatic cylinder, and an oven (e.g., an air-circulating oven). The extrusion fixture includes a body defining an interior test chamber and an extrusion plate that selectively covers a first end of the test chamber. The test chamber is cylindrical in shape and 25 millimeters in diameter. The extrusion plate, which closes one end of the test chamber, defines a 4 mm circular opening in its center that is in fluid communication with the test chamber. An exemplary test chamber is shown in Figure 4.

[0116] The material to be tested is formed into a cylindrical specimen having a diameter of 25 mm and a height of 25 mm.

[0117] During testing, the specimen is placed in a cylindrical test chamber, the extrusion plate is placed over the first end of the test chamber, and the aluminum cup is placed outside the extrusion fixture below the circular opening.

[0118] A compression plate is positioned at the opposite second end of the test chamber, behind the specimen. The compression plate is round with a diameter of 25 mm. The compression plate is low friction and formed from plastic. A pneumatic cylinder is operably coupled to the compression plate to move the compression plate relative to the extrusion fixture. In particular, the compression rod of the pneumatic cylinder contacts the plastic compression plate.

[0119] The pneumatic cylinder is energized and pressurized so that the pneumatic cylinder exerts a pressure of 200 kPa on the sample. The pressurized sample and pneumatic cylinder are placed in a 70°C oven. Material that is not resistant to extrusion falls into the aluminum cup. Material that is resistant to extrusion bulges out of the opening in a spherical extrudate. If no part of the sample falls into the aluminum cup, after a period of time, e.g., 24 hours or 168 hours, pressure is removed from the sample. The sample is allowed to recover without pressure and return to room temperature. Once the sample has returned to room temperature, the volume (if any) that remains extruded into the outer bulge of the extrusion plate is measured. In a specific example, a suitable material may be used. 3 Less than or equal to 0.25cm3 Below or 0cm 3 The measurement volume is

[0120] Breaking elongation Sealant materials can be tested for tensile elongation using ASTM D638. For example, materials can be tested using a universal testing machine (UTM), such as the Universal Testing System from Instron, Norwood, Massachusetts. The UTM includes a 2 kg load cell and two cylindrical rods. Each cylindrical rod has a 6 mm diameter and is made of steel. The rods are horizontally oriented, with the lower rod attached to the fixed base of the UTM and the upper rod attached to the load cell. Thus, the lower rod remains stationary relative to the base, while the upper rod is movable relative to the lower rod using the load cell.

[0121] The material to be tested is cut into rings with an outer diameter of 30 mm and an inner diameter of 20 mm. The thickness of the rings is 3-4 mm.

[0122] During testing, the ring is positioned so that the upper and lower rods extend into the ring. The load cell moves at a rate of 50 mm / min. Thus, the upper rod moves away from the lower rod at that rate. As the upper rod moves, the UTM measures the force applied to the upper rod and the extension curve of the ring. From these measurements, the elongation to break is calculated. The elongation to break is calculated based on the initial length of the ring (approximately 31.5 mm). In certain embodiments, suitable materials have an elongation to break of at least 500% or 800% of the initial length of the sample.

[0123] Oil bleed out Sealant materials can be tested for oil bleed-out to determine the oil loss of the material under pressure. The material to be tested is formed into cylindrical specimens, each 14 mm in diameter and 3-4 mm thick.

[0124] The test was carried out using a test block, three coarse screens (0.16 mm 2 mesh), 3 fine screens (0.01mm 2 The test is performed using a test block (a mesh of 1000 psi), three pistons, three weights, an analytical balance, and an oven. The test block defines three test cavities with open tops. Each test cavity is sized to receive one of the cylindrical specimens through its open top. The weights are shaped to fit partially into their respective test cavities through their open tops.

[0125] During testing, the initial weight of each sample is measured. Each sample is placed on its respective fine screen. Then, the corresponding fine screen is placed on its respective coarse screen. The screens support the sample while separating out low molecular weight materials. Each sample and corresponding screen is placed into one of the cavities defined by the test block.

[0126] A respective piston is placed on top of each specimen in a respective test cavity. A respective weight is placed on top of each piston, applying a pressure of 120 kPa to each specimen. The weights are shaped so that a portion of the weight extends downward into the test cavity through the open top end. The test block, screen, specimen, piston, and weight form a test assembly. The test assembly is placed in an air-circulating oven at a temperature of 70°C.

[0127] Periodically, the test assembly is removed from the oven and the sample is removed from the test block. The sample is blotted onto cleaning paper and weighed on an analytical balance. After weighing, the sample is replaced within its respective test cavity and the weight is replaced on the sample. The test assembly is returned to the oven. These periodic intervals are repeated until at least 500 hours have elapsed or the sample weight stabilizes. In certain embodiments, the sample weight of a suitable material measured at 500 hours will be 80% or more of its initial weight (e.g., less than 20% oil bleed-out), or 85% or more of its initial weight (e.g., less than 15% oil bleed-out), or 90% or more of its initial weight (e.g., less than 10% oil bleed-out).

[0128] In some embodiments, the silicone gel may be used in a closure or interconnect system that is "compatible" with a cable, for example, a low smoke zero halogen (LSZH) cable. In certain embodiments, compatibility is measured by subjecting a sample to one or more mechanical or environmental tests and testing for specific functional requirements. In some embodiments, compatibility is measured by passing a pressure loss test, an air tightness test, and / or a visual test. In certain embodiments, the silicone gel of the closure or interconnect system is compatible.

[0129] Airtightness can be tested according to International Electrotechnical Commission (IEC) Test 61300-2-38, Method A and IEC 60068-2-17, Test Qc. In certain embodiments, airtightness is tested by immersing the specimen in a water bath and applying an internal pressure of 20-40 kPa (0.2-0.4 atmospheres) for 15 minutes. It is important to measure airtightness immediately after installing the closure at a temperature of -15°C or 45°C. It is also important to remove any air bubbles present on the outside of the closure. If a continuous flow of air bubbles is observed, this indicates that the specimen is not properly sealed and is considered a failure (i.e., non-conformance).

[0130] Pressure loss may be tested according to IEC 61300-2-38, Method B. In certain embodiments, the gel and cable are compliant if the difference in pressure before and after the test is less than 2 kPa (0.02 atmospheres).

[0131] Appearance may be tested in accordance with IEC 61330-3-1 by inspecting the product with the naked eye for defects that may adversely affect the performance of the product.

[0132] The samples may be subjected to various mechanical and / or environmental conditions before being tested for air tightness, pressure drop, appearance, etc. In certain embodiments, suitability is determined by subjecting the samples to one or more of the following mechanical tests: axial tensile test, bending test, reentry test, and torsion test, and / or one or more of environmental tests: aggressive media resistance test, stress crack resistance test, salt spray test, temperature cycle test, and waterhead test.

[0133] The specimens may be subjected to an axial tensile test in accordance with IEC 61300-2-4. In this test, the specimen may be internally pressurized and sealed at room temperature at 20 kPa (0.2 atm) or 40 kPa (0.4 atm). The base assembly is clamped, and force is applied to each extension cable individually. If the specimen has an outer diameter of 7 mm or less, the amount of force applied per cable is equal to (outer diameter / 45 mm) * 500 Newtons ("N"). This force is applied to each cable for 15 minutes, building up to the IEC 61300-2-4 test. If the specimen has an outer diameter greater than 7 mm, the amount of force applied per cable is equal to (outer diameter / 45 mm) * 1000 N, with a maximum of 1000 N applied. This force is applied for one hour. The internal pressure loss is then investigated. In certain embodiments, the gel and cable are compatible if the pressure loss is less than 2 kPa (0.02 atm). Additionally, in certain embodiments, the gel and cable are compatible if the displacement of the cable is less than 3 mm. In other embodiments, the specimen is further subjected to the air tightness test described above.

[0134] The suitability of a sample can be measured by subjecting it to a bending test in accordance with IEC 61300-2-37. In this test, the sample is subjected to temperatures of -15°C and 45°C. The sample is internally pressurized at 20 kPa or 40 kPa (0.2 atm or 0.4 atm) and sealed. The cable is bent individually at a 30-degree angle (or with a maximum force of 500 N) on either side of the neutral in the same plane. Each bending operation is held for 5 minutes. After returning the cable to its original position, the procedure is repeated in the opposite direction. After five cycles for each cable, the sample is visually inspected for appearance, conditioned at room temperature, and subjected to an airtightness test. In some embodiments, gel and LSZH cables are suitable if the specimen passes the appearance test, pressure loss test (i.e., less than 2 kPa (0.02 atmospheres)), and / or airtightness test.

[0135] The suitability of a sample can be measured by subjecting the sample to a reentry test in accordance with IEC 61300-2-33. In certain embodiments, reentry can be simulated after a temperature cycle of a specific duration. To complete this test, the closure must be removed from the cycling chamber and tested for airtightness. A reentry test can then be performed, in which a dummy plug or cable is removed from the cap and another cable or dummy plug is added. Airtightness is then measured again. If the closure again passes the airtightness test, reentry is successful.

[0136] Other mechanical tests may be used to determine compatibility. Samples may be subjected to a torsion test in accordance with IEC 61300-2-5. If, after the torsion test is completed, the sample passes the visual inspection test, the pressure loss test, and / or the air tightness test, the gel and cable may be deemed compatible.

[0137] In yet other embodiments, compatibility is measured by conducting temperature cycling or accelerated aging environmental tests based on IEC 61300-2-22 and IEC 60068-2-14, Test Nb. In one embodiment, the temperature cycling test is conducted by cycling the cable jacket between gel blocks between temperatures of -40°C and 70°C for 10 days, with two cycles between the extreme temperatures per day. In some embodiments, the humidity is not controlled, the dwell time is 4 hours, and the transition time is 2 hours. In certain embodiments, the cable jacket is tested for tensile strength, ultimate elongation, airtightness, appearance, and / or reentry retention. Also, in certain embodiments, the closure must be tested for airtightness after adjusting to room temperature for at least two hours after the temperature cycling test. Thus, in certain embodiments, the gel and cable, e.g., LSZH cable, are compatible if the test specimen passes the airtightness test.

[0138] In another embodiment, compliance is determined by subjecting the sample to tests for resistance to aggressive media according to EEC 61300-2-34, ISO 1998 / 1, and EN 590. The sample is then considered compliant if it passes the hermeticity and / or appearance tests.

[0139] In yet another embodiment, compliance is determined by subjecting a sample to a stress crack resistance test in accordance with IEC 61300-2-34. The sample is then deemed compliant if it passes an air tightness test and / or shows no visible signs of cracking.

[0140] In other embodiments, compliance is determined by subjecting the sample to a salt spray test in accordance with IEC 61300-2-36 and IEC 60068-2-11, test Ka. The sample is then deemed compliant if it passes the airtightness and / or appearance tests.

[0141] In some embodiments, compliance is determined by subjecting a sample to a water head test in accordance with IEC 61300-2-23, Method 2. If there is no water intrusion, the sample is deemed to be compliant.

[0142] One challenge in formulating a gel that behaves as described is crosslinking the gel so that it has good mechanical properties (strength and relatively high elongation) while not requiring excessive force to close the closure and making it difficult to close an opening around the round cross section of the cable. This gel property is characterized by hardness. For example, in some embodiments, the silicone gel may exhibit a hardness ranging from 26 to 53 Shore OOO, or 100 to 300 g, when measured as described herein above or according to methods known in the art. In other embodiments, the silicone gel has a hardness ranging from 26 to 42 Shore OOO, or 100 to 200 g. In other embodiments, the silicone gel has a hardness ranging from 26 to 37 Shore OOO, or 100 to 160 g. In certain embodiments, the Shore hardness scale is measured according to ISO 868 or ASTM D2240.

[0143] Hardness can also be measured with a texture analyzer, as described above. For example, the LFRA Texture Analyzer-Brookfield may include a probe assembly fixed to a motor-driven bidirectional load cell. In such a system, the probe penetrates vertically into the sample at a preset speed to a preset depth. Hardness is the amount of force required to press the probe into the test sample. For silicone gels of the present disclosure, the characteristic hardness of interest may be the force measured 60 seconds after a 6.35 mm spherical probe is pressed into the gel to a depth of 4.0 mm. H 60s , i.e., the 60-second hardness value must not exceed 350 g. 60sThe hardness range is less than 200g, with less than about 120g being most preferred. Similarly, a minimum 60s hardness of about 40g is required to obtain acceptable mechanical properties and the ability to open and reseal the closure. Silicone gels of the present disclosure may be used in hardness ranges of 40-350g, 45-300g, 50-200g, 60-150g, 70-130g, 80-120g, or 105-115g. 60s It exhibits hardness.

[0144] In some embodiments, the gel is compressed to a specific strain or deformation (e.g., in certain embodiments, up to 50% of its original size). This creates a specific stress in the material. As the material relaxes, the stress is reduced. In certain embodiments, the stress relaxation of the silicone gel can range from 30-60% when subjected to a tensile strain or deformation of approximately 50% of the gel's original size, where the stress relaxation is measured after a 1-minute hold time at 50% strain. In other embodiments, the stress relaxation of the silicone gel can range from 40-60% when subjected to a tensile strain of approximately 50%. A higher stress relaxation indicates that the gel requires less stress to seal when placed in a closure.

[0145] By way of further example, in some embodiments, the compression set measured after 50% strain at 70° C. for 1000 hours may range from 2% to 20%. In other embodiments, the compression set measured after 50% strain at 70° C. for 1000 hours may range from 2% to 10% after a 30 minute recovery time when measured according to Method B, a modified version of ASTM D395.

[0146] The compression recovery test is a measure of how quickly a gel responds after being exposed to an external stress or change in shape. Compression set recovery can be determined as described herein above for a sample that is first compressed 50% for 22 hours at 70° C., then cooled and decompressed, as shown in FIG. 1.

[0147] Prior art silicone dry gels of Berghmans et al., U.S. Patent Nos. 8,642,891 and 9,556,336, exhibit slow compression set recovery, with a compression set recovery of about 60% in 5 minutes and about 30% in 30 minutes. In contrast, Figure 1 shows a graph of compression set versus recovery time for three representative silicone gels of the present disclosure, each with three different hardness values: 80 g (A), 100 g (B), or 120 g (C). Each of the three gels exhibits a rapid compression set recovery of 10% or less within 5 minutes and 5% or less within 30 minutes.

[0148] A silicone dry gel composition is provided that includes a vinyl-containing base polymer, a crosslinker, a chain extender, and a non-reactive silicone oil. For example, the silicone gel of the present disclosure can be made from a composition that includes a divinyl-terminated polydimethylsiloxane as the base polymer, a chain extender, a crosslinker, and 10 to 60 wt. % of a non-reactive PDMS silicone fluid. The non-reactive silicone oil can be polydimethylsiloxane (PDMS), a trimethylsiloxy-terminated silicone oil fluid. Adding a chain extender and a crosslinker in addition to the non-reactive silicone fluid significantly reduced the compression set recovery of the original silicone dry gel while maintaining the same gel hardness, as disclosed in U.S. Patent Nos. 8,642,891 and 9,556,336 to Berghmans et al. While prior art silicone dry gel samples tested under similar conditions required several hours to return to a compression set of less than 10%, silicone gels prepared from the compositions of the present disclosure typically exhibited a compression set of less than 10% within approximately 30, 20, 10, or even 5 minutes for the improved formulations.

[0149] In some embodiments, silicone gels formed from compositions of the present disclosure may exhibit 15% or less oil bleed-out over a period of time, or 10% or less oil bleed-out over a period of time when the gel is under a compression of 120 kPa (1.2 atmospheres) at 70°C. In certain embodiments, oil bleed-out is measured on a wire mesh, and oil loss may exit the gel through the mesh. The weight of the gel sample is recorded before and after applying pressure. In some embodiments, the silicone gel may exhibit 15% or less oil bleed-out by weight for up to 21 days, or 20% or less oil bleed-out by weight for up to 35 days.

[0150] The silicone gels of the present disclosure can be made from a formulation including a divinyl-terminated polydimethylsiloxane as a base polymer, a chain extender, a crosslinker, and a non-reactive PDMS silicone fluid.

[0151] For high viscosity vinyl-based formulations (above 60,000 cP), chain extenders may or may not be used. A variety of crosslinking methods are possible. [Example]

[0152] Example 1. Silicone gel containing non-reactive silicone oil-PDMS fluid A silicone gel was prepared in accordance with the present disclosure as a two-part A and B composition, as shown in Table 1 below. Non-reactive silicone oil polydimethylsiloxane (PDMS), trimethylsiloxy terminated (e.g., 350 cSt viscosity, average MW 13650 g / mol) was added to both side A and side B. Sides A and B were combined, molded, and cured to form a silicone oil gel block.

[0153] [Table 1] *Increasing amounts of hydride from crosslinkers and chain extenders can be added to reach a target hardness of about 110g 1:1 while maintaining a MFHC of about 0.3-0.4.

[0154] Silicone gels were synthesized according to the variations in Table 1. A first set of components was prepared. To prepare the first set of components, a platinum catalyst complex (platinum-divinyltetramethyldisiloxane complex, 3.0% Pt in vinyl-terminated PDMS (SIP6830.3, Gelest, Inc.)) was first added to a container. Then, vinyl-terminated polydimethylsiloxane (DMS-V35, Gelest, Inc.), 5,000 cSt, average MW 49,500 g / mol, was added and combined with the catalyst in a 100:0.101 ratio. A non-reactive silicone oil (e.g., DMS-T23, Gelest, Inc., 350 cSt, or DMS-T25, Gelest, Inc., 50 cSt) was added. Mixing can be initiated at low rpm (100 rpm) and gradually increased to 500 rpm for 2 minutes, after which the mixing speed can be increased to 1200-1400 rpm for 3 minutes.

[0155] The second set of ingredients was prepared by adding vinyl-terminated polydimethylsiloxane (DMS-V35, Gelest, Inc.), 5,000 cSt, average MW 49,500 g / mol, to the crosslinker, GELEST SIT 7278.0, chain extender, GELEST DMS-H03, and nonreactive silicone oil. The crosslinker is added to the vessel first, as small changes in the amount added can significantly affect gel hardness. Any inhibitors may be added to the reaction vessel. The chain extender and nonreactive silicone oil are then added. It is best to begin mixing at a low rpm (100 rpm). Increase to 500 rpm for 2 minutes, scraping down the sides of the vessel with a plastic rod. After this 2-minute period, the mixing speed can be increased to 1200-1400 rpm for 3 minutes.

[0156] The first set of components was mixed with the second set of components in a vial in an approximately 1:1 ratio. The two sets of components were mixed at 1250 rpm for 2-3 minutes, placed under vacuum for 4-5 minutes, and poured into the desired mold. The resulting molding mixture was placed under vacuum for 3 minutes and then cured at 90°C for 30 minutes. Additional silicone gels were produced at various hardnesses by adding crosslinkers and chain extenders while maintaining an MFHC of 0.3-0.4, resulting in silicone gels with harnesses of 80g, 100g, 110g, and 120g.

[0157] Example 2. Silicone Oil Gel Hardness and Compression Set Recovery Silicone oil gels were made from formulations similar to those shown in Table 1, containing 5000 cP divinyl-terminated polydimethylsiloxane, chain extender, crosslinker (the mole fraction of hydride as crosslinker was approximately 0.3–0.4), and 40% 50 cP non-reactive PDMS silicone fluid, in three different volumes of 80 g, 100 g, and 120 g. 60s The hardness and compression set recovery of the cured silicone gels are shown in Figure 1. Each silicone oil gel recovered most of its compression set within 5 minutes, with little residual compression set remaining by 60 minutes. Specifically, each of the silicone gels in Figure 1 exhibited compression set recovery of 10% or less after 5 minutes, or 5% or less after 30 minutes. The rapid compression set recovery was a physical property that allowed this gel formulation to quickly seal closures (fast enough that the closures could be assembled and tested) to pressures of 20 kPa. The same closures could be quickly opened and resealed (also within 5 minutes) and repeatedly (up to 17 times) to 20 kPa after thermal cycling each time they were opened and closed for resealing testing. Closures made using prior art silicone dry gel formulations failed this test, typically requiring up to 2 hours after opening and closing to reseal to 20 kPa.

[0158] Example 3. Bleeding out of silicone oil gel Silicone gel compositions were prepared similarly to Example 1, Table 1, except that they contained 40% of different non-reactive PDMS silicone extender oils of various viscosities, including 50 cSt, 350 cSt, 1000 cSt, or 5000 cSt. Oil bleed-out was tested for cured silicone oil gels at 70°C and 120 kPa pressure for 37 to 50 days. As shown in Figure 2, each silicone gel exhibited less than 15 wt. % oil bleed-out by 21 days. Each silicone gel exhibited less than 20 wt. % oil bleed-out by 35 days. Surprisingly, the silicone gels using the low-viscosity 50 cSt PDMS extender oil exhibited less oil bleed than the high-viscosity 350 cSt, 1000 cSt, or 5000 cSt non-reactive PDMS oils, as shown in Figure 2.

[0159] Example 4. Additional test plan for oil-extended silicone gel Additional process testing was performed as shown in Table 2.

[0160] [Table 2]

[0161] Silicone oil gels were prepared using the Al cups provided herein with the target hardness and n numbers shown in Table 3.

[0162] [Table 3]

[0163] Oil bleed out Oil bleed-out was performed on two sets of oil-extended silicone gels with 40 wt% 50 cSt silicone oil at target hardnesses of 80 g, 100 g, or 120 g, respectively, at 80 kPa for 112 days (Tables 4A, B, C) or 120 kPa for 112 days (Tables 5A, B, C).

[0164] [Table 4]

[0165] [Table 5]

[0166] [Table 6]

[0167] The silicone gel exhibited less than 10% oil bleed-out after 120 days at a pressure of 80 kPa, as shown in Tables 4A, B, and C.

[0168] [Table 7]

[0169] [Table 8]

[0170] [Table 9]

[0171] The silicone gel exhibited less than 15% oil bleed-out after 120 days at a pressure of 120 kPa, as shown in Tables 5A, B, and C.

[0172] Compression set Compression set experiments were conducted on stretched silicone gels with 40% 50 cSt silicone oil by weight at target hardnesses of 80 g, 100 g, or 120 g, respectively, using a 0.375 inch spacer at 70°C, and the compression fixture was allowed to cool to room temperature before opening. Compression set data (% compression) after 22 hours, 7 days, 21 days, or 56 days are shown in Tables 6A-9C.

[0173] [Table 10]

[0174] [Table 11]

[0175] [Table 12]

[0176] The compression set results (% compression) after 7 days are shown in Tables 7A, B, and C.

[0177] [Table 13]

[0178] [Table 14]

[0179] [Table 15]

[0180] The compression set results (% compression) after 21 days are shown in Tables 8A, B, and C.

[0181] [Table 16]

[0182] [Table 17]

[0183] [Table 18]

[0184] Compression set results (% compression) after 56 days are shown in Tables 9A, B, and C.

[0185] [Table 19]

[0186] [Table 20]

[0187] [Table 21]

[0188] The extensible silicone gels of the present disclosure after being compressed at 70°C for up to 56 days exhibit a compression set of <20%, <12%, <10%, <5%, or <4%, or 0-20%, 0-12%, 0-5%, or 0-4% after a 24 hour recovery period.

[0189] The extensible silicone gels of the present disclosure after being compressed at 70°C for up to 56 days exhibit a compression set of <20%, <15%, or <12%, or 0-20%, 2-20%, or 4-12%, after a 5 minute recovery time.

[0190] After being compressed at 70°C for up to 56 days, the extensible silicone gels having 40% by weight of 50 cSt silicone oil at target hardnesses of 80 g, 100 g, or 120 g, respectively, exhibit a compression set of 0-20%, 2-20%, or 2-12%, or a compression set of <20%, or <15%.

[0191] After being compressed at 70°C for up to 56 days, extensible silicone gels having 40 wt% 50 cSt silicone oil at target hardnesses of 80 g, 100 g, or 120 g each exhibit <15%, <12%, <10%, or <9%, or 0-20%, 1-15%, or 2-12% recovery in 30 minutes.

[0192] After being compressed at 70°C for up to 56 days, extensible silicone gels with 40 wt% 50 cSt silicone oil at target hardnesses of 80 g, 100 g, or 120 g each exhibit a compression set of <8%, or <7%, or 1-8%, or 2-7% with a 60 minute recovery time.

[0193] After being compressed at 70°C for up to 56 days, extensible silicone gels having 40% by weight of 50 cSt silicone oil at target hardnesses of 80 g, 100 g, or 120 g each exhibit a compression set of <6%, or <5%, or 0-6%, or 0.5-5% with a 24-hour recovery time.

[0194] Extrusion Resistance Extrusion resistance experiments were performed on extensible silicone gels made with 40% 50 cSt silicone oil with target hardnesses of 60 g, 80 g, 100 g, or 120 g at 70°C and 25 psi for 24 and 168 hours to determine bubble size and gel fracture. Two gels of each hardness were performed. Results: After 1 week at 70°C and 25 psi, the 120 g gel exhibited silicone gel bubbles approximately 4 mm in diameter, protruding 2–3 mm from the device. After 1 week at 70°C and 25 psi, the 80 g gel exhibited silicone gel bubbles approximately 7 mm in diameter, protruding 5–6 mm from the device.

[0195] Tensile and Elongation Tests Tensile and elongation tests were performed on stretched silicone gels made with 40% 50 cSt silicone oil with target hardnesses of 60, 70, 80, 90, 100, 110, 120, or 130 g for tensile elongation, for example, using ASTM D638 or as described herein. Tensile strength, elongation at break, and competition curves were determined under standard test conditions using two plaques of each ratio. Elongation test results are shown in Table 10A. Aged stretched silicone gel samples were also tested. The plaques were aged at 70°C for 1 week (168 hours) before blanking out the gel rings for testing. Aged elongation test results are shown in Table 10B.

[0196] [Table 22]

[0197] [Table 23]

[0198] The elongation data for the filled (20% R8200 silica) and unfilled stretched silicone gel (40%, 50 cSt non-reactive PDMS silicone oil) are shown in Table 10C. The stretched silicone gel was filled with 20 wt% fumed silica and surface modified with silane R8200 (Evonik).

[0199] [Table 24]

[0200] The extensible silicone gel exhibited an elongation of >1000% (unfilled) or >1500% when filled with 20% R8200 silica.

[0201] Hardness Testing Spreading gels with 40% by weight of 50 cSt non-reactive PDMS silicone oil were prepared according to the present disclosure. The gels were cured at 90°C for 10 minutes, or as otherwise specified. The 60-second hardness was measured using the texture analyzer provided herein. Table 11A shows the change in 60-second hardness after curing for 10 minutes at 90°C, and the increase in 60-second hardness for four spreading silicone gels at 1 hour and 6 days after curing.

[0202] [Table 25]

[0203] For each extensible silicone gel, the 60-second hardness increased from 5% to 11% between 1 hour and 6 days after curing.

[0204] Table 11B shows the 60 second hardness versus time for two different cure times, 15 minutes or 60 minutes at 90 degrees Celsius.

[0205] [Table 26]

[0206] Table 11C shows the gel hardness versus time after curing for four different extensible silicone gels made with 40% 50 cSt silicone oil.

[0207] [Table 27]

[0208] Table 11D shows the 60 minute (3600 seconds) hardness curves over time for eight stretched silicone gels with 40% silicone oil.

[0209] [Table 28]

[0210] [Table 29]

[0211] For the silicone gels of the present disclosure, as the ratio of A:B decreases, the firmness of the gel increases. Some embodiments of the present invention are described in the following items [1]-

[37] . [1] 1. A method of making a silicone gel, comprising: providing a first set of ingredients including (1) a base polymer having vinyl-silicone groups, (2) an addition cure catalyst, and optionally (3) a non-reactive silicone oil; providing a second set of ingredients including (1) a crosslinker, (2) an additional base polymer having vinyl-silicone groups, and optionally (3) a non-reactive silicone oil; mixing the first and second sets of ingredients together to form a silicone gel composition; and molding and curing the silicone gel composition to form the silicone gel. [2] 2. The method of claim 1, wherein the second set of ingredients further comprises a chain extender. [3] 3. The method of claim 1, wherein the first and / or second set of ingredients comprises the non-reactive silicone oil. [4] 4. The method according to any one of items 1 to 3, wherein the non-reactive silicone oil is a trimethylsiloxy-terminated or silanol-terminated polydialkylsiloxane. [5] The non-reactive silicone oil is 10 to 30,000 cSt (10 to 30,000 mm 2 / s), 20 to 5,000cSt (20 to 5,000mm 2 / s), 50 to 1,000cSt (50 to 1,000mm 2 / s), or 50 to 350 cSt (50 to 350 mm 2 5. The method according to any one of items 1 to 4, wherein the viscosity of the solution is 0.15 wt % or less. [6] 6. The method according to any one of items 1 to 5, wherein the silicone gel composition comprises 10 to 60 wt %, 20 to 55 wt %, or 30 to 50 wt % of the non-reactive silicone oil. [7] 7. The method of any one of items 1 to 6, wherein the base polymer and the additional base polymer are each vinyl-terminated polydimethylsiloxane. [8] The base polymer and the additional base polymer each have the following characteristics: (a) a molecular weight of 6,000 g / mol to 170,000 g / mol; (b) a molecular weight of 100 mm 2 / s~165,000mm 2 8. The method according to any one of items 1 to 7, wherein the composition has one or more of: (a) a viscosity of 0.01 eq / kg to 0.1 eq / kg; and (b) a vinyl content of 0.01 eq / kg to 0.1 eq / kg. [9] 9. The method according to any one of items 1 to 8, wherein the silicone gel composition comprises the base polymer and an additional base polymer in an amount of 40 to 90 wt %, 45 to 80 wt %, or 50 to 65 wt %.

[10] 10. The method according to any one of items 1 to 9, wherein the crosslinker has three or four Si—H hydride moieties per molecule and the chain extender has two Si—H hydride moieties per molecule.

[11] 11. The method according to any one of items 1 to 10, wherein the mole fraction of hydride (MFHC) present as the crosslinker is from about 0.2 to about 0.5.

[12] 12. The method according to any one of items 1 to 11, wherein the hydride to vinyl ratio in the silicone gel composition is 0.8 to 1.0.

[13] 13. The method according to any one of items 1 to 12, wherein the crosslinking agent is selected from the group consisting of tetrakis(dimethylsiloxy)silane, methyltris(dimethylsiloxy)silane, phenyltris(dimethylsiloxy)silane, and combinations thereof.

[14] 14. The method of any one of items 2 to 13, wherein the chain extender is selected from the group consisting of hydride-containing polydimethylsiloxanes, dihydride-containing siloxanes, hydride-terminated polydimethylsiloxanes, hydride-terminated polyphenylmethylsiloxanes, hydride-terminated polydiphenylsiloxanes, functionalized-terminated silicones, and combinations thereof.

[15] 15. The method according to any one of items 1 to 14, wherein the catalyst is selected from the group consisting of platinum and rhodium chloride complexes complexed with divinyltetramethyldisiloxane.

[16] 16. The method according to any one of items 1 to 15, wherein the weight ratio of the first component set to the second component set is 1.10:1.0 to 1.0:1.10.

[17] The silicone gel has the following properties: (a) a hardness of 50g to 200g, (b) a compression set of 2% to 20% after subjecting the gel to a 50% strain at 70°C for 1000 hours, (c) a compression set recovery of 12% or less after 5 minutes, (d) an oil bleed out of 15% or less after being subjected to a compression of 1.2 atmospheres at 70°C for 21 days, and (e) a H of 80g to 120g. 60s 17. The method according to any one of items 1 to 16, comprising one or more of:

[18] A silicone gel prepared from a silicone gel composition comprising a base polymer having vinyl-silicone groups, a catalyst, a crosslinker, and a non-reactive silicone oil.

[19] Item 19. The silicone gel according to item 18, wherein the silicone gel composition further comprises a chain extender.

[20] 20. The silicone gel according to item 18 or 19, wherein the non-reactive silicone oil is a trimethylsiloxy-terminated or silanol-terminated polydialkylsiloxane.

[21] The non-reactive silicone oil is 10 to 30,000 cSt (10 to 30,000 mm 2 / s), 20 to 5,000cSt (20 to 5,000mm 2 / s), 50 to 1,000cSt (50 to 1,000mm 2 / s), or 50 to 350 cSt (50 to 350 mm 2 21. The silicone gel according to any one of items 18 to 20, having a viscosity of 1 / s.

[22] 22. The silicone gel according to any one of items 18 to 21, wherein the silicone gel composition comprises 10 to 60 wt. %, 20 to 55 wt. %, or 30 to 50 wt. % of the non-reactive silicone oil.

[23] 23. The silicone gel according to any one of items 18 to 22, wherein the base polymer and the additional base polymer are each vinyl-terminated polydimethylsiloxane.

[24] 24. The silicone gel according to any one of items 18 to 23, wherein the base polymer and the additional base polymer each have one or more of the following properties: (a) a molecular weight of 6,000 g / mol to 170,000 g / mol, (b) a viscosity of 100 mm / s to 165,000 mm / s, and (c) a vinyl content of 0.01 equivalents / kg to 0.1 equivalents / kg.

[25] 25. The silicone gel according to any one of items 18 to 24, wherein the silicone gel composition comprises the base polymer and additional base polymer in an amount of 40 to 90 wt %, 45 to 80 wt %, or 50 to 65 wt %.

[26] 26. The silicone gel according to any one of items 18 to 25, wherein the crosslinker has three or four Si—H hydride moieties per molecule and the chain extender has two Si—H hydride moieties per molecule.

[27] 27. The silicone gel according to any one of items 18 to 26, wherein the silicone gel composition comprises a mole fraction of hydrides (MFHC) present as crosslinkers, of about 0.2 to about 0.5.

[28] 26. The silicone gel according to any one of items 17 to 25, wherein the hydride to vinyl ratio in the silicone gel composition is 0.8 to 1.0.

[29] 29. The silicone gel according to any one of items 18 to 28, wherein the crosslinking agent is selected from the group consisting of tetrakis(dimethylsiloxy)silane, methyltris(dimethylsiloxy)silane, phenyltris(dimethylsiloxy)silane, and combinations thereof.

[30] 30. The silicone gel according to any one of items 19 to 29, wherein the chain extender is selected from the group consisting of hydride-containing polydimethylsiloxanes, dihydride-containing siloxanes, hydride-terminated polydimethylsiloxanes, hydride-terminated polyphenylmethylsiloxanes, hydride-terminated polydiphenylsiloxanes, functionalized-terminated silicones, and combinations thereof.

[31] 31. The silicone gel according to any one of items 18 to 30, wherein the catalyst is selected from the group consisting of platinum and rhodium chloride complexes complexed with divinyltetramethyldisiloxane.

[32] The silicone gel has the following properties: (a) a hardness of 50g to 200g, (b) a compression set of 0% to 12% after subjecting the gel to a 50% strain at 70°C for 1000 hours, (c) a compression set recovery after 5 minutes to a compression set of 12% or less, (d) an oil bleed out of 15% or less after being subjected to a compression of 1.2 atmospheres at 70°C for 21 days, and (e) a H of 80g to 120g. 60s 32. The silicone gel according to any one of items 18 to 31, comprising one or more of the following:

[33] 33. A closure or interconnection system comprising the silicone gel of any one of items 18 to 32, the system being capable of sealing and resealing to a pressure of 20 kPa within 5 minutes after opening and closing.

[34] 1. A sealant for use in an enclosure for sealing cable entry / exit locations, said sealant comprising: Residual indentation hardness in the range of 20g to 150g, A compression set of less than 10% after 30, 20, or 10 minutes of recovery time; an elongation at break of at least 500%; 0.5cm 3 and a sealant material having an extrusion resistance having a measured volume of:

[35] 35. The sealant of claim 34, wherein the sealant material is a thermosetting material.

[36] 36. The sealant according to claim 34 or 35, wherein the sealant comprises a silicone gel prepared from a silicone gel composition comprising a base polymer having vinyl-silicone groups, a catalyst, a crosslinker, a chain extender, and a non-reactive silicone oil.

[37] 37. The sealant according to any one of items 34 to 36, wherein the sealant exhibits less than 20% or less than 15% oil bleed-out after 21 days at 70°C and 1.2 atmospheres.

Claims

1. 1. A method of making a silicone gel, comprising: providing a first set of components including (1) a base polymer having divinyl-terminated silicone groups, (2) an addition cure catalyst, and optionally (3) a non-reactive silicone oil; providing a second set of ingredients comprising: (1) a polyhydride crosslinker selected from the group consisting of tetrakis(dimethylsiloxy)silane, methyltris(dimethylsiloxy)silane, phenyltris(dimethylsiloxy)silane, and combinations thereof; (2) an additional base polymer having divinyl terminated silicone groups; and optionally (3) a non-reactive silicone oil; wherein the second set of ingredients further comprises a dihydride chain extender having two Si—H hydride moieties per molecule, and the mole fraction of hydride (MFHC) present as the crosslinker is from 0.2 to 0.5; mixing the first and second sets of components together to form a silicone gel composition; and molding and curing the silicone gel composition to form the silicone gel; The method, wherein at least one of the first and second sets of ingredients comprises the non-reactive silicone oil.

2. 10. The method of claim 1, wherein the chain extender is a hydride-terminated polydimethylsiloxane having an average molecular weight of 400 to 62,700 g / mol.

3. 10. The method of claim 1, wherein the non-reactive silicone oil is a trimethylsiloxy- or silanol-terminated polydialkylsiloxane.

4. The non-reactive silicone oil has a viscosity of 10 to 30,000 cSt (10 to 30,000 mm ２ 10. The method of claim 1, wherein the composition has a kinematic viscosity measured at 25°C of 0.1 / s.

5. The method of claim 1, wherein the silicone gel composition comprises 10 to 60 weight percent of the non-reactive silicone oil.

6. The method of claim 1 , wherein the base polymer and the additional base polymer are each vinyl-terminated polydimethylsiloxanes.

7. The base polymer and the additional base polymer each have the following characteristics: (a) an average molecular weight of 6,000 g / mol to 170,000 g / mol; (b) an average molecular weight of 100 mm ２ / s~165,000mm ２ 10. The method of claim 6, wherein the composition has one or more of: (a) a kinematic viscosity measured at 25°C of from 0.01 equivalents / kg to 0.1 equivalents / kg; and (b) a vinyl content of from 0.01 equivalents / kg to 0.1 equivalents / kg.

8. The method of claim 1, wherein the silicone gel composition comprises the base polymer and an additional base polymer in an amount of 40 to 90 weight percent.

9. 2. The method of claim 1, wherein the mole fraction of hydride (MFHC) present as the crosslinker is 0.3 to 0.

4.

10. 10. The method of claim 1, wherein the hydride to vinyl ratio, defined as the hydride / vinyl ratio, H / V, in the silicone gel composition is from 0.8 to 1.

0.

11. 10. The method of claim 1, wherein the catalyst is selected from the group consisting of platinum and rhodium chloride complexes complexed with divinyltetramethyldisiloxane.

12. 10. The method of claim 1, wherein the weight ratio of the first set of ingredients to the second set of ingredients is from 1.10:1.0 to 1.0:1.

10.

13. The silicone gel has the following properties: (a) H of 50 g to 200 g measured 60 seconds after a 6.35 mm spherical probe is pressed into the gel to a depth of 4.0 mm using a texture analyzer; ６０ｓ 10. The method of claim 1, wherein the gel exhibits one or more of the following properties: (a) hardness; (b) a compression set of 2% to 20% after subjecting the gel to a 50% strain for 1000 hours at 70°C when tested using ASTM D395, Method B; (c) a compression set recovery after 5 minutes to a compression set of 12% or less when tested using ASTM D395, Method B; and (d) an oil bleed out of less than 20% after 21 days at 70°C and 1.2 atmospheres.

14. 10. A silicone gel prepared by the method of claim 1 from a silicone gel composition comprising a base polymer having divinyl terminated silicone groups, a catalyst, a polyhydric crosslinker selected from the group consisting of tetrakis(dimethylsiloxy)silane, methyltris(dimethylsiloxy)silane, phenyltris(dimethylsiloxy)silane, and combinations thereof, a dihydric chain extender having two Si—H hydride moieties per molecule, and a non-reactive silicone oil.

15. 15. The silicone gel of claim 14, wherein the non-reactive silicone oil is a trimethylsiloxy- or silanol-terminated polydialkylsiloxane.

16. The non-reactive silicone oil has a viscosity of 10 to 30,000 cSt (10 to 30,000 mm ２ 15. The silicone gel of claim 14, having a kinematic viscosity measured at 25°C of 1 / s.

17. 15. The silicone gel of claim 14, wherein the silicone gel composition comprises 10 to 60% by weight of the non-reactive silicone oil.

18. 15. The silicone gel of claim 14, wherein the base polymer is a divinyl-terminated polydimethylsiloxane.

19. The base polymer has the following characteristics: (a) an average molecular weight of 6,000 g / mol to 170,000 g / mol; (b) an average molecular weight of 100 mm ２ / s~165,000mm ２ 15. The silicone gel of claim 14, having one or more of: (a) a kinematic viscosity measured at 25°C of 0.01 equivalents / kg to 0.1 equivalents / kg; and (b) a vinyl content of 0.01 equivalents / kg to 0.1 equivalents / kg.

20. 15. The silicone gel of claim 14, wherein the silicone gel composition comprises the base polymer in an amount of 40 to 90% by weight.

21. 15. The silicone gel of claim 14, wherein the mole fraction of hydride (MFHC) present as a crosslinker in the silicone gel composition is 0.2 to 0.

5.

22. 15. The silicone gel of claim 14, wherein the hydride to vinyl ratio, defined as H / V, in the silicone gel composition is from 0.8 to 1.

0.

23. 15. The silicone gel of claim 14, wherein the catalyst is selected from the group consisting of platinum and rhodium chloride complexes complexed with divinyltetramethyldisiloxane.

24. The silicone gel has the following properties: (a) H of 50 g to 200 g measured 60 seconds after a 6.35 mm spherical probe is pressed into the gel to a depth of 4.0 mm using a texture analyzer; ６０ｓ 15. The silicone gel of claim 14, comprising one or more of the following: (a) hardness; (b) a compression set of 2% to 20% after subjecting the gel to a 50% strain for 1000 hours when tested using ASTM D395, Method B; (c) a compression set recovery after 5 minutes to a compression set of 12% or less when tested using ASTM D395, Method B; and (d) an oil bleed out of less than 20% after 21 days at 70°C and 1.2 atmospheres.

25. 15. A closure or interconnect system comprising the silicone gel of claim 14, wherein the system can be sealed and resealed to a pressure of 20 kPa within 5 minutes of opening and closing.

26. 1. A sealant for use in an enclosure for sealing cable entry / exit locations, said sealant comprising: A residual indentation hardness ranging from 20 g to 150 g after 1 hour when a 6.35 mm spherical probe was indented into the gel to a depth of 4.0 mm using a texture analyzer; a compression set of less than 10% after 30, 20, or 10 minutes recovery time when tested using ASTM D395, Method B; an elongation at break of at least 500% when tested using ASTM D638; 0.5 cm ３ and a thermosetting sealant material prepared by the method of claim 1 having an extrusion resistance with a measured volume of: A sealant comprising a silicone gel prepared from a silicone gel composition comprising a base polymer having vinyl-silicone groups, a catalyst, a polyhydric crosslinker, a chain extender, and a non-reactive silicone oil.

27. 27. The sealant of claim 26, wherein the sealant exhibits less than 20% oil bleed-out after 21 days at 70°C and 1.2 atmospheres.

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