Liquid silicone rubber composition

Abstract

This disclosure relates to hydrosilylated (addition) curable silicone rubber compositions, silicone elastomer materials produced by curing said hydrosilylated (addition) curable silicone rubber compositions and having improved high-temperature (175°C) compression set according to ISO 815-1 Method A, and methods for preparing said silicone elastomer materials. This disclosure also extends to the use of such materials.

Description

[Technical Field]

[0001] This disclosure relates to hydrosilylated (addition) curable silicone rubber compositions, silicone elastomer materials produced by curing said hydrosilylated (addition) curable silicone rubber compositions and having improved high-temperature (175°C) compression set according to ISO 815-1 Method A, and methods for preparing said silicone elastomer materials. This disclosure also extends to the use of such materials.

[0002] A hydrosilylated curable silicone rubber composition, (i) organopolysiloxane polymers having unsaturated (alkenyl and / or alkynyl) groups, (ii) Compounds containing silicon-bonded hydrogen atoms, and (iii) A hydrosilylated curable silicone rubber composition containing a hydrosilylation catalyst is It is used to prepare silicone elastomer materials that are known in the art and have a wide range of physical properties, including electrical insulation, heat resistance and thermal stability, freeze resistance, abrasion resistance, flame retardancy, and long-term flexibility. This unique combination of properties makes elastomers manufactured from liquid silicone rubber suitable for a wide range of electrical and / or insulating applications, such as electrical connectors commonly used to form closed electrical circuits in automotive, residential, and infrastructure environments.

[0003] For example, silicone elastomers (both liquid silicone rubber (LSR) and high-consistency rubber (HCR)) are widely used in or as seals for electrical connectors due to their excellent balance of mechanical properties, chemical and thermal stability, and ease of processing. They can be used to mat rigid thermoplastic housing components, forming a tight connection that provides both electrical and environmental isolation at the connector joint. These can be used in automobiles, where the degree to which their full operation depends on electrical and electronic systems is increasing, and has increased further since the introduction of electric and hybrid vehicles. Therefore, electrical failures can lead to malfunctions or failures of devices such as radios, lights, and ventilation systems. Many electrical connectors used in such devices rely on the aforementioned silicone rubber material to prevent electrical failures and need to be able to avoid, for example, vehicle failures when engine temperatures rise.

[0004] Many of these applications require silicone elastomer materials to have low compression set, in addition to applications such as electrical insulation and / or thermal stability. Compression set is an important property of silicone elastomer materials used in any of the above applications. Compression set is the thermally induced fatigue behavior of a silicone elastomer material, which can be defined as the loss of the silicone elastomer material's ability to recover to its original thickness after being compressed over a specific period at a curing (rise) temperature. The compression set value can be measured, for example, according to methods A, B, or C of the industrial standard ISO 815-1:2019, and is specified as a percentage. For example, if there is complete recovery, i.e., the thickness of the test specimen is the same before and after the application of the load, the compression set is 0%. In contrast, if a 25% compression of the silicone elastomer material applied during the test remains unchanged when the load is removed, the compression set is 100% because it did not return to its original shape at all. While not bound by current theory, the fundamental reason why silicone elastomer materials are irrecoverable to their original thickness after being compressed for a specific period at a curing (high) temperature is thought to be that hydrosilylated curable silicone compositions do not always, if often, undergo complete curing during the standard curing process. This is thought to be at least in part due to incomplete hydrosilylation caused by steric hindrance during the interaction of the vinyl-containing silicone polymer, Si-H crosslinker(s), and hydrosilylation catalyst (most typically platinum-based catalyst). Therefore, when hydrosilylated curable silicone elastomer materials are compressed at high temperatures, further crosslinking can occur within the body of the silicone elastomer material, specifically at previously unreacted Si-H positions. Furthermore, intermolecular bond formation can occur between polydimethylsiloxane (PDMS) chains, specifically at similarly previously unreacted Si-H excess positions (via hydrolysis, oxidation, or thermal induction reaction pathways), and thermal oxidation rearrangements can occur within or between individual PDMS chains of the silicone elastomer material.One or more of the above occurrences lead to an increase in crosslinking density within the silicone elastomer material, resulting in a more rigid structure that prevents the silicone elastomer material from returning to its original thickness after compression.

[0005] Many silicone elastomer materials, even after being compressed for a short period, for example 22 hours, at temperatures of 125°C and 150°C, exhibit considerable compression set, for example, exceeding 50% or even exceeding 60%, and unless subjected to a post-curing heating process, can suffer problems during long-term use in high-temperature applications caused by resulting changes in shape and / or a significant increase in hardness. "Post-curing" is the simplest method to minimize compression set, in which case the hydrosilylated cured silicone material is subjected to post-curing heating at 150°C or above for a period of several hours, for example, more than 4 hours. However, post-curing is usually not commercially desirable or practically feasible considering the increased energy consumption and delays in manufacturing time.

[0006] For many of the above applications, a silicone elastomer material is typically desired that has the lowest possible compression set value over a wide temperature range, for example, 40% or less.

[0007] In the United States, electrical connector systems must meet the requirements of the SAE International USCAR-2 "Performance Specification for Automotive Electrical Connector Systems" test format. Sealed connector assemblies are graded for their suitability for use over a specific temperature range, meeting the relevant automotive specification class for a given temperature range. Currently, there are five ranges identified as T1 to T5. T1 is for the temperature class of -40℃ to +85℃. T2 is for the temperature range of -40°C to +100°C. T3 is for a temperature range of -40°C to +125°C. T4 is for a temperature range of -40°C to +150°C, and currently the highest grade is... This is a T5 rating, suitable for temperatures between -40°C and 175°C.

[0008] Current sealed connector assemblies meet the T3 temperature class. However, vehicle manufacturers are developing vehicles that inevitably require better sealing, higher engine efficiency, and the ability to withstand higher temperatures in and around the vehicle engine due to factors such as the use of turbochargers. Therefore, electrical connectors made from silicone rubber increasingly need to function at even higher temperatures to meet T4 and T5 requirements.

[0009] Considering that it is undesirable to post-cur all elastomers after curing, various additives have been proposed to reduce compression set without requiring post-curing.

[0010] In U.S. Patent No. 5,153,244, the compression set of hydrosilylated cured silicones was substantially reduced by introducing a phthalocyanine compound or a metal derivative of such a compound (the metal being copper, nickel, cobalt, or iron) into the composition.

[0011] U.S. Patent No. 8080598(B2) proposes a hydrosilylated cured silicone rubber with low compression set that does not require post-curing, using diacyl-hydrazide compounds such as dodecanedi-oil-di-(N'-salicyloyl)hydrazine (synonym: 1-N',12-N'-bis(2-hydroxybenzoyl)dodecanedihydrazide), along with several substitutes, in combination with a curing inhibitor selected from acetylene-containing silanes, vinyl-containing low molecular weight organosiloxane compounds, or alcohol derivatives having a CC triple bond, thereby reducing compression set. The introduction to U.S. Patent No. 8080598(B2) states that "articles molded from organopolysiloxane rubber compositions that are curable by addition reaction and compounded with phthalocyanine compounds have limited practical applications due to discoloration caused by phthalocyanine." Despite the teachings in U.S. Patent Nos. 8080598(B2), 9289963(B2), 9598575(B2), and 10000680(B2), we have returned to using phthalocyanine compounds as compression set additives.

[0012] However, most of the previously used compression set additives, such as those mentioned above, are suitable for improving compression set after at least 22 hours of compression, with a maximum upper limit of T5 (+175°C). Most current silicone elastomers made from LSR only meet the requirements of class T3 (up to 125°C) or T4 (up to 150°C), with compression set of 50% or less (≤) after 1008 hours of compression at each temperature. Therefore, they do not work well enough to reduce compression set for newer target performance at a permanent test temperature of 175°C (T5), which is increasingly being considered / proposed due to growing demand from industries such as the automotive industry.

[0013] This specification describes a silicone rubber composition comprising the following components, namely, a) One or more polyorganosiloxanes containing at least two unsaturated groups selected from alkenyl groups and alkynyl groups per molecule, and having a viscosity in the range of 1,000 mPa.s to 100,000 mPa.s at 25°C, b) Organosilicon compounds having at least two or at least three Si-H groups per molecule; c) A silica-reinforced filler that has been optionally hydrophobized, d) A hydrosilylation catalyst containing or consisting of a platinum group metal or a compound thereof, e) Compression set additives, (i) Phthalocyanine compounds or metal derivatives of such compounds, wherein the metal is copper, nickel, cobalt, iron, manganese, chromium, zinc, platinum, palladium, and vanadium, and optionally, (ii) One or more compounds selected from diacylhydrazide compounds Selected from, Compression set additives present cumulatively (i.e., in (i) + (ii)) in amounts of 0.02% to 3.5% by weight of the composition, f) The composition contains 0.25 to 5.0% by weight of one or more of magnesium hydroxide, magnesium carbonate, magnesium hydroxycarbonate, or manganese carbonate. A silicone rubber composition is provided, wherein the total weight percentage of the composition is 100% by weight.

[0014] Also provided is a silicone elastomer material which is a cured product of the above hydrosilylation-curable silicone rubber composition and has a compression set of 20% or less, preferably 15% or less, when measured according to Industrial Standard Specification ISO815-1 Method A after compression at 175°C for 22 hours, or a compression set of 30% or less, preferably 25% or less, when measured according to Industrial Standard Specification ISO815-1 Method A after compression at 175°C for 168 hours (one week), or a compression set of 45% or less, preferably 35% or less, when measured according to Industrial Standard Specification ISO815-1 Method A after compression at 175°C for 504 hours, or a compression set of 55% or less, preferably 50% or less, when measured according to Industrial Standard Specification ISO815-1 Method A after compression at 175°C for 1008 hours.

[0015] Also provided is a process for producing a silicone elastomer material, the process comprising the following components, namely: a) one or more polyorganosiloxanes containing at least two unsaturated groups selected from alkenyl groups and alkynyl groups per molecule and having a viscosity in the range of 1000 mPa·s to 100,000 mPa·s at 25°C, b) an organosilicon compound having at least two or at least three Si-H groups per molecule; c) a silica reinforcing filler optionally hydrophobized, d) a hydrosilylation catalyst containing or consisting of a platinum group metal or a compound thereof, e) a compression set additive selected from: (i) a phthalocyanine compound or a metal derivative of such a compound, wherein the metal is copper, nickel, cobalt, iron, manganese, chromium, zinc, platinum, palladium, and vanadium, and optionally, (ii) one or more compounds selected from diacylhydrazide-based compounds and A compression set additive that is present cumulatively (i.e., in (i) + (ii)) in an amount of 0.02% to 3.5% by weight of the composition, and f) One or more of magnesium hydroxide, magnesium carbonate, magnesium hydroxycarbonate, or manganese carbonate in an amount of 0.25 to 5.0% by weight of the composition, A step of mixing a hydrosilylation curable silicone rubber composition having A step in which the total weight percentage of the composition is 100% by weight, A step of curing the composition at a temperature of 80°C to 200°C, and a process is also provided.

[0016] Also, a silicone elastomer material comprising the following components, namely, a) One or more polyorganosiloxanes containing at least two unsaturated groups selected from alkenyl groups and alkynyl groups per molecule and having a viscosity in the range of 1000 mPa·s to 100,000 mPa·s at 25°C, b) An organosilicon compound having at least two or at least three Si-H groups per molecule; c) Optionally hydrophobically treated silica reinforcing filler, d) A hydrosilylation catalyst containing or consisting of a platinum group metal or a compound thereof, e) A compression set additive, (i) A phthalocyanine compound or a metal derivative of such a compound, wherein the metal is copper, nickel, cobalt, iron, manganese, chromium, zinc, platinum, palladium, and vanadium, a phthalocyanine compound or a metal derivative of such a compound, and optionally, (ii) One or more compounds selected from diacylhydrazide-based compounds Selected from, A compression set additive that is present cumulatively (i.e., in (i) + (ii)) in an amount of 0.02% to 3.5% by weight of the composition, and f) One or more of magnesium hydroxide, magnesium carbonate, magnesium hydroxycarbonate, or manganese carbonate in an amount of 0.25 to 5.0% by weight of the composition, A step of mixing a hydrosilylated curable silicone rubber composition having, The process involves a total weight percentage of the composition being 100% by weight, Also provided are silicone elastomer materials obtained or obtainable from a process that includes the step of curing the composition at a temperature of 80°C to 200°C. This silicone elastomer material is Silicone elastomer materials are also provided that, after being compressed at 175°C for 22 hours and measured according to the industrial standard ISO 815-1 Method A, have a compression set of 20% or less, preferably 15% or less; or after being compressed at 175°C for 168 hours (1 week) and measured according to the industrial standard ISO 815-1 Method A, have a compression set of 30% or less, preferably 25% or less; or after being compressed at 175°C for 504 hours and measured according to the industrial standard ISO 815-1 Method A, have a compression set of 45% or less, preferably 35% or less; or after being compressed at 175°C for 1008 hours and measured according to the industrial standard ISO 815-1 Method A, have a compression set of 55% or less, preferably 50% or less.

[0017] Furthermore, in silicone rubber compositions, e) Compression set additives, (i) Phthalocyanine compounds or metal derivatives of such compounds, wherein the metal is copper, nickel, cobalt, iron, manganese, chromium, zinc, platinum, palladium, and vanadium, and optionally, (ii) One or more compounds selected from diacylhydrazide compounds Selected from, Compression set additives present cumulatively (i.e., in (i) + (ii)) in amounts of 0.02% to 3.5% by weight of the composition, and f) Use of one or more of magnesium hydroxide, magnesium carbonate, magnesium hydroxycarbonate, or manganese carbonate in an amount of 0.25 to 5.0% by weight of the composition, wherein the silicone rubber composition contains the following components, i.e. a) One or more polyorganosiloxanes containing at least two unsaturated groups selected from alkenyl groups and alkynyl groups per molecule, and having a viscosity in the range of 1,000 mPa.s to 100,000 mPa.s at 25°C, b) Organosilicon compounds having at least two or at least three Si-H groups per molecule; c) A silica-reinforced filler that has been optionally hydrophobized, d) A hydrosilylation catalyst containing or consisting of a platinum group metal or a compound thereof, The invention also provides a means of reducing the compression set of a silicone elastomer material obtained from the curing of the composition, as measured according to the industrial standard ISO 815-1 Method A.

[0018] Ingredient (a) Component (a) of the composition is one or more polyorganosiloxanes containing at least two unsaturated groups selected from alkenyl groups and alkynyl groups per molecule, and having a viscosity in the range of 1,000 mPa.s to 100,000 mPa.s at 25°C.

[0019] Component (a) is a polydiorganosiloxane, such as a polydiorganosiloxane having at least two unsaturated groups per molecule, and these unsaturated groups are selected from alkenyl groups or alkynyl groups. Alternatively, component (a) has at least three unsaturated groups per molecule.

[0020] The unsaturated group of component (a) may be at the terminal, pendant, or both positions.

[0021] The alkenyl group may have 2 to 30, 2 to 24, 2 to 20, 2 to 12, 2 to 10, or 2 to 6 carbon atoms. Possible alkenyl groups are, but are not limited to, vinyl, allyl, methallyl, propenyl, and hexenyl groups, as well as cyclohexenyl groups.

[0022] The alkynyl group may have 2 to 30, 2 to 24, 2 to 20, 2 to 12, 2 to 10, or 2 to 6 carbon atoms. The alkynyl group is not limited to, but examples include the ethynyl, propynyl, and butynyl groups.

[0023] Component (a) is given by formula (I):R' a SiO (4-a) / 2 (I) has multiple units, In the formula, each R' is independently selected from an aliphatic hydrocarbyl group or an aliphatic non-halogenated organyl group (an organyl group is any aliphatic organic substituent having one free valence on a carbon atom, regardless of the type of functional group). Saturated aliphatic hydrocarbyls are exemplified, but are not limited to, alkyl groups such as methyl, ethyl, propyl, pentyl, octyl, undecyl, and octadecyl, and cycloalkyl groups such as cyclohexyl. Unsaturated aliphatic hydrocarbyls are exemplified, but are not limited to, the above-mentioned alkenyl and alkynyl groups. Aliphatic non-halogenated organyl groups are exemplified, but are not limited to, suitable nitrogen-containing groups such as amide and imide groups, and oxygen-containing groups such as polyoxyalkylene groups, carbonyl groups, alkoxy groups, and hydroxyl groups. The subscript "a" is 0, 1, 2, or 3, and typically in this case a is mainly 2, but may include several units in which a is 1 or 3.

[0024] Siloxy units can be denoted by abbreviated nomenclature, namely "M", "D", "T", and "Q", where R' is as described above, or an alkyl group, typically a methyl group, the M unit is a siloxy unit in the formula where a=3, i.e., R'3SiO 1 / 2 This corresponds to the D unit, which is the siloxy unit where a=2 in the formula, i.e., R'2SiO 2 / 2 This corresponds to the siloxy unit where a=1 in the formula, i.e., R'1SiO 3 / 2 This corresponds to the siloxy unit where a=0 in the formula, i.e., SiO 4 / 2 This corresponds to the polydiorganosiloxane, such as polyorganosiloxane, of component (a), which is substantially linear, but may contain a certain proportion of branching due to the presence of T units (as described above) within the molecule, and therefore the average value of the subscript a in structure (I) is approximately 2.

[0025] Typical R' groups on one or more polyorganosiloxanes containing at least two unsaturated groups selected from alkenyl and alkynyl groups per molecule include mainly alkyl groups, particularly methyl and ethyl, or methyl groups. In addition to the necessary at least two unsaturated groups selected from alkenyl and / or alkynyl groups, typically alkenyl groups, aryl and / or fluoroalkyl groups, such as trifluoropropyl or perfluoroalkyl groups, can also be included. These groups may be in pendant positions (on D or T siloxy units) or terminal positions (on M siloxy units).

[0026] Therefore, the polymer chain of component (a) may be selected from polydimethylsiloxane, alkylmethylpolysiloxane, alkylarylpolysiloxane, or copolymers thereof (the reference to alkyl means any suitable alkyl group or an alkyl group having two or more carbon atoms), provided that each component (a) polymer contains at least two alkenyl groups and / or alkynyl groups, typically at least two alkenyl groups. Such polymer chains may have any suitable end groups, for example, trialkyl ends, alkenyl dialkyl ends, alkynyl dialkyl ends, or be terminated with any other suitable combination of end groups, provided that each polymer contains at least two unsaturated groups per molecule, selected from alkenyl and alkynyl groups. In one embodiment, the end groups of such polymers do not contain any silanol end groups.

[0027] Therefore, component (a) is, for example, the following: These may be dialkylalkenyl-terminated polydimethylsiloxanes, for example, dimethylvinyl-terminated polydimethylsiloxanes; dialkylalkenyl-terminated dimethylmethylphenylsiloxanes, for example, dimethylvinyl-terminated dimethylmethylphenylsiloxanes; trialkyl-terminated dimethylmethylvinylpolysiloxanes; dialkylvinyl-terminated dimethylmethylvinylpolysiloxane copolymers; dialkylvinyl-terminated methylphenylpolysiloxanes; dialkylalkenyl-terminated methylvinylmethylphenylsiloxanes; dialkylalkenyl-terminated methylvinyldiphenylsiloxanes; dialkylalkenyl-terminated methylvinylmethylphenyldimethylsiloxanes; trimethyl-terminated methylvinylmethylphenylsiloxanes; or trimethyl-terminated methylvinylmethylphenyldimethylsiloxanes.

[0028] Component a) has a viscosity of 1,000 mPa.s to 100,000 mPa.s at 25°C, or 5,000 mPa.s to 75,000 mPa.s at 25°C, or 10,000 mPa.s to 60,000 mPa.s at 25°C, and is preferably present in an amount of 25 to 60% by weight of the composition, or 30 to 60% by weight of the composition, or 35 to 55% by weight of the composition. Viscosity can be measured using either a Brookfield® rotational viscometer with a spindle LV-4 (designed for viscosities in the range of 1,000 to 2,000,000 mPa.s) at 25°C and an appropriate rpm for viscosities exceeding 15,000 mPa.s, or a Brookfield® rotational viscometer with a cone plate configuration using a cone CP-52 at an appropriate rpm and 25°C for viscosities up to 15,000 mPa.s.

[0029] Ingredient (b) Component (b) functions as a crosslinking agent and is provided in the form of an organosilicon compound having at least two or at least three Si-H groups per molecule. Component (b) typically contains three or more silicon-bonded hydrogen atoms, which may react with the unsaturated alkenyl and / or alkynyl groups of component (a) to form a network structure, thereby curing the composition. Alternatively, if polymer (a) has more than two unsaturated groups per molecule, some or all of component (b) may have two silicon-bonded hydrogen atoms per molecule.

[0030] The molecular structure of organosilicon compound (b), which has at least two or at least three Si-H groups per molecule, is not particularly limited. It may be a polyorganosiloxane that may have a linear chain, a branched chain (a linear chain with several branches via the presence of T groups), a cyclic chain, or a silicone resin system.

[0031] The molecular weight of component (b) is not particularly limited, but its viscosity is typically 5 to 50,000 mPa.s at 25°C using the test method described for component (a).

[0032] The silicon-bonded organic groups used in component (b) can be exemplified by alkyl groups such as methyl, ethyl, propyl, n-butyl, t-butyl, pentyl, hexyl; aryl groups such as phenyl, tolyl, xylyl, or similar aryl groups; 3-chloropropyl, 3,3,3-trifluoropropyl, or similar halogenated alkyl groups, and can preferably be an alkyl group having 1 to 6 carbons, particularly a methyl, ethyl, or propyl group, or a phenyl group. Preferably, the silicon-bonded organic group used in component (b) is an alkyl group, or a methyl group, an ethyl group, or a propyl group.

[0033] Examples of the organosilicon compound (b) having at least two or at least three Si-H groups per molecule include, but are not limited to, the following: (a’) Trimethylsiloxy-terminated methylhydrogen polysiloxane, (b’) Trimethylsiloxy-terminated polydimethylsiloxane-methylhydrogensiloxane, (c’) Copolymer of dimethylhydrogensiloxy-terminated dimethylsiloxane-methylhydrogensiloxane, (d’) Cyclic copolymer of dimethylsiloxane-methylhydrogensiloxane, (e’)(CH3)2HsiO 1 / 2 unit, (CH3)3SiO 1 / 2 unit, and SiO 4 / 2 unit copolymer and / or silicone resin, (f’)(CH3)2HsiO 1 / 2 unit, and SiO 4 / 2 unit copolymer and / or silicone resin, (g’) Methylhydrogensiloxane cyclic homopolymer having 3 to 10 silicon atoms per molecule.

[0034] Alternatively, component (b) which is a crosslinking agent can be a filler, for example, silica treated with one of the above, and mixtures thereof.

[0035] In one embodiment, component (b) is selected from methylhydrogenpolysiloxane with trimethylsiloxy groups sealed at both ends; a copolymer of methylhydrogensiloxane and dimethylsiloxane with trimethylsiloxy groups sealed at both ends; dimethylsiloxane with dimethylhydrogensiloxy groups sealed at both ends; and a copolymer of methylhydrogensiloxane and dimethylsiloxane with dimethylhydrogensiloxy groups sealed at both ends.

[0036] The crosslinking agent (b) is generally present in the hydrosilylated curable silicone rubber composition such that the molar ratio of the total number of silicon-bonded hydrogen atoms in component (b) to the total number of alkenyl groups and / or alkynyl groups in component (a) is 0.5:1.0 to 10.0:1.0. If this ratio is less than 0.5:1, a sufficiently cured composition cannot be obtained. If this ratio exceeds 10:1, the hardness of the cured composition tends to increase when heated. Preferably, the amount of component (b) is such that the molar ratio of silicon-bonded hydrogen atoms in component (b) to alkenyl groups / alkynyl groups, or alkenyl groups in component (a) is in the range of 0.7:1.0 to 5.0:1.0, or 0.9:1.0 to 2.5:1.0, or even 0.9:1.0 to 2.0:1.0.

[0037] The silicon-bonded hydrogen (Si-H) content of component (b) is determined using quantitative infrared analysis in accordance with ASTM E168. In the present invention, the ratio of silicon-bonded hydrogen to alkenyl (vinyl) and / or alkynyl is important when it depends on the hydrosilylation curing process. Generally, this is determined by calculating the total weight % of alkenyl groups in the composition, e.g., vinyl [V] and the total weight % of silicon-bonded hydrogen [H] in the composition, where if the molecular weight of hydrogen is 1 and the molecular weight of vinyl is 27, the molar ratio of silicon-bonded hydrogen to vinyl is 27 [H] / [V].

[0038] Typically, depending on the number of unsaturated groups in component (a) and the number of Si-H groups in component (b), component (b) is present in an amount of 0.1 to 10% by weight of the hydrosilylated curable silicone rubber composition, or 0.1 to 7.5% by weight of the hydrosilylated curable silicone rubber composition, or 0.5 to 7.5% by weight of the hydrosilylated curable silicone rubber composition, or even 0.5% to 5% by weight.

[0039] Ingredient (c) Component (c) is optionally hydrophobized silica-reinforced filler. The reinforced filler of component (c) may be exemplified by fumed silica and / or precipitated silica and / or colloidal silica. In one alternative example, fumed silica, precipitated silica and / or colloidal silica are provided in a pulverized form.

[0040] Precipitated silica, fumed silica, and / or colloidal silica have relatively high surface areas, especially when provided in a finely powdered form, typically at least 50 m². 2 This is particularly preferable because it is calculated as / g (BET method according to ISO9277:2010). Typically, 50-450m 2 / g (BET method according to ISO9277:2010), or 50-300m 2 Use a filler with a surface area of ​​ / g (BET method according to ISO9277:2010). All of these types of silica are commercially available.

[0041] If the silica-reinforced filler (c) is originally hydrophilic (for example, an untreated silica filler), it is typically treated with a treatment agent to make it hydrophobic. These surface-modified silica-reinforced fillers (c) do not aggregate, and the surface treatment allows the filler to be easily wetted by component (a), so they can be homogeneously incorporated into the polydiorganosiloxane polymer (a) described below.

[0042] Typically, the silica-reinforced filler (c) may be surface-treated with any low molecular weight organosilicon compound disclosed in the Art that is applicable to prevent creping of the liquid silicone rubber (LSR) composition during processing. For example, organosilanes, polydiorganosiloxanes, or organosilazanes, such as hexaalkyldisilazanes and short-chain siloxane diols, which make the silica-reinforced filler (c)( Examples of silanes include, but are not limited to, phenyl,MePh)siloxanes, liquid hydroxyldimethyl-terminated polydiorganosiloxanes containing an average of 2 to 20 repeating units of diorganosiloxane in each molecule, hexaorganodisiloxanes such as hydroxyldimethyl-terminated phenylmethylsiloxane and hexamethyldisiloxane, divinyltetramethyldisiloxane; hexaorganodisilazanes such as hexamethyldisilazane (HMDZ), divinyltetramethyldisilazane, and tetramethyldi(trifluoropropyl)disilazane; hydroxyldimethyl-terminated polydimethylmethylvinylsiloxane, octamethylcyclotetrasiloxane, and silanes including, but not limited to, methyltrimethoxysilane, dimethyldimethoxysilane, vinyltrimethoxysilane, methyltriethoxysilane, vinyltriethoxysilane, chlorotrimethylsilane, dichlorodimethylsilane, and trichloromethylsilane.In one embodiment, the treatment agent may be selected from silanol-terminated vinylmethyl (ViMe)siloxane, liquid hydroxyldimethyl-terminated polydiorganosiloxane containing an average of 2 to 20 repeating units of diorganosiloxane in each molecule, hexaorganodisiloxanes such as hexamethyldisiloxane, divinyltetramethyldisiloxane; hexaorganodisilazanes such as hexamethyldisilazane (HMDZ), divinyltetramethyldisilazane and hydroxydimethyl-terminated polydimethylmethylvinylsiloxane, octamethylcyclotetrasiloxane, and silanes including methyltriethoxysilane, dimethyldiethoxysilane, and / or vinyltriethoxysilane, but not particularly limited. A small amount of water may be added together with the silica treatment agent as a processing aid.

[0043] The surface treatment of the untreated silica-reinforced filler (c) may be carried out before its introduction into the composition, or in situ (i.e., by blending these materials together at room temperature or above, in the presence of at least some of the other materials of the composition herein, until the filler is completely treated). Typically, the untreated silica-reinforced filler (c) is treated in situ with a treatment agent in the presence of material (a) to prepare a base material for silicone rubber that can later be mixed with other components.

[0044] The silica-reinforced filler (c) may optionally be present in amounts of up to 40% by weight of the composition, or 1.0 to 40% by weight of the composition, or 5.0 to 35% by weight of the composition, or 10.0 to 35% by weight of the composition.

[0045] Ingredient (d) Component (d) of the composition is a hydrosilylation catalyst comprising or consisting of a platinum group metal or a compound thereof. These are usually selected from catalysts of platinum group metals (platinum, ruthenium, osmium, rhodium, iridium, and palladium) or one or more compounds of such metals. Alternatively, platinum and rhodium compounds are preferred due to the high activity levels of these catalysts in hydrosilylation reactions, with platinum compounds being the most preferred. In hydrosilylation (or addition) reactions, hydrosilylation catalysts such as component (d) herein catalyze the reaction between an unsaturated group, usually an alkenyl group, such as vinyl, and a Si-H group.

[0046] The catalyst (d) may be a platinum group metal, and may be a platinum group metal deposited on a support, such as activated carbon, a metal oxide such as aluminum oxide or silicon dioxide, silica gel or powdered charcoal, or a compound or complex of a platinum group metal. Preferably, the platinum group metal is platinum.

[0047] Examples of preferred hydrosilylation catalysts (d) include platinum-based catalysts, e.g., platinum black, platinum oxide (Adams catalyst), platinum on various solid carriers, chloroplatinic acid, e.g., hexachloroplatinic acid (Pt oxidation state IV) (Speier catalyst), chloroplatinic acid in solution of alcohol, e.g., isooctanolic acid or amyl alcohol (Lamoreaux catalyst), and complexes of chloroplatinic acid with ethylenically unsaturated compounds, e.g., olefins, and organosiloxanes containing ethylenically unsaturated silicon-bonded hydrocarbon groups, e.g., tetra-vinyl-tetramethylcyclotetrasiloxane-platinum complex (Ashby catalyst). Examples of usable soluble platinum compounds include platinum-olefin complexes of the formula (PtCl2.(olefin)2 and H(PtCl3.olefin)), in which case the use of alkenes having 2 to 8 carbon atoms, such as ethylene, propylene, butene isomers and octene isomers, or cycloalkanes having 5 to 7 carbon atoms, such as cyclopentene, cyclohexene, and cycloheptene, is preferred. Other soluble platinum catalysts include, for example, platinum-cyclopropane complexes of the formula (PtCl2C3H6)2. These are reaction products of hexachloroplatinic acid with alcohols, ethers, and aldehydes, or mixtures thereof, or reaction products of hexachloroplatinic acid and / or its conversion products with vinyl-containing siloxanes such as methylvinylcyclotetrasiloxane in an ethanolic solution in the presence of sodium bicarbonate. Platinum catalysts having phosphorus and amine ligands, such as (Ph3P)2PtCl2, and platinum complexes with vinylsiloxanes such as sym-divinyltetramethyldisiloxane can also be used.

[0048] Therefore, suitable specific examples of platinum-based catalysts include: (i) A complex of chloroplatinic acid with an organosiloxane containing an ethylenically unsaturated hydrocarbon group, as described in U.S. Patent No. 3,419,593. (ii) Chloroplatanic acid in either hexahydrate or anhydrous form, (iii) A platinum-containing catalyst obtained by a method comprising reacting chloroplatinic acid with an aliphatic unsaturated organosilicon compound such as divinyltetramethyldisiloxane, (iv) Alkene-platinum-silyl complexes described in U.S. Patent No. 6,605,734, such as (COD)Pt(SiMeCl2)2 (wherein "COD" is 1,5-cyclooctadiene), and / or (v) Examples include a platinum divinyltetramethyldisiloxane complex containing approximately 1% by weight of platinum in a vinylsiloxane polymer having a viscosity of approximately 200 to 750 mPa·s, using the test method described for Karstedt catalyst and component (a).

[0049] While solvents such as organic solvents like toluene have historically been used as alternatives, the use of vinylsiloxane polymers is a far more preferred choice. These are described in U.S. Patents 3,715,334 and 3,814,730. In one preferred embodiment, component (d) may be selected from platinum coordination compounds. In one embodiment, hexachloroplatinic acid and its conversion products with vinyl-containing siloxanes, Karstedt catalysts, and Speier catalysts are preferred.

[0050] Component (d) is typically present in an amount of platinum atoms that provides 0.1 to 500 ppm (parts per million) relative to the weight of the reactive raw materials components (a) and (b). The catalyst may be added as a single type or as a mixture of two or more different types. Typically, depending on the form / concentration in which the catalyst is provided, the amount of catalyst present is in the range of 0.05 to 1.5% by weight of the composition, or 0.05 to 1.0% by weight of the composition, or 0.1 to 1.0% by weight of the composition, or 0.1 to 0.5% by weight of the composition, and the platinum catalyst is provided in a masterbatch of a polymer such as (a) above.

[0051] Ingredient (e) Component e) is, (i) Phthalocyanine compounds or metal derivatives of such compounds, wherein the metal is copper, nickel, cobalt, iron, manganese, chromium, zinc, platinum, palladium, and vanadium, and optionally, (ii) One or more compounds selected from diacylhydrazide compounds A compression set additive selected from, This compression set additive is present cumulatively in amounts of 0.02% to 3.5% by weight of the composition (i.e., (i) + (ii)).

[0052] Component (e)(i) is a phthalocyanine compound or a metal derivative of such a compound, where the metal is copper, nickel, cobalt, iron, manganese, chromium, zinc, platinum, palladium, or vanadium, for example, a phthalocyanine compound may have the following structure:

[0053] [ka]

[0054] Metallic phthalocyanines, such as copper phthalocyanine, are shown below.

[0055] [ka]

[0056] In one embodiment, component (e)(i) comprises or consists of copper phthalocyanine. Any suitable form of copper phthalocyanine can be used, for example, pigment 15:3 beta-type or 15:4 beta-type copper phthalocyanine, or 15.2 alpha-type copper phthalocyanine. 15:1 alpha-type copper phthalocyanine is suitable if it is sufficiently stable. 15:3 beta-type or 15:4 beta-type copper phthalocyanine is particularly preferred.

[0057] The phthalocyanine compound or a metal derivative of such compound, which is component (e)(i), is present in the composition in an amount of 0.02% to 2.5% by weight, or 0.02% to 2.0% by weight.

[0058] However, it should be noted that it may be delivered alone or in a masterbatch or mixture with a suitable polydimethylsiloxane, for example, a dimethylvinyl-terminated polydimethylsiloxane having a viscosity of 1,000 mPa.s to 25,000 mPa.s at 25°C. For example, copper phthalocyanine in a dimethylvinyl-terminated polydimethylsiloxane having a viscosity of 1,000 mPa.s to 25°C, in a mixture comprising 10 to 50% by weight of copper phthalocyanine, with the remainder being a dimethylvinyl-terminated polydimethylsiloxane having a viscosity of 1,000 mPa.s to 15,000 mPa.s at 25°C. Specific examples include 30% by weight copper phthalocyanine in vinyldimethylsiloxy-terminated polydimethylsiloxane having a viscosity of approximately 9000 mPa.s at 25°C (using a cone-plate configuration with a Cone CP-52 and a Brookfield® rotational viscometer at 3 rpm) and 15% by weight copper phthalocyanine in vinyldimethylsiloxy-terminated polydimethylsiloxane having a viscosity of approximately 2000 mPa.s at 25°C (using a cone-plate configuration with a Cone CP-52 and a Brookfield® rotational viscometer at 3 rpm). In such cases, when provided in the form of such a masterbatch or mixture, the masterbatch or mixture may be introduced into the composition in an amount of 0.2 to 5% by weight of the composition, and such a masterbatch or mixture may contain about 10 to 50% by weight of component (e)(i), with the remainder being a preferred polydimethylsiloxane.

[0059] If component (e)(ii) is present, it is one or more compounds selected from the diacylhydrazide series.

[0060] Diacylhydrazide compounds are represented by the following general formula:

[0061] [ka] In the formula, R 1 and R 2These may be the same or different, and may be a hydrogen atom, a hydroxyl group, an alkyl group, a substituted alkyl group, an aryl group, a phenol group, or a similar substituted aryl group, aralkyl group, or substituted aralkyl group. 1 and R 2 It is preferable that the compound contains an aryl group, a phenol, or a monovalent hydrocarbon group containing a similarly substituted aryl group. Specific examples of the above diacylhydrazide compounds include the following: N,N'-diformylhydrazine, N,N'-diacetylhydrazine, N,N'-dipropionylhydrazine, N,N'-butyrylhydrazine, N-formyl-N'-acetylhydrazine, N,N'-dibenzoylhydrazine, N,N'-ditoluylhydrazine, N,N'-disalithyroylhydrazine, N-H These include lumil-N'-disalityloylhydrazine, N-formyl-N'-butyl-substituted salicyloylhydrazine, N-acetyl-N'-salityloylhydrazine, N,N'-bis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionyl]hydrazine, di-(N'-salityloyl)hydrazine adipate, or dodecanedioyl-di-(N'-salityloyl)hydrazine.

[0062] Examples of commercially manufactured compounds include N,N'-bis-[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionyl]hydrazine, sold by Ciba Specialty Chemicals as Irganox® MD1024, and dodecanedi-oil-di-(N'-salicyloyl)hydrazine, which is synonymous with 1-N',12-N'-bis(2-hydroxybenzoyl)dodecanedihydrazide, sold by Adeka as ADK STAB® CDA-6 (hereinafter referred to as CDA-6).

[0063] One alternative ingredient (e)(ii) is dodcadioyl-di-(N'-salicyloyl)hydrazine.

[0064] If component (e)(ii) is present, it is added in an amount of 0.001 to 1.0% by weight of the composition, or 0.001 to 0.5% by weight of the composition, or 0.01 to 0.5% by weight of the composition, or 0.02 to 0.5% by weight of the composition.

[0065] The compression set additive (e) is present cumulatively (i.e., in (i) + (ii)) in amounts of 0.02% to 3.5% by weight of the composition, or 0.1% to 3.5% by weight of the composition, or 0.2% to 3.0% by weight of the composition.

[0066] However, when calculated based on the presence of component (e)(i) present in the masterbatch / mixture with a suitable polysiloxane polymer, the compression set additive (e) (i.e., (e)(i) masterbatch / mixture + (ii)) is 0.2% to 5.0% by weight of the composition, or 0.2% to 5.0% by weight of the composition, or 0.25 to 5.0% by weight of the composition, or 0.25 to 4.0% by weight of the composition, or 0.25 to 3.0% by weight of the composition, or 0.25 to 2.0% by weight of the composition.

[0067] Component (f) is one or more of magnesium hydroxide, magnesium carbonate, magnesium hydroxycarbonate, or manganese carbonate. Magnesium carbonate and magnesium hydroxycarbonate are particularly preferred.

[0068] These may include one or more magnesium carbonates selected from magnesite (MgCO3), verlintonite (MgCO3.2H2O), nesquihonite (MgCO3.3H2O), lancefordite (MgCO3.5H2O), as well as one or more hydroxymagnesium carbonates such as pocrovskite (Mg2(CO3)(OH)2.0.5H2O), altinite (Mg2(CO3)(OH)2.3H2O), hydromagnesite (Mg5(CO3)4(OH)2.4H2O), sometimes called light magnesium carbonate, dipingite (Mg5(CO3)4(OH)2.5H2O), giorgiosite (Mg5(CO3)4(OH)2.5-6H2O), and shelcovite (Mg7(CO3)5(OH)4.24H2O). Component (f) is present in the composition in an amount of 0.25 to 5.0% by weight of the composition, or 0.25 to 4.0% by weight of the composition, or 0.25 to 3.0% by weight of the composition, or 0.25 to 2.0% by weight of the composition.

[0069] Optional additives Such hydrosilylated curable silicone rubber compositions may also contain one or more optional additives depending on the intended application. Examples include curing inhibitors, release agents, adhesion catalysts, peroxides, conductive fillers, thermally conductive fillers, pot life extenders, lubricants, release agents, UV light stabilizers, bactericides, and wetting agents.

[0070] Hardening inhibitor Curing inhibitors are used, if necessary, to prevent or delay the addition reaction curing process, particularly during storage. Optional addition reaction inhibitors for platinum-based catalysts are well known in the art and include hydrazines, triazoles, phosphines, mercaptans, organic nitrogen compounds, acetylene alcohols, silylated acetylene alcohols, maleates, fumarates, ethylenically or aromatically unsaturated amides, ethylenically unsaturated isocyanates, olefinic siloxanes, unsaturated hydrocarbon monoesters and diesters, conjugated en-yines, hydroperoxides, nitriles, and diaziridines. Alkenyl-substituted siloxanes, such as those described in U.S. Patent No. 3,989,667, may also be used, of which cyclic methylvinylsiloxanes are preferred.

[0071] One known type of hydrosilylation inhibitor is an acetylene compound disclosed in U.S. Patent No. 3,445,420. Acetylene alcohols such as 2-methyl-3-butyne-2-ol constitute a preferred type of inhibitor that suppresses the activity of platinum-containing catalysts at 25°C. Typically, compositions containing these inhibitors need to be heated to temperatures above 70°C to cure at a practical rate.

[0072] Examples of acetylene alcohols and their derivatives include 1-ethynyl-1-cyclohexanol (ETCH), 2-methyl-3-butyne-2-ol, 3-butyne-1-ol, 3-butyne-2-ol, propargyl alcohol, 1-phenyl-2-propyne-1-ol, 3,5-dimethyl-1-hexyne-3-ol, 1-ethynylcyclopentanol, 3-methyl-1-penten-4-in-3-ol, and mixtures thereof. Examples of derivatives of acetylene alcohols include these compounds having at least one silicon atom.

[0073] If present, a low inhibitor concentration of approximately 1 mole per mole of catalyst metal provides satisfactory storage stability and curing rate. In other cases, an inhibitor concentration of up to 500 moles per mole of catalyst metal is required. The optimal concentration of a given inhibitor in a given composition can be easily determined by routine experiments. Depending on the concentration and form in which the selected inhibitor is commercially available, if present in the composition, the inhibitor is typically present in an amount of 0.0125 to 10% by weight of the composition.

[0074] In one embodiment, the inhibitor, if present, is selected from 1-ethynyl-1-cyclohexanol (ETCH) and / or 2-methyl-3-butyne-2-ol and is present in an amount greater than 0 to 0.1% by weight of the composition.

[0075] Lubricant As described above, the types of compositions described herein are often used as electrical connectors. Such electrical connectors are often made from self-lubricating silicone elastomers designed to gradually seep out over time from a cured seal and lubricate the cable and connector assembly. In such situations, polyphenylmethylsiloxane and its copolymers are typically used as lubricants. Examples of other lubricants that may be used alternatively or additionally include tetrafluoroethylene, resin powders, graphite, graphite fluoride, talc, boron nitride, fluorinated oils, and mixtures or derivatives thereof. If such lubricants are present, they may be present in an amount of 1 to 4% by weight of the composition.

[0076] In one embodiment, the compositions of this specification are free of urea in an amount of 0.005 to 0.2% by weight of the composition and / or free of cyanuric acid, biuret, or a mixture thereof in an amount of 0.005 to 0.2% by weight of the composition.

[0077] Therefore, in one alternative example, the present disclosure provides a silicone rubber composition comprising any preferred combination of the following components: a) One or more polyorganosiloxanes containing at least two unsaturated groups selected from alkenyl and alkynyl groups per molecule, having a viscosity in the range of 1,000 mPa.s to 100,000 mPa.s at 25°C, or 5,000 mPa.s to 75,000 mPa.s at 25°C, or 10,000 mPa.s to 60,000 mPa.s at 25°C, preferably present in an amount of 25 to 60% by weight of the composition, or 30 to 60% by weight of the composition, or 35 to 55% by weight of the composition. The viscosity can be measured at 25°C using a Brookfield® rotary viscometer with a spindle LV-4 (designed for viscosities in the range of 1,000 to 2,000,000 mPa.s), with the speed adjusted according to the polymer viscosity. b) An organosilicon compound having at least two or at least three Si-H groups per molecule, which may be present in an amount of 0.1 to 10% by weight of the silicone rubber composition, or 0.1 to 7.5% by weight of the silicone rubber composition, or 0.5 to 7.5% by weight of the composition, or further, 0.5% to 5% by weight of the organosilicon compound, c) A silica-reinforced filler, preferably in a finely divided form, optionally hydrophobized, and having a large surface area, typically at least 50 m² / g (BET method according to ISO 9277:2010). A filler having a surface area of ​​50-450 m² / g (BET method according to ISO 9277:2010) or 50-300 m² / g (BET method according to ISO 9277:2010), typically present in an amount of up to 40% by weight of the composition, or 1.0-40% by weight of the composition, or 5.0-35% by weight of the composition, or 10.0-35% by weight of the composition. d) A hydrosilylation catalyst comprising or consisting of a platinum group metal or a compound thereof, wherein the amount of the catalyst is in the range of 0.001 to 3.0% by weight of the composition, or 0.001 to 1.5% by weight of the composition, or 0.001 to 1.5% by weight of the silicone rubber composition, depending on the form / concentration in which the catalyst is provided. e) Compression set additives, (i) Phthalocyanine compounds or metal derivatives of such compounds, wherein the metal is copper, nickel, cobalt, iron, manganese, chromium, zinc, platinum, palladium, and vanadium, and optionally, (ii) One or more compounds selected from diacylhydrazide compounds Selected from, Compression set additives present cumulatively (i.e., in (i) + (ii)) in amounts of 0.02% to 3.5% by weight of the composition, or 0.1% to 3.5% by weight of the composition, or 0.2% to 3.0% by weight of the composition, and f) One or more of magnesium hydroxide, magnesium carbonate, hydroxymagnesium carbonate, or manganese carbonate in an amount of 0.25 to 5.0% by weight of the composition, or 0.25 to 4.0% by weight of the composition, or 0.25 to 3.0% by weight of the composition, However, the total weight percentage of the composition is 100% by weight. The composition may also contain one or more of the above optional additives in specified amounts, where again, the total weight percentage of the composition is 100% by weight.

[0078] The above hydrosilylated curable silicone rubber compositions are typically stored in two or more parts before use. In the case of a two-part composition, the two parts are typically referred to as part (A) and part (B). Part (A) typically contains a catalyst (d) in addition to a polyorganosiloxane (a) and, if present, a silica-reinforced filler (c). Part (B) typically comprises a crosslinking agent component (b), an optional inhibitor if present, and the remaining polyorganosiloxane (a) and / or silica-reinforced filler (c).

[0079] It is important that catalyst (d) be stored separately from crosslinking agent (b) to prevent premature hardening during storage.

[0080] Components (e)(i) and / or (e)(ii), and / or component (f) may be stored in either Part (A) or Part (B), or separately or together in both, provided that they do not adversely affect each other or the storage of any of the essential raw materials present in each part. Alternatively, if desired, components (e)(i) and / or (e)(ii) may be added to the remaining composition, i.e., when mixing the Part (A) composition and the Part (B) composition together before use, or thereafter, to the combination of the Part (A) composition and the Part (B) composition.

[0081] Any optional additive other than the inhibitors mentioned above may be present in either part (A) or part (B), or both, provided that it does not adversely affect the storage of any of the essential raw materials present in each part.

[0082] The composition can be designed to be mixed in any preferred weight ratio; for example, parts (A) and (B) can be mixed together in a ratio of 10:1 to 1:10, 5:1 to 1:5, or 2:1 to 1:2, but the most preferred weight ratio is 1:1.

[0083] Each raw material / component of part (A) and / or part (B) may be mixed together individually in their respective parts, or they may be introduced into the composition in pre-prepared combinations, for example, to facilitate mixing of the final composition. For example, components (a) and (c) are often mixed together to form an LSR polymer base or masterbatch before introducing other raw materials. These may then be mixed with other raw materials in the part being manufactured directly, or they may be used to produce a pre-prepared concentrate, commonly referred to in the industry as a masterbatch.

[0084] In this case, to facilitate the mixing of the raw materials, one or more masterbatches can be used to successfully mix the raw materials and form the composition of part (A) and / or part (B). For example, a "fumed silica" masterbatch can be prepared, which is efficiently an LSR silicone rubber base containing a silica-reinforced filler (c) processed in situ.

[0085] Parts A and B of the composition can be prepared by combining all of their respective components at ambient temperature. For this purpose, any mixing techniques and apparatus described in the prior art can be used. The specific apparatus used will depend on the components and the viscosity of the final composition. Suitable mixers include, but are not limited to, kneader mixers, static mixers in liquid injection molding machines, Z-blade mixers, two-roll mills (open mills), three-roll mills, Haake® Rheomix OS Lab mixers, single-screw or twin-screw extruders, etc. Alternatively, speed mixers such as the DC150.1FV, DAC400FVZ, or DAC600FVZ, sold by Hauschild, may be used. It may also be desirable to cool the components during mixing to avoid premature curing of the composition.

[0086] Before use, mix the respective (A) and (B) components together in the desired ratio.

[0087] The hydrosilylated curable silicone rubber composition on the substrate can be cured, for example, in a mold, and molded parts can be formed by injection molding, for example, using a liquid injection molding system (LIMS), press molding, extrusion molding, transfer molding, press vulcanization, or calendering. Compression set test specimens can be molded into a suitable shape, for example, a cylindrical disc with a diameter of 29.0 mm ± 0.5 mm and a thickness of 12.5 mm ± 0.5 mm, which is then compressed by 25% to a thickness of approximately 9.38 mm. These may be prepared in a mold or cut from a press sheet of silicone elastomer material.

[0088] Under compression, LSR buttons (pre-cured at 175°C for 10 minutes) were held at a suitable high temperature for a suitable time, typically 22 hours, between two metal plates in a convection oven. After the compression was released, the specimen was allowed to recover to a thickness close to the starting thickness, and the compression set was determined.

[0089] Hydrosilylated curable silicone rubber compositions are cured at any suitable temperature, for example, 80°C to 200°C, or about 100°C to 180°C, or about 120°C to 180°C. As mentioned above, one standard method for reducing compression set has historically been post-curing, aimed at reducing the number of curable groups that can be cured under compression. Surprisingly, the compositions defined herein have been found not to particularly benefit from the post-curing process, as will be further discussed below.

[0090] In the case of the process for producing the two-part silicone rubber composition described above, the process is: (i) A step of preparing a silicone-based composition comprising component (a) polymer and (c) silica-reinforced filler, (ii) Dividing the obtained base into two parts, namely part (A) and part (B), introducing catalyst (d) into part (A), and introducing crosslinking agent (b) and inhibitor (if present) into the part (B) composition, (iii) A step of introducing any other optional additive which is a different component into either or both of parts (A) and (B), (iv) The step of storing the (A) and (B) compositions separately may be included.

[0091] In the alternative process, component (e) or component (e)(i) is not introduced into either component (A) or component (B) when they are separate, but rather introduced as part of the mixing process when the (A) component and the (B) component are mixed together before use, for example, during mixing before injection molding.

[0092] Typically, to avoid premature curing, the (A) and (B) components are thoroughly mixed in the preferred weight ratio described above immediately before use. Then, the curing process is carried out.

[0093] When component (e) or component (e)(i) is introduced together with parts (A) and (B) during the mixing process, typically the weight ratio of parts (A) and (B) remains the same. For example, when parts (A) and (B) are mixed in a 1:1 weight ratio, there may be, for example, 49.5% by weight of parts (A) and (B), and 1% by weight of component (e) or component (e)(i), which were mixed together before molding.

[0094] Therefore, it was found that when one or more of component (f), magnesium hydroxide, magnesium carbonate, magnesium hydroxycarbonate, and manganese carbonate, are introduced into the silicone rubber composition of this specification in an amount of 0.25 to 5.0% by weight of the composition, the compression set results are remarkably improved when used in combination with component (e). It was also revealed that component (f) may be introduced into component (A), component (B), component (A) and component (B), and / or mixed with component (e) or component (e)(i) and introduced together when introduced separately from parts (A) and (B) as described above.

[0095] The low compression set silicone elastomer compositions and methods described herein are useful in applications such as acting as barriers to prevent the absorption or penetration of air, dust, noise, liquids, gaseous substances, or contaminants. Silicone elastomer materials having low compression set as described herein may be used in gaskets.

[0096] They are also used in a wide range of electrical and / or insulating applications. In electrical applications, they can be useful in wiring / cable wiring / power supplies, etc. For example, silicone elastomer materials obtained from the compositions described herein can be used in a variety of applications, for example, as silicone coatings for standard non-silicone insulators, for example for safety cables, and as cable coatings for cable accessories such as electrical connectors, terminals, and wire seals. Electrical connectors are generally used to create closed electrical circuits in automotive, residential, and infrastructure environments due to their excellent balance of mechanical properties, chemical and thermal stability, ease of processing, and the availability of self-lubricating formulations. They can be used to mat rigid thermoplastic housing components to electrically and environmentally isolate connector joints from, for example, possible moisture, oil, fuel, and corrosive gases. Silicone elastomers produced using the compositions described herein have appropriately low compression set at high temperatures and provide electrical connectors, etc., with the above-mentioned mechanical integrity and dimensional stability, exhibiting excellent sealing performance throughout their service life.

[0097] Such electrical connectors, terminals, and wire seals may be used in automotive applications for electric vehicle (EV) battery packs, EV batteries, and control units within EVs, for example, in motor control unit (MCU) devices, lamp housings, fuse boxes, air filters, waterproof connectors, air conditioners, lighting devices, and electronic components. They may also be used in or for spark plugs, for example, in spark plug boots for combustion engines.

[0098] Other applications include external waterproofing and installations designed for drip / drop irrigation (e.g., micro-irrigation systems that slowly drip water and nutrients onto plant roots from above or buried below the soil surface). Therefore, they are used in the manufacture of automotive parts such as cable fittings, electrical and electronic components, packaging components, structural components such as sealants, and household product components. [Examples]

[0099] Unless otherwise specified, all viscosities were measured at 25°C. In the following examples, unless otherwise noted, the viscosity of individual components was measured using a Brookfield® rotational viscometer at an appropriate rpm for viscosities exceeding 15,000 mPa.s, with a spindle LV-4 (designed for viscosities in the range of 1,000 to 2,000,000 mPa.s), and for viscosities up to 15,000 mPa.s, using a Brookfield® rotational viscometer at an appropriate rpm in a cone-plate configuration with a cone CP-52.

[0100] All compression set results were guaranteed according to Method A of the industrial standard ISO 815-1:2019, which compresses cylindrical discs with a diameter of 29.0 ± 0.5 mm and a thickness of 12.5 mm ± 0.5 mm by 25% to a thickness of approximately 9.38 mm. Under compression, LSR buttons (previously cured at 175°C for 10 minutes) were held at a high temperature between two metal plates in a convection oven for the time shown in the table below, after which the compression was released and the test specimen was restored to a thickness close to the starting thickness to determine the compression set.

[0101] Three types of A-part and B-part compositions were prepared based on the two-part liquid silicone rubber elastomer compositions (Elas.1, Elas.2, and Elas.3) shown in Table 1 as standard starting compositions.

[0102] [Table 1]

[0103] Table 1 shows, Masterbatch 1: Masterbatch 1 is, Using a spindle LV-4 and a Brookfield™ rotational viscometer at 6 rpm, 70.8 parts by weight of dimethyl vinyl-terminated polydimethylsiloxane had a viscosity of approximately 53,000 mPa.s at 25°C. 22.4 parts by weight, 300m 2 It contains hydrophobic fumed silica having a surface area of ​​ / g. The silica is hydrophobic and does not contain vinyl functional groups. Masterbatch 2: Masterbatch 2 is, Using a spindle LV-4 and a Brookfield™ rotational viscometer at 6 rpm, 66.6 parts by weight of dimethylvinylsiloxy-terminated polydimethylsiloxane had a viscosity of approximately 55 Pa.s at 25°C. 25.8 parts by weight, 300m 2 It contains hydrophobic fumed silica having a surface area of ​​ / g. The silica is hydrophobic and has approximately 0.178 mmol / g of vinyl functional groups.

[0104] The values ​​given for parts by weight are not percentages, and therefore do not need to add up to 100.

[0105] Polymer 1: Polymer 1 is a vinyldimethyl-terminated polydimethylsiloxane with a viscosity of 53,000 mPa.s at 25°C, as measured using a Brookfield™ rotational viscometer at 6 rpm with a spindle LV-4.

[0106] Polymer 2: Polymer 2 is a vinyl-terminated poly(dimethylsiloxane-co-methylvinylsiloxane) with a viscosity of 370 mPa·s at 25°C, measured using a Brookfield™ rotary viscometer at 12 rpm in a cone-plate configuration with a CP-52 cone.

[0107] Crosslinking agent 1: Crosslinking agent 1 was a trimethyl-terminated polymethylhydrogen dimethylsiloxane, which had a viscosity of 30 mPa.s at 25°C, measured using a Brookfield™ rotary viscometer at 12 rpm in a cone-plate configuration with a CP-52 cone.

[0108] Release agent: The release agent was determined to be a hydroxydimethyl-terminated polydimethylsiloxane with a viscosity of approximately 21 mPa·s at 25°C, as measured using a Brookfield™ rotational viscometer at 12 rpm with a spindle LV-2.

[0109] Cyclotetrasiloxane: The cyclotetrasiloxane was tetravinyl-tetramethyl-cyclotetrasiloxane.

[0110] Phenylmethylsiloxane copolymer: The phenylmethylsiloxane copolymer was a trimethylsilyl-terminated phenylmethylsiloxane dimethylsiloxane copolymer with a viscosity of 125 mPa·s at 25°C, measured using a Brookfield™ rotary viscometer at 12 rpm in a cone-plate configuration with a CP-52 cone.

[0111] CDA6: CDA6 is dodecanedi-oil-di-(N'-salicyloyl)hydrazine, a synonym for 1-N',12-N'-bis(2-hydroxybenzoyl)dodecanedihydrazide, and is marketed by Adeka as ADK STAB(trademark) CDA-6.

[0112] Each was used separately. The (A) composition and the (B) composition were mixed together in a 1:1 weight ratio. Except for the examples and comparative examples prepared using Elas.3 which contained a small amount of CDA-6 in the B composition, in the examples herein the compositions were prepared by adding the compression set additives (e)(i), (e)(ii), and / or (e)(iii) when the relevant (A) composition and (B) composition were mixed together, or thereafter. Thus, in Ex.2, in which a total amount of 4.6% by weight was introduced, the final cured mixture was a combination of 47.7% (A) as defined in Table 1 above, 47.7% (B) as defined in Table 1 above, and different amounts of compression set additives.

[0113] Using the above-mentioned compositions A and B of Elas.1, the test samples shown in Table 2 below were prepared.

[0114] [Table 2]

[0115] In the table, Cupc additive 1 is a mixture of 30% by weight copper phthalocyanine in vinyldimethylsiloxy-terminated polydimethylsiloxane having a viscosity of approximately 9000 mPa·s at 25°C. MgCO3(1) was light magnesium carbonate (Mg5(CO3)4(OH)2.4H2O) sold by Sigma-Aldrich under product number 13118 (Basic Magnesium Carbonate (Pure, Light, Mg 40% or more (as MgO), Light, Powder (Light))).

[0116] Unless otherwise specified, the obtained silicone rubber was not post-cured. Post-cured samples were cured at 200°C for 4 hours. Unless otherwise specified, all compression set results below were determined according to International Organization for Standardization (ISO) Test 815-1:2019 Method A as described above. After curing, elastomers prepared using the compositions listed in Table 2a were compressed at 175°C for 22 hours.

[0117] [Table 3]

[0118] Comparative Examples 1, Ex.1, and Ex.2 all show improvement in compression set compared to the reference sample, but the combination of CDA-6, copper phthalocyanine, and magnesium carbonate in Ex.2 shows the best compression set result after 22 hours.

[0119] In a further series of examples and comparative examples, basic compositions were prepared using parts A and B of Elas.3, and samples were prepared according to the compositions shown in Table 3a.

[0120] [Table 4]

[0121] Cupc additive 2 was a 15% by weight copper phthalocyanine mixture in vinyldimethylsiloxy-terminated polydimethylsiloxane, having a viscosity of approximately 2000 mPa·s at 25°C (measured using a Brookfield® rotational viscometer at 3 rpm in a cone-plate configuration with a Cone CP-52). The presence of 3% by weight of Cupc additive 2 is equivalent to the 0.45% by weight of copper phthalocyanine present in the composition.

[0122] [Table 5]

[0123] Increasing the amount of CDA-6 did not improve the compression set. In fact, it appears that increasing the abundance of CDA-6 may worsen the results.

[0124] It should be noted that Comparative Examples 2 and 3 yielded worse results than Comparative Example 1 in Table 2b, which is considered to support the clear negative effect of the presence of CDA-6. In Examples Ex.3 to 6, a positive effect of CuPc was observed. The presence of both magnesium carbonate and magnesium hydroxide improved the results, but the composition containing magnesium carbonate yielded better overall results.

[0125] In Comparative Example 5, the post-hardening effect of magnesium carbonate was observed. Therefore, it can be seen that while there is a synergistic effect when CuPc is combined with magnesium carbonate and magnesium hydroxide, the combination of CuPc and magnesium carbonate appears to be superior.

[0126] In Ex.4 and Ex.5, virtually identical results were obtained, which was expected given that the two were different samples with the same composition. Ex.6 had the same composition, but the material was post-cured, and perhaps surprisingly, the further improvement observed after post-curing was minimal. Therefore, Examples 4 and 5 exhibited excellent initial compression set even without post-curing.

[0127] Test samples were prepared using the compositions shown in Table 4a, and a further series of experiments were conducted. In these examples, the post-curing effect was considered to be the effect of magnesium carbonate alone in combination with CDA-6 present in the original composition.

[0128] [Table 6]

[0129] Table 4b shows the results of compression set over various time periods using elastomers prepared from the above composition at 175°C.

[0130] [Table 7]

[0131] Table 4b shows that, compared to Comparative Examples 6 and Ex.7, respectively, the post-curing methods shown in Comparative Examples 7 and Ex.8 did not result in any significant improvement in compression set after compression at 175°C, regardless of the duration of curing (22 to 1008 hours). Comparative Example 8, which contained only magnesium carbonate added to Elas.3, had the worst compression set despite post-curing. Comparative Examples 6 and 7 contained compositions without magnesium carbonate and showed improved results compared to Comparative Example 8. In particular, Ex.7 and Ex.8, which contained a combination of CDA-6 from elas.3, copper phthalocyanine, and magnesium carbonate, showed far superior results after 1008 hours of compression.

[0132] A further series of compositions shown in Table 5a were prepared and cured, and then a further series of experiments were conducted. In this case, Elas.2 was used as specified in Table 1. Therefore, the Elas.2 basic compositions used did not contain any compression set additives.

[0133] [Table 8]

[0134] In the above, MgCO3(2) was dipingite (Mg5(CO3)4(OH)2.5H2O), which is sometimes called heavy magnesium carbonate.

[0135] [Table 9]

[0136] It is understood that the use of copper phthalocyanine is necessary to achieve excellent long-term compression set performance. The use of magnesium carbonate shows a slight improvement over pure CuPc. The presence of CDA-6 appears to be beneficial for initial compression set, but the positive effect seems to become much less significant over longer periods, and ultimately seems to have an almost certainly negative impact on compression set, in which case CuPc / MgCO3 appears to be the optimal choice.

Claims

1. A silicone rubber composition comprising the following components, namely, a) One or more polyorganosiloxanes containing at least two unsaturated groups selected from alkenyl groups and alkynyl groups per molecule, and having a viscosity in the range of 1,000 mPa·s to 100,000 mPa·s at 25°C, b) Organosilicon compounds having at least two or at least three Si-H groups per molecule, c) A silica-reinforced filler that has been optionally hydrophobized, d) A hydrosilylation catalyst containing or consisting of a platinum group metal or a compound thereof, e) Compression set additive, (i) Phthalocyanine compounds or metal derivatives of such compounds, wherein the metal is copper, nickel, cobalt, iron, manganese, chromium, zinc, platinum, palladium, and vanadium, and optionally, (ii) One or more compounds selected from diacylhydrazide compounds Selected from, Compression set additives, which are present cumulatively (i.e., in (i) + (ii)) in an amount of 0.02% to 3.5% by weight of the composition, and f) comprising 0.25 to 5.0% by weight of one or more of magnesium hydroxide, magnesium carbonate, magnesium hydroxycarbonate, or manganese carbonate, A silicone rubber composition in which the total weight percentage of the aforementioned composition is 100% by weight.

2. The silicone rubber composition according to claim 1, wherein component (e)(i) is copper phthalocyanine present in the composition in an amount of 0.02% to 2.5% by weight of the composition.

3. The silicone rubber composition according to any one of claims 1 to 2, wherein component (e)(i) is delivered alone or in a masterbatch or mixture with a dimethyl vinyl-terminated polydimethylsiloxane having a viscosity of 1,000 mPa·s to 25,000 mPa·s at 25°C.

4. The silicone rubber composition according to any one of claims 1 to 3, wherein component (f) is magnesium carbonate, magnesium hydroxycarbonate, or a mixture thereof in an amount of 0.25 to 5.0% by weight of the composition.

5. The magnesium carbonate, magnesium hydroxycarbonate, or mixture is MgCO ３ , MgCO ３ .2H ２ O, MgCO ３ .3H ２ O, MgCO ３ .5H ２ O, Mg ２ (CO ３ )(OH) ２ .0.5H ２ O, Mg ２ (CO ３ )(OH) ２ .3H ２ O, Mg ５ (CO ３ ) ４ (OH) ２ .4H ２ O, Mg ５ (CO ３ ) ４ (OH) ２ .5H ２ O, Mg ５ (CO ３ ) ４ (OH) ２ .5 - 6H ２ O, and Mg ７ (CO ３ ) ５ (OH) ４ .24H ２ O, and the silicone rubber composition according to claim 4, selected from.

6. The silicone rubber composition according to any one of claims 1 to 5, wherein component (e) and (ii) are present in an amount of 0.001 to 1.0% by weight of the composition.

7. A silicone elastomer material which is a curing product of the above hydrosilylated curable silicone rubber composition, having a compression set of 20% or less after compression at 175°C for 22 hours, as measured according to the industrial standard ISO 815-1 Method A.

8. A process for manufacturing a silicone elastomer material, comprising the following components, namely, a) One or more polyorganosiloxanes containing at least two unsaturated groups selected from alkenyl groups and alkynyl groups per molecule, and having a viscosity in the range of 1,000 mPa·s to 100,000 mPa·s at 25°C, b) Organosilicon compounds having at least two or at least three Si-H groups per molecule, c) A silica-reinforced filler that has been optionally hydrophobized, d) A hydrosilylation catalyst containing or consisting of a platinum group metal or a compound thereof, e) Compression set additive, (i) Phthalocyanine compounds or metal derivatives of such compounds, wherein the metal is copper, nickel, cobalt, iron, manganese, chromium, zinc, platinum, palladium, and vanadium, and optionally, (ii) One or more compounds selected from diacylhydrazide compounds Selected from, Compression set additives, which are present cumulatively (i.e., in (i) + (ii)) in an amount of 0.02% to 3.5% by weight of the composition, and f) One or more of magnesium hydroxide, magnesium carbonate, magnesium hydroxycarbonate, or manganese carbonate in an amount of 0.25 to 5.0% by weight of the composition, A step of mixing a hydrosilylated curable silicone rubber composition having, The process involves the total weight percentage of the composition being 100% by weight, A process comprising the step of curing the composition at a temperature of 80°C to 200°C.

9. Component (f) is magnesium carbonate, magnesium hydroxycarbonate, or a mixture thereof, MgCO ３ , MgCO ３ 2H ２ O, MgCO ３ 3H ２ O, MgCO ３ . 5H ２ O, Mg ２ (CO ３ ) (OH) ２ 0.5H ２ O, Mg ２ (CO ３ ) (OH) ２ 3H ２ O, Mg ５ (CO ３ ) ４ (OH) ２ 4H ２ O, Mg ５ (CO ３ ) ４ (OH) ２ . 5H ２ O, Mg ５ (CO ３ ) ４ (OH) ２ 5-6H ２ O, and Mg ７ (CO ３ ) ５ (OH) ４ 24H ２ A process for producing a silicone elastomer material according to claim 8, selected from O.

10. A silicone elastomer material obtained or obtainable from a process comprising the steps of mixing a hydrosilylated curable silicone rubber composition according to any one of claims 1 to 6, and curing the composition at a temperature of 80°C to 200°C, A silicone elastomer material having a compression set of 20% or less when measured according to the industrial standard ISO 815-1 Method A after compression at 175°C for 22 hours.

11. In a silicone rubber composition, e) Compression set additive, (i) Phthalocyanine compounds or metal derivatives of such compounds, wherein the metal is copper, nickel, cobalt, iron, manganese, chromium, zinc, platinum, palladium, and vanadium, and optionally, (ii) One or more compounds selected from diacylhydrazide compounds Selected from, Compression set additives, which are present cumulatively (i.e., in (i) + (ii)) in an amount of 0.02% to 3.5% by weight of the composition, and f) One or more of magnesium hydroxide, magnesium carbonate, magnesium hydroxycarbonate, or manganese carbonate in an amount of 0.25 to 5.0% by weight of the composition, The use of the silicone rubber composition, wherein the silicone rubber composition otherwise comprises the following components, namely, a) One or more polyorganosiloxanes containing at least two unsaturated groups selected from alkenyl groups and alkynyl groups per molecule, and having a viscosity in the range of 1,000 mPa·s to 100,000 mPa·s at 25°C, b) Organosilicon compounds having at least two or at least three Si-H groups per molecule, c) A silica-reinforced filler that has been optionally hydrophobized, d) A hydrosilylation catalyst containing or consisting of a platinum group metal or a compound thereof, The composition includes, and is used as a means to reduce the compression set of the silicone elastomer material obtained from the curing of the composition, as measured according to the industrial standard ISO 815-1 Method A.

12. The magnesium carbonate, magnesium hydroxycarbonate, or mixture is MgCO ３ 、MgCO ３ ·2H ２ O、MgCO ３ ·3H ２ O、MgCO ３ ·5H ２ O、Mg ２ (CO ３ )(OH) ２ ·0.5H ２ O、Mg ２ (CO ３ )(OH) ２ ·3H ２ O、Mg ５ (CO ３ ) ４ (OH) ２ ·4H ２ O、Mg ５ (CO ３ ) ４ (OH) ２ ·5H ２ O、Mg ５ (CO ３ ) ４ (OH) ２ ·5 - 6H ２ O、and Mg ７ (CO ３ ) ５ (OH) ４ ·24H ２ O, and the use according to claim 11, selected from

13. Use of the silicone elastomer material according to claim 7 or 10 in the manufacture of automotive parts, such as cable accessories, electrical and electronic components, packaging components, structural components such as sealants, household components, and gasket sealants.

14. The use of the silicone elastomer material according to claim 12, wherein the cable accessories are electrical connectors, electrical terminals, and wire seals.

15. Use of the curable silicone rubber composition according to any one of claims 1 to 6 in the manufacture of or for the manufacture of automotive parts, cable accessories, electrical and electronic components, packaging parts, structural components such as sealants, household components, and gasket sealants.

Images