Silicone-thermoplastic composite article

Abstract

A method of maintaining the durability over time of a silicone-thermoplastic composite article comprising a thermoplastic material free of flame retardant and a silicone elastomer material by incorporating a stabilizing additive in the silicone elastomer material. The disclosure also extends to an improved silicone-thermoplastic composite article and to the use of such silicone-thermoplastic composite article.

Description

[0001] This disclosure relates to silicone-thermoplastic composite articles and methods for maintaining the durability of silicone-thermoplastic composite articles comprising flame-retardant-free thermoplastic and silicone elastomer materials over time by incorporating stabilizing additives into silicone elastomer materials. This disclosure also extends to the use of such silicone-thermoplastic composite articles.

[0002] Curable silicone rubber compositions are known in the art and are used to prepare silicone elastomer materials with 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 silicone elastomers suitable for a wide range of electrical and / or insulating applications.

[0003] For example, silicone elastomers made from liquid silicone rubber (LSR) or high-consistency rubber (HCR) have been used in a variety of silicone-thermoplastic composite articles, which combine thermoplastic and silicone elastomer materials. The physical properties of the flame-retardant-free thermoplastic and silicone elastomer materials provide composite articles with advantageous properties that would not be present if one or the other were used as a substitute for the composite. However, depending on the application in which the composite is used, the physical properties and durability of the silicone elastomer in direct contact with the flame-retardant-free thermoplastic can be negatively affected, particularly when the composite article is subjected to heat and when the silicone elastomer is subjected to compressive forces during use. For example, at high temperatures (e.g., >85°C or alternatively >150°C), species from the flame-retardant-free thermoplastic can leach from the plastic and diffuse into the silicone elastomer, and in some cases, can degrade the silicone elastomer, negatively impacting its physical properties, such as increased compressive deformation.

[0004] Taking two commonly used thermoplastic materials in silicone-thermoplastic composite products as examples, it is suspected that polyamide 66 (PA66) may release species such as adipic acid or carboxylic acid oligomers, and polybutylene terephthalate (PBT) may release esters of terephthalic acid, esters of benzoic acid, terephthalic acid and benzoic acid, etc. due to thermal degradation when such composites are used at high temperatures.

[0005] It is also known that PBT contains low molecular weight species that can be released even before thermal degradation events. These species may contain acidic or -OH end groups inherent in the original material, which can selectively migrate to the surface of the thermoplastic and diffuse into the silicone elastomer during compression heat aging.

[0006] Due to the excellent balance of mechanical properties, chemical and thermal stability, and ease of processing, silicone elastomers are among the most common applications of silicone-thermoplastic composite materials in articles of interest as seals in or for use with electrical or electronic connectors, typically used to create closed circuits in automotive, residential, and infrastructure environments. Such electrical or electronic connectors can be used to mate with rigid thermoplastic housing assemblies to form a tight connection that provides both electrical and environmental isolation to the connector joint, creating a closed circuit in environments such as automotive, residential, and infrastructure.

[0007] Such electrical or electronic connectors can be used, for example, in motor vehicles that increasingly rely on electrical and electronic systems, particularly with the development of electric and hybrid vehicles. In these applications, silicone rubber seals are subjected to mechanical compression and high temperatures, and may be exposed to moisture, oil and fuel, corrosive gases, and the presence of effluents from the contact material (e.g., thermoplastic housing), but must maintain their mechanical integrity and dimensional stability to provide adequate sealing performance throughout their service life, thereby preventing electrical failures.

[0008] Unwanted electrical faults can cause malfunctions or damage to devices such as radios, lights, and ventilation systems. This is because such devices rely on the aforementioned silicone rubber material as a sealant to prevent electrical failures.

[0009] Silicone-thermoplastic composite products can also be used in other applications where the cured silicone is used to seal, passivate, or protect parts of components from environmental and mechanical challenges, including heat, moisture, dust, and vibration, as exemplified by cap seals and adhesives for electronic module housings; gaskets or seals for radiator tanks or headlight assemblies; and potting or encapsulating agents for electrical or electronic components found in automotive, marine, aerospace, or other industrial applications.

[0010] Therefore, for silicone elastomer materials, it is important to maintain their physical properties to ensure the durability of both the silicone elastomer material itself and the silicone-thermoplastic composite products. One of the most important physical properties that silicone rubber materials need to maintain is low compressive strength for applications requiring, for example, environmental and electrical insulation and / or thermal stability.

[0011] Compression deformation is the thermally induced fatigue behavior of silicone elastomer materials, which can be defined as the loss of the silicone elastomer material's ability to recover to its initial thickness after being compressed for a specific period of time at a set (elevated) temperature. Compression deformation values ​​can be measured, for example, according to industry standard ASTM D395-18 methods A, B, or C, and determined as a percentage, such that if complete recovery exists, i.e., if the thickness of the test sample is the same before and after the application of load, the compression deformation value is 0%; conversely, if the 25% compression applied to the silicone elastomer material during the test remains unchanged upon removal of the load, the compression deformation is 100%, because it failed to fully recover to its initial shape.

[0012] Many silicone elastomer materials exhibit significant compressive deformation, such as greater than 50% or even greater than 60% after compression for a short period of time, such as 22 hours, even at temperatures of 125°C and 150°C. They may suffer from problems due to the corresponding changes in shape and / or a significant increase in hardness during prolonged use in high-temperature applications unless they undergo a post-curing heating process.

[0013] "Post-curing" is the most straightforward way to minimize compression set, in which silicone materials that have been hydrogenated or peroxide-cured are subjected to post-curing heating at 150°C or higher for several hours (e.g., four hours or more). However, given the required capital investment, post-curing is generally not commercially desirable or truly feasible due to the increased energy consumption and manufacturing time delays it requires.

[0014] Many of the applications mentioned above typically require silicone elastomer materials with the lowest possible (e.g., no more than 40%) compressive deformation values ​​over a wide temperature range.

[0015] In the United States, electrical connector systems must meet the requirements of the SAE International USCAR-2 "Performance Specifications for Automotive Electrical Connector Systems" testing regime. Hermetically sealed connector assemblies are classified to ensure their suitability for a given temperature range meets a relevant automotive specification. Currently, five ranges are certified as T1-T5:

[0016] T1 is a temperature class ranging from -40℃ to +85℃;

[0017] T2 is the temperature range from -40℃ to +100℃;

[0018] T3 is the temperature range from -40℃ to +125℃;

[0019] T4 represents a temperature range of -40°C to +150°C; and the current highest rating is...

[0020] T5 is for use from -40°C to 175°C.

[0021] Considering that post-curing of each silicone elastomer is not desirable after curing, various additives have been proposed as alternatives to reduce compressive deformation.

[0022] However, industrial and vehicle components and modules are increasingly subjected to mechanical compression and exposed to increasing operating temperatures above 125°C.

[0023] Therefore, in silicone-thermoplastic composite products (e.g., in connector sealing applications), silicone elastomer materials used in combination with flame-retardant-free thermoplastics may suffer premature seal failure after direct contact with flame-retardant-free thermoplastics.

[0024] The purpose of this disclosure is to provide a means for maintaining the durability of silicone-thermoplastic composite articles comprising a thermoplastic material without flame retardants and a silicone elastomer material over time.

[0025] This article provides an organosilicon-thermoplastic composite article, which comprises...

[0026] (i) A flame-retardant-free thermoplastic article, wherein the flame-retardant-free thermoplastic article has a usable surface, and

[0027] (ii) A cured silicone elastomer portion that is in direct contact with the usable surface of the flame-retardant-free thermoplastic article (i), wherein the silicone elastomer portion is a cured product of a silicone elastomer composition comprising 0.25% by weight to a maximum of 5% by weight of a stabilizing additive selected from the group consisting of: magnesium carbonate, magnesium hydroxycarbonate, magnesium oxide, and mixtures thereof.

[0028] A method for manufacturing an organosilicon-thermoplastic composite article according to the above description is also provided, the method comprising:

[0029] (a) A curable silicone elastomer composition comprising 0.25% by weight to a maximum of 5% by weight of a stabilizing additive selected from the group consisting of: magnesium carbonate, hydroxymagnesium carbonate, magnesium oxide, and mixtures thereof.

[0030] (b) Curing the curable elastomer composition into a mold.

[0031] (c) Physically bond the cured silicone elastomer to an available surface of a flame-retardant-free thermoplastic article (i) to form a silicone-thermoplastic composite article.

[0032] A method for manufacturing organosilicon-thermoplastic composite articles as described above is also provided, the method comprising:

[0033] (a) A curable silicone elastomer composition comprising 0.25% by weight to a maximum of 5% by weight of a stabilizing additive selected from the group consisting of: magnesium carbonate, hydroxymagnesium carbonate, magnesium oxide, and mixtures thereof.

[0034] (b) Bringing the curable silicone elastomer composition into contact with a usable surface of the flame-retardant-free thermoplastic article (i).

[0035] (c) Curing the curable silicone elastomer composition in contact with the usable surface of the flame-retardant thermoplastic article to form a silicone-thermoplastic composite article.

[0036] A method for manufacturing an organosilicon-thermoplastic composite article is also provided, wherein the organosilicon-thermoplastic composite article comprises

[0037] (i) Thermoplastic articles free of flame retardants,

[0038] The flame-retardant-free thermoplastic article has a usable surface; and

[0039] (ii) a silicone elastomer portion, wherein the silicone elastomer portion is physically bonded to the available surface of the flame-retardant-free thermoplastic;

[0040] The method includes:

[0041] (1) A curable silicone elastomer composition is provided, the curable silicone elastomer composition comprising a silicone elastomer composition curable by hydrogenation silanization reaction or a silicone elastomer composition curable by free radical reaction.

[0042] The curable silicone elastomer composition further comprises 0.25% by weight to a maximum of 5.0% by weight of stabilizing additives selected from the group consisting of: magnesium carbonate, hydroxy magnesium carbonate, magnesium oxide, and mixtures thereof;

[0043] (2) Introduce the desired amount of the curable silicone elastomer composition into a mold.

[0044] (3) Curing the curable silicone elastomer composition to form (ii) the silicone elastomer portion;

[0045] (4) Physically bond (ii) the silicone elastomer seal to (i) the available surface of the flame-retardant-free thermoplastic article, thereby forming the silicone-thermoplastic composite material.

[0046] In one embodiment of the latter, the silicone-thermoplastic composite article is an electrical connector or electronic connector, which includes...

[0047] (ia) One or more electrical wires;

[0048] (ib) An electrical connector housing or electronic connector housing, comprising a thermoplastic material free of flame retardants.

[0049] The electrical connector housing or electronic connector housing has a first (outer) usable surface and a second (inner) surface opposite to the outer surface.

[0050] The second (inner) surface defines a cavity, and

[0051] The cavity contains one or more wires (ia); and

[0052] The silicone elastomer portion (ii) is a silicone elastomer seal, wherein the silicone elastomer seal is physically bonded to the first (outer) surface of the electrical connector housing or electronic connector housing (ib).

[0053] A method is also provided for maintaining the durability of a silicone elastomer portion in physical contact with a flame-retardant-free thermoplastic, the silicone elastomer portion being subjected to mechanical compression and exposure to temperatures greater than 85°C during use, the method comprising the following steps:

[0054] (1') A curable silicone elastomer composition is prepared, wherein the curable silicone elastomer composition further comprises 0.25% to a maximum of 5.0% by weight of a stabilizing additive selected from the group consisting of: magnesium carbonate, magnesium hydroxycarbonate, magnesium oxide, and mixtures thereof.

[0055] (2') Introduce the desired amount of the curable silicone elastomer composition into the mold.

[0056] (3') Curing the curable silicone elastomer composition to form the silicone elastomer portion (ii);

[0057] (4') Physically bond the silicone elastomer portion (ii) to the available surface of the electrical connector housing or electronic connector housing (ib) to form the electrical connector or electronic connector.

[0058] In the above method, there may be a step (5') which includes connecting the electrical connector or electronic connector to the connector joint of the circuit via (i) one or more wires, thereby providing environmental and electrical insulation for the one or more wires (ia).

[0059] In addition, the electrical connector can be heated at a temperature of ≥125°C for 1008 hours, wherein the silicone elastomer seal is in a compressed state, for example, 25%.

[0060] Also provided are silicone-thermoplastic composite articles prepared by the above method. These can be automotive parts, cable accessories, such as electrical or electronic connectors with silicone elastomer seals, electrical components, electronic components, packaging components, building components, household components, or gaskets.

[0061] It also includes an organosilicon-thermoplastic composite article, which comprises...

[0062] (i) Thermoplastic articles free of flame retardants,

[0063] The flame-retardant-free thermoplastic article has a usable surface; and

[0064] (ii) a silicone elastomer seal, wherein the silicone elastomer seal is physically bonded to (i) the available surface of the thermoplastic article;

[0065] In use, subjecting the silicone elastomer seal to mechanical compression and exposure to temperatures greater than 85°C can be achieved through a method including the following steps: -

[0066] (1') A curable silicone elastomer composition is prepared, the curable silicone elastomer composition being selected from silicone elastomer compositions that can be cured by hydrosilylation reaction or silicone elastomer compositions that can be cured by free radical reaction, wherein the curable silicone elastomer composition further comprises 0.25% by weight to a maximum of 5.0% by weight of stabilizing additives selected from the group consisting of: magnesium carbonate, magnesium hydroxycarbonate, magnesium oxide, and mixtures thereof.

[0067] (2') Introduce the desired amount of the curable silicone elastomer composition into the mold.

[0068] (3') Curing the curable silicone elastomer composition to form the silicone elastomer seal (ii).

[0069] A method is also provided for preventing degradation of silicone elastomer seals that come into physical contact with thermoplastics without flame retardants, the silicone elastomer seals being subjected to mechanical compression and exposed to temperatures greater than 125°C during use, the method comprising the following steps:

[0070] (1') A curable silicone elastomer composition is prepared, the curable silicone elastomer composition being selected from silicone elastomer compositions that can be cured by hydrosilylation reaction or silicone elastomer compositions that can be cured by free radical reaction, wherein the curable silicone elastomer composition further comprises 0.25% by weight to a maximum of 5.0% by weight of stabilizing additives selected from the group consisting of: magnesium carbonate, magnesium hydroxycarbonate, magnesium oxide, and mixtures thereof.

[0071] (2') Introduce the desired amount of the curable silicone elastomer composition into the mold.

[0072] (3') Curing the curable silicone elastomer composition to form the silicone elastomer seal (ii)

[0073] (4') Physically engage the silicone elastomer seal (ii) with the available surface of the electrical connector housing or electronic connector housing (ib), thereby forming the electrical connector or electronic connector.

[0074] Also provided is a silicone elastomer portion that is subjected to mechanical compression and exposed to temperatures greater than 85°C during use. This silicone elastomer seal is obtained by a method comprising the following steps:

[0075] (1') A curable silicone elastomer composition is prepared by selecting a silicone elastomer composition that can be cured by hydrosilylation reaction or a silicone elastomer composition that can be cured by free radical reaction, wherein the curable silicone elastomer composition further comprises 0.25% to a maximum of 5.0% by weight of a stabilizing additive selected from the group consisting of: magnesium carbonate, magnesium hydroxycarbonate, magnesium oxide, and mixtures thereof.

[0076] (2') Introduce the desired amount of the curable silicone elastomer composition into the mold.

[0077] (3') Curing the curable silicone elastomer composition to form the silicone elastomer portion (ii).

[0078] Use of 0.25% by weight to a maximum of 5.0% by weight of additives selected from the group consisting of: magnesium carbonate, hydroxymagnesium carbonate, magnesium oxide, and mixtures thereof, wherein the flame-retardant-free thermoplastic is subjected to mechanical compression and exposed to temperatures greater than 85°C during use, wherein the silicone elastomer seal is further formed from a curable silicone elastomer composition selected from a silicone elastomer composition that can be cured by hydrosilylation reaction or a silicone elastomer composition that can be cured by free radical reaction.

[0079] Surprisingly, it has been identified that the problem encountered when attempting to combine silicone elastomer materials with flame-retardant-free thermoplastics in silicone-thermoplastic composite articles (e.g., in connector sealing applications), namely the need to prevent premature failure of silicone elastomer seals after direct contact with flame-retardant-free thermoplastics, can be overcome by introducing a stabilizing additive in the form of 0.25% to a maximum of 5.0% by weight of an additive selected from the group consisting of magnesium carbonate, hydroxymagnesium carbonate, magnesium oxide, and mixtures thereof.

[0080] The addition of stabilizing additives maintains the durability (e.g., mechanical integrity and dimensional stability) of the silicone elastomer portion in silicone-thermoplastic composite articles, including flame-retardant-free thermoplastics, because although the additive migrates into the silicone elastomer, it appears to maintain the physical properties of the silicone elastomer, such as compression set. For example, it prevents any significant deterioration of the compression set of the silicone elastomer in silicone elastomer seals that are subjected to mechanical compression during use and exposed to temperatures greater than 85°C, alternatively greater than 100°C, and alternatively greater than 125°C. Silicone-thermoplastic composite articles as described herein are prepared using silicone elastomers prepared from the compositions described herein combined with any suitable flame-retardant-free thermoplastic.

[0081] Flame-retardant-free thermoplastics are commonly used in silicone-thermoplastic composite articles to form rigid components, wherein the silicone elastomer is molded or otherwise dispensed into a desired shape designed to form a tight bond on and / or around the thermoplastic article. Typically, the silicone elastomer is supplied in a sealed form designed to be combined with the rigid, flame-retardant-free component to provide environmental and electrical insulation at the connector joint.

[0082] Flame retardant-free thermoplastics can be, for example, condensation polymers containing polyamides such as nylon, for example, nylon 6 (PA6), nylon 6,6 (PA6,6), heat-resistant nylon 6T / 6,6 (PA6T / 6,6), nylon 6 / 10 (PA6 / 10), nylon 6 / 12 (PA6 / 12), nylon 11 (PA11), nylon 12 (PA12), etc., as well as polyoxymethylene, polyphenylene sulfide (PPS), polyacetal, polyamide-imide, polyphthalamide, polyetherimide, polyetherketone, polyetheretherketone, polyetherketoneetherketone, polyoxymethylene (acetal) homopolymer copolymers, syndiotactic polystyrene (sPS), and compatibilizing blends of sPS and polyamides. Condensation polymers, such as polyesters, including polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyarylates (PAR), etc.; polycarbonate (PC) (including impact-modified polycarbonate); polyethers, such as polyphenylene ether (PPO), maleic anhydride-grafted polyphenylene ether (PPO), maleic anhydride-grafted olefin elastomers and plasmons, polysulfone, polyethersulfone, polyarylsulfone, polyphenylene ether, etc.; polypropylene, polyethylene, aliphatic polyketone (PK) thermoplastic styrene copolymers, such as acrylonitrile styrene acrylate (ASA), acrylonitrile butadiene styrene (ABS), and styrene acrylonitrile (SAN); polymethyl methacrylate (PMMA), polyoxymethylene (POM). Preferably, this method is provided for use in combination with PA6, PA6,6, PA6T / 6,6, PBT, PC, and PK, particularly PA6, PA6,6, PA6T / PA6,6, and PBT. Thermoplastics may also contain about 25% to 35% glass fiber (GF) as a reinforcing additive, such as PA6-GF25, PA6,6-GF25, PA6T / 6,6-GF33, PK-GF30 and PBT-GF30.

[0083] To avoid any doubt, the term "flame retardant free" is intended to refer to thermoplastics that do not contain flame retardants, meaning that no flame retardant additives have been intentionally added to the body of the thermoplastic.

[0084] Silicone elastomers used in silicone-thermoplastic composite articles are typically molded or otherwise disposed into a desired shape designed to form a tight bond on and / or around a flame-retardant-free thermoplastic article. It is presumed that when tightly bonded to a flame-retardant-free thermoplastic, species from the flame-retardant-free thermoplastic migrate into the silicone elastomer, adversely affecting the chemical structure of the silicone elastomer and thus adversely affecting the loss of compressive deformation in the silicone elastomer when in direct contact with the flame-retardant-free thermoplastic in the silicone-thermoplastic composite article.

[0085] As described herein, it has been surprisingly determined that the inclusion of 0.25% to up to 5.0% by weight of stabilizing additives selected from the group consisting of magnesium carbonate, magnesium hydroxycarbonate, magnesium oxide, and mixtures thereof in curable silicone elastomer compositions used in the preparation of silicone elastomers maintains their durability and prevents premature failure of silicone elastomer components (such as seals) by significantly improving the physical properties (such as the retention of compression set) of silicone elastomers used, for example, in combination with flame-retardant-free thermoplastics in the aforementioned silicone-thermoplastic composite articles. This is particularly surprising because other materials such as magnesium hydroxide (Mg(OH)2), zinc oxide (ZnO), and calcium carbonate (CaCO3) have not shown any effect. Similarly, acid scavengers such as disodium phosphate (Na2HPO4) or conventional antioxidants and high-temperature compression set additives such as iron(III) oxide (Fe2O3) and copper phthalocyanine complexes do not provide any benefit.

[0086] Although not bound by this assumption, it is proposed that species migrate from flame-retardant-free thermoplastics into silicone elastomers via solid-state diffusion, and that these species cause degradation of the silicone matrix, resulting in poor physical properties, including, for example, increased compressive deformation.

[0087] It is speculated, and believed, that the stabilizing additives described herein interact with these diffusing species by inhibiting or slowing the degradation of silicone elastomers. This appears to be a surprising effect, especially since other materials that might be expected to have similar effects, such as acid removers (e.g., calcium carbonate, magnesium hydroxide, zinc oxide), do not seem to have similar effects.

[0088] Because silicone elastomers used in silicone-thermoplastic composite articles are designed to form a tight bond on and / or around a flame-retardant-free thermoplastic article, when the silicone-thermoplastic composite article is an electrical or electronic connector, the silicone elastomer is designed / shaped to provide electrical and environmental isolation to the connector joint. However, considering its positioning relative to other components within, for example, an engine, the silicone elastomer seal is under mechanical compression and exposed to high temperatures.

[0089] It can also be exposed to moisture, oil, fuel, corrosive gases, and effluent from the materials it comes into contact with, and therefore it is crucial that the silicone elastomer has suitable compressive deformation, which enables it to maintain its mechanical integrity and dimensional stability to provide adequate sealing performance throughout its service life.

[0090] Silicone elastomers used in silicone-thermoplastic composite products can be prepared by curing a suitable curable silicone elastomer composition, selected from silicone elastomer compositions that can be cured by hydrosilylation reaction or by free radical reaction. The curable silicone elastomer composition can be prepared from liquid silicone rubber (LSR) or high-consistency rubber (HCR) because both produce silicone elastomers with an excellent balance of mechanical properties, chemical properties, and thermal stability upon curing.

[0091] Liquid silicone rubber is often a hydrogenated silanized curable silicone rubber composition, which contains the following components:

[0092] a) One or more polyorganosiloxanes containing at least two unsaturated groups selected from alkenyl and alkynyl groups per molecule and having a viscosity in the range of 1000 mPa·s to 100,000 mPa·s at 25°C;

[0093] b) Optional hydrophobically treated silica-reinforced filler; and

[0094] c1) Hydrogenated silane curing package, which contains

[0095] c1(i)) organosilicon compounds having at least two, alternatively at least three Si-H groups per molecule; and

[0096] c1(ii)) contains a platinum group metal or its compound or a hydrogenation silylation catalyst composed of platinum group metals;

[0097] In this disclosure, the liquid silicone rubber (LSR) composition must also incorporate an additional component (d), wherein:

[0098] (d) 0.25% by weight to a maximum of 5.0% by weight of stabilizing additives selected from the group consisting of: magnesium carbonate, hydroxy magnesium carbonate, magnesium oxide, and mixtures thereof.

[0099] Various optional additives suitable for applications of elastomers produced by curing can also be incorporated into the composition.

[0100] High-viscosity silicone rubbers typically contain polymers with much higher viscosity / chain length / molecular weight, and are usually measured based on their Williams plasticity value rather than viscosity. Williams plasticity is measured according to ASTM D-926-08. Due to their exceptionally high viscosity, they are often referred to in industry as "polymer rubbers".

[0101] Typically, high-consistency rubber compositions differ from the LSR compositions described above and contain the following components:

[0102] a”) One or more polyorganosiloxanes having a Williams plasticity of at least 100 mm / 100 according to ASTM D-926-08, and

[0103] b”) Optional hydrophobic treated silica-reinforced filler.

[0104] The high-consistency silicone rubber composition can be hydrogen silanized and cured, in which case polymer a' must also contain at least two unsaturated groups selected from alkenyl and alkynyl groups; and the composition comprises a hydrogen silanization curing agent c1”) or a free radical curing agent c2”), wherein

[0105] c1”) is a hydrogen silane curing package, which contains

[0106] c1(i)”) organosilicon compounds having at least two, alternatively at least three Si-H groups per molecule; and

[0107] c1(ii)”) contains a platinum group metal or a compound thereof or a hydrogenated silylation catalyst composed of such metals;

[0108] Alternatively, the high-consistency silicone rubber composition may be free-radical vulcanized, typically using an organic peroxide. In the case where the composition used is a high-consistency silicone rubber composition, at least two unsaturated groups selected from alkenyl and alkynyl groups are optionally present in the polymer (a”).

[0109] The composition optionally contains

[0110] c2”) free radical curing agent.

[0111] In this disclosure, the high-consistency silicone rubber composition must also incorporate an additional component (d”), wherein:

[0112] (d) is 0.25% by weight to a maximum of 5.0% by weight of a stabilizing additive selected from the group consisting of magnesium carbonate, hydroxymagnesium carbonate, magnesium oxide, and mixtures thereof. Similarly, various optional additives suitable for applications involving the cured elastomer may also be incorporated into the composition.

[0113] In the case of liquid silicone rubber:

[0114] Component (a)

[0115] The component (a) of the liquid silicone rubber composition contains at least two unsaturated groups selected from alkenyl and alkynyl groups per molecule and has one or more polyorganosiloxanes with a viscosity in the range of 1,000 mPa·s to 100,000 mPa·s at 25°C.

[0116] Component (a) of the liquid silicone rubber composition is a polyorganosiloxane, such as polydiorganosiloxane, having at least two unsaturated groups per molecule, the unsaturated groups being selected from alkenyl or alkynyl groups. Alternatively, component (a) has at least three unsaturated groups per molecule.

[0117] The unsaturated group of component (a) can be at the terminal position, the side chain position, or both.

[0118] The alkenyl group may have 2 to 30, alternatively 2 to 24, alternatively 2 to 20, alternatively 2 to 12, alternatively 2 to 10, or alternatively 2 to 6 carbon atoms. Possible alkenyl groups include, but are not limited to, the following: vinyl groups, allyl groups, methanalyl groups, propenyl groups, hexenyl groups, and cyclohexenyl groups.

[0119] The alkynyl group may have 2 to 30, alternatively 2 to 24, alternatively 2 to 20, alternatively 2 to 12, alternatively 2 to 10, or alternatively 2 to 6 carbon atoms. The alkynyl group may be, but is not limited to, the following: ethynyl group, propynyl group, and butynyl group.

[0120] Component (a) of the liquid silicone rubber composition has multiple units of formula (I): R' a SiO (4-a) / 2 (I)

[0121] Each R' is independently selected from aliphatic hydrocarbon groups and aliphatic nonhalogenated organic groups (i.e., any aliphatic organic substituent group having a free valence at a carbon atom, regardless of the functional group type). Saturated aliphatic hydrocarbon groups are exemplified by, but not limited to, alkyl groups such as methyl, ethyl, propyl, pentyl, octyl, undecyl, and octadecyl, and cycloalkyl groups such as cyclohexyl. Examples of unsaturated aliphatic hydrocarbon groups include, but are not limited to, the alkenyl and alkynyl groups described above. Aliphatic nonhalogenated organic groups are exemplified by, but not limited to, suitable nitrogen-containing groups such as amides and iminos; oxygen-containing groups (such as polyoxyalkylene groups, carbonyl groups, alkoxy groups, and hydroxyl groups). Additional organic groups may include phosphorus-containing groups and boron-containing groups. The subscript "a" is 0, 1, 2, or 3, typically in this case a is mainly 2, but may contain some units where a is 1 or 3.

[0122] When R' is an alternative alkyl group, typically a methyl group, as described above, the siloxy unit can be described using abbreviated nomenclature, i.e., -"M", "D", "T", and "Q". The M unit corresponds to a siloxy unit with α=3, i.e., R3SiO 1 / 2 The D unit corresponds to the silicon-oxygen unit with a = 2, i.e., R₂SiO₃. 2 / 2 The T unit corresponds to the silicon-oxygen unit with a = 1, i.e., R1SiO. 3 / 2 The Q unit corresponds to the silicon-oxygen unit where a = 0, i.e., SiO. 4 / 2 The polyorganosiloxane of component (a) is essentially linear, but may contain a certain proportion of branches due to the presence of T units within the molecule (as previously described), so the average value of subscript a in structure (I) is about 2.

[0123] Component (a) contains at least two unsaturated groups selected from alkenyl and alkynyl groups per molecule. Examples of typical R' groups on one or more polyorganosiloxanes include alkyl groups, especially methyl and ethyl, and alternatively methyl groups, but may include aryl and / or fluoroalkyl groups, such as trifluoropropyl or perfluoroalkyl groups, in addition to the required at least two unsaturated groups selected from alkenyl and / or alkynyl groups (usually alkenyl groups). These groups may be in the side chain position (on the D or T siloxy unit) or in the terminal position (on the M siloxy unit).

[0124] Therefore, the polymer chain of component (a) of the liquid silicone rubber composition may be selected from polydimethylsiloxane, alkylmethylpolysiloxane, alkylarylpolysiloxane, or copolymers thereof (wherein alkyl means any suitable alkyl group, alternatively 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 terminal groups, for example, they may be trialkyl-terminated, alkenyldialkyl-terminated, alkynyldialkyl-terminated, or may be terminally terminated with any other suitable combination of terminal groups, provided that each polymer per molecule contains at least two unsaturated groups selected from alkenyl and alkynyl groups. In one embodiment, the terminal groups of such polymers do not include any silanol terminal groups.

[0125] Therefore, for example, component (a) could be:

[0126] Dialkyl-alkenyl-terminated polydimethylsiloxanes, such as dimethylvinyl-terminated polydimethylsiloxanes; dialkyl-alkenyl-terminated dimethylmethylphenylsiloxanes, such as dimethylvinyl-terminated dimethylmethylphenylsiloxanes; trialkyl-terminated dimethylmethylvinyl polysiloxanes; dialkylvinyl-terminated dimethylmethylvinyl polysiloxane copolymers; dialkylvinyl-terminated methylphenyl polysiloxanes, dialkyl-alkenyl-terminated methylvinylmethylphenylsiloxanes;

[0127] Dialkylalkenyl-terminated methylvinyl diphenylsiloxane; dialkylalkenyl-terminated methylvinylmethylphenyl dimethylsiloxane; trimethyl-terminated methylvinylmethylphenylsiloxane; trimethyl-terminated methylvinyl diphenylsiloxane; trimethyl-terminated methylvinylmethylphenyl dimethylsiloxane. More preferably, it contains 0.5% to 5% by weight of a phenyl organosilicon polymer.

[0128] The component a) of the liquid silicone rubber composition has a viscosity of 1000 mPa·s to 100,000 mPa·s at 25°C, alternatively 5000 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, alternatively 30% to 60% by weight, or alternatively 35% to 55% by weight of the composition. Unless otherwise specified, the viscosity may be greater than 15,000 mPa·s at 25°C using Brookfield with spindle LV-4. TM A rotational viscometer (spindle LV-4 designed for viscosities in the range of 1,000 mPa·s to 2,000,000 mPa·s) was used at appropriate rpm, and for viscosities up to 15,000 mPa·s at 25°C and appropriate rpm, a Brookfield viscometer with a cone-plate arrangement featuring a CP-52 cone was used. TM Measurement using a rotational viscometer.

[0129] Component (b)

[0130] Component (b) of the liquid silicone rubber composition is optionally hydrophobically treated silica reinforcing filler; the reinforcing filler of component (b) may be exemplified by pyrolytic silica and / or precipitated silica and / or colloidal silica. In an alternative, pyrolytic silica, precipitated silica and / or colloidal silica are provided in a subdivided form.

[0131] Precipitated silica, pyrolytic silica, and / or colloidal silica are particularly preferred due to their relatively high surface area (especially when supplied in finer forms, typically at least 50 m² / g (BET method according to ISO 9277:2010)). Fillers with a surface area of ​​50 to 450 m² / g (BET method according to ISO 9277:2010) are typically used, alternatively 50 to 300 m² / g (BET method according to ISO 9277:2010). All these types of silica are commercially available.

[0132] When silica-reinforced fillers (b) have natural hydrophilicity (e.g., untreated silica fillers), they are typically treated with a treatment agent to impart hydrophobicity. These surface-modified silica-reinforced fillers (b) do not clump and can be uniformly incorporated into the polydiorganosiloxane polymer (a) described below because the surface treatment makes the filler readily wettable by component (a).

[0133] Typically, the silica reinforcing filler (b) of a liquid silicone rubber composition can be surface-treated with any low molecular weight silicone compound disclosed in the art that is suitable for preventing wrinkling of the liquid silicone rubber (LSR) composition during processing. For example, organosilanes, polydiorganosiloxanes, or organosilazanes, such as hexaalkyldisilazane or short-chain siloxane diols, can impart hydrophobicity to the silica reinforcing filler (b) and thus make it easier to process and obtain a homogeneous mixture with the other components. Specific examples include, but are not limited to, silanol-terminated trifluoropropylmethylsiloxane, silanol-terminated vinylmethyl (ViMe)siloxane, silanol-terminated methylphenyl (MePh)siloxane, liquid hydroxy-dimethyl-terminated polyorganosiloxane containing an average of 2 to 20 repeating units of diorganosiloxane per molecule, hydroxy-dimethyl-terminated phenylmethylsiloxane, hexaorganodisiloxanes such as hexamethyldisiloxane, divinyltetramethyldisiloxane; hexaorganodisilazanes such as hexamethyldisilazane (HMDZ), divinyltetramethyldisilazane and tetramethyldi(trifluoropropyl)disilazane; hydroxy-dimethyl-terminated polydimethylmethylvinylsiloxane, octamethylcyclotetrasiloxane and silanes, including but not limited to methyltrimethoxysilane, dimethyldimethoxysilane, vinyltrimethoxysilane, methyltriethoxysilane, vinyltriethoxysilane, trimethylchlorosilane, dimethyldichlorosilane, trichloromethylsilane.

[0134] In one embodiment, the treatment agent may be selected from silanol-terminated vinylmethyl (ViMe) siloxanes, liquid hydroxydimethyl-terminated polydiorganosiloxanes containing an average of 2 to 20 diorganosiloxane repeating units per molecule, hexaorganodisiloxanes such as hexamethyldisiloxane and divinyltetramethyldisiloxane; hexaorganodisilazanes such as hexamethyldisilazane (HMDZ) and divinyltetramethyldisilazane; and hydroxydimethyl-terminated polydimethylmethylvinylsiloxane, octamethylcyclotetrasiloxane, and silanes, including but not limited to methyltriethoxysilane, dimethyldiethoxysilane, and / or vinyltriethoxysilane. A small amount of water may be added together with the silica treatment agent as a processing aid.

[0135] The surface treatment of the untreated silica reinforcing filler (b) in the liquid silicone rubber composition can be performed before or in situ before introduction into the composition (i.e., by blending these components together at room temperature or higher until the filler is fully treated in the presence of at least a portion of the other components of the composition herein). Typically, the untreated silica reinforcing filler (c) is treated in situ with a treatment agent in the presence of component (b), which results in the preparation of a silicone rubber matrix material that can then be blended with the other components.

[0136] The silica-reinforcing filler (b) of the liquid silicone rubber composition is optionally present in an amount of up to 40% by weight of the composition, alternatively from 1.0% to 40% by weight of the composition, or alternatively from 5.0% to 35% by weight of the composition, or alternatively from 10.0% to 35% by weight of the composition.

[0137] Component (c1)

[0138] Component (c1) of the liquid silicone rubber composition is a hydrogenated silanization curing package, which contains...

[0139] c1(i)) organosilicon compounds having at least two, alternatively at least three Si-H groups per molecule; and

[0140] (c1(ii)) contains a platinum group metal or its compound or a hydrogenated silylation catalyst composed of platinum group metals;

[0141] Component (c1(i)) serves as a crosslinking agent and is provided in the form of an organosilicon compound having at least two, alternatively at least three, Si-H groups per molecule. Component (c1(i)) of the liquid organosilicon rubber composition typically contains three or more silicon-bonded hydrogen atoms, thus allowing the hydrogen atoms to react with the unsaturated alkenyl and / or alkynyl groups of component (a) to form a network structure therewith, thereby curing the composition. When polymer (a) has more than two unsaturated groups per molecule, some or all of component (c1(i)) may alternatively have two silicon-bonded hydrogen atoms per molecule.

[0142] There are no particular restrictions on the molecular configuration of organosilicon compounds (c1(i)) having at least two, or alternatively at least three, Si-H groups per molecule. It may be linear, branched (a linear chain with some branches by the presence of T groups), cyclic, or a polyorganosiloxane based on a silicone resin.

[0143] Although there is no particular limitation on the molecular weight of component (c1(i)), the viscosity at 25°C is typically from 5 mPa·s to 50,000 mPa·s, using the test method described for component (a).

[0144] The silicon-bonded organic group used in component (c1(i)) can be exemplified by: alkyl groups, such as methyl, ethyl, propyl, n-butyl, tert-butyl, pentyl, hexyl; aryl groups, such as phenyl, tolyl, xylyl or similar aryl; 3-chloropropyl, 3,3,3-trifluoropropyl or similar haloalkyl groups, preferably alkyl groups having 1 to 6 carbons, particularly methyl, ethyl or propyl or phenyl. Preferably, the silicon-bonded organic group used in component (c1(i)) is an alkyl group, alternatively a methyl group, an ethyl group or a propyl group.

[0145] Examples of organosilicon compounds (c1(i)) having at least two, alternatively at least three Si-H groups per molecule include, but are not limited to:

[0146] (a') Trimethylsiloxy-terminated methylhydropolysiloxane

[0147] (b') Trimethylsiloxy-terminated polydimethylsiloxane-methylhydrosiloxane

[0148] (c') Dimethylsiloxane-methylhydrosiloxane copolymer with dimethylhydrosiloxane end-capped

[0149] (d') dimethylsiloxane-methylhydrosiloxane cyclic copolymer

[0150] (e') is derived from (CH3)2HSiO 1 / 2 Unit, (CH3)3SiO 1 / 2unit and SiO 4 / 2 copolymers and / or silicone resins composed of units,

[0151] (f') is derived from (CH3)2HSiO 1 / 2 unit and SiO 4 / 2 copolymers and / or silicone resins composed of units,

[0152] (g') Methylhydrosiloxane cyclic homopolymers having 3 to 10 silicon atoms per molecule;

[0153] Alternatively, the crosslinking agent of component (c1(i)) may be a filler, such as silica treated with one of the above substances, or a mixture thereof.

[0154] In one embodiment, the component (c1(i)) of the liquid silicone rubber composition is selected from methylhydrosiloxanes capped at both ends with trimethylsiloxy groups; copolymers of methylhydrosiloxanes and dimethylsiloxanes capped at both ends with trimethylsiloxy groups; dimethylsiloxanes capped at both ends with dimethylhydrosiloxy groups; and copolymers of methylhydrosiloxanes and dimethylsiloxanes capped at both ends with dimethylhydrosiloxy groups.

[0155] The crosslinking agent (c1(i)) is present in the liquid silicone rubber composition in an amount such that the molar ratio of the total number of organosilicon-bonded hydrogen atoms in component (b) to the total number of alkenyl and / or alkynyl groups in component (a) is 0.5:1 to 10:1. When this ratio is less than 0.5:1, a well-cured composition will not be obtained. When this ratio exceeds 10:1, there is a tendency for the hardness of the cured composition to increase upon heating.

[0156] Preferably, the amount of component (c1(i)) is such that the molar ratio of the silicon-bonded hydrogen atoms of component (b) to the alkenyl / alkynyl groups of component (a), or alternatively the alkenyl groups, is in the range of 0.7:1.0 to a maximum of 5.0:1.0, alternatively 0.9:1.0 to 2.5:1.0, and further alternatively 0.9:1.0 to 2.0:1.0.

[0157] The organosilicon-bonded hydrogen (Si-H) content of component (c1(i)) was determined using quantitative infrared analysis according to ASTM E168. In this case, the ratio of silicon-bonded hydrogen to alkenyl (vinyl) and / or alkynyl groups is important when relying on a hydrogen silane curing process. Generally, this is determined by calculating the total weight % of alkenyl (e.g., vinyl) [V] in the composition and the total weight % of silicon-bonded hydrogen [H] in the composition, and assuming a molecular weight of 1 for hydrogen and a molecular weight of 27 for vinyl, the molar ratio of silicon-bonded hydrogen to vinyl is 27[H] / [V].

[0158] Typically, depending on the number of unsaturated groups in component (a) and the number of Si-H groups in component (c1(i)), component (c1(i)) will be present in the following amounts: 0.1% to 10% by weight of a hydrogenatable silanable curable rubber composition, alternatively 0.1% to 7.5% by weight of a hydrogenatable silanable curable silicone rubber composition, alternatively 0.5% to 7.5% by weight of the composition, and further alternatively 0.5% to 5% by weight of a hydrogenatable silanable curable silicone rubber composition.

[0159] Component (c1(ii))

[0160] Component (c1(ii)) of the liquid silicone rubber composition is a hydrosilylation catalyst comprising a platinum group metal or a compound thereof, or a combination of a platinum group metal or a compound thereof. These catalysts are typically selected from catalysts of platinum group metals (platinum, ruthenium, osmium, rhodium, iridium, and palladium), or compounds of one or more of these metals. Alternatively, platinum and rhodium compounds are preferred due to their high activity levels in the hydrosilylation reaction, with platinum compounds being the most preferred. In the hydrosilylation (or addition) reaction, the hydrosilylation catalyst, such as component (c1(ii)) of this document, catalyzes the reaction between an unsaturated group (typically an alkenyl group, such as a vinyl group) and a Si-H group.

[0161] The catalyst (c1(ii)) of the liquid silicone rubber composition may be a platinum group metal, a platinum group metal deposited on a support (such as activated carbon, metal oxides such as alumina or silica, silica gel or charcoal powder), or a compound or complex of a platinum group metal. Preferably, the platinum group metal is platinum.

[0162] Examples of preferred hydrosilylation catalysts (c1(ii)) include platinum-based catalysts such as platinum black, platinum oxide (Adams catalyst), platinum on various solid supports, chloroplatinic acid (e.g., hexachloroplatinic acid (Pt oxidation state IV) (Speier catalyst)), chloroplatinic acid in solution of alcohols (e.g., isooctyl alcohol or pentanol) (Lamoreaux catalyst), and complexes of chloroplatinic acid with olefinically unsaturated compounds (such as alkenes) and organosiloxanes containing olefinically unsaturated silicon-bonded hydrocarbon groups, such as tetravinyltetramethylcyclotetrasiloxane-platinum complexes (Ashby catalyst). Soluble platinum compounds that can be used include, for example, platinum-olefin complexes of formula (PtCl2.olefin)2 and H (PtCl3.olefin), preferably in this context olefins having 2 to 8 carbon atoms, such as isomers of ethylene, propylene, butene, and octene, or cycloalkanes having 5 to 7 carbon atoms, such as cyclopentene, cyclohexene, and cycloheptene. Other soluble platinum catalysts include, for example, platinum-cyclopropane complexes of formula (PtCl2C3H6)2, 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 vinylsiloxanes (such as methylvinylcyclotetrasiloxane) in the presence of an ethanol solution containing sodium bicarbonate. Platinum catalysts with phosphorus and amine ligands, such as (Ph3P)2PtCl2, and platinum complexes with vinylsiloxanes, such as symmetrical divinyltetramethyldisiloxane, can also be used.

[0163] Therefore, specific examples of suitable platinum-based catalysts include

[0164] (i) A complex of chloroplatinic acid as described in US 3,419,593 with an organosiloxane containing an olefinic unsaturated hydrocarbon group.

[0165] (ii) Chloroplatinic acid in hexahydrate or anhydrous form;

[0166] (iii) A platinum-containing catalyst, which is obtained by a method comprising the steps of reacting chloroplatinic acid with an aliphatic unsaturated organosilicon compound (such as divinyltetramethyldisiloxane);

[0167] (iv) olefin-platinum-silyl complexes as described in U.S. Patent 6,605,734, such as (COD)Pt(SiMeCl2)2, wherein “COD” is 1,5-cyclooctadiene; and / or

[0168] (v) Karstedt catalyst, platinum divinyltetramethyldisiloxane complex, typically containing about 1% by weight of platinum in a vinylsiloxane polymer having a viscosity of about 200 to 750, using the test method described for component (a).

[0169] Solvents such as toluene and similar organic solvents have historically been used as alternatives, but the use of vinylsiloxane polymers is currently the preferred choice. These are described in US3,715,334 and US3,814,730. In a preferred embodiment, component (c1(ii)) may be selected from platinum coordination compounds. In one embodiment, hexachloroplatinic acid and its conversion products with vinyl-containing siloxanes, Karstedt catalyst, and Speier catalyst are preferred.

[0170] Component (c1(ii)) of the liquid silicone rubber composition is typically present in an amount of platinum atoms ranging from 0.1 ppm to 500 ppm (parts per million) relative to the weight of the reactive components, i.e., components (a) and (c1(ii)). The catalyst may be added as a single substance or as a mixture of two or more different substances. Typically, depending on the form / concentration of the catalyst (c1(ii)), the amount of catalyst present will range from 0.05 wt% to 1.5 wt%, alternatively 0.05 wt% to 1.0 wt%, alternatively 0.1 wt% to 1.0 wt%, alternatively 0.1 wt% to 0.5 wt% of the composition, wherein the platinum catalyst is provided in the masterbatch of the polymer (as described above in (a)).

[0171] (d) Stabilizing additives

[0172] The component (d) of the liquid silicone rubber composition is 0.25% to a maximum of 5.0% by weight of the composition, alternatively 0.5% to 5% by weight of the composition, alternatively 0.5% to 3% by weight of the composition, alternatively 0.5% to 2% by weight of the composition, alternatively 0.5% to 1.5% by weight of the composition, alternatively 0.75% to 1.5% by weight of the composition, and alternatively 0.75% to 1.5% by weight of the composition, a stabilizing additive selected from the group consisting of one or more magnesium carbonates, one or more hydroxy magnesium carbonates, magnesium oxide, and mixtures thereof. Alternatively, the stabilizing additive comprises one or more magnesium carbonates or one or more hydroxy magnesium carbonates selected from magnesite (MgCO3), magnesia (MgCO3·2H2O), trihydrate magnesite (MgCO3·3H2O), pentahydrate magnesia (MgCO3·5H2O); and one or more hydroxy magnesium carbonates such as magnesia malachite (Mg2(CO3)(OH)2·0.5H2O), styrene magnesite (Mg2(CO3)(OH)2·3H2O), magnesia (Mg5(CO3)4(OH)2·4H2O) (sometimes referred to as light magnesium carbonate), spheroidal magnesia (Mg5(CO3)4(OH)2·5H2O) (sometimes referred to as bicarbonate), isohydrated magnesite (Mg5(CO3)4(OH)2·5-6H2O) and shelkovite (Mg7(CO3)5(OH)4·24H2O).

[0173] High-consistency silicone rubber composition

[0174] In the case of a high-viscosity rubber composition, components (b”), (c1”), and (d”) are the same as (b), (c1), and (d) of the above-mentioned liquid silicone rubber composition, respectively. However, component (a”) is different, and component (c2”) is replaced by a free radical curing agent instead of component (c1”), wherein:

[0175] (a”) is chemically identical to component (a) of the LSR composition, but contains the following differences because it has a much higher viscosity, which has a Williams plasticity of at least 100 mm / 100 as measured according to ASTM D-926-08; and

[0176] When component (c1”) is used as a catalyst package, at least two unsaturated groups selected from alkenyl or alkynyl groups per molecule are required, and when component c is a free radical curing agent (c2”), these unsaturated groups are optional; and

[0177] Component (c2”), i.e., the free radical curing agent of the high-consistency rubber composition, is selected from suitable azo compounds or organic peroxides or alternatives. Any suitable peroxide catalyst can be used. Suitable organic peroxides include substituted or unsubstituted dialkyl peroxides, alkyl aryl peroxides, and diaryl peroxides, such as benzoyl peroxide and 2,4-dichlorobenzoyl peroxide, di-tert-butyl peroxide, dicumyl peroxide, tert-butylisopropylphenyl peroxide, bis(tert-butyldioxy)dicumyl peroxide, bis(tert-butylperoxy)-2,5-dimethylhexyne, 2,4-dimethyl-2,5-di(tert-butylperoxy)hexane, di-tert-butyl peroxide, and 2,5-bis(tert-butylperoxy)-2,5-dimethylhexane. Mixtures of the above may also be used.

[0178] Typically, the amount of free radical curing agent (c2”) used in the high-consistency rubber compositions as described herein is 0.2% to 3% by weight, or alternatively 0.2% to 2% by weight, based on the weight of the composition in each case.

[0179] Optional additives

[0180] In each case, whether the composition is a liquid silicone rubber composition or a high-viscosity rubber composition, various optional additives suitable for the application to which the cured elastomer will be used can be incorporated into the composition. Examples include curing inhibitors, release agents, non-reinforcing fillers, adhesion catalysts, conductive fillers, thermally conductive fillers, shelf-life extenders, lubricants, heat stabilizers, compression set additives, UV light stabilizers, bactericides, wetting agents, etc. When present, these optional additives can function as more than one type of additive.

[0181] Curing Inhibitor

[0182] When necessary, curing inhibitors are used in hydrogenation silanization (addition) curing systems, for example when the composition contains component C1, to prevent or delay the addition reaction curing process, particularly during storage. Optional addition reaction inhibitors based on platinum catalysts are well known in the art and include hydrazine, triazole, phosphine, thiols, organonitrogen compounds, alkynols, methanesilylated alkynols, maleates, fumarates, olefinic or aromatic unsaturated amides, olefinic unsaturated isocyanates, alkenyl siloxanes, unsaturated hydrocarbon monoesters and diesters, conjugated alkenylenes, hydroperoxides, nitriles, and diazacyclopropanes. Alkenyl-substituted siloxanes as described in US3989667 can be used, with cyclic methylvinylsiloxanes being preferred.

[0183] One known class of inhibitors for hydrosilylation reactions are the alkyne compounds disclosed in US3445420. Alkynols such as 2-methyl-3-butyn-2-ol constitute a preferred class of inhibitors, which suppress the activity of platinum-containing catalysts at 25°C. Compositions containing these inhibitors typically require heating to 70°C or higher to achieve a feasible curing rate.

[0184] Examples of alkynols and their derivatives include 1-ethynyl-1-cyclohexanol (ETCH), 2-methyl-3-butyn-2-ol, 3-butyn-1-ol, 3-butyn-2-ol, propargyl alcohol, 1-phenyl-2-propyn-1-ol, 3,5-dimethyl-1-hexyn-3-ol, 1-ethynylcyclopentanol, 3-methyl-1-penten-4-yn-3-ol, and mixtures thereof. Alynol derivatives may include those compounds having at least one silicon atom.

[0185] In some cases, inhibitor concentrations as low as 1 mole of inhibitor per mole of catalyst metal will confer satisfactory storage stability and curing rate when present. In other cases, an inhibitor concentration of up to 500 moles of inhibitor per mole of catalyst metal is required. The optimal concentration of a given inhibitor in a given composition can be readily determined by routine experiments. Depending on the concentration and form of the inhibitor chosen, it is typically present in the composition at an amount of 0.0125% to 10% by weight of the composition.

[0186] In one embodiment, when present, the inhibitor is selected from 1-ethynyl-1-cyclohexanol (ETCH) and / or 2-methyl-3-butyn-2-ol, and is present in an amount greater than zero to 0.1% by weight of the composition.

[0187] Release agent

[0188] Any suitable release agent can be used. For example, it could be a hydroxydimethyl-terminated polydimethylsiloxane having a viscosity of approximately 21 mPa·s at 25°C, as determined using Brookfield's tapered plate arrangement with cones CP-52. TM The measurement was taken at 12 rpm using a rotational viscometer.

[0189] Unreinforced packing

[0190] Non-reinforcing fillers may include materials such as pulverized quartz, diatomaceous earth, barium sulfate, iron oxide, titanium dioxide and carbon black, talc, and wollastonite. Other fillers that may be used alone or in addition to the above include alumina, calcium sulfate (anhydrite), gypsum, calcium sulfate, clay such as kaolin, aluminum trihydrate, graphite, copper carbonate such as malachite, nickel carbonate such as malachite, barium carbonate such as barite, and / or strontium carbonate such as strontium strontium.

[0191] Other fillers may include alumina, silicates selected from the group consisting of: olivine; garnet; aluminosilicates; cyclosilicates; chain silicates; and platy silicates. Olivine includes silicate minerals such as, but not limited to, forsterite and Mg2SiO4. Garnet includes ground silicate minerals such as, but not limited to, pyrope; Mg3Al2Si3O4. 12 Grossular garnet and Ca2Al2Si3O 12 Aluminosilicates include milled silicate minerals such as, but not limited to, sillimanite; Al₂SiO₅; mullite; 3Al₂O₃·2SiO₂; kyanite; and Al₂SiO₅. Cyclosilicates can be used as non-reinforcing fillers; these include silicate minerals such as, but not limited to, cordierite and Al₃(Mg,Fe)₂[Si₄AlO₂]. 18 Chain silicates include ground silicate minerals, such as, but not limited to, wollastonite and Ca[SiO3]. Flake silicates may alternatively or otherwise be used as non-reinforcing fillers, wherein suitable classes contain silicate minerals, such as, but not limited to, mica; K2Al 14 [Si6Al2O 20 (OH)4; pyrophyllite; Al4[Si8O 20 (OH)4; Talc; Mg6[Si8O 20 (OH)4; serpentine, for example asbestos; kaolinite; Al4[Si4O] 10 [(OH)8; and vermiculite. To avoid any doubt, component (d) is not considered a non-reinforcing filler.]

[0192] Other additives include silicone fluids, such as trimethylsilyl or OH-terminated siloxanes. These trimethylsiloxy or OH-terminated polydimethylsiloxanes typically have a viscosity of <150 mPa·s at 25°C, a viscosity obtained using Brookfield with a cone-plate arrangement featuring cones CP-52. TM The rotational viscometer was used to measure the viscosity at 12 rpm. When present, such silicone fluids may be present in liquid curable silicone rubber compositions in amounts ranging from 0.1% to 5% by weight based on the total weight of the composition, and may be used as mold release agents.

[0193] Pigments and other colorants

[0194] Examples of pigments include titanium dioxide, chromium trioxide, bismuth vanadium oxide, iron oxide, and mixtures thereof.

[0195] Examples of colorants that can be used in hydrogenated silanized curable silicone coating compositions include pigments, vat dyes, reactive dyes, acid dyes, chromium dyes, disperse dyes, cationic dyes, and mixtures thereof. Two-part moisture-curing organopolysiloxane compositions as described herein may also contain one or more pigments and / or colorants, which may be added if desired. Pigments and / or colorants can be colored, white, black, metallic, and luminescent, such as fluorescent and phosphorescent. Pigments are used to color the composition as needed. Any suitable pigment that is compatible with the compositions described herein may be utilized. In two-part moisture-curing organopolysiloxane compositions, pigments and / or colored (non-white) fillers such as carbon black may be used in the catalyst package to color the final sealant product.

[0196] Suitable white pigments and / or colorants include titanium dioxide, zinc oxide, lead oxide, zinc sulfide, zinc barium white, zirconium oxide, and antimony oxide.

[0197] Suitable non-white inorganic pigments and / or colorants include, but are not limited to, iron oxide pigments such as goethite, lepidocrocite, hematite, maghemite, and maghemite black, yellow, brown, and red iron oxides; blue iron pigments; chromium oxide pigments; cadmium pigments such as cadmium yellow, cadmium red, and cadmium cinnabar; bismuth pigments such as bismuth vanadate and bismuth vanadate; mixed metal oxide pigments such as cobalt titanate green; chromate and molybdate pigments such as chrome yellow, molybdenum red, and molybdenum orange; ultramarine pigments; cobalt oxide pigments; nickel antimony titanate; lead chromium; carbon black; lampblack; and metallic effect pigments such as aluminum, copper, copper oxide, bronze, stainless steel, nickel, zinc, and brass.

[0198] Suitable organic non-white pigments and / or colorants include phthalocyanine pigments, such as phthalocyanine blue and phthalocyanine green; monoaryl yellow, diaryl yellow, benzimidazolone yellow, heterocyclic yellow, DAN orange, quinacridone pigments, such as quinacridone fuchsin and quinacridone violet; organic reds, including metallized azo red and non-metallized azo red, as well as other azo pigments, monoazo pigments, diazo pigments, azo pigment lakes, β-naphthol pigments, naphthol AS pigments, benzimidazolone pigments, diazo condensation pigments, isoindolineone and isoindoline pigments, polycyclic pigments, perylene and violet ketone pigments, thioindigo pigments, anthraquinone pigments, yellow anthrone pigments, anthraquinone pigments, dioxazine pigments, triarylcarbene pigments, quinacridone pigments, and diketopyrrolopyrrole pigments.

[0199] Typically, pigments and / or colorants, when in the form of microparticles, have an average particle size in the range of 10 nm to 50 μm, preferably in the range of 40 nm to 2 μm.

[0200] lubricant

[0201] As previously indicated, compositions of the type described herein are commonly used as electrical or electronic connectors. Such electrical or electronic connectors are typically made of self-lubricating silicone elastomers designed to gradually seep out from a cured seal over time and lubricate the cable and connector assembly. Typically, polyphenylmethylsiloxanes and their copolymers, such as trimethylsilyl-terminated phenylmethylsiloxane-dimethylsiloxane copolymers, have a viscosity of 100 mPa·s to 200 mPa·s at 25°C, which is obtained using Brookfield's tapered plate arrangement with cones CP-52. TM The rotational viscometer measures at 12 rpm, as well as mixtures or derivatives thereof.

[0202] In such cases, it is used as a lubricant. Examples of other lubricants that may be used alternatively or additionally include tetrafluoroethylene, resin powder, graphite, fluorinated graphite, talc, boron nitride, fluorinated oil, molybdenum disulfide, and mixtures or derivatives thereof. When present, such lubricants may be present in an amount from 1% to 7% by weight of the composition.

[0203] Heat stabilizer

[0204] The compositions described herein may also contain one or more inorganic heat stabilizers, used alone or in combination, such as hydrated cerium oxide, cerium hydroxide, cerium carboxylate and / or cerium esters, such as cerium ethylhexanoate, hydrated alumina, red iron oxide, yellow iron oxide, carbon black, graphite and zinc oxide.

[0205] Metal deactivating agents

[0206] The composition may incorporate one or more metal deactivators selected from compounds based on diacylhydrazines, aminotriazoles, and aminotriazines. Alternatively, the metal deactivator has a molecular weight of 120 to 700 and is a triazine compound containing an amino group or a compound having a phenolic group and an amide bond in its main chain. Typically, the metal deactivator has a melting point of 80°C or higher and 300°C or lower, wherein the melting point is measured by differential scanning calorimetry (DSC). The melting point can be determined by differential scanning calorimetry (DSC) according to JIS K 7121-1978 "Testing Methods for Transition Temperatures of Plastics". In this apparatus, a DSC measuring disk in which a sample of polyester resin (A) is sealed is set up, heated to 320°C at a heating rate of 10°C / min in a nitrogen atmosphere, and held at this temperature for 5 minutes. The temperature is lowered to 30°C by measuring the temperature decrease at 10°C / min. The temperature at the peak of the endothermic peak during heating is defined as the "melting point".

[0207] Compounds based on diacylhydrazides are represented by the following general formula:

[0208]

[0209] Where R 1 and R 2 They may be the same or different and may be represented by: hydrogen atoms, hydroxyl groups, alkyl groups, substituted alkyl groups, aryl groups, phenolic groups or similar substituted aryl groups, aralkyl groups or substituted aralkyl groups. Preferably, R 1 and R 2 It contains a monovalent hydrocarbon group with an aryl group, a phenolic group, or a similarly substituted aryl group. Specific examples of the above-mentioned diacylhydrazides are as follows: N,N'-diformylhydrazide, N,N'-diacetylhydrazide, N,N'-dipropionylhydrazide, N,N'-butylhydrazide, N-formyl-N'-acetylhydrazide, N,N'-dibenzoylhydrazide, N,N'-dibenzoylhydrazide, N,N'-disalicylic acid hydrazide, N-formyl-N'-disalicylic acid hydrazide, N-formyl-N'-butyl-substituted salicylhydrazide, N-acetyl-N'-salicylic acid hydrazide, N,N'-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propynyl]hydrazide, adipic acid di-(N'-salicylic acid)hydrazide, or dodecyl diacyl-di-(N'-salicylic acid)hydrazide.

[0210] Commercially produced compounds of the above contain, for example, N,N'-bis-[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl]hydrazine, which is produced by BASF using Irganox TMMD1024 for sale, dodecanodicyl-di-(N'-salicylicyl)hydrazine, its synonym is 1-N',12-N'-bis(2-hydroxybenzoyl)dodecanodicylhydrazine, which is used as ADK STAB TM CDA-6 is commercially available from Adeka Corporation (hereinafter referred to as CDA-6); N'1,N'12-bis(2-hydroxybenzoyl)dodecanedihydrazide, which is used as ADK STAB TM CDA-6S was commercially available from Adeka Corporation, along with N,N'-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl]hydrazine, which is used as ADK STAB TM CDA-10 was purchased from Adeka Corporation, and N,N'-bis-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl hexamethylenediamine, which was purchased as ANTAGE HP-300 from Kawaguchi Chemical Industry.

[0211] Compounds based on aminotriazole are represented by the following general formula (2):

[0212]

[0213] Where R 4 and R 5 Identical or different and represented by: hydrogen atom, alkyl group, substituted alkyl group, substituted aryl group, carboxyl group, acyl group, alkyl-ester group, aryl-ester group, halogen or alkali metal; R 3 It can represent a hydrogen atom or an acyl group; R 5 The group may be an acyl group, preferably a salicylyl group, a benzoyl group, or a similar acyl group having an aromatic ring. Examples of the above compounds may include 3-amino-1,2,4-triazole, 3-amino-1,2,4-triazole-carboxylic acid, 3-amino-5-methyl-1,2,4-triazole, 3-amino-5-heptyl-1,2,4-triazole, etc.; or amide derivatives based on amino-triazole compounds, wherein the hydrogen atom of the triazole-bonded amino group is replaced by an acyl group, for example, 3-(N-salicylicyl)amino-1,2,4-triazole or 3-(N-acetyl)amino-1,2,4-triazole-5-carboxylic acid. Among the above compounds, amide derivatives based on amino-triazole compounds are most preferred because these compounds do not delay the curing rate of the addition-reaction-curable silicone rubber composition.

[0214] Commercially produced examples of this type of compound are 3-(n-salicyloyl)amino-1,2,4-triazole (a synonym for 2-hydroxy-N-1H-1,2,4-triazole-3-ylbenzamide), which is used as ADK STAB. TM CDA-1 and its blend as ADK STABCDA-1M are commercially available from Adeka Corporation. Another commercial example is from Adekastab of Adeka Corporation. TM ZS-27, the main component of which is understood to be 2,4,6-triamino-1,3,5-triazine. In one embodiment, the composition contains a metal deactivator as described above.

[0215] In an alternative, component (e)(ii) is dodecanodicyl-di-(N'-salicyloyl)hydrazine or 3-(N-salicyloyl)amino-1,2,4-triazole.

[0216] When present, component (e)(ii) is typically added in amounts from 0.001 wt% to 1.0 wt% of the composition, alternatively from 0.001 wt% to 0.5 wt% of the composition, alternatively from 0.01 wt% to 0.5 wt% of the composition, alternatively from 0.05 wt% to 0.5 wt% of the composition.

[0217] Therefore, the liquid silicone rubber composition used to produce the silicone elastomer described herein may contain any suitable combination of the following components:

[0218] a) One or more polyorganosiloxanes containing at least two unsaturated groups selected from alkenyl and alkynyl groups per molecule and having a viscosity in the range of 1000 mPa·s to 100,000 mPa·s at 25°C; alternatively present in an amount of 5000 mPa·s to 75,000 mPa·s at 25°C, 10,000 mPa·s to 60,000 mPa·s at 25°C, preferably in an amount of 25% to 60% by weight of the composition, alternatively in an amount of 30% to 60% by weight of the composition, or alternatively in an amount of 35% to 55% by weight of the composition. The viscosity can be measured at 25°C as described above;

[0219] b) A silica-reinforced filler, preferably in a finely divided form and optionally hydrophobically treated; with a high surface area, typically at least 50 m² / g (according to the BET method of ISO 9277:2010). The silica-reinforced filler (c) has a surface area of ​​50 m² / g to 450 m² / g (according to the BET method of ISO 9277:2010), alternatively 50 m² / g to 300 m² / g (according to the BET method of ISO 9277:2010), and is typically present in amounts of up to 40 wt% of the composition, alternatively 1.0 wt% to 40 wt% of the composition, or alternatively 5.0 wt% to 35 wt% of the composition, or alternatively 10.0 wt% to 35 wt% of the composition.

[0220] Component (c1) of the liquid silicone rubber composition is a hydrogenated silanization curing package, which contains...

[0221] (c1(i)) organosilicon compounds having at least two, optionally at least three, Si-H groups per molecule; and

[0222] (c1(ii)) contains a platinum group metal or its compound or a hydrogenated silylation catalyst composed of platinum group metals;

[0223] The organosilicon compound (c1(i)) having at least two, alternatively at least three Si-H groups per molecule as described above may be present in amounts from 0.1 wt% to 10 wt% of the liquid organosilicon rubber composition, from 0.1 wt% to 7.5 wt% of the hydrogenable silanized curable organosilicon rubber composition, from 0.5 wt% to 7.5 wt% of the composition, and further alternatively from 0.5 wt% to 5 wt%.

[0224] The component (c1(ii)) of the liquid silicone rubber composition is a hydrogenated silanization catalyst comprising a platinum group metal or a compound thereof as described above, or a platinum group metal or a compound thereof; the amount of which depends on the form / concentration of the catalyst provided, and is in the range of 0.001 wt% to 3.0 wt% of the composition, alternatively 0.001 wt% to 1.5 wt% of the composition, alternatively 0.01 wt% to 1.5 wt% of the composition, and alternatively 0.01 wt% to 0.1.0 wt% of the silicone rubber composition.

[0225] Component (d) is 0.25% by weight to a maximum of 5.0% by weight of a stabilizing additive selected from the group consisting of: magnesium carbonate, hydroxy magnesium carbonate, magnesium oxide, and mixtures thereof;

[0226] The condition is that the total weight percentage of the composition is 100% by weight.

[0227] The composition may also contain one or more of the optional additives mentioned above in amounts again, provided that the total weight % of the composition is 100% by weight.

[0228] Therefore, the high-consistency rubber composition that can be used to produce the silicone elastomer described herein may contain any suitable combination of the following components:

[0229] a”) One or more polyorganosiloxanes having a Williams plasticity of at least 100 mm / 100 according to ASTM D-926-08, wherein when the hydrogenable silanizable curable polymer a” must also contain at least two unsaturated groups selected from alkenyl and alkynyl groups, and when the high-consistency rubber composition is free radical cured, at least two unsaturated groups selected from alkenyl and alkynyl groups are optional in polymer a”; the component a” is preferably in an amount of 25% to 60% by weight of the composition, alternatively in an amount of 30% by weight of the composition.

[0230] It is present in an amount of up to 60% by weight, or alternatively in an amount of 35% to 55% by weight of the composition.

[0231] b”) Silica-reinforced filler, which is the same as component (b) above regarding the liquid silicone rubber composition;

[0232] The high-consistency rubber component (c1”) is a hydrogenated silanization curing package and is used when the high-consistency rubber is a hydrogenated silanization (addition) curable composition and has the same composition and amount as component (c1) of the above-described liquid silicone rubber composition; position,

[0233] Component c2”, i.e., the free radical curing agent of the high-consistency rubber composition, is selected from suitable azo compounds or organic peroxides or alternatives; the amount of free radical curing agent (c2”) used in the high-consistency rubber composition as described herein is, in each case, 0.2% to 3% by weight, or alternatively 0.2% to 2% by weight, based on the weight of the composition;

[0234] In addition, component (d) comprises 0.25% to a maximum of 5.0% by weight of the composition, alternatively 0.5% to 5% by weight, alternatively 0.5% to 3% by weight, alternatively 0.5% to 2% by weight, alternatively 0.5% to 1.5% by weight, and alternatively 0.75% to 1.5% by weight of the composition of a stabilizing additive selected from the group consisting of one or more magnesium carbonates, one or more hydroxy magnesium carbonates, magnesium oxide, and mixtures thereof;

[0235] The condition is that the total weight percentage of the composition is 100% by weight.

[0236] The composition may also contain one or more of the optional additives mentioned above in amounts again, provided that the total weight % of the composition is 100% by weight.

[0237] When the silicone elastomers used herein are prepared from liquid silicone rubber compositions as described above, such compositions are hydrogen-silanizable and curable and are typically stored in two or more portions prior to use. In the case of a two-part composition, these two portions are typically referred to as portion (A) and portion (B):

[0238] In addition to polyorganosiloxane (a) and silica-reinforced filler (b) (in the presence), part (A) typically contains a catalyst (c1(ii)), and

[0239] Part (B) typically contains a crosslinking agent component (c1(ii)), and, when present, an optional inhibitor, as well as the remaining polyorganosiloxane (a) and / or silica-reinforcing filler (b).

[0240] It is important to store the catalyst (c1(ii)) separately from the crosslinking agent (c1(ii)) to prevent premature curing during storage.

[0241] Component (d), namely 0.25% by weight to a maximum of 5.0% by weight, is a stabilizing additive selected from the group consisting of magnesium carbonate, hydroxymagnesium carbonate, magnesium oxide, and mixtures thereof. It may be stored in or in part (A) or part (B), provided that these parts do not negatively affect the storage of any necessary components present in the respective parts. Alternatively, if desired, component (d) may be added to the remaining composition during or after mixing the part (A) composition and the part (B) composition together prior to use, i.e., added to the combination of the part (A) and part (B) compositions.

[0242] Any optional additives other than the inhibitors described above may be incorporated into part (A) or part (B) or both, provided that they do not negatively affect the storage of any necessary components present in the respective part.

[0243] The composition can be designed to be mixed in any suitable weight ratio, for example, part (A): part B can be mixed together in a ratio of 10:1 to 1:10, alternatively 5:1 to 1:5, alternatively 2:1 to 1:2, but the most preferred weight ratio is 1:1.

[0244] The components / components in each of portion (A) and / or portion (B) may be mixed separately in the corresponding portion, or may be introduced into the composition in a pre-prepared combined form to facilitate, for example, mixing of the final composition. For example, components (a) and (b) are typically mixed together before the introduction of other components to form an LSR polymer base or masterbatch. These may then be mixed with other components of the directly prepared portion, or may be used to prepare a pre-prepared concentrate commonly referred to in the industry as a masterbatch.

[0245] In this case, to facilitate the mixing of the components, one or more masterbatches can be used to successfully mix the components to form part (A) and / or part (B) composition. For example, a "pyrolytic silica" masterbatch can be prepared. This is actually an LSR silicone rubber base material with in-situ treated silica reinforcing filler (c).

[0246] Components A and B of the composition can be prepared by combining all their respective components at ambient temperature. Any mixing techniques and apparatus described in the prior art can be used for this purpose. The specific apparatus to be used will depend on the components and the viscosity of the final composition. Suitable mixers may include, but are not limited to, kneading mixers, static mixers in liquid injection molding machines, Z-blade mixers, two-roll mills (open mills), three-roll mills, etc. Rheomix OS Lab mixers, screw extruders, or twin-screw extruders, etc., may also be used. Alternatively, high-speed mixers, such as those sold by Hauschild as DC 150.1FV, DAC 400FVZ, or DAC 600FVZ, may be used. Cooling the components during mixing may be desirable to prevent premature curing of the composition.

[0247] The composition of part (A) and part (B) can be designed to be mixed in any suitable ratio, for example, part (A): part B can be mixed together in a weight ratio of 10:1 to 1:10, or 5:1 to 1:5, or 2:1 to 1:2, but the most preferred weight ratio is 1:1.

[0248] Before use, mix the corresponding components (A) and (B) together in the desired ratio.

[0249] The curing of the hydrogenated silanized silicone rubber composition on the substrate can be carried out, for example, in a mold, to form a molded part by compression molding, extrusion, transfer molding, pressure vulcanization, or calendering using, for example, a liquid injection molding system (LIMS).

[0250] With regard to the method of manufacturing the two-part silicone rubber composition as described above, the method may include the following steps:

[0251] (i) Preparation of an organosilicon-based composition comprising component (a) a polymer and (c) a silica-reinforced filler.

[0252] (ii) Divide the resulting base material into two parts, part (A) and part (B), and introduce catalyst (d) into part (A) and crosslinking agent (b) and inhibitor (if present) into part (B).

[0253] (B) In the composition.

[0254] (iii) Introducing any other optional additives into either or both of parts (A) and (B); and

[0255] (iv) Store part (A) and part (B) of the composition separately.

[0256] Typically, when used, portions (A) and (B) of the composition are thoroughly mixed in the appropriate weight ratio as described above, immediately before use to avoid premature curing. Curing is then carried out during the curing stage. Hydrogenable silanization curable silicone rubber compositions cure at any suitable temperature, for example, at 80°C to 200°C, alternatively about 100°C to 180°C, and alternatively about 120°C to 180°C. As indicated above, one of the standard methods for reducing compression set has historically been post-curing, with the aim of reducing the number of curable groups that may cure under compression during use as a liner.

[0257] If desired, a high-consistency rubber option that can be hydrogenated and cured via silanization can be prepared in a similar manner as described above. However, given that component (a”) is a silicone material with a Williams plasticity of at least 100 mm / 100 according to ASTM D-926-08, in the case of immediate use of the composition, the composition can typically be prepared by combining all components together at ambient temperature to form a single-component composition. Typically, the base material is prepared first to allow for in-situ treatment of the reinforcing silica filler (b”) with a hydrophobic treatment agent, while mixing the polymer and filler, and any other treatment agent (if present), and then the remaining components can be introduced into the mixture in any suitable order.

[0258] Any mixing technique and apparatus described in the prior art can be used for this purpose. The specific apparatus to be used will be determined by the components and the viscosity of the final curable coating composition. Suitable mixers include, but are not limited to, paddle mixers, such as planetary mixers and kneader-type mixers. However, when component (a”) is a glue, mixing is preferred, as described above, using a kneader mixer. It may be desirable to cool the components during mixing to prevent premature curing of the composition.

[0259] This article also describes a method for preparing a high-consistency silicone rubber elastomer, which includes the following steps:

[0260] (i) Prepare an organosilicon rubber base composition comprising components (a), (b) and (c) as described above.

[0261] (ii) Incorporating components (d), (e), and simultaneously or subsequently component (f) into the silicone rubber base material of step (i); and

[0262] (iii) Curing the composition.

[0263] Step (i) can be achieved by mixing the component polymer (a”) and filler (b) with the treatment agent (c) at a temperature ranging from 80°C to 250°C, alternatively from 100°C to 220°C, alternatively from 120°C to 200°C for a period of 30 minutes to 2 hours, alternatively from 40 minutes to 2 hours, or alternatively from 45 minutes to 90 minutes, to ensure that the reinforced silica filler is treated in situ with the hydrophobic treatment agent and is fully mixed into the component (a”). The resulting alkali can then be cooled to approximately room temperature (23°C to 25°C).

[0264] The remaining components, along with optional inhibitors (e.g., ethynylcyclohexanol (ETCH)) and any other optional additives, may then be added simultaneously or subsequently, in any suitable order, or simultaneously, and mixed until homogeneous.

[0265] Once prepared due to the reactivity of the polymer, the hydrogenated silanizing crosslinking agent, and the hydrogenated silanizing catalyst, the composition will cure. Typically, curing will occur at a temperature between 80°C and 180°C, alternatively between 100°C and 170°C, or alternatively between 120°C and 170°C. This can be done in any suitable manner; for example, the composition can be introduced into a mold and then pressure-cured for a suitable time, such as 2 to 10 minutes, or as otherwise desired or required. The thermally stable organosilicon rubber composition of the present invention, capable of hydrogenated silanization curing, can be further processed alternatively by injection molding, encapsulation molding, compression molding, dispenser molding, extrusion molding, transfer molding, compression vulcanization, centrifugal compression vulcanization, calendering, bead application, or blow molding. When necessary, the sample can be further post-cured by heating to a temperature of 130°C to 200°C for up to 4 hours.

[0266] Once prepared, the silicone elastomer article can be placed on and / or around a flame-retardant-free thermoplastic article in its functional position to provide the final silicone-thermoplastic composite article. Subsequently, the silicone-thermoplastic composite article is placed / assembled in place for use as part of the manufacturing process, etc., and as part of the manufacturing process, etc., when required.

[0267] Silicone-thermoplastic composite products have a wide range of applications in industrial settings, homes, and increasingly in automobiles. In automotive applications, they can be used as battery components, charging components and powertrain components for electric vehicles, and for noise and vibration applications. However, they are particularly well known as rigid housing components for electrical connector housings or electronic connector housings that generate closed circuits in automotive, residential, and infrastructure environments.

[0268] They are also used in a wide range of electrical and / or insulation applications, such as for cable accessories like electrical or electronic connectors, terminals, and wire seals. Electrical or electronic connectors are commonly used to create closed circuits in automotive, residential, and infrastructure environments due to their excellent balance of mechanical properties, chemical and thermal stability, ease of processing, and availability of self-lubricating agents. They can be used to fit rigid, flame-retardant-free thermoplastic housing assemblies to provide electrical and environmental isolation to the connector joints against the potential presence of, for example, moisture, oil, fuels, and corrosive gases. The silicone elastomers prepared using the compositions described herein exhibit suitable low compressive deformation at high temperatures, thereby providing mechanical integrity and dimensional stability for electrical or electronic connectors as described above, resulting in excellent sealing performance over their service life. Therefore, they are used or used in the manufacture of automotive parts, cable accessories; electrical and electronic components; packaging components; building components, such as sealants; and household components. In one embodiment, the cable accessory is an electrical or electronic connector with a silicone elastomer seal.

[0269] The following examples are intended to illustrate, and not limit, the present disclosure. Example

[0270] Unless otherwise specified, all viscosities were measured at 25°C. Unless otherwise stated, the viscosities of the components in the following examples for viscosities exceeding 15,000 mPa·s were measured using Brookfield with spindle LV-4. TM A rotational viscometer (spindle LV-4 designed for viscosities in the range of 1,000 mPa·s to 2,000,000 mPa·s) was used at appropriate rpm, and for viscosities up to 15,000 mPa·s, a Brookfield viscometer with a cone-plate arrangement featuring a CP-52 cone was used at appropriate rpm. TM Measurement using a rotational viscometer.

[0271] The stability of the physical properties induced by the stabilizing additives introduced herein is illustrated by evaluating changes in compression set in the following examples, believed to be caused by the stabilizing additives counteracting the weakening effect on the silicone elastomer assessed by species migrating into it from flame-retardant-free thermoplastics. The compression set results provided are in accordance with industry standard specification ASTM D395-18 Method B, where a cylindrical disc with a diameter of 29.0 mm ± 0.5 mm and a thickness of 12.5 mm ± 0.5 mm is compressed by 25% to a thickness of approximately 9.38 mm. Under compression, LSR button-like materials (cured by direct compression molding into a button-like mold at 171°C for 20 minutes) are clamped on both the top and bottom with a substrate (metal or flame-retardant-free thermoplastic) and placed in a normal compression fixture. Thin metal pads are used to adjust for variability in substrate thickness when necessary. Unless otherwise specified, samples are placed in a convection oven and compressed by 25% at a specific oven temperature set to a specific time period (hour (h)). Subsequently, the compression was released, and the test piece was allowed to recover for 30 minutes before compression deformation measurements were performed.

[0272] The following series of 2-part liquid silicone rubber elastomer compositions are prepared as indicated in Tables 1a, 2a and 6a.

[0273] The thermoplastic without flame retardant used in the examples is:

[0274] Unfilled PA66: Tecamid prepared by Ensinger, commercially available from McMaster Carr of Elmhurst, Illinois, USA, as part number 8539K311.

[0275] PA66 GF25: Thermoplastic PA66-GF25 is a commercially available 25% glass fiber reinforced (GF25) PA6,6, also known as DURETHAN. TM AKV25, from Lanxess.

[0276] PA6-GF25: Thermoplastic PA6-GF25 is a commercially available 25% glass fiber reinforced (GF25) PA6, also known as DURETHAN. TM BKV25, from Lanxess.

[0277] PBT GF30: Thermoplastic PBT GF30 is a commercially available 30% glass fiber reinforced (GF30) PBT, also known as ULTRADUR. TM B 4300 G6 NAT, from DuPont.

[0278] In the above text, to avoid any ambiguity, PA = polyamide and PBT = polybutylene terephthalate.

[0279] In the compositions used, the following components shall be mentioned in appropriate places:

[0280] Pyrolytic silica 1: exhibits a silica content of approximately 250 μm 2 / g BET surface area of ​​treated pyrolytic silica in the form of dimethylvinyl and trimethylated pyrolytic silica (untreated).

[0281] Pyrolytic silicon dioxide 2: exhibits a density of approximately 400 μm 2 / g BET surface area of ​​treated pyrolytic silica in the form of dimethylvinyl and trimethylated pyrolytic silica (untreated).

[0282] Polymer 1: A vinyl dimethyl-terminated polydimethylsiloxane with a viscosity of 53,000 mPa·s at 25°C, achieved using Brookfield with spindle LV-4. TM The rotational viscometer was used to measure the viscosity at 6 rpm.

[0283] Polymer 2: A vinyl-terminated poly(dimethylsiloxane-copolymer-methylvinylsiloxane) with a viscosity of 370 mPa·s at 25°C, as described by Brookfield using a cone-plate arrangement with cones CP-52. TM The rotational viscometer was used to measure the viscosity at 12 rpm.

[0284] A dispersion of dimethylvinylsiloxy-terminated polydimethylsiloxane with a viscosity of approximately 53,000 mPa·s at 25°C and a total vinyl content of 0.17 wt% and a silica masterbatch of 1:66.6 wt% at 25°C, and a total vinyl content of approximately 250 mPa·s. 2 A dispersion of pyrolytic silica treated with dimethylvinylation and trimethylation at a BET surface area of ​​ / g (untreated).

[0285] 2: A dispersion of dimethylvinylsiloxy-terminated polydimethylsiloxane with a viscosity of approximately 53,000 mPa·s at 25°C and a total vinyl content of 0.062 wt%, comprising 70.8 wt% silica masterbatch and approximately 250 mPa·s of dimethylvinylsiloxy-terminated polydimethylsiloxane. 2 A dispersion of trimethylated pyrolytic silica with a BET surface area of ​​ / g (untreated).

[0286] Crosslinking agent 1: Trimethyl-terminated polymethylhydrogendimethylsiloxane with a viscosity of 30 mPa·s at 25°C, as described by Brookfield using a cone-plate arrangement with cones CP-52. TM The rotational viscometer was used to measure the viscosity at 12 rpm.

[0287] Crosslinking agent 2: Dimethyl, methylhydrosiloxane and methylsilsesquioxane with a viscosity of 15 mPa·s at 25°C, as described by Brookfield using a conical plate arrangement with cones CP-52. TM The rotational viscometer was used to measure the viscosity at 12 rpm.

[0288] Inhibitor: 1-Ethynyl-cyclohexanol (ETCH).

[0289] Additive 1: Tetravinyl-tetramethyl-cyclotetrasiloxane.

[0290] Additive 2: A hydroxyl-dimethyl-terminated polydimethylsiloxane with a viscosity of approximately 21 mPa·s at 25°C, using Brookfield with spindle LV-2. TM The rotational viscometer was used to measure the viscosity at 12 rpm.

[0291] Additive 3: A trimethylsilyl-terminated phenylmethylsiloxane-dimethylsiloxane copolymer with a viscosity of 125 mPa·s at 25°C, using Brookfield with a cone-plate arrangement having cones CP-52. TM The rotational viscometer was used to measure the viscosity at 12 rpm.

[0292] Additive 4: Dodecanodiacyl-di-(N'-salicyloyl)hydrazine, synonymous with 1-N',12-N'-bis(2-hydroxybenzoyl)dodecanodiacylhydrazine, as ADK STAB TM The CDA-6 was commercially sold and acquired from Adeka Corporation.

[0293] Additive 5: A hydroxyl-dimethyl-terminated polydimethylsiloxane with a viscosity of approximately 42 mPa·s at 25°C, as described by Brookfield using a cone-plate arrangement with cones CP-52. TM The rotational viscometer was used to measure the viscosity at 12 rpm.

[0294] Stabilizing additive 1: 85% by weight of a dispersion of dimethylvinylsiloxy-terminated polydimethylsiloxane having approximately 2000 mPa·s at 25°C, this viscosity was obtained using Brookfield with a cone-plate arrangement having cones CP-52. TMThe rotational viscometer measured the phthalocyanine copper at 3 rpm, and 15% by weight of the copper phthalocyanine was purchased from Toyocolor Co., Ltd. as LIONOL BLUE FG-7330.

[0295] Stabilizer 2: 50% by weight of a dispersion of dimethylvinylsiloxy-terminated polydimethylsiloxane having a viscosity of approximately 2000 mPa·s at 25°C, using Brookfield with a cone-plate arrangement having cones CP-52. TM The rotational viscometer was used to measure the viscosity at 3 rpm, and 50% by weight as BAYFERROX. TM 110M is iron oxide (III) obtained commercially from Lanxess.

[0296] Stabilizing Additive 3: as Versamag TM Magnesium hydroxide obtained commercially from Akrochem.

[0297] Stabilizing Additive 4: As Atomite TM Ground calcium carbonate with an average particle size of 3 μm, commercially available from Imerys.

[0298] Stabilizing Additive 5: as Gama-Sperse TM CS-11 is a milled calcium carbonate with an average particle size of 3 μm obtained commercially from Imerys and surface-treated with ammonium stearate.

[0299] Stabilizing Additive 6: Zinc oxide from Sigma Aldrich, catalog number 96479.

[0300] Stabilizing Additive 7: Disodium hydrogen phosphate, catalog number S9763, from Sigma Aldrich.

[0301] Stabilizing Additive 8: As Akrochem TM Light magnesium carbonate was obtained from magnesium carbonate hydrate commercially from Akrochem.

[0302] Stabilizing Additive 9: As MAGOX TM 98 HR obtained magnesium oxide commercially from Premier Magnesia (Premier Magnesia, LLC).

[0303] In the following examples, the compositions described in Tables 1a, 2a and 6a were prepared using the above-described components as follows:

[0304] In the cases of the compositions in Tables 1a and 2a, prepare two-part compositions:

[0305] The treated pyrolytic silica 1, polymers 1 and 2, catalyst, additives 1, 2 and 3, and stabilizing additives are blended into the first part, part A, and...

[0306] The treated pyrolytic silica 1, polymers 1 and 2, crosslinking agent 1, inhibitor, additives 2, 3 and 4, and stabilizing additives are blended together into the second part, part B.

[0307] In the compositions in Table 6a, two-part LSR compositions were prepared as follows:

[0308] The treated pyrolytic silica 2, polymers 1 and 2, catalyst, additives 1 and 5, and stabilizing additives are blended into the first part, part A, and...

[0309] The treated pyrolytic silica 2, polymers 1 and 2, crosslinking agent 2, inhibitor, additive 5 and stabilizing additive are blended together into the second part, part B.

[0310] In each composition, the corresponding portions A and B are mixed together in a 1:1 weight ratio until homogeneous to obtain a liquid-curable silicone elastomer composition, which is then cured by direct compression molding into a button mold at 171°C for 20 minutes as indicated above.

[0311] The compositions of Reference 1 and Comparative Examples 1 to 7 (Comparative Examples 1 to 7) are depicted in Table 1a. Comparative Examples 1 to 7 were tested to evaluate the suitability of “stabilizing additives” 1 to 7 in stabilizing silicone rubbers when in direct contact with thermoplastic materials without flame retardants. In most cases, it is desirable that the selected “stabilizing additives” will contribute to the stabilization of silicone elastomers. Reference 1 does not contain the recommended stabilizers.

[0312] Table 1a: Composition (wt%) of Reference 1 and Comparative Compositions C.1 to C.7

[0313] Element Reference 1 C.1 C.2 C.3 C.4 C.5 C.6 C.7 Silicon dioxide 1 30.41 29.19 29.80 30.10 30.10 30.10 30.10 30.10 Polymer 1 59.96 57.58 58.80 59.40 59.40 59.40 59.40 59.40 Polymer 2 5.00 4.80 4.90 4.95 4.95 4.95 4.95 4.95 Karstedt catalyst 0.19 0.18 0.18 0.18 0.18 0.18 0.18 0.18 Crosslinking agent 1 1.62 1.55 1.58 1.60 1.60 1.60 1.60 1.60 Inhibitors 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.03 Additive 1 0.10 0.09 0.09 0.09 0.09 0.09 0.09 0.09 Additive 2 0.79 0.76 0.77 0.78 0.78 0.78 0.78 0.78 Additive 3 1.87 1.80 1.83 1.85 1.85 1.85 1.85 1.85 Additive 4 0.03 0.02 0.02 0.02 0.02 0.02 0.02 0.02 Stabilizing Additive 1 0.00 4.00 0.00 0.00 0.00 0.00 0.00 0.00 Stabilizing Additive 2 0.00 0.00 2.00 0.00 0.00 0.00 0.00 0.00 Stabilizer 3 0.00 0.00 0.00 1.00 0.00 0.00 0.00 0.00 Stabilizer 4 0.00 0.00 0.00 0.00 1.00 0.00 0.00 0.00 Stabilizing Additive 5 0.00 0.00 0.00 0.00 0.00 1.00 0.00 0.00 Stabilizing Additive 6 0.00 0.00 0.00 0.00 0.00 0.00 1.00 0.00 Stabilizer 7 0.00 0.00 0.00 0.00 0.00 0.00 0.00 1.00

[0314] To evaluate the effectiveness of each "stabilizer" used in the compositions employed, samples from Reference 1 (Reference 1) and Comparative Examples 1 to 7 were used in each case.

[0315] (a) In the first test, an aluminum substrate (Al) was sandwiched between both the top and bottom surfaces, and

[0316] (b) In the second test, as indicated, an equivalent sample is sandwiched between the top and bottom surfaces using a thermoplastic containing one of the aforementioned flame retardants-free thermoplastics.

[0317] According to ASTM D395-18 Method B, the sample was compressed at 25% for 168 hours at 175°C.

[0318] Each of C.1 through C.7 was evaluated to determine how much of the "stabilizer" contributed to stabilizing the tested silicone elastomer sample. The results are depicted in Table 1b below.

[0319] The percentage change in compressive deformation of unfilled PA66 to Al is determined by calculating the difference between the compressive deformation value when aluminum is the substrate and the compressive deformation value when unfilled PA66 is the substrate. For Reference 1, this percentage change is [missing value].

[0320] 44.1 - 34.7 = 9.4

[0321] And then this value is determined as a percentage of the aluminum value, for example,

[0322] (9.4 / 34.7)×100=27.1%

[0323] Table 1b: Solids after compression at 175°C for 168 hours according to ASTM D395-18 Method B, as per Reference 1 and C.1-C.7 Compression stability (%) of chemical samples

[0324]

[0325] Comparative examples of compositions containing heat stabilizers (such as copper phthalocyanine (C.1) and iron oxide (C.2)) reported in the prior art for improving the compression deformation of silicone elastomers show a higher percentage change in compression deformation than that of Reference 1.

[0326] Similar findings were observed for compositions containing acid removers such as magnesium hydroxide (C.3) reported in the prior art, showing a change of 39.7% percentage.

[0327] Comparative Examples (C.4 to C.7) correspond to liquid-curable silicone elastomer compositions containing stabilizing additives used as deacidifying agents.

[0328] When in contact with an unfilled PA66 substrate, the percentage change in compressive deformation of these comparative examples was higher than that of Reference 1. For example, the percentage change in compressive deformation of the calcium carbonate-containing C.4 composition was 34% when in contact with unfilled PA66.

[0329] The above is considered surprising because several of the above-mentioned additives were expected to stabilize the compression deformation results and were therefore considered suitable stabilizing additives that would help maintain the durability of silicone elastomers in direct contact with flame-retardant-free thermoplastics (e.g., in silicone-thermoplastic composites) over time.

[0330] The results are considered surprisingly poor, as one or two of the stabilizing additives mentioned above were expected to successfully help maintain the durability of silicone elastomers; however, significantly worse compression set results were achieved in most cases. In fact, even more surprisingly, despite the introduction of additives, the results were at best only slightly improved compared to Reference 1, but were significantly worse in general. Finally, none of the above-mentioned stabilizing additives are considered suitable for maintaining the durability of silicone elastomers in direct contact with thermoplastics, such as the durability over time in silicone-thermoplastic composites.

[0331] Another series of samples were prepared and their compression deformation was tested in the same manner. The compositions used to generate the elastomer samples are detailed in Table 2a below, relative to Reference 1 and Examples 1 to 3.

[0332] The Examples 1 to 3 of the present invention disclosed in Table 2a correspond to liquid-curable silicone elastomer compositions containing stabilizing additives selected from the group consisting of magnesium carbonate, hydroxymagnesium carbonate, and magnesium oxide, such as light magnesium carbonate (magnesium hydrate) (Akrochem) and Magox. TM 98HR magnesium oxide (Premier Magnesia, LLC).

[0333] Table 2a: Composition (wt%) of Reference 1 and Examples 1 to 3

[0334] Element Reference 1 Example 1 Example 2 Example 3 Silicon dioxide 1 30.41 30.10 29.95 30.10 Polymer 1 59.96 59.40 59.10 59.40 Polymer 2 5.00 4.95 4.92 4.95 Karstedt catalyst 0.19 0.18 0.18 0.18 Crosslinking agent 1 1.62 1.60 1.59 1.60 Inhibitors 0.03 0.03 0.03 0.03 Additive 1 0.10 0.09 0.09 0.09 Additive 2 0.79 0.78 0.78 0.78 Additive 3 1.87 1.85 1.84 1.85 Additive 4 0.03 0.02 0.02 0.02 Stabilizing Additive 8 0.00 1.00 1.50 0.00 Stabilizer 9 0.00 0.00 0.00 1.00

[0335] The samples were cured and tested in the same manner as described above, and the compression deformation results at 175°C for 168 hours are provided in Table 2b below.

[0336] Table 2b: Solids after compression at 175°C for 168 hours according to ASTM D395-18 Method B, as well as those of Reference 1 and Examples 1-3 Results of compression deformation (%) of the sample

[0337] Reference 1 Example 1 Example 2 Example 3 aluminum 34.7 35.2 45.3 40.3 Unfilled PA66 44.1 37.4 36.2 37.8 change% 27.1 6.2 -20.1 -6.2

[0338] Examples 1 and 2 contain 1.0 wt% and 1.5 wt% of stabilizing additive 8 (light magnesium carbonate, or hydromagnesia), respectively. When contacted with an unfilled PA66 substrate, they show percentage changes in compressive deformation of 6.2 and -20.1, respectively, which are significantly lower than those in Reference 1 (27.1%). The negative percentage change in Example 2 means that the compressive deformation (40.5%) of Example 2 containing 1.5 wt% light magnesium carbonate in unfilled PA66 is lower than that in Al (45.3%).

[0339] Similarly, it contains stabilizing additive 9 (Magox) TM Example 3 of 98 HR magnesium oxide (MgO) yielded a lower percentage change in compressive deformation (-6.2%).

[0340] The LSR compositions identified in Table 2a as Examples 1 and 3 were again used as the LSR compositions in Examples 4 and 5, respectively. They were used in contact with glass fiber reinforced thermoplastic PA66-GF25 without flame retardant. The results of Reference 1 and Examples 4 and 5 after contact with PA66-GF25 at 175°C for 168 hours are provided in Table 3 below.

[0341] Table 3: After compression at 175°C for 168 hours according to ASTM D395-18 Method B, Reference 1 and Example 4 and Compression deformation (%) of cured sample 5

[0342] Reference 1 Example 4 Example 5 aluminum 34.7 35.2 40.3 PA66-GF25 39.1 32.3 36.6 change% 12.7 -8.2 -9.2

[0343] Examples 4 and 5 have the same composition as Examples 1 and 3, which contain 1% by weight of stabilizing additives 8 and 9, respectively. The percentage changes in compression set of Examples 4 and 5 in PA66-GF25 were -8.2% and -9.2%, respectively, which were lower than the percentage change in Reference 1 (12.7%), thus confirming the benefits of stabilizing additives 8 and 9 in another type of flame-retardant-free thermoplastic.

[0344] The LSR compositions identified as Examples 1 and 3 in Table 2a were also used again as the LSR compositions of Examples 6 and 7, respectively. They were used in contact with glass fiber reinforced thermoplastic PA6-GF25 without flame retardants.

[0345] After contact with PA6-GF25 at 125°C for 1008 hours, the results of Reference 1 and Examples 6 and 7 are provided in Table 4 below.

[0346] Table 4: After compression for 1008 hours at 125°C according to ASTM D395-18 Method B, references 1 and Examples 6 and 7 Results of compression deformation (%) of the cured sample

[0347] Reference 1 Example 6 Example 7 aluminum 22.7 16.8 16.3 PA6-GF25 39.6 24.6 24.1 change% 74.4 46.4 47.9

[0348] When exposed to PA6-GF25, the compression set changes of Examples 6 (46.4%) and 7 (47.9%) were significantly improved compared to the results observed using Reference 1 (74.4%), thus demonstrating the benefits of stabilizing additives 8 and 9 in another type of flame-retardant-free thermoplastic and under different test conditions.

[0349] The LSR compositions identified as Examples 1 and 3 in Table 2a were also used again as the LSR compositions of Examples 8 and 9, respectively. They were used in contact with glass fiber reinforced thermoplastic PBT GF30 without flame retardant. The results of Reference 1 and Examples 8 and 9 after contact with PBT GF30 at 125°C for 1008 hours are provided in Table 5 below.

[0350] Table 5: After compression for 1008 hours at 125°C according to ASTM D395-18 Method B, Reference 1 and Examples 8 and 9 Results of compression deformation (%) of the cured sample

[0351] Reference 1 Example 8 Example 9 aluminum 22.7 16.8 16.3 PBT GF30 28.8 19.9 20.3 change% 26.9 18.5 24.5

[0352] After being exposed to PBT GF30 at 125°C for 1008 hours, Examples 8 and 9 showed lower compression set than Reference 1 material, thus further confirming the benefits of stabilizing additives 8 and 9 in another type of flame-retardant-free thermoplastic.

[0353] Further comparisons were made using the compositions in Table 6a. In Reference 2 and Example 10, additive 3 (trimethylsilyl-terminated phenylmethylsiloxane dimethylsiloxane copolymer) or 4 (ADK STAB) was absent. TM CDA-6). Therefore, Example 10 does not contain additives 3 or 4, but it does contain stabilizing additive 8 (light magnesium carbonate).

[0354] Table 6a. Composition (wt%) of Reference 2 and Example 10 .

[0355] Element Reference 2 Example 10 Pyrolysis of silicon dioxide 2 32.91 32.58 Polymer 1 59.34 58.75 Polymer 2 5.03 4.98 Karstedt catalyst 0.17 0.17 Inhibitors 0.04 0.04 Crosslinking agent 2 1.19 1.18 Additive 1 0.07 0.07 Additive 5 1.25 1.24 Stabilizing Additive 8 0.00 1.00

[0356] The compression deformation of Reference 2 and Example 10 was tested after being in contact with PA66-GF25 at 175°C for 168 hours, and the results are depicted in Table 6b below.

[0357] Table 6b. Compression deformation of cured samples after compression at 175°C for 168 hours according to ASTM D395-18 Method B. (%)result .

[0358] Reference 2 Example 10 aluminum 51.7 47.1 PA66-GF25 55.8 40.6 change% 7.9 -13.8

[0359] It should be understood that the percentage change in compressive deformation of Example 10 in PA66-GF25 is -13.8%, which is lower than the percentage change in compressive deformation of Reference 2 (7.9%).

[0360] In summary, all ten embodiments yielded significantly better results than the corresponding Reference Examples 1 and 2, and virtually all comparative examples. Given the results for the compositions in Table 1, failures were anticipated prior to the examples, making this improvement significant and surprising.

[0361] There appears to be some form of synergistic effect resulting from the use of magnesium carbonate, hydroxymagnesium carbonate, magnesium oxide, or mixtures thereof, and such materials successfully interact with species in the silicone elastomers that migrate into the composite material, thereby preventing the deterioration of compression deformation and thus maintaining the durability of the silicones in the composite article, despite their physical interaction with the thermoplastic.

[0362] In another series of embodiments (Examples 11, 12, and 13), the corresponding examples are made from silica masterbatches 1 and 2 and contain stabilizing additives 8 (light magnesium carbonate (magnesia magnesite, Akrochem)) and 9 (Magox). TM 98 HR magnesium oxide (Premier Magnesia, LLC) and 10 (basic light magnesium carbonate, catalog number AC211070010, Thermo Scientific) TM Liquid-curable silicone elastomer compositions are described. The compositions are shown in Table 7a below. In the cases of Examples 11 to 13 in Table 7a, liquid-curable silicone elastomer compositions were prepared using a masterbatch to prepare two-part compositions:

[0363] MB1 and MB2, polymer 2, catalyst, additives 1, 2 and 3, and stabilizing additives are blended into the first part (part A), and

[0364] Masterbatches MB1 and MB2, polymer 2, crosslinking agent 1, inhibitor, additives 2, 3 and 4, and stabilizing additives are blended into part two (part B). Once prepared, the two parts are mixed together in a 1:1 weight ratio until homogeneous to produce a liquid-curable silicone elastomer composition, which is then cured by direct compression molding into a button mold at 171°C for 20 minutes as indicated above.

[0365] Table 7a: Composition (wt%) of Examples 11, 12 and 13

[0366] Element Example 11 Example 12 Example 13 Silica masterbatch 1 84.12 83.13 85.12 Silica masterbatch 2 5.00 6.00 4.00 Polymer 2 5.00 5.00 5.00 Karstedt catalyst 0.19 0.19 0.19 Crosslinking agent 1 1.87 1.86 1.87 Inhibitors 0.03 0.03 0.03 Additive 1 0.10 0.10 0.10 Additive 2 0.79 0.79 0.79 Additive 3 1.87 1.87 1.87 Additive 4 0.03 0.03 0.03 Stabilizing Additive 8 1.00 0.00 0.00 Stabilizer 9 0.00 0.00 1.00 Stabilizing additive 10 0.00 1.00 0.00

[0367] These samples were cured and tested in the conventional manner discussed above, and the compression deformation results are provided in Table 7b below.

[0368] Table 7b: Solids of Examples 11, 12 and 13 after compression for 168 hours at 175°C according to ASTM D395-18 Method B. Results of compression deformation (%) of the sample

[0369] Example 11 Example 12 Example 13 aluminum 56.4 54.8 55.3 PA66-GF25 42.8 46.2 40.7 change% -24.1 -15.7 -26.4

[0370] When in contact with PA66-GF25, the compressive deformation changes of Examples 11, 12 and 13 were -24.1%, -15.7% and -26.4%, respectively, which are below the defined standard.

Claims

1. An organosilicon-thermoplastic composite material article, said organosilicon-thermoplastic composite material article comprising... (i) A flame-retardant-free thermoplastic article, wherein the flame-retardant-free thermoplastic article has a usable surface, and (ii) A cured silicone elastomer portion that is in direct contact with the available surface of the flame-retardant-free thermoplastic article (i), wherein the silicone elastomer portion is a cured product of a silicone elastomer composition comprising 0.25% by weight to a maximum of 5% by weight of a stabilizing additive selected from the group consisting of magnesium carbonate, hydroxy magnesium carbonate, magnesium oxide, and mixtures thereof.

2. The silicone-thermoplastic composite article according to claim 1, wherein the flame-retardant-free thermoplastic article (i) is selected from polyamide, polyoxymethylene, polyphenylene sulfide (PPS), polyacetal, polyamide-imide, polyphthalamide, polyetherimide, polyetherketone, polyetheretherketone, polyetherketoneketone, polyoxymethylene (acetal) homopolymer copolymer, syndiotactic polystyrene (sPS), compatibilizing blends of sPS and polyamide; polyester, polycarbonate (PC), polyether, maleic anhydride-grafted polyphenylene ether (PPO), maleic anhydride-grafted olefin elastomers and plasmons, polysulfone, polyethersulfone, polyarylsulfone, polyphenylene ether, polypropylene, polyethylene, aliphatic polyketone, thermoplastic styrene copolymer, polymethyl methacrylate (PMMA), and polyoxymethylene (POM).

3. The silicone-thermoplastic composite article according to claim 2, wherein the flame-retardant-free thermoplastic article (i) comprises PA6, PA66, PA6T / 66, PBT, PC and aliphatic polyketone, and optionally may contain up to 25%-35% by weight of glass fiber (GF) as a reinforcing additive.

4. The organosilicon-thermoplastic composite material product according to claim 1, wherein the stabilizing additive is selected from magnesite (MgCO3) and magnesia (MgCO3). 2H2O), trihydrate magnesite (MgCO3) 3H2O), pentahydrate magnesia (MgCO3) 5H2O); and one or more hydroxy magnesium carbonates and optionally may contain one or more metal deactivators.

5. The organosilicon-thermoplastic composite material product according to claim 1, wherein the one or more hydroxyl magnesium carbonates are selected from magnesium malachite (Mg2(CO3)(OH)2). 0.5H2O), magnesite (Mg2(CO3)(OH)2) 3H2O), hydromagnesia (Mg5(CO3)4(OH)2) 4H2O), spheroidal magnesia (Mg5(CO3)4(OH)2) 5H2O), heterohydrated magnesite (Mg5(CO3)4(OH)2) 5-6H2O) and Sherkov stone (Mg7(CO3)5(OH)4) 24H2O).

6. The organosilicon-thermoplastic composite article according to claim 4, wherein the metal deactivator is selected from compounds based on diacylhydrazine, compounds based on aminotriazole, compounds based on aminotriazine, or mixtures thereof.

7. The silicone-thermoplastic composite article according to claim 1, 2 or 3, wherein, in use, the silicone elastomer portion is sandwiched between two articles, at least one of the two articles being a thermoplastic article without flame retardant.

8. The silicone-thermoplastic composite article according to claim 1, 2 or 3, wherein, in use, the silicone elastomer portion is subjected to mechanical compression and exposed to a temperature greater than 85°C.

9. The silicone-thermoplastic composite material product according to claim 1, wherein the silicone-thermoplastic composite material product is an automotive part, cable accessory, electrical part, electronic part, packaging part, building part, household part, or gasket.

10. The silicone-thermoplastic composite article according to claim 9, wherein the silicone-thermoplastic composite article is an electrical connector or electronic connector having the following: a silicone elastomer seal or an electrical module housing or an electronic module housing optionally having a sealing cap, a radiator tank, a valve cover assembly, a sealed headlamp assembly, a potted electronic component, or an encapsulated electronic component.

11. A method for manufacturing an organosilicon-thermoplastic composite article according to claim 1, 2 or 3, the method comprising: (a) A curable silicone elastomer composition comprising 0.25% by weight to a maximum of 5% by weight of a stabilizing additive selected from the group consisting of: magnesium carbonate, magnesium hydroxycarbonate, magnesium oxide, and mixtures thereof. (b) Curing the curable silicone elastomer composition into a mold. (c) Physically bond the cured silicone elastomer to an available surface of a flame-retardant-free thermoplastic article (i) to form a silicone-thermoplastic composite article.

12. A method for manufacturing an organosilicon-thermoplastic composite article according to claim 1, 2 or 3, the method comprising: (a) A curable silicone elastomer composition comprising 0.25% by weight to a maximum of 5% by weight of a stabilizing additive selected from the group consisting of: magnesium carbonate, magnesium hydroxycarbonate, magnesium oxide, and mixtures thereof. (b) Contacting the curable silicone elastomer composition with a usable surface of the flame-retardant-free thermoplastic article (i). (c) Curing the curable silicone elastomer composition that is in contact with the usable surface of the flame-retardant-free thermoplastic article to form a silicone-thermoplastic composite article.

13. A method for manufacturing an organosilicon-thermoplastic composite article, wherein the organosilicon-thermoplastic composite article comprises (i) Thermoplastic articles free of flame retardants, The aforementioned flame-retardant-free thermoplastic article has a usable surface; and (ii) a silicone elastomer portion, wherein the silicone elastomer portion is physically bonded to the available surface of the flame-retardant-free thermoplastic; The method includes: (1) A curable silicone elastomer composition is provided, said curable silicone elastomer composition comprising a silicone elastomer composition curable by hydrogenation silanization reaction or a silicone elastomer composition curable by free radical reaction. The curable silicone elastomer composition further comprises 0.25% to a maximum of 5.0% by weight of stabilizing additives selected from the group consisting of: magnesium carbonate, magnesium hydroxycarbonate, magnesium oxide, and mixtures thereof; (2) Introduce the desired amount of the curable silicone elastomer composition into a mold. (3) Curing the curable silicone elastomer composition to form (ii) the silicone elastomer portion; (4) Physically bond the silicone elastomer seal of (ii) to the available surface of the thermoplastic article without flame retardant of (i), thereby forming the silicone-thermoplastic composite article.

14. The method for manufacturing an organosilicon-thermoplastic composite article according to claim 13, wherein the organosilicon-thermoplastic composite article is an electrical connector or electronic connector, the electrical connector or electronic connector comprising... (ia) One or more electrical wires; (ib) An electrical connector housing or an electronic connector housing, said electrical connector housing or electronic connector housing comprising a thermoplastic material free of flame retardants. The electrical connector housing or electronic connector housing has a first usable surface and a second surface opposite to the outer surface. The second surface defines a cavity, and The cavity contains the one or more wires (ia); and The silicone elastomer portion (ii) is a silicone elastomer seal, wherein the silicone elastomer seal is physically engaged with the first available surface of the electrical connector housing or electronic connector housing (ib).

15. A method for maintaining the durability of a silicone elastomer portion in physical contact with a flame-retardant-free thermoplastic, said silicone elastomer portion being subjected to mechanical compression and exposure to temperatures greater than 85°C during use, said method comprising the steps of: (1') A curable silicone elastomer composition is prepared, wherein the curable silicone elastomer composition further comprises 0.25% to a maximum of 5.0% by weight of a stabilizing additive selected from the group consisting of: magnesium carbonate, magnesium hydroxycarbonate, magnesium oxide, and mixtures thereof. (2') Introduce the desired amount of the curable silicone elastomer composition into a mold. (3') Curing the curable silicone elastomer composition to form the silicone elastomer portion (ii); (4') Physically bond the silicone elastomer portion (ii) to an available surface of the electrical connector housing or electronic connector housing to form the electrical connector or electronic connector.

Images