Flame-retardant liquid addition-cured silicone rubber composition for air bags

Abstract

An addition-curing type liquid silicone rubber composition for air bags, characterized by comprising: (A) an organopolysiloxane which is liquid at 25°C and contains two or more alkenyl groups bonded to silicon atoms in one molecule; (B) an organohydrogenpolysiloxane which contains two or more silicon-bonded hydrogen atoms in one molecule; (C) a silica powder having a BET specific surface area of 50 m 2 / g or more; (D) a catalyst for hydrosilylation reaction; (E) a functional group-containing organosilicon compound which imparts adhesion; (F) an organopolysiloxane resin having a three-dimensional network structure; and (G) an iron (III) oxide monohydrate, an alpha-iron (III) oxide, or both, having a pH of 5 to 9. Thus, an air bag and an addition-curing type liquid silicone rubber composition for air bags having excellent low burning speed and self-extinguishing properties as specified in FMVSS (Federal Motor Vehicle Safety Standards) No. 302 can be provided.

Description

Technical Field

[0001] This invention relates to an addition-curing liquid silicone rubber composition preferred for manufacturing flame-retardant airbags. Background Technology

[0002] Previously, a silicone rubber composition for airbags was proposed for the purpose of forming a rubber coating on the fiber surface. Airbags with silicone rubber coatings are preferred for use in automobiles and the like due to their excellent low combustion rate (flame retardancy). As a method for evaluating the flame retardancy of airbags, the FMVSS (Federal Motor Vehicle Safety Standard) No. 302 method for evaluating low ignition speed is known. This evaluation method differs significantly from the UL94 method, which typically evaluates the flame retardancy of silicone rubber. Therefore, even if the typical flame retardancy evaluation is good, there are many cases where the airbag is deemed unsuitable for use when evaluating its low ignition speed.

[0003] Examples of such silicone coating compositions for airbags include: an airbag obtained by coating a fiber surface with a liquid silicone composition containing a resinous polysiloxane and prepared by mixing the siloxane component with silica, a surface treatment agent, and water in advance (Patent Document 1); and an addition-curing liquid silicone rubber composition that uses an organohydrogen polysiloxane containing T-units or Q-units as a crosslinking agent, resulting in excellent strength of the coated substrate (Patent Document 2), etc.

[0004] However, when the conventional addition-curing liquid silicone rubber composition is coated onto the airbag base fabric and cured, the coated base fabric for airbags does not meet the low combustion rate requirement for airbag base fabric when coated with the low coating amount required in recent years.

[0005] Furthermore, it also discloses an addition-curing liquid silicone rubber composition with excellent adhesion, mechanical properties and durability by adding silicate mineral micro powders such as talc, kaolinite, and kaolinite (Patent Document 3); and an airbag with excellent flame retardancy by adding micro powdered manganese carbonate or zinc carbonate (Patent Document 4), etc.

[0006] However, existing technologies also suggest that adding silicate mineral powders or powders such as manganese carbonate and zinc carbonate would complicate the process and potentially impair mechanical strength. Existing technical documents Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2013-209517 Patent Document 2: Japanese Patent Publication No. 2019-513907 Patent Document 3: Japanese Patent Application Publication No. 2018-080421 Patent Document 4: Japanese Patent Application Publication No. 7-070923 Summary of the Invention The technical problem to be solved by the present invention

[0008] The present invention was made in view of the above circumstances, and its object is to provide an airbag with excellent low combustion speed and self-extinguishing properties as specified in FMVSS (Federal Motor Vehicle Safety Standard) No. 302, and an addition-curing liquid silicone rubber composition for airbags. Technical means to solve technical problems

[0009] To solve the above-mentioned technical problems, the present invention provides an addition-curing liquid silicone rubber composition for airbags, characterized in that it comprises: (A) An organopolysiloxane that is liquid at 25°C and contains two or more alkenyl groups bonded to silicon atoms in one molecule: 100 parts by mass (B) An organohydrogen polysiloxane containing two or more hydrogen atoms bonded to silicon atoms in one molecule: the amount of hydrosilyl contained in the composition relative to the total amount of 1 mole of silicon-bonded alkenyl groups contained in the composition is 1 to 10 moles. (C) The specific surface area of ​​the BET method is 50m². 2 1-50 parts by weight of silica micro powder with a density of / g or higher; (D) Catalyst for hydrosilylation reaction: catalytic amount; (E) Organosilicon compounds containing functional groups that impart adhesion: 0.1 to 10 parts by weight; (F) Organopolysiloxane resin with a three-dimensional network structure: 0.1 to 100 parts by weight; (G) Iron(III) monohydrate and / or α-iron(III) oxide at pH 5 to 9: 1 to 50 parts by weight.

[0010] If an addition-curing liquid silicone rubber composition is used for such an airbag, an airbag with excellent low combustion speed and self-extinguishing properties as specified in FMVSS NO.302 can be obtained.

[0011] Furthermore, the adhesive functional group of the (E) component is preferably selected from one or more groups selected from epoxy, silicon-bonded alkoxy, alkenyl, hydrogenated silyl, isocyanate, (meth)acryloyl, and (meth)acryloyloxy.

[0012] If such an addition-curing liquid silicone rubber composition is used for airbags, the adhesion of the silicone rubber composition to the base fabric of the airbag can be improved.

[0013] Preferably, it further contains 0.1 to 5 parts by mass of at least one condensation co-catalyst selected from organotitanium compounds, organozirconium compounds and organoaluminum compounds as the (H) component, relative to 100 parts by mass of component (A).

[0014] If an addition-curing liquid silicone rubber composition is used for such an airbag, adhesion can be improved.

[0015] Furthermore, the present invention provides an airbag having a cured coating of the above-mentioned addition-curing liquid silicone rubber composition for airbags on an airbag base fabric.

[0016] If it is such an airbag, then the low combustion speed and self-extinguishing properties specified in FMVSS NO.302 are excellent. Invention Effects

[0017] According to the present invention, a flame-retardant airbag with excellent low burning rate and self-extinguishing properties as specified in FMVSS NO.302 of the coated fabric can be obtained. Detailed Implementation

[0018] As stated above, the aim is to develop airbags with excellent low combustion speed and self-extinguishing properties as specified in FMVSS NO.302, and addition-curing liquid silicone rubber compositions for airbags.

[0019] In order to achieve the above-mentioned objectives, the inventors of this application conducted in-depth research and found that the addition-curing liquid silicone rubber composition, in which components (A) to (G) described below are essential components, is coated onto the surface of the base fabric for airbags and then heated and cured. This results in the airbag manufacturing silicone-coated base fabric having excellent flame retardancy and self-extinguishing properties, thus completing the present invention.

[0020] That is, the present invention is an addition-curing liquid silicone rubber composition for airbags, characterized in that it comprises: (A) 100 parts by mass of an organopolysiloxane that is liquid at 25°C and contains two or more alkenyl groups bonded to silicon atoms in one molecule; (B) An organohydrogen polysiloxane containing two or more hydrogen atoms bonded to silicon atoms in one molecule: the amount of hydrogenated silane contained in the composition relative to the total amount of silicon-bonded alkenyl groups contained in the composition is 1 to 10 moles per mole. (C) The specific surface area of ​​the BET method is 50m². 2 1-50 parts by weight of silica micro powder with a density of / g or higher; (D) Catalyst for hydrosilylation reaction: catalytic amount; (E) Organosilicon compounds containing functional groups that impart adhesion: 0.1 to 10 parts by weight; (F) Organopolysiloxane resin with a three-dimensional network structure: 0.1 to 100 parts by weight; (G) Iron(III) monohydrate and / or α-iron(III) oxide at pH 5 to 9: 1 to 50 parts by weight.

[0021] The present invention will now be described in detail, but it is not limited thereto. Furthermore, in this specification, viscosity is a value measured at 25°C using a rotational viscometer according to the method described in JIS K 7117-1:1999.

[0022] <Addition-curing liquid silicone rubber composition> The addition-curing liquid silicone rubber composition for airbags of the present invention contains the following components (A) to (G), and the composition is liquid at room temperature (25°C). Each component will be described in detail below.

[0023] [(A) ingredient] (A) is an organopolysiloxane that is liquid at 25°C and contains two or more alkenyl groups bonded to silicon atoms in one molecule, and is the base polymer (main agent) of the composition of the present invention. Furthermore, when (A) is a mixture of two or more components, the mixture only needs to be liquid at 25°C.

[0024] The molecular structure of component (A) is not particularly limited, and examples include linear, cyclic, and branched structures. Preferably, it is a linear organopolysiloxane whose main chain is essentially composed of repeating diorganosiloxane units and whose ends are capped with triorganosiloxy groups. Furthermore, when the molecular structure of the organopolysiloxane in component (A) is linear or branched, the position of the silicon atom bonded to the alkenyl group in the molecule can be either at the end of the molecular chain (i.e., the triorganosiloxy group) or in the middle of the molecular chain (i.e., a difunctional diorganosiloxane unit or a trifunctional monoorganosilsesquioxane unit located at a non-terminal point of the molecular chain), or both positions. As component (A), a linear organopolysiloxane containing at least an alkenyl group bonded to the silicon atoms at both ends of the molecular chain is particularly preferred.

[0025] The alkenyl group bonded to silicon atoms in component (A) is not particularly limited, but examples include alkenyl groups that typically have 2 to 8 carbon atoms, and preferably 2 to 4 carbon atoms. Specific examples include vinyl, allyl, propenyl, butenyl, pentenyl, hexenyl, cyclohexenyl, heptenyl, etc., with vinyl being particularly preferred.

[0026] The content of alkenyl groups bonded to silicon atoms in component (A) is preferably 0.001 to 10 mol% relative to the total monovalent organic groups (i.e., unsubstituted or substituted monovalent hydrocarbon groups) bonded to silicon atoms, and particularly preferably about 0.01 to 5 mol%.

[0027] The monovalent organic groups bonded to silicon atoms, other than alkenyl groups, that constitute component (A) are not particularly limited. Examples include unsubstituted or substituted monovalent hydrocarbon groups, typically having 1 to 12 carbon atoms, and preferably 1 to 10 carbon atoms, which may be the same as or different from each other. Specific examples of monovalent organic groups include alkyl groups such as methyl, ethyl, propyl, butyl, pentyl, hexyl, cyclohexyl, and heptyl; aryl groups such as phenyl, tolyl, xylyl, and naphthyl; aralkyl groups such as benzyl and phenethyl; and halogen-substituted alkyl groups such as chloromethyl, 3-chloropropyl, and 3,3,3-trifluoropropyl, with methyl being particularly preferred.

[0028] The degree of polymerization (weight-average degree of polymerization) of component (A) is preferably 50 to 2,000, more preferably 100 to 1,500. If the degree of polymerization is 50 or higher, the resulting silicone rubber exhibits good mechanical properties. Furthermore, if the degree of polymerization is 2,000 or lower, the viscosity of the resulting silicone rubber composition can be kept low, resulting in good coating workability, which is therefore preferred. Additionally, when component (A) is a mixture of multiple components, the sum of the products of the degree of polymerization of each component and its mass fraction is taken as the degree of polymerization of component (A). In addition, in this specification, "degree of polymerization" refers to the weight-average molecular weight obtained by gel permeation chromatography (GPC) using polystyrene as a standard substance, measured under the following conditions, and the value calculated based on that weight-average molecular weight (the same applies below). [Measurement Conditions] Developing solvent: Toluene Flow rate: 1 mL / min Detector: Differential refractive index detector (RI) Chromatographic column: KF-805L × 2 (manufactured by Shodex) Column temperature: 25℃ Sample injection volume: 20 μL (0.1% by mass toluene solution)

[0029] Specific examples of organopolysiloxanes as component (A) include: dimethylsiloxane-methylvinylsiloxane copolymers with trimethylsiloxy-terminated ends; methylvinylpolysiloxanes with trimethylsiloxy-terminated ends; dimethylsiloxane-methylvinylsiloxane-methylphenylsiloxane copolymers with trimethylsiloxy-terminated ends; dimethylsiloxane-methylpolysiloxanes with dimethylsiloxy-terminated ends; dimethylvinylsiloxane-methylvinylpolysiloxanes with dimethylsiloxy-terminated ends; and dimethylsiloxane-methylsiloxane-methylpolysiloxanes with dimethylsiloxy-terminated ends. The following are examples of copolymers of oxyalkane and methyl vinyl siloxane: dimethyl siloxane-methyl vinyl siloxane-methyl phenyl siloxane-terminated dimethyl polysiloxane, dimethyl siloxane-methyl vinyl siloxane-methyl vinyl siloxane-methyl vinyl siloxane-terminated dimethyl polysiloxane, dimethyl siloxane-methyl vinyl siloxane-methyl vinyl siloxane-terminated dimethyl polysiloxane, trivinyl siloxane-methyl vinyl siloxane-methyl vinyl siloxane-methyl vinyl siloxane-terminated dimethyl polysiloxane, trivinyl siloxane-methyl vinyl siloxane-methyl vinyl siloxane-methyl vinyl siloxane-terminated dimethyl polysiloxane, and mixtures of two or more of the above-mentioned organopolysiloxanes.

[0030] (A) The organopolysiloxane of component (A) can be used alone or in combination with two or more components.

[0031] [(B) Component] The organohydrogen polysiloxane in component (B) mainly undergoes a hydrogenation-silanization addition reaction with the alkenyl group in component (A) and functions as a crosslinking agent (curing agent). The molecular structure of component (B) is not particularly limited. For example, various structures such as linear, cyclic, branched, and three-dimensional network (resin-like) structures can be listed. However, it must have at least two, preferably three or more, hydrogen atoms (hydrosilyl groups) bonded to silicon atoms in one molecule. Ideally, it usually has 2 to 300, preferably 3 to 200, and more preferably 4 to 100 hydrosilyl groups, and it is preferably liquid at 25°C. Such hydrosilyl groups can be located at any position at the end of the molecular chain, in the middle of the molecular chain, or in both of these positions.

[0032] As the organohydrogen polysiloxane, a substance represented by the following average composition formula (1) can be used. [Chemical Formula 1] R 1 a H b SiO (4-a-b) / 2 (1)

[0033] In equation (1), R 1These are unsubstituted or substituted monovalent hydrocarbon groups bonded to silicon atoms, preferably having 1 to 10 carbon atoms, other than aliphatic unsaturated bonds such as alkenyl groups, and may be identical or different from each other. Examples include alkyl groups such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, neopentyl, hexyl, cyclohexyl, octyl, nonyl, and decyl; aryl groups such as phenyl, tolyl, xylyl, and naphthyl; and aralkyl groups such as benzyl, phenethyl, and phenylpropyl. Alternatively, groups formed by substituting some or all of the hydrogen atoms in these groups with halogen atoms such as fluorine, bromine, or chlorine may be included, for example, chloromethyl, chloropropyl, bromoethyl, and trifluoropropyl. As R 1 Preferably, it is alkyl or aryl, and more preferably methyl. Furthermore, it is preferred that a and b are positive numbers satisfying a = 0.7 to 2.1, b = 0.001 to 1.0, and a+b = 0.8 to 3.0, and more preferably that a and b are positive numbers satisfying a = 1.0 to 2.0, b = 0.01 to 1.0, and a+b = 1.5 to 2.5.

[0034] Examples of organohydropolysiloxanes that are components of this type (B) include 1,1,3,3-tetramethyldisiloxane, 1,3,5,7-tetramethylcyclotetrasiloxane, tris(dimethylsiloxy)methylsilane, tris(dimethylsiloxy)phenylsilane, methylhydrocyclopolysiloxane, methylhydrosiloxane·dimethylsiloxane cyclic copolymer, methylhydropolysiloxane with trimethylsiloxy-terminated ends, methylhydropolysiloxane with trimethylsiloxy-terminated ends, methylhydrosiloxane·methylhydrosiloxane copolymer, methylhydrosiloxane·methylphenylsiloxane·methylphenylsiloxane copolymer, and methylhydrosiloxane·methylhydrosiloxane·diphenylsiloxane·methylhydrosiloxane·diphenylsiloxane copolymer. Oxyalkane copolymers, dimethylhydrosiloxy-terminated methylhydropolysiloxanes, dimethylhydrosiloxy-terminated dimethylpolysiloxanes, dimethylhydrosiloxy-terminated dimethylsiloxanes·methylhydrosiloxane copolymers, dimethylhydrosiloxy-terminated dimethylsiloxanes·methylphenylsiloxane copolymers, dimethylhydrosiloxy-terminated dimethylsiloxanes·diphenylsiloxane copolymers, dimethylhydrosiloxy-terminated methylphenylpolysiloxanes, dimethylhydrosiloxy-terminated diphenylpolysiloxanes, or substances formed by substituting some or all of the methyl groups in the above-described compounds with ethyl, propyl, or other alkyl groups, derived from the formula: R 2 3SiO 1 / 2 The siloxane unit represented by R is the same as the formula: 2 2HSiO 1 / 2 The siloxane unit represented by the formula: SiO 4 / 2 The organosiloxane copolymer represented by the siloxane unit, derived from the formula: R 22HSiO 1 / 2 The siloxane unit represented by the formula: SiO 4 / 2 The organosiloxane copolymer represented by the siloxane unit, derived from the formula: R 2 HSiO 2 / 2 The siloxane unit represented by R is the same as the formula: 2 SiO 3 / 2 The siloxane unit or formula represented by: HSiO 3 / 2 The term refers to organosiloxane copolymers composed of siloxane units, and mixtures composed of two or more of the aforementioned organopolysiloxanes. R in the above formula... 2 It is a monovalent hydrocarbon group other than an alkenyl group.

[0035] The amount of component (B) is such that the total number of moles of hydrosilyl groups in the composition relative to the total number of silicon-bonded alkenyl groups in the composition is 1 to 10 moles. For example, the amount of component (B) is such that the total number of moles of hydrosilyl groups in component (B) relative to the total number of silicon-bonded alkenyl groups in component (A) is 1 to 10 moles, preferably 1.2 to 9 moles, more preferably 1.5 to 8 moles, more preferably 1.5 to 8 moles, of hydrosilyl groups in component (B) relative to the total number of silicon-bonded alkenyl groups in component (A). If the amount of hydrogenated silane in the composition is less than 1 mole relative to the total amount of silicon atoms bonded to alkenes in the composition, the composition will not cure sufficiently. Furthermore, if it is greater than 10 moles, the heat resistance of the resulting cured silicone rubber may be extremely poor.

[0036] (B) The organohydrogen polysiloxane component can be used alone or in combination with two or more components.

[0037] [(C) Component] (C) The silica micropowder acts as a reinforcing filler. That is, by using silica micropowder as a reinforcing filler, it imparts strength to the cured silicone rubber obtained from the composition of the present invention, enabling the formation of a coating film with the strength required for the airbag. The specific surface area (BET method) of this silica micropowder must be 50 m². 2 / g or more, preferably 50-400m 2 / g, more preferably 100-300m 2 / g, if the specific surface area is less than 50m² 2 If the particle size is less than 1 / g, it cannot impart the required strength properties. Typically, the primary particle size of silica micropowder is 1–100 nm, but due to its high cohesion, it is difficult to accurately determine the particle size (aggregate particle size).

[0038] Such silica micro powder can be a known silica micro powder that has been used as a reinforcing filler for silicone rubber, provided that its specific surface area is within the above-mentioned range. Examples include fumed silica (gas phase silica) and precipitated silica (wet silica).

[0039] The aforementioned silica micropowder can be, for example, silica micropowder whose surface has been hydrophobically treated with a surface treatment agent such as a chlorosilane, alkoxysilane, organosilazane, or other (usually hydrolyzable) organosilicon compound. In this case, these silica micropowders can be substances that have undergone surface hydrophobic treatment directly with a surface treatment agent in a powder state beforehand, or substances that have undergone surface hydrophobic treatment by adding a surface treatment agent when mixing with silicone oil (e.g., an alkenyl-containing organopolysiloxane of component (A) above).

[0040] As a common treatment method for component (C), surface treatment can be performed using known techniques. For example, the untreated silica micropowder and surface treatment agent can be added to a sealed mechanical mixing device or flow layer under normal pressure, and mixed as needed in the presence of an inactive gas, at room temperature (25°C) or under heat treatment (heating). Sometimes water or a catalyst (hydrolysis accelerator, etc.) can also be used to promote surface treatment. After mixing, drying is performed, thereby producing surface-treated silica micropowder. The amount of surface treatment agent added should be at least the amount calculated based on the coverage area of ​​the surface treatment agent.

[0041] Specifically, surface treatment agents include silazanes such as hexamethyldisilazane, methyltrimethoxysilane, ethyltrimethoxysilane, propyltrimethoxysilane, butyltrimethoxysilane, dimethyldimethoxysilane, diethyldimethoxysilane, vinyltriethoxysilane, vinyltrimethoxysilane, trimethylmethoxysilane, triethylmethoxysilane, vinyltri(methoxyethoxy)silane, trimethylchlorosilane, dimethyldichlorosilane, divinyldimethoxysilane, and chloropropyltrimethoxysilane, as well as polymethylsiloxane and organohydrogen polysiloxane. These surface treatment agents can be used to treat surfaces and produce hydrophobic silica micropowders for use. Silazanes are particularly preferred as surface treatment agents.

[0042] The amount of component (C) is 1 to 50 parts by mass relative to 100 parts by mass of the organopolysiloxane of component (A), preferably 5 to 30 parts by mass. If the amount of component (C) is too small, the required strength of the airbag cannot be obtained; if the amount of component (C) is too large, the viscosity of the composition will increase, the fluidity will decrease, and the workability of the coating may deteriorate.

[0043] (C) Micronized silica powder can be used alone or in combination with two or more components.

[0044] [(D) component] The hydrosilylation reaction of component (D) is promoted by a catalyst to facilitate the addition reaction between the silicon-bonded alkenyl groups in the composition and the hydrosilylation alkyl groups in the composition. The catalyst primarily promotes the addition reaction between the silicon-bonded alkenyl groups in component (A) and the hydrosilylation alkyl groups in component (B). The catalyst for this hydrosilylation reaction is not particularly limited, and examples include platinum group metals such as platinum, palladium, and rhodium; chloroplatinic acid; alcohol-modified chloroplatinic acid; coordination compounds of chloroplatinic acid with olefins, vinylsiloxanes, or acetylene compounds; platinum group metal compounds such as tetra(triphenylphosphine)palladium and tri(triphenylphosphine)rhodium chloride, etc., preferably platinum group metal compounds.

[0045] The amount of component (D) should be the effective amount (catalytic amount) as a catalyst. Based on the total mass of components (A) to (C), and converted to the mass of the catalyst metal element, it is preferably 1 to 500 ppm, more preferably 5 to 100 ppm. If it is 1 ppm or more, the addition reaction will not be significantly slowed down or the composition will not fail to cure; if it is 500 ppm or less, the heat resistance of the cured product will not decrease.

[0046] (D) The catalyst used for the hydrogenation and silylation reaction of component (D) can be a single catalyst or two or more catalysts can be used simultaneously.

[0047] [(E) component] Component (E) is an organosilicon compound containing functional groups that impart adhesive properties. Examples of functional groups that impart adhesive properties include epoxy groups, silicon-bonded alkoxy groups (alkoxysilyl groups), alkenyl groups, hydrogenated silyl groups, isocyanate groups, (meth)acryloyl groups, (meth)acryloyloxy groups, etc. Component (E) is added to improve the adhesion of the silicone rubber composition to the base fabric of the airbag.

[0048] As an organosilicon compound, any organosilicon compound can be used as long as it has such adhesive functional groups. It is preferred to have organosilicon compounds having one or more epoxy groups and silicon atoms bonded to alkoxy groups in one molecule. From the perspective of adhesive performance, it is more preferred to have organosilicon compounds having at least one epoxy group and at least one silicon atom bonded to alkoxy group (e.g., trialkoxysilyl, organodialkoxysilyl, etc.), such as organosilanes; or cyclic or linear organosilicon alkoxides having at least one epoxy group and at least two silicon atoms bonded to alkoxy groups with a silicon atom number of 1 to 100, preferably about 1 to 50.

[0049] The epoxy group is not particularly limited, but is preferably bonded to silicon atoms in the form of glycidyl etheroxypropyl or other glycidyl etheroxyalkyl groups; or epoxy-containing cyclohexyl alkyl groups such as 2,3-epoxycyclohexylethyl and 3,4-epoxycyclohexylethyl. There are no particular limitations on the bonding of silicon atoms to alkoxy groups, but it is preferred that they bond with silicon atoms to form trialkoxysilyl groups such as trimethoxysilyl, triethoxysilyl, etc.; alkyldialkoxysilyl groups such as methyldimethoxysilyl, ethyldimethoxysilyl, methyldiethoxysilyl, ethyldiethoxysilyl, etc.

[0050] In addition, component (E) may have at least one functional group in one molecule, for example, selected from the group consisting of vinyl alkenyl, (meth)acryloyl, (meth)acryloyloxy, isocyanate group and hydrogen silyl group, as a functional group other than epoxy group and silicon atom bonded alkoxy group.

[0051] Organosilicon compounds that are components of (E), such as γ-glycidyl etheroxypropyltriethoxysilane, γ-glycidyl etheroxypropylmethyldiethoxysilane, (3,4-epoxycyclohexylethyl)trimethoxysilane, (3,4-epoxycyclohexylethyl)triethoxysilane, (3,4-epoxycyclohexylethyl)methyldimethoxysilane, (3,4-epoxycyclohexylethyl)methyldiethoxysilane, (2,3-epoxycyclohexylethyl)triethoxysilane, (2,3-epoxycyclohexylethyl)methyldimethoxysilane, and (2,3-epoxycyclohexylethyl)methyldiethoxysilane, etc., containing epoxy groups. In addition to silane coupling agents (i.e., organoalkoxysilanes containing epoxy functional groups), vinyl-containing silane coupling agents such as vinyltrimethoxysilane, silane coupling agents containing (meth)acryloyl groups such as 3-(meth)acryloyloxypropyltrimethoxysilane, silane coupling agents containing isocyanate groups such as 3-isocyanate-propylethoxysilane, or methoxysilane modifiers of triallyl isocyanurate, other examples include cyclic organopolysiloxanes or linear organopolysiloxanes represented by the following chemical formulas, mixtures of two or more of them, or partially hydrolyzed condensates of one or more of them.

[0052] [Chemical Formula 2] In the formula, R is one or more of -CH2CH2CH2Si(OCH3)3, h is an integer from 1 to 10, k is an integer from 0 to 40, preferably an integer from 0 to 20, p is an integer from 1 to 40, preferably an integer from 1 to 20, and q is an integer from 1 to 10.

[0053] The amount of component (E) is 0.1 to 10 parts by mass relative to 100 parts by mass of the organopolysiloxane component (A), preferably 0.25 to 5 parts by mass. If the amount of component (E) is less than 0.1 parts by mass, the resulting composition may not exhibit sufficient adhesive strength. If the amount of component (E) is greater than 10 parts by mass, the cost increases and it becomes uneconomical. In addition, the coating properties deteriorate due to the increase in tackification and thixotropy.

[0054] Furthermore, when component (E) contains alkenyl and / or hydrosilyl groups, the amount of component (E) is such that the total amount of hydrosilyl groups in the composition relative to the total amount of silicon-bonded alkenyl groups in the composition is 1 to 10 moles. For example, relative to the total amount of silicon-bonded alkenyl groups in components (A) and (E) of the composition, the total amount of hydrosilyl groups in components (B) and (E) can be set to 1 to 10 moles, preferably 1.2 to 9 moles, and more preferably 1.5 to 8 moles. If the amount of hydrosilyl groups is less than 1 mole relative to the silicon-bonded alkenyl groups in the composition, the composition may not cure sufficiently and will not exhibit sufficient adhesive strength. On the other hand, if the amount is greater than 10 moles, the heat resistance of the resulting cured silicone rubber may be extremely poor.

[0055] (E) Components can be used alone or in combination with two or more.

[0056] [(F)INGREDIENT] (F) The component is an organopolysiloxane resin characterized by a three-dimensional network (resin-like) structure. Preferably, it is substantially composed of R... 3 SiO 3 / 2 Single-unit and four-functional SiO 4 / 2 It is composed of at least one branched siloxane unit in the unit, and may contain any monofunctional R as needed. 3 3SiO 1 / 2 R of single and / or bifunctional 3 2SiO 2 / 2 The unit functions as a flame retardant improver. This organopolysiloxane resin may contain alkenyl groups in its molecule, but does not contain silicon atoms bonded to hydrogen atoms (hydrogenated silyl groups). Furthermore, this organopolysiloxane resin has a three-dimensional network (resin-like) structure and is powdery at 25°C, thus it can be clearly distinguished from component (A), which has a linear structure and is liquid at 25°C.

[0057] R in the above formula 3The monovalent hydrocarbon groups, which are the same as or different from each other, have 1 to 10 unsubstituted or substituted carbon atoms, preferably 1 to 8. Examples of such groups include alkenyl and monovalent organic groups (unsubstituted or substituted monovalent hydrocarbon groups) shown in component (A) above. Specifically, examples include alkenyl groups such as vinyl, allyl, propenyl, butenyl, pentenyl, hexenyl, cyclohexenyl, and heptenyl; alkyl groups such as methyl, ethyl, propyl, butyl, pentyl, hexyl, cyclohexyl, and heptyl; aryl groups such as phenyl, tolyl, xylyl, and naphthyl; aralkyl groups such as benzyl and phenethyl; and halogen-substituted alkyl groups such as chloromethyl, 3-chloropropyl, and 3,3,3-trifluoropropyl. Methyl and vinyl groups are particularly preferred.

[0058] The content of alkenyl groups bonded to silicon atoms in component (F) is preferably 0 to 10 mol%, and particularly preferably about 2 to 8 mol%, relative to the total substituents bonded to silicon atoms.

[0059] (F) The organopolysiloxane resin preferably contains R 3 SiO 3 / 2 Unit and / or SiO 4 / 2 The unit is preferably set to 20-75 mol% of the organopolysiloxane resin of component (F), and particularly preferably 30-60 mol%. Here, as mentioned above, the organopolysiloxane resin of component (F) may contain R arbitrarily. 3 3SiO 1 / 2 Units and / or R 3 2SiO 2 / 2 The total content of the unit is preferably set to 0 to 70 mol% of the organopolysiloxane resin of component (F), and particularly preferably 0 to 50 mol%. If R in component (F) of the organopolysiloxane resin 3 SiO 3 / 2 Unit and / or SiO 4 / 2 Sufficient flame retardancy improvement can be achieved when the total amount of the unit is in the range of 20 to 75 mol%, which is therefore preferred.

[0060] Furthermore, the weight-average molecular weight of the organopolysiloxane resin of component (F), as determined by GPC (gel permeation chromatography) with toluene as the developing solvent, is preferably in the range of 2,000 to 50,000, and particularly preferably 4,000 to 20,000. If the weight-average molecular weight is in the range of 2,000 to 50,000, sufficient flame retardancy improvement can be obtained, resulting in a viscosity suitable for a liquid silicone rubber coating composition with good coating operability. This weight-average molecular weight is a value obtained through GPC analysis under the same conditions used to determine the degree of polymerization of component (A) above.

[0061] Specific examples of organopolysiloxane resins as component (F) can be listed as those derived from the formula: R'3SiO 1 / 2 The siloxane unit represented is the same as the formula: R'2R”SiO 1 / 2 The siloxane unit represented is the same as the formula: R'2SiO 2 / 2 The siloxane unit represented by the formula: SiO 4 / 2 The organosiloxane copolymer represented by siloxane units, derived from the formula: R'3SiO 1 / 2 The siloxane unit represented is the same as the formula: R'2R”SiO 1 / 2 The siloxane unit represented by the formula: SiO 4 / 2 The organosiloxane copolymer represented by the siloxane unit, derived from the formula: R'2R”SiO 1 / 2 The siloxane unit represented is the same as the formula: R'2SiO 2 / 2 The siloxane unit represented by the formula: SiO 4 / 2 The organosiloxane copolymer represented by the siloxane unit, derived from the formula: R'R”SiO 2 / 2 The siloxane unit represented by the formula: R'SiO 3 / 2 The siloxane unit or formula represented by: R”SiO 3 / 2 Organosiloxane copolymers composed of siloxane units, and mixtures composed of two or more of these organopolysiloxanes.

[0062] In the above formula, R' represents a monovalent hydrocarbon group (excluding alkenyl groups) that is the same or different from each other, with 1 to 10 unsubstituted or substituted carbon atoms, preferably 1 to 8. Examples of such groups include alkyl groups such as methyl, ethyl, propyl, butyl, pentyl, hexyl, cyclohexyl, and heptyl; aryl groups such as phenyl, tolyl, xylyl, and naphthyl; aralkyl groups such as benzyl and phenethyl; and haloalkyl groups such as chloromethyl, 3-chloropropyl, and 3,3,3-trifluoropropyl, with methyl being particularly preferred. Furthermore, R" in the above formula represents an alkenyl group. Examples of such groups include vinyl, allyl, butenyl, pentenyl, hexenyl, and heptenyl, with vinyl being particularly preferred.

[0063] The amount of component (F) is 0.1 to 100 parts by weight relative to 100 parts by weight of the organopolysiloxane component (A), preferably 1 to 95 parts by weight, and particularly preferably 2 to 90 parts by weight. If the amount of component (F) is outside the range of 0.1 to 100 parts by weight, sufficient improvement in flame retardancy cannot be obtained, and the cost-effectiveness is also poor.

[0064] Furthermore, when component (F) contains an alkenyl group, the amount of component (F) is such that 1 mole of the hydrosilyl group contained in the composition is 1 to 10 moles relative to the total number of silicon-bonded alkenyl groups contained in the composition. For example, component (F) can be set such that 1 to 10 moles (or units) of the hydrosilyl group contained in components (B) and (E) are relative to the total number of silicon-bonded alkenyl groups contained in components (A), (E), and (F) in the composition, preferably 1.2 to 9 moles (or units), and more preferably 1.5 to 8 moles (or units).

[0065] Furthermore, if further explanation is provided, when components (A), (E), and (F) containing alkenes are used in combination, the ratio of the total number of moles of hydrogenated silanes to the total number of 1 mole of alkenes in each component of the composition should be taken into account when blending. For example, if the silica micropowder of component (C) is a substance that has been directly hydrophobically treated in the powder state using a surface treatment agent containing alkenyl groups, component (F) contains alkenyl groups, and component (E) contains alkenyl groups and / or hydrosilyl groups, the total amount of hydrosilyl groups contained in components (B) and (E) relative to the total amount of silicon atoms (or nitrogen atoms) bonded alkenyl groups contained in components (A), (C), (E) and (F) in the composition is 1 to 10 moles, preferably 1.2 to 9 moles, more preferably 1.5 to 8 moles. As above, this is because if the total amount of hydrogenated silanes is less than 1 mole relative to the total amount of silicon atoms bonded to alkenes in the composition, the composition may not cure sufficiently and will not exhibit sufficient adhesive strength. On the other hand, if the amount of hydrogenated silanes is greater than 10 moles, the heat resistance of the resulting cured silicone rubber may be extremely poor.

[0066] Thus, in this invention, each component is incorporated in such a manner that the total number of moles of hydrogenated silanes is 1 to 10 moles relative to the total number of 1 mole of alkenyl groups in each component contained in the addition-curing liquid silicone rubber composition for airbags.

[0067] (F) The three-dimensional network organopolysiloxane resin can be used alone or in combination with two or more components.

[0068] [(G) component] Relative to 100 parts by mass of component (A), the amount of iron(III) monohydrate and / or α-iron(III) in component (G) is 1 to 50 parts by mass, preferably 1.1 to 40 parts by mass, more preferably 1.1 parts by mass or more but less than 25 parts by mass, and even more preferably 1.2 to 6.0 parts by mass. If the amount of admixture is within the above range, the resulting cured product exhibits excellent flame retardancy. On the other hand, if the amount of component (G) is less than 1 part by mass, the flame retardancy of the cured product is insufficient; if it is greater than 50 parts by mass, the mechanical strength may be compromised. Furthermore, iron(III) monohydrate and α-iron(III) can be used separately or simultaneously. Furthermore, according to the ambient temperature extraction method described in JIS K 5101-17-2; 2004, the pH of component (G) is 5 to 9, preferably 5.5 to 8.5. If the pH is outside this range, the self-extinguishing property is poor. Furthermore, the particle size of component (G) is not particularly limited as long as the above conditions are met, but is preferably 0.01 to 10 μm in terms of BET average particle size, and particularly preferably 0.05 to 5 μm. If the BET average particle size is 0.01 μm or more, the viscosity of the obtained silicone rubber composition becomes lower, and the workability is not reduced; if it is 10 μm or less, the mechanical strength of the obtained silicone rubber is not impaired. Examples of (G) ingredients include Toda Color TSY-1 (TODA PIGMENT CORP., pH 6.0), Toda Color TSY-2 (TODA PIGMENT CORP., pH 6.0), Toda Color 100ED (TODA PIGMENT CORP., pH 6.0), and Toda Color 130ED (TODA PIGMENT CORP., pH 6.0).

[0069] [Other ingredients] In addition to components (A) to (G) described above, any other components may be incorporated into the compositions of the present invention as needed. Specific examples include the following substances. These other components may be used individually or in combination of two or more.

[0070] 〃(H) component The condensation cocatalyst of component (H) is at least one selected from organotitanium compounds, organozirconium compounds, and organoaluminum compounds, and functions as a condensation cocatalyst that imparts adhesiveness to the functional group in component (E) in order to promote adhesion. Specific examples of component (H) include: Titanium-based condensation cocatalysts (titanium compounds) for organic titanates such as tetraisopropyl titanate, tetra-n-butyl titanate, and tetraoctyl titanate, as well as organic titanium chelating compounds such as diisopropoxybis(acetylacetone)titanium, diisopropoxybis(ethoxyacetyl)phthaloyl, and tetraacetylacetone titanium. Zirconium-based condensation cocatalysts (zirconium compounds) such as tetra-n-propylzirconate, tetra-n-butylzirconate, and other organozirconates, as well as organozirconium chelates such as tributoxymonoacetylacetone zirconium, monobutoxyacetylacetone bis(ethyl acetoacetate)zirconium, and tetraacetylacetone zirconium. Aluminum-based condensation co-catalysts (aluminum compounds) for organoaluminum chelates such as sec-butoxyaluminum esters, aluminum triacetylacetone, aluminum monoacetylacetone bis(ethyl acetoacetate)aluminum, and tri(ethyl acetoacetate)aluminum.

[0071] The condensation catalyst of component (H) can be any component incorporated as needed, and its incorporation amount is preferably 0.1 to 5 parts by mass, more preferably 0.2 to 4 parts by mass, relative to 100 parts by mass of component (A). If the incorporation amount is within the above range, the resulting cured product exhibits excellent adhesion durability under high temperature and high humidity conditions.

[0072] "Reaction control agent" The reaction control agent is not particularly limited as long as it is a compound that has a curing inhibition effect on the catalyst used in the hydrosilylation reaction of component (D), and well-known reaction control agents can be used. Specific examples include phosphorus-containing compounds such as triphenylphosphine; nitrogen-containing compounds such as tributylamine, tetramethylethylenediamine, and benzotriazole; sulfur-containing compounds; acetylene compounds such as acetylenols; compounds containing two or more alkenyl groups; hydrogen peroxide compounds; and maleic acid derivatives.

[0073] Since the degree of curing inhibition effect of reaction control agents varies depending on the chemical structure of the reaction control agent, it is preferable to adjust the amount of reaction control agent added to the most suitable amount for each reaction control agent used. By adding the most suitable amount of reaction control agent, the composition exhibits excellent long-term storage stability and curability at room temperature.

[0074] Non-reinforcing filler As a non-reinforcing filler other than silica micropowder of component (C), examples include crystalline silica (e.g., BET specific surface area less than 50 m²). 2 / g quartz powder), hollow fillers made of organic resin, polymethylsilsesquioxane microparticles (so-called silicone resin powder), fumed titanium dioxide, magnesium oxide, zinc oxide, ferrous oxide (II), aluminum hydroxide, magnesium carbonate, calcium carbonate, zinc carbonate, carbon black, diatomaceous earth, talc, kaolinite, glass fiber and other fillers; fillers after surface hydrophobic treatment of these fillers by organosilicon compounds such as organoalkoxysilane compounds, organochlorosilane compounds, organosilazane compounds, low molecular weight siloxane compounds, etc.

[0075] Other ingredients In addition, it can also be incorporated into organopolysiloxanes containing one silicon atom bonded to a hydrogen atom in one molecule but no other functional groups, organopolysiloxanes containing one silicon atom bonded to an alkenyl group in one molecule but no other functional groups, non-functional organopolysiloxanes (so-called dimethyl silicone oil) that contain neither silicon atom bonded to hydrogen atoms nor silicon atom bonded to alkenyl groups and other functional groups, organic solvents, creep-resistant hardeners, plasticizers, thixotropic agents, pigments, dyes, mildew inhibitors, etc.

[0076] <Preparation of Addition-Curing Liquid Silicone Rubber Compositions> By uniformly mixing the above-mentioned components (A) to (G) and other components such as component (H) as needed, an addition-curing liquid silicone rubber composition can be prepared. For example, by uniformly mixing component (A) (all or part), component (C), and other components as needed to prepare a base compound, and further mixing in components (A) (balance), (B), (D), (E), (F), (G), and component (H) as needed, and then uniformly mixing, an addition-curing liquid silicone rubber composition can be prepared. The mixing of the raw materials for preparing the addition-curing liquid silicone rubber composition for airbags according to the present invention can be carried out using any known method and apparatus for preparing addition-curing liquid silicone rubber compositions. Examples of usable apparatus include known mixing devices such as two-roll mixers, three-roll mixers, kneader mixers, planetary mixers, and ROSS mixers. The resulting addition-curing liquid silicone rubber composition for airbags is a liquid composition at 25°C. The viscosity at 25°C, measured using a type B rotational viscometer as described in JIS K 7117-1:1999, is preferably 1 to 1,000 Pa·s, more preferably 5 to 300 Pa·s. Within this viscosity range, uneven coating or insufficient adhesion to the base fabric after curing is less likely to occur when coated onto the airbag base fabric, thus making it preferable for use.

[0077] <Airbag Base Fabric> In this invention, the base fabric (substrate made of fiber cloth) for airbags formed from the silicone rubber layer composed of the cured product of the above-mentioned addition-curing liquid silicone rubber composition can be any known base fabric. Specific examples include various polyester fibers such as polyethylene terephthalate (PET) and polybutylene terephthalate (PBT), and various synthetic fibers such as 6,6-nylon and 6-nylon polyamide fibers.

[0078] <Inventory Manufacturing Method> The above-described addition-curing liquid silicone rubber composition is applied to at least one surface, particularly one surface, of an airbag base fabric (a substrate made of fiber cloth), and then cured by heating in a drying oven or the like, thereby forming a silicone rubber layer (cured coating). Airbags can be manufactured using the silicone rubber-coated base fabric for airbags thus obtained.

[0079] Here, conventional methods can be used to coat the addition-curing liquid silicone rubber composition onto the base fabric of the airbag, but a doctor blade coater is preferred. The coating thickness (or surface coating weight) is typically preferred to be 5 to 100 g / m². 2 More preferably 8-90 g / m 2 More preferably, it is 10–80 g / m 2 .

[0080] Addition-curing liquid silicone rubber compositions can be cured under known curing conditions and by known curing methods, thereby obtaining a cured coating of the composition. Specifically, for example, the composition can be cured by heating at 100–200°C for 1–30 minutes.

[0081] When processing an airbag base fabric (airbag silicone rubber coated base fabric) having a silicone rubber layer (cured coating) on ​​at least one surface into an airbag, one method can be used to bond the outer peripheries of two plain-weave fabrics, at least the inner side of the airbag coated with silicone rubber, together with an adhesive and then sew their adhesive layers together. Alternatively, a method can be used to coat both outer sides of the airbag base fabric, which has been pre-hollow-weave manufactured, with an addition-curing liquid silicone rubber composition applied in a specified amount as described above, and then cured under specified curing conditions. Furthermore, the adhesive used here can be a known adhesive; from the perspective of adhesive strength or adhesive durability, an organosilicon adhesive, also known as a seam sealant, is preferred. Example

[0082] The following describes preparation examples, embodiments, and comparative examples to specifically illustrate the present invention, but the present invention is not limited to the embodiments described below. Furthermore, the viscosity is the value measured at 25°C using a rotational viscometer as described in JIS K 7117-1:1999. The methods for determining the average degree of polymerization and weight-average molecular weight are as described above. The BET average particle size is the value measured by the BET method.

[0083] [Preparation Example 1] The following ingredients were added: 60 parts by mass of dimethylpolysiloxane (A1), whose molecular chains were end-capped with vinyldimethylsiloxy groups and had a viscosity of 30,000 mPa·s at 25°C and an average degree of polymerization of 750; 8 parts by mass of hexamethyldisilazane; 2 parts by mass of water; and 40 parts by mass of a specific surface area of ​​300 m² / s (calculated by the BET method). 2 / g of silica micro-powder (C) (Aerosil 300, manufactured by NIPPON AEROSIL CO.,LTD.) was added to a kneader and mixed at room temperature for 1 hour. The temperature was then raised to 150°C and mixing continued for 2 hours. Then, the mixture was cooled to room temperature and 25 parts by mass of dimethylpolysiloxane (A1) and 5 parts by mass of dimethyl-vinylmethylpolysiloxane (A2) were added and mixed evenly to obtain the basic composite (1) (Table 1). The dimethylpolysiloxane (A1) had its molecular chain end capped with vinyldimethylsiloxy groups, a viscosity of 30,000 mPa·s at 25°C, and an average degree of polymerization of 750. The dimethyl-vinylmethylpolysiloxane (A2) contained 5 mol% vinylmethylsiloxane units and 95 mol% dimethylsiloxane units in the difunctional organosiloxane units constituting the main chain, and its molecular chain end capped with trimethylsiloxy groups, a viscosity of 700 mPa·s at 25°C, and an average degree of polymerization of 200.

[0084] [Table 1] A1 85 A2 5 C 40 Hexamethyldisilazane 8 water 2

[0085] [Example 1] In the basic composite (1) obtained in Preparation Example 1 with 150 parts by mass, 10 parts by mass of vinyl dimethyl siloxy-terminated dimethyl polysiloxane (A3) with a molecular chain end vinyl dimethyl siloxy-terminated dimethyl polysiloxane with a viscosity of about 5,000 mPa·s and an average degree of polymerization of 450, 60.5 parts by mass of vinyl dimethyl siloxy-terminated dimethyl polysiloxane (A4) with a molecular chain end vinyl dimethyl siloxy-terminated dimethyl polysiloxane with a viscosity of about 1,000 mPa·s and an average degree of polymerization of 200, 52.8 parts by mass of vinyl dimethyl siloxy-terminated dimethyl polysiloxane (A5) with a molecular chain end vinyl dimethyl siloxy-terminated dimethyl polysiloxane with a viscosity of about 400 mPa·s and an average degree of polymerization of 160, and 14 parts by mass as crosslinking The binder has a viscosity of 45 mPa·s at 25°C. It consists of a dimethylsiloxane-methylhydrosiloxane copolymer (B) with silicon-bonded hydrogen atoms at both ends of the molecular chain side chains (Silicon-bonded hydrogen atom content = 0.0108 mol / g), 0.56 parts by weight of γ-glycidyl etheroxypropyltrimethoxysilane (E), 0.09 parts by weight of 1-ethynylcyclohexanol, 0.45 parts by weight of a dimethyl polysiloxane solution (D) containing 1% by weight of chloroplatinic acid / 1,3-divinyltetramethyldisiloxane complex (based on platinum atom content), and 10 parts by weight of (CH3)3SiO2. 1 / 2 Unit with 6.5 mol% (CH3)2(CH2=CH)SiO 1 / 2 Unit with 54 mol% SiO 4 / 2 Composition A (hydrogenated siloxane / vinyl (hereinafter, H / Vi, molar ratio: 4.6, viscosity 51 Pa·s) was prepared by mixing a three-dimensional network structure of organopolysiloxane resin (F) (weight average molecular weight: 6,000), 0.34 parts by mass of tetraoctyltitanium (H), and 2.83 parts by mass of Fe2O3 (G1) (α-iron oxide (III): Toda Color 130ED: TODA PIGMENT CORP., BET average particle size 0.16 μm, pH 6.0) for 1 hour.

[0086] <Test Method for Combustion Rate> Composition A is coated at a rate of 20–25 g / m². 2After being coated onto the PET base fabric (470 dtex) for airbags, the coated base fabric was cured in a dryer at 190°C for 1 minute and its flame retardancy was evaluated using the method specified in FMVSS NO. 302. The silicone rubber coated side of the base fabric (10 cm wide × 35 cm long) used as the test piece was placed face up, and the burning distance and burning time until the flame extinguished according to the method described in FMVSS NO. 302 were measured. The burning rate was calculated based on the burning distance and burning time. At this time, any of the following conditions were considered acceptable for flame retardancy: (1) the test piece did not ignite or extinguished itself before the A mark (SE); (2) it extinguished itself within a burning distance of 51 mm (and within 60 seconds) (SE); (3) the burning rate was 102 mm / min or less. Even if only one test piece was completely burned, it was considered unacceptable for flame retardancy. Measurements were performed with N=10, and the average value was used as the evaluation result. The results are shown in Table 2. Furthermore, the self-extinguishing rate (SE rate) was calculated using the following formula, and the results are recorded in Table 2. Additionally, a higher SE rate is considered to indicate better flame retardancy. SE rate (%) = ((1) Number of test pieces that do not ignite or extinguish themselves before the A mark + (2) Number of test pieces that extinguish themselves within 51 mm (and within 60 seconds)) / 10 × 100

[0087] [Example 2] Except that the amount of vinyl dimethylsiloxy-terminated dimethyl polysiloxane (A5) with a molecular chain of approximately 400 mPa·s and an average degree of polymerization of 160 at both ends was increased to 55.7 parts by mass and Fe2O3 (G1) was increased to 5.65 parts by mass, composition B (H / Vi = 4.6, viscosity 52 Pa·s) was prepared in the same manner as in Example 1. The results of the combustion rate test conducted in the same manner as in Example 1 are shown in Table 2.

[0088] [Example 3] Except that the amount of vinyl dimethylsiloxy-terminated dimethyl polysiloxane (A5) with a molecular chain of approximately 400 mPa·s and an average degree of polymerization of 160 at both ends was increased to 61.3 parts by mass and the amount of Fe2O3 (G1) was increased to 11.3 parts by mass, composition C (H / Vi = 4.6, viscosity 54 Pa·s) was prepared in the same manner as in Example 1. The results of the combustion rate test conducted in the same manner as in Example 1 are shown in Table 2.

[0089] [Example 4] Except that Fe2O3(G1) in Example 1 was replaced with 2.83 parts by mass of Fe2O3·H2O(G2) (iron(III) monohydrate: Toda Color TSY-1: TODA PIGMENT CORP., pH 6.0), composition D (H / Vi = 4.6, viscosity 52 Pa·s) was prepared in the same manner as in Example 1, and the results of the combustion rate test conducted in the same manner as in Example 1 are shown in Table 2.

[0090] [Example 5] Except that Fe2O3(G1) in Example 1 was replaced with 5.65 parts by mass of Fe2O3·H2O(G2) (iron(III) monohydrate: Toda Color TSY-1: TODA PIGMENT CORP., pH 6.0), composition E (H / Vi = 4.6, viscosity 54 Pa·s) was prepared in the same manner as in Example 1, and the results of the combustion rate test conducted in the same manner as in Example 1 are shown in Table 2.

[0091] [Example 6] Except that Fe2O3(G1) in Example 1 was replaced with 11.3 parts by mass of Fe2O3·H2O(G2) (iron(III) monohydrate: Toda Color TSY-1: TODA PIGMENT CORP., pH 6.0), composition F (H / Vi = 4.6, viscosity 56 Pa·s) was prepared in the same manner as in Example 1, and the results of the combustion rate test conducted in the same manner as in Example 1 are shown in Table 2.

[0092] [Example 7] Except that the Fe2O3 (G1) in Example 1 was reduced to 1.42 parts by mass and 1.42 parts by mass of Fe2O3·H2O (G2) was added, composition G (H / Vi = 4.6, viscosity 51 Pa·s) was prepared in the same manner as in Example 1. The results of the combustion rate test conducted in the same manner as in Example 1 are shown in Table 2.

[0093] [Comparative Example 1] Except that the amount of vinyl dimethylsiloxy-terminated dimethyl polysiloxane (A5) with a molecular chain of approximately 400 mPa·s and an average degree of polymerization of 160 in Example 1 was reduced to 51.7 parts by mass, and the amount of Fe2O3 (G1) was reduced to 1.70 parts by mass, composition H (H / Vi = 4.6, viscosity 48 Pa·s) was prepared in the same manner as in Example 1. The results of the combustion rate test conducted in the same manner as in Example 1 are shown in Table 2.

[0094] [Comparative Example 2] Except for not incorporating vinyl dimethylsiloxy-terminated dimethyl polysiloxane (A5) and Fe2O3 (G1) at both ends of the molecular chain with a viscosity of approximately 400 mPa·s and an average degree of polymerization of 160 as in Example 1, Composition I (H / Vi = 4.6, viscosity 46 Pa·s) was prepared in the same manner as in Example 1, and the results of the combustion rate test conducted in the same manner as in Example 1 are shown in Table 2.

[0095] [Comparative Example 3] Except that Fe2O3(G1) in Example 1 was replaced with 2.33 parts by mass of Fe3O4 (Toda Color KN-320: TODAPIGMENT CORP., BET average particle size 0.27 μm, pH 9.5), composition J (H / Vi = 4.6, viscosity 52 Pa·s) was prepared in the same manner as in Example 1, and the results of the combustion rate test conducted in the same manner as in Example 1 are shown in Table 2.

[0096] [Comparative Example 4] Except that the amount of vinyl dimethylsiloxy-terminated dimethyl polysiloxane (A3) with a molecular chain of approximately 5,000 mPa·s and an average degree of polymerization of 450 in Example 1 was increased to 20 parts by mass, and Fe2O3 (G1) was replaced with 10 parts by mass of TiO2, composition K (H / Vi = 4.6, viscosity 54 Pa·s) was prepared in the same manner as in Example 1. The results of the combustion rate test conducted in the same manner as in Example 1 are shown in Table 2.

[0097] [Comparative Example 5] Except that Fe2O3(G1) in Example 1 was replaced with 2.83 parts by mass of Fe2O3·H2O (Toda Color TSY-4: TODA PIGMENT CORP., pH 4.5), composition L (H / Vi = 4.6, viscosity 52 Pa·s) was prepared in the same manner as in Example 1, and the results of the combustion rate test conducted in the same manner as in Example 1 are shown in Table 2.

[0098] For Examples 1-7 and Comparative Examples 1-5, the amount of components used is shown in Table 2. Furthermore, the amounts in the table are converted to values ​​relative to 100 parts by mass of component (A). Component (D) is the value converted from the mass of catalyst metal elements relative to the total mass of components (A) to (C).

[0099] [Table 2]

[0100] In summary, as long as the airbag-type addition-curing silicone rubber composition of the present invention is used, the low burning rate (flame retardancy) and self-extinguishing rate (SE rate) specified in FMVSS NO. 302 are excellent, as shown in Examples 1 to 7. On the other hand, Comparative Examples 1 and 2, which have little or no (G) component, have satisfactory low burning rate but low SE rate. Furthermore, Comparative Examples 3 and 4, which use Fe3O4 or TiO2 instead of (G), have poor low burning rate and low self-extinguishing rate. Moreover, Comparative Example 5, which uses Fe2O3·H2O with a pH of 4.5, has satisfactory low burning rate but low SE rate.

[0101] Furthermore, the present invention is not limited to the above-described embodiments. The above embodiments are illustrative examples, and any technical solutions that have substantially the same composition and perform the same effects as the technical concept described in the claims of the present invention are included within the scope of protection of the present invention.

Claims

1. An addition-curing liquid silicone rubber composition for airbags, characterized in that, Include: (A) 100 parts by mass of an organopolysiloxane that is liquid at 25°C and contains two or more alkenyl groups bonded to silicon atoms in one molecule; (B) An organohydrogen polysiloxane containing two or more hydrogen atoms bonded to silicon atoms in one molecule: the amount of hydrogenated silane contained in the composition relative to the total amount of silicon-bonded alkenyl groups contained in the composition is 1 to 10 moles per mole. (C) The specific surface area of ​​the BET method is 50m². 2 1-50 parts by weight of silica micro powder with a density of / g or higher; (D) Catalyst for hydrosilylation reaction: catalytic amount; (E) Organosilicon compounds containing functional groups that impart adhesion: 0.1 to 10 parts by weight; (F) Organopolysiloxane resin with a three-dimensional network structure: 0.1~100 parts by weight; (G) Iron(III) oxide monohydrate, α-iron(III) oxide, or both, at pH 5-6: 1-6.0 parts by weight. The addition-curing liquid silicone rubber composition for airbags further contains 0.1 to 5 parts by weight of at least one condensation co-catalyst selected from organotitanium compounds, organozirconium compounds, and organoaluminum compounds as component (H) relative to 100 parts by weight of component (A), wherein the particle size of component (G) is 0.01 to 10 μm based on the BET average particle size. The adhesive functional group of component (E) is selected from one or more groups selected from epoxy, silicon-bonded alkoxy, alkenyl, hydrogenated silyl, isocyanate, (meth)acryloyl, and (meth)acryloyloxy.

2. An airbag, characterized in that, The airbag base fabric has a cured coating of the addition-curing liquid silicone rubber composition for airbags as described in claim 1.

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