Addition-curable liquid silicone rubber composition for airbags, and airbag

Abstract

The present invention is an addition-curable liquid silicone rubber composition for airbags which comprises (A) a linear organopolysiloxane, (B) a three-dimensional net-like organopolysiloxane resin in powder form, (C) an organohydrogen polysiloxane that contains two or more hydrosilyl groups per molecule, (D) a silica fine powder that has a BET method specific surface area of not less than 50m2 / g, (E) a hydrosilylation reaction catalyst, (F) an organic silicon compound that contains an adhesiveness-imparting functional group, and (G) an expanded graphite powder that has a median diameter of 0.1-50 μm, wherein the content of the component (C) is such that the total of hydrosilyl groups in the composition is 1-10 moles per 1 mole of the total of silicon atom binding alkenyl groups in the composition. Thus, provided is an addition-curable liquid silicone rubber composition for airbags in which coating unevenness is unlikely to occur during coating, and which makes it possible to easily detect defective products.

Description

Addition-curable liquid silicone rubber composition for airbags and airbags

[0001] The present invention relates to an addition-curable liquid silicone rubber composition for airbags and to an airbag.

[0002] Silicone rubber compositions for airbags have been proposed for forming rubber coatings on fiber surfaces. Airbags with silicone rubber coatings are suitable for use in automobiles and other vehicles due to their excellent internal pressure retention and low combustion rate.

[0003] Such addition-curable liquid silicone rubber compositions for airbags include those that use an organohydrogenpolysiloxane containing T or Q units as a crosslinking agent (Patent Document 1). Coated fabrics coated with this composition are characterized by excellent strength. Patent Document 2 also discloses an addition-curable liquid silicone rubber composition for airbags that incorporates a silicone resin composed of M, D, and Q units, with only the D units containing crosslinkable functional groups, as a flame retardant. Airbags coated with this composition are characterized by a slow burning rate.

[0004] On the other hand, in recent years, there has been a trend toward reducing the coating weight of silicone rubber compositions to save space and reduce weight. Therefore, there is a need for the development of silicone rubber compositions for airbags that have the same flame retardancy as conventional compositions even with a low coating weight. One method for improving flame retardancy is to incorporate a flame retardant. For example, compositions incorporating iron(III) oxide monohydrate or α-iron(III) oxide as a flame retardant into a silicone rubber composition (Patent Document 3) and compositions incorporating carbon black (Patent Documents 4 and 5) have been disclosed. However, incorporating a flame retardant with a strong coloring power, such as iron oxide or carbon black, into a silicone rubber composition can cause coating mottle during coating, which can impair the appearance. Furthermore, the manufacturing process for airbag base fabrics involves multiple steps, such as weaving the base fabric, washing, drying, coating with a silicone material, heat-curing the silicone material, and winding up the coated base fabric. If defects such as stains, scratches or holes occur in the airbag base fabric during these processes, and the silicone rubber coating on the airbag base fabric is dark in color and has strong hiding power, it may be difficult to detect these defects by visual inspection or image inspection using a camera.

[0005] Special Publication No. 2019-513907 Publication International Publication No. 2018 / 168315 Publication No. 2022-072086 Publication No. 2022-072086 Publication No. 7-300774 Publication No. 7-195990

[0006] The present invention has been made in view of the above circumstances, and has as its object to provide an addition-curable liquid silicone rubber composition for air bags that is less likely to cause coating unevenness during coating, that produces coated air bag base fabrics that have a slow burning rate, and that allow for easy detection of defects such as stains, scratches, and holes, and that provides an air bag having a cured coating of the composition.

[0007] In order to solve the above problems, the present invention provides an addition-curable liquid silicone rubber composition for airbags, comprising: (A) 100 parts by mass of a linear organopolysiloxane having a weight-average degree of polymerization of 50 to 2,000 and containing two or more alkenyl groups bonded to silicon atoms per molecule; (B) 5 to 100 parts by mass of a powdery three-dimensional network organopolysiloxane resin (provided that the organopolysiloxane resin does not contain hydrosilyl groups); (C) an organohydrogenpolysiloxane containing two or more hydrosilyl groups per molecule; (D) an organohydrogenpolysiloxane having a BET specific surface area of ​​50 m ２ / g or more: 1 to 50 parts by mass, (E) a hydrosilylation reaction catalyst: 1 to 500 ppm, calculated as the mass of the catalytic metal element, based on the total mass of components (A) to (D), (F) an organosilicon compound containing an adhesion-imparting functional group: 0.1 to 10 parts by mass, and (G) expanded graphite powder having a median diameter of 0.1 to 50 μm: 0.1 to 1 part by mass, wherein the total amount of hydrosilyl groups contained in the composition is 1 to 10 moles per mole of the total amount of silicon-bonded alkenyl groups contained in the composition.

[0008] A silicone-coated airbag fabric having a cured coating of this addition-curable liquid silicone rubber composition for airbags has excellent flame retardancy, is less prone to coating mottle, and makes it easy to detect defects such as stains, scratches, and holes.

[0009] Furthermore, in the present invention, it is preferable that the component (H) contains 0.05 to 5 parts by mass of one or more condensation catalysts selected from organotitanium compounds, organozirconium compounds, and organoaluminum compounds, per 100 parts by mass of the component (A).

[0010] If such an addition-curable liquid silicone rubber composition for air bags is used, the silicone-coated base fabric for air bags made from it will have excellent adhesive properties.

[0011] In the present invention, the component (F) is preferably an organosilicon compound having, in one molecule, one or more reactive silyl groups selected from an alkoxysilyl group, an alkenyl-containing silyl group, and a hydrosilyl group, and one or more reactive organic groups selected from an epoxy group, an isocyanate group, and a (meth)acrylic group.

[0012] Such an addition-curable liquid silicone rubber composition for air bags provides superior adhesion of the silicone rubber layer to the air bag fabric.

[0013] The present invention also provides an airbag having a cured coating of the addition-curable liquid silicone rubber composition for airbags of the present invention on an airbag base fabric, wherein the cured coating surface has an L value of 60 or greater when measured using the L*a*b* color system.

[0014] Such an air bag has excellent flame retardancy, is less likely to develop coating spots, and allows easy detection of defects such as stains, scratches, holes, etc.

[0015] As described above, the present invention can provide an addition-curable liquid silicone rubber composition for air bags that, when coated onto an air bag base fabric and cured, has excellent flame retardancy, is less likely to cause coating spots, and allows for easy detection of defective products, as well as an air bag.

[0016] As a result of extensive research into the above-mentioned problems, the present inventors discovered that an addition-curable liquid silicone rubber composition for air bags containing expanded graphite powder, when coated onto an airbag base fabric and cured, would provide a coated base fabric with excellent flame retardancy, would be less likely to develop coating spots, and would enable easy detection of defects such as stains, scratches, and holes, thereby completing the present invention.

[0017] That is, the present invention provides an addition-curable liquid silicone rubber composition for air bags, comprising: (A) 100 parts by mass of a linear organopolysiloxane having a weight-average degree of polymerization of 50 to 2,000 and containing two or more alkenyl groups bonded to silicon atoms per molecule; (B) 5 to 100 parts by mass of a powdery three-dimensional network organopolysiloxane resin (provided that the organopolysiloxane resin does not contain hydrosilyl groups); (C) an organohydrogenpolysiloxane containing two or more hydrosilyl groups per molecule; (D) an organohydrogenpolysiloxane having a BET specific surface area of ​​50 m ２ / g or more: 1 to 50 parts by mass, (E) a hydrosilylation reaction catalyst: 1 to 500 ppm, calculated as the mass of the catalytic metal element, based on the total mass of the components (A) to (D), (F) an organosilicon compound containing an adhesion-imparting functional group: 0.1 to 10 parts by mass, and (G) expanded graphite powder having a median diameter of 0.1 to 50 μm: 0.1 to 1 part by mass, and the composition contains the component (C) in an amount such that the total number of hydrosilyl groups contained in the composition is 1 to 10 moles per mole of the total number of silicon-bonded alkenyl groups contained in the composition.

[0018] The present invention will be described in detail below, but the present invention is not limited thereto.

[0019] In this specification, the viscosity is a value measured at 25° C. using a rotational viscometer in accordance with the method described in JIS K 7117-1: 1999. The weight-average degree of polymerization is a value determined as a polystyrene-equivalent weight-average molecular weight (weight-average degree of polymerization) by GPC (gel permeation chromatography) analysis using tetrahydrofuran (THF) as a developing solvent, measured under the following conditions:

[0020] [Measurement conditions] Developing solvent: tetrahydrofuran Flow rate: 0.35 mL / min Detector: differential refractive index detector (RI) Column: TSK Guard column Super H-L TSKgel Super H4000 (6.0 mm I.D. × 15 cm × 1) TSKgel Super H3000 (6.0 mm I.D. × 15 cm × 1) TSKgel Super H2000 (6.0 mm I.D. × 15 cm × 2) (all manufactured by Tosoh Corporation) Column temperature: 40°C Sample injection volume: 10 μL (tetrahydrofuran solution with a concentration of 0.5 wt%)

[0021] <Addition-Curable Liquid Silicone Rubber Composition for Air Bags> The addition-curable liquid silicone rubber composition for air bags of the present invention comprises: (A) 100 parts by mass of a linear organopolysiloxane having a weight-average degree of polymerization of 50 to 2,000 and containing two or more alkenyl groups bonded to silicon atoms per molecule; (B) 5 to 100 parts by mass of a powdery three-dimensional network organopolysiloxane resin (provided that the organopolysiloxane resin does not contain hydrosilyl groups); (C) an organohydrogenpolysiloxane containing two or more hydrosilyl groups per molecule; (D) an organohydrogenpolysiloxane having a BET specific surface area of ​​50 m ２ / g or more: 1 to 50 parts by mass, (E) a hydrosilylation reaction catalyst: 1 to 500 ppm, calculated as the mass of the catalytic metal element, based on the total mass of the components (A) to (D), (F) an organosilicon compound containing an adhesion-imparting functional group: 0.1 to 10 parts by mass, and (G) expanded graphite powder having a median diameter of 0.1 to 50 μm: 0.1 to 1 part by mass, wherein the composition contains component (C) in an amount such that the total number of hydrosilyl groups contained in the composition is 1 to 10 moles per mole of the total number of silicon-bonded alkenyl groups contained in the composition, and the composition is liquid at room temperature (25°C).

[0022] Each component will be described in detail below.

[0023] [Component (A)] In the present invention, the organopolysiloxane of component (A) is an organopolysiloxane that contains two or more silicon-bonded alkenyl groups per molecule and has a degree of polymerization of 50 to 2,000, and is the base polymer (main component) of the addition-curable liquid silicone rubber composition for airbags of the present invention.

[0024] The molecular structure of component (A) is also characterized by being linear. Among these, diorganopolysiloxanes whose main chain is essentially composed of repeating diorganosiloxane units and whose molecular chain ends are blocked with triorganosiloxy groups are preferred. Furthermore, the position of the silicon atom to which the alkenyl group is bonded in the linear organopolysiloxane molecule of component (A) may be either at the molecular chain end (i.e., triorganosiloxy group) or in the molecular chain (i.e., bifunctional diorganosiloxane units located at non-terminal positions), or both. A particularly preferred component (A) is a linear diorganopolysiloxane containing alkenyl groups bonded to silicon atoms at at least both molecular chain ends.

[0025] The alkenyl group bonded to a silicon atom in component (A) typically contains 2 to 8 carbon atoms, and preferably 2 to 4 carbon atoms. Specific examples include vinyl, allyl, propenyl, butenyl, pentenyl, hexenyl, cyclohexenyl, and heptenyl groups, with vinyl groups being particularly preferred.

[0026] The number of alkenyl groups bonded to silicon atoms in component (A) is two or more per molecule, preferably 2 to 100, and more preferably 2 to 50.

[0027] The silicon-bonded monovalent substituted or unsubstituted hydrocarbon group other than an alkenyl group in component (A) typically includes monovalent hydrocarbon groups having 1 to 12 carbon atoms, and preferably 1 to 10 carbon atoms. Specific examples of monovalent hydrocarbon 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 weight-average degree of polymerization of component (A) is 50 to 2,000, preferably 100 to 1,500, and more preferably 120 to 1,000. If the weight-average degree of polymerization is lower than 50, the mechanical properties of the resulting addition-curable liquid silicone rubber composition for air bags may deteriorate, while if the weight-average degree of polymerization is higher than 2,000, the viscosity of the resulting addition-curable liquid silicone rubber composition for air bags may increase, resulting in poor coating workability.

[0029] The viscosity of component (A) at 25° C. is preferably 50 to 200,000 mPa·s, more preferably 100 to 150,000 mPa·s, and even more preferably 400 to 100,000 mPa·s. If the viscosity of component (A) is 50 mPa·s or higher, the mechanical properties of the resulting addition-curable liquid silicone rubber composition for air bags will be good, and if it is 200,000 mPa·s or lower, the viscosity of the resulting addition-curable liquid silicone rubber composition for air bags will not be too high, and coating workability will also be favorable.

[0030] Specific examples of organopolysiloxanes of component (A) include dimethylsiloxane-methylvinylsiloxane copolymers capped at both molecular chain terminals with trimethylsiloxy groups, methylvinylpolysiloxanes capped at both molecular chain terminals with trimethylsiloxy groups, dimethylsiloxane-methylvinylsiloxane-methylphenylsiloxane copolymers capped at both molecular chain terminals with trimethylsiloxy groups, dimethylpolysiloxanes capped at both molecular chain terminals with dimethylvinylsiloxy groups, methylvinylpolysiloxanes capped at both molecular chain terminals with dimethylvinylsiloxy groups, and dimethylsiloxane-methylvinylpolysiloxanes capped at both molecular chain terminals with dimethylvinylsiloxy groups. and mixtures of two or more of these organopolysiloxanes.

[0031] The organopolysiloxane of component (A) may use either a single compound, or a combination of two or more different compounds.

[0032] [Component (B)] The powdery three-dimensional network organopolysiloxane resin of component (B) (provided that the organopolysiloxane resin does not contain hydrosilyl groups) acts as a flame retardancy improver. Component (B) preferably contains a trifunctional R １ SiO ３／２ units and tetrafunctional SiO ４／２ The siloxane unit may be a monofunctional R １ ３ SiO １／２ units and / or bifunctional R １ ２ SiO ２／２However, this organopolysiloxane resin does not contain any silicon-bonded hydrogen atoms (hydrosilyl groups) in the molecule. Furthermore, this organopolysiloxane resin has a three-dimensional network (resinous) structure and is in powder form at 25°C, and is therefore clearly distinguishable from the aforementioned component (A), which has a linear structure.

[0033] The above R １ are independently a monovalent substituted or unsubstituted hydrocarbon group having 1 to 10, and preferably 1 to 8, carbon atoms, and examples thereof include the same alkenyl groups and monovalent hydrocarbon groups as exemplified for component (A) above. Specific examples include alkyl groups such as methyl, ethyl, propyl, butyl, pentyl, hexyl, cyclohexyl, and heptyl; alkenyl groups such as vinyl, allyl, propenyl, butenyl, pentenyl, hexenyl, cyclohexenyl, and heptenyl; 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 and vinyl groups being particularly preferred.

[0034] The content of silicon-bonded alkenyl groups in component (B) is preferably 0 to 10 mol %, and more preferably 2 to 8 mol %, based on the total number of silicon-bonded substituents.

[0035] The organopolysiloxane resin of component (B) is formed by the addition of R １ SiO ３／２ Units and SiO ４／２ The total amount of siloxane units in the organopolysiloxane resin of component (B) is preferably 20 to 75 mol %, and more preferably 30 to 65 mol %. A content within this range is preferred, as it provides sufficient flame retardancy improvement.

[0036] As described above, the organopolysiloxane resin of component (B) contains R １ ３ SiO １／２ Units and / or R１ ２ SiO ２／２ The total content of these units in the organopolysiloxane resin of component (B) is preferably 0 to 70 mol %, and more preferably 0 to 50 mol %.

[0037] Furthermore, the polystyrene-equivalent weight-average molecular weight of the organopolysiloxane resin of component (B), as determined by GPC (gel permeation chromatography) analysis using tetrahydrofuran (THF) as the developing solvent, is preferably in the range of 2,000 to 50,000, and particularly preferably 4,000 to 20,000. A weight-average molecular weight within the range of 2,000 to 50,000 provides sufficient flame retardancy improvement and results in a viscosity of an addition-curable liquid silicone rubber composition for air bags that is easy to coat. Note that this weight-average molecular weight is a value determined by GPC analysis under the same conditions as those used to determine the degree of polymerization of component (A) above.

[0038] Specific examples of the organopolysiloxane resin of component (B) include those represented by the formula: R' ３ SiO １／２ and a siloxane unit represented by the formula: R' ２ R″SiO １／２ and a siloxane unit represented by the formula: R' ２ SiO ２／２ and a siloxane unit represented by the formula: SiO ４／２ and an organosiloxane copolymer comprising a siloxane unit represented by the formula: R' ３ SiO １／２ and a siloxane unit represented by the formula: R' ２ R″SiO １／２ and a siloxane unit represented by the formula: SiO ４／２ and an organosiloxane copolymer comprising a siloxane unit represented by the formula: R' ２ R″SiO １／２ and a siloxane unit represented by the formula: R' ２ SiO ２／２ and a siloxane unit represented by the formula: SiO ４／２ and an organosiloxane copolymer having a siloxane unit represented by the formula: R'R"SiO ２／２ and a siloxane unit represented by the formula: R'SiO３／２ or a siloxane unit represented by the formula: R″SiO ３／２ and a mixture of two or more of these organopolysiloxanes.

[0039] R' in the above formula is independently a group selected from an alkyl group having 1 to 10 carbon atoms, preferably 1 to 8 carbon atoms, an aryl group having 6 to 10 carbon atoms, preferably 1 to 8 carbon atoms, and an aralkyl group having 7 to 10 carbon atoms, preferably 7 or 8 carbon atoms. 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 halogenated alkyl groups such as chloromethyl, 3-chloropropyl, and 3,3,3-trifluoropropyl, with methyl being particularly preferred. R" in the above formula is an alkenyl group having 2 to 10 carbon atoms, preferably 2 to 8 carbon atoms. Examples of such groups include vinyl, allyl, butenyl, pentenyl, hexenyl, and heptenyl, with vinyl being particularly preferred.

[0040] The blending amount of component (B) is 5 to 100 parts by mass, preferably 8 to 90 parts by mass, and particularly preferably 10 to 80 parts by mass, per 100 parts by mass of the organopolysiloxane of component (A). A blending amount within the range of 5 to 100 parts by mass provides sufficient flame retardancy improvement and is excellent in cost effectiveness.

[0041] The three-dimensional network organopolysiloxane resin of component (B) can use either a single material or a combination of two or more different materials.

[0042] [Component (C)] Component (C) is an organohydrogenpolysiloxane having two or more hydrogen atoms bonded to silicon atoms (hydrosilyl groups) per molecule, and acts as a crosslinking agent for the composition.

[0043] The molecular structure of the organohydrogenpolysiloxane of component (C) may be linear, cyclic, branched, or three-dimensional network. In this case, those that are liquid at 25°C and have 2 to 300 silicon atoms (or a degree of polymerization) per molecule, particularly 4 to 200 silicon atoms, are preferably used. The number of hydrosilyl groups per molecule is two or more, preferably 2 to 200, more preferably 2 to 150, and even more preferably 2 to 100. The hydrosilyl groups may be located at the molecular chain terminals, in side chains (in the middle of the molecular chain), or both.

[0044] Examples of the substituent bonded to the silicon atom in component (C) include monovalent substituted or unsubstituted hydrocarbon groups typically having 1 to 12 carbon atoms, and preferably 1 to 10 carbon atoms. Specific examples of monovalent hydrocarbon 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 and phenyl groups being particularly preferred.

[0045] Examples of such organohydrogenpolysiloxanes include 1,1,3,3-tetramethyldisiloxane, 1,3,5,7-tetramethylcyclotetrasiloxane, methylhydrogencyclopolysiloxane, methylhydrogensiloxane-dimethylsiloxane cyclic copolymer, tris(dimethylhydrogensiloxy)methylsilane, tris(dimethylhydrogensiloxy)phenylsilane, methylhydrogenpolysiloxane blocked at both ends with trimethylsiloxy groups, dimethylsiloxane-methylhydrogensiloxane copolymer blocked at both ends with trimethylsiloxy groups, and methylhydrogenpolysiloxane blocked at both ends with dimethylsiloxy groups. Hydrogensiloxy group-blocked dimethylpolysiloxane, dimethylsiloxane-methylhydrogensiloxane copolymer with both ends blocked by dimethylhydrogensiloxy groups, methylhydrogensiloxane-diphenylsiloxane copolymer with both ends blocked by trimethylsiloxy groups, methylhydrogensiloxane-diphenylsiloxane-dimethylsiloxane copolymer with both ends blocked by trimethylsiloxy groups, cyclic methylhydrogenpolysiloxane, cyclic methylhydrogensiloxane-dimethylsiloxane copolymer, cyclic methylhydrogensiloxane-diphenylsiloxane-dimethylsiloxane copolymer, (CH ３ ) ２ HSiO １／２ Units and SiO ４／２ a copolymer consisting of (CH ３ ) ２ HSiO １／２ Units and SiO ４／２ Units and (C ６ H ５ ) SiO ３／２ and copolymers consisting of units, and the above-mentioned exemplary compounds in which some or all of the methyl groups have been substituted with other alkyl groups such as ethyl groups or propyl groups, or aryl groups such as phenyl groups. Specific examples of such organohydrogenpolysiloxanes include compounds of the following structural formula:

[0046] (In the formula, e is an integer of 2 to 200, and f, g, and h are each an integer of 0 to 200.)

[0047] The organohydrogenpolysiloxane preferably has a viscosity at 25°C of 0.5 to 10,000 mPa·s, and more preferably 1 to 300 mPa·s.

[0048] The amount of component (C) to be blended is an amount such that the total number of hydrosilyl groups contained in the composition of the present invention is 1 to 10 moles, preferably 1.2 to 9 moles (or groups), and more preferably 1.5 to 8 moles (or groups), per mole of silicon-bonded alkenyl groups contained in the composition of the present invention. If the composition containing component (C) contains less than 1 mole of hydrosilyl groups per mole of silicon-bonded alkenyl groups contained in components (A) and (B), the addition-curable liquid silicone rubber composition for air bags will not cure sufficiently, and if this number exceeds 10 moles, the heat resistance of the cured silicone rubber obtained from the addition-curable liquid silicone rubber composition for air bags may be extremely poor.

[0049] The organohydrogenpolysiloxane of component (C) may use either a single compound, or a combination of two or more different compounds.

[0050] [Component (D)] Component (D) has a BET specific surface area of ​​50 m ２ / g or more acts as a reinforcing filler. In other words, it imparts strength to the cured silicone rubber obtained from the addition-curable liquid silicone rubber composition for airbags according to the present invention, and by using silica fine powder as a reinforcing filler, it becomes possible to form a coating film that satisfies the strength required for the present invention. Such silica fine powder has a specific surface area of ​​50 m2 as measured by the BET method. ２ / g or more, preferably 50 to 400m ２ / g, more preferably 100 to 300 m ２ / g. The specific surface area can be 50 m ２ If the viscosity is less than 1 / g, it is not possible to impart sufficient mechanical strength properties for use as a coating agent for an air bag.

[0051] Such silica fine powder may be any known type that has been conventionally used as a reinforcing filler for cured silicone rubber, provided that its specific surface area falls within the above-mentioned range, such as fumed silica and precipitated silica (wet silica).

[0052] The silica fine powder may be one whose surface has been hydrophobized with a surface treatment agent such as a (usually hydrolyzable) organosilicon compound, for example, chlorosilane, alkoxysilane, or organosilazane. In this case, the silica fine powder may be one whose surface has been directly hydrophobized in powder form with a surface treatment agent. Alternatively, the silica fine powder may be one whose surface has been hydrophobized by adding a surface treatment agent when kneading with silicone oil (for example, the oily organopolysiloxane containing alkenyl groups, component (A)).

[0053] The surface treatment of component (D) can be carried out by known techniques. For example, the untreated silica fine powder and the surface treatment agent can be placed in a mechanical kneader or fluidized bed apparatus sealed at atmospheric pressure, and kneaded at room temperature (25°C) or under heat treatment (heating) in the presence of an inert gas, if necessary. In some cases, water or a catalyst (such as a hydrolysis promoter) can be used to promote the surface treatment. After kneading, the mixture can be dried to produce a surface-treated silica fine powder. The amount of the surface treatment agent to be added may be equal to or greater than the amount calculated from the surface area covered by the surface treatment agent.

[0054] Specific examples of the surface treatment agent include silazanes such as hexamethyldisilazane, methyltrimethoxysilane, ethyltrimethoxysilane, propyltrimethoxysilane, butyltrimethoxysilane, dimethyldimethoxysilane, diethyldimethoxysilane, vinyltriethoxysilane, vinyltrimethoxysilane, trimethylmethoxysilane, triethylmethoxysilane, vinyltris(methoxyethoxy)silane, trimethylchlorosilane, dimethyldichlorosilane, divinyldimethoxysilane, and chloropropyltrimethoxysilane, silane coupling agents such as polymethylsiloxane, organohydrogenpolysiloxane, etc., and the hydrophobic silica fine powder can be surface-treated with these and used. As the surface treatment agent, silane coupling agents or silazanes are particularly preferred.

[0055] When the silica fine powder of component (D) has been directly surface-hydrophobized in advance in a powder state with a surface treatment agent containing an alkenyl group, the amount of hydrosilyl groups contained in the composition containing component (C) is preferably 1 to 10 moles (or groups), more preferably 1.2 to 8 moles (or groups), and even more preferably 1.5 to 6 moles (or groups), per 1 mole (or groups) of alkenyl groups bonded to silicon atoms contained in the composition containing the surface treatment agents of components (A), (B), and (D).

[0056] This is because if there are less than 1 mole of hydrosilyl groups per mole of alkenyl groups bonded to silicon atoms in the addition-curable liquid silicone rubber composition for air bags, the addition-curable liquid silicone rubber composition for air bags will not cure sufficiently and may not exhibit sufficient adhesive strength, whereas if there are more than 10 moles of hydrosilyl groups, the heat resistance of the cured silicone rubber obtained from the addition-curable liquid silicone rubber composition for air bags may be significantly reduced.

[0057] The blending amount of component (D) is 1 to 50 parts by mass, preferably 3 to 30 parts by mass, and more preferably 5 to 25 parts by mass, per 100 parts by mass of the organopolysiloxane of component (A). If the blending amount is less than 1 part by mass, a silicone rubber cured product with sufficient strength will not be obtained, while if the blending amount exceeds 50 parts by mass, the viscosity of the resulting addition-curable liquid silicone rubber composition for air bags will increase, reducing flowability and making the coating process more difficult.

[0058] The fine silica powder of component (D) may be used alone or in combination of two or more different types.

[0059] [Component (E)] The hydrosilylation catalyst of component (E) primarily promotes the addition reaction between silicon-bonded alkenyl groups in components (A) and (B) and hydrosilyl groups in component (C). This hydrosilylation catalyst 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; and platinum group metal compounds such as tetrakis(triphenylphosphine)palladium and chlorotris(triphenylphosphine)rhodium, with platinum group metal compounds being preferred.

[0060] The blending amount of component (E), calculated as the mass of the catalytic metal element relative to the total mass of components (A) to (D), is 1 to 500 ppm, preferably 5 to 100 ppm. A blending amount of less than 1 ppm is undesirable because it significantly slows the addition reaction or prevents the addition-curable liquid silicone rubber composition for air bags from curing, while a blending amount of more than 500 ppm may result in a decrease in the heat resistance of the cured silicone rubber.

[0061] The hydrosilylation reaction catalyst of component (E) may use either a single compound, or a combination of two or more different compounds.

[0062] [Component (F)] Component (F) is an organosilicon compound having an adhesion-imparting functional group, and is added to develop and improve the adhesion of the addition-curable liquid silicone rubber composition for airbags to the airbag fabric.

[0063] Any organosilicon compound having an adhesion-imparting functional group can be used as component (F), but it is preferable that the component (F) be an organosilicon compound having, in one molecule, one or more reactive silyl groups selected from an alkoxysilyl group, an alkenyl-containing silyl group, and a hydrosilyl group, and one or more reactive organic groups selected from an epoxy group, an isocyanate group, and a (meth)acrylic group.

[0064] The alkoxy group (alkoxysilyl group) bonded to the silicon atom preferably bonds to the silicon atom to form, for example, a trialkoxysilyl group such as a trimethoxysilyl group or a triethoxysilyl group, or an alkyldialkoxysilyl group such as a methyldimethoxysilyl group, an ethyldimethoxysilyl group, a methyldiethoxysilyl group or an ethyldiethoxysilyl group. The epoxy group preferably bonds to the silicon atom in the form of, for example, a glycidoxyalkyl group such as a glycidoxypropyl group, or an epoxy-containing cyclohexylalkyl group such as a 2,3-epoxycyclohexylethyl group or a 3,4-epoxycyclohexylethyl group.

[0065] Examples of the organosilicon compound of component (F) include epoxy group-containing silicon compounds such as γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, (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. Examples of suitable silane coupling agents include silane coupling agents (i.e., organoalkoxysilanes containing epoxy functional groups), (meth)acrylic group-containing silane coupling agents such as 3-acryloxypropyltrimethoxysilane and 3-methacryloxypropyltrimethoxysilane, and isocyanate group-containing silane coupling agents such as 3-isocyanatepropyltriethoxysilane and 3-isocyanatepropyltrimethoxysilane, and organosilicon compounds such as cyclic organopolysiloxanes containing epoxy groups represented by the following chemical formulas, and linear organopolysiloxanes containing epoxy groups; mixtures of two or more of these, and partial hydrolysis condensates of one or more of these.

[0066] The main ones are listed below as examples.

[0067] (In the formula, p is an integer of 1 to 40, q is an integer of 0 to 40, and r is an integer of 1 to 40, preferably an integer of 1 to 20.)

[0068] The blending amount of component (F) is 0.1 to 10 parts by mass, preferably 0.15 to 5 parts by mass, per 100 parts by mass of the organopolysiloxane of component (A). If the blending amount is less than 0.1 part by mass, the resulting addition-curable liquid silicone rubber composition for air bags may not exhibit sufficient adhesive strength. If the blending amount exceeds 10 parts by mass, the addition-curable liquid silicone rubber composition for air bags may become highly thixotropic, reducing fluidity and worsening coating workability.

[0069] When component (F) contains alkenyl groups and / or hydrosilyl groups, the amount is such that the total number of hydrosilyl groups contained in the composition containing components (C) and (F) is 1 to 10 moles (or groups), preferably 1.2 to 8 moles (or groups), and more preferably 1.5 to 6 moles (or groups), per 1 mole (or groups) of silicon-bonded alkenyl groups contained in the composition containing components (A), (B), (D), and (F).

[0070] This is because if there are less than 1 mole of hydrosilyl groups per mole of alkenyl groups bonded to silicon atoms in the addition-curable liquid silicone rubber composition for air bags, the addition-curable liquid silicone rubber composition for air bags will not cure sufficiently and may not exhibit sufficient adhesive strength, whereas if there are more than 10 moles of hydrosilyl groups, the heat resistance of the cured silicone rubber obtained from the addition-curable liquid silicone rubber composition for air bags may be extremely poor.

[0071] The component (F) may use one type alone, or two or more types in combination.

[0072] [Component (G)] Component (G) is expanded graphite powder, which acts as a flame retardancy improver. Expanded graphite powder refers to a material obtained by inserting a chemical such as sulfuric acid between the layers of graphite powder, such as flake graphite, and then vaporizing the chemical by heating to spread the spaces between the graphite layers, and then pulverizing the resulting material into a powder. Conventional pulverization methods can be used, including, for example, a method in which an expanded graphite sheet formed by dry molding is pulverized using a bead mill, jet mill, roll mill, ball mill, disk mill, or hammer mill. Furthermore, the graphite powder refers to charcoal or carbon black obtained by baking out impurities at ultra-high temperatures of 2,000 to 3,000°C in an air-tight environment to increase the crystallization rate, and is clearly different from carbon black.

[0073] The volume average particle size D50 of the expanded graphite powder as measured by a laser diffraction scattering method is preferably 0.1 to 50 μm, more preferably 0.5 to 40 μm, and even more preferably 1 to 30 μm. If the median size is 0.1 or less, the thixotropy of the composition may increase, resulting in poor coating workability, while if it is 50 μm or more, it may cause coating spots when coated on a base fabric.

[0074] The blending amount of component (G) is 0.1 to 1 part by mass, preferably 0.25 to 1 part by mass, per 100 parts by mass of the organopolysiloxane of component (A). If the blending amount is less than 0.1 part by mass, sufficient flame retardancy improvement effect may not be obtained. On the other hand, if the blending amount exceeds 1 part by mass, the black color of the addition-curable liquid silicone rubber composition for airbags becomes stronger, and the brightness of the silicone-coated base fabric decreases, which may make it difficult to detect defective products during the inspection process after the airbag base fabric is manufactured.

[0075] The component (G) may use one type alone, or two or more types in combination.

[0076] [Other Components] In addition to the components (A) through (G) described above, the addition-curable liquid silicone rubber composition for air bags according to the present invention can contain any other components depending on the purpose. Specific examples include the following. These other components may each be used alone, or two or more may be used in combination.

[0077] [Component (H)] Component (H) may further contain one or more condensation catalysts selected from an organic titanium compound, an organic zirconium compound, and an organic aluminum compound. Component (H) is preferably one or more selected from a titanium alkoxide complex, a titanium chelate complex, a zirconium alkoxide complex, and a zirconium chelate complex, which acts as a condensation catalyst for the adhesion-imparting functional group in component (F) to promote adhesion.

[0078] Specific examples of the component (H) include titanium alkoxide complexes such as titanium tetraisopropoxide, titanium tetra normal butoxide, and titanium tetra-2-ethylhexoxide; titanium chelate complexes such as titanium diisopropoxybis(acetylacetonate), titanium diisopropoxybis(ethylacetoacetate), and titanium tetraacetylacetonate; zirconium alkoxide complexes such as zirconium tetra normal propoxide and zirconium tetra normal butoxide; and zirconium chelate complexes such as zirconium tributoxymonoacetylacetonate, zirconium monobutoxyacetylacetonate bis(ethylacetoacetate), and zirconium tetraacetylacetonate.

[0079] Component (H), one or more condensation catalysts selected from organotitanium compounds, organozirconium compounds, and organoaluminum compounds, is an optional component that is blended as needed, and its blend amount is preferably 0.05 to 5 parts by mass, more preferably 0.1 to 5 parts by mass, and especially preferably 0.08 to 2 parts by mass, per 100 parts by mass of component (A). When the blend amount is within the range of 0.05 to 5 parts by mass, the cured product obtained from the addition-curable liquid silicone rubber composition for airbags will have excellent adhesion to airbag fabrics.

[0080] The component (H) may use one type alone, or two or more types in combination.

[0081] [Reaction Retardant] The reaction retardant is not particularly limited as long as it is a compound that has a cure-inhibiting effect on the hydrosilylation catalyst of component (E), and known reaction retarders 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-based compounds such as acetylene alcohols; compounds containing two or more alkenyl groups; hydroperoxy compounds; and maleic acid derivatives.

[0082] The degree of cure inhibition effect of a reaction retarder varies depending on the chemical structure of the reaction retarder, so it is preferable to adjust the amount of reaction retarder added to an optimum amount for each reaction retarder used. By adding an optimum amount of reaction retarder, the addition-curable liquid silicone rubber composition for air bags will have excellent long-term storage stability at room temperature and curability.

[0083] [Non-reinforcing filler] Examples of fillers other than the fine silica powder of component (D) and the expanded graphite powder of component (G) include crystalline silica (for example, a filler having a specific surface area of ​​50 m2 by the BET method). ２ / g or less quartz powder), organic resin hollow filler, polymethylsilsesquioxane fine particles (so-called silicone resin powder), fumed titanium dioxide, magnesium oxide, zinc oxide, aluminum hydroxide, magnesium carbonate, calcium carbonate, zinc carbonate, diatomaceous earth, talc, glass fiber, and other fillers; fillers obtained by subjecting these fillers to surface hydrophobic treatment with an organosilicon compound such as an organoalkoxysilane compound, an organochlorosilane compound, an organosilazane compound, or a low-molecular-weight siloxane compound; silicone rubber powder; and silicone resin powder.

[0084] [Other Components] In addition, for example, organopolysiloxanes containing one silicon-bonded hydrogen atom per molecule and no other functional groups, organopolysiloxanes containing one silicon-bonded alkenyl group per molecule and no other functional groups, non-functional organopolysiloxanes containing no silicon-bonded hydrogen atoms, no silicon-bonded alkenyl groups, and no other functional groups (so-called dimethylsilicone oil), organic solvents, creep-hardening inhibitors, plasticizers, thixotropy-imparting agents, pigments, dyes, anti-fungal agents, and the like may be blended.

[0085] <Preparation of addition-curable liquid silicone rubber composition for air bags> The addition-curable liquid silicone rubber composition for air bags can be prepared by uniformly mixing the above components (A) to (G), component (H), and any other components that may be added as needed.

[0086] The addition-curable liquid silicone rubber composition for air bags obtained in this manner is a liquid composition at 25°C, and preferably has a viscosity at 25°C of 1 to 500 Pa·s, more preferably 2 to 400 Pa·s, and even more preferably 5 to 300 Pa·s. If the viscosity is within the above range at 25°C, it is suitable for use because it is less likely to cause uneven coating or insufficient adhesion to the air bag fabric after curing when applied to the fabric.

[0087] <Airbag Fabric> Generally, known fabrics are used as the airbag fabric (substrate made of fiber fabric) on which the silicone rubber layer is formed. Specific examples include woven fabrics of various synthetic fibers, such as various polyamide fibers such as 6,6-nylon, 6-nylon, and aramid fiber, and various polyester fibers such as polyethylene terephthalate (PET) and polybutylene terephthalate (PBT).

[0088] <Airbag> The airbag of the present invention has a cured coating of the above-described addition-curable liquid silicone rubber composition for airbags on an airbag base fabric, and is characterized in that the L value of the cured coating surface measured using the L*a*b* color system is 60 or greater.

[0089] Because the airbag of the present invention uses expanded graphite powder (component (G)) as a flame retardancy improver, the addition-curable liquid silicone rubber composition for airbags has a weak black color, while the silicone-coated base fabric has a high brightness, making it easy to detect defective products during the inspection process after the airbag base fabric is manufactured.

[0090] In the airbag of the present invention, the L value of the silicone-coated surface of the silicone-coated base fabric was measured using a spectrophotometer CM-700d (manufactured by Konica Minolta, Inc.) The L value was measured using the L*a*b* color system.

[0091] <Method of manufacturing an airbag> The addition-curable liquid silicone rubber composition for airbags can be applied to one or both sides, particularly just one side, of an airbag fabric (a substrate made of fiber fabric), and then heated and cured in a drying oven or the like to form a silicone rubber layer (cured coating). Airbags can be manufactured using the silicone rubber-coated airbag fabric obtained in this way.

[0092] The addition-curable liquid silicone rubber composition for airbags can be coated onto the airbag fabric by any conventional method, but coating with a knife coater is preferred. The coating layer thickness (or surface coating amount) is typically 5 to 100 g / m ２ , preferably 8 to 90 g / m ２ , more preferably 10 to 80 g / m ２ It can be said that:

[0093] The addition-curable liquid silicone rubber composition for air bags can be cured by known curing methods under known curing conditions. Specifically, the composition can be cured by heating at 100 to 200°C for 1 to 30 minutes, for example.

[0094] When the airbag fabric (airbag silicone rubber-coated fabric) thus produced, having a silicone rubber layer on one or both sides, is processed into an airbag, it can be produced by bonding the outer peripheries of two pieces of the airbag silicone rubber-coated fabric together with an adhesive, with the silicone rubber-coated side facing inward, and then sewing the adhesive layer together. Alternatively, a predetermined coating amount of an addition-curable liquid silicone rubber composition for airbags can be coated on both outer sides of an airbag fabric previously produced by woven fabric, as described above, and then cured under predetermined curing conditions. While known adhesives can be used, a silicone adhesive known as a seam sealant is preferred in terms of adhesive strength and durability.

[0095] The present invention will be specifically described below with reference to Preparation Examples, Examples, and Comparative Examples, but the present invention is not limited to the following Examples. The viscosity, weight average molecular weight (weight average degree of polymerization), and median diameter shown below are values ​​determined under the above-mentioned conditions.

[0096] The following components were used as component (A): (A-1): A linear dimethylpolysiloxane whose molecular chain is terminally capped with vinyldimethylsiloxy groups and whose weight-average degree of polymerization is 750 and whose viscosity is 30,000 mPa·s; (A-2): A linear dimethylpolysiloxane whose molecular chain is terminally capped with vinyldimethylsiloxy groups and whose weight-average degree of polymerization is 450 and whose viscosity is 5,000 mPa·s; (A-3): A linear dimethylpolysiloxane whose molecular chain is terminally capped with vinyldimethylsiloxy groups and whose weight-average degree of polymerization is 200 and whose viscosity is 1,000 mPa·s.

[0097] The following component was used as component (B): (CH ３ ) ３ SiO １／２ Units and (CH ３ ) (CH ２ =CH)SiO ２／２ Units and SiO ４／２ A powdery three-dimensional network organopolysiloxane resin having a weight average molecular weight of 5,500, a Q unit content of 56 mol%, and an alkenyl group content of 6.7 mol% based on the total number of silicon-bonded substituents.

[0098] The following component was used as component (C): (C): A linear dimethylsiloxane-methylhydrogensiloxane copolymer (hydrosilyl group content: 0.0089 mol / g) with both molecular chain terminals capped with trimethylsiloxy groups, a weight-average degree of polymerization of 20, an average of 9 hydrosilyl groups per molecule, and a viscosity of 8 mPa s.

[0099] The following component was used as component (D): (D): Specific surface area of ​​300 m2 by BET method ２ / g of silica fine powder (product name: Aerosil 300, manufactured by Nippon Aerosil Co., Ltd.)

[0100] The following component was used as component (E): (E): A dimethylpolysiloxane solution containing 1% by mass of a chloroplatinic acid / 1,3-divinyltetramethyldisiloxane complex in terms of platinum atom content.

[0101] The following component was used as component (F): (F): γ-glycidoxypropyltrimethoxysilane

[0102] The following components were used as component (G): (G-1): Expanded graphite powder (trade name: CS-5, manufactured by Marutoyo Foundry Manufacturing Co., Ltd., median diameter: 7 μm) according to the present invention; (G-2): Scaly graphite powder (trade name: MT-4, manufactured by Marutoyo Foundry Manufacturing Co., Ltd., median diameter: 4 μm) not according to the present invention; (G-3): Carbon fiber (trade name: XN-500, manufactured by Nippon Graphite Fiber Co., Ltd., average length: 50 μm) not according to the present invention; (G-4): Diamond powder (trade name: BRM, manufactured by Besco Superbrasives, median diameter: 10 μm) not according to the present invention; (G-5): Carbon black (trade name: Denka Black, manufactured by Denka Co., Ltd., median diameter: 0.35 μm) not according to the present invention.

[0103] The following component was used as component (H): (H): Zirconium tetraacetylacetonate (trade name: ZC-162, manufactured by Matsumoto Fine Chemical Co., Ltd.)

[0104] The following reaction inhibitor was used: (Reaction inhibitor): 1-ethynylcyclohexanol

[0105] [Preparation Example 1] 60 parts by mass of base oil (A-1), 8 parts by mass of hexamethyldisilazane, 2 parts by mass of water, and 40 parts by mass of silica fine powder (D) were added to a kneader and mixed at room temperature for 1 hour. Thereafter, 8 parts by mass of hexamethyldisilazane was further added and mixed at room temperature for 1 hour. Next, the temperature was raised to 150 ° C., and mixing was continued for 2 hours. After this, 30 parts by mass of base oil (A-1) was added and mixed until uniform, to obtain a base compound.

[0106] Examples 1 to 5 and Comparative Examples 1 to 7 The components in the compounding ratios shown in Tables 1 and 2 were mixed in a mixer at room temperature for 30 minutes to prepare addition-curable liquid silicone rubber compositions for air bags.

[0107]

[0108]

[0109] <Method of preparing silicone rubber coated base fabric> Each of the silicone rubber coating compositions for airbags prepared in Tables 1 and 2 was applied at 20 g / m to a 210 denier PA66 base fabric. ２ The silicone rubber coating composition was then cured by placing it in a dryer at 200°C for 1 minute, thereby preparing a silicone rubber-coated base fabric.

[0110] <Flame Retardancy Test Method> Flame retardancy was evaluated using the method described in FMVSS-302 (Federal Motor Vehicle Safety Standard-302). Specifically, each of the silicone rubber-coated base fabrics prepared above was cut to a size of 10 cm wide x 35 cm long. Then, with the silicone rubber-coated surface facing up, the test piece was burned using the method described in FMVSS-302, and the burning distance and burning time until the flame was extinguished were measured. The burning rate was calculated from the burning distance and burning time. In this test, any of the following was evaluated as passing flame retardancy: (1) the test piece did not ignite or self-extinguished (SE) just before the A-marked line; (2) self-extinguished (SE) within a burning distance of 51 mm (and within 60 seconds); or (3) a burning rate of 102 mm / min or less. The test was performed with N=10, and if all passed, it was evaluated as "passed", and if even one failed, it was evaluated as "failed". The results are shown in Tables 1 and 2. In addition, the self-extinguishing rate (SE rate) was calculated using the following formula, and the results are shown in Tables 1 and 2. Note that a higher SE rate indicates better flame retardancy. SE rate (%) = [((1) number of test pieces that did not ignite or self-extinguished just before the A-marked line + (2) number of self-extinguished within a burning distance of 51 mm (and within 60 seconds)) / 10] x 100 ​

[0111] <Method for measuring L value using a colorimeter> The L value of the silicone-coated surface of the prepared silicone rubber-coated base fabric was measured using a spectroscopic L colorimeter CM-700d (manufactured by Konica Minolta, Inc.) The median value measured with N=3 is shown in Tables 1 and 2. The L value was measured using the L*a*b* color system.

[0112] As can be seen from Table 1, Examples 1 to 5, which used the addition-curable liquid silicone rubber composition for air bags of the present invention, achieved excellent results in the flame retardancy test. Furthermore, the L value, which indicates lightness, was high when measured with a colorimeter.

[0113] On the other hand, as can be seen from Table 2, Comparative Examples 1 to 7, which are powders mainly composed of carbon like expanded graphite, either had inferior flame retardancy compared to the Examples or had low L values, which indicate brightness as measured by a colorimeter.

[0114] In this way, the present invention increases the brightness (L value) of the cured coating surface of the airbag, and increases the brightness of the silicone-coated base fabric, making it easier to detect defective products during the inspection process after the airbag base fabric is manufactured.

[0115] This specification includes the following embodiments: [1] (A) 100 parts by mass of a linear organopolysiloxane having a degree of polymerization of 50 to 2,000 and containing two or more alkenyl groups bonded to silicon atoms in each molecule, (B) 5 to 100 parts by mass of a powdery three-dimensional network organopolysiloxane resin (provided that the organopolysiloxane resin does not contain hydrosilyl groups), (C) an organohydrogenpolysiloxane containing two or more hydrosilyl groups in each molecule, (D) an organohydrogenpolysiloxane having a BET specific surface area of ​​50 m ２1. An addition-curable liquid silicone rubber composition for air bags, comprising: (A) a silica fine powder having a molecular weight of 1 / 2 or more and a molecular weight of 1 / 2 or more; (B) a silica fine powder having a molecular weight of 1 / 2 or more and a molecular weight of 1 / 2 or more; (C) a hydrosilylation reaction catalyst having a molecular weight of 1 / 2 or more and a molecular weight of 1 / 2 or more; (D) a catalyst for hydrosilylation reaction having a molecular weight of 1 / 2 or more and a molecular weight of 1 / 2 or more; (E) a catalyst for hydrosilylation reaction having a molecular weight of 1 / 2 or more and a molecular weight of 1 / 2 or more; (F) an organosilicon compound having an adhesion-imparting functional group having a molecular weight of 0.1 to 10 parts by mass; and (G) an expanded graphite powder having a median diameter of 0.1 to 50 μm having a median diameter of 0.1 to 50 parts by mass; [2] The addition-curable liquid silicone rubber composition for airbags according to [1], further comprising, as component (H), 0.05 to 5 parts by mass of one or more condensation catalysts selected from organic titanium compounds, organic zirconium compounds, and organic aluminum compounds, per 100 parts by mass of component (A). [3] The addition-curable liquid silicone rubber composition for airbags according to [1] or [2], wherein component (F) is an organosilicon compound having, per molecule, one or more reactive silyl groups selected from alkoxysilyl groups, alkenyl-containing silyl groups, and hydrosilyl groups, and one or more reactive organic groups selected from epoxy groups, isocyanate groups, and (meth)acrylic groups. [4] A cured coating of the addition-curable liquid silicone rubber composition for airbags according to any one of [1] to [3] on an airbag base fabric, wherein the cured coating surface is L ＊ a ＊ b ＊ An airbag characterized in that the L value measured by a color spacer is 60 or more.

[0116] The present invention is not limited to the above-described embodiments. The above-described embodiments are merely examples, and anything that has substantially the same configuration as the technical idea described in the claims of the present invention and that exhibits similar effects is included within the technical scope of the present invention.

Claims

1. An addition-curable liquid silicone composition for airbags, comprising: (A) 100 parts by mass of a linear organopolysiloxane having a weight-average degree of polymerization of 50 to 2,000 and containing two or more alkenyl groups bonded to silicon atoms in each molecule; (B) 5 to 100 parts by mass of a powder-like three-dimensional network organopolysiloxane resin (provided that the organopolysiloxane resin does not contain hydrosilyl groups); (C) an organohydrogenpolysiloxane containing two or more hydrosilyl groups in each molecule; and (D) a BET specific surface area of ​​50 m. ２ 1. An addition-curable liquid silicone rubber composition for airbags comprising: (A) a silica fine powder having a molecular weight of 1000 to 2000; (B) a silica fine powder having a molecular weight of 1000 to 2000; and (C) a silica fine powder having a molecular weight of 1000 to 2000; and (D) a silica fine powder having a molecular weight of 1000 to 2000; 2. The addition-curing liquid silicone rubber composition for airbags according to claim 1, further comprising, as component (H), 0.05 to 5 parts by mass of one or more condensation catalysts selected from organic titanium compounds, organic zirconium compounds, and organic aluminum compounds, per 100 parts by mass of component (A).

3. An addition-curing liquid silicone rubber composition for airbags as described in claim 1, characterized in that the (F) component is an organosilicon compound having in one molecule one or more reactive silyl groups selected from an alkoxysilyl group, an alkenyl-containing silyl group, and a hydrosilyl group, and one or more reactive organic groups selected from an epoxy group, an isocyanate group, and a (meth)acrylic group.

4. A cured coating of the addition-curing liquid silicone rubber composition for airbags according to any one of claims 1 to 3 is provided on an airbag base fabric, and the cured coating surface is provided on the L ＊ a ＊ b ＊ An airbag having an L value of 60 or more as measured by a color spacer.

Images