Addition-curing liquid silicone rubber composition for airbags and airbags

Abstract

To provide an addition reaction curing type liquid silicone rubber composition for an air bag excellent in low combustion rate property and generating no color shading when coating a base cloth for an air bag and curing, and an air bag.SOLUTION: An addition reaction curing type liquid silicone rubber composition for an air bag includes; (A) an organopolysiloxane having two or more alkenyl groups bonded to (a) silicon atom(s) in a molecule, and having a polymerization degree of 50-2,000; (B) an organohydrogenpolysiloxane having two or more hydrogen atoms (hydrosilyl group) bonded to (a) silicon atom(s) in a molecule; (C) a silica fine powder having a specific surface area by a BET method of 50 m2 / g or more; (D) a catalyst for hydrosilylation reaction; (E) an organosilicon compound having an adhesion-promoting functional group;and (F) a carboxylic acid metal salt.SELECTED DRAWING: None

Description

[Technical Field]

[0001] This invention relates to an addition-curing liquid silicone rubber composition for airbags and to an airbag. [Background technology]

[0002] Conventionally, silicone rubber compositions for airbags have been proposed with the aim of forming a rubber coating on the fiber surface. Airbags having a silicone rubber coating are suitable for use as airbags in automobiles and the like because they have excellent internal pressure retention and low combustion speed.

[0003] As such an addition-curing liquid silicone rubber composition for airbags, a method is known in which a resin-like polysiloxane is included, and the siloxane component is pre-mixed with silica, a surface treatment agent, and water to produce the addition-curing liquid silicone rubber composition for airbags (Patent Document 1). By coating the fiber surface with this composition, an airbag base fabric with excellent low combustion rate can be obtained. Furthermore, an addition-curing liquid silicone rubber composition for airbags is disclosed in which an organohydrogen polysiloxane containing T units or Q units is used as a crosslinking agent (Patent Document 2). The coated base fabric coated with this composition is characterized by its excellent strength. In addition, an addition-curing liquid silicone rubber composition for airbags is disclosed in which a silicone resin consisting of M, D, and Q units, with a crosslinkable functional group contained only in the D units, is blended as a flame retardant (Patent Document 3). The airbag coated with this composition is characterized by its excellent low combustion rate.

[0004] On the one hand, in recent years, in order to save space and reduce weight, the amount of silicone rubber composition applied has been decreasing, and the development of a silicone rubber composition for airbags with the same flame retardancy as the conventional one even with a low application amount is desired. As a method for improving flame retardancy, it is conceivable to blend a flame retardant. For example, a composition in which iron(III) oxide monohydrate or α-iron(III) oxide is blended as a flame retardant in a silicone rubber composition (Patent Document 4), a composition in which aluminum hydroxide is blended (Patent Document 5), a composition in which phosphazene is blended (Patent Document 6), etc. are disclosed. However, when a solid flame retardant is blended in a silicone rubber composition, the flame retardant may settle due to the density difference. Further, in recent low-application-amount silicone-coated airbag base fabrics, since the silicone rubber layer is thin, a part of the solid flame retardant with a large particle size may be exposed on the surface of the silicone rubber layer, and sufficient airtightness may not be ensured. Furthermore, since the solid flame retardant is not compatible with the silicone rubber composition, it is not uniformly dispersed in the silicone layer. For this reason, coating unevenness may occur during coating, or the base fabric characteristics such as the flame retardancy and tensile strength of the obtained silicone-coated base fabric may vary depending on the sampling position of the sample.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Patent Document 6

Summary of the Invention

Problems to be Solved by the Invention

[0006] The present invention has been made in view of the above circumstances, and an object thereof is to provide an addition-curable liquid silicone rubber composition for an airbag, which has excellent low combustion rate properties and does not cause color unevenness when coated on a base fabric for an airbag and cured.

Means for Solving the Problems

[0007] In order to solve the above problems, the present invention provides an addition-curable liquid silicone rubber composition for an airbag, comprising: (A) An organopolysiloxane having alkenyl groups bonded to two or more silicon atoms in one molecule and a degree of polymerization of 50 to 2,000: 100 parts by mass, (B) An organohydrogenpolysiloxane having hydrogen atoms (hydrosilyl groups) bonded to two or more silicon atoms in one molecule: an amount such that the hydrosilyl groups contained in the composition are 1 to 10 moles per mole of the total alkenyl groups bonded to the silicon atoms contained in the composition, (C) Silica fine powder having a BET specific surface area of 50 m ,

[0009] / g or more: 1 to 50 parts by mass, (D) A catalyst for hydrosilylation reaction: 1 to 500 ppm in terms of the mass of the catalyst metal element with respect to the mass of the component (A), (E) An organosilicon compound having an adhesion-imparting functional group: 0.1 to 10 parts by mass, (F) A metal carboxylate: 100 to 5,000 ppm in terms of the mass of the central metal with respect to the mass of the component (A) An addition-curable liquid silicone rubber composition for an airbag containing the above components is provided. <00001​​​​​Furthermore, in the present invention, it is preferable that component (E) is an organosilicon compound having one or more reactive silyl groups selected from alkoxysilyl groups, alkenyl group-containing silyl groups, and hydrosilyl groups, and one or more reactive organic groups selected from epoxy groups, isocyanate groups, and (meth)acrylic groups in one molecule.

[0010] With such an addition-curing liquid silicone rubber composition for airbags, the silicone coated base fabric for airbags produced therefrom will have superior adhesion.

[0011] Furthermore, in the present invention, it is preferable that component (G) contains 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).

[0012] Such an addition-curing liquid silicone rubber composition for airbags will result in superior adhesion of the silicone rubber layer to the airbag base fabric.

[0013] Furthermore, in the present invention, it is preferable that the carboxylic acid metal salt of component (F) is a metal salt of a carboxylic acid having 6 or more carbon atoms.

[0014] Such metal carboxylate salts have improved compatibility with silicone rubber compositions, allowing for easy dispersion. Furthermore, an addition-curing liquid silicone rubber composition for airbags made from such a composition exhibits superior flame retardancy in the resulting silicone coating base fabric.

[0015] Furthermore, in the present invention, it is preferable that the central metal ion of the carboxylate metal salt of component (F) is a trivalent iron ion.

[0016] Such metal carboxylate salts are readily available at low cost, and if such an addition-curing liquid silicone rubber composition for airbags is used, the resulting silicone-coated base fabric for airbags will have superior flame retardancy.

[0017] Furthermore, in the present invention, it is preferable that the (H) component further contains 0.1 to 100 parts by mass of a powdered three-dimensional network organopolysiloxane resin (provided that the organopolysiloxane resin does not contain hydrogen atoms bonded to silicon atoms) per 100 parts by mass of the (A) component.

[0018] With such an addition-curing liquid silicone rubber composition for airbags, the silicone coated base fabric for airbags produced from it will have superior flame retardancy.

[0019] Furthermore, the present invention provides an airbag having a cured coating of the above-described addition-curing liquid silicone rubber composition for airbags on a base fabric for airbags.

[0020] Such airbags offer excellent flame retardancy and prevent color unevenness. [Effects of the Invention]

[0021] As described above, the present invention provides an addition-curing type liquid silicone rubber composition for airbags that is excellent in flame retardancy and does not produce color unevenness when coated onto an airbag base fabric and cured, as well as an airbag. [Modes for carrying out the invention]

[0022] As described above, there was a need for the development of an addition-curing liquid silicone rubber composition for airbags and an airbag that exhibits excellent flame retardancy when coated onto an airbag base fabric and cured.

[0023] As a result of diligent research into the above-mentioned problems, the present inventors have discovered that an addition-curing liquid silicone rubber composition for airbags containing a metal carboxylate salt exhibits excellent flame retardancy and prevents color unevenness when coated onto an airbag base fabric and cured, thus completing the present invention.

[0024] In other words, the present invention relates to an addition-curing type liquid silicone rubber composition for airbags, (A) Organopolysiloxane having alkenyl groups bonded to two or more silicon atoms in one molecule and a degree of polymerization of 50 to 2,000: 100 parts by mass, (B) Organohydrogenpolysiloxane having two or more hydrogen atoms (hydrosilyl groups) bonded to silicon atoms in one molecule: The amount of hydrosilyl groups contained in the composition is 1 to 10 moles per mole of the total amount of alkenyl groups bonded to silicon atoms contained in the composition. (C) BET method specific surface area is 50m 2 Silica fine powder with a content of 1 to 50 parts by mass, (D) Catalyst for hydrosilylation reaction: 1 to 500 ppm of catalyst metal element relative to the mass of component (A), (E) Organosilicon compound having an adhesion-imparting functional group: 0.1 to 10 parts by mass, (F) Carboxylate metal salt: 100 to 5,000 ppm in terms of the mass of the central metal relative to the mass of component (A) above. This is an addition-curing liquid silicone rubber composition for airbags that contains [the specified ingredient].

[0025] The present invention will be described in detail below, but is not limited thereto. In this specification, viscosity is the value measured by a rotational viscometer at 25°C using the method described in JIS K 7117-1:1999. The weight-average degree of polymerization is the value obtained as the weight-average molecular weight (weight-average degree of polymerization) in polystyrene terms by GPC (gel permeation chromatography) analysis using tetrahydrofuran (THF) as the developing solvent, measured under the following conditions. [Measurement conditions] Developing solvent: tetrahydrofuran Flow rate: 0.35mL / min Detector: Differential refractive index detector (RI) Column: TSK Guardcolumn SuperH-L TSKgel SuperH4000(6.0mmI.D.×15cm×1) TSKgel SuperH3000(6.0mmI.D.×15cm×1) TSKgel SuperH2000(6.0mmI.D.×15cm×2) (All manufactured by Tosoh Corporation) Column temperature: 40℃ Sample injection volume: 10 μL (0.5 wt% tetrahydrofuran solution)

[0026] <Addition-curing liquid silicone rubber composition for airbags> The addition-curing liquid silicone rubber composition for airbags of the present invention is (A) Organopolysiloxane having alkenyl groups bonded to two or more silicon atoms in one molecule and a degree of polymerization of 50 to 2,000: 100 parts by mass, (B) Organohydrogenpolysiloxane having two or more hydrogen atoms (hydrosilyl groups) bonded to silicon atoms in one molecule: The amount of hydrosilyl groups contained in the composition is 1 to 10 moles per mole of the total amount of alkenyl groups bonded to silicon atoms contained in the composition. (C) BET method specific surface area is 50m 2 Silica fine powder with a content of 1 to 50 parts by mass, (D) Catalyst for hydrosilylation reaction: 1 to 500 ppm of catalyst metal element relative to the mass of component (A), (E) Organosilicon compound having an adhesion-imparting functional group: 0.1 to 10 parts by mass, (F) Carboxylate metal salt: 100 to 5,000 ppm in terms of the mass of the central metal relative to the mass of component (A) above. It is preferable that the product contains the following and is liquid at room temperature (25°C). Each component will be described in detail below.

[0027] [(A) component] (A) The organopolysiloxane is an organopolysiloxane with a weight-average degree of polymerization of 50 to 2,000, containing two or more alkenyl groups bonded to silicon atoms in one molecule, that is, an organopolysiloxane having two or more alkenyl groups bonded to silicon atoms in one molecule and a degree of polymerization of 50 to 2,000, and is the base polymer (main component) of the addition-curing liquid silicone rubber composition for airbags according to the present invention.

[0028] The molecular structure of component (A) is preferably linear, with the main chain basically consisting of repeating diorganosiloxane units, and both ends of the molecular chain sealed with triorganosiloxy groups, forming a diorganopolysiloxane. Furthermore, the position of the silicon atom to which the alkenyl group is attached in the molecule of the linear organopolysiloxane of component (A) may 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 bifunctional diorganosiloxane unit located at the non-terminus of the molecular chain), or both. Particularly preferred as component (A) is a linear diorganopolysiloxane containing alkenyl groups attached to at least the silicon atoms at both ends of the molecular chain.

[0029] (A) Examples of alkenyl groups bonded to silicon atoms in component (A) include those typically having 2 to 8 carbon atoms, preferably 2 to 4 carbon atoms. Specific examples include vinyl groups, allyl groups, propenyl groups, butenyl groups, pentenyl groups, hexenyl groups, cyclohexenyl groups, heptenyl groups, etc., with vinyl groups being particularly preferred.

[0030] (A) The number of alkenyl groups bonded to the silicon atom in component (A) is two or more per molecule, preferably 2 to 100, and more preferably 2 to 50.

[0031] (A) Examples of monovalent hydrocarbon groups bonded to silicon atoms other than the alkenyl group include monovalent hydrocarbon groups having 1 to 12 carbon atoms, 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 groups; aryl groups such as phenyl, tolyl, xylyl, and naphthyl groups; aralkyl groups such as benzyl and phenethyl groups; and halogen-substituted alkyl groups such as chloromethyl, 3-chloropropyl, and 3,3,3-trifluoropropyl groups, with methyl groups being particularly preferred.

[0032] 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-curing liquid silicone rubber composition for airbags may be poor. If the weight-average degree of polymerization is greater than 2,000, the viscosity of the resulting addition-curing liquid silicone rubber composition for airbags may be high, resulting in poor coating workability.

[0033] The viscosity of component (A) 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 at 25°C. If the viscosity of component (A) is 50 mPa·s or higher, the mechanical properties of the resulting addition-curing liquid silicone rubber composition for airbags will be good, and if it is 200,000 mPa·s or lower, the viscosity of the resulting addition-curing liquid silicone rubber composition for airbags will not be high, and the coating workability will also be good.

[0034] Specific examples of organopolysiloxanes of component (A) include: dimethylsiloxane-methylvinylsiloxane copolymer with trimethylsiloxy groups sealed at both ends of the molecular chain, methylvinylpolysiloxane with trimethylsiloxy groups sealed at both ends of the molecular chain, dimethylsiloxane-methylvinylsiloxane-methylphenylsiloxane copolymer with trimethylsiloxy groups sealed at both ends of the molecular chain, dimethylpolysiloxane with dimethylvinylsiloxy groups sealed at both ends of the molecular chain, and dimethylsiloxane-methylvinylsiloxane copolymer with dimethylvinylsiloxy groups sealed at both ends of the molecular chain. Examples include nylsiloxane copolymers, dimethylsiloxane-methylvinylsiloxane-methylphenylsiloxane copolymers with dimethylvinylsiloxy groups sealed at both ends of the molecular chain, dimethylpolysiloxane with divinylmethylsiloxy groups sealed at both ends of the molecular chain, dimethylsiloxane-methylvinylsiloxane copolymers with divinylmethylsiloxy groups sealed at both ends of the molecular chain, dimethylpolysiloxane with trivinylsiloxy groups sealed at both ends of the molecular chain, dimethylsiloxane-methylvinylsiloxane copolymers with trivinylsiloxy groups sealed at both ends of the molecular chain, and mixtures of two or more organopolysiloxanes thereof.

[0035] (A) The organopolysiloxane may be used alone or in combination of two or more types.

[0036] [(B) Component] Component (B) is an organohydrogenpolysiloxane having two or more hydrogen atoms (hydrosilyl groups) bonded to silicon atoms in one molecule, and acts as a crosslinking agent for this composition.

[0037] The molecular structure of component (B), the organohydrogenpolysiloxane, may be linear, cyclic, branched, or three-dimensional network structure. In this case, a molecule with 2 to 300 silicon atoms (or degree of polymerization), particularly 4 to 200 atoms, that is liquid at 25°C is preferably used. The number of hydrosilyl groups contained in one molecule is 2 or more, preferably 2 to 200, more preferably 2 to 150, and even more preferably 2 to 100. Note that the hydrosilyl groups may be located at the end of the molecular chain, in the side chain (middle of the molecular chain), or both.

[0038] Substituents bonded to the silicon atom of component (B) include, for example, monovalent hydrocarbon groups having 1 to 12 carbon atoms, 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 groups; aryl groups such as phenyl, tolyl, xylyl, and naphthyl groups; aralkyl groups such as benzyl and phenethyl groups; and halogen-substituted alkyl groups such as chloromethyl, 3-chloropropyl, and 3,3,3-trifluoropropyl groups. In particular, methyl or phenyl groups are preferred.

[0039] 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 with trimethylsiloxy groups sealed at both ends, dimethylsiloxane-methylhydrogensiloxane copolymer with trimethylsiloxy groups sealed at both ends, and dimethylhydrogen methylpolysiloxane with methylhydrogensiloxane at both ends, methylsiloxane-methylhydrogensiloxane copolymer, methylhydrogensiloxane-diphenylsiloxane copolymer with trimethylsiloxane at both ends, methylhydrogensiloxane-diphenylsiloxane-dimethylsiloxane copolymer with trimethylsiloxane at both ends, cyclic methylhydrogenpolysiloxane, cyclic methylhydrogensiloxane-dimethylsiloxane copolymer, cyclic methylhydrogensiloxane-diphenylsiloxane-dimethylsiloxane copolymer, (CH3)2HSiO 1 / 2 Units and SiO 4 / 2 A copolymer consisting of units, (CH3)2HSiO 1 / 2 Units and SiO 4 / 2 Units and (C6H5)SiO 3 / 2 Examples include copolymers consisting of units, and in each of the above example compounds, some or all of the methyl groups are substituted with other alkyl groups such as ethyl groups and propyl groups, or aryl groups such as phenyl groups. Specifically, examples of such organohydrogenpolysiloxanes include compounds with the following structural formulas.

[0040] [ka] (In the formula, e is an integer between 2 and 200, and f, g, and h are integers between 0 and 200.)

[0041] As this organohydrogenpolysiloxane, it is preferable that the viscosity at 25°C is 0.5 to 10,000 mPa·s, particularly 1 to 300 mPa·s.

[0042] (B) The compounding quantity of a component is the quantity which the hydrosilyl group contained in the composition containing a (B) component becomes 1-10 mol (or pieces) per 1 mol (or pieces) of the total of the alkenyl groups bonded to the silicon atom contained in the said composition containing an (A) component, Preferably it is the quantity which becomes 1.2-9 mol (or pieces), More preferably, it is the quantity which becomes 1.5-8 mol (or pieces). If the hydrosilyl group contained in the composition containing a (B) component is less than 1 mol with respect to 1 mol of the total of the alkenyl groups bonded to the silicon atom contained in the composition containing an (A) component, the addition-curing type liquid silicone rubber composition for an airbag will not be sufficiently cured, and if this exceeds 10 mol, the heat resistance of the silicone rubber cured product obtained from the addition-curing type liquid silicone rubber composition for an airbag may extremely deteriorate.

[0043] (B) The organohydrogenpolysiloxane of a component may be used individually by 1 type or may use 2 or more types together.

[0044] [(C) component] (C) The silica fine powder whose BET specific surface area is 50 m 2 / g or more acts as a reinforcing filler. That is, it imparts strength to the silicone rubber cured product obtained from the addition-curing type liquid silicone rubber composition concerning this invention, and by using silica fine powder as a reinforcing filler, it becomes possible to form the coating film which satisfies the intensity | strength required by this invention. Such silica fine powder has a specific surface area by the BET method of 50 m 2 / g or more, Preferably it is 50-400 m 2 / g, More preferably, it can be 100-300 m 2 / g. If the specific surface area is less than 50 m 2 / g, it is impossible to provide the mechanical strength characteristics which satisfy as an airbag coating agent.

[0045] Such silica fine powders may be known ones that have been conventionally used as reinforcing fillers for cured silicone rubber, provided that their specific surface area is within the above range. Examples include fumed silica and precipitated silica.

[0046] The silica fine powder used may be silica fine powder whose surface has been hydrophobized with a surface treatment agent such as a (usually hydrolyzable) organosilicon compound such as chlorosilane, alkoxysilane, or organosilazane. In this case, the silica fine powder may be used that has been directly surface-hydrophobized with a surface treatment agent in its powder form beforehand. Alternatively, the silica fine powder may be used that has been surface-hydrophobized by adding a surface treatment agent during kneading with silicone oil (for example, an organopolysiloxane containing the alkenyl group of component (A) above).

[0047] (C) Component can be treated by known techniques. For example, the untreated silica fine powder and the surface treatment agent can be placed in a sealed mechanical kneading apparatus or fluidized bed apparatus at atmospheric pressure and kneaded at room temperature (25°C) or under heat treatment (heating) in the presence of an inert gas as needed. In some cases, water or a catalyst (such as a hydrolysis accelerator) may be used to accelerate the surface treatment. After kneading, the surface-treated silica fine powder can be produced by drying. The amount of surface treatment agent to be added should be equal to or greater than the amount calculated from the coverage area of ​​the surface treatment agent.

[0048] Specific examples of surface treatment agents include silazanes such as hexamethyldisilazane, silane coupling agents such as methyltrimethoxysilane, ethyltrimethoxysilane, propyltrimethoxysilane, butyltrimethoxysilane, dimethyldimethoxysilane, diethyldimethoxysilane, vinyltriethoxysilane, vinyltrimethoxysilane, trimethylmethoxysilane, triethylmethoxysilane, vinyltris(methoxyethoxy)silane, trimethylchlorosilane, dimethyldichlorosilane, divinyldimethoxysilane, and chloropropyltrimethoxysilane, polymethylsiloxane, organohydrogenpolysiloxane, etc. Surface treatment with these agents can be used to produce hydrophobic silica fine powder. Silane coupling agents or silazanes are particularly preferred as surface treatment agents.

[0049] Furthermore, when using silica fine powder of component (C) that has been directly surface-hydrophobized in advance in powder form with a surface treatment agent containing alkenyl groups, the amount of hydrosilyl groups contained in the composition containing component (B) is preferably 1.2 to 8 moles (or groups), and more preferably 1.5 to 6 moles (or groups), for every 1 mole (or group) of alkenyl groups bonded to silicon atoms contained in the composition containing component (A) and the surface treatment agent of component (C).

[0050] This is because, if the amount of hydrosilyl groups is less than 1 mole per mole of alkenyl groups bonded to silicon atoms in the addition-curing liquid silicone rubber composition for airbags, the addition-curing liquid silicone rubber composition for airbags may not cure sufficiently and may not exhibit sufficient adhesive strength. On the other hand, if the amount of hydrosilyl groups exceeds 10 moles, the heat resistance of the cured silicone rubber product obtained from the addition-curing liquid silicone rubber composition for airbags may deteriorate drastically.

[0051] The amount of component (C) 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 organopolysiloxane (A). If the amount is less than 1 part by mass, a silicone rubber cured product with sufficient strength cannot be obtained, and if the amount exceeds 30 parts by mass, the viscosity of the resulting addition-curing liquid silicone rubber composition for airbags will increase, reducing fluidity and potentially worsening the coating process.

[0052] (C) The silica fine powder of component (C) may be used alone or in combination of two or more types.

[0053] [(D) component] The catalyst for the hydrosilylation reaction of component (D) mainly promotes the addition reaction between the alkenyl group bonded to the silicon atom in component (A) and the hydrosilyl group in component (B). This catalyst for the hydrosilylation reaction is not particularly limited and includes, for example, 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.

[0054] The amount of component (D) is 1 to 500 ppm, preferably 5 to 100 ppm, when calculated as the mass of the catalyst metal element relative to the mass of component (A). If the amount is less than 1 ppm, the addition reaction will be significantly slowed or the addition-curing liquid silicone rubber composition for airbags will not cure, which is undesirable. If the amount exceeds 500 ppm, the heat resistance of the cured silicone rubber product may decrease.

[0055] The catalyst for the hydrosilylation reaction of component (D) may be used alone or in combination of two or more types.

[0056] [(E) component] Component (E) is an organosilicon compound having an adhesion-imparting functional group, and is added to develop and improve the adhesion of the addition-curing liquid silicone rubber composition for airbags to the airbag base fabric.

[0057] Component (E) can be any organosilicon compound having an adhesion-imparting functional group, but it is preferable that it be an organosilicon compound having 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 in one molecule.

[0058] The alkoxy group (alkoxysilyl group) bonded to the silicon atom is preferably bonded to the silicon atom to form trialkoxysilyl groups such as trimethoxysilyl group and triethoxysilyl group; or alkyldialkoxysilyl groups such as methyldimethoxysilyl group, ethyldimethoxysilyl group, methyldiethoxysilyl group, and ethyldiethoxysilyl group. The epoxy group is preferably bonded to the silicon atom in the form of glycidoxyalkyl groups such as glycidoxypropyl group; or epoxy-containing cyclohexylalkyl groups such as 2,3-epoxycyclohexylethyl group and 3,4-epoxycyclohexylethyl group.

[0059] Examples of organosilicon compounds for component (E) include epoxy group-containing 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 include silane coupling agents (i.e., organoalkoxysilanes containing epoxy functional groups), or silane coupling agents containing (meth)acrylic groups such as 3-acryloxypropyltrimethoxysilane and 3-methacryloxypropyltrimethoxysilane, or silane coupling agents containing isocyanate groups such as 3-isocyanatetopropyltriethoxysilane and 3-isocyanatetopropyltrimethoxysilane, or organosilicon compounds such as cyclic organopolysiloxanes containing epoxy groups represented by the following chemical formula, or linear organopolysiloxanes containing epoxy groups, mixtures of two or more of these, or partial hydrolysis condensates of one or more of these.

[0060] The main examples are listed below. [ka] (In the formula, p is an integer between 1 and 40, q is an integer between 0 and 40, and r is an integer between 1 and 40, preferably between 1 and 20.)

[0061] The amount of component (E) is 0.1 to 10 parts by mass, preferably 0.15 to 5 parts by mass, per 100 parts by mass of organopolysiloxane (A). If the amount is less than 0.1 parts by mass, the resulting addition-curing liquid silicone rubber composition for airbags may not exhibit sufficient adhesive strength. If the amount exceeds 10 parts by mass, the thixotropy of the addition-curing liquid silicone rubber composition for airbags may increase, reducing fluidity and worsening coating workability.

[0062] Furthermore, if component (E) contains an alkenyl group and / or a hydrosilyl group, the amount of hydrosilyl groups contained in the composition containing components (B) and (E) is such that the total amount of hydrosilyl groups per mole (or individual) of alkenyl groups bonded to silicon atoms in the composition containing components (A), (C), and (E) is 1 to 10 moles (or individual), preferably 1.2 to 8 moles (or individual), and more preferably 1.5 to 6 moles (or individual).

[0063] This is because, if the amount of hydrosilyl groups is less than 1 mole per mole of alkenyl groups bonded to silicon atoms in the addition-curing liquid silicone rubber composition for airbags, the addition-curing liquid silicone rubber composition for airbags may not cure sufficiently and may not exhibit sufficient adhesive strength. On the other hand, if the amount of hydrosilyl groups exceeds 10 moles, the heat resistance of the cured silicone rubber product obtained from the addition-curing liquid silicone rubber composition for airbags may be extremely poor.

[0064] Component (E) may be used alone or in combination of two or more types.

[0065] [(F) component] Component (F) is a metal carboxylate salt and acts as a flame retardancy improver. The amount of component (F) is 100 to 5,000 ppm relative to the mass of component (A), calculated on a per-millimeter basis of the central metal, preferably 120 to 3,000 ppm, and more preferably 150 to 2,000 ppm. If the amount of component (F) is less than 100 ppm, a sufficient flame retardancy improvement effect may not be obtained, and if it is more than 5,000 ppm, the viscosity of the composition will increase, which may worsen the coating workability.

[0066] It is preferable that the carboxylic acid metal salt of component (F) is a metal salt of a carboxylic acid having 6 or more carbon atoms, including the carbon atoms of the carbonyl group. Since a metal salt of a carboxylic acid having 6 or more carbon atoms improves compatibility with the silicone rubber composition, it can be easily dispersed.

[0067] There are no particular restrictions on the central metal ion of the carboxylate metal salt of component (F) above. For example, lithium ions, potassium ions, calcium ions, titanium ions, iron ions, cobalt ions, nickel ions, copper ions, zinc ions, zirconium ions, tin ions, lead ions, etc., can be used, but trivalent iron ions are preferred. Carboxylate salts of trivalent iron ions are readily available at low cost.

[0068] (F)Specific examples of components include 2-ethylhexanoates such as lithium 2-ethylhexanoate (I), potassium 2-ethylhexanoate (I), bis(2-ethylhexanoate)calcium (II), tetrakis(2-ethylhexanoate)titanium (IV), bis(2-ethylhexanoate)manganese (II), tris(2-ethylhexanoate)iron (III), bis(2-ethylhexanoate)cobalt (II), bis(2-ethylhexanoate)nickel (II), bis(2-ethylhexanoate)zinc (II), bis(2-ethylhexanoate)zirconium (II), bis(2-ethylhexanoate)tin (II), and bis(2-ethylhexanoate)lead (II), as well as lithium stearate. Examples of stearates include iron(I), potassium stearate(I), calcium bis(stearate)(II), titanium tetrakis(stearate)(IV), manganese bis(stearate)(II), iron(III) tris(stearate), cobalt(stearate)(II), nickel(stearate)(II), zinc(stearate)(II), zirconium(stearate)(II), tin(stearate)(II), and lead(stearate)(II), but iron(III) tris(2-ethylhexanoate), cobalt(II) bis(2-ethylhexanoate), and potassium(I) 2-ethylhexanoate.

[0069] Component (F) may be used alone or in combination of two or more types.

[0070] [Other ingredients] In addition to the components (A) to (F) described above, the addition-curing liquid silicone rubber composition for airbags according to the present invention may contain other arbitrary components depending on the purpose. Specific examples include the following. Each of these other components may be used individually or in combination of two or more.

[0071] [(G) component] Furthermore, component (G) may contain one or more condensation catalysts selected from organic titanium compounds, organic zirconium compounds, and organic aluminum compounds. Preferably, component (G) is one or more selected from titanium alkoxide complexes, titanium chelate complexes, zirconium alkoxide complexes, and zirconium chelate complexes, and acts as a condensation catalyst for the adhesion-imparting functional group in component (E) to promote adhesion.

[0072] Specific examples of component (G) include, for example, titanium alkoxide complexes such as titanium tetraisopropoxide, titanium tetran-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 tetran-propoxide and zirconium tetran-butoxide; and zirconium chelate complexes such as zirconium triputoxymonoacetylacetonate, zirconium monobutoxyacetylacetonate bis(ethylacetoacetate), and zirconium tetraacetylacetonate.

[0073] One or more condensation catalysts selected from the organic titanium compounds, organic zirconium compounds, and organic aluminum compounds of component (G) are optional components that are added as needed, and the amount added is preferably 0.05 to 5 parts by mass, more preferably 0.1 to 2 parts by mass, per 100 parts by mass of component (A). When the amount added is in the range of 0.05 to 5 parts by mass, the cured product obtained from the addition-curing liquid silicone rubber composition for airbags has excellent adhesion to the base fabric for airbags.

[0074] Component (G) may be used alone or in combination of two or more.

[0075] [(H) component] Furthermore, the (H) component may contain a powdered three-dimensional network organopolysiloxane resin (provided that the organopolysiloxane resin does not contain hydrogen atoms bonded to silicon atoms). The (H) component is an organopolysiloxane resin having a three-dimensional network (resin-like) structure. Preferably, a trifunctional R 2 SiO 3 / 2 Unit and tetrafunctional SiO 4 / 2 It is basically composed of one or more branched siloxane units selected from the units, and monofunctional R as needed. 2 3SiO 1 / 2 Unit and / or bifunctional R 2 2SiO 2 / 2 The unit may be arbitrarily included and acts as a flame retardant enhancer. However, this organopolysiloxane resin may contain alkenyl groups bonded to silicon atoms in its molecule, but it does not contain hydrogen atoms (hydrosilyl groups) bonded to silicon atoms. Furthermore, this organopolysiloxane resin has a three-dimensional network (resin-like) structure and is in powder form at 25°C, thus clearly differentiating it from component (A), which basically has a linear structure and is liquid at 25°C.

[0076] R in the above formula 2 These are independently monovalent hydrocarbon groups having 1 to 10 carbon atoms, preferably 1 to 8 carbon atoms, and include the same alkenyl groups and monovalent hydrocarbon groups exemplified in component (A) above. Specifically, examples include alkenyl groups such as vinyl, allyl, propenyl, butenyl, pentenyl, hexenyl, cyclohexenyl, and heptenyl groups; alkyl groups such as methyl, ethyl, propyl, butyl, pentyl, hexyl, cyclohexyl, and heptyl groups; aryl groups such as phenyl, tolyl, xylyl, and naphthyl groups; aralkyl groups such as benzyl and phenethyl groups; and halogen-substituted alkyl groups such as chloromethyl, 3-chloropropyl, and 3,3,3-trifluoropropyl groups. In particular, methyl and vinyl groups are preferred.

[0077] The content of alkenyl groups bonded to silicon atoms in component (H) is preferably 0 to 10 mol%, and particularly preferably about 2 to 8 mol%, relative to the total substituents bonded to silicon atoms.

[0078] (H) The organopolysiloxane resin of component (H) is R 2 SiO 3 / 2 Units and / or SiO 4 / 2 It is preferable that the unit be present, and the total amount thereof is preferably 20 to 75 mol%, particularly 30 to 65 mol%, of the organopolysiloxane resin of component (H).

[0079] Here, the organopolysiloxane resin of component (H) contains, as mentioned above, R 2 3SiO 1 / 2 Units and / or R 2 2SiO 2 / 2 The unit may be included at will, but its total content is preferably 0 to 70 mol%, particularly 0 to 50 mol%, in the organopolysiloxane resin of component (H).

[0080] (H) R in organopolysiloxane resin 2 SiO 3 / 2 Units and / or SiO 4 / 2 A sufficient flame retardancy improvement effect can be obtained when the total amount of units is within the range of 20 to 75 mol%, which is preferable.

[0081] Furthermore, the weight-average molecular weight in polystyrene terms of the organopolysiloxane resin of component (H) in 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 in the range of 4,000 to 20,000. When the weight-average molecular weight is within the range of 2,000 to 50,000, a sufficient flame retardancy improvement effect is obtained, resulting in a viscosity for an addition-curing liquid silicone rubber composition for airbags with good coating workability. This weight-average molecular weight is the value obtained by GPC analysis under the same conditions as those used to determine the degree of polymerization of component (A) above.

[0082] A specific example of the organopolysiloxane resin of component (H) is given by formula: R'3SiO 1 / 2 The siloxane units and formula shown are: R'2R”SiO 1 / 2 The siloxane units and formula shown are: R'2SiO 2 / 2 Siloxane units and formula shown: SiO 4 / 2 An organosiloxane copolymer consisting of siloxane units represented by R'3SiO, formula: R'3SiO 1 / 2 The siloxane units and formula shown are: R'2R”SiO 1 / 2 Siloxane units and formula shown: SiO 4 / 2 An organosiloxane copolymer consisting of siloxane units represented by R'2R”SiO 1 / 2 The siloxane units and formula shown are: R'2SiO 2 / 2 Siloxane units and formula shown: SiO 4 / 2 An organosiloxane copolymer consisting of siloxane units represented by R'R”SiO 2 / 2 The siloxane units and formula shown are: R'SiO 3 / 2 The siloxane units or formula shown are R”SiO 3 / 2 Examples include organosiloxane copolymers consisting of siloxane units represented by and organopolysiloxanes, and mixtures consisting of two or more of these organopolysiloxanes.

[0083] In the above formula, R' is a monovalent hydrocarbon group having 1 to 10 carbon atoms, preferably 1 to 8 carbon atoms, which is either identical or different from an alkenyl group. Examples include alkyl groups such as methyl, ethyl, propyl, butyl, pentyl, hexyl, cyclohexyl, and heptyl groups; aryl groups such as phenyl, tolyl, xylyl, and naphthyl groups; aralkyl groups such as benzyl and phenethyl groups; and halogenated alkyl groups such as chloromethyl, 3-chloropropyl, and 3,3,3-trifluoropropyl groups, with methyl groups being particularly preferred. In addition, R'' in the above formula is an alkenyl group, examples of which include vinyl, allyl, butenyl, pentenyl, hexenyl, and heptenyl groups, with vinyl groups being particularly preferred.

[0084] The amount of component (H) is preferably 0.1 to 100 parts by mass, more preferably 2.5 to 90 parts by mass, and particularly preferably 5 to 80 parts by mass, relative to 100 parts by mass of organopolysiloxane (A). An amount within the range of 0.1 to 100 parts by mass provides a sufficient flame retardancy improvement effect and is cost-effective.

[0085] Furthermore, if component (H) contains an alkenyl group, the amount of hydrosilyl groups contained in the composition is 1 to 10 moles per mole of the total alkenyl groups bonded to silicon atoms in the composition. For example, component (H) is such that the amount of hydrosilyl groups contained in components (B) and (E) is 1 to 10 moles (or units) per mole of the total alkenyl groups bonded to silicon atoms in components (A), (C), (E), and (H) in the composition, preferably 1.2 to 8 moles (or units), and more preferably 1.5 to 6 moles (or units). If the total amount of hydrosilyl groups is less than 1 mole per mole of the total alkenyl groups bonded to silicon atoms in the composition, the addition-curing liquid silicone rubber composition for airbags may not cure sufficiently and may not exhibit sufficient adhesive strength. On the other hand, if the amount of hydrosilyl groups exceeds 10 moles, the heat resistance of the cured silicone rubber product obtained from the addition-curing liquid silicone rubber composition for airbags may be extremely poor.

[0086] Thus, in the present invention, each component is blended in such a way that the total number of moles of hydrosilyl groups relative to the total number of alkenyl groups bonded to silicon atoms in each component of the addition-curing liquid silicone rubber composition for airbags is 1 to 10 moles.

[0087] The three-dimensional network organopolysiloxane resin of component (H) can be used alone or in combination of two or more types.

[0088] • Reaction control agent The reaction control agent is not particularly limited as long as it is a compound that has a hardening inhibitory effect on the catalyst for the hydrosilylation reaction of component (D), and known compounds 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.

[0089] The degree of curing inhibition by reaction control agents varies depending on the chemical structure of the reaction control agent; therefore, it is preferable to adjust the amount of reaction control agent added to the optimal amount for each reaction control agent used. By adding the optimal amount of reaction control agent, the addition-curing liquid silicone rubber composition for airbags will have excellent long-term storage stability and curing properties at room temperature.

[0090] • Non-reinforcement filler (C) As a filler other than surface-treated silica fine powder, for example, crystalline silica (for example, with a specific surface area of ​​50 m² by the BET method) 2 Examples of fillers include: quartz powder (less than 1g / g), hollow organic resin fillers, polymethylsilsesquioxane fine particles (so-called silicone resin powder), fumed titanium dioxide, magnesium oxide, zinc oxide, iron oxide, aluminum hydroxide, magnesium carbonate, calcium carbonate, zinc carbonate, carbon black, diatomaceous earth, talc, kaolinite, glass fibers, etc.; fillers obtained by surface hydrophobizing these fillers with organosilicon compounds such as organoalkoxysilane compounds, organochlorosilane compounds, organosilazane compounds, and low molecular weight siloxane compounds; silicone rubber powder; and silicone resin powder.

[0091] Other ingredients In addition, for example, organopolysiloxanes containing one hydrogen atom bonded to a silicon atom per molecule and no other functional groups, organopolysiloxanes containing one alkenyl group bonded to a silicon atom per molecule and no other functional groups, non-functional organopolysiloxanes (so-called dimethyl silicone oil) that do not contain a hydrogen atom bonded to a silicon atom, an alkenyl group bonded to a silicon atom, or any other functional groups, organic solvents, creep hardening inhibitors, plasticizers, thixotropic agents, pigments, dyes, and antifungal agents can be incorporated.

[0092] <Preparation of addition-curing liquid silicone rubber composition for airbags> In addition to the components (A) to (F) above, component (G), component (H), and other components added as needed can be uniformly mixed to prepare an addition-curing liquid silicone rubber composition for airbags. The resulting addition-curing liquid silicone rubber composition for airbags is liquid at 25°C, and its viscosity at 25°C is preferably 1 to 500 Pa·s, more preferably 2 to 400 Pa·s, and even more preferably 5 to 300 Pa·s. Within this viscosity range at 25°C, the composition is suitable for application to the airbag base fabric because it is less likely to result in uneven coating or insufficient adhesion to the base fabric after curing.

[0093] <Base fabric for airbags> Generally, known materials are used as the base fabric (substrate made of fiber cloth) for airbags on which the silicone rubber layer is formed. Specific examples include woven fabrics of various synthetic fibers such as 6,6-nylon, 6-nylon, aramid fibers, polyethylene terephthalate (PET), and polybutylene terephthalate (PBT).

[0094] <Airbag> The airbag of the present invention has a cured coating of the above-mentioned addition-curing liquid silicone rubber composition for airbags on an airbag base fabric.

[0095] <Airbag manufacturing method> The above-mentioned addition-curing liquid silicone rubber composition for airbags can be applied to one or both sides, or especially only one side, of an airbag base fabric (a substrate made of fiber cloth), and then heated and cured in a drying oven or the like to form a silicone rubber layer (cured film). An airbag can then be manufactured using the silicone rubber coated base fabric obtained in this way.

[0096] Here, a conventional method can be used to coat the airbag base fabric with the addition-curing liquid silicone rubber composition for airbags, but coating by knife coater is preferred. The thickness of the coating layer (or surface coating amount) is usually 5 to 100 g / m². 2 Preferably 8-90 g / m² 2 More preferably 10-80 g / m² 2 It can be done this way.

[0097] The addition-curing liquid silicone rubber composition for airbags can be cured under known curing conditions by known curing methods. Specifically, for example, the composition can be cured by heating at 100 to 200°C for 1 to 30 minutes.

[0098] When processing an airbag base fabric (airbag silicone rubber coated base fabric) having a silicone rubber layer on one or both sides, manufactured in this manner, into an airbag, one method is to bond the outer edges of two of the above-mentioned airbag silicone rubber coated base fabrics together with an adhesive, with the silicone rubber coated side facing inward, and then sew the adhesive layer together. Alternatively, one may coat both outer surfaces of an airbag base fabric that has been pre-woven into a bag with an addition-curing liquid silicone rubber composition for airbags in a predetermined coating amount, as described above, and then cure it under predetermined curing conditions. While any known adhesive can be used here, a silicone-based adhesive called a seam sealant is preferred in terms of adhesive strength and adhesive durability. [Examples]

[0099] 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.

[0100] (A) The following components were used as components. (A-1): A linear dimethylpolysiloxane in which both ends of the molecular chain are sealed with vinyldimethylsiloxy groups, with a weight-average degree of polymerization of 700 and a viscosity of 30,000 mPa·s. (A-2): A linear dimethyl-vinylmethylpolysiloxane in which both ends of the molecular chain are sealed with trimethylsiloxy groups, the weight-average degree of polymerization is 200, the viscosity is 700 mPa·s, and the bifunctional diorganosiloxane units constituting the main chain contain 5 mol% vinylmethylsiloxane units and 95 mol% dimethylsiloxane units. (A-3): A linear dimethylpolysiloxane in which both ends of the molecular chain are sealed with vinyldimethylsiloxy groups, with a weight-average degree of polymerization of 200 and a viscosity of 1,000 mP·s. (A-4): A linear dimethylpolysiloxane in which both ends of the molecular chain are sealed with vinyldimethylsiloxy groups, with a weight-average degree of polymerization of 450 and a viscosity of 5,000 mP·s.

[0101] The following components were used as component (B): (B-1): A linear dimethylsiloxane-methylhydrogensiloxane copolymer in which both ends of the molecular chain are sealed with trimethylsiloxy groups, with a weight-average degree of polymerization of 64 and a viscosity of 45 mPa·s (hydrosilyl group content 0.011 mol / g). (B-2): A linear methylhydrogenpolysiloxane (hydrosilyl group content 0.017 mol / g) in which both ends of the molecular chain are sealed with trimethylsiloxy groups, with a weight-average degree of polymerization of 40 and a viscosity of 20 mPa·s.

[0102] The following components were used as component (C): (C): Specific surface area is 300m² using the BET method. 2 Silica fine powder (product name: Aerosil 300, manufactured by Nippon Aerosil Co., Ltd.) in a quantity of / g

[0103] The following components were used as component (D): (D): Dimethylpolysiloxane solution containing 1% by mass of chloroplatinic acid / 1,3-divinyltetramethyldisiloxane complex as the platinum atom content.

[0104] The following components were used as component (E): (E): γ-Glycidoxypropyltrimethoxysilane

[0105] The following components were used as component (F): (F-1): Iron(III) tris(2-ethylhexanoate), mineral spirit solution (product name: Nikka Octic Iron, iron content 6%, manufactured by Nippon Chemical Industrial Co., Ltd.) (F-2): Bis(2-ethylhexanoate)cobalt(II), mineral spirit solution (product name: Nikka Octic Cobalt, cobalt content 12%, manufactured by Nippon Chemical Industrial Co., Ltd.) (F-3): Potassium 2-ethylhexanoate (I) (Trade name: Nikka Octic Potassium, potassium content 10%, manufactured by Nippon Chemical Industrial Co., Ltd.)

[0106] The following components were used as component (G): (G): Zirconium tetraacetylacetonate (Trade name: ZC-162, manufactured by Matsumoto Fine Chemical Co., Ltd.)

[0107] The following components were used as the (H) component. (H):(CH3)3SiO 1 / 2 Units and (CH3)(CH2=CH)SiO 2 / 2 Units and SiO 4 / 2 A powdery, three-dimensional network organopolysiloxane resin consisting of units, with a weight-average molecular weight of 5,500, a Q unit content of 56 mol%, and an alkenyl group content of 6.7 mol% relative to the total number of substituents to which silicon atoms are bonded.

[0108] The following components were used as flame retardants. Iron(III) oxide (Product name: Toda Color 130ED, Toda Pigment Co., Ltd.)

[0109] The following components were used as reaction control agents. (Reaction control agent): 1-ethynylcyclohexanol

[0110] [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 (C) were placed in a kneader and mixed at room temperature for 1 hour. Then, 8 parts by mass of hexamethyldisilazane were added and mixed for another 1 hour at room temperature. After that, the temperature was raised to 150°C and mixed for a further 2 hours. After this, 25 parts by mass of base oil (A-1) and 5 parts by mass of base oil (A-2) were added and mixed until homogeneous to obtain a base compound.

[0111] [Examples 1-7, Comparative Examples 1-6] The components were mixed in the proportions shown in Tables 1 and 2 in a mixer at room temperature for 30 minutes to prepare an addition-curing liquid silicone rubber composition for airbags.

[0112] <Method for preparing silicone rubber coated base fabric> On a 470 denier PET base fabric, apply 20 g / m² of each silicone rubber coating composition for airbags prepared in Tables 1 and 2. 2 The material was knife-coated using a Mathis lab coater (product name: LTE-S) to achieve the desired result. Subsequently, the silicone rubber coating composition was cured in a 200°C dryer for 1 minute to prepare the silicone rubber coated base fabric.

[0113] <Method for evaluating color unevenness in silicone rubber coated base fabric> The coated surfaces (25cm x 25cm) of the silicone rubber coated base fabric prepared above were visually inspected. If no color unevenness was found, it was evaluated as "acceptable," and if color unevenness was found, it was evaluated as "unacceptable." The results are shown in Tables 1 and 2.

[0114] <Flame Retardancy Test Method> Flame retardancy was evaluated using the method described in FMVSS-302 (Federal Motor Vehicle Safety Standard-302). Specifically, each silicone rubber coated base fabric prepared earlier was cut to a size of 10 cm wide x 35 cm long. Then, with the silicone rubber coated side facing upwards, the burning distance and burning time until the flame extinguished were measured using the method described in FMVSS-302. The burning rate was calculated from this burning distance and burning time. In this process, a sample was evaluated as passing flame retardancy if it met any of the following criteria: (1) the test piece did not ignite or self-extinguished (SE) before the A mark, (2) self-extinguished (SE) within a burning distance of 51 mm (and within 60 seconds), or (3) the burning rate was 102 mm / min or less. Tests were conducted with N=10, and if all passed, it was evaluated as "pass," and if even one failed, it was evaluated as "fail." 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 also listed in Tables 1 and 2. Furthermore, a higher SE ratio is considered to indicate better flame retardancy. SE rate (%) = [((1) Number of test specimens that did not ignite or self-extinguished before mark A + (2) Number of specimens that self-extinguished within a burning distance of 51 mm (and within 60 seconds)) / 10] × 100

[0115] [Table 1]

[0116] [Table 2]

[0117] As can be seen from Table 1, Examples 1 to 7, which used the addition-curing liquid silicone rubber composition for airbags of the present invention, did not exhibit color unevenness during coating. Furthermore, they showed excellent results in flame retardancy tests.

[0118] On the other hand, as can be seen from Table 2, Comparative Examples 1 to 6, which did not use the addition-curing liquid silicone rubber composition for airbags of the present invention, showed inferior flame retardancy or color unevenness during coating compared to the examples.

[0119] This specification includes the following embodiments: [1]: Addition-curing liquid silicone rubber composition for airbags, (A) Organopolysiloxane having alkenyl groups bonded to two or more silicon atoms in one molecule and a degree of polymerization of 50 to 2,000: 100 parts by mass, (B) Organohydrogenpolysiloxane having two or more hydrogen atoms (hydrosilyl groups) bonded to silicon atoms in one molecule: The amount of hydrosilyl groups contained in the composition is 1 to 10 moles per mole of the total amount of alkenyl groups bonded to silicon atoms contained in the composition. (C) BET method specific surface area is 50m 2 Silica fine powder with a content of 1 to 50 parts by mass, (D) Catalyst for hydrosilylation reaction: 1 to 500 ppm of catalyst metal element relative to the mass of component (A), (E) Organosilicon compound having an adhesion-imparting functional group: 0.1 to 10 parts by mass, (F) Carboxylate metal salt: 100 to 5,000 ppm in terms of the mass of the central metal relative to the mass of component (A) above. An addition-curing liquid silicone rubber composition for airbags, characterized by containing [a specific substance]. [2]: The addition-curing liquid silicone rubber composition for airbags according to [1], characterized in that component (E) is an organosilicon compound having in one molecule one or more reactive silyl groups selected from alkoxysilyl groups, alkenyl group-containing silyl groups, and hydrosilyl groups, and one or more reactive organic groups selected from epoxy groups, isocyanate groups, and (meth)acrylic groups. [3]: The addition-curing liquid silicone rubber composition for airbags according to [1] or [2] above, further characterized in that it contains, as component (G), one or more condensation catalysts selected from organic titanium compounds, organic zirconium compounds, and organic aluminum compounds in an amount of 0.05 to 5 parts by mass per 100 parts by mass of component (A). [4]: An addition-curing liquid silicone rubber composition for airbags according to any one of [1] to [3] above, characterized in that the carboxylic acid metal salt of component (F) is a metal salt of a carboxylic acid having 6 or more carbon atoms. [5]: An addition-curing liquid silicone rubber composition for airbags according to any one of the above [1] to [4], characterized in that the central metal ion of the carboxylate metal salt of component (F) is a trivalent iron ion. [6]: The addition-curing liquid silicone rubber composition for airbags according to any one of [1] to [5] above, further comprising 0.1 to 100 parts by mass of powdered three-dimensional network organopolysiloxane resin (provided that the organopolysiloxane resin does not contain hydrogen atoms bonded to silicon atoms) as component (H) per 100 parts by mass of component (A). [7]: An airbag characterized by having a cured coating of any one of the airbag addition-curing liquid silicone rubber compositions for airbags described in [1] to [6] above on an airbag base fabric.

[0120] It should be noted that the present invention is not limited to the embodiments described above. The embodiments described above are illustrative, and any configuration that is substantially identical to the technical idea described in the claims of the present invention and achieves similar effects is included within the technical scope of the present invention.

Claims

1. An addition-curing liquid silicone rubber composition for airbags, (A) Organopolysiloxane having alkenyl groups bonded to two or more silicon atoms in one molecule and a degree of polymerization of 50 to 2,000: 100 parts by mass, (B) Organohydrogenpolysiloxane having two or more hydrogen atoms (hydrosilyl groups) bonded to silicon atoms in one molecule: The amount of hydrosilyl groups contained in the composition is 1 to 10 moles per mole of the total amount of alkenyl groups bonded to silicon atoms contained in the composition. (C) BET method specific surface area of ​​50 m ２ Silica fine powder of 1 to 50 parts by mass, with a content of 1 g or more. (D) Catalyst for hydrosilylation reaction: 1 to 500 ppm in mass of the catalyst metal element relative to the mass of component (A), (E) Organosilicon compound having an adhesion-imparting functional group: 0.1 to 10 parts by mass, (F) Carboxylate metal salt: 100 to 5,000 ppm in terms of the mass of the central metal relative to the mass of component (A) above. An addition-curing liquid silicone rubber composition for airbags, characterized by containing [a specific substance].

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

3. Furthermore, the addition-curing liquid silicone rubber composition for airbags according to claim 1 is characterized in that, as component (G), it contains 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).

4. The addition-curing liquid silicone rubber composition for airbags according to claim 1, characterized in that the carboxylic acid metal salt of component (F) is a metal salt of a carboxylic acid having 6 or more carbon atoms.

5. The addition-curing liquid silicone rubber composition for airbags according to claim 1, characterized in that the central metal ion of the carboxylate metal salt of component (F) is a trivalent iron ion.

6. The addition-curing liquid silicone rubber composition for airbags according to claim 1, further characterized in that it contains 0.1 to 100 parts by mass of powdered three-dimensional network organopolysiloxane resin (provided that the organopolysiloxane resin does not contain hydrogen atoms bonded to silicon atoms) as component (H) per 100 parts by mass of component (A).

7. An airbag characterized by having a cured coating of an addition-curing liquid silicone rubber composition for airbags described in any one of claims 1 to 6 on a base fabric for airbags.

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