Addition-curable liquid silicone rubber composition for airbag and airbag

Abstract

The present invention provides an addition-curable liquid silicone rubber composition for an airbag, which is characterized by containing: (A) an organopolysiloxane having two or more alkenyl groups bonded to a silicon atom in one molecule and having a degree of polymerization of 50-2,000; (B) an organohydrogenpolysiloxane having two or more hydrogen atoms (hydrosilyl) bonded to a silicon atom in one molecule; (C) fine silica powder having a BET specific surface area of 50 m2 / g or more; (D) a hydrosilylation reaction catalyst; (E) an organosilicon compound having an adhesion-imparting functional group; and (F) a carboxylic acid metal salt. As a result, it is possible to provide: an addition-curable liquid silicone rubber composition for an airbag, which has excellent flame retardancy when coated and cured on a base fabric for an airbag, and which does not cause color unevenness; and an airbag.

Description

Technical Field

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

[0002] Conventionally, a silicone rubber composition for an airbag has been proposed, the purpose of which is to form a rubber coating film on the surface of fibers. An airbag having a silicone rubber coating film is excellent in internal pressure retention and low burning rate properties, and thus is suitable for use as an airbag for an automobile or the like.

[0003] As such an addition-curable liquid silicone rubber composition for an airbag, a resinous polysiloxane is contained, and a method for producing an addition-curable liquid silicone rubber composition for an airbag by previously mixing a siloxane component with silica, a surface treatment agent, and water is also known (Patent Document 1). By covering the surface of fibers with this composition, a base fabric for an airbag excellent in low burning rate properties can be obtained. Further, an addition-curable liquid silicone rubber composition for an airbag containing an organohydrogenpolysiloxane containing a T unit or a Q unit as a crosslinking agent has been disclosed (Patent Document 2). The coated base fabric coated with this composition is characterized by excellent strength. Also, an addition-curable liquid silicone rubber composition for an airbag incorporating an organosilicon resin composed of M, D, and Q units and having a crosslinkable functional group only in the D unit as a flame retardant has been disclosed (Patent Document 3). The airbag coated with this composition is characterized by excellent low burning rate properties.

[0004] On the other hand, in recent years, in order to save space and reduce weight, methods for reducing the coating amount of the silicone rubber composition have been continuously developed, and it is desired to develop a silicone rubber composition for an airbag that has the same flame retardancy as before even with a low coating amount. As a method for improving flame retardancy, incorporation of a flame retardant has been considered. For example, a composition obtained by incorporating iron(III) monohydrate or α-iron(III) as a flame retardant into a silicone rubber composition (Patent Document 4), a composition obtained by incorporating aluminum hydroxide into a silicone rubber composition (Patent Document 5), and a composition obtained by incorporating phosphazene into a silicone rubber composition (Patent Document 6) have been disclosed. However, when a solid flame retardant is incorporated into a silicone rubber composition, the flame retardant sometimes precipitates due to a density difference. Further, for a recent organosilicon-coated airbag base fabric with a low coating amount, since the silicone rubber layer is thin, if the solid flame retardant has a large particle size, part of the flame retardant sometimes exposes on the surface of the silicone rubber layer, and sufficient airtightness cannot be ensured. Further, the solid flame retardant is not compatible with the silicone rubber composition, and thus cannot be uniformly dispersed in the organosilicon layer. Therefore, coating unevenness sometimes occurs during coating, or the flame retardancy and base fabric properties such as tensile strength of the obtained organosilicon-coated base fabric deviate depending on the sampling position.

[0005] Prior art documents

[0006] Patent documents

[0007] Patent document 1: Japanese Patent Application Laid-Open No. 2013-209517

[0008] Patent document 2: Japanese Patent Application Laid-Open No. 2019-513907

[0009] Patent document 3: International Publication No. 2018 / 168315

[0010] Patent document 4: Japanese Patent Application Laid-Open No. 2022-072086

[0011] Patent document 5: Japanese Patent Application Laid-Open No. 2010-053493

[0012] Patent document 6: Japanese Patent Application Laid-Open No. 2014-136722 Summary of the invention

[0013] (1) Technical problem to be solved

[0014] The present invention has been completed in view of the above circumstances, and an object thereof is to provide an addition-curable liquid silicone rubber composition for an airbag and an airbag, the addition-curable liquid silicone rubber composition for an airbag having excellent low combustion speed property when coated on a base fabric for an airbag and cured, and not causing color unevenness.

[0015] (2) Technical solution

[0016] In order to solve the above problems, the present invention provides an addition-curable liquid silicone rubber composition for an airbag, which contains:

[0017] (A) 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, in an amount of 100 parts by mass;

[0018] (B) An organohydrogenpolysiloxane having two or more hydrogen atoms (hydrosilyl groups) bonded to silicon atoms in one molecule, in an amount such that the hydrosilyl groups contained in the composition are 1 to 10 moles per 1 mole of alkenyl groups bonded to silicon atoms in total contained in the composition;

[0019] (C) Silica fine powder having a BET specific surface area of 50 m 2 / g or more, in an amount of 1 to 50 parts by mass;

[0020] (D) A catalyst for hydrosilylation reaction, in an amount of 1 to 500 ppm in terms of the mass of the catalyst metal element relative to the mass of the component (A);

[0021] (E) An organosilicon compound having a functional group for imparting adhesiveness, which is 0.1 to 10 parts by mass; and

[0022] (F) A metal carboxylate, which is 100 to 5,000 ppm in terms of the mass of the central metal relative to the mass of the component (A).

[0023] If it is such an addition-curing type liquid silicone rubber composition for an airbag, the flame retardancy of the silicone-coated base fabric for an airbag produced therefrom is excellent and color unevenness does not occur.

[0024] In addition, in the present invention, it is preferable that: the component (E) is an organosilicon compound having at least one reactive silicon group selected from an alkoxysilyl group, an alkenylsilyl group, and a hydrosilyl group and at least one reactive organic group selected from an epoxy group, an isocyanate group, and a (meth)acryloyl group in one molecule.

[0025] If it is such an addition-curing type liquid silicone rubber composition for an airbag, the adhesiveness of the silicone rubber layer to the base fabric for an airbag is more excellent.

[0026] In addition, in the present invention, it is preferable that: relative to 100 parts by mass of the component (A), 0.05 to 5 parts by mass of a condensation catalyst as the component (G) is further contained, and the condensation catalyst is at least one selected from an organic titanium compound, an organic zirconium compound, and an organic aluminum compound.

[0027] If it is such an addition-curing type liquid silicone rubber composition for an airbag, the adhesiveness of the silicone rubber layer to the base fabric for an airbag is more excellent.

[0028] In addition, in the present invention, it is preferable that: the metal carboxylate of the component (F) is a metal salt of a carboxylic acid having 6 or more carbon atoms.

[0029] If it is such a metal carboxylate, the compatibility with the silicone rubber composition is improved and it can be easily dispersed. If it is such an addition-curing type liquid silicone rubber composition for an airbag, the flame retardancy of the silicone-coated base fabric for an airbag produced therefrom is more excellent.

[0030] In addition, in the present invention, it is preferable that: the central metal ion of the metal carboxylate of the component (F) is a trivalent iron ion.

[0031] If it is such a metal carboxylate, it can be purchased inexpensively. If it is such an addition-curing type liquid silicone rubber composition for an airbag, the flame retardancy of the silicone-coated base fabric for an airbag produced therefrom is more excellent.

[0032] In addition, in the present invention, preferably, 0.1 to 100 parts by mass of a powdery three-dimensional network organopolysiloxane resin as the component (H) is further contained relative to 100 parts by mass of the component (A), wherein the organopolysiloxane resin does not contain hydrogen atoms bonded to silicon atoms.

[0033] If it is such an addition-curing type liquid silicone rubber composition for an airbag, the flame retardancy of the silicone-coated base fabric for an airbag made therefrom is more excellent.

[0034] In addition, the present invention also provides an airbag having a cured coating film of the above-mentioned addition-curing type liquid silicone rubber composition for an airbag on a base fabric for an airbag.

[0035] If it is such an airbag, it has excellent flame retardancy and no color unevenness will occur.

[0036] (III) Beneficial effects

[0037] As described above, according to the present invention, it is possible to provide an addition-curing type liquid silicone rubber composition for an airbag and an airbag. The addition-curing type liquid silicone rubber composition for an airbag has excellent flame retardancy and no color unevenness when coated and cured on a base fabric for an airbag. Detailed implementation manners

[0038] As described above, it is desired to develop an addition-curing type liquid silicone rubber composition for an airbag and an airbag having excellent flame retardancy when coated and cured on a base fabric for an airbag.

[0039] The inventors of the present application have conducted in-depth research on the above technical problems and found that if it is an addition-curing type liquid silicone rubber composition for an airbag containing a metal carboxylate, when coated and cured on a base fabric for an airbag, the coated base fabric has excellent flame retardancy and no color unevenness, and thus the present invention has been completed.

[0040] That is, the present invention is an addition-curing type liquid silicone rubber composition for an airbag, which contains:

[0041] (A) An organopolysiloxane having two or more alkenyl groups bonded to silicon atoms in one molecule and a polymerization degree of 50 to 2,000, which is 100 parts by mass;

[0042] (B) An organohydrogenpolysiloxane having two or more hydrogen atoms (hydrosilyl groups) bonded to silicon atoms in one molecule, and the amount of the hydrosilyl groups contained in the composition is 1 to 10 moles relative to each total 1 mole of the alkenyl groups bonded to silicon atoms contained in the composition;

[0043] (C)Silica fine powder with a BET specific surface area of 50 m 2 / g or more, which is 1 to 50 parts by mass;

[0044] (D)A catalyst for hydrosilylation reaction, which is 1 to 500 ppm in terms of the mass of the catalyst metal element relative to the mass of the component (A);

[0045] (E)An organosilicon compound having a functional group for imparting adhesiveness, which is 0.1 to 10 parts by mass; and

[0046] (F)A metal carboxylate, which is 100 to 5,000 ppm in terms of the mass of the central metal relative to the mass of the component (A).

[0047] Hereinafter, the present invention will be described in detail, but the present invention is not limited thereto. In addition, in this specification, the viscosity is a value measured by a rotational viscometer according to the method described in Japanese Industrial Standard JIS K7117-1:1999 at 25°C. Further, the weight-average degree of polymerization is a value obtained as the weight-average molecular weight (weight-average degree of polymerization) in terms of polystyrene obtained by GPC (gel permeation chromatography) analysis using tetrahydrofuran (THF) as the developing solvent under the following conditions.

[0048] [Measurement conditions]

[0049] Developing solvent: Tetrahydrofuran

[0050] Flow rate: 0.35 ml / min

[0051] Detector: Differential refractive index detector (RI)

[0052] Chromatographic column: TSK Guardcolumn SuperH-L

[0053] TSKgel SuperH4000 (6.0 mm I.D. × 15 cm × 1)

[0054] TSKgel SuperH3000 (6.0 mm I.D. × 15 cm × 1)

[0055] TSKgel SuperH2000 (6.0 mm I.D. × 15 cm × 2)

[0056] (All are manufactured by Tosoh Corporation)

[0057] Column temperature: 40°C

[0058] Sample injection volume: 10 μL (tetrahydrofuran solution with a concentration of 0.5 wt%)

[0059] <Addition-curable liquid silicone rubber composition for airbag>

[0060] Preferably, the addition-curable liquid silicone rubber composition for airbag of the present invention contains the following components and is in a liquid state at room temperature (25 °C), and the components are:

[0061] (A) An organopolysiloxane having two or more alkenyl groups bonded to silicon atoms in one molecule and a polymerization degree of 50 to 2,000, which is 100 parts by mass;

[0062] (B) An organohydrogenpolysiloxane having two or more hydrogen atoms (hydrosilyl groups) bonded to silicon atoms in one molecule, and the amount of hydrosilyl groups contained in the composition is 1 to 10 moles relative to each total 1 mole of alkenyl groups bonded to silicon atoms contained in the composition;

[0063] (C) Fumed silica having a BET specific surface area of 50 m 2 / g or more, which is 1 to 50 parts by mass;

[0064] (D) A catalyst for hydrosilylation reaction, which is 1 to 500 ppm in terms of the mass of the catalyst metal element relative to the mass of the component (A);

[0065] (E) An organosilicon compound having a functional group for imparting adhesiveness, which is 0.1 to 10 parts by mass; and

[0066] (F) A metal carboxylate, which is 100 to 5,000 ppm in terms of the mass of the central metal relative to the mass of the component (A).

[0067] Hereinafter, each component will be described in detail.

[0068] [Component (A)]

[0069] The organopolysiloxane of the component (A) is an organopolysiloxane containing two or more alkenyl groups bonded to silicon atoms in one molecule and having a weight-average polymerization degree of 50 to 2,000, that is, an organopolysiloxane having two or more alkenyl groups bonded to silicon atoms in one molecule and a polymerization degree of 50 to 2,000, which is the base polymer (main agent) of the addition-curable liquid silicone rubber composition for airbag of the present invention.

[0070] Regarding the molecular structure of the component (A), a linear diorganopolysiloxane in which the main chain is substantially composed of repeating diorganosiloxane units and both ends of the molecular chain are terminated with triorganosiloxy groups is preferred. Further, in the molecule of the linear organopolysiloxane as the component (A), the position of the silicon atom to which the alkenyl group is bonded may be either or both of the molecular chain end (i.e., triorganosiloxy group) and in the molecular chain (i.e., a bifunctional diorganosiloxane unit located at a non-terminal position of the molecular chain). As the component (A), a linear diorganopolysiloxane containing at least alkenyl groups bonded to silicon atoms at both ends of the molecular chain is particularly preferred.

[0071] As the alkenyl group bonded to the silicon atom in the component (A), for example, an alkenyl group having 2 to 8 carbon atoms, preferably 2 to 4 carbon atoms, is generally exemplified. Specific examples thereof include vinyl, allyl, propenyl, butenyl, pentenyl, hexenyl, cyclohexenyl, heptenyl, etc., and vinyl is particularly preferred.

[0072] The number of alkenyl groups bonded to the silicon atom in the component (A) is 2 or more in one molecule, preferably 2 to 100, more preferably 2 to 50.

[0073] As the monovalent hydrocarbon group bonded to the silicon atom other than the alkenyl group in the component (A), for example, a monovalent hydrocarbon group having 1 to 12 carbon atoms, preferably 1 to 10 carbon atoms, is generally exemplified. Specific examples of the monovalent hydrocarbon group include alkyl groups such as methyl, ethyl, propyl, butyl, pentyl, hexyl, cyclohexyl, heptyl; aryl groups such as phenyl, tolyl, xylyl, naphthyl; aralkyl groups such as benzyl, phenethyl; haloalkyl groups such as chloromethyl, 3-chloropropyl, 3,3,3-trifluoropropyl, etc.; and methyl is particularly preferred.

[0074] The weight-average degree of polymerization of the component (A) is 50 to 2,000, preferably 100 to 1,500, more preferably 120 to 1,000. If the weight-average degree of polymerization is less than 50, the physical properties of the addition-curable liquid silicone rubber composition for airbags obtained may sometimes deteriorate. Further, if the weight-average degree of polymerization is greater than 2,000, the viscosity of the addition-curable liquid silicone rubber composition for airbags obtained may sometimes become high and the coating workability may deteriorate.

[0075] (A) component preferably has a viscosity of 50 to 200,000 mPa·s at 25°C, more preferably 100 to 150,000 mPa·s, and even more preferably 400 to 100,000 mPa·s. As long as the viscosity of the (A) component is 50 mPa·s or more, the physical properties of the addition-curable liquid silicone rubber composition for airbags obtained will be good. If it is 200,000 mPa·s or less, the viscosity of the addition-curable liquid silicone rubber composition for airbags obtained will not be too high, and the coating operability will also become appropriate.

[0076] Specific examples of the organopolysiloxane as the (A) component include dimethylsiloxane-methylvinylsiloxane copolymer endblocked with trimethylsiloxy groups at both ends of the molecular chain, methylvinylpolysiloxane endblocked with trimethylsiloxy groups at both ends of the molecular chain, dimethylsiloxane-methylvinylsiloxane-methylphenylsiloxane copolymer endblocked with trimethylsiloxy groups at both ends of the molecular chain, dimethylpolysiloxane endblocked with dimethylethenylsiloxy groups at both ends of the molecular chain, methylvinylpolysiloxane endblocked with dimethylethenylsiloxy groups at both ends of the molecular chain, dimethylsiloxane-methylvinylsiloxane copolymer endblocked with dimethylethenylsiloxy groups at both ends of the molecular chain, dimethylsiloxane-methylvinylsiloxane-methylphenylsiloxane copolymer endblocked with dimethylethenylsiloxy groups at both ends of the molecular chain, dimethylpolysiloxane endblocked with divinylmethylsiloxy groups at both ends of the molecular chain, dimethylsiloxane-methylvinylsiloxane copolymer endblocked with divinylmethylsiloxy groups at both ends of the molecular chain, dimethylpolysiloxane endblocked with trivinylsiloxy groups at both ends of the molecular chain, dimethylsiloxane-methylvinylsiloxane copolymer endblocked with trivinylsiloxy groups at both ends of the molecular chain, and mixtures composed of two or more of these organopolysiloxanes.

[0077] (A) component of the organopolysiloxane can be used alone in one kind, or two or more kinds can be used simultaneously.

[0078] [(B) component]

[0079] (B) component is an organohydrogenpolysiloxane having two or more hydrogen atoms (hydrosilyl groups) bonded to silicon atoms in one molecule, and it functions as a crosslinking agent for the composition.

[0080] (B) The molecular structure of the organohydrogenpolysiloxane can be any of linear, cyclic, branched, or three-dimensional network structures. At this time, it is preferable to use an organohydrogenpolysiloxane having 2 to 300, particularly about 4 to 200, silicon atoms (or degree of polymerization) per molecule and being liquid at 25°C. In addition, the number of silicon-hydrogen groups contained in one molecule is 2 or more, preferably 2 to 200, more preferably 2 to 150, and further preferably 2 to 100. Further, the silicon-hydrogen groups may be located at the ends of the molecular chain, in the side chain (in the middle of the molecular chain), or in both positions.

[0081] As the substituent bonded to the silicon atom of the component (B), for example, a monovalent hydrocarbon group having 1 to 12 carbon atoms, preferably a monovalent hydrocarbon group having 1 to 10 carbon atoms, can generally be cited. Specific examples of the monovalent hydrocarbon group 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; haloalkyl groups such as chloromethyl, 3-chloropropyl, and 3,3,3-trifluoropropyl; etc. Particularly preferred are methyl or phenyl.

[0082] Examples of such organohydrogenpolysiloxanes include 1,1,3,3-tetramethyldisiloxane, 1,3,5,7-tetramethylcyclotetrasiloxane, methylhydrogencyclopolysiloxane, methylhydrogensiloxane-dimethylsiloxane cyclic copolymer, tris(dimethylhydroxysilyloxy)methylsilane, tris(dimethylhydroxysilyloxy)phenylsilane, methylhydrogenpolysiloxane capped with trimethylsilyloxy groups at both ends, dimethylsiloxane-methylhydrogensiloxane copolymer capped with trimethylsilyloxy groups at both ends, dimethylpolysiloxane capped with dimethylhydroxysilyloxy groups at both ends, dimethylsiloxane-methylhydrogensiloxane copolymer capped with dimethylhydroxysilyloxy groups at both ends, methylhydrogensiloxane-diphenylsiloxane copolymer capped with trimethylsilyloxy groups at both ends, methylhydrogensiloxane-diphenylsiloxane-dimethylsiloxane copolymer capped with trimethylsilyloxy groups at both ends, cyclic methylhydrogenpolysiloxane, cyclic methylhydrogensiloxane-dimethylsiloxane copolymer, cyclic methylhydrogensiloxane-diphenylsiloxane-dimethylsiloxane copolymer, a copolymer composed of (CH3)2HSiO 1 / 2 units and SiO 4 / 2 units, a copolymer composed of (CH3)2HSiO 1 / 2 units and SiO 4 / 2 units and (C6H5)SiO 3 / 2 units, or an organohydrogenpolysiloxane in which part or all of the methyl groups in the above-exemplified compounds are replaced by other alkyl groups such as ethyl and propyl or aryl groups such as phenyl. In addition, as such an organohydrogenpolysiloxane, a compound having the following structural formula can be specifically exemplified.

[0083] [Chemical Formula 1]

[0084]

[0085] In the formula, e is an integer from 2 to 200, and f, g, and h are each an integer from 0 to 200.

[0086] As the organohydrogenpolysiloxane, the viscosity at 25°C is preferably 0.5 to 10,000 mPa·s, and particularly preferably 1 to 300 mPa·s.

[0087] The blending amount of component (B) is such that, relative to a total of 1 mole (or unit) of alkenyl groups bonded to silicon atoms in the composition containing component (A), the amount of hydrosilyl groups contained in the composition containing component (B) is 1 to 10 moles (or units), preferably 1.2 to 9 moles (or units), and more preferably 1.5 to 8 moles (or units). If the amount of hydrosilyl groups contained in the composition containing component (B) is less than 1 mole relative to a total of 1 mole (or unit) of alkenyl groups bonded to silicon atoms in the composition containing component (A), the addition-curable liquid silicone rubber composition for airbags cannot be sufficiently cured. In addition, if it is greater than 10 moles, the heat resistance of the silicone rubber cured product obtained from the addition-curable liquid silicone rubber composition for airbags is sometimes extremely poor.

[0088] The organohydrogenpolysiloxane of component (B) can be used alone or two or more kinds can be used simultaneously.

[0089] [Component (C)]

[0090] The BET specific surface area of component (C) is silica fine powder of 50 m 2 / g or more, which functions as a reinforcing filler. That is, it is a substance for imparting strength to the silicone rubber cured product obtained from the addition-curable liquid silicone rubber composition for airbags of the present invention. Therefore, by using silica fine powder as a reinforcing filler, a coating film satisfying the required strength of the present invention can be formed. The specific surface area of the silica fine powder obtained by the BET method is 50 m 2 / g or more, preferably 50 to 400 m 2 / g, and more preferably 100 to 300 m 2 / g. When the specific surface area is less than 50 m 2 / g, the physical strength characteristics required as a coating agent for airbags cannot be imparted.

[0091] As such silica fine powder, known substances that have a specific surface area within the above range and have been conventionally used as reinforcing fillers for silicone rubber cured products can be cited. For example, fumed silica (pyrogenic silica), precipitated silica (wet silica), etc. can be mentioned.

[0092] As the above silica fine powder, silica fine powder whose surface has been hydrophobized using a surface treatment agent such as a chlorosilane, alkoxysilane, organosilazane, etc. (usually a hydrolyzable) organosilicon compound can be used. At this time, these silica fine powders can use substances that have been directly surface hydrophobized using a surface treatment agent in the powder state in advance. In addition, substances that have been surface hydrophobized by adding a surface treatment agent when kneaded with silicone oil (for example, the alkenyl-containing organopolysiloxane of the above component (A)) can also be used.

[0093] As a treatment method for component (C), surface treatment can be carried out by a known technique. For example, the above untreated silica fine powder and a surface treatment agent can be added in a closed mechanical kneading device or a fluidized bed device under normal pressure, and kneading treatment can be carried out at room temperature (25°C) or heat treatment (heating) in the presence of an inert gas as needed. Depending on the situation, water or a catalyst (hydrolysis promoter, etc.) can be used to promote the surface treatment. After kneading, surface-treated silica fine powder can be manufactured by drying. The blending amount of the surface treatment agent only needs to be greater than or equal to the amount calculated from the coverage area of the surface treatment agent.

[0094] Specific examples of the surface treatment agent 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.; Hydrophobic silica fine powder can be used by carrying out surface treatment with these surface treatment agents. As the surface treatment agent, a silane coupling agent or a silazane is particularly preferred.

[0095] In addition, when the silica fine powder of component (C) uses a substance that has been directly surface hydrophobized using an alkenyl-containing surface treatment agent in the powder state in advance, it is preferably in an amount such that the hydrosilyl group contained in the composition containing component (B) is 1 to 10 moles (or units), preferably 1.2 to 8 moles (or units), more preferably 1.5 to 6 moles (or units) relative to 1 mole (or unit) of the alkenyl bonded to the silicon atom contained in the total composition of the surface treatment agent containing components (A) and (C).

[0096] This is because, with respect to 1 mole of the alkenyl bonded to a silicon atom in the addition-curable liquid silicone rubber composition for an airbag, if the amount of hydrosilyl group is less than 1 mole, the addition-curable liquid silicone rubber composition for an airbag may not be sufficiently cured, and thus may not exhibit sufficient adhesive strength. On the other hand, if the amount of hydrosilyl group is greater than 10 moles, the heat resistance of the silicone rubber cured product obtained from the addition-curable liquid silicone rubber composition for an airbag may be extremely poor.

[0097] With respect to 100 parts by mass of the organopolysiloxane of component (A), the blending amount of component (C) is 1 to 50 parts by mass, preferably 3 to 30 parts by mass, more preferably 5 to 25 parts by mass. If the blending amount is less than 1 part by mass, a silicone rubber cured product having sufficient strength cannot be obtained. If the blending amount is greater than 30 parts by mass, the viscosity of the addition-curable liquid silicone rubber composition for an airbag obtained may become high, the fluidity may decrease, and the coating operation may deteriorate.

[0098] The fine silica powder of component (C) can be used alone or two or more kinds can be used simultaneously.

[0099] [Component (D)]

[0100] The catalyst for hydrosilylation reaction of component (D) is mainly a substance that promotes the addition reaction between the alkenyl bonded to a silicon atom in component (A) and the hydrosilyl group in component (B). There is no particular limitation on the catalyst for hydrosilylation reaction, and examples thereof include platinum group metals such as platinum, palladium, and rhodium; chloroplatinic acid; alcohol-modified chloroplatinic acid; coordination compounds of chloroplatinic acid with olefins, vinylsiloxanes, or acetylene compounds; platinum group metal compounds such as tetrakis(triphenylphosphine)palladium and chlorotris(triphenylphosphine)rhodium, etc., and platinum group metal compounds are preferred.

[0101] In terms of the mass conversion of the catalyst metal element, the blending amount of component (D) is 1 to 500 ppm, preferably 5 to 100 ppm, relative to the mass of component (A). If the blending amount is less than 1 ppm, the addition reaction significantly slows down, or the addition-curable liquid silicone rubber composition for an airbag cannot be cured, so it is not preferred. If the blending amount is greater than 500 ppm, the heat resistance of the silicone rubber cured product may decrease.

[0102] The catalyst for hydrosilylation reaction of component (D) can be used alone or two or more kinds can be used simultaneously.

[0103] [Component (E)]

[0104] (E) The component is a silicone compound having a functional group for imparting adhesiveness, and is an added component for improving the adhesiveness of the addition-curing liquid silicone rubber composition for airbags to the base fabric for airbags.

[0105] (E) As long as the component is a silicone compound having a functional group for imparting adhesiveness, any component can be used, but a silicone compound having at least one reactive silyl group selected from alkoxysilyl groups, alkenyl-containing silyl groups, and hydrosilyl groups and at least one reactive organic group selected from epoxy groups, isocyanate groups, and (meth)acryloyl groups in one molecule is preferred.

[0106] The alkoxy group (alkoxysilyl group) bonded to the silicon atom preferably forms a trialkoxysilyl group such as trimethoxysilyl group or triethoxysilyl group by bonding to the silicon atom; an alkyldialkoxysilyl group such as methyldimethoxysilyl group, ethyldimethoxysilyl group, methyldiethoxysilyl group, or ethyldiethoxysilyl group. The epoxy group is preferably bonded to the silicon atom in the form of a glycidyloxyalkyl group such as glycidyloxypropyl group, a cyclohexylalkyl group containing epoxy such as 2,3-epoxycyclohexylethyl group or 3,4-epoxycyclohexylethyl group.

[0107] Examples of the silicone compound as component (E) include silane coupling agents containing epoxy groups (i.e., organoalkoxysilanes containing epoxy functional groups) such as γ-glycidyloxypropyltriethoxysilane, γ-glycidyloxypropylmethyldiethoxysilane, (3,4-epoxycyclohexylethyl)trimethoxysilane, (3,4-epoxycyclohexylethyl)triethoxysilane, (3,4-epoxycyclohexylethyl)methyldimethoxysilane, (3,4-epoxycyclohexylethyl)methyldiethoxysilane, (2,3-epoxycyclohexylethyl)triethoxysilane, (2,3-epoxycyclohexylethyl)methyldimethoxysilane, (2,3-epoxycyclohexylethyl)methyldiethoxysilane; or silane coupling agents containing (meth)acryloyl groups such as 3-acryloxypropyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane; or silane coupling agents containing isocyanate groups such as 3-isocyanatopropyltriethoxysilane, 3-isocyanatopropyltrimethoxysilane; or cyclic organopolysiloxanes containing epoxy groups or linear organopolysiloxanes containing epoxy groups represented by the following chemical formula; mixtures of two or more of these or partial hydrolysis condensates of one or two or more of these.

[0108] The main components are exemplified below.

[0109] [Chemical formula 2]

[0110]

[0111] In the formula, p is an integer from 1 to 40, q is an integer from 0 to 40, r is an integer from 1 to 40, preferably an integer from 1 to 20.

[0112] With respect to 100 parts by mass of the organopolysiloxane of component (A), the blending amount of component (E) is 0.1 to 10 parts by mass, preferably 0.15 to 5 parts by mass. If the blending amount is less than 0.1 part by mass, the addition-curable liquid silicone rubber composition for airbags obtained sometimes cannot exhibit sufficient adhesiveness. If the blending amount is greater than 10 parts by mass, the thixotropy of the addition-curable liquid silicone rubber composition for airbags sometimes becomes high, the fluidity decreases, and the coating workability deteriorates.

[0113] In addition, when component (E) contains an alkenyl group and / or a hydrosilyl group, with respect to a total of 1 mole (or unit) of alkenyl groups bonded to silicon atoms contained in the composition containing components (A), (C), and (E), the total amount of hydrosilyl groups contained in the composition containing components (B) and (E) is in an amount of 1 to 10 moles (or units), preferably 1.2 to 8 moles (or units), more preferably 1.5 to 6 moles (or units).

[0114] This is because, with respect to 1 mole of alkenyl groups bonded to silicon atoms in the addition-curable liquid silicone rubber composition for airbags, if the amount of hydrosilyl groups is less than 1 mole, the addition-curable liquid silicone rubber composition for airbags sometimes cannot be sufficiently cured and cannot exhibit sufficient adhesiveness. On the other hand, if the amount of hydrosilyl groups is greater than 10 moles, the heat resistance of the silicone rubber cured product obtained from the addition-curable liquid silicone rubber composition for airbags is sometimes extremely poor.

[0115] Component (E) can be used alone in one kind or two or more kinds can be used simultaneously.

[0116] [(F) component]

[0117] Component (F) is a metal carboxylate salt, which functions as a flame retardancy improver. In terms of the mass conversion of the central metal, the blending amount of component (F) is 100 to 5,000 ppm, preferably 120 to 3,000 ppm, more preferably 150 to 2,000 ppm, with respect to the mass of component (A). If the blending amount of component (F) is less than 100 ppm, sometimes a sufficient flame retardancy improvement effect cannot be obtained. If it is more than 5,000 ppm, sometimes the viscosity of the composition becomes high and the coating workability deteriorates.

[0118] The metal carboxylate of the component (F) preferably contains a carbon atom of a carbonyl group, preferably a metal salt of a carboxylic acid having 6 or more carbon atoms. If it is a metal salt of a carboxylic acid having 6 or more carbon atoms, the compatibility with the silicone rubber composition is improved, and thus it can be easily dispersed. The upper limit value of the number of carbon atoms of the carboxylic acid is not particularly limited, and can be set to 20 or less, for example.

[0119] The central metal ion of the metal carboxylate of the component (F) is not particularly limited, and for example, lithium ion, potassium ion, calcium ion, titanium ion, iron ion, cobalt ion, nickel ion, copper ion, zinc ion, zirconium ion, tin ion, lead ion, etc. can be used, but trivalent iron ion is preferred. If it is a carboxylate of trivalent iron ion, it can be purchased inexpensively.

[0120] Specific examples of the component (F) include lithium 2-ethylhexanoate (I), potassium 2-ethylhexanoate (I), calcium bis(2-ethylhexanoate) (II), titanium(IV) bis(2-ethylhexanoate) (IV), manganese(II) bis(2-ethylhexanoate) (II), iron(III) tris(2-ethylhexanoate) (III), cobalt(II) bis(2-ethylhexanoate) (II), nickel(II) bis(2-ethylhexanoate) (II), zinc(II) bis(2-ethylhexanoate) (II), zirconium(II) bis(2-ethylhexanoate) (II), tin(II) bis(2-ethylhexanoate) (II), lead(II) bis(2-ethylhexanoate) (II) and other 2-ethylhexanoates; lithium stearate (I), potassium stearate (I), calcium bis(stearate) (II), titanium(IV) bis(stearate) (IV), manganese(II) bis(stearate) (II), iron(III) tris(stearate) (III), cobalt(II) bis(stearate) (II), nickel(II) bis(stearate) (II), zinc(II) bis(stearate) (II), zirconium(II) bis(stearate) (II), tin(II) bis(stearate) (II), lead(II) bis(stearate) (II) and other stearates, etc. Iron(III) tris(2-ethylhexanoate) (III), cobalt(II) bis(2-ethylhexanoate) (II), and potassium 2-ethylhexanoate (I) are particularly preferred.

[0121] The component (F) can be used alone in one kind, or two or more kinds can be used simultaneously.

[0122] [Other components]

[0123] In the addition-curable liquid silicone rubber composition for airbags of the present invention, in addition to the above components (A) to (F), any other components can be blended according to the purpose. Specific examples thereof are as follows. Each of these other components can be used alone in one kind, or two or more kinds can be used simultaneously.

[0124] [Component (G)]

[0125] Furthermore, it can contain one or more condensation catalysts selected from organotitanium compounds, organozirconium compounds, and organoaluminum compounds as the (G) component. As the (G) component, one or more selected from titanium alkoxide complexes, titanium chelate complexes, zirconium alkoxide complexes, and zirconium chelate complexes are preferred, and it functions as a condensation catalyst for the adhesion-imparting functional group in the (E) component to promote adhesion.

[0126] Specific examples of the (G) component include titanium alkoxide complexes such as tetra(isopropyl) phthalate, tetra(n-butyl) phthalate, and tetra(2-ethylhexyl) titanate; titanium chelate complexes such as diisopropoxybis(acetylacetone)titanium, diisopropoxybis(ethyl acetoacetate)titanium, and titanium tetraacetylacetonate; zirconium alkoxide complexes such as tetra(n-propyl) zirconate and tetra(n-butyl) zirconate; and zirconium chelate complexes such as tributoxymono(acetylacetone)zirconium, monobutoxy(acetylacetone)zirconium bis(ethyl acetoacetate), and zirconium tetraacetylacetonate.

[0127] One or more condensation catalysts selected from organotitanium compounds, organozirconium compounds, and organoaluminum compounds as the (G) component are optional components incorporated as needed. With respect to 100 parts by mass of the (A) component, the incorporation amount is preferably 0.05 to 5 parts by mass, more preferably 0.1 to 2 parts by mass. If the incorporation amount is within the range of 0.05 to 5 parts by mass, the cured product obtained from the addition-curing type liquid silicone rubber composition for airbags has excellent adhesion to the base fabric for airbags.

[0128] The (G) component can be used alone or two or more thereof can be used simultaneously.

[0129] [(H) component]

[0130] Furthermore, it can contain a powdery three-dimensional network organopolysiloxane resin as the (H) component (wherein the organopolysiloxane resin does not contain hydrogen atoms bonded to silicon atoms). The (H) component is a three-dimensional network (resin-like) organopolysiloxane resin. It is suitable for being mainly composed of one or more branched siloxane units selected from 3-functional R 2 SiO 3 / 2 units and 4-functional SiO 4 / 2 units, and can optionally contain monofunctional R 2 3SiO 1 / 2 units and / or bifunctional R 2 2SiO 2 / 2The unit functions as a flame retardancy improver. Among them, the organopolysiloxane resin may contain alkenyl bonded to a silicon atom in the molecule, but does not contain a hydrogen atom (hydrosilyl) bonded to a silicon atom. In addition, the organopolysiloxane resin has a three-dimensional network (resin-like) structure and is in powder form at 25°C, so it is clearly distinguishable from the component (A) which basically has a linear structure and is in liquid form at 25°C.

[0131] R in the above formula 2 is independently a monovalent hydrocarbon group having 1 to 10 carbon atoms, preferably a monovalent hydrocarbon group having 1 to 8 carbon atoms, and examples thereof include the same groups as the alkenyl and monovalent hydrocarbon groups exemplified in the above component (A). Specifically, examples include alkenyl such as vinyl, allyl, propenyl, butenyl, pentenyl, hexenyl, cyclohexenyl, heptenyl; alkyl such as methyl, ethyl, propyl, butyl, pentyl, hexyl, cyclohexyl, heptyl; aryl such as phenyl, tolyl, xylyl, naphthyl; aralkyl such as benzyl, phenethyl; haloalkyl such as chloromethyl, 3-chloropropyl, 3,3,3-trifluoropropyl, etc.; particularly preferably methyl and vinyl.

[0132] Relative to all substituents bonded to the silicon atom, the content of the alkenyl bonded to the silicon atom in the component (H) is preferably 0 to 10 mol%, particularly preferably about 2 to 8 mol%.

[0133] The organopolysiloxane resin of the component (H) preferably contains R 2 SiO 3 / 2 units and / or SiO 4 / 2 units, and the total amount thereof is preferably 20 to 75 mol% in the organopolysiloxane resin of the component (H), particularly preferably 30 to 65 mol%.

[0134] Among them, the organopolysiloxane resin of the component (H) may optionally contain R 2 3SiO 1 / 2 units and / or R 2 2SiO 2 / 2 units, but the total amount thereof is preferably 0 to 70 mol% in the organopolysiloxane resin of the component (H), particularly preferably 0 to 50 mol%.

[0135] If the total amount of R 2 SiO 3 / 2 units and / or SiO 4 / 2 units in the organopolysiloxane resin of the component (H) is in the range of 20 to 75 mol%, a sufficient flame retardancy improvement effect can be obtained, so it is suitable.

[0136] In addition, the polystyrene-reduced weight-average molecular weight of the organopolysiloxane resin as the 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 4,000 to 20,000. When the weight-average molecular weight is in the range of 2,000 to 50,000, a sufficient flame retardancy improvement effect can be obtained, and it will result in a viscosity of the addition-curable liquid silicone rubber composition for airbags with good coating workability. In addition, this weight-average molecular weight is a value determined by GPC analysis under the same conditions as those used for determining the degree of polymerization of the component (A).

[0137] Specific examples of the organopolysiloxane resin as the component (H) include siloxane units represented by the formula R’3SiO 1 / 2 and siloxane units represented by the formula R’2R”SiO 1 / 2 and siloxane units represented by the formula R’2SiO 2 / 2 and siloxane units represented by the formula SiO 4 / 2 to form an organosiloxane copolymer, siloxane units represented by the formula R’3SiO 1 / 2 and siloxane units represented by the formula R’2R’’SiO 1 / 2 and siloxane units represented by the formula SiO 4 / 2 to form an organosiloxane copolymer, siloxane units represented by the formula R’2R’’SiO 1 / 2 and siloxane units represented by the formula R’2SiO 2 / 2 and siloxane units represented by the formula SiO 4 / 2 to form an organosiloxane copolymer, siloxane units represented by the formula R’R’’SiO 2 / 2 and siloxane units represented by the formula R’SiO 3 / 2 or siloxane units represented by the formula R’’SiO 3 / 2 to form an organosiloxane copolymer, and mixtures composed of two or more of these organopolysiloxanes.

[0138] In the above formulas, R’ is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms, preferably 1 to 8 carbon atoms, which are the same or different and other than alkenyl groups. Examples thereof include alkyl groups such as methyl, ethyl, propyl, butyl, pentyl, hexyl, cyclohexyl, heptyl; aryl groups such as phenyl, tolyl, xylyl, naphthyl; aralkyl groups such as benzyl, phenethyl; haloalkyl groups such as chloromethyl, 3-chloropropyl, 3,3,3-trifluoropropyl, etc.; particularly preferably methyl. In addition, in the above formulas, R’’ is an alkenyl group. Examples thereof include vinyl, allyl, butenyl, pentenyl, hexenyl, heptenyl, etc., and particularly preferably vinyl.

[0139] With respect to 100 parts by mass of the organopolysiloxane as the component (A), the blending amount of the 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. When the blending amount is within the range of 0.1 to 100 parts by mass, a sufficient flame retardancy improvement effect can be obtained, and the cost performance is excellent.

[0140] In addition, when the component (H) contains an alkenyl group, the amount of the hydrosilyl group contained in the composition is 1 to 10 moles with respect to each total 1 mole of the alkenyl groups bonded to silicon atoms contained in the composition. For example, with respect to the component (H), with respect to each total 1 mole of the alkenyl groups bonded to silicon atoms contained in the component (A), the component (C), the component (E), and the component (H) in the composition, the amount of the hydrosilyl groups contained in the component (B) and the component (E) is 1 to 10 moles (or pieces), preferably 1.2 to 8 moles (or pieces), and more preferably 1.5 to 6 moles (or pieces). This is because, with respect to each total 1 mole of the alkenyl groups bonded to silicon atoms contained in the composition, if the total amount of the hydrosilyl groups is less than 1 mole, the addition-curable liquid silicone rubber composition for an airbag sometimes cannot be sufficiently cured and cannot exhibit sufficient adhesiveness. On the other hand, if the hydrosilyl group is greater than 10 moles, the heat resistance of the silicone rubber cured product obtained from the addition-curable liquid silicone rubber composition for an airbag is extremely poor.

[0141] Thus, in the present invention, each component is blended such that the total number of moles of the hydrosilyl groups is 1 to 10 moles with respect to each total 1 mole of the alkenyl groups bonded to silicon atoms of each component contained in the addition-curable liquid silicone rubber composition for an airbag.

[0142] (H) The three-dimensional network organopolysiloxane resin of the component can be used alone or two or more kinds can be used simultaneously.

[0143] · Reaction control agent

[0144] The reaction control agent is not particularly limited as long as it is a compound having a curing inhibitory effect on the catalyst for the hydrosilylation reaction of the component (D), and a known reaction control agent can be used. As specific examples thereof, phosphorus-containing compounds such as triphenylphosphine can be cited; nitrogen-containing compounds such as tributylamine, tetramethylethylenediamine, and benzotriazole; sulfur-containing compounds; acetylene-based compounds such as alkynols; compounds containing two or more alkenyl groups; hydroperoxides; maleic acid derivatives, and the like.

[0145] The degree of the curing inhibition effect obtained by the reaction control agent varies depending on the chemical structure of the reaction control agent. Therefore, the addition amount of the reaction control agent is preferably adjusted to an optimum amount for each of the various reaction control agents used. By adding an optimum amount of the reaction control agent, the long-term storage stability and curability of the addition-curing type liquid silicone rubber composition for airbags at room temperature become excellent.

[0146] · Non-reinforcing filler

[0147] As fillers other than the surface-treated silica fine powder as the component (C), for example, crystalline silica (e.g., quartz powder having a specific surface area of less than 50 m 2 / g obtained by the BET method), organic resin-made hollow 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, kaolin, glass fiber and other fillers; fillers obtained by subjecting these fillers to surface hydrophobization treatment with organosilane compounds, organochlorosilane compounds, organosilazane compounds, low-molecular-weight siloxane compounds and other organosilicon compounds; silicone rubber powder; silicone resin powder and the like.

[0148] · Other components

[0149] In addition, for example, an organopolysiloxane having one hydrogen atom bonded to a silicon atom and no other functional groups in one molecule, an organopolysiloxane having one alkenyl group bonded to a silicon atom and no other functional groups in one molecule, a non-functional organopolysiloxane having no hydrogen atom bonded to a silicon atom, no alkenyl group bonded to a silicon atom and no other functional groups (so-called dimethyl silicone oil), an organic solvent, an anti-creep curing agent, a plasticizer, a thixotropic agent, a pigment, a dye, a mildew-proof agent and the like can be blended.

[0150] <Preparation of addition-curing type liquid silicone rubber composition for airbags>

[0151] In addition to the above components (A) to (F), the components (G) and (H) and other components further blended as needed are uniformly mixed, whereby an addition-curing type liquid silicone rubber composition for airbags can be prepared.

[0152] The addition-curing type liquid silicone rubber composition for airbag obtained thereby is a composition that 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 further preferably 5 to 300 Pa·s. If it is within the above viscosity range at 25°C, when coated on the base fabric for airbag, situations such as uneven coating and insufficient adhesion to the base fabric after curing are not likely to occur, so it is suitable for use.

[0153] <Base fabric for airbag>

[0154] Generally, as the base fabric for airbag (substrate composed of fiber fabric) formed with a silicone rubber layer, well-known base fabrics for airbag can be used. As specific examples thereof, fabrics of various synthetic fibers such as 6,6-nylon, 6-nylon, aramid fiber and other various polyamide fibers, polyethylene terephthalate (PET), polybutylene terephthalate (PBT) and other various polyester fibers can be cited.

[0155] <Airbag>

[0156] The airbag of the present invention is an airbag having a cured coating film of the above addition-curing type liquid silicone rubber composition for airbag on the base fabric for airbag.

[0157] <Manufacturing method of airbag>

[0158] The above addition-curing type liquid silicone rubber composition for airbag is coated on one side or both sides of the base fabric for airbag (substrate composed of fiber fabric), especially only coated on one side, and then heated and cured using a drying furnace or the like, and a silicone rubber layer (cured coating film) can be formed. Using the silicone rubber-coated base fabric for airbag obtained thereby, an airbag can be manufactured.

[0159] Among them, as the method for coating the addition-curing type liquid silicone rubber composition for airbag on the base fabric for airbag, a general method can be adopted, and it is preferably coated using a knife coater. The thickness of the coating (or surface coating amount) is usually set to 5 to 100 g / m 2 、preferably 8 to 90 g / m 2 、more preferably 10 to 80 g / m 2 .

[0160] The addition-curing type liquid silicone rubber composition for airbag can be cured by a well-known curing method under well-known curing conditions. Specifically, for example, by heating at 100 to 200°C for 1 to 30 minutes, the composition can be cured.

[0161] When processing the base fabric for airbags (silicone rubber-coated base fabric for airbags) having a silicone rubber layer on one or both sides thus manufactured into an airbag, methods such as the following can be cited: setting the surface coated with silicone rubber as the inner surface side and bonding the outer peripheral portions of two pieces of the above-mentioned silicone rubber-coated base fabric for airbags to each other using an adhesive, and then sewing the adhesive layer to manufacture it. In addition, the following method can also be adopted: coating the addition-curing type liquid silicone rubber composition for airbags on the outer surfaces of the base fabric for airbags pre-woven into a tubular shape in the above-mentioned specified coating amount, and then curing it under specified curing conditions. In addition, for the adhesive used here, known adhesives can be used, but considering aspects such as adhesive strength and adhesive durability, a silicone-based adhesive called a seam sealant is preferably used.

[0162] [Examples]

[0163] Hereinafter, preparation examples, examples and comparative examples will be shown to specifically describe the present invention, but the present invention is not limited by the following examples.

[0164] As component (A), the following components are used.

[0165] (A-1): A linear dimethylpolysiloxane with vinyl dimethylsilanyloxy groups capped at both ends of the molecular chain, a weight average degree of polymerization of 700, and a viscosity of 30,000 mPa·s

[0166] (A-2): A linear dimethyl-vinylmethylpolysiloxane with trimethylsilanyloxy groups capped at both ends of the molecular chain, a weight average degree of polymerization of 200, a viscosity of 700 mPa·s, containing 5 mol% of vinylmethylsiloxane units and 95 mol% of dimethylsiloxane units in the bifunctional diorganosiloxane units constituting the main chain

[0167] (A-3): A linear dimethylpolysiloxane with vinyl dimethylsilanyloxy groups capped at both ends of the molecular chain, a weight average degree of polymerization of 200, and a viscosity of 1,000 mPa·s

[0168] (A-4): A linear dimethylpolysiloxane with vinyl dimethylsilanyloxy groups capped at both ends of the molecular chain, a weight average degree of polymerization of 450, and a viscosity of 5,000 mPa·s

[0169] As component (B), the following components are used.

[0170] (B-1): A linear dimethylsiloxane-methylhydrogensiloxane copolymer with trimethylsilanyloxy groups capped at both ends of the molecular chain, a weight average degree of polymerization of 64, a viscosity of 45 mPa·s (hydrogen silyl content 0.011 mol / g)

[0171] (B-2): Linear methylhydrogenpolysiloxane with trimethylsiloxy groups at both ends of the molecular chain, a weight-average degree of polymerization of 40, a viscosity of 20 mPa·s, and a hydrogen silyl group content of 0.017 mol / g

[0172] As the component (C), the following components are used.

[0173] (C): Silica fine powder with a specific surface area of 300 m 2 / g (trade name: Aerosil 300, manufactured by NIPPON AEROSIL CO., LTD.)

[0174] As the component (D), the following components are used.

[0175] (D): Dimethylpolysiloxane solution containing 1% by mass of chloroplatinic acid / 1,3-divinyltetramethyldisiloxane complex in terms of platinum atom content

[0176] As the component (E), the following components are used.

[0177] (E): γ-Glycidoxypropyltrimethoxysilane

[0178] As the component (F), the following components are used.

[0179] (F-1): Iron(III) tris(2-ethylhexanoate), mineral spirits solution (trade name: NikkaOcthix lron, iron content 6%, manufactured by NIHON KAGAKU SANGYO CO., LTD.)

[0180] (F-2): Cobalt(II) bis(2-ethylhexanoate), mineral spirits solution (trade name: Nikka Octhix Cobalt, cobalt content 12%, manufactured by NIHON KAGAKU SANGYO CO., LTD.)

[0181] (F-3): Potassium 2-ethylhexanoate (I) (trade name: Nikka Octhix Potassium, potassium content 10%, manufactured by NIHONKAGAKU SANGYO CO., LTD.)

[0182] As the component (G), the following components are used.

[0183] (G): Zirconium tetraacetylacetonate (trade name: ZC-162, manufactured by Matsumoto Fine Chemical Co., Ltd.)

[0184] As the component (H), the following components are used.

[0185] (H): Consisting of (CH3)3SiO 1 / 2 units, (CH3)(CH2=CH)SiO 2 / 2 units and SiO 4 / 2 units, a powdery three-dimensional network organopolysiloxane resin with a weight-average molecular weight of 5,500, a Q unit content of 56 mol%, and an alkenyl content of 6.7 mol% relative to all substituents bonded to silicon atoms

[0186] As a flame retardant, the following components are used.

[0187] Iron(III) oxide (trade name: Toda Color 130ED, manufactured by Toda Pigment Co., Ltd.)

[0188] As a reaction control agent, the following components are used.

[0189] (Reaction control agent): 1-Ethynylcyclohexanol

[0190] [Preparation Example 1]

[0191] Add 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 fine silica powder (C) to a kneader, and mix at room temperature for 1 hour. Then, continue to add 8 parts by mass of hexamethyldisilazane and further mix at room temperature for 1 hour. Then, raise the temperature to 150 °C and continue to mix for 2 hours. Then, add 25 parts by mass of base oil (A-1) and 5 parts by mass of base oil (A-2) and mix until homogeneous to obtain a base compound.

[0192] [Examples 1 to 7, Comparative Examples 1 to 6]

[0193] Prepare an addition-curable liquid silicone rubber composition for airbags by mixing the respective components at room temperature for 30 minutes using a stirrer according to the blending ratios in Tables 1 and 2.

[0194] <Method for manufacturing a silicone rubber-coated base fabric>

[0195] Using a laboratory coater (product name: LTE-S) manufactured by Mathis, blade-coat each silicone rubber coating composition for airbags prepared in Tables 1 and 2 onto a 470 denier PET base fabric at a rate of 20 g / m 2 . Then, place it in a dryer at 200 °C for 1 minute to cure the silicone rubber coating composition, thereby producing a silicone rubber-coated base fabric.

[0196] <Evaluation method for color unevenness of silicone rubber-coated base fabric>

[0197] The coating surface (25 cm × 25 cm) of the above-prepared silicone rubber-coated base fabric was visually inspected. The case where no color unevenness was found was evaluated as "qualified", and the case where color unevenness was found was evaluated as "unqualified". The evaluation results were recorded in Tables 1 and 2.

[0198] <Flame Retardancy Test Method>

[0199] The flame retardancy was evaluated according to the method described in FMVSS-302 (Federal Motor Vehicle Safety Standard-302). Specifically, each of the previously prepared silicone rubber-coated base fabrics was cut into a size of 10 cm in width and 35 cm in length. Then, with the silicone rubber coating surface facing upward, the burning distance and burning time until the flame disappeared during combustion were measured using the method described in FMVSS-302. The burning speed was calculated from the burning distance and burning time. At this time, any of the following cases was evaluated as having qualified flame retardancy: (1) the test piece did not catch fire or self-extinguished (SE) before the A marking, (2) the burning distance was within 51 mm (and within 60 seconds) and self-extinguished, (3) the burning speed was 102 mm / minute or less. The test was conducted with N = 10, and the case where all were qualified was evaluated as "qualified", and the case where any one was unqualified was evaluated as "unqualified". The results were shown in Tables 1 and 2. In addition, the self-extinguishing rate (SE rate) was calculated according to the following formula, and the results were recorded in Tables 1 and 2. Additionally, when the SE rate was high, the flame retardancy was considered to be better.

[0200] SE rate (%) = [(1) the number of test pieces that did not catch fire or self-extinguished before the A marking + (2) the number of test pieces whose burning distance was within 51 mm (and within 60 seconds) and self-extinguished / 10] × 100

[0201] [Table 1]

[0202]

[0203] [Table 2]

[0204]

[0205] As can be seen from Table 1, in Examples 1 to 7 using the addition-curable liquid silicone rubber composition for airbags of the present invention, no color unevenness occurred during coating. In addition, the results of the flame retardancy test were excellent.

[0206] On the other hand, as can be seen from Table 2, in Comparative Examples 1 to 6 that did not use the addition-curable liquid silicone rubber composition for airbags of the present invention, the results showed that the flame retardancy was worse than that of the examples or color unevenness occurred during coating.

[0207] This specification includes the following solutions.

[0208] [1]: An addition-curing liquid silicone rubber composition for an airbag, characterized by containing:

[0209] (A) An organopolysiloxane having 2 or more alkenyl groups bonded to silicon atoms in one molecule and a degree of polymerization of 50 to 2,000, which is 100 parts by mass;

[0210] (B) An organohydrogenpolysiloxane having 2 or more hydrogen atoms (hydrosilyl groups) bonded to silicon atoms in one molecule, and the amount of the hydrosilyl group contained in the composition is 1 to 10 moles relative to each total 1 mole of the alkenyl group bonded to silicon atoms contained in the composition;

[0211] (C) Silica fine powder having a BET specific surface area of 50 m 2 / g or more, which is 1 to 50 parts by mass;

[0212] (D) A catalyst for hydrosilylation reaction, which is 1 to 500 ppm in terms of the mass of the catalyst metal element relative to the mass of the component (A);

[0213] (E) An organosilicon compound having a functional group for imparting adhesiveness, which is 0.1 to 10 parts by mass; and

[0214] (F) A metal carboxylate, which is 100 to 5,000 ppm in terms of the mass of the central metal relative to the mass of the component (A).

[0215] [2]: The addition-curing liquid silicone rubber composition for an airbag according to [1], characterized in that the component (E) is an organosilicon compound having 1 or more reactive silicon groups selected from alkoxysilyl groups, alkenyl-containing silyl groups, and hydrosilyl groups and 1 or more reactive organic groups selected from epoxy groups, isocyanate groups, and (meth)acryloyl groups in one molecule.

[0216] [3]: The addition-curing liquid silicone rubber composition for an airbag according to [1] or [2], characterized in that, relative to 100 parts by mass of the component (A), it further contains 0.05 to 5 parts by mass of a condensation catalyst as the component (G), and the condensation catalyst is selected from 1 or more of organic titanium compounds, organic zirconium compounds, and organic aluminum compounds.

[0217] [4]: The addition-curing liquid silicone rubber composition for an airbag according to any one of [1] to [3], characterized in that the metal carboxylate of the component (F) is a metal salt of a carboxylic acid having 6 or more carbon atoms.

[0218] [5]: The addition-curing liquid silicone rubber composition for airbag according to any one of [1] to [4], characterized in that the central metal ion of the carboxylate metal salt of the component (F) is trivalent iron ion.

[0219] [6]: The addition-curing liquid silicone rubber composition for airbag according to any one of [1] to [5], characterized in that, based on 100 parts by mass of the component (A), 0.1 to 100 parts by mass of a powdery three-dimensional network organopolysiloxane resin as the component (H) is further contained, wherein the organopolysiloxane resin does not contain hydrogen atoms bonded to silicon atoms.

[0220] [7]: An airbag, characterized in that it has a cured coating film of the addition-curing liquid silicone rubber composition for airbag according to any one of [1] to [6] on a base fabric for airbag.

[0221] In addition, the present invention is not limited to the above embodiments. The above embodiments are illustrative, and all solutions having substantially the same composition and exhibiting the same effects as the technical concept described in the claims of the present invention are included in the technical scope of the present invention.

Claims

1. An addition-curing liquid silicone rubber composition for airbags, characterized in that, It contains: (A) 100 parts by mass of 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; (B) An organohydrogenpolysiloxane having two or more hydrogen atoms (hydrosilyl groups) bonded to silicon atoms in one molecule, in an amount such that the hydrosilyl groups contained in the composition are 1 to 10 moles relative to each total 1 mole of alkenyl groups bonded to silicon atoms contained in the composition; (C)Silica fine powder with a BET specific surface area of 50 m 2 / g or more, which is 1 to 50 parts by mass; (D) A catalyst for hydrosilylation reaction, in an amount of 1 to 500 ppm in terms of the mass of the catalyst metal element relative to the mass of the component (A); (E) 0.1 to 10 parts by mass of an organosilicon compound having a functional group for imparting adhesiveness; and (F) A metal carboxylate, in an amount of 100 to 5,000 ppm in terms of the mass of the central metal relative to the mass of the component (A).

2. The addition-curable liquid silicone rubber composition for airbag according to claim 1, wherein The component (E) is an organosilicon compound having one or more reactive silicon 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)acryloyl groups in one molecule.

3. The addition-curing liquid silicone rubber composition for airbag according to claim 1, characterized in that, Relative to 100 parts by mass of the component (A), it further contains 0.05 to 5 parts by mass of a condensation catalyst as the component (G), and the condensation catalyst is selected from one or more of organotitanium compounds, organozirconium compounds, and organoaluminum compounds.

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

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

7. An airbag, characterized in that, It has a cured coating film of the addition-curing type liquid silicone rubber composition for airbag according to any one of claims 1 to 6 on a base fabric for airbag.

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