Addition-curable liquid silicone rubber composition for airbag and airbag

Abstract

The invention provides an addition curing type liquid silicone rubber composition for an airbag. (B) a powdery three-dimensional network organopolysiloxane resin; (C) an organohydrogenpolysiloxane having two or more hydrosilyl groups in one molecule; (D) a silica micropowder having a BET-method specific surface area of 50 m2 / g or more; (E) a hydrosilylation reaction catalyst; the addition-curable liquid silicone rubber composition for an airbag contains component (C) in an amount such that the total amount of hydrogen silicon groups contained in the composition is 1-10 moles per 1 mole of the total amount of silicon atom-bonded alkenyl groups contained in the composition. The addition-curable liquid silicone rubber composition for an airbag contains an expanded graphite powder having a particle size of 1 [mu] m and a particle size of 50 [mu] m, and contains component (C) in an amount such that the total amount of hydrogen silicon groups contained in the composition is 1-10 moles per 1 mole of the total amount of silicon atom-bonded alkenyl groups contained in the composition. As a result, it is possible to provide an addition-curable liquid silicone rubber composition for an airbag, which is not susceptible to coating irregularities during coating, and which is capable of easily detecting defective products.

Description

Technical Field

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

[0002] Previously, a silicone rubber composition for airbags was proposed, the purpose of which was to form a rubber coating on the fiber surface. Airbags with silicone rubber coatings exhibit excellent internal pressure retention and low combustion velocity, making them suitable for use in automobiles and other applications.

[0003] As an addition-curing liquid silicone rubber composition for airbags, a silicone rubber composition using an organohydrogen polysiloxane containing T units or Q units as a crosslinking agent is disclosed (Patent Document 1). The coated substrate with this composition is characterized by excellent strength. Furthermore, an addition-curing liquid silicone rubber composition for airbags is also disclosed, which incorporates a silicone resin composed of M, D, and Q units, containing crosslinking functional groups only in the D units, as a flame retardant (Patent Document 2). Airbags coated with this composition are characterized by a slow burning rate.

[0004] On the other hand, in recent years, there has been a tendency to reduce the coating amount of silicone rubber compositions in order to save space and reduce weight. Therefore, it is desirable to develop a silicone rubber composition for airbags that still has the same flame retardancy as before, even with a low coating amount. As a method to improve flame retardancy, the addition of flame retardants can be considered. For example, compositions made by adding iron(III) hydrate or α-iron(III) as flame retardants to silicone rubber compositions (Patent Document 3) and compositions made by adding carbon black to silicone rubber compositions (Patent Documents 4, 5) have been disclosed. However, if flame retardants such as iron oxide or carbon black with strong coloring power are added to the silicone rubber composition, uneven coating may sometimes occur during coating, which will affect the appearance. In addition, the manufacturing process of airbag base fabric involves a large number of processes, such as weaving the base fabric, cleaning, drying, coating with silicone material, heating and curing the silicone material, and winding the coated base fabric. In these processes, if the airbag base fabric has defects such as dirt, scratches, or holes, and the silicone rubber coating on the airbag base fabric is dark in color and has strong covering power, it is sometimes difficult to detect these defects by visual inspection or by using camera image inspection.

[0005] Existing technical documents Patent documents Patent Document 1: Japanese Patent Publication No. 2019-513907 Patent Document 2: International Publication No. 2018 / 168315 Patent Document 3: Japanese Patent Application Publication No. 2022-072086 Patent Document 4: Japanese Patent Application Publication No. 7-300774 Patent Document 5: Japanese Patent Application Publication No. 7-195990 Summary of the Invention

[0006] (a) Technical problems to be solved The present invention was made in view of the above circumstances, and its purpose is to provide an addition-curing liquid silicone rubber composition for airbags and an airbag having a cured coating of the composition. The addition-curing liquid silicone rubber composition for airbags is less prone to uneven coating during application, the base fabric for airbags coated with the composition has a slow burning rate, and defects such as dirt, scratches, and holes can be easily detected.

[0007] (II) Technical Solution To address the aforementioned technical problems, the present invention provides an addition-curing liquid silicone rubber composition for airbags, characterized in that it contains: (A) A linear organopolysiloxane containing two or more alkenyl groups bonded to silicon atoms in one molecule and having a weight-average degree of polymerization of 50 to 2,000, wherein the amount is 100 parts by mass. (B) A three-dimensional network organopolysiloxane resin in powder form without hydrosilyl group, in the form of 5 to 100 parts by weight; (C) Organohydropolysiloxanes containing two or more hydrosilane groups in one molecule; (D)BET method has a specific surface area of ​​50m² 2 The silica micro powder with a density of 1 g or more is 1 to 50 parts by weight. (E) Catalyst for hydrosilylation reaction, calculated by mass conversion of catalyst metal element, is 1 to 500 ppm relative to the total mass of components (A) to (D); (F) An organosilicon compound containing adhesive functional groups, in an amount of 0.1 to 10 parts by weight; and (G) Expanded graphite powder with a median particle size of 0.1~50μm, in a quantity of 0.1~1 parts by mass. The addition-curing liquid silicone rubber composition for airbags contains the following amount of component (C): the total amount of hydrosilicone groups contained in the composition relative to the total amount of silicon-bonded alkenyl groups contained in 1 mole of the composition is 1 to 10 moles.

[0008] The silicone-coated base fabric for airbags, which has a cured coating of such an addition-curing liquid silicone rubber composition for airbags, exhibits excellent flame retardancy, is less prone to uneven coating, and can easily detect defects such as dirt, scratches, and pores.

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

[0010] If it is such an addition-curing liquid silicone rubber composition for airbags, then the silicone-coated base fabric for airbags made from it has excellent adhesion.

[0011] Furthermore, in this invention, it is preferred that the (F) component is an organosilicon compound having one or more reactive silicon groups selected from alkoxysilyl group, alkenyl-containing silicon group and hydrosilyl group in one molecule, and one or more reactive organic groups selected from epoxy group, isocyanate group and (meth)acryloyl group.

[0012] If it is an addition-curing liquid silicone rubber composition for airbags, the silicone rubber layer has better adhesion to the base fabric for airbags.

[0013] Furthermore, the present invention provides an airbag having a cured coating of the addition-cured liquid silicone rubber composition of the present invention on a base fabric for the airbag. The L value of the cured coating surface, as measured in the colorimetric system, is 60 or higher.

[0014] Such airbags are those with excellent flame retardancy, are less prone to uneven coating, and can easily detect defects such as dirt, scratches, and holes.

[0015] (III) Beneficial Effects As described above, according to the present invention, an addition-curing liquid silicone rubber composition for airbags and an airbag can be provided. The addition-curing liquid silicone rubber composition for airbags, by being coated onto a base fabric for airbags and cured, exhibits excellent flame retardancy, is less prone to uneven coating, and allows for easy detection of defective products. Detailed Implementation

[0016] The inventors of this application conducted in-depth research on the above-mentioned technical problems and found that if the composition is an addition-curing liquid silicone rubber for airbags containing expanded graphite powder, when it is coated on the base fabric for airbags and cured, the coated base fabric has excellent flame retardancy, is not prone to uneven coating, and can easily detect defects such as dirt, scratches, and holes, thus completing this invention.

[0017] That is, the present invention is an addition-curing liquid silicone rubber composition for airbags, characterized in that it contains: (A) A linear organopolysiloxane containing two or more alkenyl groups bonded to silicon atoms in one molecule and having a weight-average degree of polymerization of 50 to 2,000, wherein the amount is 100 parts by mass. (B) A powdered three-dimensional network organopolysiloxane resin without hydrosilicone groups, in the form of 5 to 100 parts by weight; (C) Organohydropolysiloxanes containing two or more hydrosilane groups in one molecule; (D)BET method has a specific surface area of ​​50m² 2 The silica micro powder with a density of 1 g or more is 1 to 50 parts by weight. (E) Catalyst for hydrosilylation reaction, calculated by mass conversion of catalyst metal element, is 1 to 500 ppm relative to the total mass of components (A) to (D); (F) An organosilicon compound containing adhesive functional groups, in an amount of 0.1 to 10 parts by weight; and (G) Expanded graphite powder with a median particle size of 0.1~50μm, in a quantity of 0.1~1 parts by mass. The addition-curing liquid silicone rubber composition for airbags contains the following amount of component (C): the total amount of hydrosilicone groups contained in the composition relative to the total amount of silicon-bonded alkenyl groups contained in 1 mole of the composition is 1 to 10 moles.

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

[0019] Furthermore, in this specification, the viscosity is a value measured at 25°C using a rotational viscometer according to the method described in Japanese Industrial Standard JIS K 7117-1:1999. Additionally, the weight-average degree of polymerization is a value calculated as the weight-average molecular weight (weight-average degree of polymerization) converted from polystyrene, measured under the following conditions, obtained by GPC (gel permeation chromatography) analysis using tetrahydrofuran (THF) as the developing solvent.

[0020] [Measurement Conditions] Developing solvent: tetrahydrofuran Flow rate: 0.35 mL / 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% by weight tetrahydrofuran solution) <Addition-curing liquid silicone rubber composition for airbags> The addition-curing liquid silicone rubber composition for airbags of the present invention is characterized by: It contains: (A) A linear organopolysiloxane containing two or more alkenyl groups bonded to silicon atoms in one molecule and having a weight-average degree of polymerization of 50 to 2,000, wherein the amount is 100 parts by mass. (B) A powdered three-dimensional network organopolysiloxane resin without hydrosilicone groups, in the form of 5 to 100 parts by weight; (C) Organohydropolysiloxanes containing two or more hydrosilane groups in one molecule; (D)BET method has a specific surface area of ​​50m² 2 The silica micro powder with a density of 1 g or more is 1 to 50 parts by weight. (E) Catalyst for hydrosilylation reaction, calculated by mass conversion of catalyst metal element, is 1 to 500 ppm relative to the total mass of components (A) to (D); (F) An organosilicon compound containing adhesive functional groups, in an amount of 0.1 to 10 parts by weight; and (G) Expanded graphite powder with a median particle size of 0.1~50μm, in a quantity of 0.1~1 parts by mass. The addition-curing liquid silicone rubber composition for airbags contains the following amount of component (C): the total amount of hydrosilicone groups contained in the composition relative to the total amount of silicon-bonded alkenyl groups contained in 1 mole of the composition is 1 to 10 moles.

[0021] The following is a detailed description of each ingredient.

[0022] [(A) ingredient] In this invention, the organopolysiloxane of component (A) is an organopolysiloxane containing two or more alkenyl groups bonded to silicon atoms in one molecule and having a degree of polymerization of 50 to 2,000. It is the base polymer (main agent) of the addition-curing liquid silicone rubber composition for airbags of this invention.

[0023] Furthermore, the molecular structure of component (A) is characterized by being linear. Preferably, it is a diorganopolysiloxane whose main chain is essentially composed of repeating diorganosiloxane units and whose ends are capped by triorganosiloxy groups. Moreover, in the linear organopolysiloxane molecule of component (A), the silicon atom bonded to the alkenyl group can be located at either or both of the molecular chain ends (i.e., triorganosiloxy groups) and the middle of the molecular chain (i.e., difunctional diorganosiloxane units located at non-molecular chain ends). Particularly preferred as component (A) is a linear diorganopolysiloxane containing at least alkenyl groups bonded to silicon atoms at both ends of the molecular chain.

[0024] The alkenyl group bonded to silicon atoms in component (A) can be, for example, an alkenyl group having 2 to 8 carbon atoms, preferably 2 to 4 carbon atoms. Specific examples include vinyl, allyl, propenyl, butenyl, pentenyl, hexenyl, cyclohexenyl, heptenyl, etc., with vinyl being particularly preferred.

[0025] (A) The number of alkenyl groups bonded to silicon atoms in a molecule is 2 or more, preferably 2 to 100, and more preferably 2 to 50.

[0026] The component (A) is a monovalent substituted or unsubstituted hydrocarbon group bonded to a silicon atom, excluding the alkenyl group. Examples of such monovalent hydrocarbon groups include those with 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; aryl groups such as phenyl, tolyl, xylyl, and naphthyl; aralkyl groups such as benzyl and phenethyl; and haloalkyl groups such as chloromethyl, 3-chloropropyl, and 3,3,3-trifluoropropyl, with methyl being particularly preferred.

[0027] (A) 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 less than 50, the physical properties of the resulting addition-curing liquid silicone rubber composition for airbags may deteriorate. Furthermore, 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 increase, and the coating operability may worsen.

[0028] The viscosity of component (A) at 25°C is preferably 50 to 200,000 mPa·s, more preferably 100 to 150,000 mPa·s, and even more preferably 400 to 100,000 mPa·s. If the viscosity of component (A) is 50 mPa·s or higher, the mechanical properties of the resulting addition-curing liquid silicone rubber composition for airbags become good. If the viscosity of component (A) is 200,000 mPa·s or lower, the viscosity of the resulting addition-curing liquid silicone rubber composition for airbags will not increase, and the coating operability is also suitable.

[0029] Specific examples of organopolysiloxanes as component (A) include dimethylsiloxane-methylvinylsiloxane copolymers with both ends of the molecular chain capped by trimethylsiloxy groups, methylvinylpolysiloxanes with both ends of the molecular chain capped by trimethylsiloxy groups, dimethylsiloxane-methylvinylsiloxane-methylphenylsiloxane copolymers with both ends of the molecular chain capped by trimethylsiloxy groups, dimethylpolysiloxanes with both ends of the molecular chain capped by dimethylvinylsiloxy groups, methylvinylpolysiloxanes with both ends of the molecular chain capped by dimethylvinylsiloxy groups, and dimethylsiloxanes with both ends of the molecular chain capped by dimethylvinylsiloxy groups. Alkyl-methylvinylsiloxane copolymers, dimethylsiloxane-methylvinylsiloxane-methylphenylsiloxane copolymers with both ends of the molecular chain capped by dimethylvinylsiloxy groups, dimethylpolysiloxanes with both ends of the molecular chain capped by divinylmethylsiloxy groups, dimethylsiloxane-methylvinylsiloxane copolymers with both ends of the molecular chain capped by divinylmethylsiloxy groups, dimethylpolysiloxanes with both ends of the molecular chain capped by trivinylsiloxy groups, dimethylsiloxane-methylvinylsiloxane copolymers with both ends of the molecular chain capped by trivinylsiloxy groups, and mixtures of two or more of these organopolysiloxanes.

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

[0031] [(B) Component] (B) The non-hydrosilicone powdered three-dimensional network organopolysiloxane resin of component (B) functions as a flame retardant improver. Component (B) is preferably composed primarily of R-type resins with trifunctionality. 1 SiO 3 / 2 Single-unit and four-functional SiO 4 / 2 It is composed of one or more branched siloxane units. It can also contain any monofunctional R as needed. 1 3SiO 1 / 2 R with one unit and / or two functions 1 2SiO 2 / 2Unit. Furthermore, this organopolysiloxane resin does not contain hydrogen atoms (hydrosilicon groups) bonded to silicon atoms in its molecule. In addition, this organopolysiloxane resin has a three-dimensional network (resin-like) structure and is in powder form at 25°C, thus clearly distinguishing it from component (A) which has a linear structure.

[0032] The above R 1 The group is independently a monovalent substituted or unsubstituted hydrocarbon group having 1 to 10 carbon atoms, preferably 1 to 8. Examples of such groups are the same as the alkenyl and monovalent hydrocarbon groups exemplified in component (A) above, including: alkyl groups such as methyl, ethyl, propyl, butyl, pentyl, hexyl, cyclohexyl, and heptyl; alkenyl groups such as vinyl, allyl, propenyl, butenyl, pentenyl, hexenyl, cyclohexenyl, and heptenyl; aryl groups such as phenyl, tolyl, xylyl, and naphthyl; aralkyl groups such as benzyl and phenethyl; and haloalkyl groups such as chloromethyl, 3-chloropropyl, and 3,3,3-trifluoropropyl, with methyl and vinyl groups being particularly preferred.

[0033] The content of alkenyl groups bonded to silicon atoms in component (B) is preferably 0 to 10 mol% relative to all substituents bonded to silicon atoms, and particularly preferably 2 to 8 mol%.

[0034] In order to form a three-dimensional network structure, the organopolysiloxane resin of component (B) can contain components selected from R. 1 SiO 3 / 2 Unit and SiO 4 / 2 One or more siloxane units in the unit. (B) In the organopolysiloxane resin, the total amount is preferably set to 20 to 75 mol%, and particularly preferably to 30 to 65 mol%. Within this range, sufficient flame retardancy improvement can be obtained, and it is therefore suitable.

[0035] Here, the organopolysiloxane resin of component (B) may, as described above, arbitrarily contain R. 1 3SiO 1 / 2 Units and / or R 1 2SiO 2 / 2 In the organopolysiloxane resin of component (B), the total content of which is preferably set to 0 to 70 mol%, and particularly preferably 0 to 50 mol%.

[0036] Furthermore, the weight-average molecular weight of the organopolysiloxane resin of component (B), as determined by GPC (gel permeation chromatography) using tetrahydrofuran (THF) as the eluent, is preferably in the range of 2,000 to 50,000, and particularly preferably 4,000 to 20,000. A weight-average molecular weight in the range of 2,000 to 50,000 provides sufficient improvement in flame retardancy and results in a viscosity suitable for application as an addition-curing liquid silicone rubber composition for airbags, exhibiting good coating operability. This weight-average molecular weight is a value obtained through GPC analysis under the same conditions as those used to determine the degree of polymerization of component (A).

[0037] Specific examples of organopolysiloxane resins as component (B) include those derived from the formula R'3SiO 1 / 2 The siloxane unit shown is similar to the formula R'2R”SiO 1 / 2 The siloxane unit shown is similar to the formula R'2SiO 2 / 2 The siloxane unit shown is similar to the formula SiO 4 / 2 The organosiloxane copolymer shown is composed of siloxane units, and is derived from the formula R'3SiO 1 / 2 The siloxane unit shown is similar to the formula R'2R''SiO 1 / 2 The siloxane unit shown is similar to the formula SiO 4 / 2 The organosiloxane copolymer shown is composed of siloxane units, and is derived from the formula R'2R''SiO 1 / 2 The siloxane unit shown is similar to the formula R'2SiO 2 / 2 The siloxane unit shown is similar to the formula SiO 4 / 2 The organosiloxane copolymer shown is composed of siloxane units, and is derived from the formula R'R''SiO 2 / 2 The siloxane unit shown is similar to the formula R'SiO 3 / 2 The siloxane unit shown or the formula R''SiO 3 / 2 The organosiloxane copolymers composed of siloxane units shown, and mixtures composed of two or more of these organopolysiloxanes.

[0038] In the above formula, R' is independently selected from alkyl groups having 1 to 10 carbon atoms, preferably 1 to 8; aryl groups having 6 to 10 carbon atoms, preferably 1 to 8; and aralkyl groups having 7 to 10 carbon atoms, preferably 7 or 8. Examples include alkyl groups such as methyl, ethyl, propyl, butyl, pentyl, hexyl, cyclohexyl, and heptyl; aryl groups such as phenyl, tolyl, xylyl, and naphthyl; aralkyl groups such as benzyl and phenethyl; and haloalkyl groups such as chloromethyl, 3-chloropropyl, and 3,3,3-trifluoropropyl, with methyl being particularly preferred. Furthermore, in the above formula, R'' is an alkenyl group having 2 to 10 carbon atoms, preferably 2 to 8. Examples include vinyl, allyl, butenyl, pentenyl, hexenyl, and heptenyl, with vinyl being particularly preferred.

[0039] The amount of component (B) is 5 to 100 parts by weight relative to 100 parts by weight of the organopolysiloxane (A), preferably 8 to 90 parts by weight, and particularly preferably 10 to 80 parts by weight. A blending amount in the range of 5 to 100 parts by weight yields sufficient improvement in flame retardancy and excellent cost-effectiveness.

[0040] (B) The three-dimensional network organopolysiloxane resin can be used alone or two or more at the same time.

[0041] [(C) Component] (C) is an organohydropolysiloxane having two or more hydrogen atoms (hydrosilicon group) bonded to silicon atoms in one molecule, which acts as a crosslinking agent for the composition.

[0042] (C) The molecular structure of the organohydrogen polysiloxane can be any of the following: linear, cyclic, branched, or three-dimensional network. In this case, it is suitable to use a substance with 2 to 300 silicon atoms (or degree of polymerization) per molecule, particularly 4 to 200, and which is liquid at 25°C. Furthermore, the number of hydrosilane 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. Additionally, the hydrosilane groups can be at the ends of the molecular chain, in the side chain (within the molecular chain), or located in both.

[0043] Substituents bonded to silicon atoms as component (C) can be, for example, monovalent substituted or unsubstituted hydrocarbon groups having 1 to 12 carbon atoms, preferably 1 to 10. Specific examples of monovalent hydrocarbon groups include: alkyl groups such as methyl, ethyl, propyl, butyl, pentyl, hexyl, cyclohexyl, and heptyl; aryl groups such as phenyl, tolyl, xylyl, and naphthyl; aralkyl groups such as benzyl and phenethyl; and haloalkyl groups such as chloromethyl, 3-chloropropyl, and 3,3,3-trifluoropropyl, with methyl or phenyl being particularly preferred.

[0044] Examples of such organohydrosiloxanes include 1,1,3,3-tetramethyldisiloxane, 1,3,5,7-tetramethylcyclotetrasiloxane, methylhydrocyclosiloxane, methylhydrosiloxane-dimethylsiloxane cyclic copolymer, tris(dimethylhydrosiloxy)methylsilane, tris(dimethylhydrosiloxy)phenylsilane, methylhydrosiloxanes end-capped with trimethylsiloxy groups, dimethylsiloxane-methylhydrosiloxane copolymers end-capped with trimethylsiloxy groups, and others. End-capped dimethyl polysiloxane, dimethylsiloxane-methylhydrosiloxane copolymers end-capped with dimethylhydrosiloxane groups, methylhydrosiloxane-diphenylsiloxane copolymers end-capped with trimethylsiloxane groups, methylhydrosiloxane-diphenylsiloxane-dimethylsiloxane copolymers end-capped with trimethylsiloxane groups, cyclic methylhydrosiloxanes, cyclic methylhydrosiloxane-dimethylsiloxane copolymers, cyclic methylhydrosiloxane-diphenylsiloxane-dimethylsiloxane copolymers, and (CH3)2HSiO 1 / 2 Unit and SiO 4 / 2 A copolymer composed of units, consisting of (CH3)2HSiO 1 / 2 Unit and SiO 4 / 2 Unit and (C6H5)SiO 3 / 2 These include copolymers composed of unit cells, or organohydrogen polysiloxanes formed by replacing some or all of the methyl groups in the above-described compounds with other alkyl groups such as ethyl or propyl, or aryl groups such as phenyl. Furthermore, compounds with the following structural formulas can be specifically exemplified as such organohydrogen polysiloxanes.

[0045] [Chemical Formula 1] In the formula, e is an integer from 2 to 200, and f, g, and h are integers from 0 to 200.

[0046] The viscosity of this organohydrogen polysiloxane at 25°C is preferably 0.5 to 10,000 mPa·s, and particularly preferably 1 to 300 mPa·s.

[0047] The amount of component (C) is such that the total amount of hydrosilicone groups contained in the composition of the present invention is 1 to 10 moles relative to the total amount of silicon-bonded alkenyl groups contained in 1 mole of the composition of the present invention, preferably 1.2 to 9 moles (or units) relative to the total amount of silicon-bonded alkenyl groups contained in 1 mole of the composition of the present invention, more preferably 1.5 to 8 moles (or units) relative to the total amount of silicon-bonded alkenyl groups contained in 1 mole of the composition of the present invention. If the amount of hydrosilicone groups contained in the composition containing component (C) is less than 1 mole relative to the total amount of silicon-bonded alkenyl groups contained in 1 mole of components (A) and (B), the addition-curing liquid silicone rubber composition for airbags cannot be sufficiently cured. Furthermore, if it is greater than 10 moles, the cured silicone rubber obtained from the addition-curing liquid silicone rubber composition for airbags sometimes has extremely poor heat resistance.

[0048] (C) The organohydrogen polysiloxane component can be used alone or in combination with two or more components.

[0049] [(D) component] (D) The specific surface area of ​​component BET method is 50 m². 2 Silica micropowder at a concentration of 1 g or higher functions as a reinforcing filler. Specifically, it imparts strength to the cured silicone rubber obtained from the addition-curing liquid silicone rubber composition for airbags of the present invention. Therefore, by using silica micropowder as a reinforcing filler, a coating film with the required strength according to the present invention can be formed. The silica micropowder has a specific surface area of ​​50 m² obtained by the BET method. 2 / g or more, preferably 50~400m 2 / g, more preferably 100~300m 2 / g. Specific surface area less than 50m² 2 At a concentration of / g, it is impossible to impart satisfactory mechanical strength properties as a coating agent for use in airbags.

[0050] Such silica micropowder can be a known substance that has been used as a reinforcing filler for silicone rubber curing, with a specific surface area within the above-mentioned range as a condition. Examples include fumed silica (gas phase silica) and precipitated silica (wet silica).

[0051] The aforementioned silica micropowder can be made from silica micropowder whose surface has been hydrophobically treated using surface treatment agents such as chlorosilanes, alkoxysilanes, organosilazanes, etc. (usually hydrolyzable) organosilicon compounds. In this case, these silica micropowders can be substances that have undergone surface hydrophobic treatment directly using a surface treatment agent in a pre-powder state. Alternatively, substances that have undergone surface hydrophobic treatment by adding a surface treatment agent during kneading with silicone oil (e.g., an alkenyl-containing organopolysiloxane of component (A) above in oil form) can also be used.

[0052] As a treatment method for component (D), surface treatment can be performed using known techniques. For example, the aforementioned untreated silica micropowder and surface treatment agent can be added to a closed mechanical kneading device or fluidized bed device under normal pressure, and kneading can be performed at room temperature (25°C) or under heat treatment (heating) in the presence of an inactive gas, as needed. Depending on the circumstances, water or a catalyst (hydrolysis accelerator, etc.) can be used to promote surface treatment. After kneading, drying is performed, thereby producing surface-treated silica micropowder. The amount of surface treatment agent added only needs to be greater than or equal to the amount calculated from the coverage area of ​​the surface treatment agent.

[0053] 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, vinyltri(methoxyethoxy)silane, trimethylchlorosilane, dimethyldichlorosilane, divinyldimethoxysilane, and chloropropyltrimethoxysilane; polymethylsiloxane, organohydrogen polysiloxane, etc. These surface treatment agents can be used to perform surface treatment to produce hydrophobic silica micropowder for use. Silane coupling agents or silazanes are particularly preferred as surface treatment agents.

[0054] Furthermore, when the silica micropowder of component (D) is used as a substance that has undergone direct surface hydrophobication treatment in a powder state using a surface treatment agent containing alkenes, the amount of hydrosilicon groups contained in the composition containing component (C) relative to the total number of alkenes bonded to silicon atoms contained in 1 mole (or one) of the surface treatment agent containing components (A), (B), and (D) is preferably 1 to 10 moles (or ones). The amount of silicon-based alkenyl groups bonded to silicon atoms in a composition comprising 1 mole (or one) of a surface treatment agent comprising components (A), (B), and (D) is 1.2 to 8 moles (or ones), more preferably, the amount of hydrosilicon-based alkenyl groups in a composition comprising component (C) is 1.5 to 6 moles (or ones) in a composition comprising a surface treatment agent comprising components (A), (B), and (D) is 1 mole (or one).

[0055] This is because, relative to 1 mole of alkenyl groups bonded to silicon atoms in an addition-curing liquid silicone rubber composition for airbags, if the number of hydrosilyl groups is less than 1 mole, the addition-curing liquid silicone rubber composition for airbags cannot be fully cured and sometimes cannot exhibit sufficient adhesive strength. On the other hand, if the number of hydrosilyl groups is greater than 10 moles, the heat resistance of the cured silicone rubber obtained from the addition-curing liquid silicone rubber composition for airbags becomes extremely poor.

[0056] The amount of component (D) is 1 to 50 parts by mass relative to 100 parts by mass of the organopolysiloxane of component (A), preferably 3 to 30 parts by mass, and more preferably 5 to 25 parts by mass. If the amount of component (D) is less than 1 part by mass, a silicone rubber cured product with sufficient strength cannot be obtained. If the amount of component (D) is greater than 50 parts by mass, the viscosity of the resulting addition-curing liquid silicone rubber composition for airbags may increase, the fluidity may decrease, and the coating operability may deteriorate.

[0057] (D) Silica micropowder can be used alone or in combination with two or more.

[0058] [(E) component] The catalyst used for the hydrosilylation reaction of component (E) mainly promotes the addition reaction between the alkenyl groups bonded to silicon atoms in components (A) and (B) and the hydrosilane groups in component (C). The catalyst for this hydrosilylation reaction is not particularly limited, and examples include: platinum group metals such as platinum, palladium, and rhodium; chloroplatinic acid; alcohol-modified chloroplatinic acid; coordination compounds of chloroplatinic acid with olefins, vinylsiloxanes, or acetylene compounds; platinum group metal compounds such as tetra(triphenylphosphine)palladium and tri(triphenylphosphine)rhodium chloride, etc., with platinum group metal compounds being preferred.

[0059] Based on the mass conversion of the catalyst metal element, the amount of component (E) incorporating is 1 to 500 ppm, preferably 5 to 100 ppm, relative to the total mass of components (A) to (D). If the amount of component (E) is less than 1 ppm, the addition reaction will be significantly slowed down or the addition-curing liquid silicone rubber composition used in airbags will not be cured, so it is not preferred. If the amount of component (E) is greater than 500 ppm, the heat resistance of the cured silicone rubber may decrease.

[0060] (E) The catalyst used for the hydrosilylation reaction of component (E) can be a single catalyst or two or more catalysts can be used simultaneously.

[0061] [(F)INGREDIENT] (F) is an organosilicon compound with adhesive functional groups, which is added to improve the adhesion of the addition-curing liquid silicone rubber composition for airbags to the base fabric for airbags.

[0062] (F) Any material can be used as long as it is an organosilicon compound with adhesive functional groups, but it is preferred to be an organosilicon compound having one or more reactive silicon groups selected from alkoxysilyl, alkenyl-containing silicon and hydrosilyl groups and one or more reactive organic groups selected from epoxy, isocyanate and (meth)acryloyl groups in one molecule.

[0063] Regarding the alkoxy group (alkoxysilyl group) bonded to the silicon atom, it is preferable to form, for example, a trimethoxysilyl group, a triethoxysilyl group, etc.; or an alkyldialkoxysilyl group, such as a methyldimethoxysilyl group, an ethyldimethoxysilyl group, a methyldiethoxysilyl group, an ethyldiethoxysilyl group, etc., bonded to the silicon atom. The epoxy group is preferably bonded to the silicon atom in the form of, for example, a glycidyl etheroxyalkyl group, such as a glycidyl etheroxypropyl group, or a cyclohexylalkyl group containing an epoxy group, such as a 2,3-epoxycyclohexylethyl group, or a 3,4-epoxycyclohexylethyl group.

[0064] Organosilicon compounds that are components of (F) include, for example, γ-glycidyl etheroxypropyltriethoxysilane, γ-glycidyl etheroxypropylmethyldiethoxysilane, (3,4-epoxycyclohexylethyl)trimethoxysilane, (3,4-epoxycyclohexylethyl)triethoxysilane, (3,4-epoxycyclohexylethyl)methyldimethoxysilane, (3,4-epoxycyclohexylethyl)methyldiethoxysilane, (2,3-epoxycyclohexylethyl)triethoxysilane, (2,3-epoxycyclohexylethyl)methyldimethoxysilane, and other epoxy-containing silanes. Coupling agents (i.e., organoalkoxysilanes containing epoxy functional groups); or silane coupling agents containing (meth)acryloyl groups, such as 3-acryloyloxypropyltrimethoxysilane and 3-methacryloyloxypropyltrimethoxysilane; or silane coupling agents containing isocyanate groups, such as 3-isocyanate-propyltriethoxysilane and 3-isocyanate-propyltrimethoxysilane; or cyclic organopolysiloxanes containing epoxy groups represented by the following chemical formulas; or organosilicon compounds such as linear organopolysiloxanes containing epoxy groups; mixtures of two or more of the above organosilicon compounds; or partially hydrolyzed condensates of one or more of the above organosilicon compounds.

[0065] The main compounds are exemplified below.

[0066] [Chemical Formula 2] In the formula, p is an integer from 1 to 40, q is an integer from 0 to 40, and r is an integer from 1 to 40, preferably an integer from 1 to 20.

[0067] The amount of component (F) is 0.1 to 10 parts by weight relative to 100 parts by weight of the organopolysiloxane of component (A), preferably 0.15 to 5 parts by weight. If the amount of component (F) is less than 0.1 parts by weight, the resulting addition-curing liquid silicone rubber composition for airbags may not exhibit sufficient adhesive strength. If the amount of component (F) is greater than 10 parts by weight, the addition-curing liquid silicone rubber composition for airbags may exhibit increased thixotropy, decreased fluidity, and poor coating operability.

[0068] Furthermore, when component (F) contains alkenyl and / or hydrosilyl groups, component (F) is an amount in which the total amount of hydrosilyl groups contained in the composition containing components (C) and (F) is 1 to 10 moles (or units) of alkenyl groups bonded to silicon atoms contained in 1 mole (or unit) of the composition containing components (A), (B), (D), and (F), preferably such that the total amount of hydrosilyl groups contained in the composition containing components (C) and (F) is 1 to 10 moles (or units) of the composition containing components (C) and (F). The total amount of alkenyl groups bonded to silicon atoms contained in the composition comprising components (A), (B), (D), and (F) is 1.2 to 8 moles (or units), more preferably, the total amount of hydrosilane groups contained in the composition comprising components (C) and (F) is 1.5 to 6 moles (or units) relative to the total amount of alkenyl groups bonded to silicon atoms contained in 1 mole (or unit) of the composition comprising components (A), (B), (D), and (F).

[0069] This is because, relative to 1 mole of alkenyl groups bonded to silicon atoms in an addition-curing liquid silicone rubber composition for airbags, if the number of hydrosilyl groups is less than 1 mole, the addition-curing liquid silicone rubber composition for airbags cannot be fully cured and sometimes cannot exhibit sufficient adhesive strength. On the other hand, if the number of hydrosilyl groups is greater than 10 moles, the heat resistance of the cured silicone rubber obtained from the addition-curing liquid silicone rubber composition for airbags can sometimes be extremely poor.

[0070] (F) Components can be used alone or in combination with two or more.

[0071] [(G) component] Component (G) is expanded graphite powder, which functions as a flame retardant improver. Expanded graphite powder refers to a substance obtained by embedding reagents such as sulfuric acid into the interlayer of graphite powder, such as flake graphite, and then heating to vaporize the reagents, thereby expanding the interlayer of the graphite and pulverizing it into powder. Conventional methods can be used for pulverization, such as bead milling, jet milling, roller milling, ball milling, disc milling, and hammer milling of expanded graphite sheets formed by dry forming. Furthermore, the graphite powder refers to a substance that has been calcined at an ultra-high temperature of 2,000~3,000℃ under air-isolated conditions to remove impurities and increase the crystallization rate, which is significantly different from carbon black.

[0072] The volume average particle size D50 of the expanded graphite powder obtained by laser diffraction scattering is preferably 0.1~50 μm, more preferably 0.5~40 μm, and even more preferably 1~30 μm. If the median particle size is less than 0.1 μm, the thixotropic properties of the composition may become high and the coating workability may become poor. If the median particle size is greater than 50 μm, it may sometimes cause uneven coating when coated on a base fabric.

[0073] The amount of component (G) is 0.1 to 1 part by weight relative to 100 parts by weight of the organopolysiloxane of component (A), preferably 0.25 to 1 part by weight. If the amount of component (G) is less than 0.1 parts by weight, sufficient improvement in flame retardancy may not be achieved. Furthermore, if the amount of component (G) is greater than 1 part by weight, the black color of the addition-curing liquid silicone rubber composition used in airbags becomes stronger, and the brightness of the silicone-coated base fabric decreases. Therefore, it may be difficult to detect defective products during the inspection process after the airbag base fabric is manufactured.

[0074] (G) Components can be used alone or in combination with two or more.

[0075] [Other ingredients] In the addition-curing liquid silicone rubber composition for airbags of the present invention, in addition to components (A) to (G) described above, any other components may be incorporated according to the purpose. Specific examples include the following components. These other components may be used individually or in combination with two or more components.

[0076] [(H) component] Furthermore, the catalyst may contain one or more condensation catalysts selected from organotitanium compounds, organozirconium compounds, and organoaluminum compounds as component (H). Preferably, component (H) is selected from one or more titanium alkoxide complexes, titanium chelate complexes, zirconium alkoxide complexes, and zirconium chelate complexes, which function as condensation catalysts that impart adhesive functional groups in component (F) to promote adhesion.

[0077] Specific examples of (H) components include: titanium alkoxide complexes such as isopropyl phthalate, n-butyl phthalate, and tetra(2-ethylhexanol)titanium; titanium chelate complexes such as di(acetylacetonyl)titanium diisopropyl phthalate, bis(ethyl acetoacetate)titanium diisopropyl phthalate, and tetra(acetylacetonyl)titanium; zirconium alkoxide complexes such as zirconium n-propoxide and zirconium n-butoxide; and zirconium chelate complexes such as zirconium tributoxymonoacetylacetonate, zirconium monobutoxyacetylacetonate bis(ethylacetoacetate), and zirconium acetylacetonate.

[0078] The condensation catalyst selected from one or more organotitanium compounds, organozirconium compounds, and organoaluminum compounds in component (H) is any component that is incorporated as needed. The amount incorporated relative to 100 parts by mass of component (A) is preferably 0.05 to 5 parts by mass, more preferably 0.1 to 5 parts by mass, and particularly preferably 0.08 to 2 parts by mass. When the amount incorporated 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 exhibits excellent adhesion to the base fabric used in airbags.

[0079] (H) Component can be used alone or in combination with two or more components.

[0080] [Reaction control agent] The reaction control agent is not particularly limited to any compound that has a curing inhibition effect on the catalyst used in the hydrosilylation reaction of component (E), and any known reaction control agent can be used. Specific examples include: phosphorus-containing compounds such as triphenylphosphine; nitrogen-containing compounds such as tributylamine, tetramethylethylenediamine, and benzotriazole; sulfur-containing compounds; acetylene compounds such as alkynols; compounds containing two or more alkenyl groups; hydroperoxides; maleic acid derivatives, etc.

[0081] The degree of curing inhibition effect brought about by the reaction control agent varies depending on the chemical structure of the reaction control agent. Therefore, the amount of reaction control agent added should preferably be adjusted to the optimal amount for the various reaction control agents used. By adding the optimal amount of reaction control agent, the addition-curing liquid silicone rubber composition for airbags exhibits excellent long-term storage stability and curing properties at room temperature.

[0082] [Non-reinforcing filler] As fillers other than silica micropowder of component (D) and expanded graphite powder of component (G), examples include: crystalline silica (e.g., with a specific surface area of ​​less than 50 m² obtained by the BET method). 2 / g quartz powder), hollow fillers made of organic resin, polymethylsilsesquioxane microparticles (so-called silicone resin powder), fumed titanium dioxide, magnesium oxide, zinc oxide, aluminum hydroxide, magnesium carbonate, calcium carbonate, zinc carbonate, diatomaceous earth, talc, glass fiber and other fillers; fillers made by surface hydrophobication treatment of these fillers using organosilicon compounds such as organoalkoxysilane compounds, organochlorosilane compounds, organosilazane compounds, low molecular weight siloxane compounds, etc.; silicone rubber powder; silicone resin powder, etc.

[0083] [Other ingredients] In addition, it can also be incorporated with, for example, organopolysiloxanes containing one hydrogen atom bonded to a silicon atom in one molecule and no other functional groups, organopolysiloxanes containing one alkenyl group bonded to a silicon atom in one molecule and no other functional groups, non-functional organopolysiloxanes (so-called dimethyl silicone oil) that do not contain hydrogen atoms bonded to silicon atoms, alkenyl groups bonded to silicon atoms and no other functional groups, organic solvents, creep-hardening inhibitors, plasticizers, thixotropic agents, pigments, dyes, antifungal agents, etc.

[0084] <Preparation of Addition-Curing Liquid Silicone Rubber Compositions for Airbags> By mixing the above components (A) to (G) and component (H), and other components to be further blended as needed, until homogeneous, an addition-curing liquid silicone rubber composition for airbags can be prepared.

[0085] The addition-curing liquid silicone rubber composition obtained thus for airbags is a liquid composition at 25°C, and its viscosity at 25°C is preferably 1~500 Pa·s, more preferably 2~400 Pa·s, and even more preferably 5~300 Pa·s. If the viscosity is within the above-mentioned viscosity range at 25°C, it is less likely to cause uneven coating and insufficient adhesion to the base fabric after curing when coated on the base fabric for airbags, and therefore can be used appropriately.

[0086] <Base fabric for airbags> Typically, the base fabric (a substrate made of fiber cloth) used for airbags to form the silicone rubber layer can be any known base fabric for airbags. 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).

[0087] <Airbag> The airbag of the present invention is characterized in that it has a cured coating of the addition-cured liquid silicone rubber composition for airbags described above on a base fabric for the airbag. The L value of the cured coating surface, as measured in the colorimetric system, is 60 or higher.

[0088] Because the airbag of the present invention uses expanded graphite powder ((G) component) as a flame retardant improver, the addition-curing liquid silicone rubber composition used in the airbag has a weak black color and the silicone-coated base fabric has a high brightness, making it easy to detect defective products in the inspection process after the airbag base fabric is manufactured.

[0089] Regarding the airbag of the present invention, the L-value of the silicone-coated surface of the aforementioned silicone-coated base fabric was measured using a spectrophotometer CM-700d (manufactured by Konica Minolta, Inc.). Furthermore, the L-value is... Values ​​measured in the colorimetric system.

[0090] <Manufacturing Method of Airbags> The addition-curing liquid silicone rubber composition for airbags described above is applied to one or both sides of a base fabric (a substrate made of fiber cloth) for airbags, particularly to one side only, and then cured by heating in a drying oven or the like, thereby forming a silicone rubber layer (cured film). Airbags can then be manufactured using the silicone rubber-coated base fabric for airbags obtained in this way.

[0091] Here, as a method for coating an addition-curing liquid silicone rubber composition for airbags onto a base fabric for airbags, conventional methods can be used, but coating with a blade coater is preferred. The coating thickness (or surface coating weight) can typically be set to 5~100 g / m². 2 The preferred setting is 8~90g / m 2 More preferably, it is set to 10~80g / m 2 .

[0092] The addition-curing liquid silicone rubber composition for use in airbags can be cured under known curing conditions and by known curing methods. Specifically, for example, the composition can be cured by heating at 100-200°C for 1-30 minutes.

[0093] When processing a base fabric for airbags (a silicone rubber-coated base fabric for airbags) with silicone rubber layers on one or both sides into an airbag, one method is to make the silicone rubber-coated side the inner side, adhere the outer peripheries of two pieces of the aforementioned silicone rubber-coated base fabric for airbags to each other using an adhesive, and then sew the adhesive layer together. Alternatively, a method can be used whereby an addition-curing liquid silicone rubber composition for airbags is applied to both outer sides of the base fabric for airbags, which has been pre-woven, at a predetermined amount, as described above, and then cured under predetermined curing conditions. Furthermore, while known adhesives can be used, silicone-based adhesives known as sealants are suitable for applications considering adhesion strength and durability.

[0094] Example The following describes the preparation examples, embodiments, and comparative examples to specifically illustrate the present invention, but the present invention is not limited to the following embodiments. Furthermore, the viscosity, weight-average molecular weight (weight-average overlap), and median particle size described below are values ​​obtained using the above conditions.

[0095] As component (A), the following components are used.

[0096] (A-1): A linear dimethyl polysiloxane with a molecular chain end capped by vinyl dimethylsiloxy groups, a weight-average degree of polymerization of 750, and a viscosity of 30,000 mPa·s. (A-2): A linear dimethyl polysiloxane with a molecular chain end capped by vinyl dimethylsiloxy groups, a weight-average degree of polymerization of 450, and a viscosity of 5,000 mPa·s. (A-3): A linear dimethyl polysiloxane with a molecular chain end capped by vinyl dimethylsiloxy groups, a weight-average degree of polymerization of 200, and a viscosity of 1,000 mPa·s. As component (B), the following components are used.

[0097] (B): Composed of (CH3)3SiO 1 / 2 Unit and (CH3)(CH2=CH)SiO 2 / 2 Unit and SiO 4 / 2 A powdered, three-dimensional network organopolysiloxane resin with a unit composition, 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. As component (C), the following components are used.

[0098] (C): A linear dimethylsiloxane-methylhydrosiloxane copolymer with a molecular chain end capped by trimethylsiloxy groups, a weight-average degree of polymerization of 20, an average of 9 hydrosiloxane groups per molecule, and a viscosity of 8 mPa·s (hydrosiloxane content: 0.0089 mol / g). As component (D), the following components are used.

[0099] (D): The specific surface area obtained using the BET method is 300 m². 2 / g of silica micropowder (trade name: Aerosil300, manufactured by NIPPON AEROSIL CO., LTD.) As component (E), the following components are used.

[0100] (E): A dimethyl polysiloxane solution containing 1% by mass of a chloroplatinic acid / 1,3-divinyltetramethyldisiloxane complex, based on platinum atomic content. As component (F), the following components are used.

[0101] (F): γ-glycidyl etheroxypropyltrimethoxysilane As component (G), the following components are used.

[0102] (G-1): Expanded graphite powder (trade name: CS-5, manufactured by MARUTOYO Co., Ltd., median particle size: 7μm), conforming to the present invention. (G-2): Flake graphite powder (trade name: MT-4, manufactured by MARUTOYO Co., Ltd., median particle size: 4μm), does not conform to the present invention. (G-3): Carbon fiber (trade name: XN-500, manufactured by Nippon Graphite Fiber Co., Ltd., average length: 50μm), does not conform to this invention. (G-4): Diamond powder (trade name: BRM, manufactured by Besco Superrabrasives, median particle size: 10 μm), does not conform to the present invention. (G-5): Carbon black (trade name: Denka Black, manufactured by Denka Company Limited, median particle size: 0.35 μm), does not conform to this invention. The following components are used as component (H).

[0103] (H): Zirconium acetylacetonate (trade name: ZC-162, manufactured by Matsumoto Fine Chemical Co., Ltd.) The following components are used as reaction control agents.

[0104] (Reaction control agent): 1-Ethynylcyclohexanol [Preparation Example 1] Add 60 parts by weight of base oil (A-1), 8 parts by weight of hexamethyldisilazane, 2 parts by weight of water, and 40 parts by weight of silica powder (D) to a kneader and mix for 1 hour at room temperature. Then, add another 8 parts by weight of hexamethyldisilazane and mix for 1 hour at room temperature. Next, raise the temperature to 150°C and continue mixing for 2 hours. Then, add 30 parts by weight of base oil (A-1) and mix until homogeneous to obtain the basic mixture.

[0105] [Examples 1-5 and Comparative Examples 1-7] According to the mixing ratios in Tables 1 and 2, the components were mixed for 30 minutes at room temperature using a mixer to prepare an addition-curing liquid silicone rubber composition for airbags.

[0106] [Table 1] [Table 2] <Method for manufacturing silicone rubber coated base fabric> Using Mathis's laboratory coating machine (product name: LTE-S), a coating of 20 g / m³ was achieved. 2 The silicone rubber coating compositions for airbags prepared in Tables 1 and 2 were applied to a 210 denier PA66 base fabric using a scraper. The mixtures were then placed in a dryer at 200°C for 1 minute to cure the silicone rubber coating compositions, thereby producing the silicone rubber coated base fabric.

[0107] <Flame Retardancy Test Method> Flame retardancy was evaluated using the method described in FMVSS-302 (Federal Motor Vehicle Safety Standard-302). Specifically, each previously prepared silicone rubber coated substrate was cut to a size of 10 cm wide × 35 cm long. Then, with the silicone rubber coated side facing up, the burning distance and burning time until the flame was extinguished were measured using the method described in FMVSS-302. The burning rate was calculated from the burning distance and burning time. At this time, any of the following conditions were evaluated as acceptable for flame retardancy: (1) the test piece did not ignite or self-extinguished before the A mark (SE), (2) self-extinguished within a burning distance of 51 mm (and within 60 seconds), (3) the burning rate was less than 102 mm / min. The test was conducted with N=10, and all acceptable cases were evaluated as "acceptable", and even if only one case was unacceptable, it was evaluated as "unacceptable". The results are shown in Tables 1 and 2. Furthermore, the self-extinguishing rate (SE rate) was calculated using the following formula, and the results are recorded in Tables 1 and 2. Additionally, it is believed that a higher SE rate indicates better flame retardancy.

[0108] SE rate (%) = [((1) Number of test pieces that did not ignite or self-extinguished before the A mark + (2) Number of test pieces that self-extinguished within a 51mm burning distance (and within 60 seconds) / 10] × 100 <Method for determining the L value using a colorimeter> The L-value of the silicone-coated surface of the prepared silicone rubber-coated substrate was measured using a spectrophotometer CM-700d (manufactured by Konica Minolta, Inc.). Intermediate values ​​measured at N=3 are shown in Tables 1 and 2. Additionally, the L-value is... Values ​​measured in the colorimetric system.

[0109] As shown in Table 1, the flame retardancy test results of Examples 1-5, which used the addition-curing liquid silicone rubber composition for airbags of the present invention, were excellent. Furthermore, the L values, indicating lightness, obtained using a colorimeter, were high.

[0110] On the other hand, as shown in Table 2, although the powder with carbon as the main component, the same as that used in expanded graphite, was used, the flame retardancy of Comparative Examples 1 to 7 was worse than that of the Examples, or the L value indicating lightness obtained by the colorimeter was low.

[0111] Thus, in this invention, the curing coating surface of the airbag has a high brightness (L value), and the silicone-coated base fabric has a higher brightness, making it easier to detect defective products during the inspection process after the airbag base fabric is manufactured.

[0112] This manual includes the following solutions.

[0113] [1] An addition-curing liquid silicone rubber composition for use in airbags, characterized in that it contains: (A) A linear organopolysiloxane containing two or more alkenyl groups bonded to silicon atoms in one molecule and having a degree of polymerization of 50 to 2,000, wherein the amount is 100 parts by mass. (B) A powdered three-dimensional network organopolysiloxane resin without hydrosilicone groups, in the form of 5 to 100 parts by weight; (C) Organohydropolysiloxanes containing two or more hydrosilane groups in one molecule; (D)BET method has a specific surface area of ​​50m² 2 The silica micro powder with a density of 1 g or more is 1 to 50 parts by weight. (E) Catalyst for hydrosilylation reaction, calculated by mass conversion of catalyst metal element, is 1 to 500 ppm relative to the total mass of components (A) to (D); (F) An organosilicon compound containing adhesive functional groups, in an amount of 0.1 to 10 parts by weight; and (G) Expanded graphite powder with a median particle size of 0.1~50μm, in a quantity of 0.1~1 parts by mass. The addition-curing liquid silicone rubber composition for airbags contains the following amount of component (C): the total amount of hydrogen alkyl groups contained in the composition relative to the total amount of silicon-bonded alkenyl groups contained in each mole of the composition is 1 to 10 moles.

[0114] [2] The addition-curing liquid silicone rubber composition for airbags according to [1] is characterized in that, relative to 100 parts by weight of the (A) component, it further contains 0.05 to 5 parts by weight of the (H) component, wherein the (H) component is one or more condensation catalysts selected from organotitanium compounds, organozirconium compounds and organoaluminum compounds.

[0115] [3] The addition-curing liquid silicone rubber composition for airbags according to [1] or [2] is characterized in that the (F) component is an organosilicon compound having in one molecule one or more reactive silicone groups selected from alkoxysilyl, alkenyl-containing silicone and hydrosilyl groups and one or more reactive organic groups selected from epoxy, isocyanate and (meth)acryloyl groups.

[0116] [4] An airbag, characterized in that it has a cured coating of the addition-curing liquid silicone rubber composition for airbags as described in any one of [1] to [3] on a base fabric for the airbag, in The L value of the cured coating surface, as measured in the colorimetric system, is 60 or higher.

[0117] Furthermore, this invention is not limited to the above embodiments. The above embodiments are illustrative examples, and any technical solutions having a substantially identical structure and achieving the same effect as the technical concept described in the claims of this invention are included within the scope of protection of this invention.

Claims

1. An addition-curing liquid silicone rubber composition for use in airbags, characterized in that, It contains: (A) A linear organopolysiloxane containing two or more alkenyl groups bonded to silicon atoms in one molecule and having a weight-average degree of polymerization of 50 to 2,000, wherein the amount is 100 parts by mass. (B) A powdered three-dimensional network organopolysiloxane resin without hydrosilicone groups, in the form of 5 to 100 parts by weight; (C) Organohydropolysiloxanes containing two or more hydrosilane groups in one molecule; (D)BET method has a specific surface area of ​​50m² 2 The silica micro powder with a density of 1 g or more is 1 to 50 parts by weight. (E) Catalyst for hydrosilylation reaction, calculated by mass conversion of catalyst metal element, is 1 to 500 ppm relative to the total mass of components (A) to (D); (F) An organosilicon compound containing adhesive functional groups, in an amount of 0.1 to 10 parts by weight; and (G) Expanded graphite powder with a median particle size of 0.1~50μm, in a quantity of 0.1~1 parts by mass. The addition-curing liquid silicone rubber composition for airbags contains the following amount of component (C): the total amount of hydrosilicone groups contained in the composition relative to the total amount of silicon-bonded alkenyl groups contained in 1 mole of the composition is 1 to 10 moles.

2. The addition-curing liquid silicone rubber composition for airbags according to claim 1, characterized in that, The product further contains 0.05 to 5 parts by mass of component (H) relative to 100 parts by mass of component (A), wherein component (H) is one or more condensation catalysts selected from organotitanium compounds, organozirconium compounds and organoaluminum compounds.

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

4. An airbag, characterized in that, It has a cured coating of the addition-curing liquid silicone rubber composition for airbags as described in any one of claims 1 to 3 on the base fabric for the airbag, in The L value of the cured coating surface, as measured in the colorimetric system, is 60 or higher.

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