JP7766577B2 - Airbag base fabric - Google Patents

Description

The present invention relates to a base fabric for airbags.

Airbag fabrics have been proposed in which a silicone rubber composition is coated on the surface of a fiber base fabric to form a hardened rubber coating. Curtain airbags made from silicone-coated base fabrics can prevent inflator gas from leaking when the airbag is inflated. This makes them excellent at retaining internal pressure, making them ideal for use in airbags for automobiles, etc.

As a method for manufacturing airbag fabric, for example, Patent Document 1 discloses a method for manufacturing a silicone-coated airbag fabric with excellent internal pressure retention. In this method, an addition-cure liquid silicone rubber composition is first prepared by combining a crosslinking agent having hydrosilyl groups at both molecular chain ends with another crosslinking agent having hydrosilyl groups in the side chain, and blending in a silane coupling agent as an adhesion aid. The composition is then coated onto the fabric and heat-cured to produce the silicone-coated airbag fabric.

Airbag fabrics manufactured using this method have the base fabric and silicone rubber coating layer chemically and firmly bonded together by the adhesive aid. This makes it difficult to separate the base fabric from the silicone rubber coating layer, posing a problem in that the base fabric and silicone rubber are difficult to recycle.

In addition, a method for manufacturing airbag base fabrics has been disclosed in which a multilayer film laminated with polyamide and modified polyethylene is adhered to the base fabric with an adhesive layer containing a copolymerized polyamide, an antiblocking agent, and a crystal nucleating agent, resulting in a base fabric with a low dynamic friction coefficient and reduced wrinkles when rolled up (Patent Document 2).

Airbag fabrics manufactured using this method require laminating and bonding various types of resins, including polyamide, modified polyethylene, copolymer polyamide, and the fabric. It is not easy to separate the resins from this laminate.

In addition, a base fabric for airbags has been disclosed that uses a double-bag structure consisting of a woven outer bag and a woven inner bag, which controls internal pressure and stably supports the driver when the airbag deploys (Patent Document 3).

Airbag fabrics manufactured using this method are sufficiently airtight for front airbags, but are unsuitable for curtain airbags or side airbags, which need to inflate for several to several tens of seconds.

Furthermore, a base fabric for airbags has been disclosed that has a double-bag structure consisting of an outer bag made of woven fabric made of thermoplastic resin and an inner bag made of thermoplastic resin, with vent holes in the inner bag that allow for control of internal pressure (Patent Document 4).

When airbag fabrics manufactured using the method described in Patent Document 4 are folded and stored inside a vehicle, the thermoplastic resin layers adhere to each other, which can cause a blocking phenomenon in the high temperature of the vehicle interior, potentially hindering airbag deployment. Furthermore, when the airbag is actually deployed by the inflator, sparks often fly, requiring measures to prevent sparks from burning holes in the thermoplastic resin inner bag.

Special Publication No. 2013-531695 Japanese Patent Application Laid-Open No. 2021-123296 Japanese Patent Application Laid-Open No. 2018-122798 Japanese Patent Application Publication No. 9-220995

The present invention was made in consideration of the above circumstances, and aims to provide an airbag fabric that has excellent internal pressure retention when an airbag is manufactured and is easily recyclable.

In order to solve the above problems, the present invention provides a base fabric for an airbag having a double bag structure consisting of an inner bag and an outer bag,
The inner bag is a bag-shaped molded body made of a thermosetting resin and having one or more openings,
The outer bag is made of woven fabric,
The airbag fabric is characterized in that a gap is formed between the inner bag and the outer bag.

Such airbag fabrics are highly airtight and have excellent internal pressure retention properties, as they prevent inflator gas from leaking when the airbag is inflated. Furthermore, such airbag fabrics can be easily separated by resin type and recycled even after the airbag has been deployed.

It is preferable that the area of the inner bag is 50 to 99% of the area of the outer bag.

If the size of the inner bag is 50% or more, it can expand to a sufficient size when the airbag is deployed and can play a role in absorbing the impact on the human body in the event of a vehicle collision. Furthermore, if the area is 99% or less, the inner bag can be easily placed inside the outer bag.

It is preferable that the thickness of the inner bag is 20 to 600 μm.

If the thickness of the inner bag is 20 μm or more, it will exhibit sufficient internal pressure retention, and if it is 600 μm or less, the volume will not increase when the airbag fabric is folded and stored inside the vehicle, and it will not take up too much space inside the vehicle.

It is preferable that the thermosetting resin is silicone rubber and has an elongation at break of 300% or more as measured using the method described in JIS K 6251:2017.

If the elongation at break is 300% or more, sufficient internal pressure retention can be achieved.

The silicone rubber is
(A) 100 parts by mass of an alkenyl group-containing organopolysiloxane having two or more alkenyl groups per molecule, a degree of polymerization of 100 to 10,000, and an amount of the alkenyl groups of 0.01 to 20 mol %,
(B) reinforcing silica having a specific surface area of 50 m ² /g or more: 5 to 100 parts by mass;
(C) A cured product of a silicone resin composition containing an effective amount of a curing agent is preferred.

Inner bags made of such silicone rubber can exhibit excellent long-term storage stability.

The component (C) is selected from the following (C-1) and (C-2):
(C-1) an organohydrogenpolysiloxane that is liquid at 25°C and contains two or more silicon-bonded hydrogen atoms (hydrosilyl groups) per molecule: the amount of hydrosilyl groups contained in this component is 1 to 10 moles per mole of the total silicon-bonded alkenyl groups contained in component (A);
(C-2) A catalyst for hydrosilylation reaction: the catalyst may contain an amount of catalytic metal element equivalent to 1 to 500 ppm by mass relative to the total mass of components (A) to (C).

Component (C) may be, for example, an addition reaction curing agent containing the above-mentioned components (C-1) and (C-2).

Alternatively, the component (C) is
(C-3) Organic peroxide: 0.01 to 10 parts by mass.

Component (C) may be a peroxide curing agent such as component (C-3) above.

The woven fabric of the outer bag is preferably woven from nylon 66 (PA66) or polyethylene terephthalate (PET) yarn, and the yarn preferably has a fineness of 50 to 1,000 denier.

The woven fabric for the outer bag can be any known material, such as one woven with nylon 66 (PA66) or polyethylene terephthalate (PET) yarn. Furthermore, a yarn fineness of 50 denier or more will provide sufficient strength, while a yarn fineness of 1,000 denier or less will provide sufficient flexibility and good foldability.

As described above, the airbag fabric of the present invention prevents leakage of inflator gas when the airbag is inflated, resulting in excellent internal pressure retention and easy recycling.

1 is a schematic diagram showing an example of an airbag fabric of the present invention.

As mentioned above, there was a need for the development of an airbag fabric that has excellent internal pressure retention when airbags are manufactured and is easily recyclable.

After extensive research into the above-mentioned problems, the inventors discovered that an airbag base fabric having a double-bag structure consisting of an inner bag and an outer bag, in which the inner bag is a bag-shaped molded body made of a thermosetting resin and has one or more openings, and the outer bag is formed from woven fabric with a gap between the inner and outer bags, can produce airbags that have excellent internal pressure retention when manufactured and are easy to recycle, leading to the completion of the present invention.

That is, the present invention is a base fabric for an air bag having a double bag structure consisting of an inner bag and an outer bag,
the inner bag is a bag-shaped molded body made of a thermosetting resin and having one or more openings,
The outer bag is made of woven fabric,
The airbag fabric is characterized in that there is a gap between the inner bag and the outer bag.

The present invention is described in detail below, but is not limited to these.

Figure 1 shows a schematic diagram of an example of the airbag fabric of the present invention.

The airbag fabric 1 shown in Figure 1 is a double-bagged airbag fabric consisting of an inner bag 2 and an outer bag 3.

The inner bag 2 is a bag-shaped molded body made of thermosetting resin. The inner bag 2 has one or more openings 4. The outer bag 3 is made of woven fabric. The airbag base fabric 1 also has a gap 5 between the inner bag 2 and the outer bag 3.

In the present invention, a bag-shaped molded product refers to a bag-shaped integrally molded product, and does not include a bag-shaped product made by laminating or bonding the outer edges of two films together, or a bag-shaped product made by folding a single film and laminating or bonding the opposing outer edges together.

Although only one opening 4 is shown in Figure 1, the airbag fabric 1 of the present invention can have multiple openings 4. The opening 4 is connected to an inflator. When the airbag is deployed, inflator gas generated by the inflator is introduced into the inner bag 2 through the opening 4, causing the inner bag 2 to inflate.

Such airbag fabric 1 can suppress leakage of inflator gas when the airbag is inflated, resulting in excellent internal pressure retention. In particular, the airbag fabric 1 of the present invention can provide excellent internal pressure retention even for shapes where maintaining internal pressure is difficult, such as curtain airbags and side airbags.

Furthermore, with this type of airbag base fabric 1, the inner bag 2 and outer bag 3 can be easily separated by resin type even after the airbag is deployed, making recycling easy.

Furthermore, in the airbag fabric 1 of the present invention, the inner bag 2 is made of a thermosetting resin and the outer bag 3 is formed of a woven fabric, so blocking can be prevented even when the temperature inside the vehicle becomes high. Therefore, an airbag made using the airbag fabric 1 of the present invention can be smoothly deployed by introducing inflator gas. And because the inner bag 2 is made of a thermosetting resin, there is no need to worry about it being punctured by sparks.

The present invention will be described in more detail below. In this specification, the degree of polymerization is determined as the weight-average degree of polymerization (weight-average molecular weight) converted into polystyrene by gel permeation chromatography (GPC) analysis using toluene as the developing solvent.

[Inner bag]
<Thermosetting resin used in the inner bag>
The inner bag of the airbag fabric of the present invention is preferably a thermosetting resin, and in particular a silicone rubber having an elongation at break of 300% or more as measured by the method described in JIS K 6251: 2017. If the elongation at break is 300% or more, sufficient internal pressure retention can be achieved.

The thermosetting resin used in the present invention is preferably a silicone rubber, which is a cured product of a silicone resin composition containing the following components (A) to (C):
(A) 100 parts by mass of an alkenyl group-containing organopolysiloxane having two or more alkenyl groups in one molecule and a degree of polymerization of 100 to 10,000, in which the amount of the alkenyl groups is 0.01 to 20 mol %,
(B) reinforcing silica having a specific surface area of 50 m ² /g or more: 5 to 100 parts by mass,
(C) Curing agent: an effective amount.

Each component will be described in detail below.
[Component (A)]
In the present invention, component (A) is an alkenyl-containing organopolysiloxane having two or more alkenyl groups per molecule, a degree of polymerization of 100 to 10,000, and an amount of the alkenyl groups of 0.01 to 20 mol %.

The alkenyl group has 2 to 12 carbon atoms, preferably 2 to 8 carbon atoms. Specific examples include vinyl, allyl, butenyl, pentenyl, hexenyl, and cyclohexenyl groups. Vinyl and allyl groups are preferred, with vinyl being particularly preferred.

Substituents other than alkenyl groups in component (A) above include groups selected from alkyl groups having 1 to 12 carbon atoms, preferably 1 to 8 carbon atoms, aryl groups having 6 to 12 carbon atoms, preferably 6 to 8 carbon atoms, and aralkyl groups having 7 to 12 carbon atoms, preferably 7 to 8 carbon atoms.

Specific examples include alkyl groups such as methyl, ethyl, propyl, butyl, hexyl, and octyl; cycloalkyl groups such as cyclopentyl and cyclohexyl; aryl groups such as phenyl and tolyl; and aralkyl groups such as benzyl and 2-phenylethyl. These hydrocarbon groups may be partially substituted with halogen atoms, as in the case of trifluoropropyl. Among these, methyl, phenyl, and trifluoropropyl groups are preferred, with methyl being particularly preferred.

The amount of alkenyl groups in component (A) (hereinafter also referred to as alkenyl group amount) is preferably 0.01 to 20 mol %, and especially 0.02 to 10 mol %, of the total number of substituents in the organopolysiloxane of component (A). These alkenyl groups may be bonded to silicon atoms at the molecular chain terminals, or somewhere along the molecular chain, or both, but it is preferable that they are bonded to silicon atoms at least at the molecular chain terminals.

When using addition reaction curing agents (C-1) and (C-2) as the (C) curing agent described below, it is essential that component (A) have two or more alkenyl groups per molecule.

Furthermore, of all substituents other than alkenyl groups in component (A), preferably 80 mol% or more, more preferably 90 mol% or more, particularly preferably 95 mol% or more, and even more preferably all substituents other than alkenyl groups are alkyl groups, particularly methyl groups.

The molecular structure of the organopolysiloxane of component (A) is preferably linear or partially branched. Specifically, the repeating structure of diorganosiloxane units (R ¹ ₂ SiO _2/2 , where R ¹ is the same as the non-alkenyl substituents in component (A) listed above, the same applies hereinafter) that constitute the main chain of the organopolysiloxane is preferably one consisting solely of repeating dimethylsiloxane units, or one in which a diorganosiloxane unit having a substituent such as a phenyl group, vinyl group, or 3,3,3-trifluoropropyl group, such as a diphenylsiloxane unit, methylphenylsiloxane unit, methylvinylsiloxane unit, or methyl-3,3,3-trifluoropropylsiloxane unit, has been introduced as part of the dimethylpolysiloxane structure consisting of repeating dimethylsiloxane units that constitute the main chain.

It is also preferred that both molecular chain terminals are blocked with, for example, a triorganosiloxy group (R ¹ ₃ SiO _1/2 ) such as a trimethylsiloxy group, a dimethylphenylsiloxy group, a vinyldimethylsiloxy group, a divinylmethylsiloxy group, or a trivinylsiloxy group, or a hydroxydiorganosiloxy group (R ¹ ₂ (HO)SiO _1/2 ) such as a hydroxydimethylsiloxy group.

As mentioned above, the organopolysiloxane of component (A) is preferably a linear polysiloxane in which both molecular chain terminals are blocked with _{triorganosiloxy} groups ( ^R13SiO1 / ₂ ) or hydroxydiorganosiloxy groups ( ^R12 (HO ₎ SiO1 _/2 ), and _the main chain is composed of repeating diorganosiloxane units ( ^R12SiO2 / ₂ ). Particularly preferred examples of the organopolysiloxane in terms of the type of substituent in the molecule (i.e., monovalent hydrocarbon groups bonded to silicon atoms) include methylvinylpolysiloxane, methylphenylvinylpolysiloxane, methyltrifluoropropylvinylpolysiloxane, and dimethylpolysiloxane.

Such organopolysiloxanes can be obtained, for example, by (co)hydrolytic condensation of one or more organohalogenosilanes, or by ring-opening polymerization of cyclic polysiloxanes (siloxane trimers, tetramers, etc.) using an alkaline or acidic catalyst.

The degree of polymerization of the organopolysiloxane is preferably 100 or higher, more preferably 150 to 100,000, and especially preferably 200 to 10,000. If the degree of polymerization is 100 or higher, the resulting silicone rubber will have sufficient strength, while if it is 100,000 or lower, the viscosity will not be too high and workability will be good.

Component (A) may be used alone or as a mixture of two or more types with different molecular weights (degrees of polymerization) or molecular structures.

[(B) Component]
The reinforcing silica of component (B) is a filler added to obtain a silicone resin composition with excellent mechanical strength, and for this purpose, the specific surface area measured by the BET adsorption method is preferably 50 m ² /g or more, more preferably 100 to 450 m ² /g, and particularly preferably 100 to 300 m ² /g. If the specific surface area is 50 m ² /g or more, a silicone rubber with sufficient strength can be obtained.

Examples of such reinforcing silica include fumed silica and precipitated silica (wet silica). These silicas whose surfaces have been hydrophobized with organosilane compounds such as methylchlorosilane or silazane compounds such as hexamethyldisilazane are also suitable for use, with fumed silica being particularly preferred.

Component (B) may be used alone or in combination of two or more types.

The amount of reinforcing silica (component (B)) blended is preferably 5 to 100 parts by mass, more preferably 10 to 80 parts by mass, and particularly preferably 15 to 60 parts by mass, per 100 parts by mass of organopolysiloxane (component (A)). A blending amount of 5 parts by mass or more of component (B) provides a sufficient reinforcing effect, while a blending amount of 100 parts by mass or less prevents the viscosity of the resulting composition from becoming too high, ensuring good workability.

In the present invention, if necessary, a dispersant (wetter) can be added as an optional component to uniformly disperse the reinforcing silica (component (B)) in the organopolysiloxane (component (A)). This wetter can be one or more selected from the group consisting of silane compounds containing silanol groups (i.e., silicon-bonded hydroxyl groups) such as diphenylsilanediol, silanol-containing organosiloxane oligomers such as linear dimethylsiloxane oligomers with silanol groups capped at both molecular chain ends (e.g., low-polymerization polymers with a degree of polymerization of 2 to 30, particularly 3 to 20, silicon atoms per molecule), and silazanes.

The amount of wetter blended is preferably 0 to 25 parts by mass, and more preferably 3 to 20 parts by mass, per 100 parts by mass of component (A).

[(C) Component]
The curing agent (C) reacts with the alkenyl-containing organopolysiloxane (A) to form a crosslinked structure, thereby curing the silicone resin composition into a silicone rubber.

The above-mentioned component (C) is selected from, for example, an addition reaction curing agent, which is a combination of (C-1) an organohydrogenpolysiloxane that is liquid at 25°C and contains two or more hydrosilyl groups per molecule, and (C-2) a hydrosilylation reaction catalyst, or (C-3) a peroxide curing agent, which is an organic peroxide. These are described in detail below.

[(C-1) component]
The organohydrogenpolysiloxane of component (C-1) undergoes a hydrosilylation addition reaction primarily with the alkenyl groups in component (A), and acts as a crosslinking agent (curing agent).

The molecular structure of component (C-1) can be a variety of structures, including linear, cyclic, branched, and three-dimensional network (resinous) structures, but it must have at least two, and preferably three or more, hydrogen atoms bonded to silicon atoms (hydrosilyl groups) per molecule. It is desirable for each molecule to have 2 to 300, preferably 3 to 200, and more preferably 4 to 100 hydrosilyl groups, and the component used should be liquid at 25°C. These hydrosilyl groups may be located at either the terminals or midway along the molecular chain, or both.

This organohydrogenpolysiloxane can be one represented by the following average composition formula (1):

In formula (1), ^R2 is independently a monovalent hydrocarbon group having 1 to 10 carbon atoms. Examples include alkyl groups such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, neopentyl, hexyl, cyclohexyl, octyl, nonyl, and decyl; aryl groups such as phenyl, tolyl, xylyl, and naphthyl; aralkyl groups such as benzyl, phenylethyl, and phenylpropyl; and groups in which some or all of the hydrogen atoms of these groups have been substituted with halogen atoms such as fluorine, bromine, or chlorine, such as chloromethyl, chloropropyl, bromoethyl, and trifluoropropyl. Note that ^R2 does not include groups having an aliphatic unsaturated bond, such as alkenyl groups. Furthermore, a is a positive number that satisfies 0.7 to 2.1, b is a positive number that satisfies 0.001 to 1.0, and a+b is a positive number that satisfies 0.8 to 3.0, and preferably a is a positive number that satisfies 1.0 to 2.0, b is a positive number that satisfies 0.01 to 1.0, and a+b is a positive number that satisfies 1.5 to 2.5.

Examples of organohydrogenpolysiloxanes of component (C-1) include 1,1,3,3-tetramethyldisiloxane, 1,3,5,7-tetramethylcyclotetrasiloxane, tris(hydrogendimethylsiloxy)methylsilane, tris(hydrogendimethylsiloxy)phenylsilane, methylhydrogencyclopolysiloxane, methylhydrogensiloxane-dimethylsiloxane cyclic copolymers, methylhydrogenpolysiloxanes terminally blocked with trimethylsiloxy groups, dimethylsiloxane-methylhydrogensiloxane copolymers terminally blocked with trimethylsiloxy groups, dimethylsiloxane-methylhydrogensiloxane-methylphenylsiloxane copolymers terminally blocked with trimethylsiloxy groups, and dimethylsiloxane-methylhydrogensiloxane-dimer terminally blocked with trimethylsiloxy groups. Phenylsiloxane copolymer, methylhydrogenpolysiloxane capped at both molecular chain terminals with dimethylhydrogensiloxy groups, dimethylpolysiloxane capped at both molecular chain terminals with dimethylhydrogensiloxy groups, dimethylsiloxane-methylhydrogensiloxane copolymer capped at both molecular chain terminals with dimethylhydrogensiloxy groups, dimethylsiloxane-methylphenylsiloxane copolymer capped at both molecular chain terminals with dimethylhydrogensiloxy groups, dimethylsiloxane-diphenylsiloxane copolymer capped at both molecular chain terminals with dimethylhydrogensiloxy groups, methylphenylpolysiloxane capped at both molecular chain terminals with dimethylhydrogensiloxy groups, diphenylpolysiloxane capped at both molecular chain terminals with dimethylhydrogensiloxy groups, and compounds in which some or all of the methyl groups in each of these exemplary compounds have been substituted with other alkyl groups such as ethyl groups or propyl groups, compounds of the formula: R 23SiO1/ ₂ 、与式： _R22HSiO1 / ₂和式：SiO4/ ₂的硅氧烷共聚物，其中，其中_的 ^硅氧烷共聚物组成^的 _硅氧烷单元，^其中，其中的硅氧烷单元_R2HSiO2 /2和式： ^R2SiO3 / ₂或式：HSiO3/ ₂的硅氧烷共聚物组成的^{混合物。 23SiO1/2} _, 23SiO1/2, _23SiO1 / ₂ , 23SiO1/ ² , 23SiO3 ...

The amount of component (C-1) to be added is such that the hydrosilyl groups contained in component (C-1) are 1 to 10 moles, preferably 1.2 to 9 moles, and more preferably 1.5 to 8 moles per mole of silicon-bonded alkenyl groups contained in component (A). When the hydrosilyl groups contained in component (C-1) are 1 mole or more per mole of silicon-bonded alkenyl groups contained in component (A), the composition can be cured sufficiently; when the amount is 10 moles or less, the heat resistance of the resulting cured silicone rubber product is good.

The organohydrogenpolysiloxane of component (C-1) may be used alone or in combination of two or more different compounds.

[(C-2) component]
The hydrosilylation catalyst for component (C-2) primarily promotes the addition reaction between silicon-bonded alkenyl groups in component (A) and hydrosilyl groups in component (C-1). This hydrosilylation catalyst is not particularly limited, and examples include platinum group metals such as platinum, palladium, and rhodium; chloroplatinic acid; alcohol-modified chloroplatinic acid; coordination compounds of chloroplatinic acid with olefins, vinylsiloxanes, or acetylene compounds; and platinum group metal compounds such as tetrakis(triphenylphosphine)palladium and chlorotris(triphenylphosphine)rhodium, with platinum group metal compounds being preferred.

The amount of component (C-2) to be added should be an effective amount as a catalyst, but is preferably 1 to 500 ppm, and more preferably 10 to 100 ppm, by mass of catalytic metal element relative to the total amount of components (A) to (C-1). Within this range, the curing reaction proceeds quickly and the heat resistance of the cured product does not decrease.

The addition reaction catalyst of component (C-2) may be used alone or in combination of two or more types.

[(C-3) component]
Examples of organic peroxide curing agents for component (C-3) include benzoyl peroxide, 2,4-dichlorobenzoyl peroxide, p-methylbenzoyl peroxide, o-methylbenzoyl peroxide, 2,4-dicumyl peroxide, 2,5-dimethyl-2,5-bis(t-butylperoxy)hexane, di-t-butyl peroxide, t-butyl perbenzoate, and 1,6-hexanediol-bis-t-butyl peroxycarbonate. The amount of organic peroxide added is 0.01 to 10 parts by mass, more preferably 0.05 to 5 parts by mass, and even more preferably 0.1 to 3 parts by mass, per 100 parts by mass of component (A). When the amount is 0.01 part by mass or more, curing proceeds sufficiently, while when the amount is 10 parts by mass or less, yellowing of the cured silicone rubber due to decomposition residues of the organic peroxide does not occur.

In addition, it is also possible to combine component (A) with components (C-1), (C-2), and (C-3) in the amounts specified above to produce a co-vulcanization type silicone resin composition that combines addition reaction curing and organic peroxide curing.

[Other ingredients]
The silicone resin composition that can be used in the present invention can contain any other components in addition to the components (A) to (C). Specific examples include the following. These other components may each be used alone, or two or more may be used in combination.

Reaction Retardant The reaction retardant is not particularly limited as long as it is a compound that has a cure-inhibiting effect on the hydrosilylation catalyst of component (C-2), and known reaction retarders can be used. Specific examples include phosphorus-containing compounds such as triphenylphosphine; nitrogen-containing compounds such as tributylamine, tetramethylethylenediamine, and benzotriazole; sulfur-containing compounds; acetylene compounds such as acetylene alcohols such as 1-ethynyl-1-cyclohexanol, 3-butyn-1-ol, 2-methyl-3-butyn-2-ol, and 3-methyl-1-tridecyn-3-ol; vinyl group-containing siloxanes such as 1,3-divinyl-1,1,3,3-tetramethyldisiloxane and 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane; hydroperoxy compounds; and maleic acid derivatives.

The degree of cure inhibition effect of a reaction retarder varies depending on the chemical structure of the reaction retarder, so it is preferable to adjust the amount of reaction retarder added to the optimum amount for each reaction retarder used. By adding an optimal amount of reaction retarder, the composition will have excellent long-term storage stability and cure properties at room temperature.

Non-reinforcing fillers Examples of fillers other than the fine silica powder of component (B) include crystalline silica (e.g., quartz powder with a BET specific surface area of less than 50 ^m2 /g), organic resin hollow fillers, polymethylsilsesquioxane microparticles (so-called silicone resin powder), fumed titanium dioxide, magnesium oxide, zinc oxide, iron oxide, aluminum hydroxide, magnesium carbonate, calcium carbonate, zinc carbonate, carbon black, diatomaceous earth, talc, kaolinite, glass fiber, and other fillers; fillers obtained by subjecting these fillers to surface hydrophobic treatment with organosilicon compounds such as organoalkoxysilane compounds, organochlorosilane compounds, organosilazane compounds, and low-molecular-weight siloxane compounds; silicone rubber powder; and silicone resin powder.

Other Components Other components that may be blended include, for example, organopolysiloxanes containing one silicon-bonded hydrogen atom per molecule and no other functional groups, organopolysiloxanes containing one silicon-bonded alkenyl group per molecule and no other functional groups, non-functional organopolysiloxanes containing no silicon-bonded hydrogen atoms, silicon-bonded alkenyl groups, or other functional groups (so-called dimethyl silicone oil), organic solvents, creep-hardening inhibitors, plasticizers, thixotropy-imparting agents, pigments, dyes, and mildew inhibitors.

<Preparation of Silicone Resin Composition for Inner Bag Production>
The silicone resin composition can be prepared by uniformly mixing the above components (A) to (C) and other components that are added as needed using a mixer or a two-roll mill.

<Inner bag manufacturing method>
The inner bag 2 can be manufactured by known methods such as mold molding, calendar molding, injection molding, cast molding, transfer molding, dip molding, and coating molding. However, the inner bag structure is not formed by sewing multiple thermosetting resin sheets together or using adhesives, but rather by manufacturing a single, integrated molded body. A specific manufacturing method involves, for example, extruding uncured thermosetting resin to half the thickness of a mold, and then placing a release film or similar on top as a core. Another thermosetting resin is then extruded on top of that and cured using a high-temperature press or similar. The opening is then cut out with a cutter or similar, and the release film serving as the core is removed, thereby manufacturing the inner bag 2 made of thermosetting resin with a bag structure.

The thickness (film thickness) of the inner bag 2 is preferably 20 to 600 μm, more preferably 40 to 400 μm, and even more preferably 60 to 300 μm. If the thickness of the inner bag is 20 μm or more, sufficient internal pressure retention is achieved, and if it is 600 μm or less, the volume does not increase when the airbag fabric is folded and stored inside the vehicle, and it does not compress the interior space.

<Woven fabric outer bag>
In the present invention, any known woven fabric can be used for the outer bag 3. Specific examples include woven fabrics made of various synthetic fibers, such as various polyamide fibers, such as nylon 66, nylon 6, and aramid fibers, and various polyester fibers, such as polyethylene terephthalate (PET) and polybutylene terephthalate (PBT). Nylon 66 or PET is particularly preferred.

The fineness of the yarn making up the woven fabric of the outer bag 3 is preferably 50 to 1,000 denier, more preferably 100 to 800 denier, and more preferably 150 to 500 denier. A yarn fineness of 50 denier or more provides sufficient strength, while a yarn fineness of 1,000 denier or less provides sufficient flexibility and good foldability.

<Area ratio of inner bag to outer bag>
The area of the inner bag 2 is preferably 50 to 99% of the area of the outer bag 3. If the size of the inner bag 2 is 50% or more of the area of the outer bag 3, it can expand to a sufficient size when the airbag is deployed and can fulfill its role of absorbing impact on the human body in the event of a vehicle collision. Furthermore, if the area of the inner bag 2 is 99% or less of the area of the outer bag 3, the inner bag 2 can be easily inserted into the outer bag 3.

In this invention, the area of the bag refers to the maximum area that can be measured when the bag is unfilled and placed flat on a flat surface.

<Method for manufacturing airbag fabric>
The produced bag-shaped thermosetting resin molded body having one or more openings 4 is used as the inner bag 2, and an outer bag 3 made of woven fabric and having one or more openings is attached to the outside of the inner bag 2 while aligning the openings, thereby manufacturing the airbag base fabric 1 of the present invention. Methods for attaching the outer bag 3 include a method of folding the inner bag 2 and inserting it through the opening of the outer bag 3, and a method of forming the outer bag 3 by sandwiching the inner bag 2 between two pieces of plain woven fabric and sewing the periphery along the shape of the inner bag 2. In this case, no adhesive or the like is used to form the double structure from the inner bag 2 and outer bag 3, and by leaving a gap between the inner bag 2 and outer bag 3, the inner bag 2 and outer bag 3 can be easily separated even after the airbag is deployed.

<Recycling of airbag fabric>
In the airbag fabric 1 having a double-blade structure of the present invention, the inner bag 2 and the outer bag 3 are not bonded with adhesive or the like, so the inner bag 2 and the outer bag 3 can be easily separated even after the airbag is deployed. When separating the two, the inner bag 2 can be pulled out through the opening of the outer bag 3, or an incision can be made in the outer bag 3 and the inner bag 2 can be pulled out. The woven fabric and thermosetting resin separated in this way do not contain any other materials and can therefore be easily recycled in an appropriate manner.

The present invention will be explained in detail below using examples and comparative examples, but these examples are not intended to limit the present invention in any way. Furthermore, the elongation at break of each thermosetting resin was measured using a 2 mm thick sheet prepared by press curing at 165°C for 10 minutes, according to the method described in JIS K 6251:2017.

[Preparation Example 1]
The following ingredients were prepared:
50 parts by mass of organopolysiloxane gum (component (A-1)) which is a copolymer of methylvinylsiloxane units and dimethylvinylsiloxy units, both ends of which are capped with dimethylvinyl units, and has a degree of polymerization of approximately 6,000 and a vinyl group content of 0.025 mol %;
50 parts by mass of organopolysiloxane gum (component (A-2)) which is a copolymer of methylvinylsiloxane units and dimethylvinylsiloxy units, both ends of which are capped with dimethylvinyl units, and has a degree of polymerization of approximately 6,000 and a vinyl group content of 0.15 mol %;
25 parts by mass of fumed silica (Aerosil 200, manufactured by Nippon Aerosil Co., Ltd.) (component (B)) having a BET specific surface area of 200 m ² /g,
As a wetter, 5 parts by mass of dimethylpolysiloxane having silanol groups at both ends, a degree of polymerization of 4, and a viscosity of 15 mPa·s at 25°C;
0.15 parts by mass of vinyltrimethoxysilane,
0.5 parts by weight of dimethyldimethoxysilane, and 0.01 parts by weight of hexamethyldisilazane.

These ingredients were added and heated and mixed in a kneader at 170°C for 2 hours to prepare the base compound.

[Preparation Example 2]
To 100 parts by mass of the base compound prepared in Preparation Example 1, 0.13 parts by mass of 2,5-dimethyl-2,5-bis(t-butylperoxy)hexane (component (C-3)) as a curing agent was added using a twin roll, and the mixture was mixed uniformly to obtain a raw rubber-like silicone resin composition A (elongation at break: 500%).

[Example 1]
The silicone resin composition A prepared in Preparation Example 2 was extruded to a thickness of 300 μm and set in a 500 mm × 500 mm × 0.7 mm thick frame mold. A 125 μm thick PET film of the same shape as the outer bag but 0.5 mm smaller than the inner dimensions of the outer bag was placed on top of it, and the silicone resin composition A extruded to a thickness of 300 μm was placed on top of that. It was then press-cured at 165 ° C for 10 minutes. Next, the molded product was removed from the mold, and a hole was made with a cutter in the portion that would become the opening of the inner bag, and the PET film was removed from inside.

The thickness of the inner bag produced was 300 μm, and its area was 99% of the area of the outer bag.

Then, the prepared inner bag was folded and inserted through the opening into a PET outer bag (fineness: 410 denier) with a 70 mm wide opening, thereby producing the airbag base fabric of Example 1.

<Internal pressure retention test method>
An internal pressure retention test was conducted using the air bag fabric prepared in Example 1. In the internal pressure retention test, the prepared air bag fabric was inflated with an air compressor to an internal pressure of 20 kPa, and the residual pressure after 30 seconds was measured using an apparatus manufactured by Miroku Seiki Seisakusho Co., Ltd. The results are shown in Table 1.

<Recyclability test method>
After the internal pressure retention test, the airbag fabrics were evaluated as "Good" if they could be separated into the inner bag and outer bag made of silicone rubber, a thermosetting resin, using a cutter, and evaluated as "Poor" if they could not. The results are shown in Table 1.

[Example 2]
An airbag fabric prepared in the same manner as in Example 1 was inflated with an air compressor to an internal pressure of 40 kPa, and the residual pressure after 30 seconds was measured. The results of the measurement and the recyclability test are shown in Table 1.

[Example 3]
In Example 1, the thickness of the silicone resin composition A to be extruded was changed from 300 μm to 100 μm, and the thickness of the mold was changed from 0.7 mm to 0.3 mm. An airbag fabric of Example 3 was produced in the same manner as in Example 1. The thickness of the produced inner bag was 100 μm, and the area of the inner bag was 99% of the area of the outer bag. The results of the internal pressure retention test and recyclability test for this airbag fabric were shown in Table 1, using the same methods as in Example 1.

[Example 4]
An airbag fabric was produced in the same manner as in Example 1, except that the outer bag was changed from a PET woven fabric to a PA66 woven fabric (fineness: 210 denier) (inner bag thickness: 300 μm, inner bag area ratio: 99%). This airbag fabric was subjected to an internal pressure retention test and a recyclability test in the same manner as in Example 1. The results are shown in Table 1.

[Example 5]
In Example 1, the size of the PET film sandwiched between the two extruded sheets of silicone resin composition A was changed from 0.5 mm smaller than the inner dimension of the outer bag to 20 mm smaller. An airbag fabric of Example 5 was produced in the same manner as in Example 1. The thickness of the produced inner bag was 300 μm, and the area of the inner bag was 65% of the area of the outer bag. The results of the internal pressure retention test and recyclability test for this airbag fabric were shown in Table 1, using the same methods as in Example 1.

[Preparation Example 3]
To 100 parts by mass of the base compound prepared in Preparation Example 1, 0.9 parts by mass of methylhydrogenpolysiloxane having hydrosilyl groups on the side chains as a curing agent (degree of polymerization 38, in formula (1), R ² = methyl group, a = 1.6, b = 0.47, 0.00725 mol/g of hydrosilyl groups) (component (C-1)) as a curing agent, 0.04 parts by mass of ethynylcyclohexanol as a reaction inhibitor, 0.05 parts by mass of platinum catalyst (Pt concentration 1% by mass) (component (C-2)) as a reaction inhibitor, and 0.02 parts by mass of ethynylcyclohexanol as a inhibitor were added and mixed uniformly using a two-roll mill to obtain a raw rubber-like silicone resin composition B (hydrosilyl group amount/vinyl group amount = 3.3, elongation at break 550%).

[Example 6]
An airbag fabric was produced using the silicone resin composition B (inner bag thickness: 300 μm, area ratio of the inner bag to the outer bag: 99%) in the same manner as in Example 1. This airbag fabric was subjected to an internal pressure retention test and a recyclability test in the same manner as in Example 1, and the results are shown in Table 1.

[Comparative Example 1]
Silicone airbag coating material X-34-4120-1A/B (manufactured by Shin-Etsu Chemical Co., Ltd.) was coated onto the same PET outer bag (fineness: 410 denier) as in Example 1 at a coating amount of 100 g/m ² (average thickness 100 μm), and the coating material was cured by heating at 180°C for 3 minutes. The back side was then similarly coated at a coating amount of 100 g/m ² (average thickness 100 μm) and cured at 180°C for 3 minutes to produce a silicone rubber-coated airbag fabric of Comparative Example 1. In other words, the airbag fabric of Comparative Example 1 did not have a double-bag structure consisting of an inner bag and an outer bag. This airbag fabric was subjected to an internal pressure retention test and a recyclability test using the same method as in Example 1, and the results are shown in Table 2.

[Comparative Example 2]
An inner bag was prepared in the same manner as in Example 1. Then, two outer bags were prepared by coating one side of a plain woven fabric made of PET (fineness: 410 denier) with an adhesive silicone coating material, KEG-2052-A/B (manufactured by Shin-Etsu Chemical Co., Ltd.), at a coating weight of 40 g/ ^m² . These were attached to both sides of the inner bag and heated at 180 °C for 3 minutes to bond the inner bag and outer bag. The periphery was then sewn to match the shape of the inner bag, and an airbag base fabric with a double bag structure of Comparative Example 2 was prepared. That is, the airbag base fabric of Comparative Example 2 did not have a gap between the inner bag and the outer bag. The results of an internal pressure retention test and a recyclability test for this airbag base fabric were shown in Table 2, which were conducted in the same manner as in Example 1.

[Comparative Example 3]
The silicone resin composition A was extruded to a thickness of 300 μm and set in a 500 mm x 500 mm, 0.3 mm thick frame mold. Two 300 μm thick silicone rubber sheets were then produced by press curing at 165 ° C for 10 minutes. These two sheets were then bonded together with an adhesive (product name: Super X-2, manufactured by Cemedine Co., Ltd.) to produce an inner bag of the same shape as in Example 1. That is, the inner bag produced in Comparative Example 3 was not a bag-shaped molded body (integrally molded body). This inner bag was folded and inserted through the opening into a PET outer bag (fineness: 410 denier) with a 70 mm wide opening, thereby producing the airbag base fabric of Comparative Example 3. This airbag base fabric was subjected to an internal pressure retention test and a recyclability test using the same method as in Example 1, and the results are shown in Table 2.

As is clear from the results shown in Table 1, the airbag fabrics of Examples 1 to 6, which are examples of the present invention, were able to maintain the same or nearly the same pressure as the initial pressure even after 30 seconds in the internal pressure retention test. Furthermore, the airbag fabrics of Examples 1 to 6, which are examples of the present invention, were able to easily separate the inner bag and outer bag after the internal pressure retention test, demonstrating excellent recyclability.

On the other hand, in the internal pressure retention test, the internal pressure of the airbag fabric of Comparative Example 1 was half of the initial pressure after 30 seconds. For Comparative Example 3, the residual pressure was 0 kPa after 30 seconds.

Furthermore, with the airbag base fabrics of Comparative Examples 1 to 3, it was impossible to separate the resin after the internal pressure retention test.

As such, the airbag fabric of the present invention has excellent internal pressure retention when the airbag is manufactured, and is easily recyclable.

The present invention includes the following aspects.
[1] An airbag base fabric having a double-bag structure consisting of an inner bag and an outer bag, wherein the inner bag is made of a thermosetting resin and is a bag-shaped molded body having one or more openings, and the outer bag is formed of a woven fabric and has a gap between the inner bag and the outer bag.
[2] The airbag fabric according to [1], characterized in that the area of the inner bag is 50 to 99% of the area of the outer bag.
[3] The airbag fabric according to [1] or [2], characterized in that the thickness of the inner bag is 20 to 600 μm.
[4] The thermosetting resin is silicone rubber, and the elongation at break measured by the method described in JIS K 6251:2017 is 300% or more. [3] The airbag base fabric according to any one of [1] to [3].
[5] The airbag fabric according to [4], characterized in that the silicone rubber comprises: (A) 100 parts by mass of an alkenyl group-containing organopolysiloxane having two or more alkenyl groups in one molecule and a degree of polymerization of 100 to 10,000, wherein the amount of the alkenyl groups is 0.01 to 20 mol %; (B) 5 to 100 parts by mass of reinforcing silica having a specific surface area of 50 m ² /g or more; and (C) an effective amount of a curing agent.
[6] The airbag fabric according to [5], characterized in that the component (C) comprises the following (C-1) and (C-2): (C-1) an organohydrogenpolysiloxane that is liquid at 25°C and contains two or more hydrogen atoms bonded to silicon atoms (hydrosilyl groups) per molecule, in which the hydrosilyl groups contained in this component are present in an amount of 1 to 10 moles per mole of the total of the silicon-bonded alkenyl groups contained in the component (A); and (C-2) a hydrosilylation reaction catalyst in an amount that corresponds to 1 to 500 ppm by mass of the catalytic metal element relative to the total mass of the components (A) to (C).
[7] The airbag fabric according to [5] or [6], characterized in that the (C) component is (C-3) organic peroxide: 0.01 to 10 parts by mass.
[8] The woven fabric of the outer bag is woven with nylon 66 (PA66) or polyethylene terephthalate (PET) yarn, and the yarn has a fineness of 50 to 1,000 denier. [1] The airbag base fabric according to any one of [7] to [7].

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

1...Airbag base fabric, 2...Inner bag, 3...Outer bag, 4...Opening, 5...Gap.

Claims (7)

An airbag fabric having a double-bag structure consisting of an inner bag and an outer bag,
The inner bag is a bag-shaped molded body made of a thermosetting resin and having one or more openings,
The outer bag is made of woven fabric,
A gap is formed between the inner bag and the outer bag ,
The thermosetting resin is silicone rubber, and the elongation at break measured by the method described in JIS K 6251:2017 is 300% or more . The airbag fabric according to claim 1, characterized in that the area of the inner bag is 50 to 99% of the area of the outer bag. The airbag fabric according to claim 1, characterized in that the thickness of the inner bag is 20 to 600 μm. The silicone rubber is
(A) 100 parts by mass of an alkenyl group-containing organopolysiloxane having two or more alkenyl groups per molecule, a degree of polymerization of 100 to 10,000, and an amount of the alkenyl groups of 0.01 to 20 mol %,
(B) reinforcing silica having a specific surface area of 50 m ² /g or more: 5 to 100 parts by mass;
2. The air bag fabric according to claim 1 , which is a cured product of a silicone resin composition containing an effective amount of (C) a curing agent. The component (C) is selected from the following (C-1) and (C-2):
(C-1) an organohydrogenpolysiloxane that is liquid at 25°C and contains two or more silicon-bonded hydrogen atoms (hydrosilyl groups) per molecule: the amount of hydrosilyl groups contained in this component is 1 to 10 moles per mole of the total silicon-bonded alkenyl groups contained in component (A);
(C-2) a hydrosilylation reaction catalyst: an amount of 1 to 500 ppm, calculated as the mass of the catalytic metal element, relative to the total mass of the components (A) to (C). The airbag fabric according to claim 4 . The component (C) is
The air bag fabric according to claim 4 , characterized in that (C-3) organic peroxide: 0.01 to 10 parts by mass. The woven fabric of the outer bag is woven with nylon 66 (PA66) or polyethylene terephthalate (PET) yarn, and the yarn has a fineness of 50 to 1,000 denier. The airbag base fabric according to any one of claims 1 to 6 .