JP2571986B2 - Silicone rubber composition for airbag coating - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air bag for a vehicle or the like.
The present invention relates to a silicone rubber composition for coating . For details, silicone for airbag coating of vehicles, etc., which has adhesive strength that can withstand the impact of expansion, especially at high temperature
The present invention relates to a rubber composition .

[0002]

2. Description of the Related Art In recent years, airbags have been put into practical use as safety devices for protecting occupants of automobiles. Such an airbag is generally composed of a base fabric in which chloroprene rubber is coated on a nylon fabric.
However, it is difficult to reduce the weight of the base fabric coated with the chloroprene rubber, and in particular, there is a disadvantage that the physical properties deteriorate with the passage of time. Recently, an airbag base fabric coated with silicone rubber has been proposed (see JP-A-63-78744). The airbag base fabric coated with the silicone rubber has an advantage of being excellent in high-temperature characteristics, and has the advantage that the weight of the silicone rubber can be reduced because it can be coated with a thin film. However, this silicone rubber has a disadvantage that its adhesive strength to a synthetic fiber fabric for airbags such as nylon 66 is insufficient. That is, when the air bag is operated, there is a problem that the rubber layer is peeled off or burnt out due to high temperature gas generated from inside the inflator and intense rubbing of the coating surfaces during expansion.

[0003]

DISCLOSURE OF THE INVENTION The present inventors have studied to solve the above-mentioned problems, and as a result, a silicone rubber composition containing a specific organosilicon compound was added to a synthetic fiber fabric for an air bag. On the other hand, they found that they adhered firmly and were also excellent in thin film coating properties, leading to the present invention. That is, an object of the present invention is to provide an airbag base fabric which exhibits excellent adhesive strength to a synthetic fiber woven fabric for an airbag, has excellent folding storage properties (flexibility) and extensibility, and has little deterioration due to aging. Air that can be obtained
It is an object of the present invention to provide a silicone rubber composition for coating a bag .

[0004]

The object of the present invention is to provide (A) 100 parts by weight of an organopolysiloxane containing two or more silicon-bonded alkenyl groups in one molecule, (B) finely divided silica 5 100 parts by weight, (C) an organic silicic silicon compound containing an epoxy group bonded to a silicon atom via an alkylene group 0.1 to 20 parts by weight, sufficient to cure the curing agent (D) the composition of the present invention Air bag coaty
This can be achieved by a silicone rubber composition for packaging .

[0005] The organopolysiloxane of the component (A) used in the present invention is a main component of the composition of the present invention, and the composition of the present invention becomes a silicone rubber coating film having rubber elasticity after curing. Two or more in one molecule
It is necessary to have a silicon-bonded alkenyl group. Such an organopolysiloxane has the general formula

(Equation 1) [Wherein R is an alkyl group such as a methyl group, an ethyl group, or a propyl group; an alkenyl group such as a vinyl group or an allyl group; an aryl group such as a phenyl group; a halogenated alkyl group such as a 3,3,3-tripropyl group; And a substituted or unsubstituted monovalent hydrocarbon group. n is 1.9 to 2.1. ] Is a substantially linear organopolysiloxane represented by the formula: The viscosity of this organopolysiloxane is 2
Those having a viscosity of 5 centipoise or more at 5 ° C. are preferably used, and those having a viscosity at 25 ° C. of 5000 centipoise or more are more preferable in consideration of the strength of the silicone rubber coating film and the workability of compounding. Specific examples of the component include dimethylpolysiloxane having dimethylvinylsiloxy groups at both ends, dimethylsiloxane / methylvinylsiloxane copolymer having dimethylvinylsiloxy groups at both ends, and dimethylsiloxane / methylphenylsiloxane having dimethylvinylsiloxy groups at both ends. And copolymers.

As the finely divided silica as the component (B), those which have been conventionally used as a reinforcing filler for silicone rubber and which are well known can be used, and the type thereof is not particularly limited. Examples of such silica include fumed silica and precipitated silica. Among them, silica in the form of ultrafine powder having a particle diameter of 50 mμ or less and a specific surface area of 50 m ² / g or more is preferable. Also, surface-treated silica,
For example, silica that has been previously surface-treated with an organosilane, an organosilazane, a diorganocyclopolysiloxane, or the like is more preferable.

[0007] As used in the present invention component (C) alkylene
Contains an epoxy group bonded to a silicon atom through a
Organosilicon compound is an essential component for improving the adhesiveness to a synthetic fiber fabric for an airbag, and γ-
Epoxy-containing organoalkoxysilanes such as glycidoxypropyltrimethoxysilane and 3,4-epoxycyclohexylethyltrimethoxysilane; epoxy-containing organopolysiloxanes having vinyl and alkoxy groups; epoxy groups having silicon-bonded hydrogen atoms And epoxy-containing organopolysiloxanes such as epoxy-containing organopolysiloxanes and epoxy-containing organopolysiloxanes having silicon-bonded hydrogen atoms and alkoxy groups. Among them, specific examples of the epoxy group-containing organopolysiloxane include the following compounds.

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The curing agent (D) used in the present invention is a catalyst or a mixture of a catalyst and a crosslinking agent for curing the composition of the present invention. What is used for hardening can be used. Examples of such a curing agent include a combination of a platinum compound catalyst and at least two organohydrogenpolysiloxanes containing silicon-bonded hydrogen atoms in one molecule, and an organic peroxide.

Among the former curing agents, platinum compound catalysts include platinum fine powder, platinum black, chloroplatinic acid, platinum tetrachloride, olefin complexes of chloroplatinic acid, complexes of chloroplatinic acid with methylvinylsiloxane, Rhodium compounds and palladium compounds are exemplified. The amount of the platinum-based compound catalyst to be used is usually within a range of 0.1 to 500 parts by weight as a platinum-based metal with respect to 1,000,000 parts by weight of the component (A).

The organohydrogenpolysiloxane containing at least two silicon-bonded hydrogen atoms in one molecule includes methylhydrogenpolysiloxane having trimethylsiloxy groups at both ends and dimethylsiloxane and methylhydrogensiloxane having trimethylsiloxy groups at both ends. Polymer, dimethylphenylsiloxy group-blocked methylphenylsiloxane / methylhydrogensiloxane copolymer at both ends, cyclic methylhydrogenpolysiloxane, dimethylhydrogensiloxy unit and SiO
Copolymers composed of _4/2 units are exemplified. The amount of the organohydrogenpolysiloxane is such that the ratio of the number of moles of silicon-bonded hydrogen atoms in the organohydrogenpolysiloxane to the number of moles of silicon-bonded alkenyl groups in the component (A) is as follows. (0.6: 1) to (20:
The amount which becomes 1) is preferable. Examples of the latter organic peroxide include benzoyl peroxide, 2,4-dichlorobenzoyl peroxide, p-chlorobenzoyl peroxide, and o-chlorobenzoyl peroxide. In the present invention, it is preferable that these curing agents use a combination of the former platinum compound catalyst and at least two silicon-bonded hydrogen atom-containing organohydrogenpolysiloxanes in one molecule.

The composition of the present invention comprises the above components (A) to (D)
Although it is composed of components, it is preferable to mix an organopolysiloxane resin as the component (E) in addition to the components (A) to (D). In particular, when a platinum catalyst and an organohydrogenpolysiloxane are used as the curing agent of the component (D), a silicone rubber coating film having a high strength is preferably obtained. As such an organopolysiloxane resin, for example, a resin composed of (CH ₃ ) ₃ SiO _1/2 unit and SiO _4/2 unit, (CH ₃ ) ₃ SiO _1/2 unit and (C
A resin consisting of H ₂ = CH) SiO _3/2 units and SiO _4/2 units, (CH ₂ = CH) (CH ₃ ) ₂ SiO
Resin consisting of _1/2 unit and SiO _4/2 unit, (CH
₂ ＣＨCH) (CH ₃ ) ₂ SiO _1/2 unit and (CH ₂ ＝
_CH) resin consisting of _{SiO 3/2} units and _{SiO 4/2} units and the like. Among these, resins containing a vinyl group are preferred.

To produce the composition of the present invention, for example, the components (A) and (B) or (A), (B)
The components and (E) are uniformly kneaded with a mixer such as a two-roll mill, a kneader mixer, a pressure kneader mixer, and a loss mixer to prepare a silicone rubber base, and then the components (C) and (D) are added thereto. May be added and blended.

[0013] The composition of the present invention is prepared by using a synthetic fiber fabric for airbags (eg, nylon 6, nylon 66, nylon 46).
Such as polyamide fiber fabric, aramid fiber fabric, polyester fiber fabric represented by polyalkylene terephthalate, polyetherimide fiber fabric, sulfone fiber fabric, carbon fiber fabric, etc. An airbag base fabric can be obtained. In applying the composition of the present invention to a synthetic fiber fabric for an airbag, the most preferred airbag fabric is a nylon 66 fiber fabric. When the organopolysiloxane composition is coated on a synthetic fiber fabric for an air bag, an organic solvent such as xylene or toluene may be added to the composition of the present invention to adjust the viscosity so that the composition can be easily applied.

In the composition of the present invention, various additives conventionally known as additives for silicone rubber, for example, inorganic fillers such as titanium oxide, carbon black, red iron oxide, rare earth oxide, cerium silanolate, pigments, etc. Addition of a heat-resistant agent or a heat-resistant agent may be used as long as the object of the present invention is not impaired.

The above components (A) to (D) or (A) to
(E) If necessary, add an organic solvent, a pigment, a heat-resistant agent, etc. to the components, mix them evenly, coat them on a synthetic fiber fabric for an air bag, put them in a hot-air drying oven, heat and cure them, and air them. It can be a silicone rubber coated base fabric for bags. The composition of the present invention as described above,
The hardness (JISA) of the silicone rubber after heat curing is 30
It is preferably in the range of 60. When this is applied to a synthetic fiber fabric for an air bag, the silicone rubber coating film and the synthetic fiber fabric for the air bag are firmly bonded and integrated. The adhesive strength is 1 kgf / cm or more, and the silicone rubber coating film does not peel off due to severe rubbing during operation of the airbag.

[0016]

Next, the present invention will be described by way of examples. In the examples, “parts” means “parts by weight” and the viscosity is 25 ° C.
And cst represents centistokes.
Me represents a methyl group, and Vi represents a vinyl group.

[0017]

Example 1 99.85 mol% of dimethylsiloxane units
Dimethylsiloxane / methylvinylsiloxane copolymer raw rubber having trimethylsiloxy groups at both ends and having a methylvinylsiloxane unit content of 0.15 mol% (degree of polymerization 30)
00) 100 parts, 7.0 parts of dimethylpolysiloxane capped with silanol groups at both ends having a viscosity of 60 cst at 25 ° C. and 30 parts of fumed silica having a specific surface area of 200 m ² / g are charged into a kneader mixer until uniform under heating. Kneaded to make a rubber base. 30 parts of this rubber base was dissolved in 70 parts of toluene while stirring at room temperature. Then,
In 100 parts of this dispersion solution, methyl hydrogen polysiloxane 1.0 having an average molecular formula of Me ₃ SiO (MeHSiO) ₆ (Me ₂ SiO) ₄ SiMe ₃
Parts, 0.5 part of a complex of chloroplatinic acid and divinyltetramethyldisiloxane (0.4% by weight of platinum) and 0.4 part of 3,5-dimethyl-1-hexyn-3-ol as a curing inhibitor. In addition, they were mixed uniformly. The viscosity of this dispersion solution was 50,000 cst. Further, the following adhesion-imparting agents were added to the dispersion solution to prepare a silicone rubber coating composition. Next, this was treated with nylon 66 (42
0 denier) The fabric was coated and its adhesive strength was measured. Here, the coating method on the nylon 66 fabric for an air bag is such that the coating amount of the silicone rubber composition is 50 to 60 g / m ² with a coater, and after drying in an oven at 120 ° C. for 4 minutes, The resin was cured by heating at 180 ° C. for 5 minutes to prepare an airbag-coated base fabric. Two coated surfaces of this airbag-coated base fabric are overlapped, and a room-temperature-curable silicone rubber adhesive [manufactured by Dow Corning Toray Silicone Co., Ltd., trade name “SE9145RT”] is interposed between them.
V "], and after curing at room temperature for 7 days, a width of 2.5 cm
X A 10 cm length was cut and a peel test was performed, and the adhesive strength at that time was measured. In the air bag inflation test, hot air at a temperature of 170 to 180 ° C. is blown into the air bag under the conditions of a pressure of 7 to 8 kg / cm ² to instantaneously inflate the air bag and visually check whether the silicone rubber coating film has peeled off. Observed. Table 1 shows the evaluation results. Adhesion-imparting agent (a) γ-glycidoxypropyltrimethoxysilane Adhesion-imparting agent (b)

Embedded image Adhesion imparting agent (c)

Embedded image Adhesion-imparting agent (d) 50 parts of γ-glycidoxypropyltrimethoxysilane, and the average unit formula is

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[Table 1] * The number of added parts is the number of parts with respect to 100 parts of the dispersion solution.

[0018]

Example 2 The silicone rubber coating composition obtained in Example 1 was coated on a polyester fiber woven fabric (420 denier) for an air bag in the same manner as in Example 1, and the characteristics were evaluated in the same manner as in Example 1. It was measured. Table 2 shows the results of these evaluations.

[Table 2]

[0019]

Example 3 73 parts of dimethylpolysiloxane having a viscosity of 12000 cst and both ends of a molecular chain blocked with dimethylvinylsiloxy groups, 73 units of Vi (Me) ₂ SiO _1/2 unit and Si
O _4/2 units of vinyl group-containing methylpolysiloxane resin (Vi weight: 5.6%, viscosity: 230 cst) 27
Parts were placed in a Ross mixer. Next, a specific surface area of 200 m ² /
g of fumed silica was added and kneaded under heating until uniform, to produce a liquid silicone rubber base having fluidity. Then, this liquid silicone rubber base 1
In 00 parts, methyl hydrogen polysiloxane 4.2 whose average molecular formula is represented by Me ₃ SiO (MeHSiO) ₆ (Me ₂ SiO) ₄ SiMe ₃
Part, 0.5 part of a platinum complex of chloroplatinic acid and vinyltetramethyldisiloxane (0.4% by weight of platinum) and 0.4 part of 3,5-dimethyl-1-hexyn-3-ol as a curing inhibitor Was added and mixed uniformly. The viscosity of this liquid silicone rubber composition was 30,000 cst. The same adhesion-imparting agent as in Example 1 was added to this composition to prepare a silicone rubber coating composition. This was then coated on a nylon 66 fiber fabric and cured by heating at 180 ° C. for 5 minutes. This silicone rubber coated base fabric cannot be adhered with the room temperature curing type silicone rubber adhesive used in Example 1 and the adhesive strength cannot be measured directly. The peeling state of the rubber coating film from the cloth surface was visually determined. In this fir test, a judgment was made after the fir test was repeated 1,000 times at a pressing force of 2 kgf. Table 3 shows the results of these measurements.

[Table 3]

[0020]

The air bag coating system of the present invention
The silicone rubber composition comprises the components (A) to (D),
In particular , a bond to a silicon atom via the alkylene group of the component (C).
Since it contains an organosilicon compound containing a combined epoxy group, it shows excellent adhesion to synthetic fiber fabrics for airbags made of synthetic fiber fabrics such as nylon 66, and has a high temperature gas generated from within the inflator. It has the feature that the silicone rubber coating film does not peel off or burn out due to intense friction between the coating surfaces during expansion.

Claims (3)

(57) [Claims] (A) a compound comprising two or more silicon atoms in one molecule ;
100 parts by weight of an organopolysiloxane and containing not focus alkenyl group, (B) microparticulate silica 5-100 parts by weight, an organic silicic silicon compound containing an epoxy group bonded to a silicon atom through a (C) alkylene group 0 1 to 20 parts by weight, (D) curing agent An airbag coat comprising an amount sufficient to cure the composition of the present invention.
Silicone rubber composition for brushing . Wherein (C) an organosilicon compound of the component, alkyl
Epoxy group and silicon bonded to a silicon atom via a lens group
Organosilicon containing alkoxy group directly bonded to elemental atom
The airbag coating according to claim 1 , which is a compound.
Silicone rubber composition for use . 3. The adhesive strength of the silicone rubber coating film to a synthetic fiber fabric for airbag is 1.0 kgf /
The airbag coating according to claim 1, which is not less than 1 cm.
Silicone rubber composition for rubber .