JPH0525435A - Silicone rubber coating composition for air bag - Google Patents

Abstract

PURPOSE:To improve the adhesive power, foldability, and spreadability of a coating film prepd. from the subject compsn. by compounding an alkenylated organopolysiloxane with a powdered silica, an epoxidized organosilicon compd., and a curative. CONSTITUTION:100 pts.wt. organopolysiloxane of formula I [wherein R is an optionally substd. monovalent hydrocarbon group such as an alkyl, alkenyl, aryl or haloalkyl group; and (n) is 1.9-2.1] having at least two alkenyl groups in the molecule is compounded with 5-100 pts.wt. powdered silica having a particle diameter of 50mum or lower and a specific surface area of 50m<2>/g or higher, 0.1-20 pts.wt. epoxidized organosilicon compd. selected from compds. of formulas II-V (wherein Me is methyl; and Vi is vinyl), and a curative in an amt. of 0.1-500ppm based on the organopolysiloxane to give the objective compsn., which gives a silicone rubber coating film exhibiting a strength of adhesion to a synthetic fabric for an air bag of at least 1.0kgf/cm.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a silicone rubber coating composition for air bags of vehicles and the like. More specifically, the present invention relates to a silicone coating composition for an air bag of a vehicle or the like, which has an adhesive strength capable of withstanding the impact of extension, particularly extension at high temperature.

[0002]

2. Description of the Related Art In recent years, an air bag has been put into practical use as a safety device for protecting an occupant of an automobile. Such an air bag is generally composed of a base fabric obtained by coating nylon fabric with chloroprene rubber.
However, the base cloth coated with this chloroprene rubber has a drawback in that it is difficult to reduce the weight, and in particular, the physical properties are deteriorated over time. Further, recently, an air bag base cloth coated with silicone rubber has been proposed (see Japanese Patent Laid-Open No. 63-78744). The air bag base cloth coated with the silicone rubber has an advantage that it is excellent in high temperature characteristics, and further, the silicone rubber has an advantage that it can be made lighter because it can be coated with a thin film. However, this silicone rubber has a drawback in that it has insufficient adhesion to synthetic fiber fabrics for air bags such as nylon 66. That is, when the air bag is operated, there is a problem that the rubber layer is peeled off or burned out due to the high temperature gas generated from the inside of the inflator and the intense friction between the coating surfaces during the expansion.

[0003]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention As a result of research to solve the above-mentioned problems, the present inventors have found that a silicone rubber composition containing a specific organosilicon compound added thereto is used as a synthetic fiber fabric for an air bag. The inventors of the present invention have found that they firmly adhere to each other and have excellent thin film coating properties, and have completed the present invention. That is, the object of the present invention is to provide an air bag base fabric which exhibits excellent adhesive strength to synthetic fiber fabrics for air bags, and has excellent foldability (flexibility) and extensibility, and which is less likely to deteriorate over time. Another object is to provide a obtainable silicone rubber coating composition for an air bag.

[0004]

Means for Solving the Problem and Its Action The above objects are: (A) 100 parts by weight of organopolysiloxane containing two or more alkenyl groups in one molecule, (B) 5 to 100 parts by weight of finely divided silica. Parts, (C) an organosilicon compound containing an epoxy group, 0.1 to 20 parts by weight, (D) a curing agent, which is achieved by a silicone rubber coating agent composition for an air bag, the amount being sufficient to cure the composition of the present invention. can do.

The organopolysiloxane of the component (A) used in the present invention is a main component of the composition of the present invention, and since the composition of the present invention becomes a silicone rubber coating film having rubber elasticity after curing. It is necessary to have two or more alkenyl groups in one molecule. Such an organopolysiloxane has the general formula

[Formula 1] [In the formula, R is an alkyl group such as a methyl group, an ethyl group and a propyl group; an alkenyl group such as a vinyl group and an allyl group; an aryl group such as a phenyl group; and a halogenated alkyl such as a 3,3,3-tripropyl group. It is a substituted or unsubstituted monovalent hydrocarbon group exemplified by the group. n is 1.9 to 2.1. ] It is a substantially linear organopolysiloxane represented by these. Regarding the viscosity of this organopolysiloxane, those having a viscosity at 25 ° C. of 100 centipoises or more are preferably used, and considering the strength of the silicone rubber coating film and the workability of compounding, those having a viscosity at 25 ° C. of 5000 centipoises or more are more preferable. . Specific examples of this component include, for example, dimethylpolysiloxane blocked with dimethylvinylsiloxy groups at both ends, dimethylsiloxane / methylvinylsiloxane copolymers blocked with dimethylvinylsiloxy groups at both ends, dimethylsiloxane / methylphenylsiloxane blocked with dimethylvinylsiloxy groups at both ends. A copolymer is mentioned.

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

The epoxy group-containing organosilicon compound of the component (C) used in the present invention is an essential component for improving the adhesiveness to synthetic fiber fabrics for air bags, and γ-glycidoxypropyltriene. Methoxysilane,
Epoxy group-containing organoalkoxysilane such as 3,4-epoxycyclohexylethyltrimethoxysilane; epoxy group-containing organopolysiloxane having vinyl group and alkoxy group, silicon atom-bonded epoxy group-containing organopolysiloxane, silicon atom-bonded Examples thereof include epoxy group-containing organopolysiloxanes such as epoxy group-containing organopolysiloxanes having a hydrogen atom and an alkoxy group. Among these, the following compounds are exemplified as specific examples of the epoxy group-containing organopolysiloxane.

[Chemical 1]

[Chemical 2]

[Chemical 3]

[Chemical 4]

The curing agent of the component (D) used in the present invention is
A catalyst or a mixture of a catalyst and a cross-linking agent for curing the composition of the present invention, which is used for curing an ordinary organopolysiloxane composition for silicone rubber, can be used. As such a curing agent, there is a combination of a platinum compound catalyst and at least two silicon atom-bonded hydrogen atom-containing organohydrogenpolysiloxanes in one molecule, and an organic peroxide.

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

Organohydrogenpolysiloxanes containing at least two silicon-bonded hydrogen atoms in one molecule include methylhydrogenpolysiloxanes capped at both ends with trimethylsiloxy groups and dimethylsiloxane capped with trimethylsiloxys at both ends and methylhydrogensiloxane. Polymer, dimethylphenylsiloxy group-blocked methylphenylsiloxane / methylhydrogensiloxane copolymer, cyclic methylhydrogenpolysiloxane, dimethylhydrogensiloxy unit and SiO
_A copolymer composed of _4/2 units is exemplified. The amount of the organohydrogenpolysiloxane blended is such that the ratio of the number of moles of silicon-bonded hydrogen atoms in the organohydrogenpolysiloxane to the number of moles of alkenyl groups in the component (A) is (0.6: 1) to An amount of (20: 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, these curing agents are preferably a combination of the former platinum-based compound catalyst and an organohydrogenpolysiloxane containing at least two silicon-bonded hydrogen atoms in one molecule.

The composition of the present invention comprises the above-mentioned components (A) to (D). In addition to the above-mentioned components (A) to (D), an organopolysiloxane resin is added as a component (E). It is preferable to mix them. In particular, it is preferable to use a platinum catalyst and an organohydrogenpolysiloxane as a curing agent for the component (D) because a silicone rubber coating film having high strength can be obtained. Examples of such an organopolysiloxane resin include (C
H ₃ ) ₃ SiO _1/2 unit and SiO _4/2 unit resin,
(CH ₃ ) ₃ SiO _1/2 units and (CH ₂ = CH) SiO _3/2
Resin consisting of units and SiO _4/2 units, (CH ₂ = CH)
Resin composed of (CH ₃ ) ₂ SiO _1/2 unit and SiO _4/2 unit, (CH ₂ ═CH) (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, a resin containing a vinyl group is preferable.

In order to produce the composition of the present invention, for example, the components (A) and (B) or the components (A), (B) and (E) are preliminarily rolled with two rolls, a kneader mixer, and a pressurizer. After uniformly kneading with a mixer such as a kneader mixer or a Ross mixer to prepare a silicone rubber base, it is advisable to add (C) component and (D) component thereto.

The composition of the present invention is used as a synthetic fiber fabric for an air bag (eg, nylon 6, nylon 66, nylon 46).
Such as polyamide fiber woven fabric, aramid fiber woven fabric, polyester fiber woven fabric represented by polyalkylene terephthalate, polyetherimide fiber woven fabric, sulfone-based fiber woven fabric, carbon fiber woven fabric, etc. Airbag base fabric can be obtained. Incidentally, in applying the composition of the present invention to a synthetic fiber woven fabric for an air bag, the most preferable air bag woven fabric is a nylon 66 fiber woven fabric. When a synthetic fiber fabric for an air bag is coated with the organopolysiloxane composition, 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 coated.

In the composition of the present invention, various additives conventionally known as additives for silicone rubber, for example, titanium oxide, carbon black, rouge, rare earth oxides, inorganic fillers such as cerium silanolate, and pigments. Addition of a heat-resistant agent or a heat-resistant agent may be carried out without impairing the object of the present invention.

If necessary, an organic solvent, a pigment, a heat-resistant agent, etc. are added to the above-mentioned components (A) to (D) or (A) to (E), and they are mixed uniformly, and then synthetic fibers for an air bag. The fabric can be coated, placed in a hot air drying oven and cured by heating to give a silicone rubber coated base fabric for an air bag. In the composition of the present invention as described above, the hardness (JIS A) of the silicone rubber after heat curing is preferably within the range of 30 to 60. When this is applied to a synthetic fiber woven fabric for air bags, the silicone rubber coating film and the synthetic fiber woven fabric for air bags 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 abrasion during the operation of the air bag.

[0016]

EXAMPLES The present invention will now be described with reference to examples. In the examples, “parts” means “parts by weight”, and the viscosity is 25 ° C.
Where cst represents centistokes. Further, Me represents a methyl group and Vi group represents a vinyl group.

[0017]

Example 1 Dimethylsiloxane unit 99.85 mol%
And a methyl vinyl siloxane unit of 0.15 mol%, both ends of which a trimethylsiloxy group-blocked dimethyl siloxane / methyl vinyl siloxane copolymer raw rubber
00) 100 parts, 7.0 parts of dimethylpolysiloxane blocked with silanol groups at both ends and 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 and heated until uniform. Kneaded to make a rubber base. 30 parts of this rubber base was dissolved in 70 parts of toluene with stirring at room temperature. Subsequently, 100 parts of this dispersion solution had an average molecular formula of Me ₃ SiO (MeHSiO) ₆ (Me ₂ SiO) ₄ SiM.
methyl hydrogen polysiloxane represented by e ₃ 1.0
Part, a complex of chloroplatinic acid and divinyltetramethyldisiloxane 0.5 part (platinum concentration 0.4% by weight) and 3,5-dimethyl-1-hexyne-3-ol 0.4 as a curing inhibitor
Parts were added and mixed uniformly. The viscosity of this dispersion solution was 50,000 cst. Furthermore, the following adhesion-imparting agents were added to this dispersion solution to prepare a silicone rubber coating composition. Then, this was coated on a nylon 66 (420 denier) fabric for an air bag, and its adhesive strength was measured. Here, the method for coating the nylon 66 woven fabric for an air bag is such that the coating amount of the silicone rubber composition is 50 to 60 g / m ² using a coater and air-drying in an oven at 120 ° C. for 4 minutes, 1
An air bag coating base fabric was prepared by heat curing at 80 ° C. for 5 minutes. The two coated surfaces of this air bag coated base fabric are overlapped, and the space between them is bonded with a room temperature curable silicone rubber adhesive [Toray Dow Corning Silicone Co., Ltd., trade name "SE9145 RTV"], and at room temperature 7 After curing for a day, a peel test was performed by cutting into a width of 2.5 cm and a length of 10 cm, and the adhesive strength at that time was measured. In the air bag inflation test, hot air with a temperature of 170 to 180 ° C. is applied to the air bag at a pressure of 7 to 8
By blowing under the condition of kg / cm ^2, the film was momentarily inflated, and the presence or absence of peeling of the silicone rubber coating film was visually observed. The results of these evaluations are shown in Table 1. Adhesion imparting agent (a) γ-glycidoxypropyltrimethoxysilane Adhesion imparting agent (b)

[Chemical 5] Adhesion imparting agent (c)

[Chemical 6] Adhesion imparting agent (d) 50 parts of γ-glycidoxypropyltrimethoxysilane and the average unit formula are

[Chemical 7] A mixture of 50 parts of a siloxane oligomer represented by

[Table 1]

[0018]

Example 2 The silicone rubber coating composition obtained in Example 1 was coated on a polyester fiber woven fabric for air bags (420 denier) in the same manner as in Example 1 and the properties thereof were determined in the same manner as in Example 1. It was measured. The evaluation results are shown in Table 2.

[Table 2]

[0019]

Example 3 73 parts of dimethylpolysiloxane having a viscosity of 12000 cst in which both ends of the molecular chain were blocked with dimethylvinylsiloxy group, Vi (Me) ₂ SiO _1/2 unit and SiO _4/2
27 parts of a vinyl group-containing methylpolysiloxane resin (Vi weight 5.6%, viscosity 230 cst) consisting of units was put in a Ross mixer. Next, 12 parts of fumed silica having a specific surface area of 200 m ² / g, which had been previously treated with hexamethyldisilazane, was added thereto and kneaded under heating until the mixture became uniform to prepare a liquid silicone rubber base having fluidity. Next, 100 parts of this liquid silicone rubber base has an average molecular formula of Me ₃ SiO (MeHSiO) ₆ (Me ₂ SiO) ₄ SiM.
methyl hydrogen polysiloxane represented by e ₃ 4.2
Parts, platinum complex of chloroplatinic acid and vinyltetramethyldisiloxane 0.5 part (platinum concentration 0.4% by weight) and 3,5-dimethyl-1-hexyne-3-ol as a curing inhibitor.
4 parts were added and mixed uniformly. The viscosity of this liquid silicone rubber composition was 30,000 cst. A silicone rubber coating agent composition was prepared by adding the same adhesion-imparting agent as in Example 1 to this composition. This was then coated onto a nylon 66 fiber fabric and cured by heating at 180 ° C for 5 minutes. Since this silicone rubber-coated base fabric cannot be bonded with the room temperature-curable silicone rubber adhesive used in Example 1 and direct adhesive strength cannot be measured, a scrubbing tester is used to perform a scrubbing test. The peeling condition of the rubber coating film from the cloth surface was visually judged. In this rubbing test, judgment was made after 1000 rubbing tests with a pressing force of 2 kgf. The results of these measurements are shown in Table 3.

[Table 3]

[0020]

The silicone rubber coating composition for air bags of the present invention comprises the components (A) to (D), and particularly contains the epoxy group-containing organosilicon compound as the component (C). It has excellent adhesion to synthetic fiber fabrics such as 66 made of synthetic fiber fabrics for air bags, and the silicone rubber coating film peels off due to the high temperature gas generated from the inflator and the intense friction between the coating surfaces during expansion. The feature is that it does not burn out.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hiroshi Honma             2-2 Chikusaigan, Ichihara-shi, Chiba Toray Dow             Corning Silicone Co., Ltd. R & D             In headquarters

Claims (3)

[Claims] 1. (A) An organopolysiloxane containing two or more alkenyl groups in one molecule.
100 parts by weight, (B) fine powder silica
5 to 100 parts by weight, (C) an epoxy group-containing organosilicon compound
0.1 to 20 parts by weight, (D) curing agent A silicone rubber coating agent composition for air bags, which is contained in an amount sufficient to cure the composition of the present invention. 2. The silicone rubber coating composition for an air bag according to claim 1, wherein the organosilicon compound as the component (C) is an organosilicon compound containing an epoxy group and a silicon atom-bonded alkoxy group. 3. The silicone rubber coating composition for an air bag according to claim 1, wherein the silicone rubber coating film has an adhesive strength of 1.0 kgf / cm or more with respect to the synthetic fabric for an air bag.