JP2570055B2 - Coating composition for airbag and airbag - Google Patents

Abstract

PURPOSE:To provide the air bag coating composition having excellent adhesiveness to air bag basic fabrics, capable of forming silicone cured coating films having no tacky touch on the surfaces and having good workability, and the air bag using the same. CONSTITUTION:A coating composition for air bags comprises (A) 100 pts.wt. of a organopolysiloxane represented by a composition of the formula I (R<1> is non-substituted or substituted monovalent hydrocarbon group, preferably >=50% of the group being methyl; a is a positive integer of 1.98-2.01) and having a viscosity (25 deg.C) of >=3000cs (at 25 deg.C), (B) 0.1-5 pts.wt. of an organosilane containing an isocyanate group and hydrolyzable groups in the molecule or its partial hydrolysate, (C) 0.1-5 pts. wt. of an organic peroxide and (D) 0.1-10 pts.wt. of an organohydrogenpolysiloxane [e.g. a compound of formula III (l is an integer of 1-200)] containing three or more of H atoms bonded to Si in the molecule. The cured coating film of the composition is formed on air bag basic fabric to provide the air bag.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an airbag coating composition capable of forming a silicone cured film having good adhesion and no surface tackiness on an airbag base fabric, and a cured film of the composition. The present invention relates to an airbag formed on an airbag base fabric.

[0002]

2. Description of the Related Art In recent years, an airbag has been used which is folded into a steering wheel of an automobile or the like and opened between the steering wheel and the human body by a shock such as a collision to relieve an impact on the human body. This airbag is generally formed of nylon cloth coated with chloroprene. However, the heat resistance and weather resistance of chloroprene rubber are insufficient, and there is a problem that the life of the airbag is short.

[0003] Further, in order to make the airbag less susceptible to fire and blast generated in the event of a collision of an automobile or the like, it is necessary to impart flame retardancy to the airbag, and a cloth coated with chloroprene rubber is required. In the produced conventional airbag, since the chloroprene rubber does not have sufficient flame retardancy, a silicone flame retardant is further coated on a portion to be exposed to the blast.

On the other hand, in the case of an airbag coated with silicone rubber, it is possible to impart flame retardancy to the silicone rubber itself by adding a known flame retardant to the silicone rubber. There is an advantage that there is no. Therefore, recently, silicone rubber coating agents having excellent heat resistance and weather resistance have been attracting attention as coating agents for airbags.

However, the problem with silicone rubber is that its adhesion to a base fabric made of polyamide fibers such as nylon is weaker than that of a chloroprene rubber coating agent. Has been studied, but the process is complicated, and there are many problems such as the deterioration of the working environment due to the use of an organic solvent.Therefore, no primer treatment is required, that is, a silicone rubber having self-adhesiveness. A coating agent was required.

A silicone rubber composition which can be used as a coating agent having such self-adhesive properties includes vinyl tris (t-butylperoxy) as an adhesiveness-imparting component.
A silicone rubber composition to which acrylperoxysilanes such as silane, triphenyl (t-butylperoxy) silane, trimethyl (t-butylperoxy) silane and methylvinyldi (t-butylperoxy) silane are added, vinyltrimethoxy Silane, vinyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane,
A silicone rubber composition to which a silane coupling agent such as γ-methacryloxypropyltrimethoxysilane is added, and further a vinylsilyl group-containing benzoate compound, for example, a vinylsilyl group-containing benzoate compound such as t-butylperoxy-4-vinyldimethylsilylbenzoate. There is known a silicone rubber composition which serves as an adhesive component and a vulcanizing agent.

[0007]

However, the self-adhesive silicone rubber composition to which the above-mentioned alkylperoxysilanes are added does not have sufficient adhesiveness, and the self-adhesive silicone rubber to which a silane coupling agent is added. There is a problem that the composition has insufficient adhesiveness and adhesive durability.

In general, when the silicone rubber composition is cured by a method such as HAV (normal pressure hot air vulcanization method) using an organic peroxide as a vulcanizing agent, the silicone rubber composition coated on a substrate The surface hardening of the product may be inhibited by oxygen in the air. For this reason, the ultrathin molded film formed of the silicone rubber composition has a tacky feeling on the surface as compared with the molded film formed of the chloroprene rubber composition, and thus the base fabric for an airbag is coated with a conventional silicone rubber coating agent. There is a concern that when the airbag is folded up and folded into the handle of an automobile or the like, it is difficult to tear when necessary.

[0009] Accordingly, from the above points, as the silicone rubber composition which can be used as a coating agent, a two-part mixed type platinum addition-curable silicone rubber composition is mainly used. The presence of a compound that is an additional poison in the environment causes significant hardening inhibition and often has a short pot life after mixing the two solutions, making it difficult to work continuously for a long time and to store after mixing the two solutions. There's a problem. Therefore, there is an urgent need to develop a silicone coating agent for airbags that has a long pot life even after the addition of a vulcanizing agent and does not adversely affect the working environment.

The present invention has been made in view of the above circumstances,
An airbag coating composition having excellent adhesion to an airbag base fabric such as polyamide and polyester, capable of forming a silicone cured film having no surface tackiness, and having good workability. An object of the present invention is to provide an airbag having a cured film of the composition formed thereon.

[0011]

The present inventors have conducted intensive studies in order to achieve the above object. As a result, (A) the viscosity at 25 ° C. represented by the following average composition formula (1) was 30.
An organopolysiloxane of at least 0 centistokes,
(B) an organosilane containing an isocyanate group and a hydrolyzable group in one molecule or a partial hydrolyzate thereof;
A composition containing (C) an organic peroxide and (D) an organohydrogenpolysiloxane containing three or more hydrogen atoms bonded to a silicon atom in one molecule has self-adhesiveness,
This is coated on an airbag base fabric and cured, so that the surface of the base fabric is uniformly and uniformly dispersed by the organosilane or its partial hydrolyzate as the component (B) and the organohydrogenpolysiloxane as the component (D). Strongly adheres, especially excellent in adhesiveness over time under high humidity,
The addition of the component (D) forms a cured film having an improved tackiness on the surface as compared with a conventional silicone rubber coating agent, and is excellent in flame retardancy. The present inventors have found that the present invention is effective as a product, and have accomplished the present invention.

[0012]

Embedded image (In the formula, R ¹ represents the same or different unsubstituted or substituted monovalent hydrocarbon group, and a represents a positive number of 1.98 to 2.01.)

Hereinafter, the present invention will be described in more detail. The coating composition for an airbag of the present invention has (A) a viscosity of 300 cS at 25 ° C. represented by the average composition formula (1).
The above organopolysiloxane, (B) an organosilane containing an isocyanate group and a hydrolyzable group in one molecule or a partial hydrolyzate thereof, (C) an organic peroxide,
(D) An organohydrogenpolysiloxane containing three or more hydrogen atoms bonded to a silicon atom in one molecule.

Here, the organopolysiloxane of the component (A) is represented by the following general formula.

[0015]

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Here, R ¹ is the same or different and is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 12 carbon atoms, preferably 1 to 6 carbon atoms. Examples of such a monovalent hydrocarbon group include an alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group and a hexyl group; a cycloalkyl group such as a cyclohexyl group; an alkenyl group such as a vinyl group and an allyl group; An aryl group such as a tolyl group, and a chloromethyl group, a trifluoropropyl group, a cyanoethyl group, and the like, in which some or all of the hydrogen atoms of these groups are substituted with a halogen atom, a cyano group, or the like, can be given. In this case, R ¹ is preferably a methyl group, an ethyl group, a phenyl group, a γ-trifluoropropyl group, a cyanoethyl group, a vinyl group, or an allyl group.
It is preferred to contain at least mol%. When the content of methyl group is 5
If it is less than 0 mol%, the original characteristics of methylpolysiloxane may be lost, and the raw material cost may be high. In the equation (1), a is 1.9.
It is a positive number in the range of 8 to 2.01.

The viscosity of the organopolysiloxane (A) at 25 ° C. is 300 cS or more.
It is preferably set to × 10 ⁴ to 10 ⁸ cS. Viscosity is 30
When it is less than 0 cS, when this coating composition is coated on a base fabric, the formed film has insufficient mechanical strength and is not practical.

The structure of the organopolysiloxane is preferably substantially linear. Further, the terminal of the molecular chain is preferably blocked with a silanol group, a trimethylsilyl group, a dimethylsilyl group, a methyldivinylsilyl group, a trivinylsilyl group, or the like, and is preferably blocked with a trivinylsilyl group. . As such an organopolysiloxane, a product produced by a known method of subjecting a cyclic polysiloxane well-known as an oligomer to ring-opening polymerization in the presence of an acid or an alkali can be used.

As the organosilane (B), those represented by the following general formula (2) can be used.

[0020]

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Here, R ² and R ³ are the same substituted or unsubstituted monovalent hydrocarbon groups as R ^1, and those described above are exemplified. Further, methoxymethyl group, ethoxymethyl group,
Examples thereof include a C _1-10 alkoxy-substituted C _1-10 alkyl group such as a methoxyethyl group, and a C _7-20 aralkyl group such as a phenylethyl group. Examples of the hydrolyzable group represented by OR ³ include a C _1-10 alkoxy group, a C _2-10 alkenyloxy group,
Examples thereof include a C _6-16 aryloxy group, a C _1-10 alkoxy-substituted C _1-10 alkoxy group, and a C _7-17 aralkyloxy group. R ⁴ is a divalent hydrocarbon group having 1 to 10 carbon atoms such as an alkylene group such as a methylene group, an ethylene group or a propylene group, an arylene group such as a phenylene group, or a sulfur-substituted divalent hydrocarbon group. B is 0, 1 or 2.
(B) it is specifically as organo silane components are exemplified those described below, (B) component alone hydrolyzate of the organosilane or _{^{(R 3 O) 2 SiR 2}} 2, (R
^It may be a hydrolyzate of a mixed silane with ³ O) ₃ SiR ² or the like.

[0022]

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The amount of the component (B) is 100 parts by weight (parts by weight) of the organopolysiloxane as the component (A).
The same applies hereinafter) to 0.1 to 20 parts, especially 0.5 to 10 parts.
It is preferable to use a part. If the amount is less than 0.1 part, sufficient adhesive strength cannot be given to the coating composition. If the amount exceeds 20 parts, the cured product obtained by curing the coating composition has tensile strength, elongation, heat resistance, etc. Properties may be reduced.

The organic peroxide as the component (C) is a vulcanizing agent, such as benzoyl peroxide, 2,4-dichlorobenzoyl peroxide, orthochlorobenzoyl peroxide, di-t-butyl peroxide, dicumyl peroxide. Oxide, t-butyl perbenzoate, t-
Conventionally known compounds such as butyl peracetate, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, and (t-butylperoxy) myristyl carbonate are exemplified.

The amount of component (C) is preferably 0.1 to 5 parts, more preferably 0.5 to 3 parts, per 100 parts of component (A). If the amount is less than 0.1 part, the vulcanization is insufficient, and the strength of the coating film may be reduced or the tackiness may be increased. If the amount exceeds 5 parts, the coating film of the cured product obtained by curing the coating composition may not be used. Tensile strength and elongation may decrease.

As the organohydrogenpolysiloxane as the component (D), those represented by the following general formula (3) can be used.

[0027]

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Here, R ⁵ is preferably an alkyl group having 1 to 10 carbon atoms such as a methyl group, c and d are positive numbers and c + d = 1.
To 3 and contains at least three or more hydrogen atoms (≡SiH) bonded to silicon atoms in one molecule. Specific examples of such an organohydrogenpolysiloxane include compounds having the following structural formula.

[0029]

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The amount of component (D) is preferably 0.1 to 10 parts, more preferably 1 to 5 parts, per 100 parts of component (A). If the amount of the component (D) is less than 0.1 part, tackiness may remain on the surface, and if the amount exceeds 10 parts, the tensile strength and elongation of the cured film of the coating composition are reduced. There are cases.

The coating composition of the present invention has, in addition to the components (A) to (D) described above,
Platinum compounds such as platinum fine powder, chloroplatinic acid, and chloroplatinic acid-olefin complex compound can be added. The amount of these components is 0.001 to 5 parts per 100 parts of component (A).
Parts, particularly preferably 0.05 to 0.5 part.

When the above-mentioned platinum or a platinum compound is added, there is a risk that scorch or the like may be generated during storage of the composition. To prevent this, the hydroxyl groups of methylvinylsiloxane, acetylene alcohol, and acetylene alcohol are reduced. It is preferable to use a reaction control agent such as one blocked with a trimethylsilyl group. The amount of the reaction control agent is preferably 0.01 to 10 parts, more preferably 0.05 to 5 parts, per 100 parts of the component (A).

Further, it is preferable to add a filler to the above coating composition. By adding the filler, the viscosity of the coating composition can be increased to improve the workability during coating, and the curing Physical properties such as hardness, tensile strength and elongation of the object can be improved. The filler can be blended in the form of fine particles or fibers, and specifically, as the filler, fumed silica, precipitated silica, quartz powder, diatomaceous earth, hollow glass spheres, iron oxide, zinc oxide, Examples include titanium oxide, magnesium oxide, talc, aluminum silicate, alumina, calcium carbonate, carbon black, asbestos, glass fiber, carbon fiber, polyester fiber, polytetrafluoroethylene powder, and polyvinyl chloride powder. Further, a resin-like polysiloxane which is a copolymer such as R ³ SiO _0.5 , R ² SiO, and RSiO _1.5 (R is a monovalent hydrocarbon group) can be blended as a filler. The amount of these fillers is determined by the amount of the organopolysiloxane 1 (A).
It is preferably 20 to 200 parts, more preferably 30 to 100 parts, per 00 parts. Less than 20 parts or 200
If the amount exceeds the range, sufficient physical properties may not be obtained. The average particle diameter of these fillers is preferably 50 μm or less.

Further, the coating composition of the present invention includes:
Depending on the purpose of use, known additives usually added to this type of coating composition may be added. For example,
silane coupling agents such as γ-glycidoxypropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltrimethoxysilane, vinyltrialkoxysilane, metal salts such as organic carboxylic acids, titanates, heat resistance Agents, flame retardants, dispersants, and the like. Note that examples of the dispersant include diphenylsilanediol, various alkoxysilanes, carbon functional silane, low molecular weight siloxane containing silanol, and the like.

The coating composition of the present invention is produced by kneading the above components, and is used for coating the base fabric for various airbags such as nylon. In this case, the composition is prepared using an appropriate organic solvent. It is preferable to use it after dissolving it. As the organic solvent, those having no active hydrogen that reacts with the organosilane as the component (B) are preferable. Specifically, benzene, toluene, xylene, hexane, heptane, kerosene and the like can be used. In this case, the amount of the organic solvent to be used is preferably 10 to 1000 parts, more preferably 100 to 300 parts, per 100 parts of the composition.

As a base fabric for an airbag on which a cured film of the coating composition is formed, fibers such as nylon, tetron, vinylon, polyester, and polyurethane or a woven fabric made of the fibers can be used. Of these, nylon and polyester are particularly preferred.

The composition can be coated on the base fabric by calendering, knife coating, brushing, dip coating, spraying, or the like. When the composition is in a solid state, as described above, It is preferable to employ a coating method such as knife coating, brush coating, dip coating, spraying or the like after dissolving in an organic solvent.

As a method of curing the coating composition, a method of vulcanizing with hot air at 110 to 150 ° C. for several seconds to 20 minutes is suitably adopted, whereby various types of silicone rubber, silicone resin, silicone gel, etc. are used depending on the components used. A cured product having a crosslinking density of

[0039]

EXAMPLES The present invention will be described below in detail with reference to examples and comparative examples, but the present invention is not limited to the following examples. In addition, in the following examples, the viscosity indicates a measured value at 25 ° C.

[Examples and Comparative Examples 1 and 2] 25% by weight toluene composed of 99.8 mol% of dimethylsiloxane units and 0.2 mol% of vinylmethylsiloxane units and having a molecular chain terminal blocked with a vinyldimethylsilyl group 100 parts of an organopolysiloxane having a relative viscosity of 2.8 in a solution was treated with a trimethylsilyl group to give a specific surface area of 23 parts.
40 parts of 0 m ² / g of hydrophobic fumed silica and 1.0 part of α, ω-dimethylpolysiloxanediol whose molecular chain ends are blocked with silanol groups are added, and heat-treated at 180 ° C. for 2 hours in a kneader. Compound A was made.

Next, 3.5 parts of organic peroxide 2,4-dichlorobenzoyl peroxide having a pure content of 50% was added to 100 parts of the compound A, and the mixture was uniformly kneaded. It was dissolved in toluene to prepare a toluene solution (I) having a silicone content of 25% by weight. The formula (C ₂ H ₅ ) was added to 100 parts of this toluene solution (I).
O) ₃ Si (CH ₂ ) ₃ NCO-containing isocyanate group-containing silane represented by the following formula:
And 5 parts by weight of an organohydrogenpolysiloxane having both ends capped with a trimersilyl group represented by the following formula (4). (Example).

[0042]

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For comparison, a sample prepared in the same manner as above except that no isocyanate group-containing silane and organohydrogenpolysiloxane were blended (Comparative Example 1) and a sample prepared in the same manner as above except that no organohydrogenpolysiloxane was blended A sample (Comparative Example 2) was produced.

The above sample had a linear density of 18 × 17 lines / 25 m.
100 μm thick on one side of a plain weave nylon fiber fabric
(At the time of drying) and air-dried at 25 ° C. for 30 minutes.
It was vulcanized by heating at 80 ° C. for 7 minutes.

Next, the cured physical properties of these samples were measured. FIG. 1 (In FIG. 1, 1 is a nylon fiber fabric,
2 is a cured silicone film, 3 is a scratching device made of stainless steel, and 4 is a weight for applying a load to the device 3. As shown in), a predetermined portion of the silicone cured film surface was scratched with a stainless steel device under a load of 200 g, and the number of times of the scratching until the silicone cured film was completely peeled off from the nylon fiber fabric was measured. Gender. Each sample was kept at 85 ° C and 95% humidity.
After keeping each sample in the RH state for one week to swell each sample, the same adhesion test as described above was performed, and the adhesion after wetting was measured.

As shown in FIG. 2, the surfaces of the nylon fiber woven fabric 1 covered with the silicone cured film 2 are adhered to each other, and are applied at 25 ° C. under a load of 20 kgf / cm ^2.
After crimping for 2 hours, cut into 2.5cm width to make a test piece,
The tackiness of the surface of the cured silicone film was examined by performing a 180 ° peel test at a rate of 10 mm / min using a tensile tester and measuring the load. Table 1 shows the results.

[0047]

[Table 1]

[0048]

The coating composition for airbags of the present invention is excellent in self-adhesiveness, shows a strong and stable adhesiveness to base cloths such as polyamide and polyester over time, and has an organic peroxide-based composition. Even when the vulcanizing agent is used, it has excellent surface curability, and therefore has less surface tack than the conventional one.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a cured physical property test in Examples and Comparative Examples of the present invention.

FIG. 2 is an explanatory diagram of a surface tackiness test in Examples and Comparative Examples of the present invention.

Continuation of the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location C09D 183/08 C09D 183/08 D06M 15/643 D06M 15/643 // B32B 27/00 101 B32B 27/00 101 D06M 15/643

Claims (2)

(57) [Claims] 1. An organopolysiloxane having a viscosity at 25 ° C. of 300 centistokes or more represented by the following average composition formula (1): (A) an isocyanate group and a hydrolyzable group in one molecule. Or a partially hydrolyzed product thereof, (C) an organic peroxide, and (D) an organohydrogenpolysiloxane containing at least three hydrogen atoms bonded to a silicon atom in one molecule. Airbag coating composition. Embedded image (In the formula, R ¹ represents the same or different unsubstituted or substituted monovalent hydrocarbon group, and a represents a positive number of 1.98 to 2.01.) 2. An airbag obtained by forming a cured film of the coating composition for an airbag according to claim 1 on an airbag base fabric.