JP2001287610A - Coating composition for air bag, and air bag - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide ground fabric for an air bag excellent in a weight-reducing property, flexibility and compactness, and satisfying burning velocity provided by the FMVSS302 even in a small applied amount such as 20 g/m2 or less of coating resin-applied amount, and a coating composition for the air bag used for the ground fabric. SOLUTION: This coating composition for the air bag is prepared by adding (A) an organopolysiloxane having 10,000 cP or less of viscosity at 25 deg.C and having vinyl groups bonded to SiC in its terminal units, (B) an organopolysiloxane having at least three hydrogen atoms bonded to Si, (C) a catalyst for promoting an addition of the Si-bonded hydrogen atom to an aliphatic multiple bond, (D) an organic silicon compound, and (E) a silicone resin, and the ground fabric of the air bag is provided by applying this composition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a base fabric for an airbag which is installed to ensure the safety of an occupant in the event of an automobile collision. More specifically, the present invention relates to a lightweight, flexible, and compact airbag. The amount of resin applied is 20 g /
The present invention relates to a base fabric for an airbag and a coating composition for an airbag that satisfy the burning rate determined by the FMVSS 302 even in a small amount such as m ² or less.

[0002]

2. Description of the Related Art Airbags have been increasingly used as occupant protection and safety devices for automobiles. Since the airbag is usually mounted as a module including an inflator case in a narrow place such as a steering wheel or an instrument panel, it is desirable that the storage volume of the airbag be small. Therefore, in order to make the storage volume compact, use fibers of fine size as fibers used in the woven fabric, and change the type and amount of the elastomer applied to the base fabric to maintain the airtightness of the airbag. Things have been done.

For example, a fiber used for a woven fabric is 940 dt.
ex to 470 dtex base fabric. In addition, the amount of the elastomer resin to be applied and the amount of application are changed from applying 90 to 120 g / m ^{2 of} chloroprene to applying 40 to 60 g / m ^{2 of} the silicone resin. A base fabric is used, and a non-coated type having minute air permeability is used in view of improvement in compactness and economical cost of coating processing.

However, in the recent market, in order to further reduce the weight and size of the airbag, it is required to reduce the weight of the base fabric for the airbag and to soften the texture, and to reduce the cost of the coating process and the cost. There is a demand to reduce the amount of coating to reduce the weight of the coated cloth. However, when the application amount of the silicone composition is reduced, the burning rate increases, and a problem occurs that the burning rate does not satisfy the burning rate determined by FMVSS302.

[0005] As typical conventional techniques for solving this problem, there are JP-A-7-195990 and JP-A-7-300774. In these techniques, the terminal unit contained in the coating composition is SiC
Since the viscosity of the organopolysiloxane having a bonded vinyl group is large and the number of terminal double bonds is small, the crosslinking density is low. Therefore, by adding the fine powder silica as the film filler and the silicone resin as the film enhancer to the coating composition, the breakage of the coating resin film during the FMVSS302 combustion test is suppressed. However, with a small application amount such as 20 g / m ² or less, FMVS
In order to pass the S302 combustion test, it is necessary to contain a large amount of fine powder silica as a film filler, and in fact, there is a problem in the fixability of the fine powder silica.

[0006]

SUMMARY OF THE INVENTION The present invention provides an FMVSS having excellent lightness, flexibility, and compactness even if the coating amount of the coating resin is as small as 20 g / m ² or less.
A base fabric for an airbag that satisfies a combustion rate determined by 302;
And a coating composition for an airbag.

[0007]

Means for Solving the Problems The present inventors have conducted intensive studies in order to solve the above problems, and as a result, have found that the viscosity of an organopolysiloxane having a vinyl group having a SiC bond at the terminal unit is reduced to 10,000 centipoise or less. by doing,
Increase the terminal vinyl group, increase the crosslink density after vulcanization,
FMVSS302 Prevents the breakage of the silicone resin film in the combustion test, suppresses the diffusion of the combustion gas, and reduces the FM even when the coating amount of the coating resin is as small as 20 g / m ² or less.
The present inventors have found an airbag base fabric that satisfies the burning rate determined by VSS302, and have completed the present invention.

That is, the present invention is as follows. (1) (A) an organopolysiloxane having an SiC-bonded vinyl group at a terminal unit having a viscosity at 25 ° C. of 8000 centipoise or less, (B) an organopolysiloxane having at least three Si-bonded hydrogen atoms,
An airbag coating composition comprising (C) a catalyst for promoting the addition of a Si-bonded hydrogen atom to an aliphatic multiple bond, (D) an organosilicon compound, and (E) a silicone resin. object.

(2) A base fabric for an airbag, wherein the coating composition for an airbag according to the above (1) is applied to the base fabric in an amount of 20 g / m ² or less. (3) An airbag comprising the base fabric for an airbag described in (2). Hereinafter, the present invention will be described in detail. In the present invention,
The organopolysiloxane (A) having a vinyl group bonded to the terminal unit by SiC is a diorganopolysiloxane represented by the following general formula.

(CH_Two= CH)_XSiR_3-X-O (Si
R_TwoO)_nSiR_3-X(CH = CH _Two)_X Wherein R is the same or different hydrocarbon group
And may be substituted, and advantageously have 1 carbon atom
Represents a hydrocarbon group having １８18. X is 1, 2 or 3
And advantageously 1. n is diorganopolysilo
Xanx is less than 10,000 centipoise at 25 ° C.
(SiR at a polymerization degree such that_TwoO) the number
The viscosity at 25 ° C. of (A) is preferably 8,000
Or less, and more preferably 50 to 500.
It is 0 centipoise. Over 8000 centipoise
With low vinyl end groups and low crosslinking density after vulcanization
Therefore, the resin film formed by coating becomes weak,
g / m^TwoAt the following coating amount, the film is broken during the combustion test, and F
The combustion rate determined by MVSS302 can be satisfied.
Absent. Also, if the viscosity is too low, the coating composition
It tends to permeate the fabric and make film formation difficult.
You.

Examples of hydrocarbon radicals as R are advantageously:
Alkyl group, for example, methyl group, ethyl group, n-propyl group, isopropyl group, butyl group, octyl group, tetradecyl group or octadecyl group; alicyclic hydrocarbon group,
For example, a cyclopentyl group, a cyclohexyl group or a methylcyclohexyl group; an aryl group such as a phenyl group; an alkaryl group such as a tolyl group; an aralkyl group such as a benzyl group or a phenylethyl group.

Examples of the substituted hydrocarbon group as R include:
Advantageously, halogenated groups, for example 3,3,3-
Examples thereof include a trifluoropropyl group, a 3-chloropropyl group and a chlorophenyl group. A cyanoalkyl group, for example, a cyanoethyl group, may be included. Groups having an unsaturated aliphatic group, for example, a vinyl group, an allyl group, a hexenyl group or a cyclohexenyl group,
It may be contained similarly.

R is preferably a hydrocarbon group having 1 to 10 carbon atoms, and more preferably, at least 80% of the organic groups represented by R are methyl groups. The organopolysiloxane may be the same copolymer or a mixture of different copolymers having the same degree of polymerization or different degrees of polymerization. When the diorganopolysiloxane has different diorganopolysiloxane units, a random distribution may exist or a distribution by blocks may exist.

The organopolysiloxane (A) is preferably contained in the coating composition of the present invention in an amount of from 10 to 80% by weight, more preferably in an amount of from 20 to 50% by weight. In the present invention, the organopolysiloxane (B) having at least three Si-bonded hydrogen atoms is an organopolysiloxane represented by the following general formula.

(CH_Three)_ThreeSiO- (SiHRO)_O−
(SiR_TwoO)_P-Si (CH_Three) _Three [Wherein, R is the same as above, and o and p are 1: 0 to 1:
20, preferably in a ratio of 1: 0 to 1: 7]. The sum of o and p can be in the range of 10-1000.
And the preferred total is 20 to 200, more preferably
The total is 30 to 100. Si bond per molecule
Organopolysilo having at least three hydrogen atoms
In the case of a xanse, a hydrogen atom and a siloxane oxygen atom
Thus, organos having no saturated silicon valence
The polysiloxane is preferably methyl, ethyl or
Or saturated with a phenyl group. However
While containing all of the groups described as R above.
No.

The organopolysiloxane (B) is preferably contained in the coating composition of the present invention in an amount of 1 to 40% by weight, more preferably 3 to 15% by weight. In the present invention, Si to the aliphatic multiple bond
As the catalyst (C) for promoting the addition of the bonded hydrogen atom, any known catalyst for promoting the reaction can be used. Examples of such catalysts are the finely divided metals platinum (platinum sol), ruthenium, rhodium, palladium or iridium. These metals include solid supports, such as silicon dioxide, aluminum oxide or activated carbon,
It may be applied on a ceramic material or an oxide or hydroxide mixture.

Compounds or complexes of these metals, for example, platinum-olefin complexes, platinum-alcohol complexes, for example, Speyers Catalyst,
Platinum-alcoholate-complex, platinum-ether-complex, platinum-aldehyde-complex, platinum-ketone-complex, e.g.
Reaction products from cyclohexane and hexachloroplatinic acid, platinum-vinylsiloxane complexes, in particular platinum-divinyltetramethyldisiloxane complexes with or without organically bound halogen atoms, bis- (γ- (Picoline) -platinum dichloride, trimethylenepyridine platinum dichloride, dicyclopentadiene platinum dichloride, dimethylsulfoxydiethyleneplatinum (2) dichloride, and also the reaction product of platinum tetrachloride and secondary butylamine dissolved in 1-octene. It is also an example of the catalyst. Platinum compounds are particularly preferred as catalysts in the products according to the invention. The above catalysts can be used alone or as a mixture.

In the present invention, the silicone composition contains
If the catalyst is a platinum catalyst, the platinum content in the composition according to the invention is from 3 to 500 pp relative to the polysiloxane content.
m, and preferably has a platinum content of 10 to 200 based on the polysiloxane used.
ppm. In the present invention, the organosilicon compound (D) may be any compound suitable as an adhesion aid. By way of example, silanes having hydrolyzable groups and vinyl-, acryloxy-, methacryloxy-, epoxy- or acid anhydride groups linked to the silicon atom via a carbon atom can be used. It is also possible to use partial hydrolysates and / or hydrolysate mixtures of such silanes. Preferably, vinyltriacetoxysilane and the following formula [formula 1]:

[0019]

Embedded image

The reaction product from the silane represented by As (D), one kind can be used, but also a mixture of two or more kinds of silanes or a reaction product thereof, or a partial hydrolyzate or a mixture of hydrolysates can be used. it can.
(D) as these adhesion aids is preferably contained in the silicone composition in an amount of 1 to 20 wt%, more preferably 2 to 8 wt%.

The coating composition of the present invention has the general formula:
(R_ThreeSiO_1/2)_a(R_ThreeSiO _3/2)_bIndicated by
The silicone resin (E), that is, the general formula: (R_ThreeSi
O_1/2)_a(R_ThreeSiO_3/2)_bSo-called
Contains aqueous emulsion of MT resin and / or MQ resin
In this case, R is the same as described above,
And advantageously methyl, phenyl, vinyl or hydrogen
Is an atom. The ratio of a to b is 30 to 3 for the silicone resin.
Selected to be within the viscosity range of 00000 centipoise
And preferably has a viscosity of 50 to 30000 centipoise.
Degree within the range, more preferably 50 to 10,000 centimeters.
A silicone resin within the viscosity range of Chipois is selected.

The coating composition of the present invention may contain the components (A), (B), (C), (D) and (E), and may be a solvent-free system or a water-based emulsion. Alternatively, it can be used in a system diluted with a toluene-based organic solvent, but from the viewpoint of work safety and environmental pollution, a solvent-free system or a system in the form of an aqueous emulsion is preferable. When used as an aqueous emulsion, it is possible to use any of the emulsifiers normally used for preparing organopolysiloxane emulsions. Examples of this emulsifier include sulfonic acid and its salts that can act as emulsifiers, as well as alkyl sulfonates, such as sodium lauryl sulfonate, benzene sulfonates substituted with aliphatic hydrocarbon groups, such as sodium dodecylbenzene sulfonate, aliphatic Naphthalene sulfonate, polyethylene glycol sulfonate and lauryl phosphate substituted with hydrocarbon groups, polyethylene oxide, polypropylene oxide, copolymers of ethylene oxide and propylene oxide, stearate and phosphate.

Also, the coating composition of the present invention includes:
It may contain known thickeners, flame retardants, fillers, pigments and stabilizers in amounts not to impair the effects of the present invention.
In the airbag fabric of the present invention, the coating amount of the coating compositions are 20 g / m ² or less in terms of solid content, preferably 5 to 15 g / m ^2. If it exceeds 20 g / m ² , the weight of the base fabric for an airbag and the softness of the hand become insufficient, and the cost of coating increases.
On the other hand, if the coating amount is too small, the flame retardancy becomes insufficient.

The fibers constituting the base fabric for an airbag of the present invention are not particularly limited, but fibers mainly composed of polyhexamethylene adipamide are preferred, and particularly, polyhexamethylene adipamide having a melting point of 215 ° C. or more ( Hereinafter, it is referred to as nylon 66 fiber, nylon 66 copolymer (nylon 66/6, nylon 66 / 6I, nylon 66/6).
10) and nylon 66 fiber blended with a polyamide polymer (nylon 6, nylon 610, etc.) are particularly preferred from the viewpoint of heat resistance.

The sulfuric acid relative viscosity ηr of the fiber mainly composed of nylon 66 is desirably 2.5 to 3.3. ηr is 2.
If it is less than 5, it is difficult to obtain high-strength fiber stably, and η
If r exceeds 3.3, the spinnability tends to be poor due to the progress of gelation accompanying the decrease in fluidity due to high viscosity.
Sulfuric acid relative viscosity ηr of the fiber mainly composed of nylon 66
Is a method of dissolving 1 g of fiber having no oil agent in 95.5% sulfuric acid (100 cc) and measuring it with an Ostwald viscometer in a thermostat at 25 ° C.

Since the base fabric for an airbag of the present invention must satisfy mechanical properties such as tensile strength and tear strength required when the airbag is operated, the single-filament fineness and the total fineness of the fibers constituting the airbag base fabric are required. , Tensile strength and weave fineness (total fineness of warp or weft (dtex) and weave density (book / 2.54c)
m) is an important requirement. The single-fiber fineness of the fibers constituting the base fabric for an airbag is not particularly limited, but is preferably 0.5 to 7 dtex, more preferably 1.1 to 3.3 dtex or less. is there. 7d
If it exceeds tex, the base fabric tends to be hard and the soft texture tends to be inferior. If it is less than 0.5 dtex, the weaving operation rate tends to decrease due to fluff during fiber production or a stop during high-density weaving.

The total fineness of the fibers refers to the total fineness per unit of the fibers in the warp direction and the weft direction used when constructing a woven fabric. One yarn may be used, or a plurality of yarns may be twisted, plyed, Although it may be in the state of a drawn yarn, the total fineness is preferably 200 dtex or less, more preferably 5 dtex or less.
0 to 200 dtex. If it is larger than 200 dtex, the compactness of the airbag is impaired, and if the total fineness is too small, there is a possibility that the pressure-resistant mechanical properties at the time of operating the airbag may not be obtained.

Further, the tensile strength of the fiber also has a great effect on the pressure-resistant mechanical characteristics during operation of the airbag. The tensile strength of the fiber is preferably 5.7 cN / dtex or more. The weave fineness (product of the total fineness (dtex) of the warp or weft and the weave density (book / 2.54 cm)) of the base fabric for an airbag is preferably 16,000 or less, more preferably 10,000 to 160.
00. If the weave fineness exceeds 16000, it will be an ultra-high-density woven fabric, and there will be many stops during weaving, making stable weaving impossible.
If the weave fineness is too small, the tensile and tear properties of the resulting base fabric will be low, and the tensile and tear strength required for an airbag may not be obtained.

As the form of the base fabric in the present invention, a woven fabric is preferable. As the woven fabric, woven fabrics such as plain weave, lattice weave, twill weave, and satin weave are used. The ratio of the number of the woven fabrics in the warp and weft directions is preferably the same for the warp and weft, but may be around several. The weaving of the woven fabric may use existing air jet weaving, water jet weaving, rapier weaving, etc., and is not particularly limited, but it is preferable to perform non-sizing air jet weaving from the simplicity of the process after weaving. .

As a method for applying the coating composition of the present invention, an existing coating device or spray device may be applied, and there is no particular limitation.

[0031]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described specifically with reference to examples. Parts represent parts by mass. The burning rate of the airbag fabric was evaluated by a method based on the FMVSS302 method (horizontal method).

Example 1 The viscosity at 25 ° C. was 500
Organopolysiloxane having a vinyl group bonded to a terminal unit of 0 centipoise with SiC, S to aliphatic multiple bond
Aqueous silicone emulsion containing a catalyst that promotes the addition of i-bonded hydrogen atoms, a silicone resin, an emulsifier, and water (“DEHENSIVE” manufactured by Asahi Kasei-Waker Corporation)
38197 VP "), 62 parts of an organopolysiloxane having at least three Si-bonded hydrogen atoms (" V20 "manufactured by Asahi Kasei-Waker Co., Ltd.), and an organosilicon compound suitable as an adhesion promoter (Asahi Kasei-Wacker Co., Ltd.) To a mixture obtained by stirring and mixing 4 parts of "HF86") and 37.5 parts of water, 0.5 part of carboxycellulose sodium salt (Wako Pure Chemical Industries, Ltd.) was added and mixed by stirring to obtain a coating composition.

[0033] The above coating composition is coated with nylon 66
The base fabric having a total fineness of 155 dtex and having a weave density (warp × weft) of 91 × 91 / 2.54 cm was coated with a knife coater so as to have an application amount of 8 g / m ² . After coating, water was removed at 130 ° C. for 2 minutes and vulcanized at 180 ° C. for 1 minute. The silicone of the obtained coated cloth was uniformly applied.

Comparative Example 1 The viscosity at 25 ° C. was 500
A silicone composition containing an organopolysiloxane having a vinyl group bonded to SiC bond at a terminal unit of 00 centipoise, a catalyst for promoting the addition of a hydrogen atom bonded to an aliphatic multiple bond to a silicon multiple bond, and a silicone resin (manufactured by Asahi Kasei-Wakker Co., Ltd. SLM45572 ") 50 parts, an organopolysiloxane having at least three Si-bonded hydrogen atoms (" Crosslinke "manufactured by Asahi Kasei-Waker Co., Ltd.)
rW ") 1.5 parts, an organosilicon compound suitable as an adhesion aid (" HF86 "manufactured by Asahi Kasei-Waker Co., Ltd.)
To 5 parts, 47 parts of toluene was added and mixed by stirring to obtain a coating composition.

Example 1 The above coating composition was prepared using a knife coater so that the coating amount was 10 g / m ^2.
The same base cloth was coated. Toluene was removed at 130 ° C. for 2 minutes and vulcanized at 180 ° C. for 1 minute. The silicone of the obtained coated cloth was uniformly applied. Comparative Example 2 The same coating composition as in Example 1 was coated with the coating composition of Comparative Example 1 using a knife coater so that the coating amount was 30 g / m ² . After coating, the toluene was removed at 130 ° C. for 2 minutes.
The mixture was vulcanized at 1 ° C for 1 minute. The silicone of the obtained coated cloth was uniformly applied.

Table 1 summarizes the evaluation results of the above Examples and Comparative Examples.

[0037]

[Table 1]

[0038]

According to the present invention, the light weight, flexibility and compactness are excellent, and the coating amount of the coating resin is 20 g / m2.
Even if it is ² or less, it is possible to provide a base fabric for an airbag that satisfies the burning rate determined by the FMVSS302.

Claims (3)

[Claims] (A) an organopolysiloxane having a vinyl group bonded to a terminal unit having a SiC bond having a viscosity at 25 ° C. of 8,000 centipoise or less, (B) an organopolysiloxane having at least three Si-bonded hydrogen atoms, An airbag coating composition comprising: (C) a catalyst for promoting the addition of a Si-bonded hydrogen atom to an aliphatic multiple bond; (D) an organosilicon compound; and (E) a silicone resin. . 2. An airbag base fabric, wherein the airbag coating composition according to claim 1 is applied to the base fabric in an amount of 20 g / m ² or less. 3. An airbag comprising the base fabric for an airbag according to claim 2.