JP4837107B2 - Airbag base fabric and airbag - Google Patents

Description

The present invention relates to an airbag base fabric that is installed to ensure the safety of an occupant in the event of an automobile collision. More specifically, the present invention is excellent in lightness, flexibility, and compactness, and the coating resin coating amount is 20 g / The present invention relates to an airbag base fabric and an airbag coating composition that satisfy the combustion rate defined by FMVSS 302 even in a small amount of m ² or less.

  Airbags are increasingly being installed as occupant protection 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 is small. Therefore, in order to make the storage volume compact, use fibers with fine fineness as the fibers used in the fabric, and change the type and amount of elastomer applied to the base fabric to maintain the airtightness of the airbag Things are being done.

For example, the fiber used for the fabric is changed from 940 dtex to a base fabric of 470 dtex. In addition, the elastomer resin to be applied and the coating amount were changed from 90 to 120 g / m ^{2 of} chloroprene to 40 to 60 g / m ^{2 of} silicone resin, and currently the silicone composition coating type of 470 dtex. A base fabric is used, and further, a non-coated type having a slight air permeability is used from the viewpoint of improvement in compactness and economy of coating processing cost.

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 airbag base fabric and to soften the texture. There is a desire to reduce the amount of coating for weight reduction.
However, if the application amount of the silicone composition is decreased, the burning rate increases, and there is a problem that the burning rate determined by FMVSS 302 is not satisfied.

Examples of conventional representative techniques that attempt to solve this problem include JP-A-7-195990 and JP-A-7-300774.
In these techniques, the viscosity of the organopolysiloxane having a vinyl group bonded to SiC in the terminal unit contained in the coating composition is large and the number of terminal double bonds is small, so that the crosslinking density is low. Therefore, by adding fine powder silica as a film filler and silicone resin as a film enhancer to the coating composition, the coating resin film is prevented from being broken during the FMVSS302 combustion test. However, in order to pass the FMVSS 302 combustion test with a small amount of application such as 20 g / m ² or less, it is necessary to contain a large amount of fine powder silica as a film filler. There is a real situation.

JP-A-7-195990 JP-A-7-300774

The present invention is excellent in light weight, flexibility and compactness, and even if the coating amount of the coating resin is a small amount such as 20 g / m ² or less, an air bag base fabric that satisfies the burning rate defined by FMVSS 302, and an air bag It aims at providing the coating composition for bags.

As a result of intensive studies to solve the above problems, the present inventors have increased the number of terminal vinyl groups by reducing the viscosity of organopolysiloxane having a vinyl group with SiC bonding to the terminal unit to 10,000 centipoise or less. The crosslinking density after vulcanization is increased, the silicone resin film is prevented from being broken in the FMVSS302 combustion test, and the diffusion of the combustion gas is suppressed. Even if the coating resin is applied in an amount as small as 20 g / m ² or less, the FMVSS302 The present inventors have found a base fabric for an air bag satisfying the burning rate determined by the above and have completed the present invention.

That is, the present invention is as follows.
(1) (A) an organopolysiloxane having a vinyl group bonded with SiC at the terminal unit and having a viscosity at 25 ° C. of 8000 centipoise or less, (B) an organopolysiloxane having at least three Si-bonded hydrogen atoms, (C) A coating composition comprising a catalyst that promotes the addition of Si-bonded hydrogen atoms to an aliphatic multiple bond, (D) an organosilicon compound, (E) a silicone resin, and (F) carboxycellulose sodium salt is a knife coater airbag fabric, characterized in that it is 5 to 15 g / m ² applied to a fabric by.
(2) The airbag fabric according to Item 1, wherein the total fineness of the fibers constituting the fabric is 200 dtex or less.
(3) The airbag fabric according to 1 or 2 above, wherein the woven fineness of the fibers constituting the fabric is 16000 or less.
(4) The airbag fabric according to any one of the above items 1 to 3, which satisfies a combustion rate defined by FMVSS 302.
(5) The airbag which consists of the base fabric for airbags as described in any one of said 1-4.

According to the present invention, it is possible to provide an airbag base fabric that is excellent in lightness, flexibility, and compactness and that satisfies the burning rate defined by FMVSS 302 even when the coating resin coating amount is 20 g / m ² or less.

Hereinafter, the present invention will be described in detail.
In the present invention, the organopolysiloxane (A) having a vinyl group having a SiC bond to the terminal unit is a diorganopolysiloxane represented by the following general formula.
_{(CH 2 = CH) X SiR} 3-X -O (SiR 2 O) n SiR 3-X (CH = CH 2) X
[Wherein R are the same or different hydrocarbon groups, which may be substituted, advantageously represent a hydrocarbon group having from 1 to 18 carbon atoms. X is 1, 2 or 3, preferably 1. n represents the number of (SiR ₂ O) when the degree of polymerization is such that the diorganopolysiloxane has an average viscosity of 10,000 centipoise or less at 25 ° C.]

The viscosity of (A) at 25 ° C. is preferably 8000 centipoise or less, and more preferably 50 to 5000 centipoise. If it exceeds 8000 centipoise, since the terminal vinyl group is small and the crosslinking density after vulcanization is small, the resin film formed by coating becomes weak, and at a coating amount of 20 g / m ² or less, the film is torn during the combustion test. The combustion speed determined by FMVSS 302 cannot be satisfied. On the other hand, if the viscosity is too low, the coating composition penetrates into the woven fabric, which tends to make film formation difficult.

  Examples of hydrocarbon groups as R are preferably alkyl groups such as methyl, ethyl, n-propyl, isopropyl, butyl, octyl, tetradecyl or octadecyl; alicyclic hydrocarbons A group such as 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 substituted hydrocarbon groups as R may advantageously be halogenated groups such as 3,3,3-trifluoropropyl groups, 3-chloropropyl groups or chlorophenyl groups. A cyanoalkyl group, such as a cyanoethyl group, may be included. A group having an unsaturated aliphatic group, for example, a vinyl group, an allyl group, a hexenyl group or a cyclohexenyl group may also be contained.

R is preferably a hydrocarbon group having 1 to 10 carbon atoms, more preferably at least 80% of the organic group represented by R is a methyl group.
The organopolysiloxane may be the same copolymer, or may be 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.

In the coating composition of the present invention, the organopolysiloxane (A) is preferably contained in an amount of 10 to 80 wt%, more preferably 20 to 50 wt%.
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 3) 3 SiO- (SiHRO} ) O - (SiR 2 O) P -Si (CH 3) 3
[Wherein R is as defined above, and o and p are present in a ratio of 1: 0 to 1:20, preferably 1: 0 to 1: 7]
The sum of o and p can range from 10 to 1000, with a preferred total being 20 to 200, and a more preferred total being 30 to 100. In the case of organopolysiloxanes having at least 3 Si-bonded hydrogen atoms per molecule, organopolysiloxanes having no silicon valence saturated with hydrogen atoms and siloxane oxygen atoms are preferably methyl groups, ethyl Or saturated with a phenyl group. However, it may contain all of the groups described above as R.

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

  Compounds or complexes of these metals, such as platinum-olefin complexes, platinum-alcohol complexes, such as Speyers Catalyst, platinum-alcolate complexes, platinum-ether complexes, platinum-aldehyde complexes, platinum Ketone complexes, such as reaction products from cyclohexane and hexachloroplatinic acid, platinum-vinylsiloxane complexes, in particular platinum-divinyltetramethyldisiloxanes containing or not containing organically bonded halogen atoms Complexes, bis- (γ-picoline) -platinum dichloride, trimethylenepyridine platinum dichloride, dicyclopentadiene platinum dichloride, dimethylsulfoxydiethylene platinum (2) dichloride, and platinum tetrachloride and second dissolved in 1-octene Reaction from butylamine Objects are also examples 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.

で示されるシランからの反応生成物が使用される。（Ｄ）としては、１種類を使用することもできるし、しかしまた、２種類もしくはそれ以上のシランの混合物又はこれらの反応生成物、ないしは部分加水分解物もしくは加水分解物混合物を使用することもできる。これら付着助剤としての（Ｄ）は、シリコーン組成物中に１〜２０ｗｔ％の量で含有するのが好ましく、更に好ましくは２〜８ｗｔ％含有する。 In the present invention, in the silicone composition, in the case of a platinum catalyst, the catalyst can be used in an amount in which the platinum content in the composition according to the present invention is in the range of 3 to 500 ppm relative to the polysiloxane content, Preferably, the platinum content relative to the polysiloxane used is 10 to 200 ppm.
In the present invention, the organosilicon compound (D) may be any suitable as a deposition aid. By way of example, it is possible to use silanes having hydrolyzable groups and vinyl-, acryloxy-, methacryloxy-, epoxy- or acid anhydride groups bonded to the silicon atom via carbon atoms. Such a partial hydrolyzate and / or hydrolyzate mixture of silane can also be used. Preferably vinyltriacetoxysilane and the following formula

The reaction product from silane is used. As (D), one kind can be used, but it is also possible to use a mixture of two or more silanes or a reaction product thereof, or a partial hydrolyzate or a hydrolyzate mixture. it can. These adhesion assistants (D) are 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 comprises a silicone resin (E) represented by the general formula: (R ₃ SiO _1/2 ) _a (R ₃ SiO _3/2 ) _b , that is, the general formula: (R ₃ SiO _1/2 ) _a (R ₃ SiO _3/2 ) _b may contain an aqueous emulsion of the so-called MT resin and / or MQ resin, in which case R is as defined above and is preferably methyl A group, a phenyl group, a vinyl group or a hydrogen atom. The ratio of a and b is selected such that the silicone resin is within the viscosity range of 30 to 300000 centipoise, preferably within the viscosity range of 50 to 30000 centipoise, more preferably within the viscosity range of 50 to 10000 centipoise. The silicone resin is selected.

The coating composition of the present invention only needs to contain the components (A), (B), (C), (D), and (E), and is a solvent-free system, an aqueous emulsion system, or Although it can be used in a system diluted with a toluene-based organic solvent, a solvent-free system or a system based on an aqueous emulsion is preferable from the viewpoint of work safety and environmental pollution.
When used as an aqueous emulsion, it is usually possible to use any emulsifier that is used in the preparation of organopolysiloxane emulsions. Examples of this emulsifier include sulfonic acids and salts thereof that can act as emulsifiers and alkyl sulfonates such as sodium lauryl sulfonate, benzene sulfonates substituted with aliphatic hydrocarbon groups such as sodium dodecyl benzene sulfonate, aliphatic Naphthalene sulfonates substituted with hydrocarbon groups, polyethylene glycol sulfonates and lauryl phosphates, polyethylene oxide, polypropylene oxide, copolymers of ethylene oxide and propylene oxide, stearates and phosphates.

In addition, the coating composition of the present invention may contain known thickeners, flame retardants, fillers, pigments and stabilizers in amounts that do not impair the effects of the present invention. Examples of the thickener include carboxycellulose sodium salt (component (F)).
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 airbag fabric and the softening of the texture become insufficient, and the coating cost increases. Moreover, if there is too little application quantity, a flame retardance will become inadequate.

  The fiber constituting the airbag fabric of the present invention is not particularly limited, but a fiber mainly composed of polyhexamethylene adipamide is preferable, and in particular, polyhexamethylene adipamide having a melting point of 215 ° C. or higher (hereinafter simply referred to as “polyhexamethylene adipamide”). Nylon 66 fiber), nylon 66 fiber blended with nylon 66 copolymer (nylon 66/6, nylon 66 / 6I, nylon 66/610, etc.), and nylon 66 blended with polyamide polymer (nylon 6, nylon 610 etc.) A fiber is particularly preferable in terms of heat resistance.

  The sulfuric acid relative viscosity ηr of the fiber mainly composed of nylon 66 is preferably 2.5 to 3.3. If ηr is less than 2.5, it is difficult to stably obtain high-strength fibers, and if ηr exceeds 3.3, the spinnability tends to be poor due to the progress of gelation due to the decrease in fluidity due to high viscosity. is there. The method for measuring the relative sulfuric acid viscosity ηr of the fiber mainly composed of nylon 66 was obtained by dissolving 1 g of a fiber having no oil agent in 100 cc of 95.5% sulfuric acid and measuring it with an Ostwald viscometer in a thermostatic chamber at 25 ° C. Is.

The airbag fabric of the present invention must satisfy mechanical properties such as tensile strength and tear strength required when the airbag is operated. Therefore, the single yarn fineness, total fineness, and tensile strength of the fibers constituting the airbag fabric The weaving fineness (the product of the total fineness (dtex) of warp or weft and the weave density (main / 2.54 cm)) is an important requirement.
The single yarn fineness of the fibers constituting the airbag fabric is not particularly limited, but preferably the single yarn fineness is 0.5 to 7 dtex, and more preferably 1.1 to 3.3 dtex or less. is there. If it exceeds 7 dtex, 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 is likely to decrease due to fluff during fiber production or due to stopping during high density weaving.

  The total fineness of fibers refers to the total fineness per unit of warp and weft fibers used when composing a woven fabric. One yarn may be used, or a plurality of yarns may be twisted, combined, or aligned. However, the total fineness is preferably 200 dtex or less, and more preferably 50 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 characteristics during operation of the airbag cannot be obtained.

In addition, the tensile strength of the fiber greatly affects the pressure resistance mechanical characteristics when the airbag is activated. The tensile strength of the fiber is preferably 5.7 cN / dtex or more.
The woven fineness of the airbag fabric (the product of the total fineness (dtex) of warp or weft) and the woven density (lines / 2.54 cm) is preferably 16000 or less, more preferably 10000 to 16000. If the weaving fineness exceeds 16000, it becomes an ultra-high-density woven fabric, there are many stops during weaving, and stable weaving cannot be performed. If the weaving fineness is too small, the tensile and tearing properties of the resulting base fabric will be lowered, and the airbag As a result, the necessary tensile and tear strength may not be obtained.

  The base fabric in the present invention is preferably a woven fabric. As the woven fabric, a plain woven fabric, a lattice woven fabric, a twill woven fabric, a satin woven fabric or the like is used. Although the same number of warps and wefts is desirable for the ratio of the number of warp and wefts in the weft direction, it may be about 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 air jet weaving without sizing from the simplicity of the process after weaving. .

  As a method for applying the coating composition of the present invention, an existing coating apparatus or spray apparatus may be applied and is not particularly limited.

Hereinafter, the present invention will be described specifically by way of examples.
In addition, a part represents a mass part.
The burning rate of the airbag fabric was evaluated by a method according to the FMVSS 302 method (horizontal method).

[Example 1]
Silicone containing organopolysiloxane having a vinyl group bonded with SiC at a terminal unit having a viscosity of 5000 centipoise at 25 ° C., a catalyst for promoting the addition of Si-bonded hydrogen atom to an aliphatic multiple bond, a silicone resin, an emulsifier, and water 52 parts of an aqueous emulsion (“DEHENSIVE 38197 VP” manufactured by Asahi Kasei-Wacker Co., Ltd.), 6 parts of organopolysiloxane (“V20” manufactured by Asahi Kasei-Wacker Co., Ltd.) having at least three Si-bonded hydrogen atoms, suitable as an adhesion aid 0.5 parts of carboxycellulose sodium salt (Wako Pure Chemical Industries, Ltd.) was added to a mixed liquid obtained by stirring and mixing 4 parts of an organic silicon compound ("HF86" manufactured by Asahi Kasei-Wacker Co., Ltd.) and 37.5 parts of water, followed by stirring and mixing. Thus, a coating composition was obtained.

  Using a knife coater, the coating composition was applied to a base fabric having a weave density (warp × weft) of 91 × 91 pieces / 2.54 cm using fibers of nylon 66 having a total fineness of 155 dtex, and a coating amount of 8 g / m 2 Coated so that After coating, moisture was removed at 130 ° C. for 2 minutes, and further vulcanized at 180 ° C. for 1 minute. The silicone of the resulting coated fabric was uniformly applied.

[Comparative Example 1]
An organopolysiloxane having a vinyl group bonded with SiC to a terminal unit having a viscosity of 50,000 centipoise at 25 ° C., a catalyst for promoting the addition of a Si-bonded hydrogen atom to an aliphatic multiple bond, a silicone composition containing a silicone resin (Asahi Kasei) "SLM45572" manufactured by Wacker Co., Ltd.), 50 parts of organopolysiloxane having at least 3 Si-bonded hydrogen atoms ("Crosslinker W" manufactured by Asahi Kasei-Wacker Co., Ltd.), an organosilicon compound suitable as an adhesion aid ( Asahi Kasei-Wacker Co., Ltd. “HF86”) (1.5 parts) was added 47 parts of toluene and mixed by stirring to obtain a coating composition.

Using the knife coater, the above coating composition was coated on the same base fabric as in Example 1 so that the coating amount was 10 g / m ² . Toluene was removed at 130 ° C. for 2 minutes and further vulcanized at 180 ° C. for 1 minute. The silicone of the resulting coated fabric was uniformly applied.

[Comparative Example 2]
The coating composition of Comparative Example 1 was coated on the same base fabric as in Example 1 using a knife coater so that the coating amount was 30 g / m ² . After coating, toluene was removed at 130 ° C. for 2 minutes, and further vulcanized at 180 ° C. for 1 minute. The silicone of the resulting coated fabric was uniformly applied.
The evaluation results for the above examples and comparative examples are summarized in Table 1.

According to the present invention, it is possible to provide an airbag base fabric that is excellent in lightness, flexibility, and compactness and that satisfies the burning rate defined by FMVSS 302 even when the coating resin coating amount is 20 g / m ² or less.

Claims (5)

(A) An organopolysiloxane having a vinyl group bonded with SiC at the terminal unit and having a viscosity at 25 ° C. of 8000 centipoise or less, (B) an organopolysiloxane having at least three Si-bonded hydrogen atoms, (C) an aliphatic multiple A coating composition comprising a catalyst that promotes the addition of Si-bonded hydrogen atoms to the bond, (D) an organosilicon compound, (E) a silicone resin, and (F) carboxycellulose sodium salt is provided by a knife coater. 5 to 15 g / m ^{2 is} applied to the air bag base fabric.   The base fabric for an air bag according to claim 1, wherein the total fineness of the fibers constituting the base fabric is 200 dtex or less.   The base fabric for an air bag according to claim 1 or 2, wherein the woven fineness of the fibers constituting the base fabric is 16000 or less.   The base fabric for airbags as described in any one of Claims 1-3 which satisfies the combustion rate which FMVSS302 determines.   The airbag which consists of the base fabric for airbags as described in any one of Claims 1-4.