JP2020032740A - Manufacturing method of silicone coating fabric base for airbag - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a simple method for manufacturing a silicone-coated base fabric for an air bag, which has excellent blocking resistance and excellent internal pressure retention when manufacturing an air bag such as a curtain air bag. A method for manufacturing a silicone-coated base cloth for an air bag having a silicone rubber layer on at least one surface of the base cloth for an air bag, wherein the base cloth for an air bag has a viscosity of 25 ° C. The first step of coating a liquid silicone rubber composition having a coating amount of 5,000 to 300,000 mPa · s so that the coating amount is 80 to 300 g / m2, the coating amount of the coated liquid silicone rubber composition. A method for producing a silicone-coated base cloth for an air bag, comprising a second step of reducing the weight to 10 to 60 g / m2 and a third step of curing the liquid silicone rubber composition after the weight reduction. [Selection diagram] None

Description

  The present invention relates to a method for producing a silicone-coated base fabric for an airbag having excellent internal pressure retention and blocking resistance.

  BACKGROUND ART Conventionally, there has been proposed an airbag base fabric in which a surface of a base fabric made of fibers is coated with a silicone rubber composition and cured to form a rubber coating. The base fabric coated with silicone is excellent in low burning rate. Further, curtain airbags manufactured from a silicone-coated base fabric are suitable for use as airbags for automobiles and the like because they can suppress leakage of inflator gas when the airbag is inflated and have excellent internal pressure retention. .

  As a method for producing such a silicone-coated base fabric for an air bag, an addition-curable liquid silicone rubber composition comprising a combination of a cross-linking material having a hydrosilyl group at both ends of a molecular chain and a cross-linking material having a hydrosilyl group at a side chain is known. To produce a silicone-coated airbag having excellent internal pressure retention by coating on a base cloth and curing by heating (Patent Document 1: JP-T-2013-531695), or an organohydro having a hydrosilyl group having a specific structure. Addition curing containing genpolysiloxane as a cross-linking agent, and as an adhesion-imparting component, an organosilicon compound having an epoxy group and a silicon-bonded alkoxy group in one molecule and one or both of a titanium compound and a zirconium compound. Mold liquid silicone rubber composition Ngushi, a method of producing a silicone coating air bag excellent in internal pressure retention by cured by heating (Patent Document 2: JP 2011-080037 publication) or the like is disclosed.

  However, the airbags manufactured by these methods have a sticky feeling peculiar to silicone rubber, and thus have extremely poor blocking resistance. As a remedy, a powder of talc or the like, which is rich in adhesiveness and slipperiness, is ground on the rubber surface. However, this method is expensive and has a risk of harming the human body due to dust. In addition, since the powder is merely attached to the surface of the rubber-coated cloth, the powder is easily removed and the effect cannot be stably exhibited.

  As a method for solving these problems, a silicone coating base cloth having excellent blocking resistance and internal pressure holding properties is obtained by coating a base cloth for an air bag with silicone containing an adhesive and curing the silicone by irradiating an electron beam. (Patent Document 3: JP-A-2015-085271) or by coating a liquid silicone rubber composition on a base fabric for an air bag, heating and curing, and then irradiating the silicone coating with vacuum ultraviolet rays. A method for producing a silicone-coated base fabric having excellent low friction properties (Patent Document 4: JP-T-2018-511687) and the like are disclosed.

  However, these manufacturing methods require the use of an electron beam or ultraviolet light, which may affect the health of workers. On the other hand, if the coating amount of the silicone is small, the filaments are exposed on the surface layer rather than the silicone rubber layer, so that the base cloth is deteriorated by electron beams or ultraviolet rays, and the strength of the silicone coating base cloth is deteriorated.

JP-T-2013-531695 JP 2011-080037 A JP-A-2005-085271 JP-T-2018-511687

  The present invention has been made in view of the above circumstances, and is excellent in blocking resistance, excellent in internal pressure retention when manufacturing an air bag such as a curtain air bag, and a simple silicone coated base fabric for an air bag. It is intended to provide a manufacturing method.

  The present inventors have conducted intensive studies to achieve the above object, and as a result, by forming a silicone rubber layer on an airbag base fabric through first to third steps described later, the blocking resistance was improved. The present inventors have found that it is possible to obtain a silicone-coated base fabric capable of producing an airbag which is excellent and has an excellent internal pressure retention property for suppressing leakage of inflator gas when the airbag is inflated, and has accomplished the present invention.

Accordingly, the present invention provides the following inventions.
1. A method for producing a silicone-coated base fabric for an airbag, having a silicone rubber layer on at least one surface of the base fabric for an airbag,
At least one surface of a base fabric for an air bag is coated with a liquid silicone rubber composition having a viscosity of 5,000 to 300,000 mPa · s at 25 ° C. so that a coating amount is 80 to 300 g / m ^2. The first step to do
A second step of reducing the coating amount of the coated liquid silicone rubber composition to 10 to 60 g / m ² , and a third step of curing the reduced liquid silicone rubber composition,
A method for producing a silicone-coated base fabric for an airbag, comprising:
2. 2. The method for producing a silicone-coated base fabric for an airbag according to 1, wherein the coating method of the liquid silicone rubber composition in the first step is knife coating, gravure coating, roll coating, bar coating, die coating or dipping.

  According to the present invention, it is possible to obtain a silicone-coated base fabric for an airbag, which is capable of producing an airbag excellent in blocking resistance and excellent in internal pressure retention that suppresses leakage of inflator gas when the airbag is inflated. .

  Hereinafter, the present invention will be described in more detail. In this specification, the viscosity is a value measured at 25 ° C. by a rotational viscometer according to a method described in JIS K 7117-1: 1999. The degree of polymerization is a value determined as a polystyrene-equivalent weight average polymerization degree (weight average molecular weight) in GPC (gel permeation chromatography) analysis using toluene as a developing solvent.

<Base fabric for airbag>
In the present invention, known fabrics are used as the base fabric for airbags (substrate made of fiber fabric or the like), and specific examples thereof include various polyamide fibers such as nylon 66, nylon 6, and aramid fibers, and polyethylene terephthalate. Woven fabrics of various synthetic fibers such as various polyester fibers such as (PET) and polybutylene terephthalate (PBT).

  When producing the airbag base fabric, a yarn having an arbitrary linear density can be used, but is preferably 10 to 3,000 denier, more preferably 50 to 1,000 denier. If the linear density is less than 10 denier, the cost of yarn production increases and it is uneconomical. If the linear density exceeds 3,000 denier, the base fabric for the airbag becomes thick, and when the airbag is folded and stored, The volume may increase.

<Liquid silicone rubber composition>
The liquid silicone rubber composition of the present invention has a viscosity of 5,000 to 300,000 mPa · s, preferably 10,000 to 250,000 mPa · s, and more preferably 20,000 to 200,000 mPa · s. More preferred. If the viscosity of the liquid silicone rubber composition is less than 5,000 mPa · s, it may be difficult to obtain an appropriate coating amount in the first step, and if the viscosity exceeds 300,000 mPa · s, And the workability in the second step may be deteriorated.

When the liquid silicone rubber composition is an addition-curable liquid silicone rubber composition, a composition containing the following components is preferred.
(A) an organopolysiloxane having an alkenyl group bonded to two or more silicon atoms in one molecule and having a degree of polymerization of 100 to 2,000: 100 parts by mass;
(B) An organohydrogenpolysiloxane containing a hydrogen atom (SiH group) bonded to two or more silicon atoms in one molecule: the SiH group in the component (B) is bonded to the silicon atom in the component (A). An amount of 1 to 10 mol per 1 mol of the total of the alkenyl groups,
(C) a silica powder having a BET specific surface area of 50 m ² / g or more: 1 to 50 parts by mass;
(D) hydrosilylation reaction catalyst: 1 to 500 ppm in terms of mass of catalytic metal element, based on the total mass of (A) to (C)
(E) an organosilicon compound having an adhesiveness-imparting functional group: 0.1 to 10 parts by mass

[(A) component]
The organopolysiloxane of the component (A) is an organopolysiloxane containing two or more alkenyl groups bonded to silicon atoms in one molecule and having a degree of polymerization of 100 to 2,000. This is an organopolysiloxane that is liquid at 25 ° C. and is the base polymer (base) of the liquid silicone rubber composition. As the component (A), one type may be used alone, or two or more types may be used in combination.

  The molecular structure of the component (A) may be, for example, linear, cyclic, branched, or the like. The main chain is basically composed of repeating diorganosiloxane units, and both ends of the molecular chain are triorganosiloxy. Linear diorganopolysiloxanes blocked with groups are preferred. When the molecular structure of the organopolysiloxane of the component (A) is linear or branched, the position of the silicon atom to which the alkenyl group is bonded in the molecule of the organopolysiloxane is determined at the end of the molecular chain (ie, Either the triorganosiloxy group) or the middle of the molecular chain (that is, a difunctional diorganosiloxane unit or a trifunctional monoorganosilsesquioxane unit located at the non-terminal of the molecular chain) may be both. As the component (A), a linear diorganopolysiloxane containing at least an alkenyl group bonded to silicon atoms at both ends of a molecular chain is preferable.

  The alkenyl group bonded to the silicon atom in the component (A) includes, for example, those having usually 2 to 8 carbon atoms, preferably 2 to 4 carbon atoms. Specific examples thereof include a vinyl group, an allyl group, a propenyl group, a butenyl group, a pentenyl group, a hexenyl group, a cyclohexenyl group, and a heptenyl group, and a vinyl group is preferable.

  The content of the alkenyl group bonded to the silicon atom in the component (A) is 0.001 relative to the total amount of the monovalent organic group bonded to the silicon atom (that is, the unsubstituted or substituted monovalent hydrocarbon group). Preferably, it is about 10 to 10 mol%, and particularly preferably about 0.01 to 5 mol%.

  Examples of the monovalent organic group bonded to a silicon atom other than the alkenyl group of the component (A) include, for example, the same or different unsubstituted or substituted, usually 1 to 12 carbon atoms, preferably 1 to 10 carbon atoms. A monovalent hydrocarbon group. Specific examples of the monovalent organic group include an alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a cyclohexyl group, and a heptyl group; a phenyl group, a tolyl group, a xylyl group, and a naphthyl group. Aryl groups such as benzyl group and phenethyl group; halogen-substituted alkyl groups such as chloromethyl group, 3-chloropropyl group, and 3,3,3-trifluoropropyl group; Is preferred.

  The polymerization degree of the component (A) is from 100 to 2,000, preferably from 150 to 1,500. If the degree of polymerization is less than 100, the mechanical properties of the obtained silicone rubber may be deteriorated. On the other hand, if the degree of polymerization exceeds 2,000, the viscosity of the obtained silicone rubber composition increases and the coating workability increases. May worsen.

  Specific examples of the organopolysiloxane of the component (A) include a dimethylsiloxane / methylvinylsiloxane copolymer having trimethylsiloxy groups at both ends of molecular chains, methylvinylpolysiloxane having trimethylsiloxy groups at both ends of molecular chains, and trimethyl at both ends of molecular chains. Siloxy group-blocked dimethylsiloxane / methylvinylsiloxane / methylphenylsiloxane copolymer, molecular chain terminal dimethylvinylsiloxy group-blocked dimethylpolysiloxane, molecular chain terminal dimethylvinylsiloxy group-blocked methylvinylpolysiloxane, molecular chain terminal dimethylvinyl Siloxy group-blocked dimethylsiloxane / methylvinylsiloxane copolymer, molecular chain at both ends dimethylvinylsiloxy group-blocked dimethylsiloxane / methylvinylsiloxane / methylphenylsiloxane copolymer, molecular chain Divinylmethylsiloxy terminal-blocked dimethylpolysiloxane, molecular chain divinylmethylsiloxy group-blocked dimethylsiloxane / methylvinylsiloxane copolymer, molecular chain terminal trivinylsiloxy group-blocked dimethylpolysiloxane, molecular chain terminal trivinylsiloxy group Examples include a blocked dimethylsiloxane / methylvinylsiloxane copolymer and a mixture of two or more of these organopolysiloxanes.

[Component (B)]
The organohydrogenpolysiloxane of the component (B) mainly undergoes a hydrosilylation addition reaction with the alkenyl group in the component (A) to act as a crosslinking agent (curing agent). As the component (B), one type may be used alone, or two or more types may be used in combination.
Examples of the molecular structure of the component (B) include various structures such as a linear, cyclic, branched, and three-dimensional network (resin-like) structure. It is necessary to have a hydrogen atom (SiH group) bonded to at least two silicon atoms, and it is preferable to have usually 2 to 300, preferably 3 to 200, more preferably 4 to 100 SiH groups, Those which are liquid at ° C are preferably used. Such a SiH group may be located either at the terminal of the molecular chain or in the middle of the molecular chain, or may be located at both of them.

As the organohydrogenpolysiloxane, those represented by the following average composition formula (1) can be used.

In the formula (1), R ¹ is the same or different from each other, excluding an aliphatic unsaturated bond such as an alkenyl group, and preferably has 1 to 10 carbon atoms and is an unsubstituted or substituted monovalent hydrocarbon bonded to a silicon atom. Group, for example, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, neopentyl, hexyl, cyclohexyl, octyl, nonyl, decyl, etc. Alkyl group, phenyl group, tolyl group, xylyl group, aryl group such as naphthyl group, benzyl group, phenylethyl group, aralkyl group such as phenylpropyl group, and part or all of hydrogen atoms of these groups are fluorine, Those substituted with a halogen atom such as bromine or chlorine, such as chloromethyl, chloropropyl, bromoethyl, and trifluoropropyl And the like. A is 0.7 to 2.1, b is 0.001 to 1.0, and a + b is a positive number satisfying 0.8 to 3.0, preferably a is 1.0 to 2 0.0 and b are 0.01 to 1.0, and a + b is a positive number satisfying 1.5 to 2.5.

Examples of the organohydrogenpolysiloxane of the component (B) include 1,1,3,3-tetramethyldisiloxane, 1,3,5,7-tetramethylcyclotetrasiloxane, and tris (hydrogendimethylsiloxy). Methylsilane, tris (hydrogendimethylsiloxy) phenylsilane, methylhydrogencyclopolysiloxane, cyclic copolymer of methylhydrogensiloxane and dimethylsiloxane, trimethylsiloxy group-blocked methylhydrogenpolysiloxane at both ends of molecular chain, trimethyl at both ends of molecular chain Siloxy group-blocked dimethylsiloxane / methylhydrogensiloxane copolymer, molecular chain at both ends trimethylsiloxy group-blocked dimethylsiloxane / methylhydrogensiloxane / methylphenylsiloxane copolymer Trimethylsiloxy group-blocked dimethylsiloxane / methylhydrogensiloxane / diphenylsiloxane copolymer at both ends of molecular chain, methylhydrogenpolysiloxane blocked at both ends of molecular chain, dimethylpolysiloxane at both ends of molecular chain Siloxane, dimethylhydrogensiloxy group-blocked dimethylsiloxane / methylhydrogensiloxane copolymer, molecular chain dimethylhydrogensiloxy group-blocked dimethylsiloxane / methylphenylsiloxane copolymer, molecular chain dimethylhydrogen Siloxy group-blocked dimethylsiloxane / diphenylsiloxane copolymer, dimethylhydrogen siloxy group-blocked methylphenylpolysiloxane at both molecular chain terminals, molecule And both ends endcapped with dimethyl hydrogen siloxy group diphenyl polysiloxane, in each of these exemplified compounds, those in which a part of the methyl group or entirely substituted with an ethyl group, other alkyl groups such as propyl group, the formula: R ² ₃ siloxane units of the formula SiO _0.5: siloxane units represented by the formula R ² ₂ HSiO _0.5: organosiloxane copolymers composed of siloxane units represented by SiO _2, wherein: the siloxane units represented by R ² ₂ HSiO _0.5 And an organosiloxane copolymer comprising a siloxane unit represented by the formula: SiO ₂ , a siloxane unit represented by the formula: R ² HSiO and a siloxane unit represented by the formula: R ² SiO _1.5 or a siloxane unit represented by the formula: HSiO _1.5 And organopolysiloxanes comprising at least two of these organopolysiloxanes And mixtures of the above. R ² in the above formula is a monovalent hydrocarbon group other than an alkenyl group, and the same groups as those of R ¹ are exemplified.

  The amount of the component (B) is such that the amount of the SiH group in the component (B) is 1 to 10 moles per 1 mole (or the same, hereinafter) of the silicon-bonded alkenyl groups in the component (A). The amount is preferably 1.2 to 9 moles (or pieces), more preferably 1.5 to 8 moles (or pieces). When the amount of the SiH group contained in the component (B) is less than 1 mol with respect to the total of 1 mol of the silicon-bonded alkenyl group contained in the component (A), the silicone rubber composition may not be sufficiently cured. On the other hand, if it exceeds 10 mol, the heat resistance of the obtained cured silicone rubber may be extremely deteriorated.

[(C) component]
The silica powder of the component (C) is a fine powder that acts as a reinforcing filler. That is, it imparts strength to the cured silicone rubber obtained from the liquid silicone rubber composition, and forms a coating film that satisfies the strength required for the present invention by using silica fine powder as a reinforcing filler. It becomes possible. As the component (C), one type may be used alone, or two or more types may be used in combination. The silica powder of the present invention needs to have a specific surface area (BET method) of 50 m ² / g or more, preferably 50 to 400 m ² / g, more preferably 100 to 300 m ² / g. If less than 50 m ² / g, satisfactory strength properties cannot be imparted.

  Such silica powder may be a known silica powder conventionally used as a reinforcing filler for silicone rubber, provided that the specific surface area is within the above range, and examples thereof include fumed silica (fumed silica). ), Precipitated silica (wet silica) and the like.

  As the silica powder, for example, a silica fine powder whose surface has been hydrophobized with a surface treatment agent such as a (usually hydrolyzable) organosilicon compound such as chlorosilane, alkoxysilane, or organosilazane can be used. In this case, these silica fine powders may be used in the form of powders which have been directly surface-hydrophobized with a surface treating agent in advance, or may be used in the form of silicone oil (for example, the alkenyl group of the component (A)). A surface-hydrophobizing agent may be used by adding a surface treating agent at the time of kneading with an organopolysiloxane (containing organopolysiloxane).

  As a usual treatment method of the component (C), surface treatment can be performed by a known technique. For example, the untreated silica fine powder and the surface treatment agent are added to a mechanical kneading device or a fluidized bed sealed at normal pressure. And, if necessary, can be mixed at room temperature (25 ° C.) or under heat treatment (heating) in the presence of an inert gas. In some cases, the surface treatment may be promoted using water or a catalyst (such as a hydrolysis promoter). After kneading, by drying, a fine powder of surface-treated silica can be produced. The compounding amount of the surface treatment agent may be at least the amount calculated from the coating area of the surface treatment agent, and is usually 1 to 50 parts by mass, preferably 5 to 40 parts by mass, per 100 parts by mass of untreated silica powder. It can be set to 10 parts by mass, more preferably 10 to 30 parts by mass.

  Specific examples of the surface treating agent include silazanes such as hexamethyldisilazane, 1,1,3,3,5,5-hexamethylcyclotrisilazane, methyltrimethoxysilane, ethyltrimethoxysilane, and propyltrisilazane. Silane coupling of methoxysilane, butyltrimethoxysilane, dimethyldimethoxysilane, diethyldimethoxysilane, trimethylmethoxysilane, triethylmethoxysilane, trimethylchlorosilane, dimethyldichlorosilane, chloropropyltrimethoxysilane, trimethylsilanol, hydroxypentamethyldisiloxane, etc. And organosilicon compounds such as polymethylsiloxane and organohydrogenpolysiloxane. Hydrophobic silica powder surface-treated with these can be used. As the surface treatment agent, silazanes or chlorosilanes are preferable.

  The compounding amount of the component (C) is 1 to 50 parts by mass, preferably 10 to 30 parts by mass, based on 100 parts by mass of the organopolysiloxane of the component (A). If the amount is too small, the strength required for the present invention may not be obtained.If the amount is too large, the viscosity of the composition may be increased, the fluidity may be reduced, and the coating operation may be deteriorated. .

[(D) component]
The hydrosilylation reaction catalyst of the component (D) mainly promotes the addition reaction between the alkenyl group bonded to the silicon atom in the component (A) and the SiH group in the component (B). As the component (D), one type can be used alone, or two or more types can be used in appropriate combination. The hydrosilylation reaction catalyst is not particularly limited. For example, platinum group metals such as platinum, palladium and rhodium; chloroplatinic acid; alcohol-modified chloroplatinic acid; chloroplatinic acid and olefins, vinylsiloxane or acetylene compound Coordination compounds; platinum group metal compounds such as tetrakis (triphenylphosphine) palladium and chlorotris (triphenylphosphine) rhodium. Among them, a platinum group metal-based curing catalyst is preferable.

  The compounding amount of the component (D) may be any effective amount as a catalyst. Preferably it is 10-100 ppm. If the amount is less than 1 ppm, the addition reaction may be extremely slow or the composition may not be cured, and if it exceeds 500 ppm, the heat resistance of the cured product may be extremely reduced.

[(E) component]
The component (E) is an organosilicon compound having an adhesiveness-imparting functional group, and can be used alone or in combination of two or more. Examples of the adhesion-imparting functional group include an epoxy group, a silicon-bonded alkoxy group (alkoxysilyl group), a hydrosilyl group, an isocyanate group, an acryl group, and a methacryl group. The adhesion of the silicone rubber composition to a base fabric for an air bag is performed. It is added to express and improve the properties. As the organic silicon compound, any organic silicon compound can be used as long as it has such an adhesiveness-imparting functional group, but an organic silicon compound having one or more epoxy groups and one or more silicon-bonded alkoxy groups in one molecule. It is preferably a silicon compound, and has at least one epoxy group and at least one silicon-bonded alkoxy group (for example, a trialkoxysilyl group, an organodialkoxysilyl group, and the like) from the viewpoint of adhesion development. An organosilicon compound, for example, an organosilane, or a cyclic or linear organosiloxane having about 2 to 100, preferably about 4 to 50 silicon atoms, wherein at least one epoxy group and at least two Those having a silicon atom-bonded alkoxy group are more preferred.

The epoxy group is, for example, a glycidoxyalkyl group such as a glycidoxypropyl group; an epoxy-containing cyclohexylalkyl group such as a 2,3-epoxycyclohexylethyl group or a 3,4-epoxycyclohexylethyl group; It is preferably bonded to
The silicon-bonded alkoxy group is bonded to a silicon atom to form, for example, a trialkoxysilyl group such as a trimethoxysilyl group or a triethoxysilyl group; a methyldimethoxysilyl group, an ethyldimethoxysilyl group, a methyldiethoxysilyl group, It is preferable to form an alkyldialkoxysilyl group such as an ethoxysilyl group.

  The component (E) includes, in one molecule, functional groups other than an epoxy group and a silicon-bonded alkoxy group, such as an alkenyl group such as a vinyl group, an acryl group, a (meth) acryloxy group, an isocyanate group, and a hydrosilyl group. It may have at least one functional group selected from the group consisting of groups (SiH groups).

  As the organosilicon compound of the component (E), for example, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, (3,4-epoxycyclohexylethyl) trimethoxysilane, (3, 4-epoxycyclohexylethyl) triethoxysilane, (3,4-epoxycyclohexylethyl) methyldimethoxysilane, (3,4-epoxycyclohexylethyl) methyldiethoxysilane, (2,3-epoxycyclohexylethyl) triethoxysilane, Epoxy group-containing silane coupling agents such as (2,3-epoxycyclohexylethyl) methyldimethoxysilane and (2,3-epoxycyclohexylethyl) methyldiethoxysilane (ie, epoxy-functional group-containing organoalkoxysilane); Vinyl group-containing silane coupling agent such as nyltrimethoxysilane; acrylic group-containing silane coupling agent such as 3-acryloxypropyltrimethoxysilane; isocyanate group-containing silane coupling agent such as 3-isocyanatopropylethoxysilane; A silane coupling agent such as a methoxysilyl-modified allyl isocyanurate; an organosilicon compound such as a cyclic organopolysiloxane or a linear organopolysiloxane represented by the following chemical formula; a mixture of two or more of these; Species or two or more kinds of partially hydrolyzed condensates are exemplified.

（式中、ｈは１〜１０の整数、ｋは０〜４０の整数、好ましくは０〜２０の整数、ｐは１〜４０の整数、好ましくは１〜２０の整数、ｑは１〜１０の整数である。）

(Wherein, h is an integer of 1 to 10, k is an integer of 0 to 40, preferably an integer of 0 to 20, p is an integer of 1 to 40, preferably an integer of 1 to 20, and q is an integer of 1 to 10. It is an integer.)

  The amount of the component (E) is 0.1 to 10 parts by mass, preferably 0.25 to 5 parts by mass, per 100 parts by mass of the organopolysiloxane of the component (A). If the amount is less than 0.1 parts by mass, the resulting composition may not have sufficient adhesive strength. If the amount exceeds 10 parts by mass, the thixotropy of the composition will increase, the fluidity will decrease, and the coating workability may deteriorate.

  When the component (E) contains an alkenyl group and / or a SiH group, the components (B) and (B) relative to a total of 1 mol (or number) of silicon-bonded alkenyl groups contained in the component (A) in the composition. E) The total amount of SiH groups contained in the component is 1 to 10 mol (or number), preferably 1.2 to 9 mol (or number), more preferably 1.5 to 8 mol (or number). is there. If the amount of the SiH group is less than 1 mol relative to 1 mol of the silicon-bonded alkenyl group in the composition, the composition may not be cured sufficiently and may not have sufficient adhesive strength. On the other hand, if it exceeds 10 mol, the heat resistance of the obtained cured silicone rubber may be extremely deteriorated.

[Other ingredients]
In addition to the above components (A) to (E), any other components can be added to the composition according to the present invention as long as the object of the present invention is not impaired. Specific examples include the following. Each of these other components may be used alone or in combination of two or more.

[(F) component]
The condensation catalyst of the component (F) is selected from an organic titanium compound, an organic zirconium compound, and an organic aluminum compound. In order to promote adhesion, the condensation catalyst serves as a condensation co-catalyst of the adhesion imparting functional group in the component (E). It works. As the component (F), one type can be used alone, or two or more types can be used in appropriate combination. Specific examples of the component (F) include, for example, organic titanates such as titanium tetraisopropoxide, titanium tetranormal butoxide, titanium tetra-2-ethylhexoxide; titanium diisopropoxy bis (acetylacetonate); Titanium-based condensation co-catalysts (titanium compounds) such as organic titanium chelate compounds such as titanium diisopropoxybis (ethyl acetoacetate) and titanium tetraacetylacetonate; organic zirconium esters such as zirconium tetranormal propoxide and zirconium tetranormal butoxide; Organic zirconium such as zirconium tributoxy monoacetylacetonate, zirconium mono (butoxyacetylacetonate) bis (ethylacetoacetate), zirconium tetra (acetylacetonate) Zirconium-based condensation promoters (zirconium compounds) such as chelate compounds; organic aluminum esters such as aluminum secondary butoxide; aluminum trisacetylacetonate; aluminum bis (ethylacetoacetate) monoacetylacetonate; aluminum tris (ethylacetoacetate); And aluminum-based condensation promoters such as organic aluminum chelate compounds.

  The component (F) is an optional component that is added as needed. The amount of the component is usually 5 parts by mass or less (0.01 to 5 parts by mass) based on 100 parts by mass of the component (A). ), But preferably 0.1 to 5 parts by mass, more preferably 0.2 to 3 parts by mass. If the compounding amount is less than 0.1 part by mass, the obtained cured product may be liable to have reduced adhesive durability under high temperature and high humidity. If the compounding amount exceeds 5 parts by mass, the obtained cured product may be obtained. May have extremely low heat resistance.

-Reaction control agent The reaction control agent is not particularly limited as long as it is a compound having a curing inhibitory effect on the hydrosilylation reaction catalyst of the component (D), and a known one can be used. Specific examples thereof include phosphorus-containing compounds such as triphenylphosphine; nitrogen-containing compounds such as tributylamine, tetramethylethylenediamine, and benzotriazole; sulfur-containing compounds; acetylene-based compounds such as acetylene alcohols; and containing two or more alkenyl groups. Compounds; hydroperoxy compounds; maleic acid derivatives and the like.

  Since the degree of the curing inhibitory effect of the reaction control agent varies depending on the chemical structure of the reaction control agent, the amount of the reaction control agent is preferably adjusted to an optimum amount for each reaction control agent used. By adding an optimal amount of the reaction control agent, the composition has excellent long-term storage stability at room temperature and excellent curability.

Non-reinforcing fillers As fillers other than the silica powder as the component (C), for example, crystalline silica (for example, quartz powder having a BET specific surface area of less than 50 m ² / g), organic resin hollow filler, polymethyl Silsesquioxane fine particles (so-called silicone resin powder), fumed titanium dioxide, magnesium oxide, zinc oxide, iron oxide, aluminum hydroxide, magnesium carbonate, calcium carbonate, zinc carbonate, carbon black, diatomaceous earth, talc, kaolinite, Filler such as glass fiber; Filler whose surface is hydrophobized with organosilicon compound such as organoalkoxysilane compound, organochlorosilane compound, organosilazane compound, low molecular weight siloxane compound; silicone rubber powder; silicone resin powder And the like.

.Other components In addition, for example, an organopolysiloxane containing one silicon-bonded hydrogen atom in one molecule and containing no other functional group, one silicon-bonded alkenyl group in one molecule , An organopolysiloxane containing no other functional groups, a non-functional organopolysiloxane containing no silicon-bonded hydrogen atoms, no silicon-bonded alkenyl groups, or other functional groups (so-called dimethyl silicone oil); An organic solvent, an anti-creep hardening agent, a plasticizer, a thixotropic agent, a pigment, a dye, a fungicide and the like can be added. An organopolysiloxane containing one silicon-bonded hydrogen atom in one molecule and containing no other functional group, containing one silicon-bonded alkenyl group in one molecule and containing another functional group When an organopolysiloxane not containing is contained, the total amount of SiH groups is 1 to 10 mol (or number), preferably 1 mol (or number) of silicon-bonded alkenyl groups in the composition as a whole. Is 1.2 to 9 mol (or number), more preferably 1.5 to 8 mol (or number).

<Preparation of liquid silicone rubber composition>
In addition to the components (A) to (E), a liquid silicone rubber composition can be prepared by uniformly mixing other components such as the component (F) as required with a stirrer or the like.

<Production method of silicone-coated base fabric for airbag>
The method for producing a silicone-coated base fabric for an airbag has the following first to third steps.
At least one surface of a base fabric for an air bag is coated with a liquid silicone rubber composition having a viscosity of 5,000 to 300,000 mPa · s at 25 ° C. so that a coating amount is 80 to 300 g / m ^2. The first step to do
A second step of reducing the coating amount of the coated liquid silicone rubber composition to 10 to 60 g / m ² , and a third step of curing the liquid silicone rubber composition after the reduction in weight. In addition, it is possible to manufacture a silicone-coated base fabric capable of producing an airbag having excellent internal pressure retention and excellent internal pressure retention.

<First step>
Liquid silicone rubber composition coating weight 80~300g / m ² in base fabric for air bags in the first step, preferably coated with a range of 100 to 200 g / m ^2. When the coating material is less than 80 g / m ² , sufficient airtightness improvement required for an air bag cannot be obtained, and the internal pressure retention property becomes insufficient. When the coating material exceeds 300 g / m ² , the improvement effect reaches a plateau, When the amount of liquid silicone rubber is reduced in the second step, workability is poor and uneconomical.

  The coating can be performed by a known method, for example, knife coating, gravure coating, roll coating, bar coating, die coating, dipping, and the like. Knife coating is simple and preferred. Moreover, you may implement coating alone or in combination depending on the situation.

<Second step>
In the second step, the coating amount of the liquid silicone rubber composition coated on the airbag base fabric in the first step is reduced to 10 to 60 g / m ² , preferably 15 to 55 g / m ^2. I do. If the coating amount after the weight reduction is less than 10 g / m ² , sufficient airtightness improvement required for the air bag cannot be obtained, and the internal pressure holding property becomes insufficient. If the coating amount exceeds 60 g / m ² , the blocking resistance becomes poor. become worse.
After coating with a certain amount in the first step and then reducing it to a certain amount in the second step, the seam (the part with the largest unevenness) of the base cloth can be uniformly coated, improving airtightness. I do.

  Examples of the method of reducing the weight of the liquid silicone rubber composition include a method of scraping with a knife coater and a method of squeezing through between two rolls, and the method of scraping with a knife coater is simple and preferable.

<Third step>
The third step is a step of curing the liquid silicone rubber composition having a coating amount of 10 to 60 g / m ^{2 in} the ^second step.

  The liquid silicone rubber composition can be cured by a known curing method under known curing conditions. Specifically, for example, the liquid silicone rubber composition is cured by heating in a heating furnace at 100 to 240 ° C, preferably 120 to 200 ° C for 0.5 to 30 minutes, preferably 1 to 10 minutes. Can be.

  The interval between the first step and the second step or the interval between the second step and the third step is not particularly limited, but a shorter interval is preferable because the manufacturing equipment becomes more compact.

  The line speed in the first, second and third steps is preferably 1 m / min to 50 m / min, more preferably 5 m / min to 40 m / min. If the line speed is lower than this, the productivity will be poor, and if the line speed is higher than this, the liquid silicone rubber composition may not be sufficiently cured in the third step.

<Manufacturing method of airbag>
A known method can be used as a method for manufacturing an airbag using the present invention. For example, the liquid silicone composition is coated on both sides of an airbag base fabric having a bag weave structure in which a bag portion is formed in advance by weaving through the first and second steps of the present invention, and the third step is performed. A method of manufacturing an air bag by curing the liquid silicone rubber composition, or a plain woven fabric as a base fabric, and after manufacturing a silicone-coated base fabric on one side through the first to third steps of the present invention, A method in which the outer peripheral portions of the two silicone-coated plain woven fabrics are stuck together with an adhesive, and the adhesive layers are stitched to produce an airbag.

  Hereinafter, the present invention will be described specifically with reference to Examples and Comparative Examples, but these Examples do not limit the present invention at all. Here, “parts” means “parts by mass”, and the viscosity is a value measured by a rotational viscometer at 25 ° C.

[Preparation Example 1]
60 parts of dimethylpolysiloxane (A) having a viscosity of about 30,000 mPa · s and an average degree of polymerization of 750 and having both ends of a vinyldimethylsiloxy group blocked at the molecular chain, 8 parts of hexamethyldisilazane, 2 parts of water, and BET 40 parts of silica fine powder (C) (trade name: Aerosil 300, manufactured by Nippon Aerosil Co., Ltd.) having a specific surface area of about 300 m ² / g by a method were mixed in a kneader for 1 hour. Thereafter, 8 parts of hexamethyldisilazane was charged and mixed for another hour. Next, the temperature in the kneader was raised to 150 ° C., followed by mixing for 2 hours. Next, after the temperature was lowered to 100 ° C., 30 parts of dimethylpolysiloxane (A) having a viscosity of about 30,000 mPa · s and an average degree of polymerization of 750, both ends of which had been blocked with vinyldimethylsiloxy groups at both molecular chains, were added. By mixing until uniform, a base compound was obtained.

[Preparation Example 2]
52.5 parts of a dimethylpolysiloxane (A) having a viscosity of about 30,000 mPa · s and an average degree of polymerization of 750 at both ends of a molecular chain having vinyldimethylsiloxy groups capped at 128 parts of the base compound obtained in Preparation Example 1. A dimethylhydrogensiloxy group-blocked dimethyl both ends of a molecular chain having a hydrogen atom bonded to a silicon atom at both ends of the molecular chain and a non-terminal of the molecular chain having a viscosity of 9 mPa · s and an average degree of polymerization of 16 as a crosslinking agent. 4.1 parts of siloxane / methyl hydrogen siloxane copolymer (B) (SiH group content: 0.0032 mol / g) (SiH group / vinyl group = 2.0 mol / mol), γ-glycidoxypropyltrimethoxysilane ( E) 0.3 part, 1-ethynylcyclohexanol 0.05 part, chloroplatinic acid / 1,3-divinyltetramethyldisilo A liquid silicone rubber was prepared by mixing 0.2 parts of a dimethylpolysiloxane solution (D) containing 1% by mass of a platinum complex as a sun complex and 0.36 parts of titanium tetraacetylacetonate (F) with a stirrer for 1 hour. A composition (viscosity 200,000 mPa · s) was prepared.

[Example 1]
In the first step, 160 g of the liquid silicone rubber composition prepared in Preparation Example 2 was applied with a batch-type knife coater while pulling a base fabric for an air bag (made of nylon 66, 210 denier) having a bag structure at 50 kgf. / M ² . Next, as a second step, the amount of the liquid silicone rubber composition was reduced to 40 g / m ² using a knife coater. Finally, as a third step, the liquid silicone rubber composition was cured by placing it in a dryer at 180 ° C. for 3 minutes. After that, the other side is similarly subjected to silicone coating and curing through the first to third steps, to produce a woven airbag coated with silicone on both sides, and subjected to an internal pressure retention test and a blocking resistance test described later. The results are shown in Table 1.

<Internal pressure retention test method>
An internal pressure retention test was performed using the woven airbag coated with silicone on both sides prepared in Example 1. In the internal pressure retention test, the created air bag was inflated at a pressure of 100 kPa, and the residual pressure after 30 seconds was measured with a device manufactured by Miroku Seiki Seisaku-sho, Ltd., and evaluated based on this value.

<Blocking resistance test>
The test was performed to evaluate the stickiness of the surface of the rubber coating layer. The produced silicone rubber-coated airbag was cut into a width of 100 mm and a length of 200 mm, and the silicone rubber-coated surface of the obtained film-forming cloth was brought into close contact with the glass plate so that air did not enter. The glass plate on which the film-forming cloth adhered was set upright, the elapsed time until the film-forming cloth naturally dropped from the glass plate was measured, and evaluated according to the following evaluation criteria. As described above, when the elapsed time from when the glass plate on which the film forming cloth adhered was stood upright to when the film forming cloth fell from the glass plate was less than 1 second, it was evaluated as “good”. The case where the time was not shorter than 6 seconds and shorter than 6 seconds was evaluated as “OK”, and the case where it was longer than 6 seconds was evaluated as “poor”.

[Example 2]
In the first step, 200 g of the liquid silicone rubber composition prepared in Preparation Example 2 was applied with a batch-type knife coater while pulling a base fabric for an air bag having a bag structure (made of nylon 66, 210 denier) at 50 kgf. / M ² . Next, as a second step, the amount of the liquid silicone rubber composition was reduced to 60 g / m ² using a knife coater. Finally, as a third step, the liquid silicone rubber composition was cured by placing it in a dryer at 180 ° C. for 3 minutes. After that, the other side is similarly subjected to silicone coating and curing through the first to third steps, to prepare a silicone-coated airbag with both sides coated, and to prepare a silicone-coated airbag and perform Table 1 shows the results of the internal pressure retention test and the blocking resistance test performed in the same manner as in Example 1.

[Comparative Example 1]
With the air bag having a bag structure (made of nylon 66, 210 denier) pulled at 50 kgf, the liquid silicone rubber composition prepared in Preparation Example 2 was coated with a batch-type knife coater to 40 g / m ² . . Next, the liquid silicone rubber composition was cured by placing it in a dryer at 180 ° C. for 3 minutes. Thereafter, the other side was similarly coated with silicone, a silicone-coated airbag was produced, and the internal pressure retention test and the blocking resistance test were performed in the same manner as in Example 1. The results are shown in Table 1.

[Comparative Example 2]
In a first step, the liquid silicone rubber composition prepared in Preparation Example 2 was pulled at 60 g / m ² using a batch type knife coater while pulling an air bag (made of nylon 66, 210 denier) having a bag structure at 50 kgf. It was coated to become. Next, as a second step, the amount of the liquid silicone rubber composition was reduced to 40 g / m ² using a knife coater. Finally, as a third step, the liquid silicone rubber composition was cured by placing it in a dryer at 180 ° C. for 3 minutes. Thereafter, the other side is similarly coated with silicone through the first to third steps to produce a silicone-coated airbag, and subjected to an internal pressure retention test and a blocking resistance test as in Example 1. The results are shown in Table 1.

[Comparative Example 3]
As a first step, a liquid silicone rubber composition prepared in Preparation Example 2 was 160 g / m ² with a batch type knife coater in a state where an air bag having a bag structure (made of nylon 66, 210 denier) was pulled at 50 kgf. It was coated to become. Next, as a second step, the amount of the liquid silicone rubber composition was reduced to 100 g / m ² using a knife coater. Finally, as a third step, the liquid silicone rubber composition was cured by placing it in a dryer at 180 ° C. for 3 minutes. Thereafter, the other side is similarly coated with silicone through the first to third steps to produce a silicone-coated airbag, and subjected to an internal pressure retention test and a blocking resistance test as in Example 1. The results are shown in Table 1.

Claims (2)

A method for producing a silicone-coated base fabric for an airbag, having a silicone rubber layer on at least one surface of the base fabric for an airbag,
At least one surface of a base fabric for an air bag is coated with a liquid silicone rubber composition having a viscosity of 5,000 to 300,000 mPa · s at 25 ° C. so that a coating amount is 80 to 300 g / m ^2. The first step to do
A second step of reducing the coating amount of the coated liquid silicone rubber composition to 10 to 60 g / m ² , and a third step of curing the reduced liquid silicone rubber composition,
A method for producing a silicone-coated base fabric for an airbag, comprising:   The method for producing a silicone-coated base fabric for an airbag according to claim 1, wherein the coating method of the liquid silicone rubber composition in the first step is knife coating, gravure coating, roll coating, bar coating, die coating or dipping.