JP2008062882A - Airbag - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an airbag having airtightness maintainable for a long period even if it repeatedly receives a temperature change and having excellent productivity and high quality. <P>SOLUTION: This airbag is formed by so overlapping or folding down a synthetic fiber fabric 2 having one surface covered with a silicone rubber 3 that the covered surface is positioned inside and binding its outer peripheral part with the bonding by a two-component reaction hardening type silicone rubber composition and the sewing by yarn to form it in a bag shape. The airbag is characterized in that the two-component reaction hardening type silicone rubber composition contains, as a filler, a quartz within the range of 1 to 25 μm in average grain size. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an airbag that is mounted on a vehicle or the like and protects an occupant from an impact such as a collision or rollover. More specifically, the present invention relates to an airbag having excellent airtightness over a long period of time and excellent productivity.

  It has been a long time since a vehicle seat airbag, a passenger seat airbag, a passenger seat airbag, and a rear seat airbag have been installed as vehicle airbags. In recent years, the use of side airbags and curtain airbags corresponding to side collisions has increased. Among these, curtain airbags corresponding to vehicle rollovers have attracted attention, especially for several seconds during which the vehicle rolls over in order to absorb the impact on the occupant's head. The internal pressure is required to be maintained. In order to cope with these various types of airbags, there is an urgent need to develop an airbag capable of increasing the airtightness of the airbag and extending the duration of inflation more than before.

  As such an airbag, for example, Patent Document 1 discloses that the edges of two panels made of a woven fabric having a silicone-based sealing coating are bonded to each other by an elastic adhesive and stitched with a thread. An airbag in which gas leakage from the coupling portion is prevented by coupling is disclosed. As an elastic adhesive used for such a purpose, a silicone rubber composition, and preferably an addition reaction curable silicone rubber composition can be mentioned most commonly. Addition reaction curable silicone rubber composition is easy to adjust curability, can be cured by room temperature or slight heating, and does not generate by-products during curing, which is advantageous in terms of production cost and environment It is.

  The addition reaction curable silicone rubber composition generally comprises an organopolysiloxane (silicone raw rubber) having an average of 2 or more alkenyl groups in one molecule as a main agent and an average of 2 or more silicon atoms in a molecule as a curing agent. It consists of an organohydrogenpolysiloxane having bonded hydrogen atoms, a catalyst, and a filler. There have been reports of attempts to impart or improve various physical properties by ingenuating this filler.

For example, Patent Document 2 discloses that hydrogen gas that can occur during storage of an addition reaction curable silicone rubber composition by containing calcium carbonate powder surface-treated with a partial hydrolysis condensate of tetraalkoxysilane as a filler. Disclosed is a technology for improving the heat resistance, electrical insulation, and rubber physical properties of silicone rubber (hereinafter sometimes referred to simply as “silicone rubber” or “cured product”) obtained by curing while suppressing generation and improving storage stability. ing. Patent Document 3 contains an alkaline earth metal carbonate powder surface-treated with an organopolysiloxane as a filler, and in addition to the effects of Patent Document 2, protects electric and electronic parts from corrosion in a cured product. A technique for providing the ability to improve the adhesiveness is disclosed. Patent Document 4 discloses a technique for improving the adhesion of a cured product to silicone rubber by containing calcium carbonate powder having a BET specific surface area of 5 to 50 m ² / g as a filler. Moreover, the technique which improves the mechanical strength of hardened | cured material is disclosed by containing the silica powder whose BET specific surface area is 50 m < ² > / g or more as arbitrary fillers.

  Cured products of these addition reaction curable silicone rubber compositions exhibit adhesion to silicone rubber and are excellent in physical properties such as strength. However, there has been a problem that physical characteristics, particularly elongation, are remarkably lowered due to repeated changes in temperature and humidity over a long period of time. When such a composition is used for bonding the woven fabrics constituting the airbag, the silicone rubber that has deteriorated over time cannot withstand the gas pressure generated from the inflator when the airbag is inflated and peels from the woven fabric. And this will cause a gas leak. Gas leaks are a very serious problem for curtain airbags that require long-term internal pressure retention.

  Patent Document 5 discloses a technique for improving the elongation of silicone rubber by containing a molecular chain both-end organohydrogensiloxy group-blocked organopolysiloxane having a viscosity at 25 ° C. of at least 100 mPa · s as a curing agent. However, this does not correspond to a decrease in physical characteristics over time.

  In Patent Document 6, as the filler, together with calcium carbonate powder, one or more selected from the group consisting of quartz, aluminum hydroxide, alumina, titanium dioxide, zinc oxide, iron oxide, magnesium carbonate, and carbon black. A technique for suppressing the increase in viscosity that may occur during storage of the two-component addition reaction curable silicone rubber composition and stabilizing the physical properties of the cured product by containing the inorganic powder is disclosed. Even if this cured product is repeatedly subjected to temperature and humidity changes over a long period of time, the physical properties thereof are hardly deteriorated. However, since the viscosity of this composition is remarkably reduced by mixing the two liquids, the width and thickness of the cured product do not reach the designed values when used in the production of an airbag, and the appearance of the airbag is not good. As a result, the yield is poor and the productivity is lowered. It is a common technique to store the addition reaction curable silicone rubber composition in two liquids and to mix and cure the two liquids during use.

JP 2001-1854 A Japanese Patent Laid-Open No. 10-60281 JP 2002-38016 A JP 2002-285130 A JP 2005-82661 A JP 2006-117823 A

  The present invention has been made in view of such a current situation, and the object of the present invention is to maintain high airtightness even when repeatedly subjected to temperature and humidity changes over a long period of time, and to achieve high quality with excellent productivity. Is to provide an airbag.

  As a result of intensive studies to solve the above problems, the present inventor has added a two-component solution containing quartz having an average particle diameter in the range of 1 to 25 μm as a filler for joining fabrics constituting an airbag. By using a reaction curable silicone rubber composition, deterioration of the silicone rubber over time can be suppressed, gas leakage from the joint can be highly prevented, and the airtightness of the airbag can be maintained. Finding that high-quality airbags with excellent appearance and excellent productivity can be obtained by suppressing the decrease in viscosity of the composition after mixing, making it easy to adjust the width and thickness after curing. The present invention has been completed based on the above.

  That is, the present invention is a method in which a synthetic fiber fabric coated on one side with silicone rubber is polymerized or folded so that the coated surface is on the inside, and the outer peripheral portion is joined with the two-component addition reaction curable silicone rubber composition. In an airbag formed into a bag shape by being bonded by stitching with a thread, the two-component addition reaction-curable silicone rubber composition contains quartz having an average particle diameter in the range of 1 to 25 μm as a filler. The air bag is characterized.

  According to the present invention, it is possible to maintain airtightness even when repeated changes in temperature and humidity over a long period of time, and it is possible to obtain a high-quality airbag excellent in productivity.

Hereinafter, the present invention will be described in detail.
In the airbag of the present invention, a synthetic fiber fabric coated on one side with silicone rubber is polymerized or folded so that the coated surface is on the inside, and the outer periphery is joined with a two-component addition reaction curable silicone rubber composition. It is formed into a bag shape by being joined by stitching with thread.

  The synthetic fiber fabric used in the present invention means a fabric woven using synthetic fiber yarns, and the structure thereof is not particularly limited, and plain weave, twill weave, satin weave, and these modified weaves, A shaft weave can be mentioned. Of these, a plain woven fabric is preferred in that it is excellent in mechanical strength and can be reduced in thickness. The type of synthetic fiber is not particularly limited, but polyamide fiber and polyester fiber are preferable because they are easy to manufacture and have excellent heat resistance, and polyamide fiber is preferable because of excellent impact resistance and large heat capacity. More preferred. These synthetic fibers may contain a heat resistance improver, an antioxidant, a flame retardant, an antistatic agent, and the like. In addition, the form of the yarn, the fineness, the density of the fabric, the basis weight, and the like are not particularly limited, and those usually used for airbags may be appropriately selected. The woven fabric may be subjected to scouring and heat treatment.

  The synthetic fiber fabric used in the present invention has one surface coated with silicone rubber. By covering with silicone rubber, the air permeability of the fabric itself can be lowered, and the fabric can be imparted with heat resistance, flame retardancy, weather resistance, and fraying prevention properties. The silicone rubber used for such a purpose is mainly composed of an organopolysiloxane having an average of two or more alkenyl groups in one molecule. Examples of the alkenyl group include a vinyl group, an allyl group, a butenyl group, a pentenyl group, a hexenyl group, and a heptenyl group, and a vinyl group is preferable. Examples of the organic group bonded to the silicon atom other than the alkenyl group include alkyl groups such as methyl group, ethyl group, propyl group, butyl group, pentyl group, and hexyl group; aryl groups such as phenyl group, tolyl group, and xylyl group A halogenated alkyl group such as a 3-chloropropyl group or a 3,3,3-trifluoropropyl group, and a methyl group is preferable. Examples of the molecular structure include a straight chain, a partially branched straight chain, a branched chain, a net, and a dendritic.

  Examples of such organopolysiloxane include dimethylpolysiloxane blocked with dimethylvinylsiloxy group at both ends of the molecular chain, dimethylsiloxane / methylvinylsiloxane copolymer blocked with dimethylvinylsiloxy group at both ends of the molecular chain, and dimethylvinylsiloxy at both ends of the molecular chain. Examples thereof include a group-capped dimethylsiloxane / methylphenylsiloxane copolymer and a molecular chain both-end dimethylvinylsiloxy group-capped methyl (3,3,3-trifluoropropyl) siloxane / methylvinylsiloxane copolymer. The viscosity of these silicone rubbers at 25 ° C. is preferably in the range of 1,000 to 50,000 cps in consideration of the strength of the silicone rubber coating film and blending workability.

For these silicone rubbers, for example, as a curing agent for crosslinking and curing the silicone rubber, for example, molecular chain both ends trimethylsiloxy group-capped methylhydrogenpolysiloxane, molecular chain both ends trimethylsiloxy group-capped dimethylsiloxane・ Methylhydrogensiloxane copolymer, dimethylphenylsiloxy group-blocked methylphenylsiloxane with molecular chain terminals at both ends ・ Methylhydrogensiloxane copolymer, cyclic methylhydrogenpolysiloxane, dimethylhydrogensiloxane unit and formula: SiO _4/2 Organohydrogenpolysiloxanes comprising the indicated siloxane units;
As a catalyst for accelerating the curing reaction, for example, platinum fine powder, platinum black, chloroplatinic acid, platinum tetrachloride, chloroplatinic acid alcohol solution, platinum olefin complex, platinum alkenylsiloxane complex, platinum carbonyl complex, Fine powder obtained by dispersing these platinum-based catalysts in thermoplastic organic resins such as methyl methacrylate resin, polycarbonate resin, polystyrene resin, and silicone resin;
As fillers for the purpose of reinforcing silicone rubber, adjusting viscosity, improving heat resistance, improving flame retardancy, etc., for example, fumed silica, precipitated silica, fine powdered silica such as calcined silica, fumed titanium oxide, etc. Reinforcing fillers, non-reinforcing fillers such as pulverized quartz, diatomaceous earth, iron oxide, aluminum oxide, calcium carbonate, magnesium carbonate, organic acids such as fatty acids and resin acids, organosilanes, organopolysiloxanes. , Surface treated with organosilicon compounds such as organoalkoxysilane, organohalosilane, organosilazane, etc .;
As an adhesion-imparting agent for improving adhesion to synthetic fiber fabrics, for example, epoxy group-containing organoalkoxysilanes such as 3-glycidoxypropyltrimethoxysilane, silicon atom-bonded vinyl groups and epoxy group-containing epoxy groups Epoxy group-containing organopolysiloxanes such as organopolysiloxanes, epoxy group-containing organopolysiloxanes having silicon-bonded hydrogen atoms, and epoxy-group-containing organopolysiloxanes having silicon-bonded hydrogen atoms and alkoxy groups;
In addition, various additives such as a curing inhibitor, an organopolysiloxane resin, a pigment, and a heat-resistant agent can be contained.

The form of the silicone rubber used in the present invention is not particularly limited, and examples thereof include a solventless type, a solvent dilution type, and a water dispersion type, but a solventless type is preferable from the viewpoint of workability and environment. The coating method is not particularly limited, and examples thereof include knife coating, gravure coating, spray coating, and lamination. Among these, knife coating is preferable from the viewpoint of workability. Moreover, it is preferable that it is in the range of 5-60 g / m < ² > as an application quantity of silicone rubber. If the coating amount is less than the lower limit of the above range, the air permeability of the fabric is increased, and the air tightness of the airbag may be poor. If the coating amount exceeds the upper limit of the above range, the thickness of the woven fabric may increase, resulting in poor airbag storage.
Hereinafter, “synthetic fiber fabric coated on one side with silicone rubber” may be simply referred to as “coating fabric”.

  In order to produce the airbag of the present invention, the two-component addition reaction curable silicone rubber composition is typically prepared by cutting the coated fabric into a predetermined shape and then polymerizing or folding the coated fabric so that the silicone rubber coating surface is on the inside. It joins with a thing, The junction part or its vicinity is sewn with a thread | yarn, and it forms in a bag shape. In addition, the coated fabric sent from the raw fabric can be produced by polymerizing and joining so that the silicone rubber coated surface is inside, and then cutting into a predetermined shape and stitching. There is almost no deviation between the opposing panels, and the dimensional accuracy is excellent, the volume when the airbag is folded is reduced, and the storage property is excellent. Further, it is possible to accurately position a bolt hole for attachment to a vehicle or the like, and a predetermined expanded shape can be easily obtained. Furthermore, after joining the coated fabric, it can be cut after being sewn, and according to this step, the airbag can be continuously manufactured by a series of devices.

  The two-component addition reaction curable silicone rubber composition used in the present invention is required to contain quartz having an average particle diameter in the range of 1 to 25 μm as a filler. This is the same as the reaction-curable silicone rubber composition. That is, as other components, at least the main component, the curing agent, and the catalyst are included, and these components are stored in two liquids.

  As the main agent, an organopolysiloxane having an average of 2 or more alkenyl groups in one molecule is used. Examples of the alkenyl group include a vinyl group, an allyl group, a butenyl group, a pentenyl group, a hexenyl group, and a heptenyl group, and a vinyl group is preferable. Examples of organic groups bonded to silicon atoms other than alkenyl groups include alkyl groups such as methyl, ethyl, propyl, butyl, pentyl, and hexyl groups; phenyl groups, tolyl groups, xylyl groups, and the like. An aryl group; halogenated alkyl groups such as 3-chloropropyl group and 3,3,3-trifluoropropyl group can be exemplified, and a methyl group is preferable. Examples of the molecular structure include a straight chain, a partially branched straight chain, a branched chain, a net, and a dendritic.

Examples of such organopolysiloxanes include dimethylpolysiloxane blocked with dimethylvinylsiloxy group at both ends of the molecular chain, dimethylsiloxane / methylvinylsiloxane copolymer blocked with dimethylvinylsiloxy group at both ends of the molecular chain, and trimethylsiloxy group at both ends of the molecular chain. Blocked dimethylsiloxane / methylvinylsiloxane copolymer, siloxane unit represented by the formula: (CH ₃ ) ₃ SiO _1/2 and siloxane unit represented by the formula: (CH ₃ ) ₂ (CH ₂ = CH) SiO _1/2 And an organopolysiloxane composed of a siloxane unit represented by SiO _4/2 , a part or all of the methyl groups of these organopolysiloxanes are alkyl groups such as ethyl group and propyl group; aryl such as phenyl group and tolyl group Group; 3,3,3-trifluoropropyl group Organopolysiloxanes substituted with halogenated alkyl groups such as, organopolysiloxanes in which some or all of the vinyl groups of these organopolysiloxanes are substituted with alkenyl groups such as allyl groups, propenyl groups, and the like. A mixture of two or more may be mentioned.

  As the curing agent, an organohydrogenpolysiloxane having an average of 2 or more silicon-bonded hydrogen atoms in one molecule is used. Examples of the organic group bonded to the silicon atom include alkyl groups such as a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, and a hexyl group; an aryl group such as a phenyl group, a tolyl group, and a xylyl group; A halogenated alkyl group such as a propyl group and a 3,3,3-trifluoropropyl group can be exemplified, and a methyl group is preferred. Examples of the molecular structure include a straight chain, a partially branched straight chain, a branched chain, a net, and a dendritic.

Examples of such organohydrogenpolysiloxane include, for example, molecular chain both ends trimethylsiloxy group-blocked methylhydrogen polysiloxane, molecular chain both ends dimethylhydrogensiloxy group-blocked dimethylpolysiloxane, molecular chain both ends trimethylsiloxy group-blocked dimethyl. Siloxane / methylhydrogensiloxane copolymer, dimethylphenylsiloxy group-capped methylphenylsiloxane / methylhydrogensiloxane copolymer, cyclic methylhydrogenpolysiloxane, dimethylhydrogensiloxane unit and formula: SiO _4/2 Organohydrogenpolysiloxanes composed of siloxane units represented by the following: some or all of the methyl groups of these organohydrogenpolysiloxanes are ethyl, propyl An alkyl group such as a phenyl group; an aryl group such as a phenyl group and a tolyl group; an organohydrogenpolysiloxane substituted with a halogenated alkyl group such as a 3,3,3-trifluoropropyl group, and the organohydrogenpolysiloxane A mixture of two or more may be mentioned. Among these, the physical properties of the resulting cured product, particularly the elongation, is improved, so that organohydrogenpolysiloxane having silicon-bonded hydrogen atoms only at both ends of the molecular chain and silicon atom bonds in the side chains of the molecular chain. It is preferably a mixture of organohydrogenpolysiloxanes.

  In the silicone rubber composition obtained by mixing the two liquids, the content of the curing agent component is such that the molar ratio of silicon-bonded hydrogen atoms in this component to alkenyl groups in the main component is within a range of 0.01 to 20. It is preferable that the amount is within the range of 0.1 to 10, more preferably within the range of 0.1 to 5. If the content is less than the lower limit of the above range, the resulting silicone rubber composition may not be sufficiently cured. If the content exceeds the upper limit of the above range, the physical properties of the silicone rubber obtained by curing may be deteriorated. When a mixture of an organohydrogenpolysiloxane having a silicon atom-bonded hydrogen atom only at both ends of the molecular chain and an organohydrogenpolysiloxane having a silicon atom bond in the molecular chain side chain is used as the curing agent, the former The organohydrogenpolysiloxane content is preferably such that the molar ratio of silicon-bonded hydrogen atoms in this component to alkenyl groups in the main component is in the range of 0.01 to 10, more preferably The amount is in the range of 0.1 to 10, more preferably the amount is in the range of 0.1 to 5. The content of the latter organohydrogenpolysiloxane is preferably such that the molar ratio of silicon-bonded hydrogen atoms in this component to alkenyl groups in the main component is in the range of 0.5 to 20, The amount is preferably in the range of 0.5 to 10, and more preferably in the range of 0.5 to 5.

  The catalyst consists of an organopolysiloxane having an average of 2 or more alkenyl groups in one molecule as the main component, and an organohydrogenpolysiloxane having an average of 2 or more silicon-bonded hydrogen atoms in one molecule as the curing agent component. This is to accelerate the curing reaction with siloxane. Examples of the catalyst include platinum fine powder, platinum black, chloroplatinic acid, platinum tetrachloride, chloroplatinic acid alcohol solution, platinum olefin complex, platinum alkenyl siloxane complex, platinum carbonyl complex, and platinum-based catalysts. Examples thereof include fine powders dispersed in thermoplastic organic resins such as methyl methacrylate resin, polycarbonate resin, polystyrene resin, and silicone resin.

  In the silicone rubber composition obtained by mixing the two liquids, the content of the catalyst component is not particularly limited as long as it is sufficient to promote curing of the main agent component and the curing agent component, but preferably the main agent component 100. The amount is such that the platinum atom in the catalyst component is in the range of 0.01 to 500 parts by weight, more preferably in the range of 0.1 to 100 parts by weight with respect to 10,000 parts by weight. There exists a possibility that hardening reaction may not fully advance that content is less than the minimum of the said range. If the content exceeds the upper limit of the above range, the raw material cost becomes expensive, which is uneconomical.

  As the filler that characterizes the present invention, quartz having an average particle diameter in the range of 1 to 25 μm is used. Quartz is a colorless and transparent to white powder generally used as a non-reinforcing filler, an expanding filler and a heat conductive filler, and has a Mohs hardness of 7. By specifically selecting and using quartz having an average particle size in the range of 1 to 25 μm, it is possible to effectively suppress deterioration of the silicone rubber over time without causing a decrease in the viscosity of the composition after two-component mixing. it can. If the average particle size is less than the lower limit of the above range, the viscosity of the composition after the two-liquid mixing is remarkably increased, and the handleability may be deteriorated. If the average particle size exceeds the upper limit of the above range, the viscosity of the composition after mixing the two liquids may be reduced, resulting in a large variation in the shape of the joint made of the cured product, which may result in poor dimensional accuracy of the airbag. There is. Furthermore, the physical properties of the cured product may be reduced.

  In the silicone rubber composition obtained by mixing two liquids, the content of the quartz is preferably in the range of 1 to 200 parts by weight, more preferably 5 to 200 parts by weight with respect to 100 parts by weight of the main ingredient component. Within the range of the part. If the content is less than the lower limit of the above range, the effect of suppressing deterioration of the silicone rubber over time may not be sufficiently exhibited. When content exceeds the upper limit of the said range, there exists a possibility that elongation of hardened | cured material may fall.

  The two-component addition reaction curable silicone rubber composition used in the present invention comprises at least the main agent, the curing agent, the catalyst, and the specific filler described above, but as other preferred fillers, Examples thereof include calcium carbonate powder and silica powder.

By containing calcium carbonate powder, it is possible to improve the adhesion to the silicone rubber covering the synthetic fiber fabric. BET specific surface area of the calcium carbonate powder is preferably in the range of 5 to 50 m ² / g, more preferably in the range of 10 to 50 m ² / g. If the BET specific surface area is less than the lower limit of the above range, the effect of improving adhesiveness may not be sufficiently exhibited. If the BET specific surface area exceeds the upper limit of the above range, the amount of impurities contained in the calcium carbonate increases and the physical properties of the cured silicone rubber may deteriorate. Examples of the calcium carbonate powder used for such purposes include heavy (or dry pulverized) calcium carbonate powder, light (or precipitated) calcium carbonate powder, and these calcium carbonate powders as organic acids such as fatty acids and resin acids. Can be mentioned, preferably light (or precipitated) calcium carbonate powder, more preferably light (or precipitated) calcium carbonate powder surface-treated with an organic acid such as fatty acid or resin acid.

  In the silicone rubber composition obtained by mixing the two liquids, the content of the calcium carbonate powder is preferably in the range of 5 to 200 parts by weight, more preferably 10 to 10 parts by weight with respect to 100 parts by weight of the main ingredient component. Within the range of 100 parts by weight. There exists a possibility that the effect which improves the adhesiveness with respect to the silicone rubber which coat | covers a synthetic fiber fabric may not fully be exhibited as content is less than the minimum of the said range. If the content exceeds the upper limit of the above range, it may be difficult to prepare a uniform two-component addition reaction curable silicone rubber composition.

Moreover, the mechanical strength of the silicone rubber obtained by hardening can be improved by containing a silica powder. Examples of the silica powder used for such purposes include fumed silica, precipitated silica, calcined silica, and these silica powders such as organosilane, organopolysiloxane, organoalkoxysilane, organohalosilane, and organosilazane. The powder surface-treated with the organosilicon compound can be mentioned. Among these, in order to sufficiently improve the mechanical strength of the cured product, it is preferable to use silica powder having a BET specific surface area of 50 m ² / g or more.

  In the silicone rubber composition obtained by mixing the two liquids, the content of the silica powder is preferably in the range of 1 to 100 parts by weight, more preferably 1 to 50 parts per 100 parts by weight of the main component. Within the range of parts by weight. There exists a possibility that the effect which improves the mechanical strength of hardened | cured material may not fully be exhibited as content is less than the minimum of the said range. When the content exceeds the upper limit of the above range, the viscosity becomes high and the handling property may be lowered.

  Moreover, the two-component addition reaction curable silicone rubber composition used in the present invention may contain an adhesion-imparting agent for improving the adhesion. Examples of such an adhesion-imparting agent include 3-glycidoxypropyltrimethoxysilane, methyltrimethoxysilane, vinyltrimethoxysilane, allyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-aminopropyltrimethoxysilane. Silane coupling agents such as methoxysilane, N- (2-aminoethyl) -3-aminopropyltrimethoxysilane, bis (trimethoxysilyl) propane, bis (trimethoxysilyl) hexane; tetraethyl titanate, tetrapropyl titanate, tetra Titanium compounds such as butyl titanate, tetra (2-ethylhexyl) titanate, titanium ethyl acetonate, titanium acetyl acetonate; ethyl acetoacetate aluminum diisopropylate, aluminum tris ( Aluminum compounds such as tylacetoacetate), alkyl acetoacetate aluminum diisopropylate, aluminum tris (acetylacetonate), aluminum monoacetylacetonate bis (ethylacetoacetate); zirconium acetylacetonate, zirconium butoxyacetylacetonate, zirconium bis Zirconium compounds such as acetylacetonate and zirconium ethylacetoacetate can be mentioned.

  Furthermore, the two-component addition reaction curable silicone rubber composition used in the present invention preferably contains a curing inhibitor for improving the storage stability and handling operability. Examples of such a curing inhibitor include 3-methyl-1-butyn-3-ol, 3,5-dimethyl-1-hexyn-3-ol, and 3-phenyl-1-butyn-3-ol. Acetylene compounds; enyne compounds such as 3-methyl-3-penten-1-yne and 3,5-dimethyl-3-hexen-1-yne; 1,3,5,7-tetramethyl-1,3,5 , 7-tetravinylcyclotetrasiloxane, 1,3,5,7-tetramethyl-1,3,5,7-tetrahexenylcyclotetrasiloxane, silanol group-capped methylvinylsiloxane, molecular chain both-end silanol Organosiloxane compounds with vinyl groups of 5% by weight or more in one molecule such as group-blocked methylvinylsiloxane / dimethylsiloxane copolymer; benzotriazole, etc. Triazoles, phosphines, mercaptans, mention may be made of hydrazines.

  As other optional components, the two-component addition reaction curable silicone rubber composition used in the present invention includes, for example, fumed titanium oxide, carbon black, diatomaceous earth, iron oxide, aluminum oxide, aluminosilicate, zinc oxide, water Contains inorganic fillers such as aluminum oxide, silver and nickel; fillers whose surfaces are treated with the above organic acids and organosilicon compounds, various additives such as organopolysiloxane resins, pigments and heat-resistant agents You may do it.

  The method for preparing the two-component addition reaction curable silicone rubber composition used in the present invention is not particularly limited, and is prepared by mixing the main agent, curing agent, catalyst, filler, and optional components as necessary. can do. In addition, when containing an arbitrary component, when this changes in quality by heating mixing, adding after a heating process is preferable. When preparing the two-component addition reaction curable silicone rubber composition, a known kneading apparatus such as a two-roll, a kneader mixer, or a loss mixer can be used.

  The two-component addition reaction curable silicone rubber composition is preferable in terms of handling and storage stability as compared with the one-component type. It is important to prepare by separating the curing agent and the catalyst so that the curing reaction starts by mixing the two liquids. If it is the composition which mix | blended the hardening | curing agent with one liquid, a catalyst is mix | blended with the other liquid. The blending of the main agent, filler, and other optional components may be appropriately set in consideration of stability and fluidity. It is preferable to prepare the two liquids to have the same fluidity because the handling properties and the applied amount control when the two liquids are mixed and cured are facilitated.

  The viscosity at 25 ° C. immediately after mixing the two-component addition reaction curable silicone rubber composition is preferably in the range of 100 to 500 Pa · s. When the viscosity at 25 ° C. is less than the lower limit of the above range, the silicone rubber composition tends to flow, and the silicone rubber composition may spread or air bubbles may be mixed after coating. On the other hand, if the viscosity at 25 ° C. exceeds the upper limit of the above range, the handleability and application accuracy may be poor. Moreover, it is preferable that the viscosity at 25 degreeC of two compositions before mixing exists in the range of 100-500 Pa.s, respectively. Furthermore, if the respective viscosities are approximately equal, it is preferable because the handling property during mixing and the application amount control become easy.

  The airbag of the present invention uses the two-component addition reaction-curable silicone rubber composition described above to join the outer peripheral part of the polymerized or folded coating fabric, and further stitches the joined part or its vicinity with a thread. It is a thing.

  Examples of the application method of the two-component addition reaction curable silicone rubber composition include a method using a dispenser, screen printing, spraying, and the like, and may be appropriately selected. In addition, it is preferable to perform drying by heating immediately after applying the composition because the process time can be shortened.

  The width of the silicone rubber obtained by curing is preferably in the range of 5 to 20 mm. If the width of the silicone rubber is less than the lower limit of the above range, the strength of the joint portion may vary, and if the joint portion is a stress concentration portion when the airbag is inflated, breakage may occur. If the width of the silicone rubber exceeds the upper limit of the above range, the joint portion becomes bulky and the air bag may be unstorable. Moreover, it is preferable that the thickness of silicone rubber exists in the range of 0.05-2 mm. If the thickness of the silicone rubber is less than the lower limit of the above range, the airtightness of the airbag may not be maintained, and if the thickness of the silicone rubber exceeds the upper limit of the above range, the air bag may be unstorable. There is.

  The sewing is performed by sewing the joint portion or the vicinity thereof using an automatic sewing machine or a manual sewing machine. It is preferable to sew the vicinity of the joint portion in terms of preventing the silicone rubber from adhering to the sewing needle and preventing the needle portion from being damaged by opening a needle hole in the joint portion. Since the inflated shape of the airbag is defined by the joint portion, it is more preferable to sew the outside of the inflated portion in order to maintain the air bag inflated shape and airtightness.

  As a thread used for stitching, a synthetic fiber yarn made of polyamide fiber or polyester fiber can be used, and polyamide fiber is preferable in terms of impact resistance and high elongation. The fineness is not particularly limited, and a general-purpose material such as 1400 dtex or 900 dtex may be used. Further, the sewing form is not particularly limited, such as main stitching and double chain stitching.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to a following example. In addition, each evaluation test in an Example followed the following method.

(1) Dimensional Accuracy of Silicone Rubber After mixing two liquids of the two-component addition reaction curable silicone rubber composition used in Examples and Comparative Examples, the cured dimensions are 10 ± 4 mm in width (tolerance range 8 mm) and 8 m in length. The silicone rubber was produced by allowing it to stand for 1 day at room temperature and curing so that the thickness would be 1 ± 0.1 mm (tolerance range 0.2 mm). About this silicone rubber, the precision of the width dimension and the thickness dimension was evaluated according to the following criteria.
◎ When the difference between the maximum and minimum values is ¼ or less of the tolerance range ○ When the difference between the maximum and minimum values exceeds ¼ of the tolerance range and is ½ or less △ Maximum and minimum values When the difference between the values exceeds 1/2 of the tolerance range and is less than or equal to the tolerance range × When the difference between the maximum and minimum values exceeds the tolerance range

(2) Elongation of silicone rubber After mixing the two liquids of the two-component addition reaction curable silicone rubber composition used in Examples and Comparative Examples, the mixture was allowed to stand at room temperature for 1 day so that the thickness dimension after curing was 1 mm. A silicone rubber sheet was prepared by curing. A test piece having a dumbbell No. 3 shape was cut out from the silicone rubber sheet. About this test piece, the elongation after an initial state and a temperature / humidity cycle test was measured according to JISK6251.

(3) Adhesive strength of silicone rubber Nylon 66 fabric coated with silicone rubber on one side after mixing two liquids of the two-component addition reaction curable silicone rubber composition used in the examples and comparative examples (in the examples and comparative examples) The same as the coated fabric used) is applied so that the dimension after curing is 20 mm in width and 1 mm in thickness, and then the same coated fabric is polymerized so that the coated surface is on the inside. The silicone rubber composition was cured by allowing to stand for days. A test piece having the shape shown in FIG. 1 (a) was cut out from the bonded coated fabric. As shown in FIG. 1B, the coated fabrics of the test pieces were held at 15 cm intervals with a holding jig of a tensile tester, and the T peel strength was measured at a tensile speed of 200 mm / min.

(4) Airtightness of airbags Nitrogen gas was filled from the gas supply part of the airbags obtained in the examples and comparative examples, and the gas supply was stopped when the internal pressure of the airbag reached 100 KPa. Thereafter, the change over time in the internal pressure of the airbag was measured and evaluated according to the following criteria.
○ When the internal pressure holding time of 20 KPa or more is 6 seconds or more △ When the internal pressure holding time of 20 KPa or more is 5 seconds or more and less than 6 seconds × When the internal pressure holding time of 20 KPa or more is less than 5 seconds or gas supply When the internal pressure of the airbag does not reach 100 KPa sometimes The airtightness was evaluated for the airbag after the initial state and the temperature and humidity cycle test.

(5) Temperature / humidity cycle test 25 cycles of temperature / humidity change defined in JIS D 0208 6.4 (3) were performed.

[Example 1]
A plain woven fabric was woven using nylon 66 yarn having a total fineness of 470 dtex and 72 filaments so that the warp density and the weft density were both 46 / 2.54 cm, then scoured in an alkaline bath and then heat-treated. On one side of this fabric, a solvent-free heat-curing silicone rubber coating material (manufactured by Toray Dow Corning Co., Ltd., main component methyl vinyl silicone rubber) is applied so that the coating amount is 25 g / m ² (weight after drying). Coating with a knife coater and heat treatment gave a coated fabric.
Next, the coated fabric was cut to cut out two panels having the shape shown in FIG. A two-component addition reaction curable silicone rubber composition having the composition shown in Formula 1 is applied to a predetermined position on the silicone rubber-coated surface of one panel with a dispenser so that the dimension after curing is 10 mm in width and 1 mm in thickness. The other panel was overlaid so that the coated surface was on the inside, and after press-bonding with a press, it was allowed to stand at room temperature for 1 day to cure. Subsequently, the airbag of the present invention was obtained by sewing the center portion in the width direction of the joint portion with a 1400 dtex nylon 66 sewing thread using a main sewing machine with a main stitching speed of 3.5 / cm.

Formula 1 (after mixing two liquids)
Main agent (dimethylvinylpolysiloxane) 100 parts by weight Curing agent (dimethylhydrogenpolysiloxane) 143 parts by weight (amount in which the molar ratio of silicon-bonded hydrogen atoms in this component to alkenyl groups in the main component is 0.64)
Catalyst (platinum fine powder) 43 × 10 ⁻⁴ parts by weight Filler (quartz with an average particle size of 10 μm) 128 parts by weight (viscosity 160 Pa · s)

[Example 2]
Formulation 1 contains 57 parts by weight of quartz having an average particle size of 10 μm as filler, 57 parts by weight of calcium carbonate powder having a BET specific surface area of 18 m ² / g, and 14 parts by weight of silica powder having a BET specific surface area of 200 m ² / g. An airbag of the present invention was obtained in the same manner as in Example 1 except that a two-component addition reaction curable silicone rubber composition (viscosity 200 Pa · s) was used.

[Example 3]
Formulation 1 contains 57 parts by weight of quartz having an average particle diameter of 2 μm as filler, 57 parts by weight of calcium carbonate powder having a BET specific surface area of 18 m ² / g, and 14 parts by weight of silica powder having a BET specific surface area of 200 m ² / g. An airbag of the present invention was obtained in the same manner as in Example 1 except that the two-component addition reaction curable silicone rubber composition (viscosity 250 Pa · s) was used.

[Comparative Example 1]
In Formulation 1, the same procedure as in Example 1 was used except that a two-component addition reaction curable silicone rubber composition (viscosity 400 Pa · s) containing 128 parts by weight of quartz having an average particle size of 0.5 μm was used as the filler. I got an airbag.

[Comparative Example 2]
An air bag was prepared in the same manner as in Example 1 except that a two-component addition reaction curable silicone rubber composition (viscosity 120 Pa · s) containing 128 parts by weight of quartz having an average particle size of 30 μm was used as the filler. Got.

[Comparative Example 3]
In Formula 1, a two-component addition reaction curable silicone rubber composition containing 114 parts by weight of calcium carbonate powder having a BET specific surface area of 18 m ² / g and 14 parts by weight of silica powder having a BET specific surface area of 200 m ² / g as fillers ( An airbag was obtained in the same manner as in Example 1 except that the viscosity was 250 Pa · s.

  Table 1 shows the evaluation results of the silicone rubber obtained by curing the two-component addition reaction curable silicone rubber composition used in the examples and comparative examples, and the airbags obtained in the examples and comparative examples.

(A) It is a perspective view which shows the shape of the test piece for evaluating the adhesive force of silicone rubber. (B) It is a perspective view which shows the state which attached the test piece to the tensile testing machine. It is a top view which shows the shape of the panel which comprises an airbag.

Explanation of symbols

1 Test piece 2 Coated fabric 3 Silicone rubber 4 Panel

Claims (1)

  Synthetic fiber fabric coated with silicone rubber on one side is polymerized or folded so that the coated surface is on the inside, and the outer periphery is bonded by joining with a two-component addition reaction curable silicone rubber composition and stitching with yarn A two-component addition reaction curable silicone rubber composition containing a quartz having an average particle diameter in the range of 1 to 25 μm as a filler.

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