Airbag fabric and manufacturing method thereof

Abstract

To provide a base fabric for an airbag, suppressed in combustion property in both resin coated surface ignition and resin non-coated surface ignition of the base fabric for an airbag in a combustion property evaluation defined by FMVSS302 after an environmental resistant test.SOLUTION: A base fabric for an airbag as a polyamide multifilament fabric is such that a silicone membrane layer is provided at least on the one surface of the fabric; an amount of the silicone membrane is 10 g / m2 or more and 100 g / m2 or less; a content of cyclopentanone is 0 ppm or more and 250 ppm or less based on the fabric weight; a larger shrinkage dimensional change rate in shrinkage dimensional change rates in the warp and weft directions before and after heating at 105°C for 60 minutes is 0% or more and 1.4% or less; and a blade combing resistance value after 400 hours under a relative humidity environment of 95% at 85°C is 350 N or more. A production method for the same is also provided.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an airbag fabric used in an airbag related to automobile safety. [Background technology]

[0002] As described in Patent Document 1 below, when a moving vehicle hits a pedestrian, the lower half of the pedestrian's body is swept away by the front of the vehicle, resulting in a secondary collision with the upper surface of the hood at the front of the vehicle. There is also a need for protection against collisions with the highly rigid front pillars on both sides of the windshield glass that rise above the upper surface of the hood. Therefore, as described in the following Patent Document 2, the pedestrian airbag device is folded and stored in a retainer case attached to a support member installed between left and right vehicle body members in the upper rear part of the engine compartment. Furthermore, Patent Document 3 below discloses that airbags, which have conventionally been used to protect passengers in the event of a vehicle collision, can also be used to protect pedestrians.

[0003] These externally deployed airbags must meet the specific durability requirements for external installations in addition to the characteristics required for conventional internally installed driver's and passenger's seat airbags. Specifically, they must be able to withstand outdoor environmental conditions and the working conditions required to maintain vehicle performance, such as light, ultraviolet light, heat, rain, snow, low temperatures, hot water, oil, solvents, detergents, and dust. These environmental factors have a particularly significant impact on the airbag if it is not housed in a sealed, robust container, or if the sealed container is damaged.

[0004] In response to this, for example, Patent Document 4 below discloses that a covering material is applied to the outer surface of the base fabric of the bag body.

[0005] In addition, the following Patent Document 5 describes a coating amount of 20 g / m 2In order to obtain an airbag base fabric that is lightweight and can maintain breathability and flame retardancy before and after heat resistance tests and moisture resistance tests, it is disclosed that the fabric is coated only with a specific water-soluble resin. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 7-108903 [Patent Document 2] Japanese Patent Application Publication No. 2018-172006 [Patent Document 3] Japanese Patent Application Laid-Open No. 2006-205805 [Patent Document 4] Japanese Patent Application Laid-Open No. 2004-115981 [Patent Document 5] Japanese Patent Application Laid-Open No. 2001-214371 Summary of the Invention [Problem to be solved by the invention]

[0007] Due to the diverse conditions under which airbags are used, such as inside and outside the vehicle, it is desirable for the airbag fabric to have excellent flame retardancy regardless of whether it is the front or back side that is used as the outer surface. The flammability evaluation standard (FMVSS 302) requires the sample to be held horizontally and ignited with the surface facing the passenger compartment facing downwards. Therefore, the fabric side (opposite the resin-coated side), which is the outer surface of the airbag fabric, is usually ignited with the resin-coated side facing downwards. When the resin-coated side is used as the outer surface of the airbag fabric, the airbag fabric is ignited with the resin-coated side facing downwards, but igniting the resin-coated side increases the burning rate. Furthermore, airbags that are installed and deployed outside the passenger compartment are desired to be flame-retardant after being exposed to outdoor environmental conditions.

[0008] Patent Document 4 does not fully consider the fire retardancy when the resin-coated surface is used as the outer surface of the airbag base fabric, nor the fire retardancy after exposure to outdoor environmental conditions. Patent Document 5 does not consider the flame retardancy of both the front and back surfaces of the airbag base fabric.

[0009] Therefore, the problem to be solved by the present invention is that in the flammability evaluation defined by FMVSS302 after the environmental resistance test, flammability is suppressed both in the resin-coated surface ignition and the non-coated surface ignition of the airbag base fabric. The problem is to provide an airbag base fabric. [Means for solving the problem]

[0010] The present invention relates to an airbag fabric made of a coated woven fabric, and it has been discovered that this fabric has specific chemical properties and is thermally dimensionally stable, making its combustion characteristics less susceptible to environmental influences. This has led to the creation of the present invention.

[0011] That is, the present invention is as follows. [1] An airbag fabric that is a polyamide multifilament woven fabric, The fabric has a layer of silicone film on at least one side thereof; The amount of silicone film is 10 g / m 2 More than 100g / m 2 is as follows: The content of cyclopentanones is 0 ppm or more and 250 ppm or less based on the weight of the fabric, The larger of the shrinkage dimensional change rates in the warp and weft directions before and after heating at 105°C for 60 minutes is 0% or more and 1.4% or less, and An airbag fabric characterized by having a blade combing resistance of 350 N or more after 400 hours in an environment of 85°C and 95% relative humidity. [2] The airbag fabric according to [1], wherein the amount of oil component contained in the woven fabric is 0% by weight or more and 0.04% by weight or less. [3] The airbag fabric according to [1] or [2], containing phosphorus atoms in an amount of 10 ppm or more and 300 ppm or less relative to the weight of the constituent yarns of the fabric. [4] The airbag fabric according to any one of [1] to [3], wherein the amount of carboxylic acid terminals exceeds the amount of amine terminals at the molecular chain terminals of the polyamide, the difference being 10 millimole equivalents / kg or more and 50 millimole equivalents / kg or less. [5] In a combustion test according to FMVSS302 after 400 hours at 80°C and 95% humidity, the following 1) or 2) was not observed in both the warp and weft directions: 1) It is self-extinguishing regardless of whether the fire is ignited from the front or back of the base fabric. 2) The airbag fabric according to any one of [1] to [4], wherein the burning rates on both the front and back sides of the fabric are 100 mm / min or less, and the ratio of the burning rates on the front and back sides is 1.0 or more and 3.0 or less. [6] The following steps: a step of melt-spinning a polyamide to obtain a polyamide multifilament yarn having a cyclopentanone content of 0 ppm or more and 800 ppm or less; a step of obtaining a woven fabric using the obtained polyamide multifilament yarn as a weaving yarn; A scouring process using alkaline washing liquid at a temperature of 35°C or higher; drying process, Siliconizing at least one surface of the fabric to form a layer of silicone film; and Vulcanization setting process, A method for producing a polyamide multifilament woven airbag fabric, comprising: [7] The method for producing an airbag fabric according to [6], wherein in the scouring step, rinsing with water is performed after the alkaline washing solution or surfactant treatment bath. [8] The method for producing an airbag fabric according to [6] or [7], wherein in the scouring step, the warp tension of the fabric conveyance is 0.08 N / cm or more and 0.8 N / cm or less. [9] The method for producing an airbag fabric according to any one of [6] to [8], wherein in the vulcanization setting step, vulcanization setting processing is carried out at a temperature of 160°C or higher with a warp overfeed of 0.8% or more. [Effects of the Invention]

[0012] The airbag fabric of the present invention has little difference in flammability evaluation between the coated and uncoated surfaces, and further has excellent flame retardancy maintenance after environmental resistance testing. This fabric provides an airbag cushion that is particularly suitable for airbag devices that are installed outside the passenger compartment and are exposed to severe environmental changes. [Brief explanation of the drawings]

[0013] [Figure 1] These are the structural formulas of compounds a) to d). DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, embodiments of the present invention will be described in detail. One embodiment of the present invention is an airbag fabric made of a polyamide multifilament woven fabric, The fabric has a layer of silicone film on at least one side thereof; The amount of silicone film is 10 g / m 2 More than 100g / m 2 is as follows: The content of cyclopentanones is 0 ppm or more and 250 ppm or less based on the weight of the fabric, The larger of the shrinkage dimensional change rates in the warp and weft directions before and after heating at 105°C for 60 minutes is 0% or more and 1.4% or less, and This is an airbag fabric characterized by a blade combing resistance of 350 N or more after 400 hours in an environment of 85°C and 95% relative humidity.

[0015] The constituent yarns of airbag fabrics are long fibers made of polyamide multifilaments. Polyamide fibers have a high melting point and large heat capacity, making them resistant to melting and bursting when an airbag is deployed with explosives. Furthermore, the presence of amide groups and amino or carboxyl groups at the polymer end groups provides excellent adhesion to coatings. Examples of polyamides include fibers made from polyamide 6, polyamide 6·6, polyamide 11, polyamide 12, polyamide 6·10, polyamide 6·12, polyamide 4·6, their copolymers, and mixtures. Among these, polyamide 6·6 fibers made primarily from polyhexamethylene adipamide are preferred. Polyhexamethylene adipamide refers to a polyamide composed of 100% hexamethylenediamine and adipic acid with a melting point above 250°C. The polyamide 6·6 fiber of the present invention may include fibers made of a polymer obtained by copolymerizing or blending polyhexamethylene adipamide with polyamide 6, polyamide 6·I, polyamide 6·10, polyamide 6·T, etc., as long as the melting point is not less than 250°C.

[0016] <Multifilament> The fineness of the constituent yarns of the base fabric is preferably 150 dtex or more and 750 dtex or less. At 150 dtex or more, the mechanical properties are excellent when woven into a fabric for material use. At 750 dtex or less, when weaving at high speeds of 800 rpm or more on a shuttleless loom, the conveying weight is not too heavy to keep up with when inserting the weft yarn, and there are no productivity problems. It is more preferably 220 dtex or more, more preferably 550 dtex or less, and even more preferably 450 dtex or less. In this embodiment, the constituent yarns of the base fabric are multifilaments consisting of single yarn bundles, and the single yarn fineness is preferably 1 dtex or more and 7 dtex or less. If the single yarn fineness is 1 dtex or more, there is little deterioration in mechanical properties during processing from the woven yarn to the base fabric, and if it is 7 dtex or less, microscopic adhesion with the coating film is good, which is preferable for suppressing the burning rate and stabilizing its behavior. Furthermore, the base fabric has good flexibility, and when made into an airbag, it has good storage properties. The cross section of the single yarn may be round or irregular.

[0017] The degree of packing of the base fabric can be expressed by the cover factor, which is the degree of packing within a plane. The cover factor is calculated from the fineness and weave density of the constituent yarns of the base fabric. The cover factor CF is calculated by adding up the warp (w) and weft (f) directions using the fineness d (dtex) of the constituent yarns and the weave density D (threads / 2.54cm). CF=(√(dw)×Dw)+(√(df)×Df) In this embodiment, the cover factor is preferably 1,800 or more and 2,500 or less. A high cover factor of 1,800 or more is preferable because the mechanical properties of the base fabric are good due to the effect of weaving density. A cover factor of 2,000 or more is more preferable. A smaller cover factor of 2,500 or less means less intermixing of the constituent yarns and better flexibility of the base fabric. This is preferable because it provides excellent storability as an airbag. A cover factor of 2,300 or less is more preferable.

[0018] The airbag fabric of this embodiment has a silicone film layer on at least one side of the woven fabric. The silicone film may be a coating film or a laminated film. The amount of silicone film is 10 g / m 2 More than 100g / m 2 The amount of silicone film is 10 g / m or less. 2 If it is equal to or greater than this, it contributes to the airtightness of the airbag and also contributes to the suppression of combustion. 2 The amount of silicone is 100g / m 2 If the amount of the silicone film is less than 70 g / m, the base fabric is lightweight and easy to store. 2 More preferably 40 g / m or less 2 The following is the result.

[0019] The airbag fabric of this embodiment has a cyclopentanone content of 250 ppm or less based on the weight of the constituent yarn. Cyclopentanones refer to the compounds a) Cyclopentanone, b) Cyclopenten-1-one, c) 1,1'-Bicyclopentyl-2-one, and d) Cyclopentanone, 2-cyclopentylidene shown in FIG. 1 , and the cyclopentanone content refers to the total content of these compounds. If the cyclopentanone content is 250 ppm or less, the silicone layer has good adhesion and the increase in burning rate after exposure to a humid and hot environment is small. More preferably, the cyclopentanone content is 150 ppm or less, and most preferably, 50 ppm or less. The lower limit of the cyclopentanone content is preferably 0 ppm or more, and more preferably 10 ppm or more. Cyclopentanones inhibit adhesion between polyamide and silicone, weakening the adhesion, particularly after exposure to a humid and hot environment. Cyclopentanone is derived from polyamide. Polyamide undergoes thermal degradation at its melting point, producing cyclopentanone. Any cyclopentanone that was not completely removed from the polyamide before it was woven into a base fabric remains in the base fabric. The cyclopentanone content can be analyzed by gas chromatography, but since cyclopentanone is partially dimerized during the analysis process, it is quantified as cyclopentanones. The cyclopentanone content varies depending on the cyclopentanone content of the polyamide yarn used for weaving and the processing conditions when it is processed into a base fabric. To keep the content of cyclopentanones in the woven base fabric to 250 ppm or less based on the weight of the constituent yarns, it is preferable to use an alkaline washing solution at a temperature of 35°C or higher in the scouring process after weaving. More preferably, it is used an alkaline washing solution at a temperature of 60°C or higher. Furthermore, the content of cyclopentanones can be reduced by rinsing with neutral water after the alkaline washing solution. Furthermore, the relaxation of the base fabric during this scouring process promotes the penetration of the washing solution between the constituent yarns of the base fabric, thereby reducing the content of cyclopentanones.

[0020] The airbag fabric of this embodiment has a larger shrinkage dimensional change rate of 1.4% or less in the warp and weft directions after 60 minutes at 105°C. The thermal dimensional stability is low at 1.4% or less, and the smaller the value, the smaller the increase in burning rate after exposure to a humid and hot environment. The thermal dimensional stability is more preferably 1.0% or less, and even more preferably 0.8% or less. The thermal dimensional stability of the fabric varies depending on the influence of heat setting in the final stage of fabric processing. Typically, the dimensional change is large in the warp direction and relatively small and stable in the weft direction, at 0.1% or less. The combustion rate of airbag fabrics can be reduced by limiting the supply of combustion gases to the combustion flame. Combustion gases are primarily polyamide decomposition gases. When the fabric is placed with the silicone layer facing upward during horizontal combustion, the flame-retardant silicone layer prevents the gas from migrating to the top surface, thereby reducing the combustion rate. On the other hand, when the fabric is placed with the silicone layer facing downward during horizontal combustion, the combustion gas supply to the combustion flame on the top surface of the fabric is not blocked, resulting in a high combustion rate. In particular, after exposure to a humid and hot environment, the silicone layer's adhesion decreases and dimensional changes (shrinkage) occur, causing the silicone layer to peel and crack. This prevents the silicone layer from blocking the combustion gas, further increasing the combustion rate. Therefore, the low cyclopentanone content and good dimensional stability of the fabric help to suppress the increase in combustion rate after exposure to a humid and hot environment. To achieve a larger shrinkage dimensional change rate of 0 to 1.4% in both the warp and weft directions before and after heating at 105°C for 60 minutes, it is preferable that the overfeed in the warp direction be 0.8% or more at a temperature of 160°C or higher in the vulcanization setting process after silicone application. An overfeed processing of 1.0% or more is more preferable. An overfeed processing of 8.0% or less is preferable because it allows stable processing.

[0021] The airbag fabric of this embodiment preferably has a blade combing resistance of 350 N or more after 400 hours in a humid heat environment (85°C, 95% relative humidity). It is more preferably 420 N or more, and even more preferably 470 N or more. Blade combing resistance is the resistance to slippage of the constituent yarns of the woven fabric, and is a combination of the binding force of the constituent yarns of the woven fabric and the resistance of silicone adhesion. The higher the blade combing resistance, 350 N or more, the better the adhesion of the silicone layer. This high blade combing resistance is one factor in suppressing the burning rate. On the other hand, if the blade combing resistance is 800 N or less, the tear resistance will be sufficiently high.

[0022] In the airbag fabric of this embodiment, the amount of oil agent contained in the woven fabric is preferably 0.04% by weight or less. A lower amount of oil agent, 0.04% by weight or less, indicates a more sufficient deoiling process in the scouring process. The amount of oil agent contained in the woven fabric is more preferably 0.02% by weight or less. A low amount of oil agent results in good adhesion between the polyamide fiber and the silicone layer, and the reduced cyclopentanone content improves adhesion and contributes to avoiding adhesive damage after exposure to a humid and hot environment. The raw weaving yarn contains approximately 1% processing oil, which can be removed by scouring after weaving. On the other hand, the amount of oil agent is preferably 0.005% by weight or more. This results in a sufficiently high tear resistance.

[0023] The airbag fabric of this embodiment preferably has a phosphorus atom content of 10 ppm or more and 300 ppm or less relative to the constituent yarn weight. The higher the phosphorus atom content, the more combustion gas generation is suppressed, resulting in a greater combustion suppression effect. The phosphorus atom content is more preferably 30 ppm or more, and even more preferably 40 ppm or more. On the other hand, since phosphorus atoms may act as a catalyst poison for silicone crosslinking, there is an upper limit to the content. The phosphorus atom content is more preferably 200 ppm or less, and even more preferably 150 ppm or less. The phosphorus atom is derived from a catalyst used in the production of polyamide resin. Examples of the catalyst include phosphoric acid compounds such as phosphoric acid, pyrophosphoric acid, and polyphosphoric acid; phosphinic acid compounds such as dimethylphosphinic acid, phenylmethylphosphinic acid, hypophosphorous acid, sodium hypophosphite, and ethyl hypophosphite; phosphonic acid compounds such as phenylphosphonic acid, sodium phenylphosphonite, and ethyl phenylphosphonite; phosphonic acid compounds such as phenylphosphonic acid, ethylphosphonic acid, sodium phenylphosphonite, diethyl phenylphosphonate, and sodium ethylphosphonite; and phosphorous acid compounds such as phosphorous acid, sodium hydrogen phosphite, sodium phosphite, triethyl phosphite, triphenyl phosphite, and pyrophosphorous acid. The polyamide preferably contains phenylphosphonic acid or a metal salt thereof as a phosphorus component in an amount of 10 ppm to 300 ppm by weight of the polymer. Phenylphosphonic acid and the like are generally used as polymerization catalysts.

[0024] To obtain polyamide 6·6 containing phenylphosphonic acid or its metal salt, either phenylphosphonic acid or its metal salt may be added during solution polymerization, or phenylphosphinic acid or its metal salt may be added, as these will be oxidized to phenylphosphonic acid during the process. Additives may be added during the polymerization process. Examples of additives include antioxidants and heat stabilizers (hindered phenol compounds, hydroquinone compounds, thiazole compounds, phosphorus compounds such as phenylphosphonic acid, imidazole compounds such as 2-mercaptobenzimidazole, and their substituted derivatives, copper halides, copper acetate and halogens, etc.), weathering agents (resorcinols, salicylates, benzotriazoles, benzophenones, hindered amines, etc.), pigments (cadmium sulfide, phthalocyanine, carbon black, etc.), gloss improvers (titanium oxide, calcium carbonate, etc.), dyes (nigrosine, aniline black, etc.), nucleating agents (talc, silica, kaolin, clay, etc.), plasticizers (p-oxyammonium chloride, etc.), and the like. The composition may contain small amounts of: antistatic agents (alkyl sulfate-type anionic antistatic agents, quaternary ammonium salt-type cationic antistatic agents, nonionic antistatic agents such as polyoxyethylene sorbitan monostearate, betaine-type amphoteric antistatic agents, etc.); flame retardants (melamine cyanurate, hydroxides such as magnesium hydroxide and aluminum hydroxide, ammonium polyphosphate, brominated polystyrene, brominated polyphenylene oxide, brominated polycarbonate, brominated epoxy resin, or combinations of these brominated flame retardants with antimony trioxide, etc.); light stabilizers such as manganese acetate; and antifoaming agents.

[0025] In the polymerization of polyamides, in order to suppress the production of cyclopentanones and to ensure that the polymerization reaction proceeds uniformly and in a short time, it is important to increase the degree of polymerization by balancing the concentrations of amino terminal groups and carboxy terminal groups. For fibers with high physical properties, a high degree of polymerization is preferred. High-degree-of-polymerization polyamides preferably have a total amino end group and carboxylic end group content of 150 millimole equivalents / kg polymer or less, more preferably 130 millimole equivalents / kg polymer or less, and even more preferably 110 millimole equivalents / kg polymer or less. For uniform fibers, the total amino end group content is preferably 50 millimole equivalents / kg polymer or more, more preferably 70 millimole equivalents / kg polymer or more, and even more preferably 90 millimole equivalents / kg polymer or more. In this embodiment, the carboxyl end group concentration of the polyamide is in excess of the amino end group concentration, and the difference in end group concentrations is preferably 5 to 80 millimole equivalents / kg polymer, more preferably 10 to 60 millimole equivalents / kg polymer, and even more preferably 20 to 50 millimole equivalents / kg polymer. A high carboxyl end group concentration and a large concentration difference of 5 millimole equivalents / kg polymer or more result in a high hydrogen ion concentration in the polyamide internal environment, suppressing catalytic toxicity of phosphorus compounds, improving adhesion between polyamide and silicone, and improving wet heat resistance of the adhesive. A concentration difference of 80 millimole equivalents / kg polymer or less results in a high degree of polymerization, making it easier to obtain high-strength fibers during drawing. Furthermore, a higher carboxyl end group concentration suppresses the generation of tertiary amines during melting, improving spinning operability and producing woven yarns with good fluff quality.

[0026] Another embodiment of the present invention is a method for producing a method for manufacturing a semiconductor device comprising the steps of: a step of melt-spinning a polyamide to obtain a polyamide multifilament yarn having a cyclopentanone content of 0 ppm or more and 800 ppm or less; a step of obtaining a woven fabric using the obtained polyamide multifilament yarn as a weaving yarn; A scouring process using alkaline washing liquid at a temperature of 35°C or higher; drying process, Siliconizing at least one surface of the fabric to form a layer of silicone film; and Vulcanization setting process, The method for producing a polyamide multifilament woven airbag fabric is characterized by comprising: The content of cyclopentanones in the polyamide resin before melt spinning is preferably 0 ppm or more and 1,000 ppm or less, more preferably 800 ppm or less, and even more preferably 80 ppm or less.

[0027] The polymerization reactor used to produce the resin composition constituting polyamide fibers is useful for two steps: heating at a relatively low temperature and removing moisture under high pressure, and promoting a polycondensation reaction at a high temperature. The reactor may be a single-tank reactor or a two-tank reactor connected in series. The polyamide resin composition is discharged from the polymerization reactor in the form of a strand, cooled, cut, and pelletized, and then dried to remove moisture, yielding pellets suitable for fiber use. In a method for producing a resin composition for polyamide fibers, the polyamide resin composition can be polymerized in the liquid phase, followed by solid-phase polymerization to further increase the degree of polymerization. Solid-phase polymerization performed below the melting point can also suppress thermal degradation of the polymer itself and is preferred because it prevents the increase of cyclopentanones in the polymer. Polyamide resins may contain, for example, antioxidants and heat stabilizers (hindered phenol compounds, hydroquinone compounds, thiazole compounds, phosphorus compounds such as phenylphosphonic acid, imidazole compounds such as 2-mercaptobenzimidazole, and their substitution products, copper halides, iodine compounds, etc.), weathering agents (resorcinols, salicylates, benzotriazoles, benzophenones, hindered amines, etc.), pigments (cadmium sulfide, phthalocyanine, carbon black, etc.), gloss improvers (titanium oxide, calcium carbonate, etc.), dyes (nigrosine, aniline black, etc.), nucleating agents (talc, silica, kaolin, crystals, etc.), and the like. The resin may contain small amounts of additives such as bromine-based flame retardants (e.g., methyl acrylate, octyl p-oxybenzoate, N-butylbenzenesulfonamide), antistatic agents (e.g., alkyl sulfate-type anionic antistatic agents, quaternary ammonium salt-type cationic antistatic agents, nonionic antistatic agents such as polyoxyethylene sorbitan monostearate, betaine-type amphoteric antistatic agents), and flame retardants (e.g., melamine cyanurate, hydroxides such as magnesium hydroxide and aluminum hydroxide, ammonium polyphosphate, brominated polystyrene, brominated polyphenylene oxide, brominated polycarbonate, brominated epoxy resin, or combinations of these brominated flame retardants with antimony trioxide).

[0028] The spinning temperature in melt spinning is preferably 290° C. or higher and 310° C. or lower. Setting the spinning temperature to 310° C. or lower is preferred because thermal decomposition of the polyamide can be suppressed, and the temperature is more preferably 300° C. or lower, and even more preferably 295° C. or lower. On the other hand, a spinning temperature of 290° C. or higher is preferred because the polyamide exhibits sufficient melt fluidity, the discharge amount between the nozzle holes is made uniform, and high-magnification drawing is possible. The shorter the residence time in the melt spinning process (the time from when the polyamide resin is melted until it is discharged from the spinneret), the better. The residence time is preferably 30 minutes or less, more preferably 15 minutes or less, and even more preferably 0.5 to 7 minutes. A short residence time is preferable because cyclopentanones in the polymer increase at the melting temperature. In the melt spinning step, it is preferable to use a single- or twin-screw extruder in the melting section, since this extruder can apply an appropriate pressure to the polyamide resin while guiding it to the polymer piping, gear pump, and spinning pack, preventing abnormal retention in these channels and suppressing an increase in cyclopentanones due to thermal decomposition of the polyamide. Furthermore, it is preferable to filter the polyamide resin using a metal fiber nonwoven fabric filter, sand, or the like before it is discharged from the spinneret, since this stabilizes the spinning operation. The shape of the spinneret holes may be selected depending on the cross-sectional shape of the single fibers constituting the filaments to be produced. The spun yarn from the spinneret is solidified with cooling air, treated with a process oil, taken up, stretched, and heat-treated to obtain the polyamide fiber used in the present invention.

[0029] It is important that the polyamide fiber contains a small amount of cyclopentanones in the polymer by the above-mentioned appropriate manufacturing method. By reducing the amount of cyclopentanones in the polyamide fiber used for weaving, the amount of cyclopentanones in the airbag fabric can be reduced. The amount of cyclopentanones in the polyamide fiber is preferably 800 ppm or less, more preferably 600 ppm or less, even more preferably 400 ppm or less, and particularly preferably 80 ppm or less. The polyamide fiber filaments preferably have a strength of 7 cN / dtex. A strength of 7 cN / dtex or more is preferred because fuzzing is less likely to occur even when the weaving tension is increased in the weaving process, and a high-density woven fabric can be obtained with good passability through the manufacturing process; a strength of 7 cN / dtex or more is more preferred, 8 cN / dtex or more is even more preferred, 9.0 cN / dtex or more is even more preferred, and 9.5 cN / dtex or more is most preferred. The tensile strength of the polyamide fiber filaments is substantially 10.5 cN / dtex or less, taking into consideration other properties and production costs, etc. The oil deposition rate of the polyamide fiber is preferably 0.6 to 1.5 wt%. If the oil deposition rate is 1.5 wt% or less, the weft yarn hardly has difficulty in flying due to stickiness (tackiness), and the weft yarn transport medium, air or water, does not lose its weft transport force due to a reduction in apparent cross-sectional area caused by the single yarn bundling being too good compared to the single yarn bundling due to entanglement, resulting in good weaving stability. On the other hand, if the oil deposition rate is 0.6 wt% or more, the weft yarn is supplied smoothly due to the appropriate friction reduction effect, resulting in excellent productivity without weaving stoppages.

[0030] In weaving, a water jet loom, an air jet loom, a rapier loom, or the like can be used as a loom. Airbag base fabrics are high-density woven fabrics, and it is preferable to increase the warp tension in the warping and weaving processes to ensure good processability. High-density woven fabrics are formed by setting the warp tension high in weaving and creating effective beating conditions. In particular, a bent shape in which the warp yarns are sufficiently intertwined is created, resulting in a large warp crimp.

[0031] The fabric woven in this manner can be subjected to a scouring process to wash out the process oil from the polyamide fibers, and at the same time, the content of cyclopentanones in the fibers can be reduced. The scouring process can be performed using hot water or hot compressed water, and the treatment process can be a single-stage or multi-stage process consisting of two or more stages. It is also preferable to perform scouring using a conventionally known scouring agent. A combination of a nonionic surfactant and soda ash or a combination of a higher alcohol sulfate and soda ash is used. In particular, scouring with an alkaline agent such as soda ash is effective in removing process oils from the fiber surface and reducing the amount of cyclopentanone in the fiber. The temperature in the scouring process is preferably 35°C or higher, and more preferably in the range of 60°C to 98°C. The higher the temperature in the scouring process, the more the cyclopentanones content in the fiber can be reduced. In the scouring process, it is preferable to perform a water washing treatment (water rinsing) after scouring with a scouring agent. In order to increase the hydrogen ion concentration inside the polyamide fiber, it is preferable to perform the water washing process in multiple stages or to extend the residence time. By increasing the hydrogen ion concentration inside the polyamide fiber, the catalytic toxicity of the silicone addition reaction of phosphorus compounds can be suppressed, and the inhibition of adhesion between silicone and textile can be avoided. The scouring step may be carried out continuously after the weaving step, or may be carried out as a separate step after weaving. Either a batch method or a continuous method can be employed, but continuous treatment while feeding and discharging the base fabric to and from the treatment zone is preferred for superior productivity. The scouring process can facilitate the removal of cyclopentanone by loosening the fabric. Regarding gripping of the fabric in the scouring bath, it is preferable to convey the fabric without gripping it in the width direction, and in the warp direction, the conveying tension is preferably 0.8 N / cm or less, more preferably 0.5 N / cm or less. In order to prevent the fabric from sagging and wrinkles from occurring during transport, it is preferable to set the warp tension to 0.08 N / cm or more. During transport, tension load can be controlled by providing a dancer roll or the like to control tension. During the scouring process, the fabric shrinks depending on the bath temperature and the thermal shrinkage characteristics of the constituent fibers. However, controlling the warp tension to a low level while shrinkage occurs, allowing the fabric to shrink in the width direction, and loosening the fabric structure contributes to the removal of cyclopentanone.

[0032] The woven fabric is preferably heat-set in a heat-setting process. The heat-setting temperature is preferably 110°C or higher and 160°C or lower, more preferably 130°C or higher and 150°C or lower, and the heat-setting time may be appropriately selected from the range of 0.1 minutes to 30 minutes. In the heat-setting process, the woven fabric is preferably dried under tension so that the shrinkage force of the fabric is maintained at a predetermined force. Heat-setting the woven fabric stabilizes the processability of the subsequent resin application process.

[0033] The woven fabric after the scouring step may be subjected to a drying treatment as needed before the heat setting step. The drying temperature is preferably in the range of 80°C to 130°C, more preferably 100°C to 120°C. The treatment time is preferably selected appropriately from 0.1 minutes to 30 minutes. Drying may be performed with the woven fabric in a relaxed or tensioned state.

[0034] The airbag fabric of this embodiment is coated with silicone and then subjected to a finish heat setting process to form an airbag coat fabric. The silicone to be applied is preferably one that is excellent in flame retardancy, heat resistance, air barrier properties, etc. The silicone is preferably an addition reaction type curable silicone rubber that can be applied without a solvent. The main component of silicone is alkenylorganopolysiloxane, which is the base polymer of the coating agent and contains at least two alkenyl groups bonded to silicon atoms. Generally, a substantially linear organopolysiloxane is preferred. Specifically, a linear diorganopolysiloxane whose molecular chain is primarily composed of repeating diorganosiloxane units and whose molecular chain ends are capped with triorganosiloxy groups is preferred. Furthermore, the position of the alkenyl group bonded to the silicon atom in the main chain is not particularly limited. The alkenyl group may be bonded to either a silicon atom at the molecular chain end or a silicon atom at a non-terminal portion of the molecular chain, or to both. Examples of side-chain organo groups include unsubstituted or substituted monovalent hydrocarbon groups having 1 to 10 carbon atoms and no aliphatic unsaturated bonds. Among these, methyl groups, phenyl groups, or a combination of these groups are preferred. Examples of alkenyl groups include alkenyl groups having 2 to 8 carbon atoms. Examples include vinyl groups, allyl groups, 1-propenyl groups, isopropenyl groups, 1-butenyl groups, isobutenyl groups, and hexenyl groups. Of these, vinyl groups are preferred.

[0035] The organosilicon compound used as the crosslinking component of silicone is at least one selected from the group consisting of organohydrogensilanes containing at least two silicon-bonded hydrogen atoms, linear or branched organohydrogenpolysiloxanes containing at least two (particularly, two or three) diorganohydrogensilyl groups (i.e., hydrogen atoms bonded to silicon atoms at the molecular chain terminals), and hydrocarbon compounds containing at least two (particularly, two or three) diorganohydrogensilyl groups. Examples of the organic groups bonded to the silicon atoms include alkyl groups such as methyl, ethyl, propyl, butyl, pentyl, and hexyl; aryl groups such as phenyl, tolyl, and xylyl; and halogenated alkyl groups such as 3-chloropropyl and 3,3,3-trifluoropropyl. Examples of the diorganohydrogensilyl groups include dimethylhydrogensilyl groups. Specific examples include methylsilane ((CH3)SiH3), dimethylsilane ((CH3)2SiH2), ethylsilane ((C2H5)SiH3), diethylsilane ((C2H5)2SiH2), and hexylsilane ((C6H 13 )SiH3), dihexylsilane ((C6H 13 )2SiH2), n-octylsilane ((n-C8H 17 )SiH3), di(n-octyl)silane ((n-C8H 17 )2SiH2), phenylsilane ((C6H5)SiH3), diphenylsilane ((C6H5)2SiH2), tris(dimethylhydrogensiloxy)methylsilane, tris(dimethylhydrogensiloxy)phenylsilane, tris(dimethylhydrogensilylethyl)methylsilane, tris(dimethylhydrogensilylethyl)phenylsilane, and 1,4-bis(dimethylhydrogensilyl)benzene.

[0036] The content of the crosslinking component is an amount such that the molar ratio of silicon-bonded hydrogen atoms in this component to alkenyl groups in the entire coating agent is in the range of 0.01 to 5.0, preferably in the range of 0.1 to 2.0, and particularly preferably in the range of 0.1 to 1.0. In this case, the proportion of alkenyl groups in component (A) to the alkenyl groups present in the entire coating agent is preferably 90 to 100 mol%, more preferably 95 to 100 mol%. The silicone reaction catalyst component is a platinum group metal catalyst, and those known as hydrosilylation reaction catalysts can be used. Examples include platinum group metals such as platinum (including platinum black), rhodium, and palladium; platinum chlorides, chloroplatinic acid, and chloroplatinic salts such as HPtCl.nH0, HPtCl.nH0, NaHPtCl.nH0, KHPtCl.nH0, NaPtCl.nH0, KPtCl.nH0, PtCl.nH0, PtCl, and NaHPtCl.nH0 (wherein n is an integer of 0 to 6, preferably 0 or 6); Examples of suitable catalysts include alcohol-modified chloroplatinic acid, complexes of chloroplatinic acid and olefins, platinum black, platinum group metals such as palladium supported on supports such as alumina, silica, and carbon, complexes of platinum and triphenylphosphine, rhodium-olefin complexes, chlorotris(triphenylphosphine)rhodium (Wilkinson's catalyst), complexes of platinum chloride, chloroplatinic acid, or chloroplatinate with vinyl group-containing siloxanes, particularly vinyl group-containing cyclic siloxanes. Among these, platinum-based catalysts such as complexes with vinyl group-containing cyclic siloxanes and complexes of platinum and triphenylphosphine are particularly preferred. In addition to the above, silicone may contain other components. For example, inorganic fillers for improving the properties of the cured resin include finely powdered silica for reinforcing resin strength and calcium carbonate powder for enhancing resin toughness; curing reaction inhibitors include acetylene compounds such as 3,5-dimethyl-1-hexyn-3-ol and enyne compounds such as 3,5-dimethyl-3-hexen-1-yne; and adhesion improvers include silane coupling agents such as methyltrimethoxysilane.

[0037] The amount of silicone applied to the airbag fabric is 10g / m 2 More than 100g / m 2 or less, more preferably 15 g / m 2 More than 70g / m 2 More preferably, it is 20 g / m or less. 2 More than 40g / m 2 Less than or equal to 10g / m 2 The required airtightness can be obtained with an application amount of 100g / m or more. 2 At the following application amounts, the coated fabric is flexible, easy to store, and the overall weight of the bag is reduced. Methods for coating the surface of a woven fabric with silicone include immersing the fabric in a resin solution bath and then removing excess resin by mangling, vacuuming, or even using a coating knife, bar coating using a comma coater, or spraying the resin using a spray or forming device. Of these, knife coating of solvent-free silicone is preferred from the perspective of applying a small amount of resin evenly. In particular, when coating by air knife coating, it is preferable to apply the coating with a contact pressure between the knife and the fabric in the range of 15 N / cm to 15 N / cm and a fabric tension in the range of 100 N / cm to 3000 N / cm. By applying a high contact pressure to the knife, it is possible to thin the coating film and control the amount of coating evenly and lightly. The fabric tension during the coating process stretches the fabric in the warp direction and accumulates thermal strain.

[0038] After silicone coating, a vulcanization setting process (finish heat setting process) is carried out to vulcanize and crosslink the silicone and to finally heat set the base fabric. Here, it is important to stabilize the warp strain caused by the warp tension during the coating process. For this reason, it is preferable to perform the setting process with an overfeed of 0.8% or more in the feed direction of the fabric, i.e., the warp direction, and more preferably an overfeed process of 1.0% to 3.0%. The amount of overfeed can be determined depending on the shrinkage rate of the weaving yarn and the heat treatment conditions of each process. By using overfeed, warp strain is eliminated, making it possible to improve the thermal dimensional stability of the base fabric. The temperature for the final heat setting process is selected to promote silicone vulcanization and improve the dimensional stability of the nylon fabric. The final heat setting temperature is preferably 160°C or higher and 210°C or lower, and more preferably 170°C or higher and 200°C or lower. In the final heat setting process, an overfeed of 0.8% to 3.0% in the warp direction and a temperature of 160°C to 210°C are preferable for improving the thermal dimensional stability of the base fabric.

[0039] In the airbag fabric of this embodiment, in a combustion test according to FMVSS302 after 400 hours at 80°C and 95% humidity, it is preferable that the fabric is self-extinguishing in both the warp and weft directions, regardless of whether it is ignited from the front or back of the fabric, or that the burning rate is 100 mm / min or less. In other words, in a combustion test according to FMVSS302 after 400 hours at 80°C and 95% humidity, it is preferable that the airbag fabric is self-extinguishing in both the warp and weft directions, regardless of whether it is ignited from the front or back of the fabric, regardless of whether it is ignited from the front or back of the fabric, or that the test piece does not ignite within the specified time or the flame is extinguished just before the A-marked line, i.e., it is judged to be self-extinguishing, or that the burning rate is 100 mm / min or less. Furthermore, it is preferable that the airbag fabric of this embodiment does not increase in flammability by moist heat treatment. That is, the airbag fabric is preferably maintained in an 80°C, 95% RH environment for 400 hours, and the increase in combustion rate after moist heat treatment is preferably 40% or less, more preferably 30% or less, and even more preferably 20% or less, relative to the combustion rate before the moist heat treatment. The silicone's excellent adhesion to nylon fabric, coupled with its thermal dimensional stability, suppresses the increase in burning rate due to moist heat treatment, allowing the airbag to maintain its flame retardancy even when installed in a vehicle under harsh conditions.

[0040] In the airbag fabric of this embodiment, the ratio of the burn rate of the coated surface (ignition with the coated surface facing down) to the burn rate of the woven surface (ignition with the coated surface facing up) after moist heat treatment is 3.0 or less, more preferably 2.5 or less, in the FMVSS 302 combustion test. The lower limit of the burn rate ratio is preferably 1.0 or more. Because the silicone adheres well to the polyamide fiber woven fabric and is thermally dimensionally stable, the difference in burn rate between the front and back of the coating does not increase under environmental conditions. In other words, flame retardancy can be maintained even in the case of an airbag cushion with the coated surface exposed in an airbag installed in a vehicle under harsh environments. As described above, the airbag fabric of this embodiment preferably has a blade combing resistance of 350 N or more after 400 hours in a humid heat environment (85°C, 95% relative humidity). It is more preferably 420 N or more, and even more preferably 470 N or more. Blade combing resistance is the resistance to slippage of the constituent yarns of the woven fabric, and is a combination of the binding force of the constituent yarns of the woven fabric and the resistance of silicone adhesion. The higher the blade combing resistance, 350 N or more, the better the adhesion of the silicone layer. This high blade combing resistance is one factor in suppressing the burning rate. On the other hand, if the blade combing resistance is 800 N or less, the tear resistance will be sufficiently high. [Example]

[0041] The present invention will be described in more detail below with reference to examples. Various evaluations in the examples were carried out according to the following methods.

[0042] (1) Amount of silicone applied to the base fabric A sample of 0.3 m square area (A) is taken from the base fabric, degreased with dichloromethane, and dried at 105°C. This is dissolved in 200 g of 90% formic acid at room temperature, and the insoluble matter is filtered out using a glass sintered filter (VIDTEC Glass Filter 17G-3, manufactured by Cosmospeed Co., Ltd.). The insoluble matter is thoroughly washed with formic acid and water, dried at 105°C, and the mass is precisely weighed (M). The coating weight (g / m 2 ) was obtained by dividing the formic acid insoluble matter (M) by the area (A) of the fabric sample.

[0043] (2) Determination of cyclopentanones in polyamide resin, fiber, and fabric before melt spinning The polyamide resin, polyamide fiber, or base fabric was cut into pieces and prepared under standard conditions (20°C, relative humidity 65%, left for 24 hours or more). Analysis was performed using HS-SPME-GC / MS. Approximately 10 mg of sample was accurately weighed and placed in a headspace vial. An SPME fiber assembly was attached. The SPME fiber assembly consisted of a PDMS fiber coated with polydimethylsiloxane. The vial containing the sample was heated to 180°C for 5 minutes in a block heater, then removed and allowed to cool at room temperature for 5 minutes. The SPME was then removed and analyzed by GC / MS. Quantitative analysis was performed using a cyclopentanone standard. The cyclopentanone content was determined by adding up a) cyclopentanone, b) cyclopenten-1-one, c) 1,1'-bicyclopentyl-2-one, and d) cyclopentanone and 2-cyclopentylidene. When polyamide fiber was used as the sample, the cyclopentanone content (ppm) in the precisely weighed sample was determined. When the sample was a base fabric, the weight of the precisely weighed base fabric was converted into the weight of the fabric by subtracting the amount of silicone applied, and the cyclopentanone content (ppm) in the constituent fabric was determined. The GC / MS was manufactured by Agilent, with GC: 7890B and MS: 5977B. The conditions were as follows: Column: DB-1MS (30 m x 0.25 mm, film thickness 0.25 μm) Column temperature: 40°C (3 min) → 20°C / min → 300°C Column flow rate: 1.0 ml / min Column flow rate: 1.0 mL / min Injection method: Splitless Injection temperature: 250℃ Interface temperature: 280℃ Ion source temperature: 230℃ Ion source: EI method Scan range: 50-500 m / z

[0044] (3) End group quantity of the constituent yarn of the base fabric (base fabric 20cm square) The constituent yarns were peeled off from the base fabric and 5 to 10 g samples were collected. (3a) Amino end group concentration The constituent yarns were peeled off from the base fabric to obtain a sample fiber sample, which was then precisely weighed and dissolved in a 90% aqueous phenol solution. After complete dissolution, the solution was titrated with a 0.05N aqueous hydrochloric acid solution until the pH reached 3. The amino end group concentration per kg of polymer was calculated from the titration amount. (3b) Carboxyl end group concentration As described above, the constituent yarn sample was precisely weighed and dissolved in benzyl alcohol at 170°C. After complete dissolution, phenolphthalein indicator was added. Then, colorimetric titration was performed with 0.1N NaOH ethylene glycol solution. The carboxyl end group concentration per 1 kg of polymer was calculated from the titration amount. The difference in terminal groups of the constituent fabrics was determined by subtracting the amino terminal group concentration from the carboxyl terminal group concentration, and the sum of the carboxyl terminal group concentration and the amino terminal group concentration was determined as the total of the terminal groups of the constituent fabrics.

[0045] (4) Determination of phosphorus content in base fabric The constituent yarn was peeled off from the base fabric to obtain a sample of approximately 0.5 g. The content of phosphorus atoms derived from phosphate groups in the constituent yarns was determined by inductively coupled plasma atomic emission spectroscopy (ICP-AES) using the following equipment and conditions. (Measurement conditions) ICP-AES device: Thermo Fisher Scientific, iCAP6300Duo High frequency output: 1150W Plasma gas: 12L / min Auxiliary gas: 0.5L / min Nebulizer gas: 0.5L / min Photometry: Axial direction Measurement wavelength: 213nm Pretreatment method: The sample was wet decomposed with sulfuric acid, nitric acid, and hydrochloric acid to prepare the test solution.

[0046] (5) Amount of oil component in base fabric Measurement was performed using Soxhlet extraction in accordance with JISL1095(2010)9.30. Cyclohexane was used as the solvent. The moisture content of the base fabric sample was measured using the Karl Fischer titration method based on moisture evaporation in accordance with JISK0068(2001), and the bone-dry weight was calculated from the precisely weighed weight of the base fabric sample. The weight of the fabric was then converted to the weight of the component fabric by subtracting the amount of silicone applied from the weight of the base fabric. The amount of oil component in the component fabric (wt%) was calculated from the amount of oil component extracted using the Soxhlet and the sample weight of the component fabric. To ensure accurate weighing of the extracted dried product, a new base fabric sample was replaced and additional extraction was repeated if necessary.

[0047] (6) Shrinkage dimensional change rate of base fabric A base fabric is exposed to an environment with a temperature of 20°C and a relative humidity of 65% for at least 24 hours, and a 150mm square piece is taken along the warp and weft directions of the base fabric as a sample. 100mm gauge lines are drawn precisely on the taken piece in both the warp and weft directions. The sample piece is placed in a hot air oven at 105°C without tension for 60 minutes. After removing it and exposing it to an environment with a temperature of 20°C and a relative humidity of 65% for at least 24 hours, the gauge distance is measured in both the warp and weft directions. The shrinkage change rate (%) of the gauge distance relative to the original 100mm is calculated. This is repeated three times and the average is calculated. The value in the warp and weft directions that shows the largest shrinkage change rate is used as the shrinkage dimensional change rate.

[0048] (7) Burning rate of the base fabric, increase in burning rate after moist heat treatment, and burning rate ratio between the front and back (C / W ratio) FMVSS302 combustion test was conducted. The base fabric was held in a standard state for 400 hours at 80°C and 95% relative humidity, and then returned to a standard state for 400 hours. The fabric was fixed to a U-shaped frame and placed horizontally with the coated side facing down. The specimen was ignited with a burner flame from the edge and the burning rate was evaluated. Tests were conducted in both warp and weft directions, and the increase in burning rate (%) before and after the moist heat treatment was evaluated. Furthermore, for base fabric samples that had been kept in an environment of 80°C and 95% relative humidity for 400 hours and then returned to standard conditions, the samples were fixed to a U-shaped frame and placed horizontally. The burning rates were evaluated for both cases: when the coated side was placed facing down and ignited with a burner flame from the edge of the sample, and when the woven side was placed facing down and ignited with a burner flame from the edge of the sample. The ratio of the burning rate with the coated side facing down (C rating) to the burning rate with the woven side facing down (W rating) was evaluated and is shown in the table below as the burning rate ratio (C / W ratio) of the front and back after moist heat treatment.

[0049] (8) Increased breathability of the base fabric after wet heat treatment The air permeability (mm / s) was measured at a pressure of 50 kPa using a "High-Pressure Air Permeability Meter" manufactured by Cosmo Instruments Co., Ltd. The base fabric samples were evaluated by comparing a standard sample with a sample that had been kept in an environment of 80°C and 95% relative humidity for 400 hours and then brought to a standard state, and the increase in air permeability (mm / s) after the moist heat treatment was determined.

[0050] (9) Combing resistance of the base fabric after wet heat treatment After storing the base fabric in an environment of 80°C and 95% relative humidity for 400 hours, the blade combing resistance of the base fabric was measured for five samples in each warp and weft directions in accordance with ASTM-D6479(2015), and the values ​​were averaged. The base fabric samples were kept in an environment of 80°C and 95% relative humidity for 400 hours and then returned to standard conditions.

[0051] (10) Scrub evaluation of base fabric Coating adhesion was confirmed by a rubbing test. The test equipment was a scrub tester, and the test was conducted in accordance with ISO 5981. The test was conducted on a base fabric in a standard state and a base fabric that had been kept in an environment of 80°C and 95% relative humidity for 400 hours and then returned to a standard state. Observations were made every 50 rubs out of 200 rubs or more, and the number of rubs at which peeling was observed was evaluated.

[0052] [Example 1] An unend-capped polyamide 6·6 polymer was polymerized using phenylphosphonic acid as a polymerization catalyst and copper iodide and potassium iodide as thermal stabilizers, and then chipped and further solid-state polymerized. Polymer chips were melted at 300°C and extruded using a melt spinning method with a residence time of 180 seconds at 290°C. The extrusion was then applied with an aliphatic synthetic ester spinning oil and stretched to obtain polyamide 6·6 fiber filaments with a 470 dtex and 136 dtex. The fiber contained 140 ppm phosphorus, 60 ppm copper, and 1800 ppm iodine. The difference between the carboxyl end group concentration and the amino end group concentration was 50 mmol equivalents / kg polymer. The fiber contained 500 ppm cyclopentanones. The boiling water shrinkage according to JIS L1017(2002)8.14 was 7.5%. This fiber was warped without twist or sizing, and then woven into a plain weave on a water jet loom using the same yarn as the weft. The fabric was scoured using an open soaper-type scourer. After immersion for 1 minute in an 80°C hot water bath containing 0.5 g / L of sodium alkylbenzene sulfonate and 0.5 g / L of soda ash, it was immersed in three layers of neutral 80°C hot water baths, one for 1 minute each. To ensure stable transport of the fabric during scouring, the warp tension was controlled at 0.22 N / cm using a dancer roll. The fabric was then dried for 3 minutes with hot air at 110°C. Furthermore, a solvent-free addition silicone resin was applied to the coating layer at 20 g / m using the air knife coating method. 2 The tension of the base fabric in the warp direction was set to 580 N / m, and the knife blade thickness was selected to achieve the desired coating amount. Subsequently, the fabric was heat-treated at 190°C for 2 minutes using a pin tenter heat treatment machine with a warp overfeed shrinkage of 2.0% and a tenter extension of 0%, to obtain a coated fabric for airbags. The cover factor was 2145 based on the weave density and the constituent yarn fineness. The physical properties of the obtained base fabric are shown in Table 1 below. Dimensional stability was measured in the warp direction because the rate of change was large in this direction. The increase in burning rate due to moist heat treatment was suppressed. Furthermore, although the burning rate with the coated side facing down was higher than that with the woven side facing down, this level remained even after moist heat treatment.

[0053] [Examples 2 to 4] An airbag base fabric was obtained in the same manner as in Example 1, except that when the woven fabric was scoured in an open soap type scourer, the temperature of the hot water bath was set to the temperature shown in Table 1 below.

[0054] [Comparative Example 1] When the woven fabric was refined in an open soap type scouring machine, it was immersed in three layers of neutral 80 ° C. hot water baths successively for 1 minute each, and then dried at 110 ° C. for 3 minutes. An airbag base fabric was obtained in the same manner as in Example 1. The increase in burning rate due to moist heat treatment is significant. Furthermore, the burning rate with the coated side facing down is higher than the burning rate with the woven side facing down, and the difference is large after moist heat treatment.

[0055] [Examples 5 to 7, Comparative Example 2] In the vulcanization setting process using a pin tenter heat treatment machine after knife coating, an airbag base fabric was obtained in the same manner as in Example 1 except that the warp overfeed shrinkage was set to the value shown in Table 1 or 2 below. The increase in burning rate due to the moist heat treatment was large in Comparative Example 2. Furthermore, the burning rate with the coated side facing down was higher than the burning rate with the woven side facing down, and the difference was large after the moist heat treatment.

[0056] [Example 8] An airbag base fabric was obtained in the same manner as in Example 1, except that when the gray fabric was scoured in an open soap type scourer, it was immersed and retained for 1 minute in a 60°C hot water bath containing 0.5 g / L of sodium alkylbenzene sulfonate and 0.5 g / L of soda ash, and then immersed in three layers of neutral 60°C hot water baths, one for 1 minute each, and then dried at 110°C for 3 minutes. After knife coating, a pin tenter heat treatment machine was used to obtain a coated airbag fabric, with a warp overfeed shrinkage of 1.5% and a tenter extension of 0%, and the fabric was treated at 190 ° C. for 2 minutes. An airbag fabric was obtained in the same manner as in Example 1.

[0057] Comparative Example 3 An airbag fabric was obtained in the same manner as in Example 8, except that in the vulcanization setting process using a pin tenter heat treatment machine after knife coating, the warp overfeed shrinkage was set to 0.5%. The combustion rate is often increased by moist heat treatment.

[0058] Comparative Example 4 When the greige fabric was scoured using an open soap scourer, it was immersed in a 30°C warm water bath containing 0.5g / L of sodium alkylbenzene sulfonate and 0.5g / L of soda ash for 1 minute, then immersed in a neutral 30°C warm water bath for 1 minute, and then dried at 110°C for 3 minutes. Furthermore, in the vulcanization setting process using a pin tenter heat treatment machine after knife coating, the warp overfeed shrinkage was set to 1.0%. An airbag base fabric was obtained in the same manner as in Example 1, except for these factors.

[0059] [Example 9] Polyamide 6·6 polymer was polymerized without end-capping using hypophosphorous acid as a polymerization catalyst and copper iodide and potassium iodide as thermal stabilizers, and then chipped and further solid-state polymerized. The polymer chips were extruded, coated with an aliphatic synthetic ester spinning oil, and then drawn to obtain 470 dtex 136 polyamide 6·6 fiber filaments. This fiber contained 10 ppm phosphorus, 60 ppm copper, and 1800 ppm iodine. The difference between the carboxyl end group concentration and the amino end group concentration was 50 millimole equivalents / kg polymer. The cyclopentanones content in the fiber was 400 ppm. This fiber was used to obtain an airbag fabric in the same manner as in Example 1. The increase in burning rate due to moist heat treatment was suppressed. Furthermore, the burning rate with the coated side facing down was higher than the burning rate with the woven side facing down, but this level remained even after moist heat treatment.

[0060] Comparative Example 5 When scouring the green fabric in an open soap type scouring machine, no alkaline cleaning solution was used, and the fabric was immersed in three layers of neutral 80 ° C. hot water baths successively for 1 minute each, and then dried at 110 ° C. for 3 minutes. An airbag base fabric was obtained in the same manner as in Example 10. The increase in combustion rate due to moist heat treatment is significant.

[0061] [Example 10] In Example 9, when polymerizing polyamide 6·6 polymer, hexamethylenediamine was added to the equimolar monomer salt to reduce the difference between the carboxyl and amino end group concentrations. Polymer chips were extruded, coated with an aliphatic synthetic ester spinning oil, and then drawn to obtain 470 dtex 136 polyamide 6·6 fiber filaments. This fiber contained 10 ppm phosphorus, 60 ppm copper, and 1800 ppm iodine. The difference between the carboxyl and amino end group concentrations was 5 mmol equivalents / kg polymer. The cyclopentanones in the fiber were 400 ppm. This fiber was used to produce an airbag fabric in the same manner as in Example 1.

[0062] [Example 11] An airbag fabric was obtained in the same manner as in Example 1, except that when the woven fabric was refined in an open soaper type scouring machine, the tension of the woven fabric transport was set to 1.5 N / cm.

[0063] [Example 12] An airbag base fabric was obtained in the same manner as in Example 1, except that when the woven fabric was scoured in an open soap type scourer, it was immersed and retained for 1 minute in an 80°C hot water bath containing 0.5 g / L of sodium alkylbenzene sulfonate and 0.5 g / L of soda ash, and then continued to the hot air drying process without being immersed in the neutral 80°C hot water bath.

[0064] The conditions, physical property results, etc. of Examples 1 to 12 and Comparative Examples 1 to 5 are shown in Tables 1 and 2 below. [Table 1]

[0065] [Table 2] [Industrial Applicability]

[0066] The airbag fabric of the present invention has stabilized flame retardancy under environmental conditions, and the difference in flame retardancy between the front and back surfaces of the coated fabric is maintained small. This allows the fabric to be used as an airbag cushion without distinguishing between the front and back surfaces. It also enables airbag cushion designs in which the coated surface is exposed and the inner surface of the airbag cushion is protected from environmental conditions by covering it with a coating film. Because the flame retardancy is stabilized under more severe environmental conditions, the fabric can also be used suitably for airbags installed outside the passenger compartment.

Claims

1. An airbag fabric that is a polyamide multifilament woven fabric, The fabric has a layer of silicone film on at least one side thereof; The amount of the silicone film is 10 g / m ２ More than 100g / m ２ is as follows: the content of cyclopentanones is 0 ppm or more and 250 ppm or less based on the weight of the fabric, The larger of the shrinkage dimensional change rates in the warp and weft directions before and after heating at 105°C for 60 minutes is 0% or more and 1.4% or less, and An airbag base fabric characterized in that the increase in burning rate of the base fabric when kept in a standard state after being kept in an 85°C, 95% relative humidity environment for 400 hours is 40% or less.

2. The airbag fabric according to claim 1, wherein the amount of oil component contained in the woven fabric is 0% by weight or more and 0.04% by weight or less.

3. The airbag fabric according to claim 1 or 2, containing phosphorus atoms in an amount of 10 ppm to 300 ppm based on the weight of the constituent yarns of the fabric.

4. At the molecular chain terminals of the polyamide, the amount of carboxylic acid terminals exceeds the amount of amine terminals, and the difference is 10 millimole equivalents / kg or more and 50 millimole equivalents / kg or less. Airbag fabric according to any one of claims 1 to 3.

5. In a combustion test of FMVSS302 after 400 hours under an 80°C, 95% humidity environment, the following 1) or 2): 1) It is self-extinguishing regardless of whether the fire is ignited from the front or back of the base fabric. 2) The burning speeds on both sides are 100 mm / min or less, and the ratio of the burning speeds on both sides is 1.0 or more and 3.0 or less. The airbag fabric according to any one of claims 1 to 4, which satisfies the above.

6. An airbag base fabric described in any one of claims 1 to 5, having a blade combing resistance of 350 N or more after 400 hours in an environment of 85°C and 95% relative humidity.

7. An airbag cushion comprising an airbag base fabric according to any one of claims 1 to 6.

8. An airbag comprising an airbag base fabric according to any one of claims 1 to 6.

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