Airbag base fabric and manufacturing method thereof

Abstract

Provided is an airbag base fabric whose flammability is suppressed under both conditions of ignition on the resin-coated surface and ignition on the uncoated surface in a flammability evaluation specified in FMVSS 302 after an environmental resistance test. The present invention relates to an airbag base fabric and a method for producing the same. The airbag base fabric is a polyamide multifilament fabric characterized in that at least one surface of the fabric has a layer of an organic silicone film, the amount of the organic silicone film being 10 g / m 2 Above and 100g / m 2 The content of cyclopentanones is greater than 0 ppm and less than 250 ppm relative to the weight of the fabric, the larger shrinkage dimensional change rate of the airbag base fabric in the warp and weft directions before and after heating at 105°C for 60 minutes is greater than 0% and less than 1.4%, and the blade combing resistance after 400 hours in an environment of 85°C and 95% relative humidity is greater than 350N.

Description

Technical Field

[0001] The present invention relates to a base fabric for an airbag used for an airbag related to automobile safety. Background Art

[0002] As described in Patent Document 1 below, it is known that when a moving vehicle collides with a pedestrian, the lower body of the pedestrian is swept by the front of the vehicle body and causes a secondary collision with the upper surface of the hood at the front of the vehicle body. In addition, protection is also required against collisions with the highly rigid front pillars on both side edges of the windshield that are arranged in a manner upright from the upper surface of the hood.

[0003] Therefore, as described in Patent Document 2 below, a pedestrian airbag device is folded and stored in a retainer case attached to a support member spanning between left and right vehicle bodies at an upper portion of a rear portion within an engine compartment.

[0004] Furthermore, Patent Document 3 below discloses that an airbag, which has been used to protect passengers in a vehicle collision, is also used to protect pedestrians.

[0005] These airbags deployed outside the vehicle must not only possess the characteristics required of conventional airbags deployed inside vehicles for the driver's and passenger seats, but also possess the inherent durability inherent to their exterior deployment. Specifically, they must withstand outdoor environmental conditions and the operational conditions required to maintain vehicle performance, such as light, ultraviolet rays, heat, rain, snow, low temperatures, hot water, oils, solvents, detergents, and dust. These environmental factors are particularly significant when the airbag is not contained in a sealed, robust container or when the container is damaged.

[0006] In this regard, for example, Patent Document 4 below discloses applying a covering material to the outer surface of an airbag body base fabric.

[0007] In addition, the following patent document 5 discloses that: in order to produce a coating amount of 20 g / m 2 The invention discloses an airbag base fabric which is excellent in lightness, can maintain air permeability before and after heat resistance test and humidity resistance test, and further maintains flame retardancy and is coated only with a specific water-soluble resin.

[0008] Prior art literature

[0009] Patent Literature

[0010] Patent Document 1: Japanese Patent Application Laid-Open No. 7-108903

[0011] Patent Document 2: Japanese Patent Application Laid-Open No. 2018-172006

[0012] Patent Document 3: Japanese Patent Application Laid-Open No. 2006-205805

[0013] Patent Document 4: Japanese Patent Application Laid-Open No. 2004-115981

[0014] Patent Document 5: Japanese Patent Application Laid-Open No. 2001-214371 Summary of the Invention

[0015] Problems to be solved by the invention

[0016] With the increasing diversity of airbag usage conditions, such as inside and outside vehicles, excellent flame retardancy is required regardless of which side of the airbag fabric is used as the exterior surface. The flammability evaluation standard (FMVSS302) requires the specimen to be held horizontally and ignited with the surface facing the cabin downward. Therefore, the evaluation is typically conducted with the fabric side (opposite the resin-coated surface) that will serve as the exterior surface of the airbag fabric facing downward. If the resin-coated surface serves as the exterior surface of the airbag fabric, ignition with the resin-coated surface facing downward increases the burning rate.

[0017] In addition, for airbags installed outside the cabin and deployed, flame retardancy after exposure to outdoor environmental conditions is desired.

[0018] Patent Document 4 does not fully investigate the flame retardancy when the resin-coated surface is the outer surface of the airbag base fabric, nor the flame retardancy after exposure to outdoor environmental conditions.

[0019] Patent Document 5 does not investigate the flame retardancy of both the front and back surfaces of the airbag base fabric.

[0020] Therefore, the problem to be solved by the present invention is to provide an airbag base fabric whose flammability is suppressed under the conditions of ignition of both the resin-coated surface and the uncoated surface in the flammability evaluation specified in FMVSS302 after environmental resistance testing.

[0021] Solutions for solving problems

[0022] The present invention is a base fabric for an air bag composed of a coated fabric. The present invention was completed based on the discovery that the base fabric has specific chemical properties and is thermally dimensionally stable, and thus its combustion properties are not easily affected by the environment.

[0023] That is, the present invention is as follows.

[0024] [1] A base fabric for an air bag, which is a multifilament fabric of polyamide, characterized in that:

[0025] The fabric has a silicone film layer on at least one side thereof,

[0026] The amount of the organic silicon film is 10 g / m 2 Above and 100g / m 2 the following,

[0027] The content of cyclopentanones is 0 ppm or more and 250 ppm or less relative to the weight of the fabric.

[0028] The larger shrinkage dimensional change rate of the airbag base fabric 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

[0029] The razor combing resistance after 400 hours under an environment of 85°C and 95% relative humidity is 350N or more.

[0030] [2] The base fabric for an airbag according to [1], wherein the amount of the oil component contained in the woven fabric is 0% by weight or more and 0.04% by weight or less.

[0031] [3] The base fabric for an air bag according to [1] or [2], which contains phosphorus atoms in an amount of 10 ppm to 300 ppm based on the weight of the constituent yarns of the woven fabric.

[0032] [4] The airbag base fabric according to any one of [1] to [3], wherein the amount of carboxylic acid terminals at the molecular chain ends of the polyamide is greater than the amount of amine terminals, and the difference is 10 mmol equivalents / kg or more and 50 mmol equivalents / kg or less.

[0033] [5] The base fabric for an air bag according to any one of [1] to [4], wherein the base fabric satisfies the following 1) or 2) in both the warp and weft directions in a combustion test of FMVSS302 after 400 hours at 80°C and 95% humidity:

[0034] 1) No matter which side of the base fabric is ignited, it will extinguish the fire.

[0035] 2) The burning speed of both the front and back surfaces of the base fabric is 100 mm / min or less, and the ratio of the burning speeds of the front and back surfaces is 1.0 to 3.0.

[0036] [6] A method for manufacturing a polyamide multifilament fabric for an airbag base fabric, characterized by comprising the following steps:

[0037] A step of melt-spinning polyamide to obtain a polyamide multifilament yarn having a cyclopentanone content of 0 ppm to 800 ppm;

[0038] a step of using the obtained polyamide multifilament yarn as a weaving yarn to obtain a fabric;

[0039] Scouring process using alkaline wash solution at temperatures above 35°C;

[0040] Drying process;

[0041] a step of coating at least one surface of the fabric with silicone to form a silicone film layer; and

[0042] Vulcanization shaping process.

[0043] [7] The method for producing a base fabric for an airbag according to [6], wherein in the scouring step, the base fabric is treated in an alkaline washing solution or a surfactant bath and then rinsed with water.

[0044] [8] The method for manufacturing a base fabric for an airbag according to [6] or [7], wherein, in the scouring step, the warp tension of the fabric during feeding is set to 0.08 N / cm or more and 0.8 N / cm or less.

[0045] [9] The method for manufacturing a base fabric for an airbag according to any one of [6] to [8], wherein in the vulcanization and setting step, the vulcanization and setting process is performed at a temperature of 160°C or higher and with a warp overfeed of 0.8% or higher.

[0046] Effects of the Invention

[0047] The airbag base fabric of the present invention exhibits minimal difference in flammability between its coated and uncoated surfaces and maintains excellent flame retardancy after environmental testing. This base fabric provides an airbag cushion particularly suitable for airbag systems installed outside the cabin, where environmental conditions are becoming increasingly severe. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 is the structural formula of compounds a) to d). DETAILED DESCRIPTION

[0049] Hereinafter, embodiments of the present invention will be described in detail.

[0050] One embodiment of the present invention is a base fabric for an airbag, which is composed of a polyamide multifilament fabric, and is characterized in that:

[0051] The fabric has a silicone film layer on at least one side thereof,

[0052] The amount of the organic silicon film is 10 g / m 2 Above and 100g / m 2 the following,

[0053] The content of cyclopentanones is 0 ppm or more and 250 ppm or less relative to the weight of the fabric.

[0054] The larger shrinkage dimensional change rate of the airbag base fabric 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

[0055] The razor combing resistance after 400 hours in an environment of 85°C and 95% relative humidity is 350N or more.

[0056] The yarns constituting the airbag base fabric are long fibers made of polyamide multifilament yarns. Polyamide fibers have a high melting point and large heat capacity, resulting in excellent resistance to explosion during explosive deployment of the airbag due to their resistance to melting. Furthermore, the presence of amide groups, amino groups at the polymer end, or carboxyl groups provides excellent adhesion to the coating film. Examples of polyamides include fibers composed of polyamide 6, polyamide 6.6, polyamide 11, polyamide 12, polyamide 6.10, polyamide 6.12, polyamide 4.6, their copolymers, and their mixtures. Among these, polyamide 6.6 fibers primarily composed of polyhexamethylene adipamide are preferred. Polyhexamethylene adipamide refers to a polyamide composed of 100% hexamethylene diamine and adipic acid with a melting point of 250°C or higher. The polyamide 6.6 fiber of the present invention may also include fibers composed of polymers obtained by copolymerizing or blending polyhexamethylene adipamide with polyamide 6, polyamide 6.I, polyamide 6.10, polyamide 6.T, etc. within a range of melting point not less than 250°C.

[0057] <Multifilament>

[0058] The fineness of the yarns constituting the base fabric is preferably 150 dtex or greater and 750 dtex or less. A fineness of 150 dtex or greater provides excellent mechanical properties when fabricated for material purposes. A fineness of 750 dtex or less prevents weft insertion from becoming too heavy and difficult to follow during high-speed weaving at 800 rpm or greater using a shuttleless loom, thus eliminating productivity issues. A fineness of 220 dtex or greater is more preferred, while a fineness of 550 dtex or less is more preferred, and a fineness of 450 dtex or less is even more preferred.

[0059] In this embodiment, the base fabric is composed of multifilament yarns consisting of monofilament bundles, and the monofilament fineness is preferably 1 dtex or greater and 7 dtex or less. A monofilament fineness of 1 dtex or greater minimizes degradation of mechanical properties during processing from yarn to base fabric. A monofilament fineness of 7 dtex or less improves microscopic adhesion to the coating, thereby suppressing the burning rate and stabilizing its behavior. Furthermore, the base fabric exhibits excellent flexibility, resulting in improved packability when fabricated into an airbag.

[0060] The cross section of the monofilament can be circular or irregular.

[0061] The density of a base fabric can be expressed by its degree of filling within a plane, or the cover factor. The cover factor is calculated from the yarn fineness and fabric density of the base fabric. The cover factor CF is calculated by summing the warp (w) and weft (f) dimensions based on the yarn fineness d (dtex) and fabric density D (roots / 2.54 cm).

[0062] CF=(√(dw)×Dw)+(√(df)×Df)

[0063] In this embodiment, the cover factor is preferably 1,800 or higher and 2,500 or lower. A cover factor of 1,800 or higher is preferred because the mechanical properties of the base fabric are improved due to the fabric density effect. A cover factor of 2,000 or higher is more preferred. A cover factor of 2,500 or lower, or lower, reduces the mixing of constituent yarns and improves the softness of the base fabric. This is preferred because it provides excellent storability as an airbag. A cover factor of 2,300 or lower is more preferred.

[0064] The airbag base fabric of this embodiment has a layer of organic silicone film on at least one side of the fabric. The organic silicone film can be a coating film or an adhesive film. The amount of the organic silicone film is 10g / m 2 Above and 100g / m 2 If the amount of silicone film is 10g / m 2 More than 15g / m 2 If the amount of silicone is 100g / m 2 The amount of the silicone film is more preferably 70 g / m 2 Below, more preferably 40g / m 2 the following.

[0065] The content of cyclopentanones in the airbag base fabric of this embodiment is 250 ppm or less relative to the weight of the constituent yarns. Figure 1The compounds shown are a) cyclopentanone, b) cyclopenten-1-one, c) 1,1'-bicyclopentyl-2-one, and d) cyclopentanone, 2-cyclopentylidene. The cyclopentanones content refers to the total content of these compounds. A cyclopentanone content of 250 ppm or less provides good adhesion to the silicone layer and minimizes the increase in burning rate after exposure to heat and humidity. A cyclopentanone content of 150 ppm or less is more preferred, and 50 ppm or less is most preferred. 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, particularly weakening adhesion after exposure to heat and humidity. Cyclopentanones are derived from polyamides and are generated by thermal aging of polyamides at their melting temperatures. Cyclopentanone that is not completely removed during the processing of polyamide yarn into base fabric remains in the base fabric. The cyclopentanone content can be analyzed by gas chromatography, but some cyclopentanone dimerizes during the analysis process, so it is quantified as cyclopentanone compounds. The cyclopentanone compound content varies depending on the cyclopentanone compound content in the polyamide yarn used for weaving and the processing conditions during the processing into the base fabric.

[0066] To reduce the cyclopentanones content in the fabric of the base fabric to 250 ppm or less relative to the weight of the constituent yarns, it is preferred to perform scouring with an alkaline wash solution at a temperature of 35°C or higher during post-weaving scouring. More preferably, scouring with an alkaline wash solution at a temperature of 60°C or higher is performed. Furthermore, rinsing with neutral water after the alkaline wash can reduce the cyclopentanones content. Furthermore, during this scouring step, the base fabric relaxes, promoting the penetration of the wash solution into the constituent yarns of the base fabric and reducing the cyclopentanones content.

[0067] The airbag fabric of this embodiment exhibits a maximum shrinkage dimensional change of 1.4% or less in both the warp and weft directions at 105°C for 60 minutes. Thermal dimensional stability is as low as 1.4% or less, with lower values ​​indicating a smaller increase in burning rate after exposure to a hot and humid environment. This 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 heat setting process during the final stage of fabric processing. Typically, dimensional change in the warp direction is greater, while dimensional change in the weft direction is smaller and more stable, at 0.1% or less.

[0068] To suppress the burning rate of the airbag fabric, it is sufficient to suppress the supply of combustion gas to the combustion flame. The combustion gas is mainly composed of decomposition gases of polyamide. However, when the fabric is placed with the silicone layer facing upward using a horizontal combustion method, the flame-retardant silicone layer suppresses the movement of the gas to the upper surface of the fabric by the combustion flame, thereby suppressing the burning rate. On the other hand, when the fabric is placed with the silicone layer facing downward using a horizontal combustion method, the supply of combustion gas to the upper surface of the fabric is not blocked, resulting in a higher burning rate. In particular, after exposure to a hot and humid environment, the silicone layer peels off and cracks due to the reduced adhesion of the silicone layer and the dimensional change (shrinkage) of the fabric. The silicone layer does not block the combustion gas, thus further increasing the burning rate. For this reason, the low content of cyclopentanone and the good dimensional stability complement each other and can suppress the increase in the burning rate after exposure to a hot and humid environment.

[0069] In order to reduce the larger shrinkage dimensional change rate in each of the warp and weft directions before and after heating at 105°C for 60 minutes to 0-1.4%, the warp direction overfeed is preferably 0.8% or more in the vulcanization setting step after silicone coating at a temperature of 160°C or higher. An overfeed of 1.0% or more is more preferred. An overfeed of 8.0% or less is preferred because stable processing can be achieved.

[0070] The blade combing resistance of the base fabric for airbags of this embodiment after being placed in a hot and humid environment (400 hours in an environment of 85°C and 95% relative humidity) is preferably 350N or more. It is more preferably 420N or more, and even more preferably 470N or more. The blade combing resistance is the resistance to displacement of the constituent yarns of the fabric, and is a combination of the restraint force of the constituent yarns of the fabric tissue and the resistance to silicone adhesion. The greater the blade combing resistance is at least 350N, the better the adhesion of the silicone layer. The high blade combing resistance becomes a factor in suppressing the burning rate. On the other hand, if the blade combing resistance is 800N or less, the tearing resistance becomes a sufficiently high value.

[0071] The amount of oil component contained in the fabric of the airbag base fabric of this embodiment is preferably 0.04% by weight or less. This indicates that the less the amount of oil component is below 0.04% by weight, the more complete the deoiling process in the scouring process. The amount of oil component contained in the fabric is more preferably 0.02% by weight or less. By reducing the amount of oil component, the adhesion between the polyamide fiber and the silicone layer is good, and by reducing the content of cyclopentanone, it helps to improve the adhesion and thus avoid adhesion damage after a hot and humid environment. The weaving raw yarn has about 1% processing oil, which can be removed by scouring after weaving. On the other hand, the amount of oil component is preferably 0.005% by weight or more. The tear resistance becomes a sufficiently high value.

[0072] The phosphorus content of the airbag base fabric of this embodiment is preferably 10 ppm to 300 ppm relative to the weight of the constituent yarn. A higher phosphorus content suppresses combustion gas generation and enhances the combustion suppression effect. The phosphorus content is more preferably 30 ppm or higher, and even more preferably 40 ppm or higher. However, since phosphorus can act as a catalyst poison during organosilicon crosslinking, there is an upper limit to its content. The phosphorus content is more preferably 200 ppm or lower, and even more preferably 150 ppm or lower.

[0073] Phosphorus atoms are derived from the catalyst used to produce polyamide resins. Examples of catalysts 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; phosphinic acid compounds such as phenylphosphinic acid, sodium phenylphosphite, and ethyl phenylphosphite; phosphinic acid compounds such as phenylphosphonic acid, ethylphosphonic acid, sodium phenylphosphite, diethyl phenylphosphite, and sodium ethylphosphite; and phosphorous acid compounds such as phosphorous acid, sodium hydrogenphosphite, sodium phosphite, triethyl phosphite, triphenyl phosphite, and pyrophosphorous acid.

[0074] The polyamide preferably contains phenylphosphonic acid or a metal salt thereof as a phosphorus component in an amount of 10 ppm to 300 ppm based on the weight of the polymer. Phenylphosphonic acid and the like are generally used as polymerization catalysts.

[0075] As a method for obtaining polyamide 6·6 containing phenylphosphonic acid or a metal salt thereof, phenylphosphonic acid or a metal salt thereof can be added during solution polymerization. Even if phenylphosphinic acid or a metal salt thereof is added, it will be oxidized during the process to become phenylphosphonic acid, so any additive can be used.

[0076] Additives can be introduced during the polymerization process. Small amounts of 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 substitutions; copper halide, copper acetate and halogen, 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.), crystal nucleating agents (talc, etc.) can be included. , silica, kaolin, clay, etc.), plasticizers (octyl p-hydroxybenzoate, N-butylbenzenesulfonamide, etc.), antistatic agents (alkyl sulfate type anionic antistatic agents, quaternary ammonium salt type cationic antistatic agents, polyoxyethylene sorbitan monostearate and other non-ionic antistatic agents; betaine type amphoteric antistatic agents, etc.), flame retardants (melamine cyanurate, magnesium hydroxide, aluminum hydroxide and other hydroxides; ammonium polyphosphate; brominated polystyrene, brominated polyphenylene ether, brominated polycarbonate, brominated epoxy resin or a combination of these brominated flame retardants and antimony trioxide, etc.), light stabilizers such as manganese acetate, and defoaming agents.

[0077] During the polymerization of polyamide, in order to suppress the formation of cyclopentanones and to allow the polymerization reaction to proceed uniformly in a short time, it is important to balance the concentrations of amino end groups and carbon end groups to increase the degree of polymerization.

[0078] To achieve high physical properties in the fiber, a higher degree of polymerization is preferred. The total amount of amino and carbon end groups in high-polymerization polyamides is preferably 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. On the other hand, to achieve uniform fiber quality, the total amount 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.

[0079] Furthermore, in this embodiment, the polyamide has an excessive carboxyl end group concentration relative to the amino end group concentration, with the end group concentration difference preferably being 5 millimolar equivalents / kg polymer or more and 80 millimolar equivalents / kg polymer or less, more preferably 10 millimolar equivalents / kg polymer or more and 60 millimolar equivalents / kg polymer or less, and even more preferably 20 millimolar equivalents / kg polymer or more and 50 millimolar equivalents / kg polymer or less. When the carboxyl end group concentration is high and the concentration difference is as large as 5 millimolar equivalents / kg polymer or more, the internal hydrogen ion concentration of the polyamide is high, the catalytic toxicity of the phosphorus compound is suppressed, the adhesion between the polyamide and the silicone is good, and the bond has good resistance to moisture and heat. When the carboxyl end group concentration is excessive and the concentration difference is 80 millimolar equivalents / kg polymer or less, the degree of polymerization increases, making it easier to obtain high-strength fibers during stretching. Furthermore, when the carboxyl end group concentration is high, the generation of tertiary amines during melting is suppressed, the spinning process is improved, and yarn with good raising quality can be obtained.

[0080] Another embodiment of the present invention is a method for manufacturing a polyamide multifilament fabric for an airbag base fabric, characterized by comprising the following steps:

[0081] A step of melt-spinning polyamide to obtain a polyamide multifilament yarn having a cyclopentanone content of 0 ppm to 800 ppm;

[0082] a step of using the obtained polyamide multifilament yarn as a weaving yarn to obtain a fabric;

[0083] Scouring process using alkaline wash solution at temperatures above 35°C;

[0084] Drying process;

[0085] a step of coating at least one surface of the fabric with silicone to form a silicone film layer; and

[0086] Vulcanization shaping process,

[0087] 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.

[0088] As the polymerization reaction device that is used to make the resin combination that constitutes polyamide fiber, the operation of heating and removing moisture under high pressure at a lower temperature, the operation of carrying out polycondensation reaction at high temperature are useful.Reaction unit now can be a single tank, also can be a continuous double tank device.This polyamide resin composition is ejected from polymerization reaction device with linear shape etc., temporarily cools / cuts and makes pellet shape, then dry and removes moisture, can obtain being applicable to the pellet of fiber.In the manufacture method of the resin combination that is used for polyamide fiber, can after making polyamide resin composition polymerize in liquid phase, further carry out solid phase polymerization to improve polymerization degree.The solid phase polymerization method that carries out below the melt temperature also can suppress the thermal aging of polymer itself, and can not increase the cyclopentanone class in the polymer, therefore is preferred method. For example, the polyamide resin may contain a small amount of antioxidants, heat stabilizers (hindered phenol compounds, hydroquinone compounds, thiazole compounds, phenylphosphonic acid and other phosphorus compounds; imidazole compounds such as 2-mercaptobenzimidazole and their substitution products; copper halide, 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.), etc. ), crystal nucleating agents (talc, silica, kaolin, clay, etc.), plasticizers (octyl p-hydroxybenzoate, N-butylbenzenesulfonamide, etc.), antistatic agents (alkyl sulfate type anionic antistatic agents, quaternary ammonium salt type cationic antistatic agents, polyoxyethylene sorbitan monostearate and other non-ionic antistatic agents; betaine type amphoteric antistatic agents, etc.), flame retardants (hydroxides such as melamine cyanurate, magnesium hydroxide, aluminum hydroxide; ammonium polyphosphate; brominated polystyrene, brominated polyphenylene ether, brominated polycarbonate, brominated epoxy resin, or a combination of these brominated flame retardants and antimony trioxide, etc.).

[0089] 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 is suppressed, and is more preferably 300°C or lower, and even more preferably 295°C or lower. On the other hand, setting the spinning temperature to 290°C or higher is preferred because the polyamide exhibits sufficient melt fluidity, the ejection amount between the ejection holes is uniform, and high-ratio stretching is possible.

[0090] The shorter the residence time (the time until the polyamide resin melts and is ejected from the spinneret) in the melt spinning process, the better. The residence time is preferably 30 minutes or less, more preferably 15 minutes or less, and even more preferably 0.5 minutes or more and 7 minutes or less. At the melt temperature, the cyclopentanones in the polymer increase, so a short residence time is preferred.

[0091] In the melt spinning process, a single-screw or twin-screw extruder is preferably used in the melt section. This extruder can apply appropriate pressure to the polyamide resin while simultaneously introducing it into the polymer piping, gear pump, and spinning bag. This suppresses the increase in cyclopentanones caused by thermal decomposition of the polyamide and prevents abnormal accumulation in these flow paths, making it preferable.

[0092] Furthermore, it is preferred to filter the polyamide resin through a metal fiber nonwoven fabric filter, sand, or the like before ejecting the polyamide resin from the spinneret, because this stabilizes the spinning operation.

[0093] The shape of the nozzle hole in the spinneret can be selected according to the cross-sectional shape of the single fiber constituting the filament to be produced. The spun fibers from the spinneret are solidified with cooling air, given a process oil, and then drawn and heat-treated after being taken out to obtain the polyamide fiber used in the present invention.

[0094] For polyamide fibers, it is important that the amount of cyclopentanones in the polymer be low through the aforementioned appropriate production method. By reducing the amount of cyclopentanones in the woven polyamide fibers, the amount of cyclopentanones in the airbag fabric can be reduced. The amount of cyclopentanones in the polyamide fibers 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.

[0095] The strength of the polyamide fiber filaments is preferably 7 cN / dtex. By setting the strength to 7 cN / dtex or higher, fuzzing is less likely to occur even when the weaving tension during the weaving process is increased, and a high-density fabric can be obtained with good manufacturing process compliance. Therefore, it is preferred, more preferably 7.5 cN / dtex or higher, further preferably 8 cN / dtex or higher, even more preferably 9.0 cN / dtex or higher, and most preferably 9.5 cN / dtex or higher. Taking other characteristics and production costs into consideration, the tensile strength of the polyamide fiber filaments is substantially 10.5 cN / dtex or lower.

[0096] The oil adhesion rate of polyamide fibers is preferably between 0.6 and 1.5 wt%. If the oil adhesion rate is 1.5 wt% or less, the weft yarn is virtually prevented from flying due to stickiness (tackiness). Furthermore, since the filaments are bundled more effectively than those achieved through interlacing, the apparent cross-sectional area is reduced, so the air or water used as the weft transport medium does not lose its weft transporting power, resulting in excellent weaving stability. On the other hand, if the oil adhesion rate is 0.6 wt% or more, the weft yarn is smoothly fed due to the appropriate friction reduction effect, resulting in no weaving downtime and excellent productivity.

[0097] Weaving machines can include water jet looms, air jet looms, and rapier looms. Airbag base fabrics are high-density fabrics, and it is preferable to increase warp tension during the warping and weaving processes to ensure high process quality. High warp tension during weaving and efficient beating-up conditions create high-density fabrics. In particular, this results in a curved shape where the warp yarns are fully engaged, resulting in greater warp crimp.

[0098] The fabric woven in this way can wash away the process oil of polyamide fiber in the refining process, and at the same time reduce the content of cyclopentanone in the fiber.

[0099] The scouring process can be performed using warm water, pressurized hot water, or the like, and the treatment process can be a single stage or a multi-stage process of two or more stages. It is also preferred to perform scouring using a conventionally known scouring agent. Combinations of nonionic surfactants and alkali ash, or combinations of higher alcohol sulfates and alkali ash, are used. Scouring using alkali agents such as alkali ash is particularly effective for removing process oils from the fiber surface and reducing the amount of cyclopentanone in the fiber.

[0100] The temperature of the scouring process is preferably above 35°C, more preferably above 60°C and below 98°C. The higher the temperature of the scouring process, the more the content of cyclopentanones in the fiber can be reduced. The scouring process is preferably followed by 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 preferred to divide the water washing process into multiple stages or extend the retention time. By increasing the hydrogen ion concentration inside the polyamide fiber, the catalyst toxicity of the organosilicon addition reaction of the phosphorus compound can be suppressed, thereby avoiding the inhibition of the adhesion between the organosilicon and the fabric.

[0101] Scouring process can be carried out continuously after weaving process, also can carry out in other operation again after weaving earlier.In addition, can adopt any one in intermittent mode, continuous mode, but when base fabric is supplied to treatment zone and discharges, continuously handle when productivity is excellent, so preferred.

[0102] In the scouring step, the removal of cyclopentanone can be promoted by relaxing the fabric structure.

[0103] Regarding the fabric clamping in the scouring bath, it is preferred to feed the fabric without clamping it in the width direction. The feeding tension in the warp direction is preferably set to 0.8 N / cm or less, more preferably 0.5 N / cm or less.

[0104] In order to prevent the fabric from becoming loose and wrinkled during transportation, the warp tension is preferably set to 0.08 N / cm or more.

[0105] During transportation, in order to control the tension, a dancer roller or the like can be set to control the tension load.

[0106] During the scouring process, the fabric shrinks according to the bath temperature and the thermal shrinkage characteristics of the constituent fibers. Although shrinkage occurs, the warp tension is controlled at a low level, and the width direction is allowed to shrink. Relaxing the fabric structure will help remove cyclopentanone.

[0107] The fabric is preferably heat-set during the heat-setting step. The heat-setting temperature is preferably 110°C to 160°C, more preferably 130°C to 150°C, and the heat-setting time can be appropriately selected within the range of 0.1 to 30 minutes. Furthermore, during the heat-setting step, the fabric is preferably dried while being stretched to maintain a predetermined shrinkage force. Heat-setting the fabric stabilizes the process of the subsequent resin coating step.

[0108] The fabric after the scouring step can be dried as needed before the heat setting step. The drying temperature is preferably between 80°C and 130°C, more preferably between 100°C and 120°C. The drying time is preferably between 0.1 and 30 minutes. Drying can be performed while the fabric is relaxed or stretched.

[0109] The base fabric for an airbag of the present embodiment is coated with silicone and then subjected to a final heat setting process to obtain a coated base fabric for an airbag.

[0110] The silicone to be applied preferably has excellent flame retardancy, heat resistance, air barrier properties, and the like.

[0111] Silicone is preferably coated without a solvent as an addition reaction type curing silicone rubber.

[0112] The alkenyl organopolysiloxane, the main component of the silicone, is the base polymer of the coating agent and contains at least two alkenyl groups bonded to silicon atoms. Generally, substantially linear organopolysiloxanes are preferred. Specifically, linear diorganopolysiloxanes whose molecular chains are mainly composed of repeating diorganosiloxane units and whose molecular chains are terminated at both ends by triorganosiloxy groups are preferred. In addition, the position of the alkenyl group bonded to the silicon atom of the main chain is not particularly limited. The alkenyl group may be bonded to only one of the silicon atoms at the terminal portion of the molecular chain and to the silicon atoms at the non-terminal portion of the molecular chain, or to both. Examples of side chain organic groups include non-substituted or substituted monovalent hydrocarbon groups having 1 to 10 carbon atoms and containing no aliphatic unsaturated bonds. Among them, methyl, phenyl, or a combination of these are preferred. Examples of alkenyl groups include alkenyl groups having 2 to 8 carbon atoms. Examples include vinyl, allyl, 1-propenyl, isopropenyl, 1-butenyl, isobutenyl, and hexenyl. Among them, vinyl is preferred.

[0113] The organosilicon compound serving as the crosslinking component of the organosilicon 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 ends of the molecular chain), and hydrocarbon compounds containing at least two (particularly two or three) diorganohydrogensilyl groups. Examples of the organic group bonded to the silicon atom include alkyl groups such as methyl, ethyl, propyl, butyl, pentyl, and hexyl; aryl groups such as phenyl, tolyl, and xylyl; and haloalkyl groups such as 3-chloropropyl and 3,3,3-trifluoropropyl. Examples of the diorganohydrogensilyl group include dimethylhydrogensilyl. Specific examples include methylsilane ((CH3)SiH3), dimethylsilane ((CH3)2SiH2), ethylsilane ((C2H5)SiH3), diethylsilane ((C2H5)2SiH2), 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(dimethylhydrogensilyloxy)methylsilane, tris(dimethylhydrogensilyloxy)phenylsilane, tris(dimethylhydrogensilylethyl)methylsilane, tris(dimethylhydrogensilylethyl)phenylsilane and 1,4-bis(dimethylhydrogensilyl)benzene, etc.

[0114] The content of the crosslinking component is such that the molar ratio of silicon-bonded hydrogen atoms in this component to alkenyl groups in the total coating agent is within the range of 0.01 to 5.0, preferably within the range of 0.1 to 2.0, and particularly preferably within the range of 0.1 to 1.0. In this case, the ratio of alkenyl groups in component (A) to alkenyl groups in the total coating agent is preferably 90 mol% to 100 mol%, more preferably 95 to 100 mol%.

[0115] The reaction catalyst of organosilicon is composed of a platinum group metal catalyst. As a hydrosilylation reaction catalyst, a known catalyst can be used. For example, platinum group metals such as platinum (including platinum black), rhodium, and palladium; platinum chloride, chloroplatinic acid, and chloroplatinates such as H2PtCl4·nH2O, H2PtCl6·nH2O, NaHPtCl6·nH2O, KHPtCl6·nH2O, Na2PtCl6·nH2O, K2PtCl4·nH2O, PtCl4·nH2O, PtCl2, and Na2HPtCl4·nH2O (wherein n is an integer from 0 to 6, preferably 0 or 6); alcohol-modified chloroplatinic acid; complexes of chloroplatinic acid and olefins; substances obtained by loading platinum group metals such as platinum black and palladium on supports such as alumina, silica, and carbon; complexes of platinum and triphenylphosphine; rhodium-olefin complexes; tris(triphenylphosphine)rhodium chloride (Wilkinson catalyst); complexes of platinum chloride, chloroplatinic acid or chloroplatinates with vinyl-containing silicones, especially vinyl-containing cyclic silicones, etc. Among them, platinum-based catalysts such as complexes with vinyl-containing cyclic organosilicon and complexes of platinum and triphenylphosphine are particularly preferred.

[0116] Silicones can also contain ingredients other than those listed above. For example, inorganic fillers used to improve the properties of cured resins include finely powdered silica for resin strength and calcium carbonate powder for increased toughness. Curing reaction control agents include acetylene compounds such as 3,5-dimethyl-1-hexyn-3-ol and enyne compounds such as 3,5-dimethyl-3-hexene-1-yne. Adhesion enhancers include silane coupling agents such as methyltrimethoxysilane.

[0117] The silicone coating amount of the airbag base fabric is 10g / m 2 Above and 100g / m 2 Below, more preferably 15g / m 2 Above and 70g / m 2 Below, more preferably 20g / m 2 Above 40g / m 2 Below. Pass 10g / m 2 On the other hand, by 100g / m 2 With the coating amount below, the coated fabric has flexibility, good storage properties, and the weight of the entire airbag is suppressed.

[0118] Methods for coating the fabric surface with silicone include immersing the fabric in a tank of resin solution and then using a mangle, vacuum device, coating knife, or the like to smooth out excess resin; bar coating using a comma coater or other similar method; and spraying the resin using a sprayer or molding device. Of these, knife coating of solvent-free silicone is preferred from the perspective of uniform and minimal resin application.

[0119] In particular, when using an air knife coating method, it is preferred to apply the coating within a range of 15 N / cm to 15 N / cm in contact with the fabric, and a base fabric tension within a range of 100 N / cm to 3000 N / cm. High air knife contact pressure allows for a thinner coating, allowing for a lighter and more uniform coating amount. The base fabric tension during the coating process acts to stretch the fabric in the warp direction and accumulate thermal strain.

[0120] After silicone coating, a vulcanization-setting process (final heat setting) is performed to vulcanize and crosslink the silicone or to achieve final heat setting of the base fabric. It is important to stabilize the warp yarn strain caused by warp tension during the coating process. Therefore, it is preferred to perform the setting process with an overfeed of 0.8% or more in the warp direction, preferably 1.0% to 3.0%. The amount of overfeed is determined based on the yarn shrinkage and the heat treatment conditions of each process. Overfeeding can eliminate warp strain and improve the thermal dimensional stability of the base fabric.

[0121] The final heat setting temperature is selected to promote silicone vulcanization and improve the dimensional stability of the nylon fabric. The final heat setting temperature is preferably 160°C to 210°C, and more preferably 170°C to 200°C.

[0122] In the final heat setting process, it is preferred to set the overfeed in the warp direction to 0.8% or more and 3.0% or less and the temperature to 160°C or more and 210°C or less in order to improve the thermal dimensional stability of the base fabric.

[0123] The airbag fabric of this embodiment preferably exhibits self-extinguishing properties in both the warp and weft directions, or exhibits a burning rate of 100 mm / minute or less, in a FMVSS302 combustion test after 400 hours at 80°C and 95% humidity. Specifically, the airbag fabric preferably exhibits self-extinguishing properties in both the warp and weft directions, or exhibits a burning rate of 100 mm / minute or less, in a FMVSS302 combustion test after 400 hours at 80°C and 95% humidity. Specifically, the airbag fabric preferably exhibits self-extinguishing properties or a burning rate of 100 mm / minute or less, in both the warp and weft directions, regardless of whether the fabric is ignited from either side.

[0124] Furthermore, the airbag fabric of this embodiment preferably does not exhibit increased flammability due to wet heat treatment. Specifically, the increase in the burning rate after wet heat treatment relative to the burning rate before wet heat treatment at 80°C and 95% humidity for 400 hours is preferably 40% or less, more preferably 30% or less, and even more preferably 20% or less.

[0125] Silicone adheres well to the nylon fabric, and along with thermal dimensional stability, it suppresses the increase in burning rate caused by wet heat treatment. If this increase in burning rate is suppressed, the flame retardancy of the airbag can be maintained even in harsh environments.

[0126] In the FMVSS302 combustion test, the airbag base fabric of this embodiment preferably exhibits a burning rate ratio of 3.0 or less, more preferably 2.5 or less, when ignited on the coated side (coated side facing downward) relative to the fabric side (coated side facing upward) in the evaluation of burning rate after wet heat treatment. The lower limit of the burning rate ratio is preferably 1.0 or greater. The base fabric is fully bonded to the polyamide fiber fabric through silicone and is thermally dimensionally stable, so that the difference in burning rate between the coated and inner surfaces does not increase under ambient conditions. This means that flame retardancy can be maintained even when the coated surface of the airbag cushion is exposed in harsh vehicle-mounted airbag environments.

[0127] In addition, as described above, the blade combing resistance of the base fabric for airbags of this embodiment after being exposed to a hot and humid environment (400 hours at 85°C and 95% relative humidity) is preferably 350N or more. It is more preferably 420N or more, and even more preferably 470N or more. The blade combing resistance is the resistance to displacement of the constituent yarns of the fabric, and is a combination of the restraint force of the constituent yarns of the fabric tissue and the resistance to silicone adhesion. The greater the blade combing resistance is above 350N, the better the adhesion of the silicone layer. This high blade combing resistance becomes a factor that suppresses the burning rate. On the other hand, if the blade combing resistance is 800N or less, the tearing resistance becomes a sufficiently high value.

[0128] Example

[0129] The present invention will be described in detail below with reference to Examples. It should be noted that various evaluations in the Examples were performed according to the following methods.

[0130] (1) Silicone coating amount of base fabric

[0131] A sample of 0.3 m square area (A) was cut from the base fabric, degreased with dichloromethane, and dried at 105°C. The sample was dissolved in 200 g of 90% formic acid at room temperature, filtered using a glass sintered filter (VIDTEC glass filter 17G-3, improved from Cosmo Speed) to separate the insoluble components, thoroughly rinsed with formic acid and water, and the insoluble components were dried at 105°C. The mass (M) was accurately measured. Coating weight (g / m 2 ) is obtained by dividing the formic acid insoluble component (M) by the area (A) of the fabric sample.

[0132] (2) Quantification of cyclopentanones in polyamide resin, fiber, and base fabric before melt spinning

[0133] As a sample, polyamide resin, polyamide fiber or base fabric is chopped and prepared in a standard state (20° C., relative humidity 65%, and left for 24 hours or more).

[0134] Analysis was performed using the HS-SPME-GC / MS method. Approximately 10 mg of sample was accurately weighed and placed in a headspace vial. The SPME fiber assembly consisted of a PDMS fiber coated with polydimethylsiloxane. The vial containing the sample was heated at 180°C for 5 minutes using a block heater, then removed and allowed to cool to room temperature for 5 minutes. The SPME was then removed and subjected to GC / MS analysis. Quantitative analysis was performed using a cyclopentanone standard. The cyclopentanone content was calculated by adding the following four compounds: a) cyclopentanone, b) cyclopenten-1-one, c) 1,1'-bicyclopentyl-2-one, and d) cyclopentanone, 2-cyclopentylidene. For polyamide fiber samples, the cyclopentanone content (ppm) in the accurately weighed sample was determined. When the sample is a base fabric, the cyclopentanone content (ppm) in the fabric is calculated by subtracting the amount of silicone coating from the accurately weighed weight of the base fabric.

[0135] The GC / MS was manufactured by Agilent and included GC: 7890B and MS: 5977B. Various conditions were set as follows.

[0136] Chromatographic column: DB-1MS (30m×0.25mm, film thickness 0.25μm)

[0137] Column temperature: 40°C (3 minutes) → 20°C / minute → 300°C

[0138] Column flow rate: 1.0 ml / min

[0139] Column flow rate: 1.0 mL / min

[0140] Injection method: splitless

[0141] Injection temperature: 250℃

[0142] Interface temperature: 280℃

[0143] Ion source temperature: 230°C

[0144] Ion source: EI method

[0145] Scan range: 50-500 m / z

[0146] (3) End basis weight of the yarns constituting the base fabric (base fabric 20 cm)

[0147] Pull out the constituent fibers from the base and take 5 to 10 g of sample.

[0148] (3a) Amino end group concentration

[0149] A sample fiber sample, obtained by pulling the constituent fibers from the base, was accurately weighed and dissolved in a 90% aqueous phenol solution. After complete dissolution, the solution was titrated with a 0.05N aqueous hydrochloric acid solution to a pH of 3. The amino end group concentration per kg of polymer was calculated based on the titrated amount.

[0150] (3b) Carboxyl end group concentration

[0151] Precisely weigh the constituent silk sample as described above and dissolve it in benzyl alcohol at 170°C. Once completely dissolved, add phenolphthalein as an indicator. Then, perform a colorimetric titration with 0.1N NaOH in ethylene glycol. Calculate the carboxyl end group concentration per kg of polymer based on the titration amount.

[0152] The value obtained by subtracting the amino end group concentration from the carboxyl end group concentration was taken as the end group difference value constituting the textile, and the value obtained by adding the carboxyl end group concentration and the amino end group concentration was taken as the total end group value constituting the textile.

[0153] (4) Quantification of phosphorus content in base fabric

[0154] The constituent fibers were pulled out from the base to collect a sample of about 0.5 g.

[0155] The content of phosphorus atoms derived from phosphate groups in the constituent silk was determined by inductively coupled plasma atomic emission spectrometry (ICP-AES) using the following apparatus and conditions.

[0156] (Measurement conditions)

[0157] ICP-AES apparatus: iCAP6300Duo manufactured by Thermo Fisher Scientific

[0158] High frequency output: 1150W

[0159] Plasma gas: 12L / min

[0160] Auxiliary gas: 0.5L / min

[0161] Atomizing gas: 0.5L / min

[0162] Metering: Axial

[0163] Measurement wavelength: 213nm

[0164] Pretreatment method: Use sulfuric acid, nitric acid and hydrochloric acid to wet decompose the sample as the detection solution.

[0165] (5) Oil content of base fabric

[0166] The measurement is performed by Soxhlet extraction in accordance with JIS L1095 (2010) 9.30. Cyclohexane is used as the solvent. For the base fabric sample, the moisture content is measured by the Karl-Fischer titration method of water vaporization using JIS K0068 (2001), and the absolute dry weight is calculated based on the accurately weighed weight of the base fabric sample. In addition, the weight of the fabric sample is converted to the weight of the fabric after subtracting the amount of silicone coating from the weight of the base fabric. The amount of oil component in the fabric is calculated based on the amount of oil component extracted by Soxhlet and the weight of the fabric sample. In order to ensure the weighing accuracy of the extracted dry solid, a new base fabric sample is replaced when necessary and the extraction is repeated.

[0167] (6) Shrinkage dimensional change rate of the base fabric

[0168] Use a base fabric exposed to an environment with a temperature of 20°C and a relative humidity of 65% for more than 24 hours, and cut 150mm square slices along the warp and weft directions of the base fabric as samples. On the cut slices, draw markings with an interval of 100mm in the warp and weft directions at accurate intervals. Place the sample slices in a hot air oven at 105°C for 60 minutes without tension. Take them out and expose them to an environment with a temperature of 20°C and a relative humidity of 65% for more than 24 hours, and then measure the distance between the markings in the warp and weft directions. Calculate the shrinkage change rate (%) of the distance between the markings relative to the original 100mm. Repeat 3 times and calculate the average value. The value of the direction showing a larger shrinkage change rate in both the warp and weft directions is used as the shrinkage size change rate.

[0169] (7) Burning rate of base fabric, increase in burning rate after wet heat treatment, and burning rate ratio of surface and inner surface (C / W ratio)

[0170] Conduct FMVSS302 combustion test.

[0171] The burning rate of a standard base fabric and a base fabric subjected to a standard condition after 400 hours of exposure to 80°C and 95% relative humidity was evaluated. The fabric was fixed to a U-shaped frame and placed horizontally. The coated surface was facing downward, and the sample was ignited from the end with a burner flame. The test was conducted in both the warp and weft directions, and the percentage increase in burning rate before and after the wet heat treatment was evaluated.

[0172] In addition, for base fabric samples that were prepared into a standard state after being maintained in an environment of 80°C and 95% relative humidity for 400 hours, when the samples were fixed to a U-shaped frame and placed horizontally, the burning rates were evaluated for the cases where the coated side was facing down and ignited from the end of the sample with a burner flame, and for the cases where the fabric side was facing down and ignited from the end of the sample with a burner flame. The ratio of the burning rate with the coated side facing down (C evaluation) to the burning rate with the fabric side facing down (W evaluation) was evaluated and shown in the table below as the burning rate ratio (C / W ratio) of the inside and outside after wet heat treatment.

[0173] (8) Increased air permeability of the base fabric after heat and humidity treatment

[0174] Air permeability (mm / s) was measured at a pressure of 50 kPa using a "High-Pressure Air Permeability Meter" manufactured by Cosmo Instruments. The base fabric sample was compared with a standard sample and a standard sample obtained by maintaining the base fabric sample at 80°C and 95% relative humidity for 400 hours. The air permeability increase (mm / s) after the wet heat treatment was determined.

[0175] (9) Blade combing resistance of base fabric after wet heat treatment

[0176] According to ASTM-D6479 (2015), 5 samples each in the warp and weft directions were kept at 80°C and 95% relative humidity for 400 hours to obtain a base fabric in a standard state. The razor combing resistance was measured, and the values ​​were averaged.

[0177] The base fabric sample was prepared by keeping the base fabric in a standard state for 400 hours under an environment of 80° C. and 95% relative humidity.

[0178] (10) Evaluation of scrubbing of base fabric

[0179] Coating adhesion was confirmed by a rubbing test. The test was conducted using a scrub tester in accordance with ISO 5981. The test was conducted on a standard base fabric and a base fabric that had been maintained at 80°C and 95% relative humidity for 400 hours. The fabric was rubbed at least 200 times, with observations made every 50 cycles. The number of times peeling was observed was evaluated.

[0180] [Example 1]

[0181] The terminal uncapped polyamide 6·6 polymer is polymerized using phenylphosphonic acid as a polymerization catalyst and copper iodide and potassium iodide as heat stabilizers, and the polymer is output in the form of chips and further solid phase polymerization is carried out.

[0182] The polymer sheet was melted at 300°C, discharged by melt spinning at 290°C for 180 seconds, and then stretched after being treated with a spinning oil containing an aliphatic synthetic ester to produce polyamide 6.6 fiber 470 dtex 136 filaments. 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 millimole equivalents / kg polymer. The cyclopentanone content in the fiber was 500 ppm. The boiling water shrinkage according to JIS L1017 (2002) 8.14 was 7.5%.

[0183] The fiber is warped in a twist-free and glue-free manner, and the same yarn is used in the weft to weave a plain weave using a water jet loom.

[0184] The fabric was scoured using an open-width soaping scouring machine. After being immersed in a bath of 80°C warm water containing 0.5 g / l sodium alkylbenzene sulfonate and 0.5 g / l soda ash for one minute, it was then immersed in three separate baths of neutral, 80°C warm water for one minute each. To ensure stable conveyance of the scouring fabric, the warp tension was controlled at 0.22 N / cm using dancer rolls. The fabric was then dried with hot air at 110°C for three minutes.

[0185] In addition, the solvent-free addition type silicone resin was coated by air knife method to achieve 20g / m 2 At this time, the base fabric tension was set to 580 N / m in the warp direction and the blade thickness was selected to achieve the desired coating amount.

[0186] Next, the fabric was treated at 190°C for 2 minutes using a pin-and-stenter heat treatment machine, with the warp direction overfeed shrinkage set to 2.0% and the open width set to 0%. This yielded a coated base fabric for airbags. Based on the fabric density and constituent yarn fineness, the cover factor was 2145.

[0187] The physical properties of the resulting base fabric are shown in Table 1 below. Dimensional stability was achieved by varying the dimensional stability in the warp direction due to the greater rate of change in the warp direction. The increase in burning rate due to the wet heat treatment was suppressed. Furthermore, the burning rate was higher when the coated side was facing downward than when the fabric side was facing downward, but this level was maintained even after the wet heat treatment.

[0188] [Examples 2 to 4]

[0189] An airbag base fabric was obtained in the same manner as in Example 1 except that the temperature of the warm water bath was set to the temperature described in Table 1 below when the fabric was scoured using an open-width soaping scouring machine.

[0190] [Comparative Example 1]

[0191] An airbag base fabric was obtained in the same manner as in Example 1 except that the fabric was sequentially immersed in three layers of neutral 80°C warm water baths for 1 minute each and then dried at 110°C for 3 minutes during scouring using an open-width soaping scouring machine.

[0192] The increase in burning rate caused by the wet heat treatment was greater. In addition, based on the burning rate of the fabric side facing down, the burning rate of the coated side facing down was greater, and the difference was greater after the wet heat treatment.

[0193] [Examples 5 to 7, Comparative Example 2]

[0194] An airbag base fabric was obtained in the same manner as in Example 1 except that the overfeed shrinkage in the warp direction was set to the values ​​shown in Table 1 or 2 below in the vulcanization setting step using a pin tenter heat treatment machine after the knife coating.

[0195] In Comparative Example 2, the increase in burning speed due to the wet heat treatment was greater. In addition, based on the burning speed with the fabric side facing down, the burning speed with the coated side facing down was greater, and the difference after the wet heat treatment was greater.

[0196] [Example 8]

[0197] An airbag base fabric was obtained in the same manner as in Example 1, except that when the grey fabric was scoured using an open-width soaping scouring machine, it was immersed in a 60°C warm water bath containing 0.5 g / l of sodium alkylbenzene sulfonate and 0.5 g / l of soda ash for 1 minute, then immersed in three layers of neutral warm water baths at 60°C for 1 minute each, and then dried at 110°C for 3 minutes.

[0198] An airbag base fabric was obtained in the same manner as in Example 1, except that after the knife coating, a pin-plate tenter heat treatment machine was used to set the overfeed shrinkage in the warp direction to 1.5%, the open width to 0%, and the treatment was performed at 190°C for 2 minutes to obtain a coated base fabric for an airbag.

[0199] [Comparative Example 3]

[0200] An airbag base fabric was obtained in the same manner as in Example 8, except that the overfeed shrinkage in the warp direction was set to 0.5% in the vulcanization setting step using a pin tenter heat treatment machine after the knife coating.

[0201] The increase in burning rate caused by moist heat treatment is greater.

[0202] [Comparative Example 4]

[0203] When scouring the fabric using an open-width soaping scouring mill, the fabric was immersed in a 30°C warm water bath containing 0.5 g / l sodium alkylbenzene sulfonate and 0.5 g / l 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 step using a pin tenter heat treatment machine after knife coating, the overfeed shrinkage in the warp direction was set to 1.0%. A base fabric for an airbag was obtained in the same manner as in Example 1 except for the above.

[0204] [Example 9]

[0205] Without end-capping, polyamide 6·6 polymer was polymerized using hypophosphorous acid as a polymerization catalyst and copper iodide and potassium iodide as thermal stabilizers, output in the form of sheets, and further subjected to solid phase polymerization.

[0206] The polymer sheet was ejected and then stretched after being treated with a spinning oil containing an aliphatic synthetic ester to produce polyamide 6.6 fiber (470 dtex, 136 mm filament). The 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 cyclopentanone content in the fiber was 400 ppm.

[0207] This fiber was used to produce a base fabric for an airbag in the same manner as in Example 1. The increase in burning rate due to the wet heat treatment was suppressed. Furthermore, the burning rate was higher when the coated surface was facing downward, compared to the burning rate with the fabric surface facing downward, but this rate was maintained even after the wet heat treatment.

[0208] [Comparative Example 5]

[0209] An airbag base fabric was obtained in the same manner as in Example 10, except that no alkaline washing solution was used when scouring the grey fabric using an open-width soaping scouring machine, and the fabric was immersed in three layers of neutral warm water baths at 80°C for 1 minute each, followed by drying at 110°C for 3 minutes.

[0210] The increase in burning rate caused by moist heat treatment is large.

[0211] [Example 10]

[0212] In Example 9, during the polymerization of polyamide 6.6 polymer, hexamethylenediamine was added to an equimolar amount of the monomer salt to reduce the difference between the carboxyl and amino end group concentrations. The polymer sheet was then ejected and stretched after applying a spinning oil containing an aliphatic synthetic ester to produce polyamide 6.6 fiber (470 dtex, 136 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 millimole equivalents / kg of polymer. The cyclopentanone content in the fiber was 400 ppm. This fiber was used to produce a base fabric for an airbag in the same manner as in Example 1.

[0213] [Example 11]

[0214] An airbag base fabric was obtained in the same manner as in Example 1, except that the tension during fabric feeding was set to 1.5 N / cm when the fabric was scoured using an open-width soaping scouring machine.

[0215] [Example 12]

[0216] An airbag base fabric was obtained in the same manner as in Example 1, except that, when scouring the fabric using an open-width soaping scouring machine, the fabric was immersed in a warm water bath at 80°C containing 0.5 g / l of sodium alkylbenzene sulfonate and 0.5 g / l of soda ash for 1 minute, and then the hot air drying step was performed without immersing the fabric in a neutral warm water bath at 80°C.

[0217] 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.

[0218] [Table 1]

[0219]

[0220] [Table 2]

[0221]

[0222] Industrial applicability

[0223] The airbag base fabric of the present invention exhibits stable flame retardancy under environmental conditions, and the difference in flame retardancy between the coated front and back surfaces is minimal. Consequently, the base fabric can be used indiscriminately as an airbag cushion, even when coated on both sides. Furthermore, an airbag cushion design can be implemented that exposes the coated surface, while the inner surface is protected from environmental conditions by the coating film. The stable flame retardancy under even more stringent environmental conditions makes it suitable for use in airbags installed outside the cab.

Claims

1. A base fabric for an airbag, which is a multifilament fabric of polyamide, characterized in that: The fabric has a silicone film layer on at least one side thereof, The amount of the organic silicon film is 10 g / m 2 Above and 100g / m 2 the following, The content of cyclopentanones is 0 ppm or more and 250 ppm or less relative to the weight of the fabric. The larger shrinkage dimensional change rate of the airbag base fabric 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 The razor combing resistance after 400 hours in an environment of 85°C and 95% relative humidity is 350N or more.

2. The base fabric for an airbag according to claim 1, wherein: The amount of the organic silicon film is 15 g / m 2 Above 70g / m 2 the following.

3. The base fabric for an airbag according to claim 1, wherein: The amount of the organic silicon film is 15 g / m 2 Above 40g / m 2 the following.

4. The base fabric for an airbag according to claim 1, wherein The content of the cyclopentanones is 0 ppm or more and 150 ppm or less based on the weight of the fabric.

5. The base fabric for an airbag according to claim 1, wherein: The content of the cyclopentanones is 10 ppm or more and 50 ppm or less based on the weight of the fabric.

6. The base fabric for an air bag according to claim 1, wherein: The larger shrinkage dimensional change rate between the warp and weft directions before and after heating at 105° C. for 60 minutes is 0.1% or more and 1.0% or less.

7. The base fabric for an air bag according to claim 1, wherein: The larger shrinkage dimensional change rate between the warp and weft directions before and after heating at 105° C. for 60 minutes is 0.1% or more and 0.8% or less.

8. The base fabric for an air bag according to claim 1, wherein: The blade combing resistance is greater than or equal to 420N and less than or equal to 800N.

9. The base fabric for an air bag according to claim 1, wherein: The blade combing resistance is greater than or equal to 450N and less than or equal to 800N.

10. The base fabric for an air bag according to claim 1, wherein The blade combing resistance is greater than or equal to 470N and less than or equal to 800N.

11. The base fabric for an air bag according to claim 1, wherein The amount of the oil component contained in the fabric is 0% by weight or more and 0.04% by weight or less.

12. The base fabric for an air bag according to claim 1, wherein The amount of the oil component contained in the fabric is 0.005% by weight or more and 0.02% by weight or less. 13 . The base fabric for an air bag according to claim 1 , comprising 10 ppm to 300 ppm of phosphorus atoms based on the weight of the constituent yarns of the woven fabric. The base fabric for an air bag according to any one of claims 1 to 12, comprising 30 ppm to 200 ppm of phosphorus atoms based on the weight of the constituent yarns of the woven fabric. 15 . The base fabric for an air bag according to claim 1 , comprising 40 ppm to 150 ppm of phosphorus atoms based on the weight of the constituent yarns of the woven fabric.

16. The base fabric for an air bag according to any one of claims 1 to 12, wherein At the molecular chain ends of the polyamide, the amount of carboxylic acid ends is greater than the amount of amine ends, and the difference is 10 mmol equivalents / kg or more and 50 mmol equivalents / kg or less.

17. The base fabric for an air bag according to any one of claims 1 to 12, wherein In the FMVSS302 combustion test after 400 hours at 80°C and 95% humidity, the following 1) or 2) shall be met in both the warp and weft directions: 1) No matter which side of the base fabric is ignited, it will extinguish the fire. 2) The burning speeds of both the front and back surfaces are 100 mm / min or less, and the ratio of the burning speeds of the front and back surfaces is 1.0 to 3.

0.

18. A method for producing a polyamide multifilament fabric for an airbag base fabric, characterized in that: The method for manufacturing the base fabric for an airbag according to any one of claims 1 to 17 comprises the following steps: A step of melt-spinning polyamide to obtain a polyamide multifilament yarn having a cyclopentanone content of 0 ppm to 800 ppm; a step of using the obtained polyamide multifilament yarn as a weaving yarn to obtain a fabric; Scouring process using alkaline wash solution at temperatures above 35°C; Drying process; a step of coating at least one surface of the fabric with silicone to form a silicone film layer; and Vulcanization shaping process.

19. The method for manufacturing a base fabric for an air bag according to claim 18, wherein: In the scouring step, an alkaline washing solution is used at a temperature of 60° C. or higher.

20. The method for producing a base fabric for an air bag according to claim 18 or 19, wherein: In the scouring step, the smelting agent is treated in an alkali washing solution or a surfactant bath and then rinsed with water.

21. The method for producing a base fabric for an air bag according to claim 18 or 19, wherein: In the scouring step, the tension in the warp direction of the fabric during feeding is set to 0.08 N / cm or more and 0.8 N / cm or less.

22. The method for manufacturing a base fabric for an airbag according to claim 21, wherein: In the scouring step, the tension in the warp direction of the fabric during feeding is set to 0.08 N / cm or more and 0.5 N / cm or less.

23. The method for producing a base fabric for an air bag according to claim 18 or 19, wherein: In the vulcanization and setting step, the vulcanization and setting process is performed at a temperature of 160° C. or higher and with a warp overfeed of 0.8% or higher.

24. The method for producing a base fabric for an air bag according to claim 18 or 19, wherein: In the vulcanization setting step, vulcanization setting is performed at a temperature of 160° C. or higher and a warp overfeed of 1.0% or higher and 8.0% or lower.

25. The method for producing a base fabric for an air bag according to claim 18 or 19, wherein: In the vulcanization setting step, vulcanization setting is performed at a temperature of 160° C. or higher and a warp overfeed of 1.5% or higher and 8.0% or lower.

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