Base fabric for airbag and airbag using the same

Abstract

The present invention addresses the problem of providing an airbag base fabric that, while exhibiting improved woven fabric-versus-woven fabric rubbing characteristics, also satisfies the flame retardancy specified in FMVSS-302 (horizontal procedure). Provided as a solution is an airbag base fabric comprising a synthetic fiber woven fabric, wherein the synthetic fiber woven fabric has a coating layer on at least one side, the coating layer contains a thermoplastic resin and a polyether having a number-average molecular weight of 1,000 to 50,000, and the slip behavior (R) of the surface of the coating layer, as calculated with the formula (R) = (RDW+RDF) / 2, is not greater than 0.25.

Description

Technical Field

[0001] The present invention relates to a base fabric for an airbag and an airbag using the same.

Background Art

[0002] In recent years, airbags have been widely used as safety equipment for protecting passengers during vehicle collisions. Since an airbag is required to be stored in a limited space inside a vehicle such as inside a steering wheel, it is compressed in a folded state multiple times. On the other hand, although an airbag is rapidly deployed in a very short time during a vehicle collision, there has been a problem that the deployment is not smooth due to friction between the fabrics during this deployment, and in the worst case, the airbag is torn and its function cannot be exhibited. In response to this problem, in some airbag mounting locations, a fabric surface-coated with about several tens of grams of silicone rubber or the like, which is a thermosetting resin, has been used. However, such a so-called coated airbag using a surface-coated fabric has an advantage of being superior in frictional properties compared to a non-coated airbag without a surface coating. On the other hand, a large amount of thermosetting resin processing not only increases costs and requires a large amount of energy for processing, but also makes it difficult to separate the cured resin from the base fabric, making recycling difficult and having a major drawback in terms of environmental consideration. That is, it has become difficult for conventional coated airbags to meet the market needs in terms of environmental consideration.

[0003] In contrast, studies have been made to reduce the coating amount of coating agents such as silicone rubber (for example, Patent Document 1). However, when the coating amount is reduced in this way, there is a concern that the problem of frictional properties cannot be sufficiently improved. As a more serious problem, as described in Patent Document 1, when a small amount of silicone resin is applied, the flame retardancy is shown to decrease when the coating amount is less than 0.2 g / m 2 In the case of such a small amount of coating, it has been shown that the flame retardancy is lower than that in the case where there is no coating after coating. That is, it has been considered difficult to simultaneously achieve the problem of frictional properties and flame retardancy with a coated airbag having a low coating amount that is easy to recycle.

Prior Art Documents

Patent Documents

[0004] Patent Document 1 Japanese Patent Application Laid-Open No. 2001-271247 Summary of the Invention Problems to be Solved by the Invention

[0005] The present invention has been made in view of the problems of the prior art, and is a low coating amount coating technology using a thermoplastic resin that requires relatively little energy for processing. While improving the frictional properties between fabrics and achieving the flame retardancy specified in FMVSS-302 (horizontal method) simultaneously, it is an object of the present invention to provide a base fabric for airbags that highly balances environmental consideration and performance. Means for Solving the Problems

[0006] As a result of intensive studies, the present inventor has found that the above problems can be solved by the means shown below, and has completed the present invention.

[0007] 1. A base fabric for an airbag including a woven fabric made of synthetic fibers, wherein the woven fabric made of synthetic fibers has a coating layer on at least one side, the coating layer contains a thermoplastic resin and a polyether having a number average molecular weight of 1,000 to 50,000, and the sliding property (R) calculated by the following formula 1 on the surface of the coating layer is 0.25 or less: Sliding property (R) = (RDW + RDF) / 2 (Formula 1) Here, RDW is the average value of the coefficient of dynamic friction in the warp direction measured based on ISO8295, RDF is the average value of the coefficient of dynamic friction in the weft direction measured based on ISO8295, respectively. 2. The base fabric for an airbag according to 1., wherein the thermoplastic resin is a polyamide elastomer, and the polyether is at least one polyether represented by the following formula 2, and the coating layer contains 10 g / m 2 or less of the thermoplastic resin. HO―〔(R 1 ―O) a -(R 2 ―O) b ―(R 3 ―O) c 〕 n ―H (Formula 2) (In Formula 2, R 1 , R 2 , R 3 are alkylene units having 2 to 10 carbon atoms, and R 2 is different from both R 1 and R 3 , and R 1 may be the same as or different from R 3 . a, b, and c are integers satisfying a + b + c ≧ 2 (however, b is 0 or more, and at least one of a and c is 1 or more), and n is an integer of 1 or more). 3. The base fabric for airbag according to 1. or 2., wherein the molar ratio of ethylene units:propylene units of the polyether is 90:10 to 60:40. 4. The base fabric for airbag according to any one of 1. to 3., wherein the coating layer contains 0.1 to 10 g / m 2 . 5. The base fabric for airbag according to any one of 1. to 4., which has an endothermic peak in the temperature range of 50 to 70 °C in the heating DSC endothermic curve. 6. The base fabric for airbag according to any one of 1. to 5., wherein the flammability measured in accordance with FMVSS302 is 80 mm / min or less. 7. An airbag comprising the base fabric for airbag according to any one of 1. to 6.

Advantages of the Invention

[0008] When the base fabric for airbag of the present invention is used as an airbag, tearing due to rubbing between fabrics during deployment is less likely to occur. Furthermore, the energy required for processing can be reduced compared to conventional silicone-coated fabrics, and at the same time, the low flammability required for automotive interior materials can also be satisfied.

Modes for Carrying Out the Invention

[0009] The present invention will be described in detail below.

[0010] The base fabric in the present invention is manufactured by applying a resin composition containing a thermoplastic resin and a polyether to a woven fabric woven by a known method.

[0011] The resin to be used is preferably a thermoplastic resin typified by polyurethane resins, acrylic resins, polyester resins, and polyamide resins, and more preferably a thermoplastic elastomer resin. In the present invention, a thermoplastic polyamide elastomer can be particularly preferably used as a suitable resin. Hereinafter, the resin composition to be applied to the woven fabric, which is the base material described in the present invention, is a thermoplastic polyamide elastomer resin composition that is a mixture of a thermoplastic resin and a polyether described later, and means a resin in which an endothermic peak due to melting is observed in DSC measurement.

[0012] In the present invention, the polyamide elastomer is preferably a block copolymer containing a polyamide block and a polyether block, and particularly preferably a block copolymer having a structure represented by the following (Formula 3). [(Polyamide block)-X-(Polyether block)] n (Formula 3) (In the formula, X is -CO-NH- or -CO-O-, and n is an integer)

[0013] Examples of the components forming the polyamide block in the above formula (Formula 3) include lactams, aminocarboxylic acids, salts of diamines and dicarboxylic acids, and the like.

[0014] Examples of the aminocarboxylic acid include ω-aminocaproic acid, ω-aminoenanthic acid, ω-aminocaprylic acid, ω-aminopelargonic acid, ω-aminocapric acid, 6-aminocaproic acid, 7-aminoheptanoic acid, 9-aminononanoic acid, 11-aminoundecanoic acid, 12-aminododecanoic acid, etc. Among them, 11-aminoundecanoic acid and 12-aminododecanoic acid are preferred, and 12-aminododecanoic acid is more preferred. 12-Aminododecanoic acid has a long polymethylene chain among aminocarboxylic acids, and when it becomes a polyamide, the amide bond density becomes low. Therefore, it is the softest among aminocarboxylic acids and also excellent in impact resistance and low-temperature properties, etc.

[0015] Examples of the dicarboxylic acid include oxalic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, sebacic acid, terephthalic acid, isophthalic acid, suberic acid, azelaic acid, nonanedicarboxylic acid, decanedicarboxylic acid, tetradecanedicarboxylic acid, octadecanedicarboxylic acid, fumaric acid, phthalic acid, xylylenedicarboxylic acid, dimer acid (an unsaturated dicarboxylic acid having 36 carbon atoms synthesized from unsaturated fatty acids mainly composed of linoleic acid and oleic acid), etc. Among them, adipic acid is most commonly used.

[0016] Examples of the component forming the polyether block in the above (Formula 2) include diamines, etc.

[0017] Examples of the diamine include polyether diamines, etc.

[0018] The above polyamide elastomer can be a reaction product of a polyamide block-forming component and a polyether block-forming component obtained from poly(alkylene oxide) glycol and a carboxylic acid; a reaction product of a polyamide block-forming component and a poly(alkylene oxide) glycol with both ends aminated or carboxylated, and a polyether block-forming component obtained from a dicarboxylic acid or a diamine, etc.

[0019] The above-mentioned thermoplastic polyamide component can contain additives. Examples of such additives include antioxidants, lubricants, etc. In the present invention, the lubricant used as a surface modifier is the most important, and a thermoplastic polyamide elastomer resin composition containing the lubricant described below is preferred.

[0020] In the present invention, it is essential to add a surface modifier mainly composed of polyether. More specifically, this polyether is a copolymerized polyether composed of two or more kinds of alkylene units. This polyether can be effectively used as a lubricant for improving friction and wear characteristics, and its number average molecular weight is 1000 to 50000, preferably 10000 to 30000. If the number average molecular weight is less than 1000, sufficient film durability cannot be obtained, and if the number average molecular weight exceeds 50000, sufficient effects as a lubricant may not be obtained.

[0021] As the copolymerized polyether composed of two or more different kinds of alkylene units, a polyether compound represented by the following formula (Formula 2) can be preferably used. HO―〔(R 1 ―O) a -(R 2 ―O) b ―(R 3 ―O) c 〕 n ―H (Formula 2) (In Formula 2, R 1 , R 2 , R 3 are alkylene units having 2 to 10 carbon atoms, R 2 is different from both R 1 and R 3 , and R 1 may be the same as or different from R 3 . a, b, and c are integers satisfying a + b + c ≧ 2 (however, b is 0 or more, and at least one of a and c is 1 or more), and n is an integer of 1 or more)

[0022] In the above, n preferably represents a number that allows the number average molecular weight of the polyether compound to be between 1000 and 50000. However, the values of a, b, and c may differ for each repetition within the brackets. R 1 、R 2 、and R 3 include ethylene, propylene, trimethylene, tetramethylene, neopentylene, hexamethylene units, etc. As two or more different types of alkylene units, it is preferable to include ethylene units and propylene units. Furthermore, from the perspective of sliding properties, the ethylene unit:propylene unit (ethylene oxide unit:propylene oxide unit) is preferably 90:10 to 60:40 (molar ratio), more preferably 90:10 to 80:20 (molar ratio).

[0023] In the present invention, the number average molecular weight of the polyether and the molar ratio of ethylene unit:propylene unit are calculated by the following NMR method. For the measurement, a 1H-NMR measurement is performed at a resonance frequency of 600 MHz using an NMR apparatus "AVANCE NEO600" manufactured by BRUKER. The method for preparing the measurement solution is as follows: after drying the sample, distilled water is added and ultrasonic treatment is performed. After centrifuging the ultrasonic-treated solution, the supernatant is collected and dried. The dried product is dissolved in deuterated chloroform / trifluoroacetic acid (85 / 15 vol ratio) and left standing for 3 days. After standing, the sample is dried, and the dried product is dissolved in deuterated chloroform, and the measurement is performed at room temperature with an acquisition time of 4 seconds, a waiting time of 1 second, and an integration number of 64 times.

[0024] First, the molar ratio of ethylene unit:propylene unit is calculated from the respective amounts of substances. The quantification of the amounts of substances is performed as follows. As an example, the calculation method in the case of a copolymer of ethylene oxide and propylene oxide is described. It is calculated as a linear copolymer polyether.

[0025] The ethylene unit is calculated according to the following formula from the peak integration value of the ethylene group at 3.2 to 3.9 ppm. Also, the propylene unit is calculated from the total integration value of the methyl group at 1.1 to 1.2 ppm, the secondary terminal group at 5.1 to 5.4 ppm, and the primary terminal group at 4.3 to 4.4 ppm. When the integration value of the ethylene group of the ethylene unit is A1, the peak integration value of the terminal ethylene group at 4.5 to 4.6 ppm is A2, the integration value of the methyl group of the propylene unit is B1, the integration value of the secondary terminal group is B2, and the integration value of the primary terminal group is B3, the amounts of substance of the ethylene unit and the propylene unit are calculated and obtained respectively according to the following formula. Amount of substance of ethylene unit (mol) = (A1 + A2) / 4 Amount of substance of propylene unit (mol) = (B1 + B2 + B3) / 3

[0026] Also, the molar ratio of the ethylene unit to the propylene unit is calculated according to the following formula. Molar ratio of ethylene unit:propylene unit = Amount of substance of ethylene unit:Amount of substance of propylene unit

[0027] Subsequently, the number average molecular weight (Mn) is calculated and obtained from the amounts of substance of each unit obtained, according to the following formula, for the amount of terminal ethylene groups and the amount of terminal propylene groups respectively.

[0028] Amount of terminal ethylene groups (eq / t) = A2 / 2 × 1000000 / (44 × Amount of substance of ethylene unit + 58 × Amount of substance of propylene unit) Amount of secondary terminal propylene groups (eq / t) = A2 / 1 × 1000000 / (44 × Amount of substance of ethylene unit + 58 × Amount of substance of propylene unit) Amount of primary terminal propylene groups (eq / t) = A3 / 2 × 1000000 / (44 × Amount of substance of ethylene unit + 58 × Amount of substance of propylene unit) Number average molecular weight (Mn) = 2 × 1000000 / (Amount of terminal ethylene groups + Amount of secondary terminal propylene groups + Amount of primary terminal propylene groups)

[0029] Specifically, for example, copolymers of ethylene oxide and propylene oxide, ethylene oxide addition polymers of poly(propylene oxide) glycol, copolymers of ethylene oxide and tetrahydrofuran, copolymers of propylene oxide and tetrahydrofuran, ethylene oxide addition polymers of copolymers of propylene oxide and tetrahydrofuran, ethylene oxide addition polymers of poly(tetramethylene oxide) glycol, copolymers of neopentyl oxide and ethylene oxide, copolymers of neopentyl oxide and propylene oxide, ethylene oxide addition polymers of copolymers of neopentyl oxide and propylene oxide, copolymers of neopentyl oxide and tetrahydrofuran, ethylene oxide addition polymers of copolymers of neopentyl oxide and tetrahydrofuran, ethylene oxide addition polymers of poly(neopentyl oxide) glycol, etc. can be cited as specific examples. Among them, ethylene oxide addition polymers of poly(propylene oxide) glycol are preferred. The blending amount (content) of these copolymer polyethers can vary depending on the affinity with the polyamide elastomer used or the required properties of the finally obtained composition. These compounds can be used in combination of two or more kinds, or in combination with other lubricant components.

[0030] The blending amount (content) of the copolymer polyether composed of two or more kinds of alkylene units is preferably 0.1 part by mass to 20 parts by mass, preferably 1 part by mass to 15 parts by mass, and more preferably 5 parts by mass to 12 parts by mass with respect to 100 parts by mass of the resin composition to be applied. If it is less than 0.1 part by mass, sufficient effects on the sliding properties may not be obtained. On the other hand, if it exceeds 20 parts by mass, there is a concern that the melt viscosity of the polyamide elastomer will significantly decrease and emulsification will become difficult.

[0031] The thermoplastic polyamide elastomer resin composition preferably has the following properties.

[0032] 1) Melting point: 125 to 200 °C, preferably 130 to 180 °C, more preferably 135 to 160 °C. If the melting point of the thermoplastic polyamide elastomer is high, it becomes difficult to ensure the flexibility of the base fabric for the airbag due to the increase in rigidity associated with the increase in the relative crystallinity of the elastomer. That is, it becomes difficult to fold the bag, and there is a risk that it will be difficult to ensure the required deployment performance (smooth deployability as the gas flows into the bag) when the bag is deployed. Conversely, if the melting point of the thermoplastic polyamide elastomer is too low, that is, close to the upper limit temperature of the vehicle use environment (usually 120 °C), there is a risk that the form of the film itself will collapse and it will be difficult to ensure the sliding characteristics.

[0033] 2) Tensile breaking strength (JIS K 6251): Desirably 10 MPa or more. If the tensile breaking strength is too low, cracks may occur in the film due to the stress when the bag is deployed, and it may be difficult to ensure the sliding characteristics.

[0034] 3) Tensile elongation at break (JIS K 6251): Desirably 200% or more. If the tensile elongation at break is too low, it becomes difficult to ensure the flexibility of the base fabric for the airbag, and cracks may occur in the film due to the stress when the bag is deployed, and it may be difficult to ensure the sliding characteristics.

[0035] 4) Tensile modulus (JIS K 6251): Desirably 100 MPa. If the flexural modulus is too high, it becomes difficult to ensure the flexibility of the base fabric for the airbag. Although a lower flexural modulus is desirable, usually, the practical upper and lower limits are desirably 10 MPa.

[0036] 5) Hardness (Shore D): Desirably 10 to 50. If the hardness is too low, the durability of the film decreases, and cracks may occur in the film due to the stress when the bag is deployed, and it may be difficult to ensure the sliding characteristics. Also, if the hardness is too high, it becomes difficult to ensure the flexibility of the base fabric for the airbag.

[0037] As the thermoplastic polyamide elastomer resin composition, a resin composition dispersed in water is preferred because the coating amount can be reduced. The resin dispersed in water here refers not only to those that dissolve in water, but also to those that are dispersed in a colloidal state or an emulsion state, and there is no particular limitation. The particle size of the thermoplastic polyamide elastomer resin composition dispersed in the emulsion is usually appropriately selected from the range of 0.05 to 10 μm, preferably 0.2 to 8 μm, and more preferably 0.5 to 5 μm. As the coating method using the emulsion or solution of the thermoplastic polyamide elastomer, when performing single-sided coating, for example, known methods such as knife coating, roller coating, brush coating, spray coating, and foam coating can be used. This is because it is easy to form a thin layer of elastomer coating film on one side of the woven fabric made of synthetic fibers while performing surface impregnation on the woven fabric and allowing the thermoplastic polyamide elastomer to penetrate into the one-sided concave portions between the weave gaps of the fabric. As a result, it is easy to ensure the flexibility of the base fabric for airbags. Knife coating and roller coating are suitable for coating resins with relatively high viscosities. Since the resin composition dispersed in water to be coated in the present invention has a relatively low viscosity, it is preferable to apply spray coating or foam coating, which is a technique for forming a coating layer using foam.

[0038] The base fabric for airbags of the present invention has a coating layer on at least one side of the woven fabric made of synthetic fibers, and the weight per unit area of the coating layer is 0.1 g / m 2 or more and 10 g / m 2 or less, preferably more preferably 0.15 g / m 2 or more and 4.5 g / m 2 or less, and even more preferably 0.2 g / m 2 or more and 4 g / m 2 or less. When the weight per unit area of the coating layer is 0.1 g / m 2 or less, sufficient sliding properties cannot be exhibited. On the other hand, when the weight per unit area of the coating layer is 10 g / m 2In the above case, the stiffness of the base fabric for airbag is too high, making it difficult to be used as an airbag. Furthermore, it becomes difficult to separate the fabric from the coating layer, deteriorating the recyclability.

[0039] The base fabric for airbag of the present invention has a slipperiness property (R) calculated by the following formula 1 of 0.25 or less, preferably 0.22 or less, and more preferably 0.20 or less. If the slipperiness property (R) is 0.25 or less, it is considered that tearing due to rubbing between fabrics during high-speed deployment of the airbag can be suppressed. Slipperiness property (R) = (RDW + RDF) / 2 (Formula 1) Here RDW represents the average value of the coefficient of kinetic friction in the warp direction measured based on ISO8295, RDF represents the average value of the coefficient of kinetic friction in the weft direction measured based on ISO8295, Each is shown.

[0040] In the present invention, the slipperiness property (R) is measured in accordance with ISO8295. Specifically, two test pieces of about 80 mm × 200 mm are taken from a sample after being stored for 1 day in an environment of a temperature of 20°C and a humidity of 65% RH. Next, a load of 200 gf is applied with the resin-applied surfaces facing each other, and measurement is performed at a speed of 100 mm / min using a tensile testing machine RTG-1250 manufactured by A&D Company, Limited. The measurement is performed in an environment of a temperature of 20°C and a humidity of 65% RH. Test pieces in the warp direction and the weft direction are taken at five different locations, and the average value of the coefficient of kinetic friction for each is calculated. The slipperiness property (R) is calculated from Formula 1 based on the obtained coefficient of friction in each direction.

[0041] The base fabric for airbag of the present invention has an endothermic peak in the temperature range of 50 to 70°C in the heating DSC endothermic curve. Preferably it is 52 to 68°C, and more preferably 55 to 65°C. The base fabric for airbag having an endothermic peak in this range can exert a sufficient effect on the slipperiness property because the copolymerized polyether contained in the thermoplastic polyamide elastomer resin composition has a suitable number average molecular weight and a molar ratio of ethylene units to propylene units.

[0042] In the present invention, the endothermic peak in the heating DSC endothermic curve is calculated by the following method. Approximately 5 mg of the sample was cut out in the shape of a pan and placed in an aluminum pan with the resin-applied surface facing down. Measurement was carried out in a nitrogen atmosphere using a differential scanning calorimeter DSC-2500 manufactured by TA Instruments. The temperature was raised from -30°C to 200°C at a rate of 20°C / min (referred to as the first heating run), cooled from -30°C to 20°C / min (referred to as the first cooling run), and then heated from 200°C to 20°C / min (referred to as the second heating run). The endothermic peak temperature was calculated from the second heating run of the obtained endothermic curve.

[0043] In the flammability test of the base fabric for airbags of the present invention, 80 mm / min or less is preferable, more preferably 50 mm / min or less, still more preferably 40 mm or less, and most preferably self-extinguishing. Generally, in a crosslinked type coated fabric such as silicone, if the coating amount of silicone is less than 25 g / m 2 If it is not the above, it will not be self-digestible, and if the coating amount is less than that, self-extinguishing property is less likely to occur. Especially when it is less than 10 g / m 2 it becomes difficult to achieve self-extinguishing property. Since the water-dispersible resin used in the present invention is thermoplastic, it is preferable because it tends to exhibit self-extinguishing property in the flammability test.

[0044] In the present invention, the flammability was measured in accordance with the horizontal method of the FMVSS No. 302 combustion test for automotive interior materials. The resin-applied surface was ignited facing down, and the warp and weft n = 5 each were measured, and the maximum value (mm / min) of the combustion rate was taken as the flammability. Those that did not reach the scale line with a combustion distance of 38 mm were regarded as self-extinguishing (self-extinguishing property).

[0045] The base fabric for airbag of the present invention is a woven fabric composed of synthetic fiber multifilaments. The total fineness of the synthetic fiber multifilaments (unwoven yarns) constituting the base fabric for airbag is preferably 100 to 700 dtex, more preferably 200 to 600 dtex. If the total fineness is 100 dtex or more, it is not necessary to excessively increase the weaving density, so that an excessive increase in the binding force between the warp and weft yarns can be suppressed, and it is easy to keep the storability in the airbag module within an appropriate range. Also, if the total fineness is 700 dtex or less, it is easy to suppress an excessive increase in the rigidity of the woven fabric constituent yarns themselves. If the total fineness of the synthetic fiber multifilaments is 100 to 700 dtex, it is moderately flexible, and thus it is easy to obtain a base fabric for airbag having good storability in the module, which is preferable.

[0046] In the present invention, the total fineness of the synthetic fiber multifilaments (unwoven yarns) constituting the base fabric for airbag is determined as follows.

[0047] The warp and weft of the base fabric obtained through the dry finishing process are unwoven respectively and measured in accordance with JIS L1013(2010)8.3.1. Specifically, a sample with an exact length of 90 cm is taken under an initial load, the absolutely dry mass is weighed, and the fineness (dtex) is calculated by the following formula, and the average value of five times is taken as the total fineness. F0 = 1000×m / 0.9×(100 + R0) / 100 F0: Fineness (dtex) m: Absolutely dry mass of the sample (g) R0: Official moisture regain (%)

[0048] The base fabric for airbag of the present invention preferably has a weaving density of 40 threads / 2.54 cm or more, more preferably 45 threads / 2.54 cm or more, in both the warp direction and the weft direction. For the base fabric for airbag woven at the above-mentioned crimp ratio, if the weaving density is 45 threads / 2.54 cm or more, gaps are less likely to occur between the fibers, and it is easy to suppress the deterioration of the sliding characteristics.

[0049] In the present invention, the fabric density is measured according to JIS L1096 (2010) 8.6.1. Specifically, the sample is placed on a flat table, and after removing unnatural wrinkles and tension, the number of warp and weft threads in a 2.54 cm section is counted at five different locations, and the average value of each is calculated for the unit length to obtain the fabric density.

[0050] The base fabric for airbag of the present invention preferably has a basis weight of 300 g / m 2 or less. More preferably, it is 250 g / m 2 or less. Within such a range, the base fabric for airbag is easily weight-reduced, and furthermore, the storability in the module is improved.

[0051] The lower limit of the basis weight of the polyester base fabric for airbag of the present invention is not particularly limited as long as it can ensure satisfactory air permeability in the use of the airbag, but if it is 180 g / m 2 or more, it is considered to have air permeability that can be used as an airbag.

[0052] In the present invention, the basis weight is measured according to JIS L 1096 8.3. Two test pieces of about 200 mm × 200 mm are taken from the sample, and the absolute dry mass (g) of each is weighed, and the mass per 1 m 2 (g / m 2 ) is obtained, and the average value is calculated to obtain the basis weight.

[0053] From the viewpoint of mechanical properties, the tensile strength of the base fabric for airbag of the present invention is preferably 600 N / cm or more, more preferably 650 N / cm or more. Also, regarding the upper limit of the tensile strength, there is no particular limitation, but from the relationship between the total fineness of the synthetic fiber multifilament used, the tensile strength, and the fabric density of the base fabric for airbag, it is preferably 1000 N / cm or less, more preferably 900 N / cm or less.

[0054] In the present invention, the tensile strength of the base fabric is measured in accordance with JIS L1096 (2010) 8.12.1. Specifically, the test piece is grasped by a tensile testing machine under an initial load, and the test is conducted under the conditions of a test piece width of 50 mm, a gripping interval of 200 mm, and a tensile speed of 200 m / min, and the strength (N) at the time of cutting is measured. However, those that are cut within 10 mm from the gripping point or are abnormally cut are excluded.

[0055] The base fabric for an airbag of the present invention preferably has a stiffness of 80 to 110 mm, more preferably 90 to 105 mm, on average in the warp and weft directions as determined by the JIS L1096 cantilever method. Although a smaller stiffness is preferable, considering the stiffness of the fabric itself as the base material, 80 mm or more can be achieved. On the other hand, if the stiffness is 110 mm or less, the base fabric for an airbag is less likely to become excessively hard, wrinkles are likely to form, and the storage property in the module is improved.

[0056] The measurement of the stiffness by JIS L 1096 8.21.1 A (cantilever method) in the present invention is specifically carried out as follows. Five test pieces of approximately 20 mm × approximately 150 mm are taken from the sample in the longitudinal direction and the transverse direction, respectively, and the short side of the test piece is placed along the scale baseline on a smooth horizontal table with a 45° inclined surface at one end. Next, the test piece is gently slid in the direction of the inclined surface by an appropriate method, and when the center point of one end of the test piece comes into contact with the inclined surface, the position of the other end is read by the scale. The stiffness is indicated by the length (mm) that the test piece has moved, and the front and back of each of the five pieces are measured.

[0057] In the present invention, considering the values of the stiffness and the slippage resistance defined in the present invention, the cover factor (CF) of the base fabric is preferably 2150 to 2600, more preferably 2200 to 2400. Note that CF is calculated by the following formula. CF = (A × 0.9) 1 / 2 × (W1) + (B × 0.9) 1 / 2 × (W2) In the formula, A and B represent the thickness (dtex) of the warp and weft yarns, and W1 and W2 represent the warp and weft densities (threads / 2.54 cm).

[0058] The material of the synthetic fiber multifilament constituting the base fabric for airbag of the present invention is not particularly limited and can be widely selected. Considering economy and satisfying the above-described characteristics, multifilaments made of polyamide-based resins such as nylon 6, nylon 66, and nylon 46, and polyester-based resins mainly composed of polyethylene terephthalate are each preferable. Among these, multifilaments made of nylon 66 or nylon 46 are particularly preferable from the viewpoints of heat capacity and flexibility.

[0059] In addition, in this specification, the "synthetic fiber multifilament constituting the base fabric for airbag of the present invention" refers to the constituent yarns, that is, the fibers obtained by unwinding the base fabric for airbag of the present invention, and is distinguished from the synthetic fiber multifilament as the raw yarn used for manufacturing the base fabric for airbag of the present invention. Specifically, the characteristics of the constituent yarns may change from those of the raw yarns in the manufacturing process of the base fabric for airbag. Even in this case, other characteristics are common between the constituent yarns and the raw yarns.

[0060] The synthetic fiber multifilament constituting the base fabric for airbag of the present invention may contain various additives usually used for improving productivity or characteristics in the manufacturing process of the raw yarns or the manufacturing process of the base fabric. The synthetic fiber multifilament constituting the base fabric for airbag of the present invention may contain, for example, at least one selected from the group consisting of heat stabilizers, antioxidants, light stabilizers, lubricants, antistatic agents, plasticizers, thickeners, pigments, and flame retardants.

[0061] The tensile strength of the synthetic fiber multifilament constituting the base fabric for airbag of the present invention is preferably high in terms of mechanical properties. Specifically, it is preferably 6.5 cN / dtex or more, more preferably 7.0 cN / dtex or more, and still more preferably 7.5 cN / dtex or more. There is no particular limitation on the upper limit of the tensile strength. However, when nylon 66 fibers are used, if the tensile strength is 7.5 cN / dtex or more, the effects of the present invention can be exhibited.

[0062] In the present invention, the tensile strength of the synthetic fiber multifilament is measured in accordance with JIS L1013(2010) 8.5.1. Specifically, with the sample in a loosely stretched state, it is attached to the gripping part of a tensile testing machine, and the load at the time when the sample is cut is measured.

[0063] The elongation at break of the synthetic fiber multifilament constituting the base fabric for airbags of the present invention is preferably 20% or more. The elongation in the warp direction and the weft direction of the base fabric for airbags is different. When the elongation at break of the synthetic fiber is 20% or more, stress concentration on parts with less elongation during airbag deployment is less likely to occur, and the internal pressure can be maintained within a predetermined range when the airbag is deployed. The elongation at break of the multifilament is more preferably 23% or more, and even more preferably 25% or more. Although a relatively high elongation at break is preferable, in practical use, it is preferably 35% or less, and more preferably 30% or less.

[0064] In the present invention, the elongation at break of the synthetic fiber multifilament is measured in accordance with JIS L1013(2010) 8.5.1. Specifically, with the sample in a loosely stretched state, it is attached to the gripping part of a tensile testing machine, and the elongation at the time when the sample is cut is measured.

[0065] The fineness of the single filament constituting the synthetic fiber multifilament constituting the base fabric for airbags of the present invention is not particularly limited, but in terms of ensuring spinning operability and also ensuring the storability of the airbag, it is preferably 5.0 dtex or less. Further, the fineness of the single filament is preferably 2.0 dtex or more, and more preferably 2.4 dtex or more.

[0066] The tensile strength of the synthetic fiber multifilament as the raw yarn used in the production of the base fabric for airbags of the present invention is preferably large from the viewpoint of mechanical properties, preferably 7.0 cN / dtex or more, more preferably 7.5 cN / dtex or more, and still more preferably 8.0 cN / dtex or more. Regarding the upper limit of the tensile strength, although there is no particular limitation, when nylon 66 fiber is used, it is preferably 9.0 cN / dtex or less from the viewpoint of raw yarn production.

[0067] The elongation at break of the synthetic fiber multifilament as the raw yarn used in the production of the base fabric for airbags of the present invention is preferably 15% or more, more preferably 18%, and still more preferably 20% or more. When the elongation at break of the multifilament is 15% or more, in the base fabric after weaving, stress concentration on the portion with less elongation during airbag deployment is less likely to occur, and a predetermined deployment internal pressure can be maintained. Also, although the elongation at break is preferably relatively high, it is preferably 30% or less, and more preferably 25% or less from the viewpoint of raw yarn production.

[0068] In the present invention, the tensile strength and elongation at break of the raw yarn are measured according to JIS L1013(2010)8.5.1. Specifically, in a state where the sample is loosely stretched, it is attached to the gripping part of the tensile tester, and the load and elongation when the sample is cut are measured.

[0069] The synthetic fiber multifilament constituting the base fabric for airbags of the present invention is preferably a substantially untwisted yarn or a slack-twisted yarn, and more preferably an untwisted yarn. When the synthetic fiber multifilament is a substantially untwisted yarn or a slack-twisted yarn, the spread of the single filaments constituting the synthetic fiber is not inhibited, and the air permeability of the base fabric for airbags can be lowered.

[0070] By weaving the above-mentioned original yarns, the base fabric for airbags of the present invention can be obtained. To produce a woven fabric using the above synthetic fiber multifilaments, the synthetic fiber multifilaments can be directly used as warp and weft yarns and woven by a normal method. At this time, it is preferable not to twist or size the yarns. This is because by omitting this step, the single yarns of the warp and weft constituting the woven fabric are more likely to spread, and low air permeability can be achieved.

[0071] Examples of the weave structure of the base fabric for airbags of the present invention include plain weave, twill weave, crepe weave, and their modified weaves. Among them, plain weave is preferable because of its excellent mechanical properties.

[0072] The airbag using the base fabric for airbags of the present invention is preferably used, for example, for driver's seat airbags, passenger seat airbags, curtain airbags, side airbags, knee airbags, seat airbags, reinforcing fabrics, etc. Therefore, these products are also included in the scope of the present invention. As the airbag using the base fabric for airbags of the present invention, since the base fabric for airbags of the present invention is less likely to shift after sewing when cutting a part that is long in the weft direction, an airbag that particularly requires a part that is long in the weft direction is preferable. Specifically, a side curtain airbag is preferable. In addition, since the base fabric for airbags of the present invention is particularly excellent in storage properties, an airbag that particularly requires storage properties is also preferable. Specifically, a driver's seat airbag, a passenger seat airbag, and a curtain airbag are preferable. As the airbag using the base fabric for airbags of the present invention, an airbag that requires both a part that is long in the weft direction and storage properties is more preferable. Specifically, a side curtain airbag is more preferable.

Examples

[0073] Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited by the following examples, and it is of course possible to appropriately modify and implement it within the range that conforms to the gist of the foregoing and following descriptions, and all of them are included in the technical scope of the present invention.

[0074] In this example, a thermoplastic polyamide elastomer resin having the following characteristics was used (denoted as PA12 in Table 1). 1) Melting point: 140 °C 2) Tensile breaking strength: 20 MPa 3) Elongation at break: 1000% 4) Tensile modulus: 30 MPa 5) Hardness: 40

[0075] A thermoplastic polyamide elastomer resin composition containing various copolymer polyethers in the above resin was applied to a fabric for preparation (see Table 1). The coating amounts are all based on dry weight.

[0076] (Example 1) Polyester multifilament raw yarns with a fineness of 555 dtex / 144f (the single-filament cross-section is round) were used for the warp and weft, and plain weaving was carried out using a water jet loom at a weaving density of 51.0 ends / 2.54 cm for the warp and 50.0 picks / 2.54 cm for the weft. After that, without drying, it was passed through a hot water shrinkage tank at 98 °C, and then, using a suction drum dryer, the drying process was passed through so that the surface temperature of the base fabric at the dryer outlet (measured with a non-contact thermometer) was 150 °C. Next, on one side of the above fabric, a thermoplastic polyamide elastomer resin composition containing 12 wt% of a copolymer polyether with a number average molecular weight of 14000 and a molar ratio of ethylene units:propylene units of 9:1 was applied by spray coating at a coating amount of 3 g / m 2 so as to be. Further, the treatment was carried out so that the surface temperature of the base fabric at the heat treatment machine outlet (measured with a non-contact thermometer) was 160 °C, and a base fabric for airbag was obtained. The physical properties, etc. of the obtained base fabric are shown in Table 1.

[0077] (Example 2) A thermoplastic polyamide elastomer resin composition containing 11 wt% of a copolymer polyether with a number average molecular weight of 28,000 and a molar ratio of ethylene units:propylene units of 9:1 was used. An airbag base fabric was obtained under the same conditions as in Example 1, except that it was woven in a plain weave using a water jet loom with a warp density of 50.0 ends / 2.54 cm and a weft density of 51.0 picks / 2.54 cm. The physical properties of the obtained base fabric are shown in Table 1.

[0078] (Example 3) A thermoplastic polyamide elastomer resin composition containing 13 wt% of a copolymer polyether with a number average molecular weight of 14,000 and a molar ratio of ethylene units:propylene units of 7:3 was used. An airbag base fabric was obtained under the same conditions as in Example 1, except that it was woven in a plain weave using a water jet loom with a warp and weft density of 51.0 ends / picks / 2.54 cm. The physical properties of the obtained base fabric are shown in Table 1.

[0079] (Example 4) An airbag base fabric was obtained under the same conditions as in Example 1, except that the thermoplastic polyamide elastomer resin composition was applied by a spray coating method to a coating amount of 1 g / m 2 . The physical properties of the obtained base fabric are shown in Table 1.

[0080] (Example 5) An airbag base fabric was obtained under the same conditions as in Example 1, except that nylon 66 multifilament raw yarns with a fineness of 470 dtex / 144 f (the single fiber cross-section is round) were used for the warp and weft, and it was woven in a plain weave using a water jet loom with a warp density of 52.0 ends / 2.54 cm and a weft density of 54.0 picks / 2.54 cm. The physical properties of the obtained base fabric are shown in Table 1.

[0081] (Comparative Example 1) Using polyester multifilament raw yarn with a fineness of 555 dtex / 144f for the warp and weft (the single-filament cross-section is round), woven in a plain weave using a water jet loom at a weaving density of 51.0 ends / 2.54 cm for the warp and 50.0 picks / 2.54 cm for the weft. After weaving, it was passed through a hot water shrinkage tank at 98 °C without drying, and then through a suction drum dryer, and passed through the drying process so that the surface temperature of the base fabric at the dryer outlet (measured with a non-contact thermometer) reached 150 °C. Next, on one side of the above-mentioned fabric, a solvent-free silicone resin was applied by spray coating so that the coating amount was 3 g / m 2 was achieved. Further, it was cured so that the surface temperature of the base fabric at the heat treatment machine outlet (measured with a non-contact thermometer) reached 200 °C, and a base fabric for airbag was obtained. The physical properties of the obtained base fabric are shown in Table 1.

[0082] (Comparative Example 2) Using polyester multifilament raw yarn with a fineness of 555 dtex / 144f for the warp and weft (the single-filament cross-section is round), woven in a plain weave using a water jet loom at a weaving density of 50.0 ends / 2.54 cm for the warp and 51.0 picks / 2.54 cm for the weft. After weaving, it was passed through a hot water shrinkage tank at 98 °C without drying, and then through a suction drum dryer, and passed through the drying process so that the surface temperature of the base fabric at the dryer outlet (measured with a non-contact thermometer) reached 150 °C. Next, without applying the resin composition, it was treated so that the surface temperature of the base fabric at the heat treatment machine outlet (measured with a non-contact thermometer) reached 160 °C, and a base fabric for airbag was obtained. The physical properties of the obtained base fabric are shown in Table 1.

[0083] (Comparative Example 3) Using polyester multifilament raw yarn with a fineness of 555 dtex / 144f for the warp and weft (the single-filament cross-section is round), woven in a plain weave using a water jet loom at a weaving density of 51.0 ends / 2.54 cm for both the warp and weft. After weaving, it was passed through a hot water shrinkage tank at 98 °C without drying, and then through a suction drum dryer, and passed through the drying process so that the surface temperature of the base fabric at the dryer outlet (measured with a non-contact thermometer) reached 150 °C. Next, a thermoplastic polyamide elastomer resin not containing a copolymerized polyether was applied to one side of the fabric by a spray coating method in an amount of 3 g / m 2 and the treatment was carried out so that the surface temperature of the base fabric at the outlet of the heat treatment machine (measured with a non-contact thermometer) became 160°C, thereby obtaining a base fabric for an airbag. The physical properties of the obtained base fabric are shown in Table 1.

[0084] (Comparative Example 4) An airbag base fabric was obtained under the same conditions as in Example 1, except that a thermoplastic polyamide elastomer resin composition containing 10 wt% of a copolymerized polyether having a number average molecular weight of 84,000 and a molar ratio of ethylene unit:propylene unit of 9:1 was used. The physical properties of the obtained base fabric are shown in Table 1.

[0085] (Comparative Example 5) An airbag base fabric was obtained under the same conditions as in Example 1, except that a thermoplastic polyamide elastomer resin composition containing 11 wt% of a copolymerized polyether having a number average molecular weight of 14,000 and a molar ratio of ethylene unit:propylene unit of 5:5 was used. The physical properties of the obtained base fabric are shown in Table 1.

[0086] (Comparative Example 6) An airbag base fabric was obtained under the same conditions as in Example 1, except that the thermoplastic polyamide elastomer resin composition was applied by a knife air method in an amount of 25 g / m 2 and the treatment was carried out so that the amount became 25 g / m. The physical properties of the obtained base fabric are shown in Table 1.

[0087]

Table 1

[0088] The airbag base fabrics of Examples 1 to 5 had good sliding properties. These base fabrics also had good results in terms of flammability. The present invention, which has such excellent sliding properties and excellent flame retardancy, is useful as a base fabric for airbags.

[0089] The embodiments and examples of the present invention have been described above. However, the embodiments and examples disclosed this time are illustrative in all respects and not restrictive. The scope of the present invention is indicated by the claims, and all modifications within the meaning and scope equivalent to the claims are included.

[0090] According to the present invention, by applying a thermoplastic resin that has a low coating amount and relatively low energy required for processing, the rubbing property between fabrics is improved, and furthermore, a base fabric for airbags that also satisfies the flame retardancy specified in FMVSS-302 (horizontal method) can be obtained, which makes a great contribution to the industrial world.

Claims

Claim 1 A base fabric for an airbag comprising a synthetic fiber woven fabric, wherein the synthetic fiber woven fabric has a coating layer on at least one side, and the coating layer contains a thermoplastic resin (excluding polyethers having a number average molecular weight of 1,000 to 50,000) and a polyether having a number average molecular weight of 1,000 to 50,000, and the sliding property (R) calculated by the following formula 1 on the surface of the coating layer is 0.25 or less: A base fabric for an airbag. Sliding property (R) = (RDW + RDF) / 2 (Formula 1) Here,[[]]END]] RDW is the average value of the dynamic friction coefficient in the warp direction measured based on ISO8295, RDF is the average value of the dynamic friction coefficient in the weft direction measured based on ISO8295, respectively. Claim 2 The thermoplastic resin is a polyamide elastomer, and the polyether is at least one polyether represented by the following formula 2, and the coating layer contains 10 g / m of the thermoplastic resin ２ The base fabric for an airbag according to claim 1, containing the following: HO—〔(R １ —O) ａ -(R ２ —O) ｂ —(R ３ —O) ｃ 〕 ｎ —H (Formula 2) (In Formula 2, R １ , R ２ , R ３ is an alkylene unit having 2 to 10 carbon atoms, and R ２ is different from both R １ and R ３ , and R １ may be the same as or different from R ３ . a, b, and c are integers satisfying a + b + c ≧ 2 (however, b is 0 or more, and at least one of a and c is 1 or more), and n is an integer of 1 or more). Claim 3 The base fabric for an airbag according to claim 1 or 2, wherein the polyether contains ethylene oxide units and propylene oxide units, and the molar ratio of ethylene oxide units: propylene oxide units is 90:10 to 60:

40. Claim 4 The coating layer contains 0.1 to 10 g / m ２ The base fabric for an airbag according to claim 1 or 2. Claim 5 The base fabric for an airbag according to claim 1 or 2, which has an endothermic peak in the temperature range of 50 to 70 °C in the heating DSC endothermic curve. Claim 6 The base fabric for an airbag according to claim 1 or 2, wherein the flammability measured in accordance with FMVSS302 is 80 mm / min or less. Claim 7 An airbag comprising the base fabric for an airbag according to claim 1 or 2.

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