Base fabric for airbag

Abstract

A base fabric for an airbag according to an embodiment comprises a base fabric body and a resin layer provided on at least one side surface of the base fabric body, the base fabric for an airbag being characterized in that the base fabric body is made of polyethylene terephthalate fibers, the resin layer is made of a polyester resin, the amount of the polyester resin on the one side surface of the base fabric body is 4.0 g / m2 or more and less than 10.0 g / m2, and the resin layer is provided such that the fibers are not exposed at a surface on the resin layer side.

Description

Airbag fabric

[0001] The present invention relates to an airbag fabric.

[0002] For example, as described in Patent Document 1, an airbag fabric comprises a fabric body such as a woven fabric and a resin layer provided on at least one side of the fabric body. The provision of the resin layer reduces the air permeability of the airbag fabric, thereby maintaining the shape of the airbag when inflated. Furthermore, the provision of the resin layer makes the fabric body less susceptible to fraying.

[0003] In a conventional airbag fabric, the fabric body is a woven fabric made of nylon or polyester yarn, and the resin layer is a layer of silicone resin.

[0004] Japanese Patent Application Publication No. 11-293541

[0005] Incidentally, in conventional general airbag base fabrics, the base fabric body and the resin layer are made of different materials as described above, which makes them difficult to recycle.

[0006] Therefore, an object of the present invention is to provide an airbag fabric that is easy to recycle.

[0007] The present invention includes the embodiments shown below.

[0008] [1] An airbag fabric comprising a base fabric body and a resin layer provided on at least one side of the base fabric body, wherein the base fabric body is made of polyethylene terephthalate fibers, the resin layer is made of polyester resin, and the amount of the polyester resin on one side of the base fabric body is 4.0 g / m ２ 10.0g / m or more ２ The airbag base fabric is provided such that the fiber is not exposed on the surface of the resin layer side, and the resin layer is less than the fiber.

[0009] [2] Air permeability under a pressure difference of 20 kPa is 0.01 L / (cm ２ The airbag fabric according to [1], wherein the elastic modulus is 1 / 2 min or less.

[0010] [3] The airbag fabric according to [1] or [2], having a bending resistance of 7N or less.

[0011] [4] The airbag fabric according to any one of [1] to [3], wherein the melting point of the polyester resin constituting the resin layer is lower than the melting point of the polyethylene terephthalate fiber constituting the base fabric body.

[0012] [5] The airbag fabric according to any one of [1] to [4], wherein the base fabric body is water-repellent.

[0013] [6] The ratio of the weight of the polyester resin permeated into the base fabric body to the weight of the polyester resin applied to the base fabric body is less than 70%. [1] to [5]. The airbag base fabric according to any one of the above.

[0014] [7] The airbag fabric according to any one of [1] to [6], wherein the base fabric body is a plain weave fabric.

[0015] [8] The airbag fabric according to any one of [1] to [7], wherein the fineness of the yarn made of polyethylene terephthalate fiber constituting the base fabric body is 280 to 560 decitex.

[0016] The airbag fabric of this embodiment is easy to recycle because the fabric body is made of polyethylene terephthalate fibers and the resin layer is made of polyester resin.

[0017] 1 is a cross-sectional view of an airbag fabric; 2 is a diagram showing a yarn and a resin layer on a cross section of an airbag fabric; 3 is a cross-sectional photograph of an airbag fabric; 4 is a photograph of the airbag fabric of Example 1 taken from the resin layer side; 5 is a photograph of the airbag fabric of Example 3 taken from the resin layer side; 6 is a cross-sectional photograph of the airbag fabric of Example 3; 7 is a photograph of the airbag fabric of Comparative Example 2 taken from the resin layer side; 8 is a photograph of the airbag fabric of Comparative Example 4 taken from the resin layer side; 9 is a diagram showing a fabric air permeability measuring device;

[0018] The following description of the embodiments will be given with reference to the accompanying drawings. Note that the embodiments described below are merely examples, and any modifications that do not deviate from the spirit of the present invention are included within the scope of the present invention.

[0019] As shown in FIG. 1 , the airbag fabric 1 of the embodiment includes a fabric body 2 and a resin layer 3 provided on one side of the fabric body 2 .

[0020] The base fabric main body 2 is made of polyethylene terephthalate fibers. Polyethylene terephthalate fibers are excellent fibers for the base fabric main body 2 in terms of the strength, durability, and cost required for airbags. One or more of various additives may be added to the polyethylene terephthalate fibers. Examples of the various additives include heat stabilizers, antioxidants, light stabilizers, anti-aging agents, lubricants, smoothing agents, pigments, water repellents, shielding agents, gloss imparting agents, flame retardants, and plasticizers. An example of a yarn made of polyethylene terephthalate fibers is polyester yarn.

[0021] More specifically, the base fabric body 2 is a woven fabric, knitted fabric, or nonwoven fabric made of polyester yarn. Examples of woven fabrics include plain weave, twill weave, satin weave, and the like. Examples of knitted fabrics include weft knitting, circular knitting, and warp knitting. Among woven fabrics, knitted fabrics, and nonwoven fabrics, those that can ensure as much strength as possible are preferred, for example, woven fabrics. Among woven fabrics, those that have as much uniform strength and other properties as possible in both the vertical and horizontal directions are preferred, for example, plain weave.

[0022] The fineness of the yarn (e.g., polyester yarn) constituting the base fabric main body 2 is preferably 280 to 560 decitex, and more preferably 300 to 470 decitex. This ensures the strength of the base fabric main body 2 and allows the base fabric main body 2 to be thin enough to be compact when folded. In particular, when the base fabric main body 2 is a woven or knitted fabric, it is preferable that the fineness of the yarn constituting the base fabric main body 2 is in the above range. The polyester yarn is a filament yarn with a filament count of, for example, 80 to 110.

[0023] Although resins such as silicone, acrylic, polyurethane, polyolefin, and phenolic resins can be used for the base fabric body 2, the resin layer 3 in this embodiment is made of polyester resin. Polyester resin is a long-chain synthetic polymer in which the bonds between monomers are primarily ester bonds. Polyesters include polyethylene terephthalate.

[0024] The melting point of the polyester resin that constitutes the resin layer 3 is lower than the melting point of the polyethylene terephthalate fibers that constitute the base fabric main body 2. As a result, the energy required to melt the airbag fabric 1 for recycling is less likely to be large compared to melting the base fabric main body 2 without the resin layer 3. This makes the airbag fabric 1 suitable for recycling. In addition, the polyethylene terephthalate fibers that constitute the base fabric main body 2 are less susceptible to thermal degradation.

[0025] The melting point of the polyester resin constituting the resin layer 3 is, for example, 80°C or higher and 250°C or lower (however, lower than the melting point of the polyethylene terephthalate fibers constituting the base fabric body 2). By having a melting point of 80°C or higher, the polyester resin is less likely to melt even in a hot vehicle interior, and the performance of the airbag is less likely to deteriorate.

[0026] The amount of polyester resin constituting the resin layer 3 is 4.0 g / m ２ 10.0g / m or more ２ The fabric main body 2 is completely covered with the resin layer 3, and the fibers of the fabric main body 2 are not exposed from the resin layer 3. Therefore, even when a person views the airbag fabric 1 from the resin layer 3 side, the fibers of the fabric main body 2 are not visible.

[0027] The resin layer 3 is provided by applying a polyester resin to the fabric body 2. The fabric body 2 may be subjected to a water-repellent treatment before the polyester resin is applied.

[0028] When the base fabric body 2 is not water-repellent, the viscosity of the polyester resin constituting the resin layer 3 is preferably 25,000 to 50,000 mPa·s. When the base fabric body 2 is water-repellent, the viscosity of the polyester resin constituting the resin layer 3 is preferably ... viscosity is relatively high, the polyester resin does not easily penetrate into the base fabric body 2, making it easier for the resin layer 3 to cover the base fabric body 2. Furthermore, when the viscosity is 50,000 mPa·s or less, it is easier to form a uniform resin layer 3 by application.

[0029] Whether or not the base fabric main body 2 has been subjected to water-repellent treatment can be confirmed by conducting a water-repellent test on the side of the airbag base fabric 1 on which the resin layer 3 is not provided.

[0030] Regardless of whether the fabric body 2 has been subjected to a water-repellent treatment or not, the penetration rate of the polyester resin into the fabric body 2 is preferably less than 70%. The penetration rate of the polyester resin into the fabric body 2 refers to the ratio of the weight of the polyester resin that has penetrated into the fabric body 2 to the weight of the polyester resin that has been applied (coated) to the fabric body 2 per unit area. This penetration rate is calculated using the following formula.

[0031]

[0032] Here, R is the penetration rate (%) of the polyester resin into the base fabric body 2, and W is the weight (g / m) of the polyester resin applied (coated) to a unit area of ​​the base fabric body 2. ２ ), T is the average thickness (μm) of the resin layer 3 in the airbag fabric 1 (i.e., the layer of polyester resin that did not penetrate into the fabric body 2 and remained on the surface of the fabric body 2).

[0033] The weight W of the polyester resin applied (coated) to a unit area of ​​the base fabric body 2 can be calculated as the difference between the weight of the unit area of ​​the airbag base fabric 1 and the weight of the base fabric body 2 remaining after dissolving and removing the polyester resin from the airbag base fabric 1 with a solvent such as toluene.

[0034] The average thickness T of the resin layer 3 is the average value of the thickness of the resin layer 3 at multiple locations (preferably 8 or more locations) on the cross-sectional photograph of the airbag fabric 1. As shown in Figures 2 and 3, the thickness t of the resin layer 3 at each measurement location is the vertical length from the vertex of the yarn 2a that constitutes the fabric body 2 and is in contact with the resin layer 3 to the surface of the resin layer 3 in a cross-sectional photograph in which the direction perpendicular to the surface of the airbag fabric 1 is the vertical direction.

[0035] Also, 1.2 is the density of the polyester resin (g / cm ３ The density of polyester resin varies slightly depending on the type, ranging from 1.1 to 1.3, but the average value is 1.2, and the density of any polyester resin does not deviate significantly from 1.2. Therefore, in calculating the permeability, the density of polyester resin is set to 1.2.

[0036] By setting the penetration rate of the polyester resin into the base fabric body 2 to less than 70%, the base fabric body 2 is less likely to become hard, and a resin layer 3 of sufficient thickness is formed, making the airbag base fabric 1 less breathable.

[0037] The penetration rate of the polyester resin into the fabric body 2 is preferably 3% or more. When the penetration rate is 3% or more, the resin layer 3 is less likely to peel off from the fabric body 2.

[0038] The air permeability of the airbag fabric 1 under a differential pressure of 20 kPa is 0.01 L / (cm ２ Here, the air permeability under a differential pressure of 20 kPa refers to the air permeability of the airbag fabric 1 when the differential pressure between one side and the other side of the airbag fabric 1 is 20 kPa. A specific method for measuring the air permeability will be described later.

[0039] The bending resistance of the airbag fabric 1 is 7N or less. The smaller the bending resistance, the more flexible it is. In order to make the bending resistance 7N or less, it is effective to cover the fabric body 2 with a resin layer 3 made of polyester resin, but the glass transition temperature of the polyester resin is also effective. A specific method for measuring the bending resistance will be described later.

[0040] To manufacture such an airbag fabric 1, first, a fabric body 2 is prepared. Next, an operator applies polyester resin to one side of the fabric body 2 to provide a resin layer 3. The application may be done manually or using an application device. Once the applied polyester resin has dried, the airbag fabric 1 is completed.

[0041] When applying a water-repellent finish to the base fabric body 2, the worker performs the water-repellent finish before applying the polyester resin. The water-repellent finish is performed by impregnating the base fabric body 2 with a water-repellent agent such as a fluorine-based, silicone-based, or hydrocarbon-based agent, and then drying the base fabric body 2.

[0042] The airbag fabric 1 thus completed is cut into a predetermined shape and then joined by means of sewing, adhesive, or the like, and if necessary, a reinforcing fabric is also joined to form an airbag. The thread used for sewing, the adhesive used for adhesion, and the reinforcing fabric are also preferably made of polyester. Examples of airbags include driver's seat airbags, passenger seat airbags, side airbags, and side curtain airbags.

[0043] Next, the effects of this embodiment will be described. First, the airbag fabric 1 of this embodiment is easy to recycle because the fabric body 2 is made of polyethylene terephthalate fibers and the resin layer 3 is made of polyester resin, and they are made of the same material or materials that can be considered the same.

[0044] The amount of polyester resin in the resin layer 3 is 10.0 g / m ２ Since the amount of polyester resin in the resin layer 3 is less than 4.0 g / m, the airbag fabric 1 is flexible and easy to fold. In addition, since the amount of polyester resin is small, the airbag fabric 1 is light. ２ For these reasons, the fibers of the base fabric body 2 are not exposed from the resin layer 3 .

[0045] Furthermore, since the resin layer 3 is provided in a form in which the fibers of the base fabric main body 2 are not exposed from the resin layer 3, the airbag base fabric 1 is less breathable.

[0046] The amount of polyester resin in the resin layer 3 is 10.0 g / m２ Even though the thickness is less than 100 μm, the fibers of the base fabric main body 2 are not exposed from the resin layer 3, which means that the polyester resin has hardly penetrated into the base fabric main body 2. Therefore, the airbag fabric 1 is flexible.

[0047] In this way, since the airbag base fabric 1 is flexible and not easily breathable, an airbag manufactured from this airbag base fabric 1 can be folded up small and stored, and maintains its shape when inflated.

[0048] In addition, the airbag fabric 1 has an air permeability of 0.01 L / (cm ２ Since the elastic modulus is equal to or less than 1 / 2 min, an airbag manufactured from this airbag fabric 1 is easy to inflate and is likely to maintain its shape when inflated.

[0049] Furthermore, since the airbag fabric 1 has a bending resistance of 7N or less, an airbag manufactured from this airbag fabric 1 can be easily folded into a small size for storage.

[0050] Furthermore, if the base fabric main body 2 is water-repellent, the polyester resin is particularly unlikely to penetrate into the base fabric main body 2, making the airbag fabric 1 particularly flexible. Conversely, if the base fabric main body 2 is not water-repellent, the water-repellent treatment step is unnecessary, improving the productivity of the airbag fabric 1. Furthermore, if the base fabric main body 2 is not water-repellent, foreign matter does not get into the material of the airbag fabric 1, making it particularly easy to recycle.

[0051] Next, examples and comparative examples will be described. In the examples and comparative examples, an operator produced an airbag fabric in which a resin layer was provided on a fabric body under the conditions described below, and measured the air permeability and bending resistance.

[0052] (Example 1) An operator placed the base fabric body on a urethane bed (table), and applied polyester resin with a viscosity of 30,000 mPa·s to the upper surface of the base fabric body using a stainless steel knife with a sharp blade, so that the amount of resin applied was 4.6 g / m ２The airbag fabric was then subjected to a heat treatment at 150 ° C. for 60 seconds using a pin tenter dryer. The surface of the resin layer side of the airbag fabric after the heat treatment was as shown in FIG. 4, and no exposure of the fibers constituting the fabric body from the resin layer was observed.

[0053] (Example 2) An operator placed the base fabric body on a urethane bed (table), and applied polyester resin with a viscosity of 30,000 mPa·s to the upper surface of the base fabric body using a stainless steel knife with a 3.8J blade, with the resin application amount being 8.6 g / m ２ The airbag fabric was prepared as follows. The 3.8J blade is a blade that is rounded and not as sharp as a sharp blade. By using a 3.8J blade, the amount of resin applied can be increased compared to when a sharp blade is used. The coated airbag fabric was subjected to a heat treatment at 150 ° C. for 60 seconds using a pin tenter dryer. The surface of the resin layer side of the airbag fabric after the heat treatment was the same as in FIG. 4, and no exposure of the fibers constituting the base fabric body from the resin layer was observed.

[0054] (Example 3) An operator placed the water-repellent base fabric body on a urethane bed (table), and applied polyester resin with a viscosity of 30,000 mPa·s to the upper surface of the base fabric body using a stainless steel knife with a sharp blade, so that the amount of resin applied was 5.4 g / m ２ The airbag fabric was then subjected to a heat treatment at 150 ° C. for 60 seconds using a pin tenter dryer. The surface of the resin layer side of the airbag fabric after the heat treatment was as shown in FIG. 5, and no exposure of the fibers constituting the fabric body from the resin layer was observed.

[0055] In the area indicated by the arrow in Figure 5, the fibers constituting the base fabric main body appear to be exposed from the resin layer. However, as shown in Figure 6, which is a cross-sectional photograph of the airbag fabric of Example 3, in reality, the resin layer is located above the fibers constituting the base fabric main body, and the fibers are not exposed. The area in Figure 5 where the fibers appear to be exposed is the area where the shape of the fibers underneath the resin layer appears on the surface of the resin layer, as shown by the arrow in Figure 6.

[0056] (Example 4) An operator placed the water-repellent base fabric body on a urethane bed (table), and applied polyester resin with a viscosity of 30,000 mPa·s to the upper surface of the base fabric body using a stainless steel knife with a 3.8J blade, with the resin application amount being 9.1 g / m ２ The airbag fabric was prepared as follows: After application, the airbag fabric was subjected to heat treatment at 150 ° C. for 60 seconds using a pin tenter dryer. The surface of the resin layer side of the airbag fabric after the heat treatment was the same as that shown in FIG. 5, and no exposure of the fibers constituting the fabric body from the resin layer was observed.

[0057] (Comparative Example 1) An operator placed the base fabric body on a urethane bed (table) and applied silicone resin with a viscosity of 30,000 mPa·s to the upper surface of the base fabric body using a stainless steel knife with an ultra-sharp blade, with the amount of resin applied being 9.8 g / m ２ The airbag fabric was prepared as follows. The ultra-sharp blade is sharper than the sharp blade. The airbag fabric after application was subjected to a heat treatment at 170 ° C. for 80 seconds using a pin tenter dryer. Exposure of the fibers constituting the base fabric body from the resin layer was confirmed.

[0058] (Comparative Example 2) An operator placed the base fabric body on a urethane bed (table), and applied polyester resin with a viscosity of 30,000 mPa·s to the upper surface of the base fabric body using a stainless steel knife with a sharp blade, so that the amount of resin applied was 3.7 g / m ２ The airbag fabric was then subjected to a heat treatment at 150 ° C. for 60 seconds using a pin tenter dryer. The surface of the resin layer side of the airbag fabric after the heat treatment was as shown in FIG. 7, and the fibers constituting the fabric body were exposed.

[0059] (Comparative Example 3) An operator placed the base fabric body on a glass bed (table) and applied polyester resin with a viscosity of 30,000 mPa·s to the upper surface of the base fabric body using a dedicated applicator (application device). The applied amount of resin was 25.0 g / m ２The airbag fabric was prepared as follows. The applicator is a device capable of applying a thick resin onto the base fabric body. The airbag fabric after application was subjected to a heat treatment at 150 ° C. for 60 seconds using a pin tenter dryer. After the heat treatment, no exposure of the fibers constituting the base fabric body from the resin layer was observed on the surface of the resin layer side of the airbag fabric.

[0060] (Comparative Example 4) An operator placed the base fabric body on a urethane bed (table), and applied polyester resin with a viscosity of 12,000 mPa·s to the upper surface of the base fabric body using a stainless steel knife with a 3.8J blade, with the resin application amount being 9.5 g / m ２ The airbag fabric was subjected to a heat treatment at 150 ° C. for 60 seconds using a pin tenter dryer. The surface of the resin layer side of the airbag fabric after the heat treatment was as shown in FIG. 8, and the fibers constituting the fabric body were exposed.

[0061] (Method for measuring airflow rate) The airflow rate under a 20 kPa differential pressure was measured using a fabric airflow rate measuring instrument manufactured by Kyoto Seiko Co., Ltd., as shown in FIG. 9. The fabric airflow rate measuring instrument in FIG. 9 is equipped with a Cosmo Instruments DF2810P as the flow meter 16, a Cosmo Instruments LF2-100L as the laminar flow tube 15, and a Cosmo Instruments DP-330BA as the pressure gauge 18. An operator fixed a 20 cm x 20 cm sample 10 cut out from the airbag base fabric with a ring-shaped fastener 12 to a cylindrical first clamp 13a having an inner diameter of 50 mm connected to a pressure device 14, and sandwiched between a cylindrical second clamp 13b having an inner diameter of 50 mm connected to the laminar flow tube 15. Then, the operator applied pressure from the first clamp 13a side using the pressure device 14, and operated the pressure regulating valve 17 so that the display of the pressure gauge 18 became 20 kPa. In this pressurized state, the amount of air passing through the sample was detected by a flow meter 16 connected to the laminar flow tube 15, and was taken as the amount of air passing under a differential pressure of 20 kPa.

[0062] (Method for measuring bending resistance) The bending resistance was measured as a pressing resistance value using an autograph tester. Specifically, an operator placed a 100 mm × 100 mm sample cut out from an airbag fabric on an iron plate with a 20 mm × 20 mm hole, pressed the sample into the hole with a 12 mm diameter round rod, and measured the pressing resistance value.

[0063] The measurement results of the Examples are summarized in Table 1, and the measurement results of the Comparative Examples are summarized in Table 2. All of the Examples had good air permeability and bending resistance, while the Comparative Examples had inferior air permeability and / or bending resistance compared to the Examples.

[0064]

[0065] Various modifications can be made to the above embodiment.

[0066] For example, resin layers may be provided on both sides of the base fabric body. When resin layers are provided on both sides of the base fabric body, the amount of polyester resin on at least one side is 4.0 g / m ２ 10.0g / m or more ２ It is sufficient that the thickness is less than 1 / 2 mm and that the fibers are not exposed from the resin layer.

[0067] DESCRIPTION OF SYMBOLS 1...Airbag base fabric, 2...Base fabric body, 2a...Thread, 3...Resin layer, 10...Sample, 12...Fastener, 13a...First clamp, 13b...Second clamp, 14...Pressure device, 15...Laminar flow tube, 16...Flow meter, 17...Pressure adjustment valve, 18...Pressure gauge

Claims

1. An airbag fabric comprising a base fabric body and a resin layer provided on at least one side of the base fabric body, the base fabric body being made of polyethylene terephthalate fibers, the resin layer being made of polyester resin, and the amount of the polyester resin on the one side of the base fabric body being 4.0 g / m ２ 10.0g / m or more ２ and the resin layer is provided in a form in which the fibers are not exposed on a surface on the resin layer side.

2. The air permeability under a pressure difference of 20 kPa is 0.01 L / (cm ２ The airbag fabric according to claim 1, wherein the elastic modulus is less than or equal to 1.0 .min.

3. The airbag fabric according to claim 1 or 2, having a bending resistance of 7N or less.

4. An airbag fabric as described in claim 1 or 2, wherein the melting point of the polyester resin constituting the resin layer is lower than the melting point of the polyethylene terephthalate fibers constituting the base fabric body.

5. The airbag fabric according to claim 1 or 2, wherein the main body of the fabric is treated to be water repellent.

6. An airbag fabric as described in claim 1 or 2, wherein the ratio of the weight of the polyester resin that has permeated into the base fabric body to the weight of the polyester resin applied to the base fabric body is less than 70%.

7. The airbag fabric according to claim 1 or 2, wherein the base fabric body is a plain weave fabric.

8. The airbag fabric according to claim 1 or 2, wherein the polyethylene terephthalate fiber yarn constituting the main body of the fabric has a fineness of 280 to 560 decitex.

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