Coated fabric and airbag including same

Abstract

This application relates to coated fabrics and airbags containing the same.

Description

[Technical Field]

[0001] <Cross-reference to related applications> This application claims the benefit of priority based on Korean Patent Application No. 10-2020-0186479, filed December 29, 2020, and Korean Patent Application No. 10-2021-0185280, filed December 22, 2021, and all contents disclosed in the documents of said Korean patent applications are incorporated herein by reference.

[0002] <Technical field> This application relates to coated fabrics and airbags containing the same. [Background technology]

[0003] Airbags are devices that protect vehicle occupants by detecting the impact of a collision and then exploding explosives, which in turn inflates the airbag cushion with the gas supplied to the cushion. The high-temperature, high-pressure gas generated around the inflator, which is involved in the cushion inflation process, can damage the airbag fabric, reducing the cushion's pressure resistance.

[0004] To prevent this phenomenon, conventional approaches have been to use high-density woven fabrics or increase the coating weight, but these methods are not in line with the trend toward smaller and lighter airbag cushions and have the problem of reducing storage (foldability). Summary of the Invention [Problem to be solved by the invention]

[0005] One object of the present application is to provide a coated fabric that can overcome the above-mentioned problems of the prior art.

[0006] Another object of the present application is to provide a coated fabric with excellent foldability.

[0007] It is yet another object of the present application to provide a coated fabric that has excellent heat resistance and durability even at low weight and / or density.

[0008] It is yet another object of the present application to provide an airbag including said coated fabric.

[0009] The above and other objects of the present application can all be achieved by the invention described below. [Means for solving the problem]

[0010] In one embodiment, the present application relates to a coated fabric, specifically, the coated fabric includes a fiber substrate (A) and a coating layer (B) formed on the fiber substrate.

[0011] In relation to the bonding relationship between the fiber substrate (A) and the coating layer (B) that constitute the coated fabric, in this specification, "a coating layer is formed on the fiber substrate" means that a film (coating layer) made of a coating layer-forming substance is formed on the surface of the fiber substrate (and / or the fibers that form the fiber substrate).

[0012] According to a specific example of the present application, the coating layer (B) includes a binder resin and a filler, and the filler is present in a dispersed state in the coating layer or in the binder resin. Here, the filler may include chopped ceramic fiber and / or its agglomerate. Specifically, the filler may be agglomerated ceramic bulk fiber (CBF).

[0013] In one example, the fiber substrate may contain non-ceramic fibers, such as organic fibers, but if the fiber substrate contains ceramic fibers, the properties required for airbag fabrics, such as tensile strength, tear strength, and elongation, may be poor.

[0014] The type of organic fiber contained in the fiber substrate is not particularly limited, and may include, for example, one or more selected from polyester fiber, aramid fiber, nylon fiber, carbon fiber, polyketone fiber, cellulose fiber, polyolefin fiber, and acrylic fiber.

[0015] In one example, the fibers contained in the fiber substrate may have a fineness in the range of 450 to 1,100 dtex. Specifically, the lower limit of the fineness may be, for example, 500 dtex or more, 550 dtex or more, or 600 dtex or more, and the upper limit may be, for example, 1,000 dtex or less, 900 dtex or less, 800 dtex or less, 700 dtex or less, or 600 dtex or less. When the fineness of the fibers used satisfies the above range, it is advantageous to ensure appropriate levels of lightness and mechanical properties.

[0016] In one example, the fiber substrate is a woven fabric. of It can include.

[0017] In one example, the fibrous substrate can include one or more layers, for example, a laminate including two or more woven layers. 、 Alternatively, it may be a laminate comprising one or more woven fabric layers and one or more nonwoven fabric layers.

[0018] The fiber substrate may have low density characteristics to ensure the foldability of the airbag (coating) fabric.

[0019] In one example, the fiber substrate may be a woven fabric containing warp and weft yarns, and the warp and weft yarn densities of the woven fabric may each be in the range of 20 to 55 threads per inch (th / inch). Specifically, the lower limit of the warp or weft density may be, for example, 25ths / inch or more, 30ths / inch or more, 35ths / inch or more, 40ths / inch or more, or 45ths / inch or more, and the upper limit may be, for example, 50ths / inch or less or 45ths / inch or less. Although not particularly limited, the density may be measured in accordance with ISO 7211-2 (section 3.07).

[0020] In the prior art, in order to ensure the airtightness of the fabric and prevent damage (or breakage) when the airbag is inflated, it has been considered to use a fiber substrate woven at a high density (e.g., 70ths / inch) for at least one of the warp and weft yarns. However, the use of such a high-density fabric not only hinders the airbag's weight reduction, but also detracts from the foldability and storability of the airbag. In the present application, the use of a low-density fabric as described above allows for the fabric and airbag to be made lighter, which is advantageous for ensuring the foldability and storability of the airbag. In particular, the coated fabric of the present application has excellent heat resistance and durability due to the presence of a coating layer described below.

[0021] As described above, the coating layer of the coated fabric according to the present application contains ceramic fibers as a filler. The ceramic fibers are short fibers that have the property of cohesion within the coating layer or within the composition for forming the coating layer, and therefore can provide more satisfactory heat resistance and durability than other types of fillers.

[0022] The ceramic fibers (e.g., CBF (ceramic bulk fiber)) used in this application have a stronger tendency to agglomerate, which allows them to provide superior heat resistance compared to ceramic fillers of the same size, i.e., regular ceramic fillers that are not in fibrous form (see Evaluation 2 below).

[0023] For example, in a specific example of the present application, the ceramic fibers have a bulk shape in which chopped short fibers are aggregated together, and in the coating layer, the fibers form a plurality of agglomerates, and these agglomerates are dispersed within the coating layer or within the binder resin.

[0024] As can be seen from the experimental examples below, the examples using a coating layer containing dispersed aggregates of chopped ceramic fiber have superior heat resistance durability to Comparative Example 1, which has a larger coating amount, and Comparative Example 2, which uses a double-woven fabric.

[0025] In one example, the ceramic fiber, i.e., CBF (ceramic bulk fiber), may have a size in the range of 0.1 to 2.0 mm. Here, the size of the CBF can be confirmed using a known optical microscope, and may refer to the length of the longest dimension of the CBF shape.

[0026] Specifically, the size of the CBF (ceramic bulk fiber) may be, for example, 0.15 mm or more, 0.20 mm or more, 0.25 mm or more, 0.30 mm or more, 0.35 mm or more, 0.40 mm or more, 0.45 mm or more, 0.50 mm or more, 0.55 mm or more, 0.60 mm or more, 0.65 mm or more, 0.70 mm or more, 0.75 mm or more, 0.80 mm or more, 0.85 mm or more, 0.90 mm or more, 0.95 mm or more, 1.0 mm or more, 1.05 mm or more, 1.10 mm or more, 1.15 mm or more, 1.20 mm or more, 1.25 mm or more, 1.30 mm or more, 1.35 mm or more, 1.40 mm or more, 1.45 mm or more, or 1.50 mm or more. The upper limit of the size of the ceramic bulk fiber (CBF) may be, for example, 1.95 mm or less, 1.90 mm or less, 1.85 mm or less, 1.80 mm or less, 1.75 mm or less, 1.70 mm or less, 1.65 mm or less, 1.60 mm or less, 1.55 mm or less, 1.50 mm or less, 1.45 mm or less, 1.40 mm or less, 1.35 mm or less, 1.30 mm or less, 1.25 mm or less, 1.20 mm or less, 1.15 mm or less, 1.10 mm or less, 1.05 mm or less, 1.0 mm or less, 0.95 mm or less, 0.90 mm or less, 0.85 mm or less, 0.80 mm or less, 0.75 mm or less, 0.70 mm or less, 0.65 mm or less, 0.60 mm or less, 0.55 mm or less, or 0.55 mm or less. CBFs agglomerated to have such a size range can provide excellent heat resistance and durability.

[0027] In a specific example of the present application, the degree of dispersion of the aggregates may be expressed as the area occupied by the aggregates visible in the coating layer relative to the area of ​​the coating layer. For example, the aggregates may occupy an area ranging from 1 to 25% of the total area of ​​the coating layer. This area is calculated by analyzing the surface of the coating layer with an optical microscope. Specifically, the total area of ​​one surface of the coating layer is determined, the area occupied by the filler (aggregates) on that surface is determined, and then the percentage of the area of ​​the coating layer occupied by the filler (aggregates) is calculated, thereby determining the degree of dispersion of the filler. Here, the coating layer is divided into several regions, and the area measured for each divided region and its ratio may be calculated as an average (arithmetic mean). The type of optical microscope used in this regard is not particularly limited. Specifically, the ratio of the area occupied by the aggregates to the total area of ​​the coating layer may be, for example, 5% or more or 10% or more, with the upper limit being, for example, 20% or less or 15% or less.

[0028] In one example, the ceramic fibers may include oxides, nitrides, or carbides of one or more of Si, Al, Ti, Zr, Ca, and Mg.

[0029] In one example, the ceramic fibers may include oxides of one or more of Si, Al, Ti, Zr, Ca, and Mg.

[0030] In one example, the ceramic fibers can contain SiO2, CaO, and MgO. When the ceramic fibers contained in the coating layer contain at least SiO2, CaO, and MgO, excellent heat resistance and durability can be ensured, as confirmed by the following experimental examples.

[0031] In one example, the ceramic fibers may contain 50-60 wt% SiO2, 20-30 wt% CaO, and 10-30 wt% MgO. When the ceramic fibers contained in the coating layer contain SiO2, CaO, and MgO in the above content ranges, excellent heat resistance and durability can be ensured, as confirmed by the following experimental examples.

[0032] In one example, the coating amount of the coating layer per layer of the fiber substrate is 100 gsm (g / m 2 ) or less. Specifically, the lower limit of the coating amount may be, for example, 50 gsm or more, 55 gsm or more, 60 gsm or more, 65 gsm or more, 70 gsm or more, 75 gsm or more, 80 gsm or more, 85 gsm or more, 90 gsm or more, or 95 gsm or more. The upper limit may be, for example, 95 gsm or less, 90 gsm or less, 85 gsm or less, 80 gsm or less, 75 gsm or less, 70 gsm or less, 65 gsm or less, or 60 gsm or less. Generally, the greater the coating amount, the greater the coating effect is expected to be. However, since the coating layer of the present application is a coating layer in which a ceramic fiber filler is dispersed, even with a small coating amount, a higher coating effect (e.g., heat resistance durability) can be ensured compared to when no ceramic fiber filler is used or when other types of fillers are used. Although not particularly limited, the coating amount may be measured in accordance with ISO 3801 (section 3.07).

[0033] In one example, the binder resin contained in the coating layer may include one or more selected from a silicone resin and a urethane resin. The specific components and properties of the silicone resin and the urethane resin are not particularly limited.

[0034] According to an embodiment of the present application, a silicone resin may be used as the binder resin. In this case, the specific type of material that can form the silicone binder resin is not particularly limited. For example, the silicone resin may be or include a silicone elastomer formed by crosslinking or curing polysiloxane. Additionally, siloxane compounds known to be capable of providing silicone resins through polyaddition reactions may also be used as the silicone binder resin. Other known products, such as TCS7516 and TCS7537 from ELKEM, may also be used to form a coating layer containing a silicone binder resin.

[0035] In one example, the coating layer may contain 20 wt % or less of the filler, based on the total weight of the coating layer (100 wt %). Here, 100 wt % of the total weight of the coating layer may refer to the total solid content of the binder resin and filler contained in the coating layer. Alternatively, the total solid content of the binder resin, filler, and other components (e.g., additives) may be considered to be 100 wt % of the total coating layer. If the filler content exceeds the above range, the viscosity of the coating liquid increases, resulting in uneven dispersion and insufficient effects of forming the coating layer. The lower limit of the filler content is not particularly limited, but may be, for example, 1 wt % or more. Specifically, considering the effect of improving heat resistance and durability due to the use of fillers, it is preferable to use 5 wt % or more of filler.

[0036] In one example, the weight (g / m) of the coated fabric having the above structure 2 ) is 350g / m 2 Specifically, the upper limit of the weight of the coated fabric may be, for example, 340 g / m 2 Below 330g / m 2 Below 320g / m 2 Below 310g / m 2 or less than 300g / m 2The lower limit may be, for example, 280 g / m 2 More than 290g / m 2 More than 300g / m 2 or more than 310g / m 2 If the weight of the coated fabric exceeds the upper limit, it may be difficult to reduce the weight, and the manufacturing cost of the fabric may increase. If the weight of the coated fabric is below the lower limit, the mechanical properties may be reduced. Although not particularly limited, the weight of the coated fabric may be measured in accordance with ISO 3801 (section 3.07).

[0037] In one example, the thickness of the coated fabric may be in the range of 0.25 to 0.40 mm. Here, the thickness of the fabric is based on one layer of the coated fabric. Specifically, the lower limit of the thickness may be 0.26 mm or more, 0.27 mm or more, 0.28 mm or more, 0.29 mm or more, or 0.30 mm or more, and the upper limit may be, for example, 0.39 mm or less, 0.38 mm or less, 0.37 mm or less, 0.36 mm or less, or 0.35 mm or less. If the thickness is less than the lower limit of the above range, it is difficult to ensure sufficient mechanical properties, and if it exceeds the above range, the folding ability is poor. Although not particularly limited, the thickness may be measured in accordance with ISO 5084 (section 3.09).

[0038] In another aspect of the present application, the present application relates to a method for producing a coated fabric.

[0039] Specifically, the method for producing the coated fabric includes the steps of coating a composition containing a binder resin and a filler on a fiber substrate and then curing the coated composition.

[0040] Here, the filler includes chopped ceramic fiber or an aggregate thereof. The binder resin and the filler are the same as those described above, and therefore will not be described again.

[0041] The coating is carried out so that a film (coating layer) of the composition can be formed on the surface of the fibrous substrate (and / or the fibers forming the fibrous substrate). In this regard, the method for coating the composition onto the fibrous substrate is not particularly limited and can be appropriately carried out by a known method.

[0042] In one example, the curing is performed at room temperature or higher. The room temperature is a temperature at which neither heating nor cooling is performed, and may refer to a temperature of about 15 to 35°C. The temperature at room temperature or higher is a temperature at which heating is performed, and may refer to a temperature above 35°C, for example, a temperature in the range of 40 to 300°C. The curing time at the temperature is not particularly limited, and the curing may be performed within, for example, a few seconds to several tens of minutes.

[0043] In another aspect of the present application, the present application relates to an airbag, the airbag including the coated fabric described above.

[0044] The description of the structure and properties of the coated fabric included in the airbag has been given above, so it will be omitted here.

[0045] In one example, the coated fabric can be used as a reinforcing fabric for an airbag. Here, the reinforcing fabric refers to a structure that is patched (backed) to prevent damage to the airbag cushion fabric in the inflation portion of the airbag. In this regard, the structure of the airbag to which the reinforcing fabric is patched can be called a main panel. Accordingly, the airbag can include a main panel and a reinforcing fabric attached to at least a portion of the main panel.

[0046] In one example, the main panel can have an area equal to or greater than the area of ​​the reinforcing fabric.

[0047] In one example, the main panel may include a fabric including one or more selected from polyester fibers, aramid fibers, nylon fibers, carbon fibers, polyketone fibers, cellulose fibers, polyolefin fibers, and acrylic fibers.

[0048] In one example, the main panel can include a fabric having a density in the range of 45 to 55 ths / inch in the warp and weft.

[0049] In one example, the main panel may have a coating layer. The coating layer of the main panel may include, but is not limited to, commonly known silicone resin or urethane resin. When a coating is applied, the coating weight may be, but is not limited to, 20 to 40 gsm. [Effects of the Invention]

[0050] According to the present application, it is possible to provide a coated fabric for airbags that has excellent heat resistance and durability, even when a low-density coating layer is formed on a low-weight fabric, taking into consideration the weight reduction of airbags and coated fabrics, and the foldability and storability of airbag cushions. [Brief explanation of the drawings]

[0051] [Figure 1A] The inflator damage evaluation method and its results are shown in outline (1). Specifically, Figure 1A is an image showing the installation method of the inflator and fabric used in the evaluation. [Figure 1B] The inflator damage evaluation method and the results are shown in outline (2). Specifically, Figure 1B is a photographed image of the heat resistance evaluation results of Example 1. [Figure 1C]The inflator damage evaluation method and the results are shown in outline (3). Specifically, Figure 1C is an image of the heat resistance evaluation results of Comparative Example 1. [Figure 1D] The inflator damage evaluation method and the results are shown in outline (4). Specifically, Figure 1D is an image of the heat resistance evaluation results of Comparative Example 2. [Figure 2] 2 is an optical microscope image of the surface of a coating layer according to an example of the present application. It can be seen that the aggregated filler particles are visible as darker shades. The size of the filler particles seen in FIG. 2 is on the order of 0.1 to 2.0 mm. [Figure 3A] Figure 3A shows the results of a hot-rod test comparing the heat resistance and durability of various fillers and their cohesive properties. Specifically, Figure 3A shows the experimental results of a hot-rod test demonstrating that the present ceramic bulk fiber (CBF) offers superior heat resistance and durability. [Figure 3B] Figure 3B compares the heat resistance durability evaluation results (hot-rod evaluation) and cohesion characteristics depending on the type of filler. Specifically, Figure 3B is a schematic diagram explaining why heat resistance durability differs depending on the type of filler and cohesion characteristics. As shown in Figure 3B, CBF has a stronger tendency to cohere than other ceramic fillers, which allows it to suppress damage to the coating layer-forming resin under high temperature / high pressure conditions. DETAILED DESCRIPTION OF THE INVENTION

[0052] The functions and effects of the present invention will be described in more detail below through specific examples of the present invention, but these are presented as examples of the present invention and do not in any way limit the scope of the invention.

[0053] <Examples and Comparative Examples> Example 1 Preparation of coating composition: A composition containing a silicone binder resin, TCS7516 (manufactured by ELKEM), and ceramic bulk fiber (55% by weight of SiO, 25% by weight of CaO, and 20% by weight of MgO) was prepared. The content of the ceramic bulk fiber was adjusted to be approximately 10% by weight in the final cured coating layer.

[0054] Preparation of coated fabric: A fabric was prepared using PET fibers with a fineness of 550 dtex. Specifically, a fabric (one layer) with a density of 46 x 46 threads / inch (warp x weft) was prepared, and the composition thus prepared was applied to the fabric at a density of about 87 g / m 2 The fabric was coated at a level of grams per square meter (gsm). Then, the fabric was cured in a hot air chamber at a temperature of 160-190°C for 1 minute 30 seconds or more to produce a woven fabric. The weight of the coated fabric was 315 g / m 2 and the thickness is approximately 0.33 mm (see Figure 2).

[0055] <Comparative Example 1> Preparation of coating composition: TCS7517 manufactured by ELKEM was prepared as a silicone binder resin.

[0056] Preparation of coated fabric: A fabric was prepared using PA66 fiber with a fineness of 470 dtex. Specifically, a fabric (1 layer) with a density of 46 x 46 th / inch (warp x weft) was prepared. The prepared coating composition was applied to the fabric at a rate of about 122 g / m 2 The fabric was coated with a level of 308 g / m² (approximately 50 gsm more than in Example 1) and then cured under the same conditions as in Example 1. The weight of the coated fabric was 308 g / m². 2 and the thickness is about 0.33 mm.

[0057] <Comparative Example 2> Preparation of coating composition: DC3730, a urethane binder resin manufactured by Dow Corning, was prepared.

[0058] Preparation of coated fabric: A fabric was prepared using PA66 fiber with a fineness of 470 dtex. Specifically, a fabric with a density of 112 x 96 th / inch (warp x weft) (binded 2 layers, double-layered fabric, unlike the examples and comparative example 1) was prepared. The prepared composition was then coated onto the fabric at a level of about 69 gsm. The weight of the prepared coated fabric was 512 g / m. 2 and the thickness is about 0.66 mm.

[0059] <Evaluation 1: Heat resistance durability evaluation of coated fabric> The heat resistance of the coated fabrics produced in the Examples and Comparative Examples was evaluated by the following method.

[0060] 1. HOT-ROD evaluation Specifically, a cylindrical rod (10 mm in diameter, 80 mm in length, and 50 g in weight) was prepared, heated to the desired temperature of 600°C, and placed in contact with the coated fabric. The time (seconds) from when the rod completely melted the fabric to when it fell to the bottom was measured and listed in Table 1.

[0061] 2. Inflator damage assessment Test specimens were prepared by placing a single layer of heat shield fabric inside a KSS DAB dual inflator jig, followed by six layers of the coated fabrics from the examples and comparative examples (see Figure 1A). High-temperature, high-pressure gas was then applied to the test specimens, simulating the process of an airbag deployment. The high-temperature, high-pressure gas was applied for 40 to 80 milliseconds (ms) at a maximum pressure of 180 to 270 Kpa.

[0062] Next, the number of damaged fabrics (n) among the five-layer coated fabrics and the number of holes (m) found in these damaged fabrics were measured, and the evaluation results were quantified as follows, with n weighted at 10 and m weighted at 1. The lower the damage score, the better the heat resistance.

[0063] Damage score = (n x 10) + (m x n x 1)

[0064] [Table 1]

[0065] <Evaluation 2: Comparison of heat resistance durability by filler> The coated fabrics manufactured in Example 1 were prepared with different filler types, as shown in Figure 3A, and the results of the HOT-ROD evaluation were compared. Specifically, the filler content in the coating layer was uniform at 5 wt%. In this manner, HOT-ROD evaluation was performed on the following fabrics: ceramic bulk fiber (CBF), conventional ceramic filler (mica; approximately 40 μm D50 average (number distribution) size), silica (approximately 20-30 μm D50 average (number distribution) size), and Talc (approximately 20-30 μm D50 average (number distribution) size), and carbon fiber (CF) filler (approximately 2-3 mm size). The Y-axis indicates the arithmetic mean value (unit: seconds) after approximately 10 passes.

Claims

1. The coating material comprises a fiber substrate (A) and a coating layer (B) formed on the fiber substrate, The coating layer includes a binder resin and a filler, the filler is dispersed within the coating layer; the filler comprises agglomerates of chopped ceramic fibers having a size in the range of 0.1 to 2.0 mm; The coating amount of the coating layer per layer of the fiber substrate is 50 g / m ２ (gsm) more than 100g / m ２ (gsm) or less coated fabric for airbags.

2. 2. The coated fabric for an airbag according to claim 1, wherein the ceramic fibers include oxides, nitrides, or carbides of one or more of Si, Al, Ti, Zr, Ca, and Mg.

3. 3. The coated fabric for an airbag according to claim 2, wherein the ceramic fibers include oxides of one or more of Si, Al, Ti, Zr, Ca, and Mg.

4. The ceramic fibers are SiO ２ 4. The coated fabric for an airbag according to claim 3, comprising CaO and MgO.

5. The ceramic fibers are SiO ２ 5. The coated fabric for an airbag according to claim 4, comprising 50 to 60% by weight of cellulose acetate, 20 to 30% by weight of CaO, and 10 to 30% by weight of MgO.

6. The coated fabric for an airbag according to claim 1 , wherein the binder resin comprises at least one selected from the group consisting of a urethane resin and a silicone resin.

7. The coated fabric for an airbag according to claim 1, wherein the coating layer contains the filler in an amount of 20% by weight or less relative to 100% by weight of the entire coating layer.

8. 2. The coated fabric for an airbag according to claim 1, wherein the fiber substrate comprises one or more fibers selected from the group consisting of polyester fibers, aramid fibers, nylon fibers, carbon fibers, polyketone fibers, cellulose fibers, polyolefin fibers, and acrylic fibers.

9. 9. The coated fabric for an airbag according to claim 8, wherein the fineness of the fibers contained in the fiber substrate is in the range of 450 to 1,100 dtex.

10. The fiber substrate is a woven fabric including warp yarns and weft yarns, 9. The coated fabric for an airbag according to claim 8, wherein the warp and weft densities of the fabric are each within the range of 20 to 55 th / inch.

11. The coated fabric has a thickness of 350 g / m ２ 2. The coated fabric for an airbag according to claim 1, having a weight of:

12. 2. The coated fabric for an airbag according to claim 1, wherein the coated fabric has a thickness in the range of 0.25 to 0.40 mm.

13. The method includes applying a coating composition containing a binder resin and a filler onto a fiber substrate and then curing the composition to form a coating layer on the fiber substrate; the filler comprises agglomerates of chopped ceramic fibers having a size in the range of 0.1 to 2.0 mm; The coating amount of the coating layer per layer of the fiber substrate is 50 g / m ２ (gsm) more than 100g / m ２ (gsm) or less.

14. An airbag comprising the coated fabric for an airbag according to claim 1.

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