Airbag fabric with improved durability and method for preparing the same

Abstract

This invention relates to airbag fabrics and a method for preparing airbag fabrics, the airbag fabric comprising: a textile substrate; and a coating on at least one side of the textile substrate, wherein the coating comprises a polyurethane resin, a crosslinking agent, and a hydrophilic thickener, and the crosslinking agent is a compound having blocked active groups. The method for preparing the airbag fabric comprises the steps of: preparing a textile substrate; and forming a coating on at least one side of the textile substrate, wherein the step of forming the coating comprises the steps of: adding a crosslinking agent and a hydrophilic thickener to a polyurethane aqueous dispersion to prepare a coating solution; coating the coating solution onto at least one side of the textile substrate; drying the textile substrate coated with the coating solution; and heat-treating the dried textile substrate.

Description

Technical Field

[0001] The present invention relates to a fabric for an airbag and a method for preparing the same, and more particularly, to a fabric for an airbag having excellent air tightness and improved durability, and a method for preparing the fabric for an airbag with high productivity. Background Art

[0002] When the impact detection sensor detects an impact applied to the vehicle during a vehicle collision or rollover while traveling above a certain speed, the airbag inflates and deploys, thereby protecting the driver and passengers of the vehicle from injury in the accident.

[0003] The fabric for an airbag includes a coating layer for improving the air tightness of the fabric and a textile substrate.

[0004] Typically, inflatable air bags are prepared by cutting and sewing a plain or basket weave woven textile substrate, or by taping the seams formed by cutting and sewing with a sealant, or using a one-piece woven (OPW) type textile substrate that forms a double-layer inflatable portion during the weaving process.

[0005] The coating formed on the textile substrate is used to provide the airtightness required for the airbag. For example, since the side curtain airbag should maintain the inflated shape for a long time (e.g., 6 seconds) to protect passengers in a rollover accident, it should have a relatively higher airtightness than other types of airbags.

[0006] As a main component of the coating, chloroprene rubber was used in the early stage. However, in order to meet the high airtightness particularly required for the side curtain fabric, an excessively large amount of chloroprene rubber needs to be applied. Therefore, using chloroprene rubber to form the coating is not preferable in terms of the production cost and packability of the airbag. Also, in the case of using chloroprene rubber to form the coating, the airbag becomes too heavy, thus causing a decrease in the fuel efficiency of the car.

[0007] Therefore, recently, silicone resin or polyurethane resin is replacing chloroprene rubber. In particular, the use of volatile organic solvents is restricted due to environmental and cost issues, etc., and therefore, interest in polyurethane aqueous dispersion coatings is growing.

[0008] Generally, polyurethane aqueous dispersions can provide excellent internal pressure retention performance for airbags even when used in smaller amounts compared to silicone resins. However, since the polyurethane aqueous dispersion coating has low adhesion to the textile substrate, there is a risk of delamination of the coating from the textile substrate when the coating is stored in a packaged manner in a car for a long time. Such delamination of the coating makes it impossible for the side curtain airbag to maintain its inflated shape in the event of a vehicle rollover accident.

[0009] In order to overcome the low durability of airbags including polyurethane aqueous dispersion coatings, it has been proposed to add a crosslinking agent to the polyurethane aqueous dispersion coating.

[0010] However, since curing of the coating solution proceeds relatively quickly immediately after the crosslinking agent is added to the polyurethane aqueous dispersion coating solution, airbag manufacturers should complete the coating process within about 2 or 3 hours after the crosslinking agent is added to the coating solution. That is, in the case where the coating process is slightly delayed, it may cause waste of materials and decrease in productivity.

[0011] Furthermore, even when a coating layer is formed using a polyurethane aqueous dispersion coating solution to which a crosslinking agent is added, the durability of the airbag is not improved as expected. Summary of the invention

[0012]

Technical issues

[0013] Therefore, the present invention relates to a fabric for an airbag and a method for preparing the same that can meet the above requirements in the related technical field.

[0014] One aspect of the present invention provides a fabric for an airbag having excellent airtightness and at the same time improved durability.

[0015] Another aspect of the present invention provides a fabric for an airbag capable of being prepared with high productivity without wasting materials and having excellent airtightness and at the same time improved durability.

[0016] In addition to the above-mentioned aspects of the present invention, other features and advantages of the present invention will be described below or may be obviously understood by those of ordinary skill in the art from these descriptions.

[0017]

Technical solution

[0018] According to one aspect of the present invention, there is provided a fabric for an airbag, comprising: a textile substrate; and a coating on at least one side of the textile substrate,

[0019] The coating comprises a polyurethane resin, a crosslinking agent and a hydrophilic thickener, and the crosslinking agent is a compound with a blocked active group.

[0020] The penetration level of the coating into the textile substrate may be between 10% and 50%, as defined by Formula 1 below:

[0021] *Formula 1: Penetration level (%) = (D / T) x 100,

[0022] Where D is the maximum depth of penetration of the coating into the textile substrate and T is the thickness of the textile substrate.

[0023] The textile substrate may be a fabric including warp yarns and weft yarns, and after aging for 408 hours at a temperature of 70±2° C. and a relative humidity of 95±2%, the flex abrasion of the airbag fabric may be more than 1,000 strokes in both the warp and weft directions as measured according to ISO 5981 standard.

[0024] The hydrophilic thickener may be a non-associative thickener.

[0025] The hydrophilic thickener may be a non-Newtonian pseudoplastic acryl-based thickener.

[0026] The textile substrate may be a one piece woven (OPW) type fabric including a plurality of warp yarns and weft yarns, the fineness of each of the warp yarns and the weft yarns may be 210 to 1500 denier, the density of the warp yarns and the density of the weft yarns may be 40th / inch to 80th / inch respectively based on one layer of the cavity area of ​​the fabric, and each of the warp yarns and the weft yarns may include at least one of aliphatic polyamide, aromatic polyamide, polyester and polyolefin.

[0027] The blocked active groups may include blocking components that dissociate from the active groups at 100° C. or higher.

[0028] The reactive group may be an isocyanate group or a carbodiimide group.

[0029] The blocking component may be 3,5-dimethylpyrazole (DMP), ε-caprolactam or methyl ethyl ketone oxime.

[0030] The crosslinking agent may be a polyisocyanate compound or a polycarbodiimide compound to which one or more blocking components selected from 3,5-dimethylpyrazole (DMP), ε-caprolactam, and methyl ethyl ketone oxime are bonded.

[0031] According to another aspect of the present invention, there is provided a method for preparing a fabric for an airbag, comprising the following steps: preparing a textile substrate; and forming a coating on at least one side of the textile substrate, wherein the step of forming the coating comprises the following steps: adding a crosslinking agent and a hydrophilic thickener to an aqueous polyurethane dispersion to prepare a coating solution; coating the coating solution on at least one side of the textile substrate; drying the textile substrate on which the coating solution is coated; and heat-treating the dried textile substrate, and the crosslinking agent is a compound having a blocked active group.

[0032] The blocked active groups may include blocking components that dissociate from the active groups at 100° C. or higher.

[0033] The reactive group may be an isocyanate group or a carbodiimide group.

[0034] The blocking component may be 3,5-dimethylpyrazole (DMP), ε-caprolactam or methyl ethyl ketone oxime.

[0035] The crosslinking agent may be a polyisocyanate compound or a polycarbodiimide compound to which one or more blocking components selected from 3,5-dimethylpyrazole (DMP), ε-caprolactam, and methyl ethyl ketone oxime are bonded.

[0036] The thickener may be a non-associative thickener.

[0037] The thickener may be a non-Newtonian pseudoplastic acryl-based thickener.

[0038] The viscosity of the thickener may be 25,000 to 60,000 cps, and the viscosity of the coating solution may be 6,000 to 30,000 cps.

[0039] The amount of coating solution applied to at least one side of the textile substrate may be 15 to 50 gsm.

[0040] The drying step may be performed by raising the temperature between 80°C and 150°C, and the heat treatment step may be performed at a temperature above 150°C.

[0041] It is to be understood that both the foregoing general description and the following detailed description are merely illustrative or explanatory of the present invention and are presented to provide more detailed explanation of the invention described in the claims.

[0042]

Beneficial Effects

[0043] By forming a coating on a textile substrate with an aqueous polyurethane dispersion capable of providing excellent internal pressure retention performance, and

[0044] (i) by adding a crosslinking agent and a hydrophilic thickener to the polyurethane aqueous dispersion coating solution, the adhesion between the textile substrate and the coating can be improved, thereby overcoming the durability problem of polyurethane, and

[0045] (ii) By using a crosslinking agent having a blocked reactive group as the crosslinking agent, the storage stability and storage life of the coating solution can be improved, thereby improving process efficiency and productivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] The accompanying drawings are used to help understand the present invention and constitute a part of the specification. They illustrate embodiments of the present invention and together with the detailed description of the present invention, explain the principle of the present invention.

[0047] Figure 1is a cross-sectional view of a fabric for an air bag according to one embodiment of the present invention. DETAILED DESCRIPTION

[0048] Hereinafter, embodiments of the present invention will be explained in detail with reference to the accompanying drawings. However, the embodiments described below are presented only as examples for clear understanding of the present invention, and the scope of the present invention is not limited thereto.

[0049] It is obvious to those skilled in the art that various modifications and changes can be made without departing from the technical concept and scope of the present invention. Therefore, the present invention includes the invention described in the claims and all modifications and changes within the scope of its equivalent.

[0050] A fabric (100) for an airbag according to an embodiment of the present invention includes a textile substrate (110) and a coating layer (120).

[0051] According to one embodiment of the present invention, the fabric (100) is used for a side curtain airbag, and the textile substrate (110) is a one piece woven (OPW) type fabric including warp yarns (111) and weft yarns (112). Based on one layer of the chamber area of ​​the OPW fabric, the density of the warp yarns (111) and the density of the weft yarns (112) are 40 to 80 th / inch, respectively.

[0052] The fineness of each warp and weft yarn (111, 112) should be 210 denier or more so that excellent mechanical properties (e.g., strength) can be maintained in terms of absorption performance for absorbing high temperature and high pressure deployment energy during airbag deployment. On the other hand, for the foldability and weight reduction of the airbag, the fineness of each warp and weft yarn (111, 112) is preferably 1500 denier or less.

[0053] Also, from the viewpoint of flexibility and smoothness of the coating surface, it is preferred that each of the warp and weft yarns (111, 112) is a multifilament yarn containing 72 or more filaments (111a, 112a).

[0054] Each of the warp yarns (111) and the weft yarns (112) may include at least one of aliphatic polyamide (eg, nylon 6 or nylon 66), aromatic polyamide (eg, aramid), polyester (eg, PET), and polyolefin (eg, PE or PP).

[0055] According to one embodiment of the present invention, the coating layer (120) on at least one side of the textile substrate (110) may include a polyurethane resin, a cross-linking agent, and a hydrophilic thickener.

[0056] The polyurethane resin of the present invention formed by urethane bonding of polyol and isocyanate is a polyol component, and may include one or more selected from polycarbonate-based polyol, polyether-based polyol, polyester-based polyol, and silicon-based polyol.

[0057] According to one embodiment of the present invention, the polyurethane resin may be a water-dispersible polyurethane resin.

[0058] The thickener imparts a certain level of viscosity to the coating solution used to form the coating layer (120), thereby improving the uniformity of the coating layer and the efficiency of the coating process.

[0059] According to the present invention, the thickener is a hydrophilic thickener. Since the hydrophilic thickener is contained as an additive in the coating solution containing the polyurethane aqueous dispersion as a main component, the polyurethane particles can better and evenly penetrate into the textile substrate (110) through the wetting effect when the medium water of the coating solution penetrates into the textile substrate (110).

[0060] The hydrophilic thickener may be a non-associative thickener that swells the medium water of the coating solution, and more preferably, it may be a low shear type non-Newtonian pseudoplastic acryl-based thickener that produces a viscosity change when a shear stress is applied.

[0061] Specifically, the thickener may be a hydrophilic non-associative thickener containing a (meth)acryloyl functional group, and such a thickener may be a liquid containing a solid content of about 5 to 20 wt %.

[0062] The penetration level of the coating (120) into the textile substrate (110) may be 10% to 50%, preferably 25% to 40%. The penetration level may be defined by Formula 1 below.

[0063] *Formula 1: Penetration level (%) = (D / T) x 100

[0064] Wherein, D is the maximum depth of the coating (120) penetrating into the textile substrate (110), and T is the thickness of the textile substrate (110). D and T can be measured by SEM photographs of the cross section of the fabric (100) for airbags.

[0065] If the permeation level of the coating layer (120) is less than 10%, although the airbag fabric (100) may have excellent flexibility, due to the low adhesion between the textile substrate (110) and the coating layer (120), they may be separated from each other when they are stored in a car for a long time. Such delamination of the coating layer makes it impossible for the side curtain airbag to maintain an inflated state in the event of a vehicle rollover accident.

[0066] According to the present invention, since the penetration level of the coating (120) is 10% or more, the bending wear of the airbag fabric (100) in both the warp and weft directions measured according to ISO 5981 standard after aging for 408 hours at a temperature of 70±2° C. and a relative humidity of 95±2% is more than 1000 strokes, which means that the coating (120) is delaminated from the textile substrate (110) even after more than 1000 strokes. This improvement in the bending wear of the airbag fabric (100) is due to the anchoring effect of the coating (120) component formed by deeply penetrating into the textile substrate (110).

[0067] Meanwhile, if the permeation level of the coating layer (120) is greater than 50%, the rigidity of the fabric (100) for an airbag rapidly increases (ie, the flexibility rapidly decreases), and thus the foldability, tear strength, and packability of the airbag deteriorate.

[0068] Optionally, the coating (120) may further include a wetting agent (e.g., an acrylate wetting agent) for promoting uniform penetration of the polyurethane particles into the textile substrate (110), a flame retardant (e.g., a non-halogen phosphorus flame retardant) for improving the flame retardancy of the airbag fabric (100), an anti-blocking agent for improving the surface properties of the airbag fabric (100), and / or a lubricant.

[0069] As mentioned above, the cross-linking agent may be a compound having blocked reactive groups.

[0070] More specifically, the blocked active groups may include blocking components that dissociate from the active groups at 100° C. or higher.

[0071] The reactive group may be an isocyanate group or a carbodiimide group.

[0072] The blocking component may be 3,5-dimethylpyrazole (DMP), ε-caprolactam or methyl ethyl ketone oxime.

[0073] The crosslinking agent may be a polyisocyanate compound or a polycarbodiimide compound to which one or more blocking components selected from 3,5-dimethylpyrazole (DMP), ε-caprolactam, and methyl ethyl ketone oxime are bonded.

[0074] The polyisocyanate compound is a compound having two or more NCO functional groups, and aliphatic, cycloaliphatic, aromatic, araliphatic polyisocyanate or a mixture thereof can be used.

[0075] As the polycarbodiimide compound, a compound having a carbodiimide equivalent of 200 to 600 can be used. The carbodiimide equivalent refers to the weight of the polycarbodiimide crosslinking agent relative to the number of moles of the carbodiimide group of the polycarbodiimide crosslinking agent.

[0076] The polycarbodiimide crosslinking agent has a long service life and excellent crosslinking efficiency. As such a polycarbodiimide crosslinking agent, Carbodilite V-02, SV-02, V-02-L2, V-04, E-01, E-02, E-03A or E-05 (Nisshinbo Chemical Inc.) can be used.

[0077] Hereinafter, a method for preparing a fabric for an airbag (100) according to one embodiment of the present invention will be described in detail.

[0078] The method of the present invention comprises the following steps: preparing a textile substrate (110); and forming a coating layer (120) on at least one side of the textile substrate (110).

[0079] The textile substrate (110) may be a one piece woven (OPW) type fabric including warp yarns (111) and weft yarns (112), and the density of the warp yarns (111) and the density of the weft yarns (112) may be 40 to 80 th / inch based on one layer of the chamber area of ​​the OPW fabric.

[0080] Each of the warp yarns and weft yarns (111, 112) may be a multifilament yarn including more than 72 filaments (111a, 112a) and having a total fineness of 210 to 1500 denier, and may include at least one of aliphatic polyamide (e.g., nylon 6 or nylon 66), aromatic polyamide (e.g., aramid), polyester (e.g., PET), and polyolefin (e.g., PE or PP).

[0081] Generally, in order to improve weaving properties, a softener or adhesive is added to the yarn before weaving. Therefore, before forming the coating layer (120) on at least one side of the textile substrate (110), in order to remove the softener or adhesive from the textile substrate (110), the steps of refining the textile substrate (110) and washing the refined textile substrate (110) may be further performed.

[0082] To form a coating (120) on at least one side of a textile substrate (110), a coating solution is first prepared.

[0083] The coating solution may be prepared by adding a cross-linking agent for improving the adhesion between the textile substrate (110) and the coating layer (120) and a thickener for controlling the viscosity of the coating solution to a polyurethane aqueous dispersion.

[0084] The water-dispersible polyurethane resin of the present invention formed by urethane bonding of polyol and isocyanate is a polyol component and may include one or more selected from polycarbonate-based polyol, polyether-based polyol, polyester-based polyol and silicon-based polyol.

[0085] As described above, since curing of the coating solution proceeds relatively quickly immediately after the crosslinking agent is added to the polyurethane aqueous dispersion, the manufacturer should complete the coating process within about 2 or 3 hours after the crosslinking agent is added. That is, if the coating process is slightly delayed, it will lead to material waste and reduced productivity.

[0086] In order to solve this problem, the crosslinking agent has a blocked active group. Since the active group of the crosslinking agent is blocked by a component that dissociates at a high temperature (e.g., above 100° C.), it takes a considerable time (pot life) for curing to start at room temperature after the crosslinking agent is added to the polyurethane aqueous dispersion. Therefore, according to the present invention, a large amount of time (e.g., about 48 hours or more) can be ensured before the coating solution is actually applied to the textile substrate (110) after the crosslinking agent is added to the polyurethane aqueous dispersion.

[0087] According to one embodiment of the present invention, the reactive group may be an isocyanate group or a carbodiimide group.

[0088] Furthermore, according to one embodiment of the present invention, the blocking component can be any compound that can be dissociated from the active group only above 100° C. and completely vaporized at a temperature exceeding 150° C. (i.e., completely removed during the heat treatment process for curing the coating solution), for example, it can be 3,5-dimethylpyrazole (DMP), ε-caprolactam or methyl ethyl ketone oxime.

[0089] More specifically, the crosslinking agent may be a polyisocyanate compound or a polycarbodiimide compound to which one or more blocking components selected from 3,5-dimethylpyrazole (DMP), ε-caprolactam, and methyl ethyl ketone oxime are bonded.

[0090] The coating solution may include the crosslinking agent in an amount of 1 to 5 parts by weight, based on 100 parts by weight of the aqueous polyurethane dispersion.

[0091] As described above, the thickener is a hydrophilic thickener, and when the medium water of the coating solution penetrates into the textile substrate (110), the thickener enables the polyurethane particles to penetrate into the textile substrate (110) better and uniformly through a wetting effect.

[0092] The hydrophilic thickener may be a non-associative thickener that swells the medium water of the coating solution, and more preferably, it may be a low shear type non-Newtonian pseudoplastic acryl-based thickener that produces a viscosity change when shear stress is applied by the head of the coating knife.

[0093] Specifically, the thickener may be a hydrophilic non-associative thickener containing a (meth)acryloyl functional group, and such a thickener may be a liquid containing about 5 wt % to 20 wt % solid content.

[0094] According to one embodiment of the present invention, the hydrophilic additive may have a viscosity of 25,000 to 60,000 cps, and may be added to the polyurethane aqueous dispersion in such an amount that the viscosity of the coating solution is 6,000 to 30,000 cps.

[0095] If the viscosity of the coating solution is greater than 30,000 cps, it may be difficult to control the amount of the coating solution applied to be less than 50 gsm (the reason why the amount of the coating solution applied should be controlled to be less than 50 gsm will be explained later), an excessive amount of thickener may be required, and uniformity may be reduced due to high viscosity, and penetration of the coating solution into the textile substrate (110) may become difficult. On the other hand, if the viscosity of the coating solution is less than 6,000 cps, it may not be possible to apply a sufficient amount of the coating solution, the desired properties of the coating layer (120) may not be exhibited, and the coating solution may penetrate too deeply into the textile substrate (110) due to capillary phenomena, thereby deteriorating the foldability and packability of the airbag.

[0096] The viscosity may be measured using a rotational viscometer, for example, a Brookfield DV2T, spindle LV-3 (63) or LV-4 (64) at a speed of 10 rpm.

[0097] Optionally, a wetting agent (e.g., an acrylate wetting agent) for promoting uniform penetration of polyurethane particles into the textile substrate (110), a flame retardant (e.g., a non-halogen phosphorus flame retardant) for improving the flame retardancy of the airbag fabric (100), an anti-adhesive agent for improving the surface properties of the airbag fabric (100), and / or a lubricant may be further added to the polyurethane aqueous dispersion.

[0098] For example, the coating solution may include 30 to 60 wt % of a solid content, and the coating solution may be prepared by adding 1 to 5 parts by weight of a crosslinking agent, 3 to 10 parts by weight of a thickener, 5 to 20 parts by weight of a flame retardant, and 0.1 to 20 parts by weight of other additives (silicon-based antiblocking agent and / or lubricant) to 100 parts by weight of an aqueous polyurethane dispersion.

[0099] Subsequently, the coating solution is coated on at least one side of the textile substrate (110). The coating solution can be uniformly coated on the textile substrate (110) by knife coating or roller coating. Knife coating may be preferred because the amount of coating can be easily controlled and uniform coating can be achieved.

[0100] According to one embodiment of the present invention, the amount of the coating solution applied to at least one side of the textile substrate may be 15 to 50 gsm. If the amount applied is less than 15 gsm, the internal pressure retention performance may be deteriorated, and if the amount applied is greater than 50 gsm, the stiffness of the airbag fabric (100) may increase rapidly (i.e., the flexibility may decrease rapidly), and thus, the foldability and packability of the airbag may be deteriorated, and weight reduction of the airbag may not be achieved.

[0101] Next, the textile substrate (110) on which the coating solution is applied is dried. For example, the textile substrate (110) can be dried in a tenter oven.

[0102] Through this drying process (also referred to as "first curing"), the water component of the coating solution is evaporated, and at the same time, the blocking component is dissociated from the active group of the cross-linking agent, so that the curing of the coating solution proceeds to form the coating layer (120). In order to prevent the coating layer (120) from being damaged, the drying process can be performed by raising the temperature between 80°C and 150°C.

[0103] Next, in order to completely cure the coating (120) (also referred to as "second cure"), the dried textile substrate is subjected to a heat treatment. The heat treatment step may be performed at a temperature above 150°C, for example, 155°C to 200°C for 120 to 350 seconds. The blocking components that are dissociated from the active groups during the drying process are vaporized and completely removed during such a heat treatment process.

[0104] A cooling process for reducing the temperature of the fabric (100) for an airbag may be further performed, for example, using a cooling cylinder (not shown), and the cooled fabric (100) may be wound in a winder (not shown).

[0105] Hereinafter, the effects of the present invention will be explained by specific examples and comparative examples of the present invention. However, the following examples are given only for a better understanding of the present invention, and the scope of the rights of the present invention is not limited thereto.

[0106] [Example and Comparative Example: Preparation of Fabric for Airbag]

[0107] Example 1

[0108] Using polyethylene terephthalate (PET) yarn, an OPW textile substrate (warp density: 57th / inch, weft density: 49th / inch) was prepared. The OPW textile substrate was sequentially passed through a refining bath and a washing bath, and then dried.

[0109] To 100 parts by weight of polyurethane aqueous dispersion, add 3 parts by weight of crosslinking agent (Covestro) [polyisocyanate blocked with DMP (3,5-dimethylpyrazole)] and 5 parts by weight of a hydrophilic non-associative acrylic thickener A-LA (Borchers) was used to obtain a coating solution with a viscosity of 15,000 cps.

[0110] 24 hours after the crosslinking agent was added to the polyurethane aqueous dispersion, the coating solution was uniformly coated on the textile substrate in an amount of 30 gsm by knife coating.

[0111] The drying process was performed by increasing the temperature between 80° C. and 150° C. Then, continuously, in order to impart smoothness and anti-blocking properties to the coating surface, a separate topcoat was applied, wherein the applied topcoat was a silicon-based topcoat composition containing talc, and was transferred onto the surface of the base coating using a gravure roller and then dried at a temperature of about 150° C. Then, by performing an additional heat treatment at 180° C., the fabric for an airbag was completed.

[0112] Comparative Example 1

[0113] A fabric for an air bag was obtained by the same method as in Example 1, except that no crosslinking agent was included in the coating solution.

[0114] Comparative Example 2

[0115] In addition to using a crosslinker with unblocked isocyanate groups (Covestro), a textile substrate and a coating solution were obtained separately by the same method as in Example 1. Then, an attempt was made to apply the coating solution (i.e., 24 hours after the crosslinking agent was added to the polyurethane aqueous dispersion, an attempt was made to apply the coating solution to the textile substrate), but curing of the coating solution had already significantly proceeded, so coating could not be performed.

[0116] Comparative Example 3

[0117] In addition to using hydrophobic PU thickener The airbag fabric was obtained by the same method as in Example 1 except that Gel L75N (Borchers) was used instead of the hydrophilic non-associative acrylic thickener.

[0118] [Experimental example: Measuring the performance of fabrics for airbags]

[0119] For each of the airbag fabrics of Examples and Comparative Examples prepared above, the penetration level of the coating and the bending wear after aging were measured, and the results are shown in Table 1 below.

[0120] Experimental example: Coating penetration level

[0121] The fabric sample was cut in a direction parallel to the weft yarn. Subsequently, a SEM photograph of the cross section was taken, and then the maximum depth (D) of the coating penetration into the textile substrate and the thickness (T) of the textile substrate were measured, respectively, and the penetration level of the coating of each fabric was calculated according to the following formula 1 using the measured values.

[0122] Formula 1: Penetration level (%) = (D / T) x 100

[0123] Experimental Example 2: Bending Wear after Aging

[0124] The fabric sample was placed at a temperature of 70±2°C and a relative humidity of 95±2% for 408 hours to perform aging. Subsequently, the bending wear of the fabric for airbags was measured in the warp and weft directions, respectively, according to ISO 5981. Specifically, when both ends of the fabric sample were fixed with a clamp and a load of 10N was applied to the fabric sample, the fabric sample was repeatedly reciprocated, and the stroke before the coating was peeled off was measured.

[0125]

Table 1

[0126]

[0127] As shown in Table 1, it was confirmed that in Example 1, the coating solution permeated into the fabric for airbags at a higher permeation level, and the finally prepared fabric for airbags had higher bending wear.

[0128] In contrast, it was confirmed that in Comparative Examples 1 to 3, each coating solution permeated into the fabric for an airbag at a low permeation level, and therefore, the bending wear of the fabric for an airbag was relatively low.

[0129] [Description of Reference Numerals]

[0130] 100: Fabric for airbags

[0131] 110: Textile base

[0132] 111: Warp

[0133] 112: Weft

[0134] 120: Coating

Claims

1. Fabrics for airbags, including: Textile substrates; and a coating on at least one side of said textile substrate, Wherein, the coating comprises a polyurethane resin, a cross-linking agent and a hydrophilic thickener, and The cross-linking agent is a compound having a blocked active group. The crosslinking agent is a polyisocyanate compound or a polycarbodiimide compound to which one or more blocking components selected from 3,5-dimethylpyrazole (DMP), ε-caprolactam or methyl ethyl ketone oxime are bonded, and Wherein, the hydrophilic thickener is a non-associative thickener.

2. The airbag fabric according to claim 1, wherein: The penetration level of the coating into the textile substrate is between 10% and 50%, as defined by Formula 1 below: *Formula 1: Penetration level (%) = (D / T) x 100, Wherein, D is the maximum depth of penetration of the coating into the textile substrate and T is the thickness of the textile substrate.

3. The airbag fabric according to claim 1, wherein: The textile substrate is a fabric comprising warp yarns and weft yarns, and After aging for 408 hours at a temperature of 70±2° C. and a relative humidity of 95±2%, the bending wear of the fabric for an airbag is measured according to ISO 5981 standard and is 1,000 strokes or more in both the warp and weft directions.

4. The airbag fabric according to claim 1, wherein: The hydrophilic thickener is a non-Newtonian pseudoplastic acryl-based thickener.

5. The airbag fabric according to claim 1, wherein: The textile substrate is a one piece woven (OPW) type fabric including a plurality of warp yarns and weft yarns, The fineness of each of the warp yarn and the weft yarn is 210 to 1500 denier, Based on one layer of the chamber area of ​​the fabric, the density of the warp yarns and the density of the weft yarns are 40th / inch to 80th / inch, respectively, and The warp yarns and the weft yarns each include at least one of aliphatic polyamide, aromatic polyamide, polyester, and polyolefin.

6. A method for preparing a fabric for an airbag, comprising the following steps: preparing a textile substrate; and forming a coating on at least one side of the textile substrate, The step of forming the coating comprises the following steps: adding a crosslinking agent and a hydrophilic thickener to a polyurethane aqueous dispersion to prepare a coating solution; applying the coating solution on at least one side of the textile substrate; drying the textile substrate having the coating solution applied thereon; and heat treating the dried textile substrate, and The cross-linking agent is a compound having a blocked active group. The crosslinking agent is a polyisocyanate compound or a polycarbodiimide compound to which one or more blocking components selected from 3,5-dimethylpyrazole (DMP), ε-caprolactam or methyl ethyl ketone oxime are bonded, and Wherein, the thickener is a non-associative thickener.

7. The method for preparing an airbag fabric according to claim 6, wherein: The hydrophilic thickener is a non-Newtonian pseudoplastic acryl-based thickener.

8. The method for preparing an airbag fabric according to claim 6, wherein: The viscosity of the thickener is 25,000 to 60,000 cps, and the viscosity of the coating solution is 6,000 to 30,000 cps.

9. The method for preparing an airbag fabric according to claim 6, wherein: The coating solution is applied on at least one side of the textile substrate in an amount of 15 to 50 gsm.

10. The method for preparing an airbag fabric according to claim 6, wherein: The drying step is carried out by increasing the temperature between 80°C and 150°C, and The heat treatment step is performed at a temperature above 150°C.

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