JP2000508270A - Airbag fabric - Google Patents

Abstract

(57) Summary A fabric (10) suitable for use in the construction of an entire airbag or a portion thereof has a plurality of reinforcing layers (23). The reinforcing layers (23) are joined together to form an integral sheet. The reinforcing layer (23) can be formed by a unidirectional laminate in which substantially parallel fibers are attached to a material such as a thermoplastic film, a nonwoven web or a coating. The fabrics (10) can be joined together by sewing or thermal processing to assemble them into an airbag.

Description

Description: FIELD OF THE INVENTION The present invention relates to composite fabrics suitable for use in inflatable airbag systems. BACKGROUND ART In an era of increasing interest in vehicle safety, vehicle safety devices have become a focus of interest for consumers, government agencies and vehicle manufacturers. Inflatable airbag systems are currently the most widely used automatic protection systems in the United States and are increasingly being used in other countries. Early airbag systems were installed in the steering wheel to protect the driver of the car in the event of a forward collision. Current airbag systems also include airbags mounted on the front dashboard to protect front-seat passengers against front collisions. Systems for side collisions and rear seats are also under development. Airbag systems are also being explored for other uses, such as automatic aircraft protection systems. The airbag system includes three major components: (1) a collision sensor, (2) an inflation source, and (3) an airbag or cushion. A collision sensor detects a collision by sensing a sudden deceleration or by other means. The sensor generates a signal to activate an inflation source, for example, a bottled gas or gas generating igniter. The gas is directed through the outlet into the airbag, causing the bag to inflate rapidly. The inflated air bag reduces the impact of the occupant by the braking effect of the gas from the gas outlet of the air bag. Since the airbag system is important as an automatic crash safety system (a reliability issue in the United States), the fabric used for the airbag must meet various design criteria. For quick inflation, the airbag must have low air permeability. The airbag must be resistant to rupture and tear. The airbag fabric must be relatively flammable in view of the hot gas and hot particulate material generated by the ignition expansion source. The outer surface of the airbag must be low-wear so that the deployed impact of the airbag does not injure the occupant. Other, more general criteria also influence airbag design. Airbags must be able to deploy rapidly. Also, a small ignition expansion source is desirable. Therefore, the airbag fabric must be lightweight and have a high packing density. These criteria are particularly important in the case of driver-side systems that are built into the steering wheel. Considering that automobiles can be used for a long period of time, airbag fabrics must have long-term stability (for example, at least 10 years or more) under various environmental conditions. Also, given the current fiercely competitive automotive market, fabrics must be inexpensive. Currently, the most commonly used airbag fabric in the United States is nylon 6 or nylon 66 fabric. Depending on the application (eg, driver, front seat occupant, side, etc.), the entire fabric or a portion thereof may be coated. In order to manufacture a bag, a nylon fabric must be cut and sewn. The time and labor required to sew the bag is raising the price of the entire airbag. Other fabrics also meet some design criteria, but generally do not balance well with many design criteria for airbags. For example, a cotton fabric may lose its strength over a long period of time, especially in a humid environment. Some glass fibers are brittle and severely break when bent. Rapid-shear resistant fibers (eg, Kevlar®) are rigid but expensive. SUMMARY OF THE INVENTION A fabric suitable for use in an airbag is provided. The fabric can be used for all or part of the airbag. The fabric includes a central layer having opposing first and second major surfaces. A plurality of substantially parallel spaced fibers are bonded to opposing first and second surfaces. The fibers bonded to the opposing first surface are oriented at an angle of about 45 to about 90 degrees with respect to the opposing second surface fibers. In one embodiment, the center layer comprises a thermoplastic film. The thermoplastic film is selected from the group consisting of polyester, polyolefin, polyurethane, polyamide, polyvinyl chloride, polyvinylidene chloride, fluoropolymer, block copolymer elastomer, polyester elastomer and combinations thereof. In other embodiments, the center layer comprises a heat bondable nonwoven web, such as a meltblown microfiber, spunbond, spunlace, airlaid or carded nonwoven web. In one embodiment, the fibers are high strength monofilaments or multifilaments selected from the group consisting of polyester fibers, polyamide fibers, polyolefin fibers, aramid fibers and combinations thereof. The fibers preferably have a denier in the range of about 200 to about 900, and preferably have a tenacity of about 8 g / denier or more. In one embodiment, the fibers are bonded to opposing first and second surfaces by thermal processing. In another embodiment, the fibers are bonded to opposing first and second surfaces by an adhesive applied to the first and second surfaces, the fibers, or both. The fibers are spaced at a density of about 7 to about 16 fibers per square centimeter. In one embodiment, the fabric further includes a first layer bonded to the fibers and the opposing first surface, and a second layer bonded to the fibers and the opposing second surface. The first and second layers can independently comprise a thermoplastic film, a nonwoven web, or a coating. In one embodiment, the fabric further comprises at least one laminate layer joined to the first sheet. In another embodiment, the fabric also includes at least one laminate layer joined to the second fabric. In another embodiment, there is provided a material suitable for use in an inflatable safety device. The material includes a plurality of reinforcement layers. The layer comprises a plurality of substantially parallel fibers bonded to the layer. The fibers of adjacent reinforcement layers are arranged at an angle of about 45 to about 90 degrees to one another. The cloth can be cut and sewn or joined by heat processing to form the entire airbag or a part thereof. Joining by thermal processing is generally faster and more cost effective than sewing. By appropriately selecting the material for each component of a different fabric, fabric characteristics such as strength characteristics can be customized. By selecting the number of laminate layers, layer material, fiber denier, fiber tensile strength, and number of fibers, various strength properties can be created. These strength characteristics can be tailored to the requirements of a particular airbag application, or can be tailored to the unique airbag components for producing an airbag having the desired characteristics. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an exploded front view of a fabric according to one embodiment of the present invention. FIG. 2 is an exploded front view of a fabric according to another embodiment of the present invention. 3A and 3B show diagrams of panels used to manufacture a driver side airbag using the fabric of the present invention. Preferred Embodiment FIG. 1 shows an embodiment of the airbag fabric of the present invention. The fabric 10 has a central layer 12. The central layer 12 has opposing major surfaces 14,16. Substantially parallel and spaced fibers 18 are disposed adjacent and joined to opposing major surfaces 14,16, respectively. The first and second layers 22 are disposed adjacent the fibers 18 on both sides of the central layer 12 and are joined to adjacent fibers and respective surfaces 14, 16 on both sides of the central layer 12. . The fabric 10 may be formed by adding an additional laminate 23 made of the fibers 18 bonded to the layer 22. The inner surface 24 of each layer 22 is bonded to a plurality of adjacent fibers 18 and the outer surface 26 of the adjacent layer 22 adjacent the central layer 12. The central layer 12 is made of a heat-bondable nonwoven web or thermoplastic film. The nonwoven web can be selected from various materials, such as a meltblown microweb, a spunbond web, a spunlace web, an airlaid web, and a card web. The thermoplastic film can be selected from various materials such as polyester, polyolefin, polyurethane, polyamide, PVC, fluoropolymer, block copolymer elastomer and polyester elastomer film. Further, the center layer 12 can be formed from a multilayer film or a film / nonwoven laminate. The thickness of the central layer 12 is selected for each individual application. For example, the thickness of the central layer is about 0.01 mm to 0.05 mm, preferably 0.01 mm to 0.1 mm. It may be in the range of 03 mm. When choosing the material for the layer 22 and the center layer 12, the breathability of the entire fabric 10 must be considered. For example, when a non-woven fabric having low air permeability is selected for the central layer 12, one or more layers of the layer 22 are required to be a thermoplastic film in order to impart the required air permeability to the fabric 10. There is. Fibers 18 bonded to opposing major surfaces 14, 16 are oriented at an angle of about 45 to about 90 degrees with respect to each other, depending on the desired strength characteristics of fabric 10. In the embodiment of FIG. 1, the fibers 18 bonded to opposing major surfaces 14, 16 are oriented at an angle of about 90 degrees to one another. Fibers 18 are bonded to opposing surfaces 14, 16 by thermal processing or adhesive, respectively. The fibers 18 are selected from high strength monofilaments or multifilaments, such as polyester fibers having a strength of 8.3 g / denier at 220 denier. Fiber 18 has a strength of about 8 g / denier. Examples of the fiber material include polyester, polyamide, polyolefin, and aramid fibers, or a combination thereof. The fibers have a denier in the range of about 200-900. For example, 220, 440, 630 or 840 denier fibers can be used. It is preferred to use low denier and high strength fibers. High denier fibers may be used. Fibers of different deniers may be used in combination. Layer 22 may be comprised of the materials described above for the central layer or a combination of such materials. The layer 22 may be formed by coating a film-forming material in a solution such as a thermoplastic adhesive and a hot melt adhesive. In order to obtain desired characteristics of the fabric 10, the number of layers of the laminate layer 23 of the fiber 18 and the layer 22 is selected. The fibers 18 of adjacent laminate layers are oriented at an angle of about 45 to about 90 degrees with respect to each other. It is not necessary that the number of the laminated layers 23 added on the opposing main surfaces be the same. For example, the fabric 10 may include three stacked layers on the opposing first surface 14 and two stacked layers on the opposing second main surface. Further, layer 22 or fiber 18 may be replaced with one or more laminate layers 23. Also, the fibers bonded to each of the various layers 12 and 22 can be selected from different materials, denier or strength. In another embodiment of the present invention, the fabric 10 includes a plurality of reinforcing layers 23 as shown in FIG. As described above, the reinforcing layer 23 includes a plurality of fibers bonded to the layer 22 to form a unidirectional reinforcing laminate. The two innermost reinforcement layers 30 are arranged such that the fibers 18 of the reinforcement layers 30 are located directly adjacent to each other. The layer 22 of the reinforcing layer 30 is joined to the two fiber layers of the fiber 18 and to each other. As described above, the fibers of adjacent reinforcing layers are disposed at an angle of about 45 to about 90 degrees with respect to each other. Also, the same materials or combinations of the materials described above for the fibers 18 and layers 22 may be used. In one embodiment for constructing a fabric, the laminate layer 23 is formed by laying fibers on the layer 22. The fibers 18 may be arranged by hand or unwound with a beam or creel. Generally, a comb is used to align the fibers 18 in a substantially parallel manner at a predetermined inter-fiber distance (eg, 7-16 fibers per cm). In one embodiment, layer 22 and fibers 18 are formed into unidirectional laminate layer 23 by thermal processing means such as heat or pressure. In other embodiments, an adhesive may be applied to the fibers 18, the layer 22, or both, to join the two materials to form the unidirectional laminate layer 23. Generally, the newly formed laminate layer 23 is wound on a large roll. The laminate layer can be formed by another method. For example, if layer 22 is a thermoplastic film, layer 22 may be extruded directly onto fiber 18. To form the fabric 10, at least two laminate layers 23 are arranged such that each fiber of the laminate layer is oriented at an angle of about 45 to about 90 degrees with respect to the fibers of the adjacent laminate layer. Directed to each other. To reduce the risk of occupant secondary injury when the airbag is deployed, the reinforcement layer is positioned so that the two exposed outer surfaces of the fabric are relatively smooth and have a non-frictional impact surface Let it. After the required number of laminated layers are integrally disposed, the laminated layers are joined by heat treatment or an adhesive to form a multidirectional composite laminated fabric 10. Universal strength characteristics are imparted to the fabric 10 by the number of the laminate layers 23 and the orientation of the fibers 18. A commonly used fabric strength test is the Mullen burst strength test (specified in ASTM D 3786). Suitable fabrics 10 provide a Murren burst strength of at least 1.8 MPa, preferably at least 2.4 MPa, more preferably at least 3.4 MPa. The orientation of the fibers 18 in each laminate layer 23 can be adjusted to impart strength in a particular direction to a particular portion of the airbag, thereby strengthening the entire airbag. Generally, the driver side airbag is made circular or square / rectangular. As shown in FIGS. 3A and 3B, the circular airbag is assembled with panels 40 and 41. A circular inflation gas opening 42 is cut into the panel for inflation. Around the inflation opening, there is provided a hole 43 corresponding to the position of the bolt of the metal mounting flange of the inflation unit. The panels 40 and 41 are joined by stitching or thermal processing. Bonding by thermal processing can be performed relatively quickly and easily. Depending on the application, suturing or other methods may be used to reinforce the joint by thermal processing. The two circular panels 40, 41 may also be sewn by various stitch patterns or suturing techniques. Generally, the sewn airbag is inverted through the inflation opening so that the peripheral sewn portion is disposed inside the airbag. The fabric can also be cut to form square and rectangular airbags from a single fabric sheet. Whether circular or square / rectangular, the fabric 10 can be configured with properties that match the local performance characteristics of the airbag. By choosing different sheet materials and thicknesses, fiber materials and densities, fiber orientations, and the number of layers, fabrics with superior properties can be produced. The invention is illustrated by the following example. Example 1 A unidirectional fiber laminate on a film was produced by the following method. Using a single-nip calender sold by Webex, Inc., Nina, Wiscons, 220 denier, 8.3 g / denier strength polyester fiber (1 from DuPont, Wilmington, Del.) / 220/50 R02-68 a), was laminated to 2.4dtex polyester fiber spunbonded web having a base weight 17g / m ² # 2250 of (TN Old Hickory Reemay Inc. (Reemay Corp.)). Both calender rolls were made of steel and were maintained at 150 ° C. The lamination pressure was 21.8 kN / m, and the lamination speed was about 1 m / min. The fibers were delivered from the beam to the nip and fed through the comb at 11 fibers per cm, keeping the distance between the fibers constant and arranged substantially parallel on the web. Next, a composite multidirectional laminate was manufactured from the unidirectional laminate. With the fiber side of the unidirectional laminate facing the center of the composite laminate, the unidirectional laminates were laminated such that the fibers of the laminate formed a 90 degree orientation with respect to each other. This laminate was subsequently joined at a rate of 3.3 m / min by passing through a calender nip at 150 ° C. and 21.8 kN / m. Two, three and four layer multidirectional laminates were produced in a similar manner. The respective thicknesses are 0.203 mm, 0.279 mm and 0.343 mm, and the Mullen burst strengths (measured according to ASTM D3786) are 1.8 MPa, 2. It was 6 MPa and 2.6 MPa. Example 2 A unidirectional fiber laminate on a film was produced by the following method. Spraying the film with 3M spray refillable, storable adhesive # 6091 onto a 0.125 mm thick polyethylene film (SF-40 SP from CT Films, Chippewa Halls, Wis.) , 220 denier, 8.3 g / denier strength polyester fiber (1/220/50 R02-68 from DuPont, Wilmington, DE) was laminated and the fibers were pressed manually onto the film, The adhesive was dried. Sixteen fibers were fed per cm through the comb to keep the distance between the fibers constant. Next, a composite multidirectional laminate was manufactured from the unidirectional laminate. With the fiber side of the unidirectional laminate facing the center of the composite laminate, the unidirectional laminates were laminated such that the fibers of the laminate formed a 90 degree orientation with respect to each other. Subsequently, the laminate was bonded by pressing at 135 ° C. and a pressure of 68.9 MPa for 1 minute using a carver press. In this way, a two-layer laminate was produced. The thickness of the laminate and the Mullen burst strength (measured by ASTM D3786) were 0.127 mm and 2.4 MPa, respectively. Example 3 A unidirectional fiber laminate on a film was produced by the following method. Polyester fibers (220/50 R02-68, DuPont, Wilmington, Del.) Of 220 denier and 8.3 g / denier strength are aligned through a comb and the fibers are pressed against the adhesive. It was laminated on a sheet of 3M # 927 transfer tape. Sixteen fibers were fed per cm through the comb to keep the distance between the fibers constant. Next, a composite multidirectional laminate was manufactured from the unidirectional laminate. With the fiber side of the unidirectional laminate facing the center of the composite laminate, the unidirectional laminates were laminated such that the fibers of the laminate formed a 90 degree orientation with respect to each other. The laminate is bonded to the press by applying a 0.0125 mm thick polyethylene sheet (SF-40 SP from CT Films, Chippewa Halls, Wis.) Or a small amount of baby powder to the laminate. Was prevented. Subsequently, the laminate was pressed and bonded at 135 ° C. and a pressure of 68.9 MPa for 2 minutes using a carver press. In this way, a two-layer laminate was produced. The thickness of the laminate when using a polyethylene film was 0.356 mm, and the thickness when using a powder was 0.203 mm. Each of the Murren burst strengths (measured according to ASTM D3786) was 2. It was 5 MPa and 2.3 MPa. Example 4 A unidirectional fiber laminate on a film was produced by the following method. A moisture-curable polyurethane adhesive (TS-230, manufactured by 3M) was applied to the paper web coated with silicon. The adhesive is still tacky when 220 denier, 8.3 g / denier strength polyester fiber (1/220/50 R02-68, DuPont, Wilmington, DE) is supplied to the web. As described above, the opening time of the adhesive was sufficiently long. Subsequently, the adhesive was crosslinked and crystallized by curing to bond the fibers to the adhesive. Lamination was performed using a three-roll double nip calender. The fibers were sent out of the creel to the nip, and 16 fibers per cm were fed through the comb and arranged approximately parallel on the web, keeping the distance between the fibers constant. Next, a composite multidirectional laminate was manufactured from the unidirectional laminate. With the fiber side of the unidirectional laminate facing the center of the composite laminate, the unidirectional laminates were laminated such that the fibers of the laminate formed a 90 degree orientation with respect to each other. Subsequently, the laminate is heated alone using a carver press at 149 ° C. under a pressure of 68.9 to 103 MPa for 1 to 2 minutes or a polyethylene film (SF-40) having a thickness of 0.013 mm is used. SP, CT Films, Chippewa Halls, Wis., Was added and joined by heating. A two-layer laminate was manufactured by this method. The thickness of each is 0.165 mm and 0.152 mm, and the Mullen burst strength (measured by ASTM D3786) is 2.3 MPa and 2. It was 4 MPa. Example 5 A unidirectional fiber laminate on a film was produced by the following method. Using a single-nip calender sold by Webex, Inc., Nina, Wisconsin, a continuous web of 0.0254 mm thick polyurethane film (PS8010 from Deerfield Urethane, South Deerfield, Mass.) Was applied. , 220 denier, 8.3 g / denier polyester fiber (1/220/50 R02-68 from DuPont, Wilmington, Del.). Both calender rolls were made of steel and were kept at 177 ° C. The lamination pressure was 21.8 kN / m, and the lamination speed was about 1 m / min. The fibers were sent out of the beam to the nip and fed through the comb at 11 fibers per cm and were arranged substantially in parallel on the web keeping the distance between the fibers constant. Next, a composite multidirectional laminate was manufactured from the unidirectional laminate. With the fiber side of the unidirectional laminate facing the center of the composite laminate, the unidirectional laminates were laminated such that the fibers of the laminate formed a 90 degree orientation with respect to each other. Subsequently, the laminate was passed through a calender at 150 ° C. and 21.8 kN / m at a speed of 3.3 m / min and joined. In the same manner, 2, 3, 4, and 6-layer laminates were produced. The thickness of each layer is 0.127 mm, 0.191 mm, 0.267 mm and 0.330 mm, and the Mullen burst strength (measured by ASTM D3786) is 1.8 MPa, 2.4 MPa, 3.65 MPa and 5.9 MPa, respectively. Met. Example 6 A unidirectional fiber laminate on a film was produced by the following method. A continuous web of 0.05 mm thick polyurethane film (PS8010 from Deer fields Urethane, South Deerfield, Mass.) Using a single-nip calender with a strength of 8.3 g / denier at 440 denier. Was laminated (1/440/50 R02-68 from DuPont, Wilmington, Del.). The upper calendar roll was made of silicone rubber, and the lower calender roll was made of steel. The roll temperature was kept at 150 ° C., and the rolls were laminated at a speed of about 1 m / min. The fibers were fed into the nip from a set of four parallel beams, fed through a comb at 13 fibers per cm, and arranged approximately parallel on the web, keeping the fiber spacing constant. Next, a composite multidirectional laminate was manufactured from the unidirectional laminate. With the fiber side of the unidirectional laminate facing the center of the composite laminate, the unidirectional laminate was laminated such that the fibers of the laminate formed a 90 degree orientation with respect to each other. A continuous web of 0.05 mm thick polyurethane film (PS8010 from Deerfield Urethane, Inc., South Deerfield, MA) was lined between the unidirectional laminates. Subsequently, the laminate was bonded by applying a pressure of 149 ° C. and a pressure of 68.9 to 103 MPa for 1 to 2 minutes using a carver press. The Mullen rupture strength measured by ASTM D 3786 was 4.48 MPa. Other embodiments are within the following claims.

────────────────────────────────────────────────── ─── Continuation of front page    (81) Designated countries EP (AT, BE, CH, DE, DK, ES, FI, FR, GB, GR, IE, IT, L U, MC, NL, PT, SE), OA (BF, BJ, CF) , CG, CI, CM, GA, GN, ML, MR, NE, SN, TD, TG), AP (KE, LS, MW, SD, S Z, UG), EA (AM, AZ, BY, KG, KZ, MD , RU, TJ, TM), AL, AM, AT, AU, AZ , BB, BG, BR, BY, CA, CH, CN, CZ, DE, DK, EE, ES, FI, GB, GE, HU, I L, IS, JP, KE, KG, KP, KR, KZ, LK , LR, LS, LT, LU, LV, MD, MG, MK, MN, MW, MX, NO, NZ, PL, PT, RO, R U, SD, SE, SG, SI, SK, TJ, TM, TR , TT, UA, UG, UZ, VN (72) Inventor Holzer, Mark Earl.             United States, Minnesota 55133-3427,             St. Paul, Post Office Bo             Box 33427 (72) Inventors Rowe, Robert H. Junior             United States, Minnesota 55133-3427,             St. Paul, Post Office Bo             Box 33427 (72) Inventors Rogers, John Jay.             United States, Minnesota 55133-3427,             St. Paul, Post Office Bo             Box 33427 (72) Inventors Skloeder, Kristin M.             United States, Minnesota 55133-3427,             St. Paul, Post Office Bo             Box 33427 (72) Inventor Tokachek, Miroslav             United States, Minnesota 55133-3427,             St. Paul, Post Office Bo             Box 33427

Claims (1)

[Claims]   1. A central layer having first and second opposing major surfaces; Substantially parallel, spaced apart joining the opposing first and second major surfaces. Comprising a plurality of fibers arranged in a The fibers bonded to the first major surface are at about 45 to about 90 degrees relative to the fibers at the second major surface. Airbag fabric oriented at an angle.   2. The center layer comprises a thermoplastic film, a nonwoven web, or a combination thereof. The fabric of claim 1, wherein   3. Fibers include polyester fiber, polyamide fiber, polyolefin fiber, ara High-strength monofilament selected from the group comprising mid fibers and combinations thereof Or the fabric of claim 1, comprising a multifilament.   4. The fibers have a denier in the range of about 200 to about 900 and greater than about 8 g / denier. The fabric of claim 1 having tenacity.   5. Further comprising a first layer bonded to the fibers and the opposing first surface. Item 7. The cloth according to Item 1.   6. Further comprising a second layer bonded to the fibers and the opposing second surface. Item 7. The cloth according to Item 1.   7. Further comprising at least one laminate layer joined to the first outer sheet; The fabric according to claim 5.   8. A plurality of reinforcement layers comprising a plurality of substantially parallel fibers joined to one layer With   The fibers of adjacent reinforcing layers are oriented at an angle of about 45 to about 90 degrees with respect to each other;   Materials suitable for use in inflatable restraints.   9. A first layer;   A second layer;   A first plurality of substantially parallel fibers disposed intermediate the first and second layers;   A second plurality of substantially parallel fibers disposed intermediate the first and second layers;   The second plurality of fibers forms an angle of about 45 to about 90 degrees with the first plurality of fibers. And the first layer is bonded to the second layer,     Fabric suitable for use in airbags.