JP7152011B2 - Composite seat and airbag - Google Patents

Description

The present invention relates to composite sheets and airbags.

Airbags are required to have the ability to retain air inside at a certain pressure or higher. In particular, side curtain airbags are required to have a function of preventing a passenger from being ejected from the vehicle in the event of a rollover (vehicle overturn) accident. Therefore, it is required to maintain the internal pressure of the deployed side curtain airbag for a certain period of time. For example, it is desirable that a side curtain airbag inflated to an internal pressure of 70 kPa maintains an internal pressure of 40 kPa or more after 12 seconds.

Base fabric materials used for airbags are provided with low breathability by being coated with a resin material such as silicone to reduce breathability. For example, airbag base fabrics are manufactured by coating methods such as die coating and knife coating, in which a liquid material is applied to the base fabric.

For example, a knife coating method is used as a coating method for silicon coating. With this method, it is possible to apply a thin layer of resin material or the like, but since the surface of the base cloth is rubbed with a knife, the amount of silicone adhered to the convex portions of the base cloth is smaller than that to the concave portions. In addition, the seam portion (the sewn portion that is not swollen by design) has a higher thread density than the plain weave portion because the weave structure is different. Because the thread density is different between the seam portion and the plain weave portion, when the internal pressure is applied to the airbag, the threads are wider than the plain weave portion, which has a lower thread density. As a result, air leaks from the boundary between the seam portion and the plain weave portion. occurs. For example, an airbag manufactured by adopting the knife coating method may have an internal pressure of less than 40 kPa 12 seconds after being inflated to an internal pressure of 70 kPa. The reason for this is that the stitches spread from the boundary between the seam portion and the plain weave portion of the bag, causing leakage.

In Patent Document 1 (Japanese Patent Publication No. 2003-535767), a low-permeability side curtain airbag is stored in a cylindrical module, where it is necessary to wrap a low-permeability article heavily coated with a silicone coating. It concerns the difficulty of reducing time and energy and storage volume. The document also points out that the problem of blocking (ie adhesion of different coatings) increases when such articles are packed closely together. Japanese Patent Laid-Open No. 2002-200002 describes that a side curtain airbag that is densely packed, has a low storage volume, low blocking, and low air permeability is desirable.

In order to meet the demands of such side curtain airbags, US Pat. It is an object. The invention described in US Pat. No. 4,600,002 is an airbag cushion comprising a fabric coated with an elastomeric composition, the elastomeric composition comprising at least 50% by weight of the total composition of a silicone-based material. contains. However, this fabric is coated with an elastomeric composition on the order of 2 ounces/square yard (approximately 60 g/m ² -70 g/m ² ) of fabric, so the amount of coating is still high.

Patent Document 2 (Japanese Patent Application Laid-Open No. 2007-229939) discloses that when a solvent-free silicone that does not use any solvent for dilution is used, the coating surface tends to have a mirror surface structure, is glossy, and adheres easily. It is described that there is a tendency to easily form a high coated surface. Patent document 2 describes that in this case, due to the high adhesiveness, a high frictional force is likely to occur between the base fabric surfaces of the airbag. A method of obtaining a composite sheet having a coating surface with low adhesion and a low surface friction coefficient without sprinkling fine powder such as talc on the coating surface or adding a filler that imparts lubricity to the coating liquid. As such, Patent Literature 2 describes mechanically forming an uneven shape on a coated surface of silicone. However, in the composite sheet of Patent Document 2, about 60 g/m ² of silicone is applied to the substrate, and the amount of silicone used is large. The reason for the large amount of silicone is presumed to be that it is necessary to coat the silicone thickly in order to mechanically provide the concave-convex shape on the silicone-coated surface. In addition, since silicone is provided on the base material by a coating method, it is thought that the amount of silicone inevitably increased in order to suppress air leakage.

Apart from the silicon coating method, a lamination method is used in which a film is heat-pressed and adhered to a base fabric. The lamination method includes, for example, a method in which a laminated film is pressed with a hot roll to fuse.

The lamination method tends to be slower and more costly than the knife coating method. Manufacturing equipment, such as wide-width extruders such as T-die extruders used to manufacture laminated films, is also costly. On the other hand, this method has the advantage of less air leakage from the processed surface when internal pressure is applied to the airbag, compared to the silicon coating method.

US Pat. No. 2008/0075903 A1 describes a method for manufacturing an airbag cushion, which method is based on a multi-component film comprising a thermoplastic adhesive resin layer and a resinous barrier layer. It includes a process of heat-sealing to the material. By using materials having different melting points as materials for the adhesive resin layer and the barrier layer, the barrier layer can be heat-sealed to the substrate via the adhesive layer. This method requires the step of laminating the resulting film to a substrate after the step of forming the multi-component film, such as by using an extruder.

Japanese Patent Publication No. 2003-535767 JP 2007-229939 A United States Patent Publication US 2008/0075903 A1

SUMMARY OF THE INVENTION An object of the present invention is to provide a composite sheet having excellent slip performance, and an airbag which is highly storable and has excellent deployment function and internal pressure retention performance.

According to the present invention, a fabric layer, a first side provided on said fabric layer and facing said fabric layer, a second side behind said first side, said a first resin layer having a plurality of island-shaped recesses recessed from the second surface toward the first surface and containing a thermoplastic first resin; and at least a portion of the second surface. a second resin layer filled in the plurality of recesses and containing a second resin containing silicone , wherein the second surface has 9 or more and 81 or less of the plurality of recesses per 1 cm ² A composite sheet is provided having:

Further, according to the present invention, there is provided an airbag comprising a bag portion and a gas introduction portion for introducing gas into the bag portion. The bag portion is formed from the above composite sheet so that the base fabric layer is positioned on the inner surface thereof.

The above composite sheet has excellent slip performance. In addition, an airbag using a composite sheet has high storability, excellent deployment function, and excellent internal pressure retention performance.

1 is a cross-sectional view schematically representing an example composite sheet; FIG. A formula representing the curing mechanism of an example silicone material. 1A-1D are schematic representations of portions of an example method of manufacturing a composite sheet; FIG. 4 is a schematic representation of another portion of an example method of manufacturing a composite sheet; 1 is a plan view schematically showing an example airbag; FIG. 2 is a plan view photograph of the embossed sheet used in Example 1. FIG. 2 is a plan photograph of the composite sheet produced in Example 1. FIG. FIG. 8 is an enlarged plan view of the composite sheet shown in FIG. 7; 4 is a scanning electron micrograph showing a cross section of the composite sheet produced in Example 1. FIG. Sectional drawing which represents a friction test roughly. 4 is a graph showing internal pressure retention performance of the airbags produced in Example 5 and Comparative Example 5. FIG.

A composite sheet and an airbag according to embodiments will be described below with reference to the drawings.

(First embodiment)
A composite sheet according to an embodiment includes a base fabric layer, a first resin layer, and a second resin layer. The first resin layer is provided on the base fabric layer. The first resin layer has a first surface facing the base fabric layer, a second surface on the back side of the first surface, and a plurality of recesses recessed from the second surface toward the first surface. is doing. The first resin layer contains a first thermoplastic resin. At least part of the second resin layer fills the plurality of recesses on the second surface. The second resin layer contains a second resin containing silicone.

FIG. 1 shows a cross-sectional view schematically representing an example composite sheet. The composite sheet 1 includes a base fabric layer 2 , a first resin layer 3 and a second resin layer 4 . In the illustrated example, the base fabric layer 2 is a woven fabric made of yarns 2a. The first resin layer 3 has a first surface 3a and a second surface 3b. The first surface 3 a of the first resin layer 3 faces the base fabric layer 2 . The first surface 3a follows the uneven shape formed on the surface of the base fabric layer 2 by the threads 2a. The second surface 3b has a plurality of recesses 5 recessed toward the first surface 3a on its surface. In FIG. 1, one of the recesses 5 is illustrated. The second resin layer 4 is provided on the second surface 3 b of the first resin layer 3 . A part of the second resin layer 4 enters the recess 5 on the second surface 3 b and fills the recess 5 .

The recesses 5 on the second surface 3b of the first resin layer 3 may be provided by embossing the first resin layer 3, for example. It is desirable that the second surface 3b has a plurality of concave portions 5 of 9 or more and 81 or less per 1 cm ² . Moreover, it is desirable that the ratio of the plurality of concave portions 5 to the area of the second surface 3b is 7% or more and 64% or less.

The second resin layer 4 contains a second resin, at least a part of which fills the recesses 5 . By filling the concave portion 5 with the second resin, the distribution of the second resin contained in the second resin layer 4 is concentrated in the concave portion 5 . As a result, the surface of the second resin layer 4 (the surface on the back side with respect to the base fabric layer 2 and the first resin layer 3) can have moderate unevenness while the thickness of the entire composite sheet 1 is reduced. The supported amount of the second resin layer 4 provided on the second surface 3b of the first resin layer 3 may be, for example, 5 g/m ² or more and 50 g/m ² or less. The supported amount of the second resin layer 4 may be uniform over the planar direction, or may not be uniform. The thickness of the composite sheet, that is, the total thickness T of the base fabric layer 2, the first resin layer 3 and the second resin layer 4 can be, for example, 0.1 mm or more and 1 mm or less.

The composite sheet 1 having the structure shown in FIG. 1 has excellent slip performance. Therefore, the composite sheet 1 is suitable as a material for forming an airbag. Since the second resin layer 4 has undulations on the outermost surface of the composite sheet 1, there is little adhesion between the surfaces of the second resin layer 4 when the composite sheet 1 is folded. Therefore, less friction occurs on the surface of the second resin layer 4 . Since the composite sheet 1 slides well, it is possible to rapidly deploy the airbag that is folded or rolled up small when stored.

In addition, since the composite seat 1 is thin as a whole, it is easy to store, and the degree of freedom in designing the vehicle on which the airbag is mounted is improved. In addition, since the composite sheet 1 has good sliding performance, it is possible to maintain a good deployment function even if the airbag is tightly packed.

In addition, by using the composite sheet 1, it is possible to obtain an airbag with high internal pressure retention performance. In other words, the composite sheet 1 is also suitable for application to side curtain airbags. The first resin layer 3 adheres to the base fabric layer 2 while following the surface shape formed by the threads 2a. The first resin layer 3 prevents the opening of the weave in the base fabric layer 2 and suppresses gas leakage. Therefore, the composite sheet 1 has high airtightness.

Next, the base fabric layer, the first resin layer, and the second resin layer will be described in detail.

A woven fabric or a non-woven fabric, for example, can be used as the base fabric layer. Examples of materials for the base fabric layer include base fabrics made of resin materials such as polyester, polyamide, and nylon. Alternatively, glass cloth or the like may be used as the base fabric layer. The base fabric layer can have a thickness of, for example, 0.1 mm or more and 0.5 mm or less.

Examples of the first resin contained in the first resin layer include thermoplastic resins such as polyurethane, polyester, polyethylene, polyethylene terephthalate (PET), and nylon. The first resin layer can have a thickness of, for example, 20 μm or more and 500 μm or less.

The first resin layer may contain one or more layers. That is, the first resin layer may be a single layer or a laminate including a plurality of laminated layers. When the first resin layer includes multiple layers, each layer may include a different first resin. For example, the first resin layer can be a multi-component film consisting of multiple layers of different materials.

The second resin contained in the second resin layer contains silicone (silicone rubber). The second resin can include thermosetting and thermoplastic materials, such as elastomers and other resin materials, in addition to silicone. Specific examples of materials other than silicone include elastomers such as chloroprene, chlorosulfonated olefins, polyamide elastomers, polystyrene butadiene, nitrile rubbers, fluororubbers, and polyurethanes. As the second resin, silicone can be used in combination with one or more of the above materials. Alternatively, one or more of the above materials can be used as the second resin instead of silicone.

An example of silicone that can be used for the second resin will be described in detail. FIG. 2 shows an equation representing the curing mechanism of an example silicone material. Specifically, FIG. 2 shows the curing mechanism of an addition-curable methylvinyl-based silicone rubber having a backbone formed of siloxane polymer. Curing proceeds by an addition reaction by heating in the presence of a platinum (Pt) catalyst.

In addition to the second resin, the second resin layer may contain a filler. For example, the second resin layer may contain a filler that imparts flame retardancy or further improves sliding performance (low friction).

The second resin layer may contain one or more layers. That is, the second resin layer can be a single layer or a laminate including multiple layers that are laminated. When the second resin layer includes multiple layers, each layer may include a different second resin.

As described above, the composite sheet has excellent sliding performance, is thin, and therefore has high storability and high airtightness. Therefore, the composite sheet can be suitably used for airbags. Airbags include side curtain airbags.

Next, a method for manufacturing the composite sheet will be described.

The base fabric layer and the first resin layer are laminated to produce a laminated base material. At this time, recesses are formed in the second surface of the first resin layer. A second resin layer is formed by applying a second resin to the second surface of the first resin layer and curing the second resin.

An example method of manufacturing a composite sheet is described with reference to FIGS.

FIG. 3 is a schematic representation of part of an example method of manufacturing a composite sheet, specifically a cross-sectional view representing the manufacture of a laminate substrate. For example, using a thermal transfer press, the release film 13, the embossed sheet 14, the first resin layer 3, and the base fabric layer 2 are stacked in this order on the pressure belt 12, and heated by the heating/pressure roll 11. By pressing while pressing, the first resin layer 3 and the base fabric layer 2 are integrated to obtain the laminate base material 6 .

The heating temperature is, for example, 130° C. or higher and 150° C. or lower. The press pressure is, for example, 0.05 MPa or more and 1 MPa or less. The conveying speed is, for example, 0.1 m/min or more and 30 m/min or less.

As the first resin layer 3, for example, a resin film made of the plastic first resin described above can be used. As the base fabric layer 2, for example, the above base fabric materials (woven fabric, non-woven fabric, glass cloth, etc.) can be used.

The embossed sheet 14 has an uneven main surface. The embossed sheet 14 has a plurality of protruding portions on the processed surface 14a of its main surface that contacts the second surface 3b of the first resin layer 3 . The processed surface 14a of the embossed sheet 14 may include a plurality of protrusions of 9 or more and 81 or less per 1 cm ² .

The first resin layer 3 and the base fabric layer 2 are integrated by heating and pressurizing using the heating-pressing roll 11, and at the same time, the processed surface 14a of the embossed sheet 14 becomes the second surface of the first resin layer 3. 3b is pressurized. At this time, a plurality of protrusions on the processed surface 14a are transferred to the surface of the second surface 3b as a plurality of recesses. The shape and size of the recess can be controlled by adjusting the shape and size of the protruding portion of the processed surface 14a and the press pressure during transfer. Thus, the second surface 3b of the first resin layer 3 is embossed to provide a plurality of concave portions.

FIG. 4 is a schematic diagram showing another part of an example method of manufacturing a composite sheet, specifically a cross-sectional diagram showing formation of a second resin layer on a laminate substrate. For example, a batch coater is used to apply a predetermined amount of coating material C containing the second resin onto the laminate substrate 6, and the coating material C is cured by heating to form the second resin layer 4. FIG. The coating material C is applied onto the second surface 3 b of the first resin layer 3 .

Specifically, the laminate substrate 6 including the base fabric layer 2 and the first resin layer 3 integrated with the base fabric layer 2 and provided with recesses on the second surface 3b by embossing is applied to the backup roll 21. transported by The conveying speed is, for example, 0.5 m/min. A coating material C is applied to the second surface 3b of the first resin layer 3 by using a coating knife 22, for example. By adjusting the distance between the second surface 3b and the coating knife 22, the coating amount of the coating material C can be controlled. At least part of the coating material C applied to the second surface 3b fills the concave portions provided on the second surface 3b. A large proportion of the coating material C can fill the recesses.

The coating material C contains the second resin described above. The coating material C may contain a diluent such as an organic solvent in addition to the second resin. Alternatively, a coating material C containing no solvent may be used.

The second resin layer 4 is formed by curing the coating material C applied to the second surface 3b of the first resin layer 3 by heating. The heating temperature can be 180° C., for example. The heating temperature is appropriately adjusted according to the curing temperature of the second resin contained in the coating material C and the presence or absence of materials other than the second resin.

In the composite sheet thus obtained, the second resin layer 4 is provided on the laminate substrate 6 formed by integrating the base fabric layer 2 and the first resin layer 3, and at least part of the second resin is A plurality of concave portions on the second surface 3 b of the first resin layer 3 are filled with the resin.

(Second embodiment)
An airbag according to an embodiment includes a bag portion and a gas introduction portion. The bag portion is formed from the composite sheet previously described. The bag portion is formed so that the base fabric layer of the composite sheet is positioned on the inner surface of the bag portion. Gas is introduced into the bag from the gas introduction section.

FIG. 5 shows a plan view schematically showing an example airbag. The airbag 30 includes a bag portion (inflatable portion) 31 and a gas introducing portion (inflator port) 32 . The airbag 30 may also include a joint portion (non-inflatable portion) 33 depending on the design.

The bag portion 31 is a bag-shaped portion of the airbag 30 . The gas introduction portion 32 is a portion connected to an inflator that generates gas for inflating the bag portion 31 when the airbag 30 is deployed.

In the airbag 30, for example, the base fabric layer side of the composite sheet faces the inside of the airbag 30, that is, the base fabric layer serves as the inner surface of the bag, and the second resin layer side serves as the outer surface of the airbag 30. and the bag portion 31 is formed. A junction 33 may be formed adjacent to the suture site. In other words, the position and size of the joint portion 33 can be adjusted by the stitching position when forming the bag portion 31 .

When the airbag 30 is deployed, an inflator (not shown) connected to the gas introduction portion 32 generates bag deployment gas, and the bag deployment gas is introduced into the airbag 30 via the gas introduction portion 32. be done. An inflator is mounted on a vehicle such as an automobile, for example. When the bag deployment gas is introduced into the airbag 30 from the inflator via the gas introduction portion 32, the bag portion 31 stores the gas from the inflator inside and inflates. The joint 33 does not swell even when gas is introduced.

Until the inflator is activated and the airbag 30 is deployed, the airbag 30 can be tightly folded or tightly rolled and stored, for example, inside the vehicle. In the stowed state, the outer surfaces of the airbag 30 (for example, the surface of the second resin layer) can be in close contact with each other. Since the bag portion 31 is formed of the above-described composite sheet, the airbag 30 is highly storable, deployable, and retains internal pressure. Since these performances are high, the airbag 30 can be suitably used as a side curtain airbag.

More preferably, in addition to the bag portion 31, the gas introduction portion 32 and the joint portion 33 are formed of a composite sheet. It is preferable that the second resin layer is positioned on the outer surface of the airbag 30 for any part.

The airbag can be obtained, for example, by One-Piece Woven (OPW, also called tubular weave). In the case of a monolithic weave, the bag portion, gas inlet portion, and joint portion may all be formed from one composite sheet. A monolithic airbag can be formed without stitching, further reducing air leakage. A monolithic airbag may include a region where two overlapping sheets are fastened together with thread folds instead of being stitched together. A joint may be formed adjacent to the portion being fastened.

Examples are described below. Specifically, a coating material containing a second resin is applied to a base fabric layer laminated with various films (first resin layer) (laminated base material), and the coefficient of friction is adjusted according to the presence or absence of embossing. By measuring, the effect of embossing was confirmed.

[Production of composite sheet]
(Comparative example 1)
As a base fabric layer, a base cloth (466 dtex×96 filaments, 57×49 filaments/inch, manufactured by HAILIDE) woven from polyester fibers was prepared. The thickness of the base fabric layer was 0.3 mm. A thermoplastic polyurethane film (manufactured by Ding Zing, thickness 50 μm) was prepared as the first resin layer. The first resin layer was laminated on the base fabric layer using a thermal transfer press (HP-1600 manufactured by Hashima Co., Ltd.) to prepare a laminated base material. No embossed sheet was used in making the laminate substrate.

Silicone (addition-curing silicone manufactured by Elkem Silicones) was prepared as a coating material. 20±10 g/m ² of this silicone was applied to the first resin layer side of the laminate substrate and heated to form a second resin layer.

A composite sheet was thus produced.

(Example 1)
An embossed sheet shown in FIG. 6 was prepared. FIG. 6 is a plan photograph of the embossed sheet viewed from the processing surface side. In the photograph shown in FIG. 6, a lattice pattern is drawn with black lines 15 for the purpose of facilitating the explanation. The size of one square in the lattice pattern is 1 cm ² . On the processed surface of the embossed sheet shown in FIG. 6, 25 apexes 14b of the protruding portion which can be visually recognized as white diamonds are observed per 1 cm ² . Each protrusion has the shape of a square pyramid. Concavities around black spots 14c are also seen on the processed surface of the embossed sheet. The peaks 14b of the protrusions and the black spots 14c, which are the centers of the recesses, are alternately arranged at intervals of about 1.7 mm.

Using the same base fabric layer and first resin layer as in Comparative Example 1, and this embossed sheet, a laminate base material was produced by the method shown in FIG. That is, the embossing is performed by simultaneously applying the embossing when laminating the first resin layer on the base fabric layer using the embossed sheet, and transferring the protruding portion of the processed surface of the embossed sheet to the second surface of the first resin layer. A base material was produced.

A composite sheet was produced by the same procedure as in Comparative Example 1, except that an embossed laminate substrate was used.

(Comparative example 2)
A thermoplastic polyester film (manufactured by Nihon Matai, thickness 50 μm) was prepared as the first resin layer. A laminate base material was produced in the same manner as in Comparative Example 1, except that the material of the first resin layer was changed to the polyester film.

A silicone similar to Comparative Example 1 was prepared. 20±10 g/m ² of this silicone was applied to the first resin layer side of the laminate substrate and heated to form a second resin layer. A composite sheet was thus produced.

(Example 2)
A first resin layer similar to that of Comparative Example 2 was prepared. An embossed sheet similar to that of Example 1 was prepared. An embossed laminate substrate was produced by the same procedure as in Example 1, except that the material of the first resin layer was changed. A composite sheet was produced in the same manner as in Comparative Example 2, except that the obtained laminate substrate was used.

(Comparative Example 3)
As a base cloth layer, a base cloth (manufactured by Asahi Kasei Corporation, 470 dtex×72 filaments, 51×51 filaments/inch) woven from polyamide fibers was prepared. The thickness of the base fabric layer was 0.3 mm. A laminate base material was produced in the same manner as in Comparative Example 1, except that the base cloth material was changed to the polyamide cloth.

A silicone similar to Comparative Example 1 was prepared. 20±10 g/m ² of this silicone was applied to the first resin layer side of the laminate substrate and heated to form a second resin layer. A composite sheet was thus produced.

(Example 3)
A base fabric layer similar to that of Comparative Example 3 was prepared. An embossed sheet similar to that of Example 1 was prepared. An embossed laminate base material was produced by the same procedure as in Example 1, except that the base fabric material was changed. A composite sheet was produced in the same manner as in Comparative Example 3, except that the obtained laminate substrate was used.

(Comparative Example 4)
A first resin layer similar to that of Comparative Example 2 was prepared. A base fabric layer similar to that of Comparative Example 3 was prepared. A laminate base material was produced in the same procedure as in Comparative Example 1, except that the materials of the first resin layer and the base fabric layer were changed.

A silicone similar to Comparative Example 1 was prepared. 20±10 g/m ² of this silicone was applied to the first resin layer side of the laminate substrate and heated to form a second resin layer. A composite sheet was thus produced.

(Example 4)
A first resin layer similar to that of Comparative Example 2 was prepared. A base fabric layer similar to that of Comparative Example 3 was prepared. An embossed sheet similar to that of Example 1 was prepared. An embossed laminate base material was produced by the same procedure as in Example 1, except that the materials of the first resin layer and the base fabric layer were changed. A composite sheet was produced in the same manner as in Comparative Example 4, except that the obtained laminate substrate was used.

[observation]
The produced composite sheet was observed as follows.

In the above examples and comparative examples, transparent colored silicone was used as the second resin, so a pigment was added to the composite sheet for the purpose of improving the visibility of the second resin. The plane of the composite sheet was observed from the second resin layer side to confirm the distribution of the second resin.

As a specific example, the result of confirming the composite sheet produced in Example 1 will be described. 7 is a plane photograph of the composite sheet produced in Example 1. FIG. FIG. 8 is an enlarged plan view photograph of the composite sheet shown in FIG. FIG. 8 corresponds to the center and periphery of FIG. As shown in FIGS. 7 and 8, the color of the pigment is darker at the position of the concave portion 5, indicating that a large amount of silicone adheres to that position. Therefore, it can be confirmed that the concave portion 5 is filled with silicone. Also, the arrangement of the concave portions 5 corresponds to the arrangement of the peaks 14b of the protrusions on the processing surface of the embossed sheet used for embossing. By comparing the area of the darkly colored portion and the lightly colored portion, it is possible to confirm the area ratio occupied by the concave portions 5 on the second surface.

Similarly, in the composite sheet produced in Example 2-4, the color of the pigment at the position of the concave portion 5 was darkened, and it was confirmed that the concave portion 5 was filled with silicone. On the other hand, in the composite sheet produced in Comparative Example 1-4, the color depth of the pigment was uniform over the entire surface (not shown). In Comparative Example 1-4, since the first resin layer was not embossed, the entire flat film surface without concave portions was colored, and it is believed that the silicone was evenly coated.

Subsequently, the composite sheet was cut to obtain an observed cross section. At this time, the cross section of the concave portion 5 confirmed by planar observation was included in the cut observation cross section. A conductive double-sided tape was attached to the base fabric layer side of the cut out composite sheet, and the composite sheet was fixed to a sample stage of an electron microscope. The observed cross section was observed with a scanning electron microscope (TM-3030, manufactured by Hitachi High-Technology Co., Ltd.).

9 is a scanning electron micrograph showing a cross section of the composite sheet produced in Example 1. FIG. The composite sheet 1 is fixed to the sample table 40 with a conductive double-sided tape 41 attached to the base fabric layer 2 side. It can be seen that in the composite sheet 1 , the first resin layer 3 follows the uneven shape formed by the threads forming the base fabric layer 2 . In particular, the first resin layer 3 is in close contact with the base fabric layer 2 at positions corresponding to the recesses 5 . As a result of mapping the observed cross section by Energy Dispersive X-ray Spectroscopy (EDX) (not shown), the Si element distribution was concentrated in the portion corresponding to the concave portion 5 . Also from this, it was confirmed that the concave portion 5 was filled with silicone. A large portion of the second resin layer 4 is filled with the recesses 5 having a width of about 1.7 mm.

[evaluation]
The coefficient of friction of the composite sheets produced in each example and comparative example was evaluated as follows. Specifically, the static friction coefficient and dynamic friction coefficient were measured by a method according to ISO-8295 (1995).

Specifically, we tested as follows. A universal testing machine TENSILON RTC manufactured by A&D Co., Ltd. was used as the test equipment. An outline of the test method is shown in FIG.

FIG. 10 is a cross-sectional view schematically showing the friction test. Two composite sheets 1 were set on a base plate 51 so that the second resin layers 4 faced each other, and a sliding piece 52 was placed thereon. As the sliding piece 52, a SUS (Steel Use Stainless) block with a contact area of 63 mm×63 mm and a weight of 200 g was used. A static friction coefficient and a dynamic friction coefficient were obtained based on the measured values when the upper composite sheet 1 was pulled at 100 mm/min using a wire 53 connected to a load cell (not shown) via a pulley 54 .

The details of the preparation of the composite sheets and the results of the friction test in each of Examples and Comparative Examples are summarized in Table 1 below. Details of the preparation of the composite sheet include the material and thickness of the base fabric layer, the material of the first resin layer, whether or not the second surface of the first resin layer is embossed, and the area of the second surface of the concave portion. percentage, the type of coating material and the actual amount applied, and the thickness of the composite sheet. The actual amount of coating material applied was determined from the difference in weight of the laminate substrate before and after coating. This weight does not include the weight of the first resin layer. The thickness of the composite sheet is the total thickness of the base fabric layer, the first resin layer and the second resin layer. The results of the friction test are static friction coefficient and dynamic friction coefficient.

The composite sheet produced in Comparative Example 1 and the composite sheet produced in Example 1 differ in whether or not the first resin layer was embossed. The coating amount of the coating material (silicone) applied to the laminate substrate and the thickness of the resulting composite sheet were comparable between the two. On the other hand, compared with the composite sheet of Comparative Example 1, the composite sheet of Example 1 was lower in both static friction coefficient and dynamic friction coefficient. In other words, as a result of embossing the second surface of the first resin layer, the sliding performance was improved.

The composite sheet produced in Comparative Example 2 and the composite sheet produced in Example 2 were similar to the comparison between Comparative Example 1 and Example 1, in terms of whether or not the first resin layer was embossed. different. In a comparison between Comparative Example 2 and Example 2, in which polyester was used as the material for the first resin layer instead of polyurethane, the coating amount of the coating material and the thickness of the composite sheet were about the same, but the embossing Both static and dynamic friction coefficients were lower for the composite sheet of Example 2 in which .

In the comparison of Comparative Examples 3 and 3 using a polyamide base fabric and a polyurethane film, and in the comparison of Comparative Examples 4 and 4 using a polyamide base fabric and a polyester film, the comparison of Comparative Examples 1 and 1 Similarly, the embossed composite sheet had lower static and dynamic friction coefficients.

As the above results show, by embossing the second surface of the first resin layer and filling the resulting embossments (recesses) with the second resin, a composite sheet having excellent slip performance can be obtained. .

An airbag was produced using the composite sheet, and the internal pressure retention performance was tested.

[Production of airbag]
(Comparative Example 5)
An OPW bag made of a polyamide base fabric (470 dtex x 72 filaments, 56 x 48 filaments/in) was prepared. Both sides of the OPW pouch were coated with 55 g/m ² of silicone per side. After curing the silicone by heating, the resulting sheet of material was used to fabricate OPW airbags similar in shape to that shown in FIG.

(Example 5)
An OPW bag made of a polyester base fabric (466 dtex x 96 filaments, 57 x 49 filaments/in) was prepared. A thermoplastic polyester film (first resin layer) similar to that of Example 2 was prepared. An embossed sheet similar to that used in Examples 1-4 was prepared. Both sides of the OPW pouch were laminated with a thermoplastic polyester film. During lamination, the polyester film was embossed using an embossed sheet. One side of the polyester film was coated with 14 g/m ² of silicone, and the other side on the back side was coated with 30 g/m ² of silicone. After curing the silicone by heating, the resulting composite sheet was used to fabricate an OPW airbag having a shape similar to that shown in FIG.

[evaluation]
The internal pressure retention performance of the airbags produced in Comparative Example 5 and Example 5 was evaluated as follows.

An air supply nozzle was connected to the inflator port of the airbag, and the valve was closed after the internal pressure was applied to the air pressure of 50 kPa. Internal pressure data was collected after the time had elapsed since the valve was closed.

FIG. 11 shows a graph representing the internal pressure retention performance of the airbags produced in Example 5 and Comparative Example 5. As shown in FIG. In the graph of FIG. 11, the horizontal axis indicates elapsed time after closing the valve, and the vertical axis indicates the internal pressure of the airbag. A solid line 61 indicates changes in internal pressure in the airbag manufactured in Comparative Example 5. FIG. A dotted line 62 indicates changes in internal pressure in the airbag manufactured in Example 5. FIG.

Table 2 below summarizes the internal pressure retention rate for each 20 seconds of elapsed time. Specifically, it shows the internal pressure of the airbag 20 seconds, 40 seconds, 60 seconds, and 80 seconds after the air valve is closed and the retention rate for the internal pressure (initial value) when the valve is closed.

From the above results, it can be seen that the airbag produced in Example 5 has higher internal pressure retention performance than the airbag produced in Comparative Example 5.

In addition, in the airbag produced in Example 5, the coating amount of silicone was different between both surfaces. When air leakage on each surface was visually confirmed, no leakage was found.

As described above, the composite sheet obtained by laminating the first resin layer on the base fabric layer, embossing, and filling the embossing with the second resin has a low coefficient of friction, and furthermore, using this composite sheet, the internal pressure retention performance is high. You can get an airbag.
The invention described in the original claims of the present application is appended below.
[1] a base fabric layer;
A first surface provided on the base fabric layer and facing the base fabric layer, a second surface on the back side of the first surface, and from the second surface toward the first surface a first resin layer having a plurality of concave recesses and containing a thermoplastic first resin;
a second resin layer at least partially filled in the plurality of recesses on the second surface and containing a second resin containing silicone;
A composite sheet comprising:
[2] The composite sheet according to [1], wherein the second surface has 9 or more and 81 or less of the plurality of recesses per 1 cm ² .
[3] The composite sheet according to [1] or [2], wherein the proportion of the area of the second surface occupied by the plurality of recesses is 7% or more and 64% or less.
[4] The composite sheet according to any one of [1] to [3], wherein the second resin layer on the second surface has a carrying amount of 5 g/m ² or more and 50 g/m ² or less.
[5] The composite sheet according to any one of [1] to [4], wherein the composite sheet has a thickness of 0.1 mm or more and 1 mm or less.
[6] The composite sheet according to any one of [1] to [5], wherein the base fabric layer comprises a woven fabric or non-woven fabric.
[7] A bag portion and a gas introducing portion for introducing gas into the bag portion, wherein the bag portion has any one of [1] to [6] so that the base fabric layer is positioned on the inner surface. An airbag formed from the composite sheet according to .
[8] The airbag according to [7], which is a side curtain airbag.

DESCRIPTION OF SYMBOLS 1... Composite sheet 2... Base fabric layer 3... 1st resin layer 4... 2nd resin layer 5... Recess 6... Laminated base material 11... Heating-pressure roll 12... Pressure belt 13 Release film 14 Embossed sheet 14a Processed surface 14b Vertex 21 Backup roll 22 Coating knife 30 Airbag 31 Bag portion 32 Gas introduction portion 33 Joining portion , 40... Sample stand, 41... Conductive double-sided tape, 51... Base plate, 52... Sliding piece, 53... Wire, 54... Pulley, C... Coating material.

Claims (6)

a base fabric layer;
A first surface provided on the base fabric layer and facing the base fabric layer, a second surface on the back side of the first surface, and from the second surface toward the first surface a first resin layer having a plurality of concave island-shaped recesses and containing a thermoplastic first resin;
a second resin layer at least partially filled in the plurality of recesses on the second surface and containing a second resin containing silicone ;
The composite sheet , wherein the second surface has 9 or more and 81 or less of the plurality of recesses per 1 cm ² . The composite sheet according to claim 1 , wherein the second resin layer on the second surface has a loading amount of 5 g/ ^m2 or more and 50 g/ ^m2 or less. 3. The composite sheet according to claim 1, wherein the composite sheet has a thickness of 0.1 mm or more and 1 mm or less. The composite sheet according to any one of Claims 1 to 3 , wherein the base fabric layer comprises a woven fabric or a nonwoven fabric. The composite sheet according to any one of claims 1 to 4 , comprising a bag portion and a gas introduction portion for introducing gas into the bag portion, wherein the base fabric layer is positioned on the inner surface of the bag portion. An airbag formed from 6. The airbag of claim 5 , which is a side curtain airbag.

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