JP2007038693A - Manufacturing method of highly airtight airbag - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of an airbag capable of preventing occurrence of deformation regardless of using an adhesive sealant, high in airtightness and excellent in cost performance. <P>SOLUTION: This manufacturing method of the airbag having a process to join foundations at least one side surfaces of which are covered with elastomer through the adhesive sealant by accumulating or folding them is constituted of a process to preliminarily heat-treat the foundations, a process to arrange the sealant on the preliminarily heat-treated foundations and the process to accumulate or fold the foundations facing each other so that the adhesive sealant is arranged between the foundations. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method of manufacturing an airbag that protects an occupant from an impact at the time of a vehicle collision, and more particularly, to a method of manufacturing an airbag having high bag airtightness and excellent cost performance. is there.

  The airbag device includes a sensor that detects a rapid deceleration such as a vehicle collision, an inflator that generates a high-pressure gas in response to a signal from the sensor, and an air that is deployed by the high-pressure gas from the inflator to mitigate a passenger's impact. It is comprised from the diagnostic circuit which judges whether a bag and an airbag system are functioning normally.

  In recent years, not only driver airbags and passenger airbags but also various types of airbags, such as side airbags and curtain shield airbags corresponding to side collisions, have begun to spread. Among them, curtain shield airbags that support the rollover of a vehicle, in particular, do not hold the internal pressure of the bag for a long time for several seconds while the vehicle rolls over in order to absorb the impact on the head of the vehicle occupant. is needed. Therefore, in order to deal with these various types of airbags, there is an urgent need to develop an airbag that can increase the airtightness of the airbag and extend the duration of inflation more than ever.

  As a configuration of such an airbag, Patent Document 1 discloses a structure in which edges of two panels are joined by stitching with a thread and adhesion with an elastic adhesive. Further, Patent Document 2 is used to fabricate an airbag formed in a bag shape by superposing the treated surfaces of a base fabric impregnated and / or coated with silicone rubber, and bonding or sewing peripheral portions to each other. An addition reaction curable silicone that is a silicone rubber composition for a sealing material to be applied to the bonding part or the sewing part, and which contains an aluminum hydroxide powder and gives a cured silicone rubber having an elongation at break of 1000% or more. A silicone rubber composition for airbag sealants comprising a rubber composition is disclosed. By combining these techniques of Patent Documents 1 and 2, an air bag having further excellent airtightness can be obtained.

JP 2001-1854 A JP 2004-322890 A

  By the way, the addition reaction curable silicone rubber composition is mainly of a type that cures at room temperature. In this case, if an excessive external force is applied to the adhesive seal portion before curing at room temperature, the adhesive seal portion may be deformed. In addition, not only excessive external force but also synthetic fiber fabric, especially nylon fiber fabric as the base fabric, the base fabric tends to wrinkle, and deformation of the adhesive seal part due to recovery of wrinkles while the adhesive seal part is cured Can occur. Due to such deformation of the adhesive seal portion, gas leakage occurs when the airbag is deployed, and the desired deployment performance cannot be obtained. Therefore, the airbag in which the deformation of the adhesive seal portion occurs is lost, and the productivity is inferior.

  The present invention solves the above problems, and despite the use of an adhesive sealing material, a method of manufacturing an airbag that is less likely to be deformed, highly airtight, and excellent in cost performance. The purpose is to provide.

  That is, the present invention relates to a method for manufacturing an airbag having a step of overlapping or folding a base fabric coated with an elastomer on at least one side and joining the base fabric via an adhesive sealant, and preheating the base fabric. A step of disposing an adhesive sealant on the preheated base fabric, and overlapping or folding the opposing base fabrics so that the adhesive sealant is disposed between the base fabrics. The present invention relates to a method for manufacturing an airbag comprising steps.

  It is preferable that the temperature range of the said preheating process is 60-150 degreeC.

  It is preferable that the apparatus for the preheating treatment includes an opposing pressure roller.

  It is preferable that an iron shrinkage rate of the base fabric is within ± 2%.

  According to the manufacturing method of the present invention, the base fabric is smoothed by the step of preheating the base fabric, so that subsequent deformation of the adhesive seal portion is suppressed, manufacturing loss is reduced, and airtightness is high. Bags can be manufactured with high cost performance.

  Further, by setting the temperature range of the preheating treatment to 60 to 150 ° C., the base fabric can be smoothed effectively.

  In addition, the provision of the pressure roller facing the preheating device enables continuous processing, which is advantageous in terms of cost.

  Moreover, a highly accurate airbag with little dimensional change can be manufactured by using the base fabric whose iron shrinkage is within ± 2%.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  1 is a plan view of an airbag manufactured by the manufacturing method of the present invention, FIG. 2 is a cross-sectional view of a joint portion 2 of the airbag of FIG. 1, FIG. 3 is a schematic diagram of a preheating treatment apparatus, and FIG. -FIG. 7 is process explanatory drawing of an Example. Although the curtain shield airbag will be described here, the present invention is not limited to this, and the present invention is not limited to this, such as a driver airbag, a passenger airbag, a side airbag, a knee airbag, and a pedestrian protection airbag. Applicable.

  As shown in FIG. 1, in an airbag 1 manufactured according to the present invention, two base fabrics (4 a and 4 b) are joined by a joining portion 2 at a partition portion between an outer peripheral portion and an inflating chamber.

  That is, as shown in FIG. 2, the base fabrics 4 a and 4 b are joined via the adhesive seal material 3 at the joint portion 2. FIG. 2 further shows a case where the joint portion 2 is sewn with the sewing thread 5.

  As the base fabric used in the present invention, a synthetic fiber, for example, a woven fabric composed of a polyamide fiber such as nylon 66, nylon 6, nylon 12 or nylon 46, and a polyester fiber such as polyethylene terephthalate or polybutylene terephthalate, It is preferably used in terms of economy and strength.

  Furthermore, these synthetic fibers can contain a heat resistance improver, an antioxidant, a flame retardant, an antistatic agent, and the like.

  The single yarn strength of these synthetic fibers is preferably 5.4 g / dtex or more in order to satisfy the physical characteristics as an airbag. More preferably, it is 7.0 g / dtex or more. Moreover, about the total fineness of these synthetic fibers, it is preferable that it is 150-500 dtex. More preferably, it is 150-470 decitex, More preferably, it is 235-470 decitex. If it is smaller than 150 dtex, the strength of the fabric tends not to be maintained. On the other hand, if it exceeds 500 dtex, the thickness of the woven fabric tends to increase and the storage capacity of the bag tends to deteriorate.

  The cross-sectional shape of the single fiber of these synthetic fibers is not particularly limited, such as round, flat, triangular, rectangular, parallelogram, hollow or star shape. Among them, those having a round cross section are preferable from the viewpoint of productivity and cost, and those having a flat cross section are preferable in that the thickness of the woven fabric can be reduced and the bag can be easily stored.

  As the structure of the woven fabric made of the synthetic fibers (hereinafter sometimes simply referred to as a woven fabric), a plain woven fabric, a twill woven fabric, a satin weaving fabric, a modified woven fabric thereof, a multiaxial woven fabric, or the like is used. Of these, a plain woven fabric is preferred because of its excellent mechanical properties.

The cover factor of the fabric is preferably 1500 to 2500. More preferably, it is 1500-2100, More preferably, it is 1800-2100. When the cover factor is smaller than 1500, the opening of the fabric becomes large, and it tends to be difficult to obtain the airtightness of the bag. On the other hand, when the cover factor exceeds 2500, the thickness of the woven fabric increases and the bag storage property tends to deteriorate. Here, the cover factor means that the warp yarn total fineness of the base fabric is D ₁ (dtex), the warp yarn density is N ₁ (lines / 2.54 cm), the weft yarn total fineness is D ₂ (dtex), and the weft yarn When the density is N ₂ (pieces / 2.54 cm), it is represented by (D ₁ × 0.9) ^1/2 × N ₁ + (D ₂ × 0.9) ^1/2 × N ₂ .

  Scouring such a base fabric and heat setting. Next, at least one surface thereof is covered with an elastomer. Of course, both sides of the base fabric may be covered. In particular, it is preferable to cover only one side of the base fabric in terms of the ability to reduce the thickness of the base fabric in consideration of the storage capacity of the airbag.

  The elastomer used in the present invention may be appropriately selected from silicone elastomers and urethane elastomers. Of these, silicone elastomers excellent in heat resistance and cold resistance are preferred. Preferred examples of the silicone-based elastomer include those containing dimethyl silicone rubber, methyl vinyl silicone rubber, methyl phenyl silicone rubber, trimethyl silicone rubber, or fluoro silicone rubber, and include curing agents, adhesion improvers, fillers, reinforcing agents, and the like. A pigment or the like may be appropriately blended. Further, the type is not particularly limited, such as a solventless type, a solvent dilution type, or a water dispersion type. Of these, a solventless type is preferable from the viewpoint of workability and environment.

The coating amount of the elastomer, 5 to 60 g / m ² is preferred. More preferably, it is 20-50 g / m < ² >. When the coating amount is less than 5 g / m ² , the air permeability of the base fabric becomes high, and there is a tendency that a problem occurs in the airtightness of the bag. On the other hand, when the coating amount exceeds 60 g / m ² , the thickness of the base fabric increases, and there is a tendency for problems in bag storage.

  Examples of the elastomer coating method include knife coating, gravure coating, spray coating, and lamination. Of these, knife coating is preferable in that a uniform film can be formed.

  It is preferable that the iron shrinkage ratio of the base cloth coated with the elastomer is within ± 2%. More preferably, it is within ± 1%. When the iron shrinkage ratio exceeds ± 2%, the dimensional change during the preheating treatment becomes large, and the dimension of the obtained airbag changes, so that the desired impact absorbing performance tends not to be exhibited. Here, the iron shrinkage rate is measured by the A-1 method (dry heat iron method) of the iron shrinkage rate test method of JIS L1057 woven fabric and knitted fabric. When the fiber type is nylon, the temperature of the iron is 120 ° C.

  The obtained base fabric is usually wound into a roll and cut into a predetermined length. In addition, it is preferable that the roll around which the base fabric is wound is sealed with a polyethylene sheet or the like and stored. Furthermore, it is more preferable to store in a storage where the temperature and humidity are controlled.

  Next, the base fabric having at least one surface coated with the elastomer is cut into a desired shape. The cutting method may be appropriately selected from laser cutting, knife cutting, ultrasonic cutting, and the like. Further, it is preferable to store the cut product so as not to be wrinkled. When it is necessary to fold the cut product, a method of fixing with a jig or the like so that the folded portion draws a large arc is effective in preventing wrinkles and is preferable.

  The adhesive sealing material 3 used in the present invention includes a silicone-based adhesive, a polyurethane-based adhesive, a polyamide-based adhesive, a nitrile rubber-based adhesive, and a polysulfide in consideration of adhesiveness with a base fabric coated with an elastomer. What is necessary is just to select suitably from a system type adhesive agent etc., and a thermoplastic thing or a thermosetting thing may be sufficient. Examples of the curing mechanism include room temperature moisture curing type, room temperature condensation reaction type, room temperature addition reaction type, heat curing type and electron beam curing type. Among them, the electron beam curing type is expensive because it shows good adhesion to the base fabric covered with silicone elastomer, and room temperature addition reaction type silicone adhesive does not require energy such as heating. Yes, environmentally and cost-effectively.

  Examples of the form of the adhesive seal material include 1 liquid, 2 liquids, liquids of 3 liquids or more, powders, films or tapes. Among these, the one having two or more liquids is more preferable than the one liquid type in terms of storage stability. Further, in terms of easy penetration between the fiber bundles and single fibers of the base fabric, a liquid one or a so-called hot melt type which has fluidity when heated is more preferable.

  Regarding the arrangement method of the adhesive sealing material, a liquid material is applied by a dispenser, screen print or spray, and a powder material is applied through a mold, a film or a tape. For example, a method of cutting and sticking to a desired shape may be used, and the method may be appropriately selected.

  Here, when the adhesive sealing material is liquid, the thixotropy index at 25 ° C. is preferably in the range of 1.5-6. More preferably, it is 1.5-3. The thixotropy index is a value obtained by dividing the viscosity at 5 rpm measured by a rotational viscometer at a constant temperature by the viscosity at 50 rpm. When the thixotropy index at 25 ° C. is less than 1.5, the adhesive sealing material applied on the synthetic fiber fabric is adjusted to a desired thickness, and then the adhesive sealing material is easy to flow until it is cured. There is a tendency that the shape of the adhesive seal portion cannot be maintained. If the thixotropy index is 1.5 or more, the adhesive seal material is difficult to flow unless a large external force is intentionally applied to the adhesive seal portion. On the other hand, when the thixotropy index exceeds 6, when applying the adhesive sealing material, the viscosity change with respect to the shear stress is large, and it tends to be difficult to control the application shape. When the adhesive sealant is a room temperature curable type, the thixotropy index is determined before the adhesive sealant begins to cure, that is, in the case of a one-component type, immediately after taking out from the container, in the case of a two-component or more Measure them immediately after mixing them.

  Similarly, when the adhesive sealing material is liquid, the viscosity at 25 ° C. is preferably in the range of 100 to 500 Pa · s. More preferably, it is the range of 200-400 Pa.s. When the viscosity is lower than 100 Pa · s, the adhesive sealing material tends to flow, and the adhesive sealing material tends to spread after the application or bubbles tend to be mixed in. On the other hand, when the viscosity exceeds 500 Pa · s, the coating workability and the coating accuracy tend to be inferior. In the case where the adhesive sealing material is a room temperature curable type, the viscosity is also measured before the adhesive sealing material begins to be cured, similarly to the thixotropy index.

  About the width | variety of the said adhesive sealing material, 5-20 mm is preferable. More preferably, it is 5-15 mm. If the width is narrower than 5 mm, the sewing portion applied in the subsequent process tends to be displaced from the adhesive seal material. On the other hand, if the width is larger than 20 mm, the joint becomes bulky, so that the bag is likely to be inferior. Moreover, about the thickness of an adhesive sealing material, 0.05-2 mm is preferable. More preferably, it is 0.1-1 mm. If the thickness is less than 0.05 mm, the airtightness of the bag tends not to be maintained, and if the thickness exceeds 2 mm, the joint becomes bulky and tends to be inferior in bag storage.

  A method for manufacturing the airbag 1 will be described below by way of example.

(Preheating process)
As shown in FIG. 3, the cut base fabric 4 a is inserted between the upper conveyor 6 and the lower conveyor 7. The base cloth 4a is carried by a conveyor, and is preheated in a space where the upper conveyor 6 and the lower conveyor 7 in which the heaters 8a and 8c, 8b and 8d are installed respectively approach. Then, the base cloth 4a is pressurized by the upper pressure roller 9 and the lower pressure roller 10, and the surface of the base cloth becomes smooth. The smooth base fabric 4 a is sent out to the rear conveyor 11. In addition, it is preferable to perform a preheating process similarly about the other base fabric 4b.
The temperature range of the preheating treatment is preferably in the range of 60 to 150 ° C. More preferably, it is 60-120 degreeC. If the temperature is lower than 60 ° C., the effect of removing wrinkles is small. Here, the preheating temperature is set to 80 ° C. Examples of the preheating treatment method other than the heater include a hot plate press and a steam iron.

  As illustrated in FIG. 3, the use of a preheating apparatus including pressure rollers facing each other is advantageous in terms of cost because the preheating process can be performed continuously.

  The interval from the preliminary heat treatment step to the step of disposing the next adhesive seal material is usually preferably within 24 hours. When 24 hours or more have elapsed, the effect of the preheating treatment is weakened, and the wrinkles of the removed base fabric tend to recover.

(Adhesive seal material placement process)
As shown in FIG. 4, a preheated base fabric 4a is placed on the top 12a. As a method of fixing the base cloth 4a on the top 12a, a method of vacuuming by arranging a large number of suction pores on the top 12a is used. The adhesive sealing material 3 is fed by the metering pump 13 and discharged through the nozzle 14.

(Base fabric overlay process)
As shown in FIG. 5, spacers 15 a and 15 b are arranged at the end of the top 12 a, and the top 12 b on which the base fabric 4 b is laminated is overlaid on the adhesive seal material 3. The top 12b also sucks the base fabric 4b by vacuum.

  Next, as shown in FIG. 6, the thickness of the adhesive sealing material 3 is adjusted to a thickness defined by the spacers 15a and 15b by crimping the top 12a and the top 12b. As a method for adjusting the thickness, as shown in FIG. 7, a method may be used in which the thickness is adjusted by a pressure roller 16 controlled to a predetermined height with respect to the top 12 a.

  In addition, when one base fabric is folded instead of overlapping two base fabrics, as shown in FIG. 8, the base fabric 4 cut so as to be substantially symmetric about the folding line 17. Is used. The shape does not necessarily have to be completely symmetric with respect to the fold line, and may have a different shape such as no concave portion or convex portion on one side. The base fabric 4 is preheated in the same manner as described above. In this case, there is an advantage that the preheating treatment can be performed at a time. Next, the preheated base fabric 4 is arranged on the top 12a in the same manner as the adhesive seal material arranging step, and the adhesive seal material is arranged only on the half base fabric with the folding line 17 as a boundary line. After that, the other half of the base fabric with the folding line 17 as the boundary line is folded over the adhesive seal material 3. Finally, in order to adjust the thickness of the adhesive sealing material as described above, pressure bonding is performed.

  Then, it is left at room temperature until the room temperature addition reaction type silicone adhesive is cured. When the bonding of the adhesive sealing material 3 is completed, the bonding between the base fabrics 4a and 4b is completed. However, when a stronger bonding as an airbag is required, the bonding portion 2 (that is, on the bonding seal portion). May be sewn with the sewing thread 5. The sewing of the joint portion 2 may be performed under known conditions and is not particularly limited.

  In this embodiment, the case where a liquid room temperature curable adhesive seal material is used has been described. However, as described above, the form of the adhesive seal material may be a film, a tape, a hot melt powder, or the like.

  The embodiments of the present invention have been described above, but various design changes can be made without departing from the scope of the present invention.

It is a top view of the airbag manufactured with the manufacturing method of this invention. It is sectional drawing in the junction part 2 of the airbag of FIG. It is the schematic which shows an example of a preheating processing apparatus. It is arrangement | positioning explanatory drawing of the adhesive sealing material in this invention. It is explanatory drawing of the thickness adjustment method of the adhesive sealing material in this invention. It is explanatory drawing of the thickness adjustment method of the adhesive sealing material in this invention. It is explanatory drawing of the thickness adjustment method of the other adhesive sealing material in this invention. It is a top view which shows an example of the cut goods in this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Airbag 2 Joint part 3 Adhesive sealing material 4, 4a, 4b Base cloth 5 Sewing thread 6 Upper conveyor 7 Lower conveyor 8a, 8b, 8c, 8d Heater 9 Upper pressure roller 10 Lower pressure roller 11 Rear conveyor 12a, 12b Top 13 Metering pump 14 Nozzle 15a, 15b Spacer 16 Pressure roller 17 Folding line

Claims (4)

In a method for manufacturing an airbag, the method includes a step of preheating the base fabric, the method including a step of superimposing or folding the base fabric covered with an elastomer on at least one side and joining the base fabric via an adhesive sealant. An airbag comprising: a step of disposing an adhesive sealing material on the base fabric, and a step of overlapping or folding the opposing base fabrics so that the adhesive sealing material is disposed between the base fabrics. Production method. The method for manufacturing an airbag according to claim 1, wherein a temperature range of the preheating treatment is 60 to 150 ° C. The method for manufacturing an airbag according to claim 1 or 2, wherein the apparatus for performing the preheating treatment includes an opposing pressure roller. The method for manufacturing an airbag according to claim 1, 2 or 3, wherein an iron shrinkage rate of the base fabric is within ± 2%.

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