JPH05170042A - Air bag - Google Patents

Abstract

PURPOSE:To prevent damage to the cloth, minimize bag capacity deterioration under high and low temperature, eliminate wear, peeling of coating and the like when an air bag is unfolded by coating a part of the bag body cloth with a polycarbonate type polyurethane resin. CONSTITUTION:A polycarbonate type polyurethane resin is a compound obtained a through a polymerization reaction of a polycarbonate diol, and a polyisocyanate. The said resin can be used in a condition such as an organic solvent solution, moisture dispersive solution, water suspension liquid of DMF, DMS and the like, and the resin coating can be used in a method such as coating, laminating, printing and spraying. A cloth made in such manner is cut to a suitable size, attached with a reinforcement cloth, straps, heat and gas sheltering material and the like and finished to a bag of specified shape.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an airbag for safely protecting an occupant in the event of an automobile collision. More specifically, the present invention relates to an air bag that has excellent durability and environmental resistance and can be manufactured at low cost.

[0002]

2. Description of the Related Art In recent years, an airbag system has been put into practical use as a safety device for protecting passengers of various transportation systems, especially automobiles. Usually, an airbag is made by applying an elastomer on the surface and sewing a laminated base fabric to improve heat resistance, flame retardancy, air barrier properties, and the like.

[0003] Airbags are used for a long time before they are actually operated.
It is stored in a narrow space inside the steering wheel and dashboard. During this period, it may be exposed to various environments such as high temperature, high humidity, and low temperature, so it is important to maintain the initial characteristics even in environmental changes among the characteristics required for airbags. .. However, chloroprene-based rubbers that have been generally typified conventionally are
Since it is a halogen-containing elastomer, when it is exposed to a high temperature atmosphere at, for example, 100 to 120 ° C. for a long period of time, it gradually begins to decompose, and halogen or hydrogen halide is generated, which not only causes curing of the elastomer but also Cause embrittlement. Also, as the base cloth material that is generally covered,
Synthetic continuous fibers such as polyamide and polyester are known, but polyester fibers are difficult to bond and are often treated with polyamide fibers for practical use. In particular, when treated with polyamide fibers, the halogen or hydrogen halide penetrates into the base fabric and significantly embrittles the fiber material forming the base fabric, and the mechanical properties of the airbag (tensile strength, tear strength, etc.) are improved. Extremely lower. Therefore, it has been attempted to add various antiaging agents, heat stabilizers, halogen adsorbents represented by metal oxides, etc. to the elastomer, but none of them was satisfied.

In recent years, silicone rubber has been proposed as an improvement of these. Since this silicone rubber is a non-halogen elastomer, it is extremely excellent in the above environmental resistance properties, but it has poor adhesion to the base fabric, so the base fabric and the coating agent may peel off due to rubbing when the airbag is expanded. The bag may be damaged. Furthermore, since the silicone resin has high smoothness, the strength of the sewn portion is not sufficient, which may cause bag damage. Also, the resin cost is extremely high and not suitable for practical use.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to obtain an airbag having high durability and low cost.

[0006]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned conventional problems by covering the fabric of the bag body constituting the airbag with a polycarbonate type polyurethane resin. The resin coating in the bag of the present invention is not particularly limited as long as it is applied to at least a part of the airbag body fabric. For example, a vent-hole type bag with exhaust holes provided on the entire bag surface, or a part of the bag surface (for example, resin coating only on the occupant contact side, steering wheel side untreated) There is a base cloth exhaust type bag in which the processing part is an exhaust part, but it may be appropriately selected depending on the use condition.

As a result of earnest research, the present inventors have found that the use of a polycarbonate type polyurethane resin can impart various properties required for an airbag. That is, a polyester type or polyether type polyurethane resin which is widely used as a normal polyurethane resin has a problem that stability in an environmental change, particularly in a high humidity state is insufficient, and a folded portion is easily adhered. In addition to polyurethane resins, there are those that have excellent long-term durability (heat resistance, humidity resistance, and low temperature resistance), such as silicone resin (or rubber). Silicone resin has excellent adhesiveness to the airbag base cloth. Friction during the rapid deployment of a low, folded bag can also cause the backing and covering to come apart. Further, since the silicone resin has high smoothness, the sewn portion easily slips, and the sewn portion does not always have sufficient strength.

The airbag having a portion coated with the polycarbonate type polyurethane resin according to the present invention is extremely stable against the environment without the above problems.
The polycarbonate type polyurethane resin referred to in the present invention is represented by the following general formula (1)

[0009]

[Chemical 1]

[0010] It is a compound obtained by a polymerization reaction of polycarbonate diol and polyisocyanate. The number of repetitions n of the above general formula is such that the required molecular weight of the polycarbonate is 500 to 50 from the viewpoint of production.
00, preferably 1000-3000 depending on n = 5
It may be appropriately selected from the 50.

The reaction for obtaining the polycarbonate diol is carried out by a conventional method, for example, 1) HO-R.
It may be selected from a reaction of a diol represented by —OH with a cyclic carbonate, a reaction of a diol with phosgene, a reaction of a diol with a chlorocarboxylic acid ester, a condensation of a dicarbonate compound, and the like. HO-R-OH
The diol indicated by is preferably selected from aliphatic diols, alicyclic diols, and aromatic diols used for ordinary polyurethane resins. For example, alkylene diol (having 2 to 6 carbon atoms, including isomers), alkylene glycol (having 2 to 6 carbon atoms, including isomers), xylylene glycol, etc., alone, in a mixture of two or more, or in a copolymer of two or more. However, the present invention is not limited to these.

The number of repetitions n in the above general formula is the required molecular weight of the polycarbonate diol, for example 500.
It is sufficient to select from n = 5 to 50 according to ˜5000, but this is not particularly limited. The polyisocyanate that reacts with the polycarbonate diol may be arbitrarily selected from those used in ordinary polyurethane resins, and examples thereof include tolylene diisocyanate (TDI) and diphenylmethane diisocyanate (MD).
I), aromatic isocyanates such as naphthalene diisocyanate, crude TDI, and crude MDI; aromatic alicyclic isocyanates such as xylylene diisocyanate and phenylene diisocyanate; hexamethylene diisocyanate;
One or more kinds of aliphatic diisocyanates such as isophorone diisocyanate, hydrogenated MDI and hydrogenated XDI, and modified compounds thereof may be selected.

Although not the main component of the resin, various amines and carboxylic acids which can react with isocyanate may be used together as the third component. For the polycarbonate-type polyurethane resin used in the present invention, the polyol component and the polyisocyanate component may be selected according to the required properties, and the molecular weight of the polyurethane resin is, for example, 10
Strong elongation in the range of 100,000 to 200,000, preferably 10,000 to 100,000,
It is selected in consideration of physical properties such as texture.

The resin may be used in any state such as an organic solvent solution of DMF, DMSO, etc., an aqueous dispersion, an aqueous suspension, or the like. Furthermore, in the resin liquid, an anti-aging agent, an antioxidant, an ultraviolet absorber, an antistatic agent, a flame retardant, a wetting agent, a softening agent, a thickener, an emulsion stabilizer, which is used for a usual processing agent, A compound having a reactive group with a pigment, carbon, an inorganic filler (silica-based, titare-based, etc.) and a urethane resin, such as an isocyanate compound, an epoxy compound, a methylol compound, etc. may be contained.

In the present invention, the air bag coated with the resin has excellent durability characteristics and environmental resistance characteristics, and further,
It also has a high adhesive strength with the fabric, withstands pressure, heat, friction, etc. when the bag is expanded and does not cause damage. Further, the resin used in the present invention is also excellent in adhesiveness with the same kind or different kinds of resins, and therefore adhesive bonding can be used for attaching the reinforcing member at the time of bag making, thus improving bag making work efficiency, The cost can be reduced.

The resin coating method in the present invention includes coating, laminating, printing, spraying and the like, which may be appropriately selected and used without any particular limitation. Further, depending on the case, a dipping method or the like may be used together. The coating amount of the resin in the present invention is
Although not particularly limited, it is preferably 15 to 120 g / m ² from the viewpoint of gas barrier property during bag expansion, heat resistance, and the like. When the coating amount is 15 g / m ² or less, gas shutoff,
It is inferior in heat resistance, and when it is 120 g / m ² or more, it is hard and heavy, which is not practical.

The cloth obtained as described above is cut into an appropriate size, and various members such as a reinforcing cloth, a strap, a hot gas shielding material, etc. are attached to the bag to have a predetermined shape and a predetermined capacity. .. Installation of these various members,
It may be selected from various methods such as sewing with a sewing machine, fusion joining with high frequency and ultrasonic waves, adhesive joining with an adhesive such as rubber glue, an adhesive and a hot melt agent, or a combination thereof.

The cloth used in the present invention includes, for example, woven fabrics, knitted fabrics, laminates thereof, and sheet-like fabrics such as planar bodies in which a large number of yarns are arranged in parallel and fixed with an adhesive material. In terms of dimensional stability, woven fabrics, particularly isotropic fabrics such as multiaxial woven fabrics are preferred. The constituent density of the woven fabric may be selected according to the total denier and the count of the fiber yarn, and the driving density is 10 to 200 for both warp and weft.
It is preferably in the range of books / inch. The structure of the fabric may be arbitrarily selected, and fiber yarns having different total denier or different fiber yarns may be used in combination.

As the cloth, a single cloth or a double cloth / multilayer cloth by partial joining may be used. As the types of fiber yarns constituting the fabric, long fibers obtained from melt spinning, dry spinning, wet spinning, etc., spun yarns obtained from short fibers, or a combination thereof, and further bulky processing were performed. Processed yarn and the like can be used.

The fiber material used in the present invention is, for example, polyamide fiber such as nylon 6,66,46; aramid fiber typified by a copolymer with paraphenylene terephthalamide and aromatic ether; polyalkylene. Polyester fibers represented by terephthalate; wholly aromatic polyester fibers; vinylon fibers; rayon fibers; polyolefin fibers such as ultra-high molecular weight polyethylene; polyoxymethylene fibers; sulfone fibers such as paraphenylene sulfone and polysulfone; polyether ether ketone In some cases, fibers, polyetherimide fibers, carbon fibers, and the like may be used alone or in combination with inorganic fibers such as glass fibers, ceramic fibers, and metal fibers.

The fiber may contain various additives which are usually used for improving the productivity or the characteristics in the manufacturing process and the processing process of the raw yarn. For example heat stabilizers,
An antioxidant, a light stabilizer, a leveling agent, a plasticizer, a thickener, a pigment, a gloss imparting agent, a flame retardant and the like may be contained. Needless to say, the airbag of the present invention obtained as described above can be applied to a passenger seat for a driver seat, a rear seat, or a door side airbag.

The airbag of the present invention absorbs the impact of an occupant due to a collision of an automobile, but in some cases, a gas other than the hot gas generated from the gas generator, a liquid, a solid, a powder, or particles. It may be applied to other uses in which the body or a mixture thereof is inflated and expanded by jetting and filling, and is included in the application range of the airbag of the present invention.

[0023]

EXAMPLES Examples of the present invention will be shown below. The test evaluation method in the examples is as follows. 1. Performance characteristics of the fabric After the airbag is finished, the air bag is subjected to camping. Initial product is untreated, heat treated product is 10
The condition of 0 ° C. × 1000 hours treatment and the wet heat treatment product means the condition of 50 ° C. × 95% RH × 1000 hours treatment.

(1) Tensile strength (kgf / in) According to the labeled strip method based on JIS-L-1096. The heat-treated product and the heat-moisture-treated product are shown by the strength retention ratio with respect to the initial product. (2) Tear strength (kgf) By a single tongue method based on JIS-L-1096.
The heat-treated product and the heat-moisture-treated product are shown by the strength retention ratio with respect to the initial product.

(3) Strength of bonded part (kgf / in) The outer peripheral bonded part of the airbag is cut in the longitudinal direction with a width of 25 mm and a length of 200 mm, and the main body cloth side of the strip is sandwiched between the upper and lower chucks to bond the bonded part. Is peeled off and pulled to read the maximum strength when the joint is broken. The heat-treated product and the heat-moisture-treated product are shown by the strength retention relative to the initial stage.

(4) Adhesive force (kgf / in) Two strips each having a width of 25 mm and a length of 200 mm are mutually end 3c.
m and length are overlaid on each other and heated and pressure-bonded with a reactive polyurethane type hot melt agent (adhesive area is 25 mm in width and 30 mm in length), and both ends of the strip are grasped and pulled. Read the breaking strength of the adhesive part of.

(5) Adhesiveness Two strips having a width of 50 mm and a length of 50 mm are superposed on each other on the coating surfaces, and sandwiched with glass plates from both sides,
With a load of 3 kg applied from one side, the sample is left in an oven at 70 ° C. for one day and then cooled, and then the presence or absence of adhesion of the two strips is confirmed. Symbol ○: No adhesion at all △: Slight adhesion ×: Very adhesion 2. Performance characteristics of airbags To treat an airbag, the bag is folded and tied with a string. Initial product is untreated, heat treated product is 100
Degree x 1000 hours treatment state, wet heat treatment product is 50 degrees x
95% RH × 1000 hours: treated state.

(1) Compressive strength (kgf / in) After the bag is unsealed and the exhaust hole is closed with a cloth, a rubber balloon is inserted into the bag and air is blown into the bag to blow the bag. Measure the internal pressure when is damaged. The heat-treated product and the heat-moisture-treated product are shown by the strength retention rate with respect to the initial product. (2) Deployment test The bag was unpacked, assembled into a module, and an inflator (TYPE-8, Morton) was attached,
Observe the damage state of the airbag when the airbag is deployed. The expansion was carried out for each bag in a room temperature state, a high temperature state, and a low temperature state.

High temperature condition: The module is heat-treated at 80 ° C. for 4 hours and then developed within 1 minute. Low temperature condition: After processing the module at -30 degrees x 4 hours, 1
Deploy within minutes. Code ○: No damage

[0030]

Example 1 Polyamide 66 long fiber yarn 420d / 70f
Polycarbonate-type polyurethane resin having the following formulation on a plain woven fabric with a history of 46 / in. (Use an emulsion consisting mainly of and)
Was coated by knife coating at 40 g / m ² (dry weight), dried at 100 ° C. for 5 minutes, and then cured at 150 ° C. for 5 minutes to obtain a coated cloth.

Two discs having a diameter of 730 mm were cut from the coated cloth, and a reinforcing cloth of the same fabric was cut in the center of the coated surface of one of the discs.
Three discs with a diameter of 200 mm are stacked, and a diameter of 105 mm,
Sewing sewing on 120 mm, 160 mm and 180 mm lines (use nylon 66 fiber No. 8 for both lock stitch and upper and lower threads),
A hole having a diameter of 100 mm was provided to serve as an inflator mounting port. Further, conversely at a position of 250 mm in the bias direction from the center, apply one piece of the same cloth, 80 mm diameter disc,
mm, a diameter of 65 mm was sewn on a sewing machine (nylon 66 fiber No. 8 was used for both the lock stitch and the upper and lower threads), and two exhaust holes having a diameter of 40 mm were provided. Next, this disk and the other disk with the coating surface on the outside are overlapped with the warp axis shifted by 45 degrees, and the circumference of 700 mm and 710 mm in diameter is sewn on by sewing machine (double chain stitch, nylon 66 fiber for sewing thread). Use upper thread No. 5 and lower thread No. 8). The bag was turned upside down so that the coated surface was on the inside to obtain an airbag. The performance characteristics of this coated cloth and airbag are shown in Table 1 and Table 2.
As shown in, good results were obtained.

[0032]

[Table 1]

[0033]

[Table 2]

(Resin formulation) Polycarbonate-based resin emulsion 25% by weight Flame retardant (halogen-based) 10% by weight Thickener 2% by weight Water 63% by weight ───────────────── ───────────── Total 100% by weight Concentration 35% Viscosity 40,000 cps (using BL type viscometer) Water-dispersible isocyanate (concentration 40%) was added to 100 parts of the above compound. Add 1 part.

[0035]

Example 2 Polyamide 66 long fiber yarn 420d / 70f
Using a locomotive with a jacquard, a circle with a diameter of 700 mm has a double-layered cloth inside, and a single-joint portion with a width of 25 mm and a single-joint portion with a width of 20 mm are provided outside the circle. Partial two-layer woven fabric (upper and lower densities 46 / in) was prepared, and the polycarbonate type polyurethane resin used in Example 1 was coated on both sides of the woven fabric by knife coating to 45 g / m each.
² (dry weight) was applied, dried at 100 ° C. for 5 minutes, and cured at 150 ° C. for 5 minutes to obtain a coated cloth.

A single knotted portion (width: 15 mm) on a line of 730 mm in diameter was cut from the coated cloth, and was composed of polyamide 66, a long fiber yarn 1680d / 280f, and a plain weave having a warp / weft density of 25 yarns / in at the center of one surface A reinforcing cloth having a diameter of 220 mm was heated and pressure-bonded with a reactive polyurethane hot melt agent, and a hole having a diameter of 100 mm was provided to serve as an inflator attachment port.

Further, 250 mm from the center in the bias direction
Contrary to the above position, one piece of the same cloth, a disk having a diameter of 80 mm, was adhered with the hot melt agent to form two exhaust holes having a hole having a diameter of 40 mm. The bag was turned inside out so that the coated surface was on the inside, to obtain an airbag. Good results were obtained as shown in Tables 1 and 2 for the performance characteristics of the coated cloth and the airbag.

[0038]

Example 3 Using the same fabric as in Example 2, a partially coated fabric was obtained in which the same resin was coated on one side of the fabric at 45 g / m ² (dry weight). The partially coated cloth was cut in the same manner as in Example 2, and the same reinforcing cloth having a diameter of 220 mm was adhered to the center portion of the other surface on the side of the end coated cloth (base cloth surface).
A hole of mm was provided to serve as an inflator mounting port. The bag was turned inside out so that the coated surface was on the inside, to obtain an airbag. As shown in Tables 1 and 2, the performance characteristics of the coated cloth and the airbag were good.

[0039]

COMPARATIVE EXAMPLE 1 As in Example 1, 40 g / m ² (dry weight) was obtained by using a polyester type polyurethane emulsion (having polyester diol and an aliphatic diisocyanate as the main components) only for the resin (the resin formulation was the same). ) A coated cloth and an air bag were obtained. As shown in Tables 1 and 2 showing the performance characteristics of the coated cloth and the airbag, the wet heat characteristics were poor.

[0040]

Comparative Example 2 The same fabric as in Example 1 was coated with a solvent solution of chloroprene rubber (solid content: 30%, viscosity: 30,000 cps) by knife coating at 40 g / m ² (dry weight),
After drying at 100 ° C for 5 minutes, vulcanization was performed at 180 ° C for 15 minutes to obtain a coated cloth. An air bag was prepared from the coated cloth in the same manner as in Example 1. As shown in Tables 1 and 2, the performance characteristics of the present coated cloth and the air bag, the strength was greatly decreased by the heat treatment, and the bag was expanded by the bag deployment.

[0041]

Comparative Example 3 The same fabric as in Example 1 was coated with a solvent solution of silicon rubber (solid content: 33%, viscosity: 30,000 cps) by knife coating at 40 g / m ² (dry polymerization), and 10
After drying at 0 ° C for 5 minutes, vulcanization at 180 ° C for 15 minutes was performed to obtain a coated cloth. An air bag was prepared from the coated cloth under the same conditions as in Example 1. As shown in Tables 1 and 2, the performance characteristics of the present coated cloth and the air bag, the adhesiveness between the resin and the base cloth was poor, and the joint portion was misaligned due to the bag expansion.

[0042]

As described above, since the airbag according to the present invention uses the non-halogen resin, it is coated with a resin which does not damage the main body fabric and has excellent durability and environment resistance. Therefore, the deterioration of the body cloth and the bag performance in the environment at high and low temperatures and over a long period of time is small.
Further, the adhesive force between the cloth and the coating material is high, and the coating material is not peeled off due to scratching when the bag is developed, high temperature and high pressure gas, etc., and there is no bag damage such as misalignment.

Further, since the resin used in the present invention has excellent adhesiveness to other resins, it is possible to use adhesive bonding for attaching a reinforcing member at the time of bag making. Can be reduced.

Claims (1)

[Claims] 1. An airbag in which at least a part of a bag body fabric is covered with a polycarbonate-type polyurethane resin.