JPH08192705A - Air bag and its recycling method - Google Patents

Abstract

PURPOSE: To efficiently and easily recycle the whole fiber materials composing the foundation of an air bag by composing the whole of fiber materials for the foundation, a sewing tread, a belt and an apron for composing the air bag of the same synthetic resin material. CONSTITUTION: An air-bag is composed of a sensor part, an inflater part and a foundation part, which is composed of a sewing thread for sewedly joining the expandingly developing foundation into a specified shape; a belt for smoothly making expansive development into a fixed shape; and an apron for reinforcing and joining the inflater part and the foundation. Each of these foundations is composed of fiber materials, which are wholly the same synthetic resin material being anyone of polyethylene terephthalate, polycapramide or polyhexamethylene a dipamide. Thus the whole of fiber materials composing the foundation of the air bag can be efficiently and easily recycled.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to improvement of an air bag for improving recyclability.

[0002]

2. Description of the Related Art Airbags have been remarkably spreading in recent years as safety devices for protecting passengers of automobiles.

The airbag is mainly composed of a sensor section for detecting a shock, an inflator section for receiving a signal from the sensor section to generate a gas, and a base cloth section for absorbing and expanding the gas to serve as a shock absorbing material. Composed of. Of these, the base fabric portion is a base fabric that expands and deploys, a sewing thread that sewes and joins the base fabric into a specific shape, a belt for smoothly expanding and deploying the base cloth, and further, an inflator portion and a base cloth. It is composed of an apron or the like used to reinforce the joint, and is usually made of a fiber material.

Conventionally, since the above-mentioned base cloth needs to have low gas permeability and mechanical strength required to expand smoothly upon impact, the base cloth made of synthetic fiber yarn having a total fineness of 400 to 1000 d. In addition, a base cloth (hereinafter referred to as a coated product) in which a resin such as chloroprene or silicone is coated has been used.

Polyamides such as polyhexamethylene adipamide and folycapramid; polyesters such as polyethylene terephthalate and polybutyle terephthalate are generally used as the polymer constituting the base cloth. It has also been proposed to partially use aromatic polyamide fibers or liquid crystalline aromatic polyester fibers for the purpose of increasing the mechanical strength of the base fabric. further,
Recently, in order to further improve the lightness, the compactness at the time of storage, and the cost, a cloth (hereinafter referred to as an uncoated product) in which the surface of the base cloth is not coated with a resin has been used, and is also used. It has been proposed to lower the total fineness and single yarn fineness of the base fabric.

On the other hand, polyamide fibers and polyethylene terephthalate fibers, especially polyhexamethylene adipamide fibers, have been mostly used for sewing threads for sewing base fabrics, and a resin is impregnated in order to improve the sewability. Sewing thread has also been used.

Further, as the belt material, a cloth equivalent to the base cloth is often used, and as the apron material, a coated base cloth in which a resin is applied to these base cloths has been used in view of heat resistance and the like.

On the other hand, since the proportion of vehicles equipped with airbags has been increasing more and more in recent years, it is expected that the amount of fiber materials used for airbags will also increase. The mounted airbag is inflated and deployed only when an accident occurs and is used, and in many cases, it is mounted in a vehicle in an unused state and is discarded. When discarded, the airbag is usually removed as a unit.

However, since the removed airbag is different in vehicle type and size, it is difficult to use it as it is as an airbag of a new vehicle. Moreover, it is highly possible that the textile material of the base cloth portion, which occupies an important part of the airbag, has changed its characteristics such as dimensional stability due to changes over time during mounting for many years, and is reused as it is for safety reasons. Is difficult.

Therefore, an efficient recycling method has not yet been found for the collected fiber material forming the base cloth portion of the airbag.

Since the fibrous material forming the base cloth portion is composed of a synthetic resin such as polyamide or polyester, it can be remelted and melt-spun again to recreate a synthetic fiber yarn, or by depolymerization. A method of re-polymerizing and melt-spinning after returning to a monomer to re-create a synthetic fiber yarn is also considered.

[0012] However, the conventional airbag is designed without considering the recyclability, while considering the characteristics during use such as mechanical characteristics, flexibility, and lightness, and the efficiency during manufacturing thereof, Since various synthetic resin fibers are often used together as the fiber material forming the base cloth portion, it is practically difficult to apply the above recycling method.

Further, from the viewpoint of recent resource saving and environmental protection, proposals intended to effectively utilize and recycle fiber materials have been targeted in fields such as seat belts, carpets and uniforms.

However, regarding the textile material of the airbag, it is proposed to make it non-coated (Technical Textile
s, 1994 Feb. p.12, etc.) and an airbag assembling method for facilitating removal of only the base cloth and the sewing thread from the airbag module (JP-A-6-278560). However, efficient recycling of all the fibrous materials forming the base fabric portion of the airbag has not been studied yet.

[0015]

The main object of the present invention is to:
An object of the present invention is to provide an airbag that solves the above-mentioned problems of the prior art and enables efficient and easy recycling of all the fibrous materials that form the base fabric portion of the airbag.

[0016]

In order to achieve the above-mentioned object, the airbag of the present invention comprises substantially all of the fiber materials constituting the airbag, specifically, the base fabric of the airbag, It is characterized in that substantially all of the fiber materials forming the sewing thread, the belt and the apron are made of the same synthetic resin material.

The same synthetic resin material is preferably polyethylene terephthalate, polycapramide or polyhexamethylene adipamide.

Further, it is preferable that the total amount of the oil agent attached to the fiber material, the treating agent, and the additive contained is 1.5% by weight or less based on the fiber.

As described above, the present invention is mainly characterized by unifying the belt and the apron as well as the same synthetic resin fiber in addition to the base cloth and the sewing thread in order to enhance the recyclability.

As a recycling method, generally, a recovered fiber material is used as it is or cut and reused as a padding for a cushioning material, or a recovered fiber material is remelted or remelted to have a fiber shape or various shapes. The method can be roughly divided into three methods: a method of re-molding into a molded article and a method of depolymerizing the recovered fiber material into a monomer and then polymerizing and re-polymerizing. The recycling method contemplated by the present invention may be any of the above three methods, but the latter two methods, which have particularly high utility value, are preferable.

The fiber material constituting the airbag according to the present invention may have any shape such as thread, rope, woven fabric, knitted fabric or non-woven fabric.

As mentioned above, airbags are usually
It is composed of a sensor portion, an inflator portion, and a base cloth portion. Of these, the base cloth portion is usually a base cloth that expands and deploys, a sewing thread that sewes and joins the base cloth into a specific shape, and a predetermined expansion and expansion. It is composed of a belt for smoothly performing a shape and an apron for reinforcing and joining the inflator portion and the base cloth, and each portion of the base cloth portion is made of a fiber material.

In many of the base cloth parts conventionally used for practical use, a coated product having a surface coated with a resin is used, and the resin is made of a base cloth such as chloroprene or silicone resin. A resin material different from the fiber material is used.

In addition, a fiber yarn made of two or more kinds of synthetic resins may be used as a base fabric for enhancing the strength and flexibility of an uncoated product which is not resin-coated. For example, there is a rip stop in which different kinds of reinforcing fibers are driven at a constant interval when driving a woven fabric. Even if the base fabric itself is composed of a single synthetic resin fiber such as polyhexamethylene adipamide fiber only or polyethylene terephthalate fiber only, to control the sewing thread for sewing and the shape when expanded. It has been generally practiced to use another synthetic resin fiber for the belt, or to impregnate the belt with resin in order to improve the convergence of the sewing thread.

In the present invention, substantially all of the fibrous materials constituting the airbag are made of the same synthetic resin material, but substantially all of the fibrous materials are as described above. Substantially all of the fibrous materials including the attached resin are meant to mean that they are not composed of two or more kinds of synthetic resins but are composed of only one kind of synthetic resin. That is, it means that substantially all of the materials constituting the base cloth, the sewing thread, the belt and the apron are made of the same synthetic resin material.

To this end, it is important that neither the cloth forming the base cloth, the belt, the apron nor the sewing thread is coated with resin.

Here, the same synthetic resin material means at least 95% by weight of the basic unit constituting the synthetic resin.
Above, preferably 98% by weight or more consists of the same monomer unit. If at least 95% by weight of the basic unit of the synthetic resin forming the fiber material is not the same material, it is difficult to purify and separate only the desired synthetic resin from the recovered product, which is not preferable. Considering its efficiency and easiness, it is more preferable that 98% by weight or more is composed of the same monomer unit.

On the other hand, since the conventional coated base cloth is coated with 10 to 20% of the total weight of the resin,
The object of the present invention cannot be achieved.

In the present invention, the basic unit constituting the synthetic resin is the minimum basic monomer unit constituting the synthetic resin, which is different from the general concept of simple polyester, polyolefin or polyamide.
For example, polyethylene terephthalate is an ethylene terephthalate unit, polyhexamethylene adipamide (nylon 66) is a hexamethylene adipamide unit, and polycapramide (nylon 6) is an aminocaproic acid unit.

Addition of a copolymerization component for the purpose of enhancing the spinnability at the time of fiber production can be used without trouble as long as the above range is satisfied and the recyclability is not impaired, and a completely different polymer material can be used. Recycling is easier than when mixed. However, if too much copolymerization component is added, it will be difficult to remelt, or to purify and separate during depolymerization. Therefore, it is necessary to use at most 5% by weight.
Of course, even if the sewing thread itself is a thread containing 5% or more of the copolymerization component, it can be used as long as the ratio of the copolymerization composition to the entire recovered fiber material is 5% or less.

Further, synthetic fibers are usually provided with an oil agent in the manufacturing process thereof, and further, various water-repellent, oil-repellent, antistatic, water-absorbing, moisture-absorbing, antibacterial, deodorizing or the like is applied to the surface or inside of the fiber material. In some cases, the additive may be attached or added, but in this case as long as the above range is satisfied and recyclability is not impaired, the additive can be used without any trouble. A more preferable amount of addition or adhesion is 1.5% by weight or less, and even more preferably 1.0% by weight or less. The additive at this time is preferably a component that can be applied to recycling without being particularly separated, and from this point, an inorganic substance is preferable to a thermally stable organic substance.

The base cloth, the belt and the apron are usually made of cloth, but their shapes may be the same or different depending on the purpose, such as woven fabric, knitted fabric and non-woven fabric. Further, for example, even cloths having the same shape may be different in that the weaving density of the woven cloth is made different.

The synthetic fiber material used in the present invention is not particularly limited, and known fibers can be used. For example, fibers made of polyester such as polyethylene terephthalate, polybutylene terephthalate and polyarylate, fibers made of polyamide such as polyhexamethylene adipamide, polytetramethylene adipamide and polycapramide, and also polyolefins such as polyethylene and polypropylene. Fibers are used. Also,
From the viewpoint of high strength fibers, fibers made of polyvinyl alcohol or aromatic polyamide having a high degree of polymerization obtained by wet spinning, dry spinning, or dry wet spinning can also be used.

Among them, polycapramide is easier to depolymerize to a monomer as compared with other polymers such as polyethylene terephthalate and polyhexamethylene adipamide,
Moreover, it is preferable because it can be easily purified to high purity. Furthermore, since the polycapramide fiber is superior to the polyethylene terephthalate fiber in terms of energy absorbing ability and flexibility of the base cloth, it is also preferable for the performance of the air bag base cloth as an original safety device.

Further, polyhexamethylene adipamide is
Depolymerization is possible relatively easily even though it is not as high as that of polycapramide, and as the performance of the airbag base fabric as an original safety device, high strength, heat resistance, energy absorption ability, flexibility of the base fabric, etc. From the viewpoint of, it is also preferable.

In the present invention, not only the base cloth but also the sewing thread, belt and apron need to be made of the same material as the base cloth. Conventionally, the sewing thread has been pasted with a resin or the like in order to improve the sewability thereof, but the adhesion of the resin is not preferable in the present invention. As a method of improving the sewability without using a resin, high entanglement or twisting is preferable. At this time, the fineness of the single yarn is increased and the number of filaments is increased, so that the entanglement and the twisting can be easily performed. On the contrary, it is also possible to use one monofilament having a large fineness as the sewing thread so as not to break into single threads.

The same fabric as the airbag base fabric can be used for the belt installed to adjust the expanded shape when inflated, and a non-coated product can be used. Since the gas permeability of the belt itself is not so important, it is possible to use a fabric in which the number of hammered-in fabrics is reduced due to the ease of manufacturing. In the case where the deployment capacity increases in accordance with the space, such as in the passenger side airbag, it is not necessary to use the belt because it is not necessary to control the deployment shape with the belt.

Since the apron is a cloth installed to thermally and mechanically reinforce the joint between the inflator section and the base cloth, a coated base cloth effective for protecting high temperature gas from the inflator section is used. It has been commonly used in the past. However, in recent years, the development of the inflator part has progressed, and it has become possible to expand at lower temperature gas, and even a cloth without a resin coat can be sufficiently used as an apron. In the present invention, this apron is also a non-coated cloth. It is important to compose from. In addition, in order to improve heat resistance and mechanical strength, a plurality of aprons may be stacked and installed, woven fabrics having different numbers of hammers may be used, or a nonwoven fabric may be used.

In the present invention, it is not necessary to make the apron non-sewn because substantially all of the fiber material used for the airbag can be removed from the module, recovered and recycled.

Since the fibrous material recovered from the airbag of the present invention consists essentially of the same synthetic resin, it can be returned to the synthetic resin by remelting or redissolving, and can be purified in that state. Any of the steps of depolymerization to return to a monomer and purification of the recovered monomer can be easily performed. In order to improve the quality of the recovered product, a method of depolymerization to return to a monomer is preferable, and the depolymerization method may be an ordinary method.

However, the airbag to be recycled here is mainly an unused airbag recovered by removing it from a discarded vehicle or the like, and unlike the car mat and the seat belt, this unused airbag is basically a basic airbag. The textile material is not contaminated by shoes or hands. Therefore, even if it is remelted, redissolved, or depolymerized, the contamination of impurities due to stains can be suppressed to an extremely low level, and purification is extremely easy. Furthermore, since it is possible to obtain a high-purity recovered polymer only by the step of remelting or re-dissolving and purifying without returning it to a monomer by depolymerization, it is possible to easily depolymerize polyethylene terephthalate etc. Even if it is easy to recycle.

Further, according to the present invention, even if the cut cloth or defective product produced in the air bag manufacturing process has substantially the same fibrous material made of the same synthetic resin, it can be easily recycled as described above. You can

[0043]

The present invention will be described in detail below with reference to examples.

[Examples 1 to 3 and Comparative Examples 1 to 6] Air was prepared by the usual method except that the base fabric, sewing thread, belt and apron which compose the airbag were manufactured by the combination of the fiber materials shown in Table 1. The bag was manufactured.

The base fabric, sewing thread, belt and apron were removed from the body of the obtained airbag. About this removed fiber material part, cutting, remelting, and
A recycling test for depolymerization and purification was performed. The results are shown in Table 1.

Various tests were conducted by the following methods.

(1) Cutting test: The collected airbag fiber material was cut as it was to a length of 5 cm with a guillotine cutter. Depending on whether the cutting work was easily done,
Evaluation was made based on the criteria of ∘: easy cutting, ×: slightly difficult cutting.

(2) Remelting test: The cut air bag fiber material was remelted by using an extruder and then spun out from a nozzle to obtain a gut. Regarding the molten state at the time of remelting (foaming degree etc.) and the spinnability of the gut at the time of spinning from the nozzle, ○: good, Δ: somewhat poor,
Poor: Evaluation was made based on the criteria of poor.

(3) Depolymerization / Purification Test: In the case of po, the ester is prepared by the methanolysis method or the glycolysis method.
In the case of polyamide, it was depolymerized under normal conditions by a wet phosphoric acid method in which phosphoric acid was added as a depolymerization catalyst, and monomer purification was performed. From the viewpoint of monomer recovery rate during the depolymerization, easiness of purification thereof, and easiness of separation of impurities, ∘: extremely good, ∘: good, Δ: somewhat bad, ×: poor did.

[0050]

[Table 1]

As is clear from the results of Table 1, in the case of the present invention (Examples 1 to 3), cutting is easy and recycling by depolymerization is easy. In particular, in the case of Example 1 in which all were composed of polyethylene terephthalate, recycling by remelting was suitable, and in the case of Example 2 in which all were composed only of polycapramide, recycling by depolymerization was suitable.

On the other hand, in Comparative Example 1, since the aromatic polyamide fibers were mixed, the cuttability was poor, and it was impossible to recover the main component (PET, its monomer) by remelting or depolymerization. Further, in Comparative Examples 2 and 3, the polymers other than the main component were mixed together at a high ratio, so that neither remelting nor depolymerization was possible. Further, in Comparative Examples 4 and 5, only one kind of the constituent polymer of the fiber material was used, but since the coated product was used for the apron, the sewing thread, etc., the silicon resin was mixed, and remelting and depolymerization were difficult. there were.

Further, in Comparative Example 6 in which the copolyester fiber is used for the base fabric and the sewing thread, the components other than the main component are 6
%, It was possible to perform both remelting and depolymerization, but purification was difficult and the recyclability was poor.

[0054]

EFFECTS OF THE INVENTION In the airbag according to the present invention, substantially all of the fibrous materials used are made of the same synthetic resin material, and almost no resin or additives are mixed.
It has excellent recyclability both when it is returned to a polymer by remelting or remelting and when it is further depolymerized to return to a monomer.

Therefore, it is possible to efficiently and easily recycle the fiber material of the unused airbag that is collected from the discarded vehicle, and further, to recycle the fiber waste and the waste cloth generated in the airbag manufacturing process. Is possible.

Claims (7)

[Claims] 1. An airbag, characterized in that substantially all of the fiber materials constituting the airbag are made of the same synthetic resin material. 2. The textile material is an airbag base cloth,
The airbag according to claim 1, wherein the airbag comprises a sewing thread, a belt and an apron. 3. The airbag according to claim 2, wherein the base cloth, the sewing thread, the belt and the apron are substantially all made of polyethylene terephthalate fiber. 4. The airbag according to claim 2, wherein the base cloth, the sewing thread, the belt and the apron are substantially all made of polycapramide fiber. 5. The airbag according to claim 2, wherein the base cloth, the sewing thread, the belt and the apron are substantially all made of polyhexamethylene adipamide fiber. 6. The total amount of the oil agent, the treating agent, and the additive contained in the fiber material is 1.
The airbag according to claim 1, which is 5% by weight or less. 7. A method for recycling an airbag, wherein substantially all the fiber material constituting the airbag according to claim 1 is separated from the module and then recycled.