Fabric (woven – knitted – or nonwoven textile or cloth – etc.) – Woven fabric – Woven fabric with a preformed polymeric film or sheet
Reexamination Certificate
2000-01-11
2002-09-03
Morris, Terrel (Department: 1771)
Fabric (woven, knitted, or nonwoven textile or cloth, etc.)
Woven fabric
Woven fabric with a preformed polymeric film or sheet
C428S034300, C428S034500, C428S034700, C428S036100, C428S066500, C428S076000, C280S728100, C442S168000, C442S170000, C442S171000, C442S172000, C442S287000, C442S288000, C442S289000, C442S290000, C442S293000, C442S294000
Reexamination Certificate
active
06444596
ABSTRACT:
BACKGROUND OF THE INVENTION AND RELATED ARE STATEMENT
The present invention relates to an air bag and a base cloth therefor for an air bag device installed in a car or vehicle for protecting a driver or passenger at a time of collision of the car, more particularly, a high performance air bag formed of a base cloth obtained by forming a coating film of a silicone modified thermoplastic polyurethane resin on a surface of a woven fabric of fibers, such as polyamide and polyester, and the base cloth for the air bag.
An air bag device for a driver installed at a center of a steering wheel includes a retainer, an air bag attached to the retainer, a gas generator or inflator for developing the air bag, and a module cover for covering the air bag. When a car collides, gas is generated from the inflator, and the air bag develops in a compartment while bursting the module cover.
on the other hand, in an air bag device for a passenger's seat provided at an instrument panel, an air bag and an inflator are attached to a container, and a module cover is further attached to the container to cover an opening thereof. The module cover is called a lid or deployment door. When a car collides, the inflator is actuated to develop the air bag. The module cover pushed by the developing air bag is opened to the side of the vehicle compartment to thereby largely develop the air bag into the vehicle compartment.
Heretofore, as an air bag, the following have been proposed.
1. An air bag formed of a base cloth obtained by coating silicone rubber disclosed in Japanese Patent Publications (KOKAI) No. 63-78744 and (KOKAI) No. 2-270654 and chloroprene rubber on a woven fabric of a synthetic resin, such as polyester and polyamide.
2. An air bag formed of a base cloth obtained by coating a silicone emulsion composition and a silicone latex composition, as a composition not using an organic solvent in view of a working environment, on a woven fabric as disclosed in Japanese Patent Publications (KOKAI) No. 56-16553, (KOKAI) No. 54-131661, (KOKAI) No. 5-98579 and U.S. Pat. No. 3,817,894.
3
. An air bag made of a thermoplastic elastomer, such as thermoplastic polyurethane as disclosed in Japanese Patent Publication (KOKAI) No. 4-266544.
Among the prior air bags, the air bag (
1
) as described above is obtained such that a hardener, adhesive assistant and reinforcer are added to chloroprene rubber and silicone rubber to obtain a composition; the composition is diluted by an organic solvent; and the diluted composition is coated on a base cloth of nylon or the like. Here, the reason why the organic solvent is required is as follows.
Namely, the base cloth of the air bag folded into a small size is developed by blasting to thereby inflate the air bag. When the air bag is developed, since a film coated on the air bag base cloth is also instantaneously expanded following the development of the air bag base cloth, the coating film itself is also required to have a sufficiently high mechanical strength. Thus, relatively high molecular weight base polymer is used for the chloroprene coating material and silicone coating material used at present so that the hardened film thereof has sufficient strength and expanding ability. However, the high molecular weight base polymer can not be applied by a knife coater, offset coater, gravure coater or the like to obtain a thickness (40 to 100 &mgr;m) of the coating film required for the ordinary air bag. Therefore, the coating material using the high molecular base polymer is normally diluted by the organic solvent to a viscosity with which it is easily coated.
However, in the air bag (
1
) wherein the organic solvent is used as explained above, when the coating is carried out, there is a dangerous situation such that the organic solvent catches fire due to static electricity under the working environment, or there is a problem for a worker to breath the organic solvent or contact the organic solvent in his skin to thereby injure his health. Also, in a viewpoint of prevention of an environmental pollution, such as air pollution, the used solvent is bound to be recovered. However, it requires a great amount of money to recover the used solvent. Thus, it has been expected that the organic solvent is not used in various fields as well as in the air bag industry.
As the simplest method for not using or expelling the organic solvent in the coating material, it is considered that the viscosity of the base polymer of the coating material is lowered to a degree with which coating can be easily carried out by the knife coater or the like. In other words, a polymerization degree of the base polymer is considered to be lowered. However, when the polymerization degree of the base polymer is small, the formed coating film has insufficient mechanical strength, and when the air bag is developed, cracks are formed in the coating film, so that there is a risk of explosion or blast of a gas with a high temperature. Also, when the viscosity is lowered too much, the coating material passes or strikes through meshes of a plain weave of nylon fibers and the like as the base cloth for an air bag, and in winding up the coated cloth with the coating material striking through the meshes the coated cloth is blocked; or in carrying out the operation, the coating material striking or passing through the meshes adheres to rolls of a coating machine to thereby deteriorate the workability of the machine, or damage an appearance of the obtained product.
In the air bag (
2
) using no organic solvent but using the silicone emulsion composition as the coating material, it takes a long time to form the coating film, so that it is not favorable as the air bag in a viewpoint of productivity and cost.
The air bag (
3
) formed of the thermoplastic elastomer as explained above has an advantage such that since the base cloth can be subjected to thermal fusion bonding, a sewing process can be omitted relative to the base cloth formed by coating rubber onto the synthetic fiber fabric. However, hardness of the thermoplastic elastomer is extremely changeable according to variation of temperature. Thus, when the air bag is developed, there is a risk such that the air bag is enlarged too much or torn in case of a high temperature, and, on the contrary, it is insufficiently developed in case of a low temperature.
The present invention has been made in view of the above problems in the conventional air bags, and an object of the invention is to provide an air bag and air bag base cloth, wherein an organic solvent is not used at a time of production, so that workability is good and the working environment is safe for the human body.
Another object of the invention is to provide an air bag and air bag base cloth as stated above, wherein the air bag can be quickly developed in a wide range from an extremely low temperature to a high temperature.
A further object of the invention is to provide an air bag and air bag base cloth as stated above, wherein the air bag and air bag base cloth can provide stable performance without any adhesion problems.
Further objects and advantages of the invention will be apparent from the following description of the invention.
SUMMARY OF THE INVENTION
An air bag of the present invention is formed of a base cloth obtained by forming a coating film of a silicone modified thermoplastic polyurethane resin having a polysiloxane segment on a surface of a woven fabric.
The base cloth for the air bag of the present invention is obtained by forming the coating film of the silicone modified thermoplastic polyurethane resin having the polysiloxane segment on the surface of the woven fabric.
In case the silicone modified thermoplastic polyurethane resin having the polysiloxane segment is used, the coating film can be formed on the surface of the woven fabric by a co-extruding, thermal fusion bonding, bonding or the like, without using an organic solvent. Moreover, the coating film formed on the woven fabric exhibits a stable performance in a wide range from an extremely low temperature to a high temperature.
I
Hanada Kazuyuki
Hirai Kinji
Koshiro Yoshitaka
Minemura Masahiko
Nakamura Susumu
Kanesaka & Takeuchi
Morris Terrel
Singh Arti R.
Takata Corporation
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