Stock material or miscellaneous articles – Hollow or container type article – Nonself-supporting tubular film or bag
Reexamination Certificate
1998-08-08
2003-09-30
Morris, Terrel (Department: 1771)
Stock material or miscellaneous articles
Hollow or container type article
Nonself-supporting tubular film or bag
C280S728100
Reexamination Certificate
active
06627275
ABSTRACT:
FIELD OF THE INVENTION
The present invention is directed to novel gels and their uses.
BACKGROUND OF THE INVENTION
Air bags are intended to save lives, but the safety of air bags have been call into question after the deaths of several adults including children; and in one case, a child was decapitated by the force of an inflating air bag. The National Highway Traffic Safety Administration has issued warnings regarding the use of airbags in vehicles to protect occupants from impact and recommends that children and small adults not ride in the front passenger seat or that the front seat passenger air bag system be switched off or disengaged.
Conventional airbags are designed for rapid deployment by expanding pressurized or ignitable gas which advances the folded and tightly packed airbag almost instantaneously in the occupant's direction (
FIG. 10
a
) with violant fluxating force and with sufficient velocity to form a predetermined rigid or semi-rigid configuration when fully deployed. Although airbags are formed of a flexible fabric, they are transformed into a substantially rigid or semi-rigid structure when rapidly inflated with gas providing resistance to collapse under impact conditions. In a crash, the air bag could hit with enough force (see
FIG. 11
timing plot and
FIG. 10
a
Bag pressure plot) to cause severe injuries or even death depending on the position of the passenger at the time of inflation.
Because conventional airbags are made from woven fabric yarn material having great strength and resistance to fraying, the airbag construction require laser cutting, precision sewing, joining at the seams, and overlapping at the fabric ends. The define air bag volume also requires folding. The cost of a conventional airbag system is very high. Often time automobiles are stolen and the airbags removed to supply the after air bag market.
In general, reports and information on the state of the art conventional airbags, restraint systems, standards, tests methods, including glossary, terminology and uses are found in the 1996 SAE Handbook, Vol. 3, pp 33.24-33.64 and Appendixes, On-Highway Vehicles and Off-Highway Machinery, Cooperative Engineering Program, and ASTM D 5426, 5645, and 5428.
Due to the severe punching force of conventional airbags (see
FIG. 10A
at 10, 20 and 30 msec profiles), what the world needs is a gentler, safer, more compact, and less expensive passenger friendly disposable airbags.
SUMMARY OF THE INVENTION
I have discovered more comfortable, soft, safe, hugging, enveloping inflatable restraint cushions can be made advantageously from predominantly liquid gels. Moreover, crystal gels made from thermoplastic elastomer copolymers and block copolymers having one or more substantially crystalline polyethylene segment midblocks exhibiting greater advantage over other non-crystalline component forming gels. The crystal gels advantageously exhibit high, higher, and ever higher tear resistances than ever realized before as well as improved high tensile strength. The crystal gels also exhibit improved damage tolerance, crack propagation resistance and especially improved resistance to high stress rupture which combination of properties makes the gels advantageously and surprisingly exceptionally more suitable for use as inflatable restraint cushions in vehicles such as in airplanes, high speed boats, trains, trucks, and automobiles than gels made from non-crystalline poly(ethylene) component copolymers.
The crystal gels which are advantageously useful for making disposible inflatable restraint cushions comprises: 100 parts by weight of one or more high viscosity (I) linear triblock copolymers, (II) multi-arm block copolymers, (III) branched block copolymers, (IV) radial block copolymers, (V) multiblock copolymers, (VI) random copolymers, (VII) thermoplastic crystalline polyurethane copolymers with hydrocarbon midblocks or mixtures of two or more (I)-(VII) copolymers in combination with or without major or minor amounts of one or more other (VIII) copolymers or polymers, said copolymers having one or more segments or one or more midblocks comprising one or more substantially crystalline polyethylene segments or midblocks and selected amounts of a compatable plasticizer (IX) sufficient to achieve gel rigidities of from less than about 2 gram Bloom to about 1,800 gram Bloom with the proviso that when said (I)-(VII) copolymers having nil amorphous segment or nil amorphous midblock are combined with one or more (VIII) copolymers having one or more amorphous segments or amorphous midblocks to form a stable plasticizer compatable gel.
As used herein, the term “gel rigidity” in gram Bloom is determined by the gram weight required to depress a gel a distance of 4 mm with a piston having a cross-sectional area of 1 square centimeter at 23° C.
The gels comprising the thermoplastic elastomer copolymers and block copolymers having one or more substantially crystalline polyethylene segments or midblocks of the invention are hereafter referred to as “elastic-crystalline gels” or simpler “crystal gels”. The segments or midblocks of copolymers forming the crystal gels of the invention are characterized by sufficient crystallinity as to exhibit a melting endotherm of at least about 4° C. as determined by DSC curve.
The various types of high viscosity copolymers and block copolymers employed in forming the crystal gels of the invention are of the general configurations (Y—AY) n copolymers, A—Z—A, and (A—Z)n block copolymers, wherein the subscript n is two, three, four, five or more. In the case of multiarm block copolymers where n is 2, the block copolymer denoted by (A—Z)n is A—Z—A. It is understood that the coupling agent is ignored for sake of simplicity in the description of the (A—Z)n block copolymers.
The segment (A) comprises a glassy amorphous polymer end block segment which can be polystyrene, poly(alpha-methylstyrene), poly(o-methylstyrene), poly(m-methylstryene), poly(p-methylstyrene) and the like, preferably, polystyrene.
The segment (Y) of (VI) copolymers (Y-AY)n comprises substantially crystalline poly(ethylene) (simply denoted by “—E—” or (E)). In the case of (VI) copolymers (A—Y) n, (Y) when next to (A) may be substantially non-crystalline or amorphous ethylenie segments. For example a crystalline copolymer (Y—AY)n may be represented by: . . . E—E—E—E—E—E—E—E—E—SE—E—E—E—E—E—E—SE—E—E—E—E—E—E—SE—. . . Where Y is a long run of polyethylenes or a non-crystalline copolymer (AY—AY)n: . . . —E—SE—SE—E—SE—E—SE—E—SE—E—E—SE—SE—E—SE—. . . , Where Y is a non-crystalline run of ethylene.
The end block segment (A) comprises a glassy amorphous polymer end block segment which can be polystyrene, poly(alpha-methylstyrene), poly(o-methylstyrene), poly(m-methylstryene), poly(p-methylstyrene) and the like, preferably, polystyrene. The segment (Y) of (VI) random copolymers A-Y comprises substantially crystalline poly(ethylene) (simply denoted by “—E—” or (E)). In the case of (VIII) random copolymers A—Y, (Y) may be substantially non-crystalline or amorphous ethylene segments. The midblocks (Z) comprises one or more midblocks of substantially crystalline poly(ethylene) (simply denoted by “—E— or (E)”) with or without one or more amorphous midblocks of poly(butylene), poly(ethylene-butylene), poly(ethylene-propylene) or combination thereof (the amorphous midblooks are denoted by “—B— or (B)”, “—EB— or (EB)”, and “—EP— or (EP)” respectively or simply denoted by “—W— or (W)” when referring to one or more of the amorphous midblocks as a group) The A and Z, and A and Y portions are incompatible and form a two or more-phase system consisting of sub-micron amorphous glassy domains (A) interconnected by (Z) or (Y) chains. The glassy domains serve to crosslink and reinforce the structure. This physical elastomeric network structure is reversible, and heating the polymer above the softening point of the glassy domains temporarily disrupt the structure, which can be restored by lowering the temperature. During mixing and heating in the presence of compatable plasticizers, the glassy domains (
Applied Elastomerics, Incorporated
Morris Terrel
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