Surgery: splint – brace – or bandage – Orthopedic bandage – Splint or brace
Reexamination Certificate
2000-05-31
2002-11-26
Brown, Michael A. (Department: 3764)
Surgery: splint, brace, or bandage
Orthopedic bandage
Splint or brace
C602S005000, C002S455000, C002S456000, C002S462000, C002S463000
Reexamination Certificate
active
06485446
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to protective apparel comprising an energy impact absorbing polymeric material and method for shaping the material.
BACKGROUND OF THE INVENTION
Manufacturers and designers of protective gear and apparel are always striving to develop a product which provides the maximum amount of protection for the least amount of cost while optimizing fit and flexibility of movement. With regard to impact protective gear and apparel, such as bullet-proof (ballistic) vests or elbow or shin guards, the rigid surface material on the outer surface of such gear or apparel does not absorb the major force of the impact. The energy of impact is transferred through the rigid material and is passed through to the underlying material and subsequently to the body, causing bruising or impact trauma. In the case of body armor, such as bullet-proof (ballistic) vests, multiple layers of Kevlar® and Spectra® woven fabric are typically encased within a fabric shell and are collectively referred to as a “ballistic pack”. As a bullet leaves the barrel of a rifle or pistol, it not only has a high rate of forward velocity, it also spinning at a high rate of speed due to the rifling of the barrel. As the bullet enters the Kevlar, it becomes entangled in the Kevlar fibers and its forward motion is stopped. Allow this action prevents the bullet from penetrating the body, it does not dampen or absorb the transfer energy of the impact. It is this transferred energy that causes bruising and impact trauma in and around the area of impact.
In an effort to reduce impact trauma, trauma packs are used in conjunction with the ballistic packs. These trauma packs are typically constructed from the same Kevlar® or Spectra® fabric used in the ballistic packs but are made up of layers which are thinner than the layers in the ballistic packs. The thinner layers in the trauma pack are either laminated together or saturated to hold them together. However, these trauma packs add substantial weight, decrease the flexibility of the vest and, thus, the movement of the wearer.
With regard to other types supporting and cushioning apparel and protective gear, at present, foam pads are generally the primary means utilized by manufacturers to reduce injury. However, foam merely flattens directly under the point of pressure and does not redirect the pressure or energy of the impact. Although foam acts as a shock absorber, it is incapable of acting as an energy absorber. Foam does not flow or conform to specific shapes. Foam merely compresses and flattens under an external load. Using foam as a cushioning material and to merely cover tender spots results in restricted circulation and does not reduce discomfort and bruising.
Shock absorbing materials such as foam compress so quickly under pressure that they are unable to absorb enough energy to significantly reduce impact trauma. Thixotropic liquids such as those described in U.S. Pat. No. 5,869,164 to Nickerson, which is a mixture of microspheres in oil and a thickener, are heavy in weight and, because they comprise a liquid medium, they are non-compressible and therefore behave like a supporting device and do not reduce trauma or provide impact protection. As such, although shock absorbers reduce the risk of surface injury, they do not significantly reduce injury to the underlying tissues because a substantial portion of the energy is transferred to the underlying tissues. Furthermore, such liquid based devices are subject to puncture and leaking and are difficult to manufacture because of their complex formulations.
In addition, although it is described in U.S. Pat. No. 5,869,164 that glass and plastic microspheres may be mixed with thixotropic liquids, the microspheres are merely suspended in the thixotropic liquid and thus are free to move around within the liquid. This freedom of movement allows the microspheres to be pushed to, and concentrated in, areas of the thixotropic liquids which are not subjected to pressure. Movement of the microspheres thus reduces the effectiveness, especially over extended periods of use, of thixotropic liquids.
Moreover, bonding agents, such as polyisobutylene polymers, which are typically used in such cushioning devices, are almost always non-liquid at room temperature because of the molecular weight, chemical composition and thermoplasticity. As such, before working with these polymers and to make them flowable, the temperature of these polymers must be raised to lower their viscosity.
Resilient, conforming materials comprising microspheres are also described in U.S. Pat. No. 4,252,910 to Schaefer. Specifically, Schaefer describes a material in which gas-filled microspheres are cohered to a mass by a bonding agent; wherein Schaefer's microspheres consist of an elastic copolymer preferably of vinylidene chloride and/or vinyl chloride copolymerized with acrylonitrile. However, the formulations of Schaefer have such a high viscosity, a high moisture content and sticky nature make the resulting materials virtually impossible to handle and are useless for most applications. For example, Schaefer's material is non-liquid at room temperature and, according to Schaefer, the user must warm his or her foot above normal body temperature to soften Schaefer's material enough to take the shape of the user's foot. Moreover, Schaefer teaches that his material must be at least at body temperature to be flowable. In addition, Schaefer's material has a very high ratio of polymeric material to microspheres, namely, about 53:1. Furthermore, Schaefer is unable to substantially increase the number of microspheres per unit volume because of the high viscosity of Schaefer's material. The low number of microspheres in Schaefer's material severely limits the number of interstices per unit volume which, in turn, reduces the dilatency of Schaefer's material.
A further disadvantage of polyamide and polyisobutylene synthetic polymers as a binding agent is that the resulting cohered mass of microspheres shows a high degree of compression set (low compression regain) which limits the mass' usefulness. This is especially true when such materials are used in cushioning applications.
Furthermore, to date there are no previously known methods for processing materials such as Schaefer's mass into predetermined shapes. Contrary to Schaefer's disclosure, in practice, it is impractical to fill an envelope with Schaefer's material, especially any type of film through which moisture vapor can be transmitted. Schaefer's material has such a high moisture content that, if encapsulated in a film through which moisture can be transmitted, Schaefer's material will lose moisture over time which will change the physical characteristics of Schaefer's material. Schaefer's material also cannot be rolled, pressed or extruded because Schaefer's mass is too viscous, too sticky and has a very high resistance to pressure due to its dilatent characteristics. Schaefer's mass will act as a cushion and will only conform to an externally applied pressure as long as the applied pressure is applied a slow, constant, low force rate.
Moreover, whenever welding or sealing plastic envelopes, it is important to ensure that the plastic film to be sealed is clean and free of contaminants, especially in the area to be sealed. When encasing flowable materials, such as Schaefer's material, there is the added problem of containing the flowable material while the film is being sealed. Previously, the only possible way to encapsulate such materials was to drop the material into a pre-made envelope which is sealed on three sides and then sealing the entry side after the material is introduced. However, this method is impractical and does not sufficiently overcome all the problems, for example, the flowable, moist materials are heavy because they comprise water and/or oil, they leak, they often contain solvents which are flammable, they separate into solid and liquid phases, they are adversely aff
Brother Theodore B.
Cowdrey Roy M.
Nichols Michael D.
Brown Michael A.
Hamilton Lalita M.
I-Tek, Inc.
Nields & Lemack
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