Title:
RENEWABLE PROJECTILE TRAP-TARGET BASED ON THERMALLY REVERSIBLE, VISCOELASTIC MATERIALS
Kind Code:
A1


Abstract:
Thermally reversible visco-elastic materials suitable for use as projectile target materials and trap materials.



Inventors:
Amick, Darryl D. (Albany, OR, US)
Application Number:
11/611806
Publication Date:
12/20/2007
Filing Date:
12/15/2006
Primary Class:
Other Classes:
273/410
International Classes:
F41J13/00
View Patent Images:
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Primary Examiner:
GRAHAM, MARK S
Attorney, Agent or Firm:
GANZ POLLARD, LLC (HILLSBORO, OR, US)
Claims:
Currently claimed inventions:

1. A body of material for decelerating and capturing a predetermined projectile, the body comprising a thermally reversible visco-elastic gel composition having a size and shape adapted to be received in a confinement structure for capturing the predetermined projectile, the predetermined projectile being selected from the group of a bullet, BB, pellet gun pellet, or an archery projectile, the projectile having a velocity of at least about 200 feet per second at point of impact with the body of material.

2. The body of material of claim 1 wherein the confinement structure comprises a bullet trap.

3. The body of material of claim 1 wherein the confinement structure comprises an archery target.

4. The body of material of claim 3 wherein the confinement target comprises a replica of a human or animal, and the body represents a section of anatomy.

5. The body of material of claim 3 wherein the confinement structure comprises a target of a projectile propelled by a pressurized gas other than the gas generated from combustion of a propellant in a cartridge in a projectile chamber of a firing apparatus.

6. A kit comprising a mold and the sufficient ingredients to form a body of a thermally reversible visco-elastic gel composition, the mold having a shape adapted to be received in a confinement structure for capturing a predetermined projectile.

7. The body of material of claim 1 and a confinement structure for the body of material.

8. The body of material and confinement structure of claim 7 assembled as a bullet trap.

9. The bullet trap of claim 8 wherein the confinement structure has at least one access area along its length for retrieving a captured projectile or fragments thereof.

10. The bullet trap of claim 8 wherein one portion of the confinement structure includes a shooting port for receiving the muzzle of a weapon to be fired into the trap.

11. The bullet trap of claim 10 wherein an opposite portion of the confinement structure includes a back stop for limiting the motion of projectile, the body of gel being intermediate the muzzle port and the back stop.

12. The bullet trap of claim 8 wherein the body comprises a non-aqueous gel composition consisting of thermoplastic block copolymers and an oil, the block copolymer being in a concentration that imparts to the gel composition sufficient properties to decelerate and capture a desired projectile.

13. The bullet trap of claim 8 wherein the gel composition comprises a substantially transparent gel.

14. The bullet trap of claim 8 wherein the gel composition comprises a substantially translucent gel.

15. The archery target of claim 3 wherein the gel composition comprises a substantially opaque gel.

16. The body of material of claim 1 wherein the body includes a material or structure, as a discontinuous phase of the gel composition.

17. The body of material of claim 1 wherein the body comprises a non-aqueous gel composition consisting of thermoplastic block copolymers and an oil, the block copolymer being in a concentration that imparts to the gel composition sufficient properties to decelerate and capture a desired projectile.

18. The body of material of claim 17 wherein the block copolymer comprising the gel composition is selected from the group of polymers comprising (i) styrene-butadiene-styrene polymers; (ii) styrene-isoprene-styrene polymers; (iii) styrene-ethylene-butylene-styrene polymers; (iv) styrene-ethylenepropylene polymers; (v) styrene-ethylenebutylene polymers; (vi) styrene-butadiene polymers; and (vii) styrene-isoprene polymers.

19. The body of material of claim 1 further comprising a material or structure for simulating a body part, as a discontinuous phase of the gel composition.

20. The gel composition of claim 18 wherein the composition includes about 12 wt % to about 22 wt % of the block copolymer.

21. The gel composition of claim 18 wherein the copolymer comprises a styrenic block copolymer.

22. The gel composition of claim 21 wherein the styrenic block copolymer is a hydrogenated styrenic block copolymer.

23. A method comprising providing a non-aqueous gel composition consisting of thermoplastic block copolymers and an oil, the block copolymer being in a concentration, size and shape that imparts to the gel composition sufficient properties to decelerate and capture a predetermined projectile.

24. The method of claim 23 further comprising melting the gel composition after a projectile is captured therein and allowing it to reform as a gel in a desired shape.

25. The method of claim 24 further comprising forming a discontinuous phase in the gel.

26. The method of claim 24 further comprising forming a functional gradient in the gel.

27. The method of claim 25 wherein the discontinuous phase corresponds to a body part or region.

28. A method comprising providing sufficient ingredients for a body of material for use in capturing a predetermined projectile in a target or a trap, wherein the ingredients enable the formation of a body comprising a non-aqueous gel composition consisting of thermoplastic block copolymers and an oil, the block copolymer being in a concentration that imparts to the gel composition sufficient properties to decelerate and capture a predetermined projectile.

29. The method of claim 28, wherein the predetermined projectile is selected from the group comprising a bullet, BB, pellet gun pellet, or an archery projectile, the projectile having a velocity of at least about 200 feet per second at point of impact with the body of material.

30. The method of claim 9 wherein the body has a depth of between about 12 inches to about 96 inches for decelerating and capturing the predetermined projectile.

31. The method of claim 23 wherein the composition is provided as a body of material, wherein the body has a depth of between about 3 inches to about 96 inches for decelerating and capturing the predetermined projectile, the predetermined projectile being selected from the group of a bullet, BB, pellet gun pellet, or an archery projectile, the projectile having a velocity of at least about 200 feet per second at point of impact with the body of material.

32. The body of material of claim 1 wherein the body has a depth of between about 3 inches to about 96 inches for decelerating and capturing the predetermined projectile.

Description:

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to and the benefit of U.S. provisional patent application Nos. 60/751,183, filed Dec. 16, 2005, by Darryl D. Amick entitled THERMALLY REVERSIBLE MATERIAL FOR ARCHERY TARGETS AND METHODS OF ARROW RETRIEVAL AND TARGET RENEWAL and 60/788,680, filed Apr. 3, 2003, by Darryl D. Amick, entitled BULLET TRAP BASED ON THERMALLY REVERSIBLE MATERIALS, which are each hereby incorporated by reference as if listed in their entirety for all purposes.

This application is also a continuation-in-part of U.S. patent application Ser. No. 11/452,660, filed Jun. 13, 2006, by Darryl D. Amick entitled GEL COMPOSITIONS AS MUSCLE TISSUE SIMULANT AND RELATED ARTICLES AND METHODS, which is a non-provisional of U.S. provisional patent application Nos. 60/692,391, filed Jun. 13, 2005, by Darryl D. Amick entitled ROOM TEMPERATURE SYNTHETIC MUSCLE TISSUE SIMULANT AND ARTICLES AND METHODS FOR PRODUCING SAME; 60/751,183, filed Dec. 16, 2005, by Darryl D. Amick entitled THERMALLY REVERSIBLE MATERIAL FOR ARCHERY TARGETS AND METHODS OF ARROW RETRIEVAL AND TARGET RENEWAL and 60/788,680, filed Apr. 3, 2003, by Darryl D. Amick, entitled BULLET TRAP BASED ON THERMALLY REVERSIBLE MATERIALS; all of which are hereby incorporated by reference as if listed in their entirety for all purposes.

BACKGROUND

The inventive subject matter disclosed herein relates to articles and methods in which thermally reversible, visco-elastic materials are used, in whole or in part, as means of decelerating and capturing projectiles, including but not limited to: arrows, darts, pellets, BB's, bullets and/or fragmented projectiles. Said projectiles are preferably captured without losses of stray particles and/or ricochets (i.e., glancing blows). In some applications, means of easily retrieving captured projectiles are desired, while in others the ability to visually examine in-situ projectiles and associated wound channels within transparent media is desirable. It follows that some applications may benefit from transparent media compositions, while opaque or translucent varieties are perfectly acceptable for others. More particularly, suitable visco-elastic materials are based on non-aqueous gel composition that may comprise thermoplastic block copolymers and an oil, the block copolymer being in a concentration that imparts to the gel composition sufficient properties to decelerate and capture a desired projectile. The compositions may be contained within structures or otherwise associated with apparatuses, such as bullet traps and archery targets, for example.

A. Bullets

Historical methods of stopping bullets, for example on firing ranges or in ballistics laboratories, include a wide variety of approaches that destroy the bullet and deface or destroy characteristic markings that otherwise could have been useful in associating the bullet with a particular firearm. Most of these methods also create conditions which are unsafe and/or undesirable from the standpoints of lead contamination and fire hazards. Following is a brief summary of many of these historical methods.

    • 1) Sand Berms: Natural or artificial sand piles serve to stop bullets, but result in lead dust and fragments, which must be cleaned up periodically. If bullets accumulate in specific areas within the sand mass, dangerous ricochets may occur.
    • 2) Pit and Plate Traps: Steel plates set at an angle appropriate to cause downward deflection are used to shatter bullets into fragments, which collect at relatively shallow depths in a sand pit. The problems with lead dust and fragments are similar to those of sand berms.
    • 3) Water and Plate Traps: Very similar to the Pit and Plate Trap, except that the sand pit is replaced with a water trough. Although problems with lead dust are effectively addressed by this method, special maintenance procedures must be followed to properly maintain water quality and containment.
    • 4) Venetian Blind Trap: This design uses a series of angled steel plates to direct shattered bullets toward the back and bottom of a containment structure. Violent shattering and potential ricochet may occur with this method unless a rubber curtain is installed in front of the trap to prevent “blow-back” of particles. The rubber curtain is permanently degraded with each shot, so it must be replaced before a dangerous condition is allowed to develop.
    • 5) Rubber Traps: Rubber blocks, lamellae, granules et al. have been employed as means of stopping bullets. In all cases, the rubber is progressively destroyed as bullets impact it, and a potential exists for dangerous and costly fires.
    • 6) Helical or Funnel Traps: Devices of various designs mechanically force bullets into roughly concentric or helical paths, thereby dissipating kinetic energy. Such devices may be either wet or dry. While ameliorating problems associated with lead fragments and ricochets, bullets are severely damaged and consequently cannot be “finger printed” for forensic purposes.

A bullet trap described in U.S. Pat. No. 6,732,628, issued May 11, 2004 to Coburn et al. claims to allow bullets to be captured and retrieved for forensic evaluation without much reduced damage. This patent is hereby incorporated by reference in its entirety. FIG. 1 hereto shows a cross section of this prior art system. The system uses an enclosed vessel system 10 with a shooting port 12 for receiving the muzzle of a gun. The vessel system encloses a plurality of discrete, resilient bullet trap media 1 within appropriate enclosures. In some cases, the media are of translucent plastic, generally spherical (¼-¾ inches in diameter),with a durometer value less than or equal to about 100. Bullets are decelerated by the granular media and may subsequently be dumped out with the media into a collection vessel. After manually removing the bullet (and/or fragments), the media is returned to the trap.

While representing an improvement over other previous bullet traps intended for forensic evaluations, there are several weaknesses in this system. First, the present commercial version of this system is only useful and safe when applied to relatively low-energy handgun ammunition. Specifically, the manufacturer specifies that muzzle energies must not exceed 1300 ft-lb. Forensics and other law enforcement professionals must deal, not only with low-energy firearms, but many common and widely available rifles, as well, any of which may be involved in crimes or accidents. Second, when the dry mixture of media and bullets and/or fragments are dumped out for separation and retrieval, a potential exists for both direct contact and airborne lead to expose technicians to both real and perceived hazards. Furthermore, the plastic media wear out progressively and must eventually be properly disposed of and replenished. Finally, the presently marketed commercial version of this system is relatively expensive and therefore beyond the means of many small-to-medium law enforcement agencies, gun dealers, firearms instructors, medical instructors and other individuals who could benefit from an effective, affordable bullet trap.

Accordingly, there is a substantial need for improved bullet traps that (1) effectively and safely decelerate and capture bullets in a relatively compact trap; (2) allow for easy retrieval of bullets; (3) are optionally transparent or translucent for inspection of impact channels and bullets in situ; (4) do not degrade the bullets so as to preclude finger printing; (5) are easy and relatively inexpensive to use; and/or (6) have reusable trap materials.

B. Archery Projectiles

Targets for archery, a term applicable to bow-and-arrow, crossbow, dart, and sling-shot shooting and hunting, must also be constructed of materials which are capable of reliably and safely stopping projectile penetration within the depth of the target body. Additionally, it is desirable that said targets allow the shooter a significant number of shots before degradation renders them unusable and/or unsafe. Further, it is desirable for a target to allow easy manual removal of projectiles, especially broadhead or mechanically expanding arrowheads, without undue damage to either the target or the projectile. Because of this factor, most archers are forced to shoot arrows with “target points” for practice, because they can be easily removed from the target. Before actually going hunting, however, it is necessary to shoot at least a few broadhead hunting arrows, since ballistics for the two different arrow types are significantly different. Still further, a target which allows the shooter to visually observe such artifacts as wound channels and penetration angles would offer advantages in fine-tuning ballistics (e.g., in identifying optimal matches between specific bows and arrows). Finally, a target which may be renewed would be particularly desirable. It is significant that, prior to the inventive subject matter, no target materials have been identified which meet the criteria listed above. Perhaps this is due to the seemingly opposite requirements of (1) adequate resistance to projectile penetration versus (2) easy projectile removal without damage to either target or projectile. Many previous attempts to identify an ideal target material have consisted of confining damage to a small, expendable area of the target (which is periodically replaced) or of spreading damage over a wider area of the target (replacement deferral). In either case, target types presently marketed are 16-24 inches in depth, to adequately stop broadhead arrows shot from modern bows, and are therefore quite massive and bulky.

U.S. Pat. No. 6,068,261, issued May 30, 2000, to Nettle, discloses an archery target having a solid clay core inset in a block of high density foam. The core/block arrangement is generally illustrated in FIG. 6 hereto discusses shortcomings of previous attempts to develop ideal targets and proposes the use of a family of plasticized clays as target insert materials. This patent is hereby incorporated by reference in its entirety. While this invention adequately addresses projectile penetration and removal, said clays are inherently opaque and therefore restrict any meaningful visual evaluation of wound or impact channel configuration, penetration angle, etc. Renewal and reuse are accomplished by repeatedly impacting the expended body of clay with a two-pound maul until all wound channels appear to have healed. This patent advocates removal of broadhead arrows that become detached from shafts during removal attempts by scooping or digging them out. Consideration of the fact that hunting arrows are intentionally maintained in razor-sharp condition will immediately reveal two problems: (1) potential injury to the shooter and (2) potential damage to the fine edges of the arrowhead. In view of the foregoing problems, there is a substantial need for improved archery targets that (1) effectively and safely decelerate and capture archery projectiles in a relatively compact area; (2) allow for easy retrieval of the projectiles; (3) are optionally transparent or translucent for inspection of impact channels and projectiles in situ; (4) do not degrade the projectile so that it may be reused; (5) are easy and relatively inexpensive to use; and/or (6) have reusable target materials.

C. Gas-Propelled Projectiles

A variety of sports and hobbies use rifles, pistols and even shotguns in which the means of projectile propulsion is compressed air or gas (e.g., carbon-dioxide). Accordingly, “gas-propelled” means ejected by gases other than from the gases that are generated upon combustion of gunpowder or other such propellant in a cartridge in a chamber with the projectile. While some of these guns may be considered as “toys”, especially such examples as so-called “BB guns” of low velocity (e.g., 200-600 ft./sec.), many others are capable of attaining muzzle velocities above 1000 ft./sec. and are actually used for hunting small game. A wide variety of targets for stopping BB's and/or pellets are marketed, but most provide no means of stopping projectiles (especially soft, lead pellets) and retrieving them so that they may be reshot. Several types of mechanical target-traps used for capturing BB's merely consist of one or more inclined metal plates which allow projectiles to glance off said plates into a receptacle box. Such controlled ricochet designs occasionally allow projectiles to escape, for example in secondary deflections, and are therefore not absolutely safe for indoor hobby shooting, especially by juveniles. In any event, mechanical traps in general do not provide a soft landing to lead pellets sufficient to allow them to be reused. The inventive subject matter, as applied to gas-propelled projectiles, provides a safe approach to gently capturing, retrieving and reusing both BB's and lead pellets.

In view of the foregoing problems, there is a substantial need for improved targets for gas propelled projectiles that (1) effectively and safely decelerate and capture the projectiles in a relatively compact area; (2) allow for easy retrieval of the projectiles; (3) are optionally transparent or translucent for inspection of impact channels and projectiles in situ; (4) do not degrade the projectile so that it may be reused; (5) are easy and relatively inexpensive to use; and/or (6) have reusable target materials.

SUMMARY

In accordance with the inventive subject matter, materials and methods for producing, using and renewing/reusing target-traps based on thermally reversible, visco-elastic materials as a medium or media are presented herein. The terminology, “thermally reversible”, is meant to define materials which may be repeatedly remelted and resolidified without significant alteration of their physical, chemical or mechanical properties, preferably by heating such materials at temperatures less than about 500 degrees F. By “visco-elastic”, it is meant that the subject media possess significant degrees of viscous and elastic properties. The term, “projectile” as used herein is intended to mean any body projected by external force and continuing in motion under its own inertia.

In certain respects, the inventive subject matter contemplates traps and targets using the aforementioned visco-elastic materials, which are adapted as follows.

Construction of a bullet, BB or pellet target or trap in accordance with the inventive subject matter will necessarily include at least one containment structure capable of confining the visco-elastic material, which in turn decelerates and captures, projectiles and, if present, fragments within itself. Optionally, a secondary containment or “backstop” structure may be employed as an added safety precaution.

Construction of an archery target, on the other hand, may consist of a body of medium within a container, or simply of medium used as an insert in a larger target, such as a full-body game animal mannequin.

Regardless of the type or design of target or trap, the concept of providing methods and means of remelting to allow the user to renew and reuse media is also included within the scope of the inventive subject matter.

A suitable visco-elastic material may be based on a non-aqueous gel composition consisting of thermoplastic block copolymers and an oil, the block copolymer being in a concentration that imparts to the gel composition sufficient properties to decelerate and capture a desired projectile. The gel composition may be substantially transparent, translucent or opaque, depending on the application. The gel composition may include a material or structure, as a discontinuous phase of the gel composition. The block copolymer comprising the gel composition may be selected from the group of polymers comprising (i) styrene-butadiene-styrene polymers; (ii) styrene-isoprene-styrene polymers; (iii) styrene-ethylene-butylene-styrene polymers; (iv) styrene-ethylenepropylene polymers; (v) styrene-ethylenebutylene polymers; (vi) styrene-butadiene polymers; and (vii) styrene-isoprene polymers. The gel composition may include about 12 wt % to about 22 wt % of the block copolymer. The block copolymer may consist of a styrenic block copolymer. The styrenic block copolymer may be a hydrogenated styrenic block copolymer.

The compositions may be contained within structures or otherwise associated with apparatuses, such as bullet traps and archery targets, for example.

Using the teachings herein, a variety of gel compositions are possible, and may be adapted to provide trap and target materials with the following characteristics:

    • 1) Stopping both handgun and rifle bullets (e.g., up to at least about 4000 ft-lb muzzle energy).
    • 2) Stopping, and allowing for later manual removal of, typical broadhead hunting arrows, launched at velocities up to about 350 ft./sec., within about 12 inches of target depth.
    • 3) Capturing and containing bullet fragments (and particulate matter in general) within one or more monolithic bodies of thermally reversible, visco-elastic material, thereby preventing the liberation of errant particles or dust.
    • 4) Capturing gas-propelled projectiles with velocities of about 200-1200 ft./sec.
    • 5) Remelting/solidifying over multiple cycles of use.
    • 6) Allowing practical retrieval of projectiles for evaluation and/or reuse.
    • 7) Capturing projectiles and fragments thereof, and subsequently allowing their retrieval, while reducing exposure of personnel to lead or other potentially toxic projectile remnants.
    • 8) Allowing, when desired, adequate clarity to allow visual observation of wound channel, trajectory, etc.

The inventive subject matter also contemplates that the visco-elastic material may be sold, as part of a kit, of an appliance for remelting medium/media, and/or molding the material into particular trap or target forms.

These and other embodiments are described in more detail in the following detailed descriptions and the figures. The foregoing is not intended to be an exhaustive list of embodiments and features of the present inventive concept. Persons skilled in the art are capable of appreciating other embodiments and features from the following detailed description in conjunction with the drawings.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 shows a bullet trap design according to the prior art.

FIG. 2 shows another prior art design of a bullet trap, according to the prior art.

FIG. 3A represents a bullet trap comprising a confinement structure for holding a body of a thermally reversible visco-elastic material, according to the inventive subject matter.

FIG. 3B shows a perspective view of the bullet trap in FIG. 3A.

FIG. 4A represents an archery target for confining a thermally reversible visco-elastic material, according to the inventive subject matter.

FIG. 4B shows a perspective view according to the archery target of FIG. 4A.

FIG. 5 represents an archery target with a cavity for replaceable receiving a thermally reversible visco-elastic material, according to the inventive subject matter.

FIG. 6 represents an archery target according to the prior art.

DESCRIPTION

The inventive subject matter provides a media for capturing projectiles. The media may be used in traps and targets for the projectile. The term “capture” and like terms used herein means that the projectile is wholly enclosed within the media or partially enclosed by the media. For example, in the case of an arrow, the arrow may be considered captured if its head is in the media but its shaft extends out of the media. For most projectile applications described herein, a material depth of from about 3 inches to about 96 inches will be sufficient for capturing a given projectile.

While the granular media of U.S. Pat. No. 6,732,628, issued by Coburn decelerate projectiles mainly by a classical “momentum transfer” mechanism (ala the collisions occurring between billiard balls), the thermally reversible materials of the inventive subject matter dissipate kinetic energy by at least two, and in some cases three, mechanisms. Momentum transfer is certainly active in examples of the inventive subject matter, as evidenced by the actual displacement of media mass (e.g., the “wound cavity” left by a bullet), but friction between the media and projectile surfaces is also a significant factor in monolithic (as opposed to granular) bodies, especially in the case of arrows which have relatively high surface areas. Furthermore, in thermally reversible materials which have a relatively high degree of visco-elasticity, a third mechanism by which kinetic energy is dissipated is very significant. As a projectile contacts this type of elastomeric medium, translational elastic compression and radial elastic expansion occur, even before permanent (or “plastic”) deformation begins to occur. The medium therefore acts as a highly effective shock absorber. While it is true that a “resilient” granular medium may display some degree of elasticity, the effect is far less than in the case of a monolithic, highly elastic medium.

While any thermally reversible, visco-elastic material is within the scope of the inventive subject matter, suitable materials include polymer-oil gels generally disclosed in the inventor's commonly owned, co-pending application (“GEL COMPOSITIONS AS MUSCLE SIMULANT AND RELATED ARTICLES AND METHODS”, filed Jun. 13, 2006, Ser. No. 11/452,660). Such gels offer certain advantageous properties, including relatively low melting temperatures (e.g., 200-275 degrees F.), excellent elasticity (more than 200% to rupture), desirable “adhesiveness” which readily attracts and holds solid particles, non-toxicity, water resistance, etc. Compositions of polymer-oil gels of this type can be varied to obtain a wide range of mechanical properties, such as yield/flow stress, elastic modulus, etc.

A suitable visco-elastic material may be based on a non-aqueous gel composition consisting of thermoplastic block copolymers and an oil, the block copolymer being in a concentration that imparts to the gel composition sufficient properties to decelerate and capture a desired projectile. The gel composition may be substantially transparent, translucent or opaque, depending on the application. The gel composition may include a material or structure, as a discontinuous phase of the gel composition.

More particularly, gel compositions according to the inventive principles may be formed from thermoplastic block copolymers and an oil, yielding a gelatinous body of material (also referred to herein as a “gel” or “gel compositions”) that may be characterized as elastomers or gel elastomers (visco-elastomers). Block copolymers are generally composed of sequences of the same monomer unit as one block-type, covalently bound to unlike sequences as another block-type. The blocks can be connected in a variety of ways. The different blocks can sometimes intermix freely at sufficiently high temperature, or when sufficiently diluted with solvent, generating a more disordered form. However, it is common for the blocks to spontaneously self-assemble (“order”) into a diversity of mesophases, with the size scale governed by the chain dimensions (order may be tens of nanometers). In the mesophases, dissimilar (e.g., thermodynamic dissimilarity) blocks exist in distinct “microdomains” which are highly enriched in blocks of the same type, sometimes to the point of being essentially pure. The covalent bonds linking the dissimilar blocks are thus localized to the vicinity of the microdomain interfaces. The block ratio is easily varied during polymer synthesis to alter the mesophase structure. The known equilibrium mesophases for diblock copolymers include spheres, cylinders, gyroid, and lamellae.

As used herein “block copolymer” is not limited to di-blocks and may encompass triblocks, tetrablocks, pentablocks, etc. Block copolymers may be made, for example, using “living polymerization” techniques, such as atom transfer free radical polymerization (ATRP), reversible addition fragmentation chain transfer (RAFT), living cationic or living anionic polymerizations.

Particularly suitable polymers for use in the inventive compositions are thermoplastic block co-polymers that are based on at least two relatively thermodynamically incompatible or dissimilar block segments. Many kinds of styrenic block copolymers are expected to be suitable. Hydrogenated styrenic block copolymers are believed to be particularly suitable. The following block copolymers are specifically contemplated: styrene-butadiene-styrene polymers; styrene-isoprene-styrene polymers; styrene-ethylene-butylene-styrene polymers; styrene-ethylenepropylene polymers; styrene-ethylenebutylene polymers; styrene-butadiene polymers; and styrene-isoprene polymers. One or more of the blocks may be a random copolymer. Suitable copolymers are sold under the name SEPTON™. These co-polymers are a series of thermoplastics and are available from KURARAY CO., LTD. and via related company Septon Company of America, Pasadena, Tex. (http://www.septon.info/en/septon/what_septon.html). In terms of structure, the SEPTON™ series polymers generally are a series of hydrogenated styrenic block copolymers that exhibit rubber-like properties. More specifically, several types of hydrogenated styrenic block copolymers of SEPTON™ include a hydrogenated poly(styrene-b-isoprene)(SEP), a hydrogenated poly(styrene-b-isoprene-b-styrene)(SEPS), a hydrogenated poly(styrene-b-butadiene-b-styrene)(SEBS) and a hydrogenated poly(styrene-b-isoprene/butadiene-b-styrene)(SEEPS).

As persons skilled in the art will recognize from the teachings herein, these block copolymers, can be chemically modified with various molecular and atomic constituents to alter the desired chemical or physical property of the gel. In addition, the monomeric groups in a block can be substituted with an alternative monomer providing differential performance from the original copolymer used. For example, it is expected that styrene may be replaced with other aromatic monomers such as naphthalene, and butadiene could be replaced with an alternative alkene. All such modifications or derivatives are intended to be within the scope of equivalency.

Suitable oils in which the block copolymers may be mixed with or dispersed in include: mineral oils and other hydrocarbon oils; organic oils (vegetable and animal based), synthetic oils similar to any of the foregoing, and mixtures thereof. The block copolymer comprising the gel composition may be selected from the group of polymers comprising (i) styrene-butadiene-styrene polymers; (ii) styrene-isoprene-styrene polymers; (iii) styrene-ethylene-butylene-styrene polymers; (iv) styrene-ethylenepropylene polymers; (v) styrene-ethylenebutylene polymers; (vi) styrene-butadiene polymers; and (vii) styrene-isoprene polymers. The gel composition may include about 12 wt % to about 22 wt % of the block copolymer. The block copolymer may consist of a styrenic block copolymer. The styrenic block copolymer may be a hydrogenated styrenic block copolymer.

Certain similar gel compositions (and methods of manufacture) for use in candle making are described in U.S. Pat. Nos. 6,066,329; 5,879,694; and 5,578,089, which are hereby incorporated by reference as if set forth in their entireties. These patents do not disclose or suggest that the gels are suitable for use as a bullet trap or projectile target, but are believed to be suitable for such use.

In describing materials of the inventive subject matter as generally “monolithic” bodies, it should be clarified that a target-trap medium could consist, not only of one or more integral, continuous masses of thermally reversible material, but also of composite structures in which a continuous phase (i.e., the “matrix” phase) of thermally reversible material is intimately mixed with one or more discontinuous phases of different solid materials in a three-dimensional array or network. Indeed, special cases in which the thermally reversible matrix phase forms a continuous three-dimensional network interpenetrated by a different continuous three-dimensional network would also fall within the scope of the inventive subject matter. Particles of said discontinuous phases may be of a variety of shapes selected to obtain desired physical and mechanical properties such as strength, resilience, density, etc. Examples of particle shapes include, but are not limited to, fibers, flakes, needles, spheres, etc. In another possible embodiment of the inventive subject matter, particles of discontinuous phases may be non-uniformly blended with the continuous phase to produce composite media with property gradients. For example, a functionally gradient medium could be designed so as to offer progressively increasing penetration resistance to a bullet along the course of its travel, thereby providing an enhanced “braking” effect to aid in arresting bullets, for example, of relatively high energy.

In summary, composite structures in which at least one continuous phase is a thermally reversible, visco-elastic material are contemplated by the inventive subject matter.

Finally, while U.S. patent application (Ser. No. 11/452,660) with respect to some embodiments emphasized that the media should contain limited frequencies and distributions of air bubbles, because controls on both transparency and animal muscle simulation are to be maintained in that invention. In most projectile targets and traps of the, no such controls are necessary. In fact, relatively opaque gel media produced without heating above room temperatures have been shown to be quite acceptable for all but the most specialized targets and traps, as discussed below.

While the foregoing teachings on gel composition are believed to provide a variety of suitable gel compositions gels, the following are examples of both unsuccessful and successful attempts to make acceptable gel compositions. These are intended as guide posts to help those skilled in the art arrive at suitable gel compositions. The Examples herein are believed to be accurate and reproducible. However, the Examples are intended to supplement the foregoing teachings, and, as is always the case with any experiment, may not have been carried out in a manner that is perfectly in accordance with scientific principles or otherwise beyond question. Accordingly, the following Examples should be viewed as prophetic in nature, but the Applicant reserves the right to rely on them as actual experiments should it be necessary to overcome certain kinds of rejections that might arise during the examination of this patent document.

EXAMPLE 1

An archery target was constructed by filling a 5-gal. plastic bucket with a mixture of about 16 wt % of an SEBS diblock copolymer and 84 wt % white oil, which was then allowed to gel at about 80 degrees F. The resulting opaque (aerated) gel was then shot repeatedly (i.e., several hundred times) throughout the day with broadhead arrows, launched by a group of archers with 45-50-pound bows, which penetrated the gel to about 7-8 inches depth. Said arrows were easily removed manually without damage. In preparation for the next day's shooting, the target was left in the sun at temperatures of about 85-95 degrees F. for several hours, which visually healed all wound channels. This procedure was carried out daily, over a one week time span, with no apparent degradation of target properties. (It was later demonstrated that melting the gel media at about 250 degrees F. to produce a transparent condition had little effect on target functionality, but allowed arrow wound channel and trajectory to be observed.)

EXAMPLE 2

A target-trap for BB and pellet guns was made by preparing the same mixture of polymer/oil as EX. 1 (at 80 degrees F.) and containing it within a 2-qt. metal bucket about 6-in.-dia.(top)×4.25-in.-dia.(bottom)×6 in. deep. About 100 BB's shot at close range with velocities 200-700 ft./sec. penetrated the gel to depths up to 4 inches with no escapement. (It was found that velocities less than about 200 ft./sec. did not permanently penetrate the gel. If it were desired to study projectiles with lower energy than this example, the concentration of polymer could simply be adjusted downward to decrease target-trap resistance.) Additionally, 25 0.177-cal.lead pellets were shot at the same target-trap, penetrating to about 4.5 inches depth. As in EX. 1, melting the gel to retrieve BB's and pellets, either by settling out or by entrapment within a nylon stocking, did not significantly change the target-trap's performance. All of the retrieved lead pellets were reinserted in a Crossman model 795 Springmaster air gun and reused. (Major diameters of these fired pellets had expanded by about 0.001 in., which caused fit to be slightly tighter on reinsertion, but not to a degree which interfered with functionality.)

MULTIPLE BULLET EXAMPLES

Transparent, melted-and-cast ballistic blocks of 16.6 wt % SEBS diblock copolymer in white oil have been shot with essentially all of the most-common rifle and pistol calibers, in applications described in U.S. Ser. No. 11/452,660 in which said blocks were designed to simulate animal muscle ala 10% ordnance gelatin. This broad experience has shown the effectiveness of such media compositions in stopping and entrapping not only bullets, but fragments of bullets and copper-alloy jackets, as well. For example, nearly all hollow-point pistol ammunition is totally encapsulated in gel depths less than 18 inches, while typical hunting rifle ammunition is confined in less than 34 in. depth. (The only large rifle round to completely pass through 34 inches to date was a 0.375 H&H magnum 270-gn bullet, fired at 100 yd.) Because of this observed ability to entrain bullets and fragments in transparent melted-and-cast gel, additional experiments were carried out using opaque, unmelted mixtures of polymer/oil at various polymer concentrations which were allowed to gel at lower temperatures (e.g., 80-100 degrees F.). It was found that 0.223 cal. hollow-point varmint bullets performed about the same in melted versus unmelted gels, attaining maximum penetrations of about 22 inches with all fragments being retained. A surprising observation was that reducing the polymer content by about 50% in an unmelted gel did not significantly affect either bullet fragmentation or penetration.

Conclusion, Ramification and Scope

The inventive subject matter provides projectile targets, traps and combinations thereof based on thermally reversible, visco-elastic media and methods for the use of same. Said media possess all of the desirable attributes demanded of an “ideal” target/trap material:

    • 1) a capability for safely stopping both handgun and rifle bullets (e.g., up to at least about 4000 ft-lb muzzle energy).
    • 2) capabilities for safely stopping, and allowing for later removal of, typical broadhead arrows, launched at velocities up to about 350 ft./sec., within about 12 inches of target depth.
    • 3) capabilities for safely capturing and containing bullet fragments (and particulate matter in general) within one or more monolithic bodies of thermally reversible, visco-elastic material, thereby preventing the liberation of errant particles or dust. wax, soap, gel et al, thereby preventing the liberation of potentially hazardous dust.
    • 4) capabilities for safely capturing gas-propelled projectiles with velocities of about 200-1200 ft./sec.
    • 5) utilization of said medium or media comprised of a majority, by weight, of one or more thermally reversible, visco-elastic materials which may be repeatedly melted (or softened) and solidified for multiple cycles of use. Said medium/media should be non-toxic, non-allergenic, non-carcinogenic, chemically stable in normal indoor and outdoor environments, relatively unaffected by water and pathogens, affordable and available.
    • 6) a capability for allowing practical retrieval of projectiles for evaluation and/or reuse. When lead or other toxic projectiles are involved, a further capability for capturing projectiles and fragments thereof, and subsequently allowing their retrieval, without unduly exposing personnel to lead or other toxic dust.
    • 7) when desired, adequate clarity to allow visual observation of wound channel, trajectory, etc.
    • 8) optional provision, as part of a kit, of an appliance for remelting medium/media. Thus, the scope of the inventive subject matter should be determined by the appended claims and their legal equivalents, rather than solely by the examples given.

In addition to compositions, the inventive subject matter contemplates a method comprising providing a gel composition comprising a styrenic block copolymer and an oil and forming the gel composition into the shape that replicates a human or animal body part. Typically such a part will be of a similar size and scale suitable for target practice.

The method may comprise forming a discontinuous phase in the gel. The method may comprise forming a functional gradient in the gel. The discontinuous phase may correspond to a body part or region. The functional gradient may correspond to a body part or region. An advantage of the gel composition disclosed herein is that they are typically usable at around room temperature and are thermally reversible so that they may be remelted and reused. As used herein around or about room temperature means about 50-80° F.

Further, the inventive subject matter includes a complete recycling kit for use in the home or laboratory is presented, comprising one or more of an initially-supplied visco-elastic bodies, an appliance with appropriate temperature control, one or more molds and, optionally, one or more types of filters by which molten SMTS may be cleaned and scavenged of fragments for reuse. The details of contemplated kits are described in more detail in Ser. No. 11/452,660, incorporated by reference above.

All patent and non-patent literature cited herein is hereby incorporated by references as if listed in its entirety herein for all purposes.

FIGS. 1-6 show various confinement structures, such as traps and targets, for holding visco-elastic materials 110 according to the inventive subject matter. FIGS. 1 and 2 show bullet traps known in the art, but with one or more bodies of the inventive visco-elastic material 110 replacing the prior art medial. The blocks, for example, may be 8.5×5.0×11.5 inches and abutting for any length. The trap of FIG. 2 has a hinged cover 3 for covering a set of removable blocks.

FIGS. 3A and 3B show another example of a bullet or projectile trap 100 containing one or more sections of visco-elastic material 110 which replace the prior art material. In one possible embodiment, shown in FIG. 3A, a bullet trap has a set of one or more hinged covers 114. The trap may be formed from a steel pipe of 1/16″ wall thickness, 6″ diameter and 48″ length. The hinged cover allows access for replacement of visco-elastic materials and recovery of projectiles. The trap includes a shooting end 116. The trap may include a safety backup plate 118. For example, the plate could be ¾″ steel plate.

FIGS. 4A and 4B show an example confinement structure 200 consisting of a cylinder, with a closed end. The cylinder not only serves as a confinement structure but also may be used as a mold for making and forming visco-elastic material 110. An optional pattern 120 representing target areas may be placed over the material 110 for a shooter to aim a projectile. For archery, the structure might have a diameter of 15″ and a depth of about 12″.

FIG. 5 shows a confinement structure 300 representing an animal. The structure has a cavity 302 for receiving visco-elastic material 110 and an optional target pattern 120.

FIG. 6 shows a confinement structure 400 for a projectile according to prior art but with the inventive material 110 replacing the prior art material.

Persons skilled in the art will recognize that many modifications and variations are possible in the details, materials, and arrangements of the parts and actions which have been described and illustrated in order to explain the nature of this inventive concept and that such modifications and variations do not depart from the spirit and scope of the teachings and claims contained therein.