High Clarity Urethane Helps Shield Against Increasing Violence

Sniper fire rains down on a U.S. diplomat touring the Middle East. Death threats terrify a witness testifying in a Mafia trial. Yet another driver is the victim of a violent carjacking on a city street. Increasing international and domestic violence underscores the need for improved automobile security. Armored vehicles equipped with bullet-resistant and break-in proof glass bonded with aliphatic urethane from Stevens Urethane plays a key role in keeping an intended victim safe.

Security glazing is manufactured in different configurations depending upon the final application, for example, Level 3 protects against hand guns, and Level 4 resists high powered rifles. Layers of glass and polycarbonate are laminated together to achieve the required strength. These glass laminations do not splinter upon impact, but actually absorb the incoming force and reflect it back in the opposite direction.

The adhesive in these laminations is critical to ensure a strong, durable bond, with no delamination once it is in the field. Visibility is also an issue, since the windows have to be as clear as regular glass.

Many glass manufacturers choose aliphatic Stevens Urethane for its excellent adhesion properties with both glass and plastic, its high level of optical clarity, light stability, and its consistently high quality. Stevens aliphatic polyether polyurethane sheet provides excellent optical clarity and is used as an optical interlayer in safety automobile glass as well as in encapsulated architectural and security glazing applications. Aliphatic Stevens Urethane is available in different melt characteristics, thicknesses and sheet widths.

In its finished form, the combination of glass, plastic, and urethane film adhesive can absorb the thermal and mechanical shocks caused by bullets or other projectiles, and prevents delimination of glazings composed of unlike materials, a critical attribute for transparent armor. Similar window construction is used for applications such as airplane windows and cockpit canopies.

Adhesive alternatives include a less expensive vinyl adhesive, but urethane’s superior bonding properties are worth the investment. Poor quality adhesive will delaminate with daily exposure to UV light, weather variations, and temperature extremes. Aliphatic Stevens Urethane is impervious to these conditions, and provides the impact resistance and elasticity needed to stand up to rigorous field conditions.

To construct a Level 4 window, the type that resists high powered rifles, two 5/8" thick pieces of glass are shape cut to fit the window, windshield, or backshield area of the car, and molded to the contour of the vehicle. The pieces are laminated together with a layer of Stevens Urethane, and then laminated to a piece of polycarbonate, again with a layer of Stevens Urethane. Windows are encapsulated in aluminum frames before installation, and windshields are installed directly.

The rest of the vehicle body is armored with traditional steeel, or with fiberglass and composite laminations, including doors, headliners, gas pans, and more. Armored cars have been manufactured for governments throughout the world, as well as multinational corporations and law enforcement officials.