Body armor insert

A body armor insert has a set of ballistic cloth plies made from polyethylene fibers sandwiched between first and second sets of ballistic cloth plies made from aramid fiber. The number of plies in each of the three sets of plies is a function of a level of protection to be provided. Each of the two sets of aramid plies are sewn together along a central region of the set of plies. The set of polyethylene fiber plies are not sewn together except that all three sets of plies are sewn together in a shoulder region of the body armor insert.

BACKGROUND OF THE INVENTION 
This invention relates to an improved body armor insert which protects the 
wearer from bullets. 
The use of protective body armor formed of ballistic cloth woven from 
aramid fibers is known in the art. This cloth protects the wearer from 
bullets. Commercial cloth is available that is made from an aramid fiber 
sold by DuPont under the trademark Kevlar. 
Protective body armor formed of ballistic cloth made from polyethylene is 
also known in the art. This cloth also protects the wearer from bullets. 
Commercial cloth is available that is made from a polyethylene fiber sold 
by the Allied Fibers division of Allied Signal Technologies under the 
trademark Spectra. 
The protection afforded by both the aramid cloth and the polyethylene cloth 
depends upon the number of plies of the cloth and thus can be selected to 
provide the required protection. 
In forming a protective body armor insert there are a number of parameters 
to consider. Of primary importance, the insert must protect the user from 
the penetration and impact of a bullet. 
Different degrees of protection are provided to protect a wearer from 
different types of weapons and accordingly protective armor is classified 
into different protection levels. Additionally, since the protective armor 
is intended for frequent and long periods of use it is important to make 
it as comfortable to wear as possible. Weight and flexibility, along with 
material feel are factors that impact on wearer's comfort. Since 
additional layers of material add both additional weight and protection, 
in forming a protective insert a trade-off must be made between protection 
level and comfort. If a protective device is not sufficiently comfortable 
it will not be used and thus will afford no protection. 
Accordingly it is the major purpose of the present invention to provide a 
body armor insert which meets a predetermined standard of bullet 
protection and which is light weight and more comfortable than prior 
inserts meeting the same standard of protection. 
A related purpose of this invention is to provide such a body armor insert 
which is relatively flexible and which has an acceptable wearing feel. 
BRIEF DESCRIPTION 
In brief, in one embodiment of this invention a protective body armor 
insert is provided which includes three sets of plies. Two sets of plies 
are formed of a ballistic cloth woven from aramid fibers. A third set of 
plies is formed of a ballistic cloth made from polyethylene fibers. The 
plies of the insert are arranged such that the set of polyethylene plies 
is sandwiched between first and second sets of aramid plies.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring now to the drawings, the reference numeral 10 generally denotes 
the improved body armor insert of the present invention. Body armor insert 
10 is shaped and dimensioned to provide protection to a wearer's upper 
torso. Body armor insert 10 is intended to be inserted into vest-like 
wearing apparel so that it can be easily and comfortably worn by a police 
officer or other individual who needs protection from bullets. 
Body armor insert 10 is formed of a plurality of discrete fiber plies. The 
fiber plies are of two types: the first type of plies 14 are formed of 
woven aramid fibers. The second type of plies 16 are formed polyethylene 
fibers laid up in orthogonal fashion. These polyethylene fibers which form 
polyethylene plies 16 are encased in a polyethylene film to hold the laid 
up fibers in place. Both the aramid plies and the polyethylene plies are 
known plies in the art. Each aramid ply 14 is about 15 mils thick and each 
polyethylene ply 16 is about 6.5 mils thick. 
The aramid plies 14 are grouped into two sets, a first set 14A and a second 
set 14B. The polyethylene plies 16 are grouped in a single set 16A. 
Depending upon the amount of protection required different number of plies 
14 and 16 are used to form body armor insert 10. The ply sets are all 
contained within a fabric insert casing 12. 
In a preferred embodiment, insert 10 is intended to protect a wearer from 
bullets from a hand gun and is classified as a Level 1 protective device. 
In Level 1 embodiment, the first set 14A of aramid plies is comprised of 
four plies, the second set 14B of aramid plies is comprised of four plies 
and set 16A of polyethylene plies is comprised of six plies. In this 
arrangement, as in other arrangements for the body armor insert 10, set 
16A of polyethylene plies 16 is sandwiched between the two aramid ply sets 
14A and 14B. 
When insert 10 is intended for Level 2A protection the first set 14A of 
aramid plies contains six plies, the second set 14B of aramid plies 
contains six plies, and set 16A of polyethylene plies contains ten plies. 
For Level 2 protection, first set 14A and second 14B of aramid plies each 
contain eight plies while set 16A of polyethylene plies contain ten plies. 
When insert 10 is for a Level 3A protection, both first set 14A and second 
set 14B of aramid plies contain ten plies each while set 16A of 
polyethylene plies contains fourteen plies. FIG. 2 illustrates a Level 2A 
design. 
Each ply 14, 16 of the body armor insert 10 is in full surface contact with 
adjacent plies. 
The plies in each set of aramid plies 14A, 14B are sewn to one another 
along central seams 18. All of the plies 14 and 16 are sewn together at 
seams 20 along the upper shoulder regions of the body armor insert 10. It 
is preferred to have no other stitching through the polyethylene plies 16 
since it has been found that stitching through the polyethylene plies may 
adversely affect the way those plies protect a wearer from the impact of a 
bullet. The polyethylene ply set 16A however is sandwiched between the 
aramid ply sets 14A and 14B which thus holds the polyethylene plies 
securely in place. 
By using both polyethylene plies and aramid plies, insert 10 provides 
optimal comfort and protection. It has been found that on a comparative 
weight basis polyethylene fiber plies provide better protection from 
bullets than do aramid fiber plies. However, the polyethylene fiber plies 
are stiff and do not have an acceptable feel. Accordingly, by sandwiching 
the polyethylene plies between the more flexible aramid plies, which have 
a more acceptable feel, the insert 10 provides good ballistic protection, 
at light weight with acceptable flexibility and comfort. 
In each of the above recited embodiments of this invention, there are first 
and second sets of aramid plies which sets are positioned on either side 
of the set of polyethylene plies to thereby sandwich the polyethylene 
plies between sets of aramid plies. Part of the reason for this is that 
the aramid plies are primarily responsible for the level of comfort of the 
insert 10. Another part of the reason is that the aramid plies may be 
stitched together and thus form ply sets 14A and 14B which have sufficient 
body to hold the individual polyethylene plies 16 in the set 16A close 
against one another in full surface contact with adjacent plies. Another 
part of the reason is that aramid is particularly fire resistent and it 
enhances the safety of the insert for the outboard plies to be of aramid. 
The polyethylene fibers used in one embodiment are fibers made of 
polyethylene having a high molecular weight of approximately between 
1,000,000 and 5,000,000 with a high degree of crystalline orientation (95% 
to 99%). These fibers are produced by a process of gel-spinning in which 
the polymer is dissolved in order to disentangle the polymer chains. The 
fibers derived from the subsequent spinning are an extended chain fiber 
having high molecular weight, very high degree of orientation and a 
minimum amount of chain folding. This type of fiber is made into the plies 
16. This type of fiber is available commercially. This fiber is used as 
the basis for the plies 16 in a known process in which the fibers are laid 
down in a substantial orthogonal matrix (they are not woven) and are 
sealed or held in place by being fused with a polyethylene film.