Stock material or miscellaneous articles – Web or sheet containing structurally defined element or... – Noninterengaged fiber-containing paper-free web or sheet...
Patent
1994-10-03
1996-10-29
Bell, James J.
Stock material or miscellaneous articles
Web or sheet containing structurally defined element or...
Noninterengaged fiber-containing paper-free web or sheet...
19163, 28103, 28107, 28116, 28117, 428221, 428224, 428280, 428284, 428286, 428297, 428299, 428373, 428400, 428911, 428102, G32B 506
Patent
active
055695280
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a non-woven layer that consists substantially of short polyolefin fibres. Such a non-woven layer is known from WO-A-89/01126. This known layer consists of polyolefin fibres, having a length of at most 20.3 cm, which are substantially unidirectionally oriented and are embedded in a polymeric matrix. This known layer is used in layered ballistic-resistant structures.
A drawback of this layer is that the specific energy absorption (SEA), that is the energy absorbtion on ballistic impact divided by the areal density (weight per m.sup.2), is still low. Because of this the ballistic-resistant layer must have a high weight per m.sup.2 to offer sufficient protection against ballistic impacts. A further drawback is that the layer comprises a matrix, as a result of which it is less flexible and does not breathe as well. Because of this, ballistic-resistant clothing, such as fragment-resistant and bulletproof vests, in which this layer is incorporated is not very comfortable to wear.
The aim of the invention is to avoid these drawbacks to a substantial extent.
This aim is achieved because the non-woven layer is a felt having in the plane of the layer substantially randomly oriented short fibres with a length of 40-100 mm, a tensile strength of at least 1.2 GPa and a modulus of at least 40 GPa.
A felt is a layer wherein the individual fibres are not assembled together to form a specific structure like obtained when yarns are knitted or woven and which layer does by definition not comprise a matrix.
Surprisingly, it has been found that this layer has an improved specific energy absorption (SEA) and is hence very suitable for use in a layered ballistic-resistant structure, in particular for protection against (shell) fragments.
`Good ballistic-resistant properties` is hereinafter understood to be in particular a high SEA. In the field of layered ballistic-resistant structures `high SEA` is generally understood to be an SEA of more than 35 Jm.sup.2 /kg. The SEA is determined according to test standard Stanag 2920 using a fragment-simulating projectile of 1.1.+-.0.02 g. The SEA of the non-woven layer according to the invention is preferably more than 40 Jm.sup.2 /kg and more preferably more than 50 Jm.sup.2 /kg and most preferably more than 60 Jm.sup.2 /kg.
The advantage of a high SEA is that fragments with a certain velocity can be arrested by a layer with a substantially lower areal density. A low areal density is very important for increasing the comfort in wearing, which, besides good protection, is the main aim in developing new materials in ballistic-resistant clothing.
A further major advantage of the use of the nonwoven layer according to the invention in ballistic-resistant clothing is that it does not comprise a matrix and is hence more flexible and more easily adaptable to the shape of the body and can moreover breathe, so that perspiration vapour can easily be discharged.
An additional advantage is that the structure of the invention can be produced via a simpler process that can be carried out using conventional and commercially available equipment.
Although the aforementioned advantages of the invention are pre-eminently advantageous in the aforementioned ballistic-resistant clothing such as fragment-resistant and bullet-proof vests, the use of the invention is not limited thereto. Other applications are in for example bomb blankets and panels.
WO-A-91/04855 discloses a felt consisting of a mixture of 2 different types of short polyolefin fibres, one type of which is substantially shorter and of a polyolefin material having a lower melting temperature than the other type. The felt is converted to a ballistic-resistant article by sintering or melting of the short fibres which are formed into a matrix embedding the long fibres. The drawbacks of this article are that it is not very flexible because of the rigid bonding of the long fibres and that it has mediocre ballistic-resistant properties. Another important difference with respect to the present invention is that WO-A-91/04855 uses
REFERENCES:
patent: 3641638 (1972-02-01), Laible
patent: 4413110 (1983-11-01), Kavesh
patent: 4457985 (1984-07-01), Harpell et al.
patent: 4623574 (1986-11-01), Harpell et al.
patent: 4650710 (1987-03-01), Harpell
patent: 4820568 (1989-04-01), Harpell et al.
patent: 5035111 (1991-07-01), Hogenboom
patent: 5035952 (1991-07-01), Bruinink
patent: 5135804 (1992-08-01), Harpell et al.
Laible & Figucia, `The Application of High-Modulus Fibers to Ballistic Protection`, J. Macromol. Sci.-Chem. A7(1), pp. 295-322 (1973).
Laible, `Ballistic Materials and Pentration Mechanics`, vol. 5 of Methods and Phenomena: Their Applications in Science and Technology, Elsevier Scientific Publishing Co., (1980).
Liable, `High Speed Testing as a Measure of the Resistance to Penetration of Needle-Punched Felts`, Journal of Applied Polymer Science, vol. 8, pp. 283-295 (1964).
Database WPI, Section Ch, Week 1692, Derwent Publications Ltd., London, GB.
Database WPI, Section Ch, Week 1292, Derwent Publications Ltd., London, GB.
Database WPI, Section Ch, Week 3289, Derwent Publications Ltd., London, GB.
Van der Burg Rene C.
Van der Loo Leonardus L.H.
Bell James J.
DSM N.V.
LandOfFree
Non-woven layer consisting substantially of short polyolefin fib does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Non-woven layer consisting substantially of short polyolefin fib, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Non-woven layer consisting substantially of short polyolefin fib will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1784720