Fire Protection Fabric
A protective fabric with a weight/area ratio of less than 300 g/m2 that is intended to form the outer layer of a garment for protection from fire, such as a garment for firefighters for example. It is composed of warp and weft threads that come from at least two types of thread that are resistant to fire, namely a first thread type of the meta-aramide type, a second high-modulus para-aramide type thread with colour variations over its length, and if necessary, in the warp, a third para-aramide type thread that does not display colour variations but is sensitive to ultraviolet light. It includes 15 to 50% of threads of the second type, and if necessary of the third type. Its weave, preferably of the warp double-sided type, is determined so that, on the outer face of the fabric, the warp threads of the second type, and if necessary of the third type, are almost totally masked.
This present invention concerns the area of protection from fire. More particularly, it concerns a protective fabric that is intended to form the outer layer of a garment for protection from fire such as the clothing of a firefighter for example.
The safety of personnel is a primary criterion in the technical development of our company. In the area of fire, we are endeavouring in particular to ensure that the people who are active in combating fires should be protected as well as possible in order to avoid or at least limit serious accidents. This is why the textile manufacturers have developed special materials for protection from fire, namely thermostable or thermoreactive fibres, the textiles manufactured from the said fibres, and the clothing created from these textiles.
Since these are the fibres currently and commonly used in the manufacture of clothing for protection from fire, one is familiar in particular with the fibres called aramides, either para-aramides or meta-aramides, such as Kermel fibre for example, which belongs to the chemical family of the polyamides-imides, like Nomex® type fibre for example, which is a polymetaphenilenelsophtalamide.
One is also familiar with the fibres that are marketed under the trade names of Kevlar®, Twaron® and Technora®.
It needs to be emphasised that a garment for a firefighter, in addition to its fire properties, must satisfy the same aesthetic requirements as any other garment, and in particular must have an external visual appearance that is acceptable or at least that can be reproduced from one garment the next.
Now there exist on the market materials that should be particularly useful for the creation of external fabrics for clothing designed for protection from fire, in the light of their mechanical strength and of their thermal properties, but that have major limitations from an aesthetic viewpoint. For example, there are threads of the high-modulus para-aramide type that display a variation of colour over their length. Without attempting to offer any scientific explanation for this phenomenon, it is possible to suppose that these variations are due to the treatments that are applied to them during the manufacture of such threads.
As a consequence, for the creation of a protective fabric that is intended to former the outer layer of a garment for protection from fire, use is made of threads of the para-aramide type that do not display such a fault, such as the threads marketed under the trade names of Kevlar®, Twaron® and Technora® for example. However, these threads have another drawback that concerns the fact that they are sensitive to ultraviolet light, and that when they are dyed, they adopt shades with low tolerance to light. It is for this reason that these para-aramide threads are most often also implemented in fabrics of the double-layer type, arranging that the said threads are placed on the inner face of the outer layer of the garment, meaning the face that is not directly exposed to the light and to ultraviolet radiation. However, this arrangement has the major drawback that it is necessary to increase the weight/area ratio of the fabric if one chooses a relatively high proportion of threads of the para-aramide type, such as fabrics with a weigh/area ratio of 300 g/m2 for example if one chooses to have 50% of para-aramide type thread. On the other hand, if it is desired to attain a more conventional weight/area ratio, such as 220 g/m2 for example, then the proportion of para-aramide type threads must be reduced significantly, to 100% of para-aramide thread for example.
The objective of this present invention is to propose a protective fabric which is designed to form the outer layer of a garment for protection from fire, and that overcomes the aforementioned drawbacks.
This is a protective fabric, which has a weight/area ratio of less than 300 g/m2, and preferably between 180 and 260 gr/m2, and that is composed of at least two types of fire-resistant thread, namely a first thread of the meta-aramide type, and a second high-modulus para-aramide type thread with colour variations over its length and if necessary, in the warp, a third para-aramide type thread that does not display these colour variations, but which is sensitive to ultraviolet radiation. This last fabric includes 15 to 50% of threads of the second type, and if necessary of the third type, and its weave is determined so that, on the outer face of the fabric, the warp threads of the second type, and if necessary of the third type, are almost totally masked.
Thus, according to the particular arrangement of this present invention, it is possible of obtain a protective fabric of conventional weight/area ratio and that includes a high proportion of para-aramide thread, in particular of high-modulus thread that is insensitive to ultraviolet light, despite the variation of colour that is inherent to this type of thread, and with an acceptable aesthetic appearance.
In fact, the applicant has been able to observe that the variation of colour over the length is not harmful when the weft is visible on the outer layer, contrary to what is observed in the case of the warp.
This can be explained when one considers that the warp threads are drawn, during the warping process, from spools taken from different production lots, so that the juxtaposition of warp threads drawn from these spools and that include different colourings, can generate a streak over the whole length of the piece, which constitutes a redhibitory defect.
In addition, even if all the spools of the warp creel are from the same lot, the variation of colour will result in a different visual appearance between the start and end of the piece, which will be reflected in the clothing manufactured with the said piece, so that a given garment has display variations in appearance if the panels cut out for the manufacturing process are taken from separate areas of the same piece or where two garments will have different visual appearances according to whether the panels used for their manufacture come from the start or end of the bolt.
On the other hand, in the case of the weft, the contrast of colours concerns only the width of the fabric, generally between 1.50 m and 1.60 m since it is the same weft thread that crosses the warp threads over the full width. If necessary, it also possible, using a weft mixer, to use several spools alternately to make up the picks and thus to reduce the effect of colour variations in the weft threads by statistical mixing.
Moreover, since it concerns para-aramide thread, which does not display any colour variations but is more sensitive to ultraviolet light, it is used only in the warp, and the fact that it is almost totally masked eliminates the problem of degradation due to the action of the light and the ultraviolet radiation.
In an implementation variant, the threads of the second type, and if necessary of the third type, represent from 30 to 50% of the warp threads and the threads of the second type represent 30 to 50% of the weft threads.
In an implementation variant, the threads of the first and second type make up in the order of 12 to 16 tex×2.
In an implementation variant, the fabric in question has a basic weave that has the following warp arrangement, namely one thread of the first type, one thread of the second type and two threads of the first type, and the weft has alternating threads of the first and second type. In this method of implementation, it has been possible to create a protective fabric with a weight/area ratio of the order of 220 gr/m2 and with a final proportion of 66.3% of meta-aramide fibres, 33% of para-aramide fibres of high modulus with colour variation over its length and with 0.7% of anti-static fibres. It should be emphasised that since there are threads of the first type, the meta-aramide fibres are generally mixed with a small percentage of anti-static fibres, in particular fibres of the Belitron® or other fibre type, which are conducting or which dissipate charges.
This present invention will be understood more clearly on reading the description of examples of implementation of a protective fabric that has a weight/area ratio of less than 300 g/m2, that is intended to form the outer layer of a garment for firefighters, illustrated in
In the first example, the threads of the first type are threads of the meta-aramide type with a tex number of 14.3 tex×2 (more currently and commonly written as Nm 70/2) composed of 99% meta-aramide fibres known by the trade name Kermel® and with 1% of anti-static fibres.
The threads of the second type are para-aramide type threads with tex number 14.3 tex×2, high modulus, displaying colour variations over their length. This can be threads known by the trade name Rusar® for example. It can also be threads that are known by the trade names Armos®, SVM® or AuTx-HT®. These are continuous-filament threads.
As indicated in
In the case of the weft pattern, it is a meta-aramide(K) thread for a para-aramide thread (P).
The weave density of the fabric is 52×22 threads/cm.
Its weight/area ratio is of the order of 220 gr/m2, with a final proportion of 66.3% of meta-aramide fibres, 33% of para-aramides fibres and 0.7% of anti-static fibres.
In this implementation example, in each unitary pattern (4×4) with the weave illustrated, the warp threads of the high modulus para-aramide type are located to be visible alternately on the fabric side and on the reverse side with a ratio of 1 in 3. In practice, with this type of weave, it turns out that the meta-aramide (K) warp thread that is located furthest to the left of the weave pattern will tend to pass over the warp thread in para-aramide (P), which means that in practice the said warp thread is virtually totally masked on the fabric side of the cloth.
It should be noted that although in the case of the warp, it is preferable to use two-ply yarn to ensure easier weaving, it is possible to use single threads for the weft. For example for threads of with a tex rating of 14.3 tex×2 for the warp, one would use single 29.4 tex threads for the weft.
The second example differs from the first in the basic weave, is of the warp double-sided weave type, illustrated in
In this second example, in each unitary pattern (4×6) the warp threads of the para-aramide type are located alternately and visible on the fabric side and on the reverse side in a ratio of 1 for 2, but as in the first example, the warp thread in meta-aramide (K) that is located furthest to the left of the weave pattern tends to pass over the warp thread in para-aramide (P) that is immediately adjacent to it, which means that, on the fabric side of the cloth, the warp thread in para-aramide is almost totally masked.
In these two examples, all the warp and weft threads in para-aramide can be of the second type, but one can also have all the warp threads in para-aramide of the third type.
Thus, for the warp thread in para-aramide (P) it should be possible to use more conventional threads of the Kevlar®, Twaron®, or Technora® type, since they are almost totally masked, and should not be directly subjected to light and ultraviolet radiation. This variant is also financially advantageous since these more conventional threads are less costly than the aforementioned para-aramide type threads that display colour variations over their length. However it can have a disadvantage in terms of the mechanical strength of the fabric due to the lower strength of the more conventional threads which, given the desired fine nature of the thread, are found as spun yarn on the market, while the aforementioned threads with the colour variation over their length are multi-filament threads (continuous filaments) which are also very strong.
This present invention is not limited to the methods of implementation described and illustrated by way of non-exhaustive examples. In particular, it is possible to envisage other weaves, such a weave in which the warp pattern is four threads of the first type for every one thread of the second type and the weft pattern is one thread of the first type for every one thread of the second type, to give a better density and a better masking of the threads of the second type in the warp, while still remaining within the desired weight/area ratios and with a proportion of the order of 30% of the threads of the second type.
Claims
1. A protective fabric with a weight/area ratio of less than 300 g/m2 that is intended to form the outer layer of a garment for protection from fire, such as a garment for firefighters for example, characterised in that it is composed of warp and weft threads that come from at least two types of threads that are resistant to fire, namely a first thread of the meta-aramide type, a second high-modulus para-aramide type thread with colour variations over its length, and if necessary, in the warp, a third type of para-aramide type thread that does not display colour variations but is sensitive to ultraviolet radiation, and in that it includes from 15 to 50% of threads of the second type, and if necessary of the third type, and in that the weave of the said fabric is of the warp double-sided type and is determined so that, on the outer face of the fabric, the warp threads of the second type, and if necessary of the third type, are almost totally masked.
2. The fabric according to claim 1, characterised in that all the warp and weft threads in para-aramide are of the second type.
3. The fabric according to claim 1, characterised in that all the warp threads in para-aramide are of the third type.
4. The fabric according to one of claims 1 to 3, characterised in that the threads of the second type, and if necessary of the third type, represent from 30 to 50% of the warp threads, and the threads of the second type represent from 30 to 50% of the weft threads.
5. The fabric according to one of claims 1 to 4, characterised in that the threads of the first type and of the second type are made up in the order of 24 to 32 tex in one or two ply.
6. The fabric according to one of claims 1 to 5, characterised by a basic weave, that has a warp pattern of three threads of the first type for every one thread of the second type, and a laying-in or weft pattern of one thread of the first type for every one thread of the second type.
7. The fabric according to claim 6, with a weigh/area ratio of the order of 220 g/m2 and with a final proportion of 66.3% of meta-aramide, 33% of para-aramide and 0.7% of anti-static fibres,
8. The fabric according to one of claims 1 to 5, characterised by a basic weave that has a warp pattern of four threads of the first type for every one thread of the second type and a weft pattern of one thread of the first type for every one thread of the second type.
Type: Application
Filed: Mar 16, 2006
Publication Date: Jun 26, 2008
Inventor: Laurent Thiriot (Andolsheim)
Application Number: 11/817,351
International Classification: D03D 15/12 (20060101);
