DE9007323U1 - Heat protective clothing - Google Patents

Description

The invention relates to heat protection clothing with an inner high temperature resistant, insulating and flame retardant fabric or fleece made of fibers and an outer metallization or metallized film.

Good heat protection clothing should provide protection against radiant heat, splashes of liquid metals, flame contact, contact heat and convection heat. At the same time, it should be as comfortable to wear as possible, not restrict the wearer's mobility too much and also be mechanically resilient, but always still provide an appropriate level of protection.

Economic efficiency should be ensured.

In the past, heat-protective clothing used to be made of asbestos fabrics with a metallized foil or metal foil on the outside to protect against radiant heat. Because of the health risks associated with the use of asbestos, cotton, wool, linen, glass fibers, carbon fibers, ceramic fibers, aramid fibers or mixtures thereof are now used as substitute materials.

The disadvantage of these well-known fabrics or fleeces is that either the heat protection is not sufficient for all applications or it is not comfortable to wear, whereby both disadvantages may occur together. Even if the heat protection is sufficient, the heat protection clothing is often too heavy, too rigid and too resistant to bending.

For example, US-PS 4 748 065 describes a flame-retardant nonwoven fabric that is impregnated with carbon particles that adsorb chemical vapors. The nonwoven fibers consist of at least 90% aramid staple fibers and the basis weight is between 35 and 70 g/m ¹ . The fibers are strengthened by two water jet treatments, once with

a jet pressure of about 1,400 kPa, then with jet pressures between 10,000 and 11,000 kPa.

Since this well-known nonwoven fabric also contains meltable fibers, it is destroyed by direct exposure to flames, which is why heat-protective clothing made of this material is only suitable for heat protection to a limited extent.

The present invention is therefore based on the object of creating heat protection clothing which avoids the above-mentioned disadvantages, in particular which provides a high level of heat protection with good wearing comfort and while maintaining cost-effectiveness.

According to the invention, this object is achieved in that the fleece has partially graphitized polyacrylonitrile fibers, and in that the fleece thus equipped is provided with the metallic foil.

Practical solutions have shown that with a fleece of the type according to the invention, surface weights in the range of 70 g/m ² and even lower can be achieved without the fleece's effect as a flame barrier decreasing. This means that heat protection clothing made of this material is significantly lighter.

than the known types. In addition, it has surprisingly been found that the flexural rigidity is also significantly lower, i.e. that the fleece according to the invention is more elastic. This means that the heat protection clothing according to the invention is significantly more comfortable to wear than the known types. The term "partially graphitized" means that the fibers are only graphitized to the extent that they can still be rolled up. The LOI value of the fibers used should be between 40 and 65. "LOI" means "Limiting Oxygen Index". This index determines the flammability of plastics in accordance with ISO Standard 45 89 "Plastics - Determination of flammability by the Oxygen Index". This index can also be applied to textiles with certain restrictions, provided they consist of organic fibers. Effective flame-retardant behavior can generally be expected with LOI values above about 27.

Practical results have shown that it is advantageous if the nonwoven fabric according to the invention is reinforced in some way in order to achieve better tear resistance and tear propagation resistance.

An inventive possibility for this may be to incorporate into the fleece in warp/weft arrangement

-5-running reinforcement threads are incorporated.

In general, it will be sufficient if
There are 4 to 24 threads/inch in the warp direction and 4 to 15 threads/cm in the weft direction.

In this way, a nonwoven fabric with a minimum strength of 70 N/5 cm at a basis weight of 40 to 100 g/m ¹ and, for example, a maximum thickness of 1.8 mm can be obtained, with the specified strength being present in at least one direction.

The reinforcing thread can be inserted using well-known stitch-bonding techniques. A short weft weave can also be used instead of a full weft/9 weave.

The weight proportion of the reinforcing threads can be between 12 and 60 g/m ² , for example. In general, the strengths achieved in this way will be sufficient, although if necessary even higher strengths can of course be achieved by increasing the number of reinforcing threads accordingly.

Prerequisite for the use of suitable

Strengthening threads is because they also have high LOI values.

However, practical results have surprisingly shown that it is not absolutely necessary to use an LOI value that is in the order of magnitude of the LOI value for the fleece, ie around 40. It has been shown that thermoplastics such as polyester fibres can also be used, which have LOI values of less than 27, but are easy to process and very cheap. Practice has shown that even with these values, the flame-retardant effect of the fleece or its strength when exposed to fire is not noticeably affected.
is sought.

Of course, within the scope of the invention, other materials for the reinforcing threads are also possible.

Another possibility for increasing the strength, in particular the tear resistance of the fleece, can be that the fleece is laminated with a second fleece, one of the two fleeces being provided with the metallic foil.

—'7·—

By laminating with a second fleece, significantly better strength is achieved.

It is even possible to use a fleece with the same chemical composition as the first fleece for the second fleece. This is especially true if the two fleeces are arranged in such a way that different strengths in a certain direction are achieved by

different layer directions can be compensated. In this way, with the same total weight per unit area, which is divided equally between the two fleeces, e.g. 30 to 50 g/m ¹ each, a noticeably higher strength can be achieved at the same weight per unit area compared to a single fleece with the same total weight per unit area.

Another possibility for improving the strength is to arrange a grid made of high-temperature-resistant and flame-retardant material between the fleece and the metallized film.

For the mesh, a material will be used that has a correspondingly high tear resistance.

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When using two fleeces, the mesh can be placed between the two fleeces and äisse !»eis sine even higher strength; de; textile material«^ for the heat protection clothingö obtained.

Carbon fibers have proven to be a very inexpensive material for the mesh.

Polyester or polyurethane-based adhesives can be used as adhesives for laminating or coating the individual components together.

It is advantageous if flame retardants are added to the adhesive, such as mineral flame retardants that release carbon dioxide and water. Hydrox/de or carbonates are suitable for this.

Organobromine compounds are also suitable as flame retardants.

bonds, optionally combined with antimony oxy-

The proportion of flame retardant in the adhesive can be between 20 and 40 percent by weight according to the invention

be.

Some possibilities for the heat protection clothing according to the invention are described below using the drawing and the composition examples.

Ss shows:

{) Fig. 1 detail. ise in enlarged view

a section through a nonwoven according to the invention, which is connected to a metallized film, which is provided with a carrier film;

Fig. 2 shows an embodiment in an enlarged view with two nonwovens according to the invention and a metallized film;

Fig. 3 shows a further embodiment in an enlarged view with two fleeces, a grid arranged between them and a metallized film provided with a carrier film.

Composition example 1:

a « · · * ' &igr; a * a · · a a a a a a a ·

For the example according to Fig. 1, a fleece 1 of 70 g/m ² , made of partially graphitized polyacrylonitrile staple fibers with a LOI value of ν \ 60 and a titer of 1.7 dtex in an isotropic fiber orientation, is consolidated in two stages with columnar water jets. In each stage there are 5 jet bars, the holes of which have a diameter of 120 /im and which are arranged at intervals of 0.6 mm.

In the first stage, the fleece top is solidified with jet pressure that increases from nozzle bar to nozzle bar, starting at 25 bar and ending at 140 bar.

The water jets act on the fibers with a pressure of approximately 10,000 kPa. However, it is also possible to increase the pressure in several stages and continuously up to 14,000 kPa .

In the second stage, the fleece is solidified on its underside, whereby the pressures of the nozzle beams Z--J nozzle beams are staggered from JO oar to 140 bar.

In both stages, the fleece is transported on a sieve belt with 100 mesh to create a fabric with

• 4 · ·

to obtain a closed surface.

The fleece is then impregnated with a commercially available hydro- and oleophobic fluorocarbon resin so that 2% resin remains on the fabric.

The fleece 1 obtained in this way is coated on one side with a polyester or polyurethane adhesive. A first coat can be applied as an adhesive base in order to achieve better smoothing, particularly on rough surfaces. A second coat is then applied and a metallized film or layer 3 is placed on the adhesive 2 obtained in this way. Of course, the first coat can also be applied as an adhesive to the metallized film, specifically on the side facing the fleece 1.

The lamination or covering of the fleece 1 with the metallized film or layer 3 can be carried out in a known manner under an appropriately applied surface pressure and at elevated temperatures, e.g. 110 to 120'. The metal used for the metallized film can be, for example, aluminum, gold or silver. For cost reasons, however, aluminum is generally used for this purpose.

The metallized film 3 can be provided with a carrier film 4, e.g. made of a polymer. The carrier film 4 is removed after the metallized film 3 has been applied to the fleece 1.

In this way, a light and very flexible material is obtained for heat protection clothing.

The practical results have shown that, with the same heat protection values, weight savings of between 30 and 70% are possible, while at the same time significantly reducing flexural rigidity and improving flexibility, which also makes it easier to assemble.

To increase the strength, the fleece 1 can also be provided with reinforcing threads 5 running in the warp direction and reinforcing threads 6 running in the weft direction. In this case, 9 reinforcing threads 5/inch and 7 reinforcing threads 6/cm can be embedded in the warp direction.

The reinforcing threads 5 and 6 can be made using a magazine weft raschel machine with fleece template with polyamide-imide warp yarn and a weft yarn on the same

sis with a spacing of 3 mm in the warp and a spacing of 35 mm in the weft/9. The yarn count in this case is 80 dtex.

Composition example 2:

According to the example in Fig. 2, there is a first fleece IA and a second fleece IB, each having a basis weight of 35 g/m ² made of 100% partially graphitized polyacrylonitrile fibers with a titer of 1.7 dtex, which are laid down with a card and cross-layer and then hydroentangled according to the conditions stated in composition example 1. The two fleeces IA and IB are bonded together by an adhesive 2, which can have the same composition as in the composition example according to Fig. 1. This can be done by lamination in a continuous press. If the two fleeces IA and IB are placed on top of each other differently according to their fiber direction, the same strength can be achieved in all planes. This means that the composite of the two fleeces IA and IB is thus equally stretchable in all directions.

• · ♦ ·

•♦ ·

-14-

Adhesive 2 is again applied to the free surface of the fleece IA and a metallized film 3 is laminated onto it. In contrast to the assembly example 1, in this case the metallized film 3 is thicker and is not provided with a carrier film. A rolled aluminum foil can be used as the metallized film for this purpose. In this way, the unit becomes stronger and more rigid, but it can also be subjected to greater loads and can therefore be used as face protection, for example.

Another possibility for coating the fleece 1 or the two fleeces IA and IB is to apply a vapor directly in a high vacuum and in this way to carry out direct metallization or to apply metal particles as a layer or film to the fleece.

Composition example 3:

The example shown in Fig. 3 is basically of the same structure as the two compositions discussed above.

The only difference is that

* «a

· · ■

Between the two fleeces IA and IB a grid 7 is inserted, which serves for reinforcement and can consist of carbon fibers, for example. In this case, a metallized film 3 with a carrier film 4 is again shown, although of course a metallized film 3 without a carrier film can also be used in this case.

Claims (1)

1. Heat protective clothing with an inner high temperature resistant, insulating and flame retardant fabric or fleece made of fibres and an outer metallisation or a metallised film, characterized in that the fleece (1,IA,IB) comprises partially graphitized polyacrylonitrile fibers, and that the fleece (1,IA,IB) thus provided is provided with the metallized film (3) or metallization. 2. Heat protective clothing according to claim 1, characterized in that • f * -2- Reinforcing threads (5,6) running in warp/weft arrangement are incorporated into the fleece (1). 3. Heat protective clothing according to claim 2, characterized in that in the warp direction there are 4 to 24 threads/cm and in the weft direction there are 4 to 15 threads/cm. [ ( j 4* Hitseschuci.ii,f*id—«g according to Ar.sprüci:* 3, characterized by the fact that in the warp direction there are 8 to 10 threads/inch and in the weft direction there are 6 to 8 threads/cm. 5. Heat-resistant clothing according to claim 3 or 4, characterized in that the basis weight of the fleece (1) is between 40 and 100 g/m ¹ and the reinforcing threads (5,6) in an amount of 12 to 200 g/m'. 6. Heat protective clothing according to one of claims 2 to 5, characterized in that the polyacrylonitrile fibers have an LOI value of at least 40 and at least the reinforcing threads (5) running in the warp direction have an LOI value of less than 27. -3- 7. Ilitz protective clothing according to one of claims 2 to 6, characterized in that I the reinforcing threads (5,6) are made of thermoplastic material. 8. Heat protective clothing according to claim 7, characterized in that the thermoplastic material is polyester. 9. Heat protection clothing according to claim 6, characterized in that the reinforcing threads (5, 6) consist of polyamide-imide. 10. Heat protection clothing according to claim 1, characterized in that/9 the fleece (IA) is laminated with a second fleece (IB), and/3 one of the two fleeces (IA, IB) is provided with the metallic foil (3). 11. Ilitz protective clothing according to claim 10, characterized in that the two fleeces (IA, IB) have at least approximately the same chemical composition. -4- 12. Heat protection clothing according to claim 10, characterized in that the second fleece (IB) contains aramid fibers, glass fibers, carbon fibers, flame-retardant cotton fabric, ceramic fibers or mixtures thereof. 13. Heat protection clothing according to one of claims 1 to characterized in that a grid (7) made of high-temperature-resistant and flame-retardant material is arranged between the fleece (1) and the metallized film (3). 14. Heat protective clothing according to one of claims 10 to 12, characterized in that/9 a grid fabric (7) made of a high-temperature-resistant and flame-retardant material is arranged between the two fleeces (IA,IB). 15. Heat protection clothing according to claim 13 or 14, characterized in that the grid fabric (7) comprises carbon fibers. -5- 16. Heat protective clothing according to one of claims 1 to 15, characterized in that the adhesive (2) for coating the fleece (1) or the fleeces (IA,IB) with each other and the metallic film (3) is based on polyurethane or polyester. { 17. Heat protective clothing according to claim 16, characterized in that/9 mineral and/or organic flame retardants are added to the adhesive (2). 18. Heat protective clothing according to claim 17,
characterized in that the adhesive agents (2) are carbon dioxide and/or water-releasing substances, such as hydroxides and/or carbonates. 19. Heat protective clothing according to claim 16,
characterized in that organobromine compounds, in particular combined with antimony oxides, are added as flame retardants. 20. Heat protective clothing according to one of claims 17 mi )l until 19, characterized in that/3 flame retardants are added in an amount of 20 to 40 percent by weight. 21. Heat protective clothing according to one of claims 1 to 20, characterized in that the metallized film (3) is provided on the outside with a carrier film (4) which can be removed after coating. 22. Heat protection clothing according to claim 21, characterized in that the carrier film (4) is made of a polymer. 23. Protective clothing according to one of claims 1 to characterized in that/9 the metallized layer or film (3) is applied to the fleece (1) directly by vapor deposition in a high vacuum.