REFERENCE TO RELATED APPLICATION

This application is a Divisional application of U.S. patent application Ser. No. 15/103,889, filed Jun. 13, 2016, the entire subject matter of which is hereby incorporated by reference.

FIELD OF THE INVENTION

The invention relates to a flame-resistant closure piece that is adapted to a corresponding closure piece such that a detachable closure is formed. The closure piece has at least one flat basic fabric of warp threads and weft threads, with functional elements that protrude on the front side of the basic fabric. The basic fabric is provided with a flame-resistant finish. The invention further relates to a flame-resistant finish or coating for a closure piece, in particular for the aforementioned closure piece.

BACKGROUND OF THE INVENTION

EP-B-0 883 354 discloses a flame-retardant fastening element, in particular a closure piece, which is adapted for releasable engagement to a second fastening element, and which has

- a backing layer of a flame-retardant polymer material with an exposed bonding surface and a support surface;
- several flexible, elastic stem portions as functional elements, which generally extend perpendicular to the bonding surface, with the distal stem portions having an enlarged head portion arranged on a distal end of the stem portion, with the enlarged head portion having a top side opposite the distal stem portions, with a latching surface opposite the bonding surface, and with the head portions being disposed to enable movement along different portions of the backing layer and into a releasable engagement with the second fastening element; and
- a non-flame retardant, pressure-sensitive adhesive that is applied to the support surface.

The prior art fastening element thus fulfills the requirements of the vertical burn test without attachment to a substrate set forth in F.A.R. 25.853(a)(1)(i). The provision or specification to this effect relates to such fastening systems that relate in particular to applications in vehicle and aircraft technology and that are used, for example, for fastening wall panels to the carrier structure of a cab of a railroad vehicle or for securing seat cover materials to airplane passenger seats and the like. In the area of aircraft technology in particular, stringent flame-resistance requirements, which can be considerably more stringent than those set forth in the aforementioned specification, are now being placed on these fastening systems.

With the prior art solution described above, in a preferred embodiment the non-flame retardant, pressure-sensitive adhesive is furthermore a foam layer of a pressure-sensitive acrylic foam adhesive. These adhesives are described by examples in more detail in WO-A-2005/017060. While the prior art solution already provides a very effective flame-retardant closure, it can nevertheless be expensive to implement, especially when it comes to the incorporation of the U-shaped fastening elements in the backing layer.

In addition to the use of standard plastic materials in the form of polyethylene, polyamide, or the like for the closure material as disclosed above, EP-B-0 883 354 already discloses the use of carbon material for producing a flame-retardant closure. This prior art solution forming a flame-retardant closure or closure piece has the loops, as well as the basic material of the loop portion as basic fabric. The loops protrude from the basic fabric as functional pieces or functional elements and are composed of carbon fibers. Accordingly, the hooks of the hook portion itself should be formed from wire. Although the loop portion as well as the hook portion, as a further functional element, have a textile nature in the prior art solution so that they can be processed, in particular sewn on, like standard textile contact closures, their flame resistance is approximately 1000° C. and hence far greater than that of standard textile contact closures. However, the use of carbon fiber material has likewise proven to be very expensive because carbon material, at least from today's standpoint, is only available for processing operations in sufficient quantities and at reasonable prices to a limited extent.

To address these disadvantages, EP-B-1 973 440 has already proposed a flame-retardant closure having at least one closure piece with at least one flat basic fabric of warp threads and weft threads and having protruding functional threads on the front side of the basic fabric that at least partially penetrate the basic fabric and form the individual closure elements. The basic fabric is non-flame retardant and has, at least on portions of its back side, a backing layer with a flame-resistant medium and/or with an active extinguishing medium. The basic fabric has a finish. The backing layer has, on its side facing away from the basic fabric, a bonding component in the form of an adhesive layer, for example.

That backing layer can be composed of a flame-resistant material, as is preferred, or is provided with an active extinguishing medium. Both material properties are also achievable with only one backing layer. The flame-resistant material for the backing layer can preferably be selected from the following substance groups:

- Ammonium phosphate (AP)
- Ammonium polyphosphate (APP)
- Aluminum trihydroxide (ATH)
- Magnesium hydroxide (MDH)
- Resorcinol bis-diphenylphosphate (PDP)
- Red phosphorus (RP)
- Tri-n-butyl phosphate (TBP)
- Tricresyl phosphate (TCP)
- Triphenyl phosphate (TPP)
- Melamine.

This prior art closure plus closure piece and finish used for the basic fabric also satisfies stringent flame resistance criteria such as the ones set forth in the AIMS 04-19-002 Specification (January 2005 edition) of Airbus S.A.S, under the title Hook and Loop Tape, Non Self-Adhesive Flame Propagation Resistant; Material Specification. In spite of these advantages regarding the flame resistance of the sought-after closure plus finish, this prior art solution is still complex. In particular, the use of the active extinguishing media described in more detail above is associated with correspondingly high implementation costs.

SUMMARY OF THE INVENTION

On the basis of this prior art, the invention addresses the problem of creating a flame-resistant closure piece plus a flame-retardant finish that can be generally used for closure pieces, which satisfy the general criteria and specifications for flame resistance while retaining the advantages of the prior art. In particular, a very high level of flame retardancy is ensured. Additionally, they can be obtained more easily and more economically from a manufacturing technology standpoint.

This problem is basically solved by a flame-resistant closure piece and by a flame-resistant finish or coating. According to the invention, the basic fabric and the functional elements are predominantly, preferably entirely, made of flame-resistant plastic materials. Because all relevant components for constructing a closure piece (i.e., the basic fabric of warp and weft threads as well as the functional elements and the finish) are of flame-resistant materials, the specified criteria such as FAR or AIMS test can be readily met or fulfilled.

The selection of the finish according to the configuration of features of the invention plays a key role in this process. In particular, if the finish itself or a coating to be applied to the closure piece is formed from a solvent-free, moisture-curing, reactive polyurethane prepolymer-based melt adhesive, all kinds of flame-resistant closure pieces can be generated in a functionally secure and cost-effective manner. There is no counterpart to this in the prior art.

Vertical as well as horizontal burn tests have shown that once lit, such a closure piece extinguishes itself immediately with essentially no flame persistence or dripping. To a large extent, it retains its functionality as a closure piece of an entire closure.

In addition to selecting the finish, other reliably functioning, flame-resistant closure pieces can be created if the warp and weft threads of the basic fabric are made of PA66 plastic materials and if PP plastic materials are used as thread material for the functional elements, such as loops and/or mushroom-shaped fastening elements.

Further improved results are achievable if the threads composed of PA66 and/or PP plastic materials have flame retardant additives that contain phosphorus compounds and/or triazine compounds and/or graphite constituents.

For the finish of the flame-resistant closure piece or other closure pieces, particular preference is given to using materials as finishes that have significant amounts of polyester-polyol or polyether-polyol within a melt adhesive system.

In particular, if the melt adhesive is a composition with the following formula:

- 10 to 90% polyester-polyol
- 0 to 50% polyether-polyol
- 5 to 35% polyisocyanate
- 2 to 50% flame retardant agents such as antimony- and halogen-free phosphorus compounds and/or triazine compounds, and
- additives such as catalysts and stabilizers as needed,
  
  a finish is achieved that fulfills the flame-resistance requirements for the product in every respect.

The finish or melt adhesive, respectively, can completely saturate the basic fabric of warp and weft threads and also parts of the functional elements, provided that the functional elements are formed from pile threads at least partially interwoven in the basic fabric. However, in addition or as an alternative, the finish can also be applied to the bottom side of a backing piece that, as a component of a cast closure, then bears the functional elements on its opposite top side.

If the basic fabric is saturated with the aforementioned finish, which is preferred, then furthermore an additional adhesive layer likewise preferably configured as flame-resistant and having a pressure-sensitive adhesive can be applied on the bottom side of the closure piece that faces away from the functional elements.

Other objects, advantages and salient features of the present invention will become apparent from the following detailed description, which, taken in conjunction with the drawings, discloses preferred embodiments of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Referring to the drawings that form a part of this disclosure and that are schematic and not to scale:

FIG. 1 is a top perspective view of a fabric structure of a contact closure piece according to an exemplary embodiment of the invention; and

FIG. 2 is a side view of the flat contact closure piece of FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows a view from above of a portion of a flat contact closure piece that can be extended ad infinitum within the image plane in either image direction. The geometric dimensions of the woven fabric depend upon the specifications of the weaving machine on which the closure piece is produced. In particular, these closure pieces are packaged for later use as rolls of contact closure tape (not illustrated).

The closure piece has warp threads 10 and weft threads 12, which threads are transversely interwoven to form the basic fabric 14 for the contact closure piece. Furthermore, in the basic fabric 14, functional threads 16 are provided in the form of pile threads, which form a further component of the basic fabric 14. The respective functional thread 16 then forms the individual functional or closure elements 18 for the flat contact closure piece, which shall be explained in more detail in the following. Furthermore, rather than threads the technical term yarns is often used.

An arrow 20 indicating the production direction for the closure piece to be manufactured is visible on the top side of FIG. 1. In the arrangement shown according to FIG. 1, the respective weft threads 12 are arcuately configured in the nature of a sine or a cosine wave. The warp threads 10 extend parallel to the production direction 20 and parallel to each other in a rectilinear arrangement at the intersections between warp threads 10 and weft threads 12. In the embodiment shown in FIG. 1, only the weft threads 12 are in an arcuately extending arrangement in the basic fabric 14. In an alternating sequence, the respective weft thread 12 passes over a warp thread 10 and passes under the next consecutive one. The advantages of such an arcuate configuration are explained in more detail in document DE-B-102 40 986 of the patent holder and therefore shall not be discussed any further here.

The functional or pile thread 16 forms a loop 22 above each place where it passes under the basic fabric 14, and then forms another loop 24 immediately afterwards, thus creating a V-binding. However, other types of binding are conceivable here, such as a W-binding or other similar binding of the functional thread 16.

The loops 22, 24 form a type of closure elements 18. If the loops 22, 24 remain closed as shown in FIG. 1, a fleece-type contact closure piece arises in which hook or mushroom-type closure elements 28 can engage in these loops 22, 24 in such a way as to obtain a releasable contact closure as part of a closure or fastening system as a whole. However, as illustrated in FIG. 2 it is also possible to cut the loops 22, 24 open along a dividing line 26 in such a way that, after melting the free ends of the opened loop, in each case a mushroom-shaped closure element 28 is formed. The mushroom-shaped closure elements 28 can then be hooked in a releasable manner with corresponding fleece material of another closure piece, not illustrated in any greater detail here, which serves as the other closure piece.

As further shown in the illustration of FIG. 2, an individual weft thread 12 can also be a weft thread pair or be multi-threaded. The same is true for the warp threads 10, which according to the cross sectional or schematic view of FIG. 2, in each case pass over a pair of weft threads 12 of the second closure piece and subsequently pass under this pair of weft threads 12 in alternating sequence. The respective functional or pile thread 16, skipping a weft thread pair 12 in each case, passes over the next two weft thread pairs 12 in the sequence shown. Hence the loops of a first kind 22 and of another kind 24 are arranged offset relative to each other on the basic fabric 14. The loops of the first kind 22 form essentially closed O-shaped loops. The loops of the second kind 24 are V-shaped or U-shaped in configuration. A repeating pattern for a function thread 16 therefore repeats itself in the direction of the weft threads 10 after five warp threads 10. To arrive at a flame-resistant or flame-retardant closure piece, the closure piece according to FIGS. 1 and 2 is constructed as described in greater detail in the following. The warp threads 10 and the weft threads 12 are thus formed from PA66 plastic materials, which in this case are monofilament polyamide threads or yarns. The thread or yarn systems are provided with a flame-retardant additive, in particular in the form of a phosphorus compound. The flame-retardant mechanism acts in the gas phase in particular. The effect is permanent and wash-resistant. In the PA66 thread system, use is made of an intrinsically flame-retardant polyamide fiber that does not contain any halogens. The textile properties of the PA fiber are not negatively impacted by the flame-retardant additive, and the fiber turns out to be high-strength. The polyamide-66 fiber in particular fulfills the specifications of DIN 4102-1, B1).

The pile threads 16, which as explained will eventually form the functional elements, are formed of PP plastic materials. The PP fibers are marketed under the brand name LIFOFLAM 70/101 PP. The polypropylene fiber is also high-strength and has a flame-retardant agent in the form of a suitable phosphorus compound.

Triazine compounds and/or thread systems containing graphite or other carbon constituents can also be used as flame-retardant additives in lieu of the aforementioned phosphorus compounds.

To provide the basic fabric 14 with a secure attachment and in particular to prevent the pile threads 16 from being pulled out of the basic fabric 14 under load, advantageously the basic fabric 14 is provided with a finish 30. In particular, the finish 30 is applied in such a way that all threads in the basic fabric system are coated with the finish 30.

Using a finish 30 with self-adhesive properties for the basic fabric 14 has proven to be particularly advantageous.

Experiments with a finish 30 of a polyurethane aqueous dispersion such as the one marketed under the trade name TUBICOAT PUS, with added flame-retardant agents such as those marketed under the brand names Apyrol PA1 and Apyrol PA2, result in very short burning distances and very short flame persistence compared to comparably configured hook and loop closure systems without such flame retardants added, especially in the FAR vertical burn test.

The following formula for the finish 30 binding the basic fabric has proven to be particularly suitable:

Apyrol PA1
7%

Apyrol PA2
7%

Tubicoat PUS
40%

Water
46%

MgCl₂
0.01%.

If an additional adhesive layer is to be applied preferably on the exposed bottom side of the finish 30, this layer is artificial rubber-based or acrylate-based. In the latter case, the acrylate is practical to be constituted as an aqueous dispersion and to add a flame-retardant agent to it, which agent is marketed under the trade name Apyrol PP46 and contains ammonium salts in addition to polyphosphoric acids. To be able to bind the basic fabric 14 provided with a finish 30 with third components, provision can be made such that an additional adhesive layer 32 is applied to the bottom side of the finish 30 facing away from the protruding functional elements 18. This adhesive layer 32, which is applied to the finish 30 like a coating, can be, for example, a flame-resistant pressure-sensitive adhesive or adhesive system. If the adhesive layer 32 is covered by a suitable paper material (not illustrated) on the surface exposed to the surroundings, the closure piece can be set directly on third components after the cover paper on the adhesive layer 32 is removed.

However, constituting the finish 30 from a solvent-free, moisture-curing, reactive polyurethane prepolymer-based melt adhesive has proven to be particularly advantageous from a flame retardancy standpoint. Such a polyurethane melt adhesive is marketed under the brand name AdtraPUR F 9131-UV. The finish to be applied like a coating for the basic fabric 14 should in particular be applied at the rate of between 40 to 200 g/m², preferably 120 g/m². The particularly preferred finish to apply has the following formula:

- 10 to 90% polyester-polyol,
- 0 to 50% polyether-polyol,
- 5 to 35% polyisocyanate,
- 2 to 50% flame-retardant agent such as antimony- and halogen-free phosphorus compounds and/or triazine compounds, and
- additives such as catalysts and stabilizers, as needed.

In this regard, particular mention is made of UV stabilizers and antioxidants, which owing to their low concentration cannot negatively impact the process parameters during the manufacturing of the closure piece.

For the average skilled professional in the field of contact closure technology, it is surprising that, with the coating-like finish 30 evenly applied subsequently to a finished, non-flame retardant hook and loop closure piece that can also be cast, surprisingly the standard flame-resistance requirements of the aircraft industry cannot only be fulfilled, but that furthermore the recently required composite test will also be passed. For instance, if the hook and loop closure with its one closure piece is sewn on in the form of a textile sheeting material that serves as, say, a curtain or a seat cover, it is no longer sufficient just to document the flame resistance of the contact closure piece. Instead, the composite as a whole must be tested for flame resistance. Owing to the finish 30 presented herein, such composite tests can be performed effortlessly and successfully, provided that the corresponding closure pieces and/or the textile basic material of the composite partner are likewise configured as flame-resistant.

In spite of the relatively high concentration of flame retardant agents, the wash fastness of the entire closure system is retained even at very high temperatures, for example in the context of 95° C. hot washes. The stringent conditions for the use of chemicals are assuredly fulfilled. The European standards and directives currently in effect are fulfilled with the finish system described above.

Overall, the criteria listed for the individual flame resistance tests can be more than adequately fulfilled with a closure piece equipped or provided with the aforementioned materials. Practical experiments have shown that compared to prior art systems, the flame persistence, the components of the closure piece dripping off under heat, and the measured burning distance can be reduced considerably, if need be to virtually zero.

While various embodiments have been chosen to illustrate the invention, it will be understood by those skilled in the art that various changes and modifications can be made therein without departing from the scope of the invention as defined in the claims.