| JP2005105447 | FIBER STRUCTURE |
| JP2005336695 | GLASS CLOTH |
| WO/1994/005840 | A METHOD OF INSERTION OF THE WEFT THREAD INTO THE SHED OF AN AIR-OPERATED JET LOOM AND A DEVICE FOR CARRYING OUT THE METHOD |
Claims:
1. Fabric (10), in particular for shading purposes, formed of interwoven warp and weft threads (1 , 2) based on fluoropolymer plastics, wherein the fabric (10) comprises an upper side and an underside having colors that are different from one another, characterized in that the fabric (10) is inter- woven from the warp and weft threads (1 , 2) in a three by three twill weave with step two, wherein the warp threads (1) and (n+2) consecutive weft threads (2) are made in the color of the upper side of the fabric (10) and n following consecutive weft threads (2) are made in the color of the underside of the fabric (10), and n is an integer greater than or equal to 1.
2. Fabric according to Claim 1 , characterized in that n is an integer less than or equal to 4.
3. Fabric according to one of the Claims 1 or 2, characterized in that the warp threads (1) and three consecutive weft threads (2) are made in the color of the upper side of the fabric (10), and every fourth weft thread (2) is made in the color of the underside of the fabric (10).
4. Fabric according to one of the Claims 1 to 3, characterized in that the warp and weft threads (1 , 2) are formed of polytetrafluoroethylene.
5. Fabric according to one of the Claims 1 to 4, characterized in that the warp threads (1) have a thread count of 90 to 120 threads/cm.
6. Fabric according to one of the Claims 1 to 5, characterized in that the warp threads (1) have a yarn size of 380 to 440 dtex.
7. Fabric according to one of the Claims 1 to 6, characterized in that the warp threads (1) are twisted with 500 to 700 t.p.m. about their longitudinal axis.
8. Fabric according to one of the Claims 1 to 7, characterized in that the weft threads (2) have a thread count of 45 to 60 threads/cm.
9. Fabric according to one of the Claims 1 to 8, characterized in that the weft threads (2) made in the color of the upper side have a yarn size that is less than that of the weft threads (2) made in the color of the underside.
10. Fabric according to Claim 9, characterized in that the weft threads (2) made in the color of the upper side have a yarn size of 380 to 420 dtex, and the weft threads (2) made in the color of the underside have a yarn size of 440 to 480 dtex.
11. Fabric according to one of the Claims 1 to 10, characterized in that the weft threads (2) are formed of single threads twisted with 500 to 700 t.p.m about their longitudinal axis in a first direction of rotation, of which two at a time are twined together with 300 to 400 t.p.m in the opposite direction of rotation about their axis of rotation.
12. Fabric according to one of the Claims 1 to 11 , characterized in that two parallel weft threads (2) at a time are interwoven as a weft.
13. Fabric according to one of the Claims 1 to 11 , characterized in that the upper side has a white coloring, and the underside has a sand-colored coloring.
14. Fabric according to one of the Claims 1 to 13, characterized in that it has a weight per unit area of 900 to 930 g/m 2 .
15. Fabric according to one of the Claims 1 to 14, characterized in that it has a thickness of 0.57 to 0.61 mm. |
Klaus Bloch 53757 St. Augustin (DE)
Fabric, in particular for shading purposes
Background of the Invention:
The invention relates to a fabric, in particular for shading purposes, formed of interwoven warp and weft threads based on fluoropolymer plastics, wherein the fabric comprises an upper side and an underside having colorings that are different from one another.
It is already known to use fabrics made from fluoropolymer plastics, in particular polytetrafluoroethylene (PTFE) for textile constructions, for example, long-span structures. The weights per unit area used herein as a rule lie between 300 and 2,200 g/m 2 , with all conceivable weaves of plain weaves, twill weaves, Panama weaves and special weaves being applied. Here, PTFE yarns of 380, 440, 880 and 1,200 dtex are being used as single yarns or in twist structures with many different yarn and twist structures. The PTFE yarns used are, in part, naturally white, or also colored, such as sand-colored, green, blue, red, or yellow.
In 1992/93, for example, twelve large-scale screens in white, each with a size of approx. 600 m 2 , were installed in the Medina mosque as an outdoor long-span structure using such PTFE weaves.
Pure PTFE is mainly used in fabrics for shading purposes that are exposed to such a high degree of insolation, because, according to current knowledge, only PTFE plastics are subject to almost no degradation of strength in regions of
such a high exposure to heat and, in particular, ultraviolet irradiation, and since a life span of 25 years and more can be assumed for such fabrics.
Additionally, with regard to prior art, reference may also be made to DE 20 2006 008 868 U1.
However, one problem of the known PTFE fabrics is that they exhibit only an inadequate shading effect, in particular if colored white. By increasing the weight per unit area from between 600 to 700 g/m 2 to at least 900 g/m 2 , an im- provement could be made which, however, is not sufficient. On the other hand, the problem of insufficient shading effect is also not solved in a satisfactory manner by augmenting the material with colored PTFE yarns, such as, for example, brown or preferably sand-colored yarns, or producing the material exclusively from them, because, though the shading effect is increased thereby, the reflecting properties of a pure white fabric vis-a-vis sunbeams, which is at least as important, is lost at the same time, so that only an insufficient reflection of sunbeams takes place, which makes the temperatures under the shading fabric rise in an undesired manner. In colored blended fabrics, the important characteristic values, namely transmission and absorption, as well as heat transfer of the fabric under insolation, are also unfavorable due to reflection being reduced as compared with a pure white fabric, that is, an increased temperature is caused under the fabric, which must be avoided under all circumstances.
Furthermore, it is known to form a fabric with different colors on its upper and underside, for example, by printing on one side of the fabric or providing it with a coating that has another coloring different from the fabric itself. However, such a coating is difficult to produce and, with regard to its long- term stability, particularly susceptible to UV irradiation, and it furthermore impairs the flexibility of the fabric, which has a very adverse effect, for example if such fabrics are used in umbrellas, on the foldability of the fabric in case it is not used, and which leads to significantly increased weights per unit area, which in turn cause increased mechanical strain on the fabric and its supporting structure.
Summary Description of the Invention
It is the object of the present invention to propose a fabric of the kind described in the introduction, which overcomes the problems of the prior art.
According to the invention, a fabric having the features of the patent claim 1 is proposed for solving the set object. The invention proposes to interweave the fabric from the warp and weft threads in a three by three twill weave with step two, and to make the warp threads and (n+2) consecutive weft threads in the color of the upper side of the fabric and to make n following consecutive weft threads in the color of the underside of the fabric, where n is an integer greater than or equal to 1.
Advantageous embodiments and developments of the invention are the subject matter of the dependent claims.
Brief description of the drawings
Fig. 1 shows a schematic perspective view of a fabric according to the present invention, seen from the upper side.
Full Description of the Invention
In Fig. 1 there is shown a fabric 10 according to the present invention, made of a series of warp threads 1a, 1b and so on, generally denoted by referece numeral 1 , and a series of weft threads 2a, 2b, 2c, 2d, 2e, 2f and so on, generally denoted by reference numeral 2, and being interwoven with each other in a manner described below.
The invention proposes to interweave the fabric 10 from the warp and weft threads 1 , 2 in a three by three twill weave with step two, and to make the warp threads 1 and (n+2) consecutive weft threads 2 in the color of the upper side of the fabric 10 (shown in Fig. 1) and to make n following consecutive weft threads
2 in the color of the underside of the fabric 10, where n is an integer greater than or equal to 1.
A three by three twill weave with step two is a well known weaving method for a person skilled in the art. In such three by three twill weave each warp thread 1runs over three weft threads2 , followed by running under the next three weft threads 2 and so on.
As can be seen from Fig. 1 , particular warp thread 1a first runs over three con- secutive weft threads 2a, 2b and 2c on the upper side of the fabric 10 and then runs under the next three consecutive weft threads 2d, 2e, 2f and so on.
Step 2 means that each consecutive warp thread will change from running over or under the weft threads, respectively, in a position two weft threads later than the preceeding warp thread.
As can be seen from Fig.1 warp thread 1a changes from running over the weft threads to running under the weft threads between weft threads 2c and 2d. However, the next warp thread 1b of the fabric 10 changes two weft threads later, namely between weft threads 2e and 2f from running over the weft threads to running under the weft threads.
Surprisingly, a high-strength fabric 10 that is suitable for shading purposes is formed by this selection of a weaving method according to the invention and by the coordinated coloring of the warp and weft threads, the upper side of the fabric being homogeneous in the one color, and its underside being homogeneous in the other color.
If the warp threads 1 and (n+2) consecutive weft 2 threads, respectively, are being made in white, and then, n weft threads 2 in a brown, preferably sand- colored coloring, the fabric 10 according to the invention is colored purely white on its upper side and purely sand-colored on its underside, without a weaving pattern showing.
This effect can be achieved with various values for n, it being considered appropriate to set n as follows:
1 < n < 4.
For example, three consecutive weft threads as well as all warp threads can be made in the color of the upper side, e.g., white, and the following fourth weft thread can be made in the color of the underside, e.g. brown or sand-colored.
Within the context of the invention, it is thus possible to manufacture a fabric 10, in particular for shading purposes, without additional coating or printing and the disadvantages connected therewith, which is characterized by very high reflectivity of sunbeams due to the pure white coloring of the upper side, and at the same time, due to a darker coloring of the underside, also by a sufficient shad- ing effect, which is adjustable at will.
Thus, the fabric 10 according to the invention is suitable, in particular, for the manufacture of shading devices, for example long-span structures, in which a very high reflection of sunbeams and, at the same time, good shading are of paramount importance. Naturally, however, other color combinations can also be produced without any problems, depending on areas of use and desired effect, because in that case, the warp and weft threads 1 , 2 must merely be selected and used in the appropriate coloring.
With a view to sufficient stability against UV radiation, the warp and weft threads 1 , 2 are preferably formed of pure polytetrafluoroethylene, and furthermore, they are preferably cut in the appropriate yarn size from a flat sheet material.
The warp threads 1 of the fabric according to the invention preferably have a thread count of 90 to 120 threads/cm, and they are made in a yarn size of 380 to 440 dtex.
In order to generate a higher strength, the warp threads 1 are furthermore twisted with 500 to 700 turns per meter (t.p.m.) about their longitudinal axis.
The weft threads 2 preferably have a thread count of 45 to 60 threads/cm, wherein the weft threads 2 made in the color of the upper side furthermore have a yarn size that is less than that of the weft threads 2 made in the color of the underside. For example, it may be provided to make the weft threads 2 made in the color of the upper side in a yarn size of between 380 to 420 dtex, so that they correspond to the yarn size of the warp threads 1, and to design the weft threads 2 made in the color of the underside in a larger yarn size of, for example, 440 to 480 dtex.
The weft threads 2 are also preferably twisted about their longitudinal axis, also with about 500 to 700 t.p.m. in a first direction of rotation. It is further preferred that the weft threads 2 are formed of two single threads twisted in this manner, which, having been twisted individually, are twined together with about 300 to 400 t.p.m. in the opposite direction of rotation. In conjunction with also the warp threads 1 being twisted, the fabric 10 according to the invention obtains a strength that is almost the same in the direction of both the warp and the weft, which is very advantageous in particular for applications of the fabric 10 according to the invention in round formats.
It is furthermore preferred that two such weft threads 2 at a time are inserted into a shed in parallel and that together, they form a weft of the fabric 10 according to the invention.
At the same time, the three by three twill weave provided according to the invention provides a high seam strength, and the fabric 10 according to the invention is rain-proof even without additional coating or finish.
Preferred weights per unit are of the fabric 10 produced according to the inven- tion lie in the range from between 900 to 930 g/m 2 at a thickness of 0.57 to 0.61 mm.
Exemplary Embodiment:
As a fabric for shading purposes, in particular for use as an outdoor bearing structure, white warp threads having a thread count of 98 threads/cm, with a tolerance of ± 5%, and a yarn size of 380 dtex and with 700 t.p.m. were twisted, and weft threads having a thread count of 53 threads/cm ± 5% were used, wherein the respective first and third weft threads with a white color were used, matching the warp threads, in a yarn size of 380 dtex, which were formed of single threads twisted with 700 t.p.m., and then, in pairs of threads twined with 300 t.p.m. in the opposite direction. The respective fourth weft thread was sand- colored, had a yarn size of 440 dtex, and was twisted from single threads with 700 t.p.m., and then, twined in pairs of threads with 300 t.p.m. in the opposite direction.
Thus, n was set to be equal to 1.
Using a three by three twill weave with step two, these warp and weft threads became a fabric with a fabric weight of 905 g/m 2 and about 0,59 mm thickness.
A pure white upper side of the fabric and a sand-colored underside corresponding to the color of every fourth weft thread used appeared, which had comparable strengths in the directions of warp and weft, and which provided for rain proofness.
The fabric thus formed was subjected to a measurement of the radiometric, photometric and UV characteristic values (transmission, reflection, absorption) in accordance with DIN EN 410, with the results determined for almost normal incidence (0° for transmission, 8° for reflection) on the white or sand-colored side of the fabric being given in the following table.
Alternatively, n may also be 2, 3 or 4, i.e., where
• n = 2 the first four weft threads are made in the color of the upper side and the next two weft threads in the color of the underside
• n = 3 the first five weft threads are made in the color of the upper side and the next three weft threads in the color of the underside
n = 4 the first six weft threads are made in the color of the upper side and the next four weft threads in the color of the underside
This does not change the intended effect of, for example, a white upper side and an underside that is colored differently thereto, only the color intensity of the underside increases with a growing n.