COOLING FABRIC

Abstract

A cooling fabric including a moisture-permeable inner surface layer, a spacer fabric and an outer surface layer, wherein the outer surface layer has an air permeability of at most 250 l/dm2/min at 500 Pa measured according to ISO 9237 and wherein the spacer fabric comprises monofilaments extending across the spacer fabric, wherein the monofilaments have a linear density of at least 250 dtex and wherein the monofilaments are present at a density of at most 800 monofilaments per square-inch.

Claims

1. A cooling fabric comprising a moisture-permeable inner surface layer, a spacer fabric and an outer surface layer, wherein the outer surface layer has an air permeability of at most 250 l/dm2/min at 500 Pa measured according to ISO 9237 and wherein the spacer fabric comprises monofilaments extending across the spacer fabric, wherein the monofilaments have a linear density of at least 250 dtex and wherein the monofilaments are present at a density of at most 800 monofilaments per square-inch.

2. The cooling fabric according to claim 1 wherein the monofilaments have a linear density of at least 300 dtex.

3. The cooling fabric according to claim 1 wherein the monofilaments are present at a density of at most 700 monofilaments per square-inch.

4. The cooling fabric according to claim 1 wherein the moisture-permeable inner surface layer comprises nanofibers having a filament diameter of at most 5 ?m.

5. The cooling fabric according to claim 1 comprising thermoconductive fibers.

6. The cooling fabric according to claim 5 wherein the thermoconductive fibers are selected from the group of metal fibers, metal-coated fibers, ceramic fibers, carbon fibers, and fibers provided with a coating of a substance having a thermal conductivity of at least 150 W/(m K).

7. The cooling fabric according to claim 1 wherein the spacer fabric has a thickness of at least 2 mm.

8. The cooling fabric according to claim 1 wherein the outer surface layer comprises a thermoplastic resin or a fiber.

9. An article comprising the cooling fabric according to claim 1.

10. The article according to claim 9 comprising at least one air ventilation means and at least one power source.

Description

EXAMPLE 1

[0065] Several cooling garments made for the size of the human upper body were tested. The cooling fabrics are constructed into a cooling garment as shown in FIG. 2a, in such a way that the front part and the back part (dark grey parts) of the torso are covered with the cooling fabric. In FIG. 2a the left panel presents the front of the garment and the right panel presents the back side of the garment. The sides and the arms of the garment (light gray parts) are made from Lycra? fabric to ensure perfect torso fitting of the garment.

[0066] The cooling fabric is provided with several ventilators in order to achieve air flow inside the garment. The ventilators are positioned on the front (2?) and on the back (4?) in a way as is depicted in FIG. 2b. In FIG. 2b the left panel presents the back of the garment and the right panel presents the front side of the garment.

[0067] The ventilators are powered by means of a battery and are directly blowing into the spacer fabric, at a maximum air flow of 65 m.sup.3/hr per ventilator. Different cooling garments have been tested on a sweating thermal manikin which simulates the heat loss from the human body. The cooling garment test was performed in accordance with ASTM F2371-5. The thermal manikin test conditions used were:

[0068] 1. Surface temperature (35? C.)

[0069] 2. Ambient temperature/Relative humidity (%) (25? C./40%)

[0070] 3. Upper body sweat rate (0.48 L/hr)

[0071] The cumulative heat flux (or cooling capacity) is measured during 1 hour testing. The torso of the manikin was dressed in one of the cooling garments described below (Samples 1-9). On top of the cooling garment a standard fire fighter suit was placed which covered the whole manikin, including the lower part of the body, the head and the hands. The cumulative heat flux was determined for the torso part of the body.

[0072] Six of the tested cooling garments consist of a moisture-permeable inner surface layer, a spacer fabric and an outer surface layer.

[0073] For these cooling garments different spacer fabrics and moisture-permeable inner surface layers were combined. The outer surface layer for Samples 1-6 was a thermoplastic polyurethane film.

[0074] Samples 1, 3 and 5 comprise a spacer fabric (1) according to the invention. This type of spacer fabric allows an air speed of 1.3 m/s.

[0075] Spacer fabric type 1 has the following properties:

TABLE-US-00001 Material: 100% polyethyleneterephthalate Monofilament density: 155 counts/inch.sup.2 (24 counts/cm.sup.2) Monofilament linear density: 656 dtex/filament Construction: warp knit fabric, 6.5 courses per cm, 2 wales per cm Thickness: 10 mm Surface pore size: 7 mm Mass per unit area: 530 g/m.sup.2

[0076] In contrast, Spacer fabric type A (comparative) allows an air speed of below 0.5 m/s and has the following properties:

TABLE-US-00002 Material: 100% polyethyleneterephthalate Monofilament density: ca. 3870 counts/inch.sup.2 (150 counts/cm.sup.2) Monofilament linear density: 33 dtex/filament Construction: warp knit fabric, 17 courses per cm, 10 wales per cm Thickness: 5 mm Surface pore size: 2 mm Mass per unit area: 432 g/m.sup.2

[0077] Both spacer type fabrics were combined with different moisture-permeable inner surface layers: a cotton fabric (standard cotton 10 A, WFK Testgewebe GmbH), a polyester fabric or a polyester nanofiber fabric.

[0078] The polyester fabric has the following properties:

TABLE-US-00003 Fiber diameter: 2 ?m Construction: warp knit fabric

[0079] The polyester nanofiber fabric has the following properties:

TABLE-US-00004 Fiber diameter: 700 nm Construction: warp knit fabric

[0080] Furthermore, three commercially available cooling garments were also tested in the thermal manikin test (Samples 7-9).

[0081] The commercially available cooling garments are E-Cooline (Sample 7), Glacier Tek Cool vest (Sample 8), Rakuten U500B cooling Vest (Sample 9).

[0082] Sample 7 is a cooling garment which requires to add water into the vest, Sample 8 is an example of a phase change cooling type garment and Sample 9 is a commercially available example of air cooling.

[0083] Table 1 shows the cooling capacity of the different cooling garments:

TABLE-US-00005 TABLE 1 Thermal manikin test for determining heat flux MP inner Type of spacer Air speed in Heat flux Sample layer fabric spacer (m/s) (kW/m.sup.2) Sample 1 - Polyester 1 1.3 306 inv. nanofiber Sample 2 - Polyester A <0.5 84 comp. nanofiber Sample 3 - Cotton fiber 1 1.3 172 inv. Sample 4 - Cotton fiber A <0.5 66 comp. Sample 5 - Polyester 1 1.3 275 inv. fiber Sample 6 - Polyester A <0.5 95 comp. fiber Sample 7 - unknown unknown unknown 97 comp. Sample 8 - unknown unknown unknown 45 comp. Sample 9 - unknown unknown unknown 52 comp. MPmoisture permeable, inv.according to the invention, comp.comparative

[0084] As can be seen from the data of table 2, the cooling garments according to the invention (Samples 1, 3 and 5) clearly outperform the commercially available cooling garments (Samples 7-9), but also the cooling garments where the spacer fabric has an air speed of below 0.5 m/s.

EXAMPLE 2

[0085] The cooling capacity of several spacer fabrics was compared.

[0086] For this purpose, the air resistance and the evaporation properties of six different spacer fabrics were determined.

[0087] Spacer 1 (according to the invention) and spacer A (comparative) were also used in Example 1. Further, spacers 2-4 (according to the invention) and spacer B (comparative) were also tested. All spacers are made of 100% polyethyleneterephthalate.

[0088] The air resistance of the spacers was determined as described above.

[0089] The monofilament density and relative pore area were determined by microscopy (as indicated above).

[0090] The evaporation properties were determined by the following method:

[0091] The experimental setup was made with the intention to simulate a sweating skin covered with a ventilated spacer fabric. The sweating skin is resembled by an water bath set to 35? C. A foam layer is placed on a support into the waterbath, such that the foam is partly emersed in water, but the foam is over its whole thickness saturated with water. For example, a polyether foam of 10 mm thickness may be emersed for 7 mm. The layer of foam assures a steady state water transport to the surface. The spacer fabric to be tested is placed on the foam and serves as a passage for the ambient air that is blown through. Using a ventilator (e.g. a Sunon KD 1208 PTSI 1.8 W ventilator), air is blown into the spacer, in the same way as for the air speed determination (described above and in FIG. 1) but allowing evaporation.

[0092] The whole setup (including the water bath, foam, spacer and ventilator) is placed on a precision scale (e.g. Kern DS 20K0.1 0.1) which allows digital analysis of the decrease of weight within a certain timeframe as a measure for the rate of evaporation. The temperature of the water bath, the spacer fabric and the surrounding air were measured with a thermocouple and logged to a file. At the same time the weight was determined (once per second) and also logged to the file. The complete setup is placed in a WEISS WK3-180/40 4.1 kW climate chamber to validate the theoretical expectations under a set temperature of 25? C. and relative humidity (Rh) of 40%. During the tests, the voltage was always set to the ventilator maximum, 12V (and thus 0.15 A).

[0093] Based on the mass of evaporated water per time unit (gram/second), the evaporation area of the spacer fabric (A4 size) and the heat of evaporation of water (J/g), a cooling capacity (W/m.sup.2) is determined.

[0094] The cooling capacity of each spacer fabric was determined three times at 25? C. and 40% Rh for 10 minutes and calculated by the following formula:

Cooling capacity (W/m.sup.2)=[Mass loss/time (gram/second)]*K/[area (m.sup.2)].

[0095] The constant K is the heat of evaporation of water at the used temperature and relative humidity (2400 J/g).

[0096] Subsequently, an average value was calculated from the three measurements (in W/m.sup.2).

TABLE-US-00006 Monofilament Monofilament Relative Air resistance Cooling Thickness Mass/area Filament LD density pore area (?P mm capacity Sample (mm) (g/m.sup.2) (dtex) (number/inch.sup.2) (%) H.sub.2O) (W/m.sup.2) 1 10 477 676 155 62 4.5 612 2 10 445 798 77 62 2.0 742 3 10 581 800 77 54 2.5 723 4 6 441 465 142 56 10 755 A 5 429 33 ca. 3870 20 56 469 B 8.5 683 233 970 20 22.5 591 n.d. = not determined, estimated to be >1000/inch.sup.2

[0097] Table 2 shows the properties of the different spacer fabrics

[0098] The data show that the spacers used in the invention result in a lower air resistance and higher cooling capacity. This is expected to result in a better cooling effect of the cooling fabrics comprising the spacer fabrics.