Use of composite materials for absorbing and distributing liquids in active and / or passively cooled fluid-carrying systems

Abstract

A composite material for receiving and distributing liquid in an actively and / or passively cooled current-carrying system, in particular in an actively and / or passively cooled power storage system, the composite material comprising a carrier layer and a liquid-receiving layer fixed to the carrier layer, wherein the liquid-receiving layer contains fixed superabsorbent particles, wherein a liquid distribution layer is arranged on the side of the liquid-receiving layer facing away from the carrier layer and is in liquid-conducting contact with the liquid-receiving layer, and the liquid distribution layer receives and distributes the liquid to be received in the plane of the composite material.

Description

Technical Field

[0001] The present invention relates to the use of a composite material for absorbing and distributing liquids in actively and / or passively cooled current-carrying systems, in particular in actively and / or passively cooled electrical storage systems. The invention also relates to an absorbent pad comprising the composite material and an actively and / or passively cooled current-carrying system. Background Art

[0002] Current-carrying systems, and in particular battery systems, are becoming increasingly important because they are essential for driving electric and hybrid vehicles. As is well known, a "current-carrying system" is a system through which electric current flows. A practically relevant current-carrying system is a "storage system," i.e., a system used to store energy that is currently available but not required for later use. This storage is usually accompanied by a conversion of the energy form, for example from electrical energy to chemical energy. If necessary, the energy is then converted back into the required electrical form. Battery systems are known as modules connected in series or parallel, each containing secondary or primary cells connected in series or parallel. Another storage system is a battery, i.e., a module connected in series or parallel, each containing secondary cells connected in series or parallel. Also practically relevant is a capacitor, i.e., a passive electrical component that can statically store charge and the associated energy in the electric field of a DC circuit.

[0003] To ensure optimal system functionality, the battery cell temperature must be maintained within the desired temperature range. Active or passive temperature control systems are used to prevent exceeding and / or falling below the operating temperature. The use of a liquid temperature control medium with a high heat capacity, which is guided along the battery cells in a heat exchanger with good thermal conductivity, has proven particularly effective.

[0004] Furthermore, these systems are usually not hermetically sealed from the surrounding environment. This means that they allow for gas exchange with the surrounding environment. To prevent the infiltration of pollutants, the incoming air is filtered. For example, microporous membranes or nonwovens are used for this purpose.

[0005] While all of these methods allow for particle filtration, they don't allow for gas filtration, and in particular, water vapor. Consequently, water vapor can pass through the membrane and into the electronics housing. However, since the housing interior is cooled, water condenses at cold spots in the housing (when its dew point is exceeded). Since current-carrying components are particularly cooled, condensation forms in the most critical locations.

[0006] Furthermore, if the housing itself remains at a low temperature, any condensate that forms can be difficult to remove from the housing. Pumps, controlled valves, or heating are possible options. These methods are complex and potentially error-prone. Furthermore, heating is prohibited in many applications, such as battery systems.

[0007] A suitable water-absorbing medium is a desiccant, which is installed in or in front of the housing and irreversibly binds water. However, a disadvantage is that such a medium absorbs not only liquid water but also water vapor. If the medium is placed in the housing, it also dehumidifies the gas space within the housing. This results in water vapor being drawn into the housing, which would normally not enter the housing at all. Consequently, such a desiccant cartridge acts not only as a moisture absorber but also as a moisture extractor.

[0008] A further problem is that, for example, in an accident in a vehicle equipped in this manner, leakage may occur and the temperature control medium may escape from the cooling element. The temperature control medium may then come into direct contact with the battery cells and, through its electrical conductivity, trigger a short circuit, for example.

[0009] A common desiccant is P2O5. While it has a high water absorption capacity, it forms liquid phosphoric acid when absorbing water. This can cause corrosion and pose a risk to electrical applications due to its conductivity. Furthermore, water absorption is irreversible. Other typical desiccants, such as CaCl2, exhibit a similar reaction.

[0010] Therefore, the above-mentioned desiccant is not technically target-oriented. Desiccant is usually loosely enclosed in a bag (desiccant bag) and therefore cannot be securely fixed.

[0011] Other known liquid-absorbing substances, in particular water-absorbing substances, are, for example, superabsorbents. The advantages of superabsorbents are, on the one hand, that they have a very high water absorption capacity, are chemically neutral (also with organic solvents), and can also be reversibly loaded.

[0012] When combined with polar liquid media, superabsorbents can cause severe swelling and possibly gel formation. In particular, the swelling can lead to the liquid's transport channels being blocked by the swelling process (the so-called blocking effect), and subsequent absorption is no longer possible. Furthermore, swelling in electronic devices can be unfavorable or harmful from two other perspectives: On the one hand, the swelling material can generate mechanical stress, which can, for example, disconnect electrical contacts. On the other hand, uncontrolled swelling can cause electrical short circuits when the swelling material comes into contact with current-carrying components.

[0013] If the superabsorbent is in bulk form, potential dust formation is problematic in the dry state, and in the swollen state it is also difficult to remove, as the swollen superabsorbent particles are mechanically unstable. This can lead to problems during maintenance and / or repairs.

[0014] Superabsorbent materials are known, for example, from medical products and are described, for example, in DE 10 2006 031 418 A1.

[0015] EP2731164 (A1) describes a battery system comprising battery cells, at least one absorption element, and a temperature control system having a liquid temperature control medium for cooling and / or heating the battery cells in a battery housing. The absorption element for absorbing the liquid temperature control medium is arranged between the battery cells and the battery housing, wherein the absorption element is a nonwoven fabric having a density of 250 to 700 g / m 2 The invention relates to a method for preparing an absorbent fiber having an average area-related mass of at least two different fiber types, wherein at least one of the fiber types is a support fiber and at least another of the fiber types is an absorbent fiber.

[0016] The disadvantage of using absorbent fibers is that their absorption capacity is generally lower than that of comparable absorbent particles. In addition, they generally have lower thermal stability in the dry and swollen state. In addition, as mentioned above, the use of absorbent fibers can lead to a gel blocking effect. Summary of the Invention

[0017] The object of the present invention is to at least partially alleviate the aforementioned disadvantages. In particular, a material with good water absorption and retention properties should be provided. This material should also be able to reversibly bind water and, if applicable, water vapor. Furthermore, it should have controlled swelling properties and avoid blocking effects. Finally, it should be capable of being used in a low-dust manner.

[0018] This object is achieved by using a composite material for receiving and distributing liquids in actively and / or passively cooled current-carrying systems, in particular in actively and / or passively cooled energy storage systems, the composite material comprising a carrier layer and a liquid-receiving layer fixed to the carrier layer, wherein the liquid-receiving layer contains fixed superabsorbent particles, wherein a liquid distribution layer is arranged on the side of the liquid-receiving layer facing away from the carrier layer, in liquid-conducting contact with the liquid-receiving layer, and which absorbs and distributes the liquid to be received in the plane of the composite material.

[0019] According to the present invention, it has been found that the composite material described above is well suited for absorbing and distributing liquids in actively and / or passively cooled fluid-carrying systems, as the fixed superabsorbent particles significantly reduce the risk of dust formation. The superabsorbent particles are preferably fixed to the carrier layer, for example, by means of an adhesive. This is particularly advantageous under mechanical stresses, such as those encountered when the composite material is used in automobiles. Furthermore, the fixing allows the use of superabsorbents in particulate form. Compared to superabsorbent fibers, this has the advantage of a higher absorption capacity in both the dry and swollen states and comparable thermal stability. Furthermore, it has surprisingly been found that fixed superabsorbent particles absorb water vapor faster and release it more completely than loose superabsorbent particles. Furthermore, the composite material exhibits a very low gel-blocking effect, as the liquid distribution layer used absorbs and distributes the liquid to be received within the plane of the composite material. This allows for optimal utilization of the absorption capacity of the liquid-receiving layer.

[0020] According to the invention, the composite material is suitable for various actively and / or passively cooled current-carrying systems, such as battery systems, inverter / power electronics systems, and / or charging stations. Various liquids, such as water and / or other cooling media, such as a water-glycol mixture, can be absorbed.

[0021] Preferred current-carrying systems according to the invention are current-carrying systems selected from the group consisting of energy storage systems, current-carrying energy converters, transformers, power electronics systems, control electronics systems, in particular processor-controlled systems, charging stations, inverters, rectifiers, electrolyzers and / or combinations thereof.

[0022] According to the invention, preferred energy storage systems are battery systems, capacitors and / or accumulators. Very particular preference is given to battery systems.

[0023] Superabsorbents are characterized by their excellent ability to bind and absorb liquids. According to the invention, superabsorbents are understood to mean polymers that are able to suck up or absorb multiples (up to 500 times) of their own weight in liquids, preferably water, with an increase in volume.

[0024] Superabsorbents form hydrogels in the swollen state. Suitable superabsorbents are, in particular, polar, crosslinked polymers. Particularly preferred are polyacrylamide, polyvinylpyrrolidone, pullulan, gelatin, and cellulose. Very particularly preferred are copolymers of acrylic acid (propionic acid, H2C═CH—COOH) and / or sodium acrylate (sodium acrylate, H2C═CH—COONa) on the one hand, and acrylamide on the other. In this case, the ratio between the two monomers can vary.

[0025] So-called core cross-linkers (CXLs) are usually added to the above-mentioned monomers, which locally connect (crosslink) the long-chain polymer molecules formed via chemical bridges. These bridges make the polymer insoluble in water. In addition, so-called surface cross-linkers (SXLs) can be used. In this case, another chemical is applied to the surface of the particles, which, upon heating, forms a second network only on the outer layer of the particles. This outer shell supports the swollen gel and holds it together even under external stress (movement, pressure).

[0026] In a preferred embodiment of the present invention, the superabsorbent particles are fixed to the carrier layer using an adhesive, in particular a water-soluble adhesive, such as polyvinyl alcohol, starch, polyvinyl pyrrolidone, casein glue, polyvinyl butyral and / or a water-swellable adhesive, such as at least partially cross-linked polyvinyl alcohol and / or at least partially cross-linked starch. A water-soluble adhesive is understood to be an adhesive having a water solubility of at least 1 g / L, for example 1 g / L to 400 g / L, more preferably 2 g / L to 350 g / L, in particular 5 g / L to 300 g / L, measured at 23°C. The use of a water-soluble adhesive and / or a water-swellable adhesive has the advantage that the free swelling capacity of the superabsorbent is not restricted.

[0027] Preferably, the proportion of the water-soluble binder and / or water-swellable binder is at least 70 weight percent, for example 70 weight percent to 100 weight percent, more preferably 80 weight percent to 100 weight percent, in particular 90 weight percent to 100 weight percent, based on the total amount of binder.

[0028] In another preferred embodiment, the superabsorbent particles contain a swelling retarder. This advantageously delays the swelling of the superabsorbent particles, thereby optimizing the distribution of the liquid to be absorbed and making particularly good use of the absorption surface of the liquid-receiving layer. The swelling retarder can consist of the same material as the water-soluble and / or swellable adhesive. Preferably, the superabsorbent particles are at least partially, preferably completely, coated with the swelling retarder.

[0029] The liquid distribution layer absorbs the liquid to be received and distributes it in the plane of the composite material.

[0030] In another preferred embodiment, the liquid distribution layer comprises a nonwoven, a woven fabric, a knitted fabric, an open-cell foam and / or an adhesive, preferably a water-soluble and / or water-swellable adhesive. Preferred water-soluble adhesives are polyvinyl alcohol, starch, polyvinyl pyrrolidone, casein glue, polyvinyl butyral. Preferred water-swellable adhesives are, for example, at least partially cross-linked polyvinyl alcohol and / or partially cross-linked starch. The advantages of these materials are their good water permeability and high structural integrity, even when wet. Preferred nonwovens are spunbond nonwovens, wet-laid nonwovens and / or dry-laid nonwovens. The basis weight is preferably 10 g / m 2 Up to 500g / m 2 .

[0031] In another preferred embodiment, the surface energy of the liquid distribution layer is greater than 30 mN / m, preferably greater than 35 mN / m, particularly preferably greater than 40 mN / m, measured according to DIN 55660. Advantageously, polar media such as water or water / glycol mixtures can be distributed particularly well.

[0032] In another preferred embodiment, the liquid distribution layer comprises at least two distribution layers, at least one of which is water-soluble and at least one of which is water-insoluble. The water-soluble distribution layer can be composed of the same material as the water-soluble and / or swellable binder for the superabsorbent particles. The water-insoluble distribution layer preferably comprises a thermoplastic polymer, in particular having a melting point below 260°C. Particularly preferred polymers are polyesters, copolyesters, polyamides, copolyamides, polyolefins, and / or blends thereof. Advantageously, these polymers can be used for thermal welding.

[0033] In another preferred embodiment, the air permeability of the liquid distribution layer is greater than 10 dm 3 / (m 2 s), preferably 20 to 3000 dm 3 / (m 2 s), still more preferably in the range of 30 to 2000 dm 3 / (m 2 s), particularly preferably in the range of 30 to 1000 dm 3 / (m 2 s). Here, the air permeability is measured at a pressure difference of 100 Pa according to DIN EN ISO 9237. Before contact with the liquid, a sample with a thickness of 0.05 to 10 mm, preferably 3 mm, and an air flow area of 20 cm is passed through the sample at a pressure difference of 100 Pa. 2 The air permeability of the samples was measured.

[0034] In a preferred embodiment of the present invention, the distribution layer, in particular the water-insoluble water distribution layer, has an average pore size greater than 1 μm, such as 1 μm to 1000 μm, preferably 10 μm to 800 μm.

[0035] In another preferred embodiment of the invention, the distribution layer comprises microfibers, preferably having a fineness of less than 1 dtex, for example 0.01 to 1 dtex, more preferably 0.01 to 0.9 dtex. Advantageously, the microfibers enable particularly high capillarity and thus particularly good distribution of the liquid in the distribution layer.

[0036] In another preferred embodiment of the present invention, the composite material has a 2 Liquid absorption capacity (deionized water), for example 2L / m 2 Up to 200L / m 2 , still more preferably 3 L / m 2 Up to 200L / m 2 , still more preferably 5 L / m 2 Up to 200L / m 2 , even more preferably 10 L / m 2 Up to 200L / m 2 , especially 20L / m 2 Up to 200L / m 2 .

[0037] The carrier layer preferably comprises a thermoplastic polymer, in particular a thermoplastic polymer having a melting point below 270° C. Particularly preferred polymers are polyesters, copolyesters, polyamides, copolyamides, polyolefins and / or blends thereof. Advantageously, these can be used for thermal welding.

[0038] Preferably, the carrier layer comprises a nonwoven, a woven fabric, a knitted fabric and / or an open-cell foam. Preferred nonwovens are spunbond nonwovens, wet-laid nonwovens and / or dry-laid nonwovens. The basis weight is preferably 10 g / m 2 Up to 500g / m 2 .

[0039] In another preferred embodiment, the composite material is compressible and can thus be well fixed in actively and / or passively cooled current-carrying systems, in particular in actively and / or passively cooled energy storage systems. Furthermore, good contact with adjacent components can be ensured.

[0040] In another preferred embodiment of the present invention, the composite material comprises a water-insoluble liquid distribution layer comprising a thermoplastic polymer and a carrier layer also comprising a thermoplastic polymer. Advantageously, the water-insoluble liquid distribution layer and the carrier layer can be welded together particularly well. Therefore, the carrier layer and the liquid distribution layer are preferably welded together and / or can be welded together. Advantageously, the liquid-receiving layer can be limited in its height expansion during liquid absorption.

[0041] Surprisingly, it has been found that the composite material according to the invention has good sound absorption properties. Therefore, in another embodiment of the present invention, the composite material has an absorption coefficient, measured in accordance with EN ISO 354:2003 at a frequency of 6300 Hz, of greater than 0.09, more preferably greater than 0.2 and particularly preferably greater than 0.25, and / or greater than 0.1, more preferably greater than 0.25 and particularly preferably greater than 0.3 at a frequency of 8000 Hz. This is surprising, as it would be assumed that a coating with superabsorbent particles would result in a composite material with low air permeability and, associated therewith, a low absorption coefficient.

[0042] The composite material can be present in a water-permeable bag welded at the edges. It is also possible to arrange multiple composite materials in a bag.

[0043] The composite material can be arranged in the bag in various ways. If the composite material is in the form of absorbent pads, they can be stacked on top of each other in the bag. If the composite material is in the form of a web, the web can be folded and / or rolled like an accordion and flattened in the bag.

[0044] In another embodiment, at least one composite material is present as an absorbent pad. An absorbent pad is understood to mean a composite material that has been cut and welded at the edges. This prevents swelling of the superabsorbent particles. Another subject matter of the present invention includes an absorbent pad comprising a composite material according to one or more of the described embodiments.

[0045] Another preferred absorbent pad is a composite material that is cut and joined at the edges with seams.

[0046] The absorbent pad may have a variety of symmetrical and / or asymmetrical geometries.

[0047] The absorbent pad may comprise a composite material heat-welded at the edges, comprising a water-insoluble distribution layer and a carrier layer, wherein the water-insoluble distribution layer and the carrier layer are heat-fused at the edges with partial penetration of the liquid-receiving layer, whereby all layers are thermally connected to one another at the edges.

[0048] In another embodiment, an absorbent pad comprises two composite materials, as described above, each comprising a carrier layer and a liquid-receiving layer fixed to the carrier layer, wherein the liquid-receiving layer contains fixed superabsorbent particles, and wherein a liquid distribution layer is arranged on the side of the liquid-receiving layer facing away from the carrier layer, in liquid-conducting contact with the liquid-receiving layer, said liquid distribution layer absorbing and distributing the liquid to be received in the plane of the composite material. In this embodiment, the first distribution layer associated with the first composite material comprises a water-soluble distribution layer and a water-insoluble distribution layer, and the second distribution layer associated with the second composite material comprises a water-soluble distribution layer. The two composite materials are arranged such that the liquid-receiving layers face each other. The absorbent pad is circumferentially heat welded at the edges, wherein at least one of the water-insoluble distribution layers is at least partially melted, thereby partially penetrating the liquid-receiving layer, thereby securing the absorbent pad. Preferably, in this embodiment, at least one of the carrier layers is also at least partially melted, thereby securing the absorbent pad.

[0049] In another embodiment, the absorbent pad comprises two composite materials, as described above, each comprising a carrier layer and a liquid-receiving layer fixed to the carrier layer, wherein the liquid-receiving layer contains fixed superabsorbent particles, and wherein a liquid distribution layer is arranged on the side of the liquid-receiving layer facing away from the carrier layer, in liquid-conducting contact with the liquid-receiving layer, said liquid distribution layer absorbing and distributing the liquid to be received in the plane of the composite material. The two composite materials are arranged such that the liquid-receiving layers face each other. The absorbent pad is circumferentially heat welded at the edges, wherein at least one of the carrier layers is at least partially melted, thereby partially penetrating the liquid-receiving layer, thereby securing the absorbent pad. Preferably, in this embodiment, at least one of the water-insoluble distribution layers is also at least partially melted, thereby securing the absorbent pad.

[0050] In another embodiment, an absorbent pad comprises two composite materials, as described above, each comprising a carrier layer and a liquid-receiving layer fixed thereto, wherein the liquid-receiving layer contains fixed superabsorbent particles, and wherein a liquid distribution layer is arranged on the side of the liquid-receiving layer facing away from the carrier layer, in liquid-conducting contact with the liquid-receiving layer, said liquid distribution layer absorbing and distributing the liquid to be received within the plane of the composite material. In this embodiment, the first distribution layer associated with the first composite material comprises a water-soluble distribution layer and a water-insoluble distribution layer, and the second distribution layer associated with the second composite material comprises a water-soluble distribution layer. The two composite materials are arranged such that the liquid-receiving layers face each other. A thermoplastic adhesive, preferably a (co)polyester, (co)polyamide, polyurethane, and / or polyolefin, is arranged between the liquid-receiving layers, the liquid-receiving layer being in the form of a two-dimensional sheet material, such as a nonwoven, film, woven fabric, and / or knitted fabric. The absorbent pad is circumferentially heat-welded at the edges, wherein the thermoplastic adhesive at least partially melts, thereby partially penetrating the liquid-receiving layers and thereby securing the absorbent pad. Preferably, in this embodiment, at least one carrier layer is also at least partially melted, thereby fixing the absorbent pad.

[0051] It is also conceivable that the absorbent pad comprises a composite material comprising a meltable, water-insoluble distribution layer and a meltable carrier layer, wherein the liquid distribution layer and the carrier layer protrude beyond the liquid receiving layer and are welded to each other including the liquid receiving layer.

[0052] In another embodiment of the invention, the absorbent pad has an absorption coefficient of greater than 0.09, more preferably greater than 0.2 and particularly preferably greater than 0.25, and / or greater than 0.1, more preferably greater than 0.25 and particularly preferably greater than 0.3, measured at a frequency of 6300 Hz in accordance with EN ISO 354:2003. The absorbent pad preferably comprises at least two composite materials, since, in practical tests, particularly good acoustic properties can be achieved with multi-layer products.

[0053] In another embodiment, the absorbent pad comprises 2 to 8 composite materials, preferably 3 to 8, in particular 3 to 7, arranged such that the outer layer is formed by the carrier layer. The absorbent pad can be at least partially circumferentially heat-welded at the edges. Welding achieves at least partial melting of the carrier layer, thereby partially penetrating the liquid-receiving layer and thereby thermally connecting all layers to one another.

[0054] A further embodiment comprises an absorbent pad in which at least one carrier layer and at least one liquid distribution layer and / or at least two carrier layers are at least partially connected to one another at the edges by at least one seam.

[0055] Another embodiment comprises an absorbent pad wherein at least one composite material is present in a moisture permeable bag that is at least partially closed at its edges by at least one seam.

[0056] The at least one seam can be formed as a fin seam or an overlapping seam.If the bag is closed by a plurality of seams, these seams can be configured independently of each other as fin seams or overlapping seams.

[0057] The shape of the bag can vary. Conventional packaging designs have proven suitable. For example, a bag can be obtained by circumferentially connecting two bag layers with a seam. This typically results in one to four seams, preferably four. Alternatively, the bag can be obtained by folding the bag layers into a tube and connecting them at the open edges with a seam. This typically results in three seams.

[0058] In a preferred embodiment, the at least one seam is implemented as a weld seam, in particular as a heat-welded and / or ultrasonically welded seam, an adhesive seam and / or a needle-punched seam. The advantage of a weld seam is that it can be realized particularly quickly and easily.

[0059] The at least one seam can be continuous and / or discontinuous. A discontinuous seam is composed of a combination of direct seam areas, i.e., those areas of the seam that serve to bond the two layers and / or close the bag, and indirect seam areas, i.e., those areas of the seam that lie between the direct seam areas. In the case of a welded seam, the direct seam area is the welded area; in the case of a sewn seam, the area covered by the thread; and in the case of an adhesive seam, the area connected by the adhesive. Discontinuous seams have the advantage of having a lower proportion of seam area and, therefore, providing a higher strength relative to the area.

[0060] A continuous seam has the advantage of reducing the risk of superabsorbent particles leaking. Furthermore, the at least one seam can be designed as a straight or curved line, or a combination thereof. In a discontinuous design, the at least one seam can be designed as a line and / or regularly arranged dots and / or dashed lines. As described above, those portions of the seam that serve to bond the layer and / or seal the permeable bag constitute the direct seam area of the seam. The width of the at least one seam is preferably 0.5 to 15 mm, more preferably 0.5 to 10 mm, and particularly preferably 1 to 6 mm. More preferably, the seam area, i.e., the sum of the indirect and direct seam areas on the surface of the absorbent material, is at least 0.4 to 50 area percent, more preferably 2 to 40 area percent, and particularly preferably 4 to 35 area percent. If the seam area is less than 0.4 area percent, the seam strength is generally too low.

[0061] In a particular embodiment, the at least one joint is designed as a weld seam, which is preferably perforated in its center. This advantageously allows the absorbent material to be adapted to the installation situation in a particularly simple manner. Thus, for example, a cutout can be formed by selectively separating a subregion along the perforated weld seam.

[0062] The shape of the weld seam can vary. In a preferred embodiment, the transition between the weld seam and the unwelded area of the layer is smooth. Therefore, in a preferred embodiment, the thickness of the welded area of the weld seam decreases toward the edge. Accordingly, the density of the welded area of the weld seam increases toward the edge. The transition between the weld seam and the pocket is preferably continuous. Advantageously, this results in a higher weld seam strength.

[0063] Another subject matter of the present invention is an actively and / or passively cooled fluid-carrying system comprising a composite material, preferably in the form of an absorbent pad, comprising a carrier layer and a liquid-receiving layer fixed to the carrier layer, the liquid-receiving layer containing superabsorbent particles, wherein a liquid distribution layer is arranged on the side of the liquid-receiving layer facing away from the carrier layer and is in liquid-conducting contact with the liquid-receiving layer, the liquid distribution layer absorbing and distributing the liquid to be received in the plane of the composite material. BRIEF DESCRIPTION OF THE DRAWINGS

[0064] Figure 1 : Water vapor absorption of the absorbent pad according to the present invention

[0065] Figure 2 : Water vapor absorption of absorbent pads not according to the invention

[0066] Figure 3 : Sound absorption properties of the absorbent pad according to the present invention

[0067] Figure 4 : Schematic diagram of the cross section of seam 5

[0068] Figure 1 The water vapor absorption of an absorbent pad according to the present invention is shown. The results show that the water vapor absorption is very rapid. After 30 minutes, the water vapor absorption has reached equilibrium. It is also noteworthy that the re-drying also proceeds very quickly and is almost complete.

[0069] Figure 2 The water vapor absorption of an absorbent pad not according to the invention is shown. The results show that the water vapor absorption is significantly slower. Water vapor absorption reaches equilibrium after 90 minutes at the earliest. Furthermore, redrying is not complete even after 20 hours.

[0070] Figure 3 The sound absorption characteristics of a plurality of absorbent pads according to the present invention are shown. It can be seen that all absorbent pads according to the present invention have good absorption coefficients.

[0071] Figure 4 A cross-section of a joint is shown. The joint is in the form of a weld. The weld thickness decreases toward the edge. Correspondingly, the weld density increases toward the edge. This transition is continuous. DETAILED DESCRIPTION

[0072] The present invention is described in detail below through several examples:

[0073] Example 1: Preparation of a composite material that can be used according to the invention

[0074] Various composite materials and absorbent pads were prepared that could be used in accordance with the present invention.

[0075] The following materials were used:

[0076] Microfiber spunbond nonwoven fabric: Microfiber spunbond nonwoven fabric polyamide / polyester 200g / m 2 .

[0077] Superabsorbent particles 1: partially neutralized and cross-linked polyacrylic acid, prepared by mass polymerization, particle size distribution d50 50 μm-1000 μm, coating weight 15 g / m 2 .

[0078] Superabsorbent particles 2: partially neutralized and cross-linked polyacrylic acid, prepared by inverse suspension polymerization, with a particle size distribution d50 of 50 μm-1000 μm and a coating weight of 15 g / m 2 .

[0079] Water-soluble distribution layer 1: water-soluble partially saponified polyvinyl alcohol, coating weight 20g / m 2

[0080] Water-soluble distribution layer 2: water-soluble starch, coating weight is 20g / m 2

[0081] The following table shows the layer structure used

[0082]

[0083] The layers are connected as follows:

[0084] First, the carrier layer is pre-placed and coated with the water-soluble distribution layer and superabsorbent particles. Subsequently, if used, the water-insoluble distribution layer is added.

[0085] Composite materials 1 to 5 were arranged on two heat-weldable layers (bag layer, microfiber spunbond nonwoven fabric 80g / m 2) between which the edges are circumferentially protruded beyond the composite material and the edges of these layers are welded to form an absorbent pad. The cutting step can be performed before or after welding.

[0086] In another embodiment, a plurality (2-5) of composite materials 1-5 are welded and an absorbent pad is obtained.

[0087] In another embodiment, the composite materials 1 - 5 are circumferentially heat-welded at the edges, wherein the water-insoluble distribution layer and the carrier layer melt and thereby partially penetrate the liquid-receiving layer, and thereby all layers are thermally connected to one another.

[0088] In another embodiment, two composite materials 5 are arranged so that the liquid-receiving layers face each other. The resulting composite is circumferentially heat-welded at the edges, with the carrier layer melting, partially penetrating the liquid-receiving layer and thereby thermally connecting all layers to one another. The cutting step can be performed before or after welding. This results in an absorbent pad 6a.

[0089] In another embodiment, the four composite materials 5 are arranged so that the carrier layer forms the outer layer. The resulting composite is circumferentially heat-welded at the edges, with the carrier layer melting and thus partially penetrating the liquid-receiving layer, thereby thermally connecting all layers to one another. The cutting step can be performed before or after welding. This results in an absorbent pad 6b.

[0090] In another embodiment, the six composite materials 5 are arranged so that the carrier layer forms the outer layer. The resulting composite is circumferentially heat-welded at the edges, with the carrier layer melting and thus partially penetrating the liquid-receiving layer, thereby thermally connecting all layers to one another. The cutting step can be performed before or after welding. This results in an absorbent pad 6c.

[0091] In another embodiment, two composite materials 5 are arranged so that the liquid receiving layers face each other. A bonding nonwoven fabric (copolyester nonwoven fabric, 30 g / m 2 , Smp. 100-110° C.). The composite thus obtained is circumferentially heat-welded at the edges, wherein the adhesive nonwoven melts and thereby partially penetrates the liquid-receiving layer, and thus all layers are thermally connected to one another. This results in an absorbent pad 7.

[0092] Example 2: Testing the Absorption Capacity of the Absorbent Pad According to the Invention

[0093] The absorption capacity of the absorbent pad 7 was tested with completely desalinated water according to DIN 53923. The absorbent pad 7 was found to have a good water absorption of 8.7 kg / m 2 In the test according to DIN 53923, the absorbent pad 7 is suspended in a swollen state and floats freely for 30 seconds. The water loss here is 550 g / m 2, resulting in excellent retention. The pad can also be easily dried without heating, demonstrating its ability to reversibly bind water. By being circumferentially welded, swelling is well controlled, and blocking effects are avoided through the use of a distribution layer. By securing the superabsorbent particles, dust formation is prevented.

[0094] Example 3: Testing of water vapor absorption of absorbent pads according to the present invention

[0095] The absorbent pad 7 was tested for water vapor absorption. To this end, the absorbent pad was stored in a climate chamber at 90% humidity and 30° C. for a period of 270 minutes. The weight gain was determined gravimetrically every 30 minutes over the 270-minute period. The absorbent pad 7 was then dried at room temperature and the weight loss was determined gravimetrically. This process was repeated 5 times and the weight loss was determined gravimetrically. Figure 1 Shown in.

[0096] The results show that water vapor absorption is very rapid. After 30 minutes, water vapor absorption has reached equilibrium. In this regard, it is worth noting that the re-drying also proceeds very quickly and is almost complete.

[0097] Example 4: Testing of water vapor absorption of absorbent pads not according to the invention

[0098] An absorbent pad not according to the invention was tested for water vapor absorption. The absorbent pad consisted of a nonwoven bag filled with 1 g of loose superabsorbent particles 2. The weight gain was measured gravimetrically every 30 minutes over a period of 270 minutes. The absorbent pad not according to the invention was then dried at room temperature for 20 hours, and the weight loss was measured gravimetrically. This process was repeated 5 times and the weight loss was measured gravimetrically. Figure 2 Shown in.

[0099] The results showed that water vapor absorption was significantly slower. Water vapor absorption reached equilibrium after 90 minutes at the earliest. Moreover, redrying was not complete even after 20 hours.

[0100] Example 5: Testing the sound absorption properties of the absorbent pad according to the present invention

[0101] The sound absorption properties of three different absorbent pads 6a, 6b, and 6c were determined according to EN ISO 354:2003. Figure 3 It can be seen that all the absorbent pads according to the present invention have a good absorption coefficient.

Claims

1. A composite material for receiving and distributing liquid in an active and / or passively cooled fluid-carrying system, the composite material comprising a carrier layer and a liquid-receiving layer fixed to the carrier layer, wherein: The liquid-receiving layer contains fixed superabsorbent particles, wherein a liquid distribution layer is arranged on the side of the liquid-receiving layer facing away from the carrier layer and is in liquid-conducting contact with the liquid-receiving layer, the liquid distribution layer receives and distributes the liquid to be received in the plane of the composite material, and the superabsorbent particles are fixed to the carrier layer by a water-soluble adhesive and / or a water-swellable adhesive, and the liquid distribution layer includes at least two distribution layers, wherein at least one distribution layer is water-soluble and at least another distribution layer is not water-soluble.

2. The use according to claim 1, in an actively and / or passively cooled electricity storage system. 3 . The method according to claim 1 , wherein the method is in an actively and / or passively cooled battery system, inverter system, power electronics system and / or charging station.

4. The method according to claim 1, wherein the method is in a fluid-carrying system which is actively and / or passively cooled with a water-glycol mixture.

5. The use according to claim 4 in an electrical storage system with active and / or passive cooling of a water-glycol mixture.

6. The use according to any one of claims 1 to 3, characterized in that The water-soluble adhesive is polyvinyl alcohol, starch, polyvinyl pyrrolidone, casein glue or polyvinyl butyral.

7. The use according to any one of claims 1 to 3, characterized in that The water-swellable binder is at least partially cross-linked polyvinyl alcohol and / or partially cross-linked starch.

8. The use according to any one of claims 1 to 3, characterized in that The superabsorbent particles comprise a swelling retardant.

9. The use according to any one of claims 1 to 3, characterized in that The superabsorbent particles comprise a swelling retarder consisting of the same material as the water-soluble and / or swellable binder.

10. The use according to any one of claims 1 to 3, characterized in that The liquid distribution layer comprises a nonwoven fabric, a woven fabric, a knitted fabric and / or an open-cell foam.

11. The use according to any one of claims 1 to 3, characterized in that The surface energy of the liquid distribution layer, measured according to DIN 55660, is at least greater than 30 mN / m.

12. The use according to claim 11, characterized in that The surface energy of the liquid distribution layer, measured according to DIN 55660, is greater than 35 mN / m.

13. The use according to claim 11, characterized in that The surface energy of the liquid distribution layer, measured according to DIN 55660, is greater than 40 mN / m.

14. The use according to any one of claims 1 to 3, characterized in that The water-soluble distribution layer consists of the same material as the water-soluble and / or swellable binder.

15. The use according to any one of claims 1 to 3, characterized in that The carrier layer comprises a thermoplastic polymer.

16. The use according to claim 15, characterized in that The carrier layer comprises a thermoplastic polymer having a melting point below 270 °C.

17. The use according to any one of claims 1 to 3, characterized in that The carrier layer and the liquid distribution layer are welded to each other.

18. The use according to any one of claims 1 to 3, characterized in that The carrier layer and the liquid distribution layer can be welded to one another.

19. An absorbent pad comprising a composite material cut and welded at the edges, the composite material comprising a carrier layer and a liquid receiving layer fixed to the carrier layer, wherein: The liquid-receiving layer contains fixed superabsorbent particles, wherein a liquid distribution layer is arranged on the side of the liquid-receiving layer facing away from the carrier layer and is in liquid-conducting contact with the liquid-receiving layer, the liquid distribution layer receives and distributes the liquid to be received in the plane of the composite material, and the superabsorbent particles are fixed to the carrier layer with a water-soluble adhesive and / or a water-swellable adhesive, and the liquid distribution layer includes at least two distribution layers, wherein at least one distribution layer is water-soluble and at least another distribution layer is not water-soluble.

20. The absorbent pad according to claim 19, wherein The absorbent pad comprises a composite material heat-welded at the edges, the composite material comprising a water-insoluble distribution layer and a carrier layer, wherein the water-insoluble distribution layer and the carrier layer are heat-fused at the edges with partial penetration of the liquid-receiving layer, whereby all layers are thermally connected to one another at the edges.

21. The absorbent pad according to claim 19 or 20, wherein The absorbent pad comprises two composite materials, wherein a first distribution layer associated with the first composite material comprises a water-soluble distribution layer and a water-insoluble distribution layer, and a second distribution layer associated with the second composite material comprises a water-soluble distribution layer, wherein the two composite materials are arranged such that the liquid-accepting layers face each other, wherein the absorbent pad is circumferentially heat welded at the edges, wherein at least one water-insoluble distribution layer is at least partially melted thereby partially penetrating the liquid-accepting layer, thereby securing the absorbent pad.

22. The absorbent pad according to claim 19 or 20, wherein The absorbent pad comprises two composite materials having a water-soluble distribution layer, wherein the two composite materials are arranged such that the liquid-receiving layers face each other, wherein a thermoplastic adhesive is arranged between the liquid-receiving layers, wherein the absorbent pad is circumferentially heat welded at the edges, wherein the thermoplastic adhesive at least partially melts and thereby partially penetrates the liquid-receiving layers, thereby securing the absorbent pad.

23. The absorbent pad of claim 22, wherein the thermoplastic adhesive is a polyester, a polyamide, a polyurethane and / or a polyolefin.

24. The absorbent pad of claim 23, wherein the polyester is a copolyester.

25. The absorbent pad of claim 23, wherein the polyamide is a copolyamide.

26. The absorbent pad of claim 22, wherein the thermoplastic adhesive is in the form of a two-dimensional sheet material.

27. The absorbent pad of claim 26, wherein the thermoplastic adhesive is in the form of a nonwoven fabric, a film, a woven fabric and / or a knitted fabric.

28. An actively and / or passively cooled fluid-carrying system comprising a composite material comprising a carrier layer and a liquid-receiving layer fixed to the carrier layer, wherein: The liquid-receiving layer contains fixed superabsorbent particles, wherein a liquid distribution layer is arranged on the side of the liquid-receiving layer facing away from the carrier layer and is in liquid-conducting contact with the liquid-receiving layer, the liquid distribution layer receives and distributes the liquid to be received in the plane of the composite material, and the superabsorbent particles are fixed to the carrier layer by a water-soluble adhesive and / or a water-swellable adhesive, and the liquid distribution layer includes at least two distribution layers, wherein at least one distribution layer is water-soluble and at least another distribution layer is not water-soluble.

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