Patent Application
20200340152
The present invention relates to a spacer fabric. More particularly this invention concerns a composite spacer fabric having several layers.
A spacer textile typically has an outer flat warp-knitted fabric layer, an inner flat warp-knitted fabric layer and spacer yarns interconnecting the warp-knitted fabric layers, the outer warp-knitted fabric layer having openings each formed by a plurality of stitches, the inner warp-knitted fabric layer having at least a first and a second yarn system, the yarns of the first yarn system running in a production direction on exactly one respective stitch wale and the yarns of the second yarn system extend over at least two adjacent stitch wales running in the production direction. The spacer fabric is provided in particular as an elastic layer in vehicle seats or in interior linings.
The assignment of the production direction and transverse direction is customary for warp-knitted fabrics, the production direction also being referred to as the knitting direction or the longitudinal direction. In the spacer fabric, the individual yarns forming the warp-knitted fabric run along the production or knitting direction and, based on this, have a usually recurring knitting pattern, according to which for example the spacer yarns run back and forth between the two warp-knitted fabric layers, possibly also with an offset in the transverse direction.
According to the usual definition of terms, the two flat warp-knitted fabric layers have stitch wales running in the production direction and stitch courses running in the transverse direction.
Spacer fabrics are characterized by a light, air-permeable structure, spacer fabrics being elastic in the direction of their thickness due to the spacer yarns running between the two warp-knitted fabric layers. For this purpose, monofilament yarns are usually provided as spacer yarns that due to their structure have a comparatively high restoring effect.
Due to their elastic properties, spacer fabrics can be provided as soft, elastic and air-permeable layers in mattresses, upholstered furniture, clothing, or shoes. Spacer fabrics are also used as technical fabrics in the automotive sector, for example for climate seats and seat covers, with spacer fabrics allowing a good contour adjustment due to their cushioning properties and very good resilience.
In addition, spacer fabrics in the automotive sector are also particularly suitable for upholstery in other applications, such as in furniture construction. Spacer fabrics are used in the automotive sector for interior lining, whereby composite materials with a spacer fabric and a laminated fabric layer, for example leather, synthetic leather, or a decorative film, can be used for lining the headlining, the dashboards, the center consoles, and the inside of the door.
A composite material or a composite arrangement having a spacer fabric and a decorative cover layer is usually connected to an underlying either rigid or flexible basic structure. For example, the composite arrangement for the interior lining or in furniture construction can be applied to a rigid substructure or also when a seat or a seat surface is formed on a flexible substructure.
Both with a rigid and a flexible substructure, there is the advantage that curves, angles or other three-dimensional shapes can be compensated to a certain extent in front of the spacer fabric, and in many cases excessive deformation and in particular kinking of the decorative cover layer can be prevented. In addition, a particularly pleasant, soft feel results for a user due to the flexibility of the spacer fabric, but a predetermined shape, at least after elastic restoring, is also maintained due to the elastic restoring forces of the spacer fabric.
Although spacer fabrics are in some cases far superior to other elastic materials in terms of these properties, there is a need to further improve the mechanical properties of the spacer fabric, particularly in the case of products that are of complex or sophisticated design and in the case of particularly long-lasting products.
U.S. Pat. No. 8,286,451 discloses a spacer fabric and a composite arrangement formed therefrom having the spacer fabric and a decorative cover layer, the composite arrangement providing reduced tear resistance at a plurality of areas for the arrangement above an airbag or an airbag flap.
For this purpose, the two flat warp-knitted fabric layers of the spacer fabric are each formed from a basic yarn system and a further yarn system, a first part of the stitch courses being formed at least by the basic yarn system, a second part of the stitch courses being formed by the second yarn system, the yarn(s) of the basic yarn system extending in the second part of the course without forming stitches and the warp-knitted fabric layers on the second part of the stitch courses having a lower tensile strength in the production direction than on the first part of the stitch courses. By omitting stitches, weak lines running in the transverse direction are formed, with corresponding weak lines being one above the other or with a slight offset in the two warp-knitted fabric layers, so that the two warp-knitted fabric layers are identical with regards to their functionality. Correspondingly, the two warp-knitted fabric layers also have the same mechanical properties, at least comparable, not only in terms of their tensile strength but also in terms of their flex strength and stretchability.
A spacer fabric is known from US 2018/0187348 where the two warp-knitted fabric layers of the spacer fabric differ fundamentally in terms of their structure and mechanical properties. In the composite arrangement with the spacer fabric, the different mechanical properties are used in a particularly advantageous manner. While one of the two warp-knitted fabric layers is quite stretchy in the production direction and transverse direction, the opposite warp-knitted fabric layer is much less stretchy in the production direction (knitting direction) and transverse direction. The warp-knitted fabric layer with the low stretchability is provided against the decorative cover layer, so that the stretchable warp-knitted fabric layer is then spaced from the decorative cover layer by the spacer yarns.
With regard to deforming the spacer fabric known from US 2018/0187348 or a composite material formed therewith, the behavior is completely different from that of a uniform layer material. While the neutral axis is usually in the middle of the thickness with a uniform layer material such as a thick plastic film or cut foam with a bend, with the spacer fabric according to US 2018/0187348, the neutral axis is located, in the case of a bend, namely where there is no substantial stretch or strain, on the warp-knitted fabric layer having the low stretchability that is located immediately under the decorative cover layer. Due to the properties of the spacer fabric and in particular the immediately adjacent warp-knitted fabric layer having low stretch, the decorative cover layer is optimally protected against kinking, twisting, or the like. With a uniform concave or convex bend, the opposite stretchable warp-knitted fabric layer can be lengthened or shortened accordingly, which also contributes to optimal protection of the decorative cover layer.
The composite arrangement known from US 2018/0187348 is distinguished by excellent properties when large uniformly curved or arched surfaces are to be provided or padded.
With regard to alternative spatial arrangements, however, the composite arrangement is still in need of improvement.
Against this background, the present invention has for its object the provision of a spacer fabric having good mechanical properties and good air permeability and that allows an expanded range of uses.
A composite spacer fabric has an outer flat warp-knitted fabric layer having openings each formed by a respective plurality of stitches and an inner flat warp-knitted fabric layer also having openings that are each formed by a respective plurality of stitches. The second warp-knitted fabric layer further having at least a first and a second yarn system. The yarns of the first yarn system run in a production direction on exactly one respective stitch wale and the yarns of the second yarn system extend over at least two adjacent stitch wales that run in the production direction. Spacer yarns interconnect the warp-knitted fabric layers.
Thus according to the invention, the less stretchable warp-knitted fabric layer that is referred to here as the inner warp-knitted fabric layer has openings formed by a plurality of stitches. In the scope of such an embodiment, the two warp-knitted fabric layers then have corresponding openings that, however, are formed differently. With the inner warp-knitted fabric layer, care must be taken to ensure that the openings do not provide too much stretchability.
According to the invention, the two warp-knitted fabric layers each have openings formed by a plurality of stitches. Every textile structure is not completely tight, so that there are always certain openings between the individual yarns. The feature that the warp-knitted fabric layers have openings that are each formed by a plurality of stitches does not refer to this customary textile structure but to a special embodiment of the corresponding warp-knitted fabric layer or both warp-knitted fabric layers, so that openings are formed there that are larger than one stitch or the space between two simple stitches.
Corresponding openings are achieved in practice by filet knitting (i.e. a miss-lapping or net structure), for which purpose typically two guide bars are used that are not fully occupied. Corresponding knitting or net patterns are shown for example in the specialist book Marcus Oliver Weber/Klaus-Peter Weber “Wirkerei and Strickerei, Technologien-Bindungen-Produktionsbeispiele,” 6th Edition 2014, deutscher Fachbuchverlag, pages 188 and 189.
Appropriate openings can be used to achieve particularly good air or fluid transport in the thickness direction in particular. Corresponding openings are only known according to US 2018/0187348 for the (i.e. a miss-lapping or net structure), knitted fabric layer having the greater stretchability.
According to this prior art, this embodiment is also based on the knowledge that, in the case of conventional knitting patterns, an improvement in the stretchability can be achieved solely on the basis of the lattice-like or net-like structure.
Despite this knowledge, the invention provides that both warp-knitted layers each have openings formed by a plurality of stitches. In the inner, less stretchable warp-knitted fabric layer within the scope of the invention, however, a knitting pattern is then to be provided that, despite the formation of corresponding openings, has only a comparatively low stretchability, i.e. the openings do not contribute to a substantial increase in the stretchability.
In the scope of the invention, the fact that the inner warp-knitted fabric layer has a first yarn system makes a substantial contribution to this, the yarns of the first yarn system running in the production direction at exactly one respective stitch wale, whereby a high tension in the production direction is then achieved by these yarns of the first yarn system.
As also known from US 2018/0187348, the first yarns of the first yarn system in the production direction can alternately form pillar stitches or be guided without forming stitches. For example, for two stitch courses, on the one hand the formation of pillar stitches and on the other hand the threading without forming stitches can be provided. If the yarns are passed without forming stitches, however, they can be guided around the corresponding needles in the knitting process, so that in practice this is also referred to as an one-needle inlay (“Schuss unter 1”).
In order to form openings described in the inner slightly stretchable warp-knitted fabric layer, the second yarn system can be formed as a filet pattern (i.e. a miss-lapping or net-like structure) having a first partial yarn system and a complementary second partial yarn system. In the scope of the invention, the partial yarn systems typically formed with a respective guide bar are referred to collectively as a second yarn system due to the fact that the knitting pattern is the same but inverted. According to a filet pattern that is conventional per se, it can be provided that the two partial yarn systems are formed by two guide bars each with a feed 1 full, 1 empty or 2 full, 2 empty. Fundamentally, further knitting patterns are also known that can also be considered within the scope of the invention. Each opening can extend for example over two stitch courses.
And despite the formation of the openings to achieve the least possible stretch in the production and transverse directions, provided according to a particularly preferred embodiment of the invention on the one hand the yarns of the second yarn system alternately form pillar stitches in the production direction and on the other hand form stitches formed from the group of tricot, cord, satin, velvet, and atlas. The stitches selected from the group of tricot, cord, satin, velvet, and satin connect the individual stitch wales in the transverse direction so that there is less stretchability in the transverse direction. However, if the yarns of the second yarn system, that is to say the first partial yarn system and the complementary second partial yarn system, also form pillar stitches, the tensile strength in the production direction is further increased and the stretchability is also reduced.
Even if the inner warp-knitted fabric layer has openings formed by a plurality of stitches, these openings are expediently smaller than the openings of the outer warp-knitted fabric layer. The yarns of the second yarn system can alternately form n>1 pillar stitches and, on the other hand m>1 stitches selected from the group of tricot, cord, satin, velvet, and atlas in the production direction. In the simplest case, two stitches of the type described are provided in succession in the production direction, but the invention is not restricted to such an embodiment.
In the scope of the invention, the spacer fabric can have for example between 10 and 35, in particular between 18 and 28, stitch courses per centimeter in the production direction.
In the transverse direction, between 4 and 13, preferably between 6 and 10, stitch wales are usually provided per centimeter.
With a preferred full occupancy of a respective guide bar with spacer yarns, the result is a pole stick density per square centimeter between 144 to 728, preferably between 200 and 560. The number of stitch courses and stitch wales is to be determined in accordance with DIN EN 14971.
The weight per unit area can typically be between 200 g/m2 and 750 g/m2, preferably between 350 g/m2 and 600 g/m2.
According to the invention and in contrast to the prior art according to US 2018/0187348, the outer flat warp-knitted fabric layer facing the decorative cover layer has greater stretchability in the production and transverse directions than the inner warp-knitted fabric layer. The different stretchability can be easily determined if the spacer fabric is angled under tension. It can then be determined by hand which of the two warp-knitted fabric layers is easier to stretch.
The greater stretchability of the outer warp-knitted fabric layer relates to a normal tension at which the material is not destroyed.
Within the scope of the invention, the stretchability or the stretch in the production direction and transverse direction can also be quantified in accordance with DIN EN ISO 13934-1:2013-08. The standard “textiles, tensile properties formed by textile surfaces, part 1” is also used if the stretch properties of the entire spacer fabric are to be determined in accordance with the prior art. On the one hand however, it has to be taken into account that the stretch behavior should be determined for the two flat warp-knitted fabric layers, it not being necessary to determine a maximum tension.
Rather, for a comparison of the two warp-knitted fabric layers within the scope of the invention, the stretch is determined and compared at a predetermined tension of for example 25 N (Newtons). According to the specified standard, strips of the spacer fabric with a width of 50 mm can be formed for this purpose. An initial length can then be determined in the longitudinal direction of these strips, with which a clamping between the test jaws of a stretching device is subsequently provided. The spacer yarns can then be severed in order to ultimately be able to test the outer flat warp-knitted fabric layer and the inner flat warp-knitted fabric layer separately from one another with regard to their stretch properties.
According to a preferred embodiment of the invention, taking into account the test described in the production direction and the transverse direction, the stretch determined in accordance with DIN EN ISO 13934-1 at a tension of 25N is at least twice as large for the outer flat warp-knitted fabric layer as for the inner flat warp-knitted fabric, so that there is then a ratio of at least 2:1. The ratio can readily be for example 3:1, 5:1, or 7:1. Ratios of 10:1 or larger can also readily be achieved.
It can be provided that the stretch determined according to DIN EN ISO 13934-1 at a tension of 25 N is between 25% and 60%, in particular between 30% and 48%, in the outer flat warp-knitted fabric layer in the production direction and the transverse direction.
On the other hand the stretch determined according to DIN EN ISO 13934-1 with a tension of 25 N for the inner flat warp-knitted fabric layer is only between 1.5% and 10%, in particular between 2% and 7%, in the production direction and the transverse direction.
In order to achieve a particularly low stretch regardless of the specific knitting pattern for the inner warp-knitted fabric layer, it is provided according to a preferred development of the invention that the inner warp-knitted layer has multifilament smooth yarn and/or monofilament yarn or is formed therefrom. The corresponding yarns then have only a comparatively low stretch along their longitudinal direction, in particular if they are formed from conventional thermoplastic such as polyester, polyamide, or polyolefin such as polyethylene or polypropylene.
In order to achieve good stretchability with regard to the outer warp-knitted fabric layer, on the other hand it is preferably provided that the outer warp-knitted fabric layer has or is formed from textured multifilament yarn. When texturing, the multifilament yarns are deformed and angled to a certain extent along their longitudinal direction, so that the yarns are shortened without tensile stress. When a tensile stress is applied, the individual textured multifilament yarns can then be pulled straight again to a certain extent, so that good stretch properties and, to a limited extent, elastic restoring properties in the longitudinal direction of the textured multifilament yarn result with the usual and also preferred use of non-elastic thermoplastics.
Multifilament yarns with a fineness between typically 49 dtex and 190 dtex are suitable for both the outer warp-knitted fabric layer and the inner warp-knitted fabric layer. Multifilament yarns can have for example 24 yarns, but other yarn configurations, including multifilament yarns based on microfibers, can also be considered.
The spacer yarns are usually formed from monofilament yarn, and the fineness can be selected in particular as a function of the desired compression hardness.
The warp-knitted spacer fabric according to the invention can be used in a very versatile manner within the scope of the invention, the use in motor vehicles being particularly preferred.
As described above, there are properties that partially correspond to the properties of the spacer fabric from US 2018/0187348, the greatly improved air permeability in the thickness direction being made possible by the openings formed by a plurality of stitches in each of the two warp-knitted fabric layers. Particularly when such an air passage in the thickness direction is provided in the area of a seat or also an interior lining of a motor vehicle, there are particular advantages.
In this context, it should be noted that the spacer fabric according to the invention can also be used very flexibly for different composite arrangements or differently shaped composite arrangements. Inner of all, the spacer fabric is very well suited, in accordance with DE 10 2016 126 881, to provide curvatures and/or arches on interior linings or comparable composite arrangements without an overlay made of for example leather, synthetic leather, or textile carried by the spacer fabric, being excessively deformed or kinked. Since such large arches or curves are to be provided, the spacer fabric with the inner, only slightly stretchable warp-knitted fabric layer adjoins a corresponding decorative cover layer. It is also particularly advantageous if the spacer fabric is only slightly stretchable in the inner warp-knitted fabric layer according to a development of the invention, but also has a relatively low flex strength.
The low flex strength of the inner warp-knitted fabric layer can be made possible by the first knitting pattern and the second knitting pattern of the first yarn system or the second yarn system. If, according to the first knitting pattern, the individual yarns in a modified pillar pattern run along only one stitch wale, the individual stitch wales can be slightly angled in the transverse direction, but at the same time the second yarn system in the transverse direction avoids excessive stretch or contraction. A low flex strength with regard to the direction of production (knitting direction) is achieved in that pillar stitches are omitted at regular intervals in the first yarn system, so that the yarns extend there over a predetermined length without forming stitches.
With regard to the bending of the spacer fabric or of a composite material formed with the spacer fabric, the behavior described with regard to the described embodiment is completely different from that of a uniform layer material. While the neutral axis is usually in the middle of the thickness with a uniform layer material such as a thick plastic film with a bend, with the spacer fabric according to the invention the neutral axis is located in the case of a bend, namely where there are no substantial stretches and strains, on the inner warp-knitted fabric layer. Based on this, the stretches and constraints required for angling or bending are made available at the outer warp-knitted fabric layer.
According to the composite arrangement described above, the inner warp-knitted fabric layer is at a decorative cover layer and preferably abuts it directly. Due to the low stretchability of the inner warp-knitted fabric layer, the decorative cover layer can be protected against unwanted kinking in the case of large arches. Furthermore, it is also known in the automotive sector to shape the seat surfaces and backrests of a vehicle seat or other lining parts three-dimensionally by means of decorative seams, in which case good deformability and also great stretchability are expedient below the corresponding decorative cover layer. Surprisingly, the warp-knitted spacer fabric according to the invention is particularly suitable for such applications if the warp-knitted fabric layer having a greater stretchability faces the decorative cover layer.
Surprisingly, a particularly good, comparatively small-scale, three-dimensional design of the decorative cover layer can then be achieved by compressing the spacer fabric on compressed areas due to the arrangement that is exactly the opposite of the above-described configuration.
The spacer fabric is expediently compressed in the compressed areas by a connection between the decorative cover layer and the inner warp-knitted fabric layer. According to a particularly preferred embodiment of the invention, the decorative cover layer can be sewn to the compressed areas with the spacer fabric by incorporating the inner warp-knitted fabric layer. The decorative cover layer is pulled at the seams with at least partial compression of the spacer fabric in the direction of the inner warp-knitted fabric layer, so that a recess is formed there starting from an initially flat structure. The spacer fabric is then not or at least less compressed between adjacent compressed areas, so that there are raised portions with respect to the decorative cover layer compared to the compressed areas.
The composite arrangement can thus be provided with a particularly appealing structuring.
The structuring can also help for example to improve the ventilation of an occupant when used on a vehicle seat. Inner of all, a certain air transport along the compressed areas can be achieved through the three-dimensional structuring. However, the composite arrangement can particularly preferably also be combined with active ventilation of an air-conditioning seat.
By sewing or by other connections, the compressed areas can form a pattern selected from the group of rib patterns, rectangular patterns, diamond patterns, and triangle patterns. Depending on the specific shaping, triangle patterns are also referred to as diamond patterns. The specified patterns are only examples, although of course arches, circles or irregular patterns and angles are also possible. Of course, different patterns can also be combined with one another in regions or can merge into one another.
If, for example in the case of a rib pattern, adjacent compressed areas and in particular seams do not intersect, the spacing between the adjacent compressed areas or respectively the center of the adjacent compressed areas can typically be between 15 mm and 100 mm, in particular between 20 mm and 70 mm.
In the compressed areas, for example on seams, the spacer fabric is at least partially compressed. The spacer fabric is usually compressed to less than 70% and in particular less than 50% of the thickness of the spacer fabric in the uncompressed state. The spacer fabric is particularly preferably completely or almost completely compressed, so that then only the thickness of the two warp-knitted fabric layers with the compressed spacer yarns remains therebetween. The spacer fabric is then compressed, that is to say pressed together, for example in the compressed areas, to less than 40% or to less than 20% of the thickness in the uncompressed state.
Even if the spacer fabric and the decorative cover layer are connected to each other at the compressed areas, for example by yarns, that is to say in particular are sewn, an integral connection can also be provided, in particular by means of adhesive, between the decorative cover layer and the outer warp-knitted fabric layer. Such bonding serves for additional fixation and can also facilitate the production process.
As already explained above, the decorative cover layer can preferably be formed from leather or synthetic leather. Depending on the application, other materials such as a decorative film or a textile can also be considered.
The thickness of the spacer fabric is, as described above, usually between 2 mm and 20 mm, these details naturally refer to the uncompressed state. The thickness of the spacer fabric also roughly specifies how strongly the decorative cover layer can be provided with a three-dimensional pattern by compressing the spacer fabric.
As already explained above, the composite arrangement can be provided both for vehicle seats or interior lining or form a seat cover or interior lining. If for example the composite arrangement is provided for a vehicle seat, the outer warp-knitted fabric layer is usually followed by a pressure-elastic substructure, for example a further spacer fabric with a greater thickness. It is known for example that spacer fabrics can be used to achieve fluid distribution in a vehicle seat. A corresponding substructure, for example a further spacer fabric, can then also be used to achieve an air distribution in the surface, in which case this additional spacer fabric is not impaired by the compressed areas and thus air distribution is not impeded. The above-described spacer fabric with the decorative cover layer adjoining the outer warp-knitted fabric layer is then substantially intended for air to pass through in the thickness direction, an open structure with openings in both warp-knitted fabric layers being particularly advantageous here.
If the composite arrangement is provided for example for a vehicle seat or forms the seat cover or seat surface of a vehicle seat, the pressure-elastic substructure can also have a ventilation device in a particularly advantageous manner or can be connected to a ventilation device.
In principle, however, other areas of a motor vehicle, surfaces of a piece of furniture, seat surfaces of a chair, or the like can also be equipped with the composite arrangement according to the invention. In such a case, the inner warp-knitted fabric layer is then connected for example to a substrate, in particular a dimensionally stable substrate.
The seams can be straight and parallel to each other. Alternatively, the ribs can also be bordered or formed by seams that are not exactly straight and for example are wavy or zigzag.
If, on the other hand individual areas are separated by the compressed areas, these areas can typically have a size between 3 cm2 and 100 cm2, in particular between 8 cm2 and 50 cm2. Here, too, the area information relates to the center of each compressed area that can be formed for example by a seam. The specified areas of the individual portions relate in particular to a rectangular pattern, a diamond pattern, or a triangular pattern.
The particularly good shapability of the spacer fabric can be attributed to various aspects. Inner of all, the outer flat warp-knitted fabric layer facing the decorative cover layer can be deformed particularly easily due to the good stretchability thereof. If, therefore, the spacer fabric is compressed there during the generation of the compressed areas, there is practically no force distribution along the plane of the outer warp-knitted fabric layer due to the good stretchability. The decorative cover layer can therefore be pressed in very well on the outer flat warp-knitted fabric layer.
The outer flat warp-knitted fabric layer lying opposite with respect to the spacer fabric of the decorative cover layer has a lower and preferably significantly lower stretchability. The tension exerted on the compressed areas in particular by a seam on the outer warp-knitted fabric layer can be distributed over a larger area due to the low stretchability.
The outer flat warp-knitted fabric layer and also the decorative cover layer thereon run in an arcuate cross-section between two adjacent compressed areas. As a result of the restoring forces at the compressed areas, tension is exerted on the inner warp-knitted fabric layer that acts in the plane of the inner warp-knitted fabric layer. However, since the inner warp-knitted fabric layer is less and in particular significantly less stretchable than the outer warp-knitted fabric layer, these tension can be absorbed. With regard to the composite arrangement, the decorative cover layer that runs in an arcuate cross-section between two adjacent compressed areas can thus be held or stretched out.
In particular, thanks to the inner less stretchable warp-knitted fabric layer, the spacer fabric alone is sufficient to keep the elastically supported decorative cover layer in the desired three-dimensional shape. An additional high-tensile layer of textile or the like is therefore not necessary, which is particularly advantageous in terms of the simplest possible structure and in terms of good breath ability.
With regard to the composite arrangement according to the invention, the formation of corresponding openings in both warp-knitted fabric layers is advantageous, but not mandatory. For example, the spacer fabric also known from US 2018/0187348 is basically suitable to form the composite arrangement according to the invention. In contrast to the composite material known from this prior art, the spacer fabric is then to be oriented exactly oppositely, so that, according to the invention, the warp-knitted fabric layer with the greater stretchability that is referred to in the scope of the invention as the outer warp-knitted fabric layer, faces the decorative cover layer and preferably directly adjoins the decorative cover layer.
With regard to the spacer fabric, which is known per se, a variant of the composite arrangement according to the invention provides that the inner warp-knitted fabric layer is formed from at least a first yarn system with a first knitting pattern and a second yarn system with a second knitting pattern, wherein as the first knitting pattern a modified pillar pattern is provided, in which the yarns of the first yarn system form pillar stitches in an alternating sequence in the knitting direction and are guided without forming stitches, and the yarns of the second yarn system each extend over at least two adjacent stitch wales in the production direction.
With regard to the further embodiment options of such a spacer fabric, reference is expressly made to the disclosure content of US 2018/0187348.
The above and other objects, features, and advantages will become more readily apparent from the following description, reference being made to the accompanying drawing in which:
The spacer fabric 1 has an outer flat warp-knitted fabric layer 2, an inner flat warp-knitted fabric layer 3 and spacer threads 4 interconnecting the warp-knitted fabric layers 2, 3. In the case of the two flat warp-knitted fabric layers 2, 3, stitch wales extends along in the production direction P and stitch courses in the transverse direction Q. In the warp-knitting process, the stitches of a stitch course are formed at the same time with respective guide bars, the individual yarns running in the production direction P with their respective knitting pattern, that is to say possibly with an offset between the individual stitch wales.
The spacer threads 4 connect the two warp-knitted fabric layers 2, 3 and are responsible for pressure-elastic restoring properties of the spacer fabric 1 when compressed in the direction of the thickness. Monofilament yarn is preferably provided for the spacer threads 4 in order to obtain good elastic properties. The compression hardness can be determined by the yarn material, the density of the spacer threads 4 and their thickness.
According to
In order to achieve a particularly high-quality design of the composite, the spacer fabric 1 has compressed areas 7 where the spacer fabric 1 is permanently at least partially compressed for structuring the decorative cover layer 5. In the compressed areas 7, the decorative cover layer 5 is sewn to the spacer fabric 1 with the incorporation of the inner warp-knitted fabric layer 3, each with a decorative yarn 8, so that connections 9 between the decorative cover layer 5 and the inner warp-knitted fabric layer 3 are formed by the decorative yarns 8.
From
In the embodiment according to
In the following, further possible patterns of the compressed areas are presented, with the most varied types of patterns and composites also being considered, of course. In particular, a seat surface can be designed by combining different patterns or pattern portions according to the technical requirements and aesthetic requirements.
According to
This behavior is achieved in the scope of the invention in that the outer warp-knitted fabric layer 2 facing the decorative cover layer 5 has greater stretchability in the production direction P and in the transverse direction Q than the inner warp-knitted fabric layer 3. If, therefore, the decorative cover layer 5 is pulled at the connections 9 formed by the decorative yarns 8 at the compressed areas 7 in the direction of the inner warp-knitted fabric layer 3, the outer warp-knitted fabric layer 2 can easily deform and in particular stretch there, whereas, due to the higher strength or lower stretchability of the inner warp-knitted fabric layer 3, there is less deformation.
The restoring forces generated by the spacer threads 4 straighten the decorative cover layer 5 between the compressed areas 7, thereby also creating a tensile load on the inner warp-knitted fabric layer 3 in the plane. Due to the low stretchability of the inner warp-knitted fabric layer 3, these tension can be absorbed. Due to the different stretching properties and in particular the low stretchability of the inner warp-knitted fabric layer 3, the decorative cover layer 5 can be “stretched open” to a certain extent by the restoring forces of the entire spacer fabric 1.
It should be taken into account that in the sense of the invention the term stretchability refers to the stretch at a predetermined tension that causes no damage and preferably also no substantial reversible changes in the spacer fabric 1 and in particular in the two warp-knitted fabric layers 2, 3.
The stretchability for the production direction P and the transverse direction Q can be determined for example in accordance with DIN EN ISO 13934-1 at a tension of 25 N. For such a test, strips with a width of 50 mm can be cut from the spacer fabric, the initial length then being marked on the spacer fabric 1, with which the clamping is subsequently provided in a corresponding test device. In order then to be able to test the two flat warp-knitted fabric layers 2, 3 individually, the spacer threads 4 can be cut by an incision made parallel to the warp-knitted fabric layers 2, 3. The influence of the remaining remnants of the spacer threads 4 in the two flat warp-knitted fabric layers 2, 3 is neglected and actually only plays a subordinate role for the stretchability. The patterns thus formed, that is to say strips running in the production direction P or transverse direction Q depending on the test, are then subjected to a tension of 25 N, the increase in length then being determined in percent. Usually, a significantly greater stretch of the outer flat warp-knitted fabric layer 2 compared to the inner flat warp-knitted fabric layer 3 is observed according to the invention. The ratio is at least 2:1, but can readily be 3:1, 5:1, 7:1, or even 10:1 and more.
For example, for the production direction P and the transverse direction Q, the stretch determined in the manner described for a tension of 25 N in the outer flat warp-knitted fabric layer 2 can be between 25% and 60%. Such good stretchability ensures that the outer warp-knitted fabric layer 2 can be easily pressed in at the connections 9. In particular, due to the good stretchability, there is practically no substantial force distribution along the outer warp-knitted fabric layer 2.
The inner flat warp-knitted fabric layer 3 has a significantly lower stretch in the production direction P and transverse direction Q with a tension of 25 N and a test according to DIN EN ISO 13934-1. The stretch can be for example between 1.5% and 10%, in particular between 2% and 7%. This slight stretch ensures that the inner warp-knitted fabric layer 3, as shown in
Finally,
The properties of the spacer fabric 1 described above can also be illustrated in
Before the corresponding connections 9 are generated by the decorative yarns 8 on the compressed areas 7, the decorative cover layers 5 and the spacer fabric 1 are substantially flat. If the compressed areas 7 are then generated with a spacing L from one another relative to the respective center, this length L is retained at the inner warp-knitted fabric layer 3, while the outer warp-knitted fabric layer 2 can be extended in an arc shape due to its good stretchability.
The measures for generating the different stretch behavior with regard to the outer warp-knitted fabric layer 2 and the inner warp-knitted fabric layer 3 are explained in more detail below.
Air for cooling and air conditioning a user can then be blown out through the spacer fabric 1 and the perforation 6 of the decorative cover layer 5. In this context in particular, the compressed areas 7 can also be particularly advantageous with regard to user comfort, because the blown-in air can be circulated or discharged through the ribs formed in this way. Against this background, very good air permeability in the thickness direction is also advantageous for the spacer fabric 1.
In order to further improve these properties, relatively low yarn tension can also be used in the knitting process for the outer warp-knitted fabric layer 2.
Furthermore, the outer warp-knitted fabric layer 2 can also be formed from textured multifilament yarn that is not only particularly soft but also elastically stretchable to a certain extent along its longitudinal direction due to the textured structure. This also applies in particular when the outer warp-knitted fabric layer 2 and preferably the entire spacer fabric 1 is formed from an inelastic thermoplastic polymer such as a polyester, polyamide, or polyolefin.
To form the inner warp-knitted fabric layer 3, a second yarn system 15 with a first partial yarn system 15a and a complementary second partial yarn system 15b is further provided. Since the two partial yarn systems 15a, 15b per se have a matching but complementary knitting pattern and together form the filet pattern, in the scope of the invention these are collectively referred to as the second yarn system 15, even if for each partial yarn system 15a, 15b in the knitting process a guide bar is provided. The two partial yarn systems 15a, 15b can be formed for example with two guide bars, each with a feed 1 full, 1 empty.
According to
The sequence of two pillar stitches 14′ and two stitches 16 of a cord pattern is only by way of example, it also being possible to provide a larger number with regard to the two stitch types. The cord pattern is also only shown by way of example. In addition, stitches selected from the group of tricot, satin, velvet, and atlas can also be considered.
In order to achieve the lowest possible overall stretch, the inner warp-knitted fabric layer 3 with the first yarn system 13 and the second yarn system 15 is made entirely of multifilament smooth yarn.
The thickness of the spacer fabric 1 is typically between 2 mm and 20 mm, in particular between 3 mm and 15 mm.
Whereas, according to
According to
In contrast to
According to
To illustrate the special advantages of the spacer fabric 1 according to the invention, a composite is only described by way of example in the embodiment that has compressed areas 7, the comparatively stretchable outer warp-knitted fabric layer 2 adjoining the decorative cover layer 5, while the inner warp-knitted fabric layer 3 having only a comparatively low stretchability can then stretch open the decorative cover layer 5 that is elastically supported by the spacer yarns.
If, on the other hand comparatively large, uniformly curved surfaces are to be provided in a composite arrangement, the spacer fabric 1 according to the invention can be provided in exactly the reverse arrangement of the warp-knitted fabric layers 2, 3, the inner warp-knitted fabric layer 3 then supporting the decorative cover layer 5 having less stretchability. With regard to possible embodiments, reference is made to the embodiments 3 of DE 10 2016 125 881, wherein a ventilation function advantageously can be provided by the embodiment according to the invention in the thickness direction, that is to say through the decorative cover layer 5, due to the inventive configuration of the spacer fabric 1, even in the case of corresponding embodiments of a composite arrangement. For this purpose, the decorative cover layer 5 can for example also be provided with openings in the manner of the perforation 6 described above.
| Number | Date | Country | Kind |
|---|---|---|---|
| 102019110909.4 | Apr 2019 | DE | national |
