Abstract:
The present invention is directed to a freight container comprising a floor, a roof (D), and a plurality of walls comprising at least a front end wall and side walls (A). These walls (A) and roof (D) each comprise at least one panel having two surface dimensions in relation to the container. The panels comprise a fibre-reinforced wall material, comprising a first and a second outer fibre layer ( 1, 6, 7,12 ), and at least a first and a second intermediate fibre layer ( 2, 3, 4, 5, 8, 9, 10, 11 ) arranged in between the first and second outer fibre layers. The fibres of the outer fibre layers are aligned along an outer fibre direction and the fibres of the intermediate fibre layers are aligned respectively along a first and second intermediate fibre direction which are mutually transverse and inclined with respect to the outer fibre direction. The outer fibre direction is aligned with a shortest of said surface dimensions of said panels.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention is directed to a freight container comprising a floor, a roof and a plurality of walls that form, in use, a door wall, a front end wall and a plurality of side walls and optionally side end walls that extend in between the roof and the floor of the container, said container defining a length direction of the container extending parallel with the floor and the side walls, said container defining a height direction of the container extending parallel with the corner posts. 
       BACKGROUND 
       [0002]    To enable efficient supply chain systems to be implemented, freight containers are preferably of a standard size, such as freight containers conforming to the ISO standards for containers. An ISO (International Standards Organization) container is a freight or shipping container that complies with one or more relevant ISO container standards, such as the ISO 1496 series. 
         [0003]    Types of freight containers may vary according to their application, but include nominal 20 and 40 foot ISO containers and 10, 25, 30, 45, 48 and 53 foot containers and SWAP bodies for conveyance of goods by road, rail and/or sea. The containers of the present invention include general purpose, thermal (e.g. insulated, refrigerated, heated) or bulk containers as described in the ISO 1496 series, but also include non ISO containers and SWAP bodies. 
         [0004]    The ISO container standards provide minimum structural properties relating to the strength of the walls, roof and floor. Rigidity and weatherproofing standards are also set. The standards ensure that the containers are suitable for purpose as freight, shipping or cargo containers. Freight containers must be able to withstand extremely high forces, such as for example resulting from stacking or from ship movement, under all kind of weathering conditions. For example, a fully loaded freight container must be apple to support a mass of containers (also referred to as stacking) without permanent deformation or abnormality which will render the container unsuitable for use and without sacrificing the dimensional requirements affecting handling, securing and interchange. 
         [0005]    Posts are vertical frame components which are integral with the floor structure and castings (fittings) which provide means for lifting, handling, stacking and securing the container. Corner posts are posts located at the corners of freight containers. A front corner post is a corner post at the front end of the freight container, i.e. opposite the door end. A rear corner post is a corner post at the door end of the freight container. 
         [0006]    Heretofore, freight or shipping containers generally have used a metal framework with steel or aluminum sheathed panels attached to the framework by bolts, rivets or welding. The problem with using such freight containers is that they are very heavy. The heavier weight of these containers limits the maximum cargo weight, or payload, that can be transported in such a container due to limitation on maximum allowed gross weight by local regulations. 
         [0007]    Freight containers comprising fibre reinforced composite materials, such as for example described in U.S. Pat. No. 7,059,488, could result in lower weight. This lighter weight will increase the amount of cargo that can be carried in the freight container. Composite material structures have also been shown to be more resistant to corrosion, making the containers more suitable for use in marine and other hostile environments. 
         [0008]    There is thus a desire to reduce the weight, however the requirements to withstand the tremendous loads routinely placed on a freight container cannot be compromised. 
       SUMMARY OF THE INVENTION 
       [0009]    It is therefore an object of the present invention to provide an improved freight container that at least partly meets a problem mentioned above. 
         [0010]    The above mentioned objects of the invention are achieved in that there is provided a freight container comprising a floor, a roof and a plurality of walls, said walls extending in between the roof and the floor of the container and comprising at least a front end wall, and a plurality of side walls, wherein said floor, said roof, and said walls each comprise at least one panel, each panel having two surface dimensions in relation to the container, wherein the panels comprise a fibre-reinforced wall material comprising a first outer fibre layer and a second outer fibre layer, and at least a first intermediate fibre layer and a second intermediate fibre layer that are arranged in between the first and second outer fibre layers, wherein fibres of the first and second outer fibre layers are aligned along an outer fibre direction, and fibres of the first intermediate fibre layer and fibres of the second intermediate fibre layer are aligned respectively along a first intermediate fibre direction and a second intermediate fibre direction that are mutually transverse and are inclined with respect to the outer fibre direction, and wherein the outer fibre direction is aligned with a shortest of said surface dimensions of said panels. 
         [0011]    It has surprisingly been found that with the freight container of the present invention the weight reduction of walls can be maximized and at the same time the compressive strength of the fibre reinforced wall material and the flexural strength and/or flexural modulus of the fibre reinforced wall material can be maximized. Increasing the compressive strength and the flexural strength and/or flexural modulus of the fibre reinforced wall material results in an improved stiffness of a panel comprising the fibre reinforced wall material as claimed. When applying another stacking sequence of the fibre layers and using the same amount of fibre layers, the compressive strength and the flexural strength and/or flexural modulus of the fibre reinforced wall material will be reduced. The compressive strength and the flexural strength and/or flexural modulus for such another stacking sequence can be increased by applying a much higher amount of fibres, but this will result in an increase of the weight of the side wall an/or the roof and thus of the freight container. 
         [0012]    In accordance with an embodiment of the invention, for a panel of at least said front end wall, the fibre-reinforced wall material further comprises multidirectional reinforcement layers, the multidirectional reinforcement layers comprising at least a first and second support fibre layer comprising fibres aligned along a support fibre direction, said first support fibre layer being present contiguous to said first outer layer, and said second support fibre layer being present contiguous to said second outer layer, and wherein said support fibre direction is transverse to said outer fibre direction. 
         [0013]    As will thus be appreciated from the above, the multidirectional reinforcement layers of the panel of the front end wall may be present on either side of the outer layers, i.e. as an additional reinforcement in the support fibre direction transverse to the outer fibre direction. 
         [0014]    Weight reduction on one hand and strength and structural integrity on the other hand are the main design drivers for the container of the present invention. The inventors advantageously found that without compromising the integrity of the freight container with respect to handling, loading, racking, and lifting thereof in use, the requirements for the composite wall panels may be released with respect to the side walls and roof of the containers, whereas this is not the case for the frond end wall of the container, which is to be designed such as to withstand multidirectional force and stress applied thereto. The side walls and roof primarily require to withstand bending loads and stress—i.e. a sufficiently large flexural strength and flexural modulus, while requirements for other sources of stress (e.g. multidirectional stress, shear stress) may be released. This allows for a container design wherein the fibre-reinforced wall material of the front end wall comprises additional fibre layers: multidirectional reinforcement layers; whereas at the same time such layers are not necessarily present in any of the other walls of the container. The front end wall thus have a structure that is adapted not only to withstand flexural forces, but also multidirectional loads, thereby requiring a quasi-isotropic configuration with respect to its surface (fibres extending in eight directions (four alignments)). As will be appreciated, this design enables to provide an optimum between total weight of the container on one hand, and structural integrity on the other hand. The weight reduction achievable in properly designing the container according to this principle of accurate load analysis for each wall provides an important benefit over conventional composite containers. 
         [0015]    In accordance with an embodiment of the invention, the walls of the container further comprise one or more side end walls or roof end parts located adjacent and parallel to said side walls and roof respectively, at a far or tail end of said container, wherein each of said side end walls or roof end parts comprises at least one panel comprising said fibre-reinforced wall material, and wherein for panels of at least said side end walls or roof end parts the fibre-reinforced wall material comprises shear stress reinforcement layers, said shear stress reinforcement layers comprising at least a third and a fourth intermediate fibre layer arranged in between the first and second outer fibre layers, wherein fibres of the third intermediate fibre layer are aligned with the fibres of the first intermediate fibre layer and the second intermediate fibre layer is arranged in between the first and third intermediate fibre layers; and wherein fibres of the fourth intermediate fibre layer are aligned with the fibres of the second intermediate fibre layer and the first intermediate fibre layer is arranged in between the second and fourth intermediate fibre layers. 
         [0016]    Side end walls and/or roof end parts are not present in every type of freight container, but only in the longer ones (e.g. &gt;40 ft). In line with the invention, it has also been found that requirements for the one or more panels forming the side end walls and/or the roof end parts should be more stringent with respect to absorbing shear loads, while the requirements may be released with respect to multi-directional loads. It has been found that, contrary to the side walls, the prime requirement in terms of integrity for the side end walls is that these walls must be able to withstand shear stress experienced during lifting and racking of the containers. This is in addition to the flexural strength requirements that apply to the whole of the side wall and the side end wall (and basically all of the walls of the container). 
         [0017]    By realising that it is only the front end walls, and where applicable the side end walls or roof end parts, that require these strict requirements with respect to forces such as shear stress (side end walls roof end parts) and multidirectional stress (front end wall), the weight of the container as a whole can be reduced considerably. This is an important improvement in the field of composite containers, as it will be appreciated by the skilled person that the total weight of a freight container is a main cost driver in the transportation industry. Moreover, the more weight reduction, the least energy there is required for handling, lifting or moving the container from A to B. Therefore, the light weight container of the invention also provides environmental advantages. 
         [0000]    Roof and/or Side Wall of the Freight Container 
         [0018]    Preferably, at least part of the roof and/or the side walls of the container comprises the fibre-reinforced wall material, wherein, in the roof and the side walls, the outer fibre direction is directed transverse to the length direction of the container. As used herein, this means that the angle between the outer fibre direction and the length direction is 90±5°, preferably 90±3° and more preferably 90±1° and even more preferably 90°. The intermediate fibre directions are inclined with respect to the outer fibre direction. As used herein, this means that the angle between the intermediate fiber directions and the length direction is 45±20°, preferably 45±15°, more preferably 45±10°, even more preferably 45±5° and even more preferably 45°. Preferably, the angle between the outer fibre direction and the length direction is 90 ° and/or the angle between the outer fiber direction and the intermediate fiber directions is 45°. More preferably, the angle between the outer fibre direction and the length direction is 90 ° and the angle between the outer fiber direction and the intermediate fiber directions is 45°. This advantageously results in that the rigidity of the freight container is maximized. 
         [0019]    In accordance with some embodiments, at least part of the roof and/or the side walls of the container comprises, a laminate structure comprising an outer and an inner laminate layer formed, at least partly, by the fibre-reinforced wall material and the laminate structure further comprises a core layer arranged in between, and in mechanical contact with, both laminate layers, said core layer in use supporting the laminate layers, wherein, in said roof and side walls, the outer fibre direction is directed transverse to the length direction of the container (for the roof, the outer fibre direction is directed parallel to the width direction) and the inner laminate layer is located at the inner side of the container (where the freight is to be located) and the outer laminate layer is located at the outer side of the container. 
         [0020]    In accordance with some embodiments, the fibre-reinforced wall material of the at least one side wall and/or roof further comprises, at least, a third intermediate fibre layer and a fourth intermediate fibre layer arranged in between the first and second outer fibre layers, wherein fibres of the third intermediate fibre layer are aligned with the fibers of the first intermediate fibre layer and the second intermediate fibre layer is arranged in between the first and third intermediate fibre layers; and wherein fibres of the fourth intermediate fibre layer are aligned with the fibers of the second intermediate fibre layer and the first intermediate fibre layer is arranged in between the second and fourth intermediate fibre layers. 
         [0021]    Optionally, in accordance with some embodiments, the fibre-reinforced wall material of the at least one side wall and/or roof comprises two adjacent multi-axial fibre layers of triaxial 90/+45° resp.−45°/−45° resp.+45° fibre in a symmetrical construction whereby one triaxial layer is mirrored relative to the other, preferably glass fibre. More preferably, the fibre-reinforced wall material comprises two adjacent multi-axial fibre layers of triaxial 90°/+45°/−45° fibre in a symmetrical construction whereby one triaxial layer is mirrored relative to the other, preferably glass fibre. Preferably, the triaxial fibre is stitched. 
         [0022]    Preferably, the total areal weight of the fibres in the outer fibre direction (in g/m2) is approximately equal to or higher than the total areal weight of the fibres in the intermediate fibre directions (in g/m2) as this will result in that the best results in terms of flexural strength and/or flexural modulus can be obtained. 
         [0023]    The container of the present invention can for example be a nominal 10, 20, 25, 30, 40, 45, 48 or 53 foot container. Preferably, the container of the present invention is a nominal 10, 20, 30, 40 or 45 foot container. In case of a nominal 10, 20, 25, 30 or 40 foot container, preferably the entire side walls of the container comprises the fibre-reinforced wall material, wherein the outer fibre direction is directed transverse to the length direction of the container 
         [0024]    In a more preferred embodiment of the invention, at least part of the side walls of the container are formed by a laminate structure comprising two outer laminate layers that are both at least partly, preferably completely, formed by the fibre-reinforced wall material as described above and the laminate structure further comprises a core layer arranged in between, and in mechanical contact with, both outer laminate layers, said core layer in use supporting the outer laminate layers, wherein, in said two side walls, the outer fibre direction is directed transverse to the length direction of the container. In case of a nominal 10, 20, 25, 30 or 40 foot container, preferably the entire side walls of the container are formed by said laminate structure. 
         [0025]    Preferably, at least part of the roof of the container comprises the fibre-reinforced wall material as described above, wherein, in the roof, the outer fibre direction is directed transverse to the length direction of the container (and parallel to the width direction). More preferably, at least part of the roof of the container is formed by a laminate structure comprising two outer laminate layers that are both at least partly, preferably completely, formed by the fibre-reinforced wall material and the laminate structure further comprises a core layer arranged in between, and in mechanical contact with, both outer laminate layers, said core layer in use supporting the outer laminate layers, wherein, in said roof the outer fibre direction is directed transverse to the length direction of the container. In case of a nominal 10, 20, 25, 30 or 40 foot container, preferably the entire roof of the container is formed by said laminate structure. 
         [0000]    Roof End Part and/or Side End Wall of the Freight Container 
         [0026]    Containers containing roof end walls and/or side end walls in particular relates to general purpose, thermal (e.g. insulated, refrigerated, heated) or bulk 45-foot ISO container wherein the intermediate posts are positioned at the 40-foot positions. 45-foot ISO containers are 40-foot ISO containers lengthened at both ends with 2.5 foot. Posts are vertical frame components which are integral with the floor structure and castings (fittings) which provide means for lifting, handling, stacking and securing the container. Corner posts are posts located at the corners of freight containers. A front corner post is a corner post at the front end of the freight container, i.e. opposite the door end. A rear corner post is a corner post at the door end of the freight container. 
         [0027]    Preferably, at least part of the side end walls and/or the roof end part of the container comprises the fibre-reinforced wall material, wherein, in the side end walls, the outer fibre direction is directed transverse to the height direction of the container and wherein, in the roof end part, the outer fibre direction is directed transverse to the width direction of the container (and parallel to the length direction of the container). 
         [0028]    As indicated, since the fibre-reinforced wall material of the side end walls is to be designed to withstand the high shear loads experienced in lifting and racking operations, the fibre-reinforced wall material in the side end walls preferably comprises shear stress reinforcement layers as described above, adding at least two additional intermediate fibre layers (third and fourth intermediate fibre layer) to the fibre-reinforced wall material. Therefore, in accordance with an embodiment, the fibre-reinforced wall material of the at least one side end wall and/or roof end part further comprises, at least, a third intermediate fibre layer and a fourth intermediate fibre layer arranged in between the first and second outer fibre layers, wherein fibres of the third intermediate fibre layer are aligned with the fibers of the first intermediate fibre layer and the second intermediate fibre layer is arranged in between the first and third intermediate fibre layers; and wherein fibres of the fourth intermediate fibre layer are aligned with the fibers of the second intermediate fibre layer and the first intermediate fibre layer is arranged in between the second and fourth intermediate fibre layers. 
         [0029]    Preferably, at least part of the side end walls and/or the roof end part of the container comprises a laminate structure comprising an outer laminate layer and an inner laminate layer, whereby the outer and inner laminate layer are both formed, at least partly, by the fibre-reinforced wall material, and the laminate structure further comprises a core layer arranged in between, and in mechanical contact with, both laminate layers, said core layer in use supporting the laminate layers, wherein, in said side end walls, the outer fibre direction is directed transverse to the height direction of the container, wherein, in said roof end part, the outer fibre direction is directed transverse to the width direction of the container and the inner laminate layer is located at the inner side of the container (where the freight is to be located) and the outer laminate layer is located at the outer side of the container. 
         [0030]    As used herein, this means that for the side end wall, the angle between the outer fibre direction and the height direction is 90±5°, preferably 90±3° and more preferably 90±1° and even more preferably 90°. The intermediate fibre directions are inclined with respect to the outer fibre direction. As used herein, this means that the angle between the intermediate fiber directions and the height direction is 45±20°, preferably 45±15°, more preferably 45±10°, even more preferably 45±5° and even more preferably 45°. Preferably, the angle between the outer fibre direction and the height direction is 90° and/or the angle between the outer fiber direction and the intermediate fiber directions is 45°. More preferably, the angle between the outer fibre direction and the height direction is 90° and the angle between the outer fiber direction and the intermediate fiber directions is 45°. This advantageously results in that the rigidity of the freight container is maximized. For the roof end part, the angle between the outer fibre direction and the width direction is 90±5°, preferably 90±3° and more preferably 90±1° and even more preferably 90°. The intermediate fibre directions are inclined with respect to the outer fibre direction. As used herein, this means that the angle between the intermediate fiber directions and the width direction is 45±20°, preferably 45±15°, more preferably 45±10°, even more preferably 45±5° and even more preferably 45°. Preferably, the angle between the outer fibre direction and the width direction is 90° and/or the angle between the outer fiber direction and the intermediate fiber directions is 45°. More preferably, the angle between the outer fibre direction and the width direction is 90° and the angle between the outer fiber direction and the intermediate fiber directions is 45°. This advantageously results in that the rigidity of the freight container is maximized. 
         [0031]    Preferably, the fibre-reinforced wall material of the roof end part comprises two adjacent multi-axial fibre layers of triaxial 90°/+45° resp.−45°/−45° resp.+45° fibre in a symmetrical construction whereby one triaxial layer is mirrored relative to the other, preferably glass fibre. More preferably, the fibre-reinforced wall material comprises two adjacent multi-axial fibre layers of triaxial 90°/+45°/−45° fibre in a symmetrical construction whereby one triaxial layer is mirrored relative to the other, preferably glass fibre. Preferably, the triaxial fibre is stitched. 
         [0032]    Preferably, the total areal weight of the fibres in the outer fibre direction (in g/m2) is approximately equal to or higher than the total areal weight of the fibres in the intermediate fibre directions (in g/m2) as this will result in that the best results in terms of flexural strength and/or flexural modulus can be obtained. 
         [0033]    The fibre-reinforced wall material of the outer laminate layer of the side end wall preferably further comprises, at least, a fifth intermediate fibre layer and a sixth intermediate fibre layer arranged in between the first and second outer fibre layers, wherein fibres of the fifth intermediate fibre layer are aligned with the fibers of the second intermediate fibre layer and the second intermediate fibre layer is arranged in between the sixth and third intermediate fibre layers; and wherein fibres of the sixth intermediate fibre layer are aligned with the fibers of the first intermediate fibre layer and the first intermediate fibre layer is arranged in between the fourth and fifth intermediate fibre layers. Preferably, the fibre-reinforced wall material of the inner laminate layer of the side end wall(s) comprises two adjacent multi-axial fibre layers of triaxial 90°/+45° resp.−45°/−45° resp.+45° fibre in a symmetrical construction whereby one triaxial layer is mirrored relative to the other, whereby the 90° direction is transverse to the height direction. Preferably, the fibre-reinforced wall material of the outer laminate layer of the side end wall(s) comprises three adjacent multi-axial fibre layers wherein the first multi-axial fibre layer is triaxial 90°/+45° resp.−45°/−45° resp.+45° fibre, the second multi-axial fibre layer is biaxial +45° resp.−45°/−45° resp.+45° fibre and the third multi-axial fibre layer is triaxial +45° resp.−45°/−45° resp.+45°/90° fibre, whereby the 90° direction is transverse to the height direction. The triaxial fibre is preferably stitched or woven. 
       Front End Wall of the Freight Container 
       [0034]    In case of the composite front end wall, due to its geometry and to the multidirectional loads during operation, a quasi-isotropic configuration for each composite facing is required. This is achieved by a fibre-reinforced wall material having a similar fibre configuration as described above, but including one or more additional multidirectional reinforcement layers. A multidirectional reinforcement layer adds an extra layer oriented in the longitudinal direction contiguous to the outer fibre layer, i.e. between the transverse fibres and the fibres oriented at an angle of +45° and −45°, or on the other side covering the outer layer. Although according to this principle, the multidirectional reinforcement layer is contiguous to the outer layer, it is preferred that a multidirectional reinforcement layer in the form of a first support fibre layer is present in between the first outer fibre layer and the first intermediate fibre layer, and a second support fibre layer in between the second outer fibre layer and the second intermediate fibre layer. 
         [0035]    The outer fibre direction, in accordance with the invention, is aligned with the shortest of the surface dimensions, which is typically the width of the container for the front end wall of a standard container. Therefore, as used herein, this means that the angle between the outer fibre direction and the height direction is 90±5°, preferably 90±3° and more preferably 90±1° and even more preferably 90°. The support fibre direction in this embodiment is aligned with the height direction, i.e. transverse to the outer fibre direction. 
         [0036]    Preferably, an angle between the outer fibre direction and the first and second intermediate fibre directions is +45° or −45°, wherein an angle between the first intermediate fibre direction and the second intermediate fibre directions is 90° (such as form +45° and −45° angles respectively with the outer fibre direction). 
         [0037]    The intermediate fibre directions are inclined with respect to the outer fibre directions. As used herein, this means that the angle between the intermediate fiber directions and the width and height direction is 45±20°, preferably 45±15°, more preferably 45±10°, even more preferably 45±5° and even more preferably 45°. 
         [0038]    Preferably, at least part of the front end wall, and preferably the entire front end wall, comprises a laminate structure comprising an outer laminate layer formed at least partly, preferably completely, by the fibre reinforced material and an inner laminate layer formed at least partly, preferably completely, by the fibre-reinforced material, the inner laminate layer is located at the inner side of the container (where the freight is to be located) and the outer laminate layer is located at the outer side of the container. As appreciated, the fibre-reinforced wall material in at least one of the laminate layers in these embodiments preferably includes the multidirectional reinforcement layers, i.e. the support fibre layers. 
         [0039]    The laminate structure preferably further comprises a core layer arranged in between, and in mechanical contact with, both laminate layers, said core layer in use supporting the laminate layers. This results in an increase of shear strength of the panel containing the fibre reinforced material. The core layer is preferably a foam layer or honeycomb as this allows to increase the stiffness with minimum weight increase. 
         [0040]    Preferably, the fibre-reinforced material comprises two adjacent multi-axial fibre layers of quadriaxial 0°/90°/+45° resp.−45°/−45° resp.+45° fibre, preferably glass fibre, in a symmetrical construction whereby one quadriaxial layer is mirrored relative to the other. More preferably, the fibre-reinforced material comprises two adjacent multi-axial fibre layers of quadriaxial 0°/90°/+45°/−45° fibre, preferably glass fibre, in a symmetrical construction whereby one quadriaxial layer is mirrored relative to the other. The 0° direction is transverse to the height direction of the container. Preferably, the quadriaxial fibre is stitched or woven. 
         [0041]    Preferably, the total areal weight of the fibres in the outer fibre direction (in g/m2) and the first intermediate fibre direction is approximately equal to or higher than the total areal weight of the fibres in the second and third intermediate outer fibre directions (in g/m2) as this will result in that the best results in terms of flexural strength and/or flexural modulus can be obtained. 
         [0042]    Preferably, the front end wall is attached to the frame by connecting the laminate structure to the top end rail and the bottom end rail by means of for example bolts, rivets, gluing or welding and preferably by gluing. 
         [0043]    In a preferred embodiment of the invention, the front end wall of the freight container comprises panels which panels comprises the laminate structure as described above. The panels may form one contiguous panel or the panels may be separate panels which are connected by a fastening means, such as a clamp, rivet, bolt, glue and/or adhesive. Preferably an adhesive is applied which adhesive preferably has a composition comprising an elastomeric polymer. More preferably, the front end wall is formed from one panel comprising the laminate structure. 
         [0000]    Core Layer of Laminate Structure of the at Least One Side Wall, the Roof, the Front End Wall and/or the at Least One Side End Wall or Roof End Part 
         [0044]    The core layer preferably comprises a polymeric material that provides a relatively light means of providing rigidity to the wall. The polymeric material is preferably a polymeric foam as this provides a low density structural material. Suitable foamed materials include metal foams, for example aluminum foam, glass foams or plastic foam, for example polyester foam, such as polyethylene terephtalate foam, polyvinyl chloride foam, polyurethane foam, polystyrene foam, polyethylene foam, polypropylene foam, a foam of an ethylene-propylene copolymer, phenolic foam, or any other plastic foam known to the person skilled in the art, may also be used. The core layer may also be made of:
       a mixed metal-plastic foam;   phenolicaramid fiber mix, such as Nomex® Paper which may be used to form a honeycomb core;   polypropylene honeycomb;   glass foam;   parabeam;   three dimensional glass matrix; and   balsa wood core (typically 100-240 kg/m3)       
 
         [0052]    Preferably the core layer comprises a polyester foam, such as polyethylene terephtalate foam, or a polyvinyl chloride foam. 
         [0053]    Fibre layers of the fibre reinforced wall material of the at least one side wall, the roof and/or the at least one side end wall 
         [0054]    Preferably, the fibre layers are embedded in a polymer matrix. 
         [0055]    Preferably, each layer is embedded into a polymer matrix comprising a thermoplastic or thermosetting resin matrix. As used herein “thermoplastic resins” are resins which can be heated and softened, cooled and hardened a number of times without undergoing a basic alteration, and “thermosetting resins” are resins which cannot be resoftened and reworked after molding, extruding or casting and which attain new, irreversible properties once set at a temperature which is critical to each resin. More preferably, the polymer matrix is a thermosetting cured resin matrix. The thermosetting resin is preferably an unsaturated polyester resin, a vinyl (ester) urethane resin, an epoxy resin or a mixture thereof. 
         [0056]    Preferably, the fibres of at least one, and preferably all, of the fibre layers have a tensile strength (measured in the axial direction (along the length of the fibres)) of at least 0.5 GPa, more preferably at least 1.2 GPa, even more preferably at least 2.5 GPa and yet even more preferably at least 3.0 GPa. Suitable fibres include aramid fibres, basalt fibres, glass fibres, fibres of high tenacity polyester and ultra-high molecular weight polyethylene fibres. Preferred fibres are glass fibres. 
         [0057]    Preferably, the fibre-reinforced wall material has a Young&#39;s modulus (E-modulus in bending) (measured in the axial direction (along the length of the fibres)) of at least 50 MPa, preferably of at least 80 MPa. 
         [0058]    The amount of fibre in the fibre-reinforced wall material is preferably at least 30 volume %, more preferably at least 40 volume % and even more preferably at least 45 volume %. The amount of fibre in the fibre-reinforced wall material is preferably at most 95 volume %, more preferably at most 90 volume % and even more preferably at most 85 volume %. 
         [0059]    In a preferred embodiment of the invention, the at least one side wall, the at least one side end wall, the front end wall, the roof and/or the roof end part of the freight container comprises panels which panels comprises the fibre reinforced wall material. The panels may form one contiguous panel or the panels may be separate panels which are connected by a fastening means, such as a clamp, rivet, bolt, glue and/or adhesive. Preferably an adhesive is applied which adhesive preferably has a composition comprising an elastomeric polymer. 
         [0060]    In a preferred embodiment, the freight container comprises a frame to which the walls are attached by means of for example bolts, rivets, gluing or welding and preferably by gluing. The frame is made out of a suitable material, preferably of steel. Said frame comprises bottom side rails, top side rails, a top end rail, a bottom end rail, front corner posts, front corner castings, a door header, a door sill, rear corner posts, rear corner castings and optionally intermediate posts. 
         [0061]    The fiber reinforced wall material can be produced by methods known to a person skilled in the art, for example by hand lay-up, continuous lamination or by vacuum infusion process. In the hand lay-up process the fiber layer mats are impregnated with resin by hand. In the continuous lamination process, fiber layer mats are automatically impregnated with resin on an impregnation table in a continuous way; the impregnated mats are then heated by for example infrared lamps so that the resin is allowed to become cured in a few minutes. In the vacuum infusion process, dry fiber layer mats are laid in a mould and then impregnated by resin under vacuum; the system is sealed by a vacuum bag and kept under vacuum until the resin has cured. The curing can occur either at room temperature or at high temperatures if a heated mould is used. 
         [0062]    The container of the present invention can for example be a nominal 10, 20, 25, 30, 40, 45, 48 or 53 foot container. Preferably, the container of the present invention is a nominal 10, 20, 30, 40 or 45 foot container. The frame is made out of a suitable material, preferably of steel. 
         [0063]    The fiber reinforced material can be produced by methods known to a person skilled in the art, for example by hand lay-up, continuous lamination or by vacuum infusion process. In the hand lay-up process the fiber layer mats are impregnated with resin by hand. In the continuous lamination process, fiber layer mats are automatically impregnated with resin on an impregnation table in a continuous way; the impregnated mats are then heated by for example infrared lamps so that the resin is allowed to become cured in a few minutes. In the vacuum infusion process, dry fiber layer mats are laid in a mould and then impregnated by resin under vacuum; the system is sealed by a vacuum bag and kept under vacuum until the resin has cured. The curing can occur either at room temperature or at high temperatures if a heated mould is used. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0064]    The invention will further be elucidated by description of some specific embodiments thereof, making reference to the attached drawings, wherein: 
           [0065]      FIG. 1  schematically shows a perspective view of a freight container, in a first embodiment according to the invention; 
           [0066]      FIG. 2  schematically shows a perspective view of a 45 foot freight container. 
           [0067]      FIG. 3  schematically shows a cross-sectional view according to the height direction of a 45 foot freight container. 
           [0068]      FIG. 4  schematically shows a cross-sectional view according to the height direction of a side wall A. 
           [0069]      FIG. 5  schematically shows a cross-sectional view according to the height direction of a side end wall. 
           [0070]      FIG. 6  schematically shows a cross-sectional view according to the height direction of the front end wall B. 
       
    
    
     DETAILED DESCRIPTION 
       [0071]    Unless stated otherwise, like reference numerals refer to like elements throughout the drawings. 
         [0072]      FIG. 1  schematically shows a perspective view of a freight container, in a first embodiment according to the invention. The freight container comprises a side wall A, a door C, a roof D, a top side rail H, a bottom side rail G, a door header K, a door sill L, a rear corner post M, a rear corner casting N. AE is the width direction, AD is the height direction and AC is the length direction. 
         [0073]      FIG. 2  schematically shows a perspective view of a 45 foot freight container comprising a side wall A, a roof D, a top side rail H, a bottom side rail G, a front end wall B, a top end rail E, a top bottom rail F, a front corner casting J and a front corner post I, side end walls P and Q, roof end parts R and S, an intermediate post U and bottom side rail reinforcements T. X is the length direction, Y is the height direction and Z is the width direction. 
         [0074]      FIG. 3  schematically shows a cross-sectional view according to the height direction of a 45 foot freight container, in which W is a scuff plate, AA is a lashening eye, V is a cross member, AG is the floor. 
         [0075]      FIG. 4  schematically shows a cross-sectional view according to the height direction of a side wall A., in which AF is the core layer;  1 ,  6 ,  7  and  12  are the outer fibre layers;  2 ,  3 ,  4 ,  5 ,  8 ,  9 ,  10  and  11  are intermediate fibre layers, whereby  2  and  8  are the fourth intermediate fibre layer;  3  and  9  are the first intermediate fibre layer;  4  and  10  are the second intermediate fibre layer; and  5  and  11  are the third intermediate fibre layer. 
         [0076]      FIG. 5  schematically shows a cross-sectional view according to the height direction of a side end wall P, in which AF is the core layer;  1 ,  6 ,  7  and  14  are the outer fibre layers;  2 ,  3 ,  4 ,  5 ,  8 ,  9 ,  10 ,  11 ,  12  and  13  are intermediate fibre layers. The fibre layers  1 ,  2 ,  3 ,  4 ,  5  and  6  are part of the inner laminate layer, whereby  2  is the fourth intermediate fibre layer;  3  is the first intermediate fibre layer;  4  is the second intermediate fibre layer; and  5  is the third intermediate fibre layer. Fibre layers  7 ,  8 ,  9 ,  10 ,  11 ,  12 ,  13  and  14  are part of the outer laminate layer, whereby  8  is the fourth intermediate fibre layer;  9  is the first intermediate fibre layer;  10  is the fifth intermediate fibre layer;  11  is the sixth intermediate fibre layer;  12  is the second intermediate fibre layer; and  13  is the third intermediate fibre layer. 
         [0077]      FIG. 6  schematically shows a cross-sectional view according to the height direction of the front end wall B, in which AF is the core layer, which is sandwiched in between an outer (layers  1  through  8 ) and inner (layers  9  through  16 ) laminate layer. Layers  1  and  9  are the first outer fibre layers, and  8  and  16  are the second outer fibre layers. Layers  2  and  10  are the first support fibre layers, and  7  and  15  are the second support fibre layers; layers  2 ,  7 ,  10  and  15  together forming the multidirectional reinforcement layers of the front end wall. Layers  3  and  11  are the first intermediate fibre layers,  4  and  12  are the second intermediate fibre layers,  5  and  13  are the third intermediate fibre layers,  6  and  14  are the fourth intermediate fibre layers, and  7  and  15  are the sixth intermediate fibre layer. 
       Experimental Part 
       [0078]    Fibre reinforced composite material are made and tested. Different numbers of layers, having a different configuration in terms of for example the fibre orientation of each layer, have been tested in the various material tests described below. 
       First Test 
     Materials of the Fibre Reinforced Composite Material 
       [0079]    The thermosetting resin used was a vinyl ester resin (Atlac 430 of DSM Composite Resins B.V.) 
         [0080]    The following glass fabrics obtained from P-D Glasseiden, Germany and all having the same sizing were applied: 
         [0000]    Multiaxial fabric with the structure −45/+45/90: 
         [0000]                                              Input material (Nominal value)                Filament diameter (μmm)   Count (tex)   Roving type               1: −45°   14   145   Oschatz       2: +45°   14   145   Oschatz       3: +90°   14   600   Oschatz       Stitching yarn        11                    
Multiaxial fabric with the structure +45/−45/90:
 
         [0000]                                              Input material (Nominal value)                Filament diameter (μmm)   Count (tex)   Roving type               1: +45°   14   145   Oschatz       2: −45°   14   145   Oschatz       3: +90°   14   600   Oschatz       Stitching yarn        11                    
Multiaxial fabric with the structure +45/90/−45:
 
         [0000]    
       
         
               
             
               
               
               
               
             
           
               
                   
               
               
                 Input material (Nominal value) 
               
             
          
           
               
                   
                 Filament diameter (μmm) 
                 Count (tex) 
                 Roving type 
               
               
                   
               
               
                 1: +45° 
                 14 
                 145 
                 Oschatz 
               
               
                 2: +90° 
                 14 
                 600 
                 Oschatz 
               
               
                 3: −45° 
                 14 
                 145 
                 Oschatz 
               
               
                 Stitching yarn 
                   
                  11 
               
               
                   
               
             
          
         
       
     
       Laminate Layer Preparation 
       [0081]    The following layup were used for the preparing the laminate layers: 
         [0000]    
       
         
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
             
           
               
                   
                   
               
               
                   
                   
                   
                 Layup 
                   
                 Layup 
                   
               
               
                   
                 Layup 1 
                 Layup 2 
                 A 
                 Layup B 
                 C 
                 Layup D 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                 Ply1 
                 1 
                 90 
                 90 
                 45 
                 45 
                 90 
                 −45 
               
               
                   
                 2 
                 −45 
                 45 
                 90 
                 90 
                 45 
                 45 
               
               
                   
                 3 
                 45 
                 −45 
                 −45 
                 −45 
                 −45 
                 90 
               
               
                 Ply2 
                 4 
                 −45 
                 45 
                 45 
                 90 
                 90 
                 90 
               
               
                   
                 5 
                 45 
                 −45 
                 90 
                 −45 
                 45 
                 −45 
               
               
                   
                 6 
                 90 
                 90 
                 −45 
                 45 
                 −45 
                 45 
               
               
                   
               
             
          
         
       
     
         [0082]    The laminate layers were prepared by vacuum infusion: the glass fibers stack was placed on a waxed glass plate; on top of the glass fibers stack nylon peel ply was used to release the flowing mesh from the laminate. On top of the peel ply a flow medium/mesh was used to help resin flow from the injection point to the vacuum suction point. The system was then sealed with a vacuum bag. They were infused at full vacuum (injection pressure of 100 mBar) with the thermosetting resin Atlac 430; the system was cured for 24 h at room temperature under vacuum and then post-cured for 1 h at 90° C. After post-curing the samples they were cut according to the geometry required in the ISO14125. 
       Testing (1 st  Test) 
       [0083]    The flexural test measures the force required to bend rectangular shaped samples under three point loading conditions. The specimen lies on a support span and the load is applied to the center by the loading nose producing three points bending at a specified rate. The parameters for this test are the support span and the speed of the loading. These parameters are based on the test specimen thickness and are defined by the ISO 14125. Flexural modulus is used as an indication of a material&#39;s stiffness when flexed. The three points bending flexural test provides values for the modulus of elasticity in bending Ef, flexural strength σf, and the flexural stress-strain response of the material. 
         [0000]    
       
         
               
             
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
             
           
               
                   
               
               
                 Test Results (1 st  TEST) 
               
             
          
           
               
                   
                   
                   
                 Comp 
                 Comp 
                 Comp 
                 Comp 
               
               
                   
                   
                   
                 Ex A 
                 Ex B 
                 Ex C 
                 Ex D 
               
               
                   
                 Ex 1 
                 Ex 2 
                 Layup 
                 Layup 
                 Layup 
                 Layup 
               
               
                   
                 Layup 1 
                 Layup 2 
                 Comp 1 
                 Comp 2 
                 Comp 3 
                 Comp 4 
               
               
                   
                   
               
             
          
           
               
                 Ply1 
                 1 
                   90° 
                   90° 
                 +45° 
                 +45° 
                   90° 
                 −45° 
               
               
                   
                 2 
                 −45° 
                 +45° 
                   90° 
                   90° 
                 +45° 
                 +45° 
               
               
                   
                 3 
                 +45° 
                 −45° 
                 −45° 
                 −45° 
                 −45° 
                   90° 
               
               
                 Ply2 
                 4 
                 −45° 
                 +45° 
                 +45° 
                   90° 
                 90 
                   90° 
               
               
                   
                 5 
                 +45° 
                 −45° 
                   90° 
                 −45° 
                 +45° 
                 −45° 
               
               
                   
                 6 
                   90° 
                   90° 
                 −45° 
                 +45° 
                 −45° 
                 +45° 
               
               
                 Flexural Strength 
                   
                 895.20 
                 877.60 
                 645.42 
                 516.63 
                 634.73 
                 470.34 
               
               
                 (MPa) 
               
               
                 Flexural Strength 
                   
                 25.88 
                 75.57 
                 34.47 
                 55.72 
                 39.17 
                 43.29 
               
               
                 standard 
               
               
                 deviation (MPa) 
               
               
                 Flexural Modulus 
                   
                 29416.00 
                 31850.33 
                 24887.17 
                 20882.67 
                 24687.33 
                 17421.40 
               
               
                 (MPa) 
               
               
                 Flexural Modulus 
                   
                 1533.64 
                 3883.56 
                 1745.74 
                 3049.99 
                 2279.88 
                 2217.18 
               
               
                 standard 
               
               
                 deviation (MPa) 
               
               
                   
               
             
          
         
       
     
         [0084]    From the above results it is clear that the highest flexural modulus and the highest flexural strength are obtained with the laminate layers with the 90° fibre layers on the outside of the laminate layer (Layup 1 &amp; Layup 2). 
       Second Test 
     Materials of the Fibre Reinforced Composite Material 
       [0085]    The thermosetting resin used was a vinyl ester resin (Atlac 430 of DSM Composite Resins B.V.) 
         [0086]    The following glass fabrics were applied: 
         [0087]    Multiaxial fabric from P-D Glasseiden, Germany with the structure −45/+45/0 
         [0000]    
       
         
               
             
               
               
               
               
             
               
               
               
               
               
             
               
               
               
               
             
           
               
                   
               
               
                 Input material (Nominal value) 
               
             
          
           
               
                   
                 Filament diameter (μm) 
                 Count (tex) 
                 Roving Type 
               
               
                   
               
             
          
           
               
                 1: 
                 −45° 
                 14 
                 145 
                 Oschatz 
               
               
                 2: 
                 +45° 
                 14 
                 145 
                 Oschatz 
               
               
                 3: 
                 0° 
                 14 
                 600 
                 Oschatz 
               
             
          
           
               
                 Stitching yarn 
                   
                  11 
                   
               
               
                   
               
             
          
         
       
     
         [0088]    Biaxial fabric from Saertex with the structure −45/+45 (800 gr/m 2 ) 
         [0089]    Biaxial fabric from Saertex with the structure −60/+60 (800 gr/m 2 ) 
         [0090]    CSM (chopped strand mat) with random structure of 800 gr/m 2    
       Laminate Layer Preparation 
       [0091]    The following layup were used for the preparing the laminate layers: 
         [0000]    
       
         
               
               
               
               
               
             
               
               
               
               
               
             
           
               
                   
               
               
                   
                 Lay-up 1 
                 Layup A 
                 Layup B 
                 Layup C 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 ply1 
                 0 
                 0 
                 0 
                 0 
               
               
                   
                 45 
                 45 
                 45 
                 45 
               
               
                   
                 −45 
                 −45 
                 −45 
                 −45 
               
               
                 ply2 
                 45 
                 / 
                 60 
                 CSM 
               
               
                   
                 −45 
                 / 
                 −60 
                 CSM 
               
               
                 ply 3 
                 45 
                 45 
                 45 
                 45 
               
               
                   
                 −45 
                 −45 
                 −45 
                 −45 
               
               
                   
                 0 
                 0 
                 0 
                 0 
               
               
                   
               
             
          
         
       
     
         [0092]    The laminate layers were prepared by vacuum infusion: the glass fibers stack was placed on a waxed glass plate; on top of the glass fibers stack nylon peel ply was used to release the flowing mesh from the laminate. On top of the peel ply a flow medium/mesh was used to help resin flow from the injection point to the vacuum suction point. The system was then sealed with a vacuum bag. They were infused at full vacuum (injection pressure of 100 mBar) with the thermosetting resin Atlac 430; the system was cured for 24 h at room temperature under vacuum and then post-cured for 1 h at 90° C. After post-curing the samples they were cut according to the geometry required in the ISO14125. 
       Testing (2 nd  Test) 
     Bending Properties: 
       [0093]    The flexural test measures the force required to bend rectangular shaped samples under three point loading conditions. The specimen lies on a support span and the load is applied to the center by the loading nose producing three points bending at a specified rate. The parameters for this test are the support span and the speed of the loading. These parameters are based on the test specimen thickness and are defined by the ISO 14125. Flexural modulus is used as an indication of a material&#39;s stiffness when flexed. The three points bending flexural test provides values for the modulus of elasticity in bending Ef, flexural strength σf, and the flexural stress-strain response of the material. 
       Inter Laminar Shear Strength (ILSS) Properties: 
       [0094]    The test is similar in nature to the three-point loading method used to determine the flexural properties of plastics and composites (ISO14125). However a smaller test span/specimen thickness ratio is adopted to increase the level of shear stress relative to the flexural stress in the test specimen to encourage interlaminar shear failure. This level of shear will act on the neutral plane of the specimen (ISO14130). 
         [0000]    
       
         
               
             
               
               
               
               
               
             
               
               
               
               
               
             
           
               
                   
               
               
                 Test Results (2 nd  TEST) 
               
             
          
           
               
                   
                   
                 Comp 
                 Comp 
                 Comp 
               
               
                   
                 Ex 1 
                 Ex A 
                 Ex B 
                 Ex C 
               
               
                   
                 Layup 1 
                 Layup A 
                 Layup B 
                 Layup C 
               
               
                   
               
             
          
           
               
                 ply1 
                 0 
                 0 
                 0 
                 0 
               
               
                   
                 45 
                 45 
                 45 
                 45 
               
               
                   
                 −45 
                 −45 
                 −45 
                 −45 
               
               
                 ply2 
                 45 
                 / 
                 60 
                 CSM 
               
               
                   
                 −45 
                 / 
                 −60 
                 CSM 
               
               
                 ply 3 
                 45 
                 45 
                 45 
                 45 
               
               
                   
                 −45 
                 −45 
                 −45 
                 −45 
               
               
                   
                 0 
                 0 
                 0 
                 0 
               
               
                 Flexural Strength (MPa) 
                 958.75 
                 508.78 
                 921.44 
                 931.40 
               
               
                 Flexural Strength 
                 59.27 
                 183.78 
                 28.11 
                 101.37 
               
               
                 standard deviation (MPa) 
                   
                   
                   
                   
               
               
                 Flexural Modulus (MPa) 
                 28711.50 
                 15610.40 
                 25613.20 
                 27320.75 
               
               
                 Flexural Modulus 
                 1974.38 
                 7041.78 
                 1944.36 
                 2031.79 
               
               
                 standard deviation (MPa) 
                   
                   
                   
                   
               
               
                 ILSS (MPa) 
                 43.47 
                 39.50 
                 43.73 
                 45.92 
               
               
                 ILSS standard 
                 3.29 
                 5.06 
                 2.73 
                 2.54 
               
               
                 deviation (MPa) 
                   
                   
                   
                   
               
               
                 Density (kg/m3) 
                 1698.14 
                 1818.44 
                 1848.40 
                 1706.35 
               
               
                   
               
             
          
         
       
     
         [0095]    From the above results it is clear that the layup with the − 45 /+ 45 ° in the middle gives the best flexural properties (Modulus and Strength), and weight reduction. CSM (chopped strand glass mat) can be used for having comparable performance however with this kind of layer in the middle plan, the weight reduction of the panel is not obtained. This kind of “fabrics” will withstand shear loads better due to the fact the fibers are randomly laid but also because the resin content in this layer is higher than in a biaxial. 
         [0096]    The present invention has been described in terms of some specific embodiments thereof. It will be appreciated that the embodiments shown in the drawings and described here and above are intended for illustrative purposes only, and are not by any manner or means intended to be restrictive on the invention. The context of the invention discussed here is merely restricted by the scope of the appended claims.