Field of invention

The present invention relates to a laminate and to a method for producing such a laminate.

Technical Background Rock or stone is widely used as building material due to its beautiful appearance and its durability. The disadvantages with such a material are that they usually are very heavy, cumbersome to handle and expensive. In recent years, synthetic materials, resembling natural rock, have been used to replace materials of rock or stone. However, such synthetic materials are seldom as beautiful or as durable as natural materials and the production costs are usually high.

In the art, light-weight boards based on a core sandwiched between facing sheets are also commonly used as building elements. These boards are often based on wood fiber materials, such as paper or paper board.

EP1714776A1 discloses a light-weight wood fiber based board comprising a core that is sandwiched between upper and lower facing sheets. The paper sheets forming the core are corrugated and stacked, so as to form flutes or channels, which flutes or channels are tilted in relation to the facing sheets. Such a construction gives rise to an increased strength, since the effective contact between the walls of the structure is increased. Summary of invention

One object with the present invention is to provide a material, which is strong and durable but yet light- weighted and easy to handle.

This object, as well as other advantages, is achieved with the laminate according to the present invention. The laminate according to the invention comprises a first layer comprising a core formed as a three dimensional body presenting a first face and a second face and a wall structure defining a plurality of channels, each channel having a longitudinal axis intersecting the first face, and a second layer

comprising rock.

The laminate of the invention is exceptionally strong and has the appearance of natural rock, but is yet light-weighted and easy to handle. The laminate can advantageously be used as building material, e.g. in- store or in home decoration.

According to one embodiment of the invention, the channels of the core intersect the first face at an angle (a) which is less than 90 degrees, preferably between 45 and 80 degrees. In this way, an exceptionally strong material is produced. The tilted channels of the core in such a structure give rise to a larger surface for the layer comprising rock to be attached to, which in turn gives a stronger material. Said surface is formed by the cut end portions of the channels forming the core.

The second layer comprising rock laminated onto said core may be made of rock.

In an alternative, preferred, embodiment the second layer may comprise a layer of rock a layer of a flexible material. Preferably, the layer of a flexible material is arranged in-between said first layer and the layer of rock. Said layer of a flexible material function as a flexible, backing material for the layer of rock and facilitates the use of very thin layers of rock. Said layer of a flexible material may, e.g., be made of fiberglass. The flexibility of the backing layer

facilitates the lamination of the second layer onto the core. Moreover, the flexibility of the backing layer facilitates decorative curves to be formed in the laminate .

The layer of rock may preferably have a thickness of between 0,5-5 mm, more preferably between 1 - 1,5 mm, such as 1 mm. The use of such a thin layer of rock involves cost savings and flexibility, but yet provides a decorative surface.

In a second aspect, the invention provides a method for manufacturing a laminate comprising the steps of providing a first layer comprising a core formed as a three dimensional body presenting a first face and a second face and a wall structure defining a plurality of channels, each channel having a longitudinal axis intersecting the first face, and laminating a second layer comprising rock onto said first face. The second layer which is laminated onto said first layer may comprise a layer of rock and a layer of a flexible material.

Detailed description of the invention

In accordance with the invention, a layer comprising rock is laminated onto a first face of a core. Said core comprises a wall structure defining a plurality of channels and said first face is formed by the end portion of the channels. The core is preferably made of wood fiber based material, such as paper or paper board. The laminate of the invention has the appearance and strength of a slab of natural rock or stone, but is light-weighted and easy to handle.

The core of the laminate may be manufactured by providing a continuous block of material presenting a plurality of channels, which block has a thickness that is greater than the desired thickness of the core and cutting from said block of material a piece that is to form the core. The block of material may be formed of a plurality of stacked corrugated sheets of wood fiber based material, such as paper or cardboard. However, other materials may also be used, such as metal sheet, polymer sheets etc. Each sheet in the stack may be adhered to the adjacent sheet by means of an adhesive, preferably a water-based adhesive. Said plurality of corrugated sheets may be interleaved with a plurality of substantially flat sheets.

A second layer comprising rock is, according to the present invention, laminated onto said core. Said second layer comprising rock may be made of rock to 100%.

Alternatively, said second layer may comprise a layer of rock and an additional layer of a flexible material, such as fiberglass. Preferably, said second layer comprising rock is pre-manufactured by laminating a flexible material onto a slab of rock, whereafter said second layer is laminated onto the core. Such a pre-manufactured second layer is easier to handle and less brittle than a thin layer of rock or stone. Thus, the backing of a flexible material facilitates the use of thin layers of rock. Moreover, the flexible material strengthens the joint between the core and the second layer comprising rock. The layer of a flexible material may have a thickness of 0,1 -1 mm, such as 0,5 mm. The rock may be any type of rock or stone, e.g.

slate or marble. The layer of rock may preferably have a thickness of 0,5 - 5 mm.

A third layer comprising rock may also be attached to a second face of the core, which second face is opposite and mutually parallel to the first face. Said third layer may, similarly to the second layer, comprise a layer of rock and a layer of a flexible material, such as fiberglass.

Edge liners may be attached to the side portions of a cut core, thus to the portions of the core that are connecting the first and the second faces of the core. Said side portions may have an extension in a plane which is perpendicular to the first and the second faces of the core. Said Edge liners may be of any materials, such as paper, laminate, particle board or rock. The edge liners may, e.g., comprise connectors of plastic material formed to connect with an edge connector of an adjacent laminate when, e.g., mounted as a wall.

The channels defining the wall structure of the core may have longitudinal axis which intersect the first face of the core at an angle which is less than 90 degrees, preferably between 45 and 85 degrees. Such a tilted structure gives rise to an increased strength. A core with a tilted wall structure may be provided by cutting a block of material so that the longitudinal axis

intersects the first face at an angle which is less than 90 degrees or at an angle between 45 and 85 degrees. This may be accomplished by provision of a block of material in the form of parallelepiped, presenting two adjacent block faces intersecting at an angle that is equal to the angle at which the longitudinal axis is to intersect the first face. Said block of material may thereafter be cut in a direction parallel with one of the block faces to form a core with a tilted wall structure. In an

alternative embodiment, a block of material presenting perpendicular block faces is cut at a cutting angle relative to one of the block faces, which cutting angle is equal to said angle at which the longitudinal axis is to intersect the first face.

Fig. la and lb show schematic perspective views of a core with a tilted wall structure. The core shown in fig. la and lb presents a first face 101 and an in relation thereto parallel, a second face 105. The faces 101, 105 are separated by a core thickness T and there are side portions 110, connecting the faces 101, 105. Fig. lb is a side view of the core 100, showing the side portion 110. Typically, the thickness T of the core 100 is between 8 - 50 mm. The core 100 is constituted of an internal wall structure defining channels 102 that are tilted in relation to the faces 101, 105, i.e. each channel 102 has a longitudinal axis 103 that intersects the faces 101, 105 at an angle a of intersection being less than 90 degrees. According to the invention, a second layer comprising rock, preferably with a thickness of between 0,5 - 5 mm, is laminated onto the first face, 101, and/or to the second face, 105, of the core.

Fig. 2a shows a laminate according to one embodiment of the invention. The laminate shown in fig. 2a comprises a first layer, 201, made of the core shown in details in fig. la and lb, and a second layer, 203, made of rock. According to this embodiment, a second layer of rock is directly laminated onto the first face of the core.

Fig. 2b shows a laminate according to another embodiment. The laminate shown in fig. 2b comprises a first layer, 201, made of the core and a second layer, 203, which second layer 203, comprises a layer of rock, 204 and an additional layer, 205, of a flexible material, such as fiberglass. As can be seen in fig. 2b, the flexible layer, 205, is attached to the first face of the core. Thus, the flexible layer, 205, is arranged in- between the core and the layer of rock.