TECHNICAL FIELD The present invention pertains in general to the field flexible band products, and a manufacturing method thereof. More particularly the invention relates to a flexible fiber product, and a manufacturing method thereof.

TECHNICAL BACKGROUND In the field of furniture manufacturing thin, flexible band products, such as edge banding, strips, veneer, etc., may constitute a way of providing a piece of furniture with pleasing aesthetics, desired surface characteristics, and to reinforce parts of furniture. Such edge banding, strips, veneer, etc., are most commonly manufactured in plastics, metal, or thin sheets of wood. Recently, there has been an increase in public and governmental awareness of environmental health, whereby the market is looking for more environmentally friendly materials than metal and plastics. Also, the manufacturing process of such products in plastics, metal, and thin sheets of wood, are step intensive, which results in high costs. Thus, cost and environmental issues results in a demand for a better material for edge banding, strips, veneer, etc.

On the contrary, fiberboard materials based on lignocelluloses, such as MDF (Medium Density Fiberboard), HDF (High Density Fiberboard), and PB (Particle Board) are well known and widely applied when there is a prerequisite that the manufactured product shall be is rigid and able to withstand strain without being deformed. Common uses of these materials are as components in furniture, such as shelves, doors, tabletops, building structures, such as flooring or wall coverage, etc. A prerequisite for these common uses is that the fiberboard material is rigid and able to withstand strain without being deformed. Within the art, a rigid fiberboard is achieved when the board, or the surface layer of the board has high density, or when the board is thick. The desired rigidity of the fiberboarcls within the art generally influences the manufacturing, which is guided towards providing rigid fiberboards. Such manufacturing typically comprises a decomposition of the starting material into particles, fibers of bundles of fibers with a suitable size. Next, the decomposed material is dried to a specified degree. Some sort of binder is applied, either before or after the drying. Then, the fibers with binder are shaped into a mat, which may comprise different layers and which may be pretreated with heat, compression, steam etc. before the final product is obtained in a continuously working press. Heat is also usually added in this processing step. Finally, the product is truncated through one or more steps into rectangular units, i.e. boards.

International application WO 96/31327 discloses a method for continuous manufacture of board from lignocelluloses, wherein a fiber mat is heated with steam and thereafter pressed to a board.

Hence, a thin, flexible band product, such as edge banding, strips, veneer, etc., , as well as manufacturing methods thereof, would be advantageous and in particular a thin, flexible band products, such as edge banding, strips, veneer, etc., and manufacturing method thereof allowing for a wider range of application or cost- effectiveness would be advantageous.

SUMMARY OF THE INVENTION

Accordingly, the present invention preferably seeks to mitigate, alleviate or eliminate one or more of the above-identified deficiencies in the art and disadvantages singly or in any combination and solves at least the above mentioned problems e.g. by providing a fiber product wherein the fiber product has a homogenous density profile across the thickness of the board and that the fibers dominantly have a relationship of lengtlrthickness of at least 20: 1, and a method for production of a fiber product, comprising decomposing the raw material into fibers, wherein the decomposing of the raw material into fibers is performed with an energy input in the in the range from 50 to 150 kWh/metric ton starting material.

Advantageous features of the invention are defined in the dependent claims.

BRIEF DESCRIPTION OF DRAWINGS

These and other aspects, features and advantages of which the invention is capable of will be apparent and elucidated from the following description of embodiments of the present invention, reference being made to the accompanying drawings, in which Fig. 1 is an illustration of the different process steps in the manufacturing method according to one embodiment;

Fig. 2 is a density profile for a fiber product within the art, such as a MDF or HDF board; and

Fig. 3 is a density profile for a fiber product according to one embodiment. DETAILED DESCRIPTION OF EMBODIMENTS Several embodiments of the present invention will be described in more detail below with reference to the accompanying drawings, in order for those skilled in the art to be able to carry out the invention. The invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. The embodiments do not limit the invention, but the invention is only limited by the appended patent claims. Furthermore, the terminology used in the detailed description of the particular embodiments illustrated in the accompanying drawings is not intended to be limiting of the invention.

As stated in the background, fiberboards within the art are rigid, and cost and environmental issues results in a demand for a better material for thin, flexible band products, such as edge banding, strips, veneer, etc. However, the present inventors have surprisingly found that it is possible to manufacture thin, flexible band products of fiber material.

In a first embodiment, according to Fig. 1, a manufacturing method 10 of such flexible band product of fiber material is disclosed. First long, slim fibers are created by decomposition/disintegration/defibration 11 of starting material. Herein, the terms decomposition, disintegration, and defibration are used interchangeably. Starting material may be wooden chips made from any kind of wood, but also non-wooden material from e.g. one-year crops, such as straw and bagasse may be used. The decomposition may for example be performed in a defibrator of known kind. A defibator is a thermo-mechanical pulping refiner, in which the pulp material, such as wood chips, is ground in an environment of steam between a rotating grinding disc and a stationary disc each with radial grooves that provides the grinding surface. Wood chips are fed into the centre and are broken down as the centrifugal force pushes them towards the circumference of the discs where the grooves are finer to produce wood fiber. However, to obtain improved flexibility the decomposition is performed with an energy input in the in the range from 50 to 150 kWh/metric ton starting material. Said energy input is lower than most processes known within the art. This gives the advantage of slimmer/longer fibers, which is one of the factors providing a flexible fiber product. According to another embodiment, the fibers that are created by the decomposition 11 are substantially or dominantly slim fibers. The term fibers both mean singular fibers and bundles of fibers. Fiber bundles are generally longer than single fibers. Depending on the starting material, the temperature and the level of moisture, different size distributions of fibers are achieved by the decomposition 11. Different kinds of starting material have different fibers, with different fiber length. The term slim fibers are fibers where the relationship between the length and the thickness is at least 20, i.e. 20:1. Fibers of lignocelluloses are mechanically decomposed from larger particles, such as wooden chips. This decomposition may take place in a rotating mill, followed by heating to different temperature levels. The decomposition process may be varied by addition of different amounts of energy. More energy added results in shorter fibers and less energy added results in longer fibers, when the rest of the process is the same.

The temperature needed for decomposition of fibers is in one embodiment achieved by adding pressure in the form of e.g. saturated steam. The added steam may then have a pressure of 5 to 11 bar.

Next, the fibers are dried 12 and mixed with a binder 13. The binder 13 may be a glue selected from the group comprising urea-formaldehyde (UF), and melamine- urea-formaldehyde (MUF). Other glues may also be used. The temperature and pressure has to be adapted to the curing temperature of glue used. The fibers are then formed into a mat 14 and compressed 15 to desired density, such as from 300 to 750 kg/m ³ and thickness of below 3 mm, such as between 1 and 3 mm. The compression 15 may be performed in a continuous double belt press, comprising perforated steel belts or steel wire screen belts, under continuous addition of hot steam 16. The steam 16 is supplied at 1 to 6 bar, whereby the mat may be heated all through to 100 to 150 ⁰ C and push out all air comprised in the mat. The compression resistance of the mat is hereby reduced significantly. This results in a solid but flexible, band shaped fiber product with homogeneous density profile. The fiber product may be rolled into a roll.

The fiber product may then be cut along the length of the fiber product 17 into narrow bands. Thereafter the bands may be rolled 18 into a roll.

Thus, according to one aspect, a roll of fiber product is disclosed. This provides easy storage and handling. Furthermore, the roll makes it possible to use the flexible product continuously or seamlessly, without the need of storing extremely large arcs of fiber product. Such use may be very advantageous in industrial applications. According to one embodiment, the fiber product is rolled 18 without being cut 17 along the length of the fiber product.

According to one embodiment, the density of the fiber product after compression 15 is homogenously 500 to 600 kg/m ³ , such as 550 kg/m ³ . When the density of the fiber product after compression 15 is homogenously 500 to 600 kg/m ³ , the strength and flexibility are such that the product conveniently may be rolled into rolls, and provide reinforcing properties to the fiber product.

In one embodiment, the fibers have a length to thickness ratio of as at least 20:1. According to one embodiment, the fibers are first dried 12 and mixed with a binder 13. According to another embodiment, the fibers are first mixed with a binder 13 and then dried 12. The binder may be added as dry powder or in a solution. The solvent of the solution may be water or any other solvent. The amount of binder added may be in the range between 0 and 15 % (weight), counted as the dry weight binder divided by the dry weight fiber.

According to one embodiment, the mat that is formed 14 from fiber and binder has a density between 30 and 50 kg/m ³ and a surface weight corresponding to the desired thickness and density of the fiber product after compression. The transporter is continuously feeding the mat in a continuously working double band press where the mat is compressed and hot steam is injected into the mat. The continuously working double band press may for example be a continuous double belt press, comprising perforated steel belts or steel wire screen belts. The injection may be performed through both bands of the press, since these bands typically comprise perforated steel belts with wire, which allow passage of steam. The distance between the bands is set to a value slightly higher than the desired thickness of the fiber pioduct produced. By injecting steam, a very fast heating of the whole fiber mat is achieved. According to one embodiment, the temperature of Ihe steam is set so that a temperature of the mat of between 100 and 150 ^° C is achieved. Most fiber products according to the state of the art arc made in presses where the rollers are made of metal. The heating in these kinds of presses are achieved through conductivity, which heats the surface area more than the middle area.

The injection gives a quick heating of the mat and makes the mat stay in the compressed state, which provides a homogeneous density across the thickness of the fiber product. Fig. 2 shows a density profile 20 of a flexible fiber product according to some embodiments of the invention, where the surface area 21 has the same density as the middle area 22. Fig. 3 shows a density profile of a state of the art fiber product, where the surface area 31 has a higher density than the middle area 32. A homogenous density, as shown in Fig. 2 makes the fiber product flexible. Accordingly, the flexible fiber product has a substantially homogeneous density profile, i.e. substantially the same density across the thickness of the product.

According to one embodiment, the present invention thus discloses a fiber product based on lignocelluloses, which is flexible. This gives several advantages compared to fiberboards within the art, which will be seen in the following.

This means that there are no layers with different density. Thus, there are no layers that may accidently be separated during the cutting process, which is an advantage compared to fiberboards within the art.

In a further embodiment, the flexible fiber product is rolled, without being deformed. This may facilitate storage. According to one embodiment, the fiber product is cut into strips before rolling. Such strips may be used for borders of, e.g. furniture. Most common within the art is to use plastic materials, metal bands or veneer as borders.

According to one embodiment, the flexible fiber product may be cut by a scissors method. This offers an advantage compared to fiber products within the art, which have to be cut according to a more energy demanding saw method, since the surface layer of conventional fiber products has a high density. Furthermore, the saw method involve material losses, i.e. waste, which is avoided by the scissors method.

Flexible fiber products are here defined as products, which can be rolled onto or into a cylinder without being plastically deformed. Flexibility may be quantitative measured as bending radius divided by board thickness. The bending radius is half the diameter of the cylinder, which is formed by the bend, measured in millimeters. The flexibility of the board products according to embodiments herein may thus be below 150, such as below 100, such as between 50 and 100, before reaching plastic deformation. A board product with a thickness of 1 mm may thus be rolled onto a cylinder with a radius of 50 to 150 mm before being plastically deformed; aboard product with a thickness of 2 mm may be rolled onto a cylinder with a radius of 100 to 300 mm before being plastically deformed; and a board product with a thickness of 3 mm may be rolled onto a cylinder with a radius of 150 to 450 mm before being plastically deformed; etc.

According to still another embodiment the fiber product according to the embodiments described above may be arranged on at least one side, such as both sides, of a distance material, such as a honeycomb material, to form a construction element, such as a sandwich structured composite or sandwich panel. In this respect a sandwich structured composite or sandwich panel is intended to be interpreted as a material with two skins on opposite sides of a lightweight core, wherein the lightweight core may be an open or closed cell structured foam, balsa wood, synthetic foam, honeycomb, etc., or other suitable distance materials.

Although the present invention has been described above with reference to specific embodiments, it is not intended to be limited to the specific form set forth herein. Rather, the invention is limited only by the accompanying claims and, other embodiments than the specific above are equally possible within the scope of these appended claims.

In the claims, the term "comprises/comprising" does not exclude the presence of other elements or steps. Furthermore, although individually listed, a plurality of means, elements or method steps may be implemented by e.g. a single unit or processor. Additionally, although individual features may be included in different claims, these may possibly advantageously be combined, and the inclusion in different claims does not imply that a combination of features is not feasible and/or advantageous. In addition, singular references do not exclude a plurality. The terms "a", "an", "'first", "second" etc do not preclude a plurality. Reference signs in the claims are provided merely as a clarifying example and shall not be construed as limiting the scope of the claims in any way.